Equivalent Power mosfet in HF tube welding machine

[mrcevall]

Hi everyone,

I'm new in this forum, my english is a bit bad but I'll try to explain my problem.

I dont have much experience in power electronics and
I have this mosfet: http://ixapps.ixys.com/Datasheet/DS99027B(IXFN38N100Q2).pdf ,

The thing is, this mosfet is obsolete right know and I have problems getting replacements, so I need a easy to find equivalent mosfet,

Mosfet came originally in a HF tube welding machine: some specs

First stage, 3 phase six pulse rectifier 380Vac
Final stage, 1 phase inverter, Output 500Vrms, switching frecuency 400kHz max.
The inverter stage have 6 blocks with mosfets-diodes connected back to back (see attached photo) they work in two stages wih two diferent firing pulses (see attached photo). Each block have 16 mosfets-diodes in parallel

Parallel diode is http://www.mouser.com/ds/2/205/96509-67416.pdf

This are the best matches I could find:
http://ixapps.ixys.com/datasheet/ds100306(ixfn44n100q3).pdf
http://www.mouser.com/ds/2/205/ixys_98520-342341.pdf

I'm fighting with switching times and Id / Vds characteristics, I cant find equivalent mosfet with good ones as original.

I'm studying this problem but I want to hear opinions from more experienced people .

Thanks for your help


block


firing pulses



output voltage

 

[(*steve*)]

What about these?

https://www.digikey.com/product-detail/en/microsemi-corporation/APT41F100J/APT41F100J-ND/1494596

https://www.digikey.com/product-detail/en/ixys/IXFN38N100P/IXFN38N100P-ND/1995013

https://www.digikey.com/product-detail/en/ixys/IXFN44N100Q3/IXFN44N100Q3-ND/2773901

https://www.digikey.com/product-detail/en/microsemi-corporation/APT45M100J/APT45M100J-ND/1494607

https://www.digikey.com/product-detail/en/ixys/IXFN38N100Q2/IXFN38N100Q2-ND/1651990

I haven't checked all the specs, but they seem to fit many of the basic requirements

Edit: I think they are the ones you've been looking at.

 

[mrcevall]

What about these?

https://www.digikey.com/product-detail/en/microsemi-corporation/APT41F100J/APT41F100J-ND/1494596

https://www.digikey.com/product-detail/en/ixys/IXFN38N100P/IXFN38N100P-ND/1995013

https://www.digikey.com/product-detail/en/ixys/IXFN44N100Q3/IXFN44N100Q3-ND/2773901

https://www.digikey.com/product-detail/en/microsemi-corporation/APT45M100J/APT45M100J-ND/1494607

https://www.digikey.com/product-detail/en/ixys/IXFN38N100Q2/IXFN38N100Q2-ND/1651990

I haven't checked all the specs, but they seem to fit many of the basic requirements

Edit: I think they are the ones you've been looking at.

Yes I check most of them, the IXFN44N100Q3 is the most similar mosfet.

What do you think about these parameters:

Vgs(th) original is 3 - 5.5V and most of the similars are 3.5 - 6.0 or 6.5 V. I read Vgs values are critical when mosfets are connected in parallel because one can turn on and turn off faster/slower.
Others parameters that differ in about 50-80% are Qg, switching times tdon, tdoff, tr and tf, and capacitances Ci, Co, Cr.
I think Parasit diode is not important because is blocked with a Fast Recovery diode (DSEI 2x 61)