Lateral stability integrated with energy efficiency control for electric vehicles

Abstract

Abstract A hierarchical controller is designed to enhance the lateral stability of electric vehicles (EVs) with as low dissipation energy as possible in this paper. In particular, a reference dynamic model based on the estimated tire cornering stiffness is established for different driving conditions, the lateral stability control can be transformed into tracking the desired sideslip angle and yaw rate by the reference dynamic model. At the upper-level, the controller is consisted of an integral terminal sliding mode (ITSM) controller and a speed tracking controller. The ITSM controller considering parameter uncertainties is proposed to quickly achieve the lateral stability, the speed tracking is used to stabilize the longitudinal dynamics. At the lower-level, in order to reduce the computational burden of the tire energy consumption, a penalty function with the longitudinal slip ratio is introduced to automatically modulate the weight factor of each wheel torque. Then, an optimal torque control allocation (CA) strategy utilizes the designed penalty function to allocate the control command from the upper-level controller. Simulation results show that the designed controller can guarantee the lateral stability under different driving conditions. Moreover, compared to other CA methods, the tire dissipation energy can be effectively decreased by the proposed CA based on the longitudinal slip ratio.