Full-Bridge LLC Resonant Converter with Wide-Range Robust Control

LLC resonant DC converters are widely applied in many scenarios. A hybrid modulation of pulse frequency modulation (PFM) and phase-shift modulation (PSM) are used to address the narrow operating range of the converter in the traditional PFM mode. To this end, an improved anti-windup PI control strategy is proposed. The converter’s wide input voltage range is achieved and the system oscillation and adjustment time are reduced. According to the operating characteristics of the full-bridge LLC resonant converter in different energy flow directions, the operating principle is analyzed and a simulation model is established using MATLAB/Simulink. Then the control system of the full-bridge LLC resonant converter is implemented using TMS320F28335. The simulation results show that the improved anti-windup PI algorithm has low overshoot, short rise, and stabilizing times. Experimental results show the control system has robustness and ideal dynamic response characteristics during input voltage mutation, reference voltage mutation, and load ingress.