Permanent magnet motors with rare earth magnets are amongst the best candidates for high performance applications such as automotive. However, due to their cost and risks relating to security of supply, alternative solutions such as ferrite magnets have recently become popular. In this paper the two major design challenges of using ferrite magnets for a high torque density and high speed application, namely their low remanent flux density and low coercivity, are addressed. It is shown that a spoke type design utilizing a distributed winding may overcome the torque density challenge due to a simultaneous flux concentration and reluctance torque possibility. Furthermore, the demagnetization challenge can be overcome through careful optimization of the rotor structure, with the inclusion of non-magnetic voids on the top and bottom of the magnets. To meet the challenges of the high speed operation an extensive rotor structural analysis has been undertaken, during which electro-magnetics as well as manufacturing tolerances are taken into account. The electromagnetic studies are validated through testing of a prototype, custom built for static torque and demagnetization evaluation. The disclosed motor design surpasses the state of the art performance and cost, merging the theories into a multi-disciplinary product.

This paper presents a comprehensive overview of the latest studies and analyses of the cooling technologies and computation methods for the automotive traction motors. Various cooling methods, including the natural, forced air, forced liquid and phase change types, are discussed with the pros and cons of each method being compared. The key factors for optimizing the heat transfer efficiency of each cooling system are highlighted here. Furthermore, the real life examples of these methods, applied in the latest automotive traction motor prototypes and products, have been set out and evaluated. Finally, the analytical and numerical techniques describing the nature and performance of different cooling schemes have been explained and addressed. This paper provides guidelines for selecting the appropriate cooling methods and estimating the performance of them in the early stages of their design. Index Terms-Automotive applications, cooling, traction motors, thermal analysis, numerical analysis. NOMENCLATURECross section area of heat path (m 2 ). , Linear current density (kA/m). , Inlet and outlet cross section areas (m 2 ). Specific heat capacity (J/kg). Diameter (m). , Friction loss factor (dimensionless). Gravitational attraction force (m/s 2 ). Grashof number (dimensionless). Fin extension (m). ℎHeat transfer coefficient (W/m 2 K). ℎLatent heat (kJ/kg). Loss coefficient (dimensionless).

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This paper presents various solutions for the power traction motors of electrical vehicles. Equivalent designs to those commercially available on the roads are investigated. Potential simple modifications of the winding configurations and cooling system are studied: (a) flat wire (hairpin) winding vs stranded round wire in induction, synchronous permanent magnet and wound field machine topologies, (b) winding material grades effect-copper vs aluminum, (c) cooling systems-water jacket vs spray, fluid properties and flow rate.