It's a nifty motor, and might find application in non-automotive applications. To read that some of the control circuitry now in use needs liquid cooling is rather discouraging: that's a lot of wasted energy. One other point: recovering braking energy isn't merely a matter of being able to lay hands on it at the motor. You have to do something with it, typically put it into your battery. Trouble is, batteries don't recharge in seconds, and some fraction of that energy is lost. Some type of supercap might be indicated.
A very informative article on hub motors for EVs. I would have liked this article to contain some graphics - Torque speed waveforms and schematics showing how commutation is achieved. Some comparative charts showing the efficiency and range improvement over other similar motors will also add value to this article.
By reading this article my thoughts go back to the VCR 's head drum direct drive and capstan direct drive motors. The same design in a small size and lower power it was working there. But here this motor has to meet many more things as shock proof, water proof,dust proof,heat proof and carry atleast two times more than the specified weight.
This seems awfully naive(full blame is on EET editors for accepting the piece), almost like it was written by a high school kid, and there's nothing novel or "nifty" about it for all you guys caught agasp in the comments section - do the math on the cost of a printed circuit motor with enough layers to be both mechanically and electromagnetically sound, appropriate layup Tg, and copper thickness and you very quickly have a $8000 weak torque motor per axle.
The Maker community have been building axial flux alternators and generators (which is what this is) for well over a decade for wind power and have figured out how to bury windings ECONOMICALLY without the excessive cost of prepregs and laminating presses. Read Hugh Pigot's book if you want reality and cost-effectiveness versus fantasyland equation based nonsense.
The issue of flux saturation and reluctance in the air/epoxy gap also is not addressed in this math exercise, which will seriously limit the mag field contribution of the 1 Tesla magnets that are being assumed in force calculations.
To suggest fixing the axle to the frame of the vehicle to "simplify shock absorbers", is extremely naive as well as is the notion that much less than 10cm is a large enough axle stub to support a 1.5 tonne vehicle hitting a pothole...LOL this has the same shaft diameter as a 1/2HP furnace blower motor. Clearly, the author's never designed autmotive drivelines; apparently just a dreamer with a glass of wine and a fireplace and enough engineering knowledge to be reckless.
And, as any HIGH SCHOOL kid can tell you, it's 1/2 m*v*v for energy, which is VERY significant energy as anyone who's hit a wall at 50km/h can tell you....you don't dump it into a resistor, especially for a vehicle carrying limited stored energy on board to start with...streetcars used to do that one 75 years ago to heat the cabin. We are supposed to be cooling the planet, not heating it with printed circuit motor braking systems or failing to recycle it for later use in moving the vehicle.
Has anyone done the math for the commutation "switches" in this wundermotor? For a 20A "starting torque" you are dissipating 400*5.6 or 2.25kW PER MOTOR, or 10kW of power in the switches for 4WD. Now add in your winding resistance. It gets a lot worse when you are using the 'sports car' 30A example that was calculated in a prior page - almost DOUBLE. The Chevy Volt only carries 16kW of batteries....
Thanks for the laughs - can't wait to see part deux. A new low, EET; a new low.
0.5mm looks like about 14 oz copper. My VERY limited experience with making coils out of PC boards was with 4 oz copper, and even that was a lot more expensive than making it the usual way. So, what is the attracttion for using PC stock?
Please add some outlook to your criticism:
What about SRM?
Why is the mass per weight so bad with current electric motors?
Please allow for some innovation - even in early stage- My guess is that electric mobility will fail with current low RPM motor designs.