Hybrid Control Method of Full-Bridge LLC Resonant Converter Based on Electric Vehicle

The high charging efficiency of LLC resonant converters over a very wide range of load conditions in electric vehicle charging systems has long been a research hotspot. In this paper, a hybrid control method is proposed for LLC resonant converter by combining pulse width modulation (PWM) and burst control to address the issues of small excitation current and limited output voltage range under the light load condition. The resonant current energy in the burst-on period is used to supplement the missing excitation current energy from PWM control zero voltage switching to realize PWM-Burst control. Therefore, a hybrid control of PFM and PWM-Burst is employed for LLC resonant converters under full load conditions. The proposed hybrid control method focuses on steady-state operation, and its operating principles are introduced and analyzed. Finally, simulation and experiments were conducted through Matlab-Simulink to verify the feasibility of the proposed method, and a 1-kW laboratory prototype was constructed to validate the effectiveness and advantages of the proposed method.