Engineer needed to verify and correct buck converter and its inductor calculation

Our product has a field coil which is powered via DC voltage and current. In our current design we have a dedicated 3 phase transformer from which we rectify and use capacitors to generate an unregulated bus of maximum 250V and 45A.

At times we are requested to provide an option to reduce this power by 50%. For this, we have given tapping in our transformer and we use contractors to switch between tapings and reduce the power.

In our next design we are merging multiple transformers into one and this bus voltage will increase to 280V. Having or switching between transformer tapping will not be possible. Since the output power needs to dwell between 50% and 90% of the maximum power, we feel having a buck converter is the best option. 100% will be 280V and 50A which is a little beyond than what my field coil can handle.

I am doing the design of this converter and have the following issues:
1. Is buck converter the best option?
2. Is something readily available in the market for this task?
3. My calculation for buck converter with switching frequency at 30kHz shows that I will need around 20uH of inductor and over 500uF of capacitor to make the converter work and keep the voltage ripple below 2Vpp. I need this data to be validated.
4. I have the datasheet of the core, wire gauge chart, and my MATLAB scrip to calculate inductor parameters for which I need the following:
a. I need all the formula and steps validated
b. I am not able to understand what the maximum B of my core will be. I am confused if, due to the 2m air gap, will I have saturation in the core or not.
c. Does it matter if I use a single conductor or multiple conductors?
d. Why is it that my winding losses and all other parameter remain the same when I change my wire diameter and number of strands?
e. I found my winding losses, but I am not able to figure out losses due to hysteresis and eddy current. I need to calculate all my losses for this inductor.

Besides this, I need inputs on any other pitfall that I might run into or anything I should look out for.
About the recuiter
Member since Mar 14, 2020
Ceo Legend Guru
from Nizhny Novgorod Oblast, Russia

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