FPGA Implementation Of Fuzzy And Predictive Direct Torque Control System

With the development of control theory and power electronic,the control strategy of AC motor is more and more widely applied.The permanent magnet synchronous motor has been widely used in various industrial fields with the continuous development of permanent magnet materials,such as robots and computer numerical control machine tools.The main control methods of AC motor are frequency conversion control,vector control and direct torque control.Direct torque control analyzed directly the mathematical model of AC motor in stator coordinate system,and it used hysteresis controller to control flux linkage and torque of the motor without complicated decoupling calculation as vector control.Motor rotor resistance and inductance parameters were used to calculate rotor flux linkage in vector control.When the motor rotated,the inductance parameter changed,so it was not easy to observe the rotor flux linkage.However,in direct torque control,stator flux linkage needed to be calculated.Therefore,the flux linkage was not easily affected by the parameter variation as long as the stator resistance of the motor can be known.However,since the Bang-bang control(hysteresis control)was used for flux linkage and torque control in direct torque control,there was a problem that the torque ripple was large.Aiming at the large flux linkage and torque ripple in the traditional DTC system,a direct torque control system based on fuzzy control and predictive control was designed in this paper.It replaced the traditional PI control with fuzzy PI control in the speed loop and replaced the hysteresis controller with the predictive controller.It predicted the change of the flux linkage and the torque when different voltage vectors are applied,so as to ensure the accuracy of the applied voltage.The control system was simulated and compared with Matlab/Simulink to veritfy the effectiveness of the new method.Finally,this article carried on the FPGA based on hardware circuit design and software design part.It took FPGA as the core.The drive circuit part adopted the intelligent power module and the hardware circuit was designed.The software designed part was to design the main control system module.