基于全耦合电感器的交错并联LLC谐振变换器均流特性研究

Research on Current Sharing Characteristics of Interleaved LLC Resonant Converter Based on Fully Coupled inductors

在大功率应用场合中,常将多相LLC谐振变换器并联运行,由于LLC谐振变换器的增益对元器件参数非常敏感,因此并联运行时,各相间由于器件参数不一致引起的均流问题较为突出。针对以上问题,该文提出了一种自动均流方法,通过在多相LLC谐振变换器的各个谐振槽中串联全耦合电感器,实现了变换器相与相间的自动均流。建立了基于耦合电感器的谐振回路交流等效电路模型,分析了耦合电感器的耦合度对变换器电压增益的影响,分析了耦合电感器的电感量与均流效果之间的关系,给出了耦合电感器的设计方法。最后搭建了一台输入48V、输出400V/1000W的实验样机,从仿真和实验两方面验证了理论推导的正确性和所提出方法的有效性。

In high-power applications,multi-phase converters are often operated in parallel.Since the gain of the LLC resonant converter is very sensitive to the parameters of component,the current sharing problem caused by the inconsistency of component parameters between phases is more prominent in parallel operation.To solve the above problems,an automatic current sharing method is proposed in this paper,which realizes automatic current sharing between phases by connecting fully Coupled inductors in series in each resonant tank of the multiphase LLC resonant converter.The AC equivalent circuit model of the resonant circuit based on Coupled inductors was established,the influence of the coupling coefficient of the Coupled inductors on voltage gain was analyzed,the relationship between the inductance of Coupled inductors and current sharing effect was deduced,and the design method of Coupled inductors was given.Finally,an experimental prototype of 48V input and 400V/1000W output was built,the correctness of the theoretical deduction and the effectiveness of the proposed method were verified by simulation and experiments.