A novel analytical calculation of magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping

Article type: Research Article

Authors: Li, Jianqi^a | Zhou, Yu^b; | Li, Jianying^a

Affiliations: [a] College of Computer and Electrical Engineering, Hunan University of Arts and Science, Changde, Hunan, China | [b] College of Electrical Engineering, Naval University of Engineering, Wuhan, Hubei, China

Correspondence: [*] Corresponding author: Yu Zhou, Mailbox 164, No. 717, Jiefang Avenue, Wuhan 430033, Hubei, China. E-mail: zhouyu_engineer@hotmail.com

Abstract: This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

Keywords: Magnetic field, permanent-magnet machines, conformal transformation, spoke-type, slots

DOI: 10.3233/JAE-201505

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 4, pp. 609-622, 2021