How to choose the optimal PWM frequency

Thread Starter


Joined Feb 28, 2023
I have been playing around with a linear direct drive motor: SDLM-025-095-01-05. I use a driver that has the features listed below. I have made it work with a PWM frequency of 1kHz, and everything works well enough, but I want to understand how to get the optimal PWM frequency and duty cycle so I can give good reasoning. Can someone please help ;(

Driver features:
  • Run DC and Voice Coil Motors with PWM and Direction Control Inputs
  • 4 Amp Motor Output
  • +6.5 VDC to +40 VDC Power Supply
  • 0 ºC to 70 ºC Operating Temperature
  • Light: 0.36 Oz (10 gm)
  • PWM Frequency up to 50 KHz


Joined Mar 14, 2008
Since the efficiency of a PWM driver generally goes down with frequency, you want to use as low a PWM frequency as possible, that still gives the desired results.
Driving an electro-mechanical device, the lower limit is generally determined by the needed frequency response of the device and/or minimizing mechanical noise and avoiding any mechanical resonances.

The PWM duty-cycle is determined by the average output voltage you want and is largely independent of the PWM frequency.


Joined Jan 12, 2015
I'm interested in this general question, surely the ideal frequency for a given RPM is a function of motor inductance, motor inertia and so on, I just don't see how it can be independent of the motor's physical characteristics.


Joined Mar 14, 2008
I just don't see how it can be independent of the motor's physical characteristics.
It's not, obviously.
At some low frequency the motor will start exhibiting noise and/or oscillations that likely should be avoided.
It's also limited by how fast the motor needs to respond to a change in the PWM duty-cycle.


Joined Jul 18, 2013
The majority of closed loop servo drives, CNC etc, I have been involved with over the decades, were no more than ~ 20khz, PWM.
Their is little point, even undesirous to go any higher if no viable reason to.