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

Abstract

The invention discloses a converter based on an asymmetric half-bridge flyback circuit and a control method thereof, and the converter comprises a full-bridge rectification circuit, a half-bridge circuit, a resonant circuit, a transformer, a load output circuit and a control circuit. The control circuit generates driving signals of an upper bridge switching tube and a lower bridge switching tube in a half-bridge circuit according to a voltage loop output value of the converter, an instantaneous voltage value of alternating current input by an alternating current input end and an instantaneous current value of a current signal on the primary side of the transformer. A current signal flowing through the primary side of the transformer changes along with the rule of an alternating current voltage signal input by the alternating current input end, so that high-power-factor rectification is realized; in addition, the control circuit determines the conduction time of the lower bridge switch tube according to the difference between the positive peak current and the negative peak current of the primary side of the transformer, the instantaneous voltage value of the direct current output by the converter and the excitation inductance of the transformer, 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 AC and DC conversion, in particular to a converter based on an asymmetric half bridge flyback circuit and a control method thereof. Background technology [0002] At present, for small and medium power off-line switching power supply, AC / DC converter is mostly a two-stage circuit scheme, such as Figure 1 As shown in, the two-stage circuit schemes are boost based power factor correction circuit and isolated DC / DC high-frequency resonant half bridge converter circuit. The circuits of these two circuit schemes work independently and realize their own functions. However, in the application of small and medium power charger and usbpd, there are obvious requirements for the volume and cost of switching power supply system. The topology and circuit devices of the above two-stage circuit scheme have been fixed, and it is basically impossible to change greatly. Therefore, it is impossible to reduce the volume and c...

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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