移相全桥变换器占空比丢失问题的研究

Research on the Loss of Duty Cycle in Phase-shifted Full-bridge Converter

在简单分析移相全桥PWM(PS-FB-PWM)变换器工作过程的基础上,详细叙述了通过合理配置隔直电容和变压器漏感来补偿占空比丢失的原理与方法,并通过PSIM软件搭建仿真模型,验证了该方法的正确性。最后根据理论分析结果,设计并制作了一台60 V/625 A的实验样机。实验结果表明,该方法可有效减小甚至消除占空比丢失的现象,从而验证了该方法的可行性。

The phase-shifted full-bridge PWM （PS-FB-PWM） converter is widely used in the low-voltage and high-cur- rent situation.The topology achieves soft switching to reduce switching loss and stress by using leakage inductance and junction capacitance.However the transformer leakage inductance decreases the rate of the primary current change and causes the loss of duty cycle in the secondary voltage.Based on the simple analysis of the PS-FB-PWM convert- er＇s working process, the principle and method are presented to compensate the loss through the reasonable blocking capacitor and leakage inductance, and the simulation model is built by PSIM to testify the efficiency of the method. Finally an experimental 60 V/625 A prototype is designed according to the theoretical conclusion.The experimental result verifies the means can compensate or even eliminate the loss of duty cycle and the strategy is feasible.