A New Reluctance Model of a Claw Pole TFPM Using SMC for the Magnetic Circuit Amina Ibala, Ahmed Masmoudi E-mail: amina ibala@yahoo.fr, a.masmoudi@enis.rnu.tn Research Unit on Renewable Energies and Electric Vehicles University of Sfax, Sfax Engineering School P.B. W, 3038 Sfax, Tunisia Glynn Atkinson, A.G.Jack E-mail: g.j.atkinson@ncl.ac.uk , alan.jack@ncl.ac.uk Department of Electrical & Electronic Engineering University of Newcastle upon Tyne Newcastle upon Tyne, NE1 7RU, England   Copyright c  2009 MC2D & MITI Abstract: The paper is aimed at the elaboration and the validation of a 3D reluctance model of a claw pole TFPM. This machine consists of a one-phase prototype made up of an SMC-made stator magnetic circuit with claw poles facing the air-gap. In the rotor, the permanent magnets are arranged in a surface-mounted topology. Compared to a model available in the literature, the proposed one takes into account of further leakage fluxes. The no-load linkage flux obtained by the proposed 3D reluctance model has been compared with the one obtained by 3D finite element analysis. The results yielded by both methods show a good agreement. Keywords: Transverse flux permanent magnet machines, claw pole topology, soft magnetic composite, reluctance model, finite element analysis, linkage flux. 1. Introduction Claw pole structures are inherently capable of producing high specific output torque when used in electrical machines. They are also simple to manufacture especially when they are made up of soft magnetic composites (SMCs) [1]. SMCs are isotropic and can be compacted into complex shapes. These characteristics are of great importance for the features of transverse flux permanent magnet machines (TFPMs) in so far as SMCs fulfil the requirements for an efficient flow of flux within three dimensional (3D) paths [2]. 2. TFPM Features 2.1 Feasibility of High pole number In a TFPM, all of the poles contribute to the flux linking the winding. This means that as pole number rises, although there is a smaller contribution of flux from each pole, there is no decrease in the overall flux linking the wind- ing. Hence the rate of change of flux linking the winding increases with the pole number. This would lead, at a first glance, to an increase of the torque. However, increasing the pole num- ber yields a decrease of the flux per pole and the torque turns to be almost independent of the machine polarity.