Question

Question 1

A stepper motor advances 2.5̊ per step.

How many pulses are needed to complete 3 revolutions?

Explain what is meant by normal drive, wave drive and half-step drive.

Why is viscous damping employed in stepper motors?

When a stepper motor is ramping or slewing properly, every pulse corresponds to a precise angle of rotation. True or false?

Answer 1

1) Given, stepper motor advances 2.5⁰  per step.

Hence 2.5⁰ = 1 pulse

n pulses =

Therefore, no: of revolutions needed to complete 3 revolutions

So, 432 pulses are needed for the stepper motor to complete 3 revolutions.

Half - step drive:

Half-step is the mode of operation in which the drive alternate between normal wave drive and creates a half-step of rotation.

Wave drive:

In this drive method, only a single phase is activated at a time. It has the same number of steps as the full-step drive, but the motor will have significantly less torque than rated. It is rarely used.

Normal drive:

Normal drive is the mode of operation of stepper motor in which two sets of field coils are energized simultaneously to cause one step of rotation

Damping in stepper motor:

In a stepper motor, the damping should respond to changes in velocity. this is achieved by using viscous damping.

A straightforward way to control resonance is to deliberately add damping to the system.

It is possible to introduce damping which responds to changes in velocity by using a viscous coupled inertia damper (VCID). This consists of an inertial mass which is free to rotate on the shaft of the stepper motor but is coupled to it via a viscous substance. At a steady speed, the shaft and mass will rotate at the same velocity, but if the motor changes speed, the inertia of the mass will introduce damping.

True or False: Yes, when a stepper motor is ramping or slewing properly, every pulse corresponds to a precise angle of rotation.