J. Deur, B. Škugor, W. Chen, Y. Zhang, E. Dai

Energy-efficient Straight-line Driving Torque Vectoring for Electric Vehicles with Multiple Motors Equipped with Disconnect Clutches

18th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES), Dubrovnik, Croatia, 2023.
Battery electric vehicles with multiple motors are characterized by actuator redundancy, which calls for application of instantaneously optimized distribution of motor/wheel torques, thus minimizing the energy consumption, i.e., maximizing the vehicle range. If the e-motors are equipped with disconnect clutches, the energy saving potential becomes even higher due to the avoidance of drag of inactive e-motors. However, in this case optimization through time and predictive control techniques should be used to provide globally minimal energy consumption. To, this end, the paper proposes the following modeling, optimization, and control methods for straight-line driving mode: (i) a dynamic backward-looking model of electric vehicle propelled by disconnect clutch-equipped four wheel motors, which takes into account the clutch synchronization-related drivetrain transient loss; (ii) globally optimal, dynamic programming (DP)-based off-line optimization of e-motor torque and clutch state control trajectories, (iii) a parameter-optimized rule-based (RB) torque vectoring control strategy, and (iv) a model predictive torque vectoring control (MPC) strategy. The control strategies are verified by simulation for various certification driving cycles, and the results are compared with the DP-optimal benchmark for different values of a user-defined weighting coefficient, which penalizes frequent clutch disconnects for improved durability. The DP optimization results reveal that the energy consumption reduction achieved through the disconnect clutch functionality is up to 7%, on top of up to 5% reduction achieved by torque distribution itself. The RB and MPC control strategies approach the DP energy consumption benchmark within the margin of 1.3% and 0.6%, respectively.