Research And Development Of Electric Forklift’s Lifting Controller Based On FPGA And DSP

Nowadays, the electronic commerce develops quickly, and the logistics industry has become a vital link in the field of electronic commerce. Electric forklift is the most important tool in the logistics industry as goods should be loaded or transported in short distance. Under the background that whole society proposes environmental protection, the market demand for electric forklift is increasing year by year. It will not be a long time that electric forklift can replace the internal-combustion forklift.The pallet forks are controlled by hydraulic system in traditional electric forklifts. However, the hydraulic system will generate oil pollution. The high-performance electric control system instead of hydraulic system is necessary. Because permanent magnet synchronous motor(PMSM) has many advantages such as small size, light weight, high efficiency, PMSM is often used to control the pallet forks. As PMSM is a multivariable and strongly coupling nonlinear controlled objects and the vector control system can realize decoupling control, the vector control system is widely used in PMSM control system.Fuzzy control has the ability of decision and illation, and it has better robustness even if the system don’t have accurate mathematical model. Therefore, the fuzzy controller is widely used in PMSM control system. In this paper, a PMSM is treated as the control object, then the vector control system and its related intelligent control methods are introduced. Concerning the problem that PMSM has slow speed response and large torque ripple under the tradition vector control system, a Fuzzy PI(FPI) controller and a Fuzzy Neural Network PI(FNNPI) controller are proposed. These controllers will be used in speed closed loop in vector control system to improve the PMSM’s response performance. At last a PMSM controller platform is designed based on FPGA and DSP. The main research work and the results are showed as follows:1. The structure of PMSM, the vector control system and the space vector pulse width modulation(SVPWM) method are introduced in the first part.2. The intelligent control methods such as PI control, Fuzzy control and RBF neural network are introduced in the second part. Base on these methods, a FPI controller and a FNNPI controller are proposed.3. A PMSM vector control system model is formulated in matlab/simulink. By using the tool boxes in simulink, the FPI and FNNPI controller are set up. Then FPI and FNNPI controller are used in speed close-loop instead of PI controller. Through the response of PMSM speed and torque, the reasonability and validity of FPI and FNNPI controller have been testified.4. According to the requirements of electric forklift’s lifting control system, an experiment platform of PMSM is designed based on FPGA and DSP. The current sampling circuit, power driving circuit and AD conversion circuit will be designed in the hardware. The software system of the controller such as vector control method, SVPWM and serial port communication are designed. Finally a motor is controlled by the experiment platform, the motor’s response results show that the platform is all right.