Shutoff energy recovery method and circuit

Abstract

The invention provides a shutoff energy recovery method and circuit. The shutoff energy recovery circuit comprises a capacitor C1, a diode D1 and a DC-DC converter; the DC-DC converter is composed ofa flyback circuit, and the flyback circuit comprises a transformer T1, a primary circuit formed by primary winding of the transformer T1 and a secondary circuit formed by secondary winding of the transformer T1; an anode of the diode D1 is led out to serve as a first input end of the shutoff energy recovery circuit and used for being connected with one end of a power switch tube; a cathode of thediode D1 is connected with a positive electrode of the capacitor C1, and a negative electrode of the capacitor C1 is led out to serve as a second input end of the shutoff energy recovery circuit and used for being connected with the other end of the power switch tube; the two ends of the capacitor C1 are connected with the primary circuit of the flyback circuit, and an output end of the secondarycircuit of the flyback circuit is led out to serve as an output end of the shutoff energy recovery circuit and used for being connected with an external power supply end.

Description

technical field [0001] The invention relates to a method and a circuit for recovering energy when a switch is turned off, in particular to a method and a circuit for recovering the energy when a main switching tube of an asymmetrical half-bridge flyback circuit is turned off. Background technique [0002] The main switching tube (that is, the power switching tube) of the existing asymmetrical half-bridge flyback circuit is used as an electronic switch (hereinafter referred to as a switch), and when it is turned on or off, loss will occur in the overlapping region of voltage and current. The traditional method is generally to modify the circuit parameters to reduce the switching loss. This method has poor generality. Since the excitation current of the asymmetrical half-bridge flyback circuit can be reversed, it can realize zero-voltage turn-on, thereby reducing the turn-on loss. However, the main power transistor of the asymmetric half-bridge flyback circuit has a large cu...

AI Technical Summary

Problems solved by technology

[0005] (1) The turn-off loss of the main switch tube is large, which is not conducive to the miniaturization of the power module;

[0006] (2) Although the turn-off loss of the main switch is reduced by connecting a capacitor in parallel to the main switch, this method will affect the turn-on process of the switch, increase the turn-off loss of the auxiliary switch tube, and increase the zero-voltage turn-on time. difficulty

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