A novel hierarchical controller for efficient and safe blending of hydraulic and regenerative braking systems in electric vehicles

Abstract Anti-lock braking systems are essential for ensuring vehicle safety by regulating tyre slip and maintaining stability during braking. In electric vehicles, regenerative braking offers a unique opportunity to recover energy and enhance efficiency. However, the integration of regenerative and hydraulic braking systems introduces significant control challenges due to their differing dynamics. This paper presents a novel hierarchical control framework for a blended hydraulic–regenerative braking system, designed to optimise both safety and energy recovery during severe braking manoeuvres. A multi-level control architecture is proposed: the high-level controller coordinates torque distribution between hydraulic and regenerative braking; the mid-level employs sliding mode control for precise tyre slip regulation; and the low-level controller governs actuator dynamics. The system is modelled comprehensively, accounting for vehicle, tyre, and actuator characteristics, and is validated under various driving conditions. Results demonstrate that the proposed system maintains robust longitudinal slip control while significantly enhancing energy recovery, achieving a harmonious balance between braking performance, efficiency, and safety.