基于大信号模型的多模块LCC级联变换器输出电压不均衡分析法

Analysis of Output Voltage Imbalance for Cascaded Multi-Module LCC Converters Based on Large-Signal Model

相对于单模块LCC变换器,输入并联输出串联(IPOS)多模块LCC级联变换器的拓扑具有模块化、元件电气应力小、输出纹波小、输出电压高、功率大等优势,但是各模块间谐振参数的偏差会引起模块输出电压不均衡。该文针对容性滤波的LCC谐振变换器,采用基波等效法计算出变换器电压电流的基波分量,利用广义状态空间平均法建立LCC变换器的状态方程,随后推导出单模块的LCC变换器大信号模型。在此基础上,推导出IPOS两模块LCC变换器的大信号模型,并以此模型来分析谐振参数偏差对模块间输出电压均衡的影响。最后搭建两模块LCC变换器的样机平台,验证了所提出的多模块LCC变换器大信号模型具有良好的准确度,所提模型可为谐振参数的容差分析提供依据。

Compared with the single-module LCC converter,the multi-module LCC converters with input parallel output series(IPOS)have the advantages of modularity,small component electrical stress,small output ripple,high output voltage and high power.However,the deviation of the resonant tank parameters between the modules will cause the unbalanced module output voltage.In this paper,for the LCC resonant converter with the capacitive filter,the fundamental components of the voltage and current of the converter were calculated by the fundamental wave approximation.The state equation of the LCC converter was established adopting the generalized state-space averaging method.Then,the large-signal model of the single-module LCC converter was derived.On this basis,the large-signal model of the two-module LCC converter with input parallel and output series was derived.Through the large-signal model,the influence of the deviation of the resonant tank parameters on the output voltage balance between modules was analyzed.Finally,a prototype of the two-module LCC converter is built,which shows that the proposed large-signal model of multi-module LCC converter has good accuracy.The proposed model can provide a basis for the tolerance analysis of resonant tank parameters.