In order to improve the problem of safe commutation and high voltage spikes in the converter commutation process, a decoupling-unipolar phase-shifted modulation strategy was proposed; In order to improve the conversion efficiency and reduce the voltage stress on the switch, the topological structure of the cycle-changing high frequency link converter is adopted. Because the leakage inductance of the transformer is in series resonance with the parasitic capacitance of the switch tube, resulting in voltage spikes and voltage oscillations at both ends of the switch tube, the resonant inductor and the clamp diode are introduced; Compared with the traditional modulation method, this modulation improves the efficiency of the converter and realizes zero voltage switching (ZVS) of all switch tubes in the topology. The correctness and feasibility of the method are verified by simulation and experiments.