Maximum power point control of photovoltaic water pump with separately excited DC motors

This paper proposes a new off grid water pumping system design with a new maximum power point tracking method. The photovoltaic water pump is composed of a separately excited DC motor, the centrifugal pump, motor driver and maximum power point tracking unit. In the thesis, each subsystems are explored in detail and then, the proposed frequency controlled MPPT method is defined. Moreover, the drive electronics and control software for the centrifugal pump connected separately excited DC motor is designed. The proposed MPPT method is based on controlling the switching frequency of the DC step down chopper circuit and therefore the loss in energy due to complex DC-DC converters in the other MPPT control units is not observed in the proposed off grid water pump. During the PV water pump tests, at various Solar irradiation levels the voltage, current, power, rpm, flow rate and pressure rate data are recorded and then analyzed. It is concluded that the proposed MPPT method increase the delivered power and therefore it is observed that performance and efficiency of the PV water pump are increased compared to without the MPPT method controlled PV pumps.