PWM控制LLC谐振变换器的单调性研究

摘要

In wide output voltage and load current range applications such as standard communication rectifier and electric vehicle charging module,etc.,since the non-monotonic phenomenon in high frequency region of the LLC resonant converter and limiting considering of the too high switching frequency,a simple frequency control is difficult to satisfy need,the usual approach is to introduce PWM control on the basis of PFM. Currently,the research about the monotonicity of LLC resonant converter in PWM control mode is rare. By simulation and experiment,the monotonicity of LLC resonant converter in PWM control and the nature of the non-monotonic behavior under particular duty cycle were researched,the range of non-monotonic duty cycle was tested. At last,the practical solution was introduced according to the experiment results.%在标准通信电源及电动汽车充电模块等宽范围输出电压及负载电流变化范围较大的应用场合,由于LLC谐振变换拓扑在高频区具有的不单调现象及实际应用中考虑开关频率的限制等情况,单纯的调频控制难以满足要求,常用的解决方案是在PFM控制的基础上特定条件下引入PWM控制.针对目前对PWM控制模式下LLC谐振变换器单调性分析并不多见的现状,对PWM控制LLC谐振变换器的单调性进行仿真及实验研究,分析了特定占空比下不单调现象的本质并测试了不单调占空比范围,最后根据实验结果给出了实用解决方案.