Abstract Major decision driving constraints in the automobile sector is space and cost. With the advent of electric vehicles, these constraints apply for electric drive motor also. For applications involving neighborhood electric vehicles (NEV), the challenges become manifold with target cost of complete drivetrain system, including motor, controller & transmission, being very low. This and application of low cost axle mount drive systems prohibits usage of liquid cooled systems. In this scenario, ways to improve thermal performance of motor can be - to reduce heat generation, increase heat conduction and to increase heat rejection so that temperature of winding is kept under thermal limit of insulation used. Major area of thermal hotspots in the motor is at the end windings where direct conductive path to the housing is less. In this paper, thermal performance of the motor is improved by introducing vacuum encapsulation at the end winding thereby increasing net heat conduction. The encapsulation process affords better heat transfer from the coils to the frame, enhance winding rigidity, create total protection against moisture and prevent corrosion thereby improving the performance and life of the traction motors in applications such as electric vehicles. The process of impregnation & incorporation of silicon wedges is also eliminated. The analysis & validation of motors with different potting materials are done in bench level to compare its thermal performance. Introduction The major power loss in a motor happens through electrical and mechanical energy. Electrical loss comprises ohmic and core losses. Mechanical loss includes friction and windage loss. Ohmic losses share major percentage in total loss and are the main source of heat in stator winding. Most of the heat produced in stator winding is transferred to motor body or frame through (path is end winding to stator core to motor body) conduction and rest is dissipated to surrounding air by convection. Similarly, part of the heat produced in rotor is transferred to shaft by conduction and rest is dissipated to surrounding air by convection. The thermal impedance to convection is higher than conduction. To improve the thermal conductivity between end windings and motor body, thermally conductive material has been introduced. These materials offer very less resistance to heat, hence the heat transfer rate between end winding and motor body will be improved. The process of filling end windings, open areas of slots, cleats with thermally conductive material is called encapsulation. There are two ways to fill potting material. One is gravity pouring and other is vacuum filling. Gravity pouring takes more time to fill and doesn’t cover whole winding. Some parts of the winding remain unfilled, leads to thermal hot spots. Whereas, vacuum pouring covers whole winding and consumes less time as compared to gravity pouring. No thermal hot spots are formed in end winding with vacuum filling. Figure 1. Thermal flow paths (conductive and convective) in traction motor This paper discusses the vacuum encapsulation of traction motor, with different potting materials to increase its thermal performance, without changing any mechanical & electrical parameters. Vacuum Encapsulation of Traction Motor Vacuum encapsulation is process of filling a complete area around the end winding and slot gaps, Cleat to frame gap of stator assembly with a solid or gelatinous compound under vacuum to create total protection against moisture, prevent corrosion, improve heat transfer from the coils to the frame and enhance winding rigidity.Vacuum Encapsulation of Traction Motor for Better Thermal Performance2017-26-0098 Published 01/10/2017 Riaz Ahamed, Koorma Rao Vavilapalli, Clement Jones, and V P Abhijith M/s Mahindra Reva Electric Vehicles, Ltd. CITATION: Ahamed, R., Vavilapalli, K., Jones, C., and Abhijith, V ., "Vacuum Encapsulation of Traction Motor for Better Thermal Performance," SAE Technical Pape