A Logic-control-based MPPT Algorithm for Stand-alone PV Power Generation System

Abstract

Maximum Power Point Tracking (MPPT) technology greatly affects the transformation efficiency of a photovoltaic system. Tracking precision and response speed requirements cannot be satisfied simultaneously using conventional perturbations and observational methods with fixed step-sizes. In this paper, a duty-cycle-based logic control algorithm for stand-alone PV systems was proposed according to the MPPT evaluation requirements. Adjusting the duty cycle of the PWM signal to track the maximum power point can be achieved by regulating the input-output relation of the converter. By comparing the power at the current moment with the previous moment, the variation tendency of the duty cycle D can be determined. In this method, the duty cycle D is adopted as a controlling parameter, and only one control cycle is required, significantly reducing the controller complexity. Using a photovoltaic array YF-M20 as an example, simulations were performed under varying light conditions, and the results indicate that the proposed method can accurately track the maximum power point of the photovoltaic system and quickly respond to changing environmental variations.