JPH0638542A - Protective circuit for inverter system - Google Patents

Abstract

PURPOSE:To suppress the rise of an accident current by reducing the size and weight of a filter reactor of an inverter system. CONSTITUTION:An inverter system supplies DC power from a pantograph 2 to an inverter 4 through a high-voltage apparatus 3, and drives an induction motor 5 for driving a railway train by an AC output of the inverter 4, and comprises a current limiter 44 at an input stage of the inverter 4 to suppress the rise of a short-circuit accident current at the side of an inverter body 43 by positive characteristics of a temperature/electric resistor of he limiter 44. Thus, a filter reactor 41, may be enough of a low inductance necessary as an original filter element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection circuit for a railway vehicle drive inverter system.

[0002]

2. Description of the Related Art An electric motor for driving a railway vehicle employs an induction motor capable of achieving a brushless and large output, and an inverter system is used for its AC power source.

FIG. 2 shows a main circuit configuration of an inverter system for driving a railway vehicle. The DC power taken from the overhead line 1 through the pantograph 2 is a high-voltage equipment unit 3 having a high-speed circuit breaker, etc.
Is taken into the inverter unit 4 via the
The voltage is converted into three-phase AC power whose voltage and frequency are controlled by to drive the induction motor 5. A plurality of these inverter systems are provided in one drive vehicle to increase the output.

The inverter section 4 is a filter reactor 4 ₁
The filter capacitor 4 ₂ constitutes a pre-stage filter, and the inverter body 4 ₃ is constituted by a bridge configuration of semiconductor switches such as a GTO thyristor and its PWM control circuit.

In addition to the filter function, the filter reactor 4 ₁ is used as a fault current rise suppressing means when a DC short circuit fault occurs in the inverter body 4 ₃ or the like. By suppressing the rise of the accident current, the high voltage equipment section 3 can be operated without causing the operation of the circuit breaker of the substation on the ground due to the short circuit current.
It is possible to secure the power supply for other inverter systems, etc.

[0006]

The conventional protection circuit against a fault current requires a large-capacity filter reactor 4 ₁ due to the large capacity of the inverter body 4 ₃ etc., and the mass of the filter reactor is the square of the capacity. Since there is an increase in proportion to, there is a problem that the increase in capacity hinders weight reduction of the vehicle.

It is an object of the present invention to provide a protection circuit for reducing the size and weight of a filter reactor and suppressing the rise of a fault current.

[0008]

SUMMARY OF THE INVENTION The present invention is an inverter system for converting direct-current power taken from a pantograph to alternating-current power and supplying the same to an induction motor for driving a railway vehicle, in a direct-current power supply path from the pantograph to the inverter body. It is characterized in that it is provided with a current limiting element that is provided in series and has a positive temperature-electrical resistance characteristic, and suppresses the rise of the short-circuit fault current on the side of the inverter body by the current limiting element.

[0009]

[Function] By inserting a current limiting element having a positive characteristic between the pantograph and the inverter body, the rising of the short-circuit fault current on the inverter body side is suppressed by the current limiting element, and the filter reactor becomes an original filter. Make sure that you have the required low inductance.

[0010]

FIG. 1 is a main circuit diagram showing an embodiment of the present invention. 2 is different from FIG. 2 in that the filter reactor 4 ₁
Current limiting element 4 ₄ having a positive characteristic between temperature and electrical resistance in series with
There is a point.

Since the current limiting element 4 ₄ has a positive characteristic that its electric resistance increases as the temperature rises, when the fault current starts to flow due to a short-circuit accident on the inverter body 4 ₃ side, its resistance value increases due to its self-heating. As the resistance value rises, the temperature rises and the resistance value rises.

[0012] By intervening in the current limiting element 4 ₄ having such a positive characteristic, the rising slope of the fault current is gradual, i.e. the rise suppressing effect of fault currents can cause the rise suppression by the conventional filter reactor 4 ₁ No means needed.

Therefore, the filter reactor 4 ₁ can use one having an inductance (for example, 5 to 8 mH) required as a filter, and a small and lightweight filter element can be used for increasing the capacity of the inverter system.
In this respect, since the conventional one is used as a fault current rise suppressing means in addition to the filter element, a large inductance (for example, 10 to 12 m) is used for suppressing the rise.
H) is required, and the number of winding turns is doubled to 1.5.
You need double the capacity. This is 4 to 2.3 times the mass because the mass increases in proportion to the square of the capacity. In other words, in this embodiment, it is 1 compared with the conventional one.
A compact and lightweight filter reactor of / 4 to 1 / 2.5 will suffice.

Note that the current limiting element 4 ₄ has a temperature close to the temperature inside the vehicle during normal operation of the inverter, its resistance value is kept small, power loss is extremely small, and it is small in capacity and small in size and light in weight. become.

Further, by increasing the current-limiting characteristics of current limiting element 4 _4, the circuit breaker with the high-pressure equipment unit 3 can be relatively a slower ones.

In the embodiment, the case where the current limiting element 4 ₄ is provided in the input stage of the inverter unit 4 is shown, but this is configured to be inserted in series in the DC power supply path from the pantograph to the inverter body 4 _3. The same effect can be achieved.

[0017]

As described above, according to the present invention, in the inverter system for driving a railway vehicle, since the current limiting element having a positive characteristic is provided in series in the DC power supply path from the pantograph to the inverter main body, The fault current rise at the time of a short-circuit accident can be suppressed by a current limiting element, and the inverter system is smaller and lighter than the conventional rise reactor suppressor, which in turn reduces the size of railway vehicles.
The weight can be reduced.

[Brief description of drawings]

FIG. 1 is a main circuit diagram showing an embodiment of the present invention.

FIG. 2 is a main circuit diagram of a conventional example.

[Explanation of symbols]

1 ... overhead wire 2 ... pantograph 3 ... high-voltage equipment part 4 ... inverter part 5 ... induction motor 4 ₁ ... filter reactor 4 ₂ ... filter capacitor 4 ₃ ... inverter body 4 ₄ ... current limiting element

Claims (1)

[Claims] 1. An inverter system for converting direct-current power taken from a pantograph into alternating-current power and supplying the same to an induction motor for driving a railway vehicle, wherein temperature-electric resistance is provided in series in a direct-current power supply path from the pantograph to the inverter body. A protection circuit for an inverter system, comprising: a current limiting element having a positive characteristic, wherein the rising of a short-circuit fault current on the inverter body side is suppressed by the current limiting element.