Feedforward Robust Control Based on LMIs Applied to Grid-Connected Converters

This paper proposes contributions to the design of feedforward controllers that are robust to uncertain parameters in grid-connected converters. First, the uncertain parameters of the plant are described by a polytopic discrete-time model, which also takes into account the delay from the digital implementation. The control law combines a state feedback with a grid voltage feedforward action. The proposed design procedure is given in terms of linear matrix inequalities conditions, whose solution depends only on two parameters chosen by the control designer, ensuring robustness against grid uncertainties. The feedforward term of the control law ensures significant improvement of the closed-loop dynamic response under sudden disturbances, as for instance, the ones resulted from faults in the grid side. The results show the efficiency of the controller designed by means of the proposed procedure.