No-delay zero-crossing trigger circuit with thuristor throw-in and throw-off capacitor

Abstract

The invention relates to thyristor throw-in and throw-off capacitor no-delay zero-crossing trigger circuit, that provides features of good trigging characteristic, lower power consumption and withoutinfluencing the trigging voltage of thyristor itself. The photo-coupler input end of main control and a limiting resistor are connected in series and across input ends of DC source. The photo-coupleroutput end of main control is connected to the photo-coupler input end that turns on at positive half cycle as well as a limiting resistor in series, then the input end of AC source is out. Main control loop is composed of dc power source, the photo-coupler output and input end. Two AC input ends are connected to diode and photo-coupler output end that turns on at positive half cycle as well as aphoto-coupler input end and photo-coupler output end that turns on at negative half cycle, then the triggering end of the invented circuit is led out.

Description

technical field [0001] The invention relates to a trigger circuit, in particular to a thyristor switched capacitor zero-crossing trigger circuit without time delay applicable in a power grid. Background technique [0002] At present, the working circuits used in thyristor zero-crossing triggering in our country are divided voltage sampling, and it is judged that when the sampling voltage is less than the set value, the pulse circuit is given. Because the sampling voltage of this circuit is not the real power supply voltage, and the parameters of the components in the circuit are affected by temperature drift factors, the problem of high zero-crossing conduction voltage of the thyristor is caused. Usually it is 10 times of the trigger voltage of the tube conduction, and some even reach 30 times. It seriously affects the use characteristics of the thyristor, especially in the automatic switching circuit of the capacitor, which may generate a large inrush current and a transit...

AI Technical Summary

Problems solved by technology

[0003] The present invention is to solve the problem that the triggering characteristics of the existing thyristor switching capacitor trigger circuit are not good, which causes the thyristor conduction voltage to be too high, and provides a triggering characteristic that does not affect the trigger voltage of the thyristor itself and the inrush current of the switching capacitor. Low, Thyristor-switched capacitors without time-delay zero-crossing trigger circuit to ensure the safe and reliable operation of reactive power compensation devices composed of capacitors and thyristors and other components

[0005] Since the thyristor switching capacitor has no delay and zero-crossing trigger circuit, the trigger circuit is turned on in advance when the thyristor is working at the reverse voltage, and it is self-maintained until the control command is interrupted, and then the power supply voltage at both ends of the thyristor becomes a forward voltage. It immediately triggers and turns on when the current trigger circuit affects the thyristor. The zero-crossing delay conduction problem caused by the high voltage of the thyristor’s zero-crossing conduction dead zone due to poor triggering characteristics is solved; because the main control optocoupler is used to make the trigger circuit The power consumption is greatly reduced

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