An AC side-active power decoupling modular for single phase power converter

The conversion between DC and AC power will typically introduce a low-frequency pulsation power in the DC side of single phase power converter which may create instability, lowers its efficiency, and reduces the reliability. In this paper, a novel Power Decoupling Modular (PDM) with 2 series differential decoupling capacitors at the ac side is proposed. Compared with the DC PDM, the proposed modular holds smaller filter inductor resulting from reusing the ac inductor as the freewheel inductor, less voltage stress of the capacitor voltage because of full use of the capacitance and shortest flowing path of the pulsation power due to supply the pulsation power directly by the series capacitors at the ac side. Theoretical analysis and results are provided to explain the operation and showcase the performance of the modular. Moreover, the power flow involved in this circuit and associated controller design are detailed in the paper. Experimental results validate that the proposed solution without effect on the original system can achieve significant mitigation of the pulsation power as well as high quality output voltage.