高功率LLC谐振变换器的设计方法

摘要

研究转换器的效率优化问题,基频分量法已广泛应用于高功率LLC谐振变换器设计中.传统方法用正弦波代替谐振电流,忽略了高次谐波的影响.为更有效的改善转换器效率,提出基于时域的LLC谐振转换器的参数设计法.采用时域分析法对谐振变换器的工作过程和状态方程进行分析,绘制直流增益特性和开关损耗优化曲线,对LLC谐振网络进行设计和参数优化.时域分析法不但保证了转换过程中的有用信息不丢失,而且在同一直流增益值下的多组参数组合更利于损耗曲线的绘制,提高转换效率.对1000W LLC谐振转换器仿真结果表明:与基波分量法相比,时域分析法设计的网络参数能更好的满足转换器的工作要求,同时具有更高的转换效率.%First Harmonic Approach (FHA) has been widely used for parameter design of high power LLC resonant converter. The FHA was useless to optimize resonant parameters because it uses sine wave instead of resonant current and ignores the high harmonic. In order to improve the converter efficiency, a novel design method based on time domain for LLC resonant converter is proposed. The new method analyzes the LLC converter working principle and state equations, draws DC gain curves and losses curves, and optimizes the LLC network parameters. The main advantage of using this method is that there is no useful information to loss and there are more parameter combinations , which are the advantages of optimizing parameters and improving efficiency. Finally, following proposed design guide line, a prototype of 1000W LLC series resonant converter with 92% efficiency has been built and tested. The result verified the novel design can better meet the work requirements and acquire the higher energy conversion efficiency.