Shoot through problem in inverter

Gaber Mohamed Boraey

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Hello

We work on UPS repair, different capacities and different design

The spare parts we used to get from supplier and was change mosfets and IGBT with same number

For ex: if we get machine for repair with shorted igbt in inverter stage, the igbt number is FGL40n120AND, we change with sane number from spare parts stock
These days our stock us empty, " waiting for next shipment", and the igbt we don't have in local market with same number, and machines need to be repaired, so the only choice we have is to buy replacement " IGBT cross reference"
Sometimes we only find replacement based on voltage and current, rds on for mosfet and Vce"sat" for igbt, but not care about other parameters which is related to timing switch such as tr, tf, tdon, tdoff, etc
The inverter is T-inverter, the gate drivers are isolated using Tlp350
Is there a way to calculate the igbt timing so I know that won't be a shoot through occur when operating?
Or in other Words, how possible that the shoot through problem happen when choosing replacement or cross reference parts for igbt in inverter?, as I believe that the original igbt's working together safely with out shoot through, and that the designer adjusted the timing, so if this timing change will be shoot through problem?, or the machine will have protection for this?
How you think?, better not try replacements?
 

Once you have selected an "equivalent" part number based on Current/Voltages/Rds etc the next main thing/parameter to look for is the "Total gate Charge (Qg)" that will decide whether the given gate driver circuit will be able to drive the Mosfets/IGBTs comfortable fast enough and this in fact will avoid the "shoot through" problem you are concerned with .
 

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