General > General Technical Chat
New motor for EVs
moflint:
I've seen articles recently about a kid who invented a motor to transform the EV industry. If you search for "robert sansone motor" you'll find a bunch of them. I'm not a motor expert but something doesn't quite add up. I mean, hats off to the kid for his knowledge and skills at 17 years old, but these are big claims and to my knowledge no one else has verified them. It is said to be a 'new motor', but at the same time it's a modification on a synchronous reluctance motor (SRM). Instead of air gaps on the stator he is said to be using 'another magnetic field' - electromagnetic as he says there are no permanent magnets in the motor. While it might add more torque I can't see how it can simultaneously be more efficient because of the switching losses in producing the extra magnetic field(s). And I can't see how this would not have been tried and tested in the past because it's so obvious a mod. Yet he says it is 31% more efficient than a simple SRM while producing 39% more torque. This is a bold claim as there already exists magnet-less SRMs of over 98% efficiency (ABB) with many over 90%. Please don't say I'm being hard on the kid. I applaud his efforts. But I don't understand how these big-name organisations like the World Economic Forum and the Smithsonian are publishing these claims without any empirical validation.
Zero999:
I read that somewhere. Yes, I'm also cynical. I very much doubt there's much room for improvements to motor technology.
T3sl4co1l:
I saw that a few days ago in a... less well formatted location:
https://imgur.com/gallery/yOxmBMD/comment/2260283877
--- Quote ---T3sl4co1l • 5d ago
As an EE, my critique: 1. Sounds great, but read down a bit.. "[compared to] traditional synchronous motor" -- IOW stepper. Steppers aren't
very powerful, or efficient -- they're mainly specialty where the static position holding/braking force is valuable, like CNCs.
Optimizing one a bit ("37% more than" 65% = 89%), is still a LONG way to go before EV application (95%+!!).
Which, research is being done in such applications -- the flux density and thus torque density of reluctance motors is quite poor, but,
that just means we can spin them faster. Instead of a 1750 RPM induction motor, or 1800RPM PM sync. motor, we can do like 50k RPM.
At fuck all torque. But geared down (given a gear train efficient enough -- also not a given at these speeds!), that can still be a win.
We can use materials with very low core losses, like ferrite, to get high electrical efficiency and thus good power density.
This differs from traditional DC or universal motors, which are brushed and have quite high losses, while running fast (~30k RPM).
The AC drive is made possible by cheap, abundant semiconductors; even say 10kHz waveforms (600k RPM!) are trivial.
--- End quote ---
Oh, apparently I was going to write that as a list, but never got to #2 hah. Stupid comments format.
And in a sub-thread;
--- Quote ---It's probably not very remarkable in the grand scheme of things, but doing it at all suggests a greater understanding than your grade school
"magnet and spool of wire on a nail" demo. I'm guessing he's at least got a couple machine tools, and maybe knows FEMM (field simulator).
Likely a long and useful career ahead of him!
--- End quote ---
Anyway, doubt it's anything remarkable, but a great sign in terms of personal/professional development.
Bonus fan content..?
--- Quote ---tylerthetoddler • 5d ago
It's not magnet free. You can't make a motor without magnetic fields. It's expensive-permanent-magnet free.
T3sl4co1l • 5d ago
As an EE, I understood it to mean PM-free. But that could be worded better, I agree. eeeeeee.
SamuelPenning • 5d ago
[Extra Fabulous panel]
Icemountainwaterbottle • 5d ago
--- End quote ---
tom66:
So the inventor claims it's 31% more efficient, but if it went from say 97% efficient to 98% efficient, you could say the losses reduced by roughly 33%. Perhaps that's where such a fantastical figure comes from. I don't see how the motor can be 31% more efficient in absolute terms because even the worst performing EV motor is in the mid 90's at ideal torque and at least the low 90's when at low or high torque.
Zero999:
The main advantage appears to be the lack of expensive permanent magnets, which need to be rare earth for a powerful motor. There are other possible alternatives which have been looked at, but as far as I'm aware none have been used for any all EV.
Induction motors with copper bars have also been touted as a replacement for rare earth magnet motors. I believe they're slightly less efficient and don't quite as have as much starting torque, but they're good enough and are easier to drive as they don't need positional feedback.
https://www.copper.org/environment/sustainable-energy/electric-vehicles/archives/performance.php
Another option is a doubly fed induction motor. It works like a doubly fed wound rotor induction motor, but the rotor is coupled via a rotating transformer, rather than slip rings and brushes.
https://www.semanticscholar.org/paper/Analysis-and-Test-Results-of-a-Brushless-Doubly-Fed-Ruviaro-Runcos/ba24b67fc98bb3f65e616bfeda941069f185d50f
https://www.researchgate.net/publication/269300854_A_dual-stator_brushless_doubly-fed_induction_motor_for_EVHEV_applications
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