[nkaminar]

For those who do not know, new electric motors that run off of batteries are permanent magnet AC motors that are driven by a motor controller. The controller puts out variable frequency, multiple phase AC (alternating current), that powers the motor. These are used in all sorts of applications, including model airplanes, for which I am the most familiar. The motors use the rare earth magnets that are super magnetic.

For model airplanes the motors are 3 phase. The controllers and motors are super efficient. These motors, and lithium batteries, have almost replaced the glow fuel engines of our youth. Even for large planes like 1/4 scale. The controller frequency, and thus the motor rpm, is controlled by the radio control, so that the motor can be run from zero to maximum rpm with the throttle stick on the transmitter.

I believe that the inverter compressors that Brent talked about above has one of these super efficient AC motors. Although it could be another type of motor that oscillates, but is still super efficient.