A New SPWM Controlled Three-Switch Buck-Boost Inverter for Distributed Generation Applications

A new three-switch buck-boost inverter suitable for distributed generation (DG) applications is presented. The operation principle is analyzed in detail and the mathematics model is founded based on input-output power balance principle. SPWM control method is employed to optimize the inverter performance. Compared to the conventional double-stage inverter, the proposed converter is structurally simple with only three power switches and can accommodate an AC voltage either larger or lower than the DC voltage in a single power stage. The new inverter circuit topology provides the main switches for turn-on at zero current switching (ZCS) to achieve a low switching loss by a series-resonant tank. Furthermore, an enhanced version of the inverter is also proposed to reduce the ripple voltage on the DC bus. Simulation and experimental results are given to verify the validity and effectiveness of the proposed inverter.