Stepper Motor as an alternator/generator
Philldapill
Posts: 1,283
I've got a TON of stepper motors that I haven't sold off yet and want to toy with some. I'm always thinking of new things to use a propeller for, and I thought about using a stepper motor to generate electricity. Attaching a simple blad assembly to a NEMA 23 stepper outputs a decent amount of power. I could hook one of these up to a step-up converter and charge some 12V batteries with it. Just a thought, remember, but how about using the propeller to do some MPP tracking and adjusting the step-up freq/duty/etc.?
Anyone ever used a stepper as a generator/alternator before? Any thoughts?
Anyone ever used a stepper as a generator/alternator before? Any thoughts?
Comments
An other use for steppers is as rotational incremental pulse generators. I've slaughtered quite many 3.5" disk drives, using the stator plates for construction of bldc·motors (they make great generators..)·and the stepper (originally for positioning the head) as pulse generators
I've never worked with them w/micros and need to add it to my education (and the Cookbook)
PM me.. [noparse]:)[/noparse]
OBC
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I don't have any data except for my assumption that you will probably get a maximum power output at a particular speed. The reason, is that as the speed increases, the frequency of the sinewave output increases, and since these have a fairly high inductance, the impedance of the motor increases, limiting the current output.
http://forums.parallax.com/showthread.php?p=720860
-Parsko
Thank you for the link. It is clear the stepper motor is a poor generator, although I cannot find any hard data.
So the question is, can any common electrical machine be converted to a reasonably efficient generator ?
I know a vehicle alternator needs high revs which are not easy to achieve, and the Fisher&Paykel washing machine motor has some cult status amongst antipodeans - anything else ?
The alternator setup also has the slight problem of needing an external power source to drive the field coils. This isn't usually a bad thing, except when you already have depleated batteries to begin with. However, as for the high revs, you can always get some fairly cheap sprockets and toothed belts from mcmaster. You can build a 5:1 gear-up linkage for well under $20(including bearings). I just might do that.
On another note, I ran some tests today on my stepper motors. First, I had a makeshift blade set attached to it since it was a windy day, but it only output about 10ma @ 12V. I then attached the motor shaft to a drill and found that the power output would increase as a square of the rotation speed, then start to drop back off and level off at about 1/3 of the max power output(100ma LOL). I did this using a double voltage multiplier, utilizing a single multiplier for each of the two phases. I imagine I could use a propeller to "tap" different stages of the muliplier to get the most power out of the motor. Kind of like changing gears on a bike or car.
were often used in 5+1/4 inch floppy drives in the late 20th century. (And other kinds as well.)
Putting a crank on one allows illumination of at least 8 super bright white LEDs at a reasonable cranking speed,
and it blows them at an unreasonable cranking speed. And that is without gearing, which impresses
me because I am not sure what other kind of motor will provide useful voltage and current if you
simply hand crank the shaft without gears. This makes a nice and simple hand powered flashlight torch.
Another thing that will happen is if you connect two of these stepper motors together and crank one,
the other one will turn synchronously, although only within a range of speed, yet this range of speed
is within reasonable hand-cranking speeds. Again, I don't know of any other kind of non-geared motor
that will generate enough power to run an identical motor if hand-cranked. There is 4 phase power.
Conclusion: It seems to me that at least that kind of stepper motor generates a useful amount of power
when it is hand cranked. It seems to me to be exceptionally useful for generation compared to
other common motors, in general.