变化负载下全桥LLC谐振变换器参数优化设计

Parameter Optimization Design of Full-Bridge LLC Resonant Converter under Variable Load

LLC谐振变换器在软开关特性方面有一定的局限性。针对可变负载条件下LLC谐振变换器软开关特性不稳定的问题,本文结合ZVS/ZCS边界推导了软开关约束条件,提出一套基于全桥LLC谐振变换器变化负载下参数优化设计方法,以提高系统的稳定性和效率。方案不仅考虑谐振电感、电容和变压器的参数优化,还充分考虑负载变化对软开关行为的影响。文中介绍了全桥LLC谐振变换器的工作原理,并对电压增益与谐振网络阻抗特性进行较为细致的分析。根据上述设计方案搭建了一台500 W的车载充电机试验样机,在实验室条件下对样机进行测试,结果表明试验样机整机在参数优化后效率有所提升,最高效率可达96.36%。

LLC resonant converter has some limitations in soft switching characteristics.Aiming at the problem of unstable soft switching characteristics of LLC resonant converter under variable load conditions,the soft switching constraints are derived based on ZVS/ZCS boundary.A set of parameter optimization design method based on full-bridge LLC resonant converter under variable load is proposed to improve the stability and efficiency of the system.The scheme not only considers the parameter optimization of resonant inductor,capacitor and transformer,but also fully considers the influence of load change on soft switching behavior.The working principle of the fullbridge LLC resonant converter is introduced,and the voltage gain and the impedance characteristics of the resonant network are analyzed in detail.According to the above design scheme,a 500 W vehicle charger test prototype is built and tested under laboratory conditions.The results show that the maximum efficiency of the test prototype can reach 96.36%.