| Brushless DC motors(BLDCMs)are widely used in industrial automation,office automation and home automation for their advantages of good speed regulation and simple structure.However,the torque ripple and the control system stability have always been the outstanding problems of brushless DC motors.In this dissertation,an FPGA-based brushless DC motor control system is proposed to solve the above problems,which can effectively restrain the torque ripple and improve the stability of the system.In the thesis,the simulation module and other functional modules of brushless DC motor are constructed by using Simulink simulation function of MATLAB software at first,and the experimental simulation of the rotor position estimation method based on the back-EMF zero-crossing detection method is completed.Aiming at the problems of poor stability and reliability and poor control effect of traditional PI control algorithm,a speed control strategy based on fuzzy control algorithm is proposed.According to the relationship between PI parameters and the rate of change of speed deviation,real-time online adjustment.The fuzzy PI control algorithm is compared with the traditional PI control algorithm to verify the effectiveness of the proposed algorithm.When the system uses the DSP as the main controller chip,it often appears that the program is easy to fly,poor system stability and other undesirable phenomena.In response to the above problems,this paper designed a brushless DC motor control system based on FPGA,and the completion of the system hardware circuit design.Among them mainly include FPGA main control drive circuit,back EMF detection circuit,current detection circuit,power supply circuit and reset circuit and so on.Use Verilog hardware description language to write the system software program,and verify the correctness of the program code on the simulation software platform.In this paper,we adopt a modulation method based on PWM_ON_PWM,and verify the applicability of the algorithm through simulation waveforms.The experimental results show that the control system of brushless DC motor based on FPGA has good dynamic performance and reliable operation and meets the expected experimental requirements.The proposed PI regulator has better speed regulation performance than the traditional PI regulator.Observing the motor torque waveform through the experimental results,it is found that the PWM_ON_PWM modulation method has a good restraining effect on the torque ripple. |
