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flc1 Senior Member Joined: 20/11/2011 Location: New ZealandPosts: 242
Posted: 09:02pm 23 Aug 2017
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yep ,may do later,just a test setup at the moment. the max current that will run in the system will be about 3 amps, so should be able to get away with what we are using now, for that system.
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 11:20pm 01 Sep 2017
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Hi Tony,
Ive checked out both sorts of start/run caps on ebay as you have suggeseted above. So many to choose from there. I would like to try some and see if I can get a little more power out of the mill, but not sure of the value I need. Could you suggest a cap rating to try on my 24v dual system. They are easy to mount and I can easily find a spot to fit them. I'm assuming I will need 6 per stator if wired 2x6c. Marcus
if it aint broke dont fix it!!
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 11:32pm 01 Sep 2017
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I have no idea what value may be required.
Suggest you do some testing with whatever cheap electrolytic capacitors you have or can readily get.
Once it looks like the idea works, then you should have some idea of what values you need. Cheers, Tony.
DaveP68 Senior Member Joined: 25/11/2014 Location: New ZealandPosts: 292
Posted: 03:16pm 02 Sep 2017
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Marcus
As already stated before, the main drive stator must wired 12x 1c Delta due to your 24 VDC system. Any deviation from this setup wont provide enough current.
Choose whatever capacitor type you like, which Tony has provided lots to choose from.
Also already suggested you can try a value of about 340 uF AC and do a test run to prove that value is the correct one to use. They do work over quite a wide RPM range when they kick in so that guess should be close to the mark.
All my testing has been above 50 VDC, so hope it works first time around.
David
There are realities if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow! The Dunning Kruger Effect :)
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 10:54pm 02 Sep 2017
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Thanks guys, I just needed some sort of uF value to begin with. As luck has it, I was going thru some old boxes today and came across 6 caps with a rating of 450v /470uF. Think the'll do the trick so Im gonna give them a go and see if there is any increase in output, but there's just one thing that puzzles me.
I noticed in the "Electronic projects and info" section, where "Gordons Cap Mod" schematic is wired exactly the same as the one in the thread . Just curious why, there was only a small improvement in output then , but Dave who is doing great work on this subject, is extracting unprecedented power output. Is it because of the uF rating or the type of caps used? Id appreciate any thoughts on this.
Marcusif it aint broke dont fix it!!
DaveP68 Senior Member Joined: 25/11/2014 Location: New ZealandPosts: 292
Posted: 12:44am 03 Sep 2017
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Hi Marcus
Yes that is where I copied that circuit from. But it's not a Capacitor Multiplier, it's in fact exactly how I connect the capacitors to the stator for power factor correction.
DC 470 uF caps connected as series pairs will make 235 uF AC capacitors and will be close enough in value to make a big difference. Remember your main drive stator must be wired 12x 1c Delta to get any good results (lots of current) at 24 VDC.
Have no in depth knowledge of what was done 8-9 years ago with the capacitor doubler testing etc.
The one thing I do understand is the capacitor doubler does have a wider operating RPM range, but this feature in my opinion is a miss guided view point.
As most on here will already know wind is cubed law, so as the wind speed doubles the power extracted is 8 times greater. This works to your advantage with power factor correction as when it approaches it's peak output the power output climbs very steeply.
More results to follow as I haven't got the maximum output from power factor correction capacitors yet.
DavidThere are realities if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow! The Dunning Kruger Effect :)
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 09:09am 03 Sep 2017
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I suppose it depends on what you are trying to achieve.
While I can see that its possible to extract much more power at higher rpm by tuning with (resonant) power factor correction, that is not going to help much with cut in at very low wind speeds.
If you truly live in a location where there are strong constant steady winds, higher power output has to be a good thing. But that is only going to occur where there is more shaft torque available than the alternator can use. So loading it up more electrically can produce more electrical power, but only if there is excess shaft power available to do it with.
At the other end of the scale, where winds are marginal to non existent much of the time, a greatly lowered cut in speed will probably gain you far more than tuning it for higher power output during high winds.
So very much depends on the blade/alternator combination you have, and the prevailing wind pattern.
I can see that a capacitor voltage multiplier would be just the thing for reduced cut in speed in light or variable winds.
For a coastal location with strong steady prevailing high wind, if the system is overpowered with wind, then this power factor correction scheme might offer a very worthwhile improvement.Cheers, Tony.
DaveP68 Senior Member Joined: 25/11/2014 Location: New ZealandPosts: 292
Posted: 10:39am 03 Sep 2017
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Tony you overlooked what is on the first page of this topic.
If you also read up on my "Cap Doublers vs Power Factor Correction" topic it states there's a 33 % power loss when using a Cap Doubler vs a standard stator or with PFC caps.
The one big advantage of the F&P stator is they can be rewired into many different modes of operation star/delta, staggered setup etc to suit different battery voltages system etc.
Taking all this into consideration the Power Factor Correction will work as I've described in what ever wind conditions. They only cut in to give the extra power at a higher RPM where there is going to be the sufficient shaft torque available.
I just don't see a problem with trying it out on a wind turbine to prove the operation of Power Factor Correction.
Hope it works out for Marcus.
The Single stator operation with Power Factor Correction can only be done with the wide voltage operating MPPT inverter (40 - 540 VDC) that Fred is about to install on his new Wind Turbine.
DavidThere are realities if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow! The Dunning Kruger Effect :)
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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