EV traction control based on nonlinear observers considering longitudinal and lateral tire forces

Abstract

An observer-based traction control strategy for electric vehicles is proposed in this paper. The proposed strategy considers the combined effects of lateral and longitudinal traction forces, both for acceleration and regenerative braking, even in curved trajectories. Nonlinear reduced-order observers are designed for estimating tire-road friction condition on each traction wheel and vehicle lateral velocity from which side-slip angles are calculated. A detailed analysis of observers convergence is performed, and a method to know the quality of the estimated variables is also proposed. The proposed traction control strategy allows avoiding the traction wheels skidding during acceleration and braking both in straight trajectories and turning maneuvers. The performance of the proposal is verified through simulation on a complete vehicle model, under different situations and even considering a different vehicle tire model.