三电平双桥谐振变换器全局优化策略及分析

Global Optimization Strategy and Analysis of Three-level Double-bridge Resonant Converter

此处提出了一种三电平双桥谐振变换器(3L-DBRC)拓扑结构,与非谐振中性点箝位型(NPC)变换器相比更容易实现零电压开关(ZVS),电流应力更低。此处全面分析了3L-DBRC的工作原理、软开关条件和导通损耗。利用全局最优条件(GOC)对谐振电流有效值(RMS)进行优化,推导出了最优控制策略,进一步拓宽了变压器电压增益范围,使所有开关管能够在全功率范围下实现ZVS,消除了变换器次级的回流功率,提高了系统效率。最后,通过实验验证了所提谐振变换器拓扑结构的可行性。

A topology structure for a three-level double-bridge resonant converter(3L-DBRC)is proposed,which is ea-sier to achieve zero-voltage switching(zVS)and has lower current stress compared to the non-resonant neutral point clamped(NPC)converter.The working principle,soft-switching conditions,and conduction losses of 3L-DBRC are co-mprehensively analyzed.The optimal control strategy is derived by optimizing the resonant current root-mean-square(RMS)value under globally optimal condition(GOC),further expanding the voltage gain range of the transformer.Th-is allows all switching devices to achieve ZvS across the entire power range,eliminating the backflow power on the secondary side of the converter and improving system efficiency.Finally,the feasibility of the proposed resonant con-verter topology structure is verified by experiments.