JPH0442769A - On-condition judging device for semiconductor breaker - Google Patents

Abstract

PURPOSE:To directly judge the on condition of a semiconductor breaker by providing it with a forward converter, whose input side is connected to an AC source through an insulated transformer and whose output side is connected in parallel with the semiconductor switch element of a semiconductor breaker, and a means, which is positioned on the AC side of the insulated transformer and judges whether or not the close circuit is formed by the forward converter and the semiconductor switch element. CONSTITUTION:In the case that a GTO thyristor 2 is in on condition, a current flows to the close circuit composed of a single bridge rectifying circuit 8, a resistor 9, a reverse flow checking diode 10, and said GTO thyristor 2. According to this, a load current flows to the primary side of an insulated transformer 7, and it is detected by a current detector 6. In case that the GTO thyristor 2 is in off condition, a current does not flow to the primary side of the insulated transformer 7, either. By detecting the current, which flows to the primary side of the insulated transformer 7, with a current detector 6, whether or not the high voltage of a DC power source 1 is applied to the GTO thyristor, the on condition or off condition of the GTO thyristor 2 can be judged.

Description

Detailed Description of the Invention [Purpose of the Invention (Industrial Application Field) The present invention is directed to the conduction state of a semiconductor circuit breaker installed as a protection device for a VVVF (Variable Voltage Variable Frequency) inverter that inputs DC power. Regarding a discrimination device.

(Prior Art) Semiconductor disconnection devices using semiconductor switching elements have been put into practical use for switching load current input to a VVVF inverter from a high-voltage DC power supply for electric railways and interrupting fault current. Conventionally, the conduction or non-conduction state of this semiconductor cut-off device has been determined indirectly based on the gate signal of the semiconductor switch element.

(Problems to be Solved by the Invention) In the case of conventionally used mechanical circuit breakers, the conduction state of the circuit breaker could be reliably determined based on the open/closed state of the auxiliary contact position that interlocks with the main contact. Determining the conduction state of the circuit breaker is very important in detecting malfunction of the circuit breaker.

In a semiconductor circuit breaker, the conduction state of the semiconductor circuit breaker is indirectly determined based on a gate signal of a semiconductor switch element.

Therefore, when no voltage is applied to the semiconductor switch element of the semiconductor circuit breaker, or when the semiconductor switch element is broken and becomes conductive, the gate signal command and the conduction state of the semiconductor switch element do not match. In this way, indirectly determining the conduction state of the semiconductor circuit breaker from the gate signal has a problem in that the reliability of the determination accuracy is low.

The present invention was made in order to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a conduction state determination device for a semiconductor circuit breaker that can directly determine the conduction state of a semiconductor circuit breaker. It is said that

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention has an input side connected to an AC power source via an isolation transformer, and an output side connected in parallel with a semiconductor switching element of a semiconductor circuit breaker. The present invention is characterized in that it includes a forward converter connected to the insulating transformer, and means for detecting whether a closed circuit is formed by the forward converter and the semiconductor switch element, which is provided on the AC side of the isolation transformer.

(Function) In the device configured as described above, when the semiconductor circuit breaker is in a conductive state, the self-extinguishing semiconductor switch element is in a conductive state. At this time, the alternating current supplied from the alternating current power source is converted into direct current by a forward converter via an isolation transformer. Then, the DC current output from the forward converter flows through a closed circuit composed of the forward converter, the reverse current blocking diode, and the self-extinguishing semiconductor switching element.

When the semiconductor circuit breaker is in a non-conducting state, the self-arc-extinguishing semiconductor switch element is in a non-conducting state.

Therefore, no direct current flows through the closed circuit. therefore,
It is possible to determine the conduction state of the semiconductor circuit breaker by detecting the direct current flowing in the closed circuit on the secondary side of the isolation transformer with a detector.

Note that the reverse current blocking diode prevents the high voltage current of the DC power supply from flowing into the forward conversion circuit when the semiconductor circuit breaker is in a non-conducting state.

(Example) The configuration of an embodiment of the present invention will be explained with reference to FIG.

1 is a DC power supply for electric railways, which supplies power to a VVVF inverter 4 through a semiconductor circuit breaker composed of a GTO thyristor 2, which is a self-extinguishing semiconductor switching element, and a diode 3 connected in antiparallel to the GTO thyristor 2. supply

Reference numeral 5 denotes a single-phase AC power supply, which is connected to the primary side of the isolation transformer 7 via a current detector 6. A single-phase bridge rectifier circuit 8 is connected to the secondary side of the isolation transformer 7. The single-phase bridge rectifier circuit 8 performs full-wave rectification on single-phase AC power and outputs DC power. The output side of the single-phase bridge rectifier circuit 8 is connected in series with a resistor 9 and a reverse current blocking diode 10 inserted to limit the flowing current. This series circuit is connected in parallel to the semiconductor circuit breaker. The backflow blocking diode 10 is G
This is provided to prevent current from flowing into the single-phase bridge rectifier circuit 8 when the TO thyristor 2 is in the OFF state and high voltage is blocked.

The operation of the embodiment configured in this way will be explained.

Now, when the GTO thyristor 2 is in a conductive state, the single-phase bridge rectifier circuit 8, the resistor 9, and the reverse current blocking diode 10
, a current flows through a closed circuit composed of the GTO thyristor 2. In response, a load current flows through the primary side of the isolation transformer 7, and the current detector 6 detects this current.

Further, when the GTO thyristor 2 is in a non-conductive state, the above-mentioned closed circuit is not formed and no current flows from the single-phase bridge rectifier circuit 8. Therefore, no current flows to the primary side of the isolation transformer 7 either.

In this way, by detecting the current flowing to the primary side of the isolation transformer 7 with the current detector 6, the current of the GTO thyristor 2 is detected regardless of whether the high voltage of the DC power supply 1 is applied to the GTO thyristor 2. A conductive state or a non-conductive state can be determined.

The configuration of another embodiment of the present invention will be explained with reference to FIG.

Single-phase AC power supply 5 is connected to the primary side of isolation transformer 7 via resistor 11 . Further, a voltage detector 12 for detecting the primary side voltage of the isolation transformer 7 is connected. and,
The single-phase bridge rectifier circuit 8 is connected in series with a reverse current blocking diode 10, and this series circuit is connected in parallel with a semiconductor circuit breaker.

The operation of another embodiment configured as described above will be described below.

When the GTO thyristor 2 is in a conductive state, a closed circuit is formed by the single-phase bridge rectifier circuit 6, the reverse blocking diode 10, and the GTO thyristor 2 on the secondary side of the isolation transformer. The next side has low impedance. Therefore, the primary side of the isolation transformer 7 also has low impedance, and the primary side voltage becomes low. This voltage value is detected by a voltage detector 12. The resistor 11 is provided to limit the current flowing when the GTO thyristor 2 is conductive.

Next, when GTO thyristor 2 is in a non-conducting state,
Since the aforementioned closed circuit is not configured, the secondary side of the isolation transformer 7 has high impedance. Therefore, the isolation transformer 7
The primary side of the AC power source 5 also has high impedance, and the primary voltage exhibits approximately the same value as the voltage value of the single-phase AC power supply 5. This voltage is detected by a voltage detector 12.

In this way, by detecting the voltage generated on the primary side of the isolation transformer 7 with the voltage detector 12, the conduction state of the GTO thyristor 2 can be determined. In this way, effects similar to those of the embodiment described above can be obtained.

In addition, by inserting a relay in place of the resistor 11, the GTO
A similar effect can also be obtained by attracting the relay with the current flowing to the primary side when the thyristor 2 is in a conductive state.

[Effects of the Invention] According to the present invention, the conduction state of the semiconductor circuit breaker is directly determined based on whether or not the current supplied from the independent AC power supply passes through the semiconductor circuit breaker. It is possible to accurately determine the conduction state of a semiconductor circuit breaker, and it is possible to provide a highly reliable conduction state determination device for a semiconductor circuit breaker.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...DC power supply, 2...GTO thyristor, 3...Diode, 4...VVVF inverter, 5...Single-phase AC power supply, 6...Current detector, 7
... Isolation transformer, 8... Single-phase bridge rectifier circuit, 9... Resistor, 10... Backflow blocking diode, 11... Resistor, 12... Voltage detector. Agent Patent Attorney Noriyuki Chika Figure 1

Claims (1)

[Claims] A forward converter whose input side is connected to an AC power source via an isolation transformer and whose output side is connected in parallel to a semiconductor switching element of a semiconductor circuit breaker; A conduction state determination device for a semiconductor circuit breaker, which includes means for detecting whether a closed circuit is formed by a converter and a semiconductor switch element.