Improving the perturb and observe Maximum Power Point Tracking by using Sliding Mode control

In this paper the Sliding Mode (SM) control, used to reject the 100Hz oscillation of the voltage of the photovoltaic field in a grid connected system, is discussed. With respect to the classical linear voltage control the SM gives rise to a wider regulation band but, unfortunately, in presence of a fast irradiance variation the SM conditions could be violated producing a divergence of the operating point with respect to the desired one. In order to prevent such a drawback, an appropriate voltage compensation loop is used to interface the Sliding Mode with the Maximum Power Point Tracking algorithm. Simulation results confirm the goodness of the proposed algorithm. The proposed approach is currently patent pending.