Bullfrog said: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 said:Bullfrog said: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.
ebike4healthandfitness said: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.
I've noticed the power relationship you mentioned too. It makes more sense after playing with the simulator.Bullfrog said: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?motor=MMAC10T&batt=B5216_GA&cont=C40&hp=0&cont_b=C40&motor_b=MMAC12T&batt_b=B5216_GA&hp_b=0&bopen=true
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
Bullfrog said:ebike4healthandfitness said:Bullfrog said: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?motor=MMAC10T&batt=B5216_GA&cont=C40&hp=0&cont_b=C40&motor_b=MMAC12T&batt_b=B5216_GA&hp_b=0&bopen=true
john61ct said: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.
calab said: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 https://endless-sphere.com/forums/viewtopic.php?f=2&t=64907&p=974291&hilit=myth#p974291
https://endless-sphere.com/forums/viewtopic.php?f=2&t=14482&p=218275&hilit=motor+winds#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
justin_le said:torker said: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
E-HP said: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?motor=Leaf%205T&batt=cust_72_0.05_24&cont=cust_70_200_0.03_V&hp=0&axis=mph&frame=mountain&autothrot=false&throt=100&grade=0&bopen=true&cont_b=cust_1000_3000_0.03_V&motor_b=Leaf%205T&batt_b=cust_72_0.05_24&hp_b=0
With 120N-M+ available at 25mph, seems like power wheelies at that speed are likely.
The Toecutter said: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.
Bullfrog said: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.
Controller and phase wire resistance.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.
E-HP said: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.
The Toecutter said:E-HP said: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.
calab said:https://endless-sphere.com/forums/viewtopic.php?f=2&t=64907&hilit=myth&start=350#p984783apples 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.