A novel active power decoupling method for single-phase photovoltaic or energy storage applications

Abstract

Conventional single-phase inverters exhibit double line frequency power pulsating, which affects dc sources such as photovoltaic performance and battery lifetime. Bulky dc-link electrolytic capacitors are typically employed as transient energy buffer to decouple the pulsating ac power from constant dc power, but such passive components suffer from temperature and aging concerns. For high reliability and high power density, active power decoupling approach is preferred. This paper presents a novel active power decoupling method by using a six-switch single-phase inverter topology. A small film capacitor is used as pulsating energy buffer in ac side, which not only improves the reliability but also the efficiency. A novel vector PWM for this topology is also proposed to maximize the dc voltage utilization, and to achieve the independent controls of the inverter output power and power decoupling. The simulation results have verified the proposed power decoupling method.