This is a pretty straightforward bit of l circuitry for driving a Gate Drive Transformer (GDT).
Though increasingly uncommon, (as isolated driver ic's have become ubiquitous in the last decade) a we designed GDT can be extremely versitile and functional.
The intrinsic galvanic isolation allows for a voltage to be referenced to anywhere one selects. And even if a mosfet is sitting across 1000 volts - the signal from the transformer can simply "float" on top of that voltage difference, allowing a high-side fet to be switched, with a simple +/- 20 volt signal. Likewise, some circuits will see the emitter voltage not be tied to ground. In this instance the Gate to Emitter voltage may become significantly lower, resulting in partial-off/massive heating.
Because the GDT's voltage is isolated, it ignores these effects entirely.
