A Novel Boost PFC Converter with Inherent Boundary Conduction Mode Operation

Generally, for existing boost-type PFC converters operating in boundary conduction mode (BCM), a zero-crossing detection (ZCD) circuit is always required to capture the instant of zero-crossing of the inductor current, which inevitably makes the control circuits more sophisticated. Furthermore, they all suffer from wide switching frequency ranges, particularly under high-voltage inputs. Different from existing BCM PFC converters, this article proposes a novel boost-type PFC converter with inherent BCM operation, while two PFM-derived control methods are developed to regulate the input current shape and realize PFC function. Since the BCM state is achieved naturally, the proposed topology eliminates the need for a ZCD circuit. During a line period, it exhibits significantly reduced frequency variations than conventional BCM PFC converters. Furthermore, the suggested converter attains ZVS operation across a wider range of AC inputs. Experimentation outcomes from a 120W prototype with 400V output voltage affirmed the effectiveness and the claimed features of the suggested converter.