Metamodel-based Design and Optimization of a Spoke-Type Interior Permanent Magnet Machine for a Vehicle Traction Application

Interior permanent magnet machines are a popular solution for traction applications. Within the frame of this paper, an air-cooled spoke interior permanent magnet machine is designed and optimized with respect to the maximum average torque and minimum magnet mass. Several performance constraints, such as the permissible torque ripple and the relative thermal loading, have been considered in the design workflow. A metamodel, (or surrogate model) optimization is utilized with the help of Ansys OptiSLang tool. Within an initial sensitivity study, the metamodel predicts the optimal design space which shortens the cumulative optimization time from typical 1-2 weeks to approximately one day. It is shown that this simplification marginally reduces the solution accuracy (±4 %). The obtained Pareto front is verified using the finite element analysis through Ansys Motor-CAD proving that the selected optimized design meets all set requirements. The novelty of the proposed design is reflected in the combination of pole shaping strategy and rotor mass minimization by implementation of inter pole holes.