SU1288814A1 - Device for protection of transistor converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in frequency-controlled electric drives powered by static frequency converters when the converter is connected to a network with a grounded neutral. The aim of the invention is to increase the reliability of the converter, to increase it. In the event of a short circuit to ground of any of the converter outputs, the signal of the corresponding current sensor 6 or 7 turns on both short-circuit thyristors 11 and 12 and the short-circuit current passes through them, the inverter 3 transistors pass. The efficiency and overall dimensions are improved by eliminating transformer input transformer. 3 il. i (lu 00 00 00

Description

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The invention relates to electrical engineering and can be used in frequency-controlled electric drives powered by static frequency converters when the converter is connected to a network with a grounded neutral.

The purpose of the invention is to increase the reliability of the converter and improve the weight and size parameters.

FIG. 1 shows a diagram of a transistor converter with a device for protection; in fig. 2 - thyristor control unit; in fig. 3 - control pulses deactivation unit.

The device (Fig. 1) contains a rectifier 1, a DC link with a filter 2, a transistor inverter 3, a rectifier control unit 4 and an inverter control block 5, a current sensor 6 in the DC bus link negative current sensor 7 DC link, short-to-close thyristor control units 8 and 9, rectifier and inverter switch-off control pulses 10, short-circuit thyristors 11 and 12.

FIG. 2 shows a block diagram of the 8 (9) control of short-turn thyristors. It includes galvanically isolated from blocks 4 and 5 (see Fig. 1) power supplies of a current U,,, And, comparator 13, amplifier-shaper 14 with three galvanically developed outputs 15-17.

FIG. Figure 3 shows the circuit of the control pulses switching off unit 10 into which the direct current power source is supplied, and the current limiting resistor 18, the storage capacitor 19, the transformer 20, the trigger 21, the low-power thyristor 22.

The device works as follows.

In case of a short circuit to earth of one or several output terminals of the inverter at the moment when a signal from any of the current sensors 6 (7) (fig. 1) arrives at the input of the comparator 13 (fig. 2), block 8 (9) of the specified value the short-circuit current comparator 13 is triggered, the voltage at its output changes sign, as a result of which the amplifier-shaper 14 gene142

It draws pulses that are fed from inputs 15 and 17 to thyristors short circuit connectors 11 and 12 (Fig. 1), from output 16 to switching on a low power thyristor 22 (Fig. 3) of block 10. Thyristors 11 and 12 have a positive and negative busbar filter 2 are shorted to ground, with the result that the developing short-circuit current will flow through the following circuits: ground and - valve of the cathode group of the rectifier - positive DC link - thyristor 12 - ground and ground thyristor 11 - negative DC link - valve of anode group of rectifier and - earth, For example, the collector and emitter groups of the inverter have a transistor due to a significantly lower voltage drop across an open thyristor compared to an open transistor.

At the same time, when the low-power thyristor 22 (Fig. 3) is turned on by impulses coming from the output of 16 blocks B and 9, the storage capacitor 19 is discharged to the primary winding of the transformer 20. The pulse formed on the secondary windings of the transformer 20 turns off the inverter transistor control pulses of the inverter in the block 5 and switches the flip-flop 21 to a state in which its output signal, fed to block 5, blocks the operation of transistor control pulse drivers, and arrives to block 4, blocks work for valve control pulse formers, the rectifier.

The proposed device allows to increase the reliability, since it completely eliminates the emergency situation during a short circuit to earth of the output terminals of the converter and increases the efficiency of the converter by 6-8%, since the losses in the converter are reduced by the amount of losses in the transformer; improve the mass – size characteristics of the converter by reducing its weight and volume by the amount of weight and volume of the isolation transformer.

Claims (1)

Invention Formula A device for protecting a transistor converter with a DC link, made in the form of a controlled rectifier connected through a filter to the input of a controlled transistor inverter and equipped with rectifier and inverter control units, containing a current sensor designed to be connected to one of the DC busbars, the first thyristor, one of the power electrodes to be connected to the first power bus of the DC link of the converter, the first thyristor control unit, made in the form of a comparator connected to a pulse shaper, and The thyristor control unit used a comparator input, which is connected to the current sensor output, and galvanically separated, similar first and second outputs of the thyristor control unit, for which the pulse shaper outputs were used, are connected respectively to the control electrode of the first thyristor and control pulse off unit, the output of which is intended to connect to the disconnecting inputs of the control units of the rectifier and inverto, characterized in that, with the aim of increasing both reliability and weight and size indicators, a second current sensor and a second thyristor are introduced with a control unit made in the form of a comparator connected to a pulse shaper with three similar galvanically separated input codes, the first thyristor control unit is equipped with a third similar output galvanically separated from its other outputs, while The second thyristor is designed to be connected between the second bus of the DC link of the converter and the grounded bus, to be connected to which it is intended to be connected the electrode of the first thyristor and the control electrode are connected to the third outputs of the thyristor control units, the first output, the second of which is connected to the control electrode of the first thyristor, and the second output is connected to the input of the control pulse switching unit. -Vm jz -CZl / If  15 QJUZ.Z Compiled by V.Shirokov Editor S.Patrusheva Tehred M.Hodanich Proofreader V.But ha Order 7818/53 Circulation 641 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 fig.Z