cpid5.m

一种pid控制算法在带小时滞的二阶梯振荡环节控制系统上的应用.

%PID Controller 大时间常数二阶振荡环节的时滞非线性控制系统
clear all;
close all;

umin=0.08;umax=0.9;
ts=0.01;%采样时间
sys=tf([0.712],[1,0.324,0.265],'inputdelay',0.04);%构造时滞系统传递函数模型
dsys=c2d(sys,ts,'z');%连续系统离散化，用z变换
[num,den]=tfdata(dsys,'v');%求零极点矩阵
u_1=0.0;u_2=0.0;u_3=0.0;%输入输出等相关变量初始化
u_4=0.0;
y_1=0.0;y_2=0.0;y_3=0.0;
x=[0,0,0]';
error_1=0;
error_2=0;
for k=1:1:400
time(k)=k*ts;%400个采样点 
rin(k)=1;%Step Signal
 kp=780;
 ki=20;
 kd=5;
u(k)=kp*x(1)+kd*x(2)+ki*x(3);%PID Controller]

if abs(u(k))<=umin
     u(k)=0;
 end
 if abs(u(k))>umax
     u(k)=sign(u(k))*umax;
 end

 
%Restricting the output of controller
if u(k)>=40       
   u(k)=10;
end
if u(k)<=-40
   u(k)=-10;
end
%Linear model
yout(k)=-den(2)*y_1-den(3)*y_2+num(2)*u_3+num(3)*u_4;
error(k)=rin(k)-yout(k);
%Return of parameters
u_4=u_3;
u_3=u_2;u_2=u_1;u_1=u(k);
y_3=y_2;y_2=y_1;y_1=yout(k);
   
x(1)=error(k)-error_1;            %Calculating P
x(2)=error(k)-2*error_1+error_2;  %Calculating D
x(3)=error(k);                    %Calculating I
error_2=error_1;
error_1=error(k);
end
figure(1);
plot(time,rin,'b',time,yout,'k');
xlabel('增大二阶振荡环节时间常数的时滞非线性控制系统PID仿真 time(s)'),ylabel('rin,yout');
figure(2);
plot(time,u,'k');
xlabel('time(s)'),ylabel('u');