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This paper presents a new single-stage power factor correction AC/DC converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant DC/DC converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the DC-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant DC-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90-265 Vrms).