SU1164833A1 - Device for damping switching surge of converter - Google Patents

Abstract

A DEVICE FOR DAMPING OF SWITCHING OVERVOLTAGES OF THE CONVERTER, containing damping units, including resistors and chains of series-connected capacitors and series-connected double-sided voltage suppressants, characterized in that, in order to reduce losses, the points, too, the points, the points, also, the points, also, the points, also, the points will have, and the points, which also have to be at the same time, the points will have, and the points will be at the same point, if the point will be the same, and the point will be in the way, the point will be the same, the point will have, the point will be the same, the point will be the same, the point will be the same, the point will be the same, the point will be the same, the point will be the same, the point will be the same, the point will be the same, the point will be the same, the point will be the same, the point will be the same, and the point will be the same, should be, that should be, should be, should also be, should be at the same time, will be at the same point and should have that, should be, should be, the same,,,,,,, in the between the voltage limiters.

Description

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The invention relates to electrical engineering and is intended to prevent abrupt voltage changes on converter valves during switching processes.

Devices for damping switching overvoltages on converter valves are known, which contain RC circuits made on line resistors and capacitances II.

The disadvantages of these devices are the large losses in the resistors when recharging de-capacitors of RC circuits with the mains frequency, as well as the impossibility of limiting the rate of increase of the voltage on the converter valves to satisfactory values.

Closest to the present invention is a device for damping switching overvoltages, containing resistors and parallel chains of series-connected capacitors and series-connected double-sided voltage suppressors 2.

A disadvantage of the known device is also greater losses in nonlinear resistors of RC circuits during recharging of capacitances with a network frequency, which constitute a large part of the total losses in RC circuits.

The purpose of the invention is to reduce losses.

The goal is achieved by the fact that in a device for damping switching overvoltages of a converter containing damping blocks including resistors and parallel chains from series-connected capacitors and series-connected double-sided voltage suppressors, the points of the capacitors are connected to each other through resistors to the points of connection between the voltage limiters.

The drawing shows a functional diagram of the device.

A device for damping switching overvoltages, on converter converter 1 valves, contains damping blocks 2, made in the form of chains of series-connected capacitors 3 and two-way voltage limiters 4, interconnected by resistors 5

and connected to the phases of the transformer 6 connected to the input of the converter 1 by a star or a triangle (damping blocks can also be connected in parallel to the valves of the converter 1).

The device works as follows.

When switching the converter valves, the corresponding phase windings of the transformer 6 are closed together. By the time the valves are turned off, the dissipation inductors of the phase windings of the transformer 6 accumulate energy, which leads to overvoltages on the switching off valve. A chain of capacitors 3 is made up of capacitors of different capacities. In this case, the voltages on the capacitors 3 are distributed inversely proportional to their capacitances, with the highest voltage being on the capacitor having the lowest capacitance. If the voltage on the chain of capacitors 3 is small (i.e., less than the total avalanche voltage of the bilateral voltage limiters 4, which is chosen to be greater than the linear voltage of the transformer 6), then the equivalent capacitance of the chain is equal to the capacitance of all series-connected capacitors 3. With increasing voltage on the line of the linear voltage of the transformer 6, the voltage across the capacitor 3 with the minimum capacitance reaches through the resistor 5 the limiter 4, at. In this way, this capacitor ceases to rust, and the capacitance of the chain is determined by the smaller number of series-connected capacitors. 3, having a large capacity. Consequently, with an increase in voltage on the capacitor chain 3, its capacitance increases. The law of increase in the capacitance of the chain (s) is determined by the choice of the capacitors of the individual capacitors of the 3 chain. By appropriate selection of the law (U), it is possible to limit the amplitude and rate of increase of voltage on the converter 1 valves with a predetermined value. Since the resistors 5 are not included in the circuit for recharging capacitors 3. with a network frequency, they can only be selected from energy 3, switching overvoltages, which are significantly less than the energy for recharging capacitors 3 with a network frequency. Moreover, the energy of these switching overvoltages is not made on a single resistor, but is distributed between all the resistors 5 and the A-voltage limiters. Thus, due to the fact that the chains of capacitors and voltage limiters with different division factors and device impedance turns out to be dependent on the applied voltage, at a certain voltage level the device impedance becomes purely capacitive, therefore at this voltage level and below it the active losses and in the device are absent, which allows to reduce the total losses during the damping of switching overvoltages in the converter.

Claims (1)

A device for damping switching overvoltages of a CONVERTER, comprising damping units including resistors and parallel chains of series-connected capacitors and series-connected bilateral voltage limiters, characterized in that, in order to reduce losses, the connection points of the capacitors to each other are connected to the points through voltage limiters. smiling □ About CO 1 1 1