Three-Phase Four-Leg Inverter Based on Voltage Hysteresis Control

As the output unit of variety distributed generation systems, the final power quality is determined by three-phase four-leg inverter. For the three-phase four-leg inverter, this paper presents a dynamic reference voltage hysteresis control scheme. Firstly, based on the existing hysteresis comparison method, this method improves the systems control rapidity and stability through designing differential negative feedback. Secondly, through theoretical analysis of electric circuit, dynamic reference voltage of the fourth bridge is achieved which make the control scheme more flexibility and adjustability. Finally, the proposed method is effective to implement output regulation of the inverter. Simulation results verify the validity of the method under unbalanced and nonlinear loads.