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Forum Index : Windmills : 48, 56, 36, 42 7 phase ????
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| greenlivin Newbie  Joined: 05/04/2012 Location: United StatesPosts: 12 |
Ok, just read the 7 phase conversion article and went to count my mags. Sure enough, mine is the 48 type. However, I have the 36 pole stator. There is a fair amount of cogging even after I twisted the poles. I was thinking of getting a 42 pole stator and doing the 7 phase conversion with my 48 pole hub and then using the 56 mag hub with my 36 pole stator for a dual mill. Question is, has anyone ever tried the 56 mag/36 pole combo before and how in the world would I wire that one? |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
The 36 pole stator 48 magnet hub combination that's used in later model F&P's should have very little cogging. The stator should have rounded poles, and the magnets, if you can sprinkle a few iron filings on them, look like triangles. You shouldn't have to twist the poles, so I'm not sure whats going on there. Using the 56 magnet hub on a 36 pole stator can work, but its a unusual combination. You end up with 10 phases, so you need to build a 10 phase bridge rectifier. No big problem, 5 standard bridge rectifiers will work. There will only be 4 coils per phase, so you can reconfigure it as 10 phase 1X4C, 2X2C or 4X1C ( see http://www.thebackshed.com/windmill/FPRewire.asp ) I dont think anyone has tried it. Output should be the same as a normal F&P build, just a lot more diodes. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| greenlivin Newbie Joined: 05/04/2012 Location: United StatesPosts: 12 |
So, essentially, I would get maybe the same return on the 36/48 that I loose through the aluminum windings and the other one wouldn't make any more power but it would take more parts and effort. O' well, it was a thought. I like the idea of decogging through the one by swapping though, so maybe it would be worth the effort for that reason alone. Especially if it results in decogging the other as well. Given my wiring skills, the 10 phase will likely resemble a birds nest when I'm done https://s3.amazonaws.com/TrollEmoticons/why.png |
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| greenlivin Newbie Joined: 05/04/2012 Location: United StatesPosts: 12 |
BTW, how do you do the math to come up with the phase combinations. That could be useful info. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I cheat. I use CAD to draw the stator,( just points around a center, nothing fancy, circular array they call it. ) and hub, then count how many stator poles line up with a magnet exactly. I also check the magnets are the same pole. 
You can see in this one the magnets and poles only line up in 4 places. Count the stator poles and we have 9. Hang on, I'm sure that was 10 last time I looked 
OK, my mistake, it's a 9 phase machine. There would be a simpler way to work it out mathematically, but I think visually and hate maths. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| greenlivin Newbie Joined: 05/04/2012 Location: United StatesPosts: 12 |
O' I gotchya. Since you had the answer, I played with the math and, yeah, I can see why you do the visual thing 
So, this means I should end up with nine blocks of four, right? |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yes, the max number of coils you can wire up in series is 4. Nothing wrong with that, 4 coils ( 9 phase 1X4C ) could be used for 24 or 48 volts, depending on the turbine. You could also wire it up as a 9 phase 2X2C for 12 or 24 volts, again depending on the turbine. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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