_Vague_ Stepper Motor Question:

What is the maximum rate one might expect to step from phase to phase?

Thanks!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 02 Oct 2010 23:00:45 GMT, (Nico Coesel)
wrote:

Jim Thompson
wrote:

_Vague_ Stepper Motor Question:

What is the maximum rate one might expect to step from phase to phase?

Depends on the maximum dissipation. I did manage to get a big stepper
(2.5A) to about 6000 steps/s (1800 rpm) with a single ended driver.
But it was necessary to ramp the speed up & down. Nowadays I think I
would use a servo motor with a position encoder or at least drive the
steppers with a full bridge PWM and feed the motor sine waves unless
halted at some point. The biggest problem with steppers is that you
can miss a step and you have no way of knowing unless you add the
encoder.

OK. I'd guess my thoughts of adding 100ns safety against H-bridge
crowbar-overlap wouldn't be a speed-limiting idea :-)

(This is an RFQ with less than marvelous explanations :-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I can see November from my house :-)

"Jim Thompson" wrote in
message ...
_Vague_ Stepper Motor Question:

What is the maximum rate one might expect to step from phase to phase?

Thanks!

...Jim Thompson

Depends on the motor, inertial load, damping, type of drive...

I work mostly with size 17, 1.8 degree/full step motors. We designed our own
microstep drive and typically run at 30 rev/sec. A lot depends on ramp rate,
start/stop velocity and avoidance of any speed where resonance can become a
problem. Most 1.8 degree steppers experience the worst resonance at about 1
revolution/second.

What do you have in mind?

Oppie

On Sat, 02 Oct 2010 20:23:17 -0500, flipper wrote:

On Sat, 02 Oct 2010 23:00:45 GMT, (Nico Coesel)
wrote:

Jim Thompson
wrote:

_Vague_ Stepper Motor Question:

What is the maximum rate one might expect to step from phase to phase?

Depends on the maximum dissipation. I did manage to get a big stepper
(2.5A) to about 6000 steps/s (1800 rpm) with a single ended driver.
But it was necessary to ramp the speed up & down. Nowadays I think I
would use a servo motor with a position encoder or at least drive the
steppers with a full bridge PWM and feed the motor sine waves unless
halted at some point. The biggest problem with steppers is that you
can miss a step and you have no way of knowing unless you add the
encoder.

Just a passing thought but seems to me it should be theoretically
possible, at least, to detect step movement by the inactive coil's
back EMF.

My 3-phase motor driver for Bosch/Mercedes did exactly that... and
used it for commutation.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I can see November from my house :-)

On 10/02/2010 07:05 PM, Jim Thompson wrote:
On Sat, 02 Oct 2010 20:23:17 -0500, wrote:

On Sat, 02 Oct 2010 23:00:45 GMT, (Nico Coesel)
wrote:

Jim
wrote:

_Vague_ Stepper Motor Question:

What is the maximum rate one might expect to step from phase to phase?

Depends on the maximum dissipation. I did manage to get a big stepper
(2.5A) to about 6000 steps/s (1800 rpm) with a single ended driver.
But it was necessary to ramp the speed up& down. Nowadays I think I
would use a servo motor with a position encoder or at least drive the
steppers with a full bridge PWM and feed the motor sine waves unless
halted at some point. The biggest problem with steppers is that you
can miss a step and you have no way of knowing unless you add the
encoder.

Just a passing thought but seems to me it should be theoretically
possible, at least, to detect step movement by the inactive coil's
back EMF.

My 3-phase motor driver for Bosch/Mercedes did exactly that... and
used it for commutation.

It's commonly done for 3-phase brushless PM motors. I don't know if
it's been done much for steppers, although I'm sure that _someone's_
tried it.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

What is the maximum rate one might expect to step from phase to phase?

Do you want normal max or far-out-craxzy max?

With a big of googling, I'f found 55,000 RPM and 1.8 degree steps.
That's 200 steps per revolution. Round 55 to 60 and we have 1000
RPS. At 200 steps per revolution, that's 200 KHz.

Round up some if you want to be conservative. Round down some if
you think I'm crazy.

[I've never played with stepper motors.]

--
These are my opinions, not necessarily my employer's. I hate spam.

flipper wrote:

On Sat, 02 Oct 2010 23:00:45 GMT, (Nico Coesel)
wrote:


Jim Thompson
wrote:


_Vague_ Stepper Motor Question:

What is the maximum rate one might expect to step from phase to phase?

Depends on the maximum dissipation. I did manage to get a big stepper
(2.5A) to about 6000 steps/s (1800 rpm) with a single ended driver.
But it was necessary to ramp the speed up & down. Nowadays I think I
would use a servo motor with a position encoder or at least drive the
steppers with a full bridge PWM and feed the motor sine waves unless
halted at some point. The biggest problem with steppers is that you
can miss a step and you have no way of knowing unless you add the
encoder.


Just a passing thought but seems to me it should be theoretically
possible, at least, to detect step movement by the inactive coil's
back EMF.
YEs, it is possible, I've done it working with eddy current type
brakes/clutches..

When the unit is not in slip, induction of the coils are a
constant how ever, when they slip, you get an effective induction
change which can be detected..

The same basic theories hold with other types of devices on the same
line, DC motors, steppers etc..

We were able to create a slip detector on a machine that employs a
tape dispense that wraps around the shield of cable as you pass it
through the center of the mount that holds the tape pad. The pad is
mounted on a disc that has a eddy current brake for tension control and
gets it's current via a set of slip rings (collector rings for some
people). With 2 wires as the supply we were able to detect slip
(movement) using a pulsed power supplied and detector circuit on this
pulse.. This was to detect if the tape broke/ran out in the process and
stop the machine.

Since these tapes are clear and on moving mast, it's kind of hard
otherwise.