Control of an Off-Grid PV System based on the Backstepping MPPT Controller

This work presents the modeling and the control of an Off-grid Photovoltaic (PV) system which consisted of a monocristalline PV module, a DC load, a DC-DC boost converter and a maximum power point tracking (MPPT) bloc. The output characteristic of the PV module is nonlinear and changes with solar irradiance and temperature. So, for given climatic conditions, the PV module output power is maximal when its voltage equals to a certain value. When temperature and solar irradiance change, the duty cycle of the converter considered as the control law is continuously adjusted to track the maximum power point (MPP) of the module. This paper highlights the non-linear Backstepping controller to extract the maximum power from the PV system. Asymptotic stability of the system is verified through Lyapunov stability analysis. The simulations results show that the proposed controller offers fast and accurate tracking of the MPP whatever is the change of the climatic conditions. (C) 2020 The Authors. Published by Elsevier B.V.