A rule-based fuzzy logic controller for a PWM inverter in photo-voltaic energy conversion scheme

A rule-based controller based on fuzzy set theory for controlling the output power of a pulse width modulation (PWM) inverter in a photovoltaic (PV) energy conversion interface scheme is presented. The objective is to track and extract the maximum available solar power from the PV array under varying solar insolation levels. To achieve this the power error and the rate of change of this error are used as input signals to the fuzzy rule-based controller and its output signal is used to control the PWM inverter. The input error signals are fuzzified and expressed as linguistic labels characterized by their membership grades. Using a fuzzy relation matrix, a set of 49 rules find fuzzy logic operations, the controller output is obtained. The fuzzy controller output expressed in linguistic labels is defuzzified to obtain the actual analog signal to control the PWM inverter. The proposed fuzzy rule-based controller is simulated and experimentally verified, and is found to give good power tracking performance