Inductance Turkey Dc Stepper Motor, Turkish Dc Stepper Motor make the stepper motor driver for a 3D printer

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Inductance Turkey Dc Stepper Motor, Turkish Dc Stepper Motor  make the stepper motor driver for a 3D printer

The inductance of the motor affects how fast the stepper motor driver can drive the motor before the torque drops off. If we temporarily ignore the back emf due to rotation (see later) and the rated motor voltage is much less than the driver supply voltage, then the maximum revs/second before torque drops off is:

revs_per_second = (2 * supply_voltage)/(steps_per_rev * pi * inductance * current)

If the motor is driving a GT2 belt via a pulley, this gives the maximum speed in mm/sec as:

speed = (4 * pulley_teeth * supply_voltage)/(steps_per_rev * pi * inductance * current)

Example: a 1.8deg/step (i.e. 200 steps/rev) motor with 4mH inductance run at 1.5A using a 12V supply, and driving a GT2 belt with 20 tooth pulley would start losing torque at about 250mm/sec. This is the belt speed, which on a CoreXY or delta printer is not the same as the head speed.

In practice the torque will drop off sooner than this because of the back emf caused by motion, and because the above doesn't allow for the winding resistance. Low inductance motors also have low back emf due to rotation.

What this means is that if we want to achieve high speeds, we need low inductance motors and high supply voltage. The maximum recommended supply voltage for Duet 2 WiFi/Ethernet is 25V, for Duet 2 Maestro is 28V, and for Duet 3 is 32V.

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