Solar PV array fed cuk converter-VSI controlled BLDC motor drive for water pumping

This paper presents a solar photovoltaic (SPV) array fed permanent magnet brushless DC (BLDC) motor drive for a water pumping system. An intermediate DC-DC Cuk converter is used between PV array and a voltage source inverter (VSI) to track the maximum power by using an incremental conductance maximum power point tracking (INC-MPPT) technique. The Cuk converter has not been used in SPV array based water pumping system so far despite of having a number of advantages which are undoubtedly sufficient to replace the other DC-DC converters. A new approach for the design of low valued DC link capacitor of VSI is proposed. Besides these, the soft starting of BLDC motor is achieved by selecting the optimum value of step size in the MPPT algorithm. A centrifugal pump, characterized by its torque speed relationship is coupled to the BLDC motor as a load for the water pumping. The size of PV array and motor rating are selected such that the water can also be pumped during the period of low solar insolation levels. This study evaluates starting, dynamic and steady state performances under varying atmospheric conditions and examines the effectiveness of the BLDC motor for SPV based water pumping system. Simulated results using MATLAB/Simulink demonstrate suitability of this drive for SPV water pumping system.