AC Servo Motor for Generator

[welldog]

I have a AC servo motor that seems to be a good canidate for a wind generator.  It sounds like, by the nameplate that it is built like the 3 phase motors that people here turn the rotor on and add magnets.  

I will add a pic of the nameplate soon.

I made a set of blades from CmeBrew's pics.  My first at that also.  Not sure what the end diameter is going to be for this project.  Will have to do some testing and question asking.  

Here are the blades.  Took about 1 1/2 hours to make and about $5 in materials.

Now to get the blades on the genny and mount everything to test. This is a great learning experience.  The posts on here are great reading.

Will keep updating as the project continues.

[welldog]

Here is the nameplate

data.http://www.otherpower.com/images/scimages/10844/MotorDataRS.JPG

Just for fun I hooked up a 1/2 drill to 2 leads of the motor and spun the motor shaft and the drill will run as long as the shaft is turning.

[CmeBREW]

Looking good Welldog!  

   It is even more exciting to see the amps flowing into the batteries! (because it means watching TV that evening,etc, etc)

Looks like that may have a 12v cut-in of around 100rpm like my big servo I just got.

From my limited experience, I would probably try a 7' diameter prop with that particular servo with those straight profile blades myself-- and then cut them down little by little if need be. Looking at the rated amps, maybe a 6.5' diam??

You just have to experiment.

Thats one of the problems, not going TOO short of blades and sacrificing power in lower winds!

It seems that rounding the blade tip corners (about 3/4") reduces the wirling noise better.

[GeeMac]

Link to that FANUC 30S

http://www.uptimecorp.com/PartData.aspx?ID=62385

[welldog]

Just a note.  if you are going to get one  of these motors for a generator.  If you go to the link above,  The plug closest to the shaft end means that it has a brake on it.  This brake has to be energized for the shaft to turn.  There are motors out there with the same specs that do not have the brake.  The motor I am using does not have the brake.

Welldog

[ghurd]

Now you tell us.  :-/

Yes, watch out for the brake.

G-

[scorman]

Just a few comments on blades as compared to the thread your referenced:

Mount these with the flat side to the back side of the mounting plate

so that the flat side faces the wind, but now you can use four symetric mounting bolts spaced as far apart as possible for more solid mounting.

You can then use washers as spacers on the trailing edge set of two bolts to increase the pitch angle ... experiment to see what works best

If you have a steel mounting plate, use three short scrap 2x4s as "spars" instead of the plywood mounting plate, and then you can experiment with different rotor diameters as well as pitch angle.

The center 1/3 of any HAWT only accounts for 11% of the wind intercept area, and runs at poor AOA anyway, so his 5 foot blades could be mounted as a 15 foot turbine!

look at DaveB's Wincharger with root going out 2+feet

the trailing edge of the blades needs to be as close to a "knife edge" as possible ... most here keep it around 1/8"

use a router with a large cove cutter to make the lower leading edge uniform

I have posted my wind calculator in my uploads which can tell you what rpm you'll get for a presumed TSR (use TSR=6 for a start) for any given rotor diameter at diff WS

plug in a number where you see a number in red

http://www.otherpower.com/images/scimages/7526/windpower.xls

that servo looks great ...it runs at 7.7v /100rpm (from nameplate)

with the high current rating, the coils are probably very low resistance

If you didn't want to charge batteries or go to a 48v system, a 3:1 gearing will give you higher voltage and less line losses

you can probably go way over the 156v rating with gearing, since that is a "power in" rating and your amps would be quite low at high voltage limited by the powwer of the turbine ..we have run servos at 4x rated voltage

best of luck on your project,

Stew Corman from sunny Endicott

[welldog]

"If you didn't want to charge batteries or go to a 48v system, a 3:1 gearing will give you higher voltage and less line losses"

"you can probably go way over the 156v rating with gearing, since that is a "power in" rating and your amps would be quite low at high voltage limited by the powwer of the turbine ..we have run servos at 4x rated voltage"

Maybe a dumb question,  You state that  "If I don't want to charge Batts or go to a 48V"  What else would you do?  I am open to any suggestions.

Also, If this can be geared 3:1 and get 4X rated voltage.  That would be around 600V  three phase.  Is that correct?  What type of load would you run with that?  Would this be possible to run a resistance heater of any size due to the voltage being high and the amps low?  

I have seen posts on here where Zubbley had put together a heater that was something like what I am talking about.  He had mounted it in his ducting.  This could be very interesting.

Thanks for all the input.

Welldog

[welldog]

Ghurd,  This could be a good thing.  If you had a small circuit that would energize the brake and allow the motor to spin with a speed controller you could stop the genny for overspeed, maintenance and other things. That is a serious brake on there.  Also.  The brake can be removed pretty easily.

Just a thought.  BTW,  I do have one of these motors with a brake on my bench that will be the next project, So I will have better info the next time.

Welldog

[ghurd]

The brake on mine seems to be 24V, and Very power hungry.

Mine would use more power than it made, even if I had 24V.

It is not nearly as big as the ones shown.  NIB No-Data Sanyo-Denki Mystery-Motor, maybe 1 or 200W.

I haven't tried to take out the brake, but will.  Eventually.

Also people should know taking servo motors appart can lead to then not working as well, or at all.  

(Also got one that was tinkered with, 2VAC at 650RPM.  eBay and my standard luck with servo motors hasn't been good.)

G-

[scorman]

Welldog,

Perhaps I was jumbling too many thoughts into a few simple sentences.

"Also, If this can be geared 3:1 and get 4X rated voltage.  That would be around 600V  three phase.  Is that correct? "

no not really ... I had a 24v DC PM motor that was rated at 194rpm ..we used a vbelt at 2:1 and got it up to 100v, so the turbine was spinning around 400rpm, motor shaft at 800rpm ...you have to know how fast you expect the turbine to spin, then figure the pulley ratio to match. You can't get out more than 35% of the power in the wind.

If you don't charge batteries, you can heat at 100% efficiency using a calrod heating element (cheap) in a domestic hot water tank like DaveB does ie preheat your water when the wind blows

Charging 12v battery is the worst option you can choose, and 48 volt charging is commonplace. Remember that battery charging is inherently 70% efficient.

Simple ohm's law dictates how much voltage loss you get in the wire that brings the juice to your home. I can run 230v/3phase at 4amps (3KW) 250 feet to the house with #12 wire

V=IxR

P=VxI=V^2/R=I^2xR

if the voltage is 5x, then the amps is 1/5x ...resistance in the wire stays the same once you buy it

so, either you choose very thick expensive wire for low voltage/high current, or very thin inexpensive wire for high voltage/low current

If you look at my calculator, you can get the rpm for any combo of turbine diameter built, TSR (assume=6) and WS ...then you pick the pulley ratio to get the voltage you want out

From that rpm, you now know what voltage you will get BUT, you have to look to see how much power is in the wind and multiply by the efficiency Cp= 0.35

Once you know max power you get when the rotor furls and some WS, you can pick out a resistance element that matches it ...you can't pick a low ohms load and put 600v thru it ...that would be 10KW and the wind only has 1 KW ...can't be done ...might as well short the leads

Another factor is the servo winding resistance.

For a 12 volt system, it is possible that the voltage drop at the servo = voltage across the load ...so 50% of power generated is lost to atmosphere up the tower.

If I run my 220v/3phase into a 3phase bridge to get me 1.4x DC voltage, then 230v becomes 322 volts DC ..if for my 10 footer, I furl at 25mph, then the max power I expect is 1.5KW, so I'd need a 69 ohm load   R=V^2/P = 322x322/1500=69 ohms

However, if I furl at 20mph, the max load will be 1KW and I can use a 103ohm load

Since my servo has (3) 3ohm windings, the most I lose up the tower is < 10% or so.

Hope this helps ,

Stew