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2017 That whistle sound

2322 Views 7 Replies 5 Participants Last post by  MikeyCVolt
I typically drive with the radio at least at low volume but yesterday I did a whole trip in my 2017 LT with the radio off so I could talk to passengers. I noticed a whistling sound which happens only at one specific throttle position. It reminds me of the sound you get out of a cordless drill when you only press the trigger slightly and the motor makes a whistling sound.

Letting up on the throttle just a tiny bit or pressing it a little more just a tiny bit makes it go away. I'd say the throttle position where it happens is maybe 1/10 throttle, maybe less: about the point where you'd have it if you are trying to hold say 30 MPH.

So my question: I assume this is normal and this is typical of how electric motor power is modulated (like a cordless drill)? It's not very loud but it's noticeable inside the cabin with all the windows up.

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If the frequency of the inverter matches one of the chord frequencies of the chassis, it'll resonate through the motors and chassis and be much louder compared to normal. In addition, when you're maintaining speed instead of accelerating or decelerating, there's no "slip" (as it's called) in the motors (has to do with the magnetic field) and the frequency is a bit louder than otherwise.
I like this sound. Reminds me of a "turbo hiss." I was wondering if GM might have even purposely made it intentionally audible since it's only at high throttle. Some EV manufacturers have been looking at ways to provide more audible feedback to drivers accustomed to the controlled explosions of a gas engine.
I don't think it's intentional; it's just a result of the inverter current being much higher during high throttle. I do believe Toyota has engineered theirs to be intentionally audible, as it's way louder than any other hybrid I've ever heard, even in brand new Priuses. It's still very high pitched and soft, but I can hear a Prius pull up along side me with my windows up if my radio's off.
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