JPS60200768A - Semiconductor rectifier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a semiconductor rectifier, and more particularly to a semiconductor rectifier using a self-extinguishing semiconductor.

[Background of the invention]

FIG. 1 shows an example of a conventional self-arc-extinguishing semiconductor device. This circuit uses gate turn-off circuits (hereinafter referred to as GTO circuits) for diodes 1a to 1f.
2a to 2f are connected in antiparallel to form a three-phase bridge circuit.

This rectifier is capable of both forward conversion operation of converting alternating current to direct current and inverse conversion operation of converting direct current to alternating current.

In the case of forward conversion operation, if the conduction period of the GTO zyristors 23 to 2f is made zero, it becomes a three-phase diode bridge and can convert alternating current to direct current.

In the case of inverse conversion operation, DC power is generated by, for example, a DC motor 5 that generates an electromotive force, and is manually applied to a rectifier via a smoothing reactor 4 of an inverted filter and a ballast capacitor 3. As shown in FIG. 2, ()TO thyristor 23~
If 2f is turned on and off at a phase delayed by π from the power supply voltage efi˜eW, it is possible to operate with a power factor of approximately 1.0.

Furthermore, by using the so-called pulse width modulation method, which operates this rectifier at a frequency several times higher than the commercial frequency, the power supply power factor can be approximately 1.0, harmonics can be extremely reduced, and the DC voltage can also be controlled arbitrarily. It becomes possible.

However, the diodes 1a to 1f and the GTO thyristor 23
~2f are connected in antiparallel, so if, for example, GTO Zyristor 2a loses its forward blocking ability due to some abnormality, an antiparallel short-circuit current will occur in the path of power supply ev → diode IC- + GTO Zyristor 'l a- + power supply eH. However, there were drawbacks such as damage to the GTo thyristor and diode. Even if a protective fuse or the like was used here, the operation was slow and the protection of the element was not sufficient.

[Purpose of the invention]

An object of the present invention is to provide a highly reliable self-commutated rectifier that can reliably cut off fault current.

[Summary of the invention]

The present invention connects a semiconductor element with a controllable pole in anti-parallel to the GTO silice instead of a diode, and applies a wide gate pulse to the controllable ultra-fine semiconductor element so that it operates in the same way as a diode during normal operation. If an abnormality occurs in the GTO thyristor, the gate pulse is blocked and the fault current is cut off in one cycle, thereby preventing further spread of the fault.

[Embodiments of the invention]

FIG. 3 shows an embodiment of the present invention. This self-excited rectifier is constructed by connecting controllable pole semiconductor devices 8a to 8f and self-extinguishing semiconductor devices 2a to 2f in antiparallel.

During the forward conversion operation, a wide pulse of 120 electrical degrees is applied to the semiconductor elements 8a to 8f with controllable poles to operate like diodes, and the conduction period of the GTO thyristors 2a to 2f is made zero.

On the other hand, in the case of inverse conversion operation, the controllable pole semiconductor elements 8a-
By applying a wide pulse of 360 electrical degrees to 8f and turning on and off the GTO thyristors 2a to 2f at arbitrary points of the power supply voltage, the power factor can be controlled arbitrarily.

It goes without saying that harmonic subcurrents can be reduced by pulse width modulation as in the conventional embodiment.

Since the rectifier of the present invention uses a semiconductor element with controllable poles, it can easily cut off fault current. That is, if a short circuit occurs on the DC side, it is naturally possible to attenuate the fault current by shifting the gate and returning the fault current to the circuit, similar to the three-phase bridge with controllable poles.

Furthermore, even if one or more of the GTO Zyristors 23 to 2f loses forward control blocking ability and causes an anti-parallel short circuit, if the controllable pole semiconductor devices 8a to 8f are gate blocked, one cycle can be achieved. Can cut off anti-parallel short circuit current. That is, assuming that the GTO thyristor 2a has lost its forward control blocking ability, the controllable pole semiconductor element 8C is given a wide gate pulse of %i electrical angle of 360 degrees, so that the source ev→controllable pole Semiconductor element 1c→G
An antiparallel short-circuit current is caused to flow through the TO thyristor 2a-+power source eu. Here, if 80 is not a semiconductor device with controllable poles but a diode IC, as shown in FIG. 4, the antiparallel short-circuit current does not turn off even after one cycle, and a sustained current continues to flow as shown by the dotted line. However, in the case of the semiconductor device 8C with controllable poles, the current is transferred to current transformers (7a and 7
If the gate pulse generated by the control circuit 6 is blocked, the semiconductor element 8c with a controllable pole will be in the off state during the reverse voltage period, and then the forward bias Even if it is, the continuous power 61f' does not continue and is cut off.

Therefore, destruction of other elements can be prevented.

FIG. 5 shows an example of application of the present invention. The self-excited rectifier is configured by anti-parallel connections of diodes 1a to 1f and GTO zyristors 2a to 2f, which is the same as the conventional example, but semiconductors with controllable poles are used to suppress DC short-circuit current and cut off anti-parallel short-circuit current. A device in which elements 9a to 9f are connected in antiparallel is inserted into each phase line of a power supply and used as a Zyristor switch.

The self-commutated rectifier is operated as described in the prior art.

During normal operation, the Zyristor switch is operated with wide pulses of 360 electrical degrees. However, DC short circuit or (JT
When an antiparallel short circuit occurs due to loss of forward blocking ability of the O thyristors 2a to 2f, the detection signals from the current transformers 7a and 7b block the gate pulse of the control circuit 6, and the fault current is cut off within one cycle. , prevent spillover accidents such as element destruction.

〔Effect of the invention〕

According to the present invention, even if the stain flow suddenly increases due to some abnormality, the feed current can be cut off within one cycle.
Subsequent spread of accidents such as element destruction can be reliably prevented.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional self-excited rectifier, Figure 2 is a diagram showing forward conversion, inverse conversion, and voltage and current waveforms during pulse width modulation operation of the self-excited rectifier. One implementation Ij
Figure 4 is a diagram showing the current waveform at the time of anti-parallel short circuit.
FIG. 5 is a circuit diagram of an application example of the present invention. 1a to 1f...Diode, 2a to 2f...Self-extinguishing semiconductor element, 3...Ballast capacitor, 4...
・Smooth reactor nope 5...DC intoxicant, 6...
Control circuit, 7a, 7b=-・Current transformer, 8 a to 8 f
, 9a to 9f,,. Semiconductor device with controllable poles. Agent Patent Attorney Tatsuyuki Unuma Sen1 Zutei 2 Artwork r° Nugo/'ゝ- Ward 3

Claims (1)

[Claims] 1. In a semiconductor rectifier that converts alternating current and direct current in forward and reverse directions by connecting arms in which a semiconductor element with a controllable pole and a GTO Zyristor are connected in inverse parallel to each other in a bridge manner, a gate pulse is applied to the excitation pole of 1b11. Equipped with a control circuit that outputs an output, and a relay circuit that detects overcurrent in the AC power source and transmits abnormalities to the control circuit,
When an overcurrent flows in the power line due to the o'ro zyristor losing its forward blocking ability, the transformer ε11 detects it;
A semiconductor tube flow device characterized in that the gate pulse of the r11 elevation circuit is blocked. 2. Diodes and GTO thyristors: In a semiconductor rectifier that converts forward and reverse AC and DC by connecting arms connected in reverse parallel to each other in a bridge, an arm in which semiconductor cords with controllable poles are connected in reverse parallel is connected to each AC source line. Equipped with a control circuit that is connected in series and outputs gate pulses to their control poles, and a current transformer that detects overcurrent in the AC power line and transmits the abnormality to the control circuit, GTO Cyrisk loses its forward blocking ability. A semiconductor rectifier characterized in that when an overcurrent flows in a power source line, a current transformer detects it and blocks a gate pulse of a control circuit.