Three-Phase Multiport DC–AC Inverter for Interfacing Photovoltaic and Energy Storage Systems to the Electric Grid

Abstract

Distributed renewable energy sources (RES) in combination with hybrid energy storage systems are capable to smooth electric power supply and provide ancillary services to the electric grid. In such applications, multiple separate DC-DC and DC-AC converters are utilized, which are configured in complex and costly architectures. In this paper, a new non-isolated multiport DC-AC power inverter is presented, which comprises less passive components and less high-frequency power semiconductors. The proposed grid-connected multiport converter (MPC) enables the integrated power management of a photovoltaic (PV) array, a battery unit, a supercapacitor bank and the battery of an electric vehicle. The power circuit of the proposed MPC inverter is based on a new version of a split-source inverter topology to support bidirectional power flow and enables to connect the PV source directly to the DC-link. The proposed design is accompanied by a specifically developed control method which enables to implement the maximum power point tracking (MPPT) process without the need of any extra power converter, regulate the power flow at each port independently, as well as to control the power flow between its ports. An experimental prototype of the proposed MPC inverter has been constructed and its operation has been validated experimentally under various power flow scenarios.