2
\$\begingroup\$

I need a stepper that has the highest possible holding torque (when power is on) and smallest possible cogging/detent torque (when power is off). This goes back to the holding/cogging ratio - is there a general rule on this ratio or does it differ on a product by product basis?

My application is on a vehicle with dual mode Ackermann steering where I need possibly high torque for automated mode (steering by electronics without human intervention) and I need small cogging torque when in manual mode (steering by hand - the stepper should not have much mechanical resistance so that the steering is not made much harder - ideally zero resistance).

Regarding mechanical solution - because of simplicity the plan is to have a something like a "single stage gear reducer" where there is a big gear on the steering column which directly touches a small gear on the stepper thus giving the stepper quite some power to turn the steering.

\$\endgroup\$
  • \$\begingroup\$ Why not direct drive with brushless DC motor? \$\endgroup\$ – Gregory Kornblum Apr 14 '16 at 4:21
  • \$\begingroup\$ I think a switched reluctance motor might do what you want. I am not an expert on such things, but I believe they have zero cogging (since there is no permanent magnet). \$\endgroup\$ – mkeith Apr 14 '16 at 7:25
2
\$\begingroup\$

You need a variable-reluctance step motor. They are available from 24 to 200 steps/revolution. With zero excitation, they spin freely. There is no permanent magnet.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.