Impedance Modeling and Stability Analysis of Charging Module Based on Vienna and Full-Bridge Three-Level LLC

Charging module stability is a key index for the stable operation of charging pile system, in order to analyze the small-signal impedance stability of charging module, a cascade-type charging module impedance modeling method based on Vienna rectifier and full-bridge three-level LLC resonant converter is proposed. In this method, the small signal model and output impedance model of Vienna rectifier are established based on the state space method, and the small signal model, output impedance model and input impedance model of fullbridge three-level LLC resonant converter are established based on the equivalent circuit method. On this basis, the small-signal circuit model of the charging module can be obtained, and then the impedance model can be deduced, which realizes the overall impedance modeling of the charging module from single-level architecture to two-level architecture type. Based on the Nyquist curve, the influence of system parameters on the stability of the charging module is analyzed. Finally, the charging module simulation system is built based on MATLAB/Simulink, and the simulation results verify the correctness of the charging module impedance modeling method.