Design and modelling of optimal driveline control strategy for an electric racing car with rear in-line motors

摘要

Interest in electric vehicles (EVs) has increased rapidly over recent years from both industrial and academic viewpoints due to increasing concerns about environmental pollution and global oil usage. In the automotive sector, huge efforts have been invested in vehicle technology to improve efficiency and reduce carbon emissions with, for example, electric vehicles. Nowadays, the safety and handling of electric vehicles present new tasks for vehicle dynamics engineers due to the changes in weight distribution and vehicle architecture. This thesis focuses on one design area of the electric vehicle – torque vectoring control – with the aim of investigating the potential benefits of improved vehicle dynamics and handling for EVs. A full electric racing car kit developed by Westfield Sportcars based on an in-line motors design has been modelled in ADAMS with typical subsystems, and then simulated with computer-based kinematic and dynamic analyses. Thus, the characteristics of the suspensions and the natural frequencies of the sprung and unsprung masses were found, so that the model was validated for further simulation and investigation. Different architectures of the EVs, namely the in-line motors and the in-wheel motors, are compared using objective measurements. The objective measurements predicted with kinematics, dynamics and handling analyses confirm that the architecture of the in-line motors provides a superior dynamics performance for ride and driveability. An Optimal Driveline Control Strategy (ODCS) based on the concept of individual wheel control is designed and its performance is compared with the more common driveline used successfully in the past. The research challenge is to investigate the optimisation of the driving torque outputs to control the vehicle and provide the desired vehicle dynamics. The simulation results confirm that active yaw control is indeed achievable. The original aspects of this work include defining the characteristics and linearity of the project vehicle using a novel consideration of yaw rate gain; the design and development the Optimal Driveline Control Strategy (ODCS); the analysis and modelling the ODCS in the vehicle and the comparison of the results with conventional drivelines. The work has demonstrated that valuable performance benefits result from using optimal torque vectoring control for electric vehicle.