ES DIY Motor Challenge

[Miles]

Other than a CA to see whats happening when i ride and sending one to thud (still not kidding T) i consider the best "test" to be real world. bolt it to a bike ride and see what happens. bench testing only tells you what happens on the bench not to say i wont bench test BUT how fragile is it ? 98.9 percent efficient and 20Nm per pound is great and all but what if the first bump in the road or the kick stand melting through ashphalt tips the bike and the motor bends ? wheres your efficiency then huh ?

That's why I added the "practical" clause....

How about:

Over 4Nm continuous torque per kg of motor weight.

Less than 3kg in weight.

No energy input other than that to the motor itself.

Capable of practical use on an electric bike.

 

[enoob]

looky there . missed that addition .

4 sentence rule book.

perfect.

 

[MitchJi]

Hi,

I'd eliminate all the rules. Everyone builds what they want and gets judged accordingly (kind of like pornography "I can't define it but I know it when I see it". The results could be something like:

• Outstanding!
  Excellent
  Good
  Poor
  Failure

If one persons criteria are a cheap, simple DIY motor they get judged by how well their motor meets their criteria.

If Luke's criteria is under 4kg and under $4k cost with a power output of 10kw he gets judged accordingly.

If one motor is clearly more outstanding than all the others they could qualify for something like a "Best in Show".

 

[Miles]

If one motor is clearly more outstanding than all the others they could qualify for something like a "Best in Show".

So, how is it clearly outstanding? Because it looks cool?

Everybody is free to build whatever they want and invite comment on the forum, anyway..... I think I'd rather just do that than take part in a "dog show"

 

[adrian_sm]

Good work Thud

I am building a dyno.
....
I am thinking an infra-red thermometer might be a nice add on to keep from smoking a motor on the dyno.

Here is a couple of options for cheap infra-red thermometers in case your interested.
$47 - Digital InfraRed Thermometer with Laser Sight (-25'C~600'C/-13'F~1112'F)
$31 - Digital InfraRed Thermometer with Laser Sight (-32'C~380'C/26'F~716'F)
$25 - Mini Digital InfraRed Thermometer with Laser Sight (-50'~260'C/-58'F~500'F)

Hope this helps,
Adrian

 

[Miles]

I am thinking an infra-red thermometer might be a nice add on to keep from smoking a motor on the dyno.

This is something which needs working out, for sure.

Maybe a thermal sensor in the windings would be better?

Do we have a fixed maximum temperature? Which would have to be low....
Or, do we let the builder specify the maximum temperature?

 

[John in CR]

If one motor is clearly more outstanding than all the others they could qualify for something like a "Best in Show".

So, how is it clearly outstanding? Because it looks cool?

Since these are torque machines, then the highest torque density under continuous operation should win. The best idea to me was ES against all other groups so we can open source the build or several builds. It's that sharing aspect that make ES heads and shoulders above the rest. With tens of millions put on the road every year in China, the number working on the technical aspects of ebikes must number in the thousands, yet the open source approach is missing. Look at the result...pretty much crap and moderately efficient efficient machines with no good answer for multi-gearing and of questionable durability. I'm sure a number of posters here can do better going at it alone, but working together we can take a big step forward. To help satisfy the competitive need, how about top contributor and top builder awards?

Along the idea of an open source approach I'll pledge the purchase of one of the magnet sets, including shipping to whoever the group designates.

John

 

[Miles]

Since these are torque machines, then the highest torque density under continuous operation should win.

Then we have to wait until "everybody" finishes? Or what, a relay?

I still like the idea of a target to beat, myself..

 

[Thud]

Adrian,
Thanks, i am checking into it.

Regarding temps I guess I just want to see if the motor is really straining, if an eponential trend shows damaging heat iminent (temp ratings for the magnets) we'll shut it down. I was thinking non contact for ease.
I am also assuming that the builders will have plenty of bench runs on a submital before tourtureing their baby on a dyno

I have no issues with any of the parameters of this challenge & am trying not to dwell on the word "Win". As much as I would like to build the highest, tourqueiest, shinyest, gooderest motor this side of eternity, I still will have to give a bunch of credit to the forum as I suspect any one who participates will. I am thingking I have already won a huge prize just being able to contribute anything. If we happen onto an applicable design that will benifit the comunity here & abroad then the aknowledgmet will be enough. (untill the Nobel prize commitee calls :lol: )
The Kudo's are just frosting on the cake. & again the target will allways be moving. (next motor should allways be better shouldn't it?)

 

[Miles]

I was thinking non contact for ease.

I was thinking: the builder adds a thermal sensor to the windings during construction, so you just have to plug it in. Just an idea.

 

[adrian_sm]

I was thinking: the builder adds a thermal sensor to the windings during construction, so you just have to plug it in. Just an idea.

Then maybe one of these... $28 - K-Type Digital Industrial Thermometer with Sensor (-50-C ~ 1300-C)

 

[enoob]

I was thinking: the builder adds a thermal sensor to the windings during construction, so you just have to plug it in. Just an idea.

Then maybe one of these... $28 - K-Type Digital Industrial Thermometer with Sensor (-50-C ~ 1300-C)

oooh me likey that . gotta be a way to integrate that into a motor for over temp current shutdown ? or possibly to activate forced air cooling ? gonna have to see about extra sensors


ive got one of these from my nitro rc days . been using it to take the temps of the boys rather than sticking something in their butt. been working great for years.
http://www.dealextreme.com/details.dx/sku.29081

 

[Miles]

I was thinking: the builder adds a thermal sensor to the windings during construction, so you just have to plug it in. Just an idea.

Then maybe one of these... $28 - K-Type Digital Industrial Thermometer with Sensor (-50-C ~ 1300-C)

You could also use the Eagle Tree eLogger..

 

[John in CR]

ok ok ok. Whatever the rules, guidelines, whatever, I'm game despite probability of middle of the road outcome. I just want to build a useful motor and would appreciate some hand holding. With stuff like as much copper as will fit as guidelines and not a clue as to how the firing sequence or coil layout of the most advanced motors with the overlapping coils work, this stuff is daunting to us noobs. Sure we can build a motor that works, but that's not the point. A bit of hand holding and guidance from you guys like Mile, LFP, Fechter, etc. will go a long way. Some of us hackers may not come up with the best motor by a long shot, but we might have a useful idea or two that contributes toward an optimum.

 

[Thud]

I am with you John,
I feel like I am in the deep end of the pool at times. The only thing I am confident of is the actual building the thing. If it actualy works will be a thrill, & if it makes Miles threasholds I will be jubilant.

Did you check out the links to the go brushless knowledge base? They have some great animations showing a "fireing order" of a typical motor. Once that sinks in, it gets easyer to imagine the sequence using different termination set ups (delta-Wye). as far as, "as much copper as you can get in there"....that is the best description I have heard. Smaller motors are at the disadvantage in that regard.(thanks MR obvious!) but really if you have any questions there is a ton of brain power here & there is a miriad of links to tech stuff in the axial flux discusion thread & some more in the mule1.1 thread(& a bunch of duplication) I am out to the foundry to cast some rotor bodies for the mule.

 

[Miles]

Useful stuff: http://www.bavaria-direct.co.za/models/motor_info.htm Mostly related to RF outrunners, though.

 

[HAL9000v2.0]

...
No energy input other than that to the motor itself.
...

What if there is few coils just for "intertnal needs"?

I guess we need a separate class....

How will you get decent efficiency without magnets?

http://endless-sphere.com/forums/viewtopic.php?p=63234#p63234

This w/o magnets and 6 phases.

 

[Miles]

Field coil is ok, because it will lower the efficiency...

 

[HAL9000v2.0]

I was thinking like this: thre phases are trensfer phases to induce magnetic field in other three phases in rotor and to react with other three phases in stator. The rotor can then be ultra light and I plan to use only 1/4th of the dia for stator coils. So basicly I can have only "thicker rim"

I know I am in "hub" class with this design that is why I did not get involved here.

 

[John in CR]

Could it make any sense to have both PMs and coils in the rotor in order to get the cruising efficiency of BLDC with enhanced low speed torque by activating the field coils when needed?

 

[HAL9000v2.0]

I want to avoid magnets so the part of rotor/rim that is outside of "stator" is not magnetic and can't pick up nails and stuff..

 

[jscoot]

John,

Like I said, larger motors do have an advantage. That's the reason for the kg limit. This is the non-hub motor forum :wink:

0.kg to kg should be the range that most people want to work within?

Unless some people realize they can get a much more Kw per $ in a ready made
package that will work efficiently from 100 watts to 5 Kw and weigh about 5 kg.
Besides 3 hall sensors, and controller a complete motor can be purchased for about $200. in a action or $329.95 Complete with 14 N-42-H
magnets on a balanced rotor ans a slection of stator windings to choose your Kv. A high torque motor of this type will also reduce the amount of reduction needed and will enhance over all efficiency without any expenses or losses in multi reduction chains, gears or multi speed hubs.


http://cgi.ebay.com/PMA-12-350VDC-P...emQQptZLH_DefaultDomain_0?hash=item414a8333f4

 

[liveforphysics]

John,

Like I said, larger motors do have an advantage. That's the reason for the 3kg limit. This is the non-hub motor forum :wink:

0.5kg to 3kg should be the range that most people want to work within?

Unless some people realize they can get a much more Kw per $ in a ready made
package that will work efficiently from 100 watts to 5 Kw and weigh about 5 kg.
Besides 3 hall sensors, and controller a complete motor can be purchased for about $200. Complete with 14 N-42-H
magnets on a balanced rotor.

Are you showing a picture of an alternator rotor PM retrofit kit? Don't those struggle to make 80% efficiency over about 1kw?

 

[jscoot]

John,

Like I said, larger motors do have an advantage. That's the reason for the 3kg limit. This is the non-hub motor forum :wink:

0.5kg to 3kg should be the range that most people want to work within?

Unless some people realize they can get a much more Kw per $ in a ready made
package that will work efficiently from 100 watts to 5 Kw and weigh about 5 kg.
Besides 3 hall sensors, and controller a complete motor can be purchased for about $200. Complete with 14 N-42-H
magnets on a balanced rotor.

Are you showing a picture of an alternator rotor PM retrofit kit? Don't those struggle to make 80% efficiency over about 1kw?

A little better efficiency than Miles motor (I designed) without adding internal gears. Just a 7 to 1 ratio 219 chain drive. Not a hub motor. The od of the rotor is about 1/8" larger than the one in Miles motor but each magnet pole is about 10 times the strength with two more poles.

 

[liveforphysics]

This motor uses an alternator stator right? Thick laminations made of poor quality steel, poor copper fill, lam shape designed around minimizing cost rather than performance, etc etc.

Or do you have something unique and special here?