一种多模式电流馈LCL谐振变换器

A Multi-mode Current-fed LCL Resonant Converter

提出一种多模式的电流馈LCL谐振变换器。该变换器仅需要在传统全桥式电流馈变换器的主变压器原边增加一个并联谐振电容Cr。利用反激变压器的原边电感L_r和主变压器的漏感Lk,与Cr构成LCL谐振腔。电感Lr在Boost,LCL和Flyback这3种电路模态中被复用,由3种模态又构成了高、中、低3种电压增益模式。变换器采用定频脉宽调制(pulse width modulation,PWM),同时保留了软开关的优点,适用于宽输出电压范围的场合。文中首先介绍变换器的拓扑结构,详细分析变换器工作过程。其次采用时域分析法推导出电压增益公式,分析电压增益特性。描述3种电压增益的设计方法,给出在控制器中的切换和设计原则。最后搭建一台55~120V输出,额定输出电压100V,额定功率300W的实验样机,实验结果验证了所提变换器的可行性及理论分析的正确性。

A multi-mode current-fed LCL resonant converter was proposed.The converter is realized by only adding a parallelling resonant capacitor Cr at the primary side of main transformer in a conventional full-bridge current-fed converter.A LCL resonant tank consists of the primary inductor Lr of the flyback transformer,the leakage inductor Lk of the main transformer and the resonant capacitor Cr.The inductor Lr is multiplexed in three circuit formations including of boost,LCL and flyback.These three circuit formations are combined to achieve three voltage gain modes with high,medium and low voltage gain mode.This converter adopts PWM method with fixed switching frequency and the soft-switching advantage is kept,which is suitable for a wide output range field.Firstly the topology of the converter was introduced,and the operating theories of each mode were analyzed in detail.Secondly,the voltage gain formula was deduced by time domain analysis method,and its characteristic was analyzed.The designing method of three voltage gain modes was described.Their switching and design principles in the controller were given.Finally,an experimental prototype with 55~120V output,rated output voltage of 100V and rated power of 300W was built.The experimental results verified the feasibility of the proposed converter and the correctness of theoretical analysis.