In this study, cooling hole structures for an outer-rotor motor used in smart factory data center cooling systems were optimized to dissipate heat inside the motor. The Taguchi method (L9(34) design) was applied to identify dominant design parameters ...
In this study, cooling hole structures for an outer-rotor motor used in smart factory data center cooling systems were optimized to dissipate heat inside the motor. The Taguchi method (L9(34) design) was applied to identify dominant design parameters for the upper and side cooling holes. Under the optimal upper hole conditions 21 circular holes, 9 mm diameter, outer placement, and 0° inclination the motor exhibited enhanced internal airflow, reducing the temperatures of major heat sources by up to 22℃. The optimal side hole design, defined by a 15° arc angle, 24 mm height, left side placement, and 0° taper angle, mitigated vortex formation in the fin wake region and further decreased bearing temperatures by 2~6℃. When the two optimal structures were integrated, the temperatures of key regions decreased by 6~23℃, while requiring only a minor increase in torque (0.44 N·m) and power (81 W), corresponding to approximately 1% of an 8 kW system. Despite these additional demands, the integrated design effectively improved heat dissipation by combining direct cooling from the upper holes with convective enhancement from the side holes. Therefore, the proposed cooling hole structure offers a viable thermal management solution for outer rotor motors employed in smart factory data center applications.