VAWT Direct Drive PMA: At what diameter can we expect worthwhile results.

[brandnewb]

I am going to pretend as if nothing happened before yes?

I am still not sure, but the more and more I think about it based on my limited ability to gather scientific data, I think we can work out what frequency of field reversal is needed and at what velocity the magnets are when doing making so for that frequency.

Now you all know me and that means I can not and therefore will not be able to do the hard math.

But let's take it first from my perspective:
I care about the frequency of field reversal in order to get to good amps. The higher the better the amps.
Yet not all systems, like a drag type VAWT, rotate fast.
Ok so then we have 2 parameters left is not mistaken.

Density of magnets and radius of those yes?

Density of magnets directly influences the frequency and the radius does the velocity.

All I ask is for the most insightful minds here to just give it a go. Think with me please.

I already know we will end up with something soo unpractical that one will never build it.

But that does not mean it is impossible.

And we also know that what ever I think I know might be totally wrong.

[JW]

But that does not mean it is impossible.

And we also know that what ever I think I know might be totally wrong.

Its reasonable questionable quoting

the largest diameter possible stator perhaps 4ft dia... you will encounter your going to need overlapping of your coils. 


JW   

[brandnewb]

who is

Bannewbe

?

Look I understand that you have been misinformed by your IT department, when I was suggested to register here, that I might be nonlegit.
That was because I use a certain email format that is, although not common, totally legit.

And ever since I am marked as a potential bot or something.

really? do we need an, although fully respected, inexperienced IT department to basically ruin my reputation from the get go?

Anyway JW, If you will allow for it then I would like to try again here.

But do know that I tread everyone with respect and expect the same yes?

Come on brother. I have something to share with you grill wise. It is smoking hot and will taste even better

[JW]

Look you are still able to post without any restrictions  bla bla pla

Flavio Must still have the keys to the server.

[brandnewb]

Thank you JW,

For that you will allow for questions to be asked and answered.

The hallmark of what fora operate like.

Nevertheless. I will be state side sooner or later and I will be expecting a good grill.

Wait what???

Did I expect a good grill??


NAHHHHH I expect the BEST grill

Would you be open to that?

[JW]

NAHHHHH I expect the BEST grill

you must work for that. now cut it out and have thick skin. Stay on topic in a technical way to your aim.

[brandnewb]

understood sir.
please remove this conversation from this totally legit thread then yes?

yet leave of course that original parts yes?

[JW]

Im not paying that much attention. trying to drink some coffee

[joestue]

to answer OP's questions..

it depends on your construction ability.

small magnets and lots of them at a larger radius is more efficient than larger magnets at a smaller radius.

however, smaller magnets cost more than larger for a given volume of magnets. machine output is approximately proportional to the volume of neodymium magnets, multiplied by the radius of the machine.

(assuming the relative ratios of the machine stay the same. so the pole count goes up, the magnets get smaller, air gap gets smaller, coils get smaller but more of them, copper volume and magnet volume stay the same)

smaller magnets need a smaller air gap to be efficient, at the larger radius the tolerances and deflection are greater/more difficult to deal with.


smaller magnets at a larger radius are less efficient than larger magnets at a smaller radius... because the copper path length for a given magnetic surface area is longer.. however the force on the magnet by the copper remains the same per unit volume of magnet.. so larger radius is better.

[brandnewb]

Thank you Joe for you to chip in.

Please allow me to hold up to scrutiny my view for you to be able to see if this aligns with or counters your view.

This is purely hypothetical and we need the likes of magnetjuice and my nation's master to poke holes in that if there are.

Let me start with the ability of construction
Mine is rather poor when it comes to spinning disks/turbines. Let alone when we extend their radius. My lord I am still struggling with this "childish" alternator at 720mm diam.



Yet.



Just yet...



I think I have an opening that I would like to explore. For things to go far larger.
But before we do so in the real world we first need some kind of theoretical groundwork.

So what I will do is gather rather detailed data on my current PMA/Coil configuration and present it as a basis to work from yes?

All I really want is the ability to share my data is the hopes one can find a way to push through.

And like one knows already. Should I hit a wall then I will of course state so.

But to not let this thead rest idle just already I have a thing to consider.

So I am at about 60VAC(r) at about 30 Hz.
My best until now before I blew out my circuit braker, is 225 watts against a 16S Lifep04 battery bank. Going in Dry mind you. We do not do safe s*x when needing to learn when to create results.

BTW does anyone also think that testing a PMA dry against a bank is not totally ideal? In that case please suggest a better alternative. I have had some earlier but they seemed not doable to me because perhaps I just did not understand it all that well.

 

 

[brandnewb]

Once again Joe, Thank you for contributing to this thread.

@Adraiaan
"Adraiaan Krachten"

If you can not help then no one ever can yes?

This is the reputation I have of you. I mean come on. I am even going so low that it is because I am also a low lander.

We need to move forward though.

Not only because I think I have something to share.

But this moment in time could serve as a test point. To see how far my theories can be supported or of course be invalidated.

I guess you know already the configuration om my current PMA/coil.

This is not a guess but a strong believe that you already know.

Please use your experience to either throw out the solution or ask me additional questions to which answers will enable you to get there.


I mean come on...

[joestue]

you speak like someone on drugs.

build your VAWT and use a friction brake to measure how much power you can get. then build the alternator to match that power.

[brandnewb]

9.1 KG force needed to stop the turbine from spinning.

and that was at around 4 meter radius.

that is quite the torque we have here.

but I still am drugged out waiting for how to proceed with this gravity test. wait what?

So never mind here then people. I will figure things out my self then.

 

[joestue]

9.1 KG force needed to stop the turbine from spinning.

and that was at around 4 meter radius.

you didn't give velocity/rpm, or windspeed during that test.

if that's the static holding torque (36 kg-m), then your average torque at slow speeds is probably less than half of that, due to drag, and the fact that you don't get peak torque at all times.

but that is plenty of torque for a traditional geared up motor conversion. so grab yourself a tread mill and make about a 10:1 pulley system and see if it can turn it.