PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

162 Practical MATLAB® Applications for Engineers

2. The resulting system nodal matrix equation is given by

31

14

2

3









































Y

V

VI

X

 Y 

*V 

where Y is the admittance matrix of the network, and the current vector I is given by

I

2

3













MATLAB Solution

>> Y = [3 -1;-1 4];

>> I = [2;3];

>> V= inv(Y)*I;

>> VX = V(1);

>> VY =V(2);

>> Result = [VX VY];

>> disp (‘**********************************’)

>> disp (‘The voltage drops Vx and Vy (in volts) are given by:’);

>> disp (Result)

>> disp (‘**********************************’)

************************************************************

The nodal voltages Vx and Vy (in volts) are given by:

1.0000 1.0000

************************************************************

Example 2.19

The switch shown in the circuit diagram in Figure 2.62 has been in position a for a long

time. At t = 0, the switch is moved to position b where it remains for 2 s and then moves

back to position a, where it remains indefi nitely.

1. Obtain analytical expressions for vC(t) and iC(t) for all t


2. Use MATLAB to obtain plots over the range 0 s ≤ t ≤ 10 s of
   a. The voltage vC(t) versus t
   b. The current iC(t) versus t

FIGURE 2.62
Network of Example 2.19.

b

a

R 3 = 3 Ω

R 2 = 1 Ω

R 1 = 7 Ω

V 0 = 100 V

C = 0.5 F

iC(t)

vC(t)

+

−