| The energy supply shortage and the deepening of the economical society stimulates the development of brushless DC motor towards small size, low cost, convenient maintenance, large load capacity and strong anti-interference. Brushless DC motor has many advantages. It adopts electronic commutation circuit to swich and avoids the noise brought by the mechanical commutation, sparks and other undesirable problems. It has advantage of traditional DC machine.Most of brushless DC motor control system uses a position sensor to detect the rotor position and reverse in real time according to hall signal. But position sensor will bring some inconvenience under some harsh conditions and then the sensorless control technology is more and more accepted by people.The article takes six dimensional asymmetrical star connection permanent magnet brushless DC motor as the carrier. Firstly introduce the development of brushless DC motor, research focus, and the important content in the paper.Secondly, research the working principle of brushless DC motor, and analyze two-two turn-on and three-three turn-on two way of working. Then describe the mathematical model of brushless DC motor, make equivalent circuit for motor, give some equations, to make foundation for the motor simulation and built. Then introduce ways of starting the motor, using "three-step" startup mode, which is rotor initial location, external synchronization, synchronization three processes. Also explain the back EMF detection, and detect back EMF crossing the terminal voltage method over zero, then turn 30° power angle, and commutate.Finally, based on the former theory research, using Matlab/Simulink platform, building brushless DC motor simulation model. The result shows, to control by using no position sensor owns the characteristics of high speed starting and torque response excellent. In the last part of this article introduce some DSP peripheral circuit, drive circuit and protecting circuit, and describe all circuit. |
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