A novel high-efficiency inverter for stand-alone and grid-connected systems

This study presents a newly designed inverter circuit for photovoltaic (PV) power generation systems. A controllable current source supplies the filter capacitors and loads with high frequency switching to integrate the output sine wave voltage. Since the resonant inductor and the filter capacitor are connected in parallel, the series diodes of the full-bridge switches can be omitted. Furthermore, a coupled-inductor with a low volume is utilized to reduce the circulating energy and clamped the voltage stress of the devices, regardless of whether operation is in continuous conduction mode. The experimental waveforms are provided to demonstrate the soft-switching properties of all the devices. Additionally, a normal rated power with 110V-1kW-60Hz, which can be operated at stand-alone and grid-connected modes, is provided to show the effectiveness of the output voltage with low distortion, fast dynamic regulating speed and insensitivity to load variation, even under nonlinear loads. Experimental results that the maximum power inverter efficiency exceeds 97%, and the total harmonic distortion for various load conditions falls within 2%.