An improved sliding mode control–based GMPPT algorithm for photovoltaic system

In this paper, an improved fixed-frequency-based integral sliding mode controller is designed and applied to a stand-alone photovoltaic (PV) system to obtain the desired reference signal for the maximum power point tracking. The proposed technique is designed with the modified sliding surface and sigmoidal function-based control law which improves the transient and steady-state performance of the PV system under uniform and partial shading conditions. Moreover, the cost of the proposed technique is further reduced by predicting the inductor current without employing a current sensor. In addition, the varying tuning factor strategy is used to further reduce the undershoot and overshoot issues during the tracking process. The desired voltage reference signal is provided by the online fractional open-circuit voltage algorithm. Furthermore, the proposed sliding mode control technique is integrated with the 0.8 V_oc model-based algorithm to obtain the global maximum power point. To check the effectiveness and fair analysis, the proposed technique is tested in MATLAB/Simulink environment under partial shading conditions, and its results are compared with the recently developed double integral derivative sliding mode control technique. The suggested technique is also tested experimentally on a 245 W PV module, in conjunction with a boost converter. The simulation and experimental findings reveal that the proposed technique outperforms the double integral derivative sliding mode control technique in terms of steady-state and transient performance, tracking speed, and transient efficiency.