Calculating Capacitor Current using i= C* dv/dt

I would like to use Matlab to calculate capaitor current for the following

i = C * dV/dt

i = 0.2uF * 12V/dt

128kHz frequncy

Answer 1

[Deepak]

Hey @Gary,

To calculate the capacitor current for the given circuit, you can use MATLAB's symbolic math toolbox to evaluate the expression for the capacitor current as a function of time.

Sample code to calculate the capacitor current for a 0.2uF capacitor, with a voltage input of 12V at a frequency of 128kHz is given below.

syms t;
C = 0.2e-6; % capacitance in Farads
V = 12; % voltage in volts
f = 128e3; % frequency in Hertz
w = 2*pi*f; % angular frequency in radians per second
i = C*diff(V*sin(w*t), t); % evaluate the capacitor current using symbolic differentiation

This creates a symbolic expression for the capacitor current as a function of time. In this example, the input voltage is a sine wave; you could use different input waveforms as needed by replacing the `V*sin(w*t)` term with a different function.

Once the symbolic expression is created, you can plot the capacitor current as a function of time using the `ezplot` function. For example:

ezplot(i, [0, 1/f]); % plot the capacitor current for one cycle of the input waveform
title('Capacitor Current vs Time');
xlabel('Time (s)');
ylabel('Current (A)');

This would create a plot showing the capacitor current as a function of time, for one cycle of the input waveform. You can adjust the plot range or add additional features as needed.