Automotive Electronic Hydraulic Power Steering

Automotive electric-hydraulic power steering system is a new technology which developed on the basis of the conventional hydraulic steering system. It can provide more steering comfortable for the driver, and it can provide more economical car steering energy. The study is very valuable.The core of the system design is the motor control unit, which is: How to improve the electro-hydraulic power steering system steering performance by controlling the motor, reduce the system energy consumption. In this paper, we start by the principle of the brushless DC motor control, research on the relationship between the power steering motor’s speed and size. Establish and simplified mathematical model, presents a stable motor control algorithms, calculating out any speed, the continuous relationship between the motor speed, steering wheel angular velocity and speed. Improve real-time functionality, reduce control error.The key of the electro-hydraulic power steering system control is stable motor control. To achieve more accurate speed control, we take the dual closed-loop PI control, and choose a 16 bits digital Signal Controllers of Microchip’s dsPIC30F5015. This chip has a wealth of hardware resources and excellent motor control module.In this system, the dsPIC30F5015 is the MCU, with its peripheral extended circuit, drive circuit, motor control pulse width modulation and so on, make up the control system of the Brushless DC Motor, thus it achieve the automotive electric hydraulic power steering function. The software by the dual closed-loop PI control of the speed outer loop and inner current loop, achieve a more precise motor speed regulation, thus increased the motor starting, anti- load, anti-jamming performance. When the motor failure, we timely communication with the vehicle by the CAN bus, display the failure information.Finally, the EHPS system integrated experimentation platform is established to test the control algorithm, signal Processing, motor control performance and the steering control performance. The experimental results verify the feasibility of the EHPS system design, control method is feasible, has achieved the anticipated test requirements.