Heater Gain Calculation Units - Page 2 - PLCS.net

drbitboy · January 14th, 2022, 01:49 PM

The gains came up negative in the spreadsheet because the Kp eXcel formulae in row 45 used (U44-U43) as a divisor, where U44=CO2=0 and U43=CO1=100, but there could still be summat amiss in the numerator.

Taylor Turner · January 14th, 2022, 05:17 PM

10% Data.

It's not the best. Damn thing just kept going. I wanted to convince myself that it was approaching its asymptote soon....

https://github.com/TTControls/Heater...tResponse.xlsx

drbitboy · January 14th, 2022, 05:43 PM

Try 1%; it looks like it will take a long time to be stable.

It may effectively be an Integrating (Non-Self-Regulating) Process: it is a thermal capacitor (tank) and the heating element is adding heat, the accumulation of which is measured by temperature.

Peter Nachtwey · January 15th, 2022, 12:17 AM

Quote:

Originally Posted by drbitboy

It may effectively be an Integrating (Non-Self-Regulating) Process:

You must be kidding me.
If the heat is taken away the system will return to ambient temperature.

This is control basics 101. There are non-integrating ( type 0 ) and integrating systems and you should be able to tell the difference.

Velocity and temperature systems are non-integrating ( type 0 ) systems because when the power is taken away they return back to a steady state. Temperature systems return to the ambient temperature and velocity systems slow to 0 velocity.

Level and position control systems are integrating systems. Level control integrates the difference between the inflow and the outflow. Position control systems integrate velocity.

drbitboy · January 15th, 2022, 12:56 AM

yeah, dunno what I was thinking.

Taylor Turner · January 17th, 2022, 03:19 PM

Gents, thank you for your time.
Here's a 1% step. I think this is all the time I can afford on the matter.
I'm going to see how well these gains work and post the results just for fun.

https://github.com/TTControls/Heater...tResponse.xlsx

This is the PID for reference.

https://github.com/TTControls/PID/blob/master/PIDFFwPWM

drbitboy · January 17th, 2022, 05:25 PM

Quote:

Originally Posted by Taylor Turner

Here's a 1% step. I think this is all the time I can afford on the matter.

https://www.youtube.com/watch?v=ujUfZ3tH1gQ&t=23s

Taylor Turner · January 17th, 2022, 05:35 PM

Ha!

Taylor Turner · January 17th, 2022, 05:41 PM

I'm going back to my old code that uses error windows for a defined diminishing output. As well as when error is negative and rate of PV is negative the ssr will output some. Clamping the output at 0 or 100 and waiting for error to flip is not looking good. Where is my high gain, zero lapped spool that never saturates...

Taylor Turner · January 18th, 2022, 10:27 AM

Damnit all to hell I have a hard time giving up.
To counter act the error +/- flip being the thing that unclamps the CO min/max, tossing velocity into the calc seems like the thing to do. Only when trying to hold steady state. When ramping up this will not work. Does this seem right?

if Error > 0 and Error < 10
ITerm := IGain*Error*Velocity*-1;
elsif Error < 0 then

ITerm := IGain*Error*Velocity;
else
ITerm := IGain*Error;
end_if;

January 14th, 2022, 01:49 PM	#16
drbitboy Lifetime Supporting Member Join Date: Dec 2019 Location: Rochester, NY Posts: 7,353	The gains came up negative in the spreadsheet because the Kp eXcel formulae in row 45 used (U44-U43) as a divisor, where U44=CO2=0 and U43=CO1=100, but there could still be summat amiss in the numerator. __________________ _ Brian T. Carcich i) Take care of the bits, and the bytes will take care of themselves. ii) There is no software problem that cannot be solved with another layer of indirection. iii) Measurement is hard. iv) I solemnly swear that I am up to no good v) I probably have the highest ratio of forum posts to actual applications in the field (but no longer ∞ ). vi) Hakuna matata. vii) Bookkeeping. viii) But I should be ignored.

January 14th, 2022, 05:43 PM	#18
drbitboy Lifetime Supporting Member Join Date: Dec 2019 Location: Rochester, NY Posts: 7,353	Try 1%; it looks like it will take a long time to be stable. It may effectively be an Integrating (Non-Self-Regulating) Process: it is a thermal capacitor (tank) and the heating element is adding heat, the accumulation of which is measured by temperature. __________________ _ Brian T. Carcich i) Take care of the bits, and the bytes will take care of themselves. ii) There is no software problem that cannot be solved with another layer of indirection. iii) Measurement is hard. iv) I solemnly swear that I am up to no good v) I probably have the highest ratio of forum posts to actual applications in the field (but no longer ∞ ). vi) Hakuna matata. vii) Bookkeeping. viii) But I should be ignored.

January 15th, 2022, 12:56 AM	#20
drbitboy Lifetime Supporting Member Join Date: Dec 2019 Location: Rochester, NY Posts: 7,353	yeah, dunno what I was thinking. __________________ _ Brian T. Carcich i) Take care of the bits, and the bytes will take care of themselves. ii) There is no software problem that cannot be solved with another layer of indirection. iii) Measurement is hard. iv) I solemnly swear that I am up to no good v) I probably have the highest ratio of forum posts to actual applications in the field (but no longer ∞ ). vi) Hakuna matata. vii) Bookkeeping. viii) But I should be ignored.

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January 14th, 2022, 05:17 PM	#17
Taylor Turner Member Join Date: Sep 2020 Location: Midwest Posts: 78	10% Data. It's not the best. Damn thing just kept going. I wanted to convince myself that it was approaching its asymptote soon.... https://github.com/TTControls/Heater...tResponse.xlsx

January 17th, 2022, 03:19 PM	#21
Taylor Turner Member Join Date: Sep 2020 Location: Midwest Posts: 78	Gents, thank you for your time. Here's a 1% step. I think this is all the time I can afford on the matter. I'm going to see how well these gains work and post the results just for fun. https://github.com/TTControls/Heater...tResponse.xlsx This is the PID for reference. https://github.com/TTControls/PID/blob/master/PIDFFwPWM

January 17th, 2022, 05:35 PM	#23
Taylor Turner Member Join Date: Sep 2020 Location: Midwest Posts: 78	Ha!

January 17th, 2022, 05:41 PM	#24
Taylor Turner Member Join Date: Sep 2020 Location: Midwest Posts: 78	I'm going back to my old code that uses error windows for a defined diminishing output. As well as when error is negative and rate of PV is negative the ssr will output some. Clamping the output at 0 or 100 and waiting for error to flip is not looking good. Where is my high gain, zero lapped spool that never saturates...

January 18th, 2022, 10:27 AM	#25
Taylor Turner Member Join Date: Sep 2020 Location: Midwest Posts: 78	Damnit all to hell I have a hard time giving up. To counter act the error +/- flip being the thing that unclamps the CO min/max, tossing velocity into the calc seems like the thing to do. Only when trying to hold steady state. When ramping up this will not work. Does this seem right? if Error > 0 and Error < 10 ITerm := IGainErrorVelocity-1; elsif Error < 0 then ITerm := IGainErrorVelocity; else ITerm := IGainError; end_if;

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