Analytical Optimization of Surface-Inset Machines With Eccentric Three-Piece Halbach Magnets

An analytical model of a surface-inset permanent magnet (PM) machine with eccentric three-piece Halbach magnets is proposed. An analytical optimization technique for the proposed model is used to obtain the optimal eccentric height that minimizes the total harmonic distortion (THD) of the air-gap flux density. Compared with the concentric model, the optimized eccentric model has the better electromagnetic performances including the back-electromotive force (EMF), the air-gap field and the electromagnetic torque. The presented analytical predictions are validated by a finite element analysis (FEA).