MOSFET输出电容对CLLLC谐振变换器特性影响分析

Analysis of the Influence of MOSFET Output Capacitance on the Bidirectional CLLLC Resonant Converter

在详细分析MOSFET输出电容对CLLLC谐振变换器运行原理和工作特性影响的基础上,针对MOSFET输出电容在续流阶段会产生振荡的问题,提出一种优化的参数设计方法,可在保持自然软开关特性的同时减轻振荡;针对由输出电容引起的变换器轻空载工作时输出电压漂高的问题,采取电压滞环间歇模式控制,可有效将输出电压调节至额定值,同时降低变换器轻空载工作时的损耗;最后,搭建了一台1 k W、400 V/48 V的实验样机,实验结果证明了所提优化设计和控制策略的正确性和可行性。

In order to solve the problem of oscillation caused by the MOSFET output capacitance in the after flow stage of the CLLLC resonant converter,based on the analysis of the effect caused by the output capacitance on the operation principle and the working characteristics,an optimized design method is proposed to maintain soft-switching and alleviate oscillation. In addition, this paper uses hysteresis burst-mode control to solve the problem of the high output voltage at light load condition,which is caused by the output capacitance. This control scheme can regulate the output voltage to the rated value,and reduce the losses at light load condition. Finally,a prototype with 400 V /48 V DC buses and 1 k W power rating is built. The experimental results verify the performance of the proposed design method and control scheme.