IGBT Selection for Full-Bridge DC-DC Converter Application

Hello!

I am building a Full-Bridge DC-DC Converter with the following specifications.
Vin: 48V DC
Vout: 400 V DC
Pout: 1500 W

After considering the transformer efficiency of 80%,
Pin = 1500/0.8 = 1875 W

This makes Iin = 1875 W/ 48 V
=39 Amps

I am a bit confused while selecting the package of the input power devices, because I haven't dealt with this degree of current in my earlier projects.

My first thought was to construct the full bridge using 2 half bridge IGBT modules of 600V / 75A (Powerex CM75DU-12F) and the DC input contacts between the 2 modules would be made via 1mm thick copper bars.

Secondly, I thought of using 2 x IKW75N60T paralleled replacing each switch position on the full-bridge, i.e. 8 IGBTs used in all. All these IGBTs would be mounted on a PCB and the DC supply would be given via thick traces + metal interconnects on the PCB.

The converter is expected to run for minimum 5 hours daily. What would be a more feasible solution for such a long term usage? I personally would want to go for the first configuration.

Also is there any better mounting procedure that would be useful in this application? Thanks!

Just a general thought. Using IGBTs for the 48V node is a bad idea due to their large saturation voltage of 1.5 to 2 volt, which already reduces the overall efficiency by several percent. MOSFETs are the right choice. I also think that you're overestimating transformer losses.

I also forgot to mention that I would be switching the converter at 25 kHz. What efficiency should I consider while designing the transformer?

But even if I consider a MOSFET with a 0.1 Ohm Rds(on), isn't there going to drop around 4 V across each MOSFET @ 40 A?
Considering IXYS's XFH60N50P3 and if I'd run 2 parallel at a time, the drop may reduce to half. But wouldn't it be equivalent to that of the IGBT?

A MOSFET designed for the intended current has Rdson in the milliohm range...

Yes, I will select the MOSFET with a low Rds(on).

What about the transformer efficiency? What should I consider while designing the transformer?

Don't saturate it, beware how leakage L robs you of duty cycle, Beware of core loss,

I'm currently referring Switching Power Supply Design by Abraham Pressman. Any good literature that I could refer along with that?

ray ridley articles as attached