Derivative-free nonlinear Kalman Filtering for control of three-phase voltage source converters

The paper is concerned with proving differential flatness of the three-phase voltage source converter (VSC) model and its resulting description in the Brunovksy (canonical) form. For the linearized canonical model of the converter a feedback controller is designed. At a second stage, a novel Kalman Filtering method (derivative-free nonlinear Kalman Filtering) is introduced. The proposed Kalman Filter is redesigned as disturbance observer for estimating perturbations in the VSC model. These estimated disturbance terms are finally used by a feedback controller that enables the DC output voltage to track desirable setpoints. The efficiency of the proposed state estimation-based control scheme is tested through simulation experiments.