The windings concentrated around the teeth offer obvious advantages for the electric machines with radial air-gap, because the volume of copper used in the end-windings can be reduced. The Joule losses are decreased and the efficiency is improved. These machines are still limited to applications of subfractional power and they generally present a reduced number of phases. In the three-phase machines, the concentrated winding is too often restricted to a winding with a short pitch of 120 electric degrees, i.e. to a winding with performances reduced compared to the traditional structures. But there is a significant number of three-phase structures which can support a concentrated winding if the number of poles is increased. In this article, the author present a synthesis of the structures of three-phase machines with concentrated windings. In the first part, the structures with a regular distribution of the slots are presented. A systematic method is proposed to determine the windings and the performances are discussed. In the second part, the authors present original structures of three-phase machines with concentrated windings which use an irregular distribution of the slots. A specific method to identify these structures is described and a comparative analysis of the performances of the original and traditional structures is performed by using a field calculation software.

In this paper different methods are presented for the calculation of torque as a function of rotation angle in an electrical machine. These methods are integrated in a. calculation code by using the finite element method. The movement is taken into account by means of the technique of the Moving Band, constituted by quadrilateral finite elements in the airgap. The torque is calculated during the displacement of the moving part by using the following methods: Maxwell stress tensor, Coenergie derivation, Coulomb's v'irtual work, Arkkio' s method and the Magnetiz ing current method. The resul ts obtained by the different methods are compared with experimental data and.allow te deduce practical informat, ions concerning the advantages and limitations of each method.

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This paper presents a factorization method for the generation and use of several kinds of transformation matrices in specific structures of phase modulation polyphase motors. The method can be applied to an arbitrary phase number. It avoids complex trigonometric manipulations. Several examples illustrate its application to a seven-phase machine.