LLC谐振变换器的谐振模式原理及最大增益分析

LLC谐振变换器具有高效率功率变换和宽范围输入电压适应性的突出优势,但是关于变换器最大增益的研究还存在明显不足.为此,以LLC谐振变换器的最大增益为研究对象,根据串并联谐振的进行过程对变换器的谐振模式进行了划分,即变换器可分为欠谐振、完全谐振和过谐振3种谐振模式.当变换器工作在完全谐振模式时,变换器增益达到最大值,对应的开关频率称为临界频率.最后,通过建立变换器状态方程推导得到最大增益和临界频率的时域表达式,并结合仿真和实验验证了理论分析的准确性.

Resonant modes and peak gain analysis of LLC resonant converter

LLC resonant converter has outstanding advantages in high power conversion efficiency and wide range adaptability of input voltage, but research on the peak gain is clearly insufficient. Therefore, the peak gain of LLC resonant converter is studied. According to the operation process of the series-parallel resonance, the converter can be divided into three resonant modes: inadequate resonant mode, complete resonant mode and over resonant mode. When the converter operates in complete resonant mode, it reaches its maximum value, and the corresponding switching frequency is named critical frequency. Finally, derivation of time-domain expression of the peak gain and the critical frequency is completed through the establishment of the converter state equations, and the accuracy of theoretical analysis is verified through simulation and experiment.