Research on Phase-Shifted Full-Bridge Circuit Based on Frequency and Phase-Shift Synthesis Modulation Strategy

Abstract

The full-bridge converters usually use transformer leakage inductance and parallel resonant capacitors to achieve smooth current commutation and soft switching functions, which can easily cause problems such as energy leakage and significant duty cycle loss. This paper designs a novel full-bridge zero-current (FB-ZCS) converter with series resonant capacitors and proposes a frequency and phase-shift synthesis modulation (FPSSM) control strategy based on this topology. Compared with the traditional parallel resonant capacitor circuit, the passive components used are significantly reduced, the structure is simple, and there is only a slight energy loss. By controlling the charging time of the capacitor, it can be achieved without additional switches or auxiliary circuits. The automatic control of capacitor energy based on input current addresses the low efficiency of the traditional control strategies. This paper introduces its principle in detail and verifies it through simulation. Finally, an experimental prototype was built further to demonstrate the feasibility of the theory through experiments. The module can be applied to a photovoltaic DC collection system using input parallel output series (IPOS) cascade to provide a new topology for large-scale, long-distance DC transmission.