stepper motor & frequency problem

Thread Starter

tracker

Joined Jun 1, 2011
41
Hi guys, i'm trying to drive a stepper (full-step) at a rather high frequency (5kHz).

I was told under load, there are certain 'harmonics' or frequency range which the stepper would just stall and refuse to drive.
I Add that when i drive it at 50 Hz it works.

Is this true? Can someone explain the theory behind it? And how can i find this range of frequencies to avoid?

I tried googling for it but i'm getting inrelevant results (i think harmonics is not the right keyword).

Many thanks in advance!
 

beenthere

Joined Apr 20, 2004
15,819
In addition to those harmonics, you generally have to start the motor at a lower rate and increase to the maximum over time. Check your motor specs, too - some will not step that fast.
 

SgtWookie

Joined Jul 17, 2007
22,230
5kHz is a mighty zippy step rate - particularly when you don't have access to the motors' specifications.

As Beenthere says, you can't start and stop stepper motors instantaneously - you have to increase/decrease the stepping rate gradually. This is to overcome the inertia of the motor itself. If you have a heavy load attached, that will also impact the rate of acceleration/deacceleration that your motor will be able to handle - and you'll wind up with it just buzzing instead of rotating.

The faster a stepper motor turns, the less torque it will have, due to the amount of time it takes to get the current flowing in the motors' windings - so at some point, the motor simply will not be able to turn any faster, even if you have no load attached.
 

Thread Starter

tracker

Joined Jun 1, 2011
41
5kHz is a mighty zippy step rate - particularly when you don't have access to the motors' specifications.

As Beenthere says, you can't start and stop stepper motors instantaneously - you have to increase/decrease the stepping rate gradually. This is to overcome the inertia of the motor itself. If you have a heavy load attached, that will also impact the rate of acceleration/deacceleration that your motor will be able to handle - and you'll wind up with it just buzzing instead of rotating.

The faster a stepper motor turns, the less torque it will have, due to the amount of time it takes to get the current flowing in the motors' windings - so at some point, the motor simply will not be able to turn any faster, even if you have no load attached.
very helpful cheers
 
Top