I need help identifying the leads on a stator winding

Popper299

Joined Jan 12, 2022
4
Hello, if this isn’t allowed then sorry, I’ve been tearing my hair our trying to understand the leads on a stator winding that came from a car alternator. I’ll start by saying this is the first project of this kind that I’ve ever attempted, I’m in school for electrical engineering junior level, but I’ve never worked directly with any stator windings.

Eventually I would like to wire the stator to an ESC in a delta or wye configuration, but for now I need to determine which leads are connected to which pairs of coils. I have done a lot of research and I thought I understood what to do but now I’m not so sure. So right now there are 3 pairs of 2 leads. The leads have continuity in 2 pairs of 3. If you see the attached pictures, the red dotted leads all have continuity with eachother, and the green dotted leads all hve continuity with eachother.

Based on the research I’ve done, I thought that I needed to snip the parallel wires and leave myself with 6 pairs of 2 wires. I thought that each of these pairs would be the ends of 1 of 3 inductors, the pairs being 2 inductors that ran side by side. But before cutting the parallel wires, I did some thought and came to the conclusion that I would not be left with what I anticipated.

So basically my question is if anyone can provide advice or expertise about these stator winding leads, if they would be able to essentially help me identify A1 A2 B1 B2 C1 C2 or if they have any other suggestions. Thanks if you took the time to read and think about my problem. Perhaps with enough time I will be able to understand it on my own.

Joined Jul 18, 2013
24,980
Apparently it would appear you have a Delta connected stator? As opposed to the usual Star connection type.
I'm assuming that each pair were connected before you dismantled the unit?
Star connection gives higher voltage and Delta delivers higher current for a given rpm.

LowQCab

Joined Nov 6, 2012
1,914
"" Eventually I would like to wire the stator to an ESC in a delta or wye configuration, ....... ""
It looks like it was originally wired Delta, which is most common for Car-Alternators.
Just connect the Wires back together exactly as they came.

It will require a lot of Current at a relatively low Voltage,
not surprising, seeing as how it's a 12-Volt Alternator,
and probably capable of handling ~75 to ~100-Amps,
and up to ~5-Amps to excite the Rotor-Winding.

You can expect up to around 2-Horsepower, maybe more, at around 24,000-RPM plus.

You will need substantial Current-Limiting for low-RPM operation, to prevent over-heating.

Alternators need a Sine or Triangle-Wave for most efficient operation,
a Square-Wave will cause over-heating.
Triangle-Wave is best.

Start-out with something simpler, like a Motor for a Radio-Controlled RC-Airplane or Drone.
https://store.tmotor.com/
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Popper299

Joined Jan 12, 2022
4
Thank you both very much for your insights, I will for now proceed forward with the assumption that I am working with a delta configuration if i connect the pairs together.

I will provide pictures below of the rectifier that was originally mounted on top of the alternator, in the hopes that it may provide more insight if possible/necessary.

I will provide a picture of the top of the rectifier and tbottom, and one additonal closeup picture of the top. The crack you see in the middle at the bottom did not originally exist thats something I did while removing the rectifier.

I am very grateful for any insight that can be provided, especially additional votes that I have a delta configuration. Additionally, being an engineering student I would very much enjoy to understand why there are so many leads if possible and maybe just a rough idea of the physical winding configuration. However simply confirming that I have a delta configuration is extremely helpful and I thank anyone that takes the time to offer their opinion.

Top view:

Bottom view:

zoomed in top view:

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Joined Jul 18, 2013
24,980
Delta is three windings connected in 'series' the junction point is each phase.
The rectifiers are typical for an alternator, press fit into the heat sink.
How are you going to provide excitation to the rotor?

LowQCab

Joined Nov 6, 2012
1,914
If You are converting this Alternator to a Motor, throw-away the Bridge-Rectifier/Diode-Pack.
If any of the wire-pairs were originally attached together, and soldered to a single terminal,
leave them connected together, do not try to change the Wiring.

When looking at the Stator-Laminations notice that there are distinct dividing gaps,
running longitudinally, that create "Poles",
these correspond to the "supposedly" "separate" Windings,
which alternate A-B-C-A-B-C-A-B-C.

To reverse direction of rotation, simply swap any 2 Coil connections.
( B-A-C-B-A-C-B-A-C )

The problem with using an Alternator for a Motor is that it was never designed to be a Motor.
The Rotor-Design is not very efficient when used as a Motor.
If You want to create a seriously powerful Motor,
You will need to completely re-design the Rotor,
and preferably replace the single Rotor-Winding with some powerful Permanent-Magnet(s).
A Rotor re-design will also allow the use of a Square-Wave-Input.
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Popper299

Joined Jan 12, 2022
4
Thank you very much, I have soldered wires to the ends of the brushes, my design right now will have the brushes re mounted and separately energized by another battery. I know this is not ideal and basically just a waste of energy.

I would love to separate the the top and bottom of the rotor, remove the copper wiring of the rotor, and replace it with a very strong permanent magnet. However, so far I haven't been able to find a suitable magnet that wouldn't require me to weld a circular plate onto the rotor shaft for the magnet to sit on.

I would love to do that, however I have never performed welding before. But, this is not something I am un-willing to learn. I basically took this project on knowing that it would require me to learn many new things, and that's exactly why I'm doing this in the first place

PS eventually if all goes well this alternator motor will be mounted onto a bicycle (will definitely require welding).

LowQCab

Joined Nov 6, 2012
1,914
Microwave-Ovens contain a circular Magnet that may work,
if You stack-up 3 of them.

An Alternator-Motor is EXTREMELY inefficient.
You would do much better to use ANY of the widely available Hub-Motors.
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pyroartist

Joined Oct 9, 2015
114
Wow, LowQCab, thanks for sharing your detailed knowledge of 3 phase car alternators and motors. To most engineers this remains a weak area of understanding.

LowQCab

Joined Nov 6, 2012
1,914
Look for a used Hover-Board to get the Brushless-3-Phase-Motors.
The already installed "Tires" on the Hover-Board-Motors can turn your wheels by direct friction,
with no belts or chains to mess with.

It doesn't matter if the Electronics are trashed,
they contain a bunch of special-Controls You don't need, and/or,
that You can't take advantage of without a ton of redesigning.
And, generic BLDC Motor-Driver-Boards are cheap, at about ~\$25.oo each.

Get a Board with the Highest-Amperage-Ratings that You can afford,
this will provide "some" insurance against smoking the Board.
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Popper299

Joined Jan 12, 2022
4
I will now keep an eye on used hover boards and see if i dont come across a good cheap BLDC motor some day!

LowQCab

Joined Nov 6, 2012
1,914
If You've got some time and gas to burn,
check your local Newspapers for Garage-Sales or Estate-Sales,
there will be at least 5 or 6 on every week-end,
you'll be amazed at what You can find for 5-Bucks.
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Janis59

Joined Aug 21, 2017
1,383
The system is extremely simple. Take the tester and mark all the 6 ends who is in resistance, thus obtaining three groups. Mark them by sticking the blue, yellow and red isolation tape piece.Then take a 1.5 AAA battery and shortly put between one of identic colour wires (for example yellow) and then de-attach. Before it mark the minus end with surplus black tape piece and plus with white. At the any of other colors, for example red, measure the voltage with analogue scale type of measure head. If the galvanometer jumps upside and then downside beyond the zero, then mark red coil with according white and black as polarity was shown. Then repeat it to green coil. For to be sure, turn the input be red or blue instead yellow and check do the polarity is still right. If any mistake happened, readjust the beginning and end marking of yellow coil. Thus - yellow black iz yellow beginning, yellow white is yellow end etc etc.