Abstract：For the special requirements of steady-state efficiency and transient boost capability, such as front-end power supplies, an improved half-bridge(HB) LLC resonant converter was obtained by adding an auxiliary switching network. In normal operation, the auxiliary switch keeps off and pulse frequency modulation(PFM) is employed to regulate the output voltage. After an ac dropout, the auxiliary switching network operates with pulse width modulation(PWM) to improve voltage gain. The only design consideration of magnetizing inductance is the performance of steady state, regardless of voltage conversion gain range, resulting in reduced circulating current due to small magnetizing inductance. The feasibility and effectiveness of the proposed converter are verified by experiment results.
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2020, Vol. 35 
