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These lecture slides are delivered at The LNM Institute of Information Technology by Dr. Sham Thakur for subject of Mathematical Modeling and Simulation. Its main points are: Continuous, Pdfs, Random, Variables, Probability, Uniform, Distribution, Solution, Program, Generate
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Lecture: Coupled Systems based Models
Models : electrical systems and Resonance
C
R
L
V
I
Current in circuit = I
Voltage Source = V
Voltage drop across resistance = RI
Voltage drop across capacitor = Q/C
Voltage drop across inductor = L dI/dt
Kirchoff’s law:
All voltage drops = Applied Voltage
Initial conditions:
Current (t = 0) =I(0) = 0
Charge (t = 0) = Q(0) = 0.
Mathematical modeling:
For the left loop, the voltage drops across each element of the circuit yields:
Voltage from the source = voltage drop across L + Voltage drop across R
12 1 dI 1 (^) / dt 4 ( I 1 I 2 )
or 4 1 4 2 12 1 I I dt
dI
Where I1 is the current in first loop and I2 is the current in the second loop.
For the next loop again the voltage balance gives:
0 6 I (^) 2 4 ( I 2 I 1 ) 4 I 2 dt
When we differentiate it we get the following balance equation:
2
2 1 0 10 4 4 I dt
dI
dt
dI 0. 4 0. 4 2 0 2 1 I dt
dI
dt
dI
This model is a linear first order non-Homogeneous, ODE Based model
Initial conditions are : I1(0) = 0.0; I2(0) =0.
1 I I dt
dI
2 1 I dt
dI
dt
dI
C = 0.25 farad
R 1 =4 ohms
L = 1 henry
V = 12 Volts
R 2 =4 ohms
Switch
t = 0
I 1 I 2 I (^1) I 2
The current in Tank 2
increases from zero
exponentially and reaches to
a peak value then it
eventually decays to zero.
The current in loop-1 grows
to a peak values and then
exponentially to a saturation
value of 3.
Model in MATLAB/SIMULINK
1 I I dt
dI 2
2 1
dI
dt
dI
Initial conditions are :
I 1 (0) = 0.0; I 2 (0) =0.
0 2 4 6 8 10
0
1
2
3
4
5
current
time
current in loop-1: I 1 current in loop-2: I 2
This has two coupled loops. The Kirchoff’s law for voltage balance will give the model equations:
C = 0.25 farad
R 1 =4 ohms
L = 1 henry
V = 12 Volts
L 2 =2 henry
Switch
t = 0
I 1 I 2 I (^1) I 2
This model is a linear, second order non-Homogeneous, ODE Based model
Initial conditions are :
I1(0) = 0.0; I2(0) =0.
1 I I dt
dI
C = 0.25 farad
R 1 = 0. ohms
L = 1 henry
V = 12 Volts L 2 = henry
Switch
t = 0
I 1 I 2 I (^1) I 2
2
2 1 2
2
2
0 0. 2 0. 2 2 I dt
dI
dt
dI
dt
d I
Model in MATLAB/SIMULINK
Initial conditions are :
I 1 (0) = 0.0; I 2 (0) =0.
1 I I dt
dI 2
2 1 2
2
2
dI
dt
dI
dt
d I
I1(t)
I2(t)
I2(t)
-0.4I1 + 0.4I2+
0.2dI1/dt - 0.2dI2/dt +2.I
example 2 : coupled electrical model
dI1/dt
I To Workspace
I To Workspace
Scope
Scope
1 s Integrator
1 s Integrator
1 s Integrator
-0.
Gain
Gain
Gain
Gain
-0. Gain
12 Constant
The current in loop-1 increases and reaches a saturation value of 30. However, the current in loop-2 first increases to a peak value and then oscillates with decreasing amplitude,
Initial conditions are :
I 1 (0) = 0.0; I 2 (0) =0.
Model in MATLAB/SIMULINK
1 I I dt
dI
2
2 1 2
2
2
dI
dt
dI
dt
d I
0 5 10 15 20
0
5
10
15
20
25
30
current
time
current in loop - 1
0 5 10 15 20
-1.
-1.
-0.
current
time
current in loop-
C = 0.25 farad
R 1 = 0.4 ohms
L = 1 henry
Sinusoidal
source
L 2 =2 henry
Switch
t = 0
I 1 I 2 I (^1) I 2
This has two coupled loops. One loop has a voltage source which is AC
type with V= Asin(wt). Let A = 12 and w can be changed from 0.1 to 2.5.
We want to study what will happen when we change this w value.
So, first develop mathematical model.
The Kirchoff’s law for voltage balance will give the model equations:
This model is a linear, second order, non-Homogeneous, ODE Based model
Initial conditions are :
I 1 (0) = 0.0; I 2 (0) =0.
C = 0.25 farad
R 1 = 0. ohms
L = 1 henry
Sinusoidal
source L 2 = henry
Switch
t = 0
I 1 I 2 I (^1) I 2
This has two coupled loops.
The Kirchoff’s law for
voltage balance gives the
model equations:
I I A wt dt
dI (^1) 0. 4 1 0. 4 2 sin
2
2 1 2
2
2 0 0. 2 0. 2 2 I dt
dI
dt
dI
dt
d I
Driving force = Asin(wt); A = 12, w = 0.
Initial conditions are :
I 1 (0) = 0.0; I 2 (0) =0.
Effect of angular frequency parameter (w) on currents
I I A wt dt
dI
2
2
dI
dt
dI
dt
d I
Current in loop – 1 Current in loop^ –^2
RESONANCE
Driving force = Asin(wt); A = 12, w = 0.
Initial conditions are :
I 1 (0) = 0.0; I 2 (0) =0.
Effect of angular frequency parameter (w) on currents
I I A wt dt
dI
2 1 2
2
2
dI
dt
dI
dt
d I
Current in loop – 1 Current in loop^ –^2
RESONANCE
Driving force = Asin(wt); A = 12, w = 0.
Initial conditions are :
I 1 (0) = 0.0; I 2 (0) =0.
Effect of angular frequency parameter (w) on currents
I I A wt dt
dI
2 1 2
2
2
dI
dt
dI
dt
d I
Current in loop – 1 Current in loop^ –^2
RESONANCE