how can i tune 3 pi controllers at a time in matlab

In MATLAB, you can tune multiple PI controllers at the same time using the Control System Toolbox. Here's an example of how you can do it:

main.m
% Define the plant transfer function
plant = tf([1], [1 2 1]);

% Define the controller structure
numControllers = 3;
controllers = cell(numControllers, 1);

% Loop through each controller and define its initial parameters
for i = 1:numControllers
    controllers{i} = pid;
    controllers{i}.Ts = 0; % Set the sampling time to continuous
    controllers{i}.P = 1;
    controllers{i}.I = 1;
end

% Define the tuning options
opts = pidtuneOptions('PhaseMargin', 60);

% Tune the controllers
[tunedControllers, ~] = pidtune(plant, controllers, opts);

% Display the tuned parameters
for i = 1:numControllers
    disp(['Tuned controller', num2str(i), ':']);
    disp(tunedControllers{i});
    disp(' ');
end
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In this example, we first define the transfer function of the plant that you want to control using the tf function. Then, we define the controller structure for numControllers number of controllers using the pid function. We loop through each controller and set its initial parameters, such as proportional gain (P) and integral gain (I).

Next, we define the tuning options using the pidtuneOptions function. In this example, we use the 'PhaseMargin' option and set it to 60 degrees, you can use other tuning methods like 'GainMargin' as well.

Finally, we tune the controllers using the pidtune function. The function returns the tuned controllers in the tunedControllers cell array.

You can then display the tuned parameters using a loop and the disp function. Adjust the parameters and tuning options according to your specific requirements.