Heard the same whine yesterday (initially blamed on traction control) in the non-perf Silver car in Palo Alto as my host, Nick, punched it in a straight line. Matt, our co-pilot, confirmed the frequency bit below and that they are working on changing it.
Thought I'll put together posts from the Get Amped threads about this for discussion here:
Thought I'll put together posts from the Get Amped threads about this for discussion here:
Here's the video Francis posted earlier in the thread. Start at 7:35, this is where I'm making the right-hand turn. I started to make the turn and then stepped it to the floor. Somewhere around 20-25 I heard that muted tone - I'm guessing that same "whine" you heard. So I don't think it was breaking loose in the turn, but rather when I really romped on it. I could feel I broke them loose.
http://www.youtube.com/watch?v=mVyhjJcQhG8
I heard that same high pitch tone in the MSP I drove every time I punched it straightline, too. I did several "regen down to 30 mph, punch it up to 60 mph" runs along the highway and heard that sound each time at max motor exertion, so I didn't think it was related to the traction control. Seemed more related to inverter/current delivery.
Then again, I suppose it's possible the car started detecting slip during hard straightline acceleration as well. That's a lot of torque to put down in two wheels. Some lightweight big block cars like the Corvette Z06 have no problem breaking traction in a straight line at speed after a downshift. I'd be impressed to learn the Model S at 4600 lbs can break traction under acceleration at 30mph!
From your explanation - this is the motor controller changing the switching frequency. The controller is more efficient at lower frequencies but also louder. It probably works on a higher switching frequency during during "normal driving" (within the continuous rated motor-controller power/current) for silent operation. When you floor it and the looses (heat) increase, the controller changes the frequency in order to increase efficiency. You will hear that as a whine from the rear end of the car.
At the Palo Alto event today, we were told that there is a connector through which very high current passes under heavy acceleration. It's AC, and the particular frequency causes the connector to physically vibrate, which is audible in the car. Apparently, they are considering modifying the frequency so that the connector will not whine audibly.