FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
POWER CONVERTER AND DRIVE CONTROLLER;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION
ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE
ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-
8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Title of Invention
POWER CONVERTER AND DRIVE CONTROLLER
5 Technical Field
[0001] The present disclosure relates to a power conversion device and a drive
control apparatus.
Background Art
[0002] Power conversion devices mounted on vehicles convert power supplied
10 from a power generator driven by an internal-combustion engine into power to be
supplied to a load, and supply the power resulting from the conversion to the load.
Patent Literature 1 describes an example of such power conversion devices. The power
conversion device described in Patent Literature 1 includes a converter that converts
alternating current (AC) power supplied from a power generator that is driven by an
15 internal-combustion engine to generate power into direct current (DC) power, and an
inverter that converts an output from the converter into AC power and supplies the AC
power to an induction motor. The induction motor is driven by the power supplied from
the inverter to produce the driving force of a vehicle.
Citation List
20 Patent Literature
[0003] Patent Literature 1: Unexamined Japanese Patent Application Publication
No. 2014-87116
Summary of Invention
Technical Problem
25 [0004] To cause the output torque of the power generator to reach a target torque,
the exciting current and the torque current of the power generator are controlled. More
specifically, a controller calculates an exciting current command value and a torque
3
current command value that cause the output torque of the power generator to reach the
target torque, and controls the converter based on the exciting current command value
and the torque current command value. Thus, the output torque of the power generator
is controlled.
5 [0005] In this case, the absolute value of the exciting current command value is
maintained at a constant value corresponding to the maximum torque of the power
generator. When a vehicle including the power conversion device described in Patent
Literature 1 coasts, the load of the power generator is low due to the target torque of the
power generator lower than the maximum torque. When the load of the power
10 generator is low, the absolute value of the exciting current command value is maintained
at a constant value corresponding to the maximum torque of the power generator as
described above. In this case, the efficiency of the power generator is lower than when
the load of the power generator high.
[0006] In response to the above issue, an objective of the present disclosure is to
15 provide a power conversion device and a drive control apparatus that improve the
efficiency of a power generator.
Solution to Problem
[0007] To achieve the above objective, a power conversion device according to an
aspect of the present disclosure includes a power converter, a target torque calculator, and
20 a power conversion controller. The power converter supplies exciting power to a power
generator drivable in an excitation state by a power source to generate power, converts
the power generated by the power generator into power to be supplied to a load, and
supplies the power resulting from the conversion to the load. The target torque
calculator calculates a target torque of the power generator in accordance with an
25 operation state of the load. During the power generation by the power generator, the
power conversion controller calculates a torque current command value and an exciting
current command value for causing an output torque of the power generator to approach
4
the target torque and controls the power converter based on the calculated torque current
command value and the calculated exciting current command value. Absolute values of
the torque current command value and the exciting current command value calculated by
the power conversion controller during the power generation by the power generator have
5 a positive correlation.
Advantageous Effects of Invention
[0008] In the above aspect of the present disclosure, the absolute values of the
torque current command value and the exciting current command value calculated by the
power conversion controller during the power generation by the power generator have a
10 positive correlation. This configuration enables improving the efficiency of the power
generator.
Brief Description of Drawings
[0009] FIG. 1 is a block diagram of a drive control apparatus according to
Embodiment 1;
15 FIG. 2 is a diagram of a power conversion device according to Embodiment 1,
illustrating the hardware configuration;
FIG. 3 illustrates timing charts of an operation of the drive control apparatus
according to Embodiment 1; (A) is a timing chart of a start command signal; (B) is a
timing chart of an operation command signal; (C) is a timing chart of a power source
20 rotational speed; (D) is a timing chart of a voltage between terminals of a filter capacitor;
(E) is a timing chart of an exciting current command value; and (F) is a timing chart of a
torque current command value;
FIG. 4 is a flowchart of an operation of initial excitation of a power generator
performed by the power conversion device according to Embodiment 1;
25 FIG. 5 is a flowchart of an operation of control of the power generator performed
by the power conversion device according to Embodiment 1;
FIG. 6 is a block diagram of a drive control apparatus according to Embodiment 2;
5
FIG. 7 illustrates timing charts of an operation of the drive control apparatus
according to Embodiment 2; (A) is a timing chart of a start command signal; (B) is a
timing chart of an operation command signal; (C) is a timing chart of a power source
rotational speed; (D) is a timing chart of a voltage between terminals of a filter capacitor;
5 (E) is a timing chart of an exciting current command value; and (F) is a timing chart of a
torque current command value;
FIG. 8 is a flowchart of an operation of control of the power generator performed
by a power conversion device according to Embodiment 2;
FIG. 9 is a block diagram of a drive control apparatus according to Embodiment 3;
10 and
FIG. 10 is a flowchart of an operation of control of the power generator performed
by a power conversion device according to Embodiment 3.
Description of Embodiments
[0010] A power conversion device and a drive control apparatus according to
15 embodiments of the present disclosure are described below in detail with reference to the
drawings. In the figures, the same or equivalent components are given the same
reference signs.
[0011] Embodiment 1
A drive control apparatus 1 according to Embodiment 1 is described using a drive
20 control apparatus mounted on a railway vehicle to drive the railway vehicle. As
illustrated in FIG. 1, the drive control apparatus 1 includes a power source 11, a power
source controller 12 that controls the power source 11, and a speed sensor 13 that detects
the rotational speed of the power source 11. The drive control apparatus 1 further
includes a power generator 14 that is driven in an excitation state by the power source 11
25 to generate power, and a power conversion device 20 that converts the power generated
by the power generator 14 into power to be supplied to a load 51 and supplies the power
resulting from the conversion to the load 51. The load 51 is, for example, a three-phase
6
induction motor that is driven by the power output from the power conversion device 20
to produce the driving force of the railway vehicle. In FIG. 1, dotted-line arrows
indicate various signals.
[0012] The power conversion device 20 includes a power converter 21 that
5 converts the power generated by the power generator 14 into the power to be supplied to
the load 51, and a target torque calculator 22 that calculates a target torque of the power
generator 14 in accordance with the operation state of the load 51. The power
conversion device 20 further includes a power conversion controller 23 that calculates a
torque current command value and an exciting current command value for causing an
10 output torque of the power generator 14 to approach the target torque, and controls the
power converter 21 based on the calculated torque current command value and the
calculated exciting current command value. The power conversion controller 23
controls the power converter 21, by vector control based on the torque current command
value and the exciting current command value, to control the output torque of the power
15 generator 14.
[0013] The absolute values of the torque current command value and the exciting
current command value calculated by the power conversion controller 23 during power
generation by the power generator 14 have a positive correlation. Thus, the absolute
values of the torque current and the exciting current of the power generator 14 vary
20 together in accordance with the operation state of the load 51. For example, when the
load of the power generator 14 decreases due to a decrease in the power consumption of
the load 51, the current effective value of the power generator 14 decreases, and thus the
efficiency of the power generator 14 is improved.
[0014] The power conversion device 20 preferably further includes a power storage
25 24 that supplies power for excitation of the power generator 14 to the power converter 21
while the power generator 14 is not generating power, a contactor MC1 that electrically
connects the power storage 24 to the power converter 21 or electrically disconnects the
7
power storage 24 from the power converter 21, and a contactor controller 25 that controls
the contactor MC1.
[0015] The power conversion device 20 further includes a current measurer CT1
that measures the value of each of U-phase current, V-phase current, and W-phase
5 current flowing in a circuit between the power generator 14 and the power converter 21, a
current measurer CT2 that measures the value of each of U-phase current, V-phase
current, and W-phase current flowing to the load 51 from the power converter 21, a
voltage measurer VT1 that measures the value of voltage between terminals of a filter
capacitor FC1 that is included in the power converter 21 and is described later, and a
10 speed sensor 26 that measures the rotational speed of the load 51.
[0016] The components of the drive control apparatus 1 are described in detail
below.
The power source 11 generates motive power. Examples of the power source 11
include internal-combustion engines such as a diesel engine and a gasoline engine. In
15 Embodiment 1, the power source 11 is an internal-combustion engine including a selfstarting motor. An output shaft of the power source 11 is connected to an input shaft of
the power generator 14. This structure transmits the rotation of the output shaft of the
power source 11 to the power generator 14.
[0017] The power source controller 12 receives a start command signal S1 from a
20 start switch on a non-illustrated driver cab, and receives an operation command signal S2
from a master controller on the driver cab. The start command signal S1 indicates the
start of the power source 11. The start command signal S1 is set to a low (L) level to
stop the power source 11. The start command signal S1 is set to a high (H) level to start
the power source 11. The operation command signal S2 includes a power notch
25 indicating the acceleration of the railway vehicle, a brake notch indicating the
deceleration of the railway vehicle, or the like.
[0018] When the start command signal S1 is at the H level, the power source
8
controller 12 starts the power source 11. More specifically, when the start command
signal S1 is at the H level, the power source controller 12 transmits a control signal to the
self-starting motor to start the self-starting motor. In response to the rotational force of
the self-starting motor being transmitted to the power source 11, the power source 11 is
5 started.
After the power source 11 is started, the power source controller 12 controls, based
on a target rotational speed corresponding to the power notch, the brake notch, or the like
indicated by the operation command signal S2, the power source 11 to cause the actual
rotational speed of the power source 11 acquired from the speed sensor 13 to approach
10 the target rotational speed. The power source controller 12 holds in advance, for each
power notch, each brake notch, and the like, a corresponding value of the target rotational
speed.
[0019] The speed sensor 13 includes a pulse generator (PG) mounted on the power
source 11. In response to a pulse signal output from the PG, the speed sensor 13
15 calculates the rotational speed of the power source 11 and outputs a signal indicating the
rotational speed of the power source 11. More specifically, the speed sensor 13 counts
the rising edges of the pulse signal at every measurement time period, and calculates the
rotational speed of the power source 11 based on the counted number of rising edges
within the measurement time period.
20 [0020] The power generator 14 is an induction generator. The input shaft of the
power generator 14 is joined to the output shaft of the power source 11. Upon being
driven by the power source 11 in an excitation state of receiving supply of exciting power
from the power conversion device 20, the power generator 14 generates AC power and
outputs the generated AC power to the power conversion device 20.
25 [0021] The components of the power conversion device 20 that receives power
from the power generator 14 are described in detail below.
The power converter 21 includes a first power converter 31 that converts the AC
9
power supplied from the power generator 14 through primary terminals into DC power,
the filter capacitor FC1 connected between secondary terminals of the first power
converter 31, and a second power converter 32 that converts the DC power supplied from
the first power converter 31 through the filter capacitor FC1 into three-phase AC power
5 to be supplied to the load 51, and supplies the three-phase AC power to the load 51.
[0022] The first power converter 31 includes multiple switching elements and is a
converter for bidirectional power conversion. The switching elements in the first power
converter 31 are, for example, insulated-gate bipolar transistors (IGBTs). The switching
elements are switched on or off based on switching control signals S3 transmitted from
10 the power conversion controller 23. Thus, the first power converter 31 converts the AC
power supplied from the power generator 14 into DC power or converts the DC power
supplied from the filter capacitor FC1 into AC power.
[0023] The filter capacitor FC1 is charged with power supplied from the first power
converter 31 or power supplied from the power storage 24.
15 [0024] The second power converter 32 converts the DC power supplied from the
first power converter 31 through the filter capacitor FC1 into three-phase AC power, and
supplies the three-phase AC power to the load 51. For example, the second power
converter 32 is a variable frequency inverter including the switching elements. The
second power converter 32 is controlled by a non-illustrated inverter controller.
20 [0025] The target torque calculator 22 calculates the target torque of the power
generator 14 in accordance with the operation state of the load 51. In Embodiment 1,
the target torque calculator 22 uses the output power of the power converter 21, or more
specifically, the output power of the second power converter 32 as a value representing
the operation state of the load 51. In particular, the target torque calculator 22 calculates
25 the torque of the three-phase induction motor that is the load 51 based on measured
values of phase current acquired from the current measurer CT2. The target torque
calculator 22 multiplies the calculated torque of the three-phase induction motor by the
10
rotational speed of the load 51 acquired from the speed sensor 26 to calculate the output
power of the second power converter 32. The target torque calculator 22 divides the
calculated output power of the second power converter 32 by the rotational speed of the
power source 11 acquired from the speed sensor 13 to calculate the target torque of the
5 power generator 14.
[0026] The start command signal S1 is supplied to the power conversion controller
23. The power conversion controller 23 acquires from the current measurer CT1 the
value of each of the U-phase current, the V-phase current, and the W-phase current
flowing between the power generator 14 and the power converter 21. The power
10 conversion controller 23 acquires the voltage between the terminals of the filter capacitor
FC1 from the voltage measurer VT1. The power conversion controller 23 acquires the
target torque of the power generator 14 from the target torque calculator 22.
[0027] The power conversion controller 23 outputs the switching control signals S3
that controls the timing of turning on or off the switching elements in the first power
15 converter 31, and controls the first power converter 31. More specifically, the power
conversion controller 23 allows the first power converter 31 to operate as a DC-AC
converter that converts the DC power supplied from the filter capacitor FC1 charged with
discharge power of the power storage 24 into AC power or an AC-DC converter that
converts the AC power supplied from the power generator 14 into DC power.
20 [0028] More specifically, the power conversion controller 23 calculates an exciting
current command value for initial excitation during initial excitation of the power
generator 14. During the initial excitation, the torque current command value is set to
zero. The power conversion controller 23 controls the first power converter 31 based on
the exciting current command value for initial excitation. Thus, the first power
25 converter 31 converts the DC power supplied from the filter capacitor FC1 charged with
discharge power of the power storage 24 into AC power, and supplies the AC power to
the power generator 14. This causes the initial excitation of the power generator 14, and
11
the power generator 14 starts to generate power.
[0029] The power conversion controller 23 calculates the torque current command
value and the exciting current command value for causing the output torque of the power
generator 14 to approach the target torque calculated by the target torque calculator 22
5 during power generation by the power generator 14. The power conversion controller
23 controls the first power converter 31 based on the calculated torque current command
value and the calculated exciting current command value. As described above, the
power conversion controller 23 controls the first power converter 31, by vector control
based on the torque current command value and the exciting current command value, to
10 control the output torque of the power generator 14.
[0030] The absolute values of the torque current command value and the exciting
current command value calculated by the power conversion controller 23 during power
generation by the power generator 14 have a positive correlation. In other words, as the
absolute value of the torque current command value decreases, the absolute value of the
15 exciting current command value decreases. As the absolute value of the torque current
command value increases, the absolute value of the exciting current command value
increases. The absolute value of the exciting current command value is preferably
greater than or equal to the absolute value of the torque current command value.
[0031] The absolute values of the torque current command value and the exciting
20 current command value calculated by the power conversion controller 23 during power
generation by the power generator 14 are preferably expected to be equal to each other.
More specifically, the power conversion controller 23 calculates the torque current
command value for causing the output torque of the power generator 14 to approach the
target torque calculated by the target torque calculator 22, and calculates the exciting
25 current command value with the absolute value expected to be equal to the absolute value
of the torque current command value.
[0032] The power storage 24 includes a rechargeable battery and is connected to
12
the filter capacitor FC1 in parallel. When the filter capacitor FC1 is charged with power
discharged by the power storage 24, the initial excitation of the power generator 14 can
be performed.
[0033] The contactor MC1 is located between the power storage 24 and the first
5 power converter 31. More specifically, one end of the contactor MC1 is connected to a
terminal of the power storage 24 and the other end of the contactor MC1 is connected to
one connection point of connection points between the secondary terminals of the first
power converter 31 and the primary terminals of the second power converter 32. For
example, the contactor MC1 is a direct current electromagnetic contactor.
10 [0034] The contactor controller 25 controls the contactor MC1. More specifically,
the contactor controller 25 transmits, to the contactor MC1, a contactor control signal S4
that turns on or off the contactor MC1. When the contactor controller 25 turns on the
contactor MC1, both the ends of the contactor MC1 are electrically connected, and the
power storage 24 is electrically connected to the power converter 21. When the
15 contactor controller 25 turns off the contactor MC1, both the ends of the contactor MC1
are insulated, and the power storage 24 is electrically disconnected from the power
converter 21.
[0035] The speed sensor 26 includes a PG mounted on the load 51. Based on a
pulse signal output from the PG mounted on the load 51, the speed sensor 26 calculates
20 the rotational speed of the load 51 and outputs a signal indicating the rotational speed of
the load 51. More specifically, the speed sensor 26 counts the rising edges of the pulse
signal at every measurement time period, and calculates the rotational speed of the load
51 based on the counted number of rising edges within the measurement time period.
[0036] The control components of the power conversion device 20 with the above
25 structure, or more specifically, the target torque calculator 22, the power conversion
controller 23, and the contactor controller 25 are implemented by a processor 61, a
memory 62, and an interface 63 as illustrated in FIG. 2. A bus 60 connects the
13
processor 61, the memory 62, and the interface 63 to one another. The bus 60 and the
interface 63 connect the processor 61 to a sensor group inside and outside the power
conversion device 20, or more specifically, to each of the current measurers CT1 and
CT2, the voltage measurer VT1, and the speed sensors 13 and 26. The processor 61
5 executes a program stored in the memory 62 to perform computation in each of the target
torque calculator 22, the power conversion controller 23, and the contactor controller 25.
[0037] The interface 63 connects the control components of the power conversion
device 20 to the sensor group inside and outside the power conversion device 20. The
interface 63 establishes communication and complies with multiple types of interface
10 standards, as appropriate. FIG. 2 illustrates the control components of the power
conversion device 20 including a single processor 61 and a single memory 62. The
control components of the power conversion device 20 may include multiple processors
61 and multiple memories 62.
[0038] The operation of the drive control apparatus 1 with the above structure is
15 described with reference to timing charts of (A) to (F) of FIG. 3 as an example in which
the power source 11 starts at a time T1.
Until the time T1, or in other words, while the power source 11 is being stopped,
the start command signal S1 is at the L level and the operation command signal S2
indicates a brake notch B1, as illustrated in (A) and (B) of FIG. 3. As illustrated in (C)
20 of FIG. 3, the power source 11 being stopped has a rotational speed RPM0. The filter
capacitor FC1 with the power source 11 being stopped is discharged, and the filter
capacitor FC1 in the discharged state has a voltage EFC0 between the terminals as
illustrated in (D) of FIG. 3.
[0039] With the power source 11 being stopped, the power generator 14 stops. As
25 illustrated in (E) of FIG. 3 illustrating the absolute value of the exciting current command
value, the exciting current command value during stop of the power generator 14 has an
absolute value Id0. As illustrated in (F) of FIG. 3 illustrating the absolute value of the
14
torque current command value, the torque current command value during stop of the
power generator 14 has an absolute value Iq0.
[0040] As illustrated in (A) of FIG. 3, when the start command signal S1 changes
from the L level to the H level at the time T1, the power source controller 12 starts the
5 power source 11. As illustrated in (C) of FIG. 3, the rotational speed of the power
source 11 starts to increase from the rotational speed RPM0. The rotational speed of the
power source 11 then reaches a rotational speed RPM1. The rotational speed RPM1 is
the rotational speed of the power source 11 when the power source 11 starts and the
operation command signal S2 indicates the brake notch B1.
10 [0041] When the start command signal S1 changes from the L level to the H level,
the contactor controller 25 turns on the contactor MC1. Thus, the voltage between the
terminals of the filter capacitor FC1 starts to increase from the voltage EFC0 at the time
T1, as illustrated in (D) of FIG. 3. When the voltage between the terminals of the filter
capacitor FC1 reaches a voltage EFC1 at a time T2, the power conversion device 20 can
15 perform the initial excitation of the power generator 14. The voltage EFC1 is the
voltage between the terminals of the filter capacitor FC1 when the filter capacitor FC1 is
charged to a level at which the initial excitation of the power generator 14 is performable.
The contactor controller 25 turns off the contactor MC1 at the time T2. Thus, the power
storage 24 is electrically disconnected from the power converter 21.
20 [0042] The initial excitation of the power generator 14 performed by the power
conversion device 20 is described with reference to FIG. 4. The power conversion
controller 23 in the power conversion device 20 repeats the processing in step S11 when
the start command signal S1 is not at the H level indicating the start of the power source
11 (No in step S11). The power conversion controller 23 acquires the voltage between
25 the terminals of the filter capacitor FC1 when the start command signal S1 is at the H
level indicating the start of the power source 11 (Yes in step S11), or more specifically,
after the time T1 in FIG. 3, and determines whether the voltage between the terminals of
15
the filter capacitor FC1 is greater than or equal to the voltage EFC1.
[0043] The power conversion controller 23 repeats the processing in step S12 when
the voltage between the terminals of the filter capacitor FC1 does not reach the voltage
EFC1 (No in step S12) as illustrated in FIG. 4, or more specifically, between the time T1
5 and the time T2 in FIG. 3. The power conversion controller 23 calculates the exciting
current command value for initial excitation (step S13) when the voltage between the
terminals of the filter capacitor FC1 is greater than or equal to the voltage EFC1 (Yes in
step S12) as illustrated in FIG. 4. The power conversion controller 23 controls the first
power converter 31 based on the exciting current command value for initial excitation
10 (step S14). When the processing in step S14 is ended, the power conversion device 20
ends the initial excitation of the power generator 14.
[0044] As described above, the absolute value of the exciting current command
value gradually increases from the time T2 as illustrated in (E) of FIG. 3 when the power
conversion controller 23 performs the initial excitation of the power generator 14. The
15 absolute value of the exciting current command value then reaches an absolute value Id1
at a time T3. When the absolute value of the exciting current command value reaches
the absolute value Id1, the initial excitation of the power generator 14 is complete, and
the power generator 14 starts to generate power.
[0045] Subsequently, the master controller inputs a power notch N2, and the
20 operation command signal S2 indicates the power notch N2. This time is defined as a
time T4. After the time T4, the power source controller 12 controls the power source 11
to cause the rotational speed of the power source 11 to approach a rotational speed RPM3
corresponding to the power notch N2. With an increase in the rotational speed of the
power source 11, the rotational speed of the power generator 14 increases, and the output
25 torque of the power generator 14 also increases.
[0046] When the power notch N2 is input at the time T4, the inverter controller
starts to control the second power converter 32. Thus, the second power converter 32
16
converts the DC power that is generated by the power generator 14, converted by the first
power converter 31, and supplied from the primary terminals through the filter capacitor
FC1 into power to be supplied to the load 51, and supplies the power resulting from the
conversion to the load 51. In other words, the output power of the second power
5 converter 32 increases after the time T4.
[0047] The power conversion device 20 controls the power generator 14 in
accordance with the target torque calculated based on the operation state of the load 51,
or more specifically, the output power of the second power converter 32. The control of
the power generator 14 by the power conversion device 20 is described with reference to
10 FIG. 5. For example, when the initial excitation of the power generator 14 is complete,
the power conversion device 20 starts the control in FIG. 5.
[0048] The target torque calculator 22 calculates the torque of the three-phase
induction motor that is the load 51 based on the measured values of phase current
acquired from the current measurer CT2. The target torque calculator 22 multiplies the
15 calculated torque of the three-phase induction motor by the rotational speed of the load 51
acquired from the speed sensor 26 to calculate the output power of the second power
converter 32 (step S21).
[0049] The target torque calculator 22 then divides the output power of the second
power converter 32 calculated in step S21 by the rotational speed of the power source 11
20 acquired from the speed sensor 13 to calculate the target torque of the power generator 14
(step S22).
[0050] The power conversion controller 23 calculates the torque current command
value and the exciting current command value for causing the output torque of the power
generator 14 to approach the target torque calculated in step S22 (step S23). The power
25 conversion controller 23 controls the first power converter 31 by vector control based on
the torque current command value and the exciting current command value calculated in
step S23 (step S24). When the processing in step S24 is complete, the components of
17
the power conversion device 20 repeat the above processing from step S21.
[0051] When the master controller inputs the power notch N2 at the time T4 in
FIG. 3, the output power of the second power converter 32 increases as described above.
Through the control of the power generator 14 by the power conversion device 20 in FIG.
5 5, the absolute value of the torque current command value increases as illustrated in (F)
of FIG. 3. More specifically, the absolute value of the torque current command value
increases from the absolute value Iq0 to an absolute value Iq2. The absolute values of
the torque current command value and the exciting current command value have a
positive correlation, and thus the absolute value of the exciting current command value
10 also increases as illustrated in (E) of FIG. 3. More specifically, the absolute value of the
exciting current command value increases from the absolute value Id1 to an absolute
value Id3. The absolute value Id3 preferably matches the absolute value Iq2.
[0052] Subsequently, when the master controller inputs a power notch N1, the
operation command signal S2 indicates the power notch N1. This time is defined as a
15 time T5. An acceleration indicated by the power notch N1 is lower than an acceleration
indicated by the power notch N2.
[0053] After the time T5, the power source controller 12 controls the power source
11 to cause the rotational speed of the power source 11 to approach a rotational speed
RPM2 corresponding to the power notch N1. The output power of the second power
20 converter 32 when the operation command signal S2 indicates the power notch N1 is
lower than the output power of the second power converter 32 when the operation
command signal S2 indicates the power notch N2. In other words, the output power of
the second power converter 32 decreases after the time T5.
[0054] The power conversion device 20 repeats the control of the power generator
25 14 in FIG. 5 after the time T5. The target torque calculated by the target torque
calculator 22 when the operation command signal S2 indicates the power notch N1 is
lower than the target torque calculated by the target torque calculator 22 when the
18
operation command signal S2 indicates the power notch N2. Thus, the absolute value of
the torque current command value decreases after the time T5 as illustrated in (F) of FIG.
3. More specifically, the absolute value of the torque current command value decreases
from the absolute value Iq2 to the absolute value Iq1. The absolute values of the torque
5 current command value and the exciting current command value have a positive
correlation, and thus the absolute value of the exciting current command value also
decreases after the time T5 as illustrated in (E) of FIG. 3. More specifically, the
absolute value of the exciting current command value decreases from the absolute value
Id3 to an absolute value Id2.
10 [0055] As described above, the absolute values of the torque current command
value and the exciting current command value vary together in accordance with the
operation state of the load 51 during power generation by the power generator 14, or
more specifically, after the time T3 in FIG. 3.
[0056] The power conversion device 20 according to Embodiment 1 calculates the
15 target torque of the power generator 14 in accordance with the operation state of the load
51 during power generation by the power generator 14, and calculates the torque current
command value and the exciting current command value in accordance with the target
torque as described above. The power conversion device 20 performs vector control
based on the calculated torque current command value and the calculated exciting current
20 command value, and controls the output torque of the power generator 14.
[0057] The absolute values of the torque current command value and the exciting
current command value calculated during power generation by the power generator 14
have a positive correlation. Thus, the absolute values of the torque current command
value and the exciting current command value vary together in accordance with the
25 operation state of the load 51, or more specifically, the output power of the second power
converter 32. Thus, the efficiency of the power generator 14 is higher than when vector
control is performed with the exciting current command value maintained constantly.
19
For example, when the power consumption at the load 51 decreases, in other words,
when the load of the power generator 14 decreases, the absolute values of the torque
current command value and the exciting current command value decrease. Thus, the
decrease in the current effective value of the power generator 14 improves the efficiency
5 of the power generator 14.
[0058] When the power conversion device 20 calculates the torque current
command value in accordance with the target torque and calculates the exciting current
command value with the absolute value expected to be equal to the absolute value of the
torque current command value, a reactive current decreases, and thus the efficiency of the
10 power generator 14 is improved.
[0059] Embodiment 2
The drive control apparatus may supply power to multiple loads. A drive control
apparatus 2 that supplies power to loads 51 and 52 according to Embodiment 2 is
described.
15 [0060] The drive control apparatus 2 illustrated in FIG. 6 includes a power
conversion device 30 that converts power generated by the power generator 14 into
power to be supplied to the loads 51 and 52 and supplies the power resulting from the
conversion to the loads 51 and 52. The load 52 is, for example, an in-vehicle apparatus
such as an illuminator and an air-conditioner. In Embodiment 2, the load 52 operates
20 under supply of three-phase AC power from the power conversion device 30.
[0061] The structure of the power conversion device 30 is described below
focusing on the differences from the power conversion device 20 according to
Embodiment 1.
The power conversion device 30 includes a power converter 27 that converts the
25 power generated by the power generator 14 into the power to be supplied to the load 51.
The power conversion device 30 further includes a current measurer CT3 that measures
the value of each of U-phase current, V-phase current, and W-phase current flowing in a
20
circuit between the power converter 27 and the load 52, and a voltage measurer VT2 that
measures the line voltage of three-phase AC power supplied to the load 52 from the
power converter 27.
[0062] In addition to the structure of the power converter 21 according to
5 Embodiment 1, the power converter 27 includes a second power converter 33 that
converts the DC power supplied from the first power converter 31 through the filter
capacitor FC1 into three-phase AC power to be supplied to the load 52, and supplies the
three-phase AC power to the load 52.
[0063] The second power converter 33 converts the DC power supplied from the
10 first power converter 31 through the filter capacitor FC1 into three-phase AC power, and
supplies the three-phase AC power to the load 52. For example, the second power
converter 33 is a constant-voltage constant-frequency inverter including multiple
switching elements. The second power converter 33 is controlled by a non-illustrated
inverter controller.
15 [0064] The target torque calculator 22 calculates the torque of the load 51 based on
the measured values of phase current acquired from the current measurer CT2, and
multiplies the calculated torque of the load 51 by the rotational speed of the load 51
acquired from the speed sensor 26 to calculate the output power of the second power
converter 32 in the same manner as in Embodiment 1. The target torque calculator 22
20 calculates each of a U-phase voltage, a V-phase voltage, and a W-phase voltage of the
three-phase AC power output by the second power converter 33 based on the line voltage
acquired from the voltage measurer VT2. The target torque calculator 22 then
calculates the output power of the second power converter 33 based on the calculated Uphase voltage, the calculated V-phase voltage, and the calculated W-phase voltage as
25 well as the U-phase current, the V-phase current, and the W-current phase acquired from
the current measurer CT3.
[0065] The target torque calculator 22 adds the calculated output power of the
21
second power converter 32 and the calculated output power of the second power
converter 33, and divides the sum by the rotational speed of the power source 11 acquired
from the speed sensor 13 to calculate the target torque of the power generator 14.
[0066] The control components of the power conversion device 30 with the above
5 structure, or more specifically, the target torque calculator 22, the power conversion
controller 23, and the contactor controller 25 are implemented by the same hardware
configuration as in Embodiment 1.
[0067] The operation of the drive control apparatus 2 with the above structure is
described with reference to timing charts of (A) to (F) of FIG. 7 as an example in which
10 the power source starts at a time T11.
Similarly to Embodiment 1, until the time T11, in other words, while the power
source 11 is being stopped, the start command signal S1 is at the L level and the operation
command signal S2 indicates the brake notch B1, as illustrated in (A) and (B) of FIG. 7.
As illustrated in (C) of FIG. 7, the power source 11 being stopped has a rotational speed
15 RPM0. The filter capacitor FC1 with the power source 11 being stopped is discharged,
and the filter capacitor FC1 in the discharged state has a voltage EFC0 between the
terminals as illustrated in (D) of FIG. 7.
[0068] With the power source 11 being stopped, the power generator 14 stops. As
illustrated in (E) of FIG. 7 illustrating the absolute value of the exciting current command
20 value, the exciting current command value during stop of the power generator 14 has an
absolute value Id0. As illustrated in (F) of FIG. 7 illustrating the absolute value of the
torque current command value, the torque current command value during stop of the
power generator 14 has an absolute value Iq0.
[0069] As illustrated in (A) of FIG. 7, when the start command signal S1 changes
25 from the L level to the H level at the time T11, the power source controller 12 starts the
power source 11, as in Embodiment 1. As illustrated in (C) of FIG. 7, the rotational
speed of the power source 11 starts to increase from the rotational speed RPM0 at the
22
time T11. The rotational speed of the power source 11 then reaches a rotational speed
RPM1. The rotational speed RPM1 is the rotational speed of the power source 11 when
the power source 11 starts and the operation command signal S2 indicates the brake notch
B1.
5 [0070] When the start command signal S1 changes from the L level to the H level,
the contactor controller 25 turns on the contactor MC1. Thus, the voltage across the
filter capacitor FC1 starts to increase from the voltage EFC0 at the time T11, as
illustrated in (D) of FIG. 7. When the voltage across the filter capacitor FC1 reaches a
voltage EFC1 at a time T12, the power conversion device 30 can perform the initial
10 excitation of the power generator 14. The contactor controller 25 turns off the contactor
MC1 at the time T12. Thus, the power storage 24 is electrically disconnected from the
power converter 27.
[0071] The power conversion device 30 performs the initial excitation of the power
generator 14 similarly to the power conversion device 20 according to Embodiment 1.
15 The absolute value of the exciting current command value gradually increases from the
time T12 as illustrated in (E) of FIG. 7 when the power conversion controller 23 in the
power conversion device 30 performs the initial excitation of the power generator 14.
The absolute value of the exciting current command value then reaches an absolute value
Id1 at a time T13. When the absolute value of the exciting current command value
20 reaches the absolute value Id1, the initial excitation of the power generator 14 is
complete, and the power generator 14 starts to generate power.
[0072] The inverter controller starts to control the second power converter 33 at the
time T13 and supplies power to the load 52, and the load 52 starts to operate. Thus, the
output power of the second power converter 33 increases.
25 [0073] The power conversion device 30 controls the power generator 14 in
accordance with the target torque calculated based on the operation state of the load 51,
or more specifically, the sum of the output power of the second power converters 32 and
23
33. The control of the power generator 14 performed by the power conversion device
30 is described with reference to FIG. 8. For example, when the initial excitation of the
power generator 14 is complete, the power conversion device 30 starts the control as
illustrated in FIG. 8.
5 [0074] The target torque calculator 22 calculates the output power of the second
power converter 32 based on the measured values of phase current acquired from the
current measurer CT2 and the rotational speed of the load 51 acquired from the speed
sensor 26, and calculates the output power of the second power converter 33 based on the
line voltage acquired from the voltage measurer VT2 and the phase current acquired from
10 the current measurer CT3 (step S31).
[0075] The target torque calculator 22 adds the output power of the second power
converters 32 and 33 calculated in step S31 (step S32).
[0076] The target torque calculator 22 calculates the target torque of the power
generator 14 based on the sum of the output power of the second power converters 32
15 and 33 calculated in step S32 (step S33).
[0077] The power conversion controller 23 calculates the torque current command
value and the exciting current command value for causing the output torque of the power
generator 14 to approach the target torque calculated in step S33 (step S34). The power
conversion controller 23 controls the first power converter 31 by vector control based on
20 the torque current command value and the exciting current command value calculated in
step S34 (step S35). When the processing in step S35 is complete, the components of
the power conversion device 30 repeat the above processing from step S31.
[0078] When the load 52 starts to operate at the time T13 in FIG. 7 as described
above, the output power of the second power converter 33 increases. As a result of the
25 control process for the power generator 14 performed by the power conversion device 30
as illustrated in FIG. 8, the absolute value of the torque current command value increases
as illustrated in (F) of FIG. 7. More specifically, the absolute value of the torque current
24
command value increases from the absolute value Iq0 to the absolute value Iq1. The
absolute values of the torque current command value and the exciting current command
value have a positive correlation, and thus the absolute value of the exciting current
command value also increases as illustrated in (E) of FIG. 7. More specifically, the
5 absolute value of the exciting current command value increases from the absolute value
Id1 to an absolute value Id2. The absolute value Id2 preferably matches the absolute
value Iq2.
[0079] Subsequently, when the master controller inputs a power notch N2, the
operation command signal S2 indicates the power notch N2. This time is defined as a
10 time T14. After the time T14, the power source controller 12 controls the power source
11 to cause the rotational speed of the power source 11 to approach a rotational speed
RPM3 corresponding to the power notch N2. With an increase in the rotational speed of
the power source 11, the rotational speed of the power generator 14 increases, and the
output torque of the power generator 14 also increases.
15 [0080] When the power notch N2 is input at the time T14, the inverter controller
starts to control the second power converter 32. Thus, the second power converter 32
converts the DC power that is generated by the power generator 14, converted by the first
power converter 31, and supplied from the primary terminals through the filter capacitor
FC1 into power to be supplied to the load 51, and supplies the power resulting from the
20 conversion to the load 51. In other words, the output power of the second power
converter 32 increases after the time T14.
[0081] The power conversion device 30 performs the control of the power
generator 14 in FIG. 8 after the time T14. The target torque calculated by the target
torque calculator 22 when the load 52 operates and the operation command signal S2
25 indicates the power notch N2 is higher than the target torque calculated by the target
torque calculator 22 when the load 52 operates and the operation command signal S2
indicates the brake notch B1. Thus, the absolute value of the torque current command
25
value increases after the time T14 as illustrated in (F) of FIG. 7. More specifically, the
absolute value of the torque current command value increases from the absolute value Iq1
to an absolute value Iq3. The absolute values of the torque current command value and
the exciting current command value have a positive correlation, and thus the absolute
5 value of the exciting current command value also increases after the time T14 as
illustrated in (E) of FIG. 7. More specifically, the absolute value of the exciting current
command value increases from the absolute value Id2 to an absolute value Id4. The
absolute value Id4 preferably matches the absolute value Iq3.
[0082] Subsequently, when the master controller does not input a power notch or a
10 brake notch, the operation command signal S2 indicates a notch N0. The notch N0
means that a vehicle is coasting. This time is defined as a time T15. After the time
T15, the rotational speed of the power source 11 is controlled to approach the rotational
speed RPM1 corresponding to the notch N0. The rotational speed of the power source
11 corresponding to the notch N0 is the same as the rotational speed of the power source
15 11 corresponding to the brake notch B1. As the rotational speed of the power source 11
decreases, the rotational speed of the power generator 14 decreases, and the output torque
of the power generator 14 also decreases.
[0083] The power conversion device 30 performs the control of the power
generator 14 in FIG. 8 after the time T15. The target torque calculated by the target
20 torque calculator 22 when the load 52 operates and the operation command signal S2
indicates the notch N0 is lower than the target torque calculated by the target torque
calculator 22 when the load 52 operates and the operation command signal S2 indicates
the power notch N2. Thus, the absolute value of the torque current command value
decreases after the time T15 as illustrated in (F) of FIG. 7. More specifically, the
25 absolute value of the torque current command value decreases from the absolute value
Iq3 to the absolute value Iq1. The absolute values of the torque current command value
and the exciting current command value have a positive correlation, and thus the absolute
26
value of the exciting current command value also decreases after the time T15 as
illustrated in (E) of FIG. 7. More specifically, the absolute value of the exciting current
command value decreases from the absolute value Id4 to the absolute value Id2. The
absolute value Id2 preferably matches the absolute value Iq1.
5 [0084] The power consumption of the load 52 then increases. This time is defined
as a time T16. The power conversion device 30 performs the control of the power
generator 14 in FIG. 8 after the time T16. When the power consumption of the load 52
increases while a railway vehicle is coasting, the target torque calculated by the target
torque calculator 22 increases. Thus, the absolute value of the torque current command
10 value increases after the time T16 as illustrated in (F) of FIG. 7. More specifically, the
absolute value of the torque current command value increases from the absolute value Iq1
to the absolute value Iq2. The absolute values of the torque current command value and
the exciting current command value have a positive correlation, and thus the absolute
value of the exciting current command value also increases after the time T16 as
15 illustrated in (E) of FIG. 7. More specifically, the absolute value of the exciting current
command value increases from the absolute value Id2 to an absolute value Id3. The
absolute value Id3 preferably matches the absolute value Iq2.
[0085] As described above, the absolute values of the torque current command
value and the exciting current command value vary together in accordance with the
20 operation states of the loads 51 and 52 during power generation by the power generator
14, or more specifically, after the time T13 in FIG. 7.
[0086] The power conversion device 30 according to Embodiment 2 calculates the
target torque of the power generator 14 in accordance with the operation states of the
loads 51 and 52 during power generation by the power generator 14, and calculates the
25 torque current command value and the exciting current command value in accordance
with the target torque, as described above. The power conversion device 30 performs
vector control based on the calculated torque current command value and the calculated
27
exciting current command value, and controls the power-generation torque of the power
generator 14.
[0087] The absolute values of the torque current command value and the exciting
current command value calculated during power generation by the power generator 14
5 have a positive correlation. Thus, the absolute values of the torque current command
value and the exciting current command value vary together in accordance with the
operation states of the loads 51 and 52, or more specifically, the sum of the output power
of the second power converters 32 and 33. Thus, the efficiency of the power generator
14 is higher than when vector control is performed with the exciting current command
10 value maintained constantly.
[0088] Embodiment 3
A method for calculating the target torque in accordance with the operation state of
the load 51 is not limited to the above examples. The value representing the operation
state of the load 51 may be the output power of the first power converter 31. A power
15 conversion device 40 and a drive control apparatus 3 including the power conversion
device 40 according to Embodiment 3 are described. The power conversion device 40
calculates the target torque in accordance with the output power of the first power
converter 31 and performs vector control in accordance with the target torque.
[0089] The drive control apparatus 3 illustrated in FIG. 9 includes the power
20 conversion device 40 that converts power generated by the power generator 14 into
power to be supplied to the load 51 and supplies the power resulting from the conversion
to the load 51.
[0090] The structure of the power conversion device 40 is described below
focusing on the differences from the power conversion device 20 according to
25 Embodiment 1.
The power conversion device 40 includes a current measurer CT4 that measures
the output current of the first power converter 31.
28
[0091] The target torque calculator 22 calculates the output power of the first power
converter 31 based on the measured values of current acquired from the current measurer
CT4 and the voltage between the terminals of the filter capacitor FC1 acquired from the
voltage measurer VT1. The target torque calculator 22 divides the calculated output
5 power of the first power converter 31 by the rotational speed of the power source 11
acquired from the speed sensor 13 to calculate the target torque of the power generator
14.
[0092] The control components of the power conversion device 40 with the above
structure, or more specifically, the target torque calculator 22, the power conversion
10 controller 23, and the contactor controller 25 are implemented by the same hardware
configuration as in Embodiment 1.
[0093] The operation of the drive control apparatus 3 including the power
conversion device 40 with the above structure is the same as in Embodiment 1 except the
method for calculating the target torque of the target torque calculator 22. The control
15 of the power generator 14 performed by the power conversion device 40 after the initial
excitation of the power generator 14 is complete is described with reference to FIG. 10.
[0094] The target torque calculator 22 calculates the output power of the first power
converter 31 based on the output current of the first power converter 31 acquired from the
current measurer CT4 and the voltage between the terminals of the filter capacitor FC1
20 acquired from the voltage measurer VT1 (step S41).
[0095] The target torque calculator 22 then divides the output power of the first
power converter 31 calculated in step S41 by the rotational speed of the power source 11
acquired from the speed sensor 13 to calculate the target torque of the power generator 14
(step S42).
25 [0096] The power conversion controller 23 calculates the torque current command
value and the exciting current command value for causing the output torque of the power
generator 14 to approach the target torque calculated in step S42 in the same manner as
29
Embodiment 1 (step S43). The power conversion controller 23 controls the first power
converter 31 by vector control based on the torque current command value and the
exciting current command value calculated in step S43 (step S44). When the processing
in step S44 is complete, the components of the power conversion device 40 repeat the
5 above processing from step S41.
[0097] The power conversion device 40 according to Embodiment 3 calculates the
torque current command value and the exciting current command value in accordance
with the target torque of the power generator 14 calculated based on the output power of
the first power converter 31, as described above. The power conversion device 20
10 performs vector control based on the calculated torque current command value and the
calculated exciting current command value, and controls the power-generation torque of
the power generator 14.
[0098] The absolute values of the torque current command value and the exciting
current command value calculated during power generation by the power generator 14
15 have a positive correlation. Thus, the absolute values of the torque current command
value and the exciting current command value vary together in accordance with the
operation state of the load 51, or more specifically, the output power of the first power
converter 31. Thus, the efficiency of the power generator 14 is higher than when vector
control is performed with the exciting current command value maintained constantly.
20 [0099] Embodiments of the present disclosure are not limited to the embodiments
described above. The hardware configuration and the flowcharts described above are
examples, and may be changed or modified as appropriate.
[0100] The drive control apparatuses 1 to 3 are not limited to use for a railway
vehicle, and can drive any vehicle such as an automobile, a ship, and an aircraft.
25 [0101] The power conversion devices 20, 30, and 40 can be installed at any position
such as under the floor, on the floor, and on the roof of the railway vehicle.
[0102] The circuit structures of the power conversion devices 20, 30, and 40 are
30
examples. The circuit structures of the power conversion devices 20, 30, and 40 may be
any circuit structure that can perform initial excitation of the power generator 14 and
control the output torque of the power generator 14.
[0103] The power conversion devices 20, 30, and 40 may include, instead of the
5 contactor MC1, any element that electrically connects the filter capacitor FC1 to the
power converters 21 and 27 or electrically disconnects the filter capacitor FC1 from the
power converters 21 and 27.
[0104] The target torque calculator 22 may acquire the rotational speed of the threephase induction motor that is the load 51 from an automatic train control (ATC), a train
10 information management system, or the like, and multiply the rotational speed of the
three-phase induction motor acquired from the ATC by the torque of the three-phase
induction motor calculated based on the measured values of phase current acquired from
the current measurer CT2 to calculate the output power of the second power converter 32.
[0105] The target torque calculator 22 may calculate the target torque based on the
15 effective power output by the second power converter 32 or the sum of the effective
power output by the second power converters 32 and 33.
[0106] A method for calculating the target torque performed by the target torque
calculator 22 is not limited to the above examples, and may be any method for calculating
the target torque in accordance with the operation state of the load 51. For example, the
20 target torque calculator 22 may acquire the operation command signal S2, estimate the
operation state of the load 51 in accordance with the operation command signal S2, and
calculate the target torque in accordance with the estimated operation state of the load 51.
[0107] The power storage 24 may be charged with the output power of the first
power converter 31 after the power generator 14 starts to generate power, or may be
25 charged with the power generated by the load 51 during braking of the railway vehicle.
In this case, the target torque calculator 22 may calculate the target torque in accordance
with the charge-discharge capacity of the power storage 24, in addition to the operation
31
states of the loads 51 and 52. For example, when the power storage 24 is charged with
the output power of the first power converter 31 after the power generator 14 starts to
generate power, the target torque calculator 22 in the power conversion device 20
according to Embodiment 1 may calculate the target torque based on the sum of the
5 output power of the second power converter 32 and power used to charge the power
storage 24.
[0108] The power conversion devices 20, 30, and 40 may not include the power
storage 24, and the filter capacitor FC1 may be charged with power supplied from an
external apparatus until the initial excitation of the power generator 14 can be performed.
10 [0109] Control by the contactor controller 25 is not limited to the above examples.
For example, the contactor controller 25 may acquire the rotational speed of the power
source 11 from the speed sensor 13 and turn on the contactor MC1 when the rotational
speed reaches a value that is expected to indicate the start of the power source 11. For
example, the contactor controller 25 may turn on the contactor MC1 after the start
15 command signal S1 changes from the L level to the H level and a predetermined time that
is longer than a time taken to start the power source 11 elapses.
[0110] Although the measurement of the U-phase current, the V-phase current, and
the W-phase current by the current measurers CT1 and CT2 is described, at least two of
the U-phase current, the V-phase current, and the W-phase current may be measured.
20 [0111] The loads 51 and 52 to which the drive control apparatuses 1 to 3 supply
power are not limited to the above examples, and may be any electronic apparatus that
consumes power.
[0112] The power source 11 is not limited to the above examples, and may be, for
example, an internal-combustion engine including no self-starting motor.
25 [0113] The foregoing describes some example embodiments for explanatory
purposes. Although the foregoing discussion has presented specific embodiments,
persons skilled in the art will recognize that changes may be made in form and detail
32
without departing from the broader spirit and scope of the invention. Accordingly, the
specification and drawings are to be regarded in an illustrative rather than a restrictive
sense. This detailed description, therefore, is not to be taken in a limiting sense, and the
scope of the invention is defined only by the included claims, along with the full range of
5 equivalents to which such claims are entitled.
Reference Signs List
[0114]
1, 2, 3 Drive control apparatus
11 Power source
10 12 Power source controller
13, 26 Speed sensor
14 Power generator
20, 30, 40 Power conversion device
21, 27 Power converter
15 22 Target torque calculator
23 Power conversion controller
24 Power storage
25 Contactor controller
31 First power converter
20 32, 33 Second power converter
51, 52 Load
60 Bus
61 Processor
62 Memory
25 63 Interface
CT1, CT2, CT3, CT4 Current measurer
FC1 Filter capacitor
33
MC1 Contactor
S1 Start command signal
S2 Operation command signal
S3 Switching control signal
5 S4 Contactor control signal
VT1, VT2 Voltage measurer

We Claim :
1. A power conversion device comprising:
a power converter to (i) supply exciting power to a power generator drivable in an
excitation state by a power source to generate power, (ii) convert the power generated by
5 the power generator into power to be supplied to a load, and (iii) supply the power
resulting from the conversion to the load;
a target torque calculator to calculate a target torque of the power generator in
accordance with an operation state of the load; and
a power conversion controller to, during the power generation by the power
10 generator, (i) calculate a torque current command value and an exciting current command
value for causing an output torque of the power generator to approach the target torque
and (ii) control the power converter based on the calculated torque current command
value and the calculated exciting current command value, wherein
absolute values of the torque current command value and the exciting current
15 command value calculated by the power conversion controller during the power
generation by the power generator have a positive correlation.
2. The power conversion device according to claim 1, wherein
the power converter includes
20 a first power converter controllable by the power conversion controller to
convert power supplied through primary terminals from the power generator into direct
current power and output the direct current power resulting from the conversion from
secondary terminals, and
a capacitor connected between the secondary terminals of the first power
25 converter.
3. The power conversion device according to claim 2, wherein the target
35
torque calculator calculates the target torque using output power of the first power
converter as a value representing the operation state of the load.
4. The power conversion device according to claim 2, wherein
5 the power converter further includes at least one second power converter to convert
the direct current power supplied through the capacitor into the power to be supplied to
the load and supply the power resulting from the conversion to the load, and
the target torque calculator calculates the target torque using output power of the at
least one second power converter as a value representing the operation state of the load.
10
5. The power conversion device according to claim 4, wherein
the target torque calculator calculates the target torque using a sum of the output
power of the at least one second power converter as the value representing the operation
state of the load.
15
6. The power conversion device according to any one of claims 2 to 5, further
comprising:
a power storage connected to the capacitor, wherein
the first power converter is controllable by the power conversion controller to
20 receive supply of direct current power through the secondary terminals from the power
storage and output exciting power for initial excitation of the power generator from the
primary terminals.
7. The power conversion device according to claim 6, wherein the power
25 storage is charged with power supplied through the capacitor from the first power
converter.
36
8. The power conversion device according to claim 6 or 7, wherein the target
torque calculator calculates the target torque in accordance with the operation state of the
load and a charge-discharge capacity of the power storage.
5 9. The power conversion device according to any one of claims 1 to 8, wherein
the absolute value of the exciting current command value calculated by the power
conversion controller during the power generation by the power generator is greater than
or equal to the absolute value of the torque current command value calculated by the
power converter during the power generation by the power generator.
10
10. The power conversion device according to any one of claims 1 to 9, wherein
the absolute values of the torque current command value and the exciting current
command value calculated by the power conversion controller during the power
generation by the power generator are substantially equal to each other.
15
11. A drive control apparatus to be mounted on a vehicle, the drive control
apparatus comprising:
the power conversion device according to any one of claims 1 to 10; and
a power source to drive the power generator in the power conversion device,
20 wherein
the load to which power is to be supplied by the power converter in the power
conversion device is an electric motor to drive the vehicle.