JPH08275570A - Power controller - Google Patents

Abstract

PURPOSE: To shorten the restart time of an inverter circuit by extinguishing the thyristor in a discharge circuit where the current flows continuously. CONSTITUTION: An inverter circuit 5 is connected in parallel with a discharge circuit 8 comprising a filter capacitor 3, a thyristor 10, a discharge resistor 9 and a transistor 12. The thyristor 10 is then fired with an overvoltage of the filter capacitor 3 and discharged thus eliminating the overvoltage of the filter capacitor 3. The transistor 12 is turned OFF through the voltage drop of the filter capacitor 3 thus extinguishing the thyristor 10. Immediately upon detecting extinction of the thyristor 10, a circuit breaker 2 is allowed to throw in thus shortening the restart time of the inverter circuit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control device used for controlling an electric motor for driving a railway vehicle or the like, and more particularly to a discharge circuit for overvoltage absorption during regenerative braking.

[0002]

2. Description of the Related Art FIG. 4 shows, for example, JP-A-62-25087.
8 is a circuit diagram showing a conventional power control device for controlling a three-phase induction motor shown in Japanese Patent Publication No. In FIG. 4, 1 is a DC power source supplied from an overhead line of a railroad track, 2 is a circuit breaker that disconnects the DC power source 1, 3 is a filter capacitor that absorbs energy generated during regenerative braking,
An inverse L-shaped filter circuit is configured with the filter reactor 4. Reference numeral 5 is a power conversion circuit that constitutes a three-phase inverter circuit, and includes diodes 6U, 6V, 6W, 6X, which are connected in antiparallel with control rectifying elements 5U, 5V, 5W, 5X, 5Y, 5Z such as gate turn-off thyristors. 6Y,
6Z and. 5PU, 5PV, 5PW are U, V, W phase positive electrode side element groups, 5NU, 5NV, 5NW
Is a negative side element group of U, V and W phases. Reference numeral 7 is an electric motor which is a three-phase induction motor connected to the load end of the inverter circuit 5 and drives a railway vehicle, and 8 is regenerative braking connected in parallel to the power supply end of the inverter circuit 5 and the filter capacitor 3. This is a discharge circuit for suppressing overvoltage at that time or discharging generated energy, and is constituted by a series circuit of a discharging resistor 9, a thyristor 10 and a diode 11.

Next, the operation will be described. In the case of so-called power running in which an electric motor is driven to drive a railway vehicle, the voltage of the DC power supply 1 is controlled by a gate control circuit (not shown) of the inverter circuit 5 to control each rectifying element 5U, 5V, 5
By sequentially switching controlling W, 5X, 5Y, and 5Z, three-phase variable voltage and variable frequency are generated to control the rotation speed of the three-phase induction motor 7. Further, in the case of so-called regenerative braking, in which braking is performed by an electric motor to reduce the speed of the railway vehicle, three-phase AC is generated by using the three-phase induction motor 7 as a generator, and each diode 6U, 6 of the inverter circuit 5 is generated.
V, 6W, 6X, 6Y, 6Z is converted into direct current, and the generated energy is absorbed by the direct current power supply 1 and the filter capacitor 3 to reduce the speed of the railway vehicle. At this time, if there is no load such as a railway vehicle on the power supply side and the internal impedance of the DC power supply 1 is high, the energy generated by the three-phase induction motor 7 cannot be absorbed. In this state, not only regenerative braking will not be performed sufficiently, but also the DC voltage of the DC power supply 1 or the filter capacitor 3 will rise abnormally, which may cause equipment failure or serious accident such as flashover accident or ground fault accident. It may progress.

In such a case, the filter capacitor 3
Is detected, the gate control circuit (not shown) of the inverter circuit 5 is stopped, and the breaker 2 is cut off to disconnect the inverter circuit 5 from the DC power supply 1. Then, after the inverter circuit 5 is disconnected from the DC power supply 1, the thyristor 10 is ignited by a gate control circuit (not shown) of the thyristor 10 to discharge the resistor 9 for discharging.
At the same time, the voltage of the filter capacitor 3 is discharged to reduce the voltage, and the energy generated by the three-phase induction motor 7 is absorbed by the discharging resistor 9.

However, even if the voltage of the filter capacitor 3 is discharged by the discharge circuit 8 and the voltage is lowered, the follow-up current I continues to flow due to the residual induced voltage V of the three-phase induction motor 7, so that the thyristor 10 starts to operate for several seconds. The state that the arc cannot be extinguished continues for several tens of seconds. At this time, when the circuit breaker 2 is turned on again to start the inverter circuit 5, a large current flows from the DC power source 1 into the discharge circuit 8, and the circuit breaker 2 immediately performs the breaking operation by the overcurrent protection circuit (not shown). When the thyristor 10 cannot be extinguished, the circuit breaker 2 cannot be closed and the inverter circuit 5 cannot be restarted. Therefore, in the discharge circuit 8, the diode 11 is connected in series with the thyristor 10.
And the forward breakdown voltage of the thyristor 10 and the diode 11 is set to be equal to or higher than the residual induced voltage V of the three-phase induction motor 7. That is, after the voltage of the filter capacitor 3 is discharged by the discharge circuit 8 and the voltage becomes lower than the forward breakdown voltage of the thyristor 10 and the diode 11, the follow current I does not flow and the thyristor 10 extinguishes. Since the circuit breaker 2 is turned on again, the inverter circuit 5 can be restarted in a short time.

[0006]

Since the conventional power control device is constructed as described above, the thyristor 10 having no self-extinguishing function is quickly extinguished to restart the power conversion circuit in a short time. To this end, it is necessary to set the forward breakdown voltage of the thyristor 10 and the diode 11 higher than the residual induced voltage V of the three-phase induction motor 7, and therefore a plurality of diodes 11 must be connected in series.
However, since the forward breakdown voltage of the diode 11 is generally 1 volt or less, it is necessary to connect four to five diodes 11 in series in order to realize the desired operation. However, a large current of several hundred amperes sometimes flows in the discharge circuit 8, and of course, it is necessary to prepare a diode 11 having a large capacity to allow it, and increasing the number thereof increases cost. It was an obstacle to increase and miniaturization. Further, the forward breakdown voltage of the diode 11 has a large variation, and the arc-extinguishing time of the thyristor 10 differs accordingly. Therefore, the restart time of the power conversion circuit 5 is restricted by the minimum breakdown voltage of the diode 11. There is a problem that it is necessary to set a time exceeding the maximum value of the arc extinguishing time of the thyristor 10, and the time cannot be shortened.

The power control device according to the present invention has been made to solve the above-mentioned problems, and enables the thyristor of the discharge circuit to be quickly and surely extinguished.
Another object of the present invention is to provide a power control device that can detect the extinction of a thyristor, shorten the restart time of the power conversion circuit, and realize a low cost and downsizing.

[0008]

In a power control device according to the present invention, a power conversion circuit connected to a DC power supply for converting power supplied to an electric motor and returning regenerative power from the electric motor to the DC power supply. A series circuit of a thyristor, a resistor and a transistor connected in parallel to the power conversion circuit and a thyristor connected in parallel to the filter capacitor and fired when the voltage of the filter capacitor is equal to or higher than a first predetermined value. A discharge circuit consisting of
A voltage responsive circuit that turns on the transistor when the thyristor is ignited and turns off the transistor when the voltage of the upper filter capacitor is equal to or lower than a second predetermined value that is lower than the first predetermined value. , A voltage responsive circuit that reliably extinguishes the thyristor.

Further, a power converter circuit connected to the DC power source through a circuit breaker to convert electric power supplied to the electric motor and for returning regenerative power from the electric motor to the DC power source, and a power converter circuit connected in parallel to the power converter circuit. Filter capacitor,
A discharge circuit consisting of a series circuit of a thyristor, a resistor and a transistor, connected in parallel with a filter capacitor,
When the voltage of the filter capacitor is equal to or higher than the first predetermined value, the circuit breaker is shut off, and when the voltage (or current) related to the transistor exceeds the third predetermined value, the circuit breaker is closed and the voltage related to the transistor is disabled. A circuit breaker control circuit that permits closing of the circuit breaker when (or current) is less than or equal to the third predetermined value, and a gate control circuit that fires the thyristor when the voltage of the filter capacitor is greater than or equal to the first predetermined value. And a voltage responsive circuit that turns on the transistor when the thyristor is ignited and turns off the transistor when the voltage of the filter capacitor is less than or equal to a second predetermined value that is lower than the first predetermined value. The voltage-responsive circuit surely extinguishes the thyristor, and this extinction is detected when the voltage (or current) related to the transistor falls below the third predetermined value. It is intended to allow the insertion of the circuit breaker.

Further, the voltage response circuit for controlling the on / off of the transistor of the discharge circuit is constituted by a Zener diode connected between the collector and the base of the transistor of the discharge circuit.

Further, the voltage response circuit for controlling the on / off of the transistor of the discharge circuit is constituted by the first resistor connected between the collector and the base of the transistor of the discharge circuit and the second resistor connected between the base and the emitter. It is a thing.

Further, the power conversion circuit is composed of an inverter circuit.

Furthermore, the power conversion circuit is composed of a chopper circuit.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. 1 is a circuit diagram showing Embodiment 1 of a power control device according to the present invention. In FIG. 1, 1 is a DC power source supplied from an overhead line of a railroad track, 2 is a circuit breaker that disconnects the DC power source 1, 3 is a filter capacitor that absorbs power generation energy when performing regenerative braking,
Reference numeral 4 is a filter reactor which forms an inverse L-shaped filter circuit together with the filter capacitor 3 and stabilizes the DC voltage and smoothes the DC current ripple.

Reference numeral 5 denotes a positive side element group 5PU of U, V and W phases,
5PV, 5PW and U, V, W phase negative electrode side element group 5N
U, 5NV, 5NW are connected in series for each phase, and a power conversion circuit forming a three-phase inverter circuit in which both ends of the U, V, W phases connected in series are all connected in parallel to the filter capacitor 3. 5U, 5V, 5W are control rectifiers such as gate turn-off thyristors provided on the positive side of U, V, W phases, and 5X, 5Y, 5Z are gate turn-offs provided on the negative side of U, V, W phases. Control rectifying elements such as thyristors, 6U, 6V, 6W, 6X, 6Y, 6Z are diodes respectively connected in antiparallel with the control rectifying elements of these respective phases, and with the control rectifying elements of each antiparallel connected phase. The diodes are the positive electrode side element groups 5PU and 5 respectively.
PV, 5PW and negative electrode side element group 5NU, 5NV, 5N
Makes up W.

Reference numeral 7 is an output terminal of the inverter circuit 5, that is, a group of positive side elements 5PU, 5PV, 5PW of U, V and W phases.
And U, V, W phase negative electrode side element groups 5NU, 5NV, 5N
A three-phase induction motor for driving a railway vehicle or the like, which is connected for each phase at an intermediate connection point with W, and 8 is a power source end of the inverter circuit 5 and a filter capacitor 3 connected in parallel for regenerative braking Is a discharge circuit for suppressing overvoltage or discharging generated energy, and is configured by connecting a discharge resistor 9, a thyristor 10 and a transistor 12 in place of the diode 11 of the conventional device in series.

Reference numeral 13 is a zener diode which serves as a voltage response circuit for controlling the on / off of the transistor 12, and determines the collector-base voltage of the transistor 12. 14
Is a resistor that lowers the impedance between the base and the emitter to prevent malfunction of the transistor 12, and 15 is a collector of the transistor 12 when the transistor 12 is turned off.
It is a resistor that stabilizes the voltage between the emitters near 0 volt. Reference numeral 16 is a voltage detection circuit for detecting a predetermined overvoltage of the filter capacitor 3, and reference numeral 18 is a circuit breaker to shut off the inverter circuit 5 from the DC power supply 1 when the voltage detection circuit 16 detects a predetermined overvoltage of the filter capacitor 3. When the collector-emitter voltage of the transistor 12 exceeds a predetermined value, the circuit breaker 2 is prohibited from being turned on, and when the collector-emitter voltage of the transistor 12 is below the predetermined value, the circuit breaker 2 is turned on. It is a circuit breaker control circuit that permits. Reference numeral 17 denotes a gate control circuit for igniting the thyristor 10 of the discharge circuit 8 after the circuit breaker 2 is cut off, that is, after a predetermined delay time, when the voltage detection circuit 16 detects a predetermined overvoltage of the filter capacitor 3. When the overvoltage of the filter capacitor 3 is detected and the thyristor 10 of the discharge circuit 8 is ignited, I is, for example, the diode 6U, the discharge circuit 8 and the diode 6Y which continue to flow due to the residual induced voltage V of the three-phase induction motor 7. It is a flowing current.

Next, the operation of the entire power conversion circuit will be described. In the case of so-called power running in which an electric motor is driven to drive a railway vehicle, when the circuit breaker 2 is turned on, the voltage of the DC power supply 1 is charged in the filter capacitor 3 through the filter reactor 4 and the inverter circuit 5 which is a power conversion circuit. It becomes the DC voltage source of. A gate control circuit (not shown) of the inverter circuit 5 sequentially switches and controls each of the control rectifying elements 5U, 5V, 5W, 5X, 5Y, and 5Z to convert this DC voltage into a three-phase variable voltage and an AC voltage with a variable frequency. The speed of the railway vehicle is converted to control the rotational speed of the three-phase induction motor 7 to control the running of the railway vehicle.

Further, in the case of so-called regenerative braking, in which braking is performed by an electric motor in order to reduce the speed of the railway vehicle, three-phase AC is generated by using the three-phase induction motor 7 as a generator, and each diode 6U of the inverter circuit 5 is generated. , 6V, 6W, 6X, 6
The speed of the railway vehicle is decelerated by converting it to DC in Y and 6Z and causing the generated power energy to be absorbed by the DC power supply 1 and the filter capacitor 3. At this time, if there is no load such as a railway vehicle on the power supply side and the internal impedance of the DC power supply 1 is high, the energy generated by the three-phase induction motor 7 cannot be absorbed. For this reason, the DC voltage of the DC power supply 1, the filter capacitor 3, etc. starts to rise abnormally.

Then, the voltage detection circuit 16 detects an overvoltage of a predetermined value or more of the filter capacitor 3, the output of the voltage detection circuit 16 stops the gate control circuit (not shown) of the inverter circuit 5, and the circuit breaker control circuit 18 The inverter circuit 5 is disconnected from the DC power source 1 by breaking the circuit breaker 2 by means of the circuit breaker 2. Then, after the inverter circuit 5 is disconnected from the DC power supply 1 after a predetermined interruption time of the circuit breaker 2, that is, after a predetermined delay time, the gate control circuit 17 causes the thyristor 10 to fire. Then
Since a voltage higher than the Zener voltage is applied between the collector and the base of the transistor 12 and the base current of the transistor 12 flows through the Zener diode 13, the transistor 12 becomes conductive and the resistor 9-thyristor 10-discharge circuit 8 of the transistor 8 is provided. A current flows through the discharge resistor 9 to discharge the voltage of the filter capacitor 3 to reduce the voltage, and the discharge resistor 9 absorbs the energy generated by the three-phase induction motor 7.

The voltage of the filter capacitor 3 is the discharge circuit 8
Is discharged and the voltage drops, but due to the residual induced voltage V of the three-phase induction motor 7, for example, the diode 6U,
The follow current I continues to flow through the discharge circuit 8 and the diode 6Y and the residual induced voltage V of the three-phase induction motor 7
Is converted into a DC voltage by the diodes 6U, 6V, 6W, 6X, 6Y, 6Z and charges the filter capacitor 3. Therefore, since the follow current I continues to flow in the thyristor 10, the thyristor 10 alone cannot extinguish the arc.

Here, the transistor 12 and the Zener diode 1 which is a voltage responsive circuit for controlling the ON / OFF of the transistor 12 are provided.
The operation of No. 3 will be described. When the collector-base voltage of the transistor 12 exceeds the Zener voltage of the Zener diode 13, a base current flows to the base of the transistor 12 via the Zener diode 13, and the transistor 1
2 turns on. Also, the collector of the transistor 12
When the voltage between the bases becomes equal to or lower than the zener voltage of the zener diode 13, the base current stops flowing and the transistor 12
Turns off. Further, in general, the voltage between the base and the emitter of the transistor 12 is a constant voltage of 1 volt or less like the forward breakdown voltage of the diode 11, so the collector-emitter voltage of the transistor 12 is equal to the zener voltage of the zener diode 13. , And the voltage between the base and emitter of the transistor 12 is controlled to be the sum of these voltages.

Therefore, if the predetermined collector-emitter voltage of the transistor 12 is set to the residual induced voltage V of the three-phase induction motor 7 or more, the filter capacitor 3
When the voltage of 2 becomes lower than the collector-emitter voltage of the transistor 12, the follow current I stops flowing and the thyristor 10 extinguishes. Therefore, the thyristor 10
It is possible to prevent the restart time of the inverter circuit 5 from being lengthened due to the delay in extinguishing the arc due to the follow current I.

For example, in the case where the residual induced voltage V of the three-phase induction motor 7 is 3 volts, the conventional technique and the present embodiment will be compared. In the conventional technology, the diode 11
If the forward breakdown voltage is 0.7 V, for example, in order to make the residual induction voltage V of the three-phase induction motor 7 or more, generally, five or more diodes 11 capable of flowing a large current of several hundred amperes are connected in series. There is a need to. Further, when the variation in the forward breakdown voltage of the diode 11 is 0.6 V to 0.9 V, the five diodes 1 connected in series are
1. The forward breakdown voltage of the whole 1 varies from 3 V to 4.5 V. Therefore, the restart time of the inverter circuit 5 needs to be set to a time exceeding the maximum value of the arc extinguishing time of the thyristor 10 under the restriction of the minimum breakdown voltage of the diode 11, and the time cannot be shortened.

On the other hand, if the voltage response circuit for controlling the on / off of the transistor 12 is constituted by the Zener diode 13, the Zener of the Zener diode 13 is compared with the case where the forward breakdown voltage by the series connection of the diodes 11 is used. Since there is little variation in the voltage, there is less variation in the time until the thyristor 10 is extinguished, and the restart time of the inverter circuit 5 can be shortened. Further, since only the base current of the transistor 12 flows through the Zener diode 13, the Zener diode 13 can be installed on the control board, and the cost and the size can be reduced.

Further, in the circuit breaker control circuit 18, when the transistor 12 is turned off and the follow current I does not flow and the thyristor 10 is extinguished, the collector-emitter voltage of the transistor 12 becomes close to 0 volt. The voltage is detected and the circuit breaker 2 is permitted to be closed. That is, the extinction of the thyristor 10 is detected by the collector-emitter voltage of the transistor 12, and the circuit breaker 2 is permitted to be closed immediately after the extinction of the thyristor 10 so that the inverter circuit 5 can be started. The restart time of 5 can be further shortened.

In the first embodiment, the case where the residual induced voltage V of the three-phase induction motor 7 is 3 V has been described.
If the residual induced voltage V changes, it may be replaced with a Zener diode 13 having a different Zener voltage.

Embodiment 2. Second Embodiment FIG. 2 is a circuit diagram showing a second embodiment of a power control device according to the present invention. Reference numeral 19 denotes a first transistor connected between the collector and the base of the transistor 12.
Is a second resistor connected between the base and the emitter of the transistor 12, and constitutes a voltage response circuit 13 for controlling the on / off of the transistor 12 by the first and second resistors.

The operation of the transistor 12 is controlled by the base current of the transistor 12, which is controlled by the voltage value divided by the first resistor 19 and the second resistor 20 of the voltage response circuit 13, so that the transistor 12 is on / off controlled. By doing so, the same operation as in the first embodiment is performed. At this time, as described above, the base-emitter voltage of the transistor 12 becomes a constant voltage of 1 volt or less. Since the ratio of the collector-base voltage of the transistor 12 to the base-emitter voltage of the transistor 12 is controlled to be equal to the ratio of the first resistor 19 and the second resistor 20, the transistor 12 is on / off controlled. The collector-base voltage is the same as the base-emitter voltage in the first resistor 19 and the second resistor 2.
The voltage is controlled by multiplying the ratio with 0. Therefore, the collector-emitter voltage of the transistor 12, which is the sum of the collector-base voltage of the transistor 12 and the base-emitter voltage, is controlled to a constant voltage.

Therefore, as in the first embodiment, if the collector-emitter voltage of the transistor 12 is set to be equal to or higher than the residual induced voltage V of the three-phase induction motor 7, the voltage of the filter capacitor 3 becomes that of the transistor 12. When the voltage becomes lower than the predetermined collector-emitter voltage, the follow current I stops flowing, and the thyristor 10 extinguishes. Therefore, it is possible to prevent the restart time of the inverter circuit 5 from being lengthened due to the delay in extinguishing the thyristor 10 by the follow current I.

As described above, the voltage responsive circuit for controlling the on / off of the transistor 12 is constituted by the voltage dividing circuit of the first resistor 19 and the second resistor 20, and the voltage between the base and the emitter of the transistor 12 is set to the first. 1 resistance 19 and 2 resistance 2
When controlled by a voltage multiplied by the ratio of 0, the thyristor 10 extinguishes because there is less variation in the base-emitter voltage of the transistor 12 compared to the case where a forward breakdown voltage due to series connection of the diode 11 is used. There is less variation in the time until, and the restart time of the inverter circuit 5 can be shortened. Since only a small current such as the base current of the transistor 12 flows between the first resistor 19 and the second resistor 20, the first resistor 19 and the second resistor 20 can be installed on the control board at low cost. It can be miniaturized.

Further, when the transistor 12 is turned off and the follow current I does not flow and the thyristor 10 is extinguished, the circuit breaker control circuit 18 makes the collector-emitter voltage of the transistor 12 close to 0 volt. The voltage is detected and the circuit breaker 2 is permitted to be closed. That is, the arc extinction of the thyristor 10 is detected by the collector-emitter voltage of the transistor 12, and the circuit breaker 2 is permitted to be closed immediately after the arc extinction of the thyristor 10 so that the inverter circuit 5 can be started. The restart time of 5 can be further shortened.

In Embodiments 1 and 2, the inverter circuit 5 which is a power conversion circuit has been described as a 2-level inverter circuit, but it may be a 3-level inverter circuit.

Embodiment 3. 3 is a circuit diagram of a power control device according to a third embodiment of the present invention when a power conversion circuit is applied to a chopper circuit for controlling a DC motor. Reference numeral 21 denotes a positive electrode side element group 21PA in which a controlled rectifying element 21A and a diode 22A are connected in antiparallel, and a controlled rectifying element 2
1B and diode 22B are connected in antiparallel to the positive electrode side element group 21PB, control rectifying element 21C and diode 22C are connected in antiparallel to the negative side element group 21NC, and control rectification element 21D and diode 22D are connected in antiparallel to the negative electrode side. It is a power conversion circuit that constitutes a chopper circuit that constitutes a bridge circuit by four element groups of the element group 21ND. The connection point of the positive side element groups 21PA and 21PB and the connection point of the negative side element groups 21NC and 21ND of this bridge circuit are connected in parallel to the filter capacitor 3, and the positive side element group 21PA which is the other end of this bridge circuit and Intermediate point of series circuit of negative electrode side element group 21NC and positive electrode side element group 21PB
And the intermediate point of the series circuit of the negative electrode side element group 21ND is connected to the field winding 23 of the DC motor that drives the railway vehicle. The control rectifying elements 21A, 21B, 21C, 2
1D uses a gate turn-off thyristor or the like to control the field current flowing in the field winding 23 of the DC motor.

Reference numeral 24 is a control rectifying element for an armature chopper such as a gate turn-off thyristor for controlling the armature current flowing in the armature winding 25 of the DC motor, and 26 is connected in parallel to the armature winding 25 of the DC motor. A flywheel diode that circulates an armature current flowing in the armature winding 25 of the DC motor, and a series circuit of the armature winding 25 and the control rectifying element 24 for the armature chopper is provided in the filter capacitor 3 and the chopper circuit 5. Connected in parallel. I detects the overvoltage of the filter capacitor 3 and when the thyristor 10 of the discharge circuit 8 is ignited, the residual induced voltage V of the field winding 23 of the DC motor causes the diode 22
A, a follow-up current flowing through the discharge circuit 8 and the diode 22D.

Therefore, as in the first embodiment, when the DC voltage of the DC power supply 1 or the filter capacitor 3 rises abnormally during regenerative braking,
Even after the breaker 2 is cut off and the thyristor 10 is ignited and discharged by the discharge resistor 9, the field winding 23 of the DC motor
The follow-up current I continues to flow in the discharge circuit 8 due to the residual induced voltage V. However, if the predetermined collector-emitter voltage of the transistor 12 is set to be equal to or higher than the residual induced voltage V of the field winding 23 of the DC motor, the filter capacitor 3
When the voltage of 2 becomes lower than the collector-emitter voltage of the transistor 12, the transistor 12 is turned off and the follow current I stops flowing, so that the thyristor 10 extinguishes. Therefore, it is possible to prevent the restart time of the chopper circuit 5 from being lengthened due to the delay in extinguishing the thyristor 10 by the follow current I.

As described above, assuming that the voltage response circuit for controlling the on / off of the transistor 12 is composed of the Zener diode 13 as in the first embodiment, the diode 1
Since the zener voltage of the zener diode 13 has less variation compared to the case where the forward breakdown voltage due to the series connection of 1 is used, there is less variation in the time until the thyristor 10 extinguishes, and the re-creation of the chopper circuit 11 is reduced. Start-up time can be shortened. Further, since only the base current of the transistor 12 flows through the Zener diode 13, the Zener diode 13 can be installed on the control board, and the cost and the size can be reduced.

Further, in the circuit breaker control circuit 18, when the transistor 12 is turned off and the follow current I does not flow and the thyristor 10 is extinguished, the collector-emitter voltage of the transistor 12 becomes close to 0 volt. The voltage is detected and the circuit breaker 2 is permitted to be closed. That is, the extinction of the thyristor 10 is detected by the collector-emitter voltage of the transistor 12, and the circuit breaker 2 is permitted to be closed immediately after the thyristor 10 is extinguished so that the chopper circuit 5 can be activated. The restart time of 5 can be further shortened.

In the first to third embodiments, the thyristor 10 is used.
It has been described that the current is extinguished and the follow current I stops flowing by detecting that the transistor 12 is turned off and the collector-emitter voltage of the transistor 12 becomes close to 0 volt. It does not matter whether the detection is performed when the voltage between the bases is near 0 volt or when the base current of the transistor 12 is near 0 amperes.

Further, in the first to third embodiments, the control rectifying elements 5U, 5V, 5W, 5X, 5Y of the inverter circuit,
Controlled rectifying elements 21A, 21 of 5Z or chopper circuit
B, 21C and 21D and the control rectifying element 24 for the armature chopper have been described by using the gate turn-off thyristor, but they are transistors, field effect transistors or IGs.
Various self-arc-extinguishing type semiconductor elements such as BT (insulated gate bipolar transistor) may be used.

Further, in the first to third embodiments, the controlled rectifying elements 5U, 5V, 5W, 5X, 5Y of the inverter circuit,
Diodes 6U and 6 respectively connected in anti-parallel to 5Z
Diodes 22A, 22B, 22C, 2 respectively connected in anti-parallel to V, 6W, 6X, 6Y, 6Z or controlled rectifiers 21A, 21B, 21C, 21D of a chopper circuit.
Although 2D has been described as another element, various self-arc-extinguishing semiconductor elements in which a controlled rectifying element and a diode connected in anti-parallel on the same element are combined may be used.

In the first to third embodiments, the structure of the discharge circuit 8 is changed from the negative side of the DC power source to the transistor 1
2, the thyristor 10 and the discharging resistor 9 are described in this order, but the order may be any.

Furthermore, in the first to third embodiments, the transistor 12 has been described as an NPN transistor.
In addition to the NP transistor, various semiconductor elements such as a field effect transistor or an IGBT (insulated gate bipolar transistor) may be used.

[0044]

As described above, according to the power control device of the present invention, the power conversion circuit is connected to the DC power supply to convert the electric power supplied to the electric motor and to return the regenerative electric power from the electric motor to the DC power supply. A series circuit of a thyristor, a resistor and a transistor connected in parallel to the power conversion circuit and a thyristor connected in parallel to the filter capacitor and fired when the voltage of the filter capacitor is equal to or higher than a first predetermined value. And a voltage responsive circuit that turns on the transistor when the thyristor is ignited and turns off the transistor when the voltage of the filter capacitor is below a second predetermined value lower than the first predetermined value. Since it is provided, the thyristor can be extinguished quickly and reliably, and the restart time of the power conversion circuit can be shortened.

Further, a power converter circuit connected to the DC power source through a circuit breaker to convert electric power supplied to the electric motor and returning the regenerative power from the electric motor to the DC power source is connected in parallel to the power converter circuit. Filter capacitor,
A discharge circuit consisting of a series circuit of a thyristor, a resistor and a transistor, connected in parallel with a filter capacitor,
When the voltage of the filter capacitor is equal to or higher than the first predetermined value, the circuit breaker is shut off, and when the voltage (or current) related to the transistor exceeds the third predetermined value, the circuit breaker is closed and the voltage related to the transistor is disabled. A circuit breaker control circuit that permits closing of the circuit breaker when (or current) is less than or equal to the third predetermined value, and a gate control circuit that fires the thyristor when the voltage of the filter capacitor is greater than or equal to the first predetermined value. And a voltage responsive circuit that turns on the transistor when the thyristor is ignited and turns off the transistor when the voltage of the filter capacitor is lower than the second predetermined value lower than the first predetermined value. Can be quickly and reliably extinguished, and the restart time of the power conversion circuit can be shortened.

Further, since the voltage response circuit is constituted by the Zener diode connected between the collector and the base of the transistor, the thyristor can be extinguished quickly and reliably, the restart time of the power conversion circuit can be shortened, and Miniaturization can be realized at low cost.

Further, since the voltage responsive circuit is composed of the first resistor connected between the collector and the base of the transistor and the second resistor connected between the base and the emitter of the transistor, the thyristor is quickly and surely extinguished. Therefore, the restart time of the power conversion circuit can be shortened, and downsizing can be realized at low cost.

Further, the power conversion circuit is composed of an inverter circuit, and when the voltage of the filter capacitor connected in parallel to this inverter circuit is below a predetermined value, the voltage response circuit turns off the transistor of the discharge circuit, and the current flowing to the discharge circuit continues. By limiting the flowing current, the thyristor can be extinguished quickly and reliably, and the restart time of the inverter circuit can be shortened.

Furthermore, the power conversion circuit is composed of a chopper circuit, and when the voltage of the filter capacitor connected in parallel to this chopper circuit is below a predetermined value, the voltage response circuit turns off the transistor of the discharge circuit and flows to the discharge circuit. By limiting the follow current, the thyristor can be quickly and surely extinguished, so that the restart time of the chopper circuit can be shortened.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a power control device of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the power control device of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the power control device of the present invention.

FIG. 4 is a circuit diagram showing a conventional power control device for controlling a three-phase induction motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Circuit breaker 3 Filter capacitor 5 Inverter circuit which is a power conversion circuit 7 Electric motor 8 Discharge circuit 9 Resistance 10 Thyristor 12 Transistor 13 Voltage response circuit 16 Voltage detection circuit 17 Gate control circuit 18 Circuit breaker control circuit 19 First resistance 20 2nd resistance 21 Chopper circuit which is a power conversion circuit 23 Field winding of an electric motor 25 Armature winding of an electric motor

Claims (6)

[Claims] 1. A power conversion circuit connected to a DC power supply for converting the power supplied to an electric motor and returning regenerative power from the electric motor to the DC power supply; and a filter capacitor connected in parallel to the power conversion circuit. A thyristor, which is connected in parallel to the filter capacitor and is fired when the voltage of the filter capacitor is equal to or higher than a first predetermined value, a discharge circuit including a series circuit of a resistor and a transistor, and the thyristor is fired. And a voltage response circuit that turns on the transistor when the voltage of the filter capacitor is equal to or lower than a second predetermined value that is lower than the first predetermined value. Control device. 2. A power conversion circuit, which is connected to a DC power supply through a circuit breaker, converts electric power supplied to the electric motor, and returns regenerative power from the electric motor to the DC power supply, and a power conversion circuit connected in parallel to the power conversion circuit. A discharge circuit consisting of a connected filter capacitor, a series circuit of a thyristor, a resistor and a transistor, connected in parallel to the filter capacitor, and interrupting the circuit breaker when the voltage of the filter capacitor is equal to or higher than a first predetermined value. At the same time, when the voltage (or current) related to the transistor exceeds a third predetermined value, the circuit breaker is closed, and when the voltage (or current) related to the transistor is equal to or less than the third predetermined value, A circuit breaker control circuit that permits closing of the circuit breaker, and the thyristor is fired when the voltage of the filter capacitor is equal to or higher than the first predetermined value. And a voltage control circuit for turning on the transistor when the thyristor is ignited and turning off the transistor when the voltage of the filter capacitor is below a second predetermined value lower than the first predetermined value. A power control device comprising: a circuit. 3. The power control device according to claim 1, wherein the voltage response circuit is constituted by a Zener diode connected between the collector and the base of the transistor. 4. The voltage-responsive circuit is constituted by a first resistor connected between the collector and the base of the transistor and a second resistor connected between the base and the emitter of the transistor. 2. The power control device according to 2. 5. The power control device according to claim 1, wherein the power conversion circuit is an inverter circuit. 6. The power control device according to claim 1, wherein the power conversion circuit comprises a chopper circuit.