Multisim Transient Analysis for LC parallell circuit

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Discussion Overview

The discussion revolves around using Multisim for transient analysis of a simple LC parallel circuit. Participants are addressing issues related to circuit configuration, measurement challenges, and software functionality while attempting to analyze the behavior of the circuit over time.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • The original poster describes their circuit setup and expresses confusion about the lack of voltage variables for the components in Multisim.
  • Some participants suggest that the circuit may be incorrectly grounded, leading to unhelpful results.
  • One participant advises removing unnecessary connections to clarify the circuit configuration.
  • There is a discussion about the distinction between series and parallel connections, noting that with only two components, the distinction may be ambiguous.
  • The original poster continues to experience issues with a flat current graph and seeks further advice on using Multisim effectively.

Areas of Agreement / Disagreement

Participants generally agree that the circuit configuration may be problematic, but there is no consensus on the best approach to resolve the measurement issues or the correct setup for the analysis.

Contextual Notes

Participants express uncertainty regarding the proper configuration of the circuit in Multisim and the implications of grounding on the analysis results. There are unresolved questions about the correct interpretation of series versus parallel connections in this context.

Who May Find This Useful

Individuals interested in circuit simulation, specifically using Multisim for transient analysis, as well as those studying LC circuits and their behavior in parallel configurations.

DrOnline
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Homework Statement



The main problem is that I need help using Multisim for transient analysis of a simple LC parallell circuit. I am doing something wrong.

C= 3*10^-5 F
L= 3*10^-3 H

The Capacitor is charged to 10V

What happens to the energy of the capacitor when we connect it in parallel with the inductor. Trace the voltage of the parallel connection and the current of the inductor until about 2ms after connecting.

Use Simulink.


Homework Equations



T=2*pi*sqrt(LC) = 1.89 ms

f= 1/T = 1/(2*pi*sqrt(LC)) = 531 Hz

The Attempt at a Solution



I have created this circuit:

31G6nWe.jpg


I suspect something is wrong already here, because the program will not let me rename nets.

sjX2ecH.jpg


"Preferred net name cannot be modified when a global connector is in connection to the net."


I go to:
Simulate->Analyses->Transient Analysis

I set the stop time to about 5 periods. 0.01s.

Now.. why is there no voltage variable for either component?

U5o5SF7.jpg


I add I(L1) and simulate.

W1BH4qQ.jpg


Can somebody please point out where I am going wrong..? I am sure there are multiple mistakes, I am not too good with Multisim yet.
 
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I'm not familiar with the details of using Multisim, but it appears to me that your circuit has both ends of both components shorted together and grounded. I can't imagine getting any reasonable results from that.

Try eliminating one or the other of the paths to ground.
 
Alright, I added a battery with no output, and now I can measure more things, but even if I only select the current through the inductor I get a flat graph.

9Ebnw56.jpg

TRLmVh5.jpg
 
Eliminate the battery. Eliminate the wire. NO connection.
 
But.. aren't they in series now..?

LiHnd5H.jpg
 
DrOnline said:
But.. aren't they in series now..?

LiHnd5H.jpg

With only two components, there is no distinction between series and parallel connection.
 
gneill said:
With only two components, there is no distinction between series and parallel connection.

Bingo. That's what I thought, but since the task specified parallel I tried to come up with something.

The problem with the current graph being flat is still there, would love for some Multisim advice on this!

Thanks for the help thus far!
 
DrOnline said:
Bingo. That's what I thought, but since the task specified parallel I tried to come up with something.

The problem with the current graph being flat is still there, would love for some Multisim advice on this!

Thanks for the help thus far!

I'll see if I can find someone who knows Multisim to have a look-in.
 

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