Electric motors with no rare earths

Post by ben_w » Sat, Jun 13, 2026, 6:48 PM UTC

wolfi1 wrote: post #196

adev_ wrote: post #155

Earlier quoted context omitted.

> 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…

150kkm - wouldn't that be 150 Mm?

Post by ErroneousBosh » Sat, Jun 13, 2026, 7:59 PM UTC

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…

Post by teamonkey » Sat, Jun 13, 2026, 9:32 PM UTC

runeks wrote: post #200

torginus wrote: post #176

Earlier quoted context omitted.

Munro took apart a Nissan Ariya which has this exact kind of motor. The maintenance is basically removing a tiny cover and replacing the tiny and cheap carbon brushes every 100k km or more. It's basically cabin filter level maintenance. And they said that PMSM motors are more efficient at low RPM, but their coils get saturated at higher RPMs meaning they lose efficiency at highway speeds (which actually affect the ra…

> [...] but their coils get saturated at higher RPMs meaning they lose efficiency at highway speeds (which actually affect the range number people car about). This seems like a big disadvantage. Highway is exactly where EVs fare worst compared to ICE cars. I wonder if this could be solved by introducing a gearbox? I know the new Mercedes CLA (EV) has two gears, the second gear being optimized for highway speeds. But…

Post by sinaa » Sat, Jun 13, 2026, 10:23 PM UTC

Onavo wrote: post #3

The main difference between this and your typical AC induction motors (also magnet free) is that this is a DC motor so you need a commutator. Your AC induction magnet free motors are very similar to drone motors in that you don't have any electrically active moving parts like slip rings and commutators. But for AC induction there will be a slight lag (known as slip).

Post by kopirgan » Sun, Jun 14, 2026, 1:19 AM UTC

jfengel wrote: post #178

kopirgan wrote: post #172

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 f…

In the long term solutions will be found, but in the short term they can gain an enormous bargaining chip. If food prices double because we've burnt the last drop from the Strategic Petroleum Reserve, the administration will give them just about anything they want to avoid utter political destruction. The game theoretic definition of a threat is something that harms you, but harms them so much that they will avoid fo…