Thermal Analysis of Water-Cooled Totally Enclosed Non-Ventilated Induction Motor

The electric motor industry has witnessed fast growth in recent years thanks to adoption of electrical vehicles, expansion of data center and increasing demand of higher efficiency across industries. Other features of the motor, including compact structure and winding encapsulation, are also desired. These requirements consequently lead to excessive temperature rise which is detrimental to the safe operation of machines. Thus, effective thermal management in electric motors attracts growing interests in motor design as well as manufacturing. This paper summarizes efforts made on motor thermal management, especially in water-cooling strategy for totally enclosed non-ventilated induction motor with polymer encapsulated stator windings. Based on the lesson learned through theoretical study, a water-cooling system composed of a single-turn copper tubing wound around the end-windings of an induction motor is prototyped and tested. The thermal test demonstrates the effectiveness of water-cooling which leads to over 60 % reduction in temperature rise compared to a regular non water-cooled motor. At the same time, minimal impact of this cooling construction on the no-load losses suggests the presence of copper cooling circuit next to the end-winding does not have noticeably negative impact on the machine losses.