Fast Determination of Feasible Torque-Speed Range for Variable Flux Machines Including Remagnetization Voltage Limit

Paper in proceeding, 2025

This paper presents a computationally efficient method for determining the feasible operating range of Variable-Flux Machines (VFMs) under inverter voltage constraints. Re-magnetization transients in VFMs demand substantial current and armature flux, resulting in elevated voltage requirements and pronounced speed limitations. To address this, the proposed approach leverages precomputed Finite Element Analysis (FEA) flux and magnetization maps to define torque-speed boundaries under voltage-limited conditions while considering the high voltage demand during remagnetization, eliminating the need for iterative field simulations or FEA co-simulation. The method is validated through driving cycle simulations, demonstrating the reduction in available traction and braking torque due to the inability to re-magnetize the machine beyond the voltage-speed limit. The results provide key insights for optimizing magnetization state control and mission profile planning in traction applications using VFMs.