Tuning pwm period for motor

Thread Starter

noweare

Joined Jun 30, 2017
115
Does driving a small dc motor with a clean pwm signal make any difference to the motor?

I was driving a little dc motor with a H-bridge from an arduino using pwm. I used the built-in analogWrite() function which puts out a pwm signal at a
frequency of 1 KHz.

The waveform output actually going to the motor and was very non square wave looking for the most part. The motor
did respond OK.

To try and make the waveform to the motor look more like a square wave I used one of the timers to pwm the motor but at 7KHz instead of
1 KHz. The wave form to the motor was a much cleaner looking pwm signal.

I have not heard of tuning the pwm period to get a better waveform output from the drive.

Thanks
 

MaxHeadRoom

Joined Jul 18, 2013
22,866
Does driving a small dc motor with a clean pwm signal make any difference to the motor?
I have not heard of tuning the pwm period to get a better waveform output from the drive.
Thanks
When driving a DC motor from a PWM signal, the resultant current waveform is quite different, it takes the form of a mean level sine wave like signal the level of which is dependent on the % width of the PWM pulses.
A general guide line is a minimum of 5Khz to 6Khz.
Max.
 

Thread Starter

noweare

Joined Jun 30, 2017
115
Thanks Max,
I did not go through every frequency but 7KHz looks alot better. Is the impedance of the coil just to low at 1KHz such that it can't support the voltage applied. Thanks for your input.
 
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