implement a dither signal on a pwm signal to control a servo valve

Thread Starter

navidelec

Joined Jul 12, 2014
29
I would like to implement a signal on a pwm signal, what is the requirements and limitation through this?
 
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crutschow

Joined Mar 14, 2008
27,031
The main requirement is that the PWM frequency be higher than the Nyquist limit of twice the highest modulation frequency. For good response a value at least 10 times the highest dither frequency or ≥3000Hz is recommended..
 

Thread Starter

navidelec

Joined Jul 12, 2014
29
The main requirement is that the PWM frequency be higher than the Nyquist limit of twice the highest modulation frequency. For good response a value at least 10 times the highest dither frequency or ≥3000Hz is recommended..
dear friend, I should take this requirement as a report to my presentation, where can I find this requirements, I mean a text or book or ...?
 
Last edited:

crutschow

Joined Mar 14, 2008
27,031
But my servo valve current is so high (about 1 amp) to be applicable due to 3000Hz PWM, I wnoder if you tell me what should I do?
The servo likely has inductance which will smooth and average the PWM pulses into a steady current, which is what you want. A higher frequency actually helps, since there is less ripple in the average current value.
The PWM driver just needs sufficient current capacity to provide the 1 amp current.

Do you understand how PWM works?
 

Thread Starter

navidelec

Joined Jul 12, 2014
29
The servo likely has inductance which will smooth and average the PWM pulses into a steady current, which is what you want. A higher frequency actually helps, since there is less ripple in the average current value.
The PWM driver just needs sufficient current capacity to provide the 1 amp current.

Do you understand how PWM works?
yes, i got it.
 
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