ABSTRACT
Step motor is a kind of electromechanical component that is driven in step angle or
line displacement by electric pulse signal. Because of having the advantage of easy
open-loop control and no accumulating error, stepper motor is being applied widely in
many fields. The performances of stepping motor are related closely with its driver,
consequently, the study on driver of stepping motor gets more and more attention. In
order to meet the requirement of high-precision orientation and moving smoothness,
subdivision driving of stepper motor is adopted.
As for the drive technique of stepping motor, subdivision drive behaves better in
controlling, using subdivision drive method in the system can markedly decrease low
frequency vibration of the motor and enhance motor’s accuracy. at the same time,
integrated subdivision driver of stepping motor makes drive circuit simpler in structure,
higher in security and more convenient in controlling as well as the subdivision drive is
realized with excellent performance.
This article analyzes the structure and the work principle of 2-phase hybrid
stepping motor, establishes a nonlinear dynamic model, and also presents the expression
of the winding flux linkage equation, rotation voltage equation, the rotor equation of
motion and the transfer function.. According to the character, the paper uses subdivision
control technology, which is based on current vector even rotation with constant
amplitude, to control the exciting winding current and to produce rounded and even
inner complex magnet field. .The value of complex magnet field vector decides the
value of motor torque; the neighboring two complex magnet field vectors decide the
value of step angle.
The driver takes single chip PIC18F4520 as the control core, selects TLP521-4 and
the H-bridge as the driver circuit. The paper discusses the technology of driver, the
hardware and software designing in detail.
Using subdivision control technology, the motor operates smoothly, the operation
precision is increased and the torque is constant. The range of subdivision can be
regulated from 1 to 256 only by changing the current waveform value in the memory.
At last, a whole test for driver is made. The experiment result indicates that this
driver reaches the qualities required. The system runs smoothly and safety. The circuit is
simple, and has a good performance. The design principle fits many kinds of stepping
motor, and has a good practical value.