Asymmetric half-bridge flyback converter and its control method

Abstract

The invention relates to the field of switching converters, and its purpose is to provide an efficiency that can take into account both light load and heavy load, and can reduce the duty cycle under light load, reduce the peak current of the primary side, reduce the cycle energy, and realize frequency conversion control , effectively reduce no-load power consumption and light-load loss; under heavy load, it can realize complementarity, transfer a part of energy through the DC blocking capacitor to the greatest extent, reduce the energy stored in the transformer, and enable the two switch tubes to achieve zero-voltage turn-on, improving the conversion A control method for the efficiency of an asymmetrical half-bridge flyback converter.

Description

technical field [0001] The invention relates to the field of switching converters, in particular to the control of asymmetrical half-bridge flyback switching converters. Background technique [0002] With the rapid development of the field of power electronics, switching converters are used more and more widely, especially people put forward more requirements for switching converters with high power density, high reliability and small size. Generally, the traditional low-power AC / DC conversion is realized by the flyback topology, which has the advantages of simple structure and low cost; [0003] However, the ordinary flyback topology is hard switching and cannot recycle leakage inductance energy, so the efficiency and volume of small and medium power are limited. In order to meet the development trend of miniaturization, light weight and modularization of power converters, soft switching technology has become a power One of the hot spots of electronic technology. "Soft sw...

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Problems solved by technology

[0006] However, because this control method is complementary, the excitation current is a continuous waveform, and the duty cycle does not change with the change of the load. Therefore, the peak current will be large at no-load and light load, and the resonant circuit The cycle energy is large, which increases the loss and greatly reduces the light-load efficiency. At the same time, this control method cannot be frequency-converted, and there is a risk of saturation. Therefore, this complementary control method can be changed to a non-complementary control method, but this non-complementary control method The control method will reduce the efficiency at full load

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