PWM控制LLC变换器的工作原理和外特性分析

Operation Principle and Characteristics Analysis of LLC Resonant Converter With PWM Control Strategy

针对变频控制LLC谐振变换器空载输出和限流时工作特性不佳的问题,提出在输入电压范围不宽且要求电路结构简单易于限流的应用场合,使用PWM控制LLC谐振变换器以获得较好的空载调压和限流特性。阐述了不同占空比下变换器的工作原理,并从时域的角度分析了其输入输出增益特性,最后针对370～390 V输入、60 V/3.6 kW输出的供电电源,完成了样机的制作与实验,验证了变换器的软开关特性和增益特性。

Aiming to the problems of poor working charateristic in LLC resonant converter during no-loads output and current-limiting condition,the LLC resonant converter with PWM control is widely applied for no-loads regulation and current-limiting.Regarding LLC resonant converter with PWM,it elaborates operational principles in different duty cycles.With respect of time domain,it analyzes the character of input and output.It is concluded that the experience consequence is consistent with proposed theory at a prototype of 370～390 V input and 60 V/3.6 kW output.