Thiết kế hệ thống dùng matlab

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Thiết kế hệ thống dùng matlab


Phương pháp sớm pha dùng giản đồ Bode, hàm leadbode

function[gc]=leadbode(g,K,PM,GM)
%This function using the Bode diagram make the phase lead compensation, 
%input is tf, Kp(or Kv, Ka) (if have no K, Kc=1),phase margin and gain 
%margin which expect.
%-------------------------------------------------------|%
            |%
%-------------------------------------------------------|%
if (nargin==3) 
    GM=PM;
    PM=K;    
    Kc=1;
elseif (nargin==4)
    Kc=Kc_error(g,K);
end

%Now, find margin
g1=Kc*g;
[gm1,Pm,wcg1,wcp1]=margin(g1);
clear gm1 wcp1 wcg1

%Step 4 in course, loop at here...
%Phase angle adder
%Step 5
theta=2;
max_ang=30;
while(theta89*pi/180)
        Result=sprintf('Bai toan vo nghiem')
        gc=nan;
        break;
    end
    %Step 6
    anpha=(1+sin(phimax))/(1-sin(phimax));
    %Step 7
    [mag phase w]=bode(g1);
    clear phase
    mag=mag(:);
    w=w(:);
%Find freq value which satisfies relation: Abs(G1(jw'c))=1/sqrt(anpha)
    temp=1/sqrt(anpha);
    t=find((mag>temp-7)&(mag=GM)&(pmc>=PM))
        clf;
        hold on
        bode(gc,g);
        bode(gkq,'r')
        legend('Phase lead compensation','Org Tranfer Function','Compensated Tranfer Function');
        margin(g*gc);
        pause();
        clf;
        hold on;
        step(feedback(gkq,1),feedback(g,1));
        grid on
        legend('Compensated Tranfer Function','Org Tranfer Function');
        pause();
        close();
        break
    else
        clear gc gmc pmc wgc wpc gkq
        theta=theta+1;
        if (theta==max_ang)
            Result=sprintf('Bai toan vo nghiem')
            gc=nan;
        end
    end
end
%End

Phương pháp trễ pha dùng giản đồ Bode, hàm lagbode

function[gc]=lagbode(g,K,PM,GM)
%This function make the phase lag compensation, input is tf,Kp(or Kv,Ka) 
%phase margin and gain margin which expect.(Kc=1) in this func if have no K. 
%gc=lagbode(g,K,PM,GM)
%-------------------------------------------------------|%
                |%
%-------------------------------------------------------|%

if (nargin==3)
    Kc=1;
%This code to find Kc
elseif (nargin==4)
    Kc=Kc_error(g,K);
end

g1=Kc*g;
[gm1,Pm,wcg1,wcp1]=margin(g1);
clear gm1 wcp1 wcg1

%Phase angle adder
theta=2;
max_ang=30;
%Step 3


while(thetaphi-10)&(phase=1)
        clear vltemp phase
        wc=w(min(t)+degree-1);    
        clear w degree t    
        w=abs(wc-0.5):0.001:(0.5+wc);
        w=w(:);        
        [mag,phase]=bode(g1,w);    
        phase=phase(:);    
        [value,degree]=min(abs(phase-phi));
        wc=w(degree);    
        clear value w
%Find anpha
        anpha=1/abs(freqresp(g1,wc));
%Caculate time constant T
        T=ceil(12/(wc*anpha));
        clear wc
%Phase lag compensation
        gc=Kc*tf([anpha*T 1],[T 1]);    
%Step 7
        gkq=g*gc;     
        [gmc,pmc,wgc,wpc]=margin(gkq);    
        gmc=20*log10(gmc);
        if ((gmc>GM)&(pmc>PM))
            clf;
            hold on
            bode(gc);
            bode(g);
            bode(gkq,'r')
            legend('Phase lag compensation','Org Tranfer Function','Compensated Tranfer Function');
            margin(gkq);
            pause();
            clf;        
            if(g.iodelay==0)
                clf;
                hold on;
                step(feedback(gkq,1),feedback(g,1));
                grid on
                legend('Compensated Tranfer Function','Org Tranfer Function');
                pause();
                close();
            end
            break
        else           
            theta=theta+1;
            if (theta==max_ang)
                Result=sprintf('Bai toan vo nghiem')
                gc=nan;
            end
        end
  else 
        clear gc gmc pmc wgc wpc gkq
       theta=theta+1;
       if (theta==max_ang)
           gc=nan;
           Result=sprintf('Bai toan vo nghiem')
       end
  end
end
%End

Bạn cần load hàm Kc_error để có thể chạy được các hàm trên.

function[Kc]=Kc_error(g,k)
%Kc=Kc_error(g,k)
%Assume that: 
%If tf have no ideal integral, k=Kp
%If tf have 1 ideal integral, k=Kv
%If tf have 2 ideal integral, k=Ka
%-------------------------------------------------------|%
%|(C)2005 Bui Trung Hieu                |%
%|Website: www.khvt.com                    |%
%|Email: hieu@khvt.com                |%
%-------------------------------------------------------|%
if (nargin==2)
    if(length(k)==1)
        sw=length(find(pole(g)==0));
        if (sw==0)
    %This code to find Kc from Kp
            a=dcgain(g);
            Kc=double(k/a);
        elseif (sw==1)
    %This code to find Kc from Kv
            s=tf('s');
            a=dcgain(minreal(s*g));
            Kc=double(k/a);
        elseif (sw==2)
    %This code to find Kc from Ka
            s=tf('s');
            a=dcgain(minreal(s^2*g));
            Kc=double(k/a);
        end
    else
        Kc=[];
        error('???Ban nhap sai so chieu cua k!!!');        
    end
else
    Kc=[];
    error('???Xem help de co them thong tin!!!');
end

Nguon: Suu tam