CS216710B1 - Wiring for control of a six-pulse thyristor three-phase rectifier - Google Patents

Abstract

The subject of the invention is a circuit for six-pulse control of a thyristor three-phase rectifier, which can be used in ozonizers for controlling the three-phase cycle of converters for powering motors and generally in all rectifiers where six-pulse operation is required. The circuit according to the invention uses a three-phase thyristor fully controlled bridge, each thyristor of which has a separate trigger circuit and is characterized in that the input of the trigger circuit of each thyristor is connected via a product circuit with an output with a basic delay in the interval 0° - 300°. The circuit uses a reference voltage source with a cosine waveform for a single- or multi-phase network as the basic control element. The main advantage of this circuit is primarily its easy and simple assembly and the use of commonly available components.

Description

The subject of the invention is a circuit for controlling a six-pulse thyristor three-phase rectifier, which is used in particular in ozonators. for controlling the three-phase cycle of converters for powering the motors generally for all rectifiers where Desipulse operation is desired.

Until now, it has been considered to be the most advantageous wiring of a thyristor bridge either half-controlled or fully-controlled to obtain a DC voltage from the AC mains.

It is suitable to use a half-bridge with triple diodes and triple thyristors where energy recovery is not required and the DC ripple in a certain part of the control is also not a problem.

Where these rectifier requirements exist, it is necessary to use a six-thyristor and six diode-wide bridge. However, there are problems with controlling such a rectifier. For a half-controlled bridge, where only four thyristors are controlled, a circuit with three single-phase synchronous circuits controlled by a saw voltage obtained from individual phases of the mains supply is commonly used. In this case, the shift of the trigger pulses is 120 °, similar to the phase shift of the individual mains voltages.

However, this solution is not sufficient for a full-bridge bridge and separate single-chain trip circuits powered from a special three-phase transformer must be used, from which six separate supply voltages offset by 60 ° relative to each other can be obtained. Other electronic circuits then select the necessary pulses for the thyristor trigger circuits, respectively. with the help of other special coincidence start-up transformers.

These connections are therefore relatively complex and require, inter alia, specially adapted components.

The above-mentioned drawbacks are eliminated in the circuit for controlling the pulse control of a thyristor three-phase rectifier with a three-phase thyristor whole-bridge bridge, each thyristor having a separate trigger circuit according to the invention. with a 0 ° basic delay and a 300 ° basic delay output, the second trigger circuit of the second thyristor is coupled through the product circuit to the 60 ° basic delay output and the 0 ° basic delay output and the third thyristor trigger circuit input with a base delay of 120 ° and a base delay output of 60 °. The input of the fourth trigger circuit of the fourth thyristor is then further coupled via a product circuit with a base delay output of 180 ° and a base delay output of 120 °, the input of the fifth trigger circuit of a fifth thyristor via a product circuit with a base delay output of 240 ° and a base delay output of 180 ° And the input of the sixth triggering circuit of the sixth thyristor is coupled via the product circuit to a 300 ° basic delay output and a 240 ° basic delay output.

216 710

The circuit according to the invention uses a cosine waveform reference voltage source for single- or multiphase forces as the basic control member. Its use eliminates negative effects resulting from the sinusoidal waveform of the reference voltage.

The circuit is constructed so that the cosine voltage with the lowest value is switched on at the beginning of each half-period of the voltage voltage and at the end of the half-period with the lowest value.

When using a three-phase circuit, where symmetry and control pulse delay are the same in all phases, the shape of the reference voltages is important.

The main advantage of the circuitry according to the invention is, above all, its easy and simple assembly to achieve the desired effect. In addition, only commercially available components can be used without any special modification.

The wiring diagram for controlling the six-pulse thyristor three-phase rectifier according to the invention is shown in the attached drawing.

The connection is shown as a synchronous control circuit .20, which is connected to a three-phase network by its inputs, namely:

to input 2 of power phase X together with the cathode of the second thyristor 2 and the anode of the fifth thyristor 5; to the input 8 of the power phase Y together with the cathode of the sixth thyristor 6 and the anode of the third thyristor 3;

to the input 2 of the power phase Z together with the cathode of the fourth thyristor 4 with the anode of the first thyristor 1.

The thyristors 1 to 6 of the thyristor three-phase bridge are connected by their control electrodes through the first to sixth separate trigger circuits 11 to 16.

A product circuit 30 is connected to the output of the synchronous control circuit 20 such that the first thyristor 1 is connected via the first trigger circuit χΐ to the output 21 with a basic delay of 0 ° and to the output 26 with a basic delay of 300 °; a second thyristor 2 via a second trigger circuit 12 to an output 21 with a base delay of 0 ° and to an output 22 with a base delay of 60 °; a third thyristor via a third trigger circuit 13 to an output 22 with a base delay of 60 ° and to an output 23 with a base delay of 120 °; a fourth thyristor via a fourth trigger circuit 14 to output 23 with a base delay of 120 ° and to output 24 with a base delay of 180 °; fifth thyristor 2 Through a fifth trigger circuit 15 of output 25 with a basic delay of 180 ° and to output 25 with a basic delay of 240 °; a sixth thyristor 6 via a sixth trigger circuit 16 to output 25 with a base delay of 240 ° and to output 26 with a base delay of 300 °.

The control voltage for adjusting the rectifier output DC voltage is input to the synchronous control circuit 20 via control input 27.

The connection works as follows:

provided that the synchronous control circuit 20 with the thyristor bridge and the three-phase network is correctly phased so that all thyristors 1-6 in the individual power phase circuits polarized in the direction of the instantaneous polarity of the network phases are connected

216 710 with its control electrodes to individual trigger circuits 11-16. which can generate trigger pulses in half-phase phase mains voltages in which the unconnected thyristors are polarized and can then be opened and shifted relative to the voltage grid with corresponding opening angles, depending on the magnitude of the control voltage at the control input 27 of the synchronous control circuit 20.

Output pulses from individual outputs 21-26 open after passing through product *

a thyristor bridge thyristor circuit tsk, tsk that pulse from output 21 opens first thyristor i and second thyristor 2, pulse from output 22 second thyristor 2 and third thyristor j, pulse from output 23 third thyristor ja fourth thyristor pulse from output 24 Fourth thyristor 4 and fifth thyristor 2, pulse from output 25 fifth thyristor 2 and sixth thyristor 6 and pulse from output 26 sixth thyristor 6 and simultaneously the first thyristor

1. This function ensures the function of six-pulse thyristor bridge control.

A simplified representation of the synchronous circuit with a simplified representation of the output base circuits from the capacitors and zener diodes is intended to connect the bridge only as rectifiers. The input circuits can be adjusted in combination with other resistors connected from the capacitors to the adjacent phase and by their mutual size select the initial opening angle to any position according to the desired function of the bridge either as a rectifier, inverter or as a combined rectifier-inverter element.

Claims (1)

A circuit for controlling a six-pulse thyristor three-phase rectifier and a three-phase full-bridge, each thyristor having a separate trigger circuit, characterized in that the input of the first trigger circuit (11) of the first thyristors (1) is connected via a product circuit (30) to the output (21). 0 ° basic delay and 300 ° basic delay output (26), the second trigger circuit (12) input is coupled via a product circuit (30) to 60 ° basic delay output (22) and 0 ° basic delay output (21) , input of the third trigger circuit (13) of the third thyristor (3) through the product circuit (30) with the output (23) with a basic delay of 120 ° and the output (22) with a basic delay of 60 °; 4) via a product circuit (30) with an output (24) with a basic delay of 180 ° and with an output (23) with a basic delay of 1 20 °, input of the fifth trigger circuit (15) of the fifth thyristor (5) through a product circuit (30) with output (25) with a basic delay of 240 ° and output (24) with a basic delay of 180 °, input of the sixth trigger circuit (16) of the sixth thyristors (6) via a product circuit (30) with an output (26) with a basic delay of 300 ° and an output (25) with a basic delay of 240 °.