Thermal-flow analysis and cooling performance enhancement of a totally enclosed fan-cooled motor

Cooling performance of rotating machines is one of the critical qualities determining product lifespan. As power density of the machines is considerably increased, enhancement of the cooling performance is required in order to secure thermal safety and prevent failure such as dielectric breakdown. In this paper, thermal-flow analysis using CFD (computational fluid dynamics) was carried out to evaluate temperature rise of a TEFC (totally enclosed fan-cooled) motor of which power density had been improved. From the analysis result, we investigated flow structures reducing cooling efficiency, such as bending loss, reverse flow and flow separation. In order to attenuate these negative phenomena, we modified cooling design for fan-cover, frame and end-shield of the motor. As a result, temperature rise of stator winding of the motor was decreased by 7.5%, from 97.4K to 90.1K. For reference, an error rate of the analysis result is 3.7% in comparison with the test result.