A high-quality rectifier-based on Sheppard-Taylor converter operating in discontinuous capacitor voltage mode

This paper presents a single-phase soft-switched high power factor (PF) Sheppard-Taylor rectifier suitable for applications requiring low-voltage and high-current output. The proposed rectifier is designed to operate at discontinuous capacitor voltage mode. The Sheppard-Taylor converter in this mode of operation provides zero-voltage. turnoff switching, as well as natural input PF correction over a wide range of input voltage, which makes the converter suitable for universal input applications. Due to its simplified control circuitry and reduced switch current stress, this converter presents better efficiency and higher reliability. In addition, the presented converter features continuous input-output currents, which result in low electromagnetic interference emission. Principle of operation, theoretical analysis, and experimental results from a laboratory prototype rated at 45 W/ 10 Vdc output voltage are presented. The measured efficiency and total harmonic distortion of the input line current were 85% and 3.2%, respectively. The input current harmonies meet the EN61000-3-2 Class D requirements.