# MATLAB: Verification of Superposition Principle

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1. Mar 7, 2018

### Bloopy

1. The problem statement, all variables and given/known data

Verify Superposition Principle using Matlab, given a DC source of 100V, an AC source of 50V, 60Hz and three resistances, R1=10 ohms, R2=20 ohms and R3=15 ohms.

I created the circuit below and ran the program. Result:

2. Relevant equations

None, just running the program.

3. The attempt at a solution

Now, the Principle of Superposition states the total current in any part of a linear circuit equals the algebraic sum of the currents produced by each source separately. I am trying to verify the current flowing through R3 = 15 ohms resistance.

1. I short circuit the DC voltage source and run the program. Result:

2. I then short circuit the AC voltage source and run the program. Result:

As clearly can be seen, the Superposition Principle is not verified. I am unable to reason where the discrepancy is.

Last edited: Mar 7, 2018
2. Mar 7, 2018

### Staff: Mentor

I'm not the best with circuits, but I don't understand your result when you short-circuit the DC source. How can you measure 94.4 V in that circuit?

3. Mar 7, 2018

### Bloopy

Yeah, I altered the step-size to get the accurate value of RMS voltage. Edited the question.

4. Mar 7, 2018

### lewando

The Current Measurement block is processing a current waveform with both AC and DC components. The block outputs the instantaneous current Not sure how this block will represent a static value of an AC current. What happens if you use an RMS block right before Display3?

5. Mar 8, 2018

### Bloopy

Sorry for the delayed replies, I am in college for 12-14 hours during the day.

6. Mar 8, 2018

### lewando

So what is now displayed is the RMS value of the combined AC and DC currents. You should be able to verify this result by using your single-source results and a googleable formula for determining the RMS value of an AC signal with a DC offset.