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DaveP68
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Posted: 01 January 2017 at 1:01am | IP Logged Quote DaveP68

Hi All

After months of testing, I've got data to prove that a 36 pole copper stator with black rotor cap has a 40% higher (linear) power output compared to a 42 pole over same RPM range. These tests were done with both stators wired uncut Delta mode.

Here is a graph and complete set of data tables (RPM, Power, Volts & Current.










The photo above is of a 42 pole stator set up as for the first test run. We ended up using both the 36 and 42 in Delta as voltage on star got over 500 VDC under load and our rectifier + capacitors are only rated up to 500 V. Max RPM reached was 1155 RPM with peak power output of 1290 W on 36 pole with black rotor cap. Only got access to this Lathe last month hence why I've been able to complete far more testing and publish a complete set of data, including the "F&P stator cut in Volts vs RPM tables".

Yes the test voltages at high power are high and for practical use the stators would need to be cut into different configurations (i.e. 6x2C or 7x2C). Like I've described in my tables of "F&P stator cut in Volts vs RPM tables".

I have seen comments on this site stating the best stators are the 80s and 100s depending how they are used.

I would be very interested in seeing how a 42 pole stator can be configured to match this 36 pole stators (with black rotor cap) data or better it. I'm not referring to the modified 7 phase wired to use a black rotor cap as the wiring is quite complex pull off and once done is hard to reconfigure.

David

Edited by DaveP68 on 01 January 2017 at 10:37pm



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DaveP68
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Posted: 06 January 2017 at 11:38pm | IP Logged Quote DaveP68

An update on this 36 pole vs 42 pole stator testing for those that may be interested.

Added a "Capacitor multiplier" as per Gordon's design and got a some good improvements in the low to medium RPM range up to 400 RPM both 36 & 42 pole stators. Yes this is where better performance is needed anyway.

But even using a "Capacitor multiplier" on a few different 42 pole stators I couldn't get as much power out as a 36 pole copper with Black Cap. By far the 36 pole copper "Factory Decogged" with a Black rotor produces more power output overall.

Let's say you put a "Capacitor multiplier" on a 42 pole and state it will out perform a 36 without the "Capacitor multiplier". That isn't a fare comparison as one just needs to add a "Capacitor multiplier" to the 36 pole and it will just put even more power than 42 pole. The laws of Physics are what are...
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Downwind
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Posted: 07 January 2017 at 2:44pm | IP Logged Quote Downwind

I find your testing interesting but a little useless.
For 1) who would want a mill running at over 1100 RPM, we normally run and hide way before that RPM.
2) producing high voltage like 500V is just pure dangerous and stupid for a home grown mill, even more so when many first mill builders have little idea of lethal voltages these stators can produce when not modified.
3) Mechanical testing (like a lathe) it almost useless when compared to real wind driven tests.
Im still not sure what you are trying to prove with your tests, as it has all been done before and well posted on this forum.(other than the black rotor)
Good to see you reinventing the wheel, but if you dig deep enough into the forums past you will find almost the same results that have all been posted before.
Its nice to have a fresh mind working on development, just be careful to what you claim as your developments as there is a long and old history of simular test results.

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oztules
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Posted: 07 January 2017 at 7:52pm | IP Logged Quote oztules

Dave, thanks for the very useful table you have spent time to produce. It gives me a good idea of how the stator can be used.

I have a few here now, and have not had the time to get an idea of their dynamic range.
I do appreciate the high rpm, and natural voltage figures, as I would not use these in the mode that folks here do. I would run them natively.

The best home use windmill I have ever had the pleasure of being associated with does not cut in until 200vac, and thats the African Wind Power, designed by Hugh Piggot. It is high voltage, and generally produces 24kwh per day average. It has survived a decade of the worst winds that the roaring forties have produced, in a marine environment, with forcing voltages well in excess of 500vac. I don't believe that all neophytes are incompetent idiots.

I also commend the bench test. For those still interested in carving their own blades to get the best performance, we need to have the power curves so that a decent TSR and diameter can be arrived at. It is not possible without this information to make an informed decision. For those using the chinese blades, then less reason to bother perhaps.

The high rpm figures are very practical if you use the Chris Olsen style mill head, but more importantly, they also give us an indication of the synchronous impedance and by looking at the graph we can see that the normal limitation faced by F&P builders which is imposed by not letting the voltage rise, is eliminated, as the inductive reactance is not prominent in these graphs. If we were to use the Olsen head and a normal GTI, it would be a perfect combination to drive back into a LF inverter, and well over 1kw would be easliy achievable for a single stator.... interesting idea.

The leakage in these stators appears to be quite high, and this normally makes braking difficult, but if we can keep the line impedance high to match the stator, normal braking should be very possible, as the leakage impedance will not current limit and let the mill over speed.


So thanks for your work in this area, I may still get an F&P up in the air.... and it will be high voltage.... probably grid tied to my inverter for battery charging if the house does not use enough of the power directly. The HV will also allow the mill to be hundreds of yards away from the house.


............oztules

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flc1
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Posted: 07 January 2017 at 10:00pm | IP Logged Quote flc1

Well said Oztules, the mppt inverters that I have said are availble online can allso work in voltags from 30-500 v dc and ac, well suited to a fnp.And the fnp appears to run very quiet when useing higher voltages.Downwind,My geared up mill runs up to a 1000 rpm on one of the stators,so its very useful data,
Fred

Edited by flc1 on 07 January 2017 at 10:18pm
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DaveP68
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Posted: 07 January 2017 at 11:10pm | IP Logged Quote DaveP68

Downwind wrote:
I find your testing interesting but a little useless.


So you find my testing interesting but a little useless, what a contradiction of terms...

Downwind wrote:

2) producing high voltage like 500V is just pure dangerous and stupid for a home grown mill, even more so when many first mill builders have little idea of lethal voltages these stators can produce when not modified.


If you carefully read what is in the post I state "Yes the test voltages at high power are high and for practical use the stators would need to be cut into different configurations (i.e. 6x2C or 7x2C). Like I've described in my tables of "F&P stator cut in Volts vs RPM tables".

So that has been covered off too.

Downwind wrote:

Im still not sure what you are trying to prove with your tests, as it has all been done before and well posted on this forum.(other than the black rotor)
Good to see you reinventing the wheel, but if you dig deep enough into the forums past you will find almost the same results that have all been posted before.


I haven't found ANY comprehensive test results for 42 or 36 pole ststors on this site, well not in the way I've formatted it anyway.

So you don't want an improvement of 40% output for the "exact same" RPM?

That is exactly what the Black Rotor cap does when configured correctly, which is the WHOLE point of me publishing this data.

As for reinventing the wheel you must live in a world that all wheel are created equal!! That isn't the case in my world. Lets take the wheel used on a train it doesn't work on our roads at all (it's a wheel)... Take a wheel on a Boeing 777 and go and try fit that to a large Truck, won't work very well when swapped over. Aircraft tyres are designed for high rotation speeds of 300 kph+ for take off/landing, a large truck is lucky to do a 3rd of that speed under normal operating conditions. Having both worked in Rail and Aviation I understand these very important differences between "wheels".

So a 36 pole copper stator with black rotor cap will out perform any 42 pole stator... One wheel can be better than another wheel

Downwind wrote:

Its nice to have a fresh mind working on development, just be careful to what you claim as your developments as there is a long and old history of simular test results.


Thanks for the compliment re fresh mind working on this stuff. I have NEVER stated the words "developments or developed" relating directly to Stators. Did say I was developing a form of Buck MPPT converter and FET switching unit which haven't been completed yet.

I'm also on record endorsing ALL the great work that has been done on this site to date by many others including you.

Edited by DaveP68 on 07 January 2017 at 11:15pm
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oztules
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Posted: 07 January 2017 at 11:33pm | IP Logged Quote oztules

Fred,
It would be very interesting to see a native stator driving say an aerosharp 3kw GTI.

It may need a clamp over 500v, and would need a brake circuit as if the battery is full, and the house does not need much power, then the voltage will rise and the GTI will drop off, we then simply brake it with a matched load. It would be very efficient using this instead of the normal battery charging regime, which is terrible in the form of efficiency.

We should be able to get around the crest factor distortion, as the pfc front end in the mppt should allow using the whole wave, not just the crests.

So this may be the only real way of using the F&P to it's full potential, and with GTIs so cheap, and the highly efficient synchronous rectification the LF inverters allow, you could squeeze most of the figures Dave published .... into the batteries, which would not be possible any other way as I see it.

Cheap high power low frequency inverters, and cheap almost disposable GTI's make things possible that we never dreamed were possible only a short time ago... I mean who would have though to use a native HV F&P stator, and expect to spank any figures, any other traditional system used. It finally allows full potential of the F&P stator, at any battery voltage ... without any modification at all.

I guess Dave has reinvented the wheel


..........oztules

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flc1
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Posted: 08 January 2017 at 12:27am | IP Logged Quote flc1

thats the one Oztules, Daves tables need to be added to the fnp contents page,
to save them from dissapearing in the forums again like the older testing results.

I would never have broke the 1kw mark with my turbine if I had not used a higher voltage mppt inverter and then added( daves idea) black rotor caps.
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DaveP68
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Posted: 08 January 2017 at 12:38am | IP Logged Quote DaveP68

Hi Oztules

Thanks very much for endorsing the hard work I've done with testing F&P stators mostly for the purpose of publishing data tables/graphs.

Thanks also Fred for acknowledging that it was my data about the 36 pole copper stators with black rotor caps that allowed you pass the "Mythical" 1 kW limit

You so far are one the few that has seen the "untapped" potential of these F&P stators, especially the 36 pole copper "Factory Decogged" with a Black rotor cap. To the non believers, how you could over look the simple fact that they give out 40% more power output for the same RPM than a 42 pole stator...

Thanks also for putting me onto the Aerosharp 3kw GTI, just checked out it's specifications on a Google search.

Here is a post on and responses re a 50 to 500V MPPT the product is "Tristan MPPT 600V" (can use for PV up to 600V & wind + hydro to 500 V)
500V MPPT wind charge controller do exist

As for controlling the voltage in a for breaking purposes above say 500V as you have pointed out, is easily done with a dynamic brake circuit.

Check out the circuit board in light blue plastic casing in the photo below.



I'm only using one small part of the overall circuitry of a F&P motor controller board. It just so happens to have a dynamic brake circuit that normally cuts in at 400 VDC. It's can easily be modified with higher rated components to operate well in excess of 1 KW into a "LARGE" resistor at 500 VDC cut in or what ever voltage around that.

So in summery like you say, all the hardware is out there "at a cost of course" to home build a will turbine using F&P stators and get the full output power potential.

Edited by DaveP68 on 08 January 2017 at 12:42am
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oztules
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Posted: 08 January 2017 at 1:15am | IP Logged Quote oztules

Yes they are quite versatile if you give them a chance..

Eg.. here I used it to drive 1k5 hp mono pump...used the original motor as a bearing block

It runs on solar panels the same as a normal solar pump would.



So am familiar with driving them ( I used a moc33033 chip, not the F@P, as it was for a 48v unit.)

I think breaking would be very simple, and not require the "breaking" circuit, as if we match the synchronous impedance, we will probably get as good as we need. It will not run away like a short circuit would do, but act as a dynamic brake... slow but not stopped I suspect.

The inductive reactance is what would normally do that runaway bit with a dead short. People would have noticed it is probably best not to direct short it, but to put a big resistor across it instead, and that slows it down until the TSR drops off, and stops it. It can also be seen as a eddy current reaction, so is inversely proportional to the rpm.

Well done.


............oztules



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DaveP68
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Posted: 08 January 2017 at 2:09am | IP Logged Quote DaveP68

Hi, great to see the F&P in yet another application other than washing clothes and generating power.

The way the dynamic brake circuit works, is when you get to the trip voltage (brake application) of say 500 volts it switches in a low resistance load (28 ohms on an F&P module). At this point the voltage will suddenly drop at a steep gradient to cut off threshold voltage of say 450 V and it lets go. This is all achieved via simple comparator circuit with a small amount of hysteresis. The switching element being a high power, high speed IGBT.

This operates as an independent circuit, but in parallel to a high voltage MPPT Inverter as you described earlier in this post. That way the dynamic braking is only taking away any excess energy that is over and above to what the Inverter can convert to charge batteries or feed back into the grid.

The cheap Chinese (non certified though) GTI wind turbine inverters have them built in. The resistors seem to be a bit under rated if you loose power in high wind conditions. This just an observation though, as they would have to take all the load if nothing is going back into the grid.

Edited by DaveP68 on 08 January 2017 at 2:10am
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gpalterpower
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Posted: 09 January 2017 at 11:34pm | IP Logged Quote gpalterpower

Hi Dave,
These are interesting stats. It really is amazing how much more power the black rotor with 36 pole stator creates. Bout a year ago I picked up a black rotor and stator. I didnt realise till I got home and inspected it a bit more closley that I ended up with the Ally wound coils. Not to be deterred, I reconfigured it to a 3x4c and fitted it to the mill. There was an immediate increase in power and kicked in at a lower rpm. So im wondering if there is a huge/marginal difference in the output of the copper compared to Ally windings. Im still on the lookout for another, but will be searching for the copper stator if the output is higher. Any graphs on these?


Marcus

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