SU1163443A2 - A.c.voltage-to-d.c.voltage converter - Google Patents

Abstract

1. AC VOLTAGE CONVERTER TO PERMANENT by bus. St. No. 692036, characterized in that, in order to increase reliability, a series-connected switching capacitor and a thyristor are connected to it, connected in parallel to a smoothing choke, and the combined valve electrodes of one of the groups of the controlled bridge are connected to the thyristor electrode of the same name.

Description

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with

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Au 00 4 4i SB

2. The converter according to claim 1, characterized in that the charge circuit of the switching capacitor contains an external power source

one

This invention relates to a conversion technique and can be used as a controlled direct current source.

The purpose of the invention is to increase reliability.

The drawing shows a schematic diagram of the proposed Converter.

Input terminals 1-3 are connected to a three-phase AC source and primary windings 4-6 of a three-phase transformer, the secondary windings 7-9 of which are connected to an uncontrolled valve bridge with diodes 10-15. A load 16 is connected to the output of the bridge. A control valve bridge connected to the windings 4-6 is made on thyristors 17-22. The DC outputs of this bridge are shunted by a smoothing choke 23, in parallel with which are connected series-connected switching capacitor 24 k thyristor 25, cathode connected to the cathode group on thyristors 17, 19 and 21. The charge of switching capacitor 24 is supplied from an external power source, which contains the transformer 26, the secondary winding through the limiting resistor 27 of one branch and through the diode 28 of the other, connected to the switching capacitor 24. In some cases, to prevent overcharging A diode 29 can be used for the capacitor 24 by the reverse polarity voltage.

The device works as follows.

When an emergency mode occurs due to external and internal short circuits, the smoothing throttle current rises above the permissible values.

in the form of a transformer, the secondary winding of which is connected through the diode of the water branch and through a resistor in the other to the switching capacitor.

Suppose that an emergency mode occurs at a point in time when thyristors 17 and 20 are in a conducting state. If the smoothing throttle current rises above 5, the thyristor 25 receives a release signal from the control circuit (not specified) and the thyristor opens. Under the action of the voltage of the capacitor 24, which must be greater than the amplitude of the line voltage of the supply mains, a counter current flows through the conductive thyristors of the controlled bridge: thyristor 25, thyristor 17, primary winding 4, alternating current source with leads 1 -2, primary winding 5, thyristor 20. Counter-current growth rate

0 is determined by the dissipation inductance of the three-phase transformer and is much greater than the speed of the emergency current, which is determined by the inductance

5 smoothing throttling. When the opposite current is equal, the emergency thyristors 17 and 20 are closed, as a result of which the voltage converter is disconnected from the AC source.

After the thyristors of the controlled bridge are locked, the current flowing through the smoothing choke 23 begins to close through the thyristor 25 and

J capacitor 24, recharged last to opposite polarity. The time during which the voltage on the capacitor 24 exceeds the linear voltage applied to the thyristors 17 and 20 after they are turned on must be longer than the recovery time of the thyristor locking properties and is determined by the speed of the recharge of the capacitor 24 through the smoothing

5 choke 23. When the current drops drossel 23 to the tripping current of the thyristor 25, the capacitor 24 is disconnected from the power circuits of the converter; | l voltage and start recharging through transformer 26, resistance 27 idiom 28 up to the voltage required for switching power thyristors.

Claims (2)

1. CONVERTER OF AC VOLTAGE TO CONSTANT by ed. St. No. 692036, characterized in that, in order to increase reliability, a switching capacitor and a thyristor are connected in series, connected in parallel with a smoothing inductor, and the combined valve electrodes of one of the control groups 2. The converter according to π. 1, characterized in that the charge circuit of the switching capacitor contains an external power source in the form of a transformer, the secondary winding of which is connected through a diode of the water branch and through a resistor to another to the switching capacitor.