I am using a stepper motor for a gantry setup. When I run the motor above certain speeds, in this case 4rev/sec, it produces a high frequency sort of whinny sound. It is a 4.5A motor and I am running it with 24V.
If I run the motor at 48V, I am able to reduce the high frequency sound quite a bit, in fact I have to go up to 6rev/sec for it to be at audible/annoying levels.
My initial guess is that at 48V the stepper is able generate more torque since the current in the coils is able to overcome back EMF and rise to higher levels than in 24V. Is this a correct assumption or is there more to it?
I do not believe the motor is defective since I tried a few different motors with the same 4.5A rating and they all have a point in the speed where they begin to produce the high frequency noise.