Simulation On The Riding Comfort Of An Electric Vehicle Based On The Braking Systems Of Mechanical Friction And Electric Regenerative

In the braking process of electric vehicles, the combination of traditional mechanical friction braking and regenerative braking can change the original braking performance. Under the same conditions, drivers will feel the braking force changing more smoothly and passengers also feel comfortable. Therefore, it is necessary to combine the electric regenerative braking with the mechanical friction braking, which benefits the driving smoothness.Based on the analysis of traditional vehicles braking characteristics and the research on the strategy of motor regenerative braking, the distribution coefficient of mechanical friction braking force and the actual braking force distribution coefficient range of modified XJTUEV_II are determined. Without changing the mechanical friction braking system, the motor braking subsystem is added to form a parallel braking system. By controlling the current value of the regenerative braking system, the effectiveness of braking, the recovery efficiency of braking energy and the change of the braking smoothness are studied. Then the single mechanical friction braking system model, the regenerative braking system model based on constant charging current and co-simulation model of regenerative braking strategy based on constant armature current are established through the AMESim-Simulink co-simulation software. At the low-speed and medium-speed of braking conditions, the simulations are carried out based on the three models to evaluate the performance of the vehicle respectively, and at a emergency braking condition, the simulation are carried out based on the mechanical models to evaluate the safety of the vehicle respectivelyThe simulation results show that the mechanical friction braking system can guarantee the braking safety, and the system can improve braking deceleration and shorten the braking distance under the same conditions, with the motor regenerative braking torque added. But the braking smoothness of the electric vehicle declines. With the constant charging current to the battery control strategy, the braking distance is the shortest and the recovered energy is the most, but the braking smoothness is relatively poor. With the constant armature current control strategy, the braking smoothness is improved, but the energy recovery efficiency is lower. In addition, when the motor torque decreases, the deceleration fluctuation is obvious under the two control strategy, leading to a great impact on the vehicle. Therefore it can’t meet the requirement of braking smoothness only by the current control. We also need to control the front axle mechanical friction torque to compensate the torque.