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Dither Amplitude and frequency for EDC valve

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Jpshockster:
Any recommendations welcome.

So I have read the API and every other document I could find with no answers to my question.

I'm working with a Linde Hydrostat HPV-02
My software drives the swash plate one direction for forward and the opposite for reverse, using C1p37 for Fwd and C1p38 for Rev.  Pinconfig 5 for both.  I have found the applying Dither 200mA @50hz to the Fwd (C1p37) gives me a very smooth transition from neutral to forward motion creep,  I apply the same values to the reverse (C1p38) and the transition is aggressive/jerky...... so I remove the Dither parameters from the Fwd (C1p37) and only use them on Rev (C1p38) and Reverse now has the very smooth transition from neutral to reverse motion creep. 
Now for the question
Is it ok to manipulate the Dither parameters or should they remain constant? 
I set it up now so that when the vehicle is in neutral there is no Dither applied to either output, once a direction is selected the Dither parameters are applied to the respective output.  I have noticed that a change to Dither parameters on C1p37 affects C1p37 - C1p40 so I have configured the application to only use 37 and 38 and moved my other output devices to C1p42 - C1p45
Has anyone ever dealt with this?
Could this be hard on the controller outputs?
TIA
Justin

Marbek_Elektronik:
I can speak for Hawe valves:

ReqFreq: default 4000Hz
PinConfig: 5
Maximum current 1100mA
Dither frequenc 100Hz
CurChgLim: default 111
Dither amplitude 100mA

For all valves an all dirctions the same parameters.

Jpshockster:
Marbek_Elektronik,
What did you do for your Minimum current?  Do you have an issue with the cracking current being higher than the drop out current? 
For my valve I have found that 440mA is the cracking current regardless of Dither parameters.  Once the valve opens I can lower my minimum to 390mA and maintain motion at a slower speed than that 440mA it took to initiate motion. 

The other question I would have for you is.......Do you set your parameters the same in every vehicle or do you have to tweak them per vehicle?

Marbek_Elektronik:
It was a 24V system.
And it was only 1 vehicle and I adjust the parameters to the vehicle.
I don't know the starting point.

My understanding is:
- if you use no dither, there will be a big hysteresis,
- if the dither frequence is low and the dither current is high, there will be a small hysteresis,
but: maybe the system works with the dither frequence and the life time is not high.

FluidPowerTom:
Well, I've found that the code will compile if you have logic to switch PWM frequency during operation, but the code will not compile if you have logic to switch the dither frequency.  What I've done with this is instead of running high frequency PWM with dither (pinconfig 5) I just do low frequency PWM without dither (pinconfig 4).  This more or less allows you to change dither frequency within your programming since it derives from the low frequency PWM.  I haven't tried any such logic with dither amplitude though...

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