The paper is showing IGBT switches, they are integrating a bipolar transistor and a MOS driver transistor on a chip. Their field of
application is a few hundred to multiple thousand V and a few ten up to thousand A. Apart from a different input capacitance,
they are driven like MOSFETs.
The paper is focussing on unipolar versus bipolar PWM scheme and not showing any driver details. Actually, the high-side
switches have to be driven by a level translator not shown in the principle schematic. IR2110 boostrap drivers are
an example of integrated drivers suited for MOSFET and small IGBT.
You'll find several dozen threads about H-bridge drivers when searching edaboard.