WO2021205586A1

WO2021205586A1 - Power conversion device

Info

Publication number: WO2021205586A1
Application number: PCT/JP2020/015903
Authority: WO
Inventors: 道夫大坪
Original assignee: 三菱電機株式会社
Priority date: 2020-04-09
Filing date: 2020-04-09
Publication date: 2021-10-14
Also published as: JPWO2021205586A1; JP7229425B2; DE112020007050T5

Abstract

A power conversion device (1) comprises: a filter capacitor (FC1) that is charged by power supplied from a power supply; a power conversion unit (11) that supplies electric power to an electric motor (51), converts electric power supplied from the electric motor (51) operating as a generator, and charges the filter capacitor (FC1); a circuit switching unit (12) that has a first resistor (CHR); a chopper circuit (13) that has a switching element (SW2) and a second resistor (BR) connected in series; and a discharge switch (SW1). In the chopper circuit (13), when the switching element (SW2) is turned on, the electric power supplied from the power conversion unit (11) is consumed by the second resistor (BR). When the discharge switch (SW1) is turned on, the first resistor (CHR) and the second resistor (BR) are connected in series, and the filter capacitor (FC1) is connected to the first resistor (CHR) and the second resistor (BR) that are connected in series and is discharged.

Description

Power converter

This disclosure relates to a power conversion device.

Some electric railway vehicles are equipped with a power converter that converts the DC power supplied from the substation through the overhead wire into the desired AC power and supplies the converted power to the motor. An example of this type of power conversion device is disclosed in Patent Document 1. This power conversion device has a power conversion unit, a filter capacitor whose ends are connected to the primary terminal of the power conversion unit, a discharge circuit having a discharge resistor for discharging the filter capacitor, and an inrush current when charging the filter capacitor. It is provided with a charging resistor for suppressing.

Japanese Unexamined Patent Publication No. 2015-050854

Some electric railway vehicles can generate brakes by dynamic braking in addition to mechanical brakes. In the electric power conversion device disclosed in Patent Document 1, in order to enable braking of an electric railway vehicle by a dynamic braking method, a circuit for consuming electric power supplied from an electric motor operating as a generator is required. You will need it. Specifically, the power converter needs to further include a switching element connected in series and a brake chopper circuit having a brake resistor. As described above, the power conversion device has a discharge resistance, a charge resistance, and a brake resistance. For this reason, the power conversion device that enables the electric railroad vehicle to be braked by the dynamic braking method has resistance for each function, so that the structure becomes complicated and the size becomes large. Note that this problem can occur in any power conversion device that requires a plurality of resistors for each function.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a power conversion device having a simple structure.

In order to achieve the above object, the power conversion device of the present disclosure includes a filter capacitor, a power conversion unit, a circuit switching unit, a chopper circuit, and a discharge switch. The filter capacitor is charged with DC power supplied from the power supply. In the power conversion unit, a filter capacitor is connected between the primary terminals, and the DC power supplied from the power supply via the filter capacitor is converted into DC power or AC power and supplied to the motor connected to the secondary terminal. .. Further, the power conversion unit converts DC power or AC power supplied from an electric motor operating as a generator into DC power and outputs the power to charge the filter capacitor. The circuit switching unit has a first resistor and electrically connects or electrically disconnects the power conversion unit and the filter capacitor from the power supply. The chopper circuit has a switching element and a second resistor connected in series. Further, both ends of the chopper circuit are connected between the primary terminals of the power conversion unit. One end of the discharge switch is connected to one end close to the power supply of the first resistor, and the other end is connected to the connection point between the switching element and the second resistor. When charging the filter capacitor with DC power supplied from the power supply, the circuit switching unit electrically connects the power conversion unit and the filter capacitor to the power supply via an electric path passing through the first resistor. In the chopper circuit, when the switching element is turned on, the DC power supplied from the power conversion unit via the filter capacitor is consumed by the second resistor. When the discharge switch is turned on, the filter capacitor is discharged by connecting the first resistor and the second resistor in series and electrically connecting the filter capacitor to the first resistor and the second resistor connected in series. ..

According to the present disclosure, the filter capacitor is discharged by connecting the first resistor and the second resistor in series and electrically connecting the filter capacitor to the first resistor and the second resistor connected in series. Therefore, it is not necessary to provide a resistor only for discharging the filter capacitor. Therefore, the structure of the power conversion device is simple.

Block diagram of the power conversion device according to the first embodiment The figure which shows the example of mounting on the railroad vehicle of the power conversion apparatus which concerns on Embodiment 1. Block diagram of the power conversion device according to the second embodiment A flowchart of an operation for determining the presence or absence of a short-circuit failure performed by the power conversion device according to the second embodiment. Block diagram of the first modification of the power conversion device according to the embodiment Block diagram of a second modification of the power conversion device according to the embodiment

Hereinafter, the power conversion device according to the embodiment of the present disclosure will be described in detail with reference to the drawings. In the figure, the same or equivalent parts are designated by the same reference numerals.

(Embodiment 1)
The power conversion device 1 according to the first embodiment will be described by taking a power conversion device mounted on a vehicle as an example.
The power conversion device 1 shown in FIG. 1 includes a positive electrode input terminal 1a connected to a power source and a negative electrode input terminal 1b to be grounded. The power conversion device 1 converts the DC power supplied from the power supply via the positive input terminal 1a into three-phase AC power for driving the motor 51, and supplies the three-phase AC power from the output terminal to the motor 51. do. The electric motor 51 is, for example, a three-phase induction motor. When the power conversion device 1 supplies the electric power 51 with three-phase AC power, the electric motor 51 is driven and the propulsive force of the vehicle is obtained. Further, the power conversion device 1 converts the three-phase AC power generated by the motor 51 operating as a generator into DC power when the vehicle is braked, and consumes it in the second resistance BR described later. As a result, a braking force for decelerating the vehicle is obtained.

The details of the power conversion device 1 will be described by taking as an example the case where the power conversion device 1 is mounted on a DC feeder type electric railway vehicle. As shown in FIG. 2, the current collector 52 acquires DC power from the substation via the overhead wire 53, and supplies the power to the power conversion device 1 via the high-speed circuit breaker 54. The current collector 52 corresponds to a power source that supplies electric power to the electric power converter 1. The high-speed circuit breaker 54 is controlled by a circuit breaker control unit (not shown) to electrically connect the current collector 52 and the power converter 1 or electrically cut off the power converter 1 from the current collector 52.

The power conversion device 1 has a pair of

primary terminals

11a and 11b, converts DC power supplied from the current collector 52 via the primary terminals 11a into three-phase AC power, and supplies power to the electric motor 51. The filter capacitor FC1 whose ends are connected to the

primary terminals

11a and 11b of the power conversion unit 11 and charged with the DC power supplied from the current collector 52, and the power conversion unit 11 and the filter capacitor FC1 are collected. A circuit switching unit 12 that is electrically connected to or electrically disconnected from the current collector 52 is provided.

Further, the power conversion device 1 has a chopper circuit 13 in which both ends are connected to the

primary terminals

11a and 11b of the power conversion unit 11 and consumes power generated by the electric motor 51 that operates as a generator when the electric railway vehicle is braked, and a circuit switching unit. The first resistance CHBR described later of 12 and the second resistance BR described later of the chopper circuit 13 are connected in series, and the filter capacitor FC1 is electrically connected to the first resistance CHR and the second resistance BR connected in series. A discharge switch SW1 for discharging the filter capacitor FC1 and a voltage measuring unit 14 for measuring the voltage value of the filter capacitor FC1 are provided.

The power conversion device 1 further includes a contactor control unit 15 that controls the circuit switching unit 12, specifically, switching the electric circuit of the circuit switching unit 12, a switching control unit 16 that controls the power conversion unit 11, and a chopper. A chopper control unit 17 for controlling the circuit 13 is provided.

The power conversion device 1 discharges the filter capacitor FC1 by the first resistance CHR and the second resistance BR, and consumes the power supplied from the motor 51 that operates as a generator when the electric railway vehicle is braked by the second resistance BR. conduct. Therefore, in order to consume the resistance used when charging the filter capacitor FC1, the resistance for discharging the filter capacitor FC1, and the electric power supplied from the motor 51 which operates as a generator when the electric railway vehicle is braked. Since it is not necessary to provide each resistor, miniaturization is possible. The details of the structure of the power conversion device 1 will be described below.

The power conversion unit 11 converts the DC power supplied via the primary terminal 11a into three-phase AC power, and supplies the three-phase AC power to the motor 51 connected to each secondary terminal. Further, the power conversion unit 11 converts the three-phase AC power supplied from the motor 51 into DC power, and outputs the DC power from the primary terminal 11a. For example, the power conversion unit 11 is a VVVF (Variable Voltage Variable Frequency) inverter.

The filter capacitor FC1 is connected between the

primary terminals

11a and 11b of the power conversion unit 11, and is charged by the power acquired by the current collector 52 via the overhead wire 53.

The circuit switching unit 12 has a first resistance CHR, and when charging the filter capacitor FC1, the power conversion unit 11 is electrically connected to the current collector 52 via an electric path passing through the first resistance CHR. As a result, the inrush current is suppressed from flowing through the filter capacitor FC1 when the filter capacitor FC1 is charged. In other words, the first resistor CHR serves as a charging resistor that suppresses the inrush current flowing through the filter capacitor FC1 during charging. The resistance value of the first resistance CHR is arbitrary as long as it can suppress the inrush current, and is, for example, several tens of Ω.

Specifically, the circuit switching unit 12 is a contact with the first resistor CHR, which is a first contactor having one end connected to the current collector 52 via a high-speed circuit breaker 54 and located in parallel with the first resistor CHR. It includes a contactor MC1 and a contactor MC2, which is a second contactor whose one end is connected to the current collector 52 via a high-speed circuit breaker 54 and the other end is connected to one end of the first resistor CHR.

Specifically, one end of the first resistor CHR is connected to the contactor MC2, and the other end is connected to the primary terminal 11a of the power conversion unit 11.

One end of the contactor MC1 is connected to the high-speed circuit breaker 54, and the other end is connected to the primary terminal 11a of the power conversion unit 11. The contactor MC1 is a DC electromagnetic contactor and is controlled by the contactor control unit 15. When the contactor control unit 15 turns on the contactor MC1, one end and the other end of the contactor MC1 are connected to each other. When the contactor MC1 is turned on with the high-speed circuit breaker 54 turned on, the power conversion unit 11 and the filter capacitor FC1 are electrically connected to the current collector 52.
When the contactor control unit 15 opens the contactor MC1, one end and the other end of the contactor MC1 are insulated. When the contactor control unit 15 opens the contactor MC1 while the contactor MC2 is open, the power conversion unit 11 and the filter capacitor FC1 are electrically disconnected from the current collector 52.

One end of the contactor MC2 is connected to the high speed circuit breaker 54, and the other end is connected to one end of the first resistor CHR. The contactor MC2 is a DC electromagnetic contactor and is controlled by the contactor control unit 15. When the contactor control unit 15 turns on the contactor MC2, one end and the other end of the contactor MC2 are connected to each other. As a result, the high-speed circuit breaker 54 and the first resistor CHR are electrically connected. When the contactor MC2 is turned on with the high-speed circuit breaker 54 turned on, the power conversion unit 11 and the filter capacitor FC1 are electrically connected to the current collector 52.
When the contactor control unit 15 opens the contactor MC2, one end and the other end of the contactor MC2 are insulated. As a result, the first resistor CHR is electrically disconnected from the high speed circuit breaker 54.

The chopper circuit 13 includes a switching element SW2 and a second resistor BR connected in series. When the chopper circuit 13 is turned on, the second resistor BR consumes the DC power supplied from the power conversion unit 11 via the filter capacitor FC1. In other words, the chopper circuit 13 serves as a brake chopper that enables the vehicle to be braked by the dynamic braking system, and the BR in the second boat storage serves as a brake resistance.

The switching element SW2 is an element capable of high-speed switching, for example, an IGBT (Insulated Gate Bipolar Transistor). In this case, the collector terminal of the switching element SW2 is connected to the connection point between the other end of the contactor MC1 and the primary terminal 11a of the power conversion unit 11, and the emitter terminal is connected to one end of the second resistor BR. A chopper control signal S3 from the chopper control unit 17, which will be described later, is input to the gate terminal.
One end of the second resistor BR is connected to the emitter terminal of the switching element SW2, and the other end is grounded. When the switching element SW2 is turned on, the filter capacitor FC1 is connected to the second resistor BR. As a result, the second resistor BR is supplied from the motor 51 operating as a generator, converted by the power conversion unit 11, and consumes the DC power supplied through the filter capacitor FC1. The resistance value of the second resistor BR is arbitrary as long as it can generate the braking force of the electric railroad vehicle by consuming the DC power supplied through the filter capacitor FC1, for example, with a few Ω. be.

One end of the discharge switch SW1 is connected to one end close to the power supply of the first resistor CHR, specifically, to the connection point between the contactor MC2 and the first resistor CHR. The other end of the discharge switch SW1 is connected to the connection point between the switching element SW2 and the second resistor BR. The discharge switch SW1 is a knife switch. A maintenance worker who performs maintenance work on the power conversion device 1 mechanically operates the discharge switch SW1 to turn the discharge switch SW1 on or off.

Specifically, the maintenance worker turns on the discharge switch SW1 with the contactors MC1 and MC2 both open. When the discharge switch SW1 is turned on, both ends of the discharge switch SW1 are electrically connected, and the first resistor CHR and the second resistor BR are connected in series. As a result, the filter capacitor FC1 is electrically connected to the first resistor CHR and the second resistor BR connected in series. Therefore, the filter capacitor FC1 is discharged by the first resistor CHR and the second resistor BR connected in series. When the discharge switch SW1 is turned off, both ends of the discharge switch SW1 are insulated.

The voltage measuring unit 14 is connected to the

primary terminals

11a and 11b of the power conversion unit 11 and measures the value of the voltage between the terminals of the filter capacitor FC1. Then, the voltage measuring unit 14 supplies a signal indicating the measured voltage value to the contactor control unit 15, the switching control unit 16, and the chopper control unit 17.

The contactor control unit 15 is supplied with an open / close instruction signal instructing the contactors MC1 and MC2 to be turned on or off from a driver's cab (not shown). Further, the contactor control unit 15 turns on or opens the contactors MC1 and MC2 according to the opening / closing instruction signal. Specifically, the contactor control unit 15 sends a contactor control signal S1 instructing the contactors MC1 and MC2 to be turned on or off, and controls the contactors MC1 and MC2.

An operation command is supplied to the switching control unit 16 from a driver's cab (not shown). The operation command includes a power running command indicating the target acceleration of the electric railway vehicle, a brake command indicating the target deceleration of the electric railway vehicle, and the like. As will be described later, the switching control unit 16 sends a switching control signal S2 to the switching element included in the power conversion unit 11 in response to an operation command to control the switching element.

An operation command is supplied to the chopper control unit 17 from a driver's cab (not shown). The chopper control unit 17 switches on / off the switching element SW2 of the chopper circuit 13 when the operation command includes the brake command. Specifically, the chopper control unit 17 sends a chopper control signal S3 for adjusting the flow rate of the switching element SW2 of the chopper circuit 13 so that a regenerative braking force can be obtained when the operation command includes a brake command. It is supplied to the gate terminal of the switching element SW2.

Next, the operation of the power conversion device 1 having the above configuration will be described.
When the electric railway vehicle is started, an ascending switch for raising the pantograph, which is an example of the current collector 52, is operated, and when the current collector 52 comes into contact with the overhead wire 53, the current collector 52 receives power from the substation. Receive supply. Further, in conjunction with the operation of the rise switch, the high-speed circuit breaker 54 is turned on, and the power conversion device 1 is electrically connected to the current collector 52.

Further, in conjunction with the operation of the rise switch, an open / close instruction signal for instructing the start is supplied to the contactor control unit 15. When the contactor control unit 15 is supplied with the opening / closing instruction signal instructing the start, the contactor control unit 15 outputs the contactor control signal S1 instructing the contactor MC2 to be turned on. As a result, the contactor MC2 is turned on, and the electric power acquired from the substation by the current collector 52 via the overhead wire 53 is transferred to the filter capacitor FC1 via the high-speed circuit breaker 54, the contactor MC2, and the first resistor CHR. It is supplied and charging of the filter capacitor FC1 is started. Since the first resistor CHR is connected in series to the contactor MC2, the inrush current is suppressed from flowing through the filter capacitor FC1 when the contactor MC2 is turned on.

After that, when the filter capacitor FC1 is sufficiently charged, the contactor control unit 15 outputs a contactor control signal S1 instructing the contactor MC1 to be turned on. As a result, the contactor MC1 is turned on, and the electric power acquired from the substation by the current collector 52 via the overhead wire 53 is supplied to the filter capacitor FC1 via the high-speed circuit breaker 54 and the contactor MC1.

After that, the contactor control unit 15 outputs the contactor control signal S1 instructing the opening of the contactor MC2. As a result, the first resistor CHR is electrically disconnected from the current collector 52.

When the operation is started after the electric railway vehicle is started, the operation command from the cab is input to the switching control unit 16 and the chopper control unit 17. The operation of the switching control unit 16 and the chopper control unit 17 in response to the operation command will be described.

When the operation command includes a power running command, that is, when the electric railway vehicle is running, the switching control unit 16 controls the switching element of the power conversion unit 11 to drive the electric power 51 to the power conversion unit 11. Converted to three-phase AC power for.

Specifically, the switching control unit 16 calculates the target torque for obtaining the target acceleration indicated by the power running command. Further, the switching control unit 16 acquires a measured value of the current flowing through the motor 51 from a motor current measuring unit (not shown), and calculates the actual torque of the motor 51 from the acquired measured value. Specifically, the switching control unit 16 acquires the measured value of the phase current flowing through the motor 51 from the motor current measuring unit that measures the values of the U-phase, V-phase, and W-phase currents flowing through the motor 51, and the phase current. The actual torque of the motor 51 is calculated from the measured value of. Then, the switching control unit 16 sends a switching control signal S2 to the switching element of the power conversion unit 11 to control the switching element in order to bring the actual torque of the electric motor 51 closer to the target torque.

When the operation command includes a brake command, that is, when the electric railroad vehicle is braked, the motor 51 operates as a generator and supplies three-phase AC power to the power conversion unit 11.
In this case, the switching control unit 16 controls the switching element of the power conversion unit 11 to cause the power conversion unit 11 to convert the three-phase AC power into DC power. Then, the power conversion device 1 can supply electric power to other electric railway vehicles located in the vicinity via the overhead wire 53. As a result, a regenerative braking force is generated in the electric railway vehicle, and the electric railway vehicle decelerates.

For example, when it is not possible to supply electric power to the overhead wire 53 because another electric railway vehicle that is running power is not located in the vicinity, the electric power supplied from the electric motor 51 is consumed by the chopper circuit 13 to generate electric power brakes on the electric railway vehicle. Force can be generated.
When the operation command includes the brake command, the chopper control unit 17 switches the switching element SW2 on and off so that the second resistor BR consumes the DC power output by the power conversion unit 11. Specifically, the chopper control unit 17 adjusts the flow rate of the switching element SW2 according to the value of the voltage between the terminals of the filter capacitor FC1 acquired from the voltage measurement unit 14, and the voltage between the terminals of the filter capacitor FC1. Keep the value of in the specified range. The defined range is a value in a range lower than the maximum voltage that can supply power to the overhead wire 53 and can be applied to the filter capacitor FC1.

Specifically, when power cannot be supplied to the overhead wire 53 and the voltage between the terminals of the filter capacitor FC1 rises, the chopper control unit 17 increases the flow rate of the switching element SW2. As a result, the electric power supplied from the electric motor 51 is consumed by the second resistance BR, and the braking force of the electric railway vehicle is obtained.

Next, the operation of the power conversion device 1 when the electric railway vehicle is stopped will be described. When the electric railway vehicle is stopped, the high-speed circuit breaker 54 and the contactor MC1 are opened after the power conversion unit 11 is stopped. As a result, the power conversion unit 11 is electrically disconnected from the current collector 52.

When the maintenance work of the power conversion device 1 is performed after the electric railway vehicle is stopped, the discharge switch SW1 is turned on by the maintenance worker mechanically operating the discharge switch SW1. When the discharge switch SW1 is turned on while the contactors MC1 and MC2 are open, the first resistor CHR and the second resistor BR are connected in series. Further, the filter capacitor FC1 is electrically connected to the first resistance CHR and the second resistance BR connected in series, and is discharged by the first resistance CHR and the second resistance BR.

As described above, according to the power conversion device 1 according to the first embodiment, the first resistor CHR provided for suppressing the discharge of the filter capacitor FC1 and the inrush current at the time of charging the filter capacitor FC1 is used. This is performed by the second resistance BR provided to consume the electric power supplied from the electric motor 51 when the electric railway vehicle is braked. Therefore, in addition to the first resistor CHR and the second resistor BR, it is not necessary to newly provide a resistor for discharging the filter capacitor FC1. Therefore, the structure of the power conversion device 1 capable of braking the electric railway vehicle by the dynamic braking method becomes simple. Further, the power conversion device 1 can be miniaturized.

The power conversion device 1 discharges the filter capacitor FC1 after connecting the first resistor CHR and the second resistor BR in series. Therefore, the resistance value of the discharge circuit of the filter capacitor FC1 is the sum of the resistance value of the first resistance CHR and the resistance value of the second resistance BR.

Further, according to the power conversion device 1 according to the first embodiment, even if the discharge switch SW1 fails due to a short circuit, the ground fault current is reduced because the second resistance BR is connected to the other end of the discharge switch SW1. NS.

The discharge current flowing when the filter capacitor FC1 is discharged is inversely proportional to the sum of the resistance value of the first resistance CHR and the resistance value of the second resistance BR. The first resistance CHR has a resistance value high enough to suppress the inrush current when the contactor MC2 is turned on, for example, several tens of Ω. Therefore, the discharge current becomes sufficiently small, a switch having a small current capacity can be used as the discharge switch SW1, and the wiring of the circuit through which the discharge current flows can be thinned. In other words, it is possible to relax the electrical restrictions of the circuit through which the current flows when the filter capacitor FC1 is discharged.

(Embodiment 2)
If the discharge switch SW1 fails due to a short circuit, a ground fault current flows from the current collector 52 to the second resistor BR via the discharge switch SW1. Therefore, the power conversion device 2 capable of determining the presence or absence of a short-circuit failure of the discharge switch SW1 based on the current flowing through the second resistor BR will be described in the second embodiment. The method of mounting the power conversion device 2 on the electric railway vehicle is the same as that of the first embodiment. The difference between the power conversion device 2 and the power conversion device 1 according to the first embodiment will be described below.

In addition to the configuration of the power conversion device 1 according to the first embodiment, the power conversion device 2 according to the second embodiment shown in FIG. 3 includes a current measuring unit 18 for measuring the value of the current flowing through the second resistance BR and a current. Further, a failure determination unit 19 for determining the presence or absence of a short-circuit failure of the discharge switch SW1 based on the measured value of the measurement unit 18 is provided.

The contactor control unit 15 supplies the contactor status signal S4 indicating whether or not at least one of the contactors MC1 and MC2 is turned on to the failure determination unit 19. For example, the contactor control unit 15 has a contactor state signal that becomes a Low level when both the contactors MC1 and MC2 are open, and becomes a High level when at least one of the contactors MC1 and MC2 is turned on. Output S4.
Further, the contactor control unit 15 opens both the contactors MC1 and MC2 when the failure determination unit 19 determines that a short-circuit failure of the discharge switch SW1 has occurred, as will be described later.

The switching control unit 16 turns off the switching element of the power conversion unit 11 when the failure determination unit 19 determines that a short-circuit failure of the discharge switch SW1 has occurred, as will be described later.

The chopper control unit 17 supplies the element state signal S5 indicating which state the switching element SW2 is on / off to the failure determination unit 19. For example, the chopper control unit 17 outputs an element state signal S5 which becomes a high level when the switching element SW2 is on and becomes a low level when the switching element SW2 is off.

The current measuring unit 18 is provided between the switching element SW2 and the second resistor BR. Specifically, one end of the current measuring unit 18 is connected to the emitter terminal of the switching element SW2, and the other end is connected to one end of the second resistor BR. Further, the other end of the discharge switch SW1 is connected to the connection point between the current measuring unit 18 and the switching element SW2. The current measuring unit 18 provided at the above-mentioned position is a CT (Current Transformer) and measures the value of the current flowing through the second resistor BR. Then, the current measuring unit 18 supplies a signal indicating the measured value of the current to the failure determining unit 19.

In the failure determination unit 19, when the discharge switch SW1 is off and the switching element SW2 of the chopper circuit 13 is off, the current value IB, which is the measured value of the current acquired from the current measurement unit 18, is equal to or higher than the threshold current Th. It is determined whether or not it is. If the discharge switch SW1 is off, the switching element SW2 of the chopper circuit 13 is off, and the current value IB is the threshold current Th or more, it can be considered that the discharge switch SW1 has a short-circuit failure. ..

The threshold current Th can be determined according to the value obtained by dividing the overhead wire voltage, which is the voltage of the overhead wire 53, by the sum of the resistance value of the first resistance CHR and the resistance value of the second resistance BR. Specifically, it is preferable that the threshold current Th is the value obtained by dividing the minimum value that the overhead wire voltage can take by the total of the resistance value of the first resistance CHR and the resistance value of the second resistance BR.

Further, the failure determination unit 19 outputs a determination result signal S6 based on the determination result of whether or not the current value IB is equal to or higher than the threshold current Th to the contactor control unit 15 and the switching control unit 16. Specifically, when the failure determination unit 19 determines that the current value IB is less than the threshold current Th, the failure determination unit 19 switches the determination result signal S6 indicating that a short-circuit failure of the discharge switch SW1 has not occurred with the contactor control unit 15. Output to the control unit 16. Further, when the failure determination unit 19 determines that the current value IB is equal to or higher than the threshold current Th, the failure determination unit 19 outputs the determination result signal S6 indicating that a short-circuit failure of the discharge switch SW1 has occurred between the contactor control unit 15 and the switching control unit 16. Output to. For example, the failure determination unit 19 outputs a determination result signal S6 which becomes the Low level when it is determined that the current value IB is less than the threshold current and becomes the High level when it is determined that the current value IB is equal to or more than the threshold current. do.

The process of determining the presence or absence of a short-circuit failure performed by the failure determination unit 19 will be described with reference to FIG. As described in the first embodiment, the maintenance worker turns on the discharge switch SW1 in a state where the high-speed circuit breaker 54 and the contactors MC1 and MC2 are open. In other words, in a state where at least one of the contactors MC1 and MC2 is turned on, if the discharge switch SW1 is normal, the discharge switch SW1 is off. Therefore, the failure determination unit 19 determines whether or not the discharge switch SW1 is turned off based on the contactor state signal S4.

Specifically, the failure determination unit 19 determines whether or not at least one of the contactors MC1 and MC2 is in the ON state based on the contactor status signal S4 (step S11). When both the contactors MC1 and MC2 are in the off state (step S11; No), the failure determination unit 19 ends the process of determining the presence or absence of a short-circuit failure.

When any of the contactors MC1 and MC2 is in the ON state (step S11; Yes), the failure determination unit 19 determines whether or not the switching element SW2 of the chopper circuit 13 is in the OFF state (step S12). ). Specifically, the failure determination unit 19 determines whether or not the element state signal S5 indicates that the switching element SW2 is off. When the switching element SW2 is in the ON state (step S12; No), the failure determination unit 19 ends the process of determining the presence or absence of a short-circuit failure.

When the switching element SW2 is in the off state (step S12; Yes), the failure determination unit 19 acquires the current value IB from the current measurement unit 18 (step S13). The failure determination unit 19 determines whether or not the current value IB is equal to or greater than the threshold current Th (step S14). If the current value IB is less than the threshold current Th, it can be considered that the short-circuit failure of the discharge switch SW1 has not occurred. Therefore, when the current value IB is less than the threshold current Th (step S14; No), the failure determination unit 19 outputs a determination result signal S6 indicating that a short-circuit failure of the discharge switch SW1 has not occurred (step S15). .. When the process of step S15 is completed, the failure determination unit 19 ends the process of determining the presence or absence of a short-circuit failure.

If the current value IB is equal to or higher than the threshold current Th, it can be considered that a short-circuit failure of the discharge switch SW1 has occurred. Therefore, when the current value IB is equal to or greater than the threshold current Th (step S14; Yes), the failure determination unit 19 outputs a determination result signal S6 indicating that a short-circuit failure of the discharge switch SW1 has occurred (step S16). .. When the process of step S16 is completed, the failure determination unit 19 ends the process of determining the presence or absence of a short-circuit failure.

The failure determination unit 19 repeats the above-mentioned process at a predetermined timing. For example, the failure determination unit 19 may repeat the above-mentioned processing at regular intervals.

The contactor control unit 15 that has acquired the determination result signal S6 indicating that the discharge switch SW1 has a short-circuit failure outputs the contactor control signal S1 instructing to open both the contactors MC1 and MC2.
Further, the switching control unit 16 that has acquired the determination result signal S6 indicating that the discharge switch SW1 has a short-circuit failure outputs a switching control signal S2 instructing that the switching element of the power conversion unit 11 is turned off. ..

As described above, according to the power conversion device 2 according to the second embodiment, it is possible to determine the presence or absence of a short-circuit failure of the discharge switch SW1 based on the current flowing through the second resistor BR.

The above circuit configuration is an example. An example of another circuit configuration is shown in FIG. As shown in FIG. 5, the circuit switching unit 12a included in the power conversion device 3 may include contactors MC1 and MC2 connected in series and a first resistor CHR connected in parallel to the contactor MC2. good. One end of the contactor MC1 is connected to the high speed circuit breaker 54. One end of the contactor MC2 is connected to the other end of the contactor MC1, and the other end is connected to the primary terminal 11a of the power conversion unit 11. One end of the first resistor CHR is connected to the connection point of the contactors MC1 and MC2, and the other end is connected to the other end of the contactor MC2. One end of the discharge switch SW1 is connected to the connection point of the contactors MC1 and MC2, and the other end is connected to the connection point of the switching element SW2 of the chopper circuit 13 and the second resistor BR. The circuit switching unit 12 included in the power conversion device 2 may have the same configuration as the circuit switching unit 12a included in the power conversion device 3.

The contactor control unit 15 included in the power conversion device 3 outputs the contactor control signal S1 instructing the contactor MC1 to be turned on when the opening / closing instruction signal instructing the start is supplied. As a result, the contactor MC1 is turned on, and the electric power acquired from the substation by the current collector 52 via the overhead wire 53 is transferred to the filter capacitor FC1 via the high-speed circuit breaker 54, the contactor MC1, and the first resistor CHR. It is supplied and charging of the filter capacitor FC1 is started.

After that, when the filter capacitor FC1 is sufficiently charged, the contactor control unit 15 included in the power conversion device 3 outputs a contactor control signal S1 instructing the contactor MC2 to be turned on. As a result, the contactor MC2 is turned on, and the electric power acquired from the substation by the current collector 52 via the overhead wire 53 is supplied to the filter capacitor FC1 via the high-speed circuit breaker 54 and the contactors MC1 and MC2.

FIG. 6 shows an example of yet another circuit configuration. The power conversion device 4 shown in FIG. 6 includes a filter reactor FL1 in addition to the configuration of the power conversion device 1. The filter reactor FL1 is provided in the circuit between the circuit switching unit 12 and the chopper circuit 13. Specifically, one end of the filter reactor FL1 is connected to the other end of the contactor MC1, and the other end is connected to the primary terminal 11a of the power conversion unit 11. By providing the filter reactor FL1, it is possible to smooth the input current of the power conversion unit 11 and the output current of the power conversion unit 11 at the time of regenerative braking. Further, by providing the filter reactor FL1, it is possible to suppress the inrush current from flowing through the first resistor CHR and the second resistor BR at the start of discharging the filter capacitor FC1. The filter reactor FL1 may be provided in the

power conversion devices

2 and 3.

The method for determining the presence or absence of a short-circuit failure of the discharge switch SW1 is not limited to the above example. As an example, the order in which the processes of steps S11 and S12 in FIG. 4 are executed is arbitrary, and the failure determination unit 19 may perform the process of step S12 and then the process of step S11.

Further, the discharge switch SW1 is provided with a function of outputting a signal indicating which of the on / off states it is, and the failure determination unit 19 is in a state where the discharge switch SW1 is off based on the signal acquired from the discharge switch SW1. It may be determined whether or not there is.

Further, the failure determination unit 19 acquires the current value IB from the current measurement unit 18 at regular intervals and stores it in the memory, reads the current value IB from the memory in step S13 of FIG. 4, and is based on the read current value IB. Then, the processing of the subsequent step S14 may be performed.

Further, the failure determination unit 19 has a timer, the discharge switch SW1 is off, the switching element SW2 of the chopper circuit 13 is off, and the current value IB is defined to be equal to or higher than the threshold current Th. It may be determined whether or not it continues for only the time. In this case, when the failure determination unit 19 determines that the state in which the current value IB is equal to or higher than the threshold current Th has not continued for a predetermined time, the determination result indicating that a short-circuit failure of the discharge switch SW1 has not occurred. The signal S6 may be output to the contactor control unit 15 and the switching control unit 16.
Further, when the failure determination unit 19 determines that the state in which the current value IB is equal to or higher than the threshold current Th continues for a predetermined time, the determination result signal S6 indicating that a short-circuit failure of the discharge switch SW1 has occurred. May be output to the contactor control unit 15 and the switching control unit 16. The defined time may be a time that can prevent the failure determination unit 19 from outputting an erroneous determination result due to a momentary fluctuation of the current value IB. For example, the defined time may be set to be longer than the update cycle of the on / off state of each element such as the discharge switch SW1 and the switching element SW2, and longer than the sampling cycle of the current value IB.

Further, the failure determination unit 19 may output the determination result signal S6 to a display device provided in the driver's cab. In this case, the presence or absence of a short-circuit failure of the discharge switch SW1 can be displayed on the driver's cab.

The motor 51 is not limited to the three-phase induction motor. As an example, the electric motor 51 may be a synchronous motor, a DC motor, or the like.

The power conversion unit 11 is an arbitrary power conversion circuit capable of bidirectional power conversion. As an example, when the electric motor 51 is a direct current electric motor, the power conversion unit 11 may be a DC (Direct Current) -DC converter.

The power conversion device 1-4 can be mounted on any vehicle, any device, etc. that can supply DC power to the power conversion device 1-4. As an example, the power conversion device 1-4 can be mounted on an AC feeder type electric railway vehicle. In this case, one of the primary terminals of the transformer may be connected to the other end of the high-speed circuit breaker 54, the converter may be connected to the secondary terminal of the transformer, and the output of the converter may be supplied to the power converters 1-4.

As another example, the power conversion device 1-4 may be mounted on an electric railway vehicle that acquires electric power via the third rail.

Further, the power conversion device 1-4 is not limited to a device that enables braking of an electric railroad vehicle by a dynamic braking method, and is an arbitrary power conversion device having a plurality of resistors. As an example, the power converter 1-4 may discharge the filter capacitor FC1 using a resistor provided for any application instead of the first resistor CHR and the second resistor BR. As a result, it is not necessary to newly provide a resistor for discharging the filter capacitor FC1, and the structure of the power conversion device 1-4 can be simplified.

The present disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of the present disclosure. Moreover, the above-described embodiment is for explaining this disclosure, and does not limit the scope of the present disclosure. That is, the scope of the present disclosure is indicated by the scope of claims, not by the embodiment. Then, various modifications made within the scope of the claims and within the scope of the equivalent disclosure are considered to be within the scope of this disclosure.

1,2,3,4 Power converter, 1a Positive input terminal, 1b Negative input terminal, 11 Power conversion unit, 11a, 11b Primary terminal, 12,12a Circuit switching unit, 13 Chopper circuit, 14 Voltage measuring unit, 15 Contact Instrument control unit, 16 switching control unit, 17 chopper control unit, 18 current measurement unit, 19 failure determination unit, 51 motor, 52 current collector, 53 overhead wire, 54 high-speed breaker, BR 2nd resistance, CHR 1st resistance, FC1 filter capacitor, FL1 filter reactor, MC1, MC2 contactor, S1 contactor control signal, S2 switching control signal, S3 chopper control signal, S4 contactor state signal, S5 element state signal, S6 discrimination result signal, SW1 discharge switch, SW2 switching element.

Claims

A filter capacitor that is charged with DC power supplied from the power supply,
The filter capacitor is connected between the primary terminals, and the DC power supplied from the power supply via the filter capacitor is converted into DC power or AC power and supplied to the motor connected to the secondary terminal to generate power. A power conversion unit that converts DC power or AC power supplied from the motor that operates as a machine into DC power and outputs it to charge the filter capacitor.
A circuit switching unit having a first resistor and electrically connecting the power conversion unit and the filter capacitor to the power supply or electrically disconnecting the filter capacitor from the power supply.
A chopper circuit having a switching element and a second resistor connected in series, both ends of which are connected between the primary terminals of the power converter.
One end is connected to one end of the first resistor close to the power supply, and the other end is a discharge switch connected to a connection point between the switching element and the second resistor.
When charging the filter capacitor with DC power supplied from the power supply, the circuit switching unit electrically connects the power conversion unit and the filter capacitor to the power supply via an electric path passing through the first resistor. connection,
In the chopper circuit, when the switching element is turned on, the DC power supplied from the power conversion unit via the filter capacitor is consumed by the second resistor.
When the discharge switch is turned on, the first resistor and the second resistor are connected in series, and the filter capacitor is electrically connected to the first resistor and the second resistor connected in series. Discharge the filter capacitor,
Power converter.
The circuit switching unit is
A first contactor, one end of which is connected to the power supply and located in parallel with the first resistor.
It has a second contactor, one end of which is connected to the power supply and the other end of which is connected to one end of the first resistor.
The other end of the first resistor is connected to the pair of primary terminals of the power conversion unit.
One end of the discharge switch is connected to one end of the first resistor.
The other end of the discharge switch is connected to a connection point between the switching element of the chopper circuit and the second resistor.
The power conversion device according to claim 1.
The circuit switching unit has a first contactor and a second contactor connected in series.
One end of the first contactor is connected to the power supply and
The other end of the first contactor is connected to one end of the second contactor.
The other end of the second contactor is connected to the primary terminal of the power conversion unit.
One end of the first resistor is connected to a connection point between the first contactor and the second contactor.
The other end of the first resistor is connected to the other end of the second contactor.
One end of the discharge switch is connected to the one end of the first resistor.
The other end of the discharge switch is connected to a connection point between the switching element of the chopper circuit and the second resistor.
The power conversion device according to claim 1.
A failure determination unit for determining the presence or absence of a short-circuit failure of the discharge switch based on the current flowing through the second resistor is further provided.
The power conversion device according to any one of claims 1 to 3.
The failure determination unit determines whether or not the current flowing through the second resistor is equal to or greater than the threshold current when the discharge switch is open and the switching element of the chopper circuit is off. To output,
The power conversion device according to claim 4.
The circuit switching unit electrically disconnects the power conversion unit from the power supply when the failure determination unit determines that the discharge switch has a short-circuit failure.
The power conversion device according to claim 4 or 5.
By switching the switching element of the power conversion unit on and off, the power conversion unit converts the DC power supplied from the power supply via the filter capacitor into DC power or AC power, or from the electric power unit. Further equipped with a switching control unit that converts the supplied DC power or AC power into DC power,
The switching control unit turns off the switching element of the power conversion unit when the failure determination unit determines that the discharge switch has a short-circuit failure.
The power conversion device according to any one of claims 4 to 6.