New design and optimization of an in-wheel permanent magnet motor with tangentially magnetized magnets and unequal stator teeth

Lassaad Zaaraoui – Ali Mansouri

   Permanent magnet synchronous machines (PMSM) are competitive motors for in-wheel traction systems of electric vehicles. A new tangentially magnetized permanent magnets machine with outer rotor and unequal stator teeth for in-wheel motor application is proposed in this paper. The analytical calculations of the proposed topology are presented by determining the magnetic flux densities and the iron losses in all parts of the machine. The machine design is optimized using three state-of-the-art multiobjective algorithms which are AbYSS, MOCell and NMOPSO algorithms. Moreover, the optimization procedure is carried out according to three objectives: the maximization of the machine efficiency and the minimization of the mass and ripple torque. The optimization results showed that all the algorithms can find a set of optimal solutions and that the NMPSO algorithm outperforms the other two techniques. The finite element method (FEM) is used to investigate the optimization results. It is observed some magnetic saturation in the rotor yoke and the magnet’s extremes. The value of the induction in these machine regions is about 1.9 T. The comparison between the FEM and optimization results proved the rationality of the proposed optimization procedure.

Keywords: In-wheel motor, tangentially magnetized permanent magnets, unequal stator teeth, multiobjective optimization, finite element method

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