Impact of Insulation and Cooling on Performance due to Reliability-Oriented Design of Electrical Machines

In this paper, a multiphysics model of a permanent magnet synchronous motor (PMSM) is created to investigate the influence of the cooling and insulation system on the temperature distribution and performance of the machine. In thermal computer fluid dynamic (CFD) studies, the influence of the coolant flow, the winding head impregnation and the insulation paper on the temperature distribution of the machine is investigated. Finally, the influence of thermal effects on the steady-state limit torque of the machine is evaluated. It is systematically shown that insulation materials with high thermal conductance allow torque increases of about 3.3%. Torque can be increased by about 1.9% per reduced 0.1 mm insulation thickness of the slot liner. Alternatively, the temperature impact on insulation can be reduced at constant torque leading to improved insulation lifetime and reliability.