New motor for EVs - Page 1
Forum section: electronics / general

author: moflint
author_rank: Newbie
timestamp: August 29, 2022, 10:36:39 am
content: 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.

author: Zero999
author_rank: Super Contributor
timestamp: August 29, 2022, 04:24:40 pm
content: I read that somewhere. Yes, I'm also cynical. I very much doubt there's much room for improvements to motor technology.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 29, 2022, 04:54:03 pm
content: I saw that a few days ago in a... less well formatted location:https://imgur.com/gallery/yOxmBMD/comment/2260283877QuoteOh, apparently I was going to write that as a list, but never got to #2 hah. Stupid comments format.And in a sub-thread;QuoteAnyway, doubt it's anything remarkable, but a great sign in terms of personal/professional development.Bonus fan content..?Quote

author: tom66
author_rank: Super Contributor
timestamp: August 29, 2022, 06:13:45 pm
content: 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.

author: Zero999
author_rank: Super Contributor
timestamp: August 29, 2022, 06:47:37 pm
content: 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.phpAnother 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/ba24b67fc98bb3f65e616bfeda941069f185d50fhttps://www.researchgate.net/publication/269300854_A_dual-stator_brushless_doubly-fed_induction_motor_for_EVHEV_applications

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 29, 2022, 06:53:08 pm
content: Quote from: Zero999 on August 29, 2022, 04:24:40 pmSame here, and the fact that it would be relayed by shit orgs like the WEF doesn't smell particularly good either. This isn't a "big name", this is a huge pile of crap that should just get definitively ignored.More generally speaking, anyone jumping on the greenwashing bandwagon with bold claims about groundbreaking solar panels, anything related to EVs, in short, anything trendy regarding what is supposed to be the ultimate good for tomorrow's world is highly, highly suspect.

author: Wolfram
author_rank: Frequent Contributor
timestamp: August 30, 2022, 06:00:05 pm
content: Quote from: Zero999 on August 29, 2022, 06:47:37 pmThe Tesla model S (at least some versions) use a copper rotor induction motor, and the Renault Zoe used a wound-rotor synchronous with sliprings for the magnetization as far as I know. The latter was used to allow demagnetization of the rotor, allowing the use of the motor windings and inverter as a charger.Edit: some neat pictures of the Zoe rotor can be found here:https://paultan.org/2015/06/19/renault-zoe-new-electric-motor-cleon-plant/zoe-engine-plant-0040/. It looks like it would develop significant reluctance torque as well, like an IPM rotor.

author: tom66
author_rank: Super Contributor
timestamp: August 30, 2022, 06:19:41 pm
content: The Zoe's charger design is clever, but unfortunately it's quite inefficient. At 7kW charging rate, it only achieved 85% efficiency, throwing away a lot of energy compared to a normal OBC with integrated magnetics which would achieve upwards of 95%. It's no longer used on the Zoe as they have CCS (the only reason it was used originally was to support up to 43kW AC 3 phase charging, i.e. 63A per 230V phase.)Another car, the Hyundai Ioniq 5, can use the motor to boost 400V DC charging up to 800V for fast charging, when not connected to an 800V station. The Porsche Taycan uses a 50kW DC-DC converter to do this instead.

author: moflint
author_rank: Newbie
timestamp: August 30, 2022, 06:54:49 pm
content: Quote from: SiliconWizard on August 29, 2022, 06:53:08 pmIt seems this kid, Robert Sansone, is being used as the face of an advertising campaign for "truly sustainable vehicales" by WEF, like Greata Thunberg was for similar agendas. Why the WEF are pushing EVs is another question. I don't think they give a rip about sustainability, whatever that is.

author: Slh
author_rank: Regular Contributor
timestamp: September 01, 2022, 08:57:19 pm
content: Switched reluctance motors are a thing already (and have been for years). They're basically stepper motors which are designed for speed not position accuracy. They can be as efficient as PMAC machines but don't quite get the power density and their torque ripple is generally rather high. Compared to induction, efficiency can be better and I think power density is better but torque ripple is worse.The other issue is that there are lots of three phase inverters out there for PMAC and induction but not many for the weird 4 phase system required for switched reluctance so the controllers are expensive. The control algorithms are also a bit harder to implement.JLR did a Land Rover Defender prototype with one a few years ago but everything they've actually brought to market is PMAC

author: Zero999
author_rank: Super Contributor
timestamp: September 02, 2022, 08:59:22 pm
content: Quote from: Wolfram on August 30, 2022, 06:00:05 pmThe stator has two pole pairs, so is it single phase, or two phase?I would have thought having a wound rotor to create a DC field would burn up more energy, making it less efficient, than a rare earth permanent magnet motor? Perhaps it is less efficient, but not enough to matter?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 02, 2022, 09:30:46 pm
content: Maybe. Strictly speaking, it's extra dissipation that you wouldn't have with PMs. It might not be much: current can be reduced when less torque is required, giving reasonable efficiency in cruise.Also allows some relaxation of gearbox requirements, as the field reduction likewise reduces EMF. You need less of a VFD, or, it can spin much faster than available voltage at nominal RPM, if you don't mind that the torque is likewise lower.The harmonic losses due to the salient-pole geometry could be more important; no idea. Also depends how the stator is wound, I think.Likely it's three phase; 4 poles just means those phases repeat twice around the circle. So, 1800 RPM at 60Hz, like most commercial motors; what they choose to run it at is of course up to them.Could potentially be quite fast (thus power-dense) if the lams are thin. Thin lams would be a prerequisite of the charger mode operation. Or maybe not, given its embarrassing efficiency in that mode, heh. I mean, even if they're thin (like 0.07mm), the losses at some kHz are still considerable, so it's not like you have to switch very hard for that to be true, even if you work very hard to get the iron losses down (but while still usingironas such).Hm, I suppose if they're doing a charger mode through there, they probably PWM the field in normal operation, to adjust it; seems like a massive wasted opportunity not to, at least. So they might not be doing much VFD action at all; well, it's still required to avoid stator saturation of course, but above a certain frequency, voltage can level off (output waveform still sinusoidal -- or add back in whatever harmonics give least losses -- right, they don't necessarily need harmonic balance, nice) and field reduces instead.Tim