Research on hybrid control strategy of LLC resonant converter
Aiming at the back-stage full-bridge LLC resonant converter of a two-stage on-board charger,a voltage-current dual single-loop competing control scheme is determined according to the charging strategy of a lithium battery,and a hybrid PFM+Burst control method is used to improve the light-load efficiency of the LLC resonant converter.The equivalent circuit method is used to simplify the small-signal modeling of the LLC resonant converter,and the frequency to output voltage transfer function is derived,based on which a 2p2z type compensator is designed for the closed-loop control of the LLC resonant converter.Finally,the correctness of the control scheme is verified in the full-bridge LLC resonant converter experimental platform.The experiments show that the converter works stably under this control scheme,and the constant voltage and constant current output is accurate.
LLC resonant convertervoltage and current double single loopPFM+Burst hybrid control2p2z type compensator