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Stepper motor for wind!

Wond3rboy

Member
Hi i wanted to make a little wind generator as a home experiment and went out and got a 2 step,only clockwise running stepper motor from an old printer.I want to know will it generate enough amps for my ni cad cells?Will it generate electricity at all?
 

tcmtech

Banned
Most Helpful Member
It will generate some but its output voltage will be alternating current so you will need to run a diode set on it. The actual output voltage will be proportonal to its speed.
I have no idea how much voltage ot total power you will get from it either. Plus those little stepper motors dont ususaly have much for bearings and it may physicaly ware out rather fast. But its hard to say. Some steppers do have actual ball bearings in them too.

You may only get a few volts at a few hunderd milliamps for actual output. build it and find out! I could be way off too!
 

Grossel

Well-Known Member
Amps and voltage vary from motor to motor.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
As suggested, try it and see - EPE did a hand powered LED torch using a steppera gfew years back. However, I can't help but think that a normal DC motor would be a better bet.
 

Grossel

Well-Known Member
Actually - I think a stepper motor may work well as generator - but within a certain rotation speed. I have some few steppers lying around, and I know if I short the wires, then I get sensible rotation resistance. For a DC motor, my experience is that cheap models (in toys) usually doesn't provide much power when used as generator. I have actually tried that out with an dremel connected to a cheap engine.
 

Wond3rboy

Member
As suggested, try it and see - EPE did a hand powered LED torch using a steppera gfew years back. However, I can't help but think that a normal DC motor would be a better bet.

I do have a simpe DC motor.I got myself a printer stepper motor since i saw a video on youtube in which a guy was lighting an LED(very brightly i should say) with only a little rotation from a stepper motor.
 

duffy

Well-Known Member
I would think a stepper would make for a good small generator. There's no brushes to wear out or cause friction.
 

Sceadwian

Banned
Yeah but the output of a stepper is multi phase AC, harder to rectify, DC motors you can use with just a simple filter cap.
 

be80be

Well-Known Member
You could change the windings in it I been thinking about trying a bldc motor to make a wind generator and the ones I have are made very good. It has needle bearings and is rated a 35 watts 24 volts cond. I figure I'll have a $8000.00 generator LOL thats what the copier cost I got them out of:D
 

Grossel

Well-Known Member
Yeah but the output of a stepper is multi phase AC, harder to rectify, DC motors you can use with just a simple filter cap.
Disagree. But rectifier design may vary based on type of stepper motor.

For an unipolar stepper, there could be two set of regular rectifiers (four diodes) and put those in parallell - then you should get a pretty much smoother dc voltage than from only one set of rectifier (one phase generator).

For a 6 wired stepper, four diodes should be enough to get the same result.
 

Sceadwian

Banned
Okay so eight diodes with at least what 2 or 4 diode drops as loss, as opposed to a brushed Dc motor with a capacitor???
 

be80be

Well-Known Member
dont look good
DC Generators

* Advantages: Simple and pre-assembled, some are good at low rpm.
* Disadvantages: High maintenance, most are not good at low rpm, large sizes very hard to find, small ones have limited power output.
* Suitability for Wind Power: POOR to OK
A brushless DC permanent magnet motor is really just a permanent magnet alternator! A special driver circuit provides AC power that is in phase with the rotation. If you are able to find a large one of these surplus, it's possible you might have an excellent start for a wind power project. They are used in robotics and precision control applications, and some use Nd-Fe-B magnets for high torque in a small space. As with surplus tape drive motors, we would not trust the bearings to stand up in a wind power application...add more bearings so you don't ruin the motor's original front bearing.
 
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Wond3rboy

Member
Altough this is my first wind generator(using stepper motors) i have tried using Dc motors(12v) and they gave very little output. The only problem with stepper motor(mechanical) will be(my assumption) is the large torque required to get it rotating.I guess extra large blades will do the trick?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Altough this is my first wind generator(using stepper motors) i have tried using Dc motors(12v) and they gave very little output. The only problem with stepper motor(mechanical) will be(my assumption) is the large torque required to get it rotating.I guess extra large blades will do the trick?
You're perhaps missing an obvious point, DC motors need to rotate pretty fast to give decent outputs, a stepper is a slow speed device, so doesn't need to spin anywhere near as fast.
 

Grossel

Well-Known Member
Okay so eight diodes with at least what 2 or 4 diode drops as loss, as opposed to a brushed Dc motor with a capacitor???
You should learn how a multiphase rectifier work before posting.

If the stepper motor has six wires, it's easily done with only four diodes with a voltage loss equal one diode.

It's the same way as for a transformator with a center tap, but here you'll have two such outputs with different phases.
 

be80be

Well-Known Member
In generating power. Loss from a bridge is little. because of the higher voltage a stepper would put out
Sceadwian makes power from dead cels and in his work there can be no loss so he has a point. He lit two leds from nao volts
That's making power from nothing. But we are making power from wind. A little more air blowing there for a bigger genrator.
 

be80be

Well-Known Member
I tried a Shnano Kenshi STH-46D017-05 stepper with a drill to drive it at 600 rpms it put out 5 volts per lag. a small 5 volt dc motor my drill it wasn't able to go fast enough to get the full 5 volts
 

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be80be

Well-Known Member
Wond3rboy after reading your post I tried out some stepper and the one's out of old floppy
drives worked the best this is a HPM-215-24A it put out all most a amp and over 12 volts starting at about 100 rpms and at about 300 rpms it hit 24 volts
 

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Silversolar

New Member
Using a stepper motor as a generator looks promising, for those who wants to build a toy wind turbine, hydro turbine or steam turbine that will power LED's or charge small batteries. The ends of the stepper windings can be connected to a full-bridge rectifier to convert the polyphase AC output into DC with a filter capacitor. Just a tip about toys, it is one thing to make it work, it's another thing to keep it working.
 

Mr RB

Well-Known Member
I did research on this a while back with an eye to releasing it as a schools project. The following is from memory;

Steppers are great for simple wind power, if you get a NEMA-23 stepper (about 51x51 mm ?) the bearing are good for about 6kg axial and radial loads, great to attach a small turbine blade set directly to the stepper shaft. The flywheel effect of most blades (say 24" to 36" diameter) is enough to overcome the cogging force of the stepper.

Older stepper motors in the 12v range NEMA-23 are about 0.5 amps and will charge a 12v battery even at modest wind speeds. The 5v 1A steppers (also common) will charge 6v battery.

Rectifying is easy enough; if it's a bipolar stepper just use 2 full bridge rectifiers into the one filter cap. If a 5-wire unipolar type connect the common to cap ground and use 8 diodes as a multiphase rect.

It's better to use a stepper motor wound for higher volts lower amps. These produce more usable power at the very low windspeeds typical of suburban backyards.

And those sheet metal fans they sell at the automotive shop for cars (about 18" to 24") work pretty good.

And remember this is micro wind power, enough to run little gadgets in low wind but not suitable for higher power use and/or high wind/tall mast applications.
 

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