Research on Pressure Control Methods for a Dual-Source Electro-Hydraulic Brake System with Redundant Braking Function

This paper presents a novel Dual-source Electro-Hydraulic Brake system (D-EHB) that incorporates a redundant braking module to enhance safety and reliability. The D-EHB is designed to address the critical issue of brake failure in vehicles, which can lead to severe accidents. The D-EHB system comprises two independent units: the Main Brake Unit (MBU) and the Redundant Brake Unit (RBU). Each unit has its own hydraulic power source. The MBU's hydraulic pressure is generated by a combination of a servo motor, ball screw, and servo piston, while the RBU has a simpler structure, with hydraulic pressure generated by a motor and plunger pump combination. Mathematical models for each component of the D-EHB have been developed and validated using AMESim. The mathematical models of each part were then combined to design a wheel cylinder hydraulic pressure estimation algorithm that can calculate the wheel cylinder pressure based on motor and valve output signals, making the system applicable to vehicles without pressure sensors in the wheel cylinders. Given the distinct characteristics of the MBU and RBU, different pressure control methods were proposed. The MBU control leverages the P-V characteristics of the servo cylinder and employs Sliding Mode Control (SMC), with the target position of the servo cylinder piston as the control output, ensuring that the hydraulic pressure of the servo cylinder quickly and accurately reaches the desired value, while maintaining robust performance. The RBU control is based on the overflow characteristics of the solenoid valve and uses proportional control. Simulations and bench tests were conducted to compare the pressure control performance of the RBU with that of the MBU. The results demonstrate that the MBU exhibits excellent control accuracy and response speed, while the RBU, although not as precise as the MBU, still meets the braking requirements.