Development of electric vehicle that uses soft magnetic composite core and does not use permanent magnet

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A novel topology optimization method has been proposed for the material distribution of electrical motors using the Genetic algorithm combined with the cluster of material and the cleaning procedure. The cluster of several kinds of material is taken into account not only to form the group of iron and the group of air but also to form the group of the r-oriented, x-oriented and y-oriented magnets. Consideration of air, iron and the r-oriented magnet gives a surface permanent magnet type rotor, and consideration of air, iron and the x-oriented and y-oriented magnets gives an interior permanent magnet type rotor. As a result, it was found that permanent magnets are very useful to produce a large torque.In order to develop a motor for electric vehicle without using permanent magnets, a switched reluctance motor with 18 stator slots and 12 rotor slots is designed. It is designed to produce a large average torque more than 400N・m by using the experimental design method coupled with 2-D finite element analysis, where the conventional shape of SRM is chosen as the initial shape to be designed. Eight parameters are chosen as design variables, which define the whole shape of stator teeth and rotor teeth with the assumption of a constant motor volume and a constant air-gap length. An algorithm for an asymmetric bridge converter coupled with finite element method is developed, and then the torque speed characteristics are investigated. The designed SRM has been manufactured.Moreover, a method for generating a music scale from a brushless DC motor with surface permanent magnets has been proposed by introducing a d-axis current with a desired frequency. The proposed method is theoretically verifies by analyzing the vibration emitted from the brushless DC motor. The proposed idea could be applicable to systems emitting a loud acoustic noise from HVs or EVs.