Lumped Parameter Thermal Modeling of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors (PMSMs) are often used in automotive applications due to their high power density. In the design process of electrical machines, the analysis of heat transfer is of equal importance as their electromagnetic one, because the temperature rise of the machine eventually determines the maximum output power with which it is allowed to be constantly loaded. Overheating in PMSM has a negative impact on the machine due to the phenomenon of demagnetization of the Permanent Magnets (PMs) as well as due to the thermal ageing of insulation. This paper deals with the thermal modeling of PMSM using Lumped Parameter Thermal Network (LPTN) and FE (Finite Element) model. Through analogy with the electrical circuits, the thermal network of the machine consists of thermal resistances and thermal capacitances. The power losses are represented in this equivalent circuit by current sources. Each part of the machine is represented by a node. Based on the intended node locations, the machine has been divided into sub-elements for which the thermal resistances and capacitances have been calculated by using Matlab-script for different geometric shapes. The temperature rise of the machine has been calculated by solving the network using two electrical circuits simulators, namely LT-spice and Matlab-Simulink.