| The stepper motor is an electromechanical device that converts electrical pulses signal into discrete step angle. Having the advantage of precise positioning and non-cumulative movement error Compared to the other motors, the stepper motor becomes one of the most important executor in the micro-motion system. With subdivision driving technology of step motor in the high accuracy and micro-motion system, it can effectively improve the stepper motor's characteristic of low frequency and achieve micro-motion and orientation with high accuracy. The popular methods of subdivision driving technology are cutting waves, pulse width modulation and tracing current now. Though these methods can implement subdivision driving and also have the advantage of precise positioning and non-cumulative movement error. Because of the error brought by the mutual inductance voltage of other windings, the accuracy of one subdivision step is still a bottleneck of subdivision driving.In this paper, a subdivision driving technique with high accuracy and high resolution based on controllable current source is introduced, which implements double 14-bits DAC(digital-to-analog converters) with PWM and 5th-order Butter -worth low-pass filter. The current source, controlled by the output of DAC, provides stable current for the winds of the stepper motor and obtains subdivision high accuracy and high resolution driving.The thesis presents the method of how to measure subdivision angle. Correcting the current through winding with combing two ways of experimentation and, this method amends the subdivision driving current and compensates the non-linear of the stepper motor's windings. 512 subdivisions can be obtained with angle error within±20%. The experimental results indicated the subdivision driving technique can satisfy the micro-motion system, featuring highly linear division, no propagation error and low noise.
|
PDF Full Text Request