Research On Brushless DC Motor Stepless Speed Regulation System Based On The Fuzzy Adaptive Pi Control

Mechanical phase conversion was replaced by electronic commutation in brushless dc motor. It has the good performance of speed of DC motor and also has the AC motor’s advance of simple structure, reliable operation, long service life, maintenance convenient and so on. Brushless dc motor is widely used in each field and daily life in national economy. In this paper, according to the structure and operation principle, the mathematical model of brushless dc motor speed control system was established, and the performance of motor speed control system was deeply researched.Due to the brushless dc motor speed control system have the high requirement of the speed control accuracy and robustness, advanced control algorithm played an important role in motor speed control performance. In this article, system used the double closed loop control system, of which outer ring was speed loop, inner ring was current loop, speed ring for the main is to realize the rotational speed of anti-interference adjustment so that motor in the steady-state had no static poor, current loop mainly realize the current follow, over-current protection and inhibiting voltage interference; For the control strategies, according to the traditional PID control of the motor speed control of slow response, low control precision and it is difficult to achieve or expected effect that the motor load or parameters changed, etc., putting forward a new fuzzy adaptive PI control strategy, it both had the characteristic of the strongly robustness, overshoot small, fast rise time, good dynamic, and had good dynamic tracking quality and stable precision of corresponding PID control, so as to meet the requirements of brushless dc motor stepless speed regulation system; Control technology adopted PWM control.With the emergence and development of the microprocessor, digital control technology can make the control circuit greatly simplified, and improve the system the ability of anti-jamming, control flexibility, and intelligence. The TI company’s TMS320F2812was considered as the main control chip, the fuzzy adaptive PI was considered as control algorithm, and the IR2136was taken as the drive chip to design the hardware platform on stepless speed regulation system of brushless dc motor, designing the main circuit, power drive circuit, voltage current sampling circuit, position detection circuit, commutation logic control and buttons display circuit etc. Under the development environment of CCS software, according to the strategy fuzzy adaptive PI control, used C language to program. The software system was consisted of the main program and interrupting program. The main program include system initialization and variable initialization, service procedure completed CAP capture, software commutation, A/D conversion, PWM produce, voltage protection, key setting and liquid crystal display, etc.The system used Matlab/Simulink to simulate the motor stepless speed regulation system. Because the motor speed closed-loop control is a nonlinear time-varying system, the conventional control algorithm can’t meet the request, therefore, fuzzy adaptive PI control was adopt to speed loop, PID control was adopt to current loop. The system studied the traditional PID control and fuzzy adaptive PI control algorithm simulation respectively, contrast and analysis the simulation results, it showed that the system had quick response speed, no overshoot, strong anti-jamming capability, and high control quality.Finally, the system did the experiment in the test platform to build on the motor stepless speed regulation system, gave the PWM and speed test waveforms, the experimental results showed that brushless dc motor stepless speed regulation system based on the fuzzy adaptive PI control strategy has obvious superiority, fast response, well reliable performance, and good application value.