M 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ELECTRONIC CONTROL DEVICE AND ELECTRONIC CONTROL METHOD
MITSUBISHI ELECTRIC CORPORATION A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
[DESCRIPTION]
[Technical Field]
[0001]
The present disclosure relates to an electronic control device and an electronic
5 control method.
[Background Art]
[0002]
Patent Document 1 describes an electronic control device including: a reverse
connection protector including a MOSFET as a switching element and a Zener diode as a
10 reverse flow prevention element; a power source circuit that generates a positive power
source voltage; a voltage detector that detects a voltage between a positive power source
voltage and a ground of a battery; an A/D convertor that performs A/D conversion on a
voltage output from the voltage detector; and a failure diagnosis unit that performs failure
diagnosis on the reverse connection protector on the basis of an output value output from
15 the A/D convertor. Patent Document 1 describes providing an electronic control device
capable of diagnosing a failure of a reverse connection protection element using a
MOSFET as a reverse connection protection element between a load and a ground.
[Citation List]
[Patent Document]
20 [0003]
[Patent Document 1]
Japanese Unexamined Patent Application, First Publication No. 2017-42015
[Summary of Invention]
[Technical Problem]
25 [0004]
3
In the electronic control device described in Patent Document 1, when a positive
voltage is applied from a positive electrode of a battery to a gate of the MOSFET, a drain
and a source of the MOSFET are electrically connected. Therefore, a short-circuit failure
in the MOSFET cannot be detected solely by monitoring a positive power source voltage.
5 When the battery is reversely connected at the time of short-circuit failure, a current flows
reversely. The reverse flow of the current causes a failure of the electronic control device.
In order to avoid the reverse flow of the current, redundancy of a reverse connection
protection relay or addition of a drive device for applying a positive power source voltage
to a gate of the MOSFET is also conceivable. These measures require additional
10 elements or peripheral circuits, thus leading to an increase in circuit scale or cost.
[0005]
One object of the present disclosure is to provide an electronic control device and
an electronic control method that solve the above-described problems.
[Solution to Problem]
15 [0006]
A first aspect is an electronic control device comprising a reverse connection
protection relay, a voltage detector, and a control device, in which the reverse connection
protection relay comprises a switching element and a rectifying element, the switching
element and the rectifying element are connected in parallel, a negative electrode of the
20 rectifying element and a positive electrode of the rectifying element are connected to a
negative electrode of a power source and a load, respectively, the load is configured to
consume power supplied from the power source, opening and closing of the switching
element are controlled on the basis of a switching control signal indicating presence or
absence of power supply from the power source, the voltage detector is configured to detect
25 a potential difference between both ends of the reverse connection protection relay, and the
4
control device is configured to determine a state of the reverse connection protection relay
on the basis of the potential difference.
[0007]
A second aspect is an electronic control method in an electronic control device
5 comprising a reverse connection protection relay, a voltage detector, and a control device,
in which the reverse connection protection relay comprises a switching element and a
rectifying element, the switching element and the rectifying element are connected in
parallel, a negative electrode of the rectifying element and a positive electrode of the
rectifying element, the negative electrode of the rectifying element and the positive
10 electrode of the rectifying element, are connected to a negative electrode of a power source
and a load, respectively, the load is configured to consume power supplied from the power
source, and opening and closing of the switching element are controlled on the basis of a
switching control signal indicating presence or absence of power supply from the power
source, the method including: a first step of detecting, by the voltage detector, a potential
15 difference between both ends of the reverse connection protection relay; and second step
of determining, by the control device, a state of the reverse connection protection relay on
the basis of the potential difference.
[Advantageous Effects of Invention]
[0008]
20 According to the present disclosure, it is possible to economically detect a failure
of a reverse connection protection relay.
[Brief Description of Drawings]
[0009]
FIG. 1 is a circuit diagram illustrating a configuration example of an electronic
25 control device according to a first embodiment.
5
FIG. 2 is a circuit diagram illustrating a circuit configuration example around a
reverse connection protection relay according to the first embodiment.
FIG. 3 is an explanatory diagram for describing a specific example of a method
for determining a state of the reverse connection protection relay according to the first
5 embodiment.
FIG. 4 is a circuit diagram illustrating a configuration example of an electronic
control device according to a second embodiment.
FIG. 5 is an explanatory diagram for describing a specific example of a method
for detecting a short-circuit failure in a reverse connection protection relay according to
10 the second embodiment.
[Description of Embodiments]
[0010]
Hereinafter, embodiments will be described with reference to the drawings.
Elements common to or corresponding to the drawings are denoted by the same reference
15 numerals, and description thereof is applied unless otherwise specified.

A first embodiment will be described with reference to the drawings. FIG. 1 is
a circuit diagram illustrating a configuration example of an electronic control device 1
according to the present embodiment. In the example of FIG. 1, it is assumed that the
20 electronic control device 1 is mounted on the same vehicle (not illustrated) together with
a power source 8, a power source switch 9, and an electric motor 7, and is used to control
an operation of an operation mechanism of the vehicle. The power source switch 9
controls necessity of power supply from the power source 8 to the electronic control device
1. The power source switch 9 receives an operation from a user, for example, and
25 generates a switching control signal indicating the necessity of power supply according to
6
the received operation. The power source switch 9 switches the necessity of power
supply from the power source 8 to the electronic control device 1 according to the
generated switching control signal, and outputs the generated switching control signal to
the electronic control device 1. The necessity of power supply from the power source 8
5 to the electronic control device 1 is instructed using the switching control signal provided
from the power source switch 9.
[0011]
A battery and an ignition switch can be applied as the power source 8 and the
power source switch 9, respectively. The battery is a storage battery capable of supplying
10 DC power to the electronic control device 1. A driver of the vehicle can be a main user
of the electronic control device 1. The ignition switch generates an ignition signal as an
example of the switching control signal. The ignition signal is used to control activation
(ON) or stop (OFF) of an operation mechanism of the vehicle. The operation mechanism
of the vehicle includes, for example, electric power steering (EPS). The electric motor 7
15 forms a part of the operation mechanism.
[0012]
The electronic control device 1 includes an electric motor drive circuit 5 as a load
that consumes power supplied from the power source 8. The electric motor drive circuit
5 supplies power from the power source 8 to the electric motor 7 to drive the electric motor
20 7. The electric motor 7 also functions as a load that consumes power supplied from the
power source 8. The number of electric motors 7 included in the operation mechanism
of the vehicle is not limited to one, and can be two or more. In this case, the electric
motor drive circuit 5 supplies power required for an operation of each electric motor 7.
Note that, in the following description, a case where the number of electric motors 7 is one
25 will be mainly described.
7
[0013]
The electronic control device 1, the power source 8, the power source switch 9,
and the electric motor 7 may be individually manufactured or transferred. In addition,
the electronic control device 1, the power source 8, the power source switch 9, and the
5 electric motor 7 may be attached to and detached from the vehicle at the time of
maintenance, inspection, repair, or the like. For example, a positive electrode terminal
and a negative electrode terminal of a battery as the power source 8 are connected to the
electronic control device 1 using a power source plug (not illustrated). When the battery
is replaced, the battery, which is a DC power source, may be connected to the power source
10 plug in error of polarity. Connection with a polarity different from a predetermined
polarity is called reverse connection. When the battery is connected with a wrong polarity,
a current from the battery flows reversely in the electronic control device 1. The reverse
flow of the current may cause a fault or a failure of the electronic control device 1. For
protection from reverse connection, the electronic control device 1 includes a reverse
15 connection protection relay 2. As described below, the electronic control device 1 can
autonomously determine a state of the reverse connection protection relay 2.
[0014]
The electronic control device 1 includes the reverse connection protection relay 2,
a voltage detector 3, a control device 4, the electric motor drive circuit 5, a power source
20 output holding circuit 6, and a power source circuit 10.
The reverse connection protection relay 2 protects the electric motor drive circuit
5 from a reverse flow of a current that may occur at the time of reverse connection of the
power source 8. The reverse connection protection relay 2 includes a switching element
2s and a rectifying element 14. The switching element 2s and the rectifying element 14
25 are connected in parallel. That is, at one end of the reverse connection protection relay 2,
8
one end of the rectifying element 14 and one end of the switching element 2s are
electrically connected. At the other end of the reverse connection protection relay 2, the
other end of the rectifying element 14 and the other end of the switching element 2s are
electrically connected. The one end of the reverse connection protection relay 2 is
5 connected to a negative electrode of the power source 8.
[0015]
Opening and closing of both ends of the switching element 2s are controlled on
the basis of a switching control signal applied from the power source switch 9 to the
switching element 2s. Whether or not a current flows from one end to the other end of
10 the switching element 2s is controlled in conjunction with presence or absence of power
supply from the power source 8 to the electronic control device 1 indicated by the
switching control signal. Even if the power source 8 is connected with a polarity reverse
to the illustrated polarity, the reverse connection protection relay 2 cuts off a current from
the power source 8 to the electric motor drive circuit 5. Therefore, the electric motor
15 drive circuit 5 is protected from the reverse flow of the current.
[0016]
A digital electric signal indicating necessity of power supply from the power
source 8 depending on whether a voltage is a high voltage or a low voltage may be used as
the switching control signal. The high voltage and the low voltage indicate a higher
20 voltage and a lower voltage of two-stage voltages, respectively. When a signal with a
high voltage is not supplied, a detected voltage may be a low voltage. In the present
application, the high voltage may be referred to as High. The low voltage may be referred
to as Low.
[0017]
25 The switching element 2s is, for example, a metal-oxide-semiconductor field-
9
effect transistor (MOSFET). The MOSFET generally comprises a source, a drain, and a
gate. The MOSFET comprises a source terminal, a drain terminal, and a gate terminal in
a source region, a drain region, and a gate region, respectively. The MOSFET as the
switching element 2s is connected to the rectifying element 14 with its source terminal and
5 drain terminal as one end and the other end, respectively. The switching control signal
input from the power source switch 9 is applied to the gate terminal.
[0018]
Note that the MOSFET as the switching element 2s may be any type of MOSFET
such as an n-type MOSFET or a p-type MOSFET. The present embodiment exemplifies
10 a case where an n-type MOSFET is used as the switching element 2s. In the n-type
MOSFET, a silicon oxide film and a gate electrode are disposed in a gate region set on a
p-type semiconductor substrate. In each of a drain region and a source region, an n-type
semiconductor is disposed on the p-type semiconductor substrate. The n-type
semiconductor is formed by ion implantation with impurity concentration higher than the
15 p-type semiconductor.
[0019]
The rectifying element 14 causes a current to flow from one end thereof to the
other end of the rectifying element 14, and cuts off a current from the other end to the one
end. The rectifying element 14 is, for example, a diode. The diode generally includes
20 an anode and a cathode. The diode as the rectifying element 14 is connected to the
switching element 2s with the anode and the cathode as one end thereof and the other end
of the rectifying element 14.
[0020]
For example, a parasitic diode may be used as the rectifying element 14. The
25 parasitic diode is also referred to as a body diode. The parasitic diode is configured to
10
have a pn junction between a source region and a drain region of the n-type MOSFET.
The pn junction is formed by disposing a p-type semiconductor together with an n-type
semiconductor in a source region and disposing an n-type semiconductor in a drain region
such that the n-type semiconductor is not in contact with the p-type semiconductor. As
5 the rectifying element 14, a parasitic diode configured in a MOSFET as the switching
element 2s may be used. As a result, a MOSFET in which the switching element 2s and
the rectifying element 14 are integrally configured can be used as the reverse connection
protection relay 2.
[0021]
10 The voltage detector 3 detects a voltage at one end of the reverse connection
protection relay 2. As described later, a voltage detected on the basis of a reference
potential GND_PCB corresponds to a potential difference between both ends of the reverse
connection protection relay 2. The voltage detector 3 generates an electric signal
indicating the detected voltage, and outputs the generated electric signal to the control
15 device 4 as a detection voltage signal.
[0022]
The control device 4 consumes power supplied from the power source 8 via the
power source switch 9 and the power source circuit 10, and executes and controls various
processes for exerting functions of the electronic control device 1. The control device 4
20 includes, for example, a central processing unit (CPU). The control device 4 determines
a state of the reverse connection protection relay 2 on the basis of the detection voltage
signal input from the voltage detector 3. The control device 4 includes, for example, an
analog to digital (A/D) converter. The A/D converter converts the input analog detection
voltage signal into a digital detection voltage signal, and determines a state of the reverse
25 connection protection relay 2 on the basis of a voltage value indicated by the converted
11
detection power signal. As the state of the reverse connection protection relay 2, for
example, presence or absence of an open failure and/or presence or absence of a shortcircuit failure is detected. A specific example of a method for determining the state of
the reverse connection protection relay 2 will be described later.
5 [0023]
The control device 4 may acquire a notification signal for providing a notification
of the determined state and output the acquired notification signal to a notifier 16. The
notifier 16 provides a notification of the state of the reverse connection protection relay 2
on the basis of the notification signal input from the control device 4. The notifier 16
10 may be a member that can present information to a user, for example, a light emitting diode
or a speaker. When a light emitting diode and a speaker are used as the notifier 16, DC
power and an acoustic signal are used, respectively. The light emitting diode emits light
according to DC power supplied from the control device 4. The speaker emits sound on
the basis of an acoustic signal input from the control device 4. As the notifier 16, for
15 example, a warning lamp, an audio speaker, or the like disposed in front of a driver's seat
of the vehicle may be applied. The notifier 16 may be integrated with the electronic
control device 1 or may be configured separately.
[0024]
The control device 4 controls an operation of the electric motor drive circuit 5 on
20 the basis of a known control method. The control device 4 controls the electric motor
drive circuit 5 on the basis of, for example, an ignition signal input to the control device 4.
The control device 4 causes the electric motor drive circuit 5 to operate the electric motor
7 when a voltage of the ignition signal is High. At this time, the control device 4
generates a drive control signal for instructing the operation of the electric motor 7, and
25 outputs the generated drive control signal to the electric motor drive circuit 5. When the
12
voltage of the ignition signal is Low, the control device 4 causes the electric motor drive
circuit 5 to stop the operation of the electric motor 7. At this time, the control device 4
stops outputting the drive control signal to the electric motor drive circuit 5.
[0025]
5 Various signals are input to the control device 4 from devices included in the
vehicle as vehicle-side input signals. The vehicle-side input signals include a torque
signal from a torque sensor that detects a steering operation, a vehicle speed signal from a
vehicle speed sensor, and the like. The control device 4 may execute an arithmetic
process and a drive instruction for driving an operation mechanism of the vehicle using the
10 vehicle-side input signals.
[0026]
The electric motor drive circuit 5 drives the electric motor 7 under control of the
control device 4. As a power supply state, for example, necessity of power supply to the
electric motor 7 is instructed. When a drive control signal indicating that an operation of
15 the electric motor 7 is necessary is input from the control device 4 to the electric motor
drive circuit 5, the electric motor drive circuit 5 supplies power from the power source 8
to the electric motor 7. When the drive control signal is not input from the control device
4 to the electric motor drive circuit 5, the electric motor drive circuit 5 stops power supply
from the power source 8 to the electric motor 7. The electric motor drive circuit 5
20 includes, for example, a bridge circuit and a motor relay switching element. The bridge
circuit includes a high-side switching element and a low-side switching element for
supplying power to each of one or more coils included in the electric motor 7. The motor
relay switching element cuts off power supplied to the electric motor 7 when the drive
control signal indicates that the operation is not necessary.
25
13
[0027]
When a switching control signal is input from the power source switch 9 to the
power source output holding circuit 6 or when a power request signal is input from the
control device 4 to the power source output holding circuit 6, the power source output
5 holding circuit 6 outputs an operation permission signal to the power source circuit 10.
The power request signal is an electric signal for indicating that power supply is necessary.
The power request signal indicates that power supply is necessary with a voltage being
High. The operation permission signal is an electric signal for instructing holding of an
operating voltage of the control device 4. The operation permission signal indicates
10 holding of the operating voltage with a voltage being High. The control device 4 outputs
the power request signal to the power source output holding circuit 6 during the operation.
[0028]
The power source output holding circuit 6 has, for example, a diode OR
configuration. The power source output holding circuit 6 includes, for example, two
15 diodes and one resistance element, and one end of each of the diodes serves as an input
end of the power source output holding circuit 6. The other end of each of the diodes is
connected to one end of the resistance element and serves as an output end of the power
source output holding circuit 6. The other end of the resistance element is grounded.
[0029]
20 According to this configuration, when a voltage of the switching control signal
input from power source switch 9 changes from High to Low, the power source circuit 10
can hold an operating voltage of the control device 4. Note that each of the power source
output holding circuit 6 and the power source circuit 10 may comprise a storage battery
that stores power supplied from the power source 8. Even if power from the power source
25 8 is interrupted, an output of the operation permission signal from the power source output
14
holding circuit 6 is maintained. At this time, power is supplied from the storage battery
of the power source circuit 10 to the control device 4. Thus, power supply from the power
source 8 via the power source circuit 10 is prevented from being immediately cut off during
the operation of the control device 4. Therefore, opportunities for termination of the
5 operation of the electric motor drive circuit 5 by the control device 4, a finalization of the
control device 4 itself, and the like can be ensured. The finalization comprises, for
example, a process of writing internal data of the control device 4 at that time into a
memory included in the control device 4. Immediately after the voltage of the switching
control signal changes from High to Low, the control device 4 can terminate the operation
10 at a predetermined timing without immediately terminating the operation.
[0030]
After completion of the finalization, the control device 4 terminates outputting the
power request signal to the power source output holding circuit 6. When an input of the
switching control signal from the power source switch 9 and an input of the power request
15 signal from the control device 4 are terminated, the power source output holding circuit 6
terminates outputting the operation permission signal to the power source circuit 10.
When no power is supplied from the power source 8 via the power source switch 9 and no
operation permission signal is input from the power source output holding circuit 6, the
power source circuit 10 terminates holding the operating voltage. At this time, power
20 supply from the power source circuit 10 to the control device 4 is terminated.
[0031]
Next, a circuit configuration example around the reverse connection protection
relay 2 according to the present embodiment will be described. FIG. 2 is a circuit diagram
illustrating a circuit configuration example around the reverse connection protection relay
25 2 according to the present embodiment. In the example of FIG. 2, a case where the
15
switching element 2s is a MOSFET, and a parasitic diode formed in the MOSFET is
applied as the rectifying element 14 is illustrated. The reverse connection protection
relay 2 is configured to include one MOSFET. A gate terminal of the MOSFET as the
switching element 2s is connected to the power source switch 9 via a resistance element
5 12 and a rectifying element 11. An anode and a cathode of a Zener diode 13 are connected
to a gate terminal and a source terminal of the MOSFET, respectively. A switching
control signal supplied from the power source switch 9 is applied to the gate terminal of
the MOSFET. The rectifying element 11 is a charge holding diode for holding a charge
when a voltage of the switching control signal is Low. The resistance element 12 is a
10 current limiting resistor for preventing an excessive current. The Zener diode 13 is
provided to avoid a reverse flow of a current due to the switching control signal, thereby
protecting the electric motor drive circuit 5l.
[0032]
According to the configuration of FIG. 2, the source terminal and the drain
15 terminal of the MOSFET as the switching element 2s are electrically connected (ON) while
a voltage of the switching control signal is High. The source terminal of the MOSFET is
cut off from the drain terminal (OFF) while the voltage of the switching control signal is
Low. Note that, in the example of FIG. 2, the rectifying element 11, the resistance
element 12, and the Zener diode 13 are not essential. Some or all of the rectifying element
20 11, the resistance element 12, and the Zener diode 13 may be omitted, or may be replaced
with other members.
[0033]
Next, a specific example of a method for determining a state of the reverse
connection protection relay 2 will be described. FIG. 3 is an explanatory diagram for
25 describing a specific example of the method for determining a state of the reverse
16
connection protection relay 2 according to the present embodiment. First, a specific
example of a method for detecting an open failure as a state of the reverse connection
protection relay 2 will be described. The open failure of the reverse connection protection
relay 2 refers to a failure in which connection between both ends of the switching element
5 2s is cut off (OFF) when both ends of the switching element 2s should be electrically
connected (ON). In the following description, it is assumed that power is initially
supplied from the power source 8 to the power source circuit 10 via the power source
switch 9, the control device 4 operates, and the electric motor drive circuit 5 does not
operate.
10 [0034]
FIG. 3 illustrates time courses of the switching control signal, a state of the reverse
connection protection relay, the operation permission signal, and an operation state of the
control device. In the illustrated example, a voltage of the switching control signal
supplied from the power source switch 9 is initially High. When no open failure occurs,
15 both ends of the reverse connection protection relay 2 are electrically connected (ON).
Thus, a current from a positive electrode terminal to a negative electrode terminal of the
power source 8 passes through the switching element 2s. When an open failure occurs,
connection between both ends of the reverse connection protection relay 2 is cut off (OFF).
Therefore, a current from a positive electrode terminal to a negative electrode terminal of
20 the power source 8 passes through the rectifying element 14 connected in parallel with the
switching element 2s. Accordingly, a potential difference generated between both ends
of the reverse connection protection relay 2 is different between the case where a current
passes through the switching element 2s and the case where the current passes through the
rectifying element 14.
25
17
[0035]
As an example, it is assumed that a resistance between a drain and a source of the
MOSFET as the switching element 2s is 1 mΩ, a forward voltage Vf of the parasitic diode
as the rectifying element 14 is 700 mV, and power consumption of the electronic control
5 device 1 is 1 A. When a current passes through the MOSFET, the potential difference is
1 mV. When a current passes through the parasitic diode, the potential difference
corresponds to 700 mV, which is a forward voltage of the parasitic diode. The forward
voltage depends on characteristics of each rectifying element 14, but has a value
sufficiently larger than the potential difference when a current passes through the switching
10 element 2s. A reference potential may be preset such that a voltage corresponding to this
potential difference can be detected by the voltage detector 3.
[0036]
As illustrated in FIG. 1, a reference potential GND of the voltage detector 3 is set
so as to be equal to a potential of a negative electrode of the power source 8. A reference
15 potential GND_PCB of a control component including the power source circuit 10 and the
control device 4 is set so as to be equal to a potential between the reverse connection
protection relay 2 and the electric motor drive circuit 5. A position where the reference
potential GND is set and a position where the reference potential GND_PCB is set are
separated across both ends of the reverse connection protection relay 2.
20 [0037]
As described above, a potential difference generated between the reference
potential GND and the reference potential GND_PCB is significantly different between
the case where an open failure occurs in the reverse connection protection relay 2 and the
case where the open failure does not occur in the reverse connection protection relay 2.
25 Therefore, the control device 4 determines presence or absence of an open failure of the
18
switching element 2s on the basis of a detection voltage signal input from the voltage
detector 3. A voltage based on the reference potential GND_PCB is a potential difference
between both ends of the reverse connection protection relay 2. More specifically, the
control device 4 compares a voltage indicated by the detection voltage signal with a preset
5 open failure threshold, and can determine presence or absence of an open failure by
whether or not the voltage indicated by the detection voltage signal is higher than the open
failure threshold. The open failure threshold may be preset between a voltage (potential
difference) detected in case of an open failure and a voltage (potential difference) detected
not in case of the open failure.
10 [0038]
Note that, when the electric motor 7 is driven in a state where an open failure
occurs in the reverse connection protection relay 2, a drive current passes through the
rectifying element 14. Power consumption of the rectifying element 14 corresponds to a
product of a potential difference between both ends of the rectifying element 14 and the
15 drive current. The power consumption is larger than power consumption of the switching
element 2s when the drive current passes through the switching element 2s. An increase
in calorific value may cause abnormal heat generation, leading to failure, smoking, or
ignition. Therefore, the control device 4 may determine presence or absence of an open
failure of the reverse connection protection relay 2 before the operation of the electric
20 motor drive circuit 5 starts. When determining occurrence of an open failure, the control
device 4 does not have to output a drive control signal to the electric motor drive circuit 5
regardless of whether or not an ignition signal is input. Thus, abnormal heat generation
due to current flow to the rectifying element 14 can be avoided without operating the
electric motor drive circuit 5.
25
19
[0039]
Next, a specific example of a method for detecting a short-circuit failure in the
reverse connection protection relay 2 will be described. The short-circuit failure in the
reverse connection protection relay 2 refers to a failure in which both ends of the switching
5 element 2s are electrically connected (ON) when connection between both ends of the
switching element 2s should be cut off (OFF). In the following description, as illustrated
in FIG. 3, it is assumed that a voltage of a switching control signal from the power source
switch 9 changes from High to Low at time T0. At this time, a voltage of an operation
permission signal output from the power source output holding circuit 6 is maintained at
10 High. Therefore, even when the time passes T0, the operation of the control device 4
continues. The control device 4 terminates the operation of the electric motor drive
circuit 5 and performs a finalization of the control device 4. Thereafter, at time T1, the
control device 4 terminates the operation. At this time, the voltage of the operation
permission signal output from the power source output holding circuit 6 changes from High
15 to Low. The control device 4 can ensure an opportunity to execute failure detection of
the reverse connection protection relay 2 in an output holding period from time T0 to time
T1.
[0040]
Since the voltage of the control signal is Low in the output holding period,
20 connection between both ends of the switching element 2s is cut off (OFF) unless a shortcircuit failure occurs. Therefore, a current from a positive electrode terminal to a negative
electrode terminal of the power source 8 passes through the rectifying element 14. On
the other hand, when a short-circuit failure occurs, the current from the positive electrode
terminal to the negative electrode terminal of the power source 8 passes through the
25 switching element 2s. As described above, a potential difference between both ends of
20
the reverse connection protection relay 2 varies depending on whether the current passes
through the rectifying element 14 or passes through the switching element 2s.
[0041]
As an example, it is assumed that a resistance between a drain and a source of the
5 MOSFET as the switching element 2s is 1 mΩ, a forward voltage Vf of the parasitic diode
as the rectifying element 14 is 700 mV, and power consumption of the electronic control
device 1 is 1 A. When a current passes through the MOSFET, the potential difference is
1 mV. When a current passes through the parasitic diode, the potential difference
corresponds to 700 mV, which is a forward voltage of the parasitic diode.
10 [0042]
Thus, the control device 4 may determine presence or absence of a short-circuit
failure in the switching element 2s on the basis of a detection voltage signal input from the
voltage detector 3. The detection voltage signal indicates a voltage detected by the
voltage detector 3. More specifically, the control device 4 compares a voltage indicated
15 by the detection voltage signal with a preset short-circuit failure threshold, to determine
presence or absence of a short-circuit failure based on whether or not the voltage indicated
by the detection voltage signal is lower than the short-circuit failure threshold. The shortcircuit failure threshold may be preset a value between a voltage (potential difference)
detected in case of short-circuit failure and a voltage (potential difference) detected not in
20 case of the short-circuit failure. In addition, as described above, the reference potential
GND of the voltage detector 3 may be preset so as to be equal to a potential of the negative
electrode of the power source 8. In addition, a reference potential GND_PCB of a control
component including the power source circuit 10 and the control device 4 is set so as to be
equal to a potential between the reverse connection protection relay 2 and the electric motor
25 drive circuit 5. With this setting, a voltage indicated by the detection voltage signal
21
corresponds to a potential difference between both ends of the reverse connection
protection relay 2.
[0043]
When determining a short-circuit failure, the control device 4 supplies DC power
5 to a warning lamp mounted on the vehicle, for example, as a notification signal for
providing a notification of the short-circuit failure. The warning lamp emits light
according to DC power from the control device 4. A driver who has visually recognized
the light-emitting warning lamp is notified of occurrence of the short-circuit failure.
When an ignition switch is applied as an example of the power source switch 9, protection
10 from a current by battery connection as the power source 8 is provided during an ignition
OFF period. The ignition OFF period corresponds to a duration when an ignition signal
with a High voltage is not input. Generally, the battery is not replaced while the vehicle
is traveling. Therefore, it can be practically sufficient that a short-circuit failure is
detected during the ignition OFF period.
15 [0044]
Note that the above description exemplifies a case where the reverse connection
protection relay 2 is driven on the basis of a switching control signal from the power source
switch 9 in place of power supplied from the power source 8, and an operating voltage of
the control device 4 is held using the power source output holding circuit 6. When power
20 is not supplied from the power source 8, even if electrical connection between both ends
of the reverse connection protection relay is cut off using the switching control signal, the
operating voltage of the control device 4 is maintained by the power source output holding
circuit 6. Even in such a case, the control device 4 can autonomously detect a shortcircuit failure in the reverse connection protection relay 2.
25 [0045]
22

A second embodiment will be described with reference to the drawings. The
following description will mainly focus on a difference from the first embodiment.
Unless otherwise specified, the description in the first embodiment is applied to other
5 matters. An electronic control device 1 according to the present embodiment can detect
presence or absence of a short-circuit failure as a state of a reverse connection protection
relay 2 even in a case where power supply from a power source 8 is started in addition to
a case where the power supply from the power source 8 is cut off. Thereafter, opening
and closing of the reverse connection protection relay 2 are controlled on the basis of a
10 switching control signal.
[0046]
FIG. 4 is a circuit diagram illustrating a configuration example of the electronic
control device 1 according to the present embodiment.
The electronic control device 1 according to the present embodiment includes a
15 reverse connection protection relay drive control circuit 24 in addition to the reverse
connection protection relay 2, a voltage detector 3, a control device 4, an electric motor
drive circuit 5, a power source output holding circuit 6, and a power source circuit 10.
The reverse connection protection relay drive control circuit 24 is disposed between and
connected to a power source switch 9 and the reverse connection protection relay 2.
20 When receiving, as an input, a switching control signal indicating power supply on from
the power source switch 9 and a switching command signal indicating a switching
command for the reverse connection protection relay 2 from the control device 4, the
reverse connection protection relay drive control circuit 24 outputs the switching control
signal indicating power supply on to the reverse connection protection relay 2. When
25 receiving a switching control signal indicating power supply off from the power source
23
switch 9, or when not receiving a switching command signal indicating a switching
command for the reverse connection protection relay 2 from the control device 4, the
reverse connection protection relay drive control circuit 24 outputs the switching control
signal indicating power supply off to the reverse connection protection relay 2. Necessity
5 of the switching command is indicated by, for example, whether a voltage of the switching
command signal is High or Low.
[0047]
Therefore, when the switching command is acquired from the control device 4,
the reverse connection protection relay drive control circuit 24 can control opening and
10 closing of the reverse connection protection relay 2 according to the switching control
signal from the power source switch 9. When the switching command is not acquired,
the reverse connection protection relay drive control circuit 24 cuts off connection between
both ends of the reverse connection protection relay 2 regardless of whether or not a
switching control signal having a High voltage is input. In this state, the control device
15 4 can determine presence or absence of a short-circuit failure in the reverse connection
protection relay 2 on the basis of a voltage indicated by a detection power signal input from
the voltage detector 3. After determining presence or absence of a short-circuit failure,
the control device 4 outputs a switching command signal indicating a switching command
for the reverse connection protection relay 2 to the reverse connection protection relay
20 drive control circuit 24. The switching command is represented, for example, with a
voltage of the switching command signal being High. The control device 4 includes, for
example, a general purpose input/output (GPIO) port, and can output the switching
command signal using the GPIO.
[0048]
25 Note that the control device 4 executes an initialization process when power
24
supply from the power source circuit 10 is started. The initialization process includes,
for example, processes such as reading of internal data stored in a memory and detection
of various devices connected to the control device 4. After completing the initialization
process, the control device 4 can determine presence or absence of a short-circuit failure.
5 After determining that there is no short-circuit failure, the control device 4 outputs a
switching command signal to the reverse connection protection relay drive control circuit
24. As a result, opening and closing of the reverse connection protection relay 2 based
on the switching control signal from the power source switch 9 can be controlled. At this
stage, the control device 4 may start control of the electric motor drive circuit 5 based on
10 an ignition signal.
[0049]
Next, a specific example of a method for detecting a short-circuit failure in the
reverse connection protection relay 2 will be described. FIG. 5 is an explanatory diagram
for describing an example of a method for detecting a short-circuit failure in the reverse
15 connection protection relay 2 according to the present embodiment. In the following
description, it is assumed that power is not initially supplied from the power source 8 to
the power source circuit 10 via the power source switch 9, and both the control device 4
and the electric motor drive circuit 5 do not operate. FIG. 5 illustrates time courses of the
switching control signal, an output of the power source circuit, an operation state of the
20 control device 4, the switching command, and a state of the reverse connection protection
relay 2. In the illustrated example, a voltage of the switching control signal supplied from
the power source switch 9 is initially Low. When a short-circuit failure does not occur,
electrical connection between both ends of the reverse connection protection relay 2 is cut
off (OFF). In this state, power is not supplied from the power source 8 to the power
25 source circuit 10 via the power source switch 9. Therefore, a voltage of power supplied
25
from the power source circuit 10 to the control device 4 is 0 V (OFF). At this time, since
the control device 4 does not operate (OFF), the switching command signal is not output
from the control device 4 (OFF).
[0050]
5 Next, it is assumed that the voltage of the switching control signal from the power
source switch 9 changes from Low to High at time T0. At this time, a voltage of power
supplied from the power source circuit 10 to the control device 4 starts to rise from 0 V
(OFF) and reaches a operating voltage (ON) at time T1, the operating voltage preset in the
control device 4. At this time, the voltage is stabilized, and an initialization process is
10 started as an operation of the control device 4 (ON). After the initialization process is
ended, at time T2, the control device 4 starts outputting a switching command signal
indicating a switching command to the reverse connection protection relay drive control
circuit 24 (ON). At this time, the reverse connection protection relay drive control circuit
24 starts outputting a switching control signal having a High voltage to the reverse
15 connection protection relay 2. If no short-circuit failure occurs, both ends of the reverse
connection protection relay 2 begin to change from a cut-off state (OFF) to an electrically
connected state (ON). Therefore, the control device 4 can determine presence or absence
of a short-circuit failure in the reverse connection protection relay 2 on the basis of a
voltage value indicated by a detection power signal input from the voltage detector 3 during
20 a period until the switching command signal is output at time T2 after the initialization
process is ended.
[0051]
In this period, since the power source circuit 10 and the control device 4 operate,
a current is generated from a positive electrode terminal to a negative electrode terminal
25 of the power source 8. When no short-circuit failure occurs in the reverse connection
26
protection relay 2, connection between both ends of the switching element 2s should be
cut off (OFF). In this state, the generated current passes through the rectifying element
14 connected in parallel with the switching element 2s. When a short-circuit failure
occurs, both ends of the switching element 2s are electrically connected (ON). Therefore,
5 a current from a positive electrode terminal to a negative electrode terminal of the power
source 8 passes through the switching element 2s. Therefore, a potential difference
generated between both ends of the reverse connection protection relay 2 is different
between the case where a current passes through the rectifying element 14 and the case
where the current passes through the switching element 2s.
10 [0052]
As an example, it is assumed that a resistance between a drain and a source of the
MOSFET as the switching element 2s is 1 mΩ, a forward voltage Vf of the parasitic diode
as the rectifying element 14 is 700 mV, and power consumption of the electronic control
device 1 is 1 A. When a current passes through the parasitic diode, the potential
15 difference corresponds to 700 mV, which is a forward voltage of the parasitic diode.
When a current passes through the MOSFET, the potential difference is 1 mV.
[0053]
Therefore, the control device 4 determines presence or absence of a short-circuit
failure in the switching element 2s on the basis of a detection voltage signal input from the
20 voltage detector 3. More specifically, the control device 4 compares a voltage indicated
by the detection voltage signal with a preset short-circuit failure threshold, and can
determine presence or absence of a short-circuit failure by whether or not the voltage
indicated by the detection voltage signal is lower than the short-circuit failure threshold.
The short-circuit failure threshold may be preset between a voltage in case of a short-circuit
25 failures and a voltage not in case of the short-circuit failure.
27
[0054]
Accordingly, the reverse connection protection relay drive control circuit 24 can
control the electrical connection between both ends of the reverse connection protection
relay 2 to be cut off, even when power is supplied from the power source 8. Therefore,
5 the control device 4 can determine presence or absence of a short-circuit failure in the
reverse connection protection relay 2 even after power supplied from the power source 8
is consumed and the operation is started.
[0055]
Next, a modification of the electronic control devices 1 according to the above
10 embodiments will be described. The electronic control device 1 may include, for
example, any one of the power source switch 9, the electric motor 7, and the notifier 16,
or a combination of any of these, and may be integrally configured. The electronic
control device 1 may further include the power source 8. The electronic control device 1
may have a function of controlling another device mounted on the vehicle. The other
15 device may be, for example, any one of an acoustic device, an air conditioning device, a
navigation device, a driving assistance system, and the like, or a combination of any of
these. The electronic control device 1 may be configured as an electronic control unit
(ECU).
[0056]
20 The power source 8 is not limited to a portable power source such as a battery,
and may be a stationary power source. Power supply from the power source 8 to the
electronic control device 1 is not limited to wired power supply, and may be wireless power
supply. When a wireless charger is used as the power source 8, the electronic control
device 1 may include a wireless power receiver and receive power transmitted from the
25 wireless charger. The load is not limited to the electric motor drive circuit 5, and may be
28
another device as long as the device consumes power supplied from the power source 8.
The device serving as the load does not have to be configured integrally with the electronic
control device 1.
[0057]
5 The switching element 2s is not necessarily limited to a MOSFET, and may be
another type of bipolar transistor. The rectifying element 14 is not necessarily limited to
a diode, and may be a selenium rectifier or the like.
A display may be used as the notifier 16. The control device 4 may generate a
signal representing information indicating a determined state by characters, symbols, or
10 images as the above notification signal, and output the signal to the display. When a
speaker is used as the notifier 16, a signal representing the information indicating the
determined state by voice may be generated as the above signal and output to the speaker.
The notification information may include, in addition to the information indicating the
determined state, information indicating a countermeasure (for example, component
15 replacement or contact with a sales store) for the state.
[0058]
As described above, the electronic control device 1 according to the present
disclosure includes the reverse connection protection relay 2, the voltage detector 3, and
the control device 4. The reverse connection protection relay 2 comprises the switching
20 element 2s and the rectifying element 14, and the switching element 2s and the rectifying
element 14 are connected in parallel. A negative electrode of the rectifying element 14
and a positive electrode of the rectifying element 14 are connected to a negative electrode
of the power source 8 and a load (for example, the electric motor drive circuit 5),
respectively. The load is configured to consume power supplied from the power source
25 8. Opening and closing of the switching element 2s are controlled on the basis of a
29
switching control signal indicating presence or absence of power supply from the power
source. The voltage detector 3 is configured to detect a potential difference between both
ends of the reverse connection protection relay 2. The control device 4 is configured to
determine a state of the reverse connection protection relay 2 on the basis of the detected
5 potential difference.
In general, electrical resistance of the reverse connection protection relay 2
depends on a state of the reverse connection protection relay 2. According to this
configuration, the state of the reverse connection protection relay 2 is determined on the
basis of the potential difference generated between both ends of the reverse connection
10 protection relay 2 by a current through the reverse connection protection relay 2 in response
to power supply from the power source 8. Therefore, the state of the reverse connection
protection relay 2 is autonomously detected without an increase in circuit scale or cost.
[0059]
the control device 4 may detect presence or absence of an open failure as the state
15 of the reverse connection protection relay 2 in case of power supply from the power source
8.
According to this configuration, when electrical connection of both ends of the
reverse connection protection relay 2 is instructed, presence or absence of an open failure
can be determined on the basis of the potential difference between both ends of the reverse
20 connection protection relay 2.
[0060]
The electronic control device 1 may include the power source circuit 10 and the
power source output holding circuit 6. The power source circuit 10 may convert a power
source voltage of power supplied from the power source 8 into an operating voltage of the
25 control device 4. The power source output holding circuit 6 may cause the power source
30
circuit 10 to hold the operating voltage in case of interruption of power supply from the
power source 8. The control device 4 may detect presence or absence of a short-circuit
failure as a state of the reverse connection protection relay 2.
According to this configuration, even when the power supply from the power
5 source 8 is cut off, the operating voltage of the control device 4 is maintained. On the
other hand, control is performed such that electrical connection between both ends of the
reverse connection protection relay 2 is cut off. The control device 4 can determine
presence or absence of a short-circuit failure on the basis of the potential difference
between both ends of the reverse connection protection relay 2 without terminating the
10 operation.
[0061]
The electronic control device 1 may further comprise a drive control circuit (for
example, the reverse connection protection relay drive control circuit 24). The drive
control circuit may cause both ends of the switching element 2s to be electrically connected
15 in case of power supply from the power source 8 and the switching command is acquired
from the control device 4. The control device 4 may detect presence or absence of a
short-circuit failure as a state of the reverse connection protection relay 2 before the power
supply from the power source 8 and the switching command acquired from the control
device 4.
20 According to this configuration, even when power is supplied from the power
source 8, electrical connection between both ends of the switching element 2s is cut off at
a stage where a switching command is not acquired from the control device 4. Even
before a switching command is input, the control device 4 is operated by the power supply
from the power source 8, whereby presence or absence of a short-circuit failure can be
25 determined on the basis of a potential difference between both ends of the reverse
31
connection protection relay 2.
[0062]
A reference potential serving as a reference of the operating voltage of the control
device 4 and a reference potential of the voltage detector 3 may be separated across both
5 ends of the reverse connection protection relay 2.
According to this configuration, by setting the reference potential of the control
device 4 to one end of the reverse connection protection relay 2, the voltage detector 3 can
detect the voltage at the one end of the reverse connection protection relay 2 as a potential
difference between both ends of the reverse connection protection relay 2.
10 [0063]
The switching element 2s may be a MOSFET, and the rectifying element 14 may
be a parasitic diode formed by joining a source and a drain of the MOSFET.
According to this configuration, one MOSFET is configured as the reverse
connection protection relay 2. Reducing the number of components contributes to
15 miniaturization and cost reduction of the electronic control device 1.
[0064]
The load may be the electric motor drive circuit 5 that is configured to drive the
electric motor 7. Opening and closing of the switching element 2s may be controlled on
the basis of an ignition signal input from an ignition switch as the switching control signal.
20 According to this configuration, opening and closing of the switching element 2s
can avoid a reverse flow of a current to the electric motor drive circuit 5 due to a reverse
connection of the power source 8 in conjunction with power supply to the electric motor
drive circuit 5 by the ignition switch. In addition, a state of the reverse connection
protection relay 2 can be detected without delay by using the ignition signal in control of
25 the switching element 2s.
32
[0065]
Although the embodiments of the present disclosure have been described above,
the present disclosure is not limited to these embodiments and a modification thereof.
Addition, omission, replacement, and other changes of the configuration can be made
5 without departing from the gist of the present disclosure.
A direction of an arrow illustrated in the block diagrams and other drawings are
for convenience of description, and do not limit flow directions of information, data,
signals, and the like in implementation.
In addition, the present disclosure is not limited by the above description, but is
10 limited solely by the attached claims.
[Industrial Applicability]
[0066]
According to the electronic control device and the electronic control method
according to the present disclosure, a state of the reverse connection protection relay 2 is
15 determined on the basis of a potential difference generated between both ends of the
reverse connection protection relay 2 by a current through the reverse connection
protection relay 2 in response to power supply from the power source 8. Therefore, the
state of the reverse connection protection relay 2 is autonomously detected without an
increase in circuit scale or cost.
20 [Reference Signs List]
[0067]
1 Electronic control device
2 Reverse connection protection relay
2s Switching element
25 3 Voltage detector
33
4 Control device
5 Electric motor drive circuit
6 Power source output holding circuit
8 Power source
5 9 Power source switch
10 Power source circuit
11 Rectifying element
12 Resistance element
13 Zener diode
10 14 Rectifying element
24 Reverse connection protection relay drive control circuit

WE CLAIM:
[Claim 1]
An electronic control device comprising a reverse connection protection relay, a
voltage detector, and a control device, wherein
5 the reverse connection protection relay comprises a switching element and a
rectifying element,
the switching element and the rectifying element are connected in parallel,
a negative electrode of the rectifying element and a positive electrode of the
rectifying element are connected to a negative electrode of a power source and a load,
10 respectively,
the load is configured to consume power supplied from the power source,
opening and closing of the switching element are controlled on a basis of a
switching control signal indicating presence or absence of power supply from the power
source,
15 the voltage detector is configured to detect a potential difference between both
ends of the reverse connection protection relay, and
the control device is configured to determine a state of the reverse connection
protection relay on a basis of the potential difference.
[Claim 2]
20 The electronic control device according to claim 1, wherein
the control device is configured to detect presence or absence of an open failure
as the state of the reverse connection protection relay in case of power supply from the
power source.
[Claim 3]
25 The electronic control device according to claim 1 or 2, comprising a power
35
source circuit and a power source output holding circuit, wherein
the power source circuit is configured to convert a power source voltage of power
supplied from the power source into an operating voltage of the control device, and
the power source output holding circuit is configured to cause the power source
5 circuit to hold the operating voltage in case of interruption of power supply from the power
source, and
the control device is configured to detect presence or absence of a short-circuit
failure as the state of the reverse connection protection relay.
[Claim 4]
10 The electronic control device according to any one of claims 1 to 3, further
comprising a drive control circuit, wherein
the drive control circuit is configured to cause both ends of the switching element
to be electrically connected in case of power supply from the power source and a switching
command acquired from the control device, and
15 the control device is configured to detect presence or absence of a short-circuit
failure as the state of the reverse connection protection relay before the power supply from
the power source and the switching command acquired from the control device.
[Claim 5]
The electronic control device according to any one of claims 1 to 4, wherein
20 a reference potential serving as a reference of an operating voltage of the control
device and a reference potential of the voltage detector are separated across both ends of
the reverse connection protection relay.
[Claim 6]
The electronic control device according to any one of claims 1 to 5, wherein
25 the switching element is a metal-oxide-semiconductor field-effect transistor
36
(MOSFET), and
the rectifying element is a parasitic diode formed by joining a source and a drain
of the MOSFET.
[Claim 7]
5 The electronic control device according to any one of claims 1 to 6, wherein
the load is an electric motor drive circuit that is configured to drive an electric
motor, and
opening and closing of the switching element are controlled on a basis of an
ignition signal input from an ignition switch as the switching control signal.
10 [Claim 8]
An electronic control method in an electronic control device comprising a reverse
connection protection relay, a voltage detector, and a control device, wherein
the reverse connection protection relay comprises a switching element and a
rectifying element,
15 the switching element and the rectifying element are connected in parallel,
a negative electrode of the rectifying element and a positive electrode of the
rectifying element, the negative electrode of the rectifying element and the positive
electrode of the rectifying element, are connected to a negative electrode of a power source
and a load, respectively,
20 the load is configured to consume power supplied from the power source, and
opening and closing of the switching element are controlled on a basis of a
switching control signal indicating presence or absence of power supply from the power
source,
the method comprising:
25 a first step of detecting, by the voltage detector, a potential difference between
37
both ends of the reverse connection protection relay; and
a second step of determining, by the control device, a state of the reverse
connection protection relay on a basis of the potential difference.