Multidisciplinary Analysis of Permanent Magnet Machines Considering Thermal Contact Resistance

In this contribution, a multidisciplinary analysis is performed on a permanent magnet synchronous machine for electric vehicle applications by studying its electromagnetic and thermal performance. The influence of the magnet depth on both the electromagnetic losses and the temperature distribution in the machine is investigated for a given cooling concept. Moreover, the thermal contact resistance, which is rarely considered for rotor thermal analysis in literature, is taken into account. To avoid critical conditions of the magnet that could lead to demagnetization, each parameter that influences the thermal behavior has to be included in simulation. The study underlines the importance to calculate magnet temperatures already during the early development stage, since significant differences in maximum magnet temperature are found for the different designs. A rotor-field analysis proposed in this paper is used to identify rotor topologies that are expected to be critical in terms of magnet temperature. Furthermore, by considering different combinations of loss implementation, magnet position and thermal contact resistance, the influencing parameters of the magnet position on temperature distribution is discussed. The presented work demonstrates how the proposed method allows to identify whether or not the thermal contact resistance has a relevant influence and needs to be investigated further for a given rotor topology.