Integrated Cooling System for Induction Motor Traction Drives, CARAT Program Phase Two Final Report
- VPT, Inc., Blacksburg, VA (United States)
This Program is directed toward improvements in electric vehicle/hybrid electric vehicle traction systems, and in particular, the development of a low cost, highly efficient, compact traction motor-controller system targeted for high volume automotive use. Because of the complex inter-relationships between the motor and the controller, the combination of motor and controller must be considered as a system in the design and evaluation of overall cost and performance. The induction motor is ideally suited for use as a traction motor because of its basic ruggedness, low cost, and high efficiency. As one can see in Figure 1.1, the induction motor traction drive has been continually evolving through a succession of programs spanning the past fifteen years. VPT marketed an induction motor-based traction drive system, the EV2000, which proved to be a reliable, high performance system that was used in a wide range of vehicles. The EV2000 drives evolved from the Modular Electric Vehicle Program (MEVP) and has been used in vehicles ranging in size from 3,000 lb. autos and utility vans, to 32,000 lb. city transit buses. Vehicles powered by the EV2000 induction motor powertrain have accumulated over 2 million miles of service. The EV2000 induction motor system represents 1993 state-of-the-art technology, and evolved from earlier induction motor programs that drove induction motor speeds up to 15,000 rpm to reduce the motor size and cost. It was recognized that the improvements in power density and motor cost sought in the PNGV program could only be achieved through increases in motor speed. Esson’s Rule for motor power clearly states that the power obtainable from a given motor design is the product of motor speed and volume. In order to meet the CARAT Program objectives, the maximum speed goal of the induction motor designed in this Program was increased from 15,000 rpm to 20,000 rpm while maintaining the efficiency and durability demonstrated by lower speed designs done in the past. A primary goal of this program was the development of an efficient, reliable, 20,000 rpm induction motor traction system. Induction motors that have been built to operate in traction applications at speeds above 15,000 rpm employed special endring structures that resulted in unacceptably high motor costs. Present induction motor manufacturing use cast aluminum endrings to minimize cost, and have become relatively common in traction applications at speeds up to 10,000 rpm. The use of induction motors with cast aluminum for traction purposes at speeds above 10,000 RPM has not been explored. In addition to the improvements in power density and power volume promised through an increase in motor operational speed, this program also added significant improvements to the overall powertrain to improve the system reliability, system efficiency, and reductions in the system cost.
- Research Organization:
- VPT, Inc., Blacksburg, VA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC02-98EE50552
- OSTI ID:
- 1171520
- Country of Publication:
- United States
- Language:
- English
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