proportional solenoid valve dither PWM control

[Electro nS]

i trying to build my own controller for hydraulic solenoid proportional valve 24v 1.7A rating.

i am a using a microcontroller and a high side switch (mosfet) and PWM wih a shunt in series to achieve Switching constant current driver . (it is working so far )

the thing i cannot understand is dither frequency . most controller talk about the importance of dither !! i donot know what that is and have no knowledge on how to implement it .

according to this article : https://www.qualityhydraulics.com/blog/what-dither-versus-pwm/

it is: " Dither is a small ripple frequency that is superimposed over the PWM signal to the solenoid current that causes the desired vibration and thereby increases the linearity of the valve and improves valve response "

please help how to implement such thing or just point me into right direction,, thanks in advance

 

[chuckey]

It sounds to me like a small amount (10%?) of amplitude modulation on the PWM, using a low frequency signal (5 - 50 HZ?). I think this is to overcome any stiction in the system.
Frank

 

[Electro nS]

It sounds to me like a small amount (10%?) of amplitude modulation on the PWM, using a low frequency signal (5 - 50 HZ?). I think this is to overcome any stiction in the system.
Frank

your are right 100% , but my question is how to implement a 50hz-400hz signal over a 10khz pwm freqeuncy ??
total by software ? does a standard microcontroller support such thing ??

 

[ud23]

Some of controller comes with PWM dithering like below

https://www.st.com/st-web-ui/static...ical/document/application_note/DM00119042.pdf

Or you can try

https://www.ti.com/lit/an/slua704/slua704.pdf
https://forum.allaboutcircuits.com/...a-pwm-signal-to-control-a-servo-valve.105483/