Cobalt Iron Core Impact on Optimal Design of an Interior Permanent Magnet Synchronous Motor for Competition Electric Vehicle

To analyze the impact of cobalt iron cores in the design of interior permanent magnet synchronous motors (IPSM) for competition electric vehicles, a spoke-type IPSM geometry is optimized considering FeSi and VaCoFe cores. This optimization is done for a range of torque/efficiency, to provide a general comparative analysis between materials considering the application of a FormulaStudent 4-motor competition car's powertrain. A genetic optimization algorithm (NSGA-II) is applied over a hybrid analytical/finite-element model of the motor to provide sufficiently accurate electromagnetic and thermal results within a feasible time. It is shown that machines with VaCoFe core are a better alternative across both considered torque and efficiency ranges. VaCoFe can result in an estimated increase of up to 3% in efficiency for the same torque, or up to 70% torque increase for the same efficiency level. However, because of the density difference between materials, core weight is similar for the overlapping torque range. For the competition car, with a required 20Nm of nominal torque, there is an efficiency increase of 1.7% and a reduction of 11% in core volume for the motor with VaCoFe compared to FeSi.