manasi
Member
initially how to tune a PID for temp control. is there any relation among P, I & D while tuning.
Regards
Manasi
Regards
Manasi
Short answer yes. Each can affect the other.initially how to tune a PID for temp control. is there any relation among P, I & D while tuning.
Regards
Manasi
initially how to tune a PID for temp control. is there any relation among P, I & D while tuning.
Regards
Manasi
Yes, auto tuning programs have worked out the math that calculates the gains after analyzing there the response of the system to excitation.initially how to tune a PID for temp control. is there any relation among P, I & D while tuning.
That is because:As rta53 says D is the most difficult term to utilize successfully.
ZN results in poor response that over shoots and the oscillates around the set point a few times. One can do much better with just a little effort. The methods on the www.controlguru.com are much better than ZN.I suggest you forget the math and do a search for Ziegler and Nichols, their tuning method is quite easy to understand.
Roy
You are right. The general rule of thumb is that one gain is required for every pole in a system. Do you know what a pole is?I would make one guess: In flow controll you should not use derivative term?
PID isn't always the best technique. It really does depend on the application. Ki is usually required on type 1 systems where reaching the set point exactly isn't required. Kd isn't required in most speed control applications. There is a mathematical justification for these statements.PID is the best technique bUt however P,PI.PD can be used in some processes with great results.these parameters rely on each other especially in critical loops
Superstition without mathematical justification. A temperature control system has dead time because it takes time for heat to move. It has one time constant which is heating the thermal mass or the load. There may be another time constant and that is the time it takes the temperature sensor to respond to the temperature of the mass being heated. A type 0, temperature or velocity control system, requires a integrator. If there is a time constant due to the thermal mass. This requires a P gain. If there is also a time constant due to the temperature then a another gain is required, the derivative gain.I have some experience with temp. loops, try the following, hope you will get good result. but before that I need to understand what is your temp. source, ( thermic fluid, heat exchanger, electric heat generator Star/delta) etc.
keep, i & d =0.
put p (kp) to a little high, try to check three cycle, if required put some I, to adjust. you might not need D, use dead band to stabilize ( if your process permit.