AC analyses issue in ADE

The most likely issue here is that perhaps the phases of the currents are not the same, since the waveforms for each current in an AC analysis are complex. So summing the magnitudes is not really giving you a correct answer. Did you try summing the currents (e.g. IF(...)+IF(...)+IF(...) and then taking the magnitude of the result of the sum?

Of course I'm sure there's a good reason for using a software release from 17 years ago which was last updated over 10 years ago, but that's unlikely to be the issue here.

Andrew

Hello Andrew,,

Thank you for answering my question. I think the phase difference you pointed out in the current  is reasonable. But I don't figure out what the meaning of "e.g. IF(...)+IF(...)+IF(...)“ in your answer. Could you explain it further?I really appreciate it if you could reply.

garfield

Hello Andrew,,

Thank you for answering my question. I think the phase difference you pointed out in the current  is reasonable. But I don't figure out what the meaning of "e.g. IF(...)+IF(...)+IF(...)“ in your answer. Could you explain it further?I really appreciate it if you could reply.

garfield

If you use Tools->Calculator and then on the ac tab in the Selection choices section, you click on "if" and then click on the three voltage source terminals in turn. Then press "+" in the panel on the left twice to add them together (the calculator operates using Reverse Polish notation, but assembles a normal infix expression) you'll get something like this:

Then press the little graph icon to the right of where it says "Append" above, and it will plot (by default) the magnitude of the sum of complex currents. Alternatively you could click on "mag" or "phase" in the list of functions in the panel on the right, to explicitly take the magnitude or phase of the sum, and then plot that instead.

Andrew

Dear garfieldzz,

garfieldzz said:

I think the phase difference you pointed out in the current  is reasonable. But I don't figure out what the meaning of "e.g. IF(...)+IF(...)+IF(...)“ in your answer. Could you explain it further?I really appreciate it if you could reply.

Just to add to Andrew's correct response to help you understand garfieldzz, the currents are complex quantities having real and imaginary parts. Therefore, the sum of their magnitudes is not the same as their complex sum and its resultant magnitude. Specifically, if each of your currents is called I1, I2, and I3, then the following relatioship is NOT necessarily true;

|(I1_real + jI1_imag)| + |(I2_real + jI2_imag)| + |(I3_real + jI3_imag)| = |(I1_real + I2_real + I3_real) + j(I1_imag + I2_imag + I3_imag)|

Kirchoff's current law requires that:  |(I1_real + I2_real + I3_real) + j(I1_imag + I2_imag + I3_imag)| = 0

but does not require that the sum of the magntudes of each current is 0, or |(I1_real + jI1_imag)| + |(I2_real + jI2_imag)| + |(I3_real + jI3_imag)| = 0.

In your initial plot, you are plotting the sum of the magnitudes of each current and there is no constraint on their sum being 0.

Does this help along with Andrew's very nice responses your understanding garfieldzz?

Shawn