Asymmetrical half-bridge fly-back converter and control method thereof

Abstract

The invention relates to the field of switch converters and aims to provide a control method of an asymmetrical half-bridge fly-back converter. According to the control method of the asymmetrical half-bridge fly-back converter, the efficiencies of both light loading and heavy loading can be considered, in the light loading, the duty ratio can be reduced, the primary side peak current is reduced, the circulation energy is reduced, the frequency converting control can also be achieved, and the no-load power consumption and the light-load loss are effectively reduced; in the heavy loading, the complementation can be achieved, a part of the energy is delivered through a blocking capacitor to the greatest extent, the energy stored by a transformer is reduced, in addition, two switches achieve zero voltage switching, and the efficiency of the converter is improved.

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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