Sliding mode control of a buck converter for maximum power point tracking of a solar panel

This paper presents a novel sliding mode control (SMC) approach for maximum power point tracking (MPPT) of photovoltaic (PV) panel using buck converter. Since classical hill climbing and incremental conductance MPPT methods can not differentiate change in power due to perturbed voltage and changing weather condition, both algorithms are prone to failure in case of rapidly varying solar radiation. Most of the maximum power point tracking approaches presented in literature are based on finding desired PV voltage for MPPT and tracking the actual PV voltage to desired one. On contrary, in this paper, SMC approach is applied to control inductor current and converter output voltage for MPPT and then convergence and tracking of PV voltage is achieved. Incremental conductance method is used to find desired value of PV voltage and steady state analysis is performed on state equation to find out desired inductor current and output voltage of converter. The proposed controller is able to bring the system on sliding surface in finite time and force it to remain on sliding surface. It has been found that exact MPPT is achieved even when we consider varying atmospheric condition and disturbances. The feature of the proposed algorithm are supported by theoretical analysis and simulation results.