Strategies Of Brushless DC Motor Control Based On ARMAX Model

Brushless DC motor has the advantages of smaller size, higher efficiency, less inertia, and higher control accuracy; and it keeps the good quality of speed regulation. Besides, it has some advantages of AC motors as simple structure, reliable operation. Brushless DC motor has an immense research value with the rapid development of computer technology and power electronic technology and the improving control performance of motors by industrial servo.Based on the analysis the working principle of brushless DC motor and the speed regulating simulation under PI, fractional-order PI (FOPI) and predictive functional control (PFC) strategies, two improved control strategies are proposed in this thesis in order to cope with such drawbacks of PI, FOPI and PFC as the incompact relationship between their parameters option and industrial practice. One is fractional-order PI predictive functional control strategy, and the other one is PI predictive functional control strategy.PFC strategy, based on the mathematic model of controlled object, needs to get the precise practical mathematic model. Only a theoretical mathematic model can be obtained from theoretical modeling, but satisfactory practical mathematic model cannot be obtained. Therefore, ARMAX model is introduced, which make it easier to identify the model.In MATLAB software, FOPIPFC algorithm is programmed with MATLAB language for the speed regulation of brushless DC motor. This algorithm identifies model of BLDC via least squares method. According to the model to predict the future value of the motor speed output, thereby calculating optimal control. Simulation results show that under FOPIPFC algorithm the response of motor rising fast, no overshoot and motor can respond in a timely manner to interference. And it solves the some problems as model mismatch of predictive control and weak anti-interference ability of conventional PI strategy.In SIMULINK software, a double close-loop control system module of brushless DC motor is established. speed-loop is under PIPFC strategy by programming in s-function model, and current-loop is under PI strategy. Through simulation, the improvement of PIPFC and be seen from the speed regulation performance, the stability and robustness when the motor suffers load torque disturbance.In order to verify the feasibility of FOPIPFC and PIPFC, these two novel control algorithms are implemented by hardware experiment, using DSP320F28335controller and C language programming. Experiment results show that the two novel control algorithms can adapt to the high performance speed-adjusting system of BLDC.