PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

Alternating Current Analysis 299

Example 3.18

Create the script fi le I_versus V_ R L C that analyzes the effect of changing R of the series

RLC circuit diagram shown in Figure 3.78, for the following values of R— 540 Ω, 1.35 kΩ,

and 2.7 kΩ, over the range 4 103 ≤ ω ≤ 2 π (^) (^15) * 103 rad/s, linearly spaced every ∆ω =
500 rad/s, and returns the following plots:

1. Z(ω) versus ω


2. I(ω) versus ω


3. ∠Z(ω) versus ω


4. VC(ω) versus ω

L = 30 mH

C = 0.01 μF

4 krad/ s < w < 6.28*15 krad/s

V = 5

I

Z(w)

0 °

R

FIGURE 3.78

Network of Example 3.18.

MATLAB Solution

% Script file: I _ vsV _ RLC

% R = 540, L = 30mH, C =. 01uF

V = 5;

RI = 270;

R1 = RI*2;

C = .01e-6;

L = 30e-3;

W = [4000:500:2*pi*15e3];

XC = -1./(W.*C);

XL = W.*L;

Z1 = sqrt(R1^2+(XL+XC).^2);

Angle1 = atan((XL+XC)./R1);

I1 = V./Z1;

VC1 = (V*XC)./Z1;

% R = 1.35K, L = 30mH, C =. 01uF

R2 = RI*5;

Z2 = sqrt (R2^2+(XL+XC).^2);

Angle2 = atan((XL+XC)./R2);

I2 = V./Z2;

VC2 = (V*XC)./Z2;

% R = 2.7K, L = 30mH, C =. 01uF

R3 = RI*10;

Z3 = sqrt(R3^2+(XL+XC).^2);

Angle3=atan((XL+XC)./R3);

I3 = V./Z3;

VC3 = (V*XC)./Z3;

figure(1)