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Archit1
Level 1
Level 1
10 sign-ins 5 questions asked First reply posted

Why do some datasheets of IGBT mention Soft Switching as Application? Can't it be used for hard switching? If no why not?
Example datasheet :https://rocelec.widen.net/view/pdf/dhf2vvldbf/INFNS12974-1.pdf?t.download=true&u=5oefqw

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1 Solution
cynic_bandera
Employee
Employee
5 questions asked First question asked 100 sign-ins

For the ZCS application, it´s very important to have not only a current capable diode but also important to have it fast. Switch-off losses of the diode are very important, it´s usually specified in the datasheet. 

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cynic_bandera
Employee
Employee
5 questions asked First question asked 100 sign-ins

The soft-switching application usually needs a high current (usually the same current rate as the IGBT) integrated diode. But for hard-switching applications, it´s not needed (it can be used much lower current rate diode).  One example, there are two very old IGBTs IRGP50B60PD1 for hard switching and IRGP50B60PD for soft switching. The difference is only the diode size (and cost).  It means "Soft-switching" targeted products also can be used for hard-switching but not vice versa.  

Archit1
Level 1
Level 1
10 sign-ins 5 questions asked First reply posted

So you are saying that if the parallel (FW)diode current rating is almost same as the IGBT, it can be used for Soft Switching. Both the IGBTs you mentioned  has written ZVS in their datasheets. 
Also, for the datasheet I have attached it says ZCS. can you please explain me why ZCS is written? I was under the impression that if soft-switching is written on a datasheet that means the switching energies are so high that one can not use them without soft switching.. 

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cynic_bandera
Employee
Employee
5 questions asked First question asked 100 sign-ins

For the ZCS application, it´s very important to have not only a current capable diode but also important to have it fast. Switch-off losses of the diode are very important, it´s usually specified in the datasheet.