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DaveP68
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Posted: 18 August 2017 at 6:15am | IP Logged Quote DaveP68

Have just tested a 36 pole copper stator with power factor correction capacitors wired 12x 1p Delta @ 600 RPM and got 1.5 kW output. The voltage was 57.1 VDC at 26.3 Amps. This was done on a lathe.

This is a far greater output than I have ever achieved with a capacitor doubler.

I'm no longer going to do any testing with capacitor doublers as they aren't as efficient in terms of power transfer.

I think the gain in efficiency is greater than 10 %.


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oztules
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Posted: 19 August 2017 at 12:42am | IP Logged Quote oztules

I think Herb in New Zealand did some work with this way back, and did strobe tests as well. From memory he noticed that the timing of the max peaks were shifted in space relative to the pole positions. This was apparently due to the MMF field positions changing some what.

I never understood exactly why, or how, but this change was responsible for the increased EMF.

I am guessing this MMF change modifies the way the MMF of the rotor reacted against the back MMF of the stator.... and somehow changed the relationship of the two fields, and where they cancel each other out to get the current limiting.

Given that the synchronous reactions are now different, I can only assume we are using the phase shift attributable to the caps, to change the timing and relative reactive forces to our benefit.

I wish I knew more about it, but your results speak for themselves in the real world... even if I can't understand the why or how.

Your results are now making me more amenable to driving these units as a small back up genny arrangement, as the natural current limiting is useful in many ways.

.......oztules

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gpalterpower
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Posted: 19 August 2017 at 11:44am | IP Logged Quote gpalterpower

Hi Dave,

Awesome work there, and all that from just one stator! You keep on sucking more and more power out of them!! Absolutely amazing! Do they perform just as well at a lower(say 100 to 300) RPM? Ive seen your pics of the blue PF correction caps in a recent thread and they look fairly small in size. Like to try one out on my mill. Are these an ebay item Dave?
Marcus

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Warpspeed
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Posted: 19 August 2017 at 1:29pm | IP Logged Quote Warpspeed

This could be some kind of resonance effect that peaks strongly at one particular rpm, but may also be disadvantageous at other rpm.





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DaveP68
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Posted: 19 August 2017 at 9:54pm | IP Logged Quote DaveP68

There are a number of things going on in this set up and yes resonance is one. But in this case it works to your advantage, as wind is cube law. So low down the capacitors have very little effect if not no effect at cut in. No problem for high input voltage range inverters.

This arrangement probably wont suit going direct into batteries. I had to do it at low voltage high current as didn't have very high voltage AC caps. The caps I used were 560 uf 250 DC back to back, so 280 uf AC which I had on had.

If the stator was a Delta 1x 12p the DC output voltage would have been around 700 VDC way beyond rectifiers and capacitors. So the only capacitors I had on hand suited the 12x 1p configuration.

I'm wanting to confirm the setup for Fred's new 40 - 540 VDC grid tie inverter. This will use a Delta 1x 12p stator. The Voltage for his setup will be limited to 400 - 450 peak. With the results from this test, I now know what AC capacitor to use on his system.
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flc1
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Posted: 19 August 2017 at 11:28pm | IP Logged Quote flc1

A 2.5 - 3 kw dual fnp windturbine is now possible, thanks Dave.
awsom work.

Edited by flc1 on 19 August 2017 at 11:29pm
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gpalterpower
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Posted: 20 August 2017 at 2:17am | IP Logged Quote gpalterpower

Well, I dare say that it's probably not going to work on my 24v setup. Just the same it's all very interesting and amazed how much power can be produced from one f n p. Your efforts into this subject Dave are greatly appreciated. Marcus

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flc1
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Posted: 20 August 2017 at 2:40am | IP Logged Quote flc1

yea Marcus, Daves test setup looks like it would suit a 36 or 48 volt battery system,with a mppt controller ,or a 22-60 volt input gridtie inverter.
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DaveP68
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Posted: 20 August 2017 at 4:52am | IP Logged Quote DaveP68

Hi Marcus

A 24 VDC system might work with a Dual 36 pole copper staggered stator setup.

The first stator (cut in) would be a 1x 6p Delta with 27-28 Volts at 80 RPM. Then the other half of this first stator is wired as 2x 3p Delta with cut in around 160 RPM. No power factor correction capacitors are required on this stator.

The main drive stator is set up as a 12x 1p Delta with the power factor correction capacitor sized at about 300 uf AC in Delta mode as explained in my other topic.

The total current could be as high as 45 Amps, so run some fat cables!

Peak power of 1200+ W could be reached at 500 RPM or even before that.

Think it's worth a try.

Fred is correct in that the best output comes at 36 or 48 VDC battery systems or even better results can be achieved using 22-60 volt input grid tie inverter.

David
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flc1
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Posted: 20 August 2017 at 8:30am | IP Logged Quote flc1

A single 36pole fnp stator wind turbine with a 40-540 v input inverter and 3 of Phills blades at say 2.5 meters,about 1.5 kw peak output and would startup with a sparrows fart on a blade,lol
would be simple to build for sombody, and have awsom watt hour performance.

Edited by flc1 on 20 August 2017 at 8:33am
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gpalterpower
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Posted: 21 August 2017 at 12:09pm | IP Logged Quote gpalterpower

Well over the past few months I have managed to get my hands on some 36 pole copper stators. Best place I found to pick these up were at the tip, scrounging thru the white goods section. I definitely got some funny looks! As yet I only have one black rotor, but I'm always on the lookout for the second. Probably heaps in NZ! Once I have all the required bits Ill refit and reconfigure them to the mill. Ill definitely give it a go. Ill need to fit another rectifier and PF correction caps. Its gonna get tight in there for room. So where do I pick up the PFC caps from as mentioned in your other thread? They don't look that big!

Just one question that my feeble brain is trying to understand.... What is the difference between a cap doubler setup and PF Correction caps? Is it the way they are configured?



Marcus

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DaveP68
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Posted: 22 August 2017 at 10:07pm | IP Logged Quote DaveP68

Hi Marcus

Yep once you get that other black rotor cap max power extraction can be achieved.

Power factor correction capacitor at a "guess" at this stage should be 6x 680 uf 250 VDC wired back to back as pairs then in AC delta configuration.

RS components 680 uf 250 VDC capacitors.

Haven't done a test yet for 24 VDC system so not sure of results.

Cheers

David
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