Research Of Electro-Hydraulic Power Steering System And Program Loading Remotely

The electro-hydraulic power steering system(EHPS) is an advanced mechatronic device with good road feeling and better energy efficiency. It’s one of the most popular automotive steering systems.This paper mainly studies the drive and control strategy of the four-phase brushless DC motor. Fistly the windig structure, the driving method and the unique freewheeling way of the motor were introduced, and the mathematical model of such kind of motors was established. All these provided theoretical reference for the next studies.Secondly the commonly used methods of weakening the magnetic flux to expand the the speed range were studied. The specific mechanism of lead angle can weaken the magnetic flux and expand speed range was specified, and the corresponding advantages and disadvantages was also highlighted. Based on this, the dual-control mode was summarized:the speed and current dual loop control mode was adapted when motor-speed was under the base-speed; the mode of using speed single loop to adjust the PWM duty and lead angle synchronously was adapted when the motor-speed was above the base-speed.Then the algorithms and program flows of the major computing modules in the program were introduced, and method adapted to improve the accuracy of the HALL sensors was analyzed.The simulation model and experimental device with hydraulic circuit were built to test the actual effect of the newly-developed controller. The freewheeling way and overshoot voltage caused by the leakage inductance of the windings were analyzed in the simulation section. The dynamic response of the entire motor driving system, the ablility to expand the speed-range by weakening the magnetic flux and how much load the motor can bear were all tested in the experimental section.Finally the program loading method via CAN communication was studied in MPC5602P chip of Freescale Corp..The program loading platform via CAN communication and actual operating procedures were studied and introduced. All these provides important technical support for the industrial production of EHPS controllers.