IMECE2003-42512 THERMAL MODELING OF A LIQUID-COOLED PM TRACTION MOTOR

Abstract

ABSTRACT The electric motor plays a critical role for the applications of the Hybrid Electric Vehicle and Fuel Cell Electric Vehicle. It is also well known that thermal constraints represent one of the main limitations in the performance of the electric motor. For example, the electric motor will be short-circuited if the insulation coatings of the copper wire bundles fail. Furthermore, the performance of the permanent magnet electric motor reduces significantly as the rotor magnet temperature increases. In this study, a series of Computational Fluid Dynamics analyses were performed for the design of a liquidcooled permanent magnet electric motor to achieve better thermal performance. Several thermal tests of a partial permanent magnet traction motor assembly (stator and housing only) were also performed to determine effective properties of the stator slot and thermal contact resistance between stator and housing that may vary due to the manufacturing process. A simplified thermal network model of this system was established from the Computational Fluid Dynamics analyses. Then the critical heat transfer path of this system was identified. Keywords: thermal modeling, liquid-cooled, traction motor INTRODUCTION In order to improve fuel economy and reduce emissions, the Hybrid Electric Vehicle (HEV) and Fuel Cell Electric Vehicle (FCEV) are receiving much attention in the automotive industry. An HEV obtains its power by combining a gasoline engine with an electric motor and a battery. By linking these three components, the HEV improves fuel economy and reduces emissions by increasing average engine efficiency. The electric motor can also be used to boost power and enhance performance. In an FCEV, the powertrain combines the lowemission, high-efficiency fuel cell engine with an electric drive system. Therefore, the performance of the electric motor plays a critical role for these two types of vehicle. Design requirements for an automotive electric traction drive syste