A three-phase micro-inverter with high efficiency and a wide range of load

In this paper, a new tree-phase micro-inverter is proposed. The main part of the proposed inverter is quasi 3rd harmonic current injection circuit providing 3rd harmonic current. It shows an improvement of the efficiency over the conventional three-phase micro-inverter. The problem that the instantaneous input power mismatches output power in single-phase micro-inverter doesn´t exist in the proposed inverter. The structure and operating principles of this topology, the value of quasi 3rd harmonic injection inductor and the method of extracting quasi 3rd harmonic injection reference current are analyzed in detail. The control system combines feed forward with feedback. Finally, a 1kW three-phase micro-inverter prototype is built. Simulation and experimental results are presented to verify the feasibility and effectiveness of the proposed circuit topology and control methods.