GoldenMotor.com Forum
General Category => General Discussions => Topic started by: Electrobent on November 20, 2009, 06:01:37 PM
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I visited my local friendly scientific instrument tech and he got out his LRC meter and measured the inductance of the three coils in my 20" 48V front Golden Motor Hub. The units are micro Henries (uH).
Between Green and Blue: 578 uH
Between Blue and Yellow: 550 uH
Between Green and Yellow: 705 uH
Does this make sense to anyone?
Thanks!
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No! IMO their is too much difference between the readings.
What model do you have?
Mine all test 850uh almost on the dot and mines is a Model: HBS36R. and its got 200 watts stamped om it.
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HBS48 with 1000W stamped on it.
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I think blue has a short in it or the winding is paired wrong.
Stop running this on your controller or it will be the next thing you have a problem with.
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can you please say more about what it means to be "paired wrong?"
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My motor I believe has 6 enamel windings together that run around the motor in a WYE configuration like this. You might have 8 per phase.
(http://www.ottawahomerepairs.com/theory_files/theoryy.gif)
To make what I am saying easier to understand.
What if we took one enamel wire input from G and one from B and swapped them and joined them to opposite parrallel phase groups
EG. 5 Blue wires paired with one Green wire and one blue wire paired with 5 green wires.
We then would have a reversed polarity winding going through both G aannd B iron cores and a reversed polarity winding running parallel to the series WYE to blue.
The reverse polarity windings over an iron core from my best guess would hammer down the inductance and give a little back through the series wye to blue.
But your test could indicate something a little more complex going on as the experience is shared on mixed phase wires to a varing degree.
So this pairing problem could be happening half way through the stator on any number of poles and corrected anywhere beteeen the start and the WYE convergence.
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I did not realize that the arms of the Y were broken.
There are three groups of 8 wires coming together to connect to the 3 phase wires in my motor.
So it sounds like maybe 2 groups of 4 are swapped.
So my inductance measurements are of 4 coils. Two in each arm connected through the center.
Two are low and one is high. So maybe the outer coils (in the Y arm) of the two low ones are swapped?
Mybe I can fix this with a soldering iron?
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... Two in each arm connected through the center. Two are low and one is high. So maybe the outer coils (in the Y arm) of the two low ones are swapped?
This is not how these motors are wound. As I tried to explain earlier (http://goldenmotor.com/SMF/index.php?topic=1218.0):
- The motor is star connected
- the bundled 8 wires are (0.54mm) strands of the same conductor
- The motor has 46P51S (poles and slots) and the winding pattern is AaABbBbcCcaAabBbBCcCAaAabBbcCcaAaABbBCcCcaAabBbcCcC
- The conductor for each phase is one 'arm of the WYE' and has no internal interruption/connection. All 8 strands are wrapped around the 17 teeth in one go.
maybe this illustrates it better http://www.youtube.com/watch?v=CabZEejbeKA
Thus I can't imagine that a phase winding is 'wrongly assembled'. But what can easily happen is that the varnish came off and part of the winding is shorted (winding to winding or winding to stator). This might show up in an unbalanced resistance or inductance (have you checked insulation/resistance between phases and stator?). I had the impression, however, that the induced voltages (back emf) of the 3 phases were quite equal (a sign of no winding shorts)? The firing pattern of the Hall elements does look ok but the phase voltages seem not perfectly symmetric.
I briefly watched your video. To me it looks like:
wrong timing or
single phase winding failure
If you have a Magic Controller (or some RC controller) available you could try it in sensorless mode to sort out the wrong timing issue. I would try this anyway to be sure the fault is not some other effect of your controller.
If the coils 'leak' , you better go for a new motor, its much cheaper then trying to rewind (probably GM replaces you the stator for free?).
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Would not a short from worn off varnish show up on a regular ohm meter between the coil and the stator?
Mine are wide open on all six accounts "0.L" on my digital multimeter.
What if a letter got skipped or upper and lower case switched in the process of winding the motor.
Explaining the three pretty sine waves I got when running it as a generator is tough--could it be generated in a correctly wound coil and just come back through the center tie point of the WYE?
And my conditions were not exactly scientific--I don't know that the RPMs were the same on the drill but I do know I did not mess with the knobs on the scope between shots.
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Would not a short from worn off varnish show up on a regular ohm meter between the coil and the stator?
If the winding was shorted against the stator it would show up, but if it was shorted against another part of its own coils, it would have a reduced resistance as the length of the winding/s bypassed by the short would be effectively removed from its overall length.
Alan
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but what would cause a coil to rub against another coil? It looks like they are wound pretty tight without room for flopping around.
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Im rewinding a motor today. I knew about the star wye and I had a post ready to go but I have this damed PC soft off next to my enter button and shut down the computer before I posted it. Its happened to me a few times. Ive removed the key now.
It looks worth rewinding them to me, as I have found motor winding copper for $30 a KG.
AaA BbBb cCc aAa bBbB CcC AaAa bBb cCc aAaA BbB CcCc aAa bBb cCcC
Is that correct?
The A stands for one direction turn and the a stands for the opposite?
I notice there is and big A and big B together and there is a one AaAa, aAaA BbBb, bBbB CcCc, a cCcC series strings in there. This seems odd but not from looking at the windings. I get lost as you can imagine and wil;l mark it as I go.
I'm ordering a sensorless controller today and wondering which is the best way to rewind this hub for the best results.
I can get any diameter copper. ATM my hub has 6 X .5mm strands wrapped around the cores with space left for another when added makes 3mm. I was thinking maybe I could use 7 strands and do the winding carefully or maybe 5 strand of .62.
Ive read that the thicker copper allow for more room on the poles.
But maybe thicker windings will be more difficult to wind or have less thermal disipation.
Any ideas as what I should do?
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G'day Leslie,
I found the following on ebikes.ca and I think it is relevant.
On the Crystalyte website, you'll see a large number of motors listed and characterized like 406, 408, 409, 4011. The last digits refer to the number of turns of copper around each stator pole. So for instance, a 406 has 6 turns, the 4011 has 11 turns.
The torque that is produced by one of these motors varies in direct proportion to the total current flowing around each pole. So in the above case, a 406 motor with 15 amps flowing through the winding has a total of 90 amps around the pole. The 409 motor would need just 10 amps to have 90 amps around the pole and hence the same torque output.
One false and oft-repeated conclusion is that therefor the 409 is a higher torque motor than the 406 because it can produce the same torque with fewer amps, or likewise more torque with the same amps. This is not the case. All 400 series motors can deliver exactly the same torque at exactly the same efficiency. The lower winding count motors just need more current to do this, but because they have fewer turns of a shorter length of heavier gauge wire, they can handle high currents with minimal loss. To use a concrete example, lets compare a 404 with a 408. The 408 has twice the number of turns than the 404, so the copper wire in the windings has 1/2 the cross sectional area and twice the length, for a total of 4 times the winding resistance of the 404. For a given torque output, the 408 needs only 1/2 the amps, but because it has 4 times the resistance the net electrical loss (I2R) is exactly the same.
Another consequence of having a larger number of turns around each stator is that the voltage induced in the winding by the passing magnets is increased in direct proportion to the number of turns. So for instance, at a certain speed of rotation, the 408 motor will produce twice the back-emf voltage as a 404 motor rotating at the same RPM. To power a motor, the battery pack voltage needs to be greater than the back-emf voltage, and so the 408 motor needs twice the voltage to spin at the same speed as a 404. However, it will only draw 1/2 the current, and you can see that the net power input (Volts * Amps) remains the same.
You have to decide if you want a speedy or torquey motor.
Muzza.au
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I have this damed PC soft off next to my enter button
I hate where the home key is on my work keyboard, I keep
hitting it when I mean to backspace.
I took a paperclip and bent it to fit under the key so it's more
springy than the adjacent keys.
I did the same thing for caps lock.
Now I can use them, but I have to really want to and hit them hard.
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Ok that was handy.
???
It reads same torque for all motors and says nothing about speed. I am guessing that it just a speed increase at the expense of efficiency and the lower turn motors run well on lower volts.
Because the wife has almost toasted this motor with shopping I think I will go for more turns and same thickness coil. I read somewhere if you can get the turns tighter you can get the same speed and more efficiency due to the higher inductance with the more turns.
The heat is what I am concerned about and I will settle for a few less KPH for a more efficient motor. The higher resistance should slow the current flow up somewhat and keep the heat down.
By using a rubber mallett I may be able to squeeze one more turn on this baby.
The controller I will be ordering be a 48v 1000 watter so I am also considering an extra parallel winding too.
What if one was to wind 6 tuns on the fist pole 5 turns on the second and four on the third pole?
Or would this make it run rough as hell?
Would this in effect give more grunt at the beginning of the firing and give more speed at the end?
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Here too they have a simulator based on inductance, it seem a little off with the speed and I need to really turn the volts down to match mine.
http://ebikes.ca/simulator/
The green line (efficiency) is whats important to me. The more turns the slower the motor, but the torque is higher at the slower speeds.
Thinking about it now I wont be able to fit another turn onto these poles and will just try to make it tighter and better.
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OK, I have a really stupid question:
How did you get the stator out of the hub?
When my 36V died and we tried to do an autopsy we could not get the stator out hub because the magnets were too strong.
We took both side panels off, rested it over a big enough hole and two of us pushed as hard as we could but could not push the stator out of the motor more than a 1/16th of inch or so.
Is there a trick?
I am going to have to know it if I am going to rewind the 48V motor which, at the rate Golden Motor is responding to my warranty claims, maybe the fastest way to get on the road again.
Now I am wishing I had not tossed that old 36V wheel into the recycle bin last month , , , ,
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(http://i29.photobucket.com/albums/c251/soulelectronique/push.jpg)
Put some good shoes and on and on a lounge or some padding in the area it will pop out and land, grab the magnet ring with both hands and push hard with your foot or both feet is better if you don't have clown feet.
It should land on something cosy about 3 feet from where you do it. Dont be scared, just go for it.
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Updated:
I gots an old crappy 12v battery out and hooked it up between where the 3 phase wires are soldered together and each phase input individually and hung a spoon end over the slots and tested them all.
I ended up with this WYE star configuration.
I drew this up because I am rewinding the motor sometime this week.
Almost done here.
(http://i29.photobucket.com/albums/c251/soulelectronique/HBSY-1.jpg)
One flavour could you do for me eclectrobent.
If you unwind the hub could you tell me how many turns are on each tooth of the 48v 1000 watt stator?
Thank you.
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I am still hoping to get some sort of warranty coverage here!
Maybe I can tell how many turns there are just from taking a side panel off?
But after looking at your diagram I am thinking that maybe a worker missed the clockwise-counterclockwise distinction for one coil.
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(http://i29.photobucket.com/albums/c251/soulelectronique/oct2009009.jpg)
I gots my high grade enamel copper and some off cut winding paper. $33 dollars so far.
The guys at HQ industrial windings have offered to dip this for $10 when I've finished
It very hard to get these windings off. Some drilling helps.
Once I broke the first winding I knew then there was no turning back.
As you can see the plastic core insulator around the outside of the slots is melted from overheating. I will remove this and replce it with the paper I got from HQ.
The grade of copper I got is rated above 180 deg and is darker in colour than the original copper. The copper on this hub is about 5 shades darker than it was when the hub was new due to the excess heat from overloading the hub.
I havent got a good count of the turns yet but last count was 5t6p on the HBS36. 30 strands surround each tooth. I will get a certain on this before I finish.
Id say the 48v 1000 watts have 4t8p. Im going to try for 5t7p as I want the power in the bottom end and a little bit less resistance if I can get the windings flat and ordered.
Ill see how I go.
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Oh dear I just finished removing the windings with a pile of utter destrucrion.
The stator made it through the hard knocks with two teeth split on the ends just a little and I should be able to fix it back.
My hands are sore.
I still didnt manage to get a proper count on the windings on the account there are half turns and what I had to do to pry these windings from their old home.
I counted 7 turns on one and possibly 8. Doing a test wind 8 is doable but 7 looks like the figure. Ill do one phase with 6 turns 7 parallel and test the inductance and if I get more than 400uh this should do the job anyway.
Be nice if Tom could jump on about now and give me an idea.
EB if you plan on doing this set aside a good day or two for the work in completion. Removing them is the hardest.
The more I took off it came exceedingly apparent the damage the heat had done to the outside insulation where they use plastic. 40% of this was melted away. The paper in between the coils and stator was still in good shape and in good faith GM should observe this for future builds as indeed the paper out performs the plastic by a good margin.
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The paper in between the coils and stator was still in good shape and in good faith GM should observe this for future builds as indeed the paper out performs the plastic by a good margin.
Leslie,
It might have something to do with a large metal stator, acting as a heat sink inside the windings, being considerably better at conducting and absorbing any excess heat than just air on the outer surfaces of the windings.
Alan
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The paper in between the coils and stator was still in good shape and in good faith GM should observe this for future builds as indeed the paper out performs the plastic by a good margin.
Leslie,
It might have something to do with a large metal stator, acting as a heat sink inside the windings, being considerably better at conducting and absorbing any excess heat than just air on the outer surfaces of the windings.
Alan
I'm not sure what you mean.
I see the stator getting very hot and the paper wrapped around the windings.
This is the result just the same.
Before and after shots.
(http://i29.photobucket.com/albums/c251/soulelectronique/compare-1.jpg)
This motor was pushed time and time again way past its intentional designed limits so in essence ive been very happy with it performance. It was still functional before I undressed her but as you can see it was on its way to the grave.
IMO paper in place of the plastic mouldings would still be an improvement on the already hardy design. I really wouldnt say what happened was due to a flaw in the design, not at all, I just I see room for better design.
GM should look at the data comming out of this work very closely because they will not find many GM motors that has been pushed so hard in such a way.
This damage has not been done by a 86v overvolt this has been done by sheer loading of weight by means of a trailer carrying lots of shopping.
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(http://i29.photobucket.com/albums/c251/soulelectronique/paper.jpg)
This is how I plan to tackle my problem.
Ive done a bit of restoration and removed the melted plastic stuff.
Another test wind with some lower temp WW4016 enamel magnet I have to experiment with and high temp winding paper cut into rectangles and folded into V's with with a 5mm nick in the middle to allow half flaps to overlap each other in the centre of each tooth.
(http://i29.photobucket.com/albums/c251/soulelectronique/paper2.jpg)
This is a 7p 8 turn wind with flat layered incrementing winding style from top to bottom on the first coil. I am contemplating doing a 8p 7t.
I have a 1kg of higher grade enamel wire for the real job. The guy I bought this off told me this redish enamel wire has a rating of 180 degrees 200 degree max. So I am looking at making a better hub than it was.
I want some feedback from a few members here before I do anything. This does need its own thread.
I shall succeed.
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I don't know if this is any help:
http://www.mtmscientific.com/rewind.html (http://www.mtmscientific.com/rewind.html)
I know it's an alternator, but the principal is the same.
I particulary liked this bit:
Hand winding a stator is not especially difficult, and it only requires a few hours effort
Alan
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Thanks. Good reading. 8)
Ive been trying to read up as much as I can about this in order to learn more. It would of been easier and I would advise most just to buy a new motor.
All of this has become a epic journey for me and I do enjoy the learning part of all this, not so much the work though.
Edit:
Ive started a thread on this as the topic subject is moving outside of coil inductance and EB's problem.
Here>>>>. http://goldenmotor.com/SMF/index.php?topic=1520.0