Modeling and Hybrid Controller Design of CLLLC

CLLLC resonant converter usually adopts traditional frequency modulation (FM) control. When the gain is less than 1, the voltage gain curve of CLLLC resonant converter has low sensitivity to frequency, which makes the frequency variation range too wide. In order to achieve the wider voltage output range, this paper proposes a hybrid modulation method adopting FM under voltage gain greater than 1 and phase shift modulation (PSM) under voltage gain less than 1. Meanwhile, this paper proposed extended description function modeling method for CLLLC resonant converter. Based on the large signal model, the voltage gain expression of phase-shift modulation can be derived, which is convenient to analyze the output characteristics of the converter. Based on the small-signal model, the frequency modulation compensator and phase-shift modulation compensator of hybrid modulation are designed respectively. Matlab simulation verifies the accuracy of modeling and the experiment verifies the effectiveness of the proposed method.