Analysis of an Interior Permanent-Magnet Machines with an Axial Overhang Structure based on Lumped Magnetic Circuit Model

Abstract

This paper shows a new magnetic field analysis of an interior permanent magnet (IPM) machines with an axial overhang structure wherein the rotor axial length exceeds that of the stator. The rotor overhang used to increase torque density of the radial flux machine is difficult to analyze because of extra consideration of axial direction, and thus it is general for machine designer to take 3-D finite element analysis (FEA) capable of considering both radial and axial complicated geometry in the machine. However, it requires too much computing time for preliminary design especially for optimization process. Therefore, in this paper a 2-D analytic method using a lumped magnetic circuit model (LMCM) is proposed to overcome the problem. For the analysis of overhang effect, the magnetic circuit is separated and solved from overhang and non-overhang regions respectively. For the validation of proposed concept, 3-D finite element analysis (FEA) is performed. From the analysis results, it is shown that our new proposed method presents good performance in terms of calculating electromotive force (EMF) and torque within a short time. Therefore, the proposed model can be useful in design of IPM with an overhang structure.

Analysis and Modeling of Axial Leakage for Spoke-Type Hybrid Permanent Magnet Machines

“…10 (b). The magnetic resistance caused by the axial leakage resistance flux can be calculated using the following equations [21], [22], [23], [24], [25], [26]. As PM 1 and PM 2 have different magnet types, the magnetic resistance corresponding to axial leakage is expressed as R ma_PM 1 and R ma_PM 2 , respectively.…”