High-efficiency True Bridgeless Totem Pole PFC based on GaN HEMT: Design Challenges and Cost-effective Solution

A true bridgeless Totem-Pole Power-Factor-Correction (TP-PFC) circuit is enabled by a diode-free GaN power HEMT bridge with low reverse-recovery charge. The proposed circuit introduces effective methods to resolve design challenges of current sensing and light load regulation, which can greatly reduce application cost and improve system stability. Experiments have been conducted to verify the proposed high efficiency AC/DC conversion of TP-PFC. Two types of GaN HEMT in TO220 and TO247 packages from Transphorm, Inc. have been successfully used in the proposed TP-PFC in 2 power levels. With 390Vdc output in continuous-current mode, a 1kW TP-PFC reaches 99% peak efficiency at 230V ac high-line input with 50KHz switching frequency, and a 2.4kW TP-PFC reaches 98.8% peak efficiency at high-line input with 100KHz switching frequency.