Performance evaluation and thermal analysis of interior permanent magnet traction motor over a wide load range

This paper investigates the electromagnetic and thermal behavior of a Double Layer Interior Permanent Magnet Motor (DLIPMM) over a wide load and speed range for an Electric Vehicle (EV) application. The DLIPMM is simulated via a transient 2D Finite Element (FE) model, allowing for the accurate mapping of the motor's main performance indexes. Simulations are performed for armature currents ranging from zero up to two times the nominal for all possible current phase angles and the torque and efficiency versus speed curves for a wide load range are extracted. The Maximum Torque per Ampere (MTPA) control for the Constant Torque Region (CTR) is employed, provided that the voltage constraints are not violated. For the Constant Power Region (CPR) a specific Field Weakening (FW) strategy is utilized in order to achieve an efficient motor drive. In a next step, a transient thermal FE model for the DLIPMM over a reference EV drive cycle and under abrupt overload condition is employed, in order to investigate the motor thermal robustness. The results demonstrate the benefits of the designed DLIPMM configuration, in terms of performance, efficiency, overload capability and thermal robustness.