Thermal and Flow Analysis of Outer-Rotor Type BLDC Motor with Cooling Blades

In this paper, thermo-flow characteristics of an outer-rotor type BLDC motor are numerically analyzed using three-dimensional turbulence modeling. On the rotor of the BLDC motor, cooling blades and cooling holes are existed for the enhanced cooling performances. Rotating the blades and holes generates axial air flow streaming into inner rotor side and passing through stator slots, which cools down stator by forced convection. Operating tests are performed and the numerical temperature fields are found to be in good agreement with experimental results. A new design of the BLDC motor has also been developed and major design parameters such as the arrangement of cooling holes, the area of cooling holes and cooling blades, and the cooling blade angle, are analyzed for the enhanced convective heat transfer rate. It is found that the convective heat transfer rate of the new BLDC motor model is increased by about 8.1%, compared to that of the reference model.