I want to do a general code to make a transfer function of any rlc circuit

is there any functions or tips to help me in the code. the user only knows the R, L and C values, the currents are unknowns, the laplace out and input of the circuit are determined by the user and the code doesnt know what are they. i know it is a bit complecated, the professor gave us this assignment and the dead line is two days away.

again i have to do a general code to generate any transfer function of an rlc circuit with any number of loops and any cmbination of elements.

Answer 1

[Sulaymon Eshkabilov]

The transfer function of RLC circuit will be derived using input voltage vs. voltage across capacitor (1) or input voltage vs. current (2):

(1) Considering Vout vs. Vin a simple series RLC circuitry:

Vout/Vin = 1/(LCs^2+RCs+1) can be also written as (1/LC)/(s^2+R/L+1/LC)

(2) The relationship between current and input voltage then,

I/Vin = 1/(R+Ls+1/Cs)

OR

I/Vin = Cs/(CLs^2+CRs+1)

R = 100; % Ohm
L = 20;  % H 
C = 1e-6; % F
NUM1 = 1;
DEN1 = [L*C R*C 1];
TF1 = tf(NUM1, DEN1)

TF1 =
 
             1
  ------------------------
  2e-05 s^2 + 0.0001 s + 1
 
Continuous-time transfer function.

NUM2 = [C 0];
DEN2 = [C*L R*C 1];
TF2 = tf(NUM2, DEN2)

TF2 =
 
          1e-06 s
  ------------------------
  2e-05 s^2 + 0.0001 s + 1
 
Continuous-time transfer function.

[Luai]

this is not what i want, your code is only for simple series circuit, i asked for any complecated circuit, beside i dont know the transfer function of the circuit the user have so i cannot put a fixed num & den in the code.

thanks

[Sam Chak]

Yes, it is possible to create such a custom function that can assess any RLC circuits with strictly linear components, and it returns the Transfer Function of RLC circuit.

However, the function will require the user to key in the inputs about the information of the RLC circuit. The function will require some special functions from the Symbol Math Toolbox.

[Sam Chak]

Now, if such an auto-modeling MATLAB function is available, how do you (as a user) validate the accuracy of the transfer function? Would 100% trust all results without any exceptions?

As an Electrical Design Engineer, I would prefer to have a function that can covert the circuits from LTspice, and Proteus to an equivalent Simscape block diagram.

[Luai]

how? my major is electric engineering too but my knowledge in matlab is a little.