A Novel topology for power decoupling of two-stage inverter based on Buck/Boost circuit

A novel power decoupling circuit using four switches is proposed, which is connected in parallel to the AC output side of the inverter. Thus, second harmonic voltage appeared in DC bus and second harmonic current appeared in voltage source can be significantly suppressed, and large electrolytic capacitor can be substituted by a small, long lifespan film capacitor. The new power decoupling circuit proposed in this paper can handle bi-directional changed pulsation power through pulse energy modulation (PEM), which calculates duty ratio in each switching cycle and achieves decoupling control. Furthermore, four operating modes of the hybrid Buck/Boost circuit are analyzed and the principle of PEM was deduced. Finally, theoretical analysis is verified by Matlab/Simulink simulation platform. The simulation results indicate that the proposed scheme is reasonable and effective and the decoupling ability of the decoupling circuit under various operating conditions is analyzed.