Research And Design Of Brushless DC Motor Control System Based On Position Sensorless

BLDC uses the power electronic commutation circuit to replace the traditional DC motor brush and commutator device,which not only has high start,high power factor,strong overload capacity,smooth and broad speed performance advantages,but also overcome due to sliding between the electric brush commutator device the electric spark and mechanical friction etc..It has been widely used in the fields of electric vehicles,medical instruments,household equipment and so on.But because of the existence of the position sensor BLDC add the cost of the system increases the volume of the system and make the system instability,thus greatly limits the application of the motor in high temperature,high pressure and other adverse events.So it becomes important to study the technology of sensorless control.This paper first introduces the current domestic and foreign scholars on the study in the following aspects:BLDC sensorless rotor position estimation of the BLDC problem;the problem of position estimation of BLDC rotor without position sensor;when the motor is stationary,it is unable to get the rotor position information starting position sensorless BLDC startup problem;because of the cogging effect and the torque ripple caused by motor current commutation.Then,the deeper research on rotor position estimation of BLDC sensorless control system is explored in this paper.First the basic structure and working principle of Brushless DC motor are introduced.The mathematical model of BLDC is built,based on which the basic equations of voltage,torque and back EMF are established.Based on traditional rotor position detection method using back EMF,a improved method is proposed in which,using the difference of two phase to phase voltage.Then based on the analysis of the current situation of continuous flow of five kinds of PWM modulation,and get H_PWM-L_PWM PWM modulation off free wheeling phase current conclusion.Then under the Matlab/Simulink simulation platform of the simulation model was built,analyzed the function of each sub module,and the accuracy and feasibility of the method for detecting the rotor position is verified by the simulation model.Finally,based on the TMS320F28338DSP the controller as the control core of the brushless DC motor without position sensor control system hardware and software design in detail,and the experimental results proved the opposite EMF method proposed by this paper can be improved Practicality and accuracy.