Research on Modeling of Distributed Compound Braking System and Braking Force Allocation Strategy

This paper proposes a novel braking force allocation strategy for electric vehicles with four in-wheel motors (IWM). Based on the principle of maximizing the regenerative braking torque of four motors, the motor and the hydraulic braking force of both front and rear axles have been allocated to four wheels respectively, and the fuzzy control method is adopted to control the vehicle's slip rate under the emergency braking. The paper first analyzes two common regenerative braking control methods of IWM: half-bridge modulation and full-bridge modulation, and compares the modulation effect of the two control methods. Then, the braking force allocation strategy is proposed, which can be divided into two parts: under normal braking and under emergency braking. Finally, the braking force allocation strategy is verified through the co-simulation platform of Carsim, Matlab/Simulink and AMEsim. The simulation results show that under normal braking, the proposed Uraking force allocation strategy can preferentially adopt the motor braking force according to the maximum motor Uraking force. When the total braking force provided by the motors cannot meet the vehicle's braking severity requirements, EHB system involves in braking to provide the remaining braking force. Under emergency braking, the slip rate can be well controlled by the fuzzy control method.