Spoke-type Permanent-magnet Machines Research Articles

Establishing the Relative Merits of Interior and Spoke-Type Permanent-Magnet Machines With Ferrite or <roman>NdFeB</roman> Through Systematic Design Optimization

In this paper, a multiobjective design optimization method combining design-of-experiments techniques and differential-evolution algorithms is presented. The method was implemented and utilized in order to provide practical engineering insights for the optimal design of interior and spoke-type permanent-magnet machines. Two combinations with 12 slots and 8 poles and 12 slots and 10 poles, respectively, have been studied in conjunction with rare-earth neodymium-iron-boron (NdFeB) and ferrites. As part of the optimization process, a computationally efficient finite-element electromagnetic analysis was employed for estimating the performance of thousands of candidate designs. Three optimization objectives were concurrently considered for minimum total material cost, power losses, and torque ripple, respectively. Independent variables were considered for both the stator and rotor geometries. A discussion based on a systematic comparison is included, showing, among other things and despite common misconception, that comparable cost versus loss Paretos can be achieved with any of the rotor topologies studied.

Analytical Prediction of Magnetic Field in Parallel Double Excitation and Spoke-Type Permanent-Magnet Machines Accounting for Tooth-Tips and Shape of Polar Pieces

This paper presents an analytical method based on subdomain method for the computation of open circuit, armature reaction, and on-load magnetic field distribution in integer slot winding parallel double excitation and spoke-type tangential permanent-magnet machines. The proposed model takes into account for stator and rotor slots tooth tips and shape of polar piece. A 2-D exact analytical solution of magnetic field distribution is established. It involves solution of Laplace's and Poisson's equations in semi-closed stator and rotor slots, air-gap, buried permanent magnets into rotor semi-closed slots, and nonmagnetic region under magnets. Obtained exact analytical results of open circuit, armature reaction, and on-load magnetic field distribution are verified with those issued from the finite element method.

Analytical Prediction of Cogging Torque for Spoke Type Permanent Magnet Machines

A generalized analytical field solution by conformal transformation is presented for calculation of no-load magnetic field distribution in the slot-less and slotted air gap of spoke-type permanent magnet (PM) machines. These analytical field solutions are used to predict the cogging torque of spoke-type PM motors. The computed cogging torque using the proposed method is compared with the results from 2D finite element analysis (FEA) in three application examples.