A photovoltaic water pumping system with high efficiency and high lifetime

A highly efficient, low cost photovoltaic water pumping system integrating a push-pull converter and a three-phase voltage source inverter using a single photovoltaic panel is proposed which has got high life time due to the absence of batteries. The converter steps up the panel voltage and the inverter powers the AC motors for varying speed conditions and it uses a sinusoidal pulse width modulation (SPWM) strategy with 1/6 optimal third harmonic injection. Maximum Power Point Tracking (MPPT) strategy forces the PV to extract the maximum power at the given irradiance level. The voltage reference obtained from this is used in a PI controller to adjust the motor speed. Thus the proposed pumping system works on varying power input and gives varying water output at a given pump head and can be used in isolated locations to deliver water.