How can i fix that? And are there any error in my code? thank. "X0 returned by MATLAB S-function 'mppt1' in 'solar/S-Function' must be a vector of length 4"

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Do An
Do An 2020-10-21
回答： Shubham 2024-10-12
function [sys,x0,str,ts,simStateCompliance] = mppt1(t,x,u,flag)
%SFUNDSC2 Example unit delay MATLAB File S-function
% The MATLAB file S-function is an example of how to implement a unit
% delay.
%
% See sfuntmpl.m for a general S-function template.
%
% See also SFUNTMPL.
% Copyright 1990-2009 The MathWorks, Inc.
switch flag,
%%%%%%%%%%%%%%%%%%
% Initialization %V
%%%%%%%%%%%%%%%%%%
case 0,
[sys,x0,str,ts,simStateCompliance] = mdlInitializeSizes;
%%%%%%%%%%
% Update %
%%%%%%%%%%
case 2,
sys = mdlUpdate(t,x,u);
%%%%%%%%%%
% Output %
%%%%%%%%%%
case 3,
sys = mdlOutputs(t,x,u);
%%%%%%%%%%%%%
% Terminate %
%%%%%%%%%%%%%
case 9,
sys = [];
otherwise
DAStudio.error('Simulink:blocks:unhandledFlag', num2str(flag));
end
%end sfundsc2
%
%=============================================================================
% mdlInitializeSizes
% Return the sizes, initial conditions, and sample times for the S-function.
%=============================================================================
%
function [sys,x0,str,ts,simStateCompliance]=mdlInitializeSizes
sizes = simsizes;
sizes.NumContStates = 0;
sizes.NumDiscStates = 4;
sizes.NumOutputs = 1;
sizes.NumInputs = 1;
sizes.DirFeedthrough = 1;
sizes.NumSampleTimes = 1;
sys = simsizes(sizes);
%initial conditions
x0=[0;0;0;0];
str = [];
ts = [0.01 0]; % Sample period of 0.1 seconds (10Hz)
% speicfy that the simState for this s-function is same as the default
simStateCompliance = 'DefaultSimState';
% end mdlInitializeSizes
%
%=======================================================================
% mdlUpdate
% Handle discrete state updates, sample time hits, and major time step
% requirements.
%=======================================================================
%
function sys = mdlUpdate(t,x,u)
x(1)=u;
if x(1)>x(2)
x(2)=x(1);
x(3)=x(4);
x(4)=t(3)+0.01;
else
x(3)=x(4);
x(4)=x(3)-0.01;
end
sys = x;
%end mdlUpdate
%
%=======================================================================
% mdlOutputs
% Return the output vector for the S-function
%=======================================================================
%
function sys=mdlOutputs(t,x,u)
sys = x(4);
%end mdlOutputs

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回答（1 个）

Shubham
Shubham 2024-10-12
Hi @Do An
The error message indicates that the initial condition vector x0 must have a length of 4. Your code seems to be correct in that regard, as you have defined "x0" as a 4-element vector:
x0 = [0; 0; 0; 0];
However, the issue may arise from the "mdlUpdate" function. Ensure that you're updating the state vector "x" properly. As far as I understand, accessing "t(3)" doesn't make sense because "t" is a scalar representing the current time.
Try modifying the update function as:
function sys = mdlUpdate(t,x,u)
x(1) = u; % Assuming u is a scalar input
if x(1) > x(2)
x(2) = x(1);
x(3) = x(4);
x(4) = t + 0.01; % Changed from t(3) to t
else
x(3) = x(4);
x(4) = x(3) - 0.01;
end
sys = x;
If you are still facing issues, then try sharing the model for complete reproduction of the issue.
I hope this helps!

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