Digital Interleaving Control for Two-Phase TCM GaN Totem-Pole PFC to Reduce Current Distortion

This paper presents a digital interleaving control method for GaN devices-based two-phase interleaved totem-pole power factor correction (PFC) rectifier working in Triangular Current Mode (TCM). Nowadays, digital signal processor (DSP) is widely implemented in converter design. A digital controlled system would induce time delay caused by sample and hold function of pulse width modulator (PWM). In this converter, the influence of this time delay is analyzed. The time delay will lead to PWM duty ratio update of two phases not synchronized, since there exists a phase shift between two phases. This phenomenon would not only cause inductor current distortion but also make converter lose ZVS operation. Using the proposed digital control method, the effect caused by time delay is compensated. Experimental result also shows that the proposed control reduces the zero-crossing current distortion significantly.