MPPT for photovoltaic system using nonlinear backstepping controller with integral action

The energy generating capability of a Photovoltaic (PV) system depends on the environmental conditions and the variations in the load connected to it. The performance of controller used for maximum power point tracking (MPPT) can improve the efficiency of the PV system. PV array is a nonlinear system, so a nonlinear controller is more suitable for MPPT applications. However, the performance of nonlinear controllers completely depend upon the nonlinear model of the system under consideration. Since all the real world systems are subjected to vary with time, it is not feasible to dynamically remodel the system as well as the controller all the time. These variations introduce steady state error in the output which degrades the efficiency of the controller. To reduce this error, a nonlinear Backstepping controller with integral action has been proposed to improve the performance of recently proposed Backstepping controller for MPPT. The study uses a regression plane to generate the reference peak power voltage for MPPT using non inverting DC - DC Buckboost converter. Global Asymptotic stability of the whole system has been proved using Lyapunov stability criteria. MATLAB/Simulink is used to test the performance of the proposed controller under varying irradiance and temperature conditions. To further validate its performance, we have compared it with modified Perturb and Observe (P&O) algorithm, nonlinear Backstepping controller and Fuzzy Logic Based nonlinear controller under rapidly varying environmental conditions.