Constant On-time Control of ZCS Full-bridge Secondary-side LC Resonant Microinverter

Multi-stage isolated microinverters are widely used in photovoltaic power generation systems. The ability of the full-bridge secondary-side LC resonant microinverter to achieve soft- switching has attracted widespread attention. A constant on-time control method is proposed in this paper to realize zero-current switching (ZCS) of the high-frequency switching tubes and diodes, while averaging the output current on the DC/DC side of the microinverter to be a sinusoidal full wave. Theoretical analysis of the sinusoidally varying switching frequency with constant on-time is given. Moreover, closed-loop regulation is added to further improve the power control accuracy. Simulation results are provided to verify the proposed control method.