Wye did I do it?

[dontsendbubbamail]

Jermey Harris made me do it.

I decided to try a wye configuration on my 3KW motor so that the KV would be about the same as my 6Kw motor. This allows me to use just one jack shaft and to be able to switch motors without changing the gears.

Will this cause me a problem? As you can see, I broke a couple of wires while teasing the wires apart. It was a pain in the butt because there was a glue at the junctions where the wire were twisted together.

What is the best way to remove the varnish from the wires?

Bubba

[rkosiorek]

Jermey Harris made me do it.

<snip>

What is the best way to remove the varnish from the wires?[/b]

Bubba

heat it quickly with th hot end of a propane torch. not too much you want to charr the lacquer without heating a big chunk of wire. clean off the charred lacquer with a wire brush that has either copper or brass bristles. all wire brushes shed particles of the bristles. steel or stainless particles can infiltrate the copper and make it more difficult to solder later.

rick

[Jeremy Harris]

Sorry, Bubba..........................

Hope you fix it OK.

Jeremy

PS: I've done a couple now and they've both been OK, maybe I was just lucky.

[ron van sommeren]

... What is the best way to remove the varnish from the wires? ...

Use real Aspirin. First post, tip #27
http://www.rcgroups.com/forums/showthread.php?t=240993

Vriendelijke groeten Ron
• brushless motor building tips & tricks • diy brushless motor discussion group
• Drive Calculator download & discussion group • int. electric fly-in, Nijmegen, the Netherlands

[dontsendbubbamail]

Thanks for the help. OOPS!!! I did something wrong. I got it wired up in the wye configuration and gave it a try. It was running good on 12S for about 30 seconds. There was a spark and then that wonderful smell of burning wires. Now the motor turns with resistance, so something is shorted. Oh well shit happens.

I am just going to blame it on Jermey for making me do it.

Maybe I will try and rewire it. Where is a good place to get the multi-strand wire that Turginy uses?


Bubba

[ron van sommeren]

Single strand gives you a better copper fill factor.

[12p3phPMDC]

Sounds like fun......

So, the Kv is supposed to drop considerably,
130 to 70 perhaps?

[Miles]

130 to 70 perhaps?

130 to 75, I think.

[dontsendbubbamail]

This was my 3kw motor. It was 230kv to 131kv.

Bubba

[12p3phPMDC]

Is it a 12 pole stator?

What kind of winding pattern are you gonna try...?
(thanks to Ron for posting all the winding info!)

LRK (interesting variant, uses less wire, possible with 12p not 9) ?
Distributed LRK ?
Are you gonna copy the original winding?

[ron van sommeren]

... LRK (interesting variant, uses less wire ...

LRK was the original diy winding diagram introduced by Christian Lucas and Ludwich Retzbach in their ElektroModell magazine articles, back in 2000. It's easier to wind because you don't have to deal with neighbouring coils. dLRK uses less wire, due to the fact that the winding heads are smaller. But Kv is 10% higher.
Original EM articles at bottom of page, in English:
http://www.aerodesign.de/peter/2001/LRK ... x_eng.html

... LRK ... possible with 12p not 9) ? ...

For SPS/LRK you need on even number of statorpoles:
http://www.aerodesign.de/peter/2001/LRK ... oclaw.html

Motor_rewinding_101
http://www.gobrushless.com
-> knowledge base
-> basic overview (1-5)

Tips and tricks, checks and tests, may keep you from frying yer ESC and/our controller:
http://www.rcgroups.com/forums/showthread.php?t=240993

... So, the Kv is supposed to drop considerably ...

By a factor 1.8. If the powersignals were sinusoidal- instead of trapezoidal-shaped, the drop would be sqrt(3)=tan(60).

[dontsendbubbamail]

Is it a 12 pole stator?

What kind of winding pattern are you gonna try...?
(thanks to Ron for posting all the winding info!)

LRK (interesting variant, uses less wire, possible with 12p not 9) ?
Distributed LRK ?
Are you gonna copy the original winding?

I would copy the existing winding, but for now I think I will put this project last in line. My hxt 80-100 is still going strong, so I will use it for build 3. Build 4 will be creating a lighter setup, assuming I like build 3. The smaller motor will save me almost 2 pounds over the hxt 80-100 and still should have all the power I need.

Bubba

[12p3phPMDC]

Ron,

Thanks for the correction re: LRK and dLRK.
Lots of reading to do!!


Bubba,
It'll be interesting to see what the current winding style is when the time comes.

[ron van sommeren]

... Where is a good place to get the multi-strand wire that Turginy uses? ...

http://www.mwswire.com/
http://www.planetengineers.com/

Mind you, multistranded wire is easier to wind but gives a lower copper fill-factor. If wire gets to thick to handle comfortably, I'd go for 2-3 wires in parallel, but not multistranded (=litze) wire. See
translate.google.com...www.aerodesign.de/peter/2001/LRK350/Skin-Effekt.html
and
http://www.powercroco.de -> English
-> theory
-> Solid or stranded?

[dontsendbubbamail]

The more I read the more I want to rewind the motor. Ron, thanks for all the links.

Bubba

[ron van sommeren]

... LRK was the original diy winding diagram introduced by Christian Lucas and Ludwich Retzbach in their ElektroModell magazine articles...

Christian Lucas, the 'L' in LRK, earns his money working on 'slightly' larger motor designs at www.magnet-motor.de (English).
Ludwich Retzbach, the 'R' in LRK, an EE too, is a renowned German e-flight author, www.elektromodellflugpraxis.de

Vriendelijke groeten Ron
• brushless motor building tips & tricks • diy brushless motor discussion group • int. electric fly-in, Nijmegen, the Netherlands

[ron van sommeren]

The more I read the more I want to rewind the motor ...

Hook, line and sinker I'm pure evil


Vriendelijke groeten Ron
• brushless motor building tips & tricks • diy brushless motor discussion group • int. electric fly-in, Nijmegen, the Netherlands

[GGoodrum]

Holy crap, that's a big-ass motor! I'm sure Luke is already trying to figure out how he can mount two of these on something...

[Miles]

Holy crap, that's a big-ass motor! I'm sure Luke is already trying to figure out how he can mount two of these.....

[ron van sommeren]

Single strand gives you a better copper fill factor.

Which leads to higher efficiency

Higher efficiency does not only mean that the motor makes better use of the batteries' power, it also means the motor is able to handle a higher power input before hitting its maximum temperature mark i.e. a the power/weight ratio will be higher.

An example:
Say the motor has an efficiency of 70% and it can handle 500Watt input. That means it can get rid off 30%*500=150Watt excess heat. Now, by cramming in thicker wire (and/or using better stator-iron, segmented magnets), efficiency increases to say 75% (I'm a bit optimistic here). The motor's ability to loose those 150Watts has not changed (by radiation, convection and conduction). This means the motor now can handle 600Watt before it hits the 150Watt (25%*600Watt) losses mark. An efficiency increase of 5% gives an increase in the power to weight ratio of 20% (from 500Watt to 600Watt). That's why efficiency plays such an important role, in any motor design: efficiency governs maximum power. The motors weight may have increased a bit due to more copper.

If you increase efficiency of a 80% efficient motor to 90%, specific power would increase by factor 2, i.e. 100%more.

[rkosiorek]

... What is the best way to remove the varnish from the wires? ...

Use real Aspirin. First post, tip #27
http://www.rcgroups.com/forums/showthread.php?t=240993

Vriendelijke groeten Ron
• brushless motor building tips & tricks • diy brushless motor discussion group
• Drive Calculator download & discussion group • int. electric fly-in, Nijmegen, the Netherlands

thanks for the tip ron. tried it toay ant it works great. now i don't need to haul out the propane torch.

i had to re-do the leads on a motor and a big 48V CT. 8A transformer. and i decided to try out the aspirin. i first used up my last 2 pils of name brand stuff. having a few more leads to do i used up some really cheap no-name stuff from a discount store. and it worked even better. less smelly smoke and less residue to clean up.

later i mentioned this to the pharmasist and he was not surprised. according to him the cheap stuff has a higher concentration of the active acid and fewer fillers and buffers.

rick

[dontsendbubbamail]

As I sit here dead in the water with all my controllers blown and waiting for the new stuff to arrive, I decided to take apart my dead HXT 80-85. This one is the newer design that has the large bearing supporting the front of the bell. It was cooked when I blew my last CC controller.

I wanted to try to tease apart the winding leads so that I could practice rewiring it in the wye configuration. Getting the motor apart was not hard. Once you get the large support bearing for the bell off, you are left with the bearing tube assembly and the stator. This seems to be held together with the same glue that was used for the magnets. The good and bad news is that they didn't spare the glue. It was all over the wires and that is no way they could be seperated and rewired as a wye.

Now my thought was that maybe I could rewind the motor. Getting the wire off was not too bad. Except for the fact that some of that glue was holding the wire to the stator and I bent up a couple of the top stator plates while pulling the wire out. I put the stator and bearing tube assembly in the oven and heated it to about 220 F, but could not separate the two. It may not be necessary to separate the two as this design has more space to work with on the motor mount end.

Bubba

[etard]

Hey Bubba, you got any pics of that motor teardown, or at least of the empty parts? I am interested to know this. It seems if the process is not too complicated and parts are easy enough to find, then it would be cool to always have a spare bolt on motor, in case one gets fried. Heck it might be wise to have an extra controller on you ( even a cheap one) the are so light and small. But if your batteries go, might as well call it a day.

[dontsendbubbamail]

Here be the pics.

Bubba

1-motor.jpg (181.01 KiB) Viewed 1084 times

1-magnets.jpg (170.35 KiB) Viewed 1083 times

1-stator2.jpg (118.02 KiB) Viewed 1084 times

1-stator.jpg

(97.08 KiB) Downloaded 515 times

1-winding.jpg (107.15 KiB) Viewed 1081 times

[etard]

Dang, ask and ye shall receive. Thanks man.

Wind it up dog!! That motor could be an opportunity to make it better. I wonder how much a rebuild costs, also wonder if you could try to wind it for a lower KV. Put some nice bearings in there and your back in biznass!