I think they mean "senseless" in that there is no sensor inside the motor. They are just sensing current which could be external to the motor.
I tried this on a brushed motor. I wanted to avoid the need for an optical encoder. I figured i could simply measure current. I guessed that a motor does not pull equal current as it moves around. I thought current might drop as a gap passed under the brush or as a coil passed a magnet. I went "primitive" and simply placed a resister in series with my motor and used the resister, or the voltage across it, as a current sensor. It did not work at all. A 100% fail. The noise caused by the brushes is orders of magnitude higher than the signal. But it might work if there are no brushes. Seems that it does work and the Hall effect sensor wastes less energy than my resister would.
Maybe if you have a brushless spindle motor you can avoid buying a tachometer for it, tap into the commutating circuit somehow. But with a brushed motor all I got was white noise.
On Sat, Mar 24, 2018 at 7:25 AM, Ralph Hulslander rhulslander@gmail.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
Actually they are using Hall Effect "sensors" for position.From the Atmel page:" So, commutation via interrupts becomes simple if each change of a Hall sensor signal forces an interrupt. Then, the actual set of Hall sensor signals defines the commutation sector. "The other ones do the same.I am not sure why they say "Sensorless".RalphOn Sat, Mar 24, 2018 at 8:40 AM, old_toolmaker@yahoo.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:One question I still have is if steppers can both spin and step, why do both steppers and BLDC motors exist? I seems the stepper is more versatile.
Chris Albertson
Redondo Beach, California
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Posted by: Chris Albertson <albertson.chris@gmail.com>
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