Whining Sound

[davidricardo86]

i-MiEV owners,

When you drive your car(s), do you normally hear what I can describe as a 'high pitched sound?' It sort of reminds me of an electric motor whine but more electronic... if that makes any sense? Please don't laugh, I am serious.

I guess my concern is that I imagined the i-MiEV to drive almost completely silent and mine makes this high pitched sound while driving. I can't remember if the last two i-MiEVs I test drove made that same sound as I may have been too excited or unaware of such 'high pitched whine sound' during that new experience. I'm going to try and record it for refference regardless.

...

So far, my i-MiEV has been flawless and a thrill to own/drive!

 

[kiev]

Occasionally i will hear that also. i think it is a normal electronic sound of the Pulse Width Modulation (PWM) circuit used in a 3-phase inverter. Nothing to be worried about, you just have young ears with no hearing loss yet, the noise will go away as you get older.

 

[wmcbrine]

When you drive your car(s), do you normally hear what I can describe as a 'high pitched sound?' It sort of reminds me of an electric motor whine but more electronic... if that makes any sense?

There's an artificial whine at low speeds (<22mph, I think), which is required by law, sadly (long story -- google "bell the hybrid", including the quotes). Other than that, I haven't noticed anything in particular... it's certainly much more quiet overall than even my Prius was, despite being poorly insulated against road noise.

 

[PV1]

There are three different noises that come to mind.

1. AVAS - A generated tone that alerts pedestrians of a moving vehicle. This is active from 0-25 MPH, and goes silent below two MPH with your foot on the brake or in Park.
2. Gearbox/motor whine - A turbine-like sound that is heard in a quiet vehicle (radio low or off) when accelerating or under regen. The sound under regen is different than when accelerating. Also, this turns into a steady high-pitched noise when at speeds over 55 mph.
3. Motor Drive Inverter - This is only apparent on one of my cars. Anytime the car is in a drive mode or reverse, there is a quiet high-pitched noise that is constant regardless of vehicle motion. The only time this stops is when the car is in Neutral or Park. To test for this, put the car in Drive with the radio off, but don't move. Then if you hear it, put the car in Neutral to see if it stops. If it does, it's the drive inverter you're hearing. Again, this is only heard on certain vehicles.

All three noises are normal. AVAS sounds more like a long-off train whistle echoing through the mountains.

 

[DonDakin]

Hi all,

On the topic of inverter hi pitch sound i noticed its much more noticable in our second imiev. The first one is very quiet.

Not sure why one produces a louder inverter sound then the other.

Anyone else experiance this ?

Don.....

 

[kiev]

When current flows thru a coil of wire, an inductor, or a motor winding, etc. it creates a magnetic field around the wire and thru the center of the coil. Each coil, loop or turn in the winding has it's own magnetic field, and when the current changes direction the magnetic field reverses also. These reversing fields will interact with each other to cause the wires to jump and move about due to the magnetic forces, and the movement of the wires will produce sounds and squealing noises.

The motor manufacturers wrap and tie the windings with string and coat everything with varnish in an attempt to limit the vibrating motion of the wires and reduce the noises. No two motors are wound, tied or dipped exactly the same, so the sounds can vary from one to an other.

my 2¢, kiev kenny

 

[DaveMiller]

The motor manufacturers wrap and tie the windings with string and coat everything with varnish in an attempt to limit the vibrating motion of the wires and reduce the noises....

To visualize how an electric motor is made, here is a Youtube link about making a Tesla motor. The motor part starts at the 5:10 minute marker.
http://youtu.be/Z0MFegHEkoQ

Dave
2012 Black Imiev
2012 Black Prius
Electric Bike
Gas Mower

 

[JoeS]

I moved this discussion into this 'new' thread - I think we've had it before but I couldn't find it.

IMO, the very slight high-pitched whine the OP mentioned would truly be imperceptible were it not for the quietness of our car to begin with.

DaveMiller, thanks for the link to that Tesla assembly video - hadn't seen it before.

 

[iwatson]

I love sarcasm! But others are offended by it! Sorry to put this on all of you, but it just popped in my head and I can't help myself!

I took a tour through the Amish communities in Pennsylvania once. Their vehicles make this odd clippity-clop sound! Very annoying!

The i-miev is serenely quiet in contrast, and far less polluting! But it does make some noise!

 

[Don]

These reversing fields will interact with each other to cause the wires to jump and move about due to the magnetic forces, and the movement of the wires will produce sounds and squealing noises.

The motor manufacturers wrap and tie the windings with string and coat everything with varnish in an attempt to limit the vibrating motion of the wires and reduce the noises.

If any of that were even *slightly* true, the 'jumping wires' would quickly rub the insulation off of each other and the motor would short out and fail

Trust me, we have no 'jumping wires moving about' making noise in this car - None at all

Don

 

[kiev]

oh okay, i guess wikipedia is wrong too, http://en.wikipedia.org/wiki/Coil_noise

But don't forget your earplugs when you go git yur mri done, banana mode

too bad i wasted all that time and money being a college puke to learn physics and stuff that ain't true...

The biggest whining sound i've ever heard is on the tesla forum with dudes crying about not getting their full 691 hp in the dual motor cars...lol

 

[PV1]

Referring to my earlier post:

3. Motor Drive Inverter - This is only apparent on one of my cars. Any time the car is in a drive mode or reverse, there is a quiet high-pitched noise that is constant regardless of vehicle motion. The only time this stops is when the car is in Neutral or Park. To test for this, put the car in Drive with the radio off, but don't move. Then if you hear it, put the car in Neutral to see if it stops. If it does, it's the drive inverter you're hearing. Again, this is only heard on certain vehicles.

I believe this is called coil whine. KiEV is on the right track with this. Some laptops even have this problem. The high frequency of PWM voltage converters can cause a coil or other components to vibrate at a high frequency. This vibration causes the high pitch whine that you hear, acting almost exactly like a speaker. So, wires aren't "jumping" per se, but just slightly vibrating from magnetic forces. They aren't vibrating far enough to allow the insulating material between them to wear off and work away, either.