A Finite Element–Analytical Method for Electromagnetic Field Analysis of Electric Machines With Free Rotation

A hybrid approach, namely the finite element-analytical method (FEAM), is newly proposed and implemented for electromagnetic field analysis of electric machines with free rotation. The key is to derive a new analytical expression of the airgap field which can naturally couple with the finite element fields of both the stator and rotor. The proposed FEAM is exemplified by using two practical machines. The accuracy and validity are verified by comparing with both the finite element method and experimental results