Power Rectifier

Hello to all.
BYV32-200 is a power rectifier that has 2 diodes in its package.
I would like to use both diodes in a buck converter. The power of my buck is 400 watts and input voltage is about 70v and the minimum voltage of output is 30 volts. Actually I want to control speed of a DC motor.
Can I parallel both diodes to each other and use in my buck converter.
Very thank you.

Your description of use isn't clear, a schematic would help immensely.

Paralleling diodes can be done but there are caveats to ensure proper load sharing. That said, it should be fairly easy with two diodes in one package if they are one the same die.

There is no problem putting diodes in parallel, but assume that one diode is going to take all the current. There will be current sharing between the two which gives you extra safety margin, but the power dissipation of the package will be (essentially) the same regardless of whether all the current goes through one diode or is shared equally since the forward voltage won't change much.

Depending on the specifics of your circuit you will probably need a heatsink. 400W at 30V implies 13.3A. If the diode is conducting 50% of the time that is going to be ~5 Watts which will burn up the part.

If you are asking such questions I would be willing to wager that your design skills are not up to designing such a beast. That is a serious Buck converter and I would be supprised if you can get an inductor that would take such a magnetic load, I think it will saturate way too soon.

I know many professional electronic engineeres who would not touch a project like this with a barge pole.

It is feasible and the inductor would not be as gargantuan as Grumpy Mike has suggested. I use one in a 15A buck converter that is only 13.7mm square and is rated for 18A RMS and has an Isat of 35A.

But, if you are looking to control a motor a simple PWM circuit would be a lot easier.