PWM Solenoid frequency

[Bob1uk]

Hello
I am engaged in repairing automotive automatic transmission, I have noticed that PWM solenoids are driven at many different Htz, although their external appearance is much the same. to date I cant find a reasonable answer for the difference & why, Closest I come to an answer is that there may be a difference in the spring/valve harmonics ???? BUT I am not certain, so here I am asking the experts <G>
Thanks in anticipation
Bob Ryan

 

[MikeHalloran]

So long as the frequency is faster than the solenoid can physically respond, it probably doesn't matter; all the PWM does is control the coil's average current, which controls the force it exerts.





Mike Halloran
Pembroke Pines, FL, USA

 

[Bob1uk]

Thank you for your prompt reply Mike, however I do not seem to have made my question clear.
These Solenoids have a set frequency plus a variable pulse width to control valve position & hence the flow of oil. My query is, Why are these driven at different frequencies? The duty cycle varies in the normal way at 0 to 100%
Thanks in anticipation
Bob Ryan

 

[israelkk]

Bob1uk

Is the PWM control in the electric level to control average driving voltage or the solenoid/valve plunger is moving/vibrating in an on-off fashion to control average pressure and fluid flow?

 

[Bob1uk]

PWM controls the voltage/ on/ off time. The fixed number of times is the Hz as I understand it.