In this paper, we exploit the multiple symmetries and the discrete character of the current distribution to express the torque and the radial forces in a PM synchronous machine. Under some assumptions, the magnetic field can be built with a limited number of discrete functions. These functions can constitute an orthogonal base of a vector space for the representation of the machine magnetic state. The representation of the stator and rotor fields as vectors of this space makes it possible to interpret the torque and the radial forces from the concept of distance between these vectors. The proposed method for torque and radial forces computation is well suited for a real-time evaluation and can be used for a generalization of the Field-Oriented Control to machines with non-sinusoidal flux distribution. Copyright (C) 2007 John Wiley & Sons, Ltd.

In this paper we investigate how to control the electromagnetic torque in a PM synchronous machine on the basis of a discrete modeling of the airgap field along the airgap. It is shown that a discretisation step corresponding to the spacing between the stator slots even if coarse allows a quite accurate torque control both for normal operation or fault conditions (loss of one phase). This allows to perform the torque control on the basis of look-up tables giving in function of the rotor position the values of the currents which must be injected in the active phases. The very small size of the look up tables and the low computational power needed should allow an easy implementation on a small FPGA. Experiments on a 1 kW machine confirm the theoretical results.

This paper proposes one approach for the ecodesign of an auxiliary transformer for the railway traction based on optimization methods. This approach is well suited to electrical devices that are very energy consuming and/or have a long life. A multiobjective problem is expressed to find the trade-off between the conflicting goals of the designer. The first one is to minimize the mass of the transformer and its cost. The second goal is to reduce the emission of gazes that contribute to green house effect. The life cycle analysis is used to build a model of the contribution to the global warming from the raw material extraction to the end of life of the product. This model is used jointly with economic and electromagnetic models in a multiobjective optimization to find the trade-off between the designer's goals, helping him to take a decision.