Torque-Vectoring Driveline for Electric Vehicles

Abstract

The range of electric vehicles is limited due to the battery capacity. As a result of high prices for batteries as well as a rising weight using additional battery modules, both the feasible level of electric recuperation and the efficiency of the system have to be as high as possible. Therefore, the Technische Universität München has developed and designed a new torque-vectoring system for electrical powertrains. Besides the main driving machine a second smaller superimposing electric motor combined with a superimposing gear makes it possible to recuperate brake energy for all driving situations. Especially in curves with high lateral forces the new system reaches higher recuperation values than comparable systems. The system size of the superimposing machine is only about 5 % of the vehicle’s driving power. Due to the continuously variable power delivery there are no slipping losses, i. e. such as those of wet clutches. The overall losses in the presented powertrain are only 10 % of the losses compared to existing systems. Gearbox efficiency results, which were calculated with a simulative model, are presented for straight-ahead driving and cornering. Varying deceleration values for these driving conditions, efficiency values are illustrated for different recuperation levels with or without the superimposing machine being activated.

F2012-B03-009