Torque Ripple Of Brushless Dc Motor Technology

With the rapid development of micro-electronics and electromotor technology, Brushless DC motor as a new type motor is becoming more and more popular in recent years. By means of power electronics circuit to control over commutation instead of traditional mechanical methods, Brushless DC motor which not only has the merits of the AC induction motor of reliable operation, simple structure and easy upholding but also has the merit of the DC motor high running efficiency, good timing performance, nice control characteristic and without wasting excitation, has applied widely in many scopes.However, the problems such as rotor position estimation and the torque ripples have become the obstacles for the BLDCM to be used in high precision fields.The objective of this dissertation is to minimize the torque ripple of BLDCM. Begin with the dissertation introducing the base elements, working principle, operating characteristic and transfer function of the Brushless DC motor, then it presents the disadvantages of sensor control. For detail, the principle and methods of sensorless control technology. On the base of these, the dissertation analyses the torque ripple in BLDCM with ideal trapezoidal waveform BEMF and compare with various detection technologies of sensorless position, then it chooses Back EMF zero-detecting to design the system of sensorless Brushless DC motor control using the AT89C2051 chip. In addition, according to the factual require, the dissertation discusses in detail the questions of how to start, exchange phase and minimize the torque ripple at the condition of sensorless. Then it designs the system of hardware, software correspondingly.The brushless DC motor is modeled by using MATLAB/Simulink for experimental use to verify the validities of the proposed methods. Those are strongly supported by Simulink and experimental results, and achieve its aim and require, and can satisfy us.