Key Technology Research On Brushless DC Motor Control System For Electric Forklift Eps

In this thesis, a in-depth theoretical analysis, simulation and experimental study on several key technologies such as rotor position detection methods, motor start-up methods and motor control strategies are performed for brushless DC motor drives of electric forklift EPS.Back-EMF zero crossing detection method is widely used in detecting the rotor position of brushless DC motor for its simple and reliable. The operation of brushless DC motor without position sensor based on back-EMF zero crossing suffer from a starting problem since there is no back-EMF at standstill, thus limiting the application of this method. On the basis of the analysis of the working principles and mathematical model of brushless DC motor, a simple starting method is proposed, which the motor is started from standstill up to a speed where sensorless methods will be able to detect the correct commutation instants. The proposed method relies on the difference of line voltages measured at the terminals of the motor, so you just need to measure the three-phase voltages of brushless DC motor to realize the reliably starting and running of the motor. The correctness of this method is verified by Matlab/Simulink.The real-time, accuracy and reliability in EPS system of electric forklift is the important guarantee of safe driving. This paper analyzes the structure and working principle of EPS system and reaserches its assist characteristic. Linear dynamical characteristics curve and basic dynamical control strategy are adopted to realize the correspondence of input torque and target current of the motor. The motor using fuzzy control strategy enhance follower of the EPS control system. A brushless DC motor controller based on DSP is designed. The hardware solution based on TMS320F28035chip and DRV8301drives simplify the volume of the controller, and enhance the system reliability. The program of EPS fuzzy control algorithm is designed. Test the performance of EPS controller on the experimental platform and the experimental results validate the proposed method and the correctness of the design of fuzzy control procedure.