FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
COMMAND DEVICE, DRIVE DEVICE, CONTROL DEVICE AND POWER
CONVERSION SYSTEM;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION
ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE
ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310,
JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED
2
DESCRIPTION
Technical Field
[0001] The present disclosure relates to a command device, a driving device, a
control apparatus, and a power conversion system.
5 Background Art
[0002] A typical power conversion apparatus includes a power conversion circuit,
such as inverter or converter, including multiple switching elements. The switching
elements in the power conversion circuit are controlled by a control apparatus, so that the
power conversion apparatus converts input electric power into electric power to be fed to
10 a load and feeds the electric power resulting from conversion to the load. The control
apparatus includes a command device to generate multiple command signals for
instructing operations of the switching elements, and a driving device to generate control
signals for controlling the switching elements in accordance with the command signals
and transmit the control signals to the respective switching elements.
15 [0003] In the case where a high voltage is applied to the power conversion circuit,
the driving device is made of circuit elements with high withstand voltage and disposed
at a position adjacent to the power conversion circuit. In contrast, the command device
is insulated from the power conversion circuit and disposed at a position away from the
power conversion apparatus. One example of the control apparatus including the
20 command device and the driving device connected to each other via a serial line is
disclosed in Patent Literature 1.
[0004] For example, the command device disclosed in Patent Literature 1 generates
serial data from multiple command signals, and generates a data frame containing the
serial data. The command device then transmits the data frame to the driving device via
25 a serial line. The driving device generates parallel data from the serial data contained in
the received data frame, generates multiple control signals on the basis of the parallel data,
3
and transmits the control signals to the respective switching elements.
Citation List
Patent Literature
[0005] Patent Literature 1: Unexamined Japanese Patent Application Publication
5 No. H11-178349
Summary of Invention
Technical Problem
[0006] Some power conversion apparatuses each controlled by a control apparatus
include, in addition to the switching elements in a power conversion circuit, other
10 switching elements independent from the power conversion circuit, such as switching
elements in a brake chopper circuit and switching elements in a discharging circuit. In
this case, the above-mentioned control apparatus controls the switching elements in the
power conversion circuit and the other switching elements independent from the power conversion circuit.
15 [0007] In an exemplary case where a serializer for serial conversion is in
conformity with the normal standard of conversion of 8-bit parallel data into serial data
and the number of switching elements to be controlled is larger than eight, the command
device includes multiple serializers, and the serializers transmit serial data to the driving
device via serial lines. Also, the driving device includes multiple deserializers to
20 convert serial data into parallel data, and the serial data input to the deserializers via the
serial lines is converted into parallel data.
[0008] In other words, the command device transmits a data frame for instructing
operations of the switching elements in the power conversion circuit via one serial line to
the driving device, and transmits a data frame for instructing operations of other
25 switching elements via another serial line to the driving device. Because of the multiple
serial lines for transmission of data frames from the command device to the driving
device, the structure for controlling the switching elements in the power conversion
4
circuit and other switching elements independent from the power conversion circuit is to
be complicated. This problem is not peculiar to the above-described example but
common to control apparatuses for controlling switching elements in power conversion
circuits of the power conversion apparatuses and switching elements included in the
5 power conversion apparatuses and independent from the power conversion circuits.
[0009] An objective of the present disclosure, which has been accomplished in
view of the above situations, is to provide a command device, a driving device, a control
apparatus, and a power conversion system having simple structures for controlling
switching elements in a power conversion circuit and one or more switching elements
10 independent from the power conversion circuit.
Solution to Problem
[0010] In order to achieve the above objective, a command device according to the
present disclosure is connected to a driving device via a serial line, which is configured to
control operations of a plurality of first switching elements included in a power
15 conversion circuit of a power conversion apparatus and one or more second switching
elements included in the power conversion apparatus and independent from the power
conversion circuit. The command device includes a command signal generator, an
encoder, and a command-device serializer. The command signal generator generates a
plurality of first command signals, which are binary signals for instructing operations of
20 the plurality of first switching elements, and one or more second command signals, which
are binary signals for instructing operations of the one or more second switching elements.
The encoder encodes at least some signals of the plurality of first command signals and
the one or more second command signals in accordance with possible combinations of
values of at least some signals of the plurality of first command signals and the one or
25 more second command signals, and thereby generates encoded data for instructing the
operations of the plurality of first switching elements and the one or more second
switching elements. The encoded data is represented in a smaller number of bits than
5
the sum of the number of the plurality of first switching elements and the number of the
one or more second switching elements. The command-device serializer generates
serial command data through serial conversion of the encoded data, and transmits the
serial command data to the driving device via the serial line.
5 Advantageous Effects of Invention
[0011] The command device according to the present disclosure encodes at least
some signals of the plurality of first command signals and the one or more second
command signals, and thereby generates the encoded data for instructing the operations
of the plurality of first switching elements and the one or more second switching
10 elements, which is represented in a smaller number of bits than the sum of the number of
the plurality of first switching elements and the number of the second switching elements.
The encoded data is subject to serial conversion and then transmitted to the driving device
via the serial line. The command device does not need multiple signal lines for the
purpose of instructing the operations of the plurality of first switching elements and the
15 one or more second switching elements, and therefore has a simple structure for
controlling the plurality of first switching elements and the one or more second switching
elements.
Brief Description of Drawings
[0012] FIG. 1 is a block diagram illustrating a power conversion system according
20 to Embodiment 1;
FIG. 2 is a block diagram illustrating a control apparatus according to Embodiment
1;
FIG. 3 is a block diagram illustrating a hardware configuration of a command
device and a driving device according to Embodiment 1;
25 FIG. 4 is a flowchart illustrating steps of a command data transmitting process
executed by the command device according to Embodiment 1;
FIG. 5 illustrates exemplary codes associated with possible combinations of values
6
of first command signals in Embodiment 1;
FIG. 6 illustrates exemplary first command signals, second command signals, and
encoded data in Embodiment 1;
FIG. 7 illustrates an exemplary data frame transmitted from the command device
5 according to Embodiment 1;
FIG. 8 is a flowchart illustrating steps of a control signal generating process
executed by the driving device according to Embodiment 1;
FIG. 9 is a flowchart illustrating modified steps of the control signal generating
process executed by the driving device according to Embodiment 1;
10 FIG. 10 is a state transition diagram of a decoder of the driving device according to
Embodiment 1;
FIG. 11 is a block diagram illustrating a control apparatus according to
Embodiment 2;
FIG. 12 is a flowchart illustrating steps of a feedback data transmitting process
15 executed by a driving device according to Embodiment 2;
FIG. 13 illustrates exemplary data output from a selector of the driving device
according to Embodiment 2;
FIG. 14 illustrates an exemplary data frame transmitted from the driving device
according to Embodiment 2;
20 FIG. 15 is a flowchart illustrating steps of a feedback signal generating process
executed by the control apparatus according to Embodiment 2;
FIG. 16 is a block diagram illustrating a power conversion system according to
Embodiment 3;FIG. 17 is a block diagram illustrating a control apparatus according to
25 Embodiment 3;
FIG. 18 illustrates exemplary codes associated with possible combinations of
values of first command signals in Embodiment 3;
7
FIG. 19 illustrates exemplary first command signals, second command signals, and
encoded data in Embodiment 3;
FIG. 20 is a block diagram illustrating a control apparatus according to
Embodiment 4;
5 FIG. 21 illustrates exemplary data output from a selector of a driving device
according to Embodiment 4;
FIG. 22 illustrates an exemplary variable resistance circuit according to
Embodiment 5;
FIG. 23 is a state transition diagram of a decoder of a driving device according to
10 Embodiment 5; and
FIG. 24 is a block diagram illustrating a modified hardware configuration of a
command device and a driving device according to the embodiments.
Description of Embodiments
[0013] A command device, a driving device, a control apparatus, and a power
15 conversion system according to embodiments of the present disclosure are described in
detail below with reference to the accompanying drawings. In the drawings, the
components identical or corresponding to each other are provided with the same
reference symbol.
[0014] Embodiment 1
20 The following focuses on a command device and a driving device included in a
control apparatus for controlling a power conversion apparatus included in a power
conversion system, focusing on an exemplary power conversion system installed in a
railway vehicle. In Embodiment 1, a power conversion system 1 is installed in a
railway vehicle of a DC feeding system. The power conversion system 1 illustrated in
25 FIG. 1 includes a power conversion apparatus 10 to convert DC power fed from a power
source, which is not illustrated, into three-phase AC power for driving a motor 91 and
feed the three-phase AC power to the motor 91, and a control apparatus 23 for controlling
8
the power conversion apparatus 10. In Embodiment 1, the power conversion apparatus
10 is a DC-AC converter, and the motor 91 is a three-phase induction motor fed with
three-phase AC power and driven to generate a propulsive force of the railway vehicle.
[0015] The power conversion apparatus 10 has a positive-electrode terminal 1a to
5 be connected to the power source, and a negative-electrode terminal 1b to be grounded.
The power conversion apparatus 10 further includes a power conversion circuit 12 to
convert DC power fed via primary terminals 12a and 12b into three-phase AC power for
driving the motor 91 and feed the three-phase AC power to the motor 91 via secondary
terminals 12c, 12d, and 12e, or convert three-phase AC power fed from the motor 91
10 serving as an electric generator into DC power and output the DC power via the primary
terminals 12a and 12b. The power conversion apparatus 10 also includes a filter
capacitor 11 connected to the primary terminals 12a and 12b of the power conversion
circuit 12, and a power consumption circuit 16 to consume the DC power output from the
power conversion circuit 12 and thereby generate a braking force for decelerating the
15 railway vehicle.
[0016] The positive-electrode terminal 1a is preferably electrically connected to the
power source via components, such as contactor and reactor, which are not illustrated.
The power source corresponds to a current collector to acquire electric power from a
substation via a power supply line. Examples of the current collector include a
20 pantograph to acquire electric power via an overhead wire, which is an example of the
power supply line, and a contact shoe to acquire electric power via a third rail, which is
an example of the power supply line. The negative-electrode terminal 1b is grounded
via components, such as ground ring, ground brush, and wheel, which are not illustrated.
[0017] The primary terminals 12a and 12b of the power conversion circuit 12 are
25 respectively connected to the positive-electrode terminal 1a and the negative-electrode
terminal 1b. In other words, the primary terminal 12a is connected with the
positive-electrode terminal 1a to the power source. The primary terminal 12b is
9
grounded. The power conversion circuit 12 includes serially connected first switching
elements 13u and 13x, serially connected first switching elements 13v and 13y, and
serially connected first switching elements 13w and 13z. The first switching elements
13u and 13x correspond to the U phase of the three-phase AC power. The first
5 switching elements 13v and 13y correspond to the V phase of the three-phase AC power.
The first switching elements 13w and 13z correspond to the W phase of the three-phase
AC power. The first switching elements 13u and 13x, the first switching elements 13v
and 13y, and the first switching elements 13w and 13z are connected in parallel to each
other.
10 [0018] The connecting point between the first switching elements 13u and 13x is
connected to the secondary terminal 12c. The connecting point between the first
switching elements 13v and 13y is connected to the secondary terminal 12d. The
connecting point between the first switching elements 13w and 13z is connected to the
secondary terminal 12e.
15 [0019] The first switching elements 13u, 13v, 13w, 13x, 13y, and 13z have the
identical structure including an insulated gate bipolar transistor (IGBT) 14, and a
freewheeling diode 15. The anode of the freewheeling diode 15 is connected to the
emitter terminal of the IGBT 14, and the cathode of the freewheeling diode 15 is
connected to the collector terminal of the IGBT 14.
20 [0020] The control apparatus 23 controls the first switching elements 13u, 13v, 13w,
13x, 13y, and 13z by feeding first control signals Gu, Gv, Gw, Gx, Gy, and Gz generated
by the control apparatus 23 to the respective gate terminals of the IGBTs 14 of the first
switching elements 13u, 13v, 13w, 13x, 13y, and 13z. Due to switching operations of
the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z, the power conversion
25 circuit 12 converts DC power into three-phase AC power, or converts three-phase AC
power into DC power.
[0021] The filter capacitor 11 is connected between the primary terminals 12a and
10
12b of the power conversion circuit 12, and is charged with DC power fed from the
power source or the power conversion circuit 12. The filter capacitor 11 reduces
harmonic components contained in the DC power fed from the power source or the DC
power output from the power conversion circuit 12.
5 [0022] The power consumption circuit 16 is connected in parallel to the filter
capacitor 11 in the circuitry between the filter capacitor 11 and the positive- and
negative-electrode terminals 1a and 1b. The power consumption circuit 16 includes a
second switching element 17 and a resistor 18, which are serially connected, and a second
switching element 19 and a resistor 20, which are serially connected. The power
10 consumption circuit 16 preferably further includes a freewheeling diode 21 connected in
parallel to the resistor 18, and a freewheeling diode 22 connected in parallel to the resistor
20.
[0023] The second switching elements 17 and 19 have the structure identical to that
of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z. The serially
15 connected second switching element 17 and resistor 18 are connected in parallel to the
serially connected second switching element 19 and resistor 20. The cathode of the
freewheeling diode 21 is connected to one end of the resistor 18 connected to the second
switching element 17, and the anode of the freewheeling diode 21 is connected to the
other end of the resistor 18. The cathode of the freewheeling diode 22 is connected to
20 one end of the resistor 20 connected to the second switching element 19, and the anode of
the freewheeling diode 22 is connected to the other end of the resistor 20.
[0024] The control apparatus 23 controls the second switching elements 17 and 19
by feeding second control signals G1 and G2 generated by the control apparatus 23 to the
respective gate terminals of the IGBTs 14 of the second switching elements 17 and 19.
25 When at least either of the second switching elements 17 and 19 are turned on while the
motor 91 is serving as an electric generator, the electric power generated by the motor 91
is consumed to generate a braking force for decelerating the railway vehicle.
11
[0025] The following focuses on the control apparatus 23 for controlling the power
conversion apparatus 10 having the above-described configuration. As illustrated in
FIG. 2, the control apparatus 23 includes a command device 30 to generate command
data for instructing the operations of the first switching elements 13u, 13v, 13w, 13x, 13y,
5 and 13z and the second switching elements 17 and 19, and a driving device 40 to
generate first control signals Gu, Gv, Gw, Gx, Gy, and Gz and second control signals G1
and G2 in accordance with the command data generated by the command device 30.
[0026] The driving device 40 is disposed at a position adjacent to the power
conversion apparatus 10, specifically, the power conversion circuit 12. The driving
10 device 40 is made of circuit elements with high withstand voltage. In contrast, the
command device 30 is insulated from the power conversion apparatus 10 and is disposed
at a position away from the power conversion apparatus 10. The command device 30
therefore does not have to be made of circuit elements with high withstand voltage. The
circuit elements with high withstand voltage indicate circuit elements tolerant to voltage
15 applied to the power conversion circuit 12. The command device 30 and the driving
device 40 are connected to each other via a serial line L1. The control apparatus 23
does not need multiple signal lines for the purpose of instructing the operations of the first
switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements
17 and 19, and therefore has a simple structure.
20 [0027] The command device 30 includes a command signal generator 31 to
generate first command signals Su, Sv, Sw, Sx, Sy, and Sz for instructing the operations
of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z, in accordance with
voltage commands acquired from a voltage command generating circuit, which is not
illustrated, and to generate second command signals S1 and S2 for instructing the
25 operations of the second switching elements 17 and 19, in accordance with
conduction-ratio commands acquired from a conduction-ratio command generating
circuit, which is not illustrated. The command device 30 further includes an encoder 32
12
to generate encoded data by encoding at least some signals of the first command signals
Su, Sv, Sw, Sx, Sy, and Sz and the second command signals S1 and S2, and a
command-device serializer 34 to generate serial command data through serial conversion
of the encoded data and transmit the serial command data to the driving device 40 via the
5 serial line L1. These components of the command device 30 operate in synchronization
with a clock signal output from an oscillator, which is not illustrated.
[0028] In order to prevent the first switching elements 13u, 13v, 13w, 13x, 13y, and
13z and the second switching elements 17 and 19 from being controlled on the basis of
incorrect command data, the command device 30 preferably further includes a
10 command-device error code generator 33 to generate a command-device error code from
the encoded data. In this case, the command-device serializer 34 preferably generates
serial command data through serial conversion of the encoded data provided with the
command-device error code.
[0029] The driving device 40 includes a driving-device deserializer 41 to generate
15 parallel command data through parallel conversion of the serial command data acquired
from the command device 30 via the serial line L1, and a decoder 42 to generate decoded
data by decoding the encoded data contained in the parallel command data. The driving
device 40 further includes a control signal generator 44 to generate first control signals
Gu, Gv, Gw, Gx, Gy, and Gz and second control signals G1 and G2 from the decoded
20 data. These components of the driving device 40 operate in synchronization with a
clock signal output from an oscillator, which is not illustrated, independent from the
command device 30.
[0030] In order to prevent the first switching elements 13u, 13v, 13w, 13x, 13y, and
13z and the second switching elements 17 and 19 from being controlled on the basis of
25 incorrect command data, the driving device 40 preferably further includes a
driving-device determiner 43 to determine the existence of an error in the parallel
command data on the basis of the command-device error code contained in the parallel
13
instruction data. In this case, the control signal generator 44 preferably generates first
control signals Gu, Gv, Gw, Gx, Gy, and Gz and second control signals G1 and G2, on
the basis of the decoded data generated from the parallel command data, which is
determined by the driving-device determiner 43 to have no error.
5 [0031] As illustrated in FIG. 3, the command device 30 and the driving device 40
having the above-described configurations are each achieved by a processing circuit 71.
The processing circuit 71 is connected to the serial line L1 via an interface circuit 72. In
the case where the processing circuit 71 is dedicated hardware, the processing circuit 71
is a single circuit, a combined circuit, a programmed processor, a parallel programmed
10 processor, an application specific integrated circuit (ASIC), a field programmable gate
array (FPGA), or a combination thereof, for example.
[0032] The command signal generator 31, the encoder 32, the command-device
error code generator 33, and the command-device serializer 34 may be achieved by
separate processing circuits 71. Alternatively, the command signal generator 31, the
15 encoder 32, the command-device error code generator 33, and the command-device
serializer 34 may be achieved by a common processing circuit 71.
[0033] The driving-device deserializer 41, the decoder 42, the driving-device
determiner 43, and the control signal generator 44 may be achieved by separate
processing circuits 71. Alternatively, the driving-device deserializer 41, the decoder 42,
20 the driving-device determiner 43, and the control signal generator 44 may be achieved by
a common processing circuit 71.
[0034] The following focuses on an operation of the control apparatus 23 having
the above-described configuration.
The command device 30 of the control apparatus 23, when acquiring voltage
25 commands from the voltage command generating circuit, initiates the command data
transmitting process illustrated in FIG. 4. The command signal generator 31 acquires,
from the voltage command generating circuit, voltage commands indicating target values
14
of the U-phase voltage, V-phase voltage, and W-phase voltage output from the power
conversion circuit 12 (Step S11).
[0035] The command signal generator 31 compares the triangular wave generated
on the basis of a clock signal with the voltage commands acquired in Step S11, and
5 thereby generates first command signals Su, Sv, Sw, Sx, Sy, and Sz, which are pulse
width modulation (PWM) signals (Step S12). The first command signals Su, Sv, Sw,
Sx, Sy, and Sz are binary signals. The first command signals Su, Sv, Sw, Sx, Sy, and Sz
have a value of 1 indicating the on state, or a value of 0 indicating the off state, for
example.
10 [0036] In detail, the command signal generator 31 compares the triangular wave
with the target value of the U-phase voltage, and thereby generates first command signals
Su and Sx. The command signal generator 31 compares the triangular wave with the
target value of the V-phase voltage, and thereby generates first command signals Sv and
Sy. The command signal generator 31 compares the triangular wave with the target
15 value of the W-phase voltage, and thereby generates first command signals Sw and Sz.
[0037] The command signal generator 31 acquires conduction-ratio commands
indicating target values of the conduction ratios of the second switching elements 17 and
19, from the conduction-ratio command generating circuit (Step S13). The command
signal generator 31 generates second command signals S1 and S2, which are PWM
20 signals having on and off periods adjusted in accordance with the target values of the
conduction ratios indicated by the conduction-ratio commands (Step S14). The second
command signals S1 and S2 are binary signals. The second command signals S1 and
S2 have a value of 1 indicating the on state, or a value of 0 indicating the off state, for
example.
25 [0038] The command signal generator 31 executes parallel transmission of the first
command signals Su, Sv, Sw, Sx, Sy, and Sz generated in Step S12 and the second
command signals S1 and S2 generated in Step S14, to the encoder 32.
15
[0039] The encoder 32 encodes at least some signals of the first command signals
Su, Sv, Sw, Sx, Sy, and Sz and the second command signals S1 and S2. In
Embodiment 1, the encoder 32 encodes the first command signals Su, Sv, Sw, Sx, Sy,
and Sz, on the basis of the codes associated with possible combinations of values of the
5 first command signals Su, Sv, Sw, Sx, Sy, and Sz (Step S15).
[0040] The first switching elements 13u and 13x illustrated in FIG. 1 are never
simultaneously in the on states, the first switching elements 13v and 13y are never
simultaneously in the on states, and the first switching elements 13w and 13z are never
simultaneously in the on states. The possible combinations of values of the first
10 command signals Su, Sv, Sw, Sx, Sy, and Sz thus have 27 patterns. Accordingly, a
possible combination of values of the first command signals Su, Sv, Sw, Sx, Sy, and Sz
can be represented in a five-figure binary. The encoder 32 thus generates a 5-bit code of
bits C0 to C4 corresponding to the values of the first command signals Su, Sv, Sw, Sx, Sy,
and Sz, on the basis of the 5-bit codes associated with possible combinations of values of
15 the first command signals Su, Sv, Sw, Sx, Sy, and Sz, as illustrated in FIG. 5.
[0041] As illustrated in FIG. 4, the encoder 32 generates encoded data containing
the 5-bit data, generated by encoding the first command signals Su, Sv, Sw, Sx, Sy, and
Sz, and the second command signals S1 and S2 (Step S16). In detail, the encoder 32
generates 7-bit encoded data containing the 5-bit data of bits C0 to C4 and the data of bits
20 C6 and C5 corresponding to the second command signals S1 and S2, as illustrated in FIG.
6. The encoder 32 then executes parallel transmission of the encoded data to the
command-device error code generator 33 and the command-device serializer 34.
[0042] As illustrated in FIG. 4, the command-device error code generator 33
generates a command-device error code on the basis of the encoded data (Step S17).
25 The command-device error code is an odd parity bit, for example. The
command-device error code generator 33 transmits the generated command-device error
code to the command-device serializer 34.
16
[0043] The command-device serializer 34 is in conformity with the standard of
conversion of 8-bit parallel data into serial data. The command-device serializer 34
generates serial command data containing the encoded data of bits C0 to C6 and a
command-device error code P1, through serial conversion of the encoded data provided
5 with the command-device error code (Step S18). In Embodiment 1, the
command-device serializer 34 executes serial conversion of 8-bit data to generate the
serial command data.
[0044] The command-device serializer 34 generates a data frame containing
synchronization data and serial command data following the synchronization data, as
10 illustrated in FIG. 7. As illustrated in FIG. 4, the command-device serializer 34 then
transmits the data frame to the driving device 40 via the serial line L1 (Step S19). The
command device 30 repeats the above-described steps, while voltage commands are
being input from the voltage command generating circuit.
[0045] The driving device 40, when receiving the data frame from the command
15 device 30, initiates the control signal generating process illustrated in FIG. 8. The
driving-device deserializer 41 receives the data frame from the command device 30 via
the serial line L1 (Step S21). The driving-device deserializer 41 then detects and
synchronizes the synchronization data contained in the data frame, and detects the serial
command data from the data frame. In Embodiment 1, the driving-device deserializer
20 41 generates 8-bit parallel command data through parallel conversion of the detected
serial command data (Step S22). In detail, the driving-device deserializer 41 extracts
the data of bits C0 to C6 and the command-device error code P1, from the data frame
illustrated in FIG. 7.
[0046] The driving-device deserializer 41 then executes parallel transmission of the
25 parallel command data except for the command-device error code to the decoder 42, and
executes parallel transmission of the parallel command data to the driving-device
determiner 43.
17
[0047] The decoder 42 decodes the encoded data contained in the parallel
command data (Step S23). In detail, the decoder 42 decodes subject data, specifically,
the data of bits C0 to C4 illustrated in FIG. 7, which corresponds to the first switching
elements 13u, 13v, 13w, 13x, 13y, and 13z. The decoder 42 then generates decoded
5 data, containing the decoded data corresponding to the first switching elements 13u, 13v,
13w, 13x, 13y, and 13z and the data corresponding to the second switching elements 17
and 19.
[0048] The driving-device determiner 43 detects the command-device error code
contained in the parallel command data. As illustrated in FIG. 8, the driving-device
10 determiner 43 then determines whether any error occurs in the data during
communication, on the basis of the command-device error code and the parallel
command data except for the command-device error code (Step S24). In detail, the
driving-device determiner 43 calculates the number of pieces of data having a value of 1
in the parallel command data except for the command-device error code. When the
15 number of pieces of data having a value of 1 is an odd number and the command-device
error code is 1, or when the number of pieces of data having a value of 1 is an even
number and the command-device error code is 0, no error is deemed to occur in the
parallel command data. In contrast, when the number of pieces of data having a value
of 1 is an odd number and the command-device error code is 0, or when the number of
20 pieces of data having a value of 1 is an even number and the command-device error code
is 1, any error is deemed to occur in the parallel command data.
[0049] When no error is determined to occur in the data during communication in
Step S24 (Step S25; No), the control signal generator 44 generates first control signals Gu,
Gv, Gw, Gx, Gy, and Gz and second control signals G1 and G2, on the basis of the
25 parallel command data (Step S26). After completion of Step S26, the above-described
steps from Step S21 are repeated.
[0050] The first control signals Gu, Gv, Gw, Gx, Gy, and Gz and the second
18
control signals G1 and G2 are voltage signals. The first control signals Gu, Gv, Gw, Gx,
Gy, and Gz and the second control signals G1 and G2 are fed to the respective gate
terminals of the IGBTs 14 of the first switching elements 13u, 13v, 13w, 13x, 13y, and
13z and the second switching elements 17 and 19, and thereby the first switching
5 elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements 17 and 19
are controlled. The control signal generator 44 varies the voltage values of the first
control signals Gu, Gv, Gw, Gx, Gy, and Gz and the second control signals G1 and G2,
in accordance with values of the parallel command data.
[0051] When any error is determined to occur in the data during communication in
10 Step S24 (Step S25; Yes), Step S26 is skipped, and the above-described steps from Step
S21 are repeated. In this case, the control signal generator 44 may keep outputting the
most recently generated first control signals Gu, Gv, Gw, Gx, Gy, and Gz and second
control signals G1 and G2.
[0052] In order to improve the safety of the control of the power conversion circuit
15 12, the decoder 42 preferably determines the existence of an abnormality in the parallel
command data. In detail, the decoder 42 preferably determines whether the parallel
command data except for the command-device error code has any error, as illustrated in
FIG. 9 (Step S27). In FIG. 9, Steps S21 to S26 are identical to Steps S21 to S26 in FIG.
8.
20 [0053] The decoder 42 preliminarily retains information on the codes associated
with possible combinations of values of the first command signals Su, Sv, Sw, Sx, Sy,
and Sz illustrated in FIG. 5. The decoder 42 then determines whether the encoded data
contained in the parallel command data matches any of the associated codes. When the
encoded data matches any of the associated codes, no error is deemed to occur in the
25 parallel command data. As illustrated in FIG. 9, when the decoder 42 determines that
the encoded data matches any of the associated codes, that is, when the parallel command
data has no error (Step S28; No), Step S23 and the following steps are executed.
19
[0054] In contrast, when the encoded data matches none of the associated codes,
any error is deemed to occur in the parallel command data. When the decoder 42
determines that the encoded data matches none of the associated codes, that is, the
parallel command data has any error (Step S28; Yes), the decoder 42 generates decoded
5 data for instructing all the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and
the second switching elements 17 and 19 to be turned off.
[0055] The control signal generator 44 then generates first control signals Gu, Gv,
Gw, Gx, Gy, and Gz and second control signals G1 and G2 for causing the first switching
elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements 17 and 19
10 to be turned off (Step S29). This step can prevent the power conversion circuit 12 from
being controlled on the basis of abnormal data. After completion of Step S29, the
above-described steps from Step S21 are repeated.
[0056] In the case where the decoder 42 is responsible for determination of the
existence of an abnormality in the parallel command data, the decoder 42 preferably
15 operates in accordance with the state transition diagram illustrated in FIG. 10. In
response to start of power feeding from the power source, the decoder 42 becomes the
initial state ST1. In the initial state ST1, the decoder 42 does not start the operation
regardless of acquisition of the parallel command data from the driving-device
deserializer 41. After the elapse of a predetermined period since the start of the initial
20 state ST1, the decoder 42 transits to the operable state ST2.
[0057] After the transition to the operable state ST2, the decoder 42 initiates the
operation. In detail, the decoder 42 determines whether the parallel command data has
any error. When the parallel command data has no error, the decoder 42 performs a
decoding operation. When the decoded data indicates turning on any of the first
25 switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements
17 and 19, the decoder 42 transits to the on state ST3.
[0058] In the on state ST3, the decoder 42 determines whether the parallel
20
command data has any error. When the parallel command data has no error, the
decoder 42 performs a decoding operation. When the decoded data indicates turning on
any of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second
switching elements 17 and 19, the decoder 42 remains in the on state ST3. When the
5 decoded data indicates turning off all the first switching elements 13u, 13v, 13w, 13x,
13y, and 13z and the second switching elements 17 and 19, the decoder 42 generates
decoded data for instructing all the first switching elements 13u, 13v, 13w, 13x, 13y, and
13z and the second switching elements 17 and 19 to be turned off, and transits to the
operable state ST2.
10 [0059] When any error occurs in the parallel command data while the decoder 42 is
in the operable state ST2 or the on state ST3, the decoder 42 generates decoded data for
instructing all the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the
second switching elements 17 and 19 to be turned off, and transits to the initial state ST1.
After the elapse of the predetermined period, the decoder 42 transits to the operable state
15 ST2 and becomes operable. Since the decoder 42 transits to the initial state ST1 and
holts the operation during the predetermined period in response to occurrence of any error
in the parallel command data, the power conversion circuit 12 can be prevented from
being controlled on the basis of abnormal data.
[0060] As described above, the command device 30 and the driving device 40 of
20 the control apparatus 23 according to Embodiment 1 are connected to each other with the
single serial line L1. The command device 30 transmits serial command data for
controlling the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second
switching elements 17 and 19 to the driving device 40 via the serial line L1, so that the
driving device 40 is able to control the first switching elements 13u, 13v, 13w, 13x, 13y,
25 and 13z and the second switching elements 17 and 19.
[0061] The devices do not need multiple signal lines for the purpose of instructing
the operations of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the
21
second switching elements 17 and 19, and therefore have simple structures for controlling
the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching
elements 17 and 19.
[0062] The decoder 42 responsible for determination of the existence of an
5 abnormality in the parallel command data can prevent the power conversion circuit 12
from being controlled on the basis of abnormal data and improve the safety of the control
of the power conversion circuit 12.
[0063] Embodiment 2
The control apparatus may execute feedback control of the first switching elements
10 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements 17 and 19. The
description of Embodiment 2 is directed to a control apparatus 24 having a simple
structure to control the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the
second switching elements 17 and 19 on the basis of data indicating on/off states of the
first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching
15 elements 17 and 19.
[0064] The control apparatus 24 illustrated in FIG. 11 controls the power
conversion apparatus 10, which has the same configuration as that in Embodiment 1.
The control apparatus 24 is described below focusing on the differences from the control
apparatus 23 of the power conversion system 1 according to Embodiment 1.
20 [0065] The driving device 40 of the control apparatus 24 generates status data
indicating on/off states of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z
and the second switching elements 17 and 19, and transmits serial status data obtained
through serial conversion of the status data, to the command device 30.
[0066] The command device 30 generates feedback signals indicating on/off states
25 of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second
switching elements 17 and 19, from the serial status data, and transmits the feedback
signals to the voltage command generating circuit and the conduction-ratio command
22
generating circuit. The voltage command generating circuit adjusts the voltage
commands in accordance with the feedback signals. The conduction-ratio command
generating circuit adjusts the conduction-ratio in accordance with the feedback signals.
The control apparatus 24 can thus achieve feedback control of the first switching
5 elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements 17 and 19.
[0067] The driving device 40 and the command device 30 are connected to each
other with a serial line L2, for the purpose of transmission and reception of serial status
data.
[0068] The following focuses on configurations of the driving device 40 and the
10 command device 30.
The driving device 40 includes, in addition to the components of the driving device
40 according to Embodiment 1, a status data generator 45 to generate status data, which is
binary data indicating on/off states of the first switching elements 13u, 13v, 13w, 13x,
13y, and 13z and the second switching elements 17 and 19, and a selector 46 to divide the
15 status data into segments of a predetermined number of bits and output the divided status
data. The driving device 40 further includes a driving-device serializer 48 to generate
serial status data through serial conversion of the data output from the selector 46, and
transmit the serial status data to the command device 30 via the serial line L2.
[0069] In order to prevent the first switching elements 13u, 13v, 13w, 13x, 13y, and
20 13z and the second switching elements 17 and 19 from being subject to feedback control
based on incorrect status data, the driving device 40 preferably further includes a
driving-device error code generator 47 to generate a driving-device error code from the
data output from the selector 46. In this case, the driving-device serializer 48 preferably
performs serial conversion of the data configured by adding the driving-device error code
25 to the data output from the selector 46, to generate the serial status data.
[0070] The command device 30 includes a command-device deserializer 35 to
generate parallel status data through parallel conversion of the serial status data, which is
23
acquired from the driving device 40 via the serial line L2, and a feedback signal generator
37 to generate feedback signals from the parallel status data and output the feedback
signals.
[0071] In order to prevent the first switching elements 13u, 13v, 13w, 13x, 13y, and
5 13z and the second switching elements 17 and 19 from being subject to feedback control
based on incorrect status data, the command device 30 preferably further includes a
command-device determiner 36 to determine the existence of an error in the parallel
status data on the basis of the driving-device error code contained in the parallel status
data. In this case, the feedback signal generator 37 preferably generates the feedback
10 signals from the parallel status data, which is determined by the command-device
determiner 36 to have no error.
[0072] The command device 30 and the driving device 40 have the same hardware
configuration as that illustrated in FIG. 3, except for that the processing circuit 71 is
connected to the serial lines L1 and L2 via the interface circuit 72.
15 [0073] The following focuses on an operation of the control apparatus 24 having
the above-described configuration.
The driving device 40 of the control apparatus 24, when receiving the data frame
from the command device 30, initiates the feedback data transmitting process illustrated
in FIG. 12. The status data generator 45 acquires the first control signals Gu, Gv, Gw,
20 Gx, Gy, and Gz and the second control signals G1 and G2 being fed to the respective gate
terminals of the IGBTs of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z
and the second switching elements 17 and 19 (Step S31). In detail, the status data
generator 45 measures voltage values of the first control signals Gu, Gv, Gw, Gx, Gy,
and Gz and the second control signals G1 and G2.
25 [0074] The status data generator 45 then generates status data by converting the
measured voltage values into digital data (Step S32). The status data generator 45
executes parallel transmission of the generated status data to the selector 46.
24
[0075] In Embodiment 2, the status data is 8-bit data. The selector 46 divides the
status data and outputs the divided data (Step S33), because the driving-device serializer
48 is in conformity with the standard of conversion of 8-bit parallel data into serial data,
like the command-device serializer 34. In detail, the selector 46 divides the status data
5 into the data group indicating on/off states of the first switching elements 13u, 13v, and
13w and the second switching element 17 and the data group indicating on/off states of
the first switching elements 13x, 13y, and 13z and the second switching element 19, as
illustrated in FIG. 13, adds codes for identifying the data groups to the divided data, and
outputs the resulting data in parallel.
10 [0076] In the example illustrated in FIG. 13, the data of bit D6 contained in the data
output from the selector 46 indicates an identification code for identifying the data group.
In an exemplary case where the data of bit D6 is 0, the data output from the selector 46
corresponds to the data group indicating on/off states of the first switching elements 13u,
13v, and 13w and the second switching element 17. In another exemplary case where
15 the data of bit D6 is 1, the data output from the selector 46 corresponds to the data group
indicating on/off states of the first switching elements 13x, 13y, and 13z and the second
switching element 19.
[0077] Since the above-mentioned data groups indicating on/off states are 4-bit data,
0 is set to the unused bits D5 and D4. The data of bit D3 indicates an on/off state of the
20 first switching element 13u or the first switching element 13x. The data of bit D2
indicates an on/off state of the first switching element 13v or the first switching element
13y. The data of bit D1 indicates an on/off state of the first switching element 13w or
the first switching element 13z. The data of bit D0 indicates an on/off state of the
second switching element 17 or the second switching element 19. The selector 46
25 generates 7-bit data of bits D0 to D6 as described above, and executes parallel
transmission of the generated data to the driving-device serializer 48 and the
driving-device error code generator 47.
25
[0078] As illustrated in FIG. 12, the driving-device error code generator 47
generates a driving-device error code on the basis of the data output from the selector 46
(Step S34). The driving-device error code is an odd parity bit, for example. The
driving-device error code generator 47 transmits the generated driving-device error code
5 to the driving-device serializer 48.
[0079] The driving-device serializer 48 generates serial status data containing the
data of bits D0 to D6 and a driving-device error code P2, through serial conversion of the
data output from the selector 46 and provided with the driving-device error code (Step
S35). In detail, the driving-device serializer 48 converts 8-bit data into serial data.
10 [0080] The driving-device serializer 48 generates a data frame containing
synchronization data and the serial status data following the synchronization data, as
illustrated in FIG. 14. As illustrated in FIG. 12, the driving-device serializer 48 then
transmits the data frame to the command device 30 via the serial line L2 (Step S36).
The driving device 40 repeats the above-described steps, while a data frame is being input
15 from the command device 30.
[0081] The command device 30, when receiving the data frame from the driving
device 40, initiates the feedback signal generating process illustrated in FIG. 15. The
command-device deserializer 35 receives the data frame from the driving device 40 via
the serial line L2 (Step S41). The command-device deserializer 35 then detects the
20 synchronization data contained in the data frame and synchronizes the operations, and
detects the serial status data from the data frame. In Embodiment 2, the
command-device deserializer 35 generates 8-bit parallel status data through parallel
conversion of the detected serial status data (Step S42). In detail, the command-device
deserializer 35 extracts the data of bits D0 to D6 and the driving-device error code P2
25 from the data frame illustrated in FIG. 14.
[0082] The command-device deserializer 35 then executes parallel transmission of
the parallel status data to the command-device determiner 36, and executes parallel
26
transmission of the parallel status data except for the driving-device error code to the
feedback signal generator 37.
[0083] The command-device determiner 36 detects the driving-device error code
contained in the parallel status data. As illustrated in FIG. 15, the command-device
5 determiner 36 then determines whether any error occurs in the data during
communication, on the basis of the driving-device error code and the parallel status data
except for the driving-device error code (Step S43). In detail, the command-device
determiner 36 calculates the number of pieces of data having a value of 1 in the parallel
status data except for the driving-device error code. When the number of pieces of data
10 having a value of 1 is an odd number and the driving-device error code is 1, or when the
number of pieces of data having a value of 1 is an even number and the command-device
error code is 0, the parallel status data is deemed to have no error. In contrast, when the
number of pieces of data having a value of 1 is an odd number and the driving-device
error code is 0, or when the number of pieces of data having a value of 1 is an even
15 number and the driving-device error code is 1, the parallel status data is deemed to have
any error.
[0084] When no error is determined to occur in the data during communication in
Step S43 (Step S44; No), the feedback signal generator 37 generates feedback signals on
the basis of the parallel status data (Step S45). After completion of Step S45, the
20 above-described steps from Step S41 are repeated.
[0085] In detail, when the identification code contained in the parallel status data is
0, the feedback signal generator 37 generates feedback signals indicating on/off states of
the first switching elements 13u, 13v, and 13w and the second switching element 17,
from the parallel status data. When the identification code contained in the parallel
25 status data is 1, the feedback signal generator 37 generates feedback signals indicating
on/off states of the first switching elements 13x, 13y, and 13z and the second switching
element 19, from the parallel status data.
27
[0086] When any error is determined to occur in the data during communication in
Step S43 (Step S44; Yes), Step S45 is skipped, and the above-described steps from Step
S41 are repeated. In this case, the feedback signal generator 37 keeps outputting the
most recently generated feedback signals.
5 [0087] As described above, the command device 30 and the driving device 40 of
the control apparatus 24 according to Embodiment 2 are connected to each other with the
serial line L2, for the purpose of transmission and reception of serial status data, which
indicates on/off states of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z
and the second switching elements 17 and 19. The devices do not need multiple signal
10 lines for the purpose of transmission and reception of data indicating on/off states of the
first switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching
elements 17 and 19, and therefore have simple structures for feedback control of the first
switching elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements
17 and 19.
15 [0088] Embodiment 3
Although the descriptions of Embodiments 1 and 2 are directed to the control
apparatuses 23 and 24 for controlling the power conversion apparatus 10 that converts
DC power into three-phase AC power, the control apparatuses 23 and 24 may control
power conversion apparatuses other than the power conversion apparatus 10 for
20 converting DC power into three-phase AC power. The description of Embodiment 3 is
directed to control of a power conversion apparatus that converts single-phase AC power
into three-phase AC power.
[0089] A power conversion system 2 illustrated in FIG. 16 is installed in a railway
vehicle of an AC feeding system. The power conversion system 2 is described below
25 focusing on the differences from the power conversion system 1 according to
Embodiment 1.
[0090] The power conversion system 2 includes a power conversion apparatus 50
28
to convert single-phase AC power fed from the power source into three-phase AC power
for driving the motor 91 and feed the three-phase AC power to the motor 91, and a
control apparatus 25 to control the power conversion apparatus 50. The motor 91 is fed
with three-phase AC power from the power conversion apparatus 50 and driven to
5 generate a propulsive force of the railway vehicle.
[0091] The power conversion apparatus 50 includes a transformer 51 to lower the
voltage of the fed AC power and output the AC power, and a power conversion circuit 52
to convert the AC power fed from the transformer 51 into DC power. The power
conversion apparatus 50 further includes the power conversion circuit 12 to convert the
10 DC power fed from the power conversion circuit 52 into three-phase AC power for
driving the motor 91 and feed the three-phase AC power to the motor 91, the filter
capacitor 11 connected between the primary terminals of the power conversion circuit 12,
and a discharging circuit 53 to discharge the filter capacitor 11. The power conversion
circuit 12 is controlled by the control apparatus 25, as in Embodiment 1.
15 [0092] One end of the primary winding of the transformer 51 is connected to the
positive-electrode terminal 1a, and the other end of the primary winding is connected to
the negative-electrode terminal 1b. The secondary winding of the transformer 51 is
connected to the power conversion circuit 52.
[0093] The power conversion circuit 52 includes serially connected first switching
20 elements 54u, 55u, 54x, and 55x and serially connected first switching elements 54v, 55v,
54y, and 55y. The serially connected first switching elements 54u, 55u, 54x, and 55x
are connected in parallel to the serially connected first switching elements 54v, 55v, 54y,
and 55y. The connecting point between the first switching elements 54u and 55u and
the connecting point between the first switching elements 54x and 55x are connected to
25 the respective branches from one end of the secondary winding of the transformer 51.
The connecting point between the first switching elements 54v and 55v and the
connecting point between the first switching elements 54y and 55y are connected to the
29
respective branches from the other end of the secondary winding of the transformer 51.
[0094] The first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y
have the identical structure including the IGBT 14 and the freewheeling diode 15, as in
Embodiments 1 and 2.
5 [0095] The control apparatus 25 controls the first switching elements 54u, 55u, 54x,
55x, 54v, 55v, 54y, and 55y by feeding first control signals Gu1, Gu2, Gx1, Gx2, Gv1,
Gv2, Gy1, and Gy2 generated by the control apparatus 25 to the respective gate terminals
of the IGBTs 14 of the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and
55y. Due to switching operations of the first switching elements 54u, 55u, 54x, 55x,
10 54v, 55v, 54y, and 55y, the power conversion circuit 52 converts single-phase AC power
into DC power.
[0096] The discharging circuit 53 is connected in parallel to the filter capacitor 11
in the circuitry between the power conversion circuit 52 and the filter capacitor 11. The
discharging circuit 53 includes a second switching element 56 and a resistor 57, which
15 are serially connected.
[0097] In Embodiment 3, the second switching element 56 is a thyristor. The
anode of the second switching element 56 is connected to the connecting point between
the first switching elements 54u and 54v, and the cathode of the second switching
element 56 is connected to one end of the resistor 57. The other end of the resistor 57 is
20 connected to the connecting point between the first switching elements 55x and 55y.
[0098] The control apparatus 25 controls the second switching element 56 by
feeding a second control signal G3 generated by the control apparatus 25 to the gate
terminal of the second switching element 56. In response to turning on the second
switching element 56, the filter capacitor 11 is discharged.
25 [0099] The following focuses on the control apparatus 25 for controlling the power
conversion apparatus 50 having the above-described configuration. The control
apparatus 25 has the same configuration as the control apparatus 23 of the power
30
conversion system 1 according to Embodiment 1, except for that the data and signals
generated by the control apparatus 25 differ from those generated by the control
apparatus 23. In detail, as illustrated in FIG. 17, the control apparatus 25 includes the
command device 30 to generate command data for instructing operations of the first
5 switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second switching
element 56, and the driving device 40 to generate first control signals Gu1, Gu2, Gx1,
Gx2, Gv1, Gv2, Gy1, and Gy2 and a second control signal G3, in accordance with the
command data generated by the command device 30.
[0100] The command device 30 and the driving device 40 have the same hardware
10 configuration as that in Embodiment 1.
[0101] The following focuses on an operation of the control apparatus 25 having
the above-described configuration.
The command device 30 of the control apparatus 25, when acquiring voltage
commands from the voltage command generating circuit, initiates the command data
15 transmitting process illustrated in FIG. 4, as in Embodiment 1. The command signal
generator 31 acquires, from the voltage command generating circuit, voltage commands
indicating a target value of the voltage output from the power conversion circuit 52 (Step
S11).
[0102] The command signal generator 31 compares the triangular wave generated
20 on the basis of a clock signal with the voltage commands acquired in Step S11, and
thereby generates first command signals Su1, Su2, Sx1, Sx2, Sv1, Sv2, Sy1, and Sy2,
which are PWM signals (Step S12). The first command signals Su1, Su2, Sx1, Sx2,
Sv1, Sv2, Sy1, and Sy2 are binary signals. The first command signals Su1, Su2, Sx1,
Sx2, Sv1, Sv2, Sy1, and Sy2 have a value of 1 indicating the on state, or a value of 0
25 indicating the off state, for example.
[0103] The command signal generator 31 acquires a conduction-ratio command
indicating a target value of the conduction ratio of the second switching element 56, from
31
the conduction-ratio command generating circuit (Step S13). The command signal
generator 31 generates a second command signal S3, which is a PWM signal having on
and off periods adjusted in accordance with the target value of the conduction ratio
indicated by the conduction-ratio command (Step S14). The second command signal
5 S3 is a binary signal. The second command signal S3 has a value of 1 indicating the on
state, or a value of 0 indicating the off state, for example.
[0104] The command signal generator 31 executes parallel transmission of the first
command signals Su1, Su2, Sx1, Sx2, Sv1, Sv2, Sy1, and Sy2 generated in Step S12 and
the second command signal S3 generated in Step S14, to the encoder 32.
10 [0105] The encoder 32 encodes at least some signals of the first command signals
Su1, Su2, Sx1, Sx2, Sv1, Sv2, Sy1, and Sy2 and the second command signal S3. In
Embodiment 3, the encoder 32 encodes the first command signals Su1, Su2, Sx1, Sx2,
Sv1, Sv2, Sy1, and Sy2, on the basis of the codes associated with possible combinations
of values of the first command signals Su1, Su2, Sx1, Sx2, Sv1, Sv2, Sy1, and Sy2 (Step
15 S15).
[0106] The first switching element 54u illustrated in FIG. 16 is never in the on state
simultaneously with the first switching element 54x or the first switching element 55x.
The first switching element 55u is never in the on state simultaneously with the first
switching element 55x. The first switching element 54v is never in the on state
20 simultaneously with the first switching element 54y or the first switching element 55y.
The first switching element 55v is never in the on state simultaneously with the first
switching element 55y.
[0107] The possible combinations of values of the first command signals Su1, Su2,
Sx1, Sx2, Sv1, Sv2, Sy1, and Sy2 thus have 64 patterns. Accordingly, values of the first
25 command signals Su1, Su2, Sx1, Sx2, Sv1, Sv2, Sy1, and Sy2 can be represented in a
six-figure binary. The encoder 32 thus generates a 6-bit code of bits C0 to C5
corresponding to the values of the input first command signals Su1, Su2, Sx1, Sx2, Sv1,
32
Sv2, Sy1, and Sy2, on the basis of the 6-bit codes associated with possible combinations
of values of the first command signals Su1, Su2, Sx1, Sx2, Sv1, Sv2, Sy1, and Sy2, as
illustrated in FIG. 18.
[0108] As illustrated in FIG. 4, the encoder 32 generates encoded data containing
5 the 6-bit data, generated by encoding the first command signals Su1, Su2, Sx1, Sx2, Sv1,
Sv2, Sy1, and Sy2, and the second command signal S3 (Step S16). In detail, the
encoder 32 generates 7-bit encoded data containing the 6-bit data of bits C0 to C5 and the
data of bit C6 corresponding to the second command signal S3, as illustrated in FIG. 19.
The encoder 32 then executes parallel transmission of the encoded data to the
10 command-device error code generator 33 and the command-device serializer 34.
[0109] The command-device error code generator 33 and the command-device
serializer 34 operate as in Embodiment 1. The command device 30 repeats the
above-described steps, while voltage commands are being input from the voltage
command generating circuit.
15 [0110] The driving device 40, when receiving the data frame from the command
device 30, initiates the control signal generating process illustrated in FIG. 8. Steps S21
and S22 are identical to those in Embodiment 1.
[0111] The decoder 42 decodes the encoded data contained in the parallel
command data (Step S23). In detail, the decoder 42 decodes subject data, specifically,
20 the data of bits C0 to C5 corresponding to the first switching elements 54u, 55u, 54x, 55x,
54v, 55v, 54y, and 55y. The decoder 42 then generates decoded data containing the
decoded data corresponding to the first switching elements 54u, 55u, 54x, 55x, 54v, 55v,
54y, and 55y and the data corresponding to the second switching element 56.
[0112] Step S24 is identical to that in Embodiment 1. When no error is
25 determined to occur in the data during communication in Step S24 (Step S25; No), the
control signal generator 44 generates first control signals Gu1, Gu2, Gx1, Gx2, Gv1, Gv2,
Gy1, and Gy2 and a second control signal G3, on the basis of the parallel command data
33
(Step S26). After completion of Step S26, the above-described steps from Step S21 are
repeated.
[0113] The first control signals Gu1, Gu2, Gx1, Gx2, Gv1, Gv2, Gy1, and Gy2 and
the second control signal G3 are voltage signals. The first control signals Gu1, Gu2,
5 Gx1, Gx2, Gv1, Gv2, Gy1, and Gy2 and the second control signal G3 are fed to the
respective gate terminals of the IGBTs 14 of the first switching elements 54u, 55u, 54x,
55x, 54v, 55v, 54y, and 55y and the second switching element 56, and thereby the first
switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second switching
element 56 are controlled. The control signal generator 44 varies the voltage values of
10 the first control signals Gu1, Gu2, Gx1, Gx2, Gv1, Gv2, Gy1, and Gy2 and the second
control signal G3, in accordance with values of the parallel command data.
[0114] When any error is determined to occur in the data during communication in
Step S24 (Step S25; Yes), Step S26 is skipped, and the above-described steps from Step
S21 are repeated. In this case, the control signal generator 44 keeps outputting the most
15 recently generated first control signals Gu1, Gu2, Gx1, Gx2, Gv1, Gv2, Gy1, and Gy2
and second control signal G3.
[0115] In order to improve the safety of the control of the power conversion circuit
52, the decoder 42 preferably determines the existence of an abnormality in the parallel
command data. In detail, as illustrated in FIG. 9, the decoder 42 preferably determines
20 whether the parallel command data except for the command-device error code has any
error (Step S27).
[0116] The decoder 42 preliminarily retains information on the codes associated
with possible combinations of values of the first command signals Su1, Su2, Sx1, Sx2,
Sv1, Sv2, Sy1, and Sy2 illustrated in FIG. 18. The decoder 42 then determines whether
25 the encoded data contained in the parallel command data matches any of the associated
codes. When the encoded data matches any of the associated codes, no error is deemed
to occur in the parallel command data. When the decoder 42 determines that the
34
encoded data matches any of the associated codes, that is, when the parallel command
data has no error (Step S28; No), Step S23 and the following steps are executed.
[0117] In contrast, when the encoded data matches none of the associated codes,
any error is deemed to occur in the parallel command data. When the decoder 42
5 determines that the encoded data matches none of the associated codes, that is, the
parallel command data has any error (Step S28; Yes), the decoder 42 generates decoded
data for instructing all the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and
55y and the second switching element 56 to be turned off.
[0118] The control signal generator 44 then generates first control signals Gu1, Gu2,
10 Gx1, Gx2, Gv1, Gv2, Gy1, and Gy2 and a second control signal G3 for causing the first
switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second switching
element 56 to be turned off (Step S29). This step can prevent the power conversion
circuit 12 from being controlled on the basis of abnormal data. After completion of Step
S29, the above-described steps from Step S21 are repeated.
15 [0119] In the case where the decoder 42 is responsible for determination of the
existence of an abnormality in the parallel command data, the decoder 42 preferably
operates in accordance with the state transition diagram illustrated in FIG. 10, as in
Embodiment 1.
[0120] As described above, the command device 30 and the driving device 40 of
20 the control apparatus 25 according to Embodiment 3 are connected to each other with the
single serial line L1. The command device 30 transmits serial command data for
controlling the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and
the second switching element 56 to the driving device 40 via the serial line L1, so that the
driving device 40 is able to control the first switching elements 54u, 55u, 54x, 55x, 54v,
25 55v, 54y, and 55y and the second switching element 56.
[0121] The devices do not need multiple signal lines for the purpose of instructing
the operations of the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y
35
and the second switching element 56, and therefore have simple structures for controlling
the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second
switching element 56.
[0122] The decoder 42 responsible for determination of the existence of an
5 abnormality in the parallel command data can improve the safety of the control of the
power conversion circuit 52.
[0123] Embodiment 4
The control apparatus may execute feedback control of the first switching elements
54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second switching element 56. The
10 description of Embodiment 4 is directed to a control apparatus 26 having a simple
structure to control the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and
55y and the second switching element 56, on the basis of data indicating on/off states of
the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second
switching element 56.
15 [0124] The control apparatus 26 illustrated in FIG. 20 controls the power
conversion apparatus 50, which has the same configuration as that in Embodiment 3.
The control apparatus 26 has the same configuration as the control apparatus 24 of the
power conversion system 1 according to Embodiment 2, except for that the data and
signals generated by the control apparatus 26 differ from those generated by the control
20 apparatus 24. In detail, the control apparatus 26 includes the command device 30 to
generate command data for instructing the operations of the first switching elements 54u,
55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second switching element 56, and the
driving device 40 to generate first control signals Gu1, Gu2, Gx1, Gx2, Gv1, Gv2, Gy1,
and Gy2 and a second control signal G3 in accordance with the command data generated
25 by the command device 30.
[0125] The driving device 40 generates status data indicating on/off states of the
first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second
36
switching element 56, and transmits serial status data obtained through serial conversion
of the status data, to the command device 30.
[0126] The command device 30 generates feedback signals indicating on/off states
of the first switching elements 54u, 55u, 54x, 55x, 54v, 55v, 54y, and 55y and the second
5 switching element 56, from the serial status data, and transmits the feedback signals to the
voltage command generating circuit and the conduction-ratio command generating circuit.
The voltage command generating circuit adjusts the voltage commands in accordance
with the feedback signals. The conduction-ratio command generating circuit adjusts the
conduction-ratio in accordance with the feedback signals. The control apparatus 26 can
10 thus achieve feedback control of the first switching elements 54u, 55u, 54x, 55x, 54v, 55v,
54y, and 55y and the second switching element 56.
[0127] The driving device 40 and the command device 30 are connected to each
other with the serial line L2, for the purpose of transmission and reception of serial status
data.
15 [0128] The command device 30 and the driving device 40 have the same hardware
configuration as that in Embodiment 1.
[0129] The following focuses on an operation of the control apparatus 26 having
the above-described configuration.
The driving device 40 of the control apparatus 26, when receiving the data frame
20 from the command device 30, initiates the feedback data transmitting process illustrated
in FIG. 12, as in Embodiment 2. The status data generator 45 acquires the first control
signals Gu1, Gu2, Gx1, Gx2, Gv1, Gv2, Gy1, and Gy2 and the second control signal G3
being fed to the gate terminals of the IGBTs of the first switching elements 54u, 55u, 54x,
55x, 54v, 55v, 54y, and 55y and the second switching element 56 (Step S31). In detail,
25 the status data generator 45 measures voltage values of the first control signals Gu1, Gu2,
Gx1, Gx2, Gv1, Gv2, Gy1, and Gy2 and the second control signal G3.
[0130] The status data generator 45 then generates status data by converting the
37
measured voltage values into digital data (Step S32). The status data generator 45
executes parallel transmission of the generated status data to the selector 46.
[0131] In Embodiment 4, the status data is 9-bit data. The selector 46 divides the
status data and outputs the divided data (Step S33), because the driving-device serializer
5 48 is in conformity with the standard of conversion of 8-bit parallel data into serial data,
like the command-device serializer 34. In detail, the selector 46 divides the status data
into the data group indicating on/off states of the first switching elements 54u, 55u, 54x,
and 55x and the second switching element 56 and the data group indicating on/off states
of the first switching elements 54v, 55v, 54y, and 55y, as illustrated in FIG. 21, adds
10 codes for identifying the data groups to the divided data, and outputs the resulting data in
parallel.
[0132] In the example illustrated in FIG. 21, the data of bit D6 contained in the data
output from the selector 46 indicates an identification code for identifying the data group.
In an exemplary case where the data of bit D6 is 0, the data output from the selector 46
15 corresponds to the data group indicating on/off states of the first switching elements 54u,
55u, 54x, and 55x and the second switching element 56. In another exemplary case
where the data of bit D6 is 1, the data output from the selector 46 corresponds to the data
group indicating on/off states of the first switching elements 54v, 55v, 54y, and 55y.
[0133] Since the above-mentioned data groups indicating on/off states are 4-bit or
20 5-bit data, 0 is set to the unused bit D5. When the data of bit D6 is 0, the data of bit D4
indicates an on/off state of the second switching element 56. When the data of bit D6 is
1, 0 is set to the unused bit D4. The data of bit D3 indicates an on/off state of the first
switching element 54u or the first switching element 54v. The data of bit D2 indicates
an on/off state of the first switching element 55u or the first switching element 55v. The
25 data of bit D1 indicates an on/off state of the first switching element 54x or the first
switching element 54y. The data of bit D0 indicates an on/off state of the first switching
element 55x or the first switching element 55y. The selector 46 generates 7-bit data of
38
bits D0 to D6 as described above, and executes parallel transmission of the generated data
to the driving-device serializer 48 and the driving-device error code generator 47.
[0134] Step S34 and the following steps in the driving device 40 are identical to
those in Embodiment 2.
5 [0135] The command device 30, when receiving the data frame from the driving
device 40, initiates the feedback signal generating process illustrated in FIG. 15, as in
Embodiment 2. Steps S41 to S43 are identical to those in Embodiment 2.
[0136] When no error is determined to occur in the data during communication in
Step S43 (Step S44; Yes), the feedback signal generator 37 generates feedback signals on
10 the basis of the parallel status data (Step S45). After completion of Step S45, the
above-described steps from Step S41 are repeated.
[0137] In detail, when the identification code contained in the parallel status data is
0, the feedback signal generator 37 generates feedback signals indicating on/off states of
the first switching elements 54u, 55u, 54x, and 55x and the second switching element 56,
15 from the parallel status data. When the identification code contained in the parallel
status data is 1, the feedback signal generator 37 generates feedback signals indicating
on/off states of the first switching elements 54v, 55v, 54y, and 55y, from the parallel
status data.
[0138] When any error is determined to occur in the data during communication in
20 Step S43 (Step S44; Yes), Step S45 is skipped, and the above-described steps from Step
S41 are repeated. In this case, the feedback signal generator 37 keeps outputting the
most recently generated feedback signals.
[0139] As described above, the command device 30 and the driving device 40 of
the control apparatus 26 according to Embodiment 4 are connected to each other with the
25 serial line L2, for the purpose of transmission and reception of serial status data, which
indicates on/off states of the first switching elements 54u, 55u, 54x, and 55x and the
second switching element 56. The devices do not need multiple signal lines for the
39
purpose of transmission and reception of data indicating on/off states of the first
switching elements 54u, 55u, 54x, and 55x and the second switching element 56, and
therefore have simple structures for feedback control of the first switching elements 54u,
55u, 54x, and 55x and the second switching element 56.
5 [0140] Embodiment 5
The control apparatus may adjust the resistances of gate resistors as well as
controlling the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z. The
description of Embodiment 5 is directed to the control apparatus 23 to adjust the
resistances of gate resistors.
10 [0141] The control apparatus 23 adjusts the gate resistances of the IGBTs 14 of the
respective first switching elements 13u, 13v, 13w, 13x, 13y, and 13z. In order to adjust
the gate resistances of the IGBTs 14, each of the gate terminals of the IGBTs 14 is
connected to a variable resistance circuit 58 illustrated in FIG. 22. The resistance of the
variable resistance circuit 58 is adjusted by means of third control signals GR1 and GR2
15 output from the control apparatus 23. Because the variable resistance circuits 58
connected to the respective gate terminals of the IGBTs 14 of the first switching elements
13u, 13v, 13w, 13x, 13y, and 13z have the identical configuration, the following focuses
on the variable resistance circuit 58 connected to the first switching element 13u.
[0142] The variable resistance circuit 58 has an input terminal 58a to be fed with
20 the first control signal Gu output from the control apparatus 23, and an output terminal
58b connected to the gate terminal of the first switching element 13u. The variable
resistance circuit 58 further includes third switching elements 59 and 60 having collector
terminals connected to the input terminal 58a, a resistor 61 having one end connected to
the emitter terminal of the third switching element 59 and the other end connected to the
25 emitter terminal of the third switching element 60, and a resistor 62 having one end
connected to the emitter terminal of the third switching element 60 and the other end
connected to the output terminal 58b. The gate terminals of the third switching
40
elements 59 and 60 are respectively fed with the third control signals GR1 and GR2
output from the control apparatus 23. The third control signals GR1 and GR2 switch
the on/off states of the respective third switching elements 59 and 60, resulting in a
change in the resistance of the variable resistance circuit 58.
5 [0143] The control apparatus 23 has the same configuration as that in Embodiment
1, except for that the control apparatus 23 acquires a resistance command for designating
gate resistances from a resistance-adjusting command generating circuit, and feeds third
control signals GR1 and GR2 to each of the first switching elements 13u, 13v, 13w, 13x,
13y, and 13z.
10 [0144] The following focuses on an operation of the control apparatus 23 for
adjusting gate resistances.
When the resistance command indicates changes in the gate resistances, the
command signal generator 31 of the command device 30 of the control apparatus 23
generates first command signals Su, Sv, Sw, Sx, Sy, and Sz assigned to changes in the
15 gate resistances, regardless of the voltage commands.
[0145] In detail, in an exemplary case where the third switching element 59 is in the
on state, the third switching element 60 is in the off state, and the resistance command
indicates turning on the third switching elements 59 and 60, the command signal
generator 31 generates first command signals Su, Sv, Sw, Sx, Sy, and Sz corresponding
20 to the resistance command. The first command signals Su, Sv, Sw, Sx, Sy, and Sz
corresponding to the resistance command are associated with an impossible combination
of on/off states of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z, for
example, the first command signals Su, Sv, Sw, Sx, Sy, and Sz all having a value of 1.
[0146] The encoder 32 retains information on the code associated with the first
25 command signals Su, Sv, Sw, Sx, Sy, and Sz and corresponding to the resistance
command, in addition to the codes illustrated in FIG. 5. The encoder 32 then generates
5-bit code associated with the first command signals Su, Sv, Sw, Sx, Sy, and Sz
41
corresponding to the resistance command.
[0147] The command-device error code generator 33 and the command-device
serializer 34 operate as in Embodiment 1.
[0148] The driving-device deserializer 41 of the driving device 40 of the control
5 apparatus 23 operates as in Embodiment 1. The decoder 42 retains information on the
code associated with the first command signals Su, Sv, Sw, Sx, Sy, and Sz corresponding
to the resistance command, like the encoder 32. When the decoded data generated by
the decoder 42 contains data assigned to changes in the gate resistances and associated
with the impossible combination of on/off states of the first switching elements 13u, 13v,
10 13w, 13x, 13y, and 13z, the control signal generator 44 generates first control signals Gu,
Gv, Gw, Gx, Gy, and Gz for causing all the first switching elements 13u, 13v, 13w, 13x,
13y, and 13z to be turned off. The control signal generator 44 then generates third
control signals GR1 and GR2 on the basis of the data assigned to changes in the gate
resistances. This process turns off the first switching elements 13u, 13v, 13w, 13x, 13y,
15 and 13z. The third switching elements 59 and 60 of the variable resistance circuits 58
connected to the gate terminals of the IGBTs 14 of the respective first switching elements
13u, 13v, 13w, 13x, 13y, and 13z are then controlled, leading to adjustment of the gate
resistances.
[0149] The decoder 42 operates in accordance with the state transition diagram
20 illustrated in FIG. 23. The initial state ST1, the operable state ST2, and the on state ST3
are the same as those in FIG. 10. In the operable state ST2 or the on state ST3, when the
decoded data contains the data assigned to changes in the gate resistances, the decoder 42
transits to the adjustment state ST4.
[0150] In the adjustment state ST4, the decoder 42 generates first control signals
25 Gu, Gv, Gw, Gx, Gy, and Gz for causing all the first switching elements 13u, 13v, 13w,
13x, 13y, and 13z to be turned off, and generates third control signals GR1 and GR2
associated with the data assigned to changes in the gate resistances contained in the
42
decoded data. The decoder 42 then transits to the initial state ST1.
[0151] As described above, the control apparatus 23 according to Embodiment 5
can, not only control the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z, but
also adjust the resistances of the gate resistors for the IGBTs 14 of the respective first
5 switching elements 13u, 13v, 13w, 13x, 13y, and 13z.
[0152] High resistances of the gate resistors can suppress surge voltages caused by
switching operations of the first switching elements 13u, 13v, 13w, 13x, 13y, and 13z.
In contrast, low resistances of the gate resistors can reduce switching losses in the first
switching elements 13u, 13v, 13w, 13x, 13y, and 13z.
10 [0153] The above-described embodiments are not intended to limit the scope of the
present disclosure. The above-described hardware configurations and flowcharts are
mere examples and may be arbitrarily modified and corrected.
[0154] The functions of the command device 30 and the driving device 40 may be
performed by software. In this case, as illustrated in FIG. 24, the command device 30
15 and the driving device 40 each include a processor 81, a memory 82, and an interface 83.
The processor 81, the memory 82, and the interface 83 are connected to each other with
buses 80.
[0155] The functions of the command device 30 and the driving device 40 are
performed by software, firmware, or a combination of software and firmware. The
20 software and the firmware are described in the form of programs and stored in the
memory 82. The processor 81 reads and executes the programs stored in the memory
82, and thereby achieves the above-described functions of the components. That is, the
memory 82 stores programs for executing operations of the command device 30 and the
driving device 40.
25 [0156] Examples of the memory 82 include non-volatile or volatile semiconductor
memories, such as random access memory (RAM), read only memory (ROM), flash
memory, erasable programmable read only memory (EPROM), and electrically erasable
43
and programmable read only memory (EEPROM), magnetic disks, flexible disks, optical
disks, compact discs, mini discs, and digital versatile discs (DVDs).
[0157] A part of the functions of the command device 30 and the driving device 40
may be performed by dedicated hardware, while another part of the functions may be
5 performed by software or firmware. For example, the command signal generator 31 and
the command-device serializer may be achieved by the processing circuit 71 illustrated in
FIG. 3, while the encoder 32 and the command-device error code generator 33 may be
achieved by programs stored in the memory 82 when the programs are read and executed
by the processor 81 illustrated in FIG. 24.
10 [0158] The above-described configurations of the power conversion apparatuses 10
and 50 are mere examples. The power conversion apparatuses 10 and 50 may include a
direct-current-direct-current (DC-DC) converter, for example. In this case, the control
apparatuses 23, 24, 25, and 26 control first switching elements included in the DC-DC
converter and the second switching element 56 included in the discharging circuit 53.
15 [0159] In the case where possible combinations of values of first switching
elements and one or more second switching elements are determined in advance, the
encoder 32 may collectively encode values of the first switching elements and the one or
more second switching elements.
[0160] The first switching elements 13u, 13v, 13w, 13x, 13y, 13z, 54u, 55u, 54x,
20 55x, 54v, 55v, 54y, and 55y and the second switching elements 17 and 19 may be any
element capable of switching operations, other than IGBTs. For example, the first
switching elements 13u, 13v, 13w, 13x, 13y, 13z, 54u, 55u, 54x, 55x, 54v, 55v, 54y, and
55y and the second switching elements 17 and 19 may be metal-oxide semiconductor
field-effect transistors (MOSFETs).
25 [0161] The second switching element 56 is not necessarily a thyristor and may also
be an IGBT or a MOSFET, for example.
[0162] The discharging circuit 53 may have any circuit configuration other than the
44
above-described configuration provided that the discharging circuit 53 can discharge the
filter capacitor 11.
[0163] The variable resistance circuit 58 may have any circuit configuration other
than the above-described configuration provided that the resistance of the variable
5 resistance circuit 58 is variable.
[0164] In the case where the control apparatus 24 adjusts the resistances of the gate
resistors as well as controlling the first switching elements 13u, 13v, 13w, 13x, 13y, and
13z, like the control apparatus 23 in Embodiment 5, the driving device 40 of the control
apparatus 24 may transmit data indicating on/off states of the third switching elements 59
10 and 60 to the command device 30. For example, the selector 46 may assign the data
indicating on/off states of the third switching elements 59 and 60 to the bit D4 and then
output the resulting data.
[0165] The driving device 40 according to Embodiment 2 may transmit, to the
command device 30, not only the data indicating on/off states of the first switching
15 elements 13u, 13v, 13w, 13x, 13y, and 13z and the second switching elements 17 and 19,
but also data indicating the state of the driving device 40, for example, data indicating the
existence of a decrease in the power supply voltage of the driving device 40, for example.
In detail, the driving device 40 may determine the existence of a decrease in the power
supply voltage on the basis of a value measured by a sensor for measuring a power
20 supply voltage, and transmit a result of determination to the command device 30. In this
case, the selector 46 assigns the data indicating the existence of a decrease in the power
supply voltage to the bit D5 and outputs the resulting data.
[0166] The foregoing describes some example embodiments for explanatory
purposes. Although the foregoing discussion has presented specific embodiments,
25 persons skilled in the art will recognize that changes may be made in form and detail
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
45
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
equivalents to which such claims are entitled.
Reference Signs List
5 [0167] 1, 2 Power conversion system
1a Positive-electrode terminal
1b Negative-electrode terminal
10, 50 Power conversion apparatus
11 Filter capacitor
10 12, 52 Power conversion circuit
12a, 12b Primary terminal
12c, 12d, 12e Secondary terminal
13u, 13v, 13w, 13x, 13y, 13z, 54u, 55u, 54x, 55x, 54v, 55v, 54y, 55y First switching
element
15 14 IGBT
15, 21, 22 Freewheeling diode
16 Power consumption circuit
17, 19, 56 Second switching element
18, 20, 57, 61, 62 Resistor
20 23, 24, 25, 26 Control apparatus
30 Command device
31 Command signal generator
32 Encoder
33 Command-device error code generator
25 34 Command-device serializer
35 Command-device deserializer
36 Command-device determiner
46
37 Feedback signal generator
40 Driving device
41 Driving-device deserializer
42 Decoder
5 43 Driving-device determiner
44 Control signal generator
45 Status data generator
46 Selector
47 Driving-device error code generator
10 48 Driving-device serializer
51 Transformer
53 Discharging circuit
58 Variable resistance circuit
58a Input terminal
15 58b Output terminal
59, 60 Third switching element
71 Processing circuit
72 Interface circuit
80 Bus
20 81 Processor
82 Memory
83 Interface
91 Motor
Gu, Gv, Gw, Gx, Gy, Gz, Gu1, Gu2, Gx1, Gx2, Gv1, Gv2, Gy1, Gy2 First control
25 signal
G1, G2, G3 Second control signal
GR1, GR2 Third control signal
47
L1, L2 Serial line
Su, Sv, Sw, Sx, Sy, Sz, Su1, Su2, Sx1, Sx2, Sv1, Sv2, Sy1, Sy2 First command signal
S1, S2, S3 Second command signal

We Claim:
[Claim 1] A command device connectable to a driving device via a serial line,
5 the driving device being configured to control operations of a plurality of first switching
elements included in a power conversion circuit of a power conversion apparatus and one
or more second switching elements included in the power conversion apparatus and
independent from the power conversion circuit, the command device comprising:
a command signal generator to generate a plurality of first command signals and
10 one or more second command signals, the plurality of first command signals being binary
signals for instructing operations of the plurality of first switching elements, the one or
more second command signals being binary signals for instructing operations of the one
or more second switching elements;
an encoder to encode at least some signals of the plurality of first command signals
15 and the one or more second command signals in accordance with possible combinations
of values of at least some signals of the plurality of first command signals and the one or
more second command signals, and thereby generate encoded data for instructing the
operations of the plurality of first switching elements and the one or more second
switching elements, the encoded data being represented in a smaller number of bits than a
20 sum of a number of the plurality of first switching elements and a number of the one or
more second switching elements; and
a command-device serializer to generate serial command data through serial
conversion of the encoded data, and transmit the serial command data to the driving
device via the serial line.
25
[Claim 2] The command device according to claim 1, wherein the encoder
generates the encoded data, the encoded data containing values of the one or more second
49
command signals and data represented in a smaller number of bits than the number of the
plurality of first switching elements, the data being generated by encoding the plurality of
first command signals in accordance with codes associated with possible combinations of
values of the plurality of first command signals.
5
[Claim 3] The command device according to claim 1 or 2, wherein the
command signal generator
generates the plurality of first command signals for instructing the operations of the
plurality of first switching elements included in the power conversion circuit, the power
10 conversion circuit being configured to convert DC power received at primary terminals
into AC power and output the AC power from secondary terminals, or to convert AC
power received at the secondary terminals into DC power and output the DC power from
the primary terminals, and
generates the one or more second command signals for instructing the operations
15 of the one or more second switching elements included in a power consumption circuit,
the power consumption circuit being configured to consume the DC power output from
the primary terminals.
[Claim 4] The command device according to claim 3, wherein
20 the command signal generator generates six first command signals of the plurality
of first command signals for instructing operations of six first switching elements of the
plurality of first switching elements included in the power conversion circuit, and
generates two second command signals of the one or more second command signals for
instructing operations of two second switching elements of the one or more second
25 switching elements included in the power consumption circuit, and
the encoder generates 5-bit data by encoding the six first command signals, and
generates 7-bit encoded data containing the 5-bit data and values of the two second
50
command signals.
[Claim 5] The command device according to claim 1 or 2, wherein the
command signal generator
5 generates the plurality of first command signals for instructing the operations of the
plurality of first switching elements included in the power conversion circuit, the power
conversion circuit being a converter configured to convert AC power received at primary
terminals into DC power and to output the DC power from secondary terminals, and
generates the one or more second command signals for instructing the operations
10 of the one or more second switching elements included in a discharging circuit, the
discharging circuit being connected between the secondary terminals of the converter.
[Claim 6] The command device according to claim 5, wherein
the command signal generator generates eight first command signals of the
15 plurality of first command signals for instructing operations of eight first switching
elements of the plurality of first switching elements included in the converter, and
generates a single second command signal of the one or more second command signals
for instructing an operation of a single second switching element of the one or more
second switching elements included in the discharging circuit, and
20 the encoder generates 6-bit data by encoding the eight first command signals, and
generates 7-bit encoded data containing the 6-bit data and a value of the single second
command signal.
[Claim 7] The command device according to any one of claims 1 to 6, further
25 comprising:
a command-device error code generator to generate a command-device error code
from the encoded data, wherein
51
the command-device serializer generates the serial command data through serial
conversion of the encoded data provided with the command-device error code.
[Claim 8] The command device according to any one of claims 1 to 7, further
5 comprising:
a command-device deserializer to acquire, from the driving device, serial status
data indicating whether the plurality of first switching elements and the one or more
second switching elements are in on or off states, and to generate parallel status data
through parallel conversion of the serial status data; and
10 a feedback signal generator to generate, from the parallel status data, a plurality of
feedback signals indicating whether the plurality of first switching elements and the one
or more second switching elements are in on or off states, and to output the plurality of
feedback signals.
15 [Claim 9] The command device according to claim 8, further comprising:
a command-device determiner to determine, based on a driving-device error code
contained in the parallel status data, whether the parallel status data has any error,
wherein
when the command-device determiner determines that the parallel status data has
20 no error, the feedback signal generator generates the plurality of feedback signals.
[Claim 10] A driving device to control operations of a plurality of first switching
elements included in a power conversion circuit of a power conversion apparatus and one
or more second switching elements included in the power conversion apparatus and
25 independent from the power conversion circuit, the driving device comprising:
a driving-device deserializer to acquire, from a command device, serial command
data for instructing the operations of the plurality of first switching elements and the one
52
or more second switching elements, and to generate parallel command data through
parallel conversion of the serial command data, the command device being connected to
the driving device via a serial line;
a decoder to decode encoded data contained in the parallel command data, and
5 thereby generate decoded data for instructing the operations of the plurality of first
switching elements and the one or more second switching elements; and
a control signal generator to generate, based on the decoded data, a plurality of first
control signals directed to the plurality of first switching elements and one or more
second control signals directed to the one or more second switching elements, transmit
10 the plurality of first control signals to the plurality of first switching elements, and
transmit the one or more second control signals to the one or more second switching
elements.
[Claim 11] The driving device according to claim 10, wherein when the encoded
15 data contained in the parallel command data is not a code associated with a possible
combination of on or off states of at least some elements of the plurality of first switching
elements and the one or more second switching elements, the decoder generates the
decoded data for instructing the plurality of first switching elements and the one or more
second switching elements to be turned off.
20
[Claim 12] The driving device according to claim 10 or 11, further comprising:
a driving-device determiner to determine, based on a command-device error code
contained in the parallel command data, whether the parallel command data has any error,
wherein
25 when the driving-device determiner determines that the parallel command data has
no error, the control signal generator generates the plurality of first control signals and the
one or more second control signals.
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[Claim 13] The driving device according to any one of claims 10 to 12, wherein
the control signal generator generates, in accordance with the parallel command data, a
plurality of third control signals for adjusting resistances of a plurality of variable
5 resistance circuits connected to the plurality of respective first switching elements, and
transmits the plurality of third control signals to the plurality of variable resistance
circuits.
[Claim 14] The driving device according to any one of claims 10 to 13, further
10 comprising:
a status data generator to generate status data indicating whether the plurality of
first switching elements and the one or more second switching elements are in on or off
states; and
a driving-device serializer to generate serial status data through serial conversion of
15 the status data, and transmit the serial status data to the command device via a serial line.
[Claim 15] The driving device according to claim 14, further comprising:
a driving-device error code generator to generate a driving-device error code from
the status data, wherein
20 the driving-device serializer generates the serial status data through serial
conversion of the status data provided with the driving-device error code.
[Claim 16] A control apparatus comprising:
the command device according to any one of claims 1 to 9; and
25 the driving device according to any one of claims 10 to 15.
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[Claim 17] A power conversion system comprising:
a power conversion apparatus including a power conversion circuit including a
plurality of first switching elements, and one or more second switching elements
independent from the power conversion circuit, the power conversion apparatus being
5 configured to convert input electric power into electric power for being fed to a load and
to feed the electric power resulting from conversion to the load; and
the control apparatus according to claim 16 to control operations of the plurality of
first switching elements and the one or more second switching elements.