Simulink Control Design™ - MathWorks

with Kp = -3.07, Ki = -0.425

Name: PI_V

Continuous-time PI controller in parallel form.

This is due to the negative signs in the second input channels of the plant. In addition,

the tunable elements are over-parameterized because multiplying DM by two and dividing

the PI gains by two does not change the overall controller. To address these issues, fix the

(1,1) entry of DM to 1 and the (2,2) entry to -1.

DM = getBlockParam(ST0,'DM');

DM.Gain.Value = diag([1 -1]);

DM.Gain.Free = [false true;true false];

setBlockParam(ST0,'DM',DM)

Re-tune the controller for the reduced set of tunable parameters.

[ST,gam,Info] = looptune(ST0,Controls,Measurements,wc,OS,DR);

Final: Peak gain = 0.988, Iterations = 78

Achieved target gain value TargetGain=1.

The step responses look similar but the values of DM and the PI gains are more suitable

for implementation.

figure('Position',[0,0,700,350])

subplot(121)

Ttrack = getIOTransfer(ST,'r','y');

step(Ttrack,40), grid, title('Setpoint tracking')

subplot(122)

Treject = getIOTransfer(ST,{'dV','dL'},'y');

step(Treject,40), grid, title('Disturbance rejection')

12 Loop-Shaping Design