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Comment by Rapzid | Hacker News Reader

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 near-doubling of energy loss - probably a healthier way to understand it when the efficiencies are all 90%+

Funnily enough if enough of that energy loss (heat) can be scavange, this wouldn't be nearly that bad for us living up here in the cold.

In most EVs motors are watercooled, so that energy can indeed be scavenged – problem is, during low-speed driving, the heat output is not high enough to get noticeably above ambient temperature.

Thermodynamically, heat is waste energy. EVs are so efficient that scavenging isn’t practical anymore; I’m not sure the temperature gets high enough to usefully extract the heat energy for heating. ICE cars obviously produce mostly heat so getting a radiator hot enough to heat the cabin is very easy

You can get about 2/3 as much output power for a given amount of waste heat and cooling capacity.

It's like how laptop power bricks used to be big and get hot, and now they aren't and don't.

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.

The actual alternative is induction motors, which are just a bit less efficient than PMSM and otherwise basically the same. Except that the frequency fed to them isn't exactly proportional to speed.

They've been used to great success since we had the needed power electronics to drive the electric trains of Europe.

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

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