Controllable silicon triggering circuit for equipotential switching of capacitor

Abstract

The invention is a capacitance equipotential-switching thyristor triggering circuit, including high- voltage thyristor, control optical coupler and auxiliary power supply, and adopting trigger current control triode, amplifier triode, voltage zero-passage detecting triode and trigger current by-pass triode. Its main circuit voltage is rectified and then applied on two ends of the high-voltage thyristor, the auxiliary power supply is a DC power supply derived from rectification and filtration of an AC power supply and applied on to a resistance connected with the collector of trigger current control triode so as to generate a trigger current for the high-voltage thyristor, and the high-voltage thyristor is triggered as the two conditions that the control optical coupler is switched on and that the main circuit voltage passes zero. It realizes the function of triggering by zero passage of the main circuit voltage at high voltage, needs no connection waiting time, and realizes the equipotential capacitance switching, and avoids the impact current as the capacitance is connected to the electric network.

Description

technical field [0001] The invention relates to a thyristor trigger circuit for equipotential switching of capacitors, which is used for switching control of capacitors in AC circuits. The invention belongs to the technical field of voltage zero-cross triggering of silicon controlled rectifiers. Background technique [0002] In active filtering and reactive power compensation equipment, there are often requirements for switching capacitors. If the residual voltage on the capacitor is not equal to the system voltage, there will be a large inrush current. Therefore, it is required to connect the capacitor to the grid when the grid voltage crosses zero, so as to avoid inrush current when the capacitor is connected to the grid. The principle of the method currently used is to first make the voltage on the capacitor equal to zero, and control the switch to connect the capacitor to the grid when the grid voltage crosses zero. In this way, the grid voltage will not generate an in...

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Problems solved by technology

[0004] However, this solution not only has the problem of fast switching capacitors, but also the withstand voltage of the optocoupler triggered by zero crossing is only 400V, and when the system voltage is 380V AC effective value, the peak value of the power supply voltage is 537V, the above optocoupler There is a problem with the ability to withstand voltage, so both aspects require the redesign of the zero-crossing trigger circuit

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