SU369661A1 - METHOD OF CONTROL OF THE TIRISTOR TRANSMITTER - Google Patents

Description

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There is a known method for controlling a thyristor converter containing a power thyristor, in parallel to which a serial switching LC circuit is connected through a triac. With this method, control pulses are simultaneously applied to the power thyristor and the triac at the moment when the power thyristor is turned on and to the triac when the power thyristor is turned off. The disadvantages of this method are the dependence of the clarity of the circuit on the off time and the magnitude of the holding current of the triac, the unreliable operation of the triac due to the double switching cycle over the period of converter operation and the complexity of the control system.

The purpose of the invention is to simplify the control system and increase the reliability of the triac. This is achieved by the fact that, according to the proposed method, control pulses are supplied to the triac only at the time when it is necessary to close the power thyristor, and the duration of these pulses must exceed the recharge time of the capacitor of the LC circuit.

FIG. 1 shows a circuit of a thyristor converter controlled by the described method; in fig. 2 - voltage diagrams on circuit elements.

The converter contains a load 1, a shunt return diode 2, a power thyristor 3 and a switching triac 4, a capacitor 5 and a choke 6.

Before starting the thyristor converter, it is necessary to open the simpstor 4, while the capacitor 5 of the switching LC circuit is charged with a plus on the lining,

connected to the anode of the power thyristor 3. After supplying the control pulse / control to the control electrode of the thyristor 3 only at time i (see Fig. 2), the thyristor opens and the supply voltage is applied to the load 1. At time / 2, the control pulse is applied to the triac 4 and the capacitor 5 is recharged with a plus to the plate connected to the choke 6 of the switching LC circuit. The duration of the triac control pulse must be longer than the recharging time of capacitor 5. After the recharging is completed, the reverse recharging of capacitor 5 and locking of the power thyristor 5, the load

disconnects from the power source. Depending on the relative duration of the on state of the power thyristor 3, the average value of the voltage f / i on the load also changes.

The proposed method is simple to implement and requires only one necessary condition to be met - the duration of the triac control pulse must be longer

time reload yes switching capacitor. The reliability of the operation of the circuit is greatly enhanced, since when power

thyristor simistor is fully open and works the entire area of its transitions. In addition, the control system is simplified and the effect of the triac parameters on the clarity of the circuit is eliminated.

Subject invention

The control method of the thyristor converter with a serial switching

An LC circuit connected in parallel to the main thyristor of the converter through a triac, which is supplied with control pulses, characterized in that, in order to increase reliability and simplification, control pulses are fed to the triac only at times when it is necessary to close the power thyristor, and the duration These pulses are chosen to be longer than the recharge time of the capacitor of the LC circuit.

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