MATLAB: RLC Circuit Equation Implementation-Runge Kutta

runge kutta

Hello, I need to convert an RLC equation to work inside the functions I have wirtten. Currently MatLab is telling me there are too many variables inside my equation for it to work. Here is the code of the function I am trying to work with
function [derriv_value] = RLC(y)
%Function that contains the derrivative value
%RLC Implementation: The equation is given by L*Q'' + R*Q' + (1/C)*Q = E(t)
% E(t) is the sum of total voltage drop across the circuit.
% R is resistance, L is indunctance, and C is capacitance. Q Is the charge
% in coloumbs. This equation is currently in a second order form.
% In most cases, the voltage in the system is known, it is usually the
% current (I) that is unknown.
% If we differentiate both sides and subsitute Q for I, we get,
% L*I'' + R*I' + (1/C)*I = E'(t)
% Since this is the more pratical case, we will use this format.
% Here are some values that could be used to simulate this.
% These above are some example values.
R = 10; % Resistance (Series RL Branch), Ohms..
L = 100e-3; % Inductance (Series RL Branch), H..
C = 50e-6; % Capacitor (Series RLC Branch), F
derriv_value = L*y(3)+R*y(2)+(1/C)*y;
end
And this function will be called in a Runge Kutta implementation file. I'll attach it. I have another file called FunctionC that has a format that matlab accepts. It works with the Runge Kutta file.

Best Answer

Instead of this
derriv_value = L*y(3)+R*y(2)+(1/C)*y;
Do you mean this?
derriv_value = L*y(3)+R*y(2)+(1/C)*y(1);
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