Buck Converter design help

Hello all! I am getting into the solar hobby and have high hopes of building my own charge controller to handle up to 700W. I have been through this on another forum and most of the responses on there were to go buy a premade one or < 20A circuits, but I am a DIY'er and don't mind spending a little extra time learning as I go along. I just need help being started in the right direction with the right components.

To start with the project, I need to build a Buck Converter that can be driven by a processor that outputs 3.3V and can source / sink 40ma per pin. Since this is much higher voltage and higher amperage than I have ever worked with, I need help selecting the right components. My preferred place I like to order from is DigiKey and I have spent a bunch of time on there recently trying to determine what components I could use.... The more I look at it, the more scared I get!

After days of researching and doing some bench testing with lower amperage (< 10A), I have learned that the turn off time of a Mosfet is key. I dabbled with using an Op-Amp to drive a P-Channel mosfet but ran into problems with frequency and "ringing" on the gate. During my journey of researching, I have learned about IGBT's and they have sparked my interest, but I have never used one and would not know how to properly drive one at the frequency most recommend (20khz to 50khz). I don't mind running at a lower frequency if it gives me room for error (including heat sink sizing).

The Gate Driver IR2101 looks to be promising, but I am not very good at the math side of electronics and am unsure if it can drive an IGBT properly at the current I am looking to run and the frequency. The Ton and Toff seem to be a little slow if my math is correct. 50khz = 50ns?
Product Details : https://www.digikey.com/product-detail/en/IR2101STRPBF/IR2101SPBFCT-ND/827940

Also, this IGBT (APT30GP60BDQ1G) is probably way too much, but it can handle the switching frequency and current.
https://www.digikey.com/product-detail/en/APT30GP60BDQ1G/APT30GP60BDQ1G-ND/1434704

From what I understand, I will also need either a very fast diode for the flyback diode, or I can use an N-Channel mosfet? Does this component also need to be rated at the high amperage as the high side IGBT or Mosfet I select?

Am I looking at the right components or is there a better alternative? I do greatly appreciate any help I get on this!

EagleTalonTim said:

From what I understand, I will also need either a very fast diode for the flyback diode, or I can use an N-Channel mosfet? Does this component also need to be rated at the high amperage as the high side IGBT or Mosfet I select?

Click to expand...

A Schottky (or low-barrier) diode is usually recommended for switching speeds typical in such converters.

When you use a mosfet/transistor instead, it is called synchronous mode and it might be more efficient than a diode. However, if you are charging a battery, there is a risk of leaving it on past the time when coil current has dropped to zero. This allows the battery to discharge through it in reverse direction.

During the experimental stage you might as well make it easy on yourself, and use a diode.

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Secondly, at the power level you are talking about, it might be more effective to make two or more interleaved converters. A benefit will be that you draw continuous current from your PV panel.

Hi buck converter can be design in two ways
1. using dedicated pwm controller IC's
2. Using microcontroller
you can check following link for complete guide on how to desing buck converter using pic microcontroller and mosfet driver IR2110
https://microcontrollerslab.com/buck-converter-using-pic-microcontroller-ir2110/