ES DIY Motor Challenge

[enoob]

laughable draper.

see a constructive way to point out the flaw in my reasoning would have been to ask how we compensate for the fact that the other motors are measuring torque at the shaft and his design would have some advantage due to the diameter of the wheel used.

but keep posting, im rather sure im not the one losing respect with every post.

 

[amberwolf]

How about using a bench supply instead of batteries? It would allow more flexibility with regard to voltages.

However, a bench supply that can dole out high currents at higher voltages can get expensive, and large.

My Sorenson 60V variable bench supply only goes up to 1.5A (1.8A, really), and it weighs almost as much as a good chunk of my SLA battery pack. However, it is a linear supply, rather than switching, so a switching supply could probably do a better job at a smaller size, but probably at a higher cost/complexity.

I have a 5VDC 200A supply holding part of the house down somewhere, and again it's linear but it weighs almost as much as my whole CrazyBike2.

I have a Lambda switching supply that's 15V 24A, and only about 5 or 6 pounds.

For my motor and controller testing, unless I am limiting current for first-stage tests or troubleshooting, I use an SLA battery pack just so I can pull whatever current I need to.

 

[liveforphysics]

I absolutely want to supply my own controller setup for optimized field timing to work with my motor.

I will make it fool-proof with a big red and black cable lug, and a throttle knob sitting on top. The controller wont smoke, but if it did, that would be a motor/system failure in my eyes, and I would accept that as a DNF.

30mins of continous operation would certianly long enough to bring these lightweight motors into thermal equilibrium. If they live for 30mins, they would live continously until bearing failure.

I can send Thud my regulated power supplies to use. Each is isolated, and rated for 26.5amps between 41v-52v. This means you can either have a 53amp supply between 41-52v, or a 26.5amp supply between 82-104v depending if you connect them in P or S. This would only give 2.6kw at best though, which is a wimpy 0.87kw/Kg for motor power density. We need more power than that, but it's going to require a 220v power supply, or batteries.

 

[jscoot]

Suppose a motor can withstand the torque tests without frying, then whal loaded RPMs would be considered useful for ebike use?

 

[enoob]

Suppose a motor can withstand the torque tests without frying, then whal loaded RPMs would be considered useful for ebike use?

i dont recall a loaded rpm # as a requirement to meet the challenge.

add to that i personally wont be concerned if i have to suffer the inefficiency of multiple stages of reduction and high rpm should that prove itself to get me to the beer store faster.

of course id like a motor that made 8kw and ran cool at 100rpm but in the end ill take what works best FOR ME . not what works best for you.

 

[Miles]

Suppose a motor can withstand the torque tests without frying, then whal loaded RPMs would be considered useful for ebike use?

Either around 1800 rpm or around 7000 rpm, I'd say.

Crikey! 4000th post...........

 

[jscoot]

Suppose a motor can withstand the torque tests without frying, then whal loaded RPMs would be considered useful for ebike use?

i dont recall a loaded rpm # as a requirement to meet the challenge.

add to that i personally wont be concerned if i have to suffer the inefficiency of multiple stages of reduction and high rpm should that prove itself to get me to the beer store faster.

of course id like a motor that made 8kw and ran cool at 100rpm but in the end ill take what works best FOR ME . not what works best for you.

Example: A Astro Model 3210 Brushless Motor weights 0.96 kg . It can deliver 2.647 nm of continuous torque at 7,500 rpm at 90% efficiency using 2100 watts At 7500 rpm. Adding a 3 nm load the power will go up as the efficiency goes down and the motor will start to get hot running out of the continuous rating zone. With vents and or cooling fans the stator and magnets it may survive the test, but may not last too long using it often under extreme conditions. Yes with a 18 to 1 reduction it would work on a ebike to produce plenty torque and speed by adding increased reduction weight.
Airplane motors are designed to operate for short times above 7500 rpm with prop wash ail cooling in a enclosed can and won't get much larger in diameter. The problem in finding high torque density motors for ebikes is not too many motor manufactures make 5' diameter motors up to 3" wide that have light weight, well vented cases and rotors while retaining strong magnets with a core backing.
To put all the RC Airplane motor parts into a new ebike motor design to eliminate as much reduction as possible without reducing motor efficiency is a goal I think we all are looking for.
After thinking about the rules of this motor challenge the more I wonder what it will accomplish ? To me torque density to the competition rules can already be accomplished in RC airplane motors. This does not mean that a slightly less torque density is not a much better all round ebike motor. Getting smaller, higher torque motors will only come at a high price that can not be avoided. The torque density Challenge can be met with Miles motor along with decent efficiency,size and shape. The efficiency, power and torque density of his design can easily be improved upon with minimal changes in costs.
What works for you or I is not as important as what Other Ebikers can enjoy at a decent price to build or eventually buy.

 

[Ypedal]

Randy, this thread is what it is, if you can't wrap your mind around it and contribute, read and stay away from the reply button. only post i'll make on this, you know how it goes from here.

 

[Miles]

Randy,

Neither an Astro 3210 or my Planet Ryder motor (your design) will meet the Challenge goal.

Either get cracking on something that will or shut the f*ck up.

 

[jscoot]

Randy,

Neither an Astra 3210 or my Planet Ryder motor (your design) will meet the Challenge goal.

Either get cracking on something that will or shut the f*ck up.

Have you ever tested your motor for a max continues torque load for 30 minutes ?
Do you think 6 nm would get too hot ?

 

[Miles]

Have you ever tested your motor for a max continues torque load for 30 minutes ?
Do you think 6 nm would get too hot ?

No, I haven't tested it. I'm pretty sure 12Nm for 30 minutes is beyond its limit, though. Without knowing the rating of the magnets, I wouldn't want to heat it above 80 deg. C. Could you do a test on your one?

A larger motor may have greater thermal inertia but the heat still needs to be dissipated eventually. So, you need a motor that is both very efficient and has a good heat dissipation rate.

 

[enoob]

The efficiency, power and torque density of his design can easily be improved upon with minimal changes in costs.

BINGO so do it and enter it in this challenge otherwise the rest of this post is more argumentative trash

What works for you or I is not as important as what Other Ebikers can enjoy at a decent price to build or eventually buy.

precisely my point in the post of mine you quote. and completely irrelevant to this thread.

 

[liveforphysics]

A larger motor may have greater thermal inertia but the heat still needs to be dissipated eventually. So, you need a motor that is both very efficient and has a good heat dissipation rate.

Yep. With a 30min continuous run, you can't skate through by simply being heavy, because it's going to find it's thermal equilibrium, or burn-up on the way there. This comes down to the motors ability to transfer heat into the air around it, and how much heat it's making (aka, efficiency).

My motor design uses the magnets in the rotor as pump veins, and has a 3" radius 1" width air inlet area towards the center. It's going to passively be pumping hundreds of CFM right across the coils and magnets. But... I've got a TON of work ahead of me to turn a few boxes of raw materials into something that spins. First I'm 100% focused on finishing the damn cell tester, then motor next

 

[etard]

Has anybody seen this:

http://www.alliedmotion.com/Products/Series.aspx?s=54

The motors are super heavy, but if you could buy the flux rings, etc... maybe a DIY motor for our needs could be made?
Seeing the huge ID of the motors has given me an idea that I m sure others have thought about as well. What if you could put planetary gearbox AND some sort of dog clutch two speed gearbox insideof the flux rings? Wouldn't that be ebike nirvana? It might be easier to design a motor around the SRAM 3 speed, to see hoe that works first.

http://www.alliedmotion.com/Data/Documents/MegafluxGenII_TechnologyOvr_R1_Std.pdf

 

[Arlo1]

Just when I thought I'd brake away from the computer and have a life for a while

 

[Arlo1]

I will clarify:
NO reductions will be tested.

I thought someone may get cute & incorperate a planitary mainshaft reduction, totaly intergrated into the "motor"
Definitaly NOT in the spirit of the Challange. (no Kudos for you)

Anyhing submited with a reduction on it, will be subjected to the furnace, poured into ingots & used as the trophy to the leader of the challange.

Sh#t realy ? Cause I have the perfact motor design that would have blown the doors off this due to the fact of the super high torque it would produce.

 

[olaf-lampe]

Hi gents,
I stumbled across this thread today and I was wondering why it all stopped suddenly?
I would like to enter the challenge with a 4-phase switched reluctance motor, but because it uses the wheel rim as rotor I'm not sure if it fits in the 3kg weight rule. John mentioned something about the weight-increase compared to a non-powered rim, but there was no decision taken. ( yet?)

What would be the biggest motor diameter the dyno could handle?

-Olaf

 

[Miles]

Hi Olaf,

I'm planning to have a go at making my axial flux design, later this year. I don't know how the others are getting on....

I set the weight limit because torque density generally scales with motor mass/volume.

Your SR wheel motor sound interesting. Is it finished? Any pics?

How much does your motor/rim unit weigh?

Maybe we could have another category for motors of, say, 3kg to 6 kg?

 

[Thud]

I am still in.......
Just need to finish the comuter, the road racer, the flat tracker & a few transmisions. Then we are right back on track to build the Dyno. :lol:

Good thing I am not easily distracted...






LOOK!............a penny

 

[Miles]

 

[olaf-lampe]

Hi Olaf,

I'm planning to have a go at making my axial flux design, later this year. I don't know how the others are getting on....

I set the weight limit because torque density generally scales with motor mass/volume.

Your SR wheel motor sound interesting. Is it finished? Any pics?

How much does your motor/rim unit weigh?

Maybe we could have another category for motors of, say, 3kg to 6 kg?

Sorry the SR motor is only a concept yet, but its theoretically 40% lighter with higher torque/efficiency than an async motor and I don't need any magnets
The main obstacle to build it is the controller + software. There are a number of indipendent coils ( no wye or delta stuff ) and they have to be switched with a proper timing advance. They only run in closed loop with a quadruple encoder/resolver feedback ( maybe also hall sensor, but then surely not very efficient )
If you want to know more, try this page:
http://www.maccon.de/en/motors/custom-motors/sr.html

The reason why I was looking in the motor category, was to ask for help on this idea. Than found the challenge thread.
If we had a controller, it would also be possible to build a SR-outrunner or axial gap .
They do not exceed PM-outrunner specs, the only appealing part is to build an non magnet motor in rim size.
If other like to chime in, we can start a new thread...
Olaf
<edit> Forgot to mention: they like to have a bigger airgap, which is fine for wobbling rims

 

[Toorbough ULL-Zeveigh]

I would like to enter the challenge with a 4-phase switched reluctance motor,

Research in the Department has resulted in the discovery that switched reluctance motors with an odd number of phase windings can be designed to operate with much higher efficiency than motors with an even number of phases.

 

[olaf-lampe]

I would like to enter the challenge with a 4-phase switched reluctance motor,

Research in the Department has resulted in the discovery that switched reluctance motors with an odd number of phase windings can be designed to operate with much higher efficiency than motors with an even number of phases.

Interesting article:

An approximate sliding mode input power controller and another feed-forward sliding mode speed controller are combined with space voltage vector modulation

But from here I'm lost

Also the extreme noise they seem to produce is more for people like AussieJester or LFP WEEEEEEEEEEEEEEEE
They seem to be proud of having 80-87% eff. :lol:
Maybe I try to build a 3-phase SR motor and adapt it to an infineon controller...just to satisfy my curiuosity
Olaf

 

[AussieJester]

More noise the better, & efficiency pffft...just add more lipos

KiM

 

[enoob]

efficiency pffft...just add more lipos
KiM

indeed.

olaf-lampe if i were you id work on power to weight ratio and worry about efficiency later.

im still in this hunt as well, im just working on getting an actual ebike rolling then ill re-open the diy motor project . wich if im correct may actually work i just havent spent enough time working all the possible connection combinations.