Analysis of permanent magnet brushless AC motor using Fourier transform approach

Abstract

The paper presents an analytical model for determining performance characteristics of surface mounted permanent magnet brushless motor using Fourier transform technique. The proposed scheme assumes a simplified geometric model of surface mounted PM (SMPM) motor with dual current sheets using layer theory to analyse electrical machines. The layer theory considers regions of PMBLAC motor to be replaced by layers of respective homogeneous material properties. Isotropic model assumes stator to be sloltless while anisotropic model is also considered to account for stator slotting effect on the motor performance. The Fourier transform applicable to linear induction motor and introduced by S. Yamamura is modified and adapted for analysing PMBLAC motor. The primary stator winding and permanent magnets on rotor are replaced by their respective equivalent linear current densities. The proposed model is validated using experimental results from a 12-slot surface mounted PMBLAC motor. The proposed method is capable of calculating the effect of design parameters on the performance of the SMPM motor, thus making it suitable for design and optimisation at initial stage. Moreover, analytical validation is also presented to prove the effectiveness of the proposed method.