Power in Flux

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Type: Posts; User: liveforphysics

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    You can also combine any of these you like. Very...

    You can also combine any of these you like. Very often the top one gets combined with the second one, as the top one is great at very low RPMs, and the second one is great at high rpms.
    ...
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    PMBLDC motors are equipped with systems to...

    PMBLDC motors are equipped with systems to resolve rotor position. You can do it sensorlessly, by measuring the change in inductance of the phases, as its influenced by the magnets position in...
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    You're working with a brushed motor, I think it's...

    You're working with a brushed motor, I think it's series wound too right? So when you have rapid changes in RPM your controller doesn't know, care, or need to know or care. Your controller is...
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    If some of you guys are interested in learning...

    If some of you guys are interested in learning about motors, there is a section on ES called "motor technology" and it's pretty killer.

    The posts by members "Biff", "Bigmoose", "Miles", "Jeremy...
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    On ES, about 3 folks made trannys from scratch...

    On ES, about 3 folks made trannys from scratch for ebikes.

    Here is my favorite one, very clever garage-built engineering, and it worked great, I rode the bike later putting around at the...
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    The more I think about Biff's post (basically,...

    The more I think about Biff's post (basically, pick a gear for the road and leave it alone), I do think it could be worth the ~3% friction hit in some situations (the extra weight etc is kinda up to...
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    Yep. Some core losses grow at the square of RPM,...

    Yep. Some core losses grow at the square of RPM, one grows at the cube of RPM, so you might find yourself with rapidly diminishing efficiency trying to spin a motor to 12k that was designed for 6k...
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    I think they are looking for OEM deals rather...

    I think they are looking for OEM deals rather than the hobby market.
    What's amazing though, is at the OEM production scale, I bet this motor costs under $1000.
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    It can also be 45v to achieve the same...

    It can also be 45v to achieve the same performance, it would just be a 1 turn rather than 10 turn and the controller would need to be designed around higher currents of course.

    But, no reason your...
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    My bicycle found that point. Continuous power...

    My bicycle found that point. Continuous power wheelie capable from 0mph to 60mph. Top speed capable of higher than I like to go on a bicycle (triple digits).
    I can not use all of it's torque...
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    No problem. AC20 = 53lbs. 50hp, though in...

    No problem.

    AC20 = 53lbs. 50hp, though in my experience dyno'ing them at 50hp output they start having smoke rising up off the windings in about 10seconds, even with a good fan blowing through...
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    It does in an ironless motor (which is why they...

    It does in an ironless motor (which is why they use litz wire). In a motor with iron, the copper never has flux lines cutting through it, this is the job of the iron to attract and guide the flux...
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    Canyon carving is so much better without your...

    Canyon carving is so much better without your rear wheel getting jerked around on downshifts under braking. You can run that much closer to the limit safely. You never have that problem of exiting in...
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    Your ideal method to fit the most copper in the...

    Your ideal method to fit the most copper in the slot is to simply slide a solid bus wrapped in a thin film of kapton down the slot. (see, solid-slot motors, and the difficultly of controlling these...
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    Good question. What I wrote: "Likewise,...

    Good question.
    What I wrote:

    "Likewise, though no amount of changing KV in a motor through changing the number of turns, changing how turns are grouped in series or parallel, changing from Delta...
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    Also, if the motors are outputting identical...

    Also, if the motors are outputting identical torque and power, meaning the 100amp motor has twice the turns of the 200amp motor, then the heating is exactly the same between the two motors.
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    Every motor peaks efficiency at the point which...

    Every motor peaks efficiency at the point which copper loss is equal to all other losses. When you're at a lower power output, core losses are greater than copper losses, when you're at a higher...
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    Not at all. There is no free lunch. To cruise...

    Not at all. There is no free lunch. To cruise at a given rate, you need x amount of power. You can achieve that power by spinning your motor at a certain speed (say 1000rpm) and 20ft-lbs of torque...
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    No. If your motor is able to turn faster, the...

    No. If your motor is able to turn faster, the BEMF is higher, and you have the ability to draw more power from the battery for any given phase current limit your controller does. When you have a...
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    Please do explain how you gain efficiency by...

    Please do explain how you gain efficiency by adding more friction and components to drag. Particularly if this is in the assumption of using a lower torque higher RPM motor that will have high...
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    What if you took the same space, weight,...

    What if you took the same space, weight, complexity, and cost, of adding a tranny, but instead applied it to the motor? ;-) You end up with a higher power, higher continuous power, higher...
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