Converter based on asymmetric half-bridge flyback circuit and its control method

Abstract

A converter based on an asymmetric half-bridge flyback circuit and a control method thereof. The converter includes a full-bridge rectifier circuit, a half-bridge circuit, a resonance circuit, a transformer, a load output circuit and a control circuit, wherein the control circuit is based on the voltage of the converter. The loop output value, the instantaneous voltage value of the alternating current input at the AC input terminal, and the instantaneous current value of the current signal on the primary side of the transformer generate the driving signals of the upper-bridge switch tube and the lower-bridge switch tube in the half-bridge circuit, so that the The current signal flowing through the primary side of the transformer changes according to the law of the AC voltage signal input by the AC input terminal, so as to realize high power factor rectification; in addition, the control circuit also changes according to the positive and negative peak values ​​of the primary side of the transformer The current difference, the instantaneous voltage value of the output DC power of the converter and the excitation inductance of the transformer determine the on-time of the lower bridge switch tube, so that the upper bridge switch tube and the lower bridge switch tube can realize the soft switching function.

Description

technical field [0001] The invention relates to the technical field of alternating current and direct current conversion, in particular to a converter based on an asymmetric half-bridge flyback circuit and a control method thereof. Background technique [0002] At present, for small and medium power off-line switching power supplies, AC / DC converters are mostly two-stage circuit solutions, such as figure 1 As shown, the two-stage circuit scheme is a power factor correction circuit based on BOOST and a high-frequency resonant half-bridge converter circuit with isolated DC / DC. The circuits of these two circuit schemes work independently, and each realizes its own function. However, in applications such as small and medium power chargers, USB PDs, etc., there are obvious requirements for the volume and cost of the switching power supply system. However, the topology and circuit components of the above two-stage circuit scheme have been fixed, and basically no major changes ca...

AI Technical Summary

Problems solved by technology

However, the topology and circuit components of the above-mentioned two-level circuit scheme have been fixed, and it is basically impossible to make major changes. Therefore, it is impossible to reduce the size and cost of the system while ensuring various functions.

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