Friday, November 8, 2019

Related to one-two phase-on stepper driving is microstepping

A stepper drive is the driver circuit that controls how the stepper motor operates. Stepper drives work by sending current through various phases in pulses to the stepper motor(23hs45-4204s17hs16-2004s1.) There are four types: wave drives (also called one-phase-on drives), two-phase on, one-two phase-on drives and microstepping drives.
Microstepping delivers very fine motion resolutions. Here, the drive uses current regulation to prevent torque oscillations. With this technique, engineers can use stepper motors in more applications.
In sort, a drive that is microstepping increases and decreases current along a sine wave, so no pole is fully on or off. Here is a sample microstepping sine-wave current:
Stepper Drive Microstepping Current Sine-Wave
Note the subtle jagged contour of the sine-wave current. While microstepping doesn’t necessarily improve accuracy, it does get higher resolution than other driving modes—which is particularly helpful for applications in which the motor goes through no-load situations. During operation, motors can miss steps. However, microstepping spreads energy out instead of delivering it to the motor all at once, which can cause ringing and overshoot.
For all of these forms of driving, the motors can have different windings. Unipolar stepper motors nema 17 only accept positive voltage. Unipolar requires an extra wire in the middle of every coil to let current flow from one end to the other. Bipolar stepper motors use both positive and negative voltage. Bipolar stepper motors have more torque because they produce a stronger magnetic field, but their construction also requires more wire.

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