Simulation – PSIM Simulation of Buck Converter

IGBTs have high voltage drop and are not suitable for low voltage switching. They only exist because reliable high current high voltage MOSFETs are hard to make.

You should use high current MOSFETs rated at 30~40V. Maximum current is often package limited, but several FETs can be wired in parallel to increase current handling. For example the IRFP7430PbF is rated at 404A, but package limited to 195A. Rdson is 1.3 milliohms, so two in parallel should drop 0.13V at 200A (= 13W per FET). In comparison an IGBT module could drop 2V or higher, resulting in 400+ Watts of heat to get rid of!

The advantage of a module is less wiring and simpler installation. One disadvantage is that it's toast if even one transistor dies. Also an IGBT module may be much more expensive than a few discrete FETs.

The TC4427 by itself can not generate a gate drive voltage greater than its own supply voltage. That follows from the functional block diagram on p.2 of the datasheet.

It would make the question clearer, if you add the gate driver to the schematic on the O.P. and show its supply rails.

For the time being, I'll assume that the TC4427 is powered from the same +17.4V that goes to the input of the buck. In that case, the source of the N-channel MOSFET will not be any higher than 17.4 V - V_th.

Typically, buck converters have a bootstrap gate driver¹ and an N-channel MOSFET, or a P-channel MOSFET.

¹ Bootstrap gate driver (see also here) is not the only option for N-challel MOSFETS. Other options: gate driver transformer, additional supply rail for gate driving with elevated voltage.