Elon Musk explains Electric Motor Cooling

Elon Musk talks coaxial rotor cooling in the Tesla, peak power and sustained sufficiency.

Elon Musk: "The bigger challenge is actually cooling it effectively and then particularly cooling the rotor, cause you've got this rotor

going at like 18 000 rpm, so the Model S we coaxially cool the rotor in order to have high steady state. So, also for electric

motor it's easier to get peak power for a short period of time, it's hard to have sustained peak power and - cause you overheat -

and then it's hard to get high effeciency over a complicated drive cycle. Those tend to be the problems we wrestle with, more

than, say, the peak power. We can get peak power pretty easily, but sustained power and efficiency over the drive cycle are hard."

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The bigger challenge is actually cooling it effectively and then particularly cooling the rotor, cause you've got this rotor

going at like 18 000 rpm, so the Model S we coaxially cool the rotor in order to have high steady state. So, also for electric

motor it's easier to get peak power for a short period of time, it's hard to have sustained peak power and - cause you overheat -

and then it's hard to get high effeciency over a complicated drive cycle. Those tend to be the problems we wrestle with, more

than, say, the peak power. We can get peak power pretty easily, but sustained power and efficiency over the drive cycle are hard.