SPICE's Fourier transform

Discussion in 'Homework Help' started by interesting_dude, Dec 1, 2013.

  1. interesting_dude

    Thread Starter New Member

    Jul 28, 2013
    20
    0
    Hello everybody! :D
    What am I doing wrong in attempts to simulate an example circuits with FFT? Why do my results not correspond to these ones in the book? With earlier simulations everything matched excellently!
    Huge thanks for any decent explanations!

    [​IMG]






    ******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
    **** FULLWAVE BRIDGE RECTIFIER
    **** INPUT LISTING TEMPERATURE = 27.000 DEG C
    ***********************************************************************


    V1 1 0 SIN(0 15 60 0 0)
    RLOAD 2 3 10K
    D1 1 2 MOD1
    D2 0 2 MOD1
    D3 3 1 MOD1
    D4 3 0 MOD1
    .MODEL MOD1 D
    .TRAN .5M 17M
    .PLOT TRAN V(1,0) V(2,3)
    .FOUR 60 V(2,3)
    .END




    ******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
    **** FULLWAVE BRIDGE RECTIFIER
    **** DIODE MODEL PARAMETERS TEMPERATURE = 27.000 DEG C
    ***********************************************************************


    MOD1
    IS 1.00E-14




    ******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
    **** FULLWAVE BRIDGE RECTIFIER
    **** INITIAL TRANSIENT SOLUTION TEMPERATURE = 27.000 DEG C
    ***********************************************************************

    NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE

    ( 1) 0.0000 ( 2) 0.0000 ( 3) 0.0000


    VOLTAGE SOURCE CURRENTS

    NAME CURRENT

    V1 2.789E-40

    TOTAL POWER DISSIPATION: 0.00E+00 WATTS




    ******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
    **** FULLWAVE BRIDGE RECTIFIER
    **** OPERATING POINT INFORMATION TEMPERATURE = 27.000 DEG C
    ***********************************************************************


    **** DIODES

    D1 D2 D3 D4
    MODEL MOD1 MOD1 MOD1 MOD1
    ID 4.35E-21 4.35E-21 4.35E-21 4.35E-21
    VD 0.000 0.000 0.000 0.000




    ******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
    **** FULLWAVE BRIDGE RECTIFIER
    **** TRANSIENT ANALYSIS TEMPERATURE = 27.000 DEG C
    ***********************************************************************


    LEGEND:

    *: V(1)
    +: V(2,3)
    TIME V(1)
    *)------------- -2.000E+01 -1.000E+01 0.000E+00 1.000E+01 2.000E+01
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    +)------------- 0.000E+00 5.000E+00 1.000E+01 1.500E+01 2.000E+01
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    0.000E+00 0.000E+00 + . * . .
    5.000E-04 2.807E+00 . + . . * . .
    1.000E-03 5.512E+00 . + . . * . .
    1.500E-03 8.029E+00 . . + . * . .
    2.000E-03 1.025E+01 . . + . * .
    2.500E-03 1.213E+01 . . . + . * .
    3.000E-03 1.354E+01 . . . + . * .
    3.500E-03 1.453E+01 . . . + . * .
    4.000E-03 1.494E+01 . . . + . * .
    4.500E-03 1.488E+01 . . . + . * .
    5.000E-03 1.424E+01 . . . + . * .
    5.500E-03 1.313E+01 . . . + . * .
    6.000E-03 1.154E+01 . . .+ . * .
    6.500E-03 9.550E+00 . . + . *. .
    7.000E-03 7.214E+00 . . + . * . .
    7.500E-03 4.628E+00 . + . . * . .
    8.000E-03 1.878E+00 . + . . * . .
    8.500E-03 -9.415E-01 + . *. . .
    9.000E-03 -3.723E+00 . + . * . . .
    9.500E-03 -6.378E+00 . + * . . .
    1.000E-02 -8.803E+00 . . * + . . .
    1.050E-02 -1.092E+01 . *. +. . .
    1.100E-02 -1.265E+01 . * . . + . .
    1.150E-02 -1.392E+01 . * . . + . .
    1.200E-02 -1.472E+01 . * . . + . .
    1.250E-02 -1.497E+01 . * . . + . .
    1.300E-02 -1.473E+01 . * . . + . .
    1.350E-02 -1.392E+01 . * . . + . .
    1.400E-02 -1.266E+01 . * . . + . .
    1.450E-02 -1.091E+01 . *. +. . .
    1.500E-02 -8.814E+00 . . * + . . .
    1.550E-02 -6.374E+00 . + * . . .
    1.600E-02 -3.727E+00 . + . * . . .
    1.650E-02 -9.404E-01 .+ . *. . .
    1.700E-02 1.880E+00 . + . . * . .
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - -






    ******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
    **** FULLWAVE BRIDGE RECTIFIER
    **** FOURIER ANALYSIS TEMPERATURE = 27.000 DEG C
    ***********************************************************************

    FOURIER COMPONENTS OF TRANSIENT RESPONSE V(2,3)

    DC COMPONENT = 8.294E+00

    HARMONIC FREQUENCY FOURIER NORMALIZED PHASE NORMALIZED
    NO (HZ) COMPONENT COMPONENT (DEG) PHASE (DEG)

    1 6.000E+01 4.134E-03 1.000000 109.967 0.000
    2 1.200E+02 6.213E+00 1503.001102 -75.620 -185.588
    3 1.800E+02 4.711E-03 1.139608 137.077 27.109
    4 2.400E+02 1.159E+00 280.425460 -61.412 -171.380
    5 3.000E+02 5.575E-03 1.348548 158.142 48.174
    6 3.600E+02 4.459E-01 107.855080 -47.527 -157.494
    7 4.200E+02 7.568E-03 1.830629 -168.855 -278.822
    8 4.800E+02 2.147E-01 51.928957 -34.592 -144.560
    9 5.400E+02 7.739E-03 1.872056 -165.930 -275.898

    TOTAL HARMONIC DISTORTION = ************ PERCENT

    JOB CONCLUDED

    TOTAL JOB TIME 0.00
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    I havent used 2G6 in forty years. Your TRAN statement looks suspicous. You need to run the sim for several whole cycles of the stimulus. The period of 60Hz is 16.667ms. Try running your sim for six cycles (0.1s)
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Heres what (free) LTSpice shows: (I made no effort to match your node numbers)
     
  4. interesting_dude

    Thread Starter New Member

    Jul 28, 2013
    20
    0
    Uh...
    I've changed ".TRAN .5M 17M" into ".TRAN .5M .1" — result didn't match completely too. Seems like LTSpice showed "almost" correct results too!
    But I think that I've really understood the general idea of that curious chapter in e-book.
    Thanks for attention! :)
     
  5. ninjaman

    Member

    May 18, 2013
    306
    1
    what type of circuit is that in the ltspice program please?

    I have to show the fundamental, third and fifth harmonics and the fifth has to have a lag of 70 degrees. I wanted to know how I could do this and that circuit may be of use. whats it called so I can look it up. it looks like a rectifier.

    thanks
    simon
     
  6. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    It is a full-wave diode bridge rectifier, drawn differently than you are used to seeing it.

    Here a simple way to sythesize waveforms...

    The second diagram shows how to set up the voltage sources...
     
  7. interesting_dude

    Thread Starter New Member

    Jul 28, 2013
    20
    0
    @ninjaman
    http://www.allaboutcircuits.com/vol_2/chpt_7/3.html

    I think I found mistake. That netlist should be such:


    fullwave bridge rectifier
    v1 1 0 sin(0 15 60 0 0)
    rload 2 3 10k
    d1 1 2 mod1
    d2 0 2 mod1
    d3 3 1 mod1
    d4 3 0 mod1
    .model mod1 d
    .tran .5m 50m
    .plot tran v(1,0) v(2,3)
    .four 60 v(2,3)
    .end
     
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