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Calculating Voltage in an AC Circuit | Matlab

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In this tutorial, we will determine the voltages at each node of the following circuit using Matlab.

Determine the voltage at each node of the circuit of figure:

RLC Series Circuit Voltage Calculation

The impedances correspond to an inductor and capacitor in the above circuit can be obtained using the following expressions:

$\begin{align}  & {{Z}_{C}}={{\left. \frac{1}{j\omega C} \right|}_{\omega =30\text{ krad/s}}} \\ & {{Z}_{L}}={{\left. j\omega L \right|}_{\omega =30\text{ krad/s}}} \\\end{align}$                        

From the voltage expression, we can obtain the phasor value as:

$V=10\exp (j\frac{\pi }{4})\text{ V}$

For the current, we have the following expression:

$I=\frac{V}{R+{{Z}_{C}}+{{Z}_{L}}}$

Now, the voltage across each element in the circuit can be obtained as:

$\begin{align}  & {{V}_{R}}=IR \\ & {{V}_{C}}=Z{}_{C}I \\ & {{V}_{L}}={{Z}_{L}}I \\\end{align}$

Now, let’s formulate above mentioned equations in Matlab:

Matlab Code for Voltage Calculation in an AC Circuit


%Simple AC Circuit
clear all;close all;clc
Voltage= 10*exp(j*pi/4); % Source Voltage
Omega=30e3; % Angular Frequency 
R= 100; % Circuit Resistance
L= 3e-3; % Circuit Impedance (3mH)
C= 0.9e-6; % Circuit Capacitance (0.9 microFarad)
Zc= 1/(j*Omega*C); % Capacitive Reactance 
Zl= j*Omega*L; % Inductive Reactance 
I= Voltage/(Zl+Zc+R) % Total Circuit Current
VR= I*R % Voltage across Resistor 
VL= I*Zl % Voltage across an Inductor 
VC= I*Zc % Voltage across Capacitor
%=============================================

Results:

VR =

   8.4467 + 2.5974i

VL =

  -2.3377 + 7.6021i

VC =

   0.9620 – 3.1284i

You May Also Read: RLC Circuit Transfer Function using Matlab

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About Ahmad Faizan

Mr. Ahmed Faizan Sheikh, M.Sc. (USA), Research Fellow (USA), a member of IEEE & CIGRE, is a Fulbright Alumnus and earned his Master’s Degree in Electrical and Power Engineering from Kansas State University, USA.

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