On the Equivalence of Major Variable-Step-Size MPPT Algorithms

Functional equivalence of three nonmodel-based variable-step-size maximum power point tracking (MPPT) algorithms is revealed in this paper by establishing general closed-loop controller-plant structure of corresponding MPPT control loops, allowing us to formulate the problem as a typical stabilization task. The MPPT loop plants may be separated into three main components, two of which are similar and the third one, namely stabilization function estimator, is the main reason for the performance differences of the discussed methods in case the MPPT loop controllers are alike. It is shown that in case the estimator convergence rate is much faster than the MPPT loop bandwidth, similar low-frequency performance may be expected by utilizing any of the three methods.