A Virtual Impedance Control of Three-phase PWM Rectifiers Under Unbalanced Voltages

This paper proposes a control scheme based on the virtual impedance control for three-phase voltage-type PWM rectifiers. In the proposed control, the input terminal of the rectifier is controlled to simulate an impedance, which includes two parts: a resistance, and an impedance which can balance the input currents. The resistance is used to regulate the output DC bus voltage. The impedance is employed to obtain a sinusoidal gird current under unbalanced grid voltages without grid voltage sensors. The highlights of the proposed control are to reduce the cost and improve the current quality. Finally, the simulation results are conducted to verify the feasibility and effectiveness of the proposed scheme.