A soft start control circuit

Abstract

The embodiment of the present invention discloses a soft start control circuit used to control a relay in an AC input circuit in a main loop. The soft start control circuit comprises an AC voltage detection circuit, a time delay circuit and a relay control circuit, wherein the input end of the AC voltage detection circuit is connected with the input end of the AC input circuit in the main loop, the output end of the AC input circuit is connected with the input end of the time delay circuit; the output end of the time delay circuit is connected with the input end of the relay control circuit, and the output end of the relay control circuit is connected with the input end of the relay in the AC input circuit. The AC voltage detection circuit is used to detect the input state of an AC voltage of the AC input circuit, the time delay circuit is used to realize the time delay via the energy storage to thereby guarantee that a capacitor in the AC input circuit has enough time to charge, and the relay control circuit is used to control the actuation of the relay in the AC input circuit.

Description

[0001] Technology and [0002] The invention relates to the field of power electronics, in particular to a soft start control circuit. Background technique [0003] At present, the main circuit of the AC power board usually includes the structure of AC input-rectification-filtering-transformer conversion-output, that is, the grid voltage is firstly rectified by the rectifier bridge into a pulsating DC power supply, and then the voltage is stabilized by capacitor filtering, and then through the switch tube and The transformer is converted, and finally rectified and output. Before power on, because the energy storage capacitor of the DC power supply has no voltage, it can be approximated as a short circuit. When the grid voltage suddenly increases, it can cause a strong impact on the rectifier bridge and energy storage capacitor, which greatly Reduce the life of the AC power board. [0004] The AC input circuit in the main circuit of the AC power board is as follows: figure 1 ...

AI Technical Summary

Problems solved by technology

[0005] However, figure 1 In the AC input circuit shown, it cannot be guaranteed that the power supply voltage will be established after the capacitor C0 is fully charged. If the power supply voltage is established when the capacitor C0 is not fully charged, it will still cause too much current in the circuit and damage it components in the circuit or shorten the service life of components in the circuit

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