SR Control With Zero Current Detection Delay Compensation for GaN CRM Totem-Pole PFC Rectifier

An synchronous rectifier (SR) control with zero current detection (ZCD) delay compensation is proposed to reduce the high reverse inductor current and input current distortion caused by the ZCD delay in critical mode totem-pole power factor correction (PFC). The basic idea of the proposed control is to calculate the SR turn- off instant considering the ZCD delay. Accurate operation model in VOT control is analyzed with ZCD delay compensation to realize the proposed control. A prototype of 2 kW GaN CRM totem-pole PFC converter is built to verify the proposed control. The total harmonic distortion (THD) with full load decreases to 3% by mitigating the current distortion caused by the ZCD delay, 1.6% lower than that before compensation. The high reverse inductor current near the zero-crossing of input voltage is avoided since the length of the zero-current platform is shortened by 87.5%. The prototype achieves 99% efficiency at full load (2 kW) and a power density of 120 W/inch ³ .