JPWO2020105080A1 - Power converter and disconnection detection method - Google Patents

Abstract

The power conversion device (1) includes a plurality of filter capacitors (FC1, FC2), a plurality of power conversion units (11, 12), and a common discharge circuit (15) for discharging a plurality of filter capacitors (FC1, FC2). , A plurality of power conversion units (11, 12) based on a determination unit (17) for determining whether or not they are electrically disconnected from the power supply, and a plurality of filter capacitors (FC1, FC2). A disconnection detection unit (18) for determining the presence or absence of disconnection of the circuit from each of the filter capacitors (FC1 and FC2) to the common discharge circuit (15) is provided.

Description

The present invention relates to a power converter and a disconnection detection method.

Some electric railway vehicles are equipped with a power conversion device that converts the electric power supplied from the substation through the overhead wire into desired AC electric power and supplies the converted electric power to the motor. An example of this type of power conversion device is disclosed in Patent Document 1. In this power conversion device, a plurality of filter capacitors and a filter capacitor are connected to each primary terminal, and the DC voltage applied to the filter capacitor is converted into a desired AC voltage to form an electric motor connected to the secondary terminal. A plurality of power conversion units to be supplied and a discharge circuit common to a plurality of filter capacitors for discharging the plurality of filter capacitors are provided.

Japanese Unexamined Patent Publication No. 2001-145208

The power conversion device disclosed in Patent Document 1 further includes a plurality of diodes for preventing backflow. The anode of each diode is connected to the corresponding filter capacitor and the cathode is commonly connected to the discharge circuit. A plurality of filter capacitors of a power converter mounted on an electric railway vehicle are charged to a high voltage. Therefore, in the maintenance work of the power conversion device, the maintenance work is performed after operating the discharge switch to operate the discharge circuit and discharging the plurality of filter capacitors. If a part of the plurality of diodes included in the power conversion device is open-failed, the filter capacitor connected to the open-failed diode is not discharged even if the discharge circuit operates. Since this power converter does not have a function of determining the presence or absence of an open diode open failure, the presence of an undischarged filter capacitor is not notified to the maintenance worker. Therefore, there arises a problem that the worker cannot safely perform the maintenance work.

The present invention has been made in view of the above circumstances, and an object of the present invention is to determine the presence or absence of disconnection of a circuit from each of a plurality of filter capacitors to a common discharge circuit.

In order to achieve the above object, the power conversion device of the present invention includes a plurality of power conversion units, a plurality of filter capacitors, at least one contactor, a common discharge circuit common to the plurality of filter capacitors, and a determination unit. And a disconnection detection unit. Each of the plurality of power converters converts the DC power supplied from the power supply via the primary terminal into DC power or AC power and supplies the DC power to the load connected to the secondary terminal. Each of the plurality of filter capacitors is connected between the primary terminals of one corresponding power converter. At least one contactor electrically connects or disconnects at least one power converter from the power source. The common discharge circuit is connected to a plurality of filter capacitors and discharges the plurality of filter capacitors. The determination unit determines whether or not the plurality of power conversion units are electrically disconnected from the power supply. When the determination unit determines that the plurality of power conversion units are electrically disconnected from the power supply, the disconnection detection unit converts each of the plurality of filter capacitors into a common discharge circuit based on the voltages of the plurality of filter capacitors. Determine if there is a break in the circuit leading up to it.

According to the present invention, it is possible to determine the presence or absence of disconnection of the circuit from each of the plurality of filter capacitors to the common discharge circuit based on the voltages of the plurality of filter capacitors.

Block diagram of the power conversion device according to the first embodiment of the present invention The figure which shows the example of mounting on the railroad vehicle of the power conversion apparatus which concerns on Embodiment 1. Flow chart of operation for determining the presence or absence of disconnection performed by the power conversion device according to the first embodiment Block diagram of the power conversion device according to the second embodiment of the present invention Flow chart of operation for determining the presence or absence of disconnection performed by the power conversion device according to the second embodiment A flowchart of an operation for determining the presence or absence of disconnection performed by the power conversion device according to the embodiment of the present invention. The figure which shows the example of mounting on the railroad vehicle of the power conversion apparatus which concerns on embodiment of this invention.

Hereinafter, the power conversion device according to the embodiment of the present invention 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 electric railway vehicle is equipped with a power conversion device that converts DC power supplied from a substation through an overhead wire into AC power and supplies the AC power to an electric motor. The power conversion device 1 according to the first embodiment shown in FIG. 1 converts the supplied DC power into AC power for driving the motors 51 and 52, and supplies the AC power to the motors 51 and 52. FIG. 2 shows an example of mounting the power conversion device 1 on an electric railway vehicle. Note that FIG. 2 is an example of a DC feeder system. The current collector 4 acquires DC power from the substation via the overhead wire 3 and supplies the power to the power conversion device 1 via the high-speed circuit breaker 5. The current collector 4 corresponds to a power source that supplies electric power to the electric power converter 1. The high-speed circuit breaker 5 is controlled by a circuit breaker control unit (not shown) to electrically connect the current collector 4 and the power converter 1 or electrically cut off the power converter 1 from the current collector 4. The motors 51 and 52 are composed of, for example, a three-phase induction motor. When the electric power converter 1 supplies electric power to the electric motors 51 and 52, the electric motors 51 and 52 are driven to obtain the propulsive force of the electric railway vehicle.

As shown in FIG. 2, the power conversion device 1 includes a positive electrode input terminal 1a connected to the high-speed circuit breaker 5 and a negative electrode input terminal 1b to be grounded. Further, the power conversion device 1 includes contactors MC1 and MC2 having one end connected to the positive electrode input terminal 1a, filter reactor FL1 having one end connected to the other end of the contactor MC1, and one end to the other end of the contactor MC2. The connected filter reactor FL2, the filter capacitor FC1 having one end connected to the other end of the filter reactor FL1 and the other end connected to the negative electrode input terminal 1b, and one end connected to the other end of the filter reactor FL2, the other end. Is provided with a filter capacitor FC2 connected to the negative electrode input terminal 1b.

In the power conversion device 1, a filter capacitor FC1 is further connected between the primary terminals, a power conversion unit 11 in which each secondary terminal is connected to the electric motor 51, and a filter capacitor FC2 are connected between the primary terminals, and each secondary terminal is connected. Is provided with a power conversion unit 12 connected to the electric motor 52 and a common discharge circuit 15 for discharging the filter capacitors FC1 and FC2. The power converter 1 further includes a diode D1 in which the anode is connected to the connection point between the other end of the contactor MC1 and one end of the filter reactor FL1 and the cathode is connected to the common discharge circuit 15, and the anode is the contactor MC2. A diode D2 connected to the connection point between the end and one end of the filter reactor FL2 and having a cathode connected to the common discharge circuit 15, a voltage measuring unit 13 connected in parallel to the filter capacitor FC1 and parallel to the filter capacitor FC2. It includes a connected voltage measuring unit 14.

The power conversion device 1 further determines whether or not the switching control unit 16 that controls the power conversion units 11 and 12 and the power conversion units 11 and 12 are electrically separated from the current collector 4. 17 and a disconnection detection unit 18 for determining the presence or absence of disconnection of the circuit from the filter capacitors FC1 and FC2 to the common discharge circuit 15.

The contactors MC1 and MC2 are turned on or off by a contactor control unit (not shown).
When the contactor MC1 is turned on, the high-speed circuit breaker 5 and the filter reactor FL1 are electrically connected. When the high-speed circuit breaker 5 and the contactor MC1 are turned on, the power conversion unit 11 is electrically connected to the current collector 4. When the contactor MC2 is turned on, the high-speed circuit breaker 5 and the filter reactor FL2 are electrically connected. When the high-speed circuit breaker 5 and the contactor MC2 are turned on, the power conversion unit 12 is electrically connected to the current collector 4. With the high-speed circuit breaker 5 and the contactors MC1 and MC2 turned on, the filter reactors FL1 and FL2 reduce the harmonic components. Further, a DC voltage is applied to the filter capacitors FC1 and FC2.
When the contactor MC1 is opened, the high-speed circuit breaker 5 and the filter reactor FL1 are electrically disconnected. As a result, the power conversion unit 11 is electrically disconnected from the current collector 4. When the contactor MC2 is opened, it electrically disconnects the high-speed circuit breaker 5 and the filter reactor FL2. As a result, the power conversion unit 12 is electrically disconnected from the current collector 4.

The power conversion unit 11 converts the DC power supplied via the primary terminal into three-phase AC power, and supplies the three-phase AC power to the motor 51 to which each secondary terminal is connected. The power conversion unit 12 converts the DC power supplied via the primary terminal into three-phase AC power, and supplies the three-phase AC power to the motor 52 to which each secondary terminal is connected. The power conversion units 11 and 12 are composed of, for example, a VVVF (Variable Voltage Variable Frequency) inverter.

The common discharge circuit 15 is a discharge circuit common to the filter capacitors FC1 and FC2, and has a resistor R1 and a switch SW1 connected in series. The switch SW1 is composed of, for example, a knife switch for discharging. When the worker mechanically operates the switch SW1 which is a knife switch for discharging, the switch SW1 is turned on or off. When the switch SW1 is turned on while the power conversion units 11 and 12 are electrically disconnected from the current collector 4, the common discharge circuit 15 discharges the filter capacitors FC1 and FC2.

The diode D1 prevents a current from flowing back from the common discharge circuit 15 to the filter capacitor FC1 when the switch SW1 is on. The diode D2 prevents the current from flowing back from the common discharge circuit 15 to the filter capacitor FC2 when the switch SW1 is on.
The voltage measuring unit 13 measures the value of the voltage between the terminals of the filter capacitor FC1 and supplies a signal indicating the measured voltage value to the switching control unit 16 and the determination unit 17. The voltage measuring unit 14 measures the value of the voltage between the terminals of the filter capacitor FC2, and supplies a signal indicating the measured voltage value to the switching control unit 16 and the determination unit 17.

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 S1 to the switching elements of the power conversion units 11 and 12 in response to an operation command to control the switching elements.

The determination unit 17 determines whether or not the power conversion units 11 and 12 are electrically disconnected from the current collector 4. Specifically, the determination unit 17 acquires the contactor control signal supplied by the contactor control unit to the contactors MC1 and MC2, and based on the contactor control signal, whether or not the contactors MC1 and MC2 are open. To judge. The determination unit 17 notifies the disconnection detection unit 18 whether or not the contactors MC1 and MC2 are open. For example, the determination unit 17 outputs a determination signal S2 which becomes a high level when the contactors MC1 and MC2 are open and becomes a low level when at least one of the contactors MC1 and MC2 is turned on. Output to 18.

The disconnection detection unit 18 acquires the voltage EFC1 which is the value of the inter-terminal voltage of the filter capacitor FC1 from the voltage measuring unit 13, and acquires the voltage EFC2 which is the value of the inter-terminal voltage of the filter capacitor FC2 from the voltage measuring unit 14. Based on the voltages EFC1 and EFC2, it is determined whether or not the circuit from one end of each of the filter capacitors FC1 and FC2 to the common discharge circuit 15 is broken. As an example of this disconnection, there is an open failure of the diodes D1 and D2. For example, if an open failure of the diode D1 occurs, even if the switch SW1 of the common discharge circuit 15 is turned on, the filter capacitor FC1 is not discharged and only the filter capacitor FC2 is discharged, so that the voltage EFC1 can be regarded as constant. However, the voltage EFC2 decreases. In other words, if only one of the voltages EFC1 and EFC2 decreases during the discharge of the filter capacitors FC1 and FC2 by the common discharge circuit 15, the filter capacitors FC1 and FC2 reach the common discharge circuit 15. It can be considered that the circuit of the above has failed.

Therefore, the disconnection detection unit 18 determines whether or not the circuit is disconnected based on the voltages EFC1 and EFC2 while the common discharge circuit 15 is discharging the filter capacitors FC1 and FC2. Specifically, in the disconnection detection unit 18, when the high level determination signal S2 is supplied from the determination unit 17, one of the voltages EFC1 and EFC2 is larger than the first reference voltage Th1 and the other of the voltages EFC1 and EFC2. Is lower than the first reference voltage Th1 and is equal to or less than the second reference voltage Th2, and the determination result is output.

Specifically, the disconnection detection unit 18 detects disconnection having an amplitude corresponding to the filter capacitor FC1 when the voltage EFC1 is larger than the first reference voltage Th1 and the voltage EFC2 is equal to or less than the second reference voltage Th2. The signal S3 is output as a determination result to a display device provided in the driver's cab. Further, the disconnection detection unit 18 transmits the disconnection detection signal S3 having an amplitude corresponding to the filter capacitor FC2 when the voltage EFC1 is equal to or less than the second reference voltage Th2 and the voltage EFC2 is larger than the first reference voltage Th1. Output to the display device as the judgment result. When the disconnection detection unit 18 determines that the voltage EFC1 and the voltage EFC2 are larger than the first reference voltage Th1, or the voltage EFC1 and the voltage EFC2 are equal to or less than the second reference voltage Th2, the filter capacitors FC1 and FC2 are respectively. The disconnection detection signal S3 having an amplitude lower than the amplitude corresponding to is output to the display device as a determination result.

Based on the amplitude of the disconnection detection signal S3, the display device is in a state where the circuit from each of the filter capacitors FC1 and FC2 to the common discharge circuit 15 is not disconnected, and from the filter capacitor FC1 to the common discharge circuit 15. It is possible to determine whether the circuit of the above circuit is disconnected or the circuit from the filter capacitor FC2 to the common discharge circuit 15 is disconnected.

The determination unit 17 holds the first reference voltage Th1 and the second reference voltage Th2 in advance. The first reference voltage Th1 and the second reference voltage Th2 are determined according to the value of the voltage between the terminals of the filter capacitors FC1 and FC2 in the state where the filter capacitors FC1 and FC2 are charged. For example, the first reference voltage Th1 is a value of 2/3 of the voltage value between terminals when the filter capacitors FC1 and FC2 are fully charged, and the second reference voltage Th2 is a value when the filter capacitors FC1 and FC2 are fully charged. It is a value of 1/3 of the voltage value between terminals.

Next, the operation of the power conversion device 1 having the above configuration will be described.
At the start of operation of the electric railway vehicle, an ascending switch for raising the pantograph, which is an example of the current collector 4, is operated, and when the current collector 4 comes into contact with the overhead wire 3, the current collector 4 receives electric power from the substation. Receive the supply of. Then, after the high-speed circuit breaker 5 is turned on, the contactors MC1 and MC2 are turned on. As a result, power is supplied to the power conversion device 1.

When operating an electric railway vehicle, an operation command from a cab (not shown) is input to the switching control unit 16. When the operation command includes a power running command, that is, when the electric railway vehicle is running, the switching control unit 16 uses the power conversion units 11 and 12 to convert DC power into three-phase AC power for driving the motors 51 and 52, respectively. The switching elements of the power conversion units 11 and 12 are controlled so as to convert. The switching control unit 16 calculates a target torque for obtaining the target acceleration indicated by the power running command. Further, the switching control unit 16 measures the value of the current flowing through the motors 51 and 52 from a current measuring unit (not shown), and calculates the actual torque of the motors 51 and 52 from the measured current value. Specifically, the switching control unit 16 acquires the value of the phase current flowing through the motors 51 and 52 from the current measuring unit that measures the values of the U-phase, V-phase, and W-phase currents flowing through the motors 51 and 52. The actual torque of the motors 51 and 52 is calculated from the value of the phase current. Then, the switching control unit 16 sends a switching control signal S1 to the switching elements of the power conversion units 11 and 12 to control the switching elements in order to bring the actual torques of the motors 51 and 52 closer to the target torque. By charging the filter capacitors FC1 and FC2 connected between the primary terminals of the power conversion units 11 and 12, the noise generated by the power conversion units 11 and 12 is reduced.

When performing maintenance work on the power conversion device 1, the high-speed circuit breaker 5 and the contactors MC1 and MC2 are opened after the power conversion units 11 and 12 are stopped. As a result, the power conversion units 11 and 12 are electrically disconnected from the current collector 4. Then, before performing the maintenance work, the maintenance worker mechanically operates the switch SW1 which is a knife switch for discharging, so that the switch SW1 is turned on. When the switch SW1 is turned on while the contactors MC1 and MC2 are open, the filter capacitors FC1 and FC2 are discharged.

If the circuit from each of the filter capacitors FC1 and FC2 to the common discharge circuit 15 is disconnected, the filter capacitors FC1 and FC2 will not be discharged even if the switch SW1 is turned on, so maintenance work can be performed safely. Can't. Therefore, the power conversion device 1 is a circuit from each of the filter capacitors FC1 and FC2 to the common discharge circuit 15 when a contactor control signal indicating that the contactor MC1 and the contactor MC2 are open is supplied. Starts the process of determining the presence or absence of disconnection. The process of determining the presence or absence of disconnection performed by the power conversion device 1 will be described with reference to FIG.

The determination unit 17 determines whether or not the contactor MC1 and the contactor MC2 are open (step S11). Then, the determination unit 17 outputs a determination signal S2 indicating the determination result to the disconnection detection unit 18. If the determination unit 17 determines that at least one of the contactors MC1 and MC2 is not open (step S11; No), the process of step S11 is repeated. At this time, since the determination unit 17 supplies the low level determination signal S2 to the disconnection detection unit 18, the disconnection detection unit 18 does not perform the processing after step S12 described later.

When the determination unit 17 determines that the contactor MC1 and the contactor MC2 are open (step S11; Yes), the determination unit 17 outputs a high level determination signal S2 to the disconnection detection unit 18, and the disconnection detection unit 18 will be described later. The processing after step S12 of the above is performed. Since the determination unit 17 performs the process of step S11, in a state where the high-speed circuit breaker 5 and the contactors MC1 and MC2 are turned on, for example, the fluctuation and regeneration of the voltages EFC1 and EFC2 caused by the fluctuation of the DC voltage of the overhead wire 3 Even if the voltages EFC1 and EFC2 during operation fluctuate, the processing after step S12 is not performed. Therefore, it is possible to prevent the circuit from being erroneously determined to be broken due to fluctuations in the voltages EFC1 and EFC2.

When the high level determination signal S2 is supplied, the disconnection detection unit 18 acquires the voltages EFC1 and EFC2 from the voltage measurement units 13 and 14, respectively (step S12). The disconnection detection unit 18 compares the voltages EFC1 and EFC2 with the first reference voltage Th1 (step S13).

When the disconnection detection unit 18 determines that the voltage EFC1 is larger than the first reference voltage Th1 and the voltage EFC2 is larger than the first reference voltage Th1 (step S13; Yes), after the contactors MC1 and MC2 are opened. It is determined whether or not the predetermined determination time has elapsed (step S14). Specifically, when the high level determination signal S2 is supplied, the disconnection detection unit 18 starts the timer and determines whether or not the measurement time of the timer has reached the determination time. The determination time is determined by discharging the filter capacitors FC1 and FC2 from a fully charged state with no disconnection in the circuit from each of the filter capacitors FC1 and FC2 to the common discharge circuit 15, and the voltage EFC1 and EFC1. This is the time required for EFC2 to drop to the first reference voltage Th1.

When the disconnection detection unit 18 determines that the determination time has elapsed (step S14; Yes), the disconnection detection unit 18 outputs to the display device that the filter capacitors FC1 and FC2 are not normally discharged. (Step S15), the process of determining the presence or absence of disconnection is completed. When the disconnection detection unit 18 determines that the determination time has not elapsed (step S14; No), the above-mentioned process is repeated from step S11.

When the disconnection detection unit 18 determines that at least one of the voltages EFC1 and EFC2 is equal to or less than the first reference voltage Th1 (step S13; No), one of the voltages EFC1 and EFC2 is larger than the first reference voltage Th1 and , It is determined whether or not the other of the voltages EFC1 and EFC2 is equal to or less than the second reference voltage Th2 (step S16).

When the disconnection detection unit 18 determines that the voltage EFC1 is larger than the first reference voltage Th1 and the voltage EFC2 is equal to or less than the second reference voltage Th2 (step S16; Yes), the disconnection detection unit 18 has an amplitude corresponding to the filter capacitor FC1. The disconnection detection signal S3 is output to the display device (step S17).
Further, when the disconnection detection unit 18 determines that the voltage EFC1 is equal to or less than the second reference voltage Th2 and the voltage EFC2 is larger than the first reference voltage Th1 (step S16; Yes), the disconnection detection unit 18 determines the amplitude corresponding to the filter capacitor FC2. The disconnection detection signal S3 is output to the display device (step S17). When the process of step S17 is completed, the power conversion device 1 ends the process of determining the presence or absence of disconnection.

As described above, according to the power conversion device 1 according to the first embodiment, it is determined whether or not the circuit from each of the filter capacitors FC1 and FC2 to the common discharge circuit 15 is disconnected based on the voltages EFC1 and EFC2. It is possible.

(Embodiment 2)
If the circuit from each of the filter capacitors FC1 and FC2 to the common discharge circuit 15 is disconnected, the common discharge circuit 15 cannot discharge the filter capacitors FC1 and FC2. Therefore, the power conversion device 2 according to the second embodiment prevents the voltages EFC1 and EFC2 from becoming overvoltage when the circuit from the filter capacitors FC1 and FC2 to the common discharge circuit 15 is disconnected. The individual discharge circuits provided for this purpose are operated to discharge each of the filter capacitors FC1 and FC2.

The timing for operating this individual discharge circuit will be described.
In the power conversion device 2, for example, in order to prevent the voltages EFC1 and EFC2 from becoming overvoltage when the outputs of the power conversion units 11 and 12 become abnormal and the power conversion units 11 and 12 are stopped, the filter capacitor FC1 , FC2 is provided with two individual discharge circuits connected to each. The power conversion device 2 discharges the filter capacitors FC1 and FC2 by operating individual discharge circuits when the outputs of the power conversion units 11 and 12 become abnormal.
Further, the power conversion device 2 is used for the electric railway vehicle by regenerative braking of the electric railway vehicle, that is, the electric motors 51 and 52 operate as a generator and supply the electric power generated by the electric motors 51 and 52 to the overhead wire 3. While the regenerative braking force is applied, the individual discharge circuits are operated in order to prevent the voltages EFC1 and EFC2 from becoming too high as compared with the voltage of the overhead wire 3.
Further, by operating this individual discharge circuit even when the circuit from the filter capacitors FC1 and FC2 to the common discharge circuit 15 is disconnected, maintenance work can be performed safely.

The power conversion device 2 according to the second embodiment shown in FIG. 4 has an individual discharge circuit 19 connected in parallel to the filter capacitor FC1 and a filter capacitor FC2 in addition to the configuration of the power conversion device 1 according to the first embodiment. Further, an individual discharge circuit 20 connected in parallel with the individual discharge circuit 20 and a discharge control unit 21 for controlling the operation of the individual discharge circuits 19 and 20 are further provided.

Each part of the power conversion device 2 different from the power conversion device 1 according to the first embodiment will be described.
The individual discharge circuit 19 includes a resistor R2 and a switching element SW2 connected in series. When the switching element SW2 is turned on by the control of the discharge control unit 21, the individual discharge circuit 19 discharges the filter capacitor FC1. The individual discharge circuit 20 includes a resistor R3 and a switching element SW3 connected in series. When the switching element SW3 is turned on by the control of the discharge control unit 21, the individual discharge circuit 20 discharges the filter capacitor FC2. The switching elements SW2 and SW3 are composed of, for example, an IGBT (Insulated Gate Bipolar Transistor).

The discharge control unit 21 turns on the switching elements SW2 and SW3 when the output of the power conversion units 11 and 12 becomes abnormal and the switching control unit 16 stops the power conversion units 11 and 12. Specifically, when the power conversion units 11 and 12 are stopped due to an abnormality in the output of the power conversion units 11 and 12, the switching control unit 16 sends a protection stop signal S4 indicating the stopped power conversion units 11 and 12 to the discharge control unit. Supply to 21. When the protection stop signal S4 indicating the power conversion unit 11 is supplied, the discharge control unit 21 turns on the switching element SW2 included in the individual discharge circuit 19 connected to the power conversion unit 11. Further, when the protection stop signal S4 indicating the power conversion unit 12 is supplied, the discharge control unit 21 turns on the switching element SW3 included in the individual discharge circuit 20 connected to the power conversion unit 12.

Further, the discharge control unit 21 turns on the switching elements SW2 and SW3 when the voltages of the filter capacitors FC1 and FC2 are equal to or higher than the threshold voltage during the regeneration operation of the electric railroad vehicle. Specifically, the discharge control unit 21 acquires an operation command from the driver's cab, acquires the voltage EFC1 from the voltage measuring unit 13, and acquires the voltage EFC2 from the voltage measuring unit 14. Then, the discharge control unit 21 turns on the switching element SW2 when the operation command includes the brake command and the voltage EFC1 is equal to or higher than the threshold voltage. Further, the discharge control unit 21 turns on the switching element SW3 when the operation command includes the brake command and the voltage EFC2 is equal to or higher than the threshold voltage. The threshold voltage is determined according to the DC voltage of the overhead wire 3, is a voltage within a range in which regenerative operation is possible and overvoltage does not occur in the overhead wire 3.

Further, the discharge control unit 21 turns on the switching element SW2 when the disconnection detection signal S3 indicating the filter capacitor FC1 is supplied. As a result, the filter capacitor FC1 is discharged. Further, the discharge control unit 21 turns on the switching element SW3 when the disconnection detection signal S3 indicating the filter capacitor FC2 is supplied. As a result, the filter capacitor FC2 is discharged.

Next, the operation of the power conversion device 2 having the above configuration will be described. The operation of the power conversion device 2 at the start of operation and at the time of braking of the electric railway vehicle is the same as that of the first embodiment.
Similar to the power conversion device 1 according to the first embodiment, the power conversion device 2 receives the contactor control signals indicating that the contactor MC1 and the contactor MC2 are open, and the filter capacitors FC1 and FC2 The process of determining whether or not the circuit from each of the above to the common discharge circuit 15 is broken is started. The process of determining the presence or absence of disconnection performed by the power conversion device 2 will be described with reference to FIG.

The processing of steps S11-S17 is the same as that of steps S11-S17 of FIG. When the process of step S17 is completed, the discharge control unit 21 switches the switching elements SW2 and SW3 on and off according to the disconnection detection signal S3 output by the disconnection detection unit 18, and the individual discharge circuits 19 and 20 switch the filter capacitors FC1 and FC1. FC2 is discharged (step S18). Specifically, when the disconnection detection signal S3 having an amplitude corresponding to the filter capacitor FC1 is supplied, the discharge control unit 21 turns on the switching element SW2 and operates the individual discharge circuit 19 to operate the filter capacitor FC1. Discharge. When the disconnection detection signal S3 having an amplitude corresponding to the filter capacitor FC2 is supplied, the discharge control unit 21 turns on the switching element SW3 and operates the individual discharge circuit 20 to discharge the filter capacitor FC2.

As described above, according to the power conversion device 2 according to the second embodiment, when the common discharge circuit 15 cannot discharge the filter capacitors FC1 and FC2 due to disconnection, the individual discharge circuits 19 and 20 filter the filters. It is possible to discharge the capacitors FC1 and FC2. As a result, it is possible to provide the power conversion device 2 having high safety.

Embodiments of the present invention are not limited to the above examples. For example, the determination unit 17 can determine whether or not each of the contactors MC1 and MC2 is open based on the contact signals output by each of the contactors MC1 and MC2. The contact signal indicates whether or not the contacts of the contactors MC1 and MC2 are conducting.
Further, the determination unit 17 may determine whether or not the high-speed circuit breaker 5 is open. Specifically, the determination unit 17 determines whether or not the high-speed circuit breaker 5 is open based on the control signal sent by the circuit breaker control unit to the high-speed circuit breaker 5 or the contact signal output by the high-speed circuit breaker 5. It can be determined. The contact signal indicates whether or not the contacts of the high-speed circuit breaker 5 are conducting.

Further, in addition to the above-mentioned determination process, the determination unit 17 may further perform a determination process for preventing erroneous detection by the disconnection detection unit 18. An example of the determination process performed by the determination unit 17 will be described with reference to FIG. The process of steps S11-S17 of FIG. 6 is the same as the process of steps S11-S17 of FIG. When the determination unit 17 determines that the contactor MC1 and the contactor MC2 are open (step S11; Yes), all the switching elements of the power conversion unit 11 and the power conversion unit 12 are turned off. It is determined whether or not the device is used (step S19).

The determination of whether or not all the switching elements of each of the power conversion unit 11 and the power conversion unit 12 are turned off is based on the switching control signal S1 supplied by the switching control unit 16 to the power conversion units 11 and 12. Will be done. Specifically, the determination unit 17 acquires the switching control signal S1 and determines whether or not all the switching elements of the power conversion units 11 and 12 are turned off based on the switching control signal S1.

When the determination unit 17 determines that at least one switching element possessed by at least one of the power conversion units 11 and 12 is turned on (step S19; No), the process of step S11 is repeated. At this time, since the determination unit 17 supplies the low level determination signal S2 to the disconnection detection unit 18, the disconnection detection unit 18 does not perform the processing after step S12.

When the determination unit 17 determines that all the switching elements of the power conversion unit 11 and the power conversion unit 12 are turned off (step S19; Yes), the high level determination signal S2 is detected by the disconnection detection unit 18. The disconnection detection unit 18 performs the processing after step S12.

Further, for example, the determination unit 17 determines whether or not the power conversion units 11 and 12 are electrically separated from the current collector 4 and the electric railway vehicle on which the power conversion devices 1 and 2 are mounted is stopped. May be determined. The determination of whether or not the contactor MC1 and the contactor MC2 are open is as shown in the above-described embodiment. Whether or not the electric railway vehicle is stopped can be determined based on the speed of the electric railway vehicle. Specifically, the determination unit 17 acquires the speed of the electric railway vehicle from the speed sensors attached to the motors 51 and 52, and determines whether or not the electric railway vehicle is stopped. Then, when the determination unit 17 determines that the contactor MC1 and the contactor MC2 are open and the electric railway vehicle is stopped, the level becomes High and at least one of the contactors MC1 and MC2 is set. When it is determined that the electric railway vehicle has been turned on or the electric railway vehicle has not stopped, the determination signal S2 that becomes the Low level is output.

The number of filter capacitors is any value greater than or equal to 2. For example, a case where the power conversion devices 1 and 2 have three filter capacitors FC1, FC2, and FC3 will be described as an example. In this case, the power conversion devices 1 and 2 have contactors MC1, MC2, and MC3 that electrically connect the corresponding power conversion unit to the current collector 4 or electrically disconnect it from the current collector 4. And. Further, the value of the voltage between the terminals of the filter capacitors FC1, FC2 and FC3 measured by the voltage measuring unit is defined as EFC1, EFC2 and EFC3. The determination unit 17 determines whether or not the contactor MC1, the contactor MC2, and the contactor MC3 are open. The disconnection detection unit 18 determines whether or not at least one of the voltages EFC1, EFC2, and EFC3 is larger than the first reference voltage Th1 and at least one of the other voltages EFC1, EFC2, and EFC3 is equal to or less than the second reference voltage Th2. Judgment is made and the judgment result is output. For example, the disconnection detection unit 18 outputs a disconnection detection signal S3 indicating the filter capacitor FC3 when the voltage EFC1 is larger than the first reference voltage Th1 and the voltage EFC3 is equal to or less than the second reference voltage Th2.

The disconnection detection unit 18 may determine whether or not the difference between the voltages EFC1 and EFC2 is equal to or greater than the reference voltage difference, and output the determination result. Specifically, when the disconnection detection unit 18 determines that the voltage difference between the voltage EFC1 and the voltage EFC2 is equal to or greater than the reference voltage difference, it corresponds to the filter capacitors FC1 and FC2 having the higher terminal voltage among the filter capacitors FC1 and FC2. The disconnection detection signal S3 having an amplitude is output to the display device as a determination result. Specifically, the disconnection detection unit 18 detects disconnection having an amplitude corresponding to the filter capacitor FC1 when the voltage difference between the voltage EFC1 and the voltage EFC2 is equal to or greater than the reference voltage difference and the voltage EFC1 is higher than the voltage EFC2. The signal S3 is output. Further, the disconnection detection unit 18 outputs a disconnection detection signal S3 having an amplitude corresponding to the filter capacitor FC2 when the voltage difference between the voltage EFC1 and the voltage EFC2 is equal to or larger than the reference voltage difference and the voltage EFC2 is higher than the voltage EFC1. do. The reference voltage difference is a voltage difference that can be regarded as one of the filter capacitors FC1 and FC2 being charged and the other being discharged. For example, the voltage difference between the terminals when the filter capacitors FC1 and FC2 are fully charged. It is a value of 1/3.

The processing of the disconnection detection unit 18 will be described by taking the case where the power conversion devices 1 and 2 have three filter capacitors FC1, FC2, and FC3 as an example. The disconnection detection unit 18 calculates the voltage difference between the voltage EFC1 and the voltage EFC2, the voltage difference between the voltage EFC1 and the voltage EFC3, and the voltage difference between the voltage EFC2 and the voltage EFC3. Each calculated voltage difference is compared with the reference voltage difference, it is determined whether or not at least one calculated voltage difference is equal to or greater than the reference voltage difference, and the determination result is output. For example, when the voltage difference between the voltage EFC1 and the voltage EFC3 is equal to or greater than the reference voltage difference and the voltage EFC3 is larger than the voltage EFC1, the disconnection detection unit 18 outputs the disconnection detection signal S3 having an amplitude corresponding to the filter capacitor FC3. ..

The power conversion devices 1 and 2 determine whether or not at least one of the voltages EFC1 and EFC2 is larger than the second threshold voltage Th2 after the time required for discharging has elapsed since the contactors MC1 and MC2 were turned on. , The determination result may be output to the display device. As a result, when the filter capacitors FC1 and FC2 are not discharged, it is possible to operate without performing maintenance work.

The power conversion devices 1 and 2 can be mounted on any vehicle, any device, or the like that can supply DC power to the power conversion devices 1 and 2. As an example, the power conversion devices 1 and 2 can be mounted on an AC feeder type electric railway vehicle. FIG. 7 shows a power conversion device 10 mounted on an AC feeder type electric railway vehicle. AC power is supplied from the current collector 4, which has acquired AC power from the substation via the overhead wire 3, to the primary terminal of the transformer 6 via the high-speed circuit breaker 5. The transformer 6 lowers the voltage of the AC power supplied to the primary terminal, and supplies the stepped-down AC power to the power conversion device 10 from the secondary terminal.

Instead of the contactors MC1 and MC2, the power conversion device 10 converts the contactor MC4 connected to the secondary terminal of the transformer 6 and the AC power supplied to the primary terminal into DC power, and converts the DC power into two. It includes a converter 22 that outputs from the next terminal. The contactor MC3 electrically connects or electrically disconnects the power converters 11 and 12 and the current collector 4. The determination unit 17 included in the power conversion device 10 shown in FIG. 7 determines whether or not the contactor MC4 is turned on.
Further, not only electric railway vehicles but also diesel railcars can be equipped with the power conversion devices 1 and 2.

The common discharge circuit 15 has an arbitrary configuration as long as it is a circuit that discharges the filter capacitors FC1 and FC2. The circuits from the filter capacitors FC1 and FC2 to the common discharge circuit 15 are not limited to the diodes D1 and D2, and any circuit that enables the filter capacitors FC1 and FC2 to be discharged by the common discharge circuit 15 is arbitrary. A circuit having the above configuration can be provided.

The power conversion units 11 and 12 are not limited to VVVF inverters, and are optional as long as they are devices that convert DC power supplied to the primary terminal into DC power or AC power and supply it to the load connected to the secondary terminal. Is. For example, the power conversion units 11 and 12 are composed of a DC (Direct Current) -DC converter or a static inverter that supplies power to lighting equipment, air conditioning equipment, and the like. Further, for example, the power conversion unit 11 is composed of a VVVF inverter, and the power conversion unit 12 is composed of a static inverter. Further, the load connected to the secondary terminal of the power conversion unit 11 and the load connected to the secondary terminal of the power conversion unit 12 may be different types of loads.

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

1,2,10 Power converter, 1a Positive input terminal, 1b Negative input terminal, 3 Overhead wire, 4 Current collector, 5 High-speed circuit breaker, 6 transformer, 11,12 Power converter, 13,14 Voltage measuring unit, 15 Common discharge circuit, 16 switching control unit, 17 judgment unit, 18 disconnection detection unit, 19, 20 individual discharge circuit, 21 discharge control unit, 22 converter, 51, 52 electric motor, D1, D2 diode, FC1, FC2, FC3 filter capacitor , FL1, FL2 filter reactor, MC1, MC2, MC3, MC4 contactor, R1, R2, R3 resistor, S1 switching control signal, S2 judgment signal, S3 disconnection detection signal, S4 protection stop signal, SW1 switch, SW2, SW3 switching element.

Claims (9)

A plurality of power converters, each of which converts DC power supplied from a power source via a primary terminal into DC power or AC power and supplies it to a load connected to a secondary terminal.
A plurality of filter capacitors connected between the primary terminals of the power conversion unit, each of which corresponds to the power conversion unit.
With at least one contactor that electrically connects or disconnects the power converter from the power source.
A common discharge circuit that is connected to the plurality of filter capacitors, discharges the plurality of filter capacitors, and is common to the plurality of filter capacitors.
A determination unit that determines whether or not the plurality of power conversion units are electrically disconnected from the power supply, and a determination unit.
When the determination unit determines that the plurality of power conversion units are electrically disconnected from the power supply, the common discharge from each of the plurality of filter capacitors is based on the voltages of the plurality of filter capacitors. A disconnection detector that determines whether or not there is a disconnection in the circuit leading up to the circuit,
A power converter equipped with. In the disconnection detection unit, the terminal voltage of at least one filter capacitor among the plurality of filter capacitors is larger than the first reference voltage, and the terminal voltage of the other at least one filter capacitor is the first. Judges whether or not it is below the second reference voltage, which is lower than the reference voltage, and outputs the judgment result.
The power conversion device according to claim 1. In the disconnection detection unit, the terminal voltage of the at least one filter capacitor is larger than the first reference voltage, and the terminal voltage of the other at least one filter capacitor is equal to or lower than the second reference voltage. In this case, a disconnection detection signal indicating the at least one filter capacitor is output as the determination result.
The power conversion device according to claim 2. The disconnection detection unit determines whether or not the difference between the terminal voltage of one filter capacitor and the terminal voltage of the other filter capacitor is equal to or greater than the reference voltage difference, and outputs the determination result.
The power conversion device according to claim 1. When the difference between the terminal voltage of the one filter capacitor and the terminal voltage of the other filter capacitor is equal to or greater than the reference voltage difference, the disconnection detection unit performs the one filter capacitor and the other. Of the one filter capacitor, a disconnection detection signal indicating a filter capacitor with a high voltage between terminals is output as the determination result.
The power conversion device according to claim 4. A plurality of individual discharge circuits, each of which is connected to one corresponding filter capacitor and discharges the connected filter capacitor.
When the disconnection detection unit detects the presence of the disconnection, the discharge control unit operates the individual discharge circuit connected to the filter capacitor connected to the circuit in which the disconnection is detected. ,
Further prepare,
The power conversion device according to any one of claims 1 to 5. The determination unit determines whether or not the plurality of power conversion units are electrically disconnected from the power source and the plurality of power conversion units are stopped.
When the determination unit determines that the plurality of power conversion units are electrically disconnected from the power source and the plurality of power conversion units are stopped, the plurality of disconnection detection units may be used. Based on the voltage of the filter capacitor of the above, it is determined whether or not the circuit from each of the plurality of filter capacitors to the common discharge circuit is broken.
The power conversion device according to any one of claims 1 to 6. Equipped with a plurality of the contactors
Each of the plurality of contactors electrically connects or disconnects the corresponding power converter from or from the power source.
The power conversion device according to any one of claims 1 to 7. A plurality of power converters, each of which converts DC power supplied from a power source via a primary terminal into DC power or AC power and supplies the load connected to the secondary terminal, are electrically disconnected from the power source. Judge whether or not it is
When it is determined that the plurality of power conversion units are electrically disconnected from the power supply, each of them is based on the voltages of a plurality of filter capacitors connected to the primary terminals of the corresponding power conversion unit. , Whether or not there is a disconnection in the circuit from each of the plurality of filter capacitors to the common discharge circuit common to the plurality of filter capacitors is determined.
Disconnection detection method.

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