Optimized Hybrid PWM Scheme for Mitigating Zero-crossing Distortion in Totem-Pole Bridgeless PFC

摘要

Totem-pole bridgeless power factor corrector (PFC) has been widely used in high-power applications for its low component count and high energy efficiency. Its active bridge is configured to operate the power circuit as a synchronous boost converter over the line cycles, with two switching devices operated at the line frequency and the other two operated at high frequency. However, typical pulsewidth modulation (PWM) scheme causes unavoidable input current distortion near the zero-crossings. This paper will present an optimized hybrid (h)-PWM scheme near the zero-crossings, where the modulation scheme for generating the output voltage of the active bridge is dynamically varied, for mitigating such current distortion. Modeling, design, and analysis will be given. A 1kW, 85-265 Vac/400Vdc, SiC-based prototype has been built and evaluated. The results reveal that the proposed method can effectively reduce the total harmonic distortion (THD) of the input current.