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Electric Motors Winding and Repair Electric Motors Winding and Repair Discussion


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Old 11-27-2015, 10:36 AM   #1 (permalink)
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Default Coaxial contrarotating, with custom made laminations

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Custom motor - RCG

Pictures are the old system, drawings the new system.

Prettig weekend Ron
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Old 11-27-2015, 11:30 AM   #2 (permalink)
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http://www.rcgroups.com/forums/showa...0&d=1446936286

the simulation is really nice.

but why he doesn't use his own calculations / results?

the magnetic circuit is imo very imbalanced.
backiron is the total bottleneck (zones with 2,4T), and at the same time the inner ring is almost the double of the real needs for flux!
the hammerstalks get max. 1,7T.
this is okay for "normal" stator sheetmaterial.
but in the root of hammerhead he gets sometimes 2,1T = oversaturated zones.
means, the form of hammerheads is not optimized.

only my remarks....
okay, may be, he has other intentions than a balanced magnetic circuit?
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Last edited by powercroco; 11-27-2015 at 03:50 PM.. Reason: direkt link added
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Old 11-27-2015, 07:15 PM   #3 (permalink)
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Thanks for you response:
I am a novice in design so I am struggling to make sense of this .
The back iron max is 2.3T and rotor max is 1.9T. Per Emotor's recommendations is to keep Tesla's around 2T. There are peaks of 1.9T in the hammerhead but the stocks are around 1.7T. The back iron maybe to thin and can go thicker if necessary. I do not know the consequences of having the flux density in the back iron at 2.3T. Does this have more to do with heat generated causing lower efficiency?
Simulation shows that I am at 93.41% efficiency already.
I am not looking for a motor that will work for this application and not to concerned about max efficiency.
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Old 11-27-2015, 08:48 PM   #4 (permalink)
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Opps: Cannot edit. The corrected sentence:
I am looking for a motor that will work for this application and not to concerned about max efficiency.
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Old 11-28-2015, 04:11 AM   #5 (permalink)
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the motor will work as it is for sure!

the normal way of further optimization would be, to add material where the flux is to high and to remove it, where the flux is very low.

but this is only the iron side.

as more material someone could remove without getting oversaturation, he could use the additional winding room for more copper and decrease the internal resistance of winding.
this will reduce the produced heat and give higher possible power by decreased copper losses.

btw. be sure, you never will reach the calculated efficiency in real life.
the toleranced in building and in material number will cost some percents.
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Last edited by powercroco; 11-28-2015 at 10:50 AM..
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Old 11-28-2015, 12:21 PM   #6 (permalink)
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Quote:
Originally Posted by p901p901 View Post
... I am not looking for a motor that will work for this application and not to concerned about max efficiency.
See
Efficiency governs power

Prettig weekend Ron
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Old 12-01-2015, 11:55 AM   #7 (permalink)
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More contrarotating coaxial designs, small and bigger:
contra rotating prop brushless - RCG

Vriendelijke groeten Ron
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Old 12-05-2015, 03:36 PM   #8 (permalink)
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The teeth was beveled and wrapped with 410 nomex tape.Still need more work on the edges to prevent damaging the wires.
The first test wrap was with 8 turns of 14 gauge. It was difficult to wrap tightly so I went with 16 gauge wire. Do not know if I should try parallel wires to fill the slot.

http://www.rcgroups.com/forums/showp...4&postcount=58
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Old 12-06-2015, 03:57 PM   #9 (permalink)
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you should use fiberglass endplates as we do1

and also have a look into the "tools" sticky.

one thick single wire will give you the better fcopperfilling in every case.
no ngative effects up to 1,8mm thickness of wire.
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Old 12-09-2015, 12:14 PM   #10 (permalink)
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Hi ,
If you use 2 or 3 wire parallel it is possible that you can wind them and the small benifit of the single big wire that you can't wind will butt kick the stress how to do . So you make nothing wrong by wind with 2 or 3 parallel . You can take different dia for the parallel wire to make them fit in the slot and to fill gaps that can not fill by a big singel strand .And if you can rise the volts of your system you will be the winner . Double volts need double turn of winds and half square of the wire to get the same result . Like one 1,5 dia wire you can than use a 1,06 dia wire . Much easyer to wind ,half amp draw samller esc and less loss in the wire and connectors if you want not the big size connectors you need a deconnect tool to hanlde them .
Just my two cent .
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Old 12-18-2015, 01:10 PM   #11 (permalink)
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Here a scorpion HKIII 4035 3+3 YY that I wound with dual stranding for 10 s lipo in a special app. Here is the motor and the measured constants thereof.











Scorpion 4035 HKIII
Kv 1190 on castle Ice HV v2
Io 4.4 amps @ 22.5 volts
Rm .008 ohms
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Old 12-18-2015, 02:05 PM   #12 (permalink)
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Here is a HK 5020 (clearance sell 130 bucks new) that may receive dual or tri strands and be rewound for 400 kv.
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Old 12-20-2015, 03:15 AM   #13 (permalink)
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lets have a test and try to discuss again....


every YY winding is in fact a 2-stranded Y-winding, only built on different teeth.

about win or loss in copperfilling with more strand winding decides the "geometrical factor".

for windings with more than 1,8mm wire in (in model motor size) it will give a benefit in caused losses against the pssible win by more coppersquare.

in 12N10P or 14P we found, the jump between the 2 teeth made with 2 wires will waste more room than doing it with only one with more diameter.

more strands will make the cooling more difficult, because of you will have more layers at the end.
This can cause that some copperwires with will have no contact anymore with the statoriron or to air.

many very thin strands will make the winders live easier - thatswhy the cheap motors are made in this way.

regarding these facts, the described more strand winding is a good help for unexperienced winders of course and it will also give a benefit in special cases against monostarnd winding!
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Old 12-22-2015, 04:34 PM   #14 (permalink)
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Quote:
Originally Posted by Ch.Lucas View Post
Hi ,
If you use 2 or 3 wire parallel it is possible that you can wind them and the small benifit of the single big wire that you can't wind will butt kick the stress how to do . So you make nothing wrong by wind with 2 or 3 parallel . You can take different dia for the parallel wire to make them fit in the slot and to fill gaps that can not fill by a big singel strand .And if you can rise the volts of your system you will be the winner . Double volts need double turn of winds and half square of the wire to get the same result . Like one 1,5 dia wire you can than use a 1,06 dia wire . Much easyer to wind ,half amp draw samller esc and less loss in the wire and connectors if you want not the big size connectors you need a deconnect tool to hanlde them .
Just my two cent .
I ran two strands of 17 ga. on each wye motor so my each terminal bundle has 4 17ga. strands...... now. With multi strands that multi strand still double same as mono in the YY . In this experience with multi stranding It was actually more difficult to lay perfectly and stay in place neatly than a larger mono wire, which isnt much much more difficult to wind IME once the hands got used to the pulling and the pain from fatigue subsided.


Then..
Here is 6 + 6 LRK turns on a 4030 stator in 1.9....something mm.It could easily fit 7 turns as you can see in the photo would be the same amount of copper a 3 + 4 DLRK YY in 1.9...something mm. but the kv would be all wrong for my app. So this is actually a dual strand of 1.9mm wound wye on different teeth.

Cake after practice.

Some high dollar motors use thermally conductive epoxy to secure their multi strand windings which help dissipate heat. If that is a concern.
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Old 12-22-2015, 10:32 PM   #15 (permalink)
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Another photo.
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Old 12-22-2015, 11:08 PM   #16 (permalink)
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"Well machining the flux ring with DOM is difficult. It seems the process Direct Over Mandrell Causes the outside surface to harden making the surface very difficult to cut. I was getting 0.003" cuts with alot of chattering. The inside was much easier to cut but still was getting only 0.003" cuts. Lathe speed was 300 rpm at .0035"/rev.
The processing of this DOM is drawn over mandrels which makes this material very dense. I do not know exactly if this is good or bad for magnetic flux. So I am abandoning this material and going with some Scheduled 80 black iron pipe. This will have a weld seam so I may get some uneven flux distribution in this area. I am trying for a 3.05" ID and 3.25" OD ring. The scheduled 80 iron pipe is 3.5" OD and 2.9" ID.
Read some postings https://groups.yahoo.com/neo/groups/...=1&viscount=50 on thickness of the flux ring. They say the ring should be 1/2 thickness of the magnets. I am using 0.1" thick magnets so per their requirements I should be using 0.050" thick ring. But my simulations shows the ring needs to be the same thickness as the magnets to bring the Tesla rating down near 2T. Would like to use thinner material for weight savings but those T numbers around 4 got me. With such a thin flux ring I would like like to see Turnigy T numbers with N42 magnets. Need to look up the large Scorpions on their flux ring size in comparison with their magnets. Could the simulations be wrong? Still have to investigate magnetic properties of materials used for flux rings.
The end bell is coming out allot better. Sure like cutting aluminum than that A519 D"

I think you should use some type of low carbon steel bar stock which should actually be rather easy to turn od's and id's. I will experience this in a few weeks. Maybe more information will come later about high speed bells etc. Ive been pondering some type of fixture to use a broach and a rotary table to cut key ways for the magnets. There also CNC milling of course. What type of lathe are you turning on? Prolly better make sure there is no taper in the cut before turning these pieces. Depending on the air gap you're goin for any taper may cause you some serious headache from one end to the other.

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Old 12-23-2015, 01:44 AM   #17 (permalink)
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I am using a 3/4 hp 8" x 16" bench top lathe to do the work. That DOM material is very difficult to cut on the OD probably because of the hardening from the process. The material I got was ASTM A513 alloys 1020 - 1026 Mild (low-carbon) steel. This pipe had a 3.5" OD and 2.75" ID and needed to be machined to 3.25" OD and 3.05" ID.
I really dread machining down a 1.5" thick 3.25" steel disc into a 1.5" thick 0.1" steel ring. I do not have a turntable on my mill and would have to hole saw or turn down the inside on the lathe.
Still planning on using the 14 gauge 8 turns wire for this. Do not know exactly the turns I need so I am doing the generator test with 20 gauge wire. I would like to eventually run this motor on 20 volts and around 80 amps. But that could change.
Edit text. The next ring will be made from some scheduled 80 3" black seamless steel pipe with a 3.5" OD and 2.9" ID. Got confused on the 0.25% MAX carbon content being a low carbon steel. Attached is the specs of this material.
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Old 12-23-2015, 02:25 AM   #18 (permalink)
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Let us know how that works. If you think it was work hardened from extrusion you could have annealed the AISI1020 at 1600F. Then machine it. Also at the diameter u may have needed to play with the rpm and feed and make sure the tool is sharp. Ill have to refer to the handbook but im sure there is a formula for getting in the ball park as well as a recommended base speed and feed for turning AISI 1020 which in bar stock is easy as pie. When I find it I will post it.

Alot of wasted material but boring through bar stock with a large endmill in the tail stock then finish the Id with a boring tool. If you have a DRO it should not be that big of a deal to be quite honest. When u are cutting it right you should get some nice blue chips...

Some I produced cutting a large mandrel for some head operations on a 2 stroke IC engine.Fairly deep passes if I recall between 600-900 rpm I'm thinking not 100 percent as its been awhile.


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Old 12-23-2015, 01:25 PM   #19 (permalink)
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I dont know what you are currently using but U can download a trial of Motorsolv analytical software from Infolytical.
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Old 12-23-2015, 01:33 PM   #20 (permalink)
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Before I finish the last arm I compare weight. This original 4025HKIIII 1100 Kv weight of the stator with copper coils on the carrier was 170.8 grams. The weight so far without the carrier and 1 less arm wrapped is 181.1 grams. The carrier is 20 grams so 201.1 grams total so far.
Speculate.....does it mean have I achieved a bit more copper than stock while gaining the needed Kv for my app with 3 strands of 17ga. In parallel 3 tooth motors. So I will have actually have 6 strands of 17Ga. Just wound on different teeth.
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