Thermal Analysis of a Small, Totally Enclosed, Fan-Cooled Induction Motor.

Improving cooling performance is a key factor when developing induction motors in smaller sizes with larger capacities and higher rotational speeds. Doing so, however, requires thermal analysis to discover the major parameters in the cooling design. This study investigates temperature distributions and heat transfer rates in a small, totally enclosed, fan-cooled induction motor with both numerical and experimental methods. Parametric studies show that (1) the frame is of the utmost importance in the design and (2) that cooling the motor close to stator coils is the most effective method for cooling. Quantitative analyses show the relationship between the size of the motor and the rise in coil temperature. The results from transient and steady-state experiments using a real motor show that (1) the hottest spot is in the rotor surface, and (2) the load-side surface has a higher temperature than that of the fan-side. The hottest spot in the stator coils is the outer surface of the load-side endwinding. The coil temperature is also significantly affected by the attached components of the frame, as well as the contact state between the stator iron and the frame. It is recommended that the current outer fan be redesigned to improve cooling performance. [ABSTRACT FROM AUTHOR]