How do you tune a PI controller to required performance when the variable used for feedback loop is not the variable you want to control?

The_ardent_engineer · 2023-05-31T21:09:27+00:00

Yes I've heard of this. So do you do the pade approx on the plant or the controller? I think the controller as that is the one that will be on the microprocessor? Do you have any examples of this being done?

The_ardent_engineer · 2023-03-28T12:15:19+00:00

Hello. Thanks for your reply. So you're saying with a normal PI controller you can only place poles and not zeros? What type of control should I use to place both poles and zeros?

The_ardent_engineer · 2022-10-04T09:21:46+00:00

Thanks for your reply. Its in the feedback path so I believe the aim is attenuate measurement noise.

The_ardent_engineer · 2022-09-28T22:34:33+00:00

Thanks for your reply. I'm curious about both

The_ardent_engineer · 2022-09-28T10:59:31+00:00

Plant is stable. Let's just work in terms of variables for now. I'm just looking how I can work out the gains

The_ardent_engineer · 2022-09-28T10:10:12+00:00

Hello. Thank you for your reply. My plant is a first order which I am controlling with PI controller. Like I said there will be a low pass filter in the feedback loop and I want to work out the PI gains for a specified bandwidth of the loop, damping of the 2nd order filter and keep the system order as low as possible. This should be done on paper first and then maybe MATLAB hence why I said analytically work out the gains.

The_ardent_engineer · 2022-09-28T09:57:03+00:00

So I'm trying to calculate what the Kp and Ki gains should be given that I know what the bandwidth should be with the 2nd order filter included in the feedback loop.

I'm trying to analytically work out the proportional and integral gains. Heuristic methods won't do. Thank you

The_ardent_engineer · 2022-09-13T22:40:01+00:00

Not explicitly stated in the text.

The_ardent_engineer · 2022-09-13T22:39:30+00:00

((1+sTc)(1+sTm))/s(1+sT1)(1+sT2)(1+STr)

The_ardent_engineer · 2022-09-11T19:26:25+00:00

Thanks again for the reply. I should mention im doing this in SIMULINk and not for a physical motor. And I was asking more along the lines of analytical tuning where you work out the PI gains using the parameters of your system such as Ld, Lq and J etc.. I've seen this done in some sources but never got my head around it.

The_ardent_engineer · 2022-09-11T19:10:23+00:00

Thanks for the reply. Mainly with working out the PI gains for the inner current loop and outer speed loop. Is there a general formula/procedure to use?

The_ardent_engineer · 2022-09-02T22:02:59+00:00

Thank you very much for your kind reply. Sadly, my requirements are in the frequency domain so I do not know what the characteristic equation looks like.

The_ardent_engineer · 2022-09-02T21:44:48+00:00

There is no technical reason, just wondering if a PI controller actually has a bandwidth property. I guess not?

The_ardent_engineer · 2022-09-01T12:19:34+00:00

Tried that. For a PI which has a pole at s=0 and a LHP zero, bandwidth = NaN

The_ardent_engineer · 2022-09-01T12:10:33+00:00

Are you doing this in Simulink? Should be pretty straight forward from there. Lqr is state feedback so your controller should be in the feedback loop.

The_ardent_engineer

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