Discussion on Modulation Methods for Flyback-type Single-Phase Inverters with Enhanced Power Decoupling for Photovoltaic AC Module Systems

Abstract

A photovoltaic AC module system has been expected to be installed on the private residences. The AC module inverter needs an active power decoupling circuit in order to enlarge the lifetimes of the inverter by eliminating a large electrolytic capacitor on the DC input bus. This paper proposes a novel modulation method, which we call Time-shared Magnetizing Modulation (TMM) method, realizing the power decoupling in the AC module flyback inverter as well as improving the efficiency conversion. The Sequential Magnetizing Modulation (SMM) method, which the authors have proposed earlier, are compared with the proposed method in operation principle and conversion efficiency point of view. It is verified that the TMM method has advantage with respect to the conversion efficiency. This paper concludes that the flyback inverter with the TMM method for the power decoupling is one of the suitable method for a single-phase grid interactive inverter used in the AC module system.