Fully Electrified Regenerative Braking Control for Deep Energy Recovery and Maintaining Safety of Electric Vehicles

Recycling braking energy is significant to improve the total energy efficiency of electric vehicles (EVs). Moreover, braking safety must be maintained under complex conditions. As the actuator, the electric traction motor has much better features than the internal combustion engine, e.g., faster torque response and capability for energy feedback. From the perspective of energy efficiency and safety, highlighting regenerative braking is a meaningful but challenging problem. In this paper, a braking system using only electric motors/generators as the actuators is investigated, in which the energy may be potentially fed back to the onboard energy storage system (ESS) as much as possible. The energy that may be recovered to the ESS is analyzed. To maintain the stability and to improve the performance of the regenerative braking in unknown tire-road conditions, a knowledge-based methodology in a hierarchical control structure is proposed, where the maximum adhesion force and the motor reference torque (MRT) are determined online. The proposed methodology avoids the complex determination of the optimum slip ratio, while acquiring nearly the optimum antiskid braking performance. Simulation and experiment were carried out to validate the effectiveness.