Study on Braking Stability of Electro-mechanical Hybrid Braking System in Electric Vehicles Based on ECE Regulation

Regenerative braking makes the braking stability of electric vehicles change when it recovers the braking energy of vehicles. The calculation models were established for electric braking force, electric braking torque and utilization adhesion coefficients of front axle and rear axle, aiming at the electro-mechanical hybrid braking system composed of electric braking and conventional mechanical friction braking. The utilization adhesion coefficients of front and rear axles were calculated respectively with the paralleled-hybridized braking control strategy under different braking intensity, according to front-wheel drive and rear-wheel drive in the electro-mechanical hybrid braking system. The calculation results indicate that rear-wheel drive is not suitable for electro-mechanical hybrid braking system from the perspective of energy recovery and braking stability. For front-wheel drive of electro-mechanical hybrid braking system, front-axle is always locked ahead of rear-axle no matter what the electric motor is working at the constant power braking area or constant torque braking area, and the braking stability is preferable. However, the front wheels are locked between times when braking intensity is weak. This case could be improved by adjusting the electric braking force in order to meet the requirements of braking stability of ECE regulation.