1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Transfer function needed -- help please

  1. Mar 18, 2016 #1
    Hi guys, I'm new to this engineering problem solving and I just wanted to ask for your help getting a transfer function of the input voltage Uin(t) and the output voltage Uout(t).


    1. Uin(t) = U_R(t) + u_out(t)
    2. i(t) = i_L(t) + i_C(t)
    3. u_r(t) = R_i(t)
    4. u_out(t) = L d_iL / dt
    5. i_C = C d_uout / dt


    3. The attempt:

    Dv_c(t) / dt = 1/C i_c(t) = [ 1/C (i(t) - i_out(t) ] = - 1/RC_vc(t) + 1/C i (t)
    Di(t) / dt = 1/L v_L(t) = 1/L...
     
    Last edited by a moderator: Mar 18, 2016
  2. jcsd
  3. Mar 18, 2016 #2

    berkeman

    User Avatar

    Staff: Mentor

    Welcome to the PF.

    Is there a circuit diagram that you could UPLOAD for us to look at. For me, it's hard to visualize the problem. Thanks :smile:
     
  4. Mar 18, 2016 #3
    Sure, attached is the circuit. :) http://postimg.org/image/7a4mj5c6b/

    << Link removed by Mentor >>
     
  5. Mar 18, 2016 #4

    berkeman

    User Avatar

    Staff: Mentor

    Could you instead please use the UPLOAD button at the lower right to upload your image to the PF? The website you have linked to has some questionable advertisements on it. Thanks. :smile:
     
  6. Mar 18, 2016 #5
    Sorry for that, here is the picture of the system.
     

    Attached Files:

  7. Mar 18, 2016 #6

    berkeman

    User Avatar

    Staff: Mentor

    No worries. Thanks for the diagram.

    I'm not able to follow what you are doing with your equations, but it seems like you are working with each component individually (I could be wrong). Instead, I would write the one KCL equation for the node between the input resistor and the RLC load. Write that differential equation and solve for the currents and voltages. Can you give that approach a try? :smile:
     
  8. Mar 18, 2016 #7
    I will try, but it's not as easy for me. anyways, thanks for advice.
     
  9. Mar 19, 2016 #8

    LvW

    User Avatar

    Suiluas - are you aware that a system`s "transfer function" requires to find voltage-current relations in the frequency domain?
    You have started in the time domain - this is not necessary and requires application of the Laplace transformation. Instead, you can start directly with impedances in the frequency domain
    Examples: inductice impedance: ZL=jωL, capcitive impedance: ZC=1/jωC.
     
    Last edited: Mar 19, 2016
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Transfer function needed -- help please
  1. Transfer function (Replies: 2)

  2. Transfer Functions (Replies: 1)

  3. Transfer Function (Replies: 3)

  4. Transfer Function (Replies: 8)

  5. Transfer Function (Replies: 20)

Loading...