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PCB coils for alternators??
By Tom in NH, Section Mechanical Posted on Sat Jan 28, 2006 at 04:10:44 AM MST
Has anyone ever experimented with printed circuit board stators?

It seems like I've been spending a lot of my time lately designing printed circuit boards. It occurred to me that it would be easy to design a circuit board that had copper coils printed on it. You could use a multi layer board for multiple coils. The board might make a nice stator that would allow you to reduce the gap between the poles to insanely narrow distances. Have any of you alternator and generator folks ever experimented with something like this? --tom

PCB coils for alternators?? | 21 comments (21 topical)

Re: PCB coils for alternators?? (3.00 / 0) (#1)
by stevesteve on Sat Jan 28, 2006 at 02:18:21 AM MST

That's a cool idea. I was looking at a project that someone posted a link to the other day ( a metal detector with the search coil made on a PCB) and I didnt make the mental jump - duh!

It might not be so good for the large power machines that many folk make but it might be ideal for a small low power machine. The inter-pole spacing on a dual machine could be really low but there might be an issue with cooling.
Cheers, Steve

Re: PCB coils for alternators?? (3.00 / 0) (#2)
by jlt on Sat Jan 28, 2006 at 04:37:33 AM MST

seen a moter built like that i thimk it was a pancake moter from a subaru heater.

Re: PCB coils for alternators?? (3.00 / 0) (#3)
by dinges on Sat Jan 28, 2006 at 06:23:10 AM MST

Hmmm,

In the motor business (for VCRs, CD/DVD players, etc) there are lots of people trying to do their utmost best to squeeze the last penny of cost-savings out of the product. The fact that you don't see the motors as you describe (which would be much cheaper & simpler to manufacture than glueing & soldering on coils) may mean that the route doesn't work (for motors, so probably also not for alternators)

For a metal-detector, give etching coils a try. For an RF-oscillator (that doesn't have to be very stable), go ahead and etch the coil in the PCB (check for example SM0VPO, Harry Lythal from Sweden; he has designed 3m FM transmitters with etched oscillator coil)

You think you can get more than 10 turns in there? (per coil?). Hmm, you might use double-sided PCB, that would mean double the nr. of turns/coil.

Still, I personally wouldn't bother. But certainly would like to read a story in some days how you did manage to get it working after all :)

Peter.

Re: PCB coils for alternators?? (3.00 / 0) (#4)
by Flux on Sat Jan 28, 2006 at 07:12:50 AM MST

Printed circuit motors have been around for years, but they never seem to have been accepted for other than servomotors where low inertia and low inductance are properties valued above all else.

Probably the reason they fail to get into the domestic motor market is the difficulty of producing enough turns, but I assume it could be done with layers of film circuits and through connection.

Electro forming has been tried with commutators and probably for windings but has not proved better than other methods for general use.

It may happen one day, sometimes a spin off from one technology opens a new field in other areas where the development cost would have ruled it out.
Flux

[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#5)
by zubbly on Sat Jan 28, 2006 at 07:21:50 AM MST

hi Tom!

printed circuit board motors have been in use for some time. many are used in the textile industry for the twisting of the yarns at very high speeds. most are rated in the 1/15 to 1/25hp area. not big, but more than sufficient for use needed.

zubbly

Re: PCB coils for alternators?? (3.00 / 0) (#6)
by ghurd on Sat Jan 28, 2006 at 08:40:28 AM MST

I have a 4 brush Kollmorgan (sp?) from an industrial sewing machine. Low inertia, high speed (7100?). The coils are cast in fiberglass, about 1/8" thick, VERY few turns. Very good ceramics or very weak neos, about 3/4dx1" long, chrome plated magnets. Looks like a dual rotor... except for the coils, and the wrong part rotates.

Outside, it looks like those 99 cent ebay surplus scooter motors. But bigger.

With the import textile and clothing situation in the US, these will be available in quantity soon.
G-
Ghurd.info

Re: PCB coils for alternators?? (3.00 / 0) (#7)
by zap on Sat Jan 28, 2006 at 10:49:56 AM MST

Interesting article here http://www.cse.cuhk.edu.hk/~phwl/mt/public/archives/papers/gen_isssm00.pdf

zap

Re: PCB coils for alternators?? (3.00 / 0) (#8)
by wooferhound on Sat Jan 28, 2006 at 08:18:48 PM MST

Folks have talked about now many turns you can make on the PC Board. But i wonder about the current carrying capacity of the small spirals that it would need to be.

W o o f -={(

Re: PCB coils for alternators?? (3.00 / 0) (#9)
by Tom in NH on Sun Jan 29, 2006 at 05:51:03 AM MST

Yeah, that's my concern too, Woof. Current capacity is a function of the cross sectional area of the conductor, and there's not a lot of cross sectional area on a PCB trace. --tom

[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#10)
by stevesteve on Sun Jan 29, 2006 at 08:37:30 AM MST

I have been talking this over with my brother, the rocket scientist (space electronics design etc).
It might be possible using both sides of a board -tracks inside a multilayer PCB might just cook and are harder to make as a prototype. If I can get the time I am going to try to make a small coil this way any try it out.
Don't hold your breath though, it will take a while to get round to and I haven't even bought the board/etch kit yet. Only V small power systems possible though. To get more amps you need wider tracks, which mean less 'turns' would fit.
Cheers, Steve
[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#11)
by wooferhound on Sun Jan 29, 2006 at 08:54:34 AM MST

Once you get a spiral etched onto both sides of the PC Board, How will you bring the center of the spiral on one side of the PCB to the outside of the spiral on the other side of the PCB. Then get the center of the second spiral out to a point where you can use it ?

W o o f -={(

Re: PCB coils for alternators?? (3.00 / 0) (#12)
by stevesteve on Sun Jan 29, 2006 at 09:04:09 AM MST

Err... reverse the spiral and take it from centre back out? Yes, I'm making it up as I go here!
Cheers, Steve
[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#13)
by Flux on Sun Jan 29, 2006 at 09:05:18 AM MST

Wind the spirals in opposite directions, link the insides and take power from the outside.

Can wind dual rotor coils that way and avoid having to have a thick wire crossing the coil and causing extra air gap.
Flux

[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#14)
by stevesteve on Sun Jan 29, 2006 at 09:14:19 AM MST

Hey, two answers both the same... must be right ;-)
Cheers, Steve
[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#15)
by wooferhound on Mon Jan 30, 2006 at 06:28:47 AM MST

If one coil is reversed it will cancel out the voltage to zero

W o o f -={(

[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#16)
by stevesteve on Mon Jan 30, 2006 at 11:46:22 AM MST

I don't think it will cancel if one is wired outside-in and the other inside-out. the current would be flowing the same way in the circuit. (not guarenteeing that I'm not confused of course).
Cheers, Steve
[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#17)
by asheets on Mon Jan 30, 2006 at 12:44:56 PM MST

This sounds like an interesting idea to try. My dad once had a contract to build some kind of motor controller, and he used a bunch of scrap PCB his company had around, some etchant, and used a "Sharpie" to draw his traces (I guess the stuff acts as a halfway decent resist).

My issues would be (1) how thin to draw the trace, and (2) how to draw the trace reasonably uniform with the Sharpie...
_____________________________

Alan Sheets

Re: PCB coils for alternators?? (3.00 / 0) (#18)
by RP on Mon Jan 30, 2006 at 10:18:04 PM MST

Actually a lot of folks make laser printer printouts (extra dark) and then use them as an iron-on to transfer the toner to the PCB. It works but it can be tricky to avoid defects.

[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#19)
by asheets on Tue Jan 31, 2006 at 11:54:51 AM MST

hmmmm, sounds like something to try... using standard thickness, doublesided PCB board...

how thick should the traces be?
how big should the coil be on each side of the pcb?
how many pcb boards should be stacked together to make a decent-performing coil?

_____________________________

Alan Sheets
[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#20)
by asheets on Tue Jan 31, 2006 at 11:58:04 AM MST

Now that I think about this a little more, you could also use adhesive copper foil. I used to use that stuff in making stained glass stuff, and the thinnest width available would almost be the right size for a "coil" that could carry electrons with only a somewhat minimal resistance loss...

Or you could take the thicker stuff and trim it down to size...
_____________________________

Alan Sheets
[ Parent ]

Re: PCB coils for alternators?? (3.00 / 0) (#21)
by ghurd on Tue Jan 31, 2006 at 09:21:27 PM MST

The 2 ounce cu can carry some pretty good amps in a narrower than expected trace. The outfit I deal with said they can make it as thick as needed when I wanted 6 ounce, and they said it could be several layers. Afraid to ask the cost.
G-
Ghurd.info
[ Parent ]

PCB coils for alternators?? | 21 comments (21 topical)

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