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Spark gap switch and 2N6798 in PSPICE

  1. May 11, 2016 #1
    Error is like " no PSPICE template for 2N6798 , spark gap switch
    how to find the .ilb of spark gap switch and 2N6798?
    thank for your help.
     
  2. jcsd
  3. May 12, 2016 #2

    Baluncore

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  4. May 12, 2016 #3

    CWatters

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  5. May 12, 2016 #4

    Baluncore

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    There has also been a long running discussion of spark gap modelling on the LTspice group.

    Using spice to model sub-sections individually can be very quick and useful, that is what spice was designed to do. The problem is that users get carried away and try to integrate the entire project into one simulation. It is not surprising that a simulation will be very slow when 10 seconds of project time is simulated with a time step of 10nsec simply because there was a digital component present in a small part of the simulation.

    An accurate spark gap simulation is a problem because it has nanosecond breakdown followed by a one second recovery. The triggering of spark gap breakdown, as a load, can be done with a zener diode and SCR structure. The result of the spark gap breakdown, as a source, can be simulated by a voltage step. The problem comes when the two are coupled into the same model. The simulation needs to be split into two independent modules, one on each side of the spark gap.

    Before modelling spark gaps see; https://en.wikipedia.org/wiki/Paschen's_law
     
  6. May 15, 2016 #5
    Thank your reply.
    I tried ,but the new error like this.
    I am not sure what the mistake i made
    Can you give me suggestions about this?
    thank you very much.
    upload_2016-5-16_10-36-21.png
    upload_2016-5-16_10-35-8.png
     
  7. May 16, 2016 #6

    Baluncore

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    Do not do all at the start. You should use a simple circuit at the start of modelling.
    Why do you specify and use IRFF230 ?
    I will take me some time to make a .MODEL IRFF230 VDMOS( . . . )
    Use another model until IRFF230 is available. I use IRFH5300.

    The IRFF230 is in a TO-205AF (TO-39) package. It has low power.
    A Mosfet is low power only when zero current with voltage, or zero voltage with current.
    Your mosfet circuit is unusual. You must use pulse control of the gate. I have changed the circuit.
    I have LTspice. See the attached circuit.
    When M1 turns on, R1 limits the current through the transformer primary to Ip = V1 / R1 amp.
    When M1 turns off, D1 conducts current through L1 to prevent voltage spike.

    I do not understand your switch connections.
    Circ1.png
     
  8. May 29, 2016 #7
    thanks for your apply
    擷取2.PNG
    It is circuit from paper
    I want to simulate this circuit with pspice.
    This switch is spark gap switch.
    But i do not know how to do
    i am not a Electrical Engineering student ,so i am very confused about that
     
  9. May 29, 2016 #8

    Baluncore

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    What is Discrete EFI ? Is it for high speed flash photography ?

    I can model the circuit for you. But I need more information.
    Please post a link or attach the paper with the circuit diagram.
    The circuit cannot be modelled until design is finished.

    High voltage to trigger spark gap. Comes from a pulse transformer with high turns ratio. 1 : 50 ?
    Design of transformer. Requires specification of spark gap device part number and data sheet.
    Have you selected a three terminal spark gap component ?
    What is part number for three terminal spark gap ?

    Here are some spark gap examples and data.
    http://www.highenergydevices.com/products/three-electrode /
    Start with application note download; AN-TG-10 Use of Triggered Spark Gaps.
    AN-TG-20 TX Miniature Triggered Spark Gaps Description and Use.
    Also; Datasheets; TX Series Datasheet. Selection Guide; Three-Electrode Triggered Spark Gaps

    AE = adjacent electrode? Adjacent to trigger = main electrode.
    OE = opposite electrode? Opposite to trigger.

    Spice is confusing for beginners.
    1M = 1m = 1e-3 = 10-3
    1Meg = 1meg = 1e6 = 106
    1uF = 1f = 1 femto = 1e-15 = 10-15
     
    Last edited: May 30, 2016
  10. May 30, 2016 #9
    The circuit at page 3 of paper.
    I think Discrete EFI can replace by a 0.1 Ω resistance
    thank you.
     

    Attached Files:

    Last edited: May 30, 2016
  11. May 30, 2016 #10

    Baluncore

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    The MT4206 pulse transformer was used for original simulation.
    It has only 1:1:1 turns ratio. It cannot be used for real circuit.
    The trigger voltage must be HV, maybe 1kV. So turns ratio must be 25V : 1kV = 1 : 40.

    Spice transformer ratio is set by inductance.
    Inductance is proportional to n^2. So 1 : 40 turns ratio is 1.0uH : 1.6mH.

    Attached is simple spice model of circuit and switch.
    It shows same response as Fig 7 of Baginski Et Al. Micromachined Planar Triggered Spark Gap Switch.
     

    Attached Files:

    • SG-4.png
      SG-4.png
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  12. May 30, 2016 #11
    upload_2016-5-31_4-0-50.png
    upload_2016-5-31_4-1-33.png
    Thanks for your reply very much.
    I tried,but my result is wrong.
    I am not sure what the mistake i made
    Can you give me suggestions about this?
    thanks for your help.
    (I do not have .ilb of IRFH5300.)
     
  13. May 30, 2016 #12

    Baluncore

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    DO NOT use “F” or “f” for capacitance with SPICE. It is sometimes seen as 1e-15 = 1 femto = 10-15.

    Change C1 from 40nF to 40u
    Change C2 from 0.17nf to 0.17u
    Change L1 from 1nH to 1u
    Change L2 from 1600nH to 1600u
    Change R6 from 5M to 5MEG

    What is your transformer coupling? Ktran L1 L2 1.000
    What is your switch specification? .MODEL Sbreak SW(RON= ROFF= VT=500 )

    Use any MOSFET that works in model. You may need higher voltage from V3.
    The IRFF230 is old. There are now faster components for that application.
     
  14. May 31, 2016 #13
    Because I follow your design steps, however, the result seems weird.

    So Could you please send me your LTSPICE project file so that I can figure out the difference between yours and mine.

    Thanks for your explain in detail.
     
  15. May 31, 2016 #14

    Baluncore

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    Attached is file SG-4.asc.txt , remove the .txt to make SG-4.asc which is LTspice file.

    Attachment to post #10, SG-4.png
    Blue text is comment. Black text is Spice command or parameter values.

    I do not use Pspice because it is limited or expensive.
    LTspice is free. LTspice is not limited. There is a big LTspice users group.
     

    Attached Files:

  16. Jun 1, 2016 #15

    Baluncore

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    The design of the EFI trigger pulse transformer is never openly discussed.
    Patents show “pulse transformers” and “piezoelectric transformers” being applied to EFI.
    Attached is the Perkin Elmer documentation for spark gaps and trigger transformers.

    Chinese document; Design of High-voltage Transformer in Small-scale Pulsed Power Experimental Device.
    http://en.cnki.com.cn/Article_en/CJFDTotal-CSJS201201009.htm

    This Canadian article has Pspice models for the spark gap and EFI.
    http://cradpdf.drdc-rddc.gc.ca/PDFS/zba33/p498223.pdf

    The JAN TX 2N6798 is referenced in US documents because it is a military specified device that works in this application.
    There are now better MOSFETs available without mil-spec. They are faster and have lower resistance.
     

    Attached Files:

  17. Jun 2, 2016 #16
    Thank for information of spark gap and EFI you provide

    I think I need a little time to read this information.

    Thanks so much
     
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