JP7363251B2 - Power conversion equipment, electric vehicles, railway vehicles and servers - Google Patents

Description

The present invention relates to a power conversion device that is an isolated DC/DC (direct current/direct current) conversion device that insulates an input side and an output side, an electric vehicle, a railway vehicle, and a server equipped with the power conversion device.

The power conversion device disclosed in Patent Document 1 includes a center-tapped transformer having a switch circuit that converts DC voltage into AC voltage, and a primary winding and a secondary winding into which the AC voltage is input. and a rectifier circuit connected to the secondary winding. The rectifier circuit includes a plurality of rectifier diodes (first diode group) connected in parallel to one end of the secondary winding, and a plurality of rectifier diodes connected in parallel to the other end of the secondary winding. diodes (second diode group). Further, the power conversion device disclosed in Patent Document 1 includes a temperature sensor (first temperature sensor) that is provided next to one diode in the first diode group and detects the temperature of the diode, and a temperature sensor (first temperature sensor) that is provided next to one diode in the first diode group and Among them, there is a temperature sensor (second temperature sensor) installed next to one diode that detects the temperature of the diode, and the temperature difference detected by each of the first temperature sensor and the second temperature sensor is outside the predetermined range. and a failure detection unit that determines that a failure has occurred in one of the diodes in the first diode group and the second diode group. Thereby, failures in multiple diodes connected in parallel as a rectifier can be detected with a simple configuration.

Japanese Patent Application Publication No. 2014-103732

However, in the conventional technology disclosed in Patent Document 1, since a temperature sensor is provided next to one diode in a diode group, it is not possible to determine which diode in the diode group has failed. Further, when any diode has an open failure, a large current flows through healthy diodes other than the diode, and the temperature of the healthy diode increases. At this time, since there is a time lag between the time when the open failure occurs and the temperature of the healthy diode rises, there is a risk that a large current will continue to flow through the healthy diode and destroy it by the time the diode failure is detected. As described above, in the conventional power conversion device, there is room for improvement in detecting a failure of a plurality of diodes.

The present invention has been made in view of the above, and an object of the present invention is to provide a power conversion device that can easily and accurately detect a failure of a diode.

In order to solve the above-mentioned problems and achieve the objects, the power conversion device according to the present invention has an upper arm switching element and a lower arm switching element connected in series to the upper arm switching element, which operate in a complementary manner. , an isolation transformer having a voltage converter that converts a DC voltage into an AC voltage, a primary winding to which the upper arm switching element and the lower arm switching element are connected, and a secondary winding having a center tap; , a first diode for rectification that is connected to one end of the secondary winding and becomes conductive when the upper arm switching element is ON; and the lower arm switching element is connected to the other end of the secondary winding. a rectifier having a second diode for rectification that becomes conductive when turned on, and rectifying the voltage of the secondary winding; a current flowing through the first diode and a current flowing through the second diode; and a current detector that detects the total sum of the current.

According to the present invention, it is possible to easily and accurately detect a failure of a diode.

A diagram showing a configuration example of a power conversion device according to an embodiment of the present invention Diagram showing an example of the configuration of the control unit A diagram showing a configuration example of a diode failure detection section 60 Timing chart for explaining the state of the failure determination signal etc. before and after the diode 30a has an open failure Timing chart for explaining the state of the failure determination signal etc. before and after the diode 31a has an open failure A diagram showing a configuration example of a diode failure detection section 61 Timing chart for explaining the states of failure determination signals, etc. before and after the diode 30b has an open failure Timing chart for explaining the state of the failure determination signal etc. before and after the diode 31b has an open failure A diagram showing a configuration example of the diode failure detection section 62 Timing chart for explaining the states of failure determination signals, etc. before and after the diode 30c has an open failure Timing chart for explaining the states of failure determination signals, etc. before and after the diode 31c has an open failure A diagram showing a configuration example of a diode failure detection section 60A according to a modification example. A diagram showing a configuration example of a diode failure detection unit 61A according to a modification example. A diagram showing a configuration example of a vehicle in which an inverter device including a power conversion device 1 according to the present embodiment is mounted. A diagram showing an example of the configuration of a railway vehicle on which a train propulsion device including a power conversion device 1 according to the present embodiment is mounted. A diagram showing a configuration example of a server including a power conversion device 1 according to the present embodiment

EMBODIMENT OF THE INVENTION Below, the power conversion device, electric vehicle, railway vehicle, and server which concern on embodiment of this invention are demonstrated in detail based on drawing. Note that the present invention is not limited to this embodiment.

Embodiment FIG. 1 is a diagram showing a configuration example of a power conversion device according to an embodiment of the present invention. A DC power supply 100 is connected to the primary side of the power converter 1, and a DC load 200 is connected to the secondary side of the power converter 1. The power converter 1 is a DC/DC converter circuit that converts a DC voltage from a DC power supply 100 into a DC voltage of a desired voltage value and inputs the DC voltage to a DC load 200.

The power converter 1 includes a capacitor 11 and a capacitor 12 connected in series, a power device 13, a center-tapped isolation transformer 14, a rectifier 40, a current detector 35a, a current detector 35b, a DC voltage detector 17, and an output current. It includes a detector 18, a control section 19, and a gate drive circuit 20.

A series connection body of a capacitor 11 and a capacitor 12 and a power device 13 are connected in parallel to the DC power supply 100 . One end of the series connection body is connected to the positive electrode of DC power supply 100 and one end of power device 13 . The other end of the series connection body is connected to the negative electrode of DC power supply 100 and the other end of power device 13 . A mutual connection point 2 of the capacitor 11 and the capacitor 12 is connected to one end of the primary winding 14 a of the center-tapped isolation transformer 14 .

The power device 13 is a voltage converter that converts a DC voltage into an AC voltage by complementary operation of an upper arm switching element 13a and a lower arm switching element 13b connected in series to the upper arm switching element 13a.

The upper arm switching element 13a and the lower arm switching element 13b are, for example, N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Note that the upper arm switching element 13a and the lower arm switching element 13b are not limited to N-channel MOSFETs, and may be FETs (Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), or the like.

One end of the series connection of the upper arm switching element 13a and the lower arm switching element 13b is connected to the positive electrode of the DC power supply 100 and the capacitor 11. The other end of the series connection body is connected to the negative electrode of DC power supply 100 and capacitor 12 . A mutual connection point 3 of the upper arm switching element 13a and the lower arm switching element 13b is connected to the other end of the primary winding 14a of the center-tapped isolation transformer 14. Hereinafter, the upper arm switching element 13a may be simply referred to as an "upper arm" and the lower arm switching element 13b may simply be referred to as a "lower arm."

The rectifier 40 includes a diode 30a and a diode 30b that are a plurality of first diodes for rectification, and a diode 31a and a diode 31b that are a plurality of second diodes for rectification. In addition, the rectifier 40 includes a diode 30c, which is a third diode that is connected in parallel with the first diode and whose current is not detected by the current detector 35a and the current detector 35b, and the current detector 35a and the current detector 35b. The diode 31c is a fourth diode connected in parallel with the second diode. The rectifier 40 also includes a smoothing reactor 15 and a smoothing capacitor 16 that smooth the voltage rectified by the first diode, the second diode, the third diode, and the fourth diode. Hereinafter, the diodes 30a, 30b, 30c, 31a, 31b, and 31c will be referred to as "rectifier diodes" unless they are distinguished from each other. Moreover, below, the six diodes 30a, diode 30b, diode 30c, diode 31a, diode 31b, and diode 31c may be referred to as "a plurality of rectifier diodes."

The diode 30a, the diode 30b, and the diode 30c are connected in parallel between the positive output terminal P of the center-tapped isolation transformer 14 and one end of the smoothing reactor 15. The anodes of the diodes 30a, 30b, and 30c are connected to one end of the secondary winding 14b via the positive output terminal P of the center-tapped isolation transformer 14. Each cathode of diode 30a, diode 30b, and diode 30c is connected to one end of smoothing reactor 15.

The diode 31a, the diode 31b, and the diode 31c are connected in parallel between the negative output terminal N of the center-tapped isolation transformer 14 and one end of the smoothing reactor 15. The anodes of the diodes 31a, 31b, and 31c are connected to the other end of the secondary winding 14b via the negative output terminal N of the center-tapped isolation transformer 14.

Each cathode of the diode 31a, the diode 31b, and the diode 31c is connected to one end of the smoothing reactor 15.

The other end of the smoothing reactor 15 is connected to one end of the smoothing capacitor 16 and one end of the DC load 200. The other end of the smoothing capacitor 16 is connected to an intermediate output terminal M provided at the center tap of the center-tapped isolation transformer 14 .

The DC voltage detector 17 detects the voltage applied to the smoothing capacitor 16 and inputs a voltage detection value indicating the value of the detected voltage to the control unit 19.

The current detector 35a detects the sum of the current flowing through one of the plurality of first diodes (diode 30a) connected in parallel and the current flowing through one of the plurality of second diodes (diode 31a) connected in parallel. 1 current detector. The current detector 35a inputs a current detection value indicating the sum of detected currents to the control unit 19. Below, the current detection value may be referred to as "35a current detection value."

The current detector 35b detects the sum of the current flowing through the other of the plurality of first diodes (diode 30b) connected in parallel and the current flowing through the other of the plurality of second diodes (diode 31b) connected in parallel. 2 current detector. The current detector 35b inputs a current detection value indicating the sum of detected currents to the control unit 19. Below, the current detection value may be referred to as a "35b current detection value."

Next, the configuration of the control section 19 will be explained with reference to FIG. FIG. 2 is a diagram showing an example of the configuration of the control section. The control section 19 includes a voltage control section 50, a diode failure detection section 60, a diode failure detection section 61, a diode failure detection section 62, and a failure processing section 63.

The voltage control section 50 includes an AVR (Automatic Voltage Regulator) 51 that is a voltage control section and a PWM signal generation section 52. The AVR 51 is realized by a comparator, a PI (Proportional Integral) controller, and the like. For example, the AVR 51 determines the deviation between the voltage detection value detected by the DC voltage detector 17 and the target voltage, calculates a voltage command that makes this deviation zero, and inputs it to the PWM signal generation section 52.

The PWM signal generation unit 52 can be realized, for example, by a processor or the like reading a program stored in a memory realized by a ROM (Read Only Memory) or the like into a main memory realized by a RAM or the like and executing the program. . By comparing the input voltage command and the carrier signal, the PWM signal generation unit 52 generates an upper arm ON signal, which is a PWM signal that turns on the upper arm, and a lower arm ON signal, which is a PWM signal that turns on the lower arm. The arm ON signal is generated and input to the gate drive circuit 20. Note that the PWM signal is a rectangular wave signal that takes two values, high level or low level, and when the PWM signal is high level, the upper arm and lower arm are in the ON state, so the upper arm ON signal and the lower arm ON signal Each represents a signal when the PWM signal is at a high level.

The gate drive circuit 20 amplifies the input upper arm ON signal to a signal having a value that enables the upper arm to operate, and inputs the amplified signal to the upper arm. Further, the gate drive circuit 20 amplifies the input lower arm ON signal to a signal having a value that enables the lower arm to operate, and inputs the amplified signal to the lower arm. As a result, the upper arm and the lower arm perform complementary ON/OFF operations, and DC voltage is converted to AC voltage.

The diode failure detection section 60 receives the upper arm ON signal and lower arm ON signal from the PWM signal generation section 52, the output current detection value from the output current detector 18, and the 35a current detection value from the current detector 35a. Based on this, two failure determination signals are calculated and input to the failure processing section 63. Of the two failure determination signals, one is a signal indicating that the diode 30a has an open failure, and the other is a signal indicating that the diode 31a has an open failure. Hereinafter, a signal indicating that the diode 30a has an open failure may be referred to as a "30a failure determination signal", and a signal indicating that the diode 31a has an open failure may be referred to as a "31a failure determination signal".

An example of the configuration of the diode failure detection section 60 will be described with reference to FIG. 3. FIG. 3 is a diagram showing an example of the configuration of the diode failure detection section 60. The diode failure detection section 60 includes a comparator 300a, a comparator 300b, an AND device 301a, and an AND device 301b.

Comparator 300a compares the detected current value 35a with open abnormality determination current threshold 400. The open-circuit abnormality determination current threshold 400 is a threshold for determining an abnormality due to an open-circuit failure of the first diode and the second diode. The open abnormality determination current threshold 400 is set in advance in a memory, for example, and is set to a current value of 3% of the rated diode current. When the detected current value 35a is higher than the open abnormality determination current threshold 400, the output of the comparator 300a is at a low level. When the current detection value 35a is lower than the open abnormality determination current threshold 400, the output of the comparator 300a is at a high level.

Comparator 300b compares the output current detection value and output state determination current threshold 401. The output state determination current threshold 401 is set in advance in a memory, for example, and is set to a current value of 3% of the rated output current. When the output current detection value is lower than the output state determination current threshold 401, the output of the comparator 300b is at a low level. When the detected output current value is higher than the output state determination current threshold 401, the output of the comparator 300b is at a high level.

If the output of the comparator 300a is at high level and the output of the comparator 300b is at high level when the upper arm ON signal is output, the AND circuit 301a selects one of the first diodes (diode 30a). It is determined that an open failure has occurred. At this time, the output of the AND device 301a becomes a high level, and the failure determination signal 30a is input to the failure processing section 63 in FIG. Under other input conditions, the output of the AND device 301a is at a low level.

If the output of the comparator 300a is at high level and the output of the comparator 300b is at high level when the lower arm ON signal is output, the AND circuit 301b selects one of the second diodes (diode 31a). It is determined that an open failure has occurred. At this time, the output of the AND device 301b becomes a high level, and the failure determination signal 31a is input to the failure processing section 63 in FIG. Under other input conditions, the output of the AND device 301b is at a low level.

In this way, the diode failure detection unit 60 can prevent false detection by determining that the output is in a certain level of output state by using the comparison result between the detected output current value and the output state determination current threshold 401.

Next, referring to FIG. 4A, the operation of outputting the 30a failure determination signal from the AND device 301a will be specifically described. FIG. 4A is a timing chart for explaining the states of the failure determination signal and the like before and after the diode 30a has an open failure.

FIG. 4A shows, in order from the top, the values of the current flowing through each of the diode 30a, diode 30b, diode 30c, diode 31a, diode 31b, and diode 31c, the current detection value of 35a, the current detection value of 35b, and the upper arm ON state. A lower arm ON signal and a failure determination signal 30a are shown. The horizontal axis in FIG. 4A is time.

Time t1 represents the timing at which the diode 30a has an open failure. The waveforms of each current value and each signal before time t1 are waveforms when the diode 30a is normal, that is, when the diode 30a has not experienced an open failure.

Under normal conditions, the current detection value 35a is constant. When the diode 30a has an open failure at time t1, the value of the current flowing through the diode 30a becomes 0 [A], and the detected current value of the diode 35a becomes equal to the value of the current flowing through the diode 31a. At this time, the AND device 301a determines that the current value flowing through the diode 30a is 0 at time t2, which is the timing at which the PWM signal that drives the upper arm changes from low level to high level (timing at which the upper arm ON signal is input). By determining that it is [A], a 30a failure determination signal is output.

Next, referring to FIG. 4B, the operation of outputting the failure determination signal 31a from the AND device 301b will be specifically described. FIG. 4B is a timing chart for explaining the states of the failure determination signal and the like before and after the diode 31a has an open failure.

In FIG. 4B, a failure determination signal 31a is shown instead of the failure determination signal 30a in FIG. 4A. Time t3 represents the timing at which the diode 31a has an open failure. The waveforms of each current value and each signal before time t3 are waveforms when the diode 31a is normal, that is, when the diode 31a has not experienced an open failure.

Under normal conditions, the current detection value 35a is constant. When the diode 31a has an open circuit failure at time t3, the current value flowing through the diode 31a becomes 0 [A], and the detected current value 35a becomes equal to the current value flowing through the diode 30a. At this time, the AND device 301b determines that the current value flowing through the diode 31a is 0 at time t4, which is the timing at which the PWM signal that drives the lower arm changes from low level to high level (timing at which the lower arm ON signal is input). By determining that it is [A], the 31a failure determination signal is output.

The diode failure detection section 61 shown in FIG. Based on the detected values, two failure determination signals are calculated and input to the failure processing section 63. Of the two failure determination signals, one is a signal indicating that the diode 30b has an open failure, and the other is a signal indicating that the diode 31b has an open failure. Hereinafter, a signal indicating that the diode 30b has an open failure may be referred to as a "30b failure determination signal," and a signal indicating that the diode 31b has an open failure may be referred to as a "31b failure determination signal."

Next, a configuration example of the diode failure detection section 61 will be explained with reference to FIG. FIG. 5 is a diagram showing an example of the configuration of the diode failure detection section 61. The diode failure detection section 61 includes a comparator 300c, a comparator 300d, an AND device 301c, and an AND device 301d.

Comparator 300c compares the detected current value 35b with open abnormality determination current threshold 400. The open abnormality determination current threshold 400 is set in advance in a memory, for example, and is set to a current value of 3% of the rated diode current. When the detected current value 35b is higher than the open abnormality determination current threshold 400, the output of the comparator 300c is at a low level. When the detected current value 35b is lower than the open abnormality determination current threshold 400, the output of the comparator 300c is at a high level.

Comparator 300d compares the output current detection value and output state determination current threshold 401. The output state determination current threshold 401 is set in advance in a memory, for example, and is set to a current value of 3% of the rated output current. When the detected output current value is lower than the output state determination current threshold 401, the output of the comparator 300d is at a low level. When the output current detection value is higher than the output state determination current threshold 401, the output of the comparator 300d is at a high level.

When the output of the comparator 300c is at high level and the output of the comparator 300d is at high level when the upper arm ON signal is output, the AND circuit 301c determines that the other of the first diodes (diode 30b) It is determined that an open failure has occurred. At this time, the output of the AND device 301c becomes a high level, and the failure determination signal 30b is input to the failure processing section 63 in FIG. Under other input conditions, the output of the AND device 301c is at a low level.

When the output of the comparator 300c is at a high level and the output of the comparator 300d is at a high level when the lower arm ON signal is output, the AND device 301d selects the other of the second diodes (diode 31b). It is determined that an open failure has occurred. At this time, the output of the AND device 301d becomes a high level, and the failure determination signal 31b is input to the failure processing section 63 in FIG. Under other input conditions, the output of the AND device 301d is at a low level.

In this way, the diode failure detection section 61 can prevent false detection by determining that the output state is to a certain degree by using the comparison result between the detected output current value and the output state determination current threshold value 401.

Next, referring to FIG. 6A, the operation of outputting the failure determination signal 30b from the AND device 301c will be specifically described. FIG. 6A is a timing chart for explaining the states of the failure determination signal and the like before and after the diode 30b has an open failure.

In FIG. 6A, a failure determination signal 30b is shown instead of the failure determination signal 30a in FIG. 4A. Time t5 represents the timing at which the diode 30b has an open failure. The waveforms of each current value and each signal before time t5 are waveforms when the diode 30b is normal, that is, when the diode 30b does not have an open failure.

Under normal conditions, the current detection value 35b is constant. When the diode 30b has an open failure at time t5, the value of the current flowing through the diode 30b becomes 0 [A], and the detected current value of the diode 35b becomes equal to the value of the current flowing through the diode 31b. At this time, the AND device 301c outputs a 30b failure determination signal by determining that the current value flowing through the diode 30b is 0 [A] at time t6, which is the timing at which the upper arm ON signal is input. do.

Next, referring to FIG. 6B, the operation of outputting the failure determination signal 31b from the AND device 301d will be specifically described. FIG. 6B is a timing chart for explaining the states of the failure determination signal and the like before and after the diode 31b has an open failure.

In FIG. 6B, a 31b failure determination signal is shown instead of the 30b failure determination signal in FIG. 6A. Time t7 represents the timing at which the diode 31b has an open failure. The waveforms of each current value and each signal before time t7 are waveforms when the diode 31b is normal, that is, when the diode 31b does not have an open failure.

Under normal conditions, the current detection value 35b is constant. When the diode 31b has an open failure at time t7, the current value flowing through the diode 31b becomes 0 [A], and the detected current value 35b becomes equal to the current value flowing through the diode 30b. At this time, the AND device 301d determines that the current value flowing through the diode 31b is 0 [A] at time t8, which is the timing at which the lower arm ON signal is input, and outputs a 31b failure determination signal. do.

The diode failure detection unit 62 shown in FIG. 2 calculates two failure determination signals based on the upper arm ON signal, the lower arm ON signal, the detected output current value, the detected current value 35a, and the detected current value 35b. and inputs it to the failure processing section 63. Of the two failure determination signals, one is a signal indicating that the diode 30c has an open failure, and the other is a signal indicating that the diode 31c has an open failure. Hereinafter, a signal indicating that the diode 30c has an open failure may be referred to as a "30c failure determination signal," and a signal indicating that the diode 31c has an open failure may be referred to as a "31c failure determination signal."

Next, a configuration example of the diode failure detection section 62 will be described with reference to FIG. FIG. 7 is a diagram showing an example of the configuration of the diode failure detection section 62. The diode failure detection unit 62 includes a divider 302, an adder 303, a comparator 300e, a comparator 300f, a comparator 300g, an ANDer 301e, an ANDer 301f, an ANDer 302a, and an ANDer 302b.

The divider 302 calculates the value of the current flowing through each of the plurality of rectifier diodes by dividing the detected output current value by the number of parallel rectifier diodes 403, which is information representing the number of rectifier diodes, for example. The result is input to adder 303. The number of rectifier diodes in parallel 403 is set in advance in a memory, for example, and is a theoretical average current flowing through one diode among a plurality of first diodes or second diodes connected in parallel.

Adder 303 adds open abnormality determination current addition value 402 to the calculation result of divider 302, and inputs the addition result to comparator 300e and comparator 300f. The open abnormality determination current addition value 402 is set in advance in a memory, for example, and is set to a current value of 3% of the rated diode current.

Comparator 300e compares the input addition result with the current detection value 35a. When the current detection value 35a is lower than the addition result, the output of the comparator 300e is at a low level. When the current detection value 35a is higher than the addition result, the output of the comparator 300e is at a high level.

The comparator 300f compares the input addition result and the current detection value 35b. When the detected current value 35b is lower than the addition result, the output of the comparator 300f is at a low level. When the detected current value 35b is higher than the addition result, the output of the comparator 300f is at a high level.

If the output of the comparator 300e is at high level and the output of the comparator 300f is at high level when the upper arm ON signal is output, the AND device 301e determines that the diode 30c has an open failure. do. At this time, the output of the AND device 301e becomes a high level and is input to the AND device 302a. Under other input conditions, the output of the AND device 301e is at a low level.

If the output of the comparator 300e is at a high level and the output of the comparator 300f is at a high level when the lower arm ON signal is output, the AND device 301f determines that the diode 31c has an open failure. do. At this time, the output of the AND device 301f becomes a high level and is input to the AND device 302b. Under other input conditions, the output of the AND device 301f is at a low level.

Comparator 300g compares the output current detection value and output state determination current threshold 401. The output state determination current threshold 401 is set in advance in a memory, for example, and is set to a current value of 3% of the rated output current. When the detected output current value is lower than the output state determination current threshold 401, the output of the comparator 300g is at a low level. When the output current detection value is higher than the output state determination current threshold 401, the output of the comparator 300g becomes high level and is input to the AND device 302a and the AND device 302b.

AND unit 302a outputs each of the current detection value 35a and the current detection value 35b to adder 303 when the outputs of AND unit 301e and comparator 300g are at high level, that is, when the upper arm ON signal is output. If it is higher than the calculation result and the output current detection value is higher than the output state determination current threshold 401, it is determined that the diode 30c has an open failure. At this time, the output of the AND device 302a becomes a high level, and the failure determination signal 30c is input to the failure processing section 63 in FIG.

AND unit 302b determines that each of the current detection value 35a and the current detection value 35b is input to adder 303 when the outputs of AND unit 301f and comparator 300g are at high level, that is, when the lower arm ON signal is output. If it is higher than the calculation result and the output current detection value is higher than the output state determination current threshold 401, it is determined that the diode 31c has an open failure. At this time, the output of the AND device 302b becomes a high level, and the 31c failure determination signal is input to the failure processing section 63 in FIG.

In this manner, the diode failure detection unit 62 can prevent erroneous detection by determining that the output is in a certain level of output state by using the comparison result between the output current detection value and the output state determination current threshold 401.

Next, referring to FIG. 8A, the operation of outputting the failure determination signal 30c from the AND device 302a will be specifically described. FIG. 8A is a timing chart for explaining the states of the failure determination signal and the like before and after the diode 30c has an open failure. In FIG. 8A, a failure determination signal 30c is shown instead of the failure determination signal 30a in FIG. 4A.

Time t9 represents the timing at which the diode 30c has an open failure. The waveforms of each current value and each signal before time t9 are waveforms when the diode 30c is normal, that is, when the diode 30c does not have an open failure.

During normal operation, the current detection value 35a and the current detection value 35b are each constant. When the diode 30c has an open failure at time t9, the value of the current flowing through the diode 30c becomes 0 [A], and the current that should originally flow through the diode 30c is distributed between the diode 30a and the diode 30b. Therefore, the value of the current flowing through each of the diode 30a and the diode 30b when the diode 30c is in failure becomes larger than the value of the current flowing through each of the diode 30a and the diode 30b when the diode 30c is normal. Therefore, the detected current values 35a and 35b detected when the diode 30c is in failure are larger than the detected current values 35a and 35b detected when the diode 30c is normal.

At this time, the AND device 302a determines that the detected current value 35a and the detected current value 35b after time t10, which is the timing at which the upper arm ON signal is input, are larger than the detected current value 35a and the detected current value 35b before time t10. By determining that this is the case, a 30c failure determination signal is output.

Next, referring to FIG. 8B, the operation of outputting the 31c failure determination signal from the AND device 302b will be specifically described. FIG. 8B is a timing chart for explaining the states of the failure determination signal and the like before and after the diode 31c has an open failure. In FIG. 8B, a 31c failure determination signal is shown instead of the 30c failure determination signal in FIG. 8A.

Time t11 represents the timing at which the diode 31c has an open failure. The waveforms of each current value and each signal before time t11 are waveforms when the diode 31c is normal, that is, when the diode 31c does not have an open failure.

During normal operation, the current detection value 35a and the current detection value 35b are each constant. When the diode 31c has an open failure at time t11, the value of the current flowing through the diode 31c becomes 0 [A], and the current that should originally flow through the diode 31c is distributed between the diode 31a and the diode 31b. Therefore, the value of the current flowing through each of the diode 31a and the diode 31b when the diode 31c fails is larger than the value of the current flowing through each of the diode 31a and the diode 31b when the diode 31c is normal. Therefore, the detected current values 35a and 35b detected when the diode 31c is in failure are larger than the detected current values 35a and 35b detected when the diode 31c is normal.

At this time, the AND device 302b determines that the detected current value 35a and the detected current value 35b after time t12, which is the timing at which the lower arm ON signal is input, are larger than the detected current value 35a and the detected current value 35b before time t12. By determining that this is the case, a 31c failure determination signal is output.

When the failure processing unit 63 shown in FIG. 2 receives the failure determination signal 30a, failure determination signal 31a, failure determination signal 30b, failure determination signal 31b, failure determination signal 30c, and failure determination signal 31c, 13a and the lower arm switching element 13b, or a stop signal that stops the output of power supplied to the DC load 200. Then, the failure processing unit 63 inputs, for example, the calculated stop signal or output suppression signal to the PWM signal generation unit 52 of the voltage control unit 50, and generates failure information indicating that a specific rectifier diode has failed. , is input to the host device 21.

The stop signal is, for example, a low enable signal that stops the PWM signal generation operation by the PWM signal generation section 52 of the voltage control section 50, that is, a low-level clock enable signal. The stop signal is output, for example, immediately after any one of the failure determination signals 30a to 31c is input. Therefore, the PWM signal generation section 52 of the voltage control section 50 that has input the stop signal stops the PWM signal generation operation, thereby disabling one or more healthy rectifier diodes (for example, the diode 30a) connected in parallel with the faulty rectifier diode (for example, the diode 30a). It is possible to prevent a large current from continuing to flow through the rectifying diodes (for example, the diode 30b and the diode 30c), and it is possible to suppress the destruction of healthy rectifying diodes.

To generate failure information, for example, table information that associates identification information for identifying each of a plurality of rectifier diodes with failure information indicating that a specific rectifier diode has failed is stored in advance in a memory. put. Then, when any of the failure determination signals 30a to 31c is input, the failure processing unit 63 identifies the rectifier diode corresponding to the failure determination signal by referring to the table information, and selects the rectifier diode that corresponds to the failure determination signal. The failure information indicating that the device has failed is read out and input to the host device 21. Thereby, for example, in a monitoring center where the host device 21 is installed, a worker who monitors the operating state of the power conversion device 1 can easily determine which rectifier diode has failed among the plurality of rectifier diodes. Therefore, for example, even if an open failure occurs in a rectifier diode at a cycle shorter than the regular inspection cycle of the power converter 1, a worker inspecting the power converter 1 must check the faulty rectifier diode among the multiple rectifier diodes. Temporary measures such as replacing only the rectifier diode can be taken.

Furthermore, since a faulty rectifier diode can be easily identified, even if the PWM signal generation operation is stopped due to a stop signal, quick recovery work is possible, and the restart of operation of the DC load 200 can be accelerated.

In this embodiment, an example of a configuration in which three diodes 30a, 30b, and 30c are connected in parallel, and three diodes 31a, 31b, and 31c are connected in parallel has been described. The number of connections may be 2 or less or 4 or more.

As described above, the power conversion device 1 according to the present embodiment operates complementary to the upper arm switching element and the lower arm switching element connected in series to the upper arm switching element, thereby converting the DC voltage. An isolation transformer including a voltage converter that converts into an alternating current voltage, a primary winding to which an upper arm switching element and a lower arm switching element are connected, and a secondary winding having a center tap, and the secondary winding. A first diode for rectification that is connected to one end and becomes conductive when the upper arm switching element is ON, and a rectifier diode that is connected to the other end of the secondary winding and becomes conductive when the lower arm switching element is ON. and a rectifier that rectifies the voltage of the secondary winding, and a current detector that detects the sum of the current flowing through the first diode and the current flowing through the second diode.

With this configuration, by using the sum of the current flowing through the first diode and the current flowing through the second diode, and the ON/OFF state of the switching element of the upper arm or the lower arm, a plurality of rectifier diodes connected in parallel can be selected. The failed diode can be identified from

Further, according to the present embodiment, the number of first diodes (for example, diode 30a, diode 30b, etc.) and second diodes (for example, diode 31a, diode 31b, etc.) connected in parallel is set to M (M is an integer greater than or equal to 2), and the number of current detectors is N (N is an integer greater than or equal to 1), the number N of current detectors is set to N=M-1.

With this configuration, the number of current detectors can be reduced compared to the case where a current detector is provided for each of a plurality of rectifier diodes, so the configuration of the power converter 1 is simplified, and it is inexpensive and reliable. A high-performance power conversion device 1 can be realized.

Note that the power conversion device 1 according to the present embodiment changes the open abnormality determination current threshold 400 and the output state determination current threshold 401 according to the detected current value 35a, the detected current value 35b, the detected output current value, etc. It may be configured as follows. This configuration example will be explained with reference to FIGS. 9 and 10.

FIG. 9 is a diagram showing a configuration example of a diode failure detection section 60A according to a modification. The diode failure detection section 60A includes a first threshold correction section 310 and a second threshold correction section 311 in addition to the configuration shown in FIG.

The first threshold value correction unit 310 receives, for example, the detected value of the current 35a that flows when a certain period of time (for example, tens of milliseconds to hundreds of milliseconds) has elapsed from the time when the DC load 200 is started, and selects a predetermined current value at this time. By calculating the first correction coefficient and multiplying the open abnormality determination current threshold 400 read from the memory by the first correction coefficient, the corrected open abnormality determination current threshold 400a is calculated and input to the comparator 300a.

By using the current detection value 35a after a certain period of time has elapsed from the time when the DC load 200 is started, appropriate threshold value correction can be performed while the rush current is suppressed. The first correction coefficient is calculated by using, for example, a map, a function, etc. that defines the correspondence between the number of rectifier diodes in parallel, the rated diode current, and the like.

By using the first threshold correction unit 310, for example, even if the specifications of the power converter 1 are changed depending on the number of rectifier diodes in parallel, the rated diode current, etc., an appropriate open abnormality judgment current threshold 400a is automatically set. can. Therefore, work such as changing the setting of the open circuit abnormality determination current threshold 400 is not necessary, and the manufacturing of the power conversion device 1 is facilitated and manufacturing costs can be reduced. Further, since an appropriate open abnormality determination current threshold 400a can be used, the accuracy of failure determination of the rectifier diode is improved, and a highly reliable power converter 1 can be realized.

The second threshold correction unit 311 receives, for example, a detected value of the output current that flows when a certain period of time (for example, several tens of ms to several hundreds of ms) has elapsed from the time when the DC load 200 is started, and selects a predetermined value at this time. By calculating the second correction coefficient and multiplying the output state determination current threshold value 401 read from the memory by the second correction coefficient, a corrected output state determination current threshold value 401a is calculated and inputted to the comparator 300b.

By using the output current detection value after a certain period of time has elapsed from the time when the DC load 200 is started, it is possible to perform appropriate threshold value correction while inrush current is suppressed. The second correction coefficient is calculated using, for example, a map, a function, etc. that defines the correspondence between the input current to the power converter 1, the rating of the DC load 200, and the like.

By using the second threshold value correction unit 311, for example, even if the output current detection value varies depending on the rating or application of the DC load 200 connected to the power converter 1, an appropriate output state determination current threshold 401a can be automatically set. Can be set as follows. Therefore, even if the rating, application, etc. of the DC load 200 are different, there is no need to reset the output state determination current threshold 401a, making it easier to manufacture the power converter 1 and reducing manufacturing costs. Further, since an appropriate output state determination current threshold 401a can be used, the accuracy of failure determination of the rectifier diode is improved, and a highly reliable power converter 1 can be realized.

Note that the diode failure detection section 60A may include both the first threshold correction section 310 and the second threshold correction section 311, or may include only one of them. By including both the first threshold value correction unit 310 and the second threshold value correction unit 311, the accuracy of failure determination of the rectifier diode is further improved compared to the case where only either one is provided, and a more reliable power conversion device can be achieved. 1 can be achieved.

FIG. 10 is a diagram showing a configuration example of a diode failure detection section 61A according to a modification. The diode failure detection section 61A includes a third threshold correction section 312 and a second threshold correction section 311 in addition to the configuration shown in FIG. Note that the second threshold value correction unit 311 is the same as that shown in FIG. 9, so the description thereof will be omitted below.

The third threshold value correction unit 312 inputs, for example, the detected value of the 35b current that flows when a certain period of time (for example, tens of milliseconds to hundreds of milliseconds) has elapsed from the time when the DC load 200 is activated, and By calculating the third correction coefficient and multiplying the open abnormality determination current threshold 400 read from the memory by the third correction coefficient, the corrected open abnormality determination current threshold 400b is calculated and input to the comparator 300c.

By using the current detection value 35b after a certain period of time has elapsed from the time when the DC load 200 is started, appropriate threshold value correction can be performed while the rush current is suppressed. The third correction coefficient is calculated using, for example, a map, a function, etc. that defines the correspondence between the number of rectifier diodes in parallel, the rated diode current, and the like.

By using the third threshold value correction unit 312, an appropriate open abnormality determination current threshold value 400b can be set, for example, even when the specifications of the power conversion device 1 are changed depending on the number of rectifier diodes in parallel, the rated diode current, etc. Therefore, work such as changing the setting of the open circuit abnormality determination current threshold 400 is not necessary, and the manufacturing of the power conversion device 1 is facilitated and manufacturing costs can be reduced. Moreover, since an appropriate open abnormality determination current threshold 400b can be used, the accuracy of failure determination of the rectifier diode is improved, and a highly reliable power converter 1 can be realized.

Note that the diode failure detection section 61A may include both the third threshold value correction section 312 and the second threshold value correction section 311, or may include only one of them. By including both the third threshold value correction unit 312 and the second threshold value correction unit 311, the accuracy of failure determination of the rectifier diode is further improved compared to the case where only either one is provided, and the power conversion device has higher reliability. 1 can be achieved.

Note that the power conversion device 1 according to the present embodiment can be used, for example, in electric vehicles, railway vehicles, servers, etc., and can significantly improve the reliability and maintainability of the circuit that drives the motor, as well as improve the motor drive. Even if the system is stopped, it becomes easy to identify the faulty rectifier diode, allowing for early recovery. An example of mounting the power conversion device 1 on an electric vehicle, a railway vehicle, a server, etc. will be described with reference to FIGS. 11 to 13.

FIG. 11 is a diagram showing an example of the configuration of a vehicle in which an inverter device including the power conversion device 1 according to the present embodiment is mounted.

Vehicle 160 is, for example, an EV (Electric Vehicle). The vehicle 160 includes a motor 203 that is a main motor such as a synchronous rotating electrical machine or an induction rotating electrical machine that generates driving force when the vehicle 160 runs, and a high-voltage battery 201 that is a storage battery that stores electric power to drive the motor 203. It includes an inverter device 150 that converts the DC voltage input from the high voltage battery 201 into an AC voltage and applies it to the motor 203.

Inverter device 150 includes power converter device 1 according to the present embodiment, control section 70, and signal insulating section 207 such as a photocoupler.

The control unit 70 includes an ECU 72 that controls the inverter circuit 54 in an integrated manner. The ECU 72 is driven by power supplied from the low voltage battery 71. When controlling the motor 203, the ECU 72, for example, determines the values of at least two currents (for example, U-phase and W-phase currents) among the U, V, and W phase currents detected by the current detection unit 204. Based on the current detection signal shown, a pulse width modulation signal is generated so that each of the three-phase currents flowing through the motor 203 has a target value corresponding to the target torque. The pulse width modulation signal is input to the inverter circuit 54 via the signal insulator 207. As the on-duty of the pulse width modulation signal changes, the average value of the output current (AC voltage) of the inverter circuit 54 changes. The current detection unit 204 is a current detection means such as a shunt resistor that detects the current flowing through the three-phase AC wiring provided between the inverter circuit 54 and the motor 203.

Note that the vehicle 160 is not limited to an EV, and may be any electric vehicle including a high-voltage battery 201, an inverter device 150, and a motor 203, such as a hybrid vehicle or a plug-in hybrid vehicle.

FIG. 12 is a diagram showing an example of the configuration of a railway vehicle on which a train propulsion device including the power conversion device 1 according to the present embodiment is mounted.

The railway vehicle 170 includes a train propulsion device 180, a train braking device 191, an automatic train operation device 192, a train safety device 193, an on-board radio device 194, and a master controller 195.

Train propulsion device 180 includes power conversion device 1 according to the present embodiment, control unit 182, voltage detector 181 that detects input voltage ES, inverter 183, and electric motor 184.

DC power from the DC overhead wire 5 is input via the current collector 6, and the DC power is supplied to the power converter 1. At this time, a voltage value indicating the voltage value of the DC overhead wire 5 detected by the voltage detector 181 is input to the control unit 182. Further, an operation command from the master controller 195 is input to the control unit 182 . The driving commands include a power running command, a brake command, a coasting command, and the like. For example, when a power running command is output from the master controller 195, the power conversion device 1 operates as a DC/DC converter, converts the DC voltage from the DC overhead wire 5 into a DC voltage of a different value, and supplies the DC voltage to the inverter 183. input. Then, the control unit 182 generates a control signal for controlling the switching elements in the inverter 183 based on the voltage value detected by the voltage detector 181, the power running command from the master controller 195, etc., and inputs it to the inverter 183. Thereby, inverter 183 converts the input DC voltage into AC voltage and inputs it to electric motor 184 .

FIG. 13 is a diagram showing an example of the configuration of a server including the power conversion device 1 according to the present embodiment. Server 500 includes power conversion device 1 according to the present embodiment, CPU (Central Processing Unit) 501, storage device 502, network I/F 503, input I/F 504, and output I/F 505.

The CPU 501 is an arithmetic device that uses the power supplied from the power converter 1 as a driving source to perform calculations and process various data to realize various processes and controls. The storage device 502 stores data, programs, setting values, and the like.

The network I/F 503 transmits and receives various data and the like to and from devices connected via a network such as the Internet and a LAN (Local Area Network). For example, the network I/F 503 is a connector to which a NIC (Network Interface Controller) and a LAN cable are connected. Note that the network I/F 503 is not limited to an I/F that uses a network, but may be an I/F that transmits and receives data to and from an external device using a cable, wireless, connector, or the like.

The input I/F 504 is a user interface through which various operations performed by a system administrator or the like are input. For example, the input I/F 504 includes an input device such as a keyboard, a connector for connecting the input device to the server 500, and the like.

The output I/F 505 is an interface with a system administrator or the like who uses the server 500. Specifically, the output I/F 505 outputs the processing results of various processes performed by the server 500 to a system administrator or the like. For example, the output I/F 505 is an output device such as a display and a connector for connecting the output device to the server 500.

The configurations shown in the embodiments described above are examples of the contents of the present invention, and can be combined with other known techniques, and the configurations can be modified without departing from the gist of the present invention. It is also possible to omit or change parts.

1: Power converters 2, 3: Connection point 5: DC overhead wire 6: Current collectors 11, 12: Capacitor 13: Power device 13a: Upper arm switching element 13b: Lower arm switching element 14: Center-tapped isolation transformer 14a: Primary winding 14b: Secondary winding 15: Smoothing reactor 16: Smoothing capacitor 17: DC voltage detector 18: Output current detector 19: Control unit 20: Gate drive circuit 21: Host device 30a, 30b, 30c , 31a, 31b, 31c: diodes 35a, 35b: current detector 40: rectifier 50: voltage controller 51: AVR
52: PWM signal generation section 54: Inverter circuit 60, 60A, 61, 61A, 62: Diode failure detection section 63: Failure processing section 70: Control section 71: Low voltage battery 72: ECU
100: DC power supply 150: Inverter device 160: Vehicle 170: Railway vehicle 180: Train propulsion device 181: Voltage detector 182: Control unit 183: Inverter 184: Electric motor 191: Train braking device 192: Automatic train operation device 193: Train security Device 194: On-board radio device 195: Masu controller 200: DC load 201: High voltage battery 203: Motor 204: Current detection section 207: Signal insulation section 300a, 300b, 300c, 300d, 300e, 300f, 300g: Comparator 301a, 301b, 301c, 301d, 301e, 301f: AND device 302: Divider 302a, 302b: AND device 303: Adder 310: First threshold correction section 311: Second threshold correction section 312: Third threshold correction section 400, 400a, 400b : Open abnormality judgment current threshold 401, 401a: Output state judgment current threshold 402: Open abnormality judgment current addition value 403: Number of parallel rectifier diodes 500: Server 501: CPU
502: Storage device 503: Network I/F
504: Input I/F
505: Output I/F
ES: input voltage

Claims (10)

a voltage converter that converts a DC voltage into an AC voltage by complementary operation of an upper arm switching element and a lower arm switching element connected in series to the upper arm switching element;
an isolation transformer having a primary winding to which the upper arm switching element and the lower arm switching element are connected, and a secondary winding having a center tap;
a first diode for rectification that is connected to one end of the secondary winding and becomes conductive when the upper arm switching element is turned on; and the lower arm switching element is connected to the other end of the secondary winding and is turned on. a rectifier having a second diode for rectification that becomes conductive when , and rectifying the voltage of the secondary winding;
a current detector that detects the sum of the current flowing through the first diode and the current flowing through the second diode;
Equipped with
The number of the first diodes and the second diodes connected in parallel is M (M is an integer of 2 or more), and the number of current detectors is N (N is an integer of 1 or more). When,
The power conversion device , wherein the number N of the current detectors is set to N=M-1 . a voltage converter that converts a DC voltage into an AC voltage by complementary operation of an upper arm switching element and a lower arm switching element connected in series to the upper arm switching element;
an isolation transformer having a primary winding to which the upper arm switching element and the lower arm switching element are connected, and a secondary winding having a center tap;
a first diode for rectification that is connected to one end of the secondary winding and becomes conductive when the upper arm switching element is turned on; and the lower arm switching element is connected to the other end of the secondary winding and is turned on. a rectifier having a second diode for rectification that becomes conductive when , and rectifying the voltage of the secondary winding;
a current detector that detects the sum of the current flowing through the first diode and the current flowing through the second diode;
Equipped with
When the upper arm switching element is ON,
The current value detected by the current detector that detects the sum of the current flowing through one of the plurality of first diodes connected in parallel and the current flowing through one of the plurality of second diodes connected in parallel is When the current is lower than an open abnormality determination current threshold for determining an abnormality due to an open failure of the first diode and the second diode,
A power conversion device that determines that one of the plurality of first diodes connected in parallel has failed, and stops the power conversion device or suppresses the output of the power conversion device. a voltage converter that converts a DC voltage into an AC voltage by complementary operation of an upper arm switching element and a lower arm switching element connected in series to the upper arm switching element;
an isolation transformer having a primary winding to which the upper arm switching element and the lower arm switching element are connected, and a secondary winding having a center tap;
a first diode for rectification that is connected to one end of the secondary winding and becomes conductive when the upper arm switching element is turned on; and the lower arm switching element is connected to the other end of the secondary winding and is turned on. a rectifier having a second diode for rectification that becomes conductive when , and rectifying the voltage of the secondary winding;
a current detector that detects the sum of the current flowing through the first diode and the current flowing through the second diode;
Equipped with
When the lower arm switching element is ON,
The current value detected by the current detector that detects the sum of the current flowing through one of the plurality of first diodes connected in parallel and the current flowing through one of the plurality of second diodes connected in parallel is When the current is lower than an open abnormality determination current threshold for determining an abnormality due to an open failure of the first diode and the second diode,
A power conversion device that determines that one of the plurality of second diodes connected in parallel has failed, and stops the power conversion device or suppresses the output of the power conversion device. When the upper arm switching element is ON,
The current value detected by the current detector that detects the sum of the current flowing through the other of the plurality of first diodes connected in parallel and the current flowing through the other of the plurality of second diodes connected in parallel is When the current is lower than an open abnormality determination current threshold for determining an abnormality due to an open failure of the first diode and the second diode,
The power conversion device according to any one of claims 1 to 3 , wherein it is determined that the other of the plurality of first diodes connected in parallel has failed, and the power conversion device is stopped or the output of the power conversion device is suppressed. When the lower arm switching element is ON,
The current value detected by the current detector that detects the sum of the current flowing through the other of the plurality of first diodes connected in parallel and the current flowing through the other of the plurality of second diodes connected in parallel is When the current is lower than an open abnormality determination current threshold for determining an abnormality due to an open failure of the first diode and the second diode,
The power conversion device according to any one of claims 1 to 4 , wherein it is determined that the other of the plurality of second diodes connected in parallel has failed, and the power conversion device is stopped or the output of the power conversion device is suppressed. a voltage converter that converts a DC voltage into an AC voltage by complementary operation of an upper arm switching element and a lower arm switching element connected in series to the upper arm switching element;
an isolation transformer having a primary winding to which the upper arm switching element and the lower arm switching element are connected, and a secondary winding having a center tap;
a first diode for rectification that is connected to one end of the secondary winding and becomes conductive when the upper arm switching element is turned on; and the lower arm switching element is connected to the other end of the secondary winding and is turned on. a rectifier having a second diode for rectification that becomes conductive when , and rectifying the voltage of the secondary winding;
a current detector that detects the sum of the current flowing through the first diode and the current flowing through the second diode;
Equipped with
When the upper arm switching element is ON,
a current value detected by the current detector that detects the sum of a current flowing through one of the plurality of first diodes connected in parallel and a current flowing through one of the plurality of second diodes connected in parallel; The current value detected by the current detector that detects the sum of the current flowing through the other of the plurality of first diodes connected and the current flowing through the other of the plurality of second diodes connected in parallel is If it is higher than the theoretical average current flowing through one diode among the plurality of connected first diodes or second diodes,
A power conversion device that determines that current detection by the current detector is not performed and a third diode connected in parallel with the first diode has failed, and stops the power conversion device or suppresses output of the power conversion device. . a voltage converter that converts a DC voltage into an AC voltage by complementary operation of an upper arm switching element and a lower arm switching element connected in series to the upper arm switching element;
an isolation transformer having a primary winding to which the upper arm switching element and the lower arm switching element are connected, and a secondary winding having a center tap;
a first diode for rectification that is connected to one end of the secondary winding and becomes conductive when the upper arm switching element is turned on; and the lower arm switching element is connected to the other end of the secondary winding and is turned on. a rectifier having a second diode for rectification that becomes conductive when , and rectifying the voltage of the secondary winding;
a current detector that detects the sum of the current flowing through the first diode and the current flowing through the second diode;
Equipped with
When the lower arm switching element is ON,
a current value detected by the current detector that detects the sum of a current flowing through one of the plurality of first diodes connected in parallel and a current flowing through one of the plurality of second diodes connected in parallel; The current value detected by the current detector that detects the sum of the current flowing through the other of the plurality of first diodes connected and the current flowing through the other of the plurality of second diodes connected in parallel is If it is higher than the theoretical average current flowing through one diode among the plurality of connected first diodes or second diodes,
A power conversion device that determines that current detection by the current detector is not performed and a fourth diode connected in parallel with the second diode has failed, and stops the power conversion device or suppresses output of the power conversion device. . An electric vehicle comprising the power conversion device according to any one of claims 1 to 7 . A railway vehicle comprising the power conversion device according to any one of claims 1 to 7 . A server comprising the power conversion device according to any one of claims 1 to 7 .

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