JPS6337582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for a power control device that prevents overvoltage in the power control device.

FIG. 1 shows a drive circuit for an electric motor in a railway vehicle. In the figure, 1 is a current collector connected to the overhead line, and 2 is a main circuit disconnector (hereinafter referred to as a switch).
3 is a reactor, and 4 is a capacitor. The reactor 3 and the capacitor 4 constitute an inverted L-shaped filter 5 that absorbs internal and external surges. Reference numeral 6 designates a power control device comprising a variable voltage variable frequency inverter (hereinafter simply referred to as an inverter) comprising a controlled rectifier, and 7 represents an induction motor (hereinafter referred to as IM) whose speed is controlled by the inverter 6.

When the electric brake is used to regenerate electric power to reduce the speed of the vehicle and bring it to a stop, the regenerated electric power is consumed by other powered vehicles.

However, during regeneration, if there is no load on the same feeding system that consumes the regenerated power, there is nowhere for the regenerated power to go, so charge is stored in the capacitor 4, the voltage rises rapidly, and an overvoltage occurs, causing the control of the inverter 6. This may lead to destruction of the rectifying element.
Therefore, a protection method is generally used in which the overvoltage is detected and the charge in the capacitor 4 is discharged.

FIG. 2 shows a conventional example of the above protection system. In the figure, 8 is a discharge resistor, 9 is a discharge control rectifier,
Reference numeral 10 denotes voltage detection means composed of a DCPT for detecting overvoltage, and reference numeral 11 denotes a series resistor for dividing the high voltage of the capacitor 5 and applying it to the voltage detection means 10.

In FIG. 2, when the output of the voltage detection means 10 exceeds a predetermined value, it is determined that there is an overvoltage, the discharge control rectifier element 9 is fired, the charge is consumed by the discharge resistor 8, and the switch 2 A protection method is adopted in which the circuit is released from the overhead wire by giving an opening command to the terminal.

FIG. 3 shows a conventional example in which a large number of inverters are connected to drive a vehicle. In the figure, 3
a and 3b are first and second reactors, respectively;
4a and 4b are first and second capacitors.
Note that the first reactor 3a and the first capacitor 4a constitute a first filter 5a, and the second reactor 3b and second capacitor 4b constitute a second filter 5b. 10a, 10b are voltage detection means, 11a, 11b are series resistors, 12a, 1
2b is a matching rectifier element for separating the potentials of the first and second inverters 6a and 6b, 7a,
7b is an induction motor.

In FIG. 3, consider the case where the discharge control rectifying element 9 is erroneously fired. In this case, the current determined by the voltage supplied from the overhead wire and the discharge resistor 8 = (overhead wire voltage) ÷ (discharge resistance value) continues to flow, but since the voltage of the capacitors 4a and 4b does not decrease, the voltage detection means 10a, 10b, the change cannot be detected, and the discharge resistor 8, the discharge control rectifying element 9, and the matching rectifying elements 12a and 12b burn out.

The present invention has been made to eliminate the above-mentioned drawbacks, and provides a protection device for a power control device that can detect erroneous firing of a discharge control rectifier element and prevent equipment burnout.

The figures will be explained below. In Figure 4,
13a and 13b are respective voltage detection means 10a and 10b.
In addition, when the discharge control rectifying element 9 is activated, each voltage detection means 10
This is a rectifying element for detection in which inputs a and 10b are short-circuited. When the discharge control rectifying element 9 is activated, the output of each voltage detection means 10a, 10b becomes zero instantaneously. Therefore, both voltage detection means 10
The outputs of capacitors 4a and 10b are connected to capacitors 4a and 10b, respectively.
When the voltage 4b becomes zero, it is determined that erroneous ignition has occurred and the switch 2 is released, thereby preventing burnout of each device.

FIG. 5 shows another embodiment of the invention. In the figure, 14a, 14b, 15a, and 15b are series resistors of each voltage detection means 10a and 10b, respectively, which are divided into two and the detection rectifier 1 is connected from the dividing point.
3a and 13b are connected to the discharge control rectifier element 9. By dividing the series resistance in this way, when the detection rectifying elements 13a and 13b are destroyed,
High voltage is prevented from being directly applied to the voltage detection means 10a, 10b.

Although the above embodiment has been described using a combination of an inverter and an induction motor, the same functions can be achieved even if the power control device is a chopper control device and the motor is a DC motor or the like.

According to the present invention, since the switch is opened upon detecting the erroneous firing of the discharge control rectifying element, it is possible to prevent each device from being burnt out.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a drive circuit of a drive motor in an electric vehicle, Fig. 2 is a block diagram showing a conventional overvoltage protection device, and Fig. 3 is a block diagram showing a conventional overvoltage protection device applied to a power control device. , FIG. 4 is a block diagram showing one embodiment of the present invention, and FIG. 5 is a block diagram showing another embodiment of the present invention. In the figure, 2 is a switch, 5a and 5b are first and second filters,
6a and 6b are first and second inverters (power control devices), 7a and 7b are induction motors, 8 is a discharge resistor, 9 is a discharge control rectifier, 10a and 10b are voltage detection means, and 11a and 11b are connected in series. resistance, 12
a, 12b are butt rectifying elements, 13a, 13
b is a rectifying element for detection. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] 1. Inverted L-shaped first and second filters comprising a reactor and a capacitor are connected to a power source via one switch, and each filter is connected to a first and second filter comprising a controlled rectifying element. A first and a second electric motor are connected to each of the power control devices, respectively, and the first and second motors are connected to the respective anodes from the connection point of the reactor and the capacitor of each of the filters. The cathodes of the rectifying elements are connected to each other, and a first series circuit of a discharge resistor and a discharge control rectifying element is connected between the cathodes of both of the rectifying elements and the opposite side of the power source, and each of the above power controls is performed. A second and a third series circuit including a series resistor and a voltage detection means are connected between each input terminal of the device, and each of the voltage detection means detects the voltage of each of the capacitors to determine the output of each of the power control devices. The anodes of the third and fourth rectifying elements are connected between the voltage detecting means and the series resistors of the second and third series circuits, respectively, and the cathodes are connected to the discharge control rectifier. A protection device for a power control device, characterized in that it is connected to an anode of an element. 2. The protection device for a power control device according to claim 1, wherein the series resistor is divided into two, and the anodes of the third and fourth rectifying elements are connected from the dividing point, respectively. 3. The protection device for a power control device according to claim 1 or 2, wherein the switch is released when the voltage detected by the voltage detection means disappears.