Research on temperature rise characteristics of built in permanent magnet synchronous motor coupled with magnetic thermal flow field

Frequency converters serving as power sources for integrated permanent magnet synchronous motors (IPMSMs) introduce significant time-harmonic distortions in current waveforms, leading to harmonic contamination of electromagnetic fields during variable-frequency operation. These harmonics induce parasitic eddy currents and energy dissipation in stator cores, rotor assemblies, and permanent magnets, causing localized overheating that threatens operational reliability through accelerated insulation aging and demagnetization risks. This study addresses transient thermal accumulation in a 12-pole/36-slot high-torque-density IPMSM prototype by developing a multi-physics numerical framework correlating harmonic frequencies, loss distribution, and temperature evolution. Through first-principles analysis, we quantify rated operational losses including volumetric heat generation, hysteresis losses, eddy currents, and ohmic dissipation. The proposed electromagnetic-thermal coupling model, validated with a deviation of less than 5% from thermometric system, demonstrates thermally-induced electromagnetic performance degradation:a 12.7% reduction in radial force harmonics and 9.2% airgap flux density attenuation across 20-120°C, attributed to permanent magnets negatives’ temperature coefficient altering the magnetomotive force distribution. These finding provide critical insights for improving lifespan of IPMSM systems.