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Forum Index : Windmills : visual effect of capacitors
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fillm Guru  Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Another person converted to cps/Vdbl , I hope more keep trying as the benifits are there . As you know Gordon I am using Caps to a voltage quaddroupler on the Ax Fx and getting more out where there was nothing . It would probably be good infomation to give the F&P wiring configuration in either star or delta with the cap size .. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Phill, It is possible to use any parallel combination of series caps/direct rectifier, and capacitor voltage doubler/tripler/quadrupler/pentupler to get as close to ideal loading. This is at the battery, so no changes needed to alternator, or transmission wiring. I would prefer readers to post their own findings. I was merely stating that I had heard of a 12V system now, however it was wired for 12V. The cap size still needs to be tailored to the particular mill. I do not have a F&P mill anymore, so my testing with one has ended. There are plenty who still do, so maybe they could provide some numbers from their own testing as well. 100-470uF is a good place to start. Gordon. become more energy aware |
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BUGS Newbie  Joined: 12/04/2007 Location: AustraliaPosts: 21 |
Gordon, I've just tested my 12v 300w (china)turbine with 6 x 220uf 450v caps back to back, no change with amp meter in line.  I'll try 100uf caps. I need to hook my logger up, and thanks for the update.
Ivan BUGS |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi BUGS, the 6 back to back caps would be for reducing the windmill loading with just series cap loading. Are you sure that this is what is required? Most benefits are with a capacitor voltage multiplier in adition to the normal rectifiers. This provides additional current at low rpm, when the windmill would normally not provide battery cutin voltage. Please check again. unless the mill is stalling, I would expect voltage multipliers would be needed. Gordon. become more energy aware |
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| BUGS Newbie Joined: 12/04/2007 Location: AustraliaPosts: 21 |
Gordon, Yes, running in parallel with normal rectifiers. Do I need 12 caps and bridges for 12 volts ?? Thanks Ivan P.S. what size caps would you suggest. ?? BUGS |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
You need a minimum of 12 caps in voltage doubler using back to back DC caps. You need 4 1phase bridge rectifiers as well, wired in my published layout[earlier post] for a voltage doubler. 220uF @ 100VDC caps would be a start on a 300W max windmill. Gordon. become more energy aware |
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| daveames Newbie Joined: 19/09/2009 Location: United StatesPosts: 30 |
They came of bold and roving stock that would not fixed abide;* Gentelmen, what a fascinating read this thread has been. over the past few days we have managed to get through this and Gordons other (the f&p) topic thread and scratch the surface of the links and references provided. along the way i ran into several things i thought we had a firm grasp on only to see i know "nought" about it. i love/hate when that happens! was hoping there might be room on the forum for a connecticut yankee. afraid i can't add to the topic at hand. but sure do enjoy the education/fun of playing around in the shack with some of these renewables. kind regards, dave. kb1mzf -from daves best(memories)of oz files: standing ankle deep in vb at the observer hotel, listening to girl overboard play "when the word came down"..rafters on the rocks! *clipped from banjo pattersons pioneers. |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Dave, there is a lot to go through. one day a concise version will appear as an article. As oztules stated a while back. I spent a long time working on an electronic MPPT. I have working analogue and digital versions, but the tracking is only reasonable at best. The loading matching available with combinations of my 3phase capacitor voltage multiplier ccts is close to ideal, with a cubic power relationship achievable. The natural properties of these parallel capacitor arrangements leads to stable simple wind power loading to a low impedance loading, like a battery. There are not too many constraints, but best ressults are obtained when the windmill alternator is wound for normal battery system voltage cutin at approx half the maximum expected operating rpm. This will give higher alternator efficiency with increased maximum output power. The capacitor ccts take care of the low rpm/power end, where no output would occcur. This is a win/win. Gordon. become more energy aware |
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| daveames Newbie Joined: 19/09/2009 Location: United StatesPosts: 30 |
Hi Gordon, i've been remiss in thanking you for the reply and the advice. i agree that a more concise version of the work you and others have tried to bring forward might make for an easier read but would be hard pressed to capture the evolution of the project.(just as intriguing as the subject) i have several of the "new style" 36 pole f&p's that i look forward to playing with. we will try to post how we get on. my data gathering abilities are limited and my understanding of all things electronic are elementary at best, but i can tell the difference between better and worse and can notice trends so that will be a start. all good fun. kind regards, dave |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Herb, I have a pic of the voltages I measured today. The meter on the left is the ACV across 2phases. The centre meter is the DC voltage across the lower bridge of the voltage doubler. The right meter is the voltage across the two bridges. 
WRT your comments. I treat the voltage doubler like 2 series cap coupled arrangements that are parallel across the windings but in series across the load. This to me is the easiest way to visualize. In the cct here 
What I have seen is that the caps connected to the top rectifiers develop a negative DC voltage when measured between the AC from the winding and the rectifier input, and the caps connected to the bottom rectifiers develop a positive DC voltage when measured between the AC from the winding and the rectifier input. The sum of the absolute value of the voltages equals half the output voltage. The voltages are not static, but change with loading and AC input voltage. As to what to call the diodes function????? I suppose normal rectifiers could be called steering diodes as well. To test the function of my cap voltage doubler arrangement would not require large expensive caps or bridge rectifiers. 3phase source may be a problem for some. I would not go back to a single phase test as the ripple makes it harder to measure without a CRO. Gordon. become more energy aware |
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KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
so Gordon, how does the series load work with 24V battery and a 48+V inverter like the PVE1200, ie like Phill's I cant understand this part of how it works per the schematic, would obviously save me some money in batteries. I bought a PL20 as the aim is to have as many similarities to Phills as possible as the learning has been done. I took his advise and have got (on their way from Japan) 24 x 680uf 450V caps. Initially I'll be running them on a single stator with half wired as star the other half as delta, rotor is probably a bit big at almost 2.6m. Batteries is a bridge i'm still yet to cross, if 24V will do then i'll save the $$. Luck favours the well prepared |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
I have noticed an error in the cap article. There should be a connection between both pairs of bridge rectifiers. That is the 2 + terminals of the bottom rectifiers shoud be connected together, and the 2 - ve terminals of the top set of rectifiers should be connected together, and these sets are then connected together. This means 4 connections in the centre between the rectifiers. My original picture in the forum thread a way up now was correct. I expect Gizmo will be able to easily fix the pic in the article. There have not been any Queries, so I suspect no one noticed a difference either. I hope all readers have the correct wiring, as in my pic above. Gordon. become more energy aware |
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herbnz Senior Member Joined: 18/02/2007 Location: New ZealandPosts: 258 |
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SparWeb Senior Member Joined: 17/04/2008 Location: CanadaPosts: 196 |
Hi again Gordon. I'm always following progress, and again I have a mill worth trying this on. Maybe I will add some experience with industrial motor conversions, where so far most success has been with the F&P's. I do want to understand the diagram as well as possible, first, and the reduction in resolution makes it hard to read the image. I also cannot tell if Gizmo has updated your diagram image or not, so the starting point may be a bit out of date. What I can see leaves me with a question. I've "tweaked" the drawing to show what I mean: 
Do you have to use 12v batteries? It looks like a continuous string of cells for 24v should be connected, like I've shown in my edited version. I'm not very familiar with circuit drawing conventions so maybe you're not supposed to draw things this way, or maybe you've used a short-hand notation and it's obvious to everyone but me. I also use a 3-phase bridge in my system, not the little square bricks, and it looks like it won't matter as long as I use the 4 brick rectifiers as you've shown in the parallel Cap circuits. If I'm right so far, I'll draw up my own circuit diagram and post it. Hopefull someone will give a shout if I'm about to let the magic smoke out. Steven T. Fahey |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
There are several points here that I will address. Starting at the top. "The DC voltages across the caps". Some will say that one set of caps could be removed, and a direct winding coupling to one 3phase bridge would work. This is true, but as the AC voltage rises to the point where the normal 3phase non doubler 3phase rectifier would pass current, the caps would effectively be directly loading the windings in a parallel resonant manner. This is not the objective. The DC voltage across the caps? consider only when there is just DC current flowing to the load and above. 1/2 of the peak rectified AC voltage appears as a DC acrosss the caps at cap voltage doubler loading cutin. I have not had the opportunity to measure all voltages in all windmill operating conditions. The caps in the top and bottom rectifier cct are synchronized. The volages are directly additive within the cycle, and for each phase. The charging is not determined by the loading, as voltage doubling occurs below cutin, with no load current. The measurements in the pict above were measured from an unloaded test. The output voltage is proportional to the input AC voltage up to cutin. This is not a charge pump like you are suggesting, as the synchronicity gives the peak voltage straight away. There is no power charging and discharging of caps until current flows. There is a DC balancing charge voltage developed across the caps up to cutin, but no AC until current flows. As increasing AC power is passed by the caps, increasing AC voltage is developed across the caps. The voltage boost is linear with AC windmill output voltage up to cutin, and is not proportional to cap uF. The power transferred to the load after cutin is proportional to cap uF and AC Hz and the ACV developed across the cap in response to the loading. I think you will be surprised when you consider the windmill windings being effectively 2 parallel sets of windings with DC isolation being provided by the caps. The separation of the AC and DC with the synchronous operation allows the cct to function the way it does. Gordon. PS: anyone with a multimeter, handy with a soldering iron, or clip leads, with a 3phase PM motor and 12 diodes and 12 DC caps could show the voltage doubler function as an academic exercise. probably a few dollars for new components, Low voltage testing, not even a battery needed, 1n4001 diodes and 10uF 35V caps, and spinning the motor by hand on a pulley. The usefulness with a windmill comes with component sizing for the required power levels. PPS: from the meter readings above. The ACV was 38.2VAC. This would be approx 54.01 peakDCV, less approx 1.2V diode loss, so 52.8VDC. The measured 51.8V is close enough. double this is 103.6VDC. The measured 102.3 is close enough. All these measurements are within the meter measurement errors. become more energy aware |
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| herbnz Senior Member Joined: 18/02/2007 Location: New ZealandPosts: 258 |
Very surprised Not saying it dosent boost just how it does it. Gill stop grinning up there sorry I did not support you at the start you were right on with your analyisis. I will continue testing caps here but will end this discusion now as it appears the forum supports Gordons explaination. I myself cannot accept the isolation theory. Herb |
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| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
I reckon you should call it the "OZ-FLUX CAPACITOR" It will sit in the "fridge" electrical cabinet. Additional wires with ends are for the stop switches. This setup uses 12x 35A bridge rectifiers and 24x 680uf 450V caps back to back. Can be used for a dual stator mill or in my case a single stator with half in star and half in delta. caps ebay from Japan- best I could do was $100USD including freight.(which was 1/3 of the cost) Total is about $180 bucks worth of bits here and about 3-4hrs to put it together. From an economic point of view at 18c/kw/hr =1000KWhrs extra the 'mill will need to make over its life. I figure 1KW/hr/day extra it will make over uncapped rig call it 3 year payback which is not unreasonable. If you have no other sources of power ....probably priceless as not much will match it. 
Luck favours the well prepared |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Herb, This discussion has been in flux since last christmas, when I first presented the cap voltage doubler. I was hoping someone could have presented a spice simulation or similar in this time as well. Here are some measured AC & DC voltages that you requested. Just remember that no DC durrent flows through the caps, only AC, and this is only when there is current to the loading. I have just run a 1phase test of a cap voltage doubler only, using a single output 28V 2.5kW torroid on the mains. This has 4 pairs of DC caps connected to 2 bridge rectifiers, with the bridge rectifies connected in series. 50Hz test only. The output was quite constant DC wise on the meter. I used an 100uF cap, to simulate a small battery. The voltage did not drift up or down over time. The 28VAC input gave 76.8VDC output. The cap arrangement consumed 4mA rms AC at 28VAC. There appears to be no significant power[0.1W] consumed in the voltage doubling process. Unloaded, there is DC across the caps, but no AC. Both ends of the transformer output AC were at a potential of 30VDC above the negative potential of the lower bridge rectifier. The input of the top bridge rectifiers was 13VDC below the maximum DC positive output voltage, and the input of the lower bridge rectifiers was 13VDC above the voltage on the negative output. The ACV between the upper and lower bridge rectifier inputs to the bridge rectifiers, after the caps was 100VAC on one side, and 80VAC on the other. I expect that this is not a sine wave. I have probably posted a pic of the waveform around page 15. The path the current flows will be guided by the potential at each of these points. The pics posted by others did not make allowance for the DC across the caps. This changes the way the bridge rectifiers work. The windings sit at a DC potential approx half the output voltage, and the full input AC is effectively placed across each bridge rectifier. There are 2 bridge rectifiers, so the voltage will be double, which it is when measured on the cct. All I can suggest is that your understanding of the isolation here is different to mine. Take for instance, say bifilar windings on a transformer. These have low capacitive coupling, and galvanic isolation. These are useful to isolate power supplies in noisy electrical environments with high AC noise, as they block AC and DC interactions between the outputs. On the other hand, Caps pass the AC, so are not useful in this way. Caps do block the DC, so are useful to block a DC path, but still maintain an AC path. There is no need to have a galvanically isolated setup here in a cap voltage doubler. Hi Sparweb, any chance of a spice simulation? My voltage multipliers are working on my new design AxFx mill. Phillm has the Rolls Royce version at 3kW. The cap article has more details of my cap arrangements, and Phill has posted his config elsewhere as well. I have 12V batteries and LiPo cells. The battery is just that, an accumulation of cells. This gives the system voltage. A battery is not essential, but smooths out the transient power bursts from wind gusts. Your pic is OK. 3phase bridges make the connections easier as well. You will only need a total of 3. Gordon. become more energy aware |
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| SparWeb Senior Member Joined: 17/04/2008 Location: CanadaPosts: 196 |
[quote]3phase bridges make the connections easier as well. You will only need a total of 3. [/quote] Three instead of four rectifier blocks: This will probably become more obvious as I draw it up. Once I have a good diagram and tried wiring it up, I do want to try a Spice sim, too. Thanks. Steven T. Fahey |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi sparweb, Yes, with 3phase bridges, only 3 in a total system of cap doubler with a normal rectifier. 2 used in the cap voltage doubler, and one for the normal rectifier. The direct connected 3phase bridge would have a higher current capacity, as outlined in the cap article. It will be interesting to see what spice comes up with. Gordon. become more energy aware |
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