Thermal and dynamic modelling of permanent-magnet synchronous motors (PMSM) driven electric vehicle powertrain with dual-loop control strategy

Abstract

This paper presents a comprehensive electro-thermal model of a Permanent Magnet Synchronous Motor (PMSM)-driven electric vehicle (EV) powertrain integrated with a dual-loop control strategy for dynamic speed and current regulation. The model was developed in MATLAB/Simulink for speed tracking and torque response under varying load conditions. Thermal ports corresponding to the stator windings (HA, HB, HC) and rotor core (HR) were activated to capture heat transfer behaviour during operation. Simulation results demonstrated that the proposed control system effectively maintained the reference speed of 3,500 rpm across all torque levels, with rapid settling time (∼0.4 s). An observed trend indicated that higher load torque resulted in faster convergence to the reference speed, accompanied by higher current demand and increased thermal stress, most notably within the rotor core. When sequential load torques were applied up to 120 Nm, temperatures exceeded safe limits, leading to thermal runaway. To address this, a three-stage proportional cooling strategy was implemented, successfully limiting temperature rise below 120 °C and restoring steady-state operation without derating. The results validate the importance of integrated electro-thermal modelling and staged cooling control in improving the reliability, safety, and performance of PMSM-based EV powertrains.