Newbies > Newbies
stator question
derekisastro:
--- Quote from: DanB on July 13, 2010, 12:07:14 AM ---
--- Quote from: artv on May 12, 2010, 07:08:07 AM ---Hi Flux ...single phase with (9 coil, 12mag)...is it all the coils are hooked in series one right after the other?Three phase every third coil hooked in series? So single phase is basically one coil, Three phase basically three coils.This way the three phase would be better because it creates less heat being its' only producing 1/3 of the time,compared to single which produces all the time?When things get hot effiecency goes down.......don't know if I'm reading things right...........artv
--- End quote ---
Hi Art.
you cannot have single phase with 9 coils and 12 magnets. In order for 2 coils to be in phase, they must be seeing an 'identical magnetic situation' (not sure how else to say that) - which is impossible with 9 coils spaced evenly around 12 poles. But - with 9 coils around 12 poles, then 3 of those coils are seeing an identical situation and they are therefor 'in phase' with one another.
--- End quote ---
As another 'new' guy to motors/generators, this may be one of the more concise descriptions that I have heard that simply explains how to think of poles and coils. It's actually quite amazing how much research you can do and still struggle to find, what to new people, seems like the easiest and most obvious questions to answer.
Try Googling "how to wind a stator" and it's really difficult to find simple and concise answers as well as simple and concise reasons as to why you wind coils in a certain way, why you link them in a certain way, and how you consider the numbers of poles and magnets ... YES ... I get that 'it depends upon what you want to achieve' but there are still some really simple guidelines that I think many take for granted, that when explained to new people might actually help us really learn and understand some concepts.
This above description is one of them. I am thinking of putting together a dummies-style guide to motor, generators and such, such that a newbie can get a head start. This definition will be part of it.
Thanks!
SparWeb:
We're here to help.
Very valuable resource, these members - even the ones no longer with us now.
BTW, one of the links above in Reply #6 is broken. The link to that document is now at: http://www.sparweb.ca/Forum/AXIAL_FLUX_HowItWorks.pdf
Hope that helps.
derekisastro:
--- Quote from: SparWeb on July 29, 2019, 10:08:03 PM ---We're here to help.
Very valuable resource, these members - even the ones no longer with us now.
BTW, one of the links above in Reply #6 is broken. The link to that document is now at ... AXIAL_FLUX_HowItWorks.pdf
Hope that helps.
--- End quote ---
Tis a great article to be sure ... though still some interesting take away's ... 3 things that I'll mention ...
1) They quote 1.33 magnets per coil but really give no other explanation other than "here's the trick" ... don't get me wrong, I don't believe you can go wrong with the 3 coils to 4 magnet ratio ... I just know from even just this message board alone, that many (including Hugh himself) have bucked this "trick".
2) I just love this quote from the article ...
The decision on how many coils/magnets to put into the Alternator is somewhat arbitrary,
somewhat mystical.
and lastly 3) it also says ... either 12V, 24, or sometimes 48V, depending
on your system. The size and gauge of wire should be selected to produce the right voltage.
... but gives no mention of the selection parameters or guide lines and I get that it's not easy to do so but still ... I guess it's part of that 'mystical' part of PMA's.
SparWeb:
Well, it's a "how it works" document, not a "how to design", which would be much longer.
The details that you mention are actually rather hard to pin exactly. Certainly not with a rule of thumb or a simple ratio. There are too many things affecting the choice. If you just want to make simple comparisons, then the range of operation at 12V requires lots of current for a given voltage, while a 24V system needs twice the voltage and half the current. That means that the alternator needs 2x as many turns of wire per coil to have (roughly) the same power range. And all that gets you is a comparison between to uses of alternator. It's not a rule to use for choosing the EXACT wire size you need in any given alternator. That takes a lot more information to sort out.
It does seem like that intro guide is leading you to ask some good questions. Perfect.
Astro:
--- Quote from: derekisastro on July 31, 2019, 08:31:06 PM ---
--- Quote from: SparWeb on July 29, 2019, 10:08:03 PM ---We're here to help.
Very valuable resource, these members - even the ones no longer with us now.
BTW, one of the links above in Reply #6 is broken. The link to that document is now at ... AXIAL_FLUX_HowItWorks.pdf
Hope that helps.
--- End quote ---
Tis a great article to be sure ... though still some interesting take away's ... 3 things that I'll mention ...
1) They quote 1.33 magnets per coil but really give no other explanation other than "here's the trick" ... don't get me wrong, I don't believe you can go wrong with the 3 coils to 4 magnet ratio ... I just know from even just this message board alone, that many (including Hugh himself) have bucked this "trick".
2) I just love this quote from the article ...
The decision on how many coils/magnets to put into the Alternator is somewhat arbitrary,
somewhat mystical.
and lastly 3) it also says ... either 12V, 24, or sometimes 48V, depending
on your system. The size and gauge of wire should be selected to produce the right voltage.
... but gives no mention of the selection parameters or guide lines and I get that it's not easy to do so but still ... I guess it's part of that 'mystical' part of PMA's.
--- End quote ---
#1. I think it is because it works out almost as perfect as you can get it. The most amount of mags you can fit. Not physically, but in terms of what we are trying to do. Think about it, you are putting coils in a circle. You are putting mags in a circle. What is an important number to know when working with circles? What does you stator and mag rotor look like when you get it all drawn out? Pie. 3.14. 3 coils 1 stator 4 mags. Coincidence??? That is probably not why, but I am pretty sure it is because it works out in the math of the physics of what we are trying to do.
#2 and 3. You answered. There are a million different ways to build this thing and the decisions made on choosing the size of wire, the number of winds among many other factors are going to decide what you get out in the end.
This is why I have a hard time explaining from the beginning how to build these things, because first we need to know what it is we are trying to accomplish. What avg wind speed is available, and many other things need to be thought of in the design. You might have a guy on here that has a mill that makes 10kwh a day with his set up, but take it down and move it 200 miles away and set it all back up the same exact way and you may only get 5kwh per day. So one needs lots of parameters first. Then they need to know what the goal is. I mean you are not going to produce several kwh per day from a mill with 18in blades.
The mystical is not as mystical as it is combining many numbers together to build something that works well. But again it will work better in one place then another, because some of those numbers are site specific.
This is why when they make the great big windmills AND they are all made the same size, they choose where to put them based on avg wind speed. Because they know that the design works best in that wind condition. They really can't individually build such large machines and taylor build them to the environmental conditions. Plus in areas where the wind is sub 15mph most of the time you are going to have an even harder time making a machine to extrapolate power from the wind. Not that you can't, but that it is harder to do. You have less "fuel" for the wind mill. If we put a gallon of fuel in our lawnmowers, we can go mow for well over an hr. Put a gallon of fuel in my truck and hook up my rv and you are only going to go 15-20 min. Different "motors" for different needs. Except in our case the need does not change, only the amount of fuel available. You are not going to produce 80v and 60 amps in 5mph wind, just like you are not going to pull an rv with a lawnmower. Again it is physics. You can however make 80v at 5 amps. (just making up numbers as an example). But basically if you have lower wind conditions most of the time, you are going to do better with many small mills over 1 or 2 bigger ones. If you only have enough fuel to run a lawnmower, and you want to pull an rv, you are going to need more lawnmowers.
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