An Analytical Expression for Magnet Shape Optimization in Surface-Mounted Permanent Magnet Machines

Ali Jabbari

doi:10.3390/mca23040057

Abstract

Surface-mounted permanent magnet machines are widely used in low and medium speed applications. Pulsating torque components is the most crucial challenge, especially in low-speed applications. Magnet pole shape optimization can be used to mitigate these components. In this research, an analytical model is proposed to calculate the magnetic vector potential in surface-mounted permanent magnet machines. A mathematical expression is also derived for optimal the magnet shape to reduce the cogging torque and electromagnetic torque components. The presented model is based on the resolution of the Laplace’s and Poisson’s equations in polar coordinates by using the subdomain method and applying hyperbolic functions. The proposed method is applied to the performance computation of a surface-mounted permanent magnet machine, i.e., a 3-phase 12S-10P motor. The analytical results are validated through the finite element analysis (FEA) method.

Highlights

Surface-mounted permanent magnet machines are interested in high-performance applications because of their high efficiency and power density
An extensive variety of techniques such as magnet skewing [1,2,3,4], magnet-arc optimization [5,6,7,8,9], magnet shape optimization [10], and magnet displacing [2,3,4,7,8,9] for minimizing cogging torque in permanent magnet motors is documented in the literature
The subdomain model is more accurate than the other analytical models [15]

Summary

Introduction

Surface-mounted permanent magnet machines are interested in high-performance applications because of their high efficiency and power density. A variety of techniques including analytical and numerical methods have been conducted to evaluate the pulsating torque components in electrical machines. According to Reference [37], the Dubas’ superposition technique [35,36] is very interesting since it enables the magnetic field calculation in the material of slotted geometries This technique has been implemented in radial-flux electrical machines considering finite soft-magnetic material permeability [34]. Tthee pulsating torque coDmupboasn’sensutsp.erposition technique could have been used to develop a new model with the The cfooncsuidseraotfionthoifsthpeasapteurratiisonteoffedcet.rIinvReefaernenacensa[l3y8–ti4c1a],lanexanparleytsiscaiol mnofdoerl htahs ebeeonpitnitmroadlucmedagnet pole to compute electric machine performance by using the subdomain method. .IItt iiss sshhoowwnnthtaht athtetdheevreelospueldtsmoofdtehl ceaannefafleycttiivcealyl mestoimdeatleatrhee imnacglnoestiec agreement with the rfeieslud,ltcsogogfinthg etoFrqEuAe, emleecttrhoomda.gnetic torque, back electromotive force and self/mutual inductance This model is applied to the performance calculation of a surface‐mounted permanent magnet motor, 2.

Parallel Magnetization

Model Evaluation

Conclusions