半桥型LLC谐振变换器的损耗分析

Loss Analysis of Half-bridge LLC Resonant Converter

对于半桥型LLC谐振变换器,建立了一种改进的损耗估算模型。该损耗模型可为LLC谐振变换器的效率优化设计提供参考。此处改进了励磁电流的估算公式以减小与实际值的偏差。根据变压器和谐振电感各自磁通波形的特点,具体分析计算了磁芯损耗。在开关损耗部分,对关断时间的选取进行了详细地讨论介绍。基于所建立的损耗模型分析比较了 LLC谐振变换器在欠谐振区域和过谐振区域工作时的损耗特性。设计制作了两台分别工作在欠谐振区域和过谐振区域的1 kW样机,验证了损耗估算模型的准确性。

An improved loss estimation model of the half-bridge LLC resonant converter is established.This loss model can provide a reference for the efficiency optimization design of the LLC resonant converter.The estimation formula of the excitation current to reduce the deviation from the actual value is improved. According to the characteristics of the respective magnetic flux waveforms of the transformer and the resonant inductor,the core loss is specifically calculated. In the switching loss part, the selection of the off time is discussed in detail.Based on the established loss model, the loss characteristics of the LLC resonant converter in the under-resonant region and the over-resonant region are analyzed and compared. Two 1 kW prototypes working in the under-resonant region and the over-resonant region respectively are designed and fabricated to verify the accuracy of the loss estimation model.