New approach to longitudinal magnetic field in drum type machine

Without 3D analysis, the longitudinal distribution of the magnetic field in a drum-type electric machine can be determined two-dimensionally, provided that radial results, fundamental components of the air gap flux density related to each axially-separated part, are obtained in advance by any conventional 2D numerical method. Details on the new approach, including how to bound the domain, how to represent the problem and how to solve it, are presented. As an application, a new type of synchronous machine with a two-part rotor, having a surface permanent magnet part and an axially-laminated anisotropic reluctance part axially-separated on the same shaft, is investigated, with obvious high computational economy and improved accuracy.