Multipurpose battery‐assisted solar water pumping system for off‐grid applications: design and development

Abstract

Providing basic human needs like water and household electricity is a challenging task at remote locations. To support both needs, this study presents the development of a multipurpose battery-assisted solar water pumping system (SWPS). The system consists of only two power electronics converter, viz., bidirectional DC–DC converter, and three-phase voltage source inverter (VSI). The detailed control system is presented, where the DC–DC converter controls the battery power and also ensures the maximum utilisation of stand-alone solar photovoltaic source. In pumping operation, the VSI is operated as a variable frequency motor drive and rotates an induction motor (IM) at the rated power to deliver rated water discharge. In power supply operation, the household electrical load is connected between the mid-point of DC-bus and the star point of an IM winding. The VSI, along with motor inductance, realises the single-phase inverter, which is controlled with synchronous sine pulse-width modulation to deliver single-phase output. The motor does not rotate during this operation and the motor winding acts as a current filter. This multipurpose SWPS assures rated water discharge during the irrigation period and availability of electrical power in the remaining period. A prototype is developed and extensive experiments are performed to investigate system performances.