n-c alternator modifications: discussion and testing

[ecurbruce]

This is a continuation of the anatomy of stator coils;(started on page 15)

coils-color.jpg

This illustration depicts the stator coils of the six pole, four coil spools stator of the narrow case alternator.
As stated in previous posting, there are 2 larger coil spools, and 2 smaller coil spools. The larger spools have 4 layers of windings, with 22 turns on each layer. Two of the layers comprise one coil, then a layer of paper separating the next 2 layers comprising the other coil. They are wound counterclockwise (ccw).
The smaller spools also have the same configuration of layers, with the exception that there are 14 turns per layer, and they are wound clockwise (cw).
In the illustration, the circuit in orange is 1-4 consisting of coils A-B-C-D, the circuit in blue is 2-3 consisting of coils E-F-G-H. Small spool E-A is wound clockwise, large spool B-F is wound counterclockwise, small spool G-C is wound clockwise, large spool D-H is wound counterclockwise. On spool E-A, A is underneath E, on spool B-F, F is underneath B, on spool G-C, C is underneath G, on spool D-H, H is underneath D. So in each circuit the coil changes polarity in succession.There are 6 magnets for 4 stator poles, which means for each 360 rotation there are six wave pulses, and 2 of the magnet positions are dormant at each wave peak.

[DewCatTea-Bob]

" This is a continuation of the anatomy of stator coils;(started on page 15) "

____ First I must say that you've provided some very good & useful work Bruce !


" This illustration depicts the stator coils of the six pole, four coil spools stator of the narrow case alternator. "

____ Your illustration is fairly nicely well done Bruce ! _ It depicts most winding-details of the coil-turns of both stator-windings within the 4 dual coil-spools.
However I notice one possible issue with it, which seems ought to be incorrect...
While stator-winding '2-3' has all four of it's spool-coils wound-turned from outer-most to inner-most (of the stator-core),, the '1-4' stator-winding has most of it's spool-coils wound-turned from inner-most to outer-most, EXCEPT spool-coil 'C' !
So this leads to the question - is that as intended, or is that a mistake, (or could it be that it's the only one that's actually correct) ?


" As stated in previous posting, there are 2 larger coil spools, and 2 smaller coil spools. The larger spools have 4 layers of windings, with 22 turns on each layer. Two of the layers comprise one coil, then a layer of paper separating the next 2 layers comprising the other coil. They are wound counterclockwise (ccw).
The smaller spools also have the same configuration of layers, with the exception that there are 14 turns per layer, and they are wound clockwise (cw). "

____ From this data plus that provided by your illustration, we can now understand why Bill's measurement-tests indicated that one alt.winding had slightly higher power-output than the other...
While stator-winding '2-3' has 56 longer/outer coil-turns & 88 shorter/inner coil-turns,, stator-winding '1-4' has 88 longer/outer coil-turns & 56 shorter/inner coil-turns,, thus providing the '1-4' winding with 32 turns of a slightly larger average-radius, (therefore a longer winding, with more opportunity for induction).


" There are 6 magnets for 4 stator poles, "

____ Not really worded correctly Bruce, as both the alt.rotor AND the alt.stator each have 6 'poles' , (it's just that 2 of the stator's core-poles are left without a coil-spool).


" which means for each 360 rotation there are six wave pulses, "

____ Right... 3 positive & 3 negative, from EACH alt.winding.


" and 2 of the magnet positions are dormant at each wave peak. "

____ It may seem so (at least 'directly'), however I'm sure those two magnetic positions at least help assist in polarizing the stator-core.


Thankful-Cheers,
-Bob

[ecurbruce]

Bob,
Concerning how the spools are wound, we can all agree that they are all wound from bottom to top- from inside to outside. I didn't have a good way to draw that detail, let's just say that's how they are!
However, it may be that you're questioning this; thinking of continuity of the series circuit, as the cir uit passes from one spool to another, it always goes from outer of the previous to inner of the next.

[DewCatTea-Bob]

By: wcorey...
" Took a break from testing, actually worked on the bike instead. "

____ Not to be faulted at all for that Bill !

I believe you've had a test-result that didn't check-out to be exactly confirmed... Once, (as I think I recall), the series-connected alt.windings' combined AC-output was simply somewhat less than double that of either winding alone, while another AC-test indicated that the series combined output of both was actually a bit LESS than either alt.winding's output by itself.
So the test ought to be run again, to clear-up which outcome is most correct.

" I'm confused by the above statements in bold, they both sound like the same thing but worded differently. Could you re-phrase so it registers another way in my brain? "

____ Sure! _ First I should restate that I'm not sure but, it seems that one-time your test-outcome indicated that the two windings connected in 'series' produced power-output which was somewhat less than would be expected from the two added together - (in other-words, 1 + 1 equaled about 1.5). _ While (I believe) another quite similar test-outcome indicated that the two combined in 'series' produced even less than either winding all-alone - (in other-words, 1 + 1 equaled slightly less than 1).
The older test may have been done with the bulb-load (which probably didn't draw as much power as the later test-load did). _ In any case, it would be quite useful to confirm (if possible) the later test-result (with it's more incredible outcome).

...the series-connected alt.windings' combined AC-output.... So the test ought to be run again, to clear-up which outcome is most correct.


" No load or rectifier? If loaded, what resistance? Drawings always help, "

____ Yes, same load & rect.block setup, and I now have the related scheme-diagram posted (way-down at bottom, underneath the other two posted-pix).
__ All these latest tests ought be done with the 1-ohm load, since that then allows for direct-comparisons & also indicates the alt.power-output near it's strongest.

" Same as what? Is this the same as what's in the previous quote? There are no values on the drawing and too much time has passed for me to recall which particular past test we are comparing to. "

____ I meant same as the last/most previous (at the time, [and I don't think you've done any other test since]). _ But that shouldn't have mattered much, cuz I also supplied the related scheme-diagram and reminded of the "1-ohm load" .
So in other-words, (if nothing has been changed since the very-last test), you then only need to replace the 3-ohm load with a 1-ohm load.


Hopeful-Cheers,
-Bob

[Bevel bob]

Ok Bill,I'll hang on in there, would be a bit sad to go through 20 pages of posts and only gain a headache!!.

[MotoMike]

Bruce
thanks for that good work on disecting the coils.

It does make sense and I don't find fault with Bob's critique. I do have an area that I would want to consider further before offering an opinion. Now this has nothing to do with helping us understand the circuit, but the two un used cores and their effect on the system is what I'm talking about.

In way of clarification, should the 3 negative pulses and the 3 postitive be discussed?. Resulting from the north-south orientation of the magnets? I loose prespective sometimes and if, said clarification goes without saying, then disregard. Is it clear how the magnets are distrubuted and why? I'd discuss this if desired.

[MotoMike]

Bill
You are a real trooper.

Bob wrote:____ Sure! _ First I should restate that I'm not sure but, it seems that one-time your test-outcome indicated that the two windings connected in 'series' produced power-output which was somewhat less than would be expected from the two added together - (in other-words, 1 + 1 equaled about 1.5). _ While (I believe) another quite similar test-outcome indicated that the two combined in 'series' produced even less than either winding all-alone - (in other-words, 1 + 1 equaled slightly less than 1).
The older test may have been done with the bulb-load (which probably didn't draw as much power as the later test-load did). _ In any case, it would be quite useful to confirm (if possible) the later test-result (with it's more incredible outcome).

MM
Of all the testing you have done this is the one that is still a bit of a mystery to me. My initial thought is that with the low ohmic load the current through the series connected full stator was enough to cause the opposing fields to be strong and give us the less than the voltage ouput of half the stator alone. Then with the 3 ohm load you got voltage acceptable for a 12volt system but if I remember correctly still not twice the half stator voltage. so I though that the trippled ohmic load was reducing the effects of load current induced opposing fields so as to allow more output from the series connected coils. Clearly your tests of connecting the coils in series but out of phase where the ouput is near zero shows that is not the cause of the less than expected output. So if opposing fields resultant to load current is not what is going on, I'm still left wondering why the output with a 3 ohm load is not more clearly near double that of half the stator alone. The line of reason that at the low ohmic value we are reaching the point where the alternator just can't handle that load would seem to be invalid when looking at some of your other tests with only one half stator in use and a one ohm load. So I'm still thinking about this one. Even if we get no further I can live with my hypothesis because we know these systems can be put into service in a 12 volt system.

Bevel Bob is riding just such a system around with no problems. I don't know if your testing can replicate Bevel Bob's system. Maybe DCT Bob can speak to the quality control and similarity between one system to another in terms of magnet strength and spacing between rotor and core ends also if the magnets seem to maintain well after 45 years in service. I only mention this because a very slight difference in magnet strength and/or spacing results in a big difference in performance.

[ecurbruce]

Of course, Mike!
There are six magnets on the flywheel, three with the positive pole pointing into the stator, alternating with three with the negative pole pointing into the stator. Thus each passing magnet in rotation creates it's positive or negative wave in the stator coil.
Also I believe there are a total of six positive and six negative pulses total, depending on how it's wired?

[MotoMike]

I would add that those magnets, as their fields get passed through the coils, induce a voltage across them. with the magnets alternating, n,s,n,s,n,s the polarities they induce would be opposite from one coils to the next, if not for the coil windings being alternated cw,ccw,cw,ccw in the series connected stator. The net result is that the voltage induced across all the coils is in phase and adds together. If frozen at the instant of time when 4 magnets are pulsing 4 coils (2 sets of 4 coils actually) thier polarities will add together as in the D cell analogy. -+,-+,-+,-+ (of course it could be the opposite and during the next magnet pulse it will switch polarity) so that their total is felt across the half stator they compose.

[DewCatTea-Bob]

" I would add that those magnets, as their fields get passed through the coils, induce a voltage across them. "

_____ I don't have the time to post a pic of the rotor with it's 6-poles showing, but while the end-result would of course still be the same regardless of knowing about the exact arrangement of the rotor's six magnets,, it may still be worthy to note that the magnetic-flux which passes through the coil-windings is not direct and could be thought of as 'third-hand'. ...
That's because each of the flywheel-rotor's 6-poles are magnetized by either the North OR South sides of two magnets, (thus the concentrated N or S flux [of 2 magnets] becomes 'second-hand' THROUGH the rotor-poles.
Next, the flux-fields from the rotor-poles pass-on their respective fields into the stator-cores, and it's then actually the induced flux-fields from the stator-cores which "cut" the coil-windings, thus "third-hand" magnetic-flux is what really induces the coil-windings, (not the magnets directly).

UPDATE: - I've now added a pic of the inside of the rotor, indicating the magnetic-pole set-up within.
(If the pic needs adjustment, please let me know, [and I'll do it better].)


Dukaddy-DUKEs,
-Bob