Research in Engineering and Aviation

Analytical calculation of open-circuit magnetic field distribution of slotless brushless PM machines

January 2013

Author(s): Rahideh, A., Korakianitis, T.

Journal: International Journal of Electrical Power and Energy Systems, 44 (1), pp. 99-114. doi: 10.1016/j.ijepes.2012.07.030


A comprehensive analytical open-circuit magnetic field distribution of slotless brushless permanent magnet machines with surface mounted magnets is presented for six different magnetization patterns. The stator and rotor back-irons are assumed to be finite permeable. Therefore, the analytical model covers five annular regions: rotor; magnet; air–gap/winding; stator; and exterior. The expressions of the five regions are presented in a convenient form to ease the numerical computation for both internal and external rotor motors. The induced back-EMF is also expressed analytically. The efficacy of the analytical model is validated by comparing the results with finite element analyses (FEAs).

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