LLC谐振变换器的扩展描述函数法建模

给出了LLC谐振变换器的等效电路,基于扩展描述函数法建立了该等效电路的小信号模型、得到了LLC变换器的稳态解及其直流电压增益特性。借助PSpice仿真软件得到了该变换器在不同开关频率和不同电路参数下输出变量对控制变量的频率特性曲线。分析了开关频率、输入电压、占空比、品质因数和负载等主要参数对频率特性的影响。所作的工作对变换器参数的优化设计、闭环控制及动态性能设计具有指导意义。

Modeling of LLC Resonant Converter Based on Extended Describing Function Method

An equivalent circuit of LLC resonant converter was given. The small-signal model was established for the LLC resonant converter by the extended describing function method. The steady-state solution of LLC converter and its DC voltage gain characteristic were obtained. Using PSpice simulation we can get the frequency characteristic curves of the output variable to control variable of the converter at different switching frequencies and different circuit parameters. The affect of major parameters which include the switching frequency,input voltage,duty ratio,quality factors and the load on the frequency characteristics were analyzed. The work that we have done had guiding significance for the optimization of parameters,design of closed loop control and dynamic performance of the converter.