Finite Element-based Multi-objective Design Optimization of IPM Considering Saturation Effects for Constant Power Region of Operation

This paper proposes a Finite Element (FE)-based multi-objective optimization procedure, under a set of constraints, for interior permanent-magnet synchronous machines (IPMSMs) to achieve a wide constant-power region of operation taking saturation effects and multiple operating points into account. Nonlinear models of the d-q flux linkages are derived based on magnetostatic FEA, which can significantly enhance computational efficiency with good accuracy (only 6 seconds per tentative design using a common PC). A new numerical method conforming to MTPA and flux weakening is presented based on the nonlinear models of the d-q flux linkage. Furthermore, this paper proposes to combine the new numerical method with the magnetostatic FEA using the differential evolution (DE) optimization algorithm to optimize the machine performance to achieve a wide constant power speed range (CPSR). Any operating points (different current/torque and speed) within the torque and speed boundary requirements can be also incorporated in the optimization procedure. Furthermore, saturation effects and multiple operating points are considered in the proposed optimization procedure. The design optimization procedure has been employed to recently developed low-cost IPM with a blend of magnet types. The proposed optimization procedure can be extended to other types of electrical machines.