Design of a Sensorless Photovoltaic MPPT System Using PI-Observer

Abstract

This paper aims to develop a two-loop modular pho-tovoltaic (PV) maximum power point tracking (MPPT) system that does not rely on any current sensors. The approach involves decomposing the PV system into two separate time scales: an open-loop system with a fast inner peak-current mode controller and a slower outer voltage control loop for MPPT operation. By applying this decomposition, we can accurately model the open-loop PVS by treating the duty-ratio dynamics as a state variable and reducing it to a second-order system. We also provide systematic design guidelines for the proportional-integral observer (PIO) for the PVS to achieve optimal performance in the presence of input disturbances and model uncertainties, and compare it with that of the classical P-observer.