High quality output current control for single phase grid-connected inverters

This paper presents a method for current controller design in a single phase grid-connected inverter (GCI). The proposed controller addresses the following items: transient performance; steady state tracking; output current distortions and dc; active damping; and start-up transient. The proposed controller is based on various extensions of the linear quadratic regulator (LQR) method and it inherits the optimality and robustness features of the LQR. A design algorithm is proposed that offers a very systematic method of designing controller gains to achieve all the above control objectives. Simulation and experimental results are presented to illustrate performance of the proposed method.