How to deal with the saturation?

[cnpcshangbo]

My FOPD controller is greatly influenced by the controller output saturation.

[cnpcshangbo]

When I comment out Fractional DD the system works well.

[cnpcshangbo]

After I uncomment that.

The speed doesn't converge. I'll need to get the sample time smaller.

[cnpcshangbo]

Then I changed the sampling period to 0.3 sec.

It didn't work. I'll need to get the sampling period even smaller to 0.1 sec.

[cnpcshangbo]

Ts=0.1; tustin

[cnpcshangbo]

I am still thinking about if it is ringing effect. We need to check the pole in discrete domain.
http://www.diangon.com/zhishi/jsjkz/201504/00022081.html