Automatic soft power-on rectifying circuit

Abstract

The invention provides an automatic soft power-on rectifying circuit including five power diodes PD1-PD5, a unidirectional thyristor, an electrolytic capacitor, a thermosensitive resistor, a voltage-stabilizing diode, resistors R1-R6, and capacitors C1-C3. When a single-phase alternating current power supply is switched on, a rectifying bridge formed by the four power diodes PD1-PD4 charges the electrolytic capacitor EC1. The electrolytic capacitor EC1 and the thermosensitive resistor form a resistance-capacitance charging branch circuit. The voltage of the electrolytic capacitor EC1 rises slowly. When the voltage of the electrolytic capacitor EC1 rises and approaches a net voltage peak, a divider resistor R3 gets enough voltage. After rear stage voltage stabilization and current limitation, the current is formed and sent to a place between a gate pole and a negative pole of the thyristor TY1. The thyristor is conducted to short out the power-on current-limiting thermosensitive resistor. The rectifying circuit enters the full and natural rectifying state, and finishes the soft power-on. The automatic soft power-on rectifying circuit can be applied to the field in which an AC-DC convertor is used as a preceding stage circuit, and can simultaneously realize the automatic soft power-on process and the single-phase rectification process.

Description

technical field [0001] The invention relates to a single-phase rectifier circuit in the technical field of power electronic conversion, in particular to an automatic soft power-on rectifier circuit. Background technique [0002] For power electronic conversion equipment powered by AC power with a diode rectifier circuit, such as frequency conversion home appliances and communication power supplies, the issue of soft power-on needs to be considered. Otherwise, because the initial electrolytic capacitor voltage is zero, the power electronic conversion device will have an overcurrent fault during the power-on stage, resulting in overvoltage breakdown of the subsequent stage converter and air switch action. [0003] Among the commonly used power-on current-limiting measures, most of them adopt the method of adding a current-limiting resistor in the AC or DC line, which specifically includes three methods: (1) The current-limiting resistor is connected in series on the DC side or...

AI Technical Summary

Problems solved by technology

The problem with the first two methods is: the secondary current impact problem is brought about when the resistance is cut off

The problem with the latter method is that it is only suitable for applications with a load power below 200W

For power electronic conversion devices that start and stop frequently, the PTC thermistor will lose its current limiting function due to heat. Work

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