Robust and adaptive maximum power point tracking for standalone photovoltaic systems using a sliding mode control approach

In this paper, a sliding mode control approach is amalgamated with an adaptive control method to develop a MPPT, which is capable of achieving accurate tracking in the presence of unmodeled, nonlinear, nonvanishing disturbances and parametric uncertainty. The maximum power operating point (MPOP) is calculated online using the power/voltage relationship of the PV power system, and the error system is developed with the objective of driving the PV array voltage to the time-varying MPOP. One of the MPPT design challenges is that the dynamic model contains input-multiplicative parametric uncertainty. This difficulty is circumvented via careful manipulation in the error system development, along with Lyapunov-based adaptive laws. A rigorous Lyapunov-based stability analysis is utilized to prove the theoretical result, and numerical simulation results are provided to demonstrate practical application of the proposed PV MPPT in the presence of a rapidly changing MPOP due to sudden fluctuations in temperature.