A CONCEPT FOR AN ELECTRIC VEHICLE WITH WHEEL HUB DRIVES FOR IMPROVED VEHICLE DYNAMICS AND PACKAGE EFFICIENCY

摘要

As the most efficient usage of limited traffic areas for individual traffic is highly desired, this paper describes a new concept for an energy and space efficient passenger car driven by electric wheel hub drives at the rear axle. It is characterized by enhanced vehicle dynamics, energy efficiency, manoeuvrability and safety, as well as by an improved ratio of usable volume to ground area. This project's aim is to enable wheel hub drives to be used in marketable mass production cars for the first time. Within this project, two main approaches are carried out in parallel. While the overall vehicle concept, packaging and design of body and chassis systems, are done in a virtual development environment, the drive and brake systems are fully developed and realized in hardware. The development of the vehicle dynamics controls is done both by simulations as well as by test drives. Based on the motion control approach, a torque vectoring control including a speed-window-control of the wheel hub drives is realized with the aim of using the maximum recuperation potential and enhancing the vehicle stability. The speed-window-control utilizes fully the higher control dynamics of the wheel hub drives compared to a conventional brake system and limits the wheel hub drive speeds to maximum and minimum boundaries. For this purpose two technology demonstrators will be built equipped with two wheel hub drives and a brake system optimized for energy recuperation and controllability. Based on these technologies the functional safety will be examined according to ISO 26262 standard. The project's main results are planned to be both a production-oriented virtual prototype vehicle, optimized for electric wheel hub drives at the rear axle as well as the drivable technology demonstrators, equipped with the named drive system, showing improved vehicle dynamics and energy efficiency with increasing the safety and comfort known by the unmodified base vehicle. The properties of the virtual prototype will be evaluated by comparison to applicable and existing reference vehicles. By applying accepted test procedures to the technology demonstrators, the performance and the robustness of the new drive system as well as the improved vehicle dynamics will be proven.