Novel Lumped-Parameter Thermal Modelling. Part II: Thermal Models for Cylindrical Components and Application to Electrical Machines

The novel lumped-parameter thermal models (LPTMs) have been developed for a general cuboidal component in Part I. In this paper (Part II), the proposed thermal modelling method is developed for general cylindrical components in all 1-D directions, 2-D planes, and the 3-D solid. By introducing two compensation thermal resistances, both average and midpoint temperatures can be predicted, where the material anisotropy, the distributed loss generation, and the non-uniform heat flow are all considered. Afterwards, together with cuboidal LPTMs in Part I, the proposed LPTMs are further applied to establish a complete thermal network for a permanent magnet synchronous machine, whose prediction results exhibit excellent agreement with both the finite element analyses and experimental results. As will also be shown, the proposed LPTMs demonstrate high estimation accuracy, simple modelling complexity, and multi-temperature prediction capability in the thermal modelling of complex thermal systems, e.g., electrical machines.