输入并联输出串联的两路三相LLC变换器

Dual Three-phase LLC Converter With Input-parallel and Output-series

LLC谐振变换器具有功率密度高、效率高、电磁干扰(EMI)低等特点,在电动汽车充电桩、移动电站等领域得到了广泛应用。但其输出滤波电路仅含电容,不含滤波电感,输出电流纹波较大,不利于滤波电容容量的降低,限制了功率等级的提升。此处采用的三相LLC谐振变换器,三相桥臂依次延迟120°导通,能自动平衡各相间电流,利用移相后电流的叠加效应降低次级整流输出纹波。为了应对不同电池组的电压要求,采用两路三相LLC输入并联输出串联的拓扑实现了输出电压的宽范围调节,并且达到了自动均压的效果,简化了控制算法。搭建了15 kW样机,实验验证了理论分析的正确性及方案的可行性。

LLC resonant converter has the characteristics of high power density, high efficiency, low electromagnetic interference （EMI） and so on.It is widely used in electric vehicle charging piles, mobile power plants and other fields. However,the output filter circuit only contains capacitors and has no filter inductance.The output current ripple is large which is not conducive to the reduction of the filter capacitor capacity and limits the power level enhancement. The three-phase LLC resonant converter is adopted,the three-phase bridge is delayed by 120°in sequence and the current between the phases can be automatically balanced.The rectifier output ripple is reduced by the superposition effect of the phase shift current.In order to cope with the different requirements of battery voltage,the dual three- phase LLC with input-parallel and output-series is adopted which can achieve a wide range of output voltage and au- tomatic voltage regulation and simplify the control algorithm.Finally,a 15 kW experimental prototype is built.The ex- perimental results verify the correctness of the theoretical analysis and the feasibility of the scheme.