FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ELECTRIC-VEHICLE-CONTROLLER AND METHOD OF CONTROLLING
REGENERATIVE ELECTRIC POWER;
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
Field
[0001] The present invention relates to an electric5 vehicle-controller that controls traveling of an electric
vehicle and also relates to a method of controlling
regenerative electric power.
Background
10 [0002] Railway operators are increasingly installing
train automatic stop-position controllers (TASCs). The
TASC is an operation support apparatus that causes a train
about to make a stop at a station to automatically brake
for stopping at a given position alongside a platform. For
15 the TASC, improvement of stopping accuracy is a pressing
need.
[0003] A technique disclosed in Patent Literature 1
below for an electric-vehicle-controller equipped with
regenerative braking improves the stopping accuracy of an
20 electric vehicle. Specifically, when a distance from one’s
own vehicle to a next stop position is shorter than a
distance from another vehicle to the next stop position, a
regeneration disabling voltage of the one’s own vehicle is
set higher than a regeneration disabling voltage of the
25 other vehicle through control in Patent Literature 1.
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Patent Application
30 Laid-open No. 2001-204102
Summary
Technical Problem

3
[0005] However, according to the technique of Patent
Literature 1, information on current positions of the one’s
own vehicle and the other vehicle is inevitable, and
without this information the control is not possible.
5 [0006] The present invention has been made in view of
the above, and an object of the present invention is to
obtain an electric-vehicle-controller that enables an
electric vehicle to have improved stopping accuracy without
using positional information.
10
Solution to Problem
[0007] In order to solve the above-stated problem and
achieve the object, an electric-vehicle-controller
according to the present invention includes: a filter
15 capacitor; a power converter; and a controller that
controls operation of the power converter. The filter
capacitor smooths an overhead line voltage output from an
overhead line. The power converter converts direct-current
power stored in the filter capacitor into alternating20 current power and supplies the alternating-current power
after the conversion to a motor installed in an electric
vehicle in driving the motor. The controller includes a
calculation unit that calculates, on the basis of speed
information indicating a traveling speed of the electric
25 vehicle, a squeezing start voltage that is set as a value
to start squeezing of regenerative electric power that is
generated during deceleration braking of the electric
vehicle. When the traveling speed has decreased to a first
speed or lower, the calculation unit changes the squeezing
30 start voltage to a second voltage that is higher than a
first voltage that is a default value.
Advantageous Effects of Invention

4
[0008] The present invention effects an improvement in
stopping accuracy of the electric vehicle without using
positional information.
5 Brief Description of Drawings
[0009] FIG. 1 is a diagram illustrating a configuration
of an electric vehicle driving system that includes an
electric-vehicle-controller according to an embodiment.
FIG. 2 is a diagram illustrating a configuration of a
10 controller according to the embodiment.
FIG. 3 is a first diagram that is used for describing
operation of an essential part of the controller according
to the embodiment.
FIG. 4 is a second diagram that is used in describing
15 the operation of the essential part of the controller
according to the embodiment.
FIG. 5 is a flowchart illustrating a flow of
processing in the controller according to the embodiment.
FIG. 6 is a third diagram that is used for describing
20 operation of the essential part of the controller according
to the embodiment.
FIG. 7 is a block diagram illustrating an example of a
hardware configuration that implements functions of the
controller according to the embodiment.
25 FIG. 8 is a block diagram illustrating another example
of the hardware configuration that implements the functions
of the controller according to the embodiment.
Description of Embodiment
30 [0010] With reference to the accompanying drawings, a
detailed description is hereinafter provided of an
electric-vehicle-controller and a method of controlling
regenerative electric power according to an embodiment of

5
the present invention. It is to be noted that the
following embodiment is not restrictive of the present
invention.
[0011] Embodiment.
5 FIG. 1 is a diagram illustrating a configuration of an
electric vehicle driving system 100 that includes an
electric-vehicle-controller according to an embodiment.
The electric vehicle driving system 100 in FIG. 1 includes:
an overhead line 1; a power collector 2; switches 3 and 4;
10 a filter reactor 5; a filter capacitor 6; an inverter 7; a
motor 8; and a controller 12.
[0012] The overhead line 1 applies a direct-current
power supply voltage between a high potential–side directcurrent bus line 14a and a low potential–side direct15 current bus line 14b. The switches 3 and 4 and the filter
reactor 5 are inserted in the high potential–side directcurrent bus line 14a. The switch 3 is, for example, a
high-speed circuit breaker. The switch 4 is, for example,
a line breaker. The filter capacitor 6 is connected
20 between the high potential–side direct-current bus line 14a
and the low potential–side direct-current bus line 14b.
The direct-current voltage output from the overhead line 1
is applied to the filter capacitor 6 via the power
collector 2 and the filter reactor 5. The filter capacitor
25 6 smooths the direct-current voltage output from the
overhead line 1. The filter reactor 5 and the filter
capacitor 6 constitute a filter circuit. The inverter 7 is
a power converter that converts direct-current power stored
in the filter capacitor 6 into alternating-current power.
30 The inverter 7 supplies the alternating-current power after
the conversion to the motor 8 that is installed in an
electric vehicle for driving the motor 8. The motor 8 is a
propulsion drive motor that provides the electric vehicle

6
with a driving force.
[0013] An overhead wire and a pantograph-shaped power
collector are illustrated respectively as the overhead line
1 and the power collector 2 in FIG. 1 but are not limiting.
5 The overhead line 1 may be replaced by a third rail that is
used on a subway or another, and the power collector 2 to
be used may be replaced by a power collector for the third
rail accordingly. While the overhead line 1 illustrated in
FIG. 1 is a direct-current overhead line, the overhead line
10 1 may be an alternating-current overhead line. In cases
where the overhead line 1 is the alternating-current
overhead line, a transformer is provided between the power
collector 2 and the switch 3 or between the switch 3 and
the switch 4 for stepping down an alternating-current
15 voltage received, and a converter is provided downstream of
the transformer for converting the alternating-current
voltage output from the transformer into a direct-current
voltage.
[0014] The electric vehicle driving system 100 includes
20 as various sensors: voltage detectors 9 and 10; a current
detector 11; and a speed detector 16. The voltage detector
9 detects a voltage between the direct-current bus lines
14a and 14b as an overhead line voltage. The voltage
detector 10 detects a filter capacitor voltage that is a
25 voltage of the filter capacitor 6. The current detector 11
detects a motor current that flows between the inverter 7
and the motor 8. The speed detector 16 detects a
rotational speed of the motor 8.
[0015] The overhead line voltage detected by the voltage
30 detector 9, the filter capacitor voltage detected by the
voltage detector 10, and the motor current detected by the
current detector 11 are input to the controller 12. The
rotational speed detected by the speed detector 16 is input

7
to the controller 12 as speed information indicating a
traveling speed of the electric vehicle.
[0016] Sensorless control is publicly known in electric
vehicles as a technique that does not use a speed sensor or
5 a position sensor but estimates a motor speed or a rotor
position in a motor and controls the motor on the basis of
information on the estimated motor speed or the estimated
position. Therefore, the speed detector 16 is not needed
in an electric vehicle to which the sensorless control is
10 applied.
[0017] FIG. 2 is a diagram illustrating a configuration
of the controller 12 according to the embodiment. The
controller 12 includes: an inverter control unit 12A that
controls operation of the inverter 7; and a squeezing start
15 voltage calculation unit 12B that is a calculation unit in
the embodiment. On the basis of the speed information
output from the speed detector 16, the squeezing start
voltage calculation unit 12B, which is described in detail
later, calculates a squeezing start voltage RS and outputs
20 the RS to the inverter control unit 12A.
[0018] On the basis of the overhead line voltage, the
filter capacitor voltage, the motor current, and the speed
information, the inverter control unit 12A: generates a
control signal GC for on-off control of a switching element
25 7a provided in the inverter 7; and outputs the control
signal GC to the inverter 7. Moreover, the inverter
control unit 12A controls, on the basis of the squeezing
start voltage RS and the filter capacitor voltage,
squeezing of regenerative electric power that is generated
30 during deceleration braking of the electric vehicle.
[0019] FIG. 3 is a first diagram that is used for
describing operation of an essential part of the controller
12 according to the embodiment. In FIG. 3, a horizontal

8
axis represents the traveling speed of the electric vehicle,
and a vertical axis represents the squeezing start voltage.
The squeezing start voltage is set as a value to start the
squeezing of the regenerative electric power that is
5 generated during deceleration braking of the electric
vehicle. Starting the squeezing of the regenerative
electric power when the filter capacitor voltage reaches
the squeezing start voltage is controlled by the inverter
control unit 12A.
10 [0020] During deceleration braking of the electric
vehicle, the traveling speed of the electric vehicle
decreases. As illustrated in FIG. 3, until the traveling
speed decreases and reaches a first speed K1, the squeezing
start voltage is set at a first voltage V1 that is a
15 default value. On the other hand, when the traveling speed
of the electric vehicle has decreased to the first speed K1
or lower, the squeezing start voltage is changed to a
second voltage V2 higher than the first voltage V1.
[0021] Therefore, the squeezing control of the
20 regenerative electric power according to the embodiment
refers to an operation mode below. During a period until
the traveling speed of the electric vehicle reaches the
first speed K1, the inverter control unit 12A starts the
squeezing control of the regenerative electric power when
25 the filter capacitor voltage increases and reaches the
first voltage V1. On the other hand, with the traveling
speed of the electric vehicle being the first speed K1 or
lower, the inverter control unit 12A starts the squeezing
control of the regenerative electric power when the filter
30 capacitor voltage reaches the second voltage V2. In other
words, in cases where the traveling speed of the electric
vehicle is the first speed K1 or lower, no squeezing
control of the regenerative electric power is performed

9
when the filter capacitor voltage is greater than or equal
to the first voltage V1 and less than the second voltage V2.
[0022] With reference to FIG. 4, a description is
provided next of why the squeezing start voltage is set as
5 in FIG. 3. FIG. 4 is a second diagram that is used in
describing the operation of the essential part of the
controller 12 according to the embodiment. FIG. 4 is the
diagram that schematically illustrates a relationship
between the traveling speed of the electric vehicle and the
10 regenerative electric power that is generated during
deceleration braking of the electric vehicle. A horizontal
axis represents the traveling speed of the electric vehicle,
and a vertical axis represents the regenerative electric
power.
15 [0023] As illustrated in FIG. 4, the regenerative
electric power that is generated during deceleration
braking of the electric vehicle increases with a shift from
a higher-speed range to a medium-speed range. Therefore,
raising the squeezing start voltage should be avoided in
20 these ranges as there is an effect of an overhead line
voltage limit. On the other hand, the regenerative
electric power decreases with a shift from the medium-speed
range to a lower-speed range. Therefore, even when the
squeezing start voltage is raised in the lower-speed range,
25 the effect of the overhead line voltage limit is enabled to
be smaller.
[0024] The electric-vehicle-controller according to the
embodiment can have its function expressed in the form of a
flowchart. FIG. 5 is the flowchart that illustrates a flow
30 of processing in the controller 12 according to the
embodiment.
[0025] The inverter control unit 12A detects
regenerative braking caused by regenerative electric power

10
generated during deceleration braking of the electric
vehicle (step S11). Upon detecting the occurrence of the
regenerative braking, the inverter control unit 12A
compares the traveling speed of the electric vehicle with a
5 threshold (step S12). If the traveling speed of the
electric vehicle is greater than the threshold (Step S12,
No), a return is made to step S11 from where the processing
is repeated.
[0026] If the traveling speed of the electric vehicle
10 has decreased to the threshold or less (step S12, Yes), the
squeezing start voltage calculation unit 12B changes the
squeezing start voltage, which is set as the value to start
the squeezing of regenerative electric power, to the second
voltage higher than the first voltage that is the default
15 value (step S13), and the processing flow of FIG. 5 ends.
[0027] As the processing flow of FIG. 5 ends, the
inverter control unit 12A performs squeezing control of the
regenerative electric power with the second voltage to
which the changeover has been made at above-described step
20 S13. In cases where the traveling speed is equal to the
threshold in determination processing described at above
step S12, a determination is “Yes”; however, the
determination may be “No”. In other words, the
determination may be either “Yes” or “No” when the
25 traveling speed is equal to the threshold.
[0028] With reference to FIG. 6, a description is
provided next of a method of setting the squeezing start
voltage with blending control taken into consideration.
FIG. 6 is a third diagram that is used for describing
30 operation of the essential part of the controller 12
according to the embodiment. An upper part of FIG. 6
illustrates a relationship between the traveling speed of
the electric vehicle and braking force of the electric

11
vehicle. A lower part of FIG. 6 illustrates a relationship
between the traveling speed of the electric vehicle and the
squeezing start voltage. The blending control is a control
method that uses electric braking by a power conversion
5 apparatus and mechanical braking by a mechanical braking
controller in combination for carrying out stop control of
the electric vehicle with total braking force.
[0029] The upper part of FIG. 6 illustrates that the
mechanical braking is increased while the electric braking
10 is decreased when the traveling speed is Kb. In the
present specification, this traveling speed Kb is referred
to as “blending speed”.
[0030] The squeezing start voltage in the lower part of
FIG. 6 is maintained at the value of the first voltage V1
15 until the traveling speed of the electric vehicle decreases
and reaches the first speed K1. As the traveling speed of
the electric vehicle reaches the first speed K1, the
squeezing start voltage is linearly increased to the second
voltage V2, which is higher than the first voltage V1,
20 until the traveling speed of the electric vehicle decreases
further and reaches a second speed K2. The second speed K2
is smaller in value than the first speed K1 and is larger
in value than the blending speed Kb.
[0031] Setting the squeezing start voltage as in FIG. 6
25 is possible without being affected by the blending control.
Although the squeezing start voltage is linearly increased
from the first voltage V1 to the second voltage V2 in FIG.
6, this is not limiting. The squeezing start voltage may
be increased along a nonlinear function curve.
30 [0032] With reference to FIGS. 7 and 8, a description is
provided next of a hardware configuration that implements
the functions of the controller 12 according to the
embodiment. FIG. 7 is a block diagram illustrating an

12
example of the hardware configuration that implements the
functions of the controller 12 according to the embodiment.
FIG. 8 is a block diagram illustrating another example of
the hardware configuration that implements the functions of
5 the controller 12 according to the embodiment.
[0033] In order to implement the above-stated functions
of the controller 12, the configuration may include, as
illustrated in FIG. 7, a processor 300 that performs
operations, a memory 302 that stores programs to be read by
10 the processor 300, and an interface 304 through which
signals are input and output.
[0034] The processor 300 may be an arithmetic means such
as an arithmetic unit, a microprocessor, a microcomputer, a
central processing unit (CPU), or a digital signal
15 processor (DSP). An example of the memory 302 that can be
given is: a magnetic disk, a flexible disk, an optical disk,
a compact disk, a mini disk, a digital versatile disc
(DVD); or a nonvolatile or volatile semiconductor memory
such as a random-access memory (RAM), a read-only memory
20 (ROM), a flash memory, an erasable programmable ROM (EPROM),
or an electrically EPROM (EEPROM) (registered trademark).
[0035] The memory 302 stores programs that implement the
functions of the controller 12. The processor 300
transmits and receives necessary information through the
25 interface 304 and is capable of performing the above-stated
functions of the controller 12 by executing the programs
stored in the memory 302.
[0036] The processor 300 and the memory 302 that are
illustrated in FIG. 7 may be replaced by processing
30 circuitry 303 as in FIG. 8. The processing circuitry 303
corresponds to a single circuit, a composite circuit, an
application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), or a combination of these.

13
[0037] As described above, the controller according to
the embodiment includes the calculation unit that
calculates, on the basis of the speed information that
indicates the traveling speed of the electric vehicle, the
5 squeezing start voltage that is set as the value to start
the squeezing of regenerative electric power that is
generated during deceleration braking of the electric
vehicle. When the traveling speed has decreased to the
first speed or lower, this calculation unit changes the
10 squeezing start voltage to the second voltage higher than
the first voltage that is the default value. In this way,
an improvement is enabled in stopping accuracy of the
electric vehicle without use of positional information.
[0038] A problem with a conventional technique is that
15 without required information on current positions of one’s
own vehicle and another vehicle, no control is possible.
In contrast, the method according to the embodiment does
not require the use of positional information and thus is
applicable even to older types of electric vehicles that do
20 not have positional information.
[0039] Moreover, the conventional technique is not a
technique that uses speed information. For this reason,
even if the positional information is accurate,
regeneration may be disabled in cases where the traveling
25 speed is faster. In contrast, there is no such problem
with the method according to the embodiment because the
information on the traveling speed of the electric vehicle
is used.
[0040] The first speed at which the squeezing of
30 regenerative electric power is started is desirably faster
than the blending speed at which the blending control is
started. This enables the squeezing start voltage to be
set without being affected by the blending control.

14
[0041] The squeezing start voltage that is changed when
the traveling speed has decreased to the first speed or
lower desirably changes to the second voltage before the
traveling speed reaches the blending speed. Thus the
5 blending control does not affect the setting of the
squeezing start voltage even in cases where the squeezing
start voltage is gradually changed to the second voltage.
[0042] According to the embodiment, a method of
controlling regenerative electric power involves execution
10 of a first, a second, a third, and a fourth step below. At
the first step, the regenerative braking caused by the
regenerative electric power generated during deceleration
braking of the electric vehicle is detected. At the second
step when the occurrence of the regenerative braking is
15 detected, the traveling speed of the electric vehicle is
compared with the threshold. At the third step when the
traveling speed has decreased to the threshold or less, the
squeezing start voltage, which is set as the value to start
the squeezing of the regenerative electric power generated
20 during the deceleration braking of the electric vehicle, is
changed at to the second voltage higher than the first
voltage, which is the default value. At the fourth step,
the squeezing control of the regenerative electric power is
performed using the second voltage to which the changeover
25 has been made at the third step. These first through
fourth steps enable the improvement in stopping accuracy of
the electric vehicle without the use of positional
information.
[0043] The above configurations illustrated in the
30 embodiment are illustrative of contents of the present
invention, can be combined with other techniques that are
publicly known, and can be partly omitted or changed
without departing from the gist of the present invention.

15
Reference Signs List
[0044] 1 overhead line; 2 power collector; 3, 4
switch; 5 filter reactor; 6 filter capacitor; 7 inverter;
5 7a switching element; 8 motor; 9, 10 voltage detector; 11
current detector; 12 controller; 12A inverter control
unit; 12B squeezing start voltage calculation unit; 14a,
14b direct-current bus line; 16 speed detector; 100
electric vehicle driving system; 300 processor; 302
10 memory; 303 processing circuitry; 304 interface.

We Claim:
1. An electric-vehicle-controller comprising:
a filter capacitor adapted to smooth an overhead line
5 voltage output from an overhead line;
a power converter adapted to convert direct-current
power stored in the filter capacitor into alternatingcurrent power and supply the alternating-current power
after the conversion to a motor installed in an electric
10 vehicle in driving the motor; and
a controller adapted to control operation of the power
converter, wherein
the controller includes a calculation unit adapted to
calculate, on a basis of speed information indicating a
15 traveling speed of the electric vehicle, a squeezing start
voltage that is set as a value to start squeezing of
regenerative electric power that is generated during
deceleration braking of the electric vehicle, and
when the traveling speed has decreased to a first
20 speed or lower, the calculation unit changes the squeezing
start voltage to a second voltage higher than a first
voltage that is a default value.
2. The electric-vehicle-controller according to claim 1,
25 wherein
the controller is adapted to perform blending control
that uses electric braking and mechanical braking in
combination to carry out stop control of the electric
vehicle with total braking force, wherein
30 a value of the first speed that starts squeezing the
regenerative electric power is larger than a value of a
blending speed that starts the blending control.

17
3. The electric-vehicle-controller according to claim 2,
wherein
the squeezing start voltage that is changed when the
traveling speed has decreased to a first speed or lower
5 during the deceleration braking of the electric vehicle
changes to the second voltage before the traveling speed
reaches the blending speed.
4. A method of controlling regenerative electric power of
10 an electric vehicle, the method comprising:
a first step of detecting regenerative braking caused
by regenerative electric power generated during
deceleration braking of the electric vehicle;
a second step of comparing a traveling speed of the
15 electric vehicle with a threshold upon detecting the
regenerative braking;
a third step of changing a squeezing start voltage to
a second voltage higher than a first voltage when the
traveling speed has decreased to a threshold or less, the
20 squeezing start voltage being set as a value to start
squeezing of the regenerative electric power generated
during the deceleration braking of the electric vehicle,
the first voltage being a default value; and
a fourth step of performing squeezing control of the
25 regenerative electric power with the second voltage that
the changeover has been made to at the third step.