SU1169113A1 - Device for forced switching of thyristor converter - Google Patents

Abstract

A TIRISTOR TURISTOR EQUIPMENT DEVICE, containing a diode bridge with a filter capacitor, two series-connected switching thyristors, two series-connected charging thyristors, two series-connected discharge diodes, a switching circuit from a series-connected switching thyristor, and switching capacitors, backdaptores; connections of commuting thyristors and to joint common points of connection of charge thyristors discharge diodes, two series-connected reset diodes, characterized in that, in order to increase reliability by reducing switching overvoltages, two additional diodes are connected to it, connected by the same anode and cathode, respectively, to the positive and negative output terminals of the diode bridge with filter capacitor, and the other anode and cathode to the same terminals of the reset diodes, and an additional capacitor connected by its outputs to the common points of connection of the isolating diodes and the diode s reset, wherein (A total point reset compounds diodes connected to a common junction point of switching the reactor and the condenser, and the corresponding terminals and commuting thyristors dnyh charge and discharge diode connected to the output terminals of the diode bridge with the filter capacitor. O5 WITH co: / 5

Description

The invention relates to a converter technique and can be used for artificially switching thyristors in frequency converters.

The purpose of the invention is to increase reliability by reducing switching overvoltages.

FIG. 1 is a schematic diagram of the proposed device; in fig. 2 shows current and voltage diagrams of a switching capacitor.

The device (Fig. 1) contains a thyristor converter 1 with a transformer and a load ZH, a diode bridge 2 with a filter, the buses of which are connected to the terminals of two series-connected switches, their thyristors 3 and 4, and charge thyristors 5 and 6, shunted counter-parallel discharge diodes 7 and 8, sequentially connected switching capacitor 9 and reactor 10, connected to common points of connection of switching thyristors 3 and 4 and charge thyristors 5 and 6, two series-connected diodes 11 and 12 of reset, which unite diodes 13 and 14, connected by anode and cathode to the output buses of diode bridge 2. The same terminals of diodes 11 and 13 and diodes 12 and 14 are interconnected, an additional filter capacitor 15 is connected to common points of connection of cathodes of diodes 11 and 13 and anodes of diodes 12 and 14. The diverting diodes 13 and 14 are shunted by thyristors 16 and 17 of the fault. The output of the forced switching device is connected to the thyristor converters 1 via distribution. Chiristors 18 and 19.

The device for switching the thyristors of the converter (Fig. 1) according to the voltage and current diagrams (Fig. 2) works as follows.

Suppose that two thyristors of opposite groups of converter 1 are initially conducted, a current of 1 c flows through the load circuit, and the capacitor 9 is charged before the voltage of the filter of diode bridge 2 with the polarity indicated in FIG. 1. To lock one of the thyristors of the cathode group of converter 1 (at time tj) turn on thyristors 3 and 18. The load current from the conducting thyristor of converter 1 is displaced by the oscillating current of the LC circuit along the circuit: 1, 2, 3, 9, 10 , 18, 1. The excess current of the recharging of the capacitor 9 is closed along the circuit: 9, 10, 7, 3, 9, creating a voltage drop in the circuit of diode 7, plus applied through the distribution thyristor 18 to the cathode, and minus - through the diode bridge 2 - to the anode of the lockable thyristor. In this case, the voltage drop must be greater than the open state of the thyristor 18, for which in the circuit of the discharge diodes 7 and 8 is included

several valves connected in series. Until the time t of the load current of the LC circuit exceeds the current, the free recharge of capacitance 9 continues. The voltage Ug changes sign. At time it, discharge diode 7 is closed. In the time interval tg-i, a load current flows through the LC circuit, linearly increasing the voltage U9 on the capacitor 9. At the time tj, the voltage Uj exceeds the voltage of the additional capacitor 15 equal to the voltage Uz of the diode bridge filter 2 , the corresponding cathode thyristor opens

5 converter 1, the load current of the converter is closed through the aforementioned thyristor, diodes 7, 12 and 13 are opened and the excess energy of the reactor 10 is transferred to the capacitor 15 through a circuit: 10, 7, 13, 15, 12, 10. As the capacity of the additional filter capacitor 15 is much greater than the capacitance of capacitor 9, then we can assume that the voltage on the capacitor 15 during the time of the excess energy output is constant over time;

5, the current of the reactor 10 decreases linearly (Fig. 2).

Thus, in the process of switching thyristors, the voltage converter on the switching capacitor is set no higher than the supply voltage, which increases the reliability of the thyristors and reduces the weight and size parameters of the device.

The accumulated in the process of switching the excess energy from the additional

5 of the capacitor 15 is output by known methods, for example, turning on the thyristors 16 and 17, reset (Fig. 1) and transferring this energy to the main filter of the diode bridge 2 at the inter-switching interval and then using it for switching.

At the moment in time is the process of switching the thyristors of the anode group of the converter 1 begins, similarly to the described process.

5 Through charge thyristors 5 and 6, the charge of switching capacitor 9 is performed after each switching by switching on the corresponding pair of thyristors 5 and 4 or 3 and 6 when the converter is in idling mode.

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 The thyristors of the thyristor forced switching device of the converter are controlled by means of a control unit that generates signals that are applied to the control electrodes of the corresponding thyristors according to the described algorithm.

As a converter 1 in the device (Fig. 1), a known AC / DC converter (adjustable rectifier) is adopted, control systems for such converters, such as a phase control system, are also well known. In the control unit of the proposed device for switching and distributing thyristors, control signals are generated on the falling edges of the thyristor control pulse 1 (the duration of such a control pulse corresponds to the entire duration of the thyristor conducting state) using a short pulse former. For charge thyristors, control pulses are generated, which are delayed relative to the mentioned pulses for the duration of the switching interval by means of single vibrators.

Claims (1)

CONVERTER THYRISTOR FORCED COMMUNICATION DEVICE, comprising a diode bridge with a filter capacitor, two series-connected switching thyristors, two series-connected charging thyristors, two series-connected discharge diodes, a switching circuit from a series-connected switching reactor and a switching capacitor connected to a common point connected by its terminals thyristors and to the combined common points of connection of charging thyristors and discharge diode diodes, two series-connected reset diodes, characterized in that, in order to increase reliability by reducing switching overvoltages, two decoupling diodes connected to the plus and minus outputs of the diode bridge with a filter capacitor, respectively, are additionally introduced into it; other anode and cathode to the same terminals of the reset diodes, and an additional capacitor connected with its findings to the common connection points of the decoupling diodes and reset diodes, when it common point compounds reset diode connected to a common junction point of switching the reactor and the condenser, and the corresponding terminals and switching the charging thyristor and the discharge diode connected to the output terminals of the diode bridge with the filter capacitor. SU ,,, 1169113