Diodes in the inverter

Minoru Yubuchi_21921
Minoru Yubuchi_21921 Altair Community Member
edited November 2022 in Community Q&A

Let me ask a question about the inverter model included in the ElectricDrive extension library.

In the inverter model six diodes are included as seen below.image

Are they necessary in this model? I think that this kind of diodes is necessary in the case semi-conductors are used for switches. Is this correct?

Regards,

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Answers

  • Minoru Yubuchi_21921
    Minoru Yubuchi_21921 Altair Community Member
    edited November 2022

    Sorry, I should say "this kind of diodes is necessary in the case that any inductor is connected to the inverter as a load". 

  • Kazunari Moriya
    Kazunari Moriya Altair Community Member
    edited November 2022

    Hello, Yubuchi-san,

    I think you are right, and this inverter model is described for general purpose. The diodes are necessary when the switches connected in parallel with the diodes mean IGBTs. The reason is that IGBTs can't take reverse current. 

    If the switches of upper side and lower side in same phase never be OFF state at the same time, the diodes are not necessary (including dead time).

     

    best regards

  • Minoru Yubuchi_21921
    Minoru Yubuchi_21921 Altair Community Member
    edited November 2022

    Thank you so much for the advice!

    Minoru Yubuchi

  • Pascal Denoyelle_21681
    Pascal Denoyelle_21681
    Altair Employee
    edited November 2022

    Hello Minoru,

    I add that in the case of power MOSFETs (not IGBTs), the diode between the source and the drain of the MOSFET exist by construction, due to the specific manufacturing of power MOSFETs that is different from MOSFET used in digital integrated circuits. This diode is included in the SPICE model of power MOSFETs provided by manufacturers.

    Its presence is useful in some cases as a freewheeling diode.

    Best regards

    Pascal Denoyelle

     

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