LLC Resonant Converter-Frequency Domain Analysis or Time Domain Analysis

Frequency domain based analysis methods have been widely used for resonant converters due to its simplicity and acceptable accuracy. However, considerable errors would exist when the switching frequency is far away from the resonant frequency, where the circuit currents contain rich harmonics, which cannot simply be neglected. Time domain analysis is an accurate analysis method, the converter characteristics can be well obtained, which facilitate the optimal design of LLC converters. In this paper, comprehensive comparisons between frequency domain analysis (FDA) and time domain analysis (TDA) are made. Advantages and disadvantages of FDA and TDA can be easily recognized. Experimental results are presented to validate the theoretical analysis.