This paper investigates zero-voltage-switching (ZVS) control of a single-phase GaN-based critical-conduction-mode (CRM) totem-pole power factor correction (TPFC) in fully analog domain. Critical mode operation is used by the totem-pole PFC rectifier in order to achieve both high frequency operation and hence smaller magnetics while also achieving high efficiency due to soft switching. A digitally controlled CRM TPFC faces challenges due to current sensing delays and zero-current detection (ZCD) sensitivity to high di/dt noise, which complicates ZVS control. For designing a fully analog controlled CRM TPFC, a full-line-cycle ZVS strategy is derived in this work comprising variable extended on-time and dead time followed by its implementation using analog circuits. Furthermore, an optimum dead time over the full line cycle is obtained using quantitative analysis to achieve minimum average turn-on loss. Finally, a 2.5kW GaN-based 120Vac/240Vac to 400V dc totem-pole PFC is demonstrated with 98.12% peak efficiency operating between 70 kHz (near peak) and 460 kHz (near peak) switching frequency.
