Sloving a depentant voltage source problem using node voltage

In summary, the conversation discusses a problem with approaching a dependent voltage source problem using node voltages. The circuit has four nodes, two of which are part of a supernode. The issue is with solving for the current across the 60 Volt source and a recursion problem with solving for iψ. A solution is proposed to treat nodes A and C as one big super node and use two equations to solve for Vb and Vc. The conversation also mentions the possibility of transforming the circuit to remove the supernode.
  • #1
cybhunter
25
0
Hi everyone,

I currently stumped in the process of approaching a dependent voltage source problem using node voltages. Attached is the circuit.

What I know:

the Node north of the 60V supply with also be 60V

there are four nodes, two when supernodes are used


What I'm confused about:

with the super node being the 6iψ, KCL states the sums must be zero

when I try to solve, I end up getting the equation (using v2 as the junction of the dependent, and both 3Ω resistors):

[(60-v1)/2]+[(V2-V3)/3]+[V2/3]=0
I am not sure how to calculate the current across the 60Volt source

:confused:


In addition, I end up having a recursion problem trying to solve for iψ

Since V2 is 60+6iψ, and iψ is ([V2-V2]/3), I end up with

V2=60+6([V2-V3]/3)


any help would be greatly appreciated

Joe
 

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  • #2
Simply treat A and C as a one big (super) node.
So we only have one unknown node Vb

attachment.php?attachmentid=44355&stc=1&d=1330171555.jpg


Current leaving the node is equal current entering the node.

For node B

Vb/24 + (Vb - 60)/2 + (Vb - Vc)/3 = 0 (1)

And one additional equation

Vc = Va + 6*Iψ = Va + 6*(Vc - Vb)/3 = 2Vb-Va = 2Vb - 60 (2)

So we have

Vb/24 + (Vb - 60)/2 + (Vb - (2Vb - 60))/3 = 0

http://www.wolframalpha.com/input/?i=+b/24+++(b+-+60)/2+++(b+-+(2b+-+60))/3+=+0

But we can remove the supernode from the circuit. We you can transform this circuit, legally, and get a new circuit which is equivalent to the old one

attachment.php?attachmentid=44354&stc=1&d=1330171517.jpg
 

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Last edited:

Related to Sloving a depentant voltage source problem using node voltage

1. What is a dependent voltage source?

A dependent voltage source is a type of voltage source that is controlled by another voltage or current in the circuit. It can either be a voltage-controlled voltage source (VCVS) or a current-controlled voltage source (CCVS).

2. How do you solve a dependent voltage source problem using node voltage?

To solve a dependent voltage source problem using node voltage, follow these steps:

  • Identify the dependent voltage source in the circuit and its controlling voltage or current.
  • Assign a variable to represent the dependent voltage source in the node voltage equations.
  • Write the node voltage equations for each node in the circuit, including the variable for the dependent voltage source.
  • Solve the equations simultaneously to find the node voltages.

3. What is the difference between a VCVS and a CCVS?

A VCVS is a voltage-controlled voltage source, meaning that the voltage output of the source is directly proportional to the controlling voltage. On the other hand, a CCVS is a current-controlled voltage source, meaning that the voltage output is directly proportional to the controlling current.

4. Can a dependent voltage source be used as a standalone source?

No, a dependent voltage source cannot be used as a standalone source. It always needs a controlling voltage or current in the circuit in order to function.

5. How do you handle dependent voltage sources in circuit analysis?

Dependent voltage sources can be handled in circuit analysis by using the appropriate equations and techniques for the type of source. For VCVS, the controlling voltage should be treated as a variable in the node voltage equations. For CCVS, the controlling current can be treated as a variable in the loop equations.

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