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how calculate D Part in PID controllers?

Created by: kunjila-kobasa at: 7/2/2013 6:01 PM (5 Replies)

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7/2/2013 6:01 PM	Rate (0)
kunjila-kobasa Posts: 24 Rating: (0)	Pegaia Hi, The S7-1200 has a one of the most complete PID controller of the SIMATIC world. Your tuning tool, for example, makes your use very practical. Some applications, however, are very simple, and don’t need all of the potential of the intern S7-1200 PID controller. For this very simple application, the follow “lean” version of PID controller could be a choice. He has a clean list of parameter that makes your use for simple application, that doesn’t needs of tuning tools. He has an auto detection of its call time, so he could be place in any cycle or time OB without any special adjusts. Your open source could also easily adapt for special uses. Attachment:PID.zip (1193 Downloads) Hi Pegaia! Can you tell me how did you calculate the LMN_D part? Your function for LMN_D is: LMN_D = (Tm_R * DeltaER + LMN_D)/(Tm_R * DeltaTimeR / Td_R + 1) Am I correct? How do you calculate it, where do you get this formula? Everything else is clear to me
kunjila-kobasa Posts: 24 Rating: (0)	Last edited by: O_Moderator at: 7/11/2013 10:44 AM new subject after splitting from /tf/WW/en/Posts/45886#top
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7/3/2013 1:12 PM	Rate (0)
Denilson Pegaia Platinum Expert Joined: 9/23/2005 Last visit: 11/29/2023 Posts: 4277 Rating: (1377)	Hi, that I remember it should be *LMN_D (derivative part of the PID) = Tm_lag Delta ER / (Delta Time * Tm_lag / Td + 1 ) + LMN_D * ( 1 + Delta Time * Tm_lag / Td)**
	Denilson Pegaia Siemens Industry Sector Technical Support
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This contribution was helpful to 1 thankful Users kunjila-kobasa

7/4/2013 12:16 PM	Rate (0)
kunjila-kobasa Posts: 24 Rating: (0)	Yes! That is what I wrote, just in different form :) I't s just that I don't know where did you get this formula. Have you calculated the reverse laplace transformation of D part? (time domain)
kunjila-kobasa Posts: 24 Rating: (0)
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7/4/2013 1:22 PM	Rate (0)
Denilson Pegaia Platinum Expert Joined: 9/23/2005 Last visit: 11/29/2023 Posts: 4277 Rating: (1377)	Hi, I toke from some literature, but I don't have the reference of it in this momment. Is there something wrong?
	Denilson Pegaia Siemens Industry Sector Technical Support
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7/8/2013 10:16 AM	Rate (0)
kunjila-kobasa Posts: 24 Rating: (0)	I don't know :) I was just curious where did you get it, I'm sure it's ok
kunjila-kobasa Posts: 24 Rating: (0)
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7/8/2013 10:28 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 11/18/2023 Posts: 6822 Rating: (1351)	loxly I don't know :) I was just curious where did you get it, I'm sure it's ok Hello, Normally differentiators in PID controllers in SIMATIC range of productcs are like (diff_matlab.jpg ) and the following Laplace Transform: diff tf = td *s/(1+ts) It is not difficult to test.Check D part only when there is a STEP change in error(Change in Setpoint).There is solutions to solve that function in time domain.But D part in PID is not only this function.It is the main Part. Best regards Hamid Hosseini Attachment DIFF.jpg (285 Downloads)
	Last edited by: hdhosseini at: 7/8/2013 10:38 AM Demo Channel on Youtube
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