Design and development of a maximum power tracking circuit for a photovoltaic system feeding DC motors

This research deals with the design and development of a novel scheme for maximum power tracking in the case of a photovoltaic generator feeding a d.c. motor. The proposed system consists of a photovoltaic generator, a buck converter and a separately excited d.c. motor. Positive feedback of the motor speed is used to track the maximum power point. Mathematical models are given for the PV generator, buck converter and d.c. motor. Control laws relating duty cycle of the converter with the speed of the motor for different types of load torques and solar insolations are derived and implemented. Also state space averaged equations are developed to study the transient performance of the system.; Comparison between direct connection and connection through a maximum power tracking circuit of the d.c. motor to the solar panel is presented in terms of the utilization efficiency. It is seen that with the proposed maximum power point tracking method, the utilization efficiency of the solar panels remains above 96% even for low values of insolations. Temperature effects on the PV generator are also included in the studies. Experimental results obtained from a prototype system are given.