SU1171929A1 - Device for controlling polyphase converter - Google Patents

Abstract

A DEVICE FOR CONTROLLING A MULTI-FASNB1M CONVERTER containing a synchronizing transformer and channels according to the number of phases of the converter, each of which contains a series-connected saw-head voltage generator, a first input of the adder and a zero-body, the output of which is intended to be connected to the corresponding control input of the converter, the input of the saw-shaped generator, the voltage is connected to the corresponding secondary winding of the clock transformer, the primary winding of which is intended for connection to the mains, the output of the control voltage source is connected to the second inputs of the adders of all channels, characterized in that, in order to increase the working accuracy by eliminating the asymmetry of the control channels, it is equipped with an analog memory unit and a subtractor in each channel, an adder (O is provided with a third input, and the output of the subtraction unit is connected to the specified input (L, the inputs of which are connected to the outputs of the source of the control voltage and the analog memory block, the synchronization input of which a yield of a zero-body, and an information input - with the output of the sawtooth generator.

Description

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The invention relates to electrical engineering and can be used in automated electric drive systems where it is necessary to eliminate asymmetry in control channels of multiphase thyristor converters.

The aim of the invention is to improve the accuracy by eliminating the asymmetry of the control channels.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - time diagrams.

The device contains a synchronizing transformer 1, channels 2,3, ..., t control thyristor converter, control voltage source 4, multiphase thyristor converter 5, sawtooth voltage generator 6, adder 7, null organ 8, block 9 subtraction, block 10 analog memory.

The synchronizing transformer 1 is connected to the network with its input, and its outputs are connected simultaneously to the generator inputs b of each channel, the output of which, in each control channel is connected to the first input of the adder 7, to the second input of which the control voltage of the source 4 is applied, the output of the adder 7 is connected to the input of the zero-organ 8, the output of which is connected to the input of the thyristor converter bis by the second input of the block 10. The first input of the block 10 is connected to the output of the generator 6, and the output of the block 10 - to the first input of the block 9, to the second input of which the control voltage of the source 4 is applied, and its output is connected to the auxiliary input of the adder 7.

The operation of the device is explained by timing diagrams (Fig. 2), where Ui is the voltage at the output of the synchronizing transformer 1; Us is the voltage at the output of the generator 6; Uz is the voltage at the output of block 10; U4 is the voltage at the output of block 9; in fig. Us is the voltage at the output of the null organ 8.

Consider the operation of the device on the example of the operation of a single control channel multiphase thyristor converter. The remaining channels work similarly. The network voltage from the output of the synchronizing transformer 1 is fed to the input of the generator 6. It produces sawtooth pulses with a frequency of 100 Hz, synchronized with the network. Usually, sawtooth pulses with a frequency of 50 Hz are used to control multiphase thyristor converters. In the proposed device, the first sawtooth pulse is used

to obtain information about the threshold of the zero-body 8 and to work out the correction value of the threshold. The second sawtooth pulse is used,. as usual for generating a thyristor control pulse. The sawtooth voltage from the output of the generator 6 is fed to the inputs of the adder 7 and block 10. The input of the adder 7 also arrives, the control voltage of the source 4. The second input 0 of the block 10 receives impulses from the output of the null organ 8. The input of the zero-organ 8 receives the sum control voltage and ramp sweep voltage. Null organ

8, in the ideal case, should work at the moment of equality of the voltages arriving at its input, i.e., at time ti (Fig. 2), but in fact it works at time t2. Thus, a pulse arrives at the second input of the block 10 at the moment of time and a voltage appears at its output, the value of which corresponds to the magnitude of the sweep voltage at the moment of time ta. The inputs of block 9 receive the voltage from the output of block 10 and the control voltage of source 4. Block 9 performs algebraic summation of the sweep voltage,

5 corresponding to the time of the actual actuation of the null organ 8, and the control voltage. Unit output voltage

9 is supplied to the input of the adder 7 to correct the threshold of the zero-organ response 8. In the next period, the control voltage at the output of the adder 7 decreases (Fig. 2) by the amount of correction voltage supplied from the output of block 9. Therefore, the equality of the sweep voltage and voltage control comes earlier - at the moment of time is (fig. 2) and the zero-body 8

triggered at time t |. Thus, the thyristor control pulse is generated at the moment of equal voltage sweep and real control voltage, i.e. at time ti and

0 steering angle will be d.

The use of the proposed device allows to increase the accuracy of the formation of the phase of the control pulses, eliminates the asymmetry in the control channels of the thyristor converter that occurs

5 due to the unequal threshold of the triggering of the null organs. The use of the proposed device in thyristor converter control systems, in comparison with the known, allows to provide a lower output voltage ripple ratio, which will reduce the cost of installing a smoothing filter at the output.

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Claims (1)

DEVICE FOR CONTROL OF A MULTI-PHASE CONVERTER, containing a synchronizing transformer and channels according to the number of phases of the converter, each of which contains a sawtooth voltage generator, a first input of the adder and a zero-organ, the output of which is designed to connect to the corresponding control input of the converter, the input of a sawtooth generator voltage is connected to the corresponding secondary winding of the synchronizing transformer, the primary winding of which is designed for CONNECTIONS to the mains, supply output a control voltage is connected to the second inputs of the adders of all the channels, characterized in that, in order to increase accuracy of operation by eliminating the asymmetry control channels is provided in each channel of the analog memory unit and a subtracting unit, an adder _s provided with a third input and moreover, the output of the subtraction unit is connected to the specified input, the inputs of which are connected to the outputs of the control voltage source and the analog memory unit, the synchronization input of which is connected to the zero output organ, and the information input - with the output of a sawtooth voltage generator. SU ,, 1171929>