A High Step-Up Multilevel DC-AC/DC Three-Port Converter using single DC source for hybrid microgrid applications

Abstract

In hybrid microgrids, integration of the low voltage renewable energy sources to high voltage AC and DC buses of grid requires a multiple voltage conversions. These conversions include low voltage to medium voltage and medium voltage to high voltage. When the number of conversions are increased the device count increases and power quality decreases. With this intent, this paper proposes a DC-AC/DC Three Port High Step-up Multi-level Converter (TPHSMC) topology. It has one input and two output ports namely low voltage DC input port, high voltage AC and high voltage DC output ports. The converter is a combination of switched capacitor with single DC source arrangement ( for producing multilevel boost output DC levels using single input DC source), auxiliary switches and H-bridge inverter. Operation of the converter topology is explained with the help of a single DC source nine-level high step-up three port converter. An appropriate control scheme is described and simulation results are presented using MATLB/Simulink. The proposed TPHSMC topology compared with existing topologies in aspects of power quality, device count, size of passive elements, boosting and three-port capabilities are presented to illustrate the effectiveness of the proposed converter.