Got any high-res pic of this? Very interested
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For our use ( and ebikes and other uses that the motor is subject to the elements) I think moving the heat to the magnets is the best, else you will just fill your motor with junk
Water cooling would be cool (pun intended), but customs motors are needed for that
My view is that if the amount of heat your are producing are making the motor overheat, the problems is not the cooling, every bit you cool is wasted energy and loss of energy
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Well. Which direct drive motor is stock off the shelf? Aren’t they all custom to an extent? And there is a fair share of stock water cooled motors (maytech has a few).
But the heat thing, there is a balance of size too. You can’t just keep sizing up motors until it runs nice and cool, because then you’re going to have to figure out how to strap two 50lb pumpkins to your 20lb board. Even high performance electric cars run water cooling.
Even at extreme efficiencies, you have to deal with heat with power. 95% efficient motor, pushing 5000 watts, is producing 250 watts of heat. Quite significant. And 95% is in unrealistic territory.
I felt like Enertion’s copper heat pipe was onto something. Except they stuck the heat pipe in a steel drilled hole. Had the stator have copper inserts that extends to the axle making contact with the heat pipe, then giving an actual mass and fins for the heat pipe to dump into, it would’ve been way more successful imo.
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I agree, the thing to look as you said is efficiency, if you are running in a low efficiency zone, cooling will work, but there are other things that you can change
One nice way to cool it would be tiny holes in the stator core itself, even a small amount of water can do wonders to move heat away
But is comes as a problem for me due to you have to mound radiators, pumps and all that
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I think the problem is that, no matter what you do, 1:1 drives will be less efficient than geared. Hence why no electric vehicle other than PEVs run 1:1 drive. All hub motors etc have way underrated continuous power ratings due to heat. Improving efficiency is easiest by spinning the motor faster and reducing gear ratio, which makes it a moot point. So alternative would be ways to remove heat faster, I think water cooling is just too much with the extra parts, but air cool, copper mass and heat pipes may be worth looking at.
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Yeah, you have to spin up the motor to the point where the core loses start to get significant
The thing is, there are other ways to make the core loses go up and bring the windings loses down, and that is what I’m playing with in my motor
The hardest part is to find the load profile for a given vehicle and optimize for that
This why I need logs to find it
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Transverse flux motor design seems the easiest way to get the most copper in.
A cooling system seems to me a lot of complexity and risk of breaking down. The hanger could be used as a great heatsink if only can get the heat there. I plan to press the end of the stator into the motor case wall with a thermal pad between. Copper to thermal pad to mild steel. Looking forward to see how it goes
How did it go when it burnt out @Skatardude10 ? In my experience a burnt out motor throws u.
Using 270c rated wire (new thing out there) and lrk winding to further isolate phases to avoid cross phase short
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It didn’t throw me, I was holding the wheels locked at 0mph against the wall and pumping the throttle. I probably should have let the wheels spin a bit.
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except if they put that same copper in the windings i doubt they’d need the heat pipe so i’m not convinced
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never tried that. Why?
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Discharge the battery / heat up the motors to test how fast the motors cool down. I don’t know how the phases in a motor work exactly but I’m guessing one or two of the phases were loaded disproportionately since I never let the wheels spin, and all the current was probably going into one/two phases.
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How quickly that happened? Was like suddenly or after you have been holding it for a while?
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Still wondering how foc works as it supposedly has all three phases powered. Waiting for someone on a forum to break it down for me. Surely have to get the back emf. If all phases powered at same time I’d think would be a much better motor.
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the foc torque nm = KT * 1.5 * (motor current or peak current per phase / sqrt(2))
so the ((copper loss per phase * 3) + (torque * rad/sec) = electrical wattage
KT = 60 / (2 * pi * kv)
copper loss per phase watts = (line to line resistance ohms / 2) * (motor current / sqrt(2))^2
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Doing bldc and foc tests show very similar kv and therefore Kt. It seems like ur saying the Kt would be 1.5 higher in foc
KT is tested in BLDC, but the torque in FOC is 1.5 * KT * “(motor current / sqrt(2))” = torque NM
motor current FOC = RMS current per phase * sqrt(2)
The kv can be gotten in either bldc or foc and could get a Kt from either. They’ve very close
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no the kv is tested in bldc at 100% duty at 0 motor current (faster than the motor spins on its own because the no load rpm is also the rpm of the motor when the peak back emf voltage produced by the motor equals the battery voltage)… the max rpm in foc is lower
at true no load speed in bldc, the back emf v produced by the motor equals the battery voltage, which is why there is 0 motor current and also why the motor can’t spin faster
in foc, the motor only sees the battery voltage at the peak of the sine waves, but in bldc it sees it the whole time at 100% duty, so foc spins slower but the KV is the same for both
the KT = 60 / (2 * pi *kv)
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To truly know the kv you spin the motor manually and get the voltage. Only way to get zero current. What that has to do with how foc works I don’t see
From the little I understand the three phases are powered and the voltages in two of the phases are half the third.
Makes sense foc would run cooler at highest torque as it’s one phase at full amperage and two at half, so one tooth saturates vs in bldc it’s two teeth at same high magnetic field. The same torque production in foc but using more teeth. Maybe. Where’s a dyno n thermometer
right spinning the motor to get the back emf voltage gives the same voltage/kv measurement whether you later spin it with bldc or foc, but the motor’s no load speed will be slower with foc