Join the discussion
Write your take first — we'll ask for email only when you're ready to publish.
- Hacker News
- How soon to see rare-earth-free paired with CATL Sodium batteries? Seems a price war, range war is imminent.by delfugal
- "At the same time, China is also the world's leading producer of electric cars..."
Kind of interesting for a professionally branded company to use "..." like that
by E-Reverance - Clearly making a motor with induced magnetic fields both for the stator and rotor isn't the innovation here, since a large fraction of industrial motors do not have permanent magnets.
I would assume the innovation here would need to be making it small and efficient for any meaningful torque output? Usually when you see claims of a 93% efficient electrical motor its the result of taking an absolute beast of a 2kW machine and operating it at 400W. Does anyone have insights into what Renault are doing here?
by dcanelhas - 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.
by giobox - Broader point is this: Middle East created oil crisis back in 70s. Since then US economy has grown enormously while it's still using pretty much same amount of oil, imported or otherwise. They shot themselves in their foot. Iran is doing this now, telling the world to avoid Hormuz. They will learn to do that.
China is doing that by blackmailing countries with rare earth.
Answers will be found. Especially as some of finest brains across 2 continents + Japan are very interested in doing it. In the past, China could flood market at right time to make alternatives unviable. But that trick has worn off.
In this context, 92% or even 80% efficiency of permanent magnets is no big deal. It'll not be the answer to every use case but will satisfy many and limit demand.
by kopirgan - BMW also makes rare-earths-free motors for their EVs and - at this very moment - theirs are far more advanced. They offer almost twice the power (up to 300kW vs 160kW) and are on a 800v architecture.by bgarbiak
- 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 required would make them both too expensive and dangerous, and still not powerful enough for their size; a field coil can generate a field that's only limited by the current and resistive heating of the winding, but rare earth magnets have fixed limits on field strength.
by userbinator - 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 brushes.
It is possible to make brushless EESMs, but they require a rotating transformer and a semiconductor rectifier inside the rotor.
The second disadvantage is a lower efficiency than with permanent magnets, which cannot be improved so much as to match PM motors, because the electrical currents that circulate through the rotor windings must generate heat. The lower efficiency also makes cooling more difficult.
Renault says that their EESMs have an efficiency of 92%. This is a good efficiency, even if not as good as attainable with permanent magnets. Losing a few percents in efficiency is an acceptable compromise for avoiding the use of expensive and supply-constrained chemical elements.
What I wonder is whether Renault reaches this 92% efficiency with EESMs having brushes, or with brushless EESMs, and this is what I would have liked to read on the parent Web page.
Brushless EESMs usually had a lower efficiency, so 92% would be impressive for them, while it would look normal for EESMs with brushes.
If Renault has succeeded to make a brushless EESM (i.e. maintenance-free) with an efficiency of 92%, that is something worth to brag about. Otherwise, making a traditional EESM would not be great news, because everybody has avoided those because of the maintenance problem.
by adrian_b