openinverter forum

While I can happily announce that even my wife is no longer afraid to drive in Touran, she does have a complaint. She says the drive noise is quite disturbing. Actually more disturbing than in the old industrial motor Polo.

Now my own ears are impaired a bit and don't pick up high frequencies unless I turn my head towards the noise source. And indeed the Nissan motor whines quite noticeably under load. With good hearing I can imagine this to be disturbing. Of course there is also noise in Polo but less pronounced and lower frequencies. Both inverters run at 8.8kHz.

Has anyone noticed that synchronous motors are more noisy? Maybe due to cogging or something? It's not transmission noise as you can hear it out of gear also.

How is it in OEM cars? I now for sure in e-Golf you can't hear a thing.

There is a noticeable difference in 'noise' level when a Tesla drive unit is fitted with the open inverter controller board. I've always assumed this is because of the switching frequency. Is it possible to run the Touran at a higher frequency to see if your wife thinks it's better?

Hm... I have run Leaf motor with 10khz with Paul's inverter and it sounded like I was in the shower.
Leaf motor whines quite a bit. But in pug insulation is really good and radio increases volume automatically with speed .

It sounded like shower??
Yes I can try changing the frequency. 17.6kHz will make the inverter run rather hot, but should be ok for a quick test. And I can see if 4.4kHz makes it louder.

Yes it sounded like rushing water while pwm was active. I remember I saw 10khz on scope.
But maybe you could setup STM32 to vary pwm frequency a bit so as to be more pleasing to the ears. But really Leaf whine is quite loud. Maybe you could use better insulation material for motor/transmission mounts... Chassis resonates from motor mounts.

Kevin Sharpe wrote: ↑Fri Jul 17, 2020 7:35 pm There is a noticeable difference in 'noise' level when a Tesla drive unit is fitted with the open inverter controller board. I've always assumed this is because of the switching frequency. Is it possible to run the Touran at a higher frequency to see if your wife thinks it's better?

The noise does seem pretty close to a 10khz tone which would support that. It has been my theory as well. It’s almost comical the number of “experts” that claim its bearing “milling” from videos.

Hm... Right now i run Leaf motor with Lebowski control and pwm is set at 6kHz. This was found the best frequency by Arlo and i find it runs really good there.
Motor inductance value is supposedly 178uH and its phase internal resistance is supposed to be 48mOhm. But there is a lot of diversity there.

So just got around to testing. Temporarily set the pwm frequency to 17.6kHz. Wife says noise is unchanged. So must be something mechanical.

What does the motor waveform look like when driven as a generator?

johu wrote: ↑Sun Aug 23, 2020 2:50 pm So just got around to testing. Temporarily set the pwm frequency to 17.6kHz. Wife says noise is unchanged. So must be something mechanical.

Well, it could be the motor coupler is too tight and you hear the metal horns squeezing the plastic in between. But that would mean motor is pulsating power even when it is driving!

I still have this rubbery sound and vibration in my traction. I traced it to a siezed bearing inside LH inner CV joint. I still need to take it apart and inspect it. I found this when i lifted my car up and tried to move both wheels. LH was sticking a bit. It turned out even that was enough for the shaking to propagate. I recommend you visit a shop with a lift.

SciroccoEV wrote: ↑Sun Aug 23, 2020 6:31 pm What does the motor waveform look like when driven as a generator?

You mean il1/il2 currents? Sinusoidal the last time I checked You think it could be torque ripple?

arber333 wrote: ↑Sun Aug 23, 2020 7:24 pm Well, it could be the motor coupler is too tight and you hear the metal horns squeezing the plastic in between. But that would mean motor is pulsating power even when it is driving!

I'd say it's the typical running noise of the Leaf motor that you hear on numerous videos. Just under load it's much more pronounced. When cruising on a level road it is unhearable. To me the noise is not disturbing but it seems to contain some high frequency component that I do not hear.

johu wrote: ↑Sun Aug 23, 2020 8:42 pm
I'd say it's the typical running noise of the Leaf motor that you hear on numerous videos. Just under load it's much more pronounced. When cruising on a level road it is unhearable. To me the noise is not disturbing but it seems to contain some high frequency component that I do not hear.

Could be your motor/transmission mounts. Can you check they are free to move when you push down on the motor? If even one would be touching some chassis part every vibration would propagate into the cabin.

Have you considered recording the noise using a good microphone and recording device? If I had this problem I'd point my Zoom H1 at it and upload the result here.

do you have a vibration transducer that you could hook up to a data recorder or oscilloscope, perhaps use a second hand loudspeaker as a vibration transducer? try measure vibration of different surfaces within your motor transmission system?

celeron55 wrote: ↑Mon Aug 24, 2020 4:03 am Have you considered recording the noise using a good microphone and recording device? If I had this problem I'd point my Zoom H1 at it and upload the result here.

Haha! Lets not get caried away here . Though it has a precedence. I actually flew on a turboprop airplane that was using active vibration damping technology. Saab 2000 is quite an expensive airplane for a turboprop. I remember when we were at flight level i couldnt pickup any vibration from my seat. It was very comfortable. Then i leaned from my aile and all of a sudden prop vibration would hit me. They were using speakers on a halfh frequency to get into the flight level harmonics so passangers would be more comfortable. If you would use a microphone a uC and a marine speaker inside cabin you could actually do this .

First i would still observe motor mounts. Could they sag under the motor/inverter assembly weight so that center bushing would be allowed to touch the outer case? It would mean you have to replace them.
As a trial remedy You could lift the motor a bit (to releave pressure on the mounts) and squeeze the black gasket sealant between rubber and bushing so there would be less air. When it solidifies this mount would be harder but would also behave differently with frequency. The old engine had to be suspended against 3D vibrations. You now only have 2D vibrations: Axis direction and fwd - rev direction. And they are on much higher order than before.

Is vibration changing with motor or with driveshaft RPM? You can shift and use 2nd to spin the motor faster or 4th at lower RPM and ask Ingrid how it sounds.
I remeber Arlin uses a BMW driveshaft rubber dampener to interface his two motors. Maybe you could set up your coupler that way. It is also a standard BMW part you can buy if it goes...

If it changes with driveshaft take a look at some old VW cars. They had rubber dampeners on the driveshafts just for that. Its a soft rubber installed at the halfh shaft.
https://www.scirp.org/pdf/EPE20120400004_37611614.pdf
Maybe finding some in scrap yard and installing them would help?

A

Audio recording is a good call IMO. It's quick, cheap and easy; and if there's anything in there that's producing a tone then it'll at least rule out a few possibilities.

It wouldn't be a problem for my Mrs, She'd just turn Ed up.
Ed Sherran that is.

Today we found a surprisingly simple "solution" for the problem. So the whine is only really pronounced once you go over 90 km/h in 3rd gear. Shift to 4th and you can drive in relative silence till 120 km/h or so.
Will still try to track down the noise. Just wondering, is anyone with a stock conversion (i.e. using the stock Nissan control board) hearing this? It starts at around 5000rpm. Just wondering if it could also be caused by the oscillation of the field weakening controller.

johu wrote: ↑Sun Aug 30, 2020 8:55 pm Today we found a surprisingly simple "solution" for the problem. So the whine is only really pronounced once you go over 90 km/h in 3rd gear. Shift to 4th and you can drive in relative silence till 120 km/h or so.
Will still try to track down the noise. Just wondering, is anyone with a stock conversion (i.e. using the stock Nissan control board) hearing this? It starts at around 5000rpm. Just wondering if it could also be caused by the oscillation of the field weakening controller.

Then it could be transmission?
What does the 2nd sound like at more than 5k?
I noticed with old cars transmissions 3rd and 5th bearings can be worn and barrels can Humm because of wear.
With large cars it's the 5th since they are mostly used long distance and with small urban cars it is 3rd which is worn.

Interesting idea, I just went out to make a demo video (will upload tomorrow). I watched it several times and found the whining starts at 5300rpm in 3rd and at 4500rpm in 4th, bot at full load accelerating uphill. Will test more later.
There is also a hum, most pronounced at 3000rpm on regen. But thats not on the video. Need to work on audio quality anyway.

I'm running the stock control board and there's no noticeable extra sounds starting at 5000rpm.

There's the very high pitched switching whine which smoothly varies with torque, and there's the transmission noise which smoothly varies with rpm and each gear sounds different. Additionally I have some differential noise at around 80km/h - I guess the van has been driven a lot at that speed.

So, early release for thread participants: as I accelerate on the Autobahn you can hear said noise as I overtake the silver VW Lupo:


Go Pro seems to throttle down audio eventually because it becomes hard to understand me talking

Sounds like normal transmission noise to me. I'd probably select a taller gear for the highway to get less of that noise. Maybe it's unusually loud? Difficult to tell from a video.

I got really loud "regular" transmission noise when I accidentally axially loaded the transmission input shaft.

celeron55 wrote: ↑Wed Sep 02, 2020 7:07 am Sounds like normal transmission noise to me. I'd probably select a taller gear for the highway to get less of that noise. Maybe it's unusually loud? Difficult to tell from a video.

I got really loud "regular" transmission noise when I accidentally axially loaded the transmission input shaft.

Me also. When i experimented with side load barrel bearings. Clutch loades motor bearings from the side and when i tried to shift that load would hold the bearings in. Otherwise in normal use my bearings would sing really loud. In the end i replaced them with normal ball bearings. Albeit the ones that can take significant side loads.

Ok, so you think the noise was present in the petrol car also, just that you don't hear it because a petrol motor makes much more noise at 5000 rpm. So maybe there is a point to using 4th or even 5th gear on highway driving. Will keep experimenting.