Design And Research Of Brushless Dc Motor Control System

In recent years, automatic doors are widely used in the places like high-grade residences and high offices for the features of reliable, convenient, safe and etc. Automatic entrance doors can not only beautify the environment, but also save energy, prevent dust, noise and other functions, so it is often used in intelligent buildings.The core of the automatic door is the control system, which determines the performances of the auto doors. The brushless DC motor (BLDCM) is more and more sophisticated with the development of the power-electronics and micro-control technique. And it takes on the advantages of small volume, light weight, high efficiency, low noise, big capacity and high reliability. Therefore it can be used in the system of automatic doors.In this thesis, the control system for brushless DC motors with HALL position sensors based on blackfin531 is given. The system operation speed is required to be quickly and smoothly.Firstly, the drive method of space vector PWM (SVPWM) is adopted into the brushless DC motor speed control system. Secondly the sliding mode control module (SMC) is studied to improve the stability and reduce the torque ripple at low speed.Next the mathematical model of BLDCM is derived. According to the SVPWM algorithm experiments are carried out. Finally, the simulation results of the PI method and SMC method are compared and analyzed.A digital solution with speed loop and current loop is realized based on Complex Programmable Logic Device (CPLD) and DSP. The software program are completed. The control circuits and driver circuits are given.