Coordinated Control Strategy of Electromagnetic and Regenerative-Friction Combined Braking for In-Wheel Motor Electric Vehicles 2021-01-0971

In view of friction braking consumes the kinetic energy of the car by converting it into heat energy, it cannot recover this part of energy. And compared to electric braking, its braking response is slower. An integrated braking system of electromagnetic braking, regenerative braking and friction braking of in-wheel motor is proposed. Firstly, the operating characteristics of the electromagnetic braking system, regenerative braking system, and friction braking system were analyzed respectively, and seven operating modes of the electromagnetic and regenerative-friction combined braking system were designed, namely, the pure regenerative braking mode, the pure friction braking mode, the pure electromagnetic braking mode, the electromagnetic and regenerative combined braking mode, the regenerative and friction combined braking mode, the electromagnetic and friction combined braking mode and the electromagnetic, regenerative-friction combined braking mode, and then seven kinds of braking model switching conditions were determined. According to the hybrid control theory, the vehicle has both a continuous working state and a discrete state when the vehicle is braking and MATLAB/Stateflow was used to establish the switching control strategy of braking modes. Finally, by building the longitudinal dynamics model of the vehicle, the tire model, and the electromagnetic, regenerative-friction combined braking system model, simulation analysis of five different braking conditions were carried out in MATLAB/Simulink. The simulation results show that the electromagnetic and regenerative-friction combined braking system can work in different modes according to the designed coordinated switching control strategy to meet the braking requirements. At the same time, the proposed hybrid theoretical model can maximally shorten the braking distance by 4.6% and maximally shorten the braking time by 0.11 seconds, which can effectively improve braking efficiency and improve the braking safety of vehicle.