JPH04289769A - Thyristor switch - Google Patents

Abstract

PURPOSE:To provide a thyristor unit wherein a firing capacitor can be charged even if there is no potential difference across a thyristor arm. CONSTITUTION:A thyristor arm 1 comprising a plurality of series connected main thyristors for feeding firing energy from a main circuit is provided for each phase. Firing circuit 5 for each main thyristor 1 is provided with a bilateral charging circuit 4 and an inter-phase capacitor 8 is connected to the way of the plurality of thyristors for each phase. Consequently, a potential difference is produced between the opposite ends of the thyristor arm 1 and the way thereof by means of the inter-phase capacitor 8 even if there is no potential difference across the thyristor arm 1 and thereby the firing circuit 5 can be charged. Furthermore, firing lag due to charging lag can be prevented through bilateral charging.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thyristor switching device for electric power, and more particularly to a thyristor switching device suitable for use even in locations where there is no potential difference between both ends of a thyristor arm.

0002

[Prior Art] In a device using a thyristor in a high voltage system, ignition energy is obtained using the voltage across the thyristor, and this ignition energy is supplied to the gate of the thyristor using a light pulse to activate the thyristor. A firing thyristor switchgear is used. A representative technique is the one shown in Japanese Patent Application Laid-Open No. 165659/1983, which uses an ignition capacitor for accumulating ignition energy whose accumulated energy exceeds a predetermined value. An auxiliary thyristor that is sometimes conductive is connected so that ignition energy is supplied from the ignition capacitor to the gate of the thyristor only when sufficient energy is stored in the ignition capacitor.

However, in such a circuit, if there is no potential difference between both ends of the thyristor arm, ignition energy for turning on the main thyristor cannot be obtained. For this reason,
When a thyristor switchgear is connected between the secondary bus bars of multiple transformers and the thyristor switchgear is turned on when the load on each transformer becomes unbalanced, the thyristor arm Since there is no potential difference between the two ends of the ignition energy, no ignition energy can be obtained. Furthermore, even if a potential difference occurs between both ends of the thyristor arm, the energy required for ignition can be stored in the ignition capacitor only when either positive or negative voltage is applied. There was a problem in that it took some time to charge the capacitor, causing a delay in ignition.

0004

[Problems to be Solved by the Invention] The present invention solves the above-mentioned conventional problems, and can charge the ignition capacitor even when there is no potential difference between both ends of the thyristor arm, thereby eliminating the ignition delay. It was completed in order to provide a thyristor switching device without

[0005]

[Means for Solving the Problems] The present invention, which was made to solve the above problems, supplies ignition energy from a main circuit in which a thyristor arm in which a plurality of main thyristors are connected in series is provided for each phase. The thyristor switching device is characterized in that a bidirectional charging circuit is provided in the ignition circuit of each main thyristor, and an interphase capacitor is connected midway between the plurality of thyristors of each phase.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to illustrated embodiments. In the circuit of Figure 1, 1 indicates each phase of the three-phase alternating current (
Each thyristor arm 1 has a plurality of main thyristors 2 for positive voltage and main thyristor 3 for negative voltage connected in series. Further, a thyristor ignition circuit 5 provided with a bidirectional charging circuit 4 is connected to each of the main thyristors 2 and 3, respectively. 6 and 7 are voltage dividing capacitors and snubber resistors which also serve as snubber capacitors and are connected in series between each thyristor. Further, 8 is an interphase capacitor connected in the middle of a plurality of thyristors forming the thyristor arm 1 of each phase. The interphase capacitor 8 is connected between the phases of each thyristor arm 1 by a Y connection or a Δ connection.

FIG. 2 shows a thyristor ignition circuit 5 in an embodiment. Moreover, FIGS. 3 to 5 show one of the thyristor ignition circuits 5 taken out. In the thyristor ignition circuit 5 of the embodiment, a snubber resistor 7 (R1) is provided between the anode and cathode of the main thyristor 2.
, a partial voltage capacitor 6 (C1) that also serves as a snubber,
A series body of diodes (D12) is connected in parallel, and a diode (D12) is connected between both poles of this diode (D12).
An ignition capacitor (C2) is connected in parallel via D31), and a charging control circuit is provided. This charging control circuit consists of voltage dividing resistors (R3), (R4), comparator (E), resistor (R2), and transistor (TR2).
), and the comparator (E) turns off the output when the ignition capacitor (C2) exceeds the triggerable voltage. Also, transistor (TR2)
When the comparator (E) turns off, current flows through the base and turns it on. This thyristor ignition circuit 5 operates to disconnect the charging circuit by the charging control circuit when the charging voltage of the ignition capacitor (C2) exceeds the triggerable voltage.

The bidirectional charging circuit 4 provided in the thyristor ignition circuit 5 includes a diode (D12), a capacitor (C4), and a diode (D22) connected in series.
A resistor (R6), a resistor (R7),
A series body of a Zener diode (ZD) and a bidirectional voltage switch diode (SBS) are connected in parallel, and a transistor (TR3) is provided. A bidirectional voltage switch diode (SBS) is equipped with the circuit shown in Figure 6. When a predetermined voltage is applied between A1 and A2 terminals, conduction occurs between A1 and A2, and when the current is reduced to 0, the circuit is turned off. It is what it is.

In the thyristor ignition circuit 5 equipped with the above bidirectional charging circuit 4, when a positive voltage is applied to the capacitor (C1), a current flows as shown by the arrow in FIG. (C2) is charged. Furthermore, when a voltage in the opposite direction is applied, current flows through the diode (D22) of the bidirectional charging circuit 4 and charges the capacitor (C4), as shown by the arrow in Figure 4, and the charging voltage becomes bidirectional. When the sum of the operating voltage of the voltage switch diode (SBS) and the breakdown voltage of the Zener diode (ZD) is reached, the bidirectional voltage switch diode (SBS) turns on and the transistor (TR3) also turns on. As a result, the potential difference between point e and point d becomes almost 0, and the capacitor (C4) is discharged as shown in FIG. 5, and the ignition capacitor (C2) is charged via the diode (D32). In this way, this circuit is capable of bidirectional charging.

0010

[Operation] Next, the operation of the thyristor switching device of the present invention will be explained. In FIG. 1, when the voltages VR1 and VR2 across the thyristor arm 1 are equal, the potential difference between the ends of the thyristor arm 1 is zero. However, since the interphase capacitor 8 is connected between the middle of the R-phase thyristor arm 1 and the middle of the S-phase thyristor arm 1, the potential at point A is the voltage VR1 divided by the voltage dividing capacitor 6 (C11), ( C1
2) The potentials are divided by the voltage division ratio of the interphase capacitor 8 (C). Therefore, VR1>0, VR2>0
When , R1 → C11 → C12 → as shown by the solid line
Current flows in the direction of C, R2 → C14 → C13 → C, and the thyristor firing circuits (G2), (G4), (G5
), (G7), and the ignition capacitors (C2) of the thyristor ignition circuits (G2), (G4), (G5), and (G7) are charged. Also, in order to charge the ignition capacitors of the thyristor ignition circuits (G1), (G3), (G6), and (G8), a voltage in the opposite direction is applied, but as described above, the bidirectional charging circuit 4 Since thyristor ignition circuits (G1), (G3), (
The ignition capacitors (C2) of G6) and (G8) will also be charged.

[0011] Also, VR1<0, VR2
When <0, contrary to the above, C → C12 → C11 →
Current flows in the direction of R1, C → C13 → C14 → R2, and the thyristor firing circuit (G1), (G3), (G6),
Since a forward voltage is applied to (G8), the thyristor firing circuit (G1), (G3), (G6), (G8
) each ignition capacitor (C2) is charged. Also,
Thyristor firing circuit (G2), (G4), (G5), (
G7) will be applied with a voltage in the opposite direction, but since the bidirectional charging circuit 4 is provided, the thyristor ignition circuits (G2), (G4), (G5), (G7)
The ignition capacitor (C2) will also be charged. After the ignition energy is stored in all of the ignition capacitors (C2) in this way, the phototransistor (PTR)
When a light pulse is applied to the phototransistor (P
TR) becomes conductive, and the transistor for gate signal amplification (T
R1) is also conductive, and the ignition energy of the ignition capacitor (C2) is supplied to the gates of main thyristors 2 and 3 through the transistor (TR1) and gate current limiting resistor (R5), and all main thyristors are 2 and 3 will be ignited.

0012

[Effects of the Invention] As explained above, the present invention can charge the ignition capacitor of the thyristor even if there is no potential difference between the two ends of the thyristor arm by connecting the interphase capacitor in the middle of the thyristor arm. . Moreover, in the present invention, a bidirectional charging circuit is provided in the thyristor ignition circuit so that charging can be performed with either a positive voltage or a negative voltage, so that ignition delay does not occur. Therefore, the present invention greatly contributes to the development of industry as a thyristor opening/closing device that eliminates the conventional problems.

[Brief explanation of the drawing]

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

FIG. 2 is a circuit diagram of a thyristor firing circuit.

FIG. 3 is a circuit explanatory diagram showing the charging state of the ignition capacitor when a forward voltage is applied to the thyristor ignition circuit.

FIG. 4 is a circuit explanatory diagram showing a state in which the ignition capacitor is not charged when a reverse voltage is applied to the thyristor ignition circuit.

FIG. 5 is a circuit explanatory diagram showing a state in which the ignition capacitor is charged when a reverse voltage is applied to the thyristor ignition circuit.

FIG. 6 is a circuit diagram of a bidirectional voltage switch diode.

[Explanation of symbols]

1 Thyristor arm 2 Main thyristor for positive voltage 3 Main thyristor for negative voltage 4 Bidirectional charging circuit 5 Thyristor firing circuit 6 Voltage dividing capacitor 7 Resistor for snubber 8 Interphase capacitor

Claims (1)

[Claims] Claim 1: In a thyristor switching device that supplies ignition energy from a main circuit in which a thyristor arm in which a plurality of main thyristors are connected in series is provided for each phase, a bidirectional charging circuit is provided in the ignition circuit of each main thyristor. In addition to providing
A thyristor switching device characterized in that an interphase capacitor is connected in the middle of a plurality of thyristors of each phase.