Calculation of the magnetic field in the eccentric air gap of an alternating pole radial magnetic coupling
TIAN Jie
ZHENG Zhongwen
REN Tai'an
WANG Xingdong
WU Songrong
Abstract：[Objective]The eccentricity of the inner rotor is shown to affect the air-gap magnetic flux density of alternating pole radial magnetic couplings,which subsequently influences their performance.To calculate the no-load air gap magnetic field under the inner rotor eccentricity,a computational method based on equivalent transformation was proposed.[Methods]The model was equivalently transformed by converting the original coupling with non-uniform air gap distribution and uniform residual magnetization into an equivalent structure with uniform air gap distribution but non-uniform residual magnetization on the inner rotor,while maintaining consistent structural parameters.Subsequently,the equivalent model was divided into three sub-domains:the inner rotor region,air gap region,and outer rotor region,followed by separate analyses of each sub-domain.Finally,the air gap magnetic field under eccentric conditions was derived using magnetic field boundary conditions.At the same time,the electromagnetic torque variation was analyzed under different eccentricities and different mechanical angles,and was compared with the finite element simulation results.[Results]The results demonstrate that the analytical solutions for electromagnetic torque achieve a relative error margin within 1.1%across varying eccentricity levels and remain accurate within 0.1 N·m deviation at different mechanical angles.These findings confirm the effectiveness of the proposed equivalent transformation method in calculating eccentric air gap magnetic fields for alternating pole radial magnetic couplings.
Keywords：Alternating pole radial magnetic couplingRotor eccentricityAir gap magnetic fieldEquivalent transforma-tionFinite element method
Publication Date：2025-06-15
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：7( 71-77 )