A high frequency power factor correction converter with soft switching

Abstract

Power factor correction (PFC) converters are typically operated at low frequency to mitigate switching losses and to simplify control; this in turn requires large passive components. Soft switching techniques could permit higher frequency operation, but most soft-switched converters do not maintain high performance across the wide voltage and power ranges required for PFC applications. Here we present a PFC converter which enables high frequency operation by maintaining soft switching and by using a control scheme which requires no current sensing. These advantages are verified with a prototype which achieves power factors above 0.996 (THD < 10%) while maintaining ZVS across voltage and power for efficiencies ∼ 97 %. By using increased switching frequency (∼ 10x over conventional designs), this converter can take advantage of greatly reduced passive component values for power conversion and EMI filtering.