Diodes in the inverter

Minoru Yubuchi_21921

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.

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,

Minoru Yubuchi_21921

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

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

Thank you so much for the advice!

Minoru Yubuchi

Pascal Denoyelle_21681

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