Question

A 3-phase stepping motor is to be used to drive a linear axis for a robot. The motor output shaft will be connected to a screw thread with a screw pitch of 1 mm. We want to be able to have a spatial control of at least 0.05 mm. a)How many poles should the motor have?

Answer 1

The number of poles is 12.

Step-by-step explanation:

The step angle is given by

`\phi=(360^(\circ))/(N)`

Where

`\phi_1` is the step angle

To Find the Step angle of the Stator

`\phi_1=(360^(\circ))/(N_s)`

Where

`\phi_1` is the step angle

`N_s` is the number of poles or teeth on stator

To Find the Step angle of the Rotor

`\phi_2=(360^(\circ))/(N_r)`

where

`\phi_2` is the step angle

`N_r` is the number of poles or teeth on rotor

In the question it is stated that

`N_s+ N_r = (1)/(0.05)`

`N_s+ N_r = 20`

Selecting
`N_s`= 12 and
`N_r`= 8

`\phi = \phi_2 -\phi_1`

`=((360^(\circ)))/(8)- ((360^(\circ)))/(12)`

=
`45^(\circ)-30^(\circ)`

=
`15^(\circ)`