FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
POWER SUPPLY DEVICE FOR VEHICLE;
PANASONIC CORPORATION, A CORPORATION ORGANIZED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 1006, OAZA KADOMA, KADOMA-SHI, OSAKA 571-8501, JAPAN
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

DESCRIPTION
Technical Field
The present invention relates to a vehicle power supply apparatus used in a car or suchlike vehicle.
Background Art
In recent years, hybrid cars and electric cars have been attracting attention from an environmental protection viewpoint, and their development has progressed rapidly. These cars have a configuration whereby a driving force for driving the wheels is obtained by converting direct current electric power from a power supply having a secondary battery to alternating current electric power, and driving a motor by means of alternating current electric power. Normally, a hybrid car is an electric car that uses both an engine and a motor, and in a broad sense is a kind of electric car. Therefore, for convenience, in this specification the term "electric car" is used in a broad sense that includes a hybrid car unless specifically indicated otherwise,
The apparatus described in Patent Literature 1, for example, is known as a conventional vehicle power supply apparatus used in an electric car having the above configuration as a power source. In Patent Literature 1, a regenerative system is disclosed that comprises two batteries (for example, a lithium-ion battery and a lead battery) with different nominal

voltages. In this regenerative system, a main power supply that is a general lead battery, and an auxiliary power supply that is a high-performance battery (for example, a lithium-ion battery) that features better chargeability and easier state detection than the main power supply, are connected via a DC-DC converter. A generator is connected directly to the auxiliary power supply. The main power supply has priority over the auxiliary power supply in supplying electric power to a vehicle's electrical load, and the auxiliary power supply recovers and stores regenerated electric power generated by the generator during vehicle deceleration, and is also used as a redundant power supply for the main power supply. By means of this configuration, in Patent Literature 1 provision is made for enabling regenerated energy generated during vehicle deceleration to be recovered efficiently, and for a stable voltage to be supplied to an electrical load.
Citation List Patent Literature
PTL 1
Japanese Patent Application Laid-Open No. 2004-328988
Summary of Invention Technical Problem
However, there are the following problems with the above-described conventional vehicle power supply apparatus.

Although a lithium-ion battery provides high performance, it is an expensive device, making it difficult to achieve system cost commensurate with performance. Also, with a lithium-ion battery, charge/discharge control for stable in-vehicle use is difficult, and high-performance charge/discharge control is necessary for stable in-vehicle use of a lithium-ion battery. Furthermore, since there are two kinds of batteries, state detection technology is necessary for each
Moreover, since there is no alternative but to install the lithium-ion battery and lead battery in different places in a vehicle (with, for example, the former being installed in the passenger compartment and the latter in the engine compartment), there is little freedom of design, and there are also certain limitations on reducing the installation space.
It is an object of the present invention to provide a vehicle power supply apparatus that can efficiently recover regenerated energy during vehicle deceleration, and also supply electric power to an electrical load in a stable fashion, by means of a simple and inexpensive configuration, while allowing greater freedom of design and a reduction in the installation space.
Solution to Problem
A vehicle power supply apparatus of the present invention has: a generator installed in a vehicle; a first electrical storage device that is connected to the generator and

stores electric power generated by the generator; a second electrical storage device that can be connected in series to the first electrical storage device; a DC-DC converter located between the generator and the first electrical storage device, and the electrical equipment; a switching section that switches the first electrical storage device and the second electrical storage device to a series or parallel connection state; and a control section that controls operation of the generator, the DC-DC converter, and the switching section; in which the control section controls the output voltage of the generator and the operating state of the DC-DC converter and the switching section so that regenerated electric power generated by the generator during vehicle deceleration charges the first electrical storage device and the second electrical storage device connected in series, and electric power is supplied to the electrical equipment via the DC-DC converter. It is preferable for the first electrical storage device to be a lead battery, and the second electrical storage device to be a lead battery,
Advantageous Effects of Invention
The present invention can efficiently recover . regenerated energy during vehicle deceleration, and also supply electric power to an electrical load in a stable fashion, by means of a simple and inexpensive configuration, while allowing greater freedom of design and a reduction in the installation space.

Brief Description of Drawings
FIG.l is a block diagram showing the configuration of a power supply system that includes a vehicle power supply apparatus according to Embodiment 1 of the present invention;
FIG.2 is a flowchart showing the overall operation of the power supply system in FIG.l;
FIG.3 is a flowchart showing the contents of start processing in FIG.2;
FIG.4 is a drawing showing the procedure for switching from parallel to series battery connection;
FIG.5 is a flowchart showing the contents of battery state detection processing in FIG.2;
FIG.6 is a flowchart showing the contents of control processing for regenerative electric power generation in FIG.2;
FIG.7 is a flowchart showing the contents of control processing for electric power generation in FIG.6;
FIG.8 is a flowchart showing the contents of auxiliary charge processing in FIG.2;
FIG.9 is a flowchart showing the contents of stop processing in FIG.2;
FIG.10 is a drawing showing the procedure for switching from series to parallel battery connection;
FIG.l 1 is a block diagram showing the configuration of a power supply system that includes a vehicle power supply apparatus according to Embodiment 2 of the present invention;
FIG.12 is a flowchart showing the overall operation of the

power supply system in FIG,11;
FIG.13 is a flowchart showing the contents of start processing in. FIG.12;
FIG.14 is a drawing showing the procedure for switching from singly-operated to series battery connection;
FIG.15 is a flowchart showing the contents of electrical storage device state detection processing in FIG.12;
FTG.16 is a flowchart showing the contents of control processing for regenerative electric power generation in FIG.12;
FIG.17 is a flowchart showing the contents of control processing for electric power generation in FIG.16;
FIG.18 is a flowchart showing the contents of auxiliary charge processing in FIG.12;
FIG.19 is a flowchart showing the contents of stop processing in FIG.2;
FIG.20 is a drawing showing the procedure for switching from series to singly-operated battery connection;
FIG.21 is a block diagram showing the configuration of a power supply system that includes a vehicle power supply apparatus according to Embodiment 3 of the present invention;
FIG.22 is a flowchart showing the overall operation of the power supply system in FIG.21;
FIG.23 is a flowchart showing the contents of battery state detection processing in FIG.22;
FIG.24 is a flowchart showing the contents of mode processing in FIG.22;
FIG,25 is a drawing showing the procedure for switching

from regeneration mode to driving mode;
FIG.26 is a drawing showing the procedure for switching from driving mode to regeneration mode;
FIG.27 is a flowchart showing the contents of control processing for regenerative electric power generation in FIG.22;
FIG.28 is a flowchart showing the contents of control processing for electric power generation in FIG.27; and
FIG.29 is a flowchart showing the contents of auxiliary charge processing in FIG.22.
Description of Embodiments
Now, embodiments of the present invention will be described in detail using the accompanying drawings.
(Embodiment 1) FIG.1 is a block diagram showing the configuration of a power supply system that includes a vehicle power supply apparatus according to Embodiment 1 of the present invention.
Power supply system 100 shown in FIG.l has generator
110, two batteries (first battery 120 and second battery 130), two
current sensors 122 and 132, DC-DC converter 140, four
in-vehicle relays (first in-vehicle relay 150, second in-vehicle
relay 152, third in-vehicle relay 154, and fourth in-vehicle relay
156), power supply ECU (Electronic Control Unit) 160, starter
170, starter relay 172, and in-vehicle other general load
(electrical equipment) 180. Of the above configuration
elements, two batteries 120 and 130, two current sensors 122 and 132, DC-DC converter 140, four in-vehicle relays 150 through

156, and power supply ECU 160, compose a power supply apparatus. Below, starter 170 and other general load (electrical equipment) 180 are referred to by the generic term "electrical load."
During vehicle deceleration, the rotation of engine 112 is transferred to generator 110, which generates electric power and outputs regenerated energy electric power. Generator 110 is, for example, a large-capacity (for example, 150 A class) alternator with an IC regulator that is belt-driven by engine 112 and generates a voltage specified by power supply ECU 160 (for example, a 29 V voltage). It is also possible for generator 110 to be driven (caused to generate electric power) by control of power supply ECU 160 as necessary other than during vehicle deceleration. Generator 110 is connected to first battery 120 and DC-DC converter 140.
In this embodiment, an alternator is used as generator 110, but this is not a limitation. For example, it is also possible to use a motor generator as generator 110 instead of an alternator. A motor generator is provided with the functions of both a motor and a generator in a single unit. Also, generator 110 may, for example, be connected by means of a transfer means such as a gear or belt or the like, or directly coupled, to an axle, crank axle, or the like, instead of being belt-driven by engine 112.
The two batteries (first battery 120 and second battery 130) are, for example, both general lead batteries with a nominal voltage of 12 V, generate a voltage of 12 to 13 V, and supply

electric power to electrical loads (starter 170 and general load 180). A lead battery is well established technologically, and therefore safe as a system component, and is also a comparatively inexpensive electrical storage device, enabling the system cost to be kept comparatively low. As described in detail later herein, two batteries 120 and 130 are connected in series after the engine is started, and recover and store regenerated energy generated by generator 110 during vehicle deceleration. Charging two batteries 120 and 130 connected in series makes high-voltage charging possible, and enables regenerated energy recovery to be performed efficiently. As two batteries 120 and 130 are charged with regenerated energy in this way, batteries 120 and 130 should preferably feature excellent chargeability and a large charging current. For example, a lead battery for use in idle reduction operation is particularly to be preferred because of its excellent chargeability. Also, two batteries 120 and 130 should preferably be of the same kind to enable modularization jn a single unit. Modularizing two batteries 120 and 130 enables freedom of design to be increased and the installation space to be reduced.
In this embodiment, taking low cost and simplicity of system implementation into consideration, lead batteries are used as batteries 120 and 130, but this is not a limitation. For example, it is also possible to use nickel-hydride batteries, lithium-ion batteries, or the like; as batteries 120 and 130 instead of lead batteries.
Current sensor 122 is a current sensor for measuring the

charge/discharge current of first battery 120 in order to detect the state of first battery 120, and current sensor 132 is a current sensor for measuring the charge/discharge current of second battery 130 in order to detect the state of second battery 130.
DC-DC converter 140 is a step-down DC-DC converter that converts a direct current voltage to a different, lower direct current voltage. DC-DC converter 140 can handle, for example, at least an input voltage range tip to a maximum of 29 V (= 14.5 V x 2) during battery charging and up to a maximum of 24 V (= 12 V x 2) during battery discharging. Also, DC-DC converter 140 can output a voltage in the range of 12.5 V to 14.5 V, for example. The output voltage of DC-DC converter 140 is controlled by power supply ECU 160. For example, electric power is normally supplied to electrical loads (starter 170 and general load 180) with the output voltage of DC-DC converter 140 controlled at 12.5 V, but in a mode in which only second battery 130 is charged, the output voltage of DC-DC converter 140 is controlled at 14.5 V. Also, the output voltage of DC-DC converter 140 is adjusted according to the amount of charge of batteries 120 and 130. In a mode in which only first battery 120 is charged, the generator output voltage is controlled at 14.5 V while the output voltage of DC-DC converter 140 is controlled at 12.5 V.
The four in-vehicle relays (first in-vehicle relay 150, second in-vehicle relay 152, third in-vehicle relay 154, and fourth in-vehicle relay 156) are used to switch the connection of two batteries 120 and 130 to parallel or series connection

according to whether engine 112 is in an on (started) or off (stopped) state. Four in-vehicle relays 150 through 156 repeat on/off operations according to control signals from power supply ECU 160.
First in-vehicle relay 150 is located between first battery 120 and second battery 130 (to be precise, current sensor 132 for second battery 130), Second in-vehicle relay 152 has one end connected between first battery 120 and first in-vehicle relay 150, and the other end grounded. Third in-vehicle relay 154 has one end connected between generator 110 and first battery 120 (to be precise, current sensor 122 for first battery 120), and the other end connected between DC-DC converter 140 and general load 180. Fourth in-vehicle relay 156 has one end connected between first in-vehicle relay 150 and second battery 130 (to be precise, current sensor 132 for second battery 130), and the other end connected between DC-DC converter 140 and general load 180. As described later herein, a charging circuit for batteries 120 and 130 from generator 110 and a feed circuit for electrical loads (starter 170 and general load 180) from batteries 120 and 130 are selected as appropriate by means of on/off combinations of four in-vehicle relays 150 through 156.
When two batteries 120 and 130 are being charged while connected in series, a large regenerated energy current flows from generator 110 to first in-vehicle relay 150, and therefore first in-vehicle relay 150 must be a large-capacity (for example, a 150 A class) relay. On the other hand, other in-vehicle relays 152, 154, and 156 are used to supply electric power from

batteries 120 and 130 to electrical loads (starter 170 and general load 180) and therefore do not require such a large capacity as first vehicle relay 150, and may be 40 A. class vrelays, for example.
Power supply ECU 160 performs overall control of the power supply system 100. Specifically, for example, power supply ECU 160 controls the on (closed)/off (open) state of four in-vehicle relays 150 through 156 in order to switch the connection of two batteries 120 and 130 to parallel or series connection according to whether engine 112 is in an on (started) or off (stopped) state. Also, power supply ECU 160 measures the voltage and charge/discharge current of each of batteries 1 20 and 130, and calculates the State Of Charge (SOC) of each of batteries 120 and 130 by means of current integration. furthermore, power supply ECU 160 controls generator 110 and DC-DC converter 140. In addition, power supply ECU 160 performs other controls described later herein. Details of control of power supply ECU 160 will be given later herein using flowcharts in FIG.2 onward. Power supply ECU 160 includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory) that stores a program, and RAM (Random Access Memory) for program execution (none of which is shown in the drawings).
Starter 170 is a motor used when starting (cranking) engine 112. Starter 170 is also used during driving to restart the engine from an idle reduction state when the vehicle has stopped. A current is applied to starter 170 by turning the

ignition (IG) switch (not shown), which is the engine starting switch, to the engine start position (ST position) and turning on starter relay 172.
General load 180 is, for example, a light or lamp, windshield wipers, audio equipment, a car navigation system, an air conditioner, or suchlike equipment installed in or on the vehicle.
In this embodiment, two batteries 120 and 130 are connected in series when engine 112 is running. Then, when the vehicle decelerates, batteries 120 and 130 connected in series are simultaneously charged at a high voltage with regenerated electric power generated by generator 110. In this case, for example, if one battery is charged at 14,5 V, it is possible to charge the two batteries at 29 V. Also, when regenerated electric power is generated in this way, together with charging of batteries 120 and 130 connected in series, electric power is directly supplied at 1 2 V to general load 180 from generator 110 via (and with the voltage stepped-down by) DC-DC converter 140.
./ When the vehicle is not decelerating, electric power at
12 V is supplied to general load 180 from series-connected batteries 120 and 130 via (and with the voltage stepped-down by) DC-DC converter 140.
When engine 112 is stopped, since continued operation of DC-DC converter 140 would consume electric power, operation of DC-DC converter 140 is stopped, two batteries 120 and 130 are switched to parallel connection, and a dark current is

supplied from batteries 120 and 130 to general load 180 at 12 V.
During repeated charging and discharging, the ratio of charge (that is, the State Of Charge: SOC) becomes different for two batteries 120 and 130, and therefore in this embodiment, a means of keeping the ratio of charge at or above a predetermined value for both batteries 120 and 130 is provided (auxiliary charge processing described later herein).
As described above, power supply ECU 160 switches the connection of two batteries 120 and 130 to parallel or series connection according to whether engine 112 is on or off. The on/off states of four in-vehicle relays 150 through 156 at this time are as described below.
When connecting two batteries 120 and 130 in parallel, power supply ECU 160 controls first in-vehicle relay 150 so as to be in an off (open) state, controls second in-vehicle relay 1 52 so as to be in an on (closed) state, controls third in-vebicle relay 154 so as to be in an on (closed) state, and controls fourth in-vehicle relay 156 so as to be in an on (closed) state. In this case, power supply ECU 160 stops (turns off) DC-DC converter 140.
At this time, the following circuits are formed as feed circuits from batteries 120 and 130 to general load 180: first battery 120 → third in-vehicle relay 154 → general load 180, and second battery 130 → fourth in-vehicle relay 156 → general load 180.
On the other hand, when connecting two batteries 120 and 130 in series, power supply ECU 160 controls first in-vehicle

relay 150 so as to be in an on (closed) state, controls second in-vehicle relay 152 so as to be in an o,ff (open) state, controls third in-vehicle relay 154 so as to be in an off (open) state, and controls fourth in-vehicle relay 156 so as to be in an off (open) state. In this case, power supply ECU 160 starts (turns on) DC-DC converter 140.
At this time, the following circuit is formed as a charging circuit from generator 110 to batteries 120 and 130: generator 110 → batteries 120 and 130 connected in series. Also, the following circuit is formed as a feed circuit from batteries 120 and 130 to general load 180: batteries 120 and 130 connected in series → DC-DC converter 140 → general load 180. In this case, the following circuit for direct feeding from generator 110 is also formed as a feed circuit to general load 180: generator 110 → DC-DC converter 140 → general load 180.
Next, the operation of power supply system 100 having the above configuration will be described using FIG.2 through FIG.10. Here, FIG.2 is a flowchart showing the overall operation of power supply system 100, FIG.3 is a flowchart showing the contents of start processing in FIG.2, FIG.4 is a drawing showing the procedure for switching from parallel to series battery connection, FIG.5 is a flowchart showing the contents of battery state detection processing in FIG.2, FIG.6 is a flowchart showing the contents of control processing for regenerative electric power generation in FIG.2, FIG.7 is a flowchart showing the contents of control processing for electric power generation in FIG.6, FIG.8 is a flowchart showing the

contents of auxiliary charge processing in FIG.2, FIG.9 is a flowchart showing the contents of stop processing in FIG.2, and FIG. 10 is a drawing showing the procedure for switching from series to parallel battery connection. These flowcharts are stored in a storage apparatus (for example, ROM or the like) (not shown) as control programs, and are executed by a CPU (not shown).
First, in step S 1000, power supply ECU 160 determines whether or not the ignition (IG) switch (not shown) has been switched on. Specifically, if the ignition switch has been turned to the engine start position (ST position), power supply ECU 160 determines that the ignition switch has been switched on. If it is determined that the ignition switch has been switched on (S1000: YES), the processing flow proceeds to step S2000, whereas if it is determined that the ignition switch has not been switched on (S1000: NO), the program goes to a standby state.
In step S2000, power supply ECU 160 performs start processing. The contents of this start processing are as shown in the flowchart in FIG.3.
First, in step S2100, power supply ECU 160 starts engine 112. Specifically, power supply ECU 160 turns on starter relay 172 and applies a current to starter 170 from batteries 120 and 130 connected in parallel. By this means, engine 112 starts.
Then, in step S2200, power supply ECU 160 starts (turns on) DC-DC converter 140.

Next, in step S2300, power supply ECU 160 controls four in-vehicle relays 150 through 156 to switch the connection of two batteries 120 and 130 from parallel to series connection. The actual switching procedure at this time is as shown in FIG.4. By means of this switching procedure, the connection of two batteries 120 and 130 can be safely and surely switched from parallel to series connection. Following this, the control procedure returns to the main flowchart in FIG.2.
Next, in step S3000, power supply ECU 160 performs battery state detection processing. The contents of this battery state detection processing are as shown in the flowchart in FIG.5.
First, in step S3100, power supply ECU 160 measures the battery. Specifically, power supply ECU 160 measures the current (I1) and voltage (Vi) of first battery 120, and also measures the current (I2) and voltage (V2) of second battery 130. The current (I1) of first battery 120 is detected by current sensor 122, and the current (I2) of second battery 130 is detected by current sensor 132.
Then, in step S3200, power supply ECU 160 calculates the battery state. Specifically, for example, power supply ECU 160 integrates a detection result (charge/discharge current value) from current sensor 122 and calculates the SOC of first battery 120 (hereinafter referred to as "SOC1"), and integrates a detection result (charge/discharge current value) from current sensor 132 and calculates the SOC of second battery 130 (hereinafter referred to as "SOC2"). In this way, the SOC of a battery can be calculated by integrating a current flowing into

the battery and a current flowing out of the battery (so-called Coulomb count processing). The SOC calculation method for batteries 120 and 130 is not limited to Coulomb count processing, and any other known method can also be used. Following this, the control procedure returns to the main flowchart in FIG.2.
Next, in step S4000, power supply ECU 160 perforins regenerative electric power generation control. The contents of this regenerative electric power generation control are as shown in the flowchart in F1G.6,
First, in step S4100, power supply ECU 160 determines whether or not the vehicle speed is greater than or equal to a predetermined value (for example, 10 km/h) and the vehicle is decelerating. Here, determining whether or not the vehicle speed is greater than or equal to a predetermined value is to determine whether or not the current vehicle speed is suitable for regenerative electric power generation — that is, whether or not kinetic energy necessary for regenerative electric power generation is available in the vehicle. Regenerated energy is obtained by converting kinetic energy of the vehicle to electrical energy. Since a low vehicle speed leads to low kinetic energy, a regenerated energy amount cannot be expected. Whether or not the vehicle is decelerating is determined, for example, based on vehicle speed information, or based on the degree of brake pedal depression (whether the brake pedal is being depressed). If it is determined that the vehicle speed is greater than or equal to the predetermined value (1() km/h) and the vehicle is decelerating (S4100: YES), the processing flow proceeds to step

S4200, and if this is not the case — that is, if the vehicle speed is less than the predetermined value (10 km/h) or the vehicle is not decelerating (that is, the vehicle is accelerating, traveling at a constant speed, idling, or the like) — (S4100: NO), the main flowchart in FIG.2 is returned to immediately.
In step S4200, power supply ECU 160 performs electric power generation control on generator 110. In this electric power generation control, voltages V1 and V2 of batteries 120 and 130 respectively are controlled so as not to exceed a predetermined value (for example, 14.5 V). The reason for this is that a lead battery will deteriorate more quickly if an excessively high voltage is applied to it. Also, in this electric power generation control, electric power generation by generator 110 is stopped if the SOC of at least one of two batteries 120 and 130 reaches 100% or above. The reason for this is that a lead battery will deteriorate more quickly if excessively charged. The contents of this electric power generation control are as shown in the flowchart in FIG.7.
: First, in step S4210, power supply ECU 160 determines whether or not the state of charge of first battery 120 (SOC1) is greater than or equal to 100%, or the state of charge of second battery 130 (SOC2) is greater than or equal to 100%, If it is determined that the state of charge of first battery 120 (SOC1) is greater than or equal to 100% or the state of charge of second battery 130 (SOC2) is greater than or equal to 100% — that is, that the SOC of at least one of two batteries 120 and 130 is greater than or equal to 100% — (S4210: YES), the processing

flow proceeds to step S4220, and if this is not the case — that is, if the SOCs of both batteries 120 and 130 are less than 100% — (S4210: NO), the processing flow proceeds to step S4230.
In step S4220, power supply ECU 160 stops electric power generation by generator 110. Following this, the control procedure returns to the main flowchart in FIG,2.
On the other hand, in step S4230, power supply ECU 160 further determines whether or not the voltage (Vi) of first battery 120 exceeds a predetermined value (for example, 14.5 V), or the voltage (V2) of second battery 130 exceeds a predetermined value (for example, 14.5 V). If it is determined that the voltage (V[) of first battery 120 exceeds the predetermined value (14.5 V) or the voltage (V2) of second battery 130 exceeds the predetermined value (14.5 V) — that is, that the voltage of at least one of two batteries 120 and 130 exceeds the predetermined value (14.5 V) — (S4230: YES), the processing flow proceeds to step S4240, and if this is not the case — that is, if voltages V1 and V2 of batteries 120 and 130 respectively are both less than or equal to the predetermined value (14.5 V) — (S4230: NO), the processing flow proceeds to step S4250.
In step S4240, power supply ECU 160 sets an output instruction value to generator 110 lower than a target value (for example, 29 V). Following this, the control procedure returns to the main flowchart in FIG.2.
On the other hand, in step S425 0, power supply ECU 160 sets an output instruction value to generator 110 to the target

value (29 V), Following this, the control procedure returns to the main flowchart in FIG.2.
The control contents of step S4240 are not limited to the above example. In this case, any kind of control method may be used as long as a battery voltage exceeding the predetermined value (14.5 V) can be lowered to the predetermined value (14.5 V) or below. For example, it is also possible to use so-called PID control for such control that a battery voltage exceeding the predetermined value (14.5 V) is forced to converge at the predetermined value (14.5 V).
Next, in step S5000, power supply ECU 160 performs auxiliary charge processing. This auxiliary charge processing is control for preventing the difference between the SOCs of two batteries 120 and 130 from becoming large, or for performing charge if the SOC value of battery 120 or 130 becomes less than or equal to a predetermined value. The reason for the former case is that charge/discharge characteristics in a series connection state deteriorate if the difference between the SOCs of two batteries 120 and 130 becomes large, and the reason for the latter case is that a lead battery deteriorates more quickly if the SOC falls. The contents of this auxiliary charge processing are as shown in the flowchart in FIG.8.
First, in step S5100, power supply ECU 160 determines whether or not state of charge of first battery 120 (SOC1) is less than predetermined value A and state of charge of second battery 130 (SOC2) is less than predetermined value A, where predetermined value A is a suitable value in the range of 80 to

90%, for example. If it is determined that state of charge of first battery 120 (SOC1) is less than predetermined value A and state of charge of second battery 130 (SOC2) is less than predetermined value A — that , that the SOCs of both batteries 120 and 130 are less than predetermined value A — (S5100: YES), the processing flow proceeds to step S5200, and if this is not the case (S5100: NO), the processing flow proceeds to step S5300.
In step S5200, power supply ECU 160 simultaneously chrages two batteries 120 and 130 in series. specification, in this case, power supply ECU 160 keeps the connection state of two batteries 120 and 130 at Series connection as long as the vehicle is traveling. Auxiliary charging at this time is immediately necessary for two batteries 120 and 130 in order to avoid battery deterioration, regardless of whether or not the vehicle is decelerating. Consequently, when the vehicle is decelerating, this opportunity is used to charge batteries 120 and 130 with regenerated energy, whereas when the vehicle is not decelerating — that is, when the vehicle is traveling — generator 110 is forcibly made to generate electric power at 29 V and charge batteries 120 and 130. By this means, regenerated energy generated by generator 110 during vehicle deceleration or electric power forcibly generated by generator 110 when the vehicle is traveling simultaneously charges batteries 120 and 130 in series (that is, the following charging circuit is used: generator 110 → batteries 12() and 130 connected in series). This kind of simultaneous charging is continued until at least one of the SOCs of two batteries 120 and 130 reaches

predetermined value A or above. During charging, as described above, electric power is directly supplied from generator 110 to general load 180 via (and with the voltage stepped-down by) DC-DC converter 140 (that is, using the following feed circuit: generator 110 → DC-DC converter 140→ general load 180). At this time, if DC-DC converter 140 is in a stopped (off) state, power supply ECU 160 starts (turns on) DC-DC converter 140.
On the other hand, in step S5300, power supply ECU 160 further determines whether or not only state of charge of first battery 120 (SOC1) is less than predetermined value A. If it is determined that only state of charge of first battery 120 (SOC1) is less than predetermined value A (S5300: YES), the processing flow proceeds to step S5400, and if this is not the case (S5300: NO), the processing flow proceeds to step S5500.
In step S5400, power supply ECU 160 charges only first battery 120. Specifically, in this case, at the start of charging, power supply ECU 160 switches the connection state of batteries 120 and 130 from series to parallel, and then places fourth in-vehicle relay 156 in an off (open) state. By this means, first in-vehicle relay 150 is placed in an off (open) state, second in-vehicle relay 152 in an on (closed) state, third in-vehicle relay 154 in an on (closed) state, and fourth in-vehicle relay 156 in an off (open) state. Also, at the time of this switching, power supply ECU 160 stops (turns off) DC-DC converter 140. First battery 120 is charged with electric power at, for example, 14.5 V generated from generator 110 controlled by power supply ECU 160 (that is, the following charging circuit is used:

generator 110 → first battery 120). During charging of first battery 120, electric power is supplied directly from generator 110 to general load 180 via third in-vehicle relay 154 (that is, the following feed circuit is used; generator 110 → third in-vehicle relay 154 → general load 180), When charging of first battery 120 is completed, power supply ECU 160 first places fourth in-vehicle relay 156 in an on (closed) state and returns the connection state of batteries 120 and 130 to parallel connection, and then further returns the connection state of batteries 120 and 130 to series connection, Also, at the time of this switching, power supply ECU 160 starts (turns on) DC-DC converter 140.
On the other hand, in step S5500, power supply ECU 160
further determines whether or not only state of charge of second
battery 130 (SOC2) is less than predetermined value A. If it is
determined that only state of charge of second battery 130
(SOC2) is less than predetermined value A (S5500: YES), the
processing flow proceeds to step S5600, and if this is not the
case (S5500: NO), the processing flow proceeds to step S5700.
In step S5600, power supply ECU 160 charges only
second battery 130. Specifically, in this case, at the start of charging, power supply ECU 160 switches the connection state of batteries 120 and 130 from series to parallel, and then places second in-vehicle relay 152 in an off (open) state. By this means, first in-vehicle relay 150 is placed in an off (open) state, second in-vehicle relay 152 in an off (open) state, third in-vehicle relay 154 in an on (closed) state, and fourth in-vehicle relay 156 in an on (closed) state. Also, at the time of

this switching, power supply ECU 160 stops (turns off) DC-DC converter 140. Second battery 130 is charged with electric power at, for example, 14.5 V generated from generator 110 controlled by power supply ECU 160 (that is, the following charging circuit is used: generator 110→ third in-vehicle relay 154 → fourth in-vehicle relay 156 → second battery 130). During charging of second battery 130, electric power is supplied directly from generator 110 to general load 180 via third in-vehicle relay 154 (that is, the following feed circuit is used: generator 11 0 → third in-vehicle relay 15 4 → general load 180). When charging of second battery 130 is completed, power supply ECU 160 first places second in-vehicle relay 152 in an on (closed) state and returns the connection state of batteries 120 and 130 to parallel connection, and then further returns the connection state of batteries 120 and 130 to series connection. Also, at the time of this switching, power supply ECU 160 starts (turns on) DC-DC converter 140.
On the other hand, in step S5700, power supply ECU 160 further determines whether or not the difference in SOCs between two batteries 120 and 130 is greater than predetermined value a. With the circuit configuration shown in FIG, 1, normally second battery 130 tends to cause a larger amount of discharge than that of first battery 120 and have a small SOC. Thus, here, a value obtained by subtracting SOC2 from SOC1 is found as the difference in SOCs between two batteries 120 and 130. Also, predetermined value a is, for example, 2%. If it is determined that the difference in SOCs between two batteries 120

and 130 (SOC1-SOC2) is greater than predetermined value a (S5700: YES), the processing flow proceeds to step S5800, and if this is not the case — that is, if the difference in SOCs between two batteries 120 and 130 (SOC1-SOC2) is less than or equal to predetermined value a — (S5700: NO), the processing flow immediately returns to the main flowchart in FIG.2.
In step S5800, in order to lower the difference in SOCs between two batteries 120 and 130 to predetermined value a or below, power supply ECU 160 performs discharging from only first battery 120 having the larger SOC. Specifically, in this case, power supply ECU 160 switches the connection state of batteries 120 and 130 from series to parallel, and then places fourth in-vehicle relay 156 in an off (open) state. By this means, first in-vehicle relay 150 is placed in an off (open) state, second in-vehicle relay 152 in an on (closed) state, third in-vehicle relay 154 in an on (closed) state, and fourth in-vehicle relay 156 in an off (open) state. Also, during this time, power supply ECU 160 temporarily stops (turns off) DC-DC converter 140. At this time, first battery 120 discharges by supplying electric power to general load 180 via third in-vehicle relay 154 (that is, the following feed circuit is used: first battery 120 → third in-vehicle relay 154 → general load 180). During this time, second battery 130 does not perform charging or discharging. When the difference in SOCs between two batteries 120 and 130 reaches predetermined value a or below, power supply ECU 160 starts (turns on) DC-DC converter 140, then first places fourth in-vehicle relay 156 in an on (closed)

state and returns the connection state of batteries 120 and 130 to parallel connection, and then further returns the connection state of batteries 120 and 130 to series connection.
In step S6000, power supply ECU 160 determines whether or not the ignition (IG) switch (not shown) has been switched off. If it is determined that the ignition switch has been switched off (S6000; YES), the processing flow proceeds to step S7000, whereas if it is determined that the ignition switch has not been switched off (S6000'. NO), the processing flow returns to step S3000.
In step S7000, power supply ECU 160 performs stop processing. The contents of this stop processing are as shown in the flowchart in FIG.9.
First, in step S7100, power supply ECU 160 controls four in-vehicle relays 150 through 156 and switches the connection of two batteries 120 and 130 from series to parallel connection. The actual switching procedure at this time is as shown in FIG.10. By means of this switching procedure, the connection of two batteries 120 and 130 can be safely and surely switched from series to parallel connection.
Then, in step S7200, power supply ECU 160 stops (turns off) DC-DC converter 140.
In step S7300, power supply ECU 160 stops engine 112. Specifically, power supply ECU 160 outputs a control signal that stops engine 112 to an engine ECU (not shown) that controls engine operation. By this means, engine 112 stops.
An idle reduction function has not been considered in

the above series of control operations, but it is of course possible for this to be considered. Specifically, for example, the connection of two batteries 120 and 130 may be switched from series to parallel connection each time engine 112 is stopped due to an idle reduction operation.
Thus, according to this embodiment, when a vehicle decelerates and generator 110 outputs regenerated energy, batteries 120 and 130 are connected in series, and regenerated energy generated by generator 110 simultaneously charges series-connected batteries 120 and 130 at a high voltage. Therefore, regenerated energy generated during vehicle deceleration can be recovered efficiently by means of a simple and inexpensive configuration.
Also, when regenerated energy is being generated, together with charging of batteries 120 and 130 connected in series, electric power at 12 V is supplied directly from generator 110 to general load 180 via DC-DC converter 140. When the vehicle is not decelerating — that is, when generator 110 is not outputting regenerated energy —electric power at 12 V is supplied to general load 180 via DC-DC converter 140 from series-connected batteries 120 and 130 storing regenerated energy. Furthermore, after engine 112 stops, the operation of DC-DC converter 140 is stopped, the connection of two batteries 120 and 130 are switched to parallel connection, and a dark current is sent at 12 V to general load 180 from batteries 120 and 130. Therefore, electric power can be supplied to general load 180 in a stable fashion.

Also, when technologically well-established and comparatively inexpensive lead batteries are used as two batteries 120 and 130, lower system cost and higher system safety can be secured than when other high-performance batteries (for example, lithium-ion batteries, nickel-hydride batteries, or the like) are used.
Moreover, the same kind of battery (a lead battery) is used for two batteries 120 and 130, enabling freedom of design to be increased and the installation space to be reduced by modularizing two batteries 120 and 130.
Also, if the ratios of charge (SOCs) of two batteries 120 and 130 are less than or equal to a predetermined value, or the difference in the ratios of charge (SOCs) is greater than or equal to a predetermined value, the ratios of charge of both batteries 120 and 130 are controlled to be greater than or equal to the predetermined value (auxiliary charge processing), enabling an increase in the rate of battery deterioration to be suppressed.
In this embodiment, the number of batteries used is two, but there is no particular limitation on the number of batteries in the present invention, and it is also possible to use a configuration in which three or more batteries can be switched to a series or parallel connection state.
(Embodiment 2)
FIG. 11 is a block diagram showing the configuration of a
power supply system that includes a vehicle power supply
apparatus according to Embodiment 2 of the present invention.
Configuration parts in power supply system 100A shown in

FIG.11 common to power supply system 100 shown in FIG.l are assigned the same reference signs, and detailed descriptions thereof are omitted.
Power supply system 100A shown in FIG,11 has
generator 110, Electric Double Layer Capacitor (EDLC) 120A,
second battery 130, current sensor 132, DC-DC converter 140,
two in-vehicle relays (first in-vehicle relay 150 and second
in-vehicle relay 152), power supply ECU (Electronic Control
Unit) 160A, starter 170, starter relay 172, and in-vehicle other
general load (electrical equipment) 180. Of the above
configuration elements, EDLC 120A, second battery 130, current sensor 132, DC-DC converter 140, two in-vehicle relays 150 and 152, and power supply ECU 160A, compose a power supply apparatus.
, Generator 110 is connected to EDLC 120A and DC-DC converter 140.
EDLC 120A is a storage device that is capable of charge/discharge of a larger current than a general secondary battery and features excellent charge/discharge cycle life. An EDLC has, for example, a maximum rating of 2.8 V per cell. Thus, in this embodiment, for example, a maximum rating of 14 V is obtained with an EDLC module including five cells in series. When connected in series to second battery 130, EDLC 120A supplies electric power to general load 180 via (and with the voltage stepped-down by) DC-DC converter 140 together with second battery 130. Depending on the output capacity of generator 110 and input voltage range of DC-DC converter 140,

the number of cells composing EDLC 120A may be increased to raise the maximum rating. Raising the maximum rating enables regenerated energy to be recovered efficiently at a higher voltage.
The two in-vehicle relays (first in-vehicle relay 150 and second in-vehicle relay 152) are used to switch the connection of EDLC 120A and second battery 130 to parallel or series connection according to whether engine 112 is in an on (started) or off (stopped) state, Here, connecting EDLC 120A and second battery 130 in "parallel" means, to be precise, a state in which it is possible for only second battery 130 to be used, and this is also referred to as a "singly-operated battery" state. Two in-vehicle relays 150 and 152 repeat on/off operations according to control signals from power supply ECU 160A.
First in-vehicle relay 150 is located between EDLC 120A and second battery 130 (to be precise, current sensor 132 for second battery 130). Second in-vehicle relay 152 has one end connected between first in-vehicle relay 150 and second battery 130 (to be precise, current sensor 132 for second battery 130), and the other end connected between DC-DC converter 140 and general load 180. As described later herein, a charging circuit for EDLC 120A and second battery 130 from generator 110 and a feed circuit for electrical loads (starter 170 and general load 180) from EDLC 120A and second battery 130 are selected as appropriate by means of on/off combinations of two in-vehicle relays 150 and 152.
When EDLC 120A and second battery 130 are charged

while connected in series, a large regenerated energy current flows from generator 110 to first in-vehicle relay 150, and therefore first in-vehicle relay 150 must be a large-capacity (for example, a 150 A class) relay. On the other hand, second in-vehicle relay 152 is used to supply electric power from only second battery 130 to electrical loads (starter 170 and general load 180), therefore does not require such a large capacity as first in-vehicle relay 150, and may be a 40 A class relay, for example,
Power supply ECU 160A performs overall control of power supply system 100A, Specifically, for example, power supply ECU 160A controls the on (closed)/off (open) state of two in-vehicle relays 150 and 152 in order to switch the connection of EDLC 120A and second battery 130 to parallel (singly-operated battery) or series connection according to whether engine 112 is in an on (started) or off (stopped) state. Also, power supply ECU 160A measures voltage VB and charge/discharge current IB of second battery 130, and calculates the State Of Charge (SOC) of second battery 130 by means of current integration. The state of charge (SOC) of EDLC 120A is easily detected by simply measuring voltage VE of EDLC 120A. Furthermore, power supply ECU 160A controls generator 110 and DC-DC converter 140. In addition, power supply ECU 160A performs other controls described later herein. Details of control of power supply ECU 160A will be given later herein using flowcharts in FIG. 12 onward. Power supply ECU 160A includes, for example, a CPU (Central Processing Unit), ROM

(Read Only Memory) that stores a program, and RAM (Random Access Memory) for program execution (none of which is shown in the drawings).
In this embodiment, EDLC 120A and second battery 130 are connected in series when engine 112 is running. Then, when the vehicle decelerates, EDLC 120A and second battery 130 connected in series are simultaneously charged at a high voltage with regenerated electric power generated by generator 110, In this case, for example, since it is possible to charge second battery 130 at 14.5 V and EDLC 120A at 14 V (in a 5-ceil series configuration), charging at 28.5 V is possible in total. Also, when regenerated electric power is generated in this way, together with charging of EDLC 120A and second battery 130 connected in series, electric power is directly supplied at 12 V to general load 180 from generator 110 via (and with the voltage stepped-down by) DC-DC converter 140.
When the vehicle is not decelerating, electric power at 12 V is supplied to general load 180 from series-connected EDLC 120A and second battery 130 via (and with the voltage stepped-down by) DC-DC converter 140.
\ ' When engine 112 is stopped, since continued operation
of DC-DC converter 140 would consume electric power, operation of DC-DC converter 140 is stopped, EDLC 120A and second battery 130 are switched to parallel (singly-operated battery) connection, and a dark current is supplied from only second battery 130 to general load 180 at 12 V.
As described above, power supply ECU 160A switches

the connection of EDLC 120A and second battery 130 to parallel
(singly-operated battery) or series connection according to
whether engine 112 is on or off. The on/off states of two
in-vehicle relays 150 and 152 at this time are as described below.
When connecting EDLC 120A and second battery 130 in
parallel (singly-operated battery mode), power supply ECU 160A controls first in-vehicle relay 150 so as to be in an off (open) state, and controls second in-vehicle relay 152 so as to be in an on (closed) state. In this case, power supply ECU 160A stops (turns off) DC-DC converter 140.
At this time, the following circuit is formed as a feed circuit from second battery 130 to general load 180: second battery 130 → second in-vehicle relay 152 → general load 180.
On the other hand, when connecting EDLC 120A and second battery 130 in series, power supply ECU 160A controls . first in-vehicle relay 150 so as to be in an on (closed) state, and controls second in-vehicle relay 152 so as to be in an off (open) state. In this case, power supply ECU 160A starts (turns on) DC-DC converter 140.
At this time, the following circuit is formed as a charging circuit from generator 110 to EDLC 120A and second battery 130: generator 110 → EDLC 120A and second battery 130 connected in series. Also, the following circuit is formed as a feed circuit from EDLC 120A and second battery 130 to general load 180: EDLC 120A and second battery 130 connected in series → DC-DC converter 140 → general load 180. In this case, the following circuit for direct feeding from generator 110 is also

formed as a feed circuit to general load 180: generator 110 → DC-DC converter 140 → general load 180.
Next, the operation of power supply system 100A having the above configuration will be described using FIG.12 through FIG,20. Here, FIG.12 is a flowchart showing the overall operation of power supply system 100A, FIG.13 is a flowchart showing the contents of start processing in FIG.1.2, FIG.14 is a drawing showing the procedure for switching from singly-operated battery to series connection, FIG.15 is a flowchart showing the contents of electrical storage device state detection processing in FIG.12, FIG,16 is a flowchart showing the contents of control processing for regenerative electric power generation in FIG.12, FIG. 17 is a flowchart showing the contents of control processing for electric power generation in FIG.16, FIG. 1 8 is a flowchart showing the contents of auxiliary charge processing in FIG.12, FIG.19 is a flowchart showing the contents of stop processing in FIG.12, and FIG.20 is a drawing showing the procedure for switching from series to singly-operated battery connection. These flowcharts are stored in a storage apparatus (for example, ROM or the like) (not shown) as control programs, and are executed by a CPU (not shown).
First, in step S1000A, power supply ECU 160A determines whether or not the ignition (IG) switch (not shown) has been switched on. Specifically, if the ignition switch has been turned to the engine start position (ST position), power supply ECU 160A determines that the ignition switch has been

switched on. If it is determined that the ignition switch has been switched on (S1000A: YES), the processing flow proceeds to step S2000A, whereas if it is determined that the ignition switch has not been switched on (S1000A: NO), the program goes to a standby state.
In step S2000A, power supply ECU 160A performs start processing. The contents of this start processing are as shown in the flowchart in FIG. 13.
First, in step S2100A, power supply ECU 160A starts engine 112. Specifically, power supply ECU 160A turns on starter relay 172 and applies a current to starter 170 from second battery 130 in parallel (singly-operated battery) connection. By this means, engine 112 starts.
Then, in step S2200A, power supply ECU 160A starts (turns on) DC-DC converter 140.
Next, in step S2300A, power supply ECU 160A controls two in-vehicle relays 150 and 152 to switch the connection of EDLC 120A and second battery 130 from parallel (singly-operated battery) to series connection. The actual switching procedure at this time is as shown in FIG.14. By means of this switching procedure, the connection of EDLC 120A and second battery 130 can be safely and surely switched from parallel (singly-operated battery) to series connection. Following this, the control procedure returns to the main flowchart in FIG, I 2.
In step S3000A, power supply ECU 160A performs electrical storage device state detection processing. The

contents of this electrical storage device state detection processing are as shown in the flowchart in FIG.15.
First, in step S3100A, power supply ECU 160A measures the battery. Specifically, power supply ECU 160A measures current IB and voltage VB of second battery 130. Current IB of second battery 130 is detected by current sensor 132.
Then, in step S3200A, power supply ECU 160A calculates the battery state. Specifically, for example, power-supply ECU 160A integrates a detection result (charge/discharge current value IB) from current sensor 132 and calculates the SOC of second battery 130. In this way, the SOC of a battery can be calculated by integrating a current flowing into the battery and a current flowing out of the battery (so-called Coulomb count processing). The SOC calculation method for second battery 130 is not limited to Coulomb count processing, and any other known method can also be used.
Next, in step S3300A, power supply ECU 160A measures the voltage of the EDLC. Specifically, power supply ECU 160A measures voltage VE of EDLC 120A. The SOC of an EDLC generally depends on the voltage of the EDLC. For example, if the maximum voltage of the EDLC is 14 V, the SOC is 0% when the voltage is 0 V, and the SOC is 100% when the voltage is 14 V. Normally, the SOC is not calculated for an EDLC, and only the voltage is monitored (that is, it can be considered that the amount of charge in an EDLC = voltage). Following this, the control procedure returns to the main flowchart in FIG.12.
Next, in step S4000A, power supply ECU 160A performs

regenerative electric power generation control. The contents of this regenerative electric power generation control are as shown in the flowchart in FIG. 16.
First, in step S4100A, power supply ECU 160A determines whether or not the vehicle speed is greater than or equal to a predetermined value (for example, 10 km/h) and the vehicle is decelerating. Here, determining whether or not the vehicle speed is greater than or equal to a predetermined value is to determine whether or not the current vehicle speed is suitable for regenerative electric power generation — that is, whether or not kinetic energy necessary for regenerative electric power generation is available in the vehicle. Regenerated energy is obtained by converting kinetic energy of the vehicle to electrical energy. Since a low vehicle speed leads to low kinetic energy, a regenerated energy amount cannot be expected. Whether or not the vehicle is decelerating is determined, for example, based on vehicle speed information, or based on the degree of brake pedal depression (whether the brake pedal is being depressed). If it is determined that the vehicle speed is greater than or equal to the predetermined value (10 km/h) and the vehicle is decelerating (S4100A: YES), the processing flow proceeds to step S4200A, and if this is not the case — that is, if the vehicle speed is less than the predetermined value (10 km/h) or the vehicle is not decelerating (that is, the vehicle is accelerating, traveling at a constant speed, idling, or the like) — (S4100A: NO), the main flowchart in FIG.12 is returned to immediately.
In step S4200A, power supply ECU 160A performs

electric power generation control on generator 110. In this electric power generation control, voltage VB of second battery 130 is controlled so as not to exceed a predetermined value (for example, 14.5 V). The reason for this is that a lead battery will deteriorate more quickly if an excessively high voltage is applied to it. Also, in this electric power generation control, electric power generation by generator 1 10 is stopped if voltage VE ofEDLC 120A reaches a predetermined value (for example, 14 V) or above, or if the SOC of second battery 130 reaches 100% or above. The reason for this is that an EDLC and a lead battery will deteriorate more quickly if excessively charged. The contents of this electric power generation control are as shown in the flowchart in FIG.17.
First, in step S42I0A, power supply ECU 160A determines whether or not voltage Ve of EDLC 120A is greater than or equal to the maximum voltage (14 V) (that is, the SOC of EDLC 120A is greater than or equal to 100%), or the state of charge (SOC) of second battery 130 is greater than or equal to 100%. If it is determined that voltage VE of EDLC 120A is greater than or equal to the maximum voltage (14 V) or the state of charge (SOC) of second battery 130 is greater than or equal to 100% — that is, that the SOC of at least one of EDLC 120A and second battery 130 is greater than or equal to 100% — (S4210A: YES), the processing flow proceeds to step S4220A, and if this is not the case — that is, if the SOCs of both EDLC 120A and second battery 130 are less than 100% — (S4210A: NO), the processing flow proceeds to step S4230A.

In step S4220A, power supply ECU 160A stops electric power generation by generator 110. Poltowing this, the control procedure returns to the main flowchart in FIG.12.
On the other hand, in step S4230A, power supply ECU 160A further determines whether or n applies a charging voltage, the charging voltage for EDLC 120A and second battery 130 connected in series becomes 0 V + 14.5 V = 14.5 V. Then, as electric power is stored in EDLC 120A from this state, only the voltage of EDLC 120A continues to rise. Therefore, so-called PID control should preferably he used for control in step S4240A. Following this, the control procedure returns to

the main flowchart in FIG.12.
The control contents of step S4240A are not limited to the above example. In this case, any kind of control method may be used as long as the voltage of second battery 130 exceeding the predetermined value (14.5 V) can be lowered to the predetermined value (14.5 V) or below, For example, it is also possible to use so-called PID control for such control that the voltage of second battery 130 exceeding the predetermined value (14.5 V) is forced to converge at the predetermined value (14.5 V).
Next, in step S5000A, power supply ECU 160A performs
auxiliary charge processing. This auxiliary charge processing is control for performing charge if the SOC value of second battery 130 becomes less than or equal to a predetermined value. The reason for this is that a lead battery deteriorates more quickly if the SOC falls. The contents of this auxiliary charge processing are as shown in the flowchart in FIG.18.
First, in step S5100A, power supply ECU 160A determines whether or not state of charge of second battery 130 is less than predetermined value A, where predetermined value A is a suitable value in the range of 80 to 90%, for example. If it is determined that state of charge of second battery 130 is less than predetermined value A (S5100A: YES), the processing flow proceeds to step S5200A, whereas if it is determined that state of charge of second battery 130 is greater than or equal to predetermined value A (S5100A: NO), the main flowchart in FIG. 12 is returned to immediately,

In step S5200A, power supply ECU 160A charges only second battery 130, Specifically, in this case, at the start of charging, power supply ECU 160A switches the connection state of EDLC 120A and second battery 130 from series to parallel (singly-operated battery). The actual switching procedure at this time is as shown in FIG.20 later herein. By this means, first in-vehicle relay 150 is placed in an off (open) state, and second in-vehicle relay 152 in an on (closed) state. Second battery 130 is charged with electric power at, for example, 14.5 V generated from generator 110 controlled by power supply ECU 160A (that is, the following charging circuit is used: generator 110 → DC-DC converter 140 → second in-vehicle relay 152 → second battery 130). At this time, as described above, the output voltage of DC-DC converter 140 is controlled at 14.5 V. During charging of second battery 130, electric power at 12 V is simultaneously supplied from generator 110 to general load 180 via (and with the voltage stepped-down by) DC-DC converter 140 (that is, using the following feed circuit: generator 110 → DC-DC converter 140 → general load 180). When charging of second battery 130 is completed, power supply ECU 160A returns the connection state of EDLC 120A and second battery 130 to series connection from parallel (singly-operated battery) connection (see FIG. 14 for the actual switching procedure). Following this, the control procedure returns to the main flowchart in FIG. 12.
Next, in step S6000A, power supply ECU 160A determines whether or not the ignition (IG) switch (not shown)

has been switched off. If it is determined that the ignition switch has been switched off (S6000A: YES), the processing flow proceeds to step S7000A, whereas if it is determined that the ignition switch has not been switched off (S6000A: NO), the processing flow returns to step S3000A.
In step S7000A, power supply ECU 160A performs stop processing. The contents of this stop processing are as shown in the flowchart in FIG. 19.
. First, in step S7100A, power supply ECU 160A controls
two in-vehicle relays 150 and 152 and switches the connection of EDLC 120A and second battery 130 from series to parallel (singly-operated battery) connection. The actual switching procedure at this time is as shown in FIG.20. By means of this switching procedure, the connection of EDLC 120A and second battery 130 can be safely and surely Switched from series to parallel (singly-operated battery) connection.
Then, in step S7200A, power supply ECU 160A stops (turns off) DC-DC converter 140.
In step S7300A, power supply ECU 160A stops engine
112. Specifically, power supply ECU 160A outputs a control
signal that stops engine 112 to an engine ECU (not shown) that
controls engine operation. By this means, engine 112 stops.
: An idle reduction function has not been considered in
the above series of control operations, but it is of course possible for this to be considered. Specifically, for example, the connection of EDLC 120A and second battery 130 may be switched from series to parallel connection each time engine 112

is stopped due to an idle reduction operation.
Thus, according to this embodiment, when a vehicle decelerates and generator 110 outputs regenerated energy, EDLC 120A and second battery 130 are connected in series, and regenerated energy generated by generator 110 simultaneously charges series-connected EDLC 120A and second battery 130 at a high voltage. Therefore, regenerated energy generated during vehicle deceleration can be recovered efficiently by means of a simple and inexpensive configuration.
Also, when regenerated energy is being generated, together with charging of EDLC 120A and second battery 130 connected in series, electric power at 12 V is supplied directly from generator 110 to general load 180 via DC-DC converter 140. When the vehicle is not decelerating — that is, when generator 110 is not outputting regenerated energy —electric power at 12 V is supplied to general load 180 via DC-DC converter 140 from series-connected EDLC 120A and second battery 130 storing regenerated energy. Furthermore, after engine 112 stops, the operation of DC-DC converter 140 is stopped, the connection of EDLC 120A and second battery 130 are switched to parallel (singly-operated battery) connection, and a dark current is sent at 12 V to general load 180 from second battery 130 only. Therefore, electric power can be supplied to general load 180 in a stable fashion.
Also, when a technologically well-established and comparatively inexpensive lead battery is used as second battery 130, lower system cost and higher system safety can be secured

than when another high-performance battery (for example, a lithium-ion battery, nickel-hydride battery, or the like) is used.
Moreover, if the ratio of charge (SOC) of second battery 130 is less than or equal to a predetermined value, the ratio of charge of second battery 130 is controlled to be greater than or equal to the predetermined value (auxiliary charge processing), enabling an increase in the rate of battery deterioration to be suppressed.
In this embodiment, one EDLC and one battery are used, but there is no particular limitation on the numbers used. For example, at least one of the EDLC and the battery connected in series can be provided as a plurality of elements.
(Embodiment 3) FIG.21 is a block diagram showing the configuration of a power supply system that includes a vehicle power supply apparatus according to Embodiment 3 of the present invention. Configuration parts in power supply system 100B shown in FIG.21 common to power supply system 100 shown in FIG.l are assigned the same reference signs, and detailed descriptions thereof are omitted here.
Power supply system 100B shown in FIG.21 has generator 110, two batteries (first battery 120 and second battery 130), two current sensors 122 and 132, switch 142, three in-vehicle relays (first in-vehicle relay 150, second in-vehicle relay 152, and third in-vehicle relay 154), power supply ECU (Electronic Control Unit) 160B, starter 170, starter relay 172, and in-vehicle other general load (electrical equipment) 180.

Of the above configuration elements, two batteries 120 and 130, two current sensors 122 and 132, switch 142, three in-vehicle relays 150 through 154, and power supply ECU 160B, compose a power supply apparatus.
Switch 142 is used to switch the connection of two batteries 120 and 130 to parallel or series connection according to whether or not the vehicle is decelerating. Switch 142 is located between first battery 120 and second battery 130 (to be precise, current sensor 132 for second battery 130). Switch 142 is controlled so as to be in an on (closed) state when first battery 120 and second battery 130 are connected in series, and is controlled so as to be in an off (open) state when first battery 120 and second battery 130 are connected in parallel. Switch 142 repeats on/off switching according to a control signal from power supply ECU 160B,
Switch 142 should preferably be a large-capacity, durable semiconductor switch, for example. The reason for this is that when two batteries 120 and 130 are charged while connected in series, a large regenerated energy current flows from generator 110 to switch 142 (for example, a maximum current of 200 A may flow depending on the battery size), and switch 142 repeats on/off switching each time the vehicle decelerates. With a general in-vehicle relay, this presents a problem in terms of durability. It is possible for an in-vehicle relay to be used instead of a switch, particularly if it has durability.
The three in-vehicle relays (first in-vehicle relay 150,

second in-vehicle relay 152, and third in-vehicle relay 154) are used in collaboration with switch 142 to switch the connection of two batteries 120 and 130 to parallel or series connection according to whether or not the vehicle is decelerating. Three in-vehicle relays 150 through 154 repeat on/off operations according to control signals from power supply ECU 160B.
First in-vehicle relay 150 has one end connected between first battery 120 and switch 142, and the other end grounded. Second in-vehicle relay 152 has one end connected between generator 110 and first battery 120 (to be precise, current sensor 122 for first battery 120), and the other end connected to general load 180. Third in-vehicle relay 154 has one end connected between switch 142 and second battery 130 (to be precise, current sensor 132 for first battery 130), and the other end connected to general load 180. As described later herein, a charging circuit for batteries 120 and 130 from generator 110 and a feed circuit for electrical loads (starter 170 and general load 180) from batteries 120 and 130 are selected as appropriate by means of on/off combinations of switch 142 and three in-vehicle relays 150 through 154.
In-vehicle relays 150 through 154 are used to supply electric power from batteries 120 and 130 to electrical loads (starter 170 and general load 180) and therefore do not require such a large capacity as switch 142, and may be 40 A class relays, for example.
Power supply ECU 160B performs overall control of power supply system 100B. Specifically, for example, power

supply ECU 160B controls the on (closed)/off (open) state of switch 142 and three in-vehicle relays 150 through 154 in order to switch the connection of two batteries 120 and 130 to parallel or series connection according to whether or not the vehicle is decelerating. At this time, whether or not the vehicle is decelerating is determined, for example, based on vehicle speed information or the degree of brake pedal depression. Also, power supply ECU 160B measures the voltage and charge/discharge current of each of batteries 120 and 130, and calculates the State Of Charge (SOC) of each of batteries 120 and 130 by means of current integration. Furthermore, power supply ECU 160B controls generator 110. In addition, power supply ECU 160B performs other controls described later herein, Details of control of power supply ECU 160B will be given later herein using flowcharts in FIG.22 onward. Power supply ECU 160B includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory) that stores a program, and RAM (Random Access Memory) for program execution (none of which is shown in the drawings).
In this embodiment, when engine 112 is running and the vehicle is decelerating, two batteries 120 and 130 are connected in series, and batteries 120 and 130 connected in series are simultaneously charged at a high voltage with regenerated electric power generated by generator 110. In this case, for example, if one battery is charged at 14.5 V, it is possible to charge the two batteries at 29 V.
Also, when engine 112 is running and the vehicle is not

decelerating, and when engine 112 is stopped — that is, when generator 110 is not outputting regenerated electric power — two batteries 120 and 130 are connected in parallel, and electric power at 12 V is supplied to general load 180 from two batteries 120 and 130 storing regenerated electric power.
Furthermore, electric power at 12 V is also supplied to general load 180 from second battery 130 when the vehicle is decelerating.
As described above, power supply ECU 160B switches the connection of two batteries 120 and 130 to parallel or series connection according to whether or not the vehicle is decelerating. The on/off states of switch 142 and three in-vehicle relays 150 through 154 at this time are as described below.
When connecting two batteries 120 and 130 in parallel, power supply ECU I60B controls switch 142 so as to be in an off (open) state, controls first in-vehicle relay 150 so as to be in an on (closed) state, controls second in-vehicle relay 152 so as to be in an on (closed) state, and controls third in-vehicle relay 154 so as to be in an on (closed) state,, In this case, power supply ECU 160B stops (turns off) generator 110.
At this time,, the following circuits are formed as feed circuits from batteries 120 and 130 to general load 180: first battery 120 → second in-vehicle relay 152 → general load 180, and second battery 130 → third in-vehicle relay 154 → general load 180.
On the other hand, when connecting two batteries 120

and 130 in series, power supply ECU 160B controls switch 142 so as to be in an on (closed) state, controls first in-vehicle relay 150 so as to be in an off (open) state, controls second in-vehicle relay 152 so as to be in an off (open) state, and controls third in-vehicle relay 154 so as to be in an on (closed) state, In this case, power supply ECU 160B starts (turns on) generator 110.
At this time, the following circuit is formed as a charging circuit from generator 110 to batteries 120 and 130: generator 110 → batteries 120 and 130 connected in series. Also, the following circuit is formed as a feed circuit to general load 180: generator 110 → first battery 120 → switch 142 → third in-vehicle relay 154 → general load 180. If regenerated energy is sufficiently high, this circuit functions as a feed circuit to general load 180, but as regenerated energy decreases together with a reduction in speed, the following circuit is also formed in addition to this circuit in order to make up the deficiency in electric power supplied to general load 180: second battery 130 → third in-vehicle relay 154 → general load 180.
Below, a mode in which two batteries 120 and 130 are connected in series during vehicle deceleration and regeneration is referred to as "regeneration mode," and a mode in which two batteries 120 and 130 are connected in parallel other than during vehicle deceleration and regeneration is referred to as "driving mode."
Next, the operation of power supply system 100B having the above configuration will be described using FIG,22 through FIG.29. FIG.22 is a flowchart showing the overall operation of

power supply system 100B, FIG.23 is a flowchart showing the contents of battery state detection processing in FIG.22, FIG.24 is a flowchart showing the contents of mode processing in FIG.22, FIG.25 is a drawing showing the procedure for switching from regeneration mode to driving mode, FIG.26 is a drawing showing the procedure for switching from driving mode to regeneration mode, FIG.27 is a flowchart showing the contents of control processing for regenerative electric power generation in FIG.22, FIG.28 is a flowchart showing the contents of control processing for electric power generation in FIG.27, and FIG.29 is a flowchart showing the contents of auxiliary charge processing in FIG.22. These flowcharts are stored in a storage apparatus (for example, ROM or the like) (not shown) as control programs, and are executed by a CPU (not shown),
First, in step S1000B, power supply ECU 160B determines whether or not the ignition (IG) switch (not shown) has been switched on. Specifically, if the ignition switch has been turned to the engine start position (ST position), power supply ECU 160B determines that the ignition switch has been switched on. If it is determined that the ignition switch has been switched on (S1000B: YES), the processing flow proceeds to step S2000B, whereas if it is determined that the ignition switch has not been switched on (S1000B: NO), the program goes to a standby state.
In step S2000B, power supply ECU 160B starts engine 112. Specifically, power supply ECU 160B turns on starter relay 172 and applies a current to starter 170 from batteries 120

and 130 connected in parallel. By this means, engine 112 starts.
Then, in step S3000B, power supply ECU 160B performs battery state detection processing. The contents of this battery state detection processing are as shown in the flowchart in FIG.23.
First, in step S3100B, power supply ECU 160B measures the battery. Specifically, power supply ECU 160B measures the current (Ij) and voltage (V|) of first battery 120, and also measures the current (I2) and voltage (V2) of second battery 130, The current (Ij) of first battery 120 is detected by current sensor 122, and the current (I2) of second battery 130 is detected by current sensor 132.
Then, in step S3200B, power supply ECU 160B calculates the battery state. Specifically, for example, power supply ECU 160B integrates a detection result (charge/discharge current value) from current sensor 122 and calculates the SOC of first battery 120 (hereinafter referred to as "SOC1"), and integrates a detection result (charge/discharge current value) from current sensor 132 and calculates the SOC of second battery 130 (hereinafter referred to as "SOC2"). In this way, the SOC of a battery can be calculated by integrating a current flowing into the battery and a current flowing out of the battery (so-called Coulomb count processing). The SOC calculation method for batteries 120 and 130 is not limited to Coulomb count processing, and any other known method can also be used. Following this, the control procedure returns to the main

flowchart in FIG.22.
Next, in step S4000B, power supply ECU 160B performs mode processing. The contents of this mode processing are as shown in the flowchart in FIG.24.
First, in step S4100B, power supply ECU 160B determines whether or not the vehicle speed is greater than or equal to a predetermined value (for example, 10 km/h). Here, determining whether or not the vehicle speed is greater than or equal to a predetermined value is to determine whether or not the current vehicle speed is suitable for regenerative electric power generation — that is, whether or not kinetic energy necessary for regenerative electric power generation is available in the vehicle. Regenerated energy is obtained by converting kinetic energy of the vehicle to electrical energy. Since a low vehicle speed leads fo low kinetic energy, a regenerated energy amount cannot be expected. If it is determined that the vehicle speed is less than the predetermined value (10 km/h) (S4100B: NO), the processing flow proceeds to step S4200B, whereas if it is determined that the vehicle speed is greater than or equal to the predetermined value (10 km/h) (S4100B: YES), the processing flow proceeds to step S4400B.
In step S4200B, power supply ECU 160B further determines whether or not the current mode is regeneration mode. If it is determined that the current mode is regeneration mode (S4200B: YES), the processing flow proceeds to step S4300B, whereas if it is determined that the current mode is not regeneration mode (S4200B: NO), it is determined that driving

mode is already in effect, and the main flowchart in FIG.22 is returned to immediately.
In step S4300B, power supply ECU 160B controls switch 142 and three in-vehicle relays 150 through 154 and switches the mode from regeneration mode to driving mode. The actual switching procedure at this time is as shown in FIG.25. By means of this switching procedure, the connection of two batteries 120 and 130 can be safely and surely switched from series to parallel connection. Following this, the control procedure returns to the main flowchart in FIG.22.
On the other hand, in step S4400B, power supply ECU 160B further determines whether or not the vehicle is decelerating. Whether or not the vehicle is decelerating is determined, for example, based on vehicle speed information, or based on the degree of brake pedal depression (whether the brake pedal is being depressed). If it is determined that the vehicle is not decelerating (S4400B: NO), the processing flow proceeds to step S4500B, whereas if it is determined that the vehicle is decelerating (S4400B: YES), the processing flow proceeds to step S4700B.
In step S4500B, power supply ECU 160B further determines whether or not the current mode is regeneration mode, as in step S4200B. If it is determined that the current mode is regeneration mode {S4500B: YES), the processing flow proceeds to step S4600B, whereas if it is determined that the current mode is not regeneration mode (S4500B: NO), it is determined that driving mode is already in effect, and the main flowchart in

FIG.22 is returned to immediately,
In step S4600B, as in step S4300B, power supply ECU
160B controls switch 142 and three in-vehicle relays 150 through
154 and switches the mode from regeneration mode to driving
mode. The actual switching procedure at this time is as shown
in FIG.25. By means of this switching procedure, the
connection of two batteries 120 and 130 can be safely and surely switched from series to parallel connection. Following this, the control procedure returns to the main flowchart in FIG.22.
On the other hand, in step S4700B, power supply ECU 160B determines whether or not the current mode is driving mode If it is determined that the current mode is driving mode (S4700B: YES), the processing flow proceeds to step S4800B, whereas if it is determined that the current mode is not driving mode (S4700B: NO), it is determined that regeneration mode is already in effect, and the main flowchart in FIG.22 is returned to immediately.
In step S4800B, power supply ECU 160B controls switch 142 and three in-vehicle relays 150 through 154 and switches the mode from driving mode to regeneration mode. The actual switching procedure at this time is as shown in FIG.26, By means of this switching procedure, the connection of two batteries 120 and 130 can be safely and surely switched from parallel to series connection, Following this, the control procedure returns to the main flowchart in FIG.22.
In short, in the mode processing in step S4000B, if the vehicle speed is greater than or equal to a predetermined value

(for example, 10 km/h) and the vehicle is decelerating, power supply ECU 160B sets the mode to regeneration mode, and if this is not the case — that is, if the vehicle speed is less than the predetermined value (10 km/h) or the vehicle is not decelerating (that is, the vehicle is accelerating, traveling at a constant speed idling, or the like) — power supply ECU 160B sets the mode to driving mode.
Next, in step S5000B, power supply ECU 160B performs regenerative electric power generation control. The contents of this regenerative electric power generation control are as shown in the flowchart in FIG.27.
First, in step S5100B, power supply ECU 160B determines whether or not the current mode is regeneration mode If it is determined that the current mode is regeneration mode (S5100B: YES) — that is, if the vehicle speed is greater than or equal to the predetermined value (10 km/h) and the vehicle is decelerating — the processing flow proceeds to step S5200B, and if this is not the case, that is, if the current mode is driving mode (S5100B: NO) — that is, if the vehicle speed is less than the predetermined value (10 km/h) or the vehicle is not decelerating (that is, the vehicle is accelerating, traveling at a constant speed idling, or the like) — the main flowchart in FIG.22 is returned to immediately,
In Step S5200B, power supply ECU 160B performs electric power generation control on generator 110. In this electric power generation control, voltages V1 and V2 of batteries 120 and 130 respectively are controlled so as not to

exceed a predetermined value (for example, 14.5 V). The reason for this is that a lead battery will deteriorate more quickly if an excessively high voltage is applied to it. Also, in this electric power generation control, electric power generation by generator 110 is stopped if the SOC of at least one of two batteries 120 and 130 reaches 100% or above. The reason for this is that a lead battery will deteriorate more quickly if excessively charged. The contents of this electric power generation control are as shown in the flowchart in FIG.28,
First, in step S5210B, power supply ECU 160B determines whether or not the state of charge of first battery 120 (SOC1) is greater than or equal to 100%, or the state of charge of second battery 130 (SOC2) is greater than or equal to 100%. If it is determined that the state of charge of first battery 120 (SOC1) is greater than or equal to 100% or the state of charge of second battery 130 (SOC2) is greater than or equal to 100% — that is, that the SOC of at least one of two batteries 120 and 130 is greater than or equal to 100% — (S52 10B: YES), the processing flow proceeds to step S5220B, and if this is not the case — that is, if the SOCs of both batteries 120 and 130 are less than 100% — (S5210B: NO), the processing flow proceeds to step S5230B.
In step S5220B, power supply ECU 160B stops electric power generation by generator 110. Following this, the control procedure returns to the main flowchart in FIG.22.
On the other hand, in step S5230B, power supply ECU 160B further determines whether or not the voltage (V[) of first

battery 120 exceeds a predetermined value (for example, 14.5 V), or the voltage (V2) of second battery 130 exceeds a predetermined value (for example, 14.5 V). If it is determined that the voltage (Vi) of first battery 120 exceeds the predetermined value (14,5 V) or the voltage (V2) of second battery 130 exceeds the predetermined value (14.5 V) — that is, that the voltage of at least one of two batteries 120 and 130 exceeds the predetermined value (14.5 V) — (S5230B: YES), the processing flow proceeds to step S5240B, and if this is not the case — that is, if voltages V1 aad V2 of batteries 120 and 130 respectively are both less than or equal to the predetermined value (14.5 V) — (S5230B: NO), the processing flow proceeds to step S5250B.
In step S5240B, power supply ECU 160B sets an output instruction value to generator 110 lower than a target value (for example, 29 V). Following this, the control procedure returns to the main flowchart in FIG.22.
On the other hand, in step S5250B, power supply ECU 160B sets an output instruction value to generator 110 to the target value (29 V), Following this, the control procedure returns to the main flowchart in FIG.22.
The control contents of step S5240B are not limited to the above example. In this case, any kind of control method may be used as long as a battery voltage exceeding the predetermined value (14.5 V) can be lowered to the predetermined value (14.5 V) or below. For example, it is also possible to use so-called PID control for such control that a

battery voltage exceeding the predetermined value (14.5 V) is forced to converge at trie predetermined value (14.5 V).
Next, in step S6000B, power supply ECU 160B performs auxiliary charge processing. This auxiliary charge processing is control for preventing the difference between the SOCs of two batteries 120 and 130 from becoming large, or for performing charge if the SOC value of battery 120 or 130 becomes less than or equal to a predetermined value. The reason for the former case is that charge/discharge characteristics in a series connection state deteriorate if the difference between the SOCs of two batteries 120 and 130 becomes large, and the reason for the latter case is that a lead battery deteriorates more quickly if the SOC falls. In particular, in this embodiment, second battery 130 always discharges unlike first battery 120 regardless of whether second battery 130 is connected to first battery 120 in series or parallel. Therefore, if the connection of batteries 120 and 130 is switched (series ↔ parallel) repeatedly, the difference in SOCs between two batteries 120 and 130 increases readily. Therefore, in this embodiment, this auxiliary charge processing is more necessary, The contents of this auxiliary charge processing are as shown in the flowchart in FIG.29.
First, in step S6100B, power supply ECU 160B determines whether or not two batteries 120 and 130 are connected in parallel. This determination is performed, for example, by determining whether the current mode is driving mode or regeneration mode. If it is determined that two batteries 120 and 130 are connected in parallel (S6100B: YES) —

that is, the current mode is driving mode — the processing flow proceeds to step S6200B, whereas if it is determined that two batteries 120 and 130 are connected in series (S6100B: NO) — that is, the current mode is regeneration mode — batteries 120 and 130 are already being charged, and therefore the main flowchart in FIG.22 is returned to immediately.
In step S6200B, power supply ECU 160B determines whether or not state of charge SOC1 of first battery 120 is less than predetermined value A and state of charge SOC2 of second battery 130 is less than predetermined value A, where predetermined value A is a suitable value in the range of 80 to 90%, for example. If it is determined that state of charge SOC1 of first battery 120 is less than predetermined value A and state of charge SOC2 of second battery 130 is less than predetermined value A — that is, that the SOCs of both batteries 120 and 130 are less than predetermined value A — (S6200B: YES), the processing flow proceeds to step S6300B, and if this is not the case (S6200B: NO), the processing flow proceeds to step S6400B.
In step S6300B, power supply ECU 160B simultaneously charges two batteries 120 and 130 in series. Specifically, in this case, at the start of charging, power supply ECU I60B switches the connection state of two batteries 120 and 130 from parallel to series connection as long as the vehicle is traveling. By this means, switch 142 is placed in an in an on (closed) state, first in-vehic!e relay 150 in an off (open) state, second in-vehicle relay 152 in an off (open) state, and third in-vehicle

relay 154 in an on (closed) state. Auxiliary charging at this time is immediately necessary for two batteries 120 and 130 in order to avoid battery deterioration, regardless of whether or not the vehicle is decelerating. Consequently, when the vehicle is decelerating, this opportunity is used to charge batteries 120 and 130 with regenerated energy, whereas when the vehicle is not decelerating — that is, when the vehicle is traveling — generator 110 is forcibly made to generate electric power at 29 V and charge batteries 120 and 130. By this means, regenerated energy generated by generator 110 during vehicle deceleration or electric power forcibly generated by generator 110 when the vehicle is traveling simultaneously charges batteries 120 and 130 in series (that is, the following charging circuit is used: generator 110 → batteries 120 and 130 connected in series). This kind of simultaneous charging is continued until at least one of the SOCs of two batteries 120 and 130 reaches predetermined value A or above. When charging of batteries 120 and 130 is completed, power supply ECU 160B returns the connection state of batteries 120 and 130 from series to parallel connection. During charging, as described above, electric power is supplied to general load 180 from generator 110 via first battery 120, switch 142, and third in-vehicle relay 154 (that is, using the following feed circuit: generator 110 —> first battery 120 → switch 142 → third in-vehicle relay 154 → general load 180), and when the vehicle speed falls, in addition to this circuit, electric power is also supplied to general load 3 80 from second battery 130 via third in-vehicle relay 154 (that is, using the

following feed circuit: second battery 130 →third in-vehicJe relay 154 → general load 180).
On the other hand, in step S6400B, power supply ECU 160B further determines whether or not only state of charge SOC1 of first battery 120 is less than predetermined value A, If it is determined that only state of charge SOC1 of first battery 120 is less than predetermined value A (S6400B: YES), the processing flow proceeds to step S6500B, and if this is not the case (S6400B: NO), the processing flow proceeds to step S6600B.
In step S6500B, power supply ECU 160B charges only first battery 120. Specifically, in this case, at the start of charging, power supply ECU I60B places third in-vehicle relay 154 in an off (open) state from a state in which batteries 120 and 130 are connected in parallel. By this means, switch 142 is placed in an off (open) state, first in-vehicie relay 150 in an on (closed) state, second in-vehicle relay 152 in an on (closed) state, and third in-vehicle relay 154 in an off (open) state. First battery 120 is charged with electric power at, for example, 14.5 V generated from generator 110 controlled by power supply ECU 160B (that is, the following charging circuit is used: generator 110 → first battery 120). During charging of first battery 120, electric power is simultaneously supplied from generator 110 to general load 180 via second in-vehicle relay 152 (that is, the following feed circuit is used: generator 110 → second in-vehicle relay 152 → general load 180). When charging of first battery 120 is completed, power supply ECU 160B places

third in-vehicle relay 154 in an on (closed) state and returns the connection state of batteries 120 and 130 to parallel connection.
On the other hand, in step S6600B, power supply ECU 160B further determines whether or not only state of charge SOC2 of second battery 130 is less than predetermined value A. If it is determined that only state of charge SOC2 of second battery 130 is less than predetermined value A (S6600B: YES), the processing flow proceeds to step S6700B, and if this is not the case (S6600B: NO), the processing flow proceeds to step S6800B.
In step S6700B, power supply ECU 160B charges only second battery 130. Specifically, in this case, at the start of charging, power supply ECU 160B places first in-vehicle relay 150 in an off (open) state from a state in which batteries 120 and 130 are connected in parallel. By this means, switch 142 is placed in an off (open) state, first in-vehicle relay 150 in an off (open) state, second in-vehicle relay 152 in an on (closed) state, and third in-vehicle relay 154 in an on (closed) state. Second battery 130 is charged with electric power at, for example, 14.5 V generated from generator 110 controlled by power supply ECU 160B (that is, the following charging circuit is used: generator 110 → second in-vehicle relay 152 → second battery 130). During charging of second battery 130, electric power is simultaneously supplied from generator 110 to general load 180 via second in-vehicle relay 152 (that is, the following feed circuit is used; generator 110 → second in-vehicle relay 152 → general load 180). When charging of second battery 130 is

completed, power supply ECU 160B places first in-vehicle relay 150 in an on (closed) state and returns the connection state of batteries 120 and 130 to parallel connection.
On the other hand, in step S6800B, power supply ECU 160B further determines whether or not the difference in SOCs between two batteries 120 and 130 is greater than predetermined value a. In this embodiment, as described above, second battery 130 is almost constantly discharging, and therefore normally the SOC of second battery 130 tends to be smaller than that of first battery 120. Thus, here, a value obtained by subtracting SOC2 from SOC1 is found as the difference in SOCs between two batteries 120 and 130. Also, predetermined value a is, for example, 2%. If it is determined that the difference in SOCs between two batteries 120 and 130 (SOC1-SOC2) is greater than predetermined value ct (S6800B: YES), the processing flow proceeds to step S6900B, and if this is not the case — that is, if the difference in SOCs between two batteries 320 and 130 (SOC1-SOC2) is less than or equal to predetermined value a — (S6800B; NO), the main flowchart in FIG.22 is returned to immediately.
Instep S6900B, in order to lower the difference in SOCs between two batteries 120 and 130 to predetermined value a or below, power supply ECU 160B performs discharging from only first battery 120 having the larger SOC. Specifically, in this case, power supply ECU 160B places third in-vehicle relay 154 in an off (open) state from a state in which batteries 120 and 130 are connected in parallel. By this means, switch 142 is placed

in an off (open) state, first in-vehicle relay 150 in an on (closed) state, second in-vehicle relay 152 in an on (closed) state, and third in-vehicle relay 154 in an off (open) state. At this time, first battery 120 discharges by supplying electric power to general load 180 via second in-vehicle relay 152 (that is, the following feed circuit is used: first battery 120 → second in-vehicle relay 152 → general load 180). During this time, second battery 130 does not perform charging or discharging. When the difference in SOCs between two batteries 120 and 130 reaches predetermined value a or below, power supply ECU 160B places third in-vehicle relay 154 in an on (closed) state and returns the connection state of batteries 120 and 130 to parallel connection.
Next, in step S7000B, power supply ECU 160B determines whether or not the ignition (1G) switch (not shown) has been switched off. If it is determined that the ignition switch has been switched off(S7000B: YES), the processing flow proceeds to step S8000B, whereas if it is determined that the ignition switch has not been switched off (S7000B: NO), the processing flow returns to step S3000B.
In step S8000B, power supply ECU 1 60B stops engine 112. Specifically, power supply ECU 160B outputs a control signal that stops engine 112 to an engine ECU (not shown) that controls engine operation, By this means, engine 112 stops.
Thus, according to this embodiment, when a vehicle decelerates and generator 110 outputs regenerated energy, batteries 120 and 130 are connected in series (regeneration

mode), and regenerated energy generated by generator 110 simultaneously charges series-connected batteries 120 and 130 at a high voltage. Therefore, regenerated energy generated during vehicle deceleration can be recovered efficiently by means of a simple and inexpensive configuration.
Also, when the vehicle is not decelerating — that is, when generator 110 is not outputting regenerated energy — batteries 120 and 130 are connected in parallel (driving mode), and electric power at 12 V is supplied to genera) load 180 from parallel-connected batteries 120 and 130 storing regenerated energy. Furthermore, electric power at 12 V is also constantly supplied to general load 180 from second battery 130 when two batteries 120 and 130 are connected in series during vehicle deceleration. Therefore, electric power can be supplied to general load 180 in a stable fashion.
Also, when technologically well-established and comparatively inexpensive lead batteries are used as two batteries 120 and 130, lower system cost and higher system safety can be secured than when other high-performance batteries (for example, lithium-ion batteries, nickel-hydride batteries, or the like) are used.
Moreover, the same kind of battery (a lead battery) is used for two batteries 120 and 130, enabling freedom of design to be increased and the installation space to be reduced by modularizing two batteries 120 and 130.
Also, if the ratios of charge (that is, SOCs) of two batteries 120 and 130 are less than or equal to a predetermined

value, or the difference in the ratios of charge (that is, SOCs) is greater than or equal to a predetermined value, the ratios of charge of both batteries 120 and 130 are controlled to be greater than or equal to the predetermined value (auxiliary charge processing), enabling an increase in the rate of battery deterioration to be suppressed.
In this embodiment, the number of batteries used is two, but there is no particular limitation on the number of batteries used. It is also possible to use a configuration in which three or more batteries can be switched to a series or parallel connection state.
The disclosures of Japanese Patent Application No.2010-075276, filed on March 29, 2010, Japanese Patent Application No.2010-075277, filed on March 29, 2010, and Japanese Patent Application No.20 1 0-075278, filed on March 29, 2010, including the specifications, drawings and abstracts, are incorporated herein by reference in their entirety.
Industrial Applicability
A vehicle power supply apparatus according to the present invention is suitable for use as a vehicle power supply apparatus that can efficiently recover regenerated energy during vehicle deceleration, and also supply electric power to an electrical load in a stable fashion, by means of a simple and inexpensive configuration, while allowing greater freedom of design and a reduction in the installation space.

Reference Signs List
100, 100A, 100B Power supply system
11 0 Generator
112 Engine
120, 130 Battery
120A Electric double layer capacitor (EDLC)
122, 1 32 Current sensor
140 DC-DC converter
142 Switch
150, 152, 154, 156 In-vehicle relay
160, 160A, 160B Power supply ECU
170 Starter
172 Starter relay
180 General load (electrical equipment)

We Claim :
Claim 1
A vehicle power supply apparatus comprising;
a generator that generates regenerated electric power when a vehicle decelerates;
a first electrical storage device that is connected to the generator and stores the regenerated electric power;
a second electrical storage device that is capable of being connected in series to the first electrical storage device and stores the regenerated electric power;
a first switch that connects/disconnects the second electrical storage device and electrical equipment; and
a control section that controls an electrical connection state of the generator, the first electrical storage device, the second electrical storage device, and the electrical equipment, according to a state of the vehicle, wherein
the control section charges the first electrical storage device and the second electrical storage device with regenerated electric power generated by the generator when an engine of the vehicle is running and the vehicle is decelerating, and turns on the first switch and feeds the electrical equipment from the second electrical storage device when the engine of the vehicle is stopped.
Claim 2
The vehicle power supply apparatus according to claim 1, wherein:

the first electrical storage device is an electric double layer capacitor or a lead battery; and
the second electrical storage device is a lead battery.
Claim 3
The vehicle power supply apparatus according to claim 1, further comprising a DC-DC converter that electrically connects the generator and the first electrical storage device and the electrical equipment, and converts an input direct current voltage to a lower direct current voltage and outputs that lower direct current voltage, wherein
the control section, when the engine of the vehicle is running, operates the DC-DC converter, turns off the first switch, and feeds regenerated electric power generated by the generator via the DC-DC converter, or electric power with which the first electrical storage device and the second electrical storage device are charged, to the electrical equipment, and, when the engine of the vehicle is stopped, stops the DC-DC converter and turns on the first switch.
Claim 4
The vehicle power supply apparatus according to claim 3, further comprising a second switch that is parallel to the DC-DC converter and connects/disconnects the generator to and from the first electrical storage device and the electrical equipment, wherein
the control section turns off the second switch when the engine of the vehicle is running, and when the engine of the vehicle is stopped, turns on the second switch, connects the first electrical storage device and the second electrical storage device in parallel with respect to the

electrical equipment, and feeds electric power to the electrical equipment from the first electrical storage device and the second electrical storage device.
Claim 5
The vehicle power supply apparatus according to claim 1, further comprising:
a third switch that connects/disconnects the first electrical storage device and the electrical equipment; and
a fourth switch that connects/disconnects the first electrical storage device and the second electrical storage device, wherein
the control section, when the engine of the vehicle is running and the vehicle is decelerating, turns on the first switch, turns off the third switch, turns on the fourth switch, and feeds regenerated electric power generated by the generator to the electrical equipment, and when the engine of the vehicle is running and the vehicle is not decelerating, or when the engine of the vehicle is stopped, turns on the first switch, turns on the third switch, turns off the fourth switch, connects the first electrical storage device and the second electrical storage device in parallel with respect to the electrical equipment, and supplies electric power to the electrical equipment from the first electrical storage device and the second electrical storage device.
Claim 6
The vehicle power supply apparatus according to claim 1, further comprising a third switch that connects/disconnects the generator and the first electrical storage device to and from the

electrical equipment, wherein
the control section, when the engine of the vehicle is running and the vehicle is decelerating, turns on the first switch, turns off the third switch, and feeds regenerated electric power generated by the generator to the electrical equipment, and
when the engine of the vehicle is running and the vehicle is not decelerating, or when the engine of the vehicle is stopped, turns on the first switch, turns off the third switch, and supplies electric power to the electrical equipment from the second electrical storage device.
Claim 7
The vehicle power supply apparatus according to claim 1, further comprising a current sensor that measures charge/discharge currents of the first electrical storage device and the second electrical storage device, wherein
the control section calculates the ratio of charge of the first electrical storage device and the second electrical storage device based on a value measured by the current sensor, and
controls an output voltage of the generator and an electrical connection state of the generator, the first electrical storage device, the second electrical storage device, and the electrical equipment, so that the ratio of charge of the first electrical storage device and the second electrical storage device becomes greater than or equal to a predetermined value.