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hugo41
Visitor II
October 15, 2024
Question

Theoretical issue transistor switching loss academic project

  • October 15, 2024
  • 1 reply
  • 1062 views

Hello,

I'm a french student in a 2 years intensive class to prepare engineering school entrance exam and I have to present a scientist project to this exam. I choose to work on transistor conduction and switching loss.

 

My problematic is  " To what extent are switching and conduction losses depending on switching frequency ?"

 

I'm willing to establish a "simple" theoretical model of a transistor able to link power losses to switching frequency.

Moreover I'll do some measure and simulation to compare the results.

 

Currently i decided to assimilate the transistor during the conduction phase to a high value resistor when its Off and to a low value resistor when it's On. This two value will be measure by an experiment.

 

However i struggle to find an accurate model to estimate the power loss during the switching phase.

 

 

Do you have any idea on how to do it ?

Or any document dealing with the subject ?

 

Thanks for your help

Hugo 

 

 

 

 

 

 

 

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    1 reply

    A
    AScha.3
    Super User
    October 15, 2024

    Hi,

    > However i struggle to find an accurate model to estimate the power loss during the switching phase

    Thats to be expected - because ther is no "accurate model" for switching ...what? mosfet, IGBT, SiC-mos..?

    All models are more or less good approximations to the real world device.

    Just because real mosfet or igbt exibit a very complex behavior in switching, changing/altering when  current, voltage, temperature or gate drive is changed. And even different for switching on and off !

     

    But for your question: > To what extent are switching and conduction losses depending on switching frequency ?

    I would say, basically: no changes at all. Just in a certain time intervall , 1 sec or so, you have the ON-time loss ( x time ) and the switching loss (x events/time ).

    On sate loss and switching are not changing by itself, just both will change with rising teperatur of the device.

    So to get it exactlx for a certain device, you have to measure it in real world.

    And adjust your "model quality" to the deviation you want to accept.

     

    About real switching...just ask google and read...like this:

    https://www.infineon.com/dgdl/Infineon%20-%20AN2003-03%20-%20Switching%20behaviour%20and%20optimal%20driving%20of%20IGBT3%20modules.pdf?fileId=db3a304412b407950112b40ee84712c4

     

     

     

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