Axial flux PM BLDC motor design methodology and comparison with a radial flux PM BLDC motor


Abstract: The aim of this paper is to develop a methodology to design an axial flux permanent magnet brushless direct current (AFPM) motor for a washing machine and compare the results with a conventional radial flux permanent magnet brushless direct current (RFPM) motor with the same power ratings. The AFPM motor is designed based on the maximum power density for an optimum inner-to-outer diameter ratio by using the reference RFPM motor constraints, such as the same rated torque at the rated speed. Both motors use the same materials in terms of lamination, permanent magnet, and conductor. They both use ferrite magnets; however, the AFPM motor has a surface-mounted structure and the RFPM motor has a buried one. The algorithm is used to determine the motor dimensions such as motor diameters, lengths, and the number of turns. The optimum number of poles considered for the design is chosen. Both motors are analyzed by finite element method (FEM) to verify the analytical approach and are compared in terms of power density, torque density, total weight and volume, torque ripple, and efficiency.

Keywords: Permanent magnet machines, brushless motors, finite element analysis, electric motors, AC motors

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