Design Optimization with Flux Weakening of High-Speed PMSM for Electrical Vehicle Considering the Driving Cycle

In this paper, the design optimization of a nonsalient high-speed permanent magnet synchronous machine (PMSM) for electric vehicle applications is presented. It will be shown how, with a new approach, it is possible to find a deterministic solution to solve the sizing of the machine from a given driving cycle. The optimal geometry and the optimal control strategy over the cycle minimizing both the energy losses and the volume of the machine will be calculated. At first, the one-dimensional analytical model used is presented and validated for the most significant point of the driving cycle using a finite element method. Then, the design methodology and the results through a specific application are detailed. Particularly, it will be shown how the flux weakening, directly given by the design process via the optimization of the control strategy, allows reducing both the energy losses and the constraints on the power converter. At last, in order to validate the solution considering the whole cycle while keeping a reduced computation time, a reluctance network model of the PMSM is used. This model validate the energy losses and the flux densities in the steel parts over the cycle. The study will be done considering the urban dynamometer driving schedule.