How to deal with dc source on ac circuits?

In summary, the conversation discussed using superposition theorem to solve for steady state voltage v. One person began by solving with voltage source using mesh analysis and obtained a value of 3.2cos(6t+126.87) for the voltage. They then expressed confusion about dealing with the other source in AC analysis and asked about using Phasors or analyzing AC circuits with a single fixed frequency. The other person suggested using Phasor impedances to write AC KCL equations and ignoring the DC current source for the AC analysis. They also advised writing a Phasor KCL equation for the top middle node. To get the contribution to v from the 4 amp source, it was suggested to short circuit the voltage source and consider
  • #1
Secre
4
2
Homework Statement
Find the steady state voltage v.
Relevant Equations
v(t) = V(dc) + V(ac)
IMG_20210526_221720.jpg

We are tasked to solve for the steady state voltage v using superposition theorem. I start with solving with voltage source using mesh analysis and got the current flowing through the 3 ohms resistor and get the first value of the voltage which is 3.2cos(6t+126.87). Now my problem is I am confused on how to deal with the other source since we're in ac analysis. I tried solving it with dc analysis but I think it's wrong.
 
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  • #2
Have you started using Phasors yet or analyzing AC circuits with a single fixed frequency?
 
  • #3
Yes
 
  • #4
Great! The 4A current source looks like a/an __________ for AC, so you can probably use the Phasor impedances to write the AC KCL equation(s)...
 
  • #5
Should I assume w= 0 rad/s for the current source since I'll be needing it to convert it into phasor circuit?
 
  • #6
Well, I'd just ignore the DC current source for the AC analysis, since an ideal current source has infinite output resistance (looks like an open circuit). Can you write the Phasor KCL equation for the top middle node (since the DC current source is not an open)?
 
  • #7
IMG_20210526_232911.jpg
 
  • #8
To get the contribution to v from the 4 amp source just start by short circuiting the voltage source. Now in the steady state the inductors with be short circuits and the capacitor will be an open circuit. You are then left with three parallel circuit elements (one current source and two 4 ohm resistors.) I think you can take it from there.
 

Related to How to deal with dc source on ac circuits?

1. What is the difference between AC and DC sources?

AC (alternating current) sources produce a current that changes direction periodically, while DC (direct current) sources produce a current that flows in one direction only.

2. How do I convert a DC source to an AC source?

This can be done using a device called an inverter, which converts the DC input into an AC output.

3. Can I connect a DC source directly to an AC circuit?

No, it is not recommended to connect a DC source directly to an AC circuit as it can cause damage to the circuit and potentially harm the user. It is important to use the appropriate conversion devices.

4. What precautions should I take when dealing with DC sources on AC circuits?

Always make sure to use the appropriate conversion devices and follow the manufacturer's instructions. It is also important to properly ground the circuit to prevent electric shocks.

5. How do I calculate the voltage and current of a DC source on an AC circuit?

The voltage and current of a DC source on an AC circuit can be calculated using Ohm's law (V=IR) and the appropriate conversion formulas for AC and DC circuits. It is important to take into account the frequency and phase difference between the AC and DC sources.

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