Motor comparison spreadsheet

Electric Motors and Controllers
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Miles
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Re: Motor comparison spreadsheet

Post by Miles » Jan 12, 2016 2:25 pm

crossbreak wrote:backiron thickness should be about half of the tooth width?
Only when the return path is via the adjacent tooth! When the number of poles is significantly less than the number of teeth, then.........

Hence my British understatement :) :
Miles wrote:
crossbreak wrote:If you just want thinner yokes, you can simply use high slot count like the leaf does.
Good luck with that....

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 12, 2016 4:23 pm

Hey guys I'm working out the math trying to get a educated guess together what I think the peak rms phase amps are for the Leaf motor from factory Now that we have kv and the battery is a 98s. (360v nominal). Kv at 20.5 it looks like they used a lot of feild weakening to get 10300rpm.
So this would mean they might have been using less phase amps then I originally though.
My guess is 516rms phase amps at 3000 rpm. And 614amps at 2000rpm for the 210ft-lbs they used to max out at.
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
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Re: Motor comparison spreadsheet

Post by Lebowski » Jan 13, 2016 3:34 am

Arlin, isn't it just a matter of keeping track of motor temperature and making sure you don't go over so and so many degrees ?

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 13, 2016 10:27 am

Lebowski wrote:Arlin, isn't it just a matter of keeping track of motor temperature and making sure you don't go over so and so many degrees ?
Not really. I think luke pointed out at some point that when your motor reaches 50% efficient is when you can no longer get any more power out of it.
I'm looking for that number where I can make any more HP because any more power added to the motor will just turn to heat.
I think if I spin it faster and build a controller for ~2000+ phase amps it will be close with a peak HP number at ~7500 rpm :)
This is for a Drag car. But I will drive it as a commuter in between races. And just remove the heavy battery for use with a light weight RC lipo drag battery for 1/4 mile stuff.
Crossbreak answered in PM and it looks promising. :)
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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Re: Motor comparison spreadsheet

Post by crossbreak » Jan 13, 2016 11:11 am

There indeed is this 50% efficiency rule at 50% no load speed. But it highly depends on battery voltage. The 2kA RMS are no where close to this figure even if you don't up the voltage. We're still talking about 80% EFF at 2kA RMS and 3000rpm

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 13, 2016 11:20 am

crossbreak wrote:There indeed is this 50% efficiency rule at 50% no load speed. But it highly depends on battery voltage. The 2kA RMS are no where close to this figure even if you don't up the voltage. We're still talking about 80% EFF at 2kA RMS and 3000rpm
So with 470v the no load speed is 9635 and at 410 (nominal voltage) the no load speed is 8405 which one do I use nominal or full voltage?
anyways 1/2 of the 9635 is 4817 1/2 of the 8405 is 4205 So if I get 50% efficient at ~4200-4800rpm I'm at the max power I can get out?

So I need to make a 4000 amp controller...? I don't know if the voltage will be able to push 4000 amps...
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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Re: Motor comparison spreadsheet

Post by crossbreak » Jan 13, 2016 11:56 am

So with 470v the no load speed is 9635 and at 410 (nominal voltage) the no load speed is 8405 which one do I use nominal or full voltage?
I think it's most realistic to use nominal voltage.

No idea how you come to that 4000A figure. the spreadsheet tells me it should be around 9000A at Pout= ~2.7MW. Still no realistic, as battery resistance was not taken into account. if you want a realistic figure, you have to add it to Rm in the spreadsheet. Guess it will be around the same as Rm, yso max Pout maybe roughly 1.3MW.

Still, these numbers are not realistic. As pointed out in PM, you will run into serious heat problems above 2000A.
I don't know if the voltage will be able to push 4000 amps...
what do you mean with this? The voltage is enough to push 9000A if your battery had no Ri

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 13, 2016 12:32 pm

crossbreak wrote:
I don't know if the voltage will be able to push 4000 amps...
what do you mean with this? The voltage is enough to push 9000A if your battery had no Ri
I meant I needed to work the math. :) Thats all.

Also I used 4000 amps more as a goal....
Remember I'm Hoping to get V1 to 800a rms for a 10 second burst....
4000 amps will not be cheep.... or easy....
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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Re: Motor comparison spreadsheet

Post by speedmd » Jan 13, 2016 3:13 pm

Interesting point on limiting the current to what the motor can actually use. Base current flow to torque output possibly? Those that have experience with carburetor racing engines may know the sensation of reaching the engines max power under load and just turning the throttle opening a bit further and having it just change the fuel mixture and actually reduce power. Not until we had good air metering based fuel injection did we see the potential improvement proper mix control had on ICE performance. Mix here is current to power vs current to waste heat. Torque /speed change over time may be the indicators that can tell the controller what is best to do.

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Re: Motor comparison spreadsheet

Post by Punx0r » Jan 13, 2016 7:37 pm

crossbreak wrote: what do you mean with this? The voltage is enough to push 9000A if your battery had no Ri
AFAIK, ignoring battery Ri max phase current at 50% no-load speed will be simply applied voltage divided by motor winding resistance. Applied voltage would be half battery voltage (as BEMF would be half Vbatt).

So I phasemax@50%speed = (1/2 Vbatt) / Rm

Battery, wiring and controller resistance would be added to bring this number down.

Yes/no?

Also, if you're drag racing and the motor isn't saturated, why not stuff in more current? :twisted:

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Re: Motor comparison spreadsheet

Post by crossbreak » Jan 13, 2016 9:15 pm

yep, thats exactly how it works!
why not stuff in more current?
It will meltdown within much less than 10 seconds. But it has to work 10 seconds to make it to the finish line fast. The Copper of this motor for example (13kg) can take approx. 800kJ of heat before it takes damage. So, copper loss should be no more than ~80kW within these 10 seconds. This is how I came to the 2kA figure.

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 14, 2016 12:18 am

crossbreak wrote:yep, thats exactly how it works!
why not stuff in more current?
It will meltdown within much less than 10 seconds. But it has to work 10 seconds to make it to the finish line fast. The Copper of this motor for example (13kg) can take approx. 800kJ of heat before it takes damage. So, copper loss should be no more than ~80kW within these 10 seconds. This is how I came to the 2kA figure.
If we make enough power the time becomes less then 10s
I would say ~400hp is 10s ~700hp is 8.5s and ~1300hp is 7s etc. Looking to increase RPM as well.
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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Re: Motor comparison spreadsheet

Post by speedmd » Jan 14, 2016 1:47 pm

Pulsed current can be much higher as demonstrated by many here than continuous current. Imagine Much depends on wave forms and wire conduction - heat flows/paths and conducting heat sink as well as air flows. Amp limit may be closer to conductor fusing current in practice at least for the few seconds of a drag race.

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Re: Motor comparison spreadsheet

Post by Punx0r » Jan 14, 2016 1:50 pm

If the car is going to be a front wheel drive Leaf I think motor temperature will be far from your greatest obstacle to getting those kind of times :D

Crossbreak, taking mass of copper and using specific heat capacity to find a ball park upper limit for maximum short burst power is interesting, I like it :) I have a suggestion though: fill the motor with liquid nitrogen before the race. Double win of much lower copper loss and amazing cooling. Once the LN2 has boiled off after racing the car runs as normal for street use with no mess.

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 14, 2016 2:58 pm

Fwd for now... If possible I want to add one to the rear wheels when time comes. Fwd street cars are now running in the 7s thanks to mutual friends of Luke's at Speed factory
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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Re: Motor comparison spreadsheet

Post by speedmd » Jan 14, 2016 3:37 pm

I have a suggestion though: fill the motor with liquid nitrogen before the race.
:twisted: CO2 type fire extinguisher sprayed in during high current dumps!

As long as the motor is making mostly torque with the current and not abnormal amounts of heat, why limit it unless traction is broken?

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 14, 2016 5:17 pm

There will be a point where the magnets and iron can't offer any more torque even if you make the electro magnet stronger.... Otherwise the limits will be in the controller the battery and the wiring.
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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Re: Motor comparison spreadsheet

Post by speedmd » Jan 14, 2016 11:36 pm

There will be a point where the magnets and iron can't offer any more torque even if you make the electro magnet stronger.
The stronger (more amp turns) the electro magnet, the stronger the attraction- repulsion up to the point of saturation of the stator core. After that point you are just wasting current. Is my understanding wrong here?

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Re: Motor comparison spreadsheet

Post by bunya » Jan 15, 2016 12:09 am

jk1 wrote:
For the cyclone 1680w motor no load measurement did you try it without the motor seal ? Most motors do not have a seal whereas that one does. Also IPM design has LESS eddy current losses not more, and its the reason why Zero motorcycles went to them this year , here is a video of the benefits of IPM design :

http://www.motorcycle-usa.com/2015/12/a ... rce-motor/
I didn't try the motor without the seal, I could remove the spring that provides the tension to the seals lip and see it there is any noticeable difference... I was referring to the Eddy losses in the laminations not relating them to the IPM design.
I was more trying to understand the high losses at no load, motors are pretty tricky to get a head around especially considering there are so many different operating conditions. In regards to the IPM comment I was more referring to the fact that by having more iron between the magnet and the stator poles there is more material that sees a change in magnetic flux and more associated losses. Do you think magnetic flux reversal inside the magnets is significant at no load when comparing SMPM to IPM losses?

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 15, 2016 2:32 am

speedmd wrote:
There will be a point where the magnets and iron can't offer any more torque even if you make the electro magnet stronger.
The stronger (more amp turns) the electro magnet, the stronger the attraction- repulsion up to the point of saturation of the stator core. After that point you are just wasting current. Is my understanding wrong here?
I think you have it correct and I worded it incorrect.
Meaning the iron the electro magnet is wrapped around has a limit.
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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Re: Motor comparison spreadsheet

Post by Punx0r » Jan 15, 2016 11:22 am

Arlo, yours is an amazing project - much respect on that. Those Civic guys with the 7.995 sec pass have also done immensely well, but I still have a hunch that most of their success is due to their work on the chassis to let them put down the power. I'd think your biggest challenges would be, in ascending order: 1) Making the required motor torque, 2) not grenading the transmission 3) putting that power down to the ground. Electric sure gives you an advantage with 1) but probably makes 2) harder :D

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Re: Motor comparison spreadsheet

Post by speedmd » Jan 15, 2016 11:30 am

the iron the electro magnet is wrapped around has a limit
Better stator iron (higher T) is key limiting factor to max current?

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Re: Motor comparison spreadsheet

Post by crossbreak » Jan 15, 2016 1:08 pm

Punx0r wrote:2) not grenading the transmission
Most gear transmissions use hardened steel teeth. The limiting factor for these materials is the tooth flank surface pressure. If it is too high, the surface is damaged, this induces wear. The other limit is the strength of the tooth root. Tooth root exploitation is small in most car gearboxes (like 30%), while flank exploitation is high (like almost 100%). So these gearboxes will likely die by caries, not by tooth fracture. You should be able to use such a gearbox at 300% it's original rating without braking something, but it will be worn out much faster

For the leaf this would be around 800 Nm, which relate to 1700A RMS phase current :shock:

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Re: Motor comparison spreadsheet

Post by crossbreak » Jan 15, 2016 1:12 pm

speedmd wrote:Better stator iron (higher T) is key limiting factor to max current?
yep, using Vacoflux50 or Hyperco50 Permendur alloys, you can reach 2.3 Tesla http://www.vacuumschmelze.com/fileadmin ... -004_e.pdf

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Re: Motor comparison spreadsheet

Post by Arlo1 » Jan 15, 2016 1:24 pm

crossbreak wrote:
Punx0r wrote:2) not grenading the transmission
Most gear transmissions use hardened steel teeth. The limiting factor for these materials is the tooth flank surface pressure. If it is too high, the surface is damaged, this induces wear. The other limit is the strength of the tooth root. Tooth root exploitation is small in most car gearboxes (like 30%), while flank exploitation is high (like almost 100%). So these gearboxes will likely die by caries, not by tooth fracture. You should be able to use such a gearbox at 300% it's original rating without braking something, but it will be worn out much faster

For the leaf this would be around 800 Nm, which relate to 1700A RMS phase current :shock:
A problem 1 day I will have!
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

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