Power-Sharing Control Strategy for an Open-End Winding Dual-Inverter Photovoltaic–Energy Storage System Based on Decoupled Modulation

Abstract

The open-winding dual inverter topology has the advantages of a multilevel output, high DC voltage utilization, large modulation freedom, and easy fault tolerance, and is widely used in photovoltaic grid-connected systems. The open-winding photovoltaic–energy-storage converter system studied in this paper adopts this topology. The system consists of photovoltaic and energy-storage units, and the two converters can independently deliver active power to the grid when the DC-bus voltages on both sides are balanced. To achieve active-power regulation and distribution between the photovoltaic side and the energy-storage side, this paper constructs a mathematical model of the open-winding dual-inverter photovoltaic–energy-storage system and proposes a power-allocation strategy for steady-state operation. Compared with the conventional SPWM, the proposed strategy introduces a reference-voltage allocation layer before the SPWM modules, enabling flexible power sharing while retaining the simple implementation of the conventional SPWM. The proposed strategy effectively guarantees the operational stability and grid-connected power quality of the photovoltaic–energy-storage converter. Finally, its feasibility and effectiveness are verified through simulation analysis and experimental testing.