Turning PMA into a Motor

[DavidPV]

Hi,

I have recently bought a PMA for a DIY Wind Turbine, I would like to be able to use this PMA as motor to spin up the turbine rotor (for posing on calm days) when required.

Links to the motor:

Ebay Link

http://www.fieldlines.com/story/2008/2/20/51825/5242

I know it can be done with a PM Brushless Stepper motor controller, but any idea where I can find such a suitable low-cost controller, through which I can turn the PMA as a motor;

1. -at the required speed/rpm
   
2. -at the required amps or power consumed. Meaning I don't want it to consume a lot of hard earned battery power when turbing as a motor just for pose.
   
   

Also, it should not be an AC input type controller, but rather operate from the battery voltage 40-60V for a 48V system.

I would like to turn it on as MOTOR through a dip switch or a push button for a predefined time period, and then return it to the original generator phase, but thats the sedon stage. First stage it to find a suitable controller.

I hope the idea is clear, any input is welcomed.

Dave.

[vawtman]

Are you from Hollywood buy chance?

[TomW]

vawtman;

I kinda wondered.

People should give full disclosure.

In my experience any photos of my turbine, regardless of RPM freezes the action so it looks stopped anyway.

There is no sensible reason to drive it as a motor that I can see.

Go figure.

TomW

[vawtman]

It could be a Man thing, Tom

 Thats all i can think it would be for.Thus Hollywood where men arent real.

 I got a get to bed and and get over this crap so i can get back to work.I don't know how you deal with this all day.

 I had fun and much better than watching soaps.

[JohnC]

Don't laugh, it could be do-able.

I've seen some all north pole rotors pulsed, thus using very, very little current. I have already started to build one,the pulse circuit is already made.  so during low wind, together you could reach chargeing voltage for your battery.

[electronbaby]

thats ridiculous.

[TomW]

Roy;

I had to sit on my hands to not respond the same way you did.

Its pretty funny the stuff people convince themselves of.

Perhaps he missed the "No Overunity" rule?

TomW

[oztules]

 Well Tomw,

It is very simple to make a very crude driver for the axial flux PMA mills. It requires three fets, three halleffect devices a couple of resistors, a current limit resistor and thats it.

I know this because I just finished building the axial mill alternator, and had nothing to hook it up to to get a feel of the torque required at different impedances. I happened to have a 3kw 415v 3phase motor on the desk next to it.... so hooked it up to see.

Sure enough, it turned the three phase induction motor at three times the speed of the mill...... so I had to see if the axial could be driven like a motor.

Stripped a PSU fan apart, noted the hall effect device, the trannies to switch the coils and decided to whack up a quick circuit ... just too see.

Sure enough, the axial flux runs as a clunky (half wave driver) motor of very good torque......

So it is possible to overcome the problems of cogging motor conversions (eg F&P mills) with a very simple start up circuit... 2 or three seconds would probably be enough to overcome start up cog in light winds.

It would seem to have no place on the axial flux type because start up cogging is not an issue.

The next illogical step is to build a proper driver (just bought some MC33033 brushless driver chips to simplify this process) and see if a high torque low rpm traction motor is a doable thing. It may be then time for iron powder impregnated coil centers perhaps.

Curiosity dictates that I find out the hard way and have some fun to boot.

........oztules

[Flux]

Why all the surprise?  It's a wind generator isn't it?

Yes as Oz said it is possible, you may even be able to do it open loop without the hall sensors if you ramp the frequency up from zero. Just needs someone brighter than me to sort out the step sequence.

Put another one up nearby to use the wind and work out the overall system efficiency.

Flux

[TomW]

I think you guys should carefully read #4 in this thread. That is the claim I am disputing.

I used to "kick start" my GarboGen with a quick shot of DC to break it loose of the cogging because it would produce power in speeds that would not start it but that is not what the poster in #4 said or implied. The implication there was that he could drive the mill into "cutin" speed with little or no power using pulses.

Maybe its me but these damned vague fishing questions lead to this stuff.

You would think we were Keelynet some days from the BS that flows thru this place. The monopole can work. Something for nothing can not.

Plus, what moronic reasoning would you have [hollywood excluded] to motor your turbine? Really?

I should have killed it before it saw the light of day.

OK back to my cave.

TomW

[Norm]

Put a recoil starter on it...With an

Extended rope pull.....a cheap camera

with a real slow shutter speed like they had

back in the '80s

[Flux]

Yes Tom the whole thing is a bit crazy but the original poster was honest in his intentions. If he wants to consume battery power and generate wind then that is fine by me.

Some of the other implications are more difficult to accept and are best ignored.

There may be others who want to use these alternators as motors, it can be done and done efficiently. If he really wants a turbine for posing then it would have been easier to start with a dc motor rather than develop a brushless synchronous one.

Flux

[TomW]

Flux;

Excellent point.

Another idea I had [from DanB] a commutator setup driving the motor. Nah that would need the commutator on the genny shaft. I think DanB suggested this as a way to use the PMA as a starter motor on a Lister or ??

The DC commutator motor would work "out of the box" to do just this.

TomW

[Countryboy]

Just get an Ametek DC motor.  Bypass the line diode whenever you want to make it spin the blades for appearance purposes.