The Research And Design On Controler In Electric Power Steering System For Electric Forklift

With the continuous development of electronic technology and computer technology, Electrical power steering (EPS) system has become the trend of power steering system. It is a new developing technology in automation. EPS has advantages of small volume, high efficiency, no population and is easy to control, so EPS system is increasingly being applied to all types of motor vehicles. The main task of this paper is to design and develop the of electric power steering system of electric forklift based on MCU, the main works of this paper are as fallows:1. Firstly, based on the basic structure and dynamics model of EPS system for electric forklift, the basic principle of system is illustrated.The difference of the EPS system between electric forklift and car and the control strategy is determined considering the actual work environment and work characteristics of electric forklifts. Several key factors which affect the performance of EPS system are discussed.2. Permanent magnet brushless DC motor (BLDCM) has advantages of small structure, reliable operation, good mechanical properties and dynamic characteristics and is determined to be the power motor. BLDCM control system uses two closed-loop control structures, the speed loop adopts fuzzy PID control and the current loop adopts hysteresis control. The simulation model of the system is built in MATLAB/Simulink and the simulation results are compared and analyzed.3. The reason of commutation torque ripple is stated in brief in this paper, methods are proposed toreduce and minimize it. Power compensation control is added to to improve response sensitivity and speed of response of EPS system. Parabolic assistance characteristic is determined to get ideal power effect. An simulating model of the EPS systems is established in the environment of MATLAB/Simulink, the simulation results are in good agreement with the expected results which strictly verify the correctness of the model and the validity of the control strategy.4. Based on the chip of C8051F340, the relevant hardware and software of EPS system are design and related principle of hardware logic circuit and software program flow are briefly introduced.5. The validation experiment, help assist characteristic and compensation control experiments of electric forklift have been completed on the relevant experimental platform. The results show that the electric forklift EPS system established in this paper has good performance and demonstrate the effectiveness of the whole control system.In summary, this paper gives a more detailed description about the design of the EPS control system. Including theoretical analysis, modeling and simulation and experiment, the whole process has basically completed the requirements for pre-design tasks and has a certain reference value for practical engineering applications.