Development of Efficient 5-HP BLDC motor for Solar water pump and performance comparison with Induction Motor counterpart

Induction motor based, 5 HP Solar water pumps are common in farming application. The solar power available varies from minimum to maximum during the day. It is known that the solar insolation pattern is such that about 60 percent or more power is available for only 50 percent operating duration. For best performance of solar pumping system, the motor must exhibit very good efficiency for wide operating speed range. For 4 pole motor the operating speed range is 1200 to 2850 rpm. Efficiency of 5 HP, 4 pole Induction motor used in cost effective solar water pump is reported as 83 percent maximum at rated condition and drops to 74 percent when speed drops to minimum operating value. Drastic reduction in efficiency limits the pumping capacity and increases the motor temperature. A 5 HP BLDC motor is having efficiency about 92 percent under rated condition and remains above 89 percent for minimum operating speed. This makes BLDC motor attractive option for solar pumping system. A 5 HP, 4 pole BLDC motor is designed and integrated in surface type solar water pump and tested with standard solar panel. Comparative study is conducted with standard Induction motor based solar pump and results are presented. Finally, BLDC solar pump is qualified by testing at Government accredited laboratory.