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Analytical Solution of Magnetic Field in Permanent-Magnet Eddy-Current Couplings by Considering the Effects of Slots and Iron-Core Protrusions
Journal of Magnetics, Volume 20, Number 3, 30 Sep 2015, Pages 273-283
Xin Dai (Shanghai Jiao Tong University), Qinghua Liang (Shanghai Jiao Tong University), Chao Ren (Shanghai Jiao Tong University), Jiayong Cao (Shanghai Jiao Tong University), Jinqiu Mo (Shanghai Jiao Tong University), Shigang Wang * (Shanghai Jiao Tong University)
Abstract

In this study, we propose an analytical model for studying magnetic fields in radial-flux permanent-magnet
eddy-current couplings by considering the effects of slots and iron-core protrusions on the eddy currents. We focus on the analytical prediction of the air-gap field by considering the influence of eddy currents induced in conducting bars. In the proposed model, the permanent magnet region is treated as the source of a timevarying magnetic field and the moving-conductor eddy current problem is solved based on the resolution of time-harmonic Helmholtz equations. The spatial harmonics in the air gap and in slots, as well as the time harmonics are all considered in the analytical calculation. Based on the proposed field model, the electromagnetic torque is computed by using the Maxwell stress tensor method. Nonlinear finite element analysis is performed to validate the analytical model. The proposed model can be used for permanent-magnet eddy-current couplings with any slot–pole combination.


 

Keywords: eddy current coupling; iron-core protrusion; permanent magnet; slotting effect; subdomain model
DOI: http://dx.doi.org/10.4283/JMAG.2015.20.3.273
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