A Novel Ferrite SMDS Spoke-Type BLDC Motor for PV Bore-Well Submersible Water Pumps

Photovoltaic (PV) powered submersible electric water pumps are becoming popular in remote rural areas, due to the nonavailability of grid connectivity. However, the initial cost of a PV system is high. Permanent magnet (PM) brushless dc (BLDC) motors are efficient compared to existing induction motors, which reduce the cost of PV array. However, steep increase in the cost of rare-earth magnets like NdFeB and SmCo makes the use of PM motor uneconomical for PV systems. Thus, the design of PM motors with ferrite magnets is gaining interest. These magnets have low remanence flux density and are brittle. Thus, flux concentration rotor topologies are desirable. The conventional spoke-type (ST) rotor is one such topology. However, flux leakage is one of its prime concerns. To negotiate this, a novel “semi-modular dual-stack” ST BLDC motor along with its parametric aided three-dimensional finite element method analysis is proposed for a PV-based 100 mm deep bore-well submersible water pump. The motor features minimum flux leakage irrespective of rotor bridge width. In addition, a lumped parameter thermal network is modeled for quick estimation of the winding temperature rise. A prototype motor is fabricated to ascertain the results obtained from simulations, and the experimental results are presented.