SU922963A1 - Thyristor control device - Google Patents

Description

The invention relates to electrical engineering and can be used in shapers of output pulses for simultaneously activated thyristors.

A device for generating control pulses simultaneously turned on, i.e. series or parallel connected thyristors in the form of current transformers [1].

The disadvantage of the device is a large variation of the minimum required values of current and voltage of the general power supply due to the significant variation of the current-voltage characteristics of the thyristor control transitions (input characteristics). This causes the current and voltage reserves of the device to be injected, which increases the losses.

The closest in technical essence of the present invention is a device for controlling

2

thyristors, containing a control pulse driver, connected through serially connected primary windings of output pulse transformers, the secondary windings of which are connected to control switches of the thyristors, to the power supply [2].

A disadvantage of the known device are the additional losses in nonlinear stabilizing elements that shunt the primary windings of the output transformers.

The purpose of the invention is to reduce losses.

This goal is achieved by the fact that in the thyristor control device, each transformer is provided with an additional winding connected via a rectifier to a power source.

FIG. 1 shows the principal

device layout; figure 2 - limit

input characteristics of thyristors.

922963

A device for controlling thyristors "contains a driver 1 for control pulses, made on bipolar transistors 2 with current stabilizing resistances 3, connected in series with the primary windings 4 of the output pulse transformers 5, the secondary windings 6 of which are connected through rectifiers 7 to the control circuits of the thyristors 8. On each current transformer made additional winding 9 connected via a rectifier 10 to the power source 11.

The device works as follows.

The input characteristics of the thyristors 8 are between the limiting input characteristics 12 and 13 (figure 2). The thyristor manufacturer guarantees the inclusion of thyristors if the values of currents and voltages outside the right angle of straight lines 14 are provided at the control junction (Fig. 2). The output characteristic, which is provided by the device at the output of any transformer, is shown by two sections of curves 15 and 16 (Fig. 2).

At zero control voltage at the base of transistor 2, it is closed and current does not flow through it. When a negative control voltage is applied to one of the transistors 2, it opens, almost the same voltage is maintained on the current-stabilizing resistance 3, which determines the current value of the transistor, and this current is determined by the control voltage on the base of transistor 2 and the resistance 3, i.e. . a constant current of a given value flows through all the primary windings of current transformers. Moreover, negative voltage pulses are in turn fed to transistors 2, therefore, bipolar current pulses are generated in the primary windings of transformers 5. If the voltage drop on one of the current transformers, determined by the input · 'characteristic of the corresponding thyristor, is less than the voltage of the guaranteed switching on of the thyristor, then a constant current flows in the secondary winding 6 of the current transformer 5. Thus, the section 15 of the output characteristics of the device is formed. Winding voltage 4,

6 and 9 current transformers 5 proportion ·

15

20

25

thirty

35

45

50

The number of turns of the additional winding is equivalent to the number of turns of these windings.

9 is chosen so that the voltage on it is equal to the voltage of the circuit power supply when the voltage on the secondary winding 6 reaches the value of the thyristor turn-on voltage. With the increased voltage on the control transition of the thyristor 8, the voltage on the additional winding 9 exceeds the voltage of the power source 11, the rectifier

10 opens and the excess power returns to the power source (i.e., energy is recovered to the power source), and the voltages on the windings 4, 6 and 9 remain constant. Thus, the section 16 of the output characteristics of the device is formed. The magnitude of the control current and the stabilization voltage are set such that the output characteristic 15 and 16 possibly cover the angle as closely as possible from the limiting values of the currents and voltages 14 at which the manufacturer ensures that the thyristor 8 is turned on.

Thus, the proposed device ensures the inclusion of m ^ fig. torus for any variation of the input characteristics and with this, it reduces the amount of losses due to the fact that when the voltage is limited at the transformer windings, the energy is not lost, but returned to the power source.

Claims (1)

Claim A device for controlling thyristors, containing a control pulse former connected through serially connected primary windings of output pulse transformers, the secondary windings of which are connected to thyristor control transitions, a power source, characterized in that, in order to reduce losses, each transformer is provided with an additional winding connected through rectifier to power supply.