Research On Reliable Starting And Precise Commutation Methods Of Sensorless Brushless DC Motor

Rotor position sensor plays an important part in the operation of brushless DC motor,whereas its disadvantages of extra output lines,volume occupation,lack of the ability to work under extreme working conditions,such as high temperature or being soaked in the fuel,have become weak links in the development of brushless DC motor control system,which promoted the research and development of sensorless brushless DC motor control technology.Researches are carried out in depth about the reliable starting and precise commutation methods of sensorless brushless DC motor for fuel pump drive.The corresponding optimization control methods are put forward respectively to improve the starting reliability and commutation accuracy,which lay the theoretical and technical groundwork to the engineering application of sensorless brushless DC motor in the aviation field.Firstly,the basic principles of three commonly used back-EMF detection methods of sensorless brushless DC motor are introduced.The Matlab/Simulink simulation models are established respectively to analysis the characteristics of each method.Secondly,the commonly used starting control methods are introduced.In addition,the impacts on motor working under conditions of voltage fluctuation,load torque ripples and mechanical vibrations have been analyzed.A three-step starting optimization method is proposed,theoretical analysis and simulation verification prove that the method can enhance the reliability of the motor starting.Finally,the effects of commutation accuracy on the operational performance of sensorless brushless DC motor have been analyzed by simulation.Armature reaction,motor neutral point difference and filter circuit are the three main factors which affect the commutation precision.Analyzes are carried on in-depth to study them.A rotor phase compensation optimization method based on the terminal voltage detection is proposed,and simulation analysis verifies its effectiveness in promotion of motor commutation precision.A digital experimental platform of sensorless brushless DC motor control system is designed based on Digital Signal Processor(DSP).The experimental results show that the optimization starting and rotor phase compensation optimization methods can effectively improve the starting reliability and commutation precision respectively,which are of high value in engineering applications.