 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. |
Forum Index : Windmills : Rewiting F&P
| Author | Message | ||||
| RossW Guru  Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Oh dear, I think I may have "shot myself in the foot". Looking at the F&P, it seems to be a 42 pole machine. 42 poles divided by 3 phases = 14 poles-per-phase. If it's designed to operate off 220V AC, with full wave rectification, thats 308V DC, so roughly 22 volts per pole. But I have a 48V system. No worries, 2 poles makes 44V, 3 poles 66V. Probably better than 44, as long as I keep the load on it. But.... 14 poles / 3 doesn't go! There are (as I see it) only 4 ways to connect it for optimum operation: a. 3 phase, 14 series = 308V @ 2A b. 3 phase, 2 x 7 series = 154V @ 4A c. 3 phase, 7 x 2 series = 44V @ 14A d. 3 phase, 14 parallel = 22V @ 28A That all assumes the thing is running at "full speed" (doubtful), and full-wave rectifiers on the output (which I would do). The alternative I guess, would be to rewire in star, not delta, and pick up the sqrt(3) voltage gain a. 3 phase star, 14 series = 533V @ 1.2A b. 3 phase star, 2 x 7 series = 266V @ 2.3A c. 3 phase star, 7 x 2 series = 76V @ 8A d. 3 phase star, 14 parallel = 38V @ 16A Yet I notice here, you're using 2 coils in series in 7 parallel groups to charge 12V battery banks, which just doesn't fit my figures. What am I missing? Does anyone have a better voltage Vs RPM chart anywhere? And/or, has anyone done any tests (this would be interesting) of constant RPM and varying the load current and seeing what the output voltage does, and how much power one transfers from it? *ponders more* It'd be really interesting to plot input current (power) to spin one of these, then adjust the current to get a desired voltage (as would happen charging batteries), and plot input power and RPM as a function of output watts! |
||||
| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
I use 4 and 4 in parallel times three phases with each phase full wave rectified on my bicycle generator. I get 14 volts at 5 amps with the rotor RPM about 450. I think there is a table online somewhere from the NZ people who offer the F&P kits, cant recall the name exactly but maybe something like "Ecotech" |
||||
Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Ecoinnovation in NZ. Michael is the guy behind a lot of the early F&P work. http://www.ecoinnovation.co.nz/links.php?code=8 I have a standard 80 series on my Lenz windmill. In standard trim, not reconfigured, the F&P makes 13 vdc ( after a 3 phase bridge rect ) at 20 rpm. Divide 12 by 14 poles, gives 0.93 volts per pole at 20 rpm ( ignoring star connections for now ). So at 100 rpm each pole is 4.6 volts. 300 RPM is 13.9, etc. You just need to work out what sort of RPM you expect and what voltage you need. Unfortunately 14 doesn't divide very well! Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
Hi Ross, I split the 14 poles in half and draw power of both ends, 7 pole delta. I can get charge at 12v at around 60rpm. I have seen it go up to around 300rpm, open circuit voltage at 75v DC. With the 2 pole star to charge 12v the rpm needs to be 180+ To charge 48 volts, you would need at least 7 pole to charge at a reasonable rpm. Trev @ drivebynature.com |
||||
| Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
Hi Ross, just checked your wind data again, possibly you will have to use 14 pole to get the voltage high enough Just experiment to match all perameters,-wind speed, driving force, rpm, voltage etc. Have fun Trev @ drivebynature.com |
||||
| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Yes, thats my feeling also, although I was contemplating one other - that a simple 3-phase rectifier into a large capacitor (I have a bunch of ceramic 31,000 uF, 50V working) caps here - with balancing resistors they'd probably made decent 100V banks), and a large SCR, I could make a charge-pump and operate at (near) optimum output. Perhaps a commercial MPPT converter would be a better option, although at close to 1KW it won't be cheap. By "14 poles", I presume you mean I should just use an unmodified F&P motor? Glenn - whats the latest on a LENZ2? I'm very interested to try a VAWT that may work better in turbulent (and low) wind. I have another thought, that perhaps the gears from a bicycle might be an option - gear up with light winds and down in strong ones. This of course would be a lot easier to achieve with a VAWT. Anyhow, still thinking and planning. |
||||
| Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
Hey Ross, yes 14 poles, I do mean not re-wired, that is 3 phase x 14 poles. Of course it is worth experimenting though. Trev @ drivebynature.com |
||||
| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Ross. Latest on the Lenz2 is lack of funds at the moment. I just got the rates bill and my car rego is due, you know how it is. But I've been collecting tid-bits of info ( bearings, steel prices, etc ) and will start soon. First up is the tower, and then start on the turbine itself. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Sadly, yes, all too well. Silly questions.... but hey, if I don't ask I'll never know! How large are you planning to make your beast? What power are you expecting to get from it in practice? Is there any savings in quantity (well, making two!)? Would making two and having someone paying for one help? (by "help" I mean either giving you the incentive, and/or combined with benefits in quantities, letting you do it sooner rather than later?) While I'm not particularly flush with funds, I'm even more time-poor at the moment, and if there is a way we can kill two birds with one stone, then I'm interested! *IF* I had the time, inclination and resources, I'd make a reasonably large VAWT, probably NOT a direct-drive one, but an offset-drive so I can use timing belts or chain drive to play with gearing, brakes etc. RossW |
||||
| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Ross. It is going to be 2400mm high by 2010mm wide. These figures suit a wing made from one sheet of 2400*1200 aluminum. Gives a frontal area of about 5 meters square, fairly big, and this introduces a bunch of problems. The drive shaft will be 48.3mm thick wall pipe. Each wing will be supported on two 40mm square spar's. The thing will be heavy, I tend to over engineer my windmills. I'm yet to design the ribs that will hold the aluminum sheet, but will use a similar design to the smaller Lenz2 windmill, meaning I can adjust the wing angles if needed. Power is unknown at this stage. What I'm aiming for is a windmill that makes more watt hours per day. My little Lenz2 ( 1200 * 1300 ) direct drive to a F&P is making power most of the day, even if only a few watts, while the big HAWT is making nothing. So even though is a small windmill in a bad location, it makes more watt hours per day than the big HAWT windmill. And watt hours is all that counts. I was going to run a 1 inch drive shaft down the tower to about chest height. I could then play around with gear boxes or belt drives. I have a few 9 inch angle grinder gearboxes I can try, they have a 4:1 ratio. Using one of these means I can spin a F&P at four times the turbine speed, and the torque of the vertical means no starting problems. Yes making two would be cheaper, but this is a prototype that I will me making little changes to as I put it together. But that said, I have a lot of faith in Ed's design, and plan to build another as soon as the first one is finished, and then I can punch out a extra set of parts. I'll need to discuss this with Ed, I know he has plans for his design and I dont want to step on his feet. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
By all means, please chat with Ed. If he's happy, and you're happy, I'd be delighted to help "spread the good word" as it were! My websites are fairly busy - my "main" site is just about to tick over its 7 millionth visit, my "skycam" site gets about 175,000 hits a month, the weather site gets about 120,000 hits a month. I haven't made much mention about our renewable energy sources yet, but would be happy to give Ed a plug! (Unless he'd rather not, of course!) I agree, it's watt-hours produced in a day thats important, not just the peak watts ability. I've just been offered some 500 amphour 2V VRLA batteries that have been used for only 12 months. They'd make a decent addition to the setup here and give me a little more storage capacity for any surplus watts that might come my way! At under $100 each, it means about $2K outlay for my 48V installation. (It does mean a 3 hour drive to the big smoke though! My trailer is good for 2 tonnes, so can handle them all in one load.) |
||||
 Print this page |
