Linear Electro-Magnetic Valve Characteristic Analysis and Precise Pressure Control of the Electro-Hydraulic Brake System

With the development of modern vehicle chassis control systems, such as Anti-Lock Brake System (ABS), Acceleration Slip Regulation (ASR), Electronic Stability Control (ESC), and Regenerative Braking System (RBS) for EVs, etc., there comes a new requirement for the vehicle brake system that is the precise control of the wheel brake pressure. The Electro-Hydraulic Brake system (EHB), which owns an ability to adjust four wheels' brake pressure independently, can be a good match with these systems. However, the traditional control logic of EHB is based on the PWM (Pulse-Width Modulation), which has a low control accuracy of linear electromagnetic valves. Therefore, this paper presents a research of the linear electro-magnetic valve characteristic analysis, and proposes a precise pressure control algorithm of the EHB system with a feed forward and a PID control of linear electro-magnetic valves. The research analyzes the working mechanism of the linear electromagnetic valve with both hydraulic analysis and electromagnetic analysis firstly, and then, a hardware-in-loop test bench of electronic hydraulic brake system is built, which is used for testing the response of the system. Finally, an incremental PID and the feed forward control principle is designed with an experimental platform. The hardware-in-loop experiment results show that the algorithm is valid and reliable.