Hydraulic braking force compensation control for hybrid electric vehicles

The possibility of regenerative braking is one inherent advantage of hybrid electric vehicle. The motor and the hydraulic braking system are braking together while the hybrid electric vehicle is braking. But, the difference of the braking force dynamic response between the motor and the hydraulic braking system will lead the inadequate or excessive braking and will affect the braking feeling of the driver. In this paper, we analyze the braking dynamic characteristics of the motor and the hydraulic braking system. Then, we propose the braking force coordinated control strategy based on using the hydraulic braking force to compensate the motor braking force during the braking process of the hybrid electric vehicle. And in order to improve the accuracy of the motor torque control, we use the adaptive fuzzy sliding model control method to control the motor torque. After that this paper used the integrated feed-forward and feedback control to design the hydraulic braking force compensation control strategy. This compensation control strategy can maintain the stability of the control system while reduce the system error and increase the dynamic performance of the system. The simulation results show that hydraulic braking force compensation control is effective and the total braking force can meet the desired braking force during the braking of the hybrid electric vehicle.