Leaf / leafmotor / leafbike high efficiency 1500w motor

General Discussion about electric bicycles.
john61ct   100 GW

100 GW
Posts: 8443
Joined: Dec 18 2018 2:06pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by john61ct » Dec 20 2021 5:38pm

From my notes

"torque is proportional to current SQUARED REGARDLESS of RPM…

that is true up until the field enters saturation, at which point torque increases linearly with current."



Apparently this might only be true for "series motors"??

Bullfrog   10 kW

10 kW
Posts: 524
Joined: Apr 08 2017 10:37am

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Bullfrog » Dec 21 2021 1:15pm

Below is an explanation of Magnetic Saturation and its effects from one of the guys on the Endless Sphere forum that I respect a lot:

"The saturation point only depends on the iron properties and the amp-turns of copper. Making the laminations thinner won't change the saturation point but will reduce eddy current losses. For a given stator material, the flux increases linearly with current until you reach saturation. After that, more current barely increases the flux and you get a lot of heating in the copper."

"the iron properties" are referring to the material composing the stator poles which have copper wire wound around them.

"flux" is the strength of the magnetic field and is directly proportional to the torque/acceleration produced by the motor.

Everything above applies to a Direct Drive hub motor like the LEAF, a geared hub motor like the GMAC/MAC, and a mid drive like the BBSHD.

ebike4healthandfitness   10 kW

10 kW
Posts: 553
Joined: May 19 2012 10:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by ebike4healthandfitness » Dec 22 2021 6:41pm

Bullfrog wrote:
Dec 21 2021 1:15pm
Below is an explanation of Magnetic Saturation and its effects from one of the guys on the Endless Sphere forum that I respect a lot:

"The saturation point only depends on the iron properties and the amp-turns of copper.Making the laminations thinner won't change the saturation point but will reduce eddy current losses. For a given stator material, the flux increases linearly with current until you reach saturation. After that, more current barely increases the flux and you get a lot of heating in the copper."

"the iron properties" are referring to the material composing the stator poles which have copper wire wound around them.

"flux" is the strength of the magnetic field and is directly proportional to the torque/acceleration produced by the motor.

Everything above applies to a Direct Drive hub motor like the LEAF, a geared hub motor like the GMAC/MAC, and a mid drive like the BBSHD.
Regarding the amp-turns of copper.....In the simulator for any given motor family the lowest turn (i.e fastest wind) always make the most power for any given voltage and amps.

Bullfrog   10 kW

10 kW
Posts: 524
Joined: Apr 08 2017 10:37am

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Bullfrog » Dec 22 2021 7:00pm

ebike4healthandfitness wrote:
Dec 22 2021 6:41pm
Bullfrog wrote:
Dec 21 2021 1:15pm
Below is an explanation of Magnetic Saturation and its effects from one of the guys on the Endless Sphere forum that I respect a lot:

"The saturation point only depends on the iron properties and the amp-turns of copper.Making the laminations thinner won't change the saturation point but will reduce eddy current losses. For a given stator material, the flux increases linearly with current until you reach saturation. After that, more current barely increases the flux and you get a lot of heating in the copper."

"the iron properties" are referring to the material composing the stator poles which have copper wire wound around them.

"flux" is the strength of the magnetic field and is directly proportional to the torque/acceleration produced by the motor.

Everything above applies to a Direct Drive hub motor like the LEAF, a geared hub motor like the GMAC/MAC, and a mid drive like the BBSHD.
Regarding the amp-turns of copper.....In the simulator for any given motor family the lowest turn (i.e fastest wind) always make the most power for any given voltage and amps.
The same motor family should make identical power no matter what the winding, if the same "battery" amperage is supplied...up until the point that the slower speed winding begins to approach the synchronous speed.

There may be a difference at low speeds but only if the controller can't supply adequate "phase" amperage to the faster motor.

This run using a 12T and a 10T MAC is a good example:

https://ebikes.ca/tools/simulator.html? ... bopen=true

User avatar
neptronix   100 GW

100 GW
Posts: 16354
Joined: Jun 15 2010 5:56pm
Location: Utah, USA
Contact:

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by neptronix » Dec 22 2021 9:52pm

ebike4healthandfitness wrote:
Dec 22 2021 6:41pm
Regarding the amp-turns of copper.....In the simulator for any given motor family the lowest turn (i.e fastest wind) always make the most power for any given voltage and amps.
That's not my experience at all. No in the real world, nor with the simulator.
If you see a difference, it's a percent or two in a certain part of the power band. And sometimes the low turn count motor even wins the hair-splitting contest.

If you see a difference more dramatic than that, you're not feeding the low turn count motor enough phase and battery amps, you're using a high resistance battery or controller, etc and have voltage drop as a result that's lowering the efficiency.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

User avatar
neptronix   100 GW

100 GW
Posts: 16354
Joined: Jun 15 2010 5:56pm
Location: Utah, USA
Contact:

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by neptronix » Dec 22 2021 9:53pm

Oy, bullfrog got to it first.. :)
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

User avatar
E-HP   1.21 GW

1.21 GW
Posts: 3744
Joined: Nov 01 2018 9:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by E-HP » Dec 22 2021 11:23pm

Bullfrog wrote:
Dec 22 2021 7:00pm
The same motor family should make identical power no matter what the winding, if the same "battery" amperage is supplied...up until the point that the slower speed winding begins to approach the synchronous speed.

There may be a difference at low speeds but only if the controller can't supply adequate "phase" amperage to the faster motor.

This run using a 12T and a 10T MAC is a good example:

https://ebikes.ca/tools/simulator.html? ... bopen=true
I've noticed the power relationship you mentioned too. It makes more sense after playing with the simulator.

Some of the relationships between the same motor families are counterintuitive. For example, on the two MACs, my intuition tells me that the 12T motor could handle a 10% hill longer than the 10T. But, for any speed the 12T climbs the hill, the 10T just needs to throttle back to the same speed as the 12T, and the 12T will always melt first.
MACS.jpg
MACS.jpg (395.06 KiB) Viewed 555 times
Same motor power, and the 12T even shows slightly better efficiency. Maybe the 10T winding has more copper fill?

Bringing it back full circle to the Leaf. Is it better to get the 6T if you don't need the 5T speed, because of the copper fill?

calab   100 kW

100 kW
Posts: 1222
Joined: Dec 11 2013 1:00am

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by calab » Dec 22 2021 11:34pm

Keep one motor locked in and you need to play with the other same motor values like the battery voltage, controller amps, resistances and throttle around until the curves match, its been done all before and it has confused many. Motors have different winding resistances but it all equals out because of the math formulas described in the big thread viewtopic.php?f=2&t=64907&p=974291&hilit=myth#p974291
viewtopic.php?f=2&t=14482&p=218275&hili ... ds#p218275
The myth that more turns = more torque is deeply pervasive in this industry. I blame some well intended but ill-informed Crystalyte salesmen in the early 2000's for entrenching the entire ebike community with this falsehood, and it's forever an uphill battle to set the record straight.

Justin

ebike4healthandfitness   10 kW

10 kW
Posts: 553
Joined: May 19 2012 10:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by ebike4healthandfitness » Dec 22 2021 11:39pm

Bullfrog wrote:
Dec 22 2021 7:00pm
ebike4healthandfitness wrote:
Dec 22 2021 6:41pm
Bullfrog wrote:
Dec 21 2021 1:15pm
Below is an explanation of Magnetic Saturation and its effects from one of the guys on the Endless Sphere forum that I respect a lot:

"The saturation point only depends on the iron properties and the amp-turns of copper.Making the laminations thinner won't change the saturation point but will reduce eddy current losses. For a given stator material, the flux increases linearly with current until you reach saturation. After that, more current barely increases the flux and you get a lot of heating in the copper."

"the iron properties" are referring to the material composing the stator poles which have copper wire wound around them.

"flux" is the strength of the magnetic field and is directly proportional to the torque/acceleration produced by the motor.

Everything above applies to a Direct Drive hub motor like the LEAF, a geared hub motor like the GMAC/MAC, and a mid drive like the BBSHD.
Regarding the amp-turns of copper.....In the simulator for any given motor family the lowest turn (i.e fastest wind) always make the most power for any given voltage and amps.
The same motor family should make identical power no matter what the winding, if the same "battery" amperage is supplied...up until the point that the slower speed winding begins to approach the synchronous speed.

There may be a difference at low speeds but only if the controller can't supply adequate "phase" amperage to the faster motor.

This run using a 12T and a 10T MAC is a good example:

https://ebikes.ca/tools/simulator.html? ... bopen=true
How does your example go against what I wrote? The 10T makes about 100 watts more power than the 12T with about 2 less phase amps.

BalorNG   1 kW

1 kW
Posts: 348
Joined: Nov 10 2019 7:22pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by BalorNG » Dec 23 2021 12:28am

Low turn vs high turn count is a matter of balancing voltages and currents for a given speed and efficiency.
2x higher turn count motor needs, roughly speaking, 2x more voltage and 2x less current to acheve same speed/torque and efficiency. There is just no replacing magnet/stator/copper mass (sheer motor size) - and besides the power is supplied by the CONTROLLER. You can feed 10kw to a 25ow hub. But if it will happen at low speed it will melt in short order - and at high speed it will either fly part or again melt - from iron losses.

OTHER factors must be considered: for instance, it is just plain easier and *safer* to get high-current, low voltage batteries AND controllers - less electrocution chance, less series connections to balance, high-voltage fets are less efficient and switch less fast in general, and there are cheap and very, very powerful controllers avalable like Vescs. High-voltage chargers are harder to get and more expeincive.... unless you have a 400v battery :P

If you want to keep withing e-bike voltages (generally safe to handle) and want considerably more power - lower turn count AND higher mechanical gear reduction is the way to go.

john61ct   100 GW

100 GW
Posts: 8443
Joined: Dec 18 2018 2:06pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by john61ct » Dec 23 2021 6:59am

Which brings us again to what seems to me to be a sensible approach

Figure out what gets you to the maximum top speed you want

including for getting out of traffic issues

and do not build a system that gets you any faster than that, no higher voltage than necessary.

Within that context, going much higher torque capacity than you think you need is OK, invest in higher **current** and heat dissipation.

The key is, not underestimating the top speed needed, "just barely" reaching that may not be enough, you want to be at partial throttle much of the time not WOT.

Not that I expect any true consensus, but do you experts mostly-ish agree?

User avatar
ZeroEm   10 MW

10 MW
Posts: 2335
Joined: May 03 2019 11:53am
Location: San Antonio, TX

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by ZeroEm » Dec 23 2021 10:39am

Looks like it has all been said again. Sorta of like the winding discussion. It rises up again now and again. People new to the idea need to embed the facts.

Unless you are building a race bike then you need the find your average riding speed and keep the motor spinning at least 50% of its max speed. Different windings let you tune your motor to this. It's really which winding is best for you with your setup.

Most know the rules run a lot of amps and small wheel and your favorite voltage. Get the winding that gets you close to the top speed you will use with out burning it up.

Myself did not want fuss with the wires in the axel so ran with a higher voltage and lower winding to get what I wanted. If you take your time beef up the wiring to run more amps and lower Turn motor.
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

User avatar
E-HP   1.21 GW

1.21 GW
Posts: 3744
Joined: Nov 01 2018 9:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by E-HP » Dec 23 2021 11:27am

john61ct wrote:
Dec 23 2021 6:59am
Figure out what gets you to the maximum top speed you want

including for getting out of traffic issues

and do not build a system that gets you any faster than that, no higher voltage than necessary.
I look at a couple of things, since I'm most interested in mid-range roll on acceleration, not top speed. I noticed that if you still have around 60N-M or above available and twist the throttle more, you can feel the bike accelerate. Below that, it accelerates more slowly, based on my seat of the pant dyno. So, for the speed range that I ride, I want the torque to be above that value.

I also look for the "knee" in the torque curve (where it sharply drops off), and want that drop off to occur above my normal riding speeds (with the cushion to accelerate faster than my cruising speed to get out of situations). In the end, like with a motorcycle, I want 3 escape options, braking, maneuvering, and accelerating.
Knee.jpg
Knee.jpg (157.92 KiB) Viewed 495 times
I cruise at 20-25mph, but want to accelerate quickly to 35mph when necessary.

ebike4healthandfitness   10 kW

10 kW
Posts: 553
Joined: May 19 2012 10:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by ebike4healthandfitness » Dec 24 2021 1:12am

calab wrote:
Dec 22 2021 11:34pm
Keep one motor locked in and you need to play with the other same motor values like the battery voltage, controller amps, resistances and throttle around until the curves match, its been done all before and it has confused many. Motors have different winding resistances but it all equals out because of the math formulas described in the big thread viewtopic.php?f=2&t=64907&p=974291&hilit=myth#p974291
viewtopic.php?f=2&t=14482&p=218275&hili ... ds#p218275
The myth that more turns = more torque is deeply pervasive in this industry. I blame some well intended but ill-informed Crystalyte salesmen in the early 2000's for entrenching the entire ebike community with this falsehood, and it's forever an uphill battle to set the record straight.wh

Justin
Look at the whole quote from Justin:
justin_le wrote:
Dec 07 2009 1:16am
torker wrote:Is that 6*10 pretty torquey? Anything to compare it to. I didn't get to order mine during the sale. I did get my donor bike. Picked up a Giant Rincon for 110 dollars on Craigslist.
The 6x10 winding won't really have any more torque than the 7x9 or 9x7 windings. You'll only get marginally more torque off the line and at a stall because the controller and phase lead losses will be somewhat less, but the effect is going to be pretty small, and can be negated with the faster winds by using heavy 10 or 12 AWG phase wire between your controller and the motor. As soon as you reach any appreciable speeds, then the slow 6x10 winding would have LESS torque than the faster windings for a given controller/battery combo.

The myth that more turns = more torque is deeply pervasive in this industry. I blame some well intended but ill-informed Crystalyte salesmen in the early 2000's for entrenching the entire ebike community with this falsehood, and it's forever an uphill battle to set the record straight.

Justin

Less torque for the slower wind means less power.

So yeah, faster winds (for any given motor family) in the simulator make more power for any given voltage and controller combo.

User avatar
The Toecutter   100 kW

100 kW
Posts: 1017
Joined: Feb 08 2015 4:02pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by The Toecutter » Dec 24 2021 10:26am

Part of the reason that myth persists is because a higher turn count gives more torque per ampere of current. This does NOT mean the motor can produce more torque with a higher turn count wind than a lower turn count wind continuously without overheating. Maximum continuous torque between the two motors will be comparable, with a slight advantage to whatever wind has the most ideal combination between less conductor length/increased conductor thickness/more copper fill. The lower turn count motor will commonly be able to handle more amperes of current continuously than a higher turn count motor to make up for the less torque delivered per ampere of current, and closely in proportion, making roughly the same continuous torque.

The same mostly applies to peak torque output as well, but any differences between the lower turn count motor and higher turn count motor become more pronounced. And you have to assume a controller with no current limit, wherein you output to the motor as much current as possible until you reach flux saturation. A lower turn count motor and higher turn count motor will have roughly the same peak torque capability, again with a slight advantage to whatever wind has the most ideal combination between less conductor length/increased conductor thickness/more copper fill. The lower turn count motor will require more amperes of current to do it.

Back in the early days of ebikes, commercially available controllers couldn't make the kind of max current they do today, so if you wanted a faster-accelerating ebike, a higher turn count motor was commonly the least expensive way to do it.

This is why I chose a 4T wind instead of a 3T wind Leafbike motor for my first ebike build. The 96A max phase current from my Phaserunner controller is a limiting factor, and thus by picking the 4T wind, I can make roughly 33% more torque than the 3T wind, and with a 26" diameter drive wheel, the extra acceleration is much appreciated. But this increased torque output is only within the context of my controller being the limiting factor. Both motors are roughly capable of the same amount of continuous torque without overheating(with a slight advantage to the 3T wind due to more copper infill, shorter/thicker conductor length), and maximum possible peak torque would be almost the same between the two without a maximum current limit imposed by the controller, thereby allowing flux saturation to be reached.

My most recent purchase is a 3T wind Leafbike built into a 20" wheel. THIS is what the ASI BAC4000 controller in my possession is for. The controller can output over 400A phase current, but the motor will reach flux saturation around 250A and this 250A is what the controller will be programmed to limit the phase current to. This same phase current could much more easily damage the 4T wind motor in my possession than my 3T wind motor, all things being equal(and they're not, given different wheel diameters). I picked this motor because I'm building a sports car posing as a human powered vehicle that is functional as either, and want to have the performance of a car when the motor is in use. The 3T has the combination of traits of the winds available most conducive to this goal when considering the off the shelf components available.

If I were building a normal inexpensive ebike with 26" wheels and desiring performance more typical of a commuter ebike and were more budget-oriented, I think a 6T wind would be the ideal choice from the Leafbike 1500W series of motors, especially paired with a Phaserunner controller running at its maximum of 72V. It would make 50% more torque per amp when compared to my current 4T setup, and with a 72V pack, it would be able to top out at over 40 mph, which is enough margin to accelerate away from trouble in any city environment where cruising speeds are commonly 20-30 mph, while the 96A phase current limit imposed by the controller would allow initial acceleration from a stop light comparable to a 200A phase current on a 3T wind motor(given the same wheel diameter).

And if doing a fully street legal 750W/28 mph build with 26" drive wheel, a Baserunner and a 6T wind with a 48V or 52V pack would be an even more suitable/cheaper combo. It would maximize the possible acceleration from this controller while being optimized for street legal speeds, and the motor would be incapable of overheating in virtually any fathomable usage cases.
Custom electric velomobile, 2500W: viewtopic.php?f=6&t=110298

User avatar
ZeroEm   10 MW

10 MW
Posts: 2335
Joined: May 03 2019 11:53am
Location: San Antonio, TX

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by ZeroEm » Dec 24 2021 11:23am

If you study the charts close you will see that with the same setup the torque moves from upper rpm to lower rpm range as you increase the turn count.
This does not make the motor more powerful or does it lose power you just move it in the rpm range where you want or need it.
Have been looking to keep my motor spinning at 50% of max rpm for power, efficiency. My first setup with the leafmotor was close with a 7T at 72V in a 26" wheel. It's hard talking about windings without quoting Wheel size and voltage which affect how fast the motor is going to turn.

Grin has the 5T leafmotor in the simulator so used it to compare to the 7T leafmotor.
5Tvs7T.jpg
5Tvs7T.jpg (171.83 KiB) Viewed 425 times
Currently use Grins 40a controller and using a 72V 24ah battery (not Grins) so it all close to real life.
I'm heavy and did not want my tike to lug when taking off and do not ride above 30 mph. Top speed of 53 kph is good as have it limited to 45 kph at the moment. Ride the trails at 15mph/24kph so it all works well for me.

You can see what torque I gain on the low end is lost on the top end. One motor is not more powerful than the other. Next leafmotor will be a 6T in a 24" wheel think will will be a great setup with a ASI 2000.
6TASI2000.jpg
6TASI2000.jpg (129.97 KiB) Viewed 425 times
Looks good right!
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

User avatar
E-HP   1.21 GW

1.21 GW
Posts: 3744
Joined: Nov 01 2018 9:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by E-HP » Dec 24 2021 1:53pm

Possibly going back to the saturation discussion; I noticed that the more current is available to the motor, the "knee", for lack of the correct term, in the torque curve moves up and toward lower speeds/rpms; and at some point the torque curve become completely smooth; at 325 battery amps (975 phase amps) in this example, and no matter how much additional current is made available, all of the curves remain the same (note that the other curves, power and efficiency, all smooth out at well). Even when upping the current to 1000 battery/3000 phase, the curves don't change. Is this somewhat tied to saturation?
sat.jpg
sat.jpg (410.6 KiB) Viewed 415 times
https://ebikes.ca/tools/simulator.html? ... _24&hp_b=0

With 120N-M+ available at 25mph, seems like power wheelies at that speed are likely.

Bullfrog   10 kW

10 kW
Posts: 524
Joined: Apr 08 2017 10:37am

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Bullfrog » Dec 24 2021 2:03pm

E-HP wrote:
Dec 24 2021 1:53pm
Possibly going back to the saturation discussion; I noticed that the more current is available to the motor, the "knee", for lack of the correct term, in the torque curve moves up and toward lower speeds/rpms; and at some point the torque curve become completely smooth; at 325 battery amps (975 phase amps) in this example, and no matter how much additional current is made available, all of the curves remain the same (note that the other curves, power and efficiency, all smooth out at well). Even when upping the current to 1000 battery/3000 phase, the curves don't change. Is this somewhat tied to saturation?
sat.jpg
https://ebikes.ca/tools/simulator.html? ... _24&hp_b=0

With 120N-M+ available at 25mph, seems like power wheelies at that speed are likely.
According to Justin, the Grin Tech Motor Simulator does NOT take into account magnetic saturation.


User avatar
The Toecutter   100 kW

100 kW
Posts: 1017
Joined: Feb 08 2015 4:02pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by The Toecutter » Dec 24 2021 7:59pm

Magnetic saturation is going to impose an upper limit on max torque output before there are severe diminishing returns. Adding more amperes after that saturation point will mostly make heat instead of torque, so severely to the point that perhaps doubling the current might only give you 10-20% more torque. The added amps WILL give you more torque, however, it probably won't be enough to justify the extra damage and wear/tear on the motor from all of the excess heat, and just demanding that sort of torque even once you'd be compromising the motor's ability to sustain higher power demands for the duration of the ride.
Custom electric velomobile, 2500W: viewtopic.php?f=6&t=110298

User avatar
E-HP   1.21 GW

1.21 GW
Posts: 3744
Joined: Nov 01 2018 9:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by E-HP » Dec 24 2021 8:40pm

The Toecutter wrote:
Dec 24 2021 7:59pm
Magnetic saturation is going to impose an upper limit on max torque output before there are severe diminishing returns. Adding more amperes after that saturation point will mostly make heat instead of torque, so severely to the point that perhaps doubling the current might only give you 10-20% more torque. The added amps WILL give you more torque, however, it probably won't be enough to justify the extra damage and wear/tear on the motor from all of the excess heat, and just demanding that sort of torque even once you'd be compromising the motor's ability to sustain higher power demands for the duration of the ride.
It looks like for any given voltage level, there's a maximum torque the motor can produce, as long as the motor gets as much current as it can take. If you change the controller to provide 1000A, the max is still the same; 300 and 420 for 72V and 100V in this example.
Max Torque.jpg
Max Torque.jpg (438.97 KiB) Viewed 387 times
https://ebikes.ca/tools/simulator.html? ... bopen=true

ebike4healthandfitness   10 kW

10 kW
Posts: 553
Joined: May 19 2012 10:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by ebike4healthandfitness » Dec 24 2021 10:46pm

Bullfrog wrote:
Dec 21 2021 1:15pm
Below is an explanation of Magnetic Saturation and its effects from one of the guys on the Endless Sphere forum that I respect a lot:

"The saturation point only depends on the iron properties and the amp-turns of copper. Making the laminations thinner won't change the saturation point but will reduce eddy current losses. For a given stator material, the flux increases linearly with current until you reach saturation. After that, more current barely increases the flux and you get a lot of heating in the copper."

"the iron properties" are referring to the material composing the stator poles which have copper wire wound around them.

"flux" is the strength of the magnetic field and is directly proportional to the torque/acceleration produced by the motor.

Everything above applies to a Direct Drive hub motor like the LEAF, a geared hub motor like the GMAC/MAC, and a mid drive like the BBSHD.
Bullfrog,

Can you clarify the part about the amp turns of copper?

calab   100 kW

100 kW
Posts: 1222
Joined: Dec 11 2013 1:00am

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by calab » Dec 25 2021 12:30am

viewtopic.php?f=7&t=99255&p=1453302&hil ... s#p1453170 Look at the resistance on the second graph viewtopic.php?f=2&t=64907&hilit=myth&start=350#p984783
apples to apples comparison means that when you select a low turn motor, you are running at a lower voltage and higher current in general, so your phase wire gauge, controller mosfet resistance etc. should scale down accordingly so that the external losses are the same. In that apples to apples sense, motor winding really makes no difference as the graph above shows. The blame for lower torque with the fast motor does not lay in the motor, but in the controller and external wiring.
Controller and phase wire resistance.
motor graph.jpg
motor graph.jpg (90.37 KiB) Viewed 360 times

User avatar
The Toecutter   100 kW

100 kW
Posts: 1017
Joined: Feb 08 2015 4:02pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by The Toecutter » Dec 25 2021 12:40am

E-HP wrote:
Dec 24 2021 8:40pm

It looks like for any given voltage level, there's a maximum torque the motor can produce, as long as the motor gets as much current as it can take. If you change the controller to provide 1000A, the max is still the same; 300 and 420 for 72V and 100V in this example.
Check the controller/battery current for the two settings. They are not equal.
Custom electric velomobile, 2500W: viewtopic.php?f=6&t=110298

User avatar
E-HP   1.21 GW

1.21 GW
Posts: 3744
Joined: Nov 01 2018 9:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by E-HP » Dec 25 2021 1:29pm

The Toecutter wrote:
Dec 25 2021 12:40am
E-HP wrote:
Dec 24 2021 8:40pm

It looks like for any given voltage level, there's a maximum torque the motor can produce, as long as the motor gets as much current as it can take. If you change the controller to provide 1000A, the max is still the same; 300 and 420 for 72V and 100V in this example.
Check the controller/battery current for the two settings. They are not equal.
Yup, looks like with the higher voltage, higher current is required to reach to max torque for that voltage. It's actually proportionally higher to the voltage increase. If you increase the available current for either scenario, the graphs don't change, but they do change if you decrease the current.

Here's "System A" with half the current and twice the current. But with double the current, the max torque is still the same at 300 N-M
higher lower.jpg
higher lower.jpg (408.9 KiB) Viewed 297 times

ebike4healthandfitness   10 kW

10 kW
Posts: 553
Joined: May 19 2012 10:20pm

Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by ebike4healthandfitness » Dec 25 2021 3:38pm

calab wrote:
Dec 25 2021 12:30am
viewtopic.php?f=2&t=64907&hilit=myth&start=350#p984783
apples to apples comparison means that when you select a low turn motor, you are running at a lower voltage and higher current in general, so your phase wire gauge, controller mosfet resistance etc. should scale down accordingly so that the external losses are the same. In that apples to apples sense, motor winding really makes no difference as the graph above shows. The blame for lower torque with the fast motor does not lay in the motor, but in the controller and external wiring.
I've seen that written as well as a fast wind running in a smaller wheel being equal to a slow wind in a larger wheel at the same voltage and amps.
Last edited by ebike4healthandfitness on Dec 25 2021 7:31pm, edited 1 time in total.

Post Reply