Design Analysis and Performace Improvement of Radial Flux Permanent Magnet Brushless DC PMBLDC Motor

Abstract

electric motor. This research work aims to design and improve the performance of the radial flux permanent magnet brushless dc (PMBLDC) motor. newlineThe use of a permanent magnet (PM) material in place of electromagnetic excitation markedly increases the operational efficiency and reduces the motor size for the same output power. The radial flux PMBLDC motors are classified into two types according to the placement of PMs on the rotor. They are (1) the Surface Permanent Magnet (SPM) motor and (2) the Interior Permanent Magnet (IPM) motor. The radial flux PMBLDC motor offers high efficiency, high power density, compactness, wide speed range, high torque to current ratio, and fast dynamic response. In this research work, three different radial flux surface mounted PMBLDC motors of rating 200 W, 2.2 kW, and 20 kW are designed by assuming various design variables like air gap flux density, current density, slot space factor, winding factor, stacking factor, and allowable flux densities in the stator and rotor core. Finite element analysis (FEA) has been carried out to validate the analytical designs. The performance parameters and the flux density in various sections of the motors obtained from FEA are compared with the analytical designs. The comparison between analytical and FEA-based results validates the analytical designs. newlineCogging torque is an undesirable but inherent characteristic of slotted permanent magnet motors. It produces vibration, and annoying noise, and deteriorates the torque quality. It is inevitable to minimize cogging torque to improve the torque quality and performance of the radial flux PMBLDC motor. The three motors designed initially are considered reference motors. Their cogging torque profiles are obtained by performing FE analysis. Various design modification techniques have been proposed, focusing on the reduction of cogging torque. Comparative analysis is carried out between cogging torque obtained with and without design modifications to examine the effect of these techniques on cogging torque