Author Topic: PWM output, proportional Valve  (Read 1762 times)

Offline AP

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PWM output, proportional Valve
« on: April 17, 2024, 10:40:56 PM »
Hello I am new to Danfoss! THANK YOU FOR ANY HELP!!

I am trying to control a proportional valve with a PWM signal, the valve requires a 0 to 600mA.

What are the steps involve in this. as simple as possible?

1. Scaling. the valve is inversely proportional so 0mA= 3000PSI and 600mA=0PSI, I can use y=mx+b or scale function from library.
2. is there a function block needed to output a PWM? or can I send the scaled value to the Multifunctional Output?
3. how is the ping configuration done? Output mode option 3,4 or 5?

Thank you again !!

Offline Lukey

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Re: PWM output, proportional Valve
« Reply #1 on: April 18, 2024, 02:50:18 AM »
1. As a beginner yes I would use the scale Fb this is
2. Yes there is a PWM_Driver function block found in the outputs library, see attached
3. Ping config 3 is a good starting point, see attached

Offline samuelhj

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Re: PWM output, proportional Valve
« Reply #2 on: April 22, 2024, 12:25:10 AM »
Hello I am new to Danfoss! THANK YOU FOR ANY HELP!!

I am trying to control a proportional valve with a PWM signal, the valve requires a 0 to 600mA.

What are the steps involve in this. as simple as possible?

1. Scaling. the valve is inversely proportional so 0mA= 3000PSI and 600mA=0PSI, I can use y=mx+b or scale function from library.
2. is there a function block needed to output a PWM? or can I send the scaled value to the Multifunctional Output?
3. how is the ping configuration done? Output mode option 3,4 or 5?

Thank you again !!

Since I recently had to deal with Bosch-Rexroth valves that wanted PWM signal, I'll share my insight on this, be aware I don't know your specific valve type so milage may vary.
The datasheet for the valve should at least have some guidelines on how to drive the valve via PWM.

What worked for the specific valve I was working with (which was contrary to the datasheet for that valve) was

Config per output:
PinConfig = 5
DitherAmp = 600 (60mA)

Config per group (you'll see this under the main page for Outputs)
CurChgLim = 111 (default)
DitherFreq = 150 (150Hz)
ReqFreq = 1000 (1kHz)

After messing around with the settings for a bit this proved to be very smooth way of controlling the valves in question.

I used the PWM driver from the function library (really worth the investment to save time).

Be mindful that not all outputs on all the danfoss controllers support dither and such (like MC050-118 does not support dither on output 41 and 46 iirc).