Study On Speed-control Algorithm And Starting Circuitry Of Brushless DC Motor

In recent years, brushless DC motor has been more widely used, it is an electronic exchange to replace the mechanical commutation, there is no mechanical commutator and carbon brushes, brush DC motor to overcome short life, noise low efficiency, and reduced motor wear, and the unreliability of carbon brush and commutator contact electromagnetic acoustic, the study of our brushless DC motor has a very important production and life meaning.Generally, it requires installing position sensor for real-time detecting of position signal back to the controller in order to achieve the effect of speed control. However, considering the motor applications, the size,the cost and many other issues, If can not use position sensors to achieve the same purpose-driven, it will be more cost-effective. So sensorless controling method has been proposed, its starting circuit has been analyzed and researched in thesis.In the introduction section,Development Overview of BLDCM speed control and Sensorless control system of BLDCM be reviewed.The study is divided into two parts first part (Chapter 2 and Chapter 3) is fuzzy control of brushless DC motor speed control system, the second part (Chapter 4 Chapter 5) is the starting circuit of sensorless BLDCM, Is the focus of the content of papersThe first part of this article reviews the brushless DC motor structure, working principle and mathematical model, Then the speed of the BLDCM methods are analyzed. For a number of shortcomings of Traditional PID control, Fuzzy adaptive PID control method has been proposed, Simulation results show that System has a faster response time, no overshoot, and steady-state accuracy.Based on the Sensorless BLDCM the basic operating principle. Starting method of BEMF detection rotor position has been proposed. Piecewise linear method was used to achieve the BEMF detection circuit, For the problem of excessive current caused by Three-step starting, Current closed-loop starting method has been introduced. Through its analysis, The simulation results for the current closed loop starting and the steady running indicate the proposed measure solves the problem of the bigger current when starting.