I want to know how to tune the PI controller in case of parameter estimation,
let say i have equation Ls=[Kp+Ki/2]*[VdEd+VqEq]
so how to estimate Kp and Ki value for better performance of the whole system
I am working on the MRAC system For ac machines
Looking forward for guidance and technical help
One way is to used frequency domain tools such as the SISO tool in matlab. This allows you to determine the values of PI/PID controllers for your desired response. However to do this you need to obtain a transfer function in Laplace form. If you use Rotor Flux Oriented Control you should obtain linearized current transfer functions Vd/Id = 1/(sLd+R) and Vq/Iq = 1/(sLq+R). The non-linear terms need to be added as compensation terms in feed-forward.
I can recommend one useful book: Control system design guide, 3rd ed. by George Ellis. There you can find the so-called zone-based tuning procedure for feedback loops. In short it says:
1. tune proportional gain Kp. set Ki to zero and set Kp low to ensure stability;
2. apply a square wave and raise Kp until significant overshoot is generated. How much overshoot should be depends on your application.
3. As far as Kp is tuned, raise Ki until acceptable overshoot. Usually 5-10%.
Kris Scicluna I want to know if I like to find PI gain for a simple equation that is based on error signal and estimation state values e.g(stator induction estimation based on adaptive law) then how can i find the Laplace transform of the equation and then find z-transform and utilize it for siso tool to find the PI gain....
Maksim Dybko thanks for the suggestion I want to ask if I need to find 3 PI controller gain values that are utilized in the cascaded system for control the how to determine PI gain separately for the effective performance of the system
your's suggestion will be helpful for me........
The plant is obtained from a simplified differential equation of the machine and the result in the s-domain is what I stated in the earlier comment. You can use the Bilinear transform to go from the s-domain to the z-domain.
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