Abstract
High power density outer-rotor motors commonly use water or oil cooling. A reasonable thermal design for outer-rotor air-cooling motors can effectively enhance the power density without the fluid circulating device. Research on the heat dissipation mechanism of an outer-rotor air-cooling motor can provide guidelines for the selection of the suitable cooling mode and the design of the cooling structure. This study investigates the temperature field of the motor through computational fluid dynamics (CFD) and presents a method to overcome the difficulties in building an accurate temperature field model. The proposed method mainly includes two aspects: a new method for calculating the equivalent thermal conductivity (ETC) of the air-gap in the laminar state and an equivalent treatment to the thermal circuit that comprises a hub, shaft, and bearings. Using an outer-rotor air-cooling in-wheel motor as an example, the temperature field of this motor is calculated numerically using the proposed method; the results are experimentally verified. The heat transfer rate (HTR) of each cooling path is obtained using the numerical results and analytic formulas. The influences of the structural parameters on temperature increases and the HTR of each cooling path are analyzed. Thereafter, the overload capability of the motor is analyzed in various overload conditions.
Highlights
Nowadays, energy shortage and environmental pollution are two increasingly serious problems in the world
Determining the heat dissipation mechanism of this type of motor and calculating the limit values in various overload conditions are necessary to develop a reasonable design for the cooling structure of an air-cooling motor
The new method is more accurate than the conventional method in terms of the equivalent thermal conductivity (ETC) calculation
Summary
Energy shortage and environmental pollution are two increasingly serious problems in the world. A reasonable thermal design of outer-rotor air-cooling motors can effectively enhance the power density without the fluid circulating device. This enhancement is a direction for the further development of in-wheel motors. For the outer-rotor air-cooling motors, the heat generated from the stator mainly transfers to the end caps and enclosure through the air-gap. If this type of motor adopts the ETC method, the accuracy of the air-gap ETC must be ensured. Thereafter, the overload capability of the motor is analyzed in various overload conditions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
