Overview
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Stepper motors are commonly used for positioning in printers or digital
cameras.
Pull-in and pull-out torques are important characteristics for evaluating
a stepper motor, and hence, need to be investigated before designing the
motor.
In JMAG, it is possible to calculate these characteristics using 3D transient
response analysis, however, it may take too much time.
So, JMAG-RT system is used to create RT motor model, which is used as a
reference for a circuit / control simulator to obtain pull-in and pull-out
torques.
This note presents how to obtain pull-in and pull-out torques at each pulse
rate in the case of a stepper motor with bifilar winding / unipolar drive
and in the case with monofilament winding / bipolar drive. |
Pull-In and Pull-Out Torques(bifilar winding / unipolar drive)
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Figure 1 shows the pull-in and pull-out torques when bifilar winding and
unipolar drive are used. The self starting region and slew region can be
determined from the pull-in and pull-out torque characteristics. This provides
the correlation between the torque and the pulse rate required for the
motor to run on without losing synchronized stepping. |
Pull-In and Pull-Out Torques(monofilament winding / bipolar drive)
| Figure 2 shows the pull-in and pull-out torques when monofilament winding
and bipolar drive are used along with the result in Figure 1. As shown
in the figure, both the bifilar winding / unipolar drive and the monofilament
winding / bipolar drive have similar pull-in and pull-out torque characteristics
when other parameters are the same. |
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