A low-cost semi-modular dual-stack PM BLDC motor for a PV based bore-well submersible pump

Photovoltaic (PV) powered electric water pumps are becoming popular in remote rural locations due to the non-availability of grid connectivity. A typical PV based drive scheme consists of a PV array, DC-DC converter, inverter-fed induction motor and a water pump. Induction motors are rugged in construction and offer low maintenance but their efficiency is poor at low power levels. Therefore, permanent magnet brushless DC (BLDC) motors are preferred in these applications in view of their relatively high efficiency and robust structure. But, over the years there has been a steep hike in the price of rare-earth permanent magnets like NdFeB (Neodymium Iron Boron) and SmCo (Samarium Cobalt) which make the motor un-economical. Therefore, the design of BLDC motor with low-cost ferrite permanent magnets is gaining interest. In this paper, a novel low-cost three-phase “Semi-Modular Dual-Stack” (SMDS) spoke type brushless dc motor is proposed for a PV powered deep bore-well electric submersible pump (ESP). The proposed motor has good flux concentration without compromise on the ruggedness of the rotor with additional advantage of low cogging torque. Detailed simulation studies of the proposed motor are carried in 2D and 3D-FEM environment using MagNet software to validate the claims and the results are presented.