JPS5937616B2 - Semiconductor circuit breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new type of current-limiting semiconductor breaker using a reverse conducting thyristor as a switching element.

Reverse conducting thyristor 1 as a conventional switching element shown in Fig. 1
A semiconductor breaker using 6-1-1 has the advantage that it is easier to obtain a high-speed switching thyristor with a large current and high withstand voltage, compared to one using a thyristor.

When a fault current due to a short circuit or the like flows through the main circuit, the semiconductor circuit breaker detects this fault current with a current transformer 2, and when this detected value exceeds a set value, it is transmitted to the control circuit 12 and reverse conducting thyristor 16-1 When the gate signal of the thyristor section -1 is stopped, the gate signal is supplied to the auxiliary thyristor 17, and the reverse current from the commutation circuit is supplied to the thyristor section of the reverse conduction thyristor 16-1i, thereby cutting off the fault current. He followed a method.

If this method is used, inside the element of the reverse conduction thyristor 16-1-1, the diode section connected in antiparallel to the thyristor will be in the forward direction with respect to the applied voltage polarity of the commutation circuit that supplies reverse current. The defect is that a large current flows in the diode part, where the fault current from other phases flows, and in the thyristor part, because the reverse current is superimposed on the diode part as a forward current. there were.

However, in a general reverse conduction thyristor, the rated surge current per cycle of the diode section is smaller than that of the thyristor section, and the selection of elements is complicated because sufficient consideration must be given to the surge current withstand capacity.

Furthermore, since the charge in the capacitor of the commutation circuit escapes through the diode section, it is necessary to reserve a large charge to account for this amount.

In order to eliminate the above-mentioned drawbacks, the present invention reverses the connection of the reverse conduction thyristor to prevent reverse current from flowing into the diode section, and provides a semiconductor breaker that has a large surge current withstand capacity, facilitates the selection of elements, and performs reliable breaker operation. The purpose is to provide

The present invention will be explained below with reference to the drawings.

In the figure, 1 is a three-phase power supply, 2 is a current transformer, 2-1 is an R-phase current transformer, 2-
2 is an S-phase current transformer, 2-3 is a T-phase current transformer, 3 is a breaker,
3-1 is an R-phase breaker, 3-1-1 is a reverse conduction thyristor, 3-1-2 is a beam axle, 3-2 is an S-phase breaker, 3
-3 is T-phase breaker, 4 is 3-phase load, 5 is auxiliary thyristor, 5-1 is R-phase auxiliary thyristor, 5-2 is S-phase auxiliary thyristor, 5-3 is T-phase auxiliary thyristor, 6 is auxiliary diode , 6-1 is an R-phase auxiliary diode, 6-2 is an S-phase auxiliary diode, 6-3 is a T-phase auxiliary diode, 7 is a current-carrying current separation detection circuit, γ-1 is an R-phase conducting current polarity detection circuit, 7-2 is an S-phase current polarity detection circuit, 7-3 is a T-phase current polarity detection circuit, 8 is a surge absorption circuit, 8-1 is a capacitor, 8-2 is a discharging resistor, 9 is a charging resistor, 10 is a charging circuit, 10-1 is a charging capacitor, 10-2 is a discharging resistor, 11 is a short-circuit current detection circuit, 12 is a control circuit, 13 is a single-phase full-wave rectifier, 13-1 to 13-4 are diodes, 14
is the auxiliary transformer, 14-1 is the auxiliary transformer primary winding, 14-
2 is an auxiliary transformer secondary winding, and 15 is an auxiliary power supply.

Next, the operation of the above configuration will be explained.

Pass the charging resistor 9 from the auxiliary power supply 15, and then the auxiliary transformer 1
4 to an appropriate value, and the single-phase full-wave rectifier 13 converts the alternating current to direct current to charge the charging capacitor 10-1.

The current in the main circuit is detected by a current transformer 2, and the polarity of each energized current is detected by a polarity detection circuit 7 for each energized current.

The conducting polarity is a circuit that detects the conducting polarity of the diode portion of the reverse conducting thyristor.

Short circuit current detection circuit 11 indicates that a short circuit failure has occurred in control circuit 1.
2, the supply of the gate signal to the reverse conduction risk is immediately stopped, and furthermore, a signal is sent from the control circuit 12 to the current flow isolation detection circuit 7.

The current separation property detection circuit 7 takes the AND signal of this signal and the diode part energization signal of the reverse conduction thyristor, and calculates this A
A gate signal is supplied to the corresponding auxiliary thyristor 5 only for the phase in which the ND signal is at the "1" level.

The main circuit current is supplied from a three-phase power supply 1 to a three-phase load 4 through a current transformer 2 and a breaker 3 .

If a short circuit fault occurs now, reverse conducting thyristor 3-1
-1.3-2-1.3-3-1 Only the polarity of the energized diode portion is detected by the energization current separation detection circuit 7, respectively.

Auxiliary thyristor 5-1, 5-2.5-3 corresponding to this
A gate signal is supplied to one of them to turn it on, and the charged charge of the charging capacitor 10-1 supplies a reverse current to the diode section of the reverse conduction thyristor which is energized.

Since the auxiliary thyristor of the energized thyristor section of the reverse conduction thyristor is off, no reverse current is supplied.

However, since a reverse current is supplied to all of the energized diode sections, the fault current is cut off, and the current in the thyristor section of the energized reverse conduction thyristor becomes less than the holding current and is turned off.

As described above, the present invention supplies a reverse current to the energized diode section to cut off the fault current, thereby reducing the current in the energized thyristor section to less than the holding current of the thyristor, thereby eliminating the fault current. .

In the case of the present invention, unlike the conventional method, the reverse current from the commutation circuit side is not superimposed in the forward direction of the current-carrying side diode section (it can also be used with a reverse conduction thyristor having a diode section with a small surge current capacity). It is.

A reverse conduction thyristor can be selected by considering only the magnitude of the fault current and its current limiting start value, making selection easy.

Furthermore, since only reverse current flows through the diode section, the first
As shown in the figure, there is an advantage that the reverse current can be used very effectively without flowing a forward current.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional semiconductor breaker, and FIG. 2 is a circuit diagram showing an embodiment of the semiconductor breaker of the present invention. 1... 3-phase power supply, 2... current transformer, 3...
..... Breaking section, 3-1-1 .... Reverse conduction thyristor, 4 .... 3-phase load, 5 ..... Auxiliary thyristor, 6 ....・Auxiliary diode, 7...
.... Current flow separation detection circuit, 9... Charging resistance, 10%... Charging circuit, 11... Short circuit current detection circuit, 12...・Control circuit, 14...
...Auxiliary transformer, 15...Auxiliary power supply.

Claims (1)

[Claims] 1 Connected between the power supply of the main circuit and the load, it consists of a thyristor part and a diode part connected in antiparallel, and normally a gate signal is applied to the thyristor part to turn it on and supply power to the load.Reverse conduction A thyristor, a current transformer that detects a fault current when it flows in the main circuit, a circuit that issues an output signal when the fault current value exceeds a set value by this current transformer, and a circuit that generates an output signal by this output signal. A semiconductor circuit breaker, which is connected in a forward direction with respect to a power source, and a control circuit that operates to stop the gate signal of the thyristor section, turn off the thyristor section, and stop supplying power to the load. a detection circuit that detects the polarity of the fault current flowing through the reverse conduction thyristor diode section and generates an output signal when the detected value matches the conduction polarity of the diode section of the reverse conduction thyristor; A semiconductor breaker comprising: a circuit that supplies a reverse current to the reverse conduction thyristor diode section and stops a gate signal of the reverse conduction thyristor thyristor section.