高频LLC谐振变换器的效率优化

随着电力电子功率器件的发展,功率变换器向着高频、模块化发展。LLC谐振变换器由于拓扑结构简单且能在全负载范围内实现开关管的零电压开通和副边二极管的零电流关断,损耗小、效率高,可逐渐应用于高频场合,从而成为业界的研究热点。随着工作频率的提高,原先在传统LLC中被忽略的寄生电容不仅会影响原边开关管的软开关过程而且还会使得谐振电流发生畸变。分析了寄生电容对变换器软开关的影响且对死区时间进行优化设计,以提高变换器的效率。研制了一台功率为250 W,工作频率为400 kHz的LLC谐振变换器原理样机,并进行了实验验证。

Efficiency Optimization of High Frequency LLC Resonant Converter

Along with the development of power electronic devices,power converter is developing towards high frequency and modular type.LLC resonant converters can be used widely in high frequency field and is becoming a hotspot for research in the industry due to its simple topology structure,zero voltage turn-on of the primary switches and zero current turn-off of the secondary diodes in the entire load range,low loss &high efficiency and high frequency applications.With the increase of the working frequency,the parasitic capacitance which is neglected in the traditional LLC will not only affect the soft switching process of the primary side switches,but also lead the distortion of resonance current .Based on the analysis of the influence of parasitic capacitance on the soft switching process,this paper optimizes the design of the dead time between the switches to improve the efficiency of the converters and a prototype of 250 W LLC resonant converter working at 400 kHz condition is developed to verify the theoretical analysis.