have I got the gist of this?

[bcalmed]

After lurking for a couple of years, I've decided to try to assemble (I'd say build, but that's such a strong word) some sort of wind turbine. I tracked down a free GE 1hp ECM and I rewired it by splitting the wye point and bringing out 6 leads. I've hooked the wires from the 3 groups of 6 coils to 3 bridges, parallelled the +/- outputs. I plan to use this for 12v charging for camping and just for fun as a learning tool.

Using highly sensitive equipment - my ears - I believe I can spin it up to ~1700 - 2000 rpm with a hand-held 2500 rpm drill. Open circuit volts on a $4 HF DMM are 140+/-. So, if all my reading here has sunk in at all, and if the voltage/rpm ratio is linear(ish), I think I need to series/parallel the groups of 6 coils to both raise the cutin speed (to avoid stall) which should increase the current available above the higher cutin speed.

I have "crafted" some 33" PVC blades (that's how long the free piece of PVC was) and had a buddy with a waterjet rig cut me a 3 blade hub from some 5/16" scrap steel plate. The total diameter is ~70". I have no idea of their TSR as I haven't flown them, but I guess they're reasonably "fast".

Is the open circuit voltage way too high the way it is now?

Should I series/parallel the 6 coils into 3 groups of 2 instead of 2 groups of 3?

Can one mix/match the wiring of the 3 groups of 6 - ala one 6 series, one 3/2, one 2/3?

What voltage should I be looking for with no load?

What am I doing here?

I throw myself upon the mercy and knowledge of the ghurd ru and anyone else who deigns to respond.

[Rover]

Quick question, the blades are 33" each ? for roughly a 70" swept area? .. .

Might be to big to obtain the rpms required...(quite certain it will be)

2) maybe I misread, but you are bringing  down each phase, (GE ecms are 18 coils, split into 3 x 6(series) coils) , for 12 volt charging, I and others ... have found that the voltage rises to fast ... and you tend to plateau , and stall .

Search out Jery's posts on wiring for 12 volt

[ghurd]

I decided no 2 ECMs are exactly the same.

"Is the open circuit voltage way too high the way it is now?"  Yup.
It is really not the high voltage as much as the high resistance, though both play their own parts.

The volts seem a little low.  I can get 70VAC per phase by spinning the shaft between my palms.  Maybe they peak out too, I never spun one that fast.
Chuck it in a drill press and spin it at a lower RPM?  Maybe ~500 and ~750 RPM?

3 series coils, in parallel with the other 3, per phase, will get 12V cut in below 200RPM. (?)
That may be good for camping?  Quiet.  Not a lot of amps.  Good low wind charging if it does not stall really bad.
Will need 8" PVC (I think) to give it some torque and hopefully keep it from hard stalling.

3 parallel pairs per phase will raise the cut in to somewhere a little under 300RPM. (?)
With PVC blades, probably want them quite a bit shorter than 33" / 70" dia.
Will still be quiet.  Amps will be more (may not be desirable to have too many amps while camping anyway).

Could mix/match.  I thought about it a lot.  Not sure what I think about it.  Full of Catch 22s.
Pretty sure leaving one phase with all 6 in series is not a good idea.
I would probably go one phase 3 series in parallel with the other 3, and the other 2 phases 3 series pairs each.

Pretty sure it will work better with shorter blades either way.

'What voltage should I be looking for with no load?'
Depends on what you want to do, and what kind of blades you want to use.  Again full of catch 22s.

'What am I doing here?'
Having fun, I hope!
G-

[bcalmed]

Rover & G-,

Thanks for the advice. I think I've read Jerry's posts about ECM's so many times they're wearing out. I find that some things only penetrate my skull when I DO them - or try to.

The free PVC I used for the blades was 10" dia. and I did the sort of "wide, curved flare at the root to skinny/straight slight taper starting at about 1/3 the way out" profile. My muddled thinking was to get startup grunt but not limit the top end too much. I cut the blades long before I had anything to spin with them. I figured I could always remove material, but couldn't put it back.

I'll figure out some way to drive it with a known rpm below 1k and check the AC volts on one phase for a baseline. It sounds like you're saying that trial and error is as good a formula as any with an ECM. I will mention that when I hook up the output to a 12.3v flooded battery, the cutin point (whatever rpm it is) is obvious from the load on the poor drill. It seems drastic - is that a common thing or a function of trying to jam too much juice too soon into the battery? It seems that the best scenario would give a more or less gradual cutin - hence the voltage question.

Could this be a rudimentary "matching" light-bulb moment.

I guess the practical variables are the size/shape of the blades and the wiring of the coils in the motor. The thought of bringing all the ends of all the coils out of the can seems daunting, but, once done, would certainly allow the easiest changing of wiring configurations. I'm liking your idea of the one 2/3 and two 3/2's but I think I'll do the rpm/volt testing first.

By next week, I should be able to mate the rotor to the motor and fly it with whatever initial setup seems best using the existing blades and see what happens.

Pics then...

My "tower" is guaranteed to make you laugh.

It's all fun so far.

[ghurd]

"The thought of bringing all the ends of all the coils out of the can seems daunting"
It is!
You really do Not want to go there.

Plus it makes 72 (minimum) potential spots for bad connections, and wires that wiggle (and snap).

Do the RPM tests before getting committed to a configuration.

The load on the drill is common.
'Click!'  goes the light bulb. 
The trick is to get the potential wind power to match up with the PMA output at the RPMs of each...
which uses a LOT of my pipe.   

Short the sucker and try to turn it.  (by hand, Not with the drill or the bridges could pop)
It does not prove anything, but its surprising.
G-

[jlt]

Yes i agree ecm motors a Quite different . I have one that had a round control on it,put out 38volts at 250 rpm & with square control box That put out 17 volts at 250 rpm.they were both 1/2 hp.

[bcalmed]

Short the sucker and try to turn it.  (by hand, Not with the drill or the bridges could pop)
It does not prove anything, but its surprising

Aha, NOW I see the reason to short the leads of an axial to stop it. Before the rectifiers, I'll bet.

I'm pretty sure I've read something about iron-cored machines not being so easy to stop that way, does that only apply when they're approaching runaway speeds?

What does the iron do to make that happen - or NOT happen?

[taylorp035]

By next week, I should be able to mate the rotor to the motor and fly it with whatever initial setup seems best using the existing blades and see what happens.

Nothing is more valuable than actually standing there with a volt/amp meter and watching it spin.  Maybe you can figure out some rpm/volt numbers for your different configurations, which then you can compare that to your diameter/ how fast the blades are.  70" diameter should be usable if you have lots of volts to play with.
Good luck!

[Ungrounded Lightning Rod]

Short the sucker and try to turn it.  (by hand, Not with the drill or the bridges could pop)
It does not prove anything, but its surprising

Aha, NOW I see the reason to short the leads of an axial to stop it. Before the rectifiers, I'll bet.

I'm pretty sure I've read something about iron-cored machines not being so easy to stop that way, does that only apply when they're approaching runaway speeds?

What does the iron do to make that happen - or NOT happen?

"Inductance limiting".  The field takes a bit of time to propagate into the core - especially when being fought by current in the coils and eddy currents in the core.  When the RPM gets above a certain point the more it rises (and thus the frequency rises, and thus the time spent with the mag field working inward before the poles move on and it switches to working back outward lowers), the less the field penetrates.  This limits generation, which limits braking torque.

[bcalmed]

ULR,

So the term "inductance limited" is the same phenomenon for generation and electrical (magnetic) braking?

Is it as if the "recovery time" is just too short or out of "synch" to work at higher frequencies?

[tecker]

 When setting up a motor stator to charge batteries a thing to remember is that the charger will see an impedance that goes from what measures to about a short to 30 to 60 ohms .
The wire size on the ecm is small . You need to group the speed windings as close  as possible for the power band . I find that if you bring taps out to the ground At least those that give in excess of your target cut in you can set up a good charge combination without too much trouble
 Run up your blade hub in moderate winds or take the gen set for a drive and load the charger down to get your max charge while not exceeding the amperage of the wire size in the motor.

[ghurd]

What ULR said.  Plus it is the same thing that limits the amps. 
In the beginning, the charging amps vs RPM are pretty linear. 
Eventually the amps hit a plateau.  Which is good, maybe, because I can not get enough charging amps in individual coils to get past the wire's limit.

Chart looks sort of like this-
  _____
 /
/

I have a feeling most iron core machines (meaning motors of some type) have too much resistance to short to a stop under severe conditions.

I Totally agree "Nothing is more valuable than actually standing there with a volt/amp meter and watching it spin".  And at many different wind speeds.
But I don't really agree about 70" being good with enough voltage, because leaving it wired that way limits the amps.  A lot.  And no reason to have 70" blade set with a relatively low potential output.  It all depends.

G-

[Rover]

As far the "plateau" you can see it one of my prior posts on an ECM with different wiring schemes

http://fieldlines.com/board/index.php/topic,140861.msg943404.html#msg943404

Notice that ones that start with lower cut-ins, tend to plateau quicker

[Rover]

I should add, this only relates to that specific ECM , and the wiring schemes I chose after I brought all the  wires.
 

[ghurd]

Hey Rover,
I think you ran out of RPM before actually hitting the plateau hard.

A friend tested a 1/3 or 1/2 HP.  Many people claim they are the same.
This chart is his.  If he want to take credit or have it removed, he can speak up!

It wired 'IRP' (regular Jerry rigged), each phase of 6 coils, in series, going to their own bridge rectifiers.
This is the total output into a 12V battery.

(it works a lot better with some re-connecting of the coils, as your comparative graphs show)
G-

[Rover]

This had to be 6 coils series, x3  then down regulated.. still too high for 12 v ... it does follow my pattern.. I just couldn't bring the curve far enough.

I didn't run of RPM ... ok rpm + torque... err yeah .. but still not bad for a B&D 1/2 drill (pos)

[bcalmed]

Lacking a third (and ideally a fourth) hand, I tried to measure the open volts/rpm with a laser(?) tach from our old friends at HF. Holding the drill, the ECM and the tach made for some shaky moments but it looks like about 42 vdc @ ~550 rpm. That seemed to be the speed where I could keep everything calm enough to read the DMM abd the tach at (hopefully) the same time. Being slightly walleyed helped a bunch.

Jerry's posts seem to recommend this configuration for 12v charging, but, as you all have been saying, I see that there's ECMs and then there's ECMs and then there's this here particular ECM.

Given these #'s - which I'll nail down (or clamp, or bolt, or bungee, etc.) - about where should I be for 12v charging?

I've got 2 abused, 3 year old 100ah deep cycle batteries which I'll series and, after I lock down all the moving parts, use to check the charging current @24v. It seems as if 12v would be too much of a mismatch. I'm not really clear on the whole"clamping" thing - at least as far as knowing how much is too much voltagewise. Isn't there a range above which more voltage is wasted or counterproductive?

More fun awaits...

bcalmed

[Rover]

I'm definetly for the rpm test into a battery... without alteration 24v could be an appropriate target.  But, before then make a decision on how you want to use ouput of a battery bank, is 24 v  suitable.. for a lot it can be, is 12 v suitable ... can be...for a lot as well.

..as far the laser doo-hickey rpm measurement thing from HF, I have a simiilar cheap unit .. and they are quite accurate. ( I tach mine against my drill press.. pretty close )

[bcalmed]

without alteration 24v could be an appropriate target.  But, before then make a decision on how you want to use ouput of a battery bank, is 24 v  suitable.. for a lot it can be,

These are my "camping" batteries and I usually use one 'til the inverter sqeaks, then switch to the other. we run CFL's, guitar amps, keyboards, PA's and mixing/effects boards off the inverters (and the occasional blender blast for the margaritas). I've got an 800W and a 400W (both cheap MSW) and I wonder if hooking one to each batt while they're seriesed would mess up the charging. I seem to recall  reading here somewhere that charging in series is more forgiving than in parallel, but I could be hallucinating.

bcalmed

[97fishmt]

Well I don't know why I can't get this point out there,
just get an AC Servo Motor.  I picked up another one
off ebay for $40. 

400 volt 16.5 amps @ 1500 rpm. It will make a nice
48 volt machine.

[bcalmed]

Well I don't know why I can't get this point out there,
just get an AC Servo Motor.  I picked up another one
off ebay for $40.

Hi,

I think it's "out there" and it's cool.

I have a free ECM...

...and $40 - and I'm doing this strictly for fun.

Enjoy yours and I'll do the same.

bcalmed

[ghurd]

Not sure I would go for 24V.
Seems to work out to the same power output in regular IRP with 6 in series for 24V, as it does for 12V with 3 in series.
The cut in is practically the same (with 6 in series for 24V, 3 in series for 12V).

The chart I posted above... the motor sticker says 208-220V, 2.8A, and that is in Wye (Star).
The chart shows a peak of about 4A, split between 3 phases is 1.35A, so it does not look possible to smoke the coils when used as a PMA.  When the phases are wired for half the open voltage, the amps double, but the max output amps in each COIL stay the same.

I know for a fact ECMs can smoke the coils when used as GE intended... eBay is full of them, which I also know for a fact. 

Just to get people thinking and increase the value of my aspirin company stocks - I have thought about IRP for some coils, and Wye for others.  Could do a bit of hardwired power matching.

My personal luck with AC servo motors has not been so great.  Brakes that can not easily be removed, stuff that has been dis/re-assembled (which is a very bad idea), severely inductance limited, etc.  I never had on anything near 400V 16.5A.
And the average guy is stuck with whatever they do.  Not practical to do any internal reconnecting.
G-

[wingman1776]

I know i am a bit late here but I recently rewired a 3/4 hp ecm motor. I ended up seperating all the coils. It is a task to say the least I have about 12 hrs in the rewire I did. I do think tho for 12 volts useing 3 coils per phase  then irp would be the way to go you would get power right with out tons of work. I did 2 coils pr phase then a star connection. I posted some pics in the thread I did here.

 http://fieldlines.com/board/index.php/topic,140989.0.html

hope it helps

[ghurd]

I ended up seperating all the coils. It is a task to say the least

After seeing the pic that looked like a multi colored porcupine exploded, I never thought that one would get put back together!
G-

[Ungrounded Lightning Rod]

ULR,

So the term "inductance limited" is the same phenomenon for generation and electrical (magnetic) braking?

I think so.  (Flux or others would know for sure.)

Depends on what you mean by "electrical (magnetic) braking".  There are a couple ways to do that.

If you're talking braking by running it as a generator and causing the generation to load the shaft, then absolutely.  With a fixed field strength the torque is directly proportional to the current.

If you're talking making a magnetic brake by something like sticking a squirrel-cage induction motor on the shaft and applying some DC to one or more of its coils, I'm pretty sure the answer is also "yes".  In that case you're inducing current in the "shorted turns" of the squirrelcage in the rotor and heating these turns to consume the mechanical energy.  Again the induced current fights the penetration of the field.  It's just the "generator" case turned inside-out.

Not sure how it works if you're running a conductive disk between the poles of an electromagnet, like a disk-brake.  I suspect if you spin it fast enough the disk might start excluding some of the field (like a superconductor only wimpier), forcing it to go around the edge of the disk.

Is it as if the "recovery time" is just too short or out of "synch" to work at higher frequencies?

Not a sync issue.  It's a continuous analog function.  The higher the RPM, the less the field penetrates on each reversal, and the lower the braking torque.  Braking HP is proportional to torque x RPM, so the HP keeps going up somewhat, but flattens out toward being almost constant.  (I think the asymptote is a constant maximum HP but I'm not sure.)

[bcalmed]

Just so I understand, the "braking force" that shorting the leads creates is just the same as the load of charging or whatever only into a dead short it maximises the "loading"?

I'm also intrigued by the apparent fact that the field propagates at some relatively slow speed into iron cores - relative, that is, to its propagation in air (or vacuum, etc.). What determines that reduced speed?

While I'm at it. can I split the 6 coils  of one phase on this ECM 4/2 series or do I need to individually rectify the 4's and the 2's?

I'm still working on it - but slowly.

bcalmed

[Ungrounded Lightning Rod]

Just so I understand, the "braking force" that shorting the leads creates is just the same as the load of charging or whatever only into a dead short it maximises the "loading"?

Yep.

I'm also intrigued by the apparent fact that the field propagates at some relatively slow speed into iron cores - relative, that is, to its propagation in air (or vacuum, etc.). What determines that reduced speed?

The current induced in the conductors - the output coil and any eddy currents.

 - The CHANGE of the incoming field induces a voltage.
 - The voltage drives a current.
 - The current produces an opposing magnetic field that cancels some of the incoming field on the inside and adds to it on the outside - amounting to "keeping some of the field outside".  (The field would otherwise would be propagating inward at the speed of light in the medium.)

In a superconductor the current can become arbitrarily large and never decays once started.  So the mag field never penetrates more than the skin and stops moving inward when the current it induced in the skin of the conductor produces an opposing field that matches its strength.  Because the induced voltage only accelerated the current, which can continue indefinitely with no voltage, it just sits there and spins, essentially 'excluding' the mag field from the superconductor.

With real conductors the current is constantly fighting resistance and load.  The load would cause the current to decay - reducing the cancellation - which can be viewed as more field penetrating - which can be viewed as inducing more voltage to hold the current up.  The balancing act continues with the field "slowly" propagating inward until it has all penetrated, the induced voltage goes away, and the current stops - or until the geometry changes and the magnets stop "pushing" the field in and start "pulling" it out - which induces voltage in the other direction, causing the field to be slowly pulled out through the "sticky" conductor.

I'm not sure I explained that well, or quite correctly.  But that's how I understand it.

[ghurd]

While I'm at it. can I split the 6 coils  of one phase on this ECM 4/2 series or do I need to individually rectify the 4's and the 2's?

Can split a phase into 4 and 2, but they (4 and 2) will each require their own bridge.
Without each having their own bridge, it will act as a short, though not quite as severe.  And the 2 will be a drain on power from the 4.
G-