Phidgets motor whining (PWM Frequency?)

Hardware Autosteer
1

I just got my Phidgets motor (3269_3) and my driver is Cytron MD13S. I just hooked up everything and my motor is making a whining noise when it’s controlled by PWM. On a direct DC voltage by buttons MA and MB it’s working really quietly and not whining at all but when it’s driven by PWM it starts whining.

My guess is that I need to change the PWM frequency? I tried with 490Hz and 3921Hz and it’s still whining… Then I tried it with 122Hz and it’s a lot quieter.

On cytron site, this is written

Speed control PWM frequency up to 20KHz (Actual output frequency is same as input frequency)

But in Arduino files, there are options to change frequency to 3921Hz and 31372Hz. 3921Hz is whining and 31372 is 50% higher than the maximum PWM frequency for Cytron driver.

There are also some official Phidgets DC drivers and they are operating at 20kHz to 25kHz.

So, on which PWM frequency do you guys make your Phidgets work quietly?

2

100 thread views and no responses? How? Do you guys not use Phidgets motors or still didn’t finish your project?

Maybe to ask in general:

  • What motor do you use?
  • What PWM frequency do you use?
  • Is your motor producing some noise (whining)?
3

Trimble ez steer motor on 12 volt and cyrton. No whining

4

The EZ Steer motor is exceptionally quiet.

5

I’m using the phidgets on 24v. I wouldn’t say mine makes any whining noise.

6

Phidgets 3269_3 on 24v no whining noise all default config MD13S motor driver.

7

these whinnings are a very subjective concept… I find that they make too much noise, my cabins are silent, I don’t hear them from other cabins… If you ever find the solution, I will surely apply it … In the meantime, I turn up the sound of the radio.

8

Maybe a small capacitor and a resistor to deplete it again, on the pwm line. Would off course give some delay in action. Resistor must be big enough to avoid overload of nano output.

9

I can’t record the video now but I found someone’s video on youtube showing that whining sound

You can hear at about 1:25 on that youtube video that whining sound I also have when motor is running on low PWM.

It’s kinda “normal” for motor to whine when it’s on PWM signal and human ear can’t hear above 20kHz so it’s maybe better to increase PWM frequency. Also, phidghet’s driver is running on 25kHz and our Arduino nano in default configuration is running on 490Hz

  /*  PWM Frequency -> 
   *   490hz (default) = 0
   *   122hz = 1
   *   3921hz = 2
   */
  #define PWM_Frequency 0

And motor is producing exactly 490Hz sound noise when it’s not on 100% PWM

So, did anyone try to play with Arduino PWM generator to make it quieter?

Those are “default” PWM frequencies

  //TCCR1B = TCCR1B & B11111000 | B00000001;    // set timer 1 divisor to     1 for PWM frequency of 31372.55 Hz
  //TCCR1B = TCCR1B & B11111000 | B00000010;    // set timer 1 divisor to     8 for PWM frequency of  3921.16 Hz
  //TCCR1B = TCCR1B & B11111000 | B00000011;    // set timer 1 divisor to    64 for PWM frequency of   490.20 Hz (The DEFAULT)
  //TCCR1B = TCCR1B & B11111000 | B00000100;    // set timer 1 divisor to   256 for PWM frequency of   122.55 Hz
  //TCCR1B = TCCR1B & B11111000 | B00000101;    // set timer 1 divisor to  1024 for PWM frequency of    30.64 Hz

But you can make any PWM frequency with playing with Arduino timers. Did anyone try something like that and got a quite motor or maybe even more stable motor or something like that?

10

I’m not sure you can add a capacitor to PWM line because Cytron driver expect PWM signal so it can switch on/off transistors (or MOSFETs). If you “flatten” that PWM signal with a capacitor it will be always on or always off…?

11

What have you picked for steering tuning parameters?

12

Default for now, testing motor on the bench, not yet mounted

13

The high pitch sound seems to only be at incredibly slow speed in the video.

Are you using a bench power supply, or a battery in your test?

14

Bench power suply, ~13.5V 5A

15

Wait until you try off a battery until you sink too much time trying to solve this, AC to DC converters can sometimes add to noise issues. Not sure if you have a lab one, or just an simple one but most affordable ones leak some ripple.

Also give the 24v wiring a try, I use the 12/24 converter and have not heard the high pitch noise, mostly just the planetaries turning.

16

It’s DC/DC (step-down converter), not the lab one…

Ok, I’ll try it with battery but the main question, I think, is still unanswered?

Should we try to change the PWM frequency to the one recommended by the manufacturer? I mean, if it’s recommended to run on 25000Hz and we are running it on 490Hz, there probably should be some noticeable changes? Like more stable work, more power, silent work, etc?

17

As long the low frequency is kept, for us who need it to avoid the "sticking " issue in hydraulic valves, it is fine to add higher frequencies.

18

Hi @backonjam
Did you find a solution for the noise?
Mine sound like this

Until now it hasn’t bothered me, but my employees is starting to complain, so I found this thread.

19

Keep in mind that if a higher pwm frequency will increase switching losses in the mosfets on the cytron. The mosfets will get warmer when used with a higher pwm frequency.

20

The whine is always going to be proportional to the frequency, no? So reducing the PWM frequency will reduce the whine, but not sure how it affects the torque. At a certain point there must be diminished returns when increasing frequency.