DC to Single-Phase AC Grid Connected Inverter with Boost Type Active Buffer Circuit Operated in Discontinuous Current Mode

Abstract

A novel circuit topology for a single-phase inverter with a power decoupling capability operated in discontinuous current mode (DCM) is proposed in this paper. An inverter connected to a single-phase grid requires a power decoupling capability to compensate for a power ripple with twice the grid frequency. Bulky capacitors are used as DC-link capacitors in conventional systems. In contrast, the proposed circuit topology can use ceramic capacitors instead of electrolytic capacitors by reducing the required capacitance based on the active buffer concept. Moreover, this active buffer requires no additional inductor because it uses DCM for the power decoupling capability. In this paper, a control method for the active buffer circuit operated in DCM is introduced. An experimental verification of a 1-kW prototype shows that the proposed circuit reduces the input current ripple at twice the grid frequency by 96.8%, with a maximum efficiency of 95.2%. In addition, the Pareto optimization of power density and efficiency is used to clarify the maximum power density points. It is found that the maximum power density of the proposed circuit is 1.6 times higher than that of a conventional boost-type active buffer.