# Plotting Phase angle in Matlab

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Matthew Portnoy on 25 Oct 2020
Commented: Sindar on 25 Oct 2020
I am trying to plot 2 phase angle graphs based on two impedance calculations. The problem is when i try to calculate the angle with unwrap(angle(Zc)), the plot looks nothing like it should. I am using 5 different text files as data, those are attached. And below is my code and my graphs, then graphs of what I am supposed to be getting.
clear all;
clc;
Czero = 7.524/1e3;
Cpos = 1.2027/1e3;
Gzero = 2/1e8;
Gpos = 2/1e8;
w(1)=0;
Zc(1)=0;
Zcpos(1)=0;
Zcmag(1)=0;
Zcposmag(1)=0;
i=1;
k=1;
n=10;
for i=1:size(Rzero1,1)
w(i) = 2*pi*freq1(i);
Zcmag(i) = abs(((Rzero1(i)+1j*w(i)*Lzero1(i))./(Gzero+1j*w(i)*Czero))); %magnitude of Zc
Zc(i) = sqrt(((Rzero1(i)+1j*w(i)*Lzero1(i))./(Gzero+1j*w(i)*Czero)));
end
for k=1:size(Rpos1,1)
w(k) = 2*pi*freq1(k);
Zcposmag(k) = abs(((Rpos1(k)+1j*w(k)*Lpos1(k))./(Gpos+1j*w(k)*Cpos))); %magnitude of Zc
Zcpos(k) = sqrt(((Rpos1(k)+1j*w(k)*Lpos1(k))./(Gpos+1j*w(k)*Cpos)));
end
figure(1)
semilogx(freq1,Zcmag);
figure(2)
semilogx(freq1,Zcposmag)
Zcphase = unwrap(angle(Zc));
Zcposphase = unwrap(angle(Zcpos));
figure(3);
semilogx(freq1,Zcphase);
figure(4);
semilogx(freq1,Zcposphase);
Zc phase for zero sequence Zc phase for positive sequence  Sindar on 25 Oct 2020
First off, "load" is for Matlab files, not raw text. Check out textscan. If your code isn't error-ing, you probably have old versions of the variables sitting around somehow
Next, there are several code issues to clean up:
This loop can be done with elementwise vector operations. Change it from
for i=1:size(Rzero1,1)
w(i) = 2*pi*freq1(i);
Zcmag(i) = abs(((Rzero1(i)+1j*w(i)*Lzero1(i))./(Gzero+1j*w(i)*Czero))); %magnitude of Zc
Zc(i) = sqrt(((Rzero1(i)+1j*w(i)*Lzero1(i))./(Gzero+1j*w(i)*Czero)));
end
to
w = 2*pi*freq1;
Zc(i) = sqrt((Rzero1+1j*w.*Lzero1)./(Gzero+1j*w*Czero));
Zcmag = abs(Zc.^2);
Also, these lines are completely unnecessary:
w(1)=0;
Zc(1)=0;
Zcpos(1)=0;
Zcmag(1)=0;
Zcposmag(1)=0;
i=1;
k=1;

#### 1 Comment

Sindar on 25 Oct 2020
Huh, reading the load documentation, it actually does support text files. Still not a good choice, but perhaps not the source of your problem

R2020a

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