Light-load control method of phase-shifted full-bridge converter

Abstract

The invention provides a phase-shifted full-bridge converter light load control method. According to the phase-shifted full-bridge converter light load control method, a control mode of a phase-shifted full-bridge converter is switched by detecting magnetization current magnitude of a transformer of the phase-shifted full-bridge converter. The phase-shifted full-bridge converter light load control method comprises the following steps: firstly, when the magnetization current of the transformer is larger, operating the phase-shifted full-bridge converter to be in an extended phase-shifted full-bridge control mode; secondly, when the magnetization current continues to decrease till the charge loaded by residual magnetization current is close to or less than half of a direct current input voltage, operating the phase-shifted full-bridge converter to be in a modified phase-shifted full-bridge control mode; lastly, allowing the phase-shifted full-bridge converter to achieve the greatest soft driving when the operation is under the modified phase-shifted full-bridge control mode. According to the method, the greatest soft driving of a switch element is realized, the overall efficiency is improved, the heating loss is reduced, and electromagnetic compatibility is realized.

Description

technical field [0001] The invention relates to a control method of a phase-shifting full-bridge converter, in particular to a light-load control method of a phase-shifting full-bridge converter. Background technique [0002] Due to the increasingly vigorous development of semiconductor technology, many electronic products are developing towards the trend of being light, thin, short and small. With the development of power electronic products in recent years, in order to effectively reduce the volume and weight of switching power converters, the switching frequency of the converters has been continuously increased. However, once the switching frequency increases, the power switching elements of the power converter must bear greater switching stress and switching loss during switching, thereby reducing the conversion efficiency of the switching power converter. . [0003] Generally, switching power converters adopt traditional hard switching. If the operating frequency incr...

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Problems solved by technology

[0006] In addition, there are the following two situations in the light-load control operation of the existing phase-shifted full-bridge converter: 1. When the output inductor current is in continuous conduction mode (CCM), due to the current value of the two resonance points It is very small, so there is not enough energy to resonate; 2. When the output inductor current is in discontinuous conduction mode (DCM), since the current value of the two resonance points is zero, there is no energy resonance

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