Decoupled PI current controller for grid-tied inverters with improved transient performances

This study proposes a novel decoupled proportional–integral (PI) current controller for grid-tied inverters. The proposed controller can be viewed as the modification of the existing decoupled PI current controller to include the reference jump in order to achieve nominal performance recovery in response to step changes in the current reference. The modified decoupled PI current controller is derived based on combining feedback-linearisation technique with a disturbance observer-based control approach that belongs to the high-gain observer technique. The key feature of the composite controller is its ability to retain the transient performance specified under the feedback-linearising control, particularly when the control does not saturate. Furthermore, by considering the control saturation in the observer design, an anti-windup scheme arises naturally into the controller, leading to an improved transient performance in the presence of saturation. The effectiveness of the proposed controller was verified by simulation and experimental results.