[adev_]

> 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.

[wolfi1]

150kkm - wouldn't that be 150 Mm?

[halper]

Yes, you are correct. As the SI brochure states: "Compound prefix symbols, i.e. prefix symbols formed by the juxtaposition of two or more prefix symbols, are not permitted."

Unfortunately, almost no one uses SI units and/or prefixes correctly.

[taffydavid]

I have another alternative: you could simply prefix the km with ,000

[AngryData]

Meh, units should be used at the convenience of us, they are all arbitrarily defined to start with. We still use lots of non-si units, like AUs, minutes seconds and hours, degrees and arc units, or whatever else. Conversion is easier than ever today so I think units should be adapted to the application and use more fractional units when appropriate.

[ben_w]

Sure, also 1 mAU and 0.5 light seconds, but treating km as a base unit and prefixing it with another k isn't too uncommon a misuse.

[bibelo]

it's also 150 000 000 meters