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Electric motors with no rare earths

renaultgroup.com

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Re: Electric motors with no rare earths

#151

Post by sofixa »

formerly_proven wrote: post #127
alephnerd wrote: post #19

Earlier quoted context omitted.

They share the same OEMs, and both are following the same ex-China automotive strategy. Renault has also been thumbing China recently for undermining EU manufacturing as well [0] while China has returned to using Wolf Warrior diplomacy against Europe [1][2][3][4] using the same rhetoric that the Trump admin uses. Of course, under the Xi admin China's foreign policy has always viewed the EU as inferior and a has-been…

> following the same ex-China automotive strategy Is that why Renault EVs (R5, Twingo) are wholesale developed in China? Doesn't seem very ex-to me, more an in- type of strategy.

Why do you think the R5 was developed in China? Renault have been quite open about all the improvements they had to make to their processes, development centres and factories in France to make it. The Twingo was partially developed in China.

Re: Electric motors with no rare earths

#152

Post by duffydotsvg »

adrian_b wrote: post #120

Unfortunately, their Web page does not say a single word about the important problems of their motors. The electrically excited synchronous motors have been known forever, but they had not been used in EVs because of 2 disadvantages. The first is that traditional EESMs require brushes, i.e. sliding electrical contacts, which are worn out by friction, so such motors require frequent maintenance for changing the brushe…

Amazing breakdown for someone (me) who knows literally nothing about how motors work.

Re: Electric motors with no rare earths

#153

Post by actinium226 »

WalterBright wrote: post #83
userbinator wrote: post #38

A historical pioneer in the complex technology of electric motors without magnets Those who know the history of electric machines will find the title and verbiage very amusing. Motors with no permanent magnets were the first practical ones, and at this point wound-rotor motors are over a century old. It's worth noting that some of the biggest motors have always been designed this way, because the size of magnets requ…

Long ago, when I was in Cub Scouts, one of the projects was to build an electric motor. The parts list was: 1. a plank to form the base 2. several 6 inch nails 3. wire 4. a tin can (as a source of sheet metal) 5. tape No magnets. But it worked perfectly fine when connected to a dry cell. Adventurous science lad that I was, I decided it would work better when connected to AC. So I attached a power cord and plugged it…

Username checks out.

Re: Electric motors with no rare earths

#154

Post by Devorlon »

giobox wrote: post #32

It's interesting that this is a brushed design. In the RC car community, brushless motors are generally regarded as superior, but those of course have the rare earth magnet problem. Technically the brushes can wear out, although there are claims they are good for 150,000-250,000 miles it seems.

It's brushless: https://www.evspecifications.com/images/news/6ec9484/additio...

Re: Electric motors with no rare earths

#155

Post by adev_ »

adrian_b wrote: post #120

Unfortunately, their Web page does not say a single word about the important problems of their motors. The electrically excited synchronous motors have been known forever, but they had not been used in EVs because of 2 disadvantages. The first is that traditional EESMs require brushes, i.e. sliding electrical contacts, which are worn out by friction, so such motors require frequent maintenance for changing the brushe…

> such motors require frequent maintenance for changing the brushes.

"Frequent" is all relative.

The Renault Zoe, 10y ago, was already using a synchronous engine with wired rotor. And most were going over 150kkm without any issues nor brush changes.

> because the electrical currents that circulate through the rotor windings must generate heat

Currently stator heat in wired synchronous engine is less a problem than in SynRMs with permanent magnets.

Most neodymium based permanent magnets start to be irreversibly damaged id they heat up beyond 100°C. That's currently why Tesla has such a good cooling system in their engine.

Wired rotor are bunch of copper coil, as such they are much more resistant to temperature gradients.

Re: Electric motors with no rare earths

#156

Post by Karliss »

bornfreddy wrote: post #132
adrian_b wrote: post #120

Unfortunately, their Web page does not say a single word about the important problems of their motors. The electrically excited synchronous motors have been known forever, but they had not been used in EVs because of 2 disadvantages. The first is that traditional EESMs require brushes, i.e. sliding electrical contacts, which are worn out by friction, so such motors require frequent maintenance for changing the brushe…

Interesting question, it looks like they are / will be brushelss: > Group will gradually embed new technological improvements from 2024 on its EESM: stator hairpin, glued motor stack, *brushless* and hollow rotor shafts. [0] https://www.evspecifications.com/en/news/6ec9484 That said, what sibling says about the maintenance problems is very true. :-/

All sources point that their 2025 models are still using brushed rotors. Here is a teardown video it's from Nisan car but it's using a Renault electric motor https://www.youtube.com/watch?v=BFmp9ODkCA8 .

In the picture at Renault website (section describing their next gen 2027 motors) you can clearly see the 2 slip rings on right side. That might be just a placeholder using their last gen motor, but I would expect that they would mention it if their next gen was brushless while the current one has brushes.

Brushless seems to be a thing that they have described as future work for at least 5 years but it's not there yet.

Re: Electric motors with no rare earths

#157

Post by conductr »

monster_truck wrote: post #141
throwaway2037 wrote: post #99

Earlier quoted context omitted.

> BMWs have a terrible record for needing expensive repairs. EVs? That makes no sense. EVs are so much simpler to maintain compared to ICEs.

They suffer from some of the same problem your likely modern fridge does, and then kick it up two notches. In the name of "safety", they have made design decisions such as integrating fuses directly into the very large and expensive control boards and making them non-replacable. Just in case this wasn't enough, they also tend to blow an OTP so that in the event that you have the know how to replace the fuses anyways,…

This is a company intentionally making sure EVs didn’t erode service revenues

Re: Electric motors with no rare earths

#158

Post by carefulfungi »

irishcoffee wrote: post #85
scheme271 wrote: post #82

Earlier quoted context omitted.

It's more than that though. Any repairs due to wear and tear or whatever, ends up being really expensive. Although you can probably reduce the costs a bit if you get the non-branded OEM part or potentially the same part from another manufacturer (e.g. the toyota supra uses a lot of bmw parts so if the toyota part might be cheaper than the same bmw part).

That was my whole point actually, the wear and tear is really minimal if you get regular oil changes. Things don’t just break and need replacing. Tires, rotors, brakes, those wear out. The tires are not cheap, rotors and pads aren’t crazy expensive and super easy to DIY. What other wear and tear things are expensive?

Owned a BMW. Had the audacity to use non-BMW windshield washer fluid. The fluid sensor broke; because in a BMW it’s a fancy sensor that is only compatible with specific washing fluids. Sums up my experience with that car. It was nice to sit in, though.

Re: Electric motors with no rare earths

#159

Post by mcdonje »

handstitched wrote: post #72
Rapzid wrote: post #67

Earlier quoted context omitted.

To a layman that seems like a really small efficiency tax if you can't get your hands on the magnets for some reason.

It's a small difference, but if you had a choice between "more efficient AND less maintenance" and "less efficient and more maintenance" then it's easy to see why the permanent-magnet solution is preferred.

Another comment said they're not using brushes, so they shouldn't need more maintenance.

Re: Electric motors with no rare earths

#160

Post by msandford »

tlb wrote: post #125
fc417fc802 wrote: post #71

Earlier quoted context omitted.

Not just some, approximately all of them. It greatly complicates the logistics of a black start. † Of course that situation has additional complexity due to the need for substantial additional power in order for the various fuel supply systems to operate but I digress. † https://en.wikipedia.org/wiki/Black_start

Generator excitation is not the hard part of a black start. You have to run coal feeders, blowers, and water pumps for an hour before you can spin the generator. Then you get power instantly upon applying power to the field windings.

And even that's not the hard part of a black start. The plant control is relatively easy. What's hard is grid coordination.

All generation and consumption have to be almost perfectly balanced every second of every day. And the power company doesn't have good addressability of load. Worse when you restore power to an area all their stuff turns on in parallel giving an inrush that could be 3x or more the steady state.

A black start is a very drawn out process of bringing generation and load online in a balanced way and with wait times between load increases for stabilization.

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