Regenerative Brake-by-Wire System Development and Hardware-In-Loop Test for Autonomous Electrified Vehicle

As the essential of future driver assistance system, brake-by-wire system is capable of performing autonomous intervention to enhance vehicle safety significantly. Regenerative braking is the most effective technology of improving energy consumption of electrified vehicle. A novel brake-by-wire system scheme with integrated functions of active braking and regenerative braking, is proposed in this paper. Four pressure-difference-limit valves are added to conventional four-channel brake structure to fulfill more precise pressure modulation. Four independent isolating valves are adopted to cut off connections between brake pedal and wheel cylinders. Two stroke simulators are equipped to imitate conventional brake pedal feel. The operation principles of newly developed system are analyzed minutely according to different working modes. High fidelity models of subsystems are built in commercial software MATLAB and AMESim respectively. The control strategies of brake force distribution and hydraulic pressure modulation are designed on basis of closed-loop controller simultaneously. Co-simulations under typical braking and active braking scenarios are conducted to validate the feasibility of proposed system architecture and reasonability of designed control algorithm. Simulation results show that the motor brake torque works cooperatively with hydraulic brake force. More than 36% of recoverable energy can be regenerated during typical braking procedure. Active braking can shorten the brake distance by nearly 18% compared with conventional driver emergency braking. Hardware-in-loop (HIL) bench tests are implemented under scenarios identical with simulations. The data acquired from HIL bench tests matches well with simulation results. Nearly 37% of recoverable energy is regenerated under typical braking condition, and brake distance is shortened by 4.33 m during active braking procedure.