SU473266A1 - Device for thyristor phase control - Google Patents

Description

one

The invention relates to the field of electrical engineering and can be used in converter thyristor control systems. Known devices for phase control thyristors, containing a clock transformer, resistors, diodes, capacitor. The drawbacks of these devices are the relatively short rise time and voltage in connection with the relatively high power of the clock transformer and the large number of secondary windings needed to form a sawtooth voltage.

The difference of the invention is that the separation diode at the input of the thyristor driver is connected through a capacitor to the collector of the traisistor, the base of which is connected to one phase winding, and the collector is connected to a different phase winding of the synchronizing transformer.

This makes it possible to increase the duration of the growth of the sawtooth and reduce the power of the synchronizing transformer.

FIG. 1 shows the scheme of the proposed device; in fig. 2 shows time diagrams of operation of the device (in Fig. 2, a shows the shape of the winding on the winding 3; and Fig. 26 shows the voltage form on the winding 4; Fig. 2 c shows the voltage form on the capacitor 9).

The device for phase control of thyristors works in the following way. When the source of stabilized charging 1 is connected, for example, at time ti, a positive voltage of the winding 3 is applied to the base of transistor 2 (Fig. 26). At the same time, the negative winding 4 of the three-phase synchronizing transformer is applied to the collector of the transistor 2

(Fig. 2 a). The transistor 2 is in the locked state. Under the influence of negative voltage, the co-capacitor 5 starts charging along the circuit: the end of the winding 4 — the resistor 6 — the resistor 7 — the diode 8 — the beginning of the winding 4.

One time, the capacitor 9 is charged along a circuit: the voltage source of a constant voltage 1 is a resistor 10 - minus the source of a constant voltage. For example, on the condenser 9, it grows along a sawtooth

law (Fig. 2 c).

At the time tz, a negative voltage is applied to the base of the transistor 2, the transistor 2 opens and the capacitor 5 begins to discharge, but value: a semi-conducting diode 11 -

the control electrode of the thyristor 12 is the emitter-collector junction of transistor 2. Under the influence of the discharge current, the thyristor 12 is opened and the capacitor 9 begins to discharge in a circuit: the thyristor 12 is a resistor 13. Time

the discharge of the co-agent is determined by the magnificence

3

resistance 13, which serves to limit the current flowing through the thyristor at the initial moment of discharge of the capacitor 9.

The time during which the non-origin of the charge of the capacitor 9 is determined by the duration of the discharge of the capacitor 5. This prem is 5-6 el. hail, and includes the discharge time of the capacitor 9 and the open state of the thyristor 12.

Thus, the thyristor phase adjustment device makes it possible to form a saw-tooth voltage with a capacitor charge duration (saw rise time) 354-355 el. hail.

The fluctuation of the alternating voltage in the network changes the duration of the discharge of the capacitor 5 and the charging time of the capacitor 9 within the limits of I-2 el. hail. Such a change in the long-term charge of the capacitor 9 is almost impossible.

It is paired with ns ieneiinii phases of unlocking pulses.

Subject invention

A thyristor control device containing a three-phase synchronizing transformer, a transistor, diodes, a capacitor, and a thyristor of a sawtooth voltage divider.

a diode and an input resistance, which is HI e so that, in order to increase the capacitance and the rise time of the sawtooth, the indicated separation diode is connected via a capacitor to the collector of the transistor, the base of which is connected to one phase winding, and the collector is connected to another phase winding of the synchronizing transformer through a collector.

Fig 2