Robust control for three-phase grid connected power converters via second order sliding mode

In this paper, a model based robust control for three-phase two-level grid connected power converters is studied. The proposed controller uses a Second Order Sliding Mode (SOSM) technique to develop the control law. The control objectives are to achieve desired dc-link capacitor voltage regulation and unity power factor. This requires controllers with fast response in the presence of external disturbances. An Extended State Observer (ESO) is employed to asymptotically reject the disturbances which are integrated in the controller design. The proposed control strategy has a cascaded structure which consists of current tracking (inner) and voltage regulation (outer) loops based on ESO. Multi-rate simulation illustrates the effectiveness and robustness of the proposed controller under parametric uncertainties and load variations.