Research On CLLC Converter Compound Control Strategy Based On Efficiency Optimization

At present, CLLC resonant converters with wide output range have attracted more and more attention. However, as the output voltage deviates from the rated voltage, the switching frequency is far away from the resonant frequency, which will lead to the loss of soft switching characteristics of part of the switching tube, which will lead to the overall efficiency of the converter. To solve this problem, a compound control method based on efficiency optimization is proposed in this paper. The simulated annealing algorithm (SA) is used to adjust the operating frequency and shift ratio of the resonant converter simultaneously. First, the output gain expression of the converter is calculated. Then the factors affecting converter conversion efficiency are analyzed by calculating converter loss. Finally, the operating frequency and shift ratio that can achieve the highest converter conversion efficiency are determined by the loss analysis results. The simulation circuit model is established, and the simulation results of the composite control method are compared with the traditional control method. It is verified that the proposed method can improve the efficiency of the whole machine while output a wide gain range.