Maybe try to adjust the switching frequency on the VESC?
The now discontinued ARC200 controller made a big deal in their advertisements that “23.4kHz switching frequency for zero audible PWM noise”
Also this discussion
On vesc 6+ i can hear it faintly at 25khz and only on low battery at 30khz. It almost sounds like a wheel is slowly losing air so it’s quite odd
25Khz is quite a good frequency for the typical skate outrunner.
This sounds very interesting. The switching frequency is set at 25kHz. I wonder if I should try turning it up or down.
Let us know how that works!
Looks like that FSEC 7550 uses 3 phase shunts, so you should be able to increase it quite a bit. Give 20 & 30 a try to see what noise it makes. You can also turn on “Sample in V0 and V7” at 20, 25, and 30 to see if it makes a difference.
Also:
Phase shunts do offer a benefit of doubling the sampling frequency which makes it easier to move into the inaudible range but we need to do some tricks before it’s possible to run 45 khz pwm sampling v0 and v7 without maxing out CPU.
Interested in the results!
Heya, switching frequency won’t do shit for motors resonating. Switching frequency at 30khz mutes what i can only describe now as a fridge running sound, kinda.
As for the actual issue. I had freerchobby motors that were resonating at 28 and 31mph each, really fucking annoying as all london roads are mostly all 30mph. Solution?
Changed from freerchobby 190kv (10/47 with 9 inchers) to flipshit 140kv (12/47 9 inchers) and that resonating frequency is well above my max speed now. They run way cooler as well. Roughly in tune with heatsink exposed vescs, where shitchobby ones were at 85°
I was wrong about the switching frequency setting. The Ubox is actually set at 40kHz! I turned it down to 25 kHz and set “Sample in V0 and V7” to true. It does seem to have reduced the problem. It’s more of a whine than a blood curdling scream, and it doesn’t last as long. Before it lasted clear from 25-30mph. Now it seems to be right at 26 mph. I’ll do some more science, but I may owe Flipsky an apology.
So, after a good amount of riding, it does seem that adjusting the switching frequency from 40khz to 25 kHz has helped the screaming motor problem quite a bit. I only get a small scream around 26 mph now which is a lot more bearable than what I was dealing with previously. I’m going to play with the setting a little further to see if I can improve it further.
Interesting that it worked!
@Gamer43 was able to go up to 35khz with Sample V0 and V7 enabled, 70 khz with it off using an old V4 but at 40/80khz it bricked it and needed a reflash with a STLink. The 75/300 with 3 phase shunts seem to be able to go higher, like 80khz, but a lot of factors that go over my head seem to play into that limit.
This would probably be a safe range to play with:
<35khz with Sample V0 and V7 on
<70khz with it off
Keep us updated on how it goes!
I’d be intrigued to see if others with the screaming motor issue can get good results.
Personally, I don’t think it’s an issue with the resonating frequency of the cans. There would be other symptoms like strange vibrations.
Firmware has gotten progressively worse since then.
Vesc cant even manage 20khz control loop update rate without hiccups now.
@tomiboi
On the screaming motor issue, I’ve found the same thing happens with completely different ESCs (not VESC, Castle and KDE) with a different switching frequency.
For me it happens around 7k RPM.
Speed up past that, the screaming goes away, that’s why I suspect it’s a resonance.
I guess the other thing it could be is not a mechanical resonance, but rather an eletrical one with the zero sequence inductance causing recirculating currents in the delta configuration.
If it were to be an issue with mechanical resonance, a can cover would change the rpm at which the scream happened? Right? Also, this isn’t just a Flipsky matter then. It’s a problem all motors should have.
I might print up a can cover and see what happens.
Yes, I can get various motors to resonate at their respective frequencies.
For 6374’s their resonance is at a frequency much higher than their maximum operating speed.
The ones from saite really hate 16k rpm.
Update on the flipsky 63100 motor screaming.
I opened up another 63100 I got a while back, and this one does not scream at all.
It feels like it has a little bit more cogging torque, not sure where that comes from, but the parameters are the same.
I did notice that the one that does NOT scream has a slightly larger gap between the can and the bell. According to my caliper, the difference is 0.7mm vs 1.00mm.
Maybe the solution to the screaming is to add an additional 0.5mm shim to the shaft inside the can?
Flipsky is also using a wave washer to hold the c-clip in place, looks like they’re taking motor assembly pretty seriously
So it’s ok to cover the entire beautiful top side of your decks with grip tape?!?
I am digging that look!!!
That’s my preferred way of going about things. I like grip tape.
Is that Jessup Roam?
I use Vicious brand, coarse grip-tape. I keep a big roll of black and clear on hand.
@tomiboi that top box is a smart way to make more room for more cells.
Is the bms in there too, or were you able to fit that in with the battery?
