Thermal modelling for electrical machines fed with low voltage

Permanent magnet electrical motors are more and more currently used in car manufacture. A very constraining utilization reduces their life duration. Authors of this paper propose a new way to define reliability criterions of these low power machines. Most of internal fragility locations are winding insulations, ball bearings so that the system collector and brushes. Nowadays, statistical determination methods of the reliability criterions are very costly. For this reason, authors propose a new method consisting in the development of thermal models for different surrounding temperatures. It will also take into account degradation laws of constituting materials as functions of reached temperatures and life duration. This article will detail the initial validation of the thermal models for surrounding temperatures of 25 and 85 °C.