Highly Compact Electric Drive for Automotive Applications

The penetration of hybrid or purely electric drivetrain solutions in automotive applications increases continuously, benefiting also from the rapid advancements in the complementary technologies related to the on-board electric energy generation and storage. The automotive community has made a strong commitment to the development of fuel cells into viable products during the next decade, and there are already several hybrid vehicle designs successfully commercialized. The current electric drive configurations are susceptible to significant improvements with respect to weight and envelope dimensions versus torque and power capacity. This paper introduces a compact wheel end power unit concept that integrates advanced motor, package bearing, and gear technologies, and summarizes the development work related to its integration with the specific components of an automotive driveline. The resultant electric drive is evaluated under different technical and commercial criteria, including performance, power density, ease of assembly, complexity and cost. Based on both analytical model predictions and performance test results, the wheel-end electric drives presented in the paper are very well suited for a wide range of vehicle platforms, as compact and efficient drive modules.