Make a stepper motor less noisy

[kidi3]

I am currently trying to make my stepper motor ramp up and down as noiseless as possible, but for some reason am I not able to hit the right sweet spot, which causes my motor to get warm, and the motor to make noise in vibration. The top-speed it reaches it very noise free.


The motor i am using a PK244-01A (A video of the motor) driver which it is connected to is an ST330-v3


The code i am using for creating the ramp is inspired by the application note from Atmel


The values i use right now is 800 [rad/sec]/sec for ramping up and 800 [rad/sec]/sec for ramping down,
it should move 23400 steps, and the max speed it should reach is 2000 rad/sec

At the top speed is the noise not a problem it is when it ramps up and down, there is certain part where it is very noisy and I don't know whether it is because I am moving it too fast, as moving it slower makes the same noise, and it makes things even worse as the region where the max speed is reached shortened, so the duration of the noise will be longer.

I scoped the the signal i provide the stepper motor, As i am not able to plot the whole sequence of PWM signal, i just plotted the frequency of the PWM vs. the time. X-axis is the time in seconds an y-axis is the frequency in hz.



I made a sound clip of the noise it makes in both 1/8 stepping and 1/16 stepping.

**broken link removed**

**broken link removed**

So my question is:

How do i determine what values i should use for ramping up and down my motor?

- The info isn't as far I can see specified in the data sheet
- I have some heating issue with the motor, which i think occurs due the the noise the motor making.

Is my conversion of speed the same as the pulse frequency generated?
- I am not sure whether speed I am providing the program, does provide the desired rampup or rampdown speed, if not, how do i determine the speed it actually moves by?

 

[d123]

Hi,

Probably no help at all... Listening to the noise/soundclips, reminds me of the sound of running 5V ~25mA solar motors at too high a voltage, like 7V or 9V, I assumed it was causing excessive RPM to make that screeching sound. I associated vibration with "out of control/too much power applied", no doubt I'm wrong.

With a tiny 5V bipolar stepper, I just used a squarewave at presumably much lower frequency than you are applying, and it made a "nice" little clicking noise as it moved from position to position, even if a squarewave isn't a good method.

Have you put a non-polarised capacitor across the terminals/respective input wires? Not that that has anything to do with the problem.

 

[kidi3]

my motor is powered with an 12 V battery, it could be that the source is not stable i dont know, i have to test that.. but it should work.. so iam not sure what is wrong..

I havent put a cap. on the input wire.

i will later test with an higher acc an decel

 

[c_mitra]

The sound files do not appear synchronized with the ramp. But I can see two resonance - one each during the ramp up and down respectively. You need to play with other ramps (instead of a linear ramp you may consider an hyperbolic ramp)- but first check that you are not applying too much voltage and current to the motor.

 

[kidi3]

I am pretty sure that the current has been limited to 1.5 A and voltage is 12V.. The power is provided through a battery a 12 V battery. So...

 

[kidi3]

No.. The time stamp on the ramp is not synchronized with the sound clip.. (I am not that fast when it comes to entering commands.... )

- - - Updated - - -

Why different ramps?...
I know other people have managed to do it with this one. The only things I could think, which could cause it to make noise like this would be because of the ramp being to slow.

 

[c_mitra]

The only things I could think, which could cause it to make noise like this would be because of the ramp being to slow.

No, I do not think that the ramp is the problem. The motor has its natural frequency and it makes noise. Other motors will not have this problem. The motor is not on load and the noise will be different if you have some load on the motor.

 

[kidi3]

The ramp was the problem... A higher acceleration rate made it less noisy, but weird part is that the decelleration make a bit of noise in a certain area of the decelerating step.

 

[andre_luis]

the decelleration make a bit of noise in a certain area of the decelerating step.

Just a guess, but isn't it plausible to consider the possibility of happening a mechanical vibration occurring at the fundamental frequency of the structure as a whole? In other words, does a certain frequency of switching the entire mass assembly coupled to the motor could not be reverberating ?

 

[FvM]

It's quite normal to observe resonances with step motor drives, either resonances inside the stepper motor or resonances of the connected load. It might be possible to skip known resonance frequencies by modifying the ramp, but you must take care of not loosing steps when jumping over a certain step frequency range.