Sound dampening for sharp/abrasive motor sounds?

[polyphonic54]

I am looking for products that can be added to the engine bay of an EV to quiet the motor and inverter noises. High frequency motor whine tends to grate on my ears. The noise is in the 1000-5000 Hz range.

Has anyone attempted this type of mod? I have noticed that high frequency noise is a persistent complaint with many EVs, but I am having trouble finding examples of mitigation.

The primary concern is interfering with airflow or causing heat build up around the inverter. Otherwise these high frequencies are very treatable, in theory.

 

[mk677]

the best you could do is to try to sound proof the areas where the drives are located but I don't think that you will be able to accomplish a full deadening of the sounds from the motors

 

[GtiMart]

Have you looked at noise cancelling technology instead of insulation? Maybe that would be enough to reduce your pain.

 

[polyphonic54]

the best you could do is to try to sound proof the areas where the drives are located but I don't think that you will be able to accomplish a full deadening of the sounds from the motors

Yes that's what I was thinking too. I bet the OEMs could engineer a solution that makes it imperceptibly quiet like in the Mercedes EQC, but I would settle for a reduction.

Have you looked at noise cancelling technology instead of insulation? Maybe that would be enough to reduce your pain.

I haven't looked in that direction yet, but from what I gather those systems can be expensive and tough to tune. Not ruling it out though.

If this sound were produced by a houshold appliance I could mitigate it with acoustic cotton. That material would easily soak up those high frequencies.
BMW makes these acoustic foam engine covers. I think extra dampening material under the hood near the motor and inverter is the right approach, but I'm wary of damaging something with heat buildup.

 

[jacie6056]

Yes that's what I was thinking too. I bet the OEMs could engineer a solution that makes it imperceptibly quiet like in the Mercedes EQC, but I would settle for a reduction.

I haven't looked in that direction yet, but from what I gather those systems can be expensive and tough to tune. Not ruling it out though.

If this sound were produced by a houshold appliance I could mitigate it with acoustic cotton. That material would easily soak up those high frequencies.
BMW makes these acoustic foam engine covers. I think extra dampening material under the hood near the motor and inverter is the right approach, but I'm wary of damaging something with heat buildup.

I tried different material like acoustic cotton, foam or 3M thinsulate before. It did cut away a lot of 2k frequency sounds. However I end up removed it all since I am worry about the mold build up for the long-run

I don't think the heat matter that much since the electric motor use the coolant for heat management. Also I had seen other EV like Bmw i4, rivian, EQS, etc. They all have some NVH foam to cover the whole drive unit