Abstract: With the widespread application of DC/DC converters in distributed energy systems, improving their efficiency and power density has become a research focus. This paper proposes an extended phase-shift and variable-frequency extended phase-shift modulation strategy for the series resonant converter, aiming to minimize the root-mean-square (RMS) value of the inductor current. The resonant tank current model is established using the fundamental harmonic analysis method, the soft-switching conditions are analyzed, and a closed-loop control system is designed. Experimental results show that the proposed strategy effectively reduces the resonant current peak and turn-off current, thereby enhancing the system efficiency.