A Modeling Method for Extended Phase-Shift Control of CLLC Resonant Converter Based on Simplified Time-Domain Analysis

The CLLC resonant converter has advantages including soft switching, wide output range, and bidirectional operation, making it a popular bidirectional DC-DC circuit topology. However, the CLLC resonant converter still suffers from poor voltage gain regulation and low efficiency at light load. In this article, a simplified time-domain analysis-based modeling method is proposed for extended phase-shift (EPS) control of CLLC resonant converter to enhance light load efficiency. By simplifying the time-domain expression, the computational difficulty is greatly reduced. A specific expression of the relationship between gain and phase-shift angle of the converter with EPS control can be obtained, which has been verified to have high accuracy. It is also used for analysis to determine the optimal phase-shift angle ratio with EPS control, in order to achieve maximum energy conversion efficiency. The correctness of the analysis and conclusion is effectively verified by simulation.