Power Decoupling Method NPC Single-phase AC/DC Converter using Neutral Point Voltage Control

Abstract

In this paper, a power decoupling method for a neutral point clamped (NPC) single-phase AC/DC converter using neutral point voltage control is proposed. In general, single-phase AC/DC converters employ bulky electrolytic capacitors at the DC link in order to smooth the ripple power with twice the utility frequency. The bulky electrolytic capacitor leads to an increased system size and shortens its lifetime. In order to solve these problems, some active power decoupling methods have been proposed. Conventional power decoupling methods absorb the ripple power by using a small film capacitor. However, additional magnetic components are required to realize these methods. The proposed control method uses a T-type NPC circuit with a small film capacitor and decouples the ripple-power with neutral point current control. Hence, the proposed method does not require an additional magnetic component as compared with the conventional methods. The effectiveness of the proposed method is proved using an 800W experimental setup.