Cascaded control to shape output virtual impedance and improve output voltage quality for power inverter

In this paper, a cascaded control scheme for single-phase inverters connected to a load is proposed to improve the power quality and shape the output impedance. The proposed strategy consists of a proportional controller in the inner loop and the Uncertainty and Disturbance Estimator (UDE) in the outer loop. An advanced modulation method is adopted to minimize the control implementation delay and both the current and the voltage control loops are analytically investigated. Simulation and experimental results are presented to validate the theory.