SHARKBITEATTACK
10 W
My ceiling fan motor doesn't have any brushes either and it's almost completely silent. What's the deal? Lower frequency?
So why exactly are RC motors so loud anyhow?
- Thread starter SHARKBITEATTACK
- Start date
fizzit
10 kW
They spin extremely fast compared to a ceiling fan and they're being driven with a square wave instead of sinusoidal power. Those are the two factors that I know of.
spinningmagnets
100 TW
The "trapezoidal" wave form of the common controller is like flipping a light switch suddenly on and off. Sinusoidal means that its like you are using a dimmer switch and the light is brought on and off gradually. The smoother flow reduces the buzz. The AC coming out your wall sockets is fairly sinusoidal.
RC motors on 44V are often spinning at more than 3,000-RPMs, so I agree with fizzit on the RPMs...
RC motors on 44V are often spinning at more than 3,000-RPMs, so I agree with fizzit on the RPMs...
kfong
100 kW
I would of thought a sinwave would help significantly. it now appears to me to be the high pitch frequency and noise resonances.
fizzit
10 kW
I think that RC inrunners are generally pretty quiet, so it's not quite correct to say that all RC motors are loud. Outrunners are probably a lot louder because their rotating mass is shaped like a bell and is exposed directly to the air.
spinningmagnets
100 TW
My 63mm Exceed outrunner is noticeably quieter than the 63mm Turnigy outrunner I have, both were run at the same voltage using the same ESC...I haven't measured the shell thickness, but the Exceed does look a little thicker.
So many things about the RC motors make for lots of noise. I do believe that being unsealed is a large part of it, plus spinning at about 10 times the speed than an ordinary direct drive motor.
I'm sure that trapezoidial / square commutation has a lot to do with the noise. I'd really like to hear some noise comparisons..
I'm sure that trapezoidial / square commutation has a lot to do with the noise. I'd really like to hear some noise comparisons..
thepronghorn
1 kW
I think it's because they aren't very well balanced to start with, and then they spin pretty fast. These two factors combine to cause a lot of vibration and therefore noise.
Hillhater
100 TW
When you program an RC ESC, the programmer uses a pulse generated in the ESC to make a tone ( or series of tones) from the motor. So electrical "pulses/signals" could well be the source of most noise
As somebody said before, changing the PWM setting, or a different ESC, does make a difference to the noise level.
As somebody said before, changing the PWM setting, or a different ESC, does make a difference to the noise level.
With big colossus there is a certain harmonic from the motor it self. When it switches from sensored to sensorless it gets better and the sine vs trap wave makes a difference but its still very loud in used. This video it 100% sine waves at center aligned pwm at 20khz which is the same torque ripple as 40khz with a normal controller so its like having 40khz pwm because it feeds the power into the motor at the start and end of the pwm cycle.
Either way this is the quietest you can make this motor with out lowering the HP and this is with 15 kw fed into the system.
[youtube]91pGd7jOgB4[/youtube]
Either way this is the quietest you can make this motor with out lowering the HP and this is with 15 kw fed into the system.
[youtube]91pGd7jOgB4[/youtube]
Depends how the motor is build/designed when regarding to noise in RC motors. My slotless 2 pole motors are really quiet compared to a slotted 2 pole motor at the same RPM for example and the same ESC. My 4 pole Nue/Aveox/Tekin motors are a lot quieter vs my Plettenberg/Castle Creations/Novak 4 pole motors. Doesn't matter if it's Delta or Wye windings.
Pics of the motors that I have left
Pics of the motors that I have left
neptronix said:Holy crap that is a lot of RC motors.. are you a former RC hobbyist, or have you just blown an amazing amount of money trying to find 'the one' ?
hehehhe. Nah, there are more motors that are in the actual rc cars. Just like some other peeps in here that are masters in E-bike motors, I am/was one with the RC dragsters. Looking at my motor spreadsheet, I counted 73 different motors that I blew my money on.
There was never the "one" motor. ESC controllers, ESC settings, power wires, wire length, plug size, caps, heatsinking, batteries, battery temp, etc all played a roll as well. 2 Pole motors spools up faster vs a 4 pole motor in the same dimensions. That it came down to which 2 pole motor was the best for your car for example. Hacker motors had smaller rotors vs a Lehner motor, so that dictated gearing options and traction issues. Sensorless is king in dragracing. Hybrid sensored/sensorless just started a few years ago and gave me more motor options and rotors to mess with. I have quite a few reviews writting and most can be found on the rc-monster forum.I dropped out of RC once I started working on my first Ebike. It's the same as my RC toys, just bigger.
spinningmagnets
100 TW
Snellemin, that's a lot of RC motors. When the beloved family pet passes on, you might consider doing this:
http://www.youtube.com/watch?v=-HnwhGgsgXc
http://www.youtube.com/watch?v=-HnwhGgsgXc
I think it's because the rotor, the outer spinning shell of the motor, acts like a loudspeaker. Every time a force acts on a magnet, either from simple attraction to the iron teeth of the stator, or from electric current in winding, the shell will deform (or bend), which moves the air around it, thus producing sound.
Since the motors are intended for flight, they have to be as light as possible, so all dimensions are as thin as they can be. The shell will deform more with thinner walls than with thick. So I think that's why it will make more noise than a motor intended for uses where robustness and noise are bigger priorities.
Since the motors are intended for flight, they have to be as light as possible, so all dimensions are as thin as they can be. The shell will deform more with thinner walls than with thick. So I think that's why it will make more noise than a motor intended for uses where robustness and noise are bigger priorities.
Hummina Shadeeba
10 MW
I changed the switching frequency to Thirty kilo hertz and its much quieter. Since hobby escs often will play a tune in the motor without spinning it I think the sound comes from the vibration of the ferromagnetic material in the stator. But if the iron were vibrating I’d think that would be due to a variation of the polarity and magnetic field built within the teeth and that would be a sign of inconsistency of that field strength and go along with torque pulses. But don’t think that’s the case. There’s oscilloscopes all around me and will have to plug one in
I always thought it was due to magnetostriction, but apparently it's actually down to Maxwell Forces instead. Similar concept though: cyclical distortion of the motor core due to the varying electromagnetic forces:
https://eomys.com/e-nvh/notes-on-electromagnetically-excited-noise-and-vibrations/article/magnetic-noise-and-vibrations-in-electrical-machines?lang=en/
https://eomys.com/e-nvh/notes-on-electromagnetically-excited-noise-and-vibrations/article/magnetic-noise-and-vibrations-in-electrical-machines?lang=en/
Similar threads
