Line Power Extension for Capacitor Size Reduction in AC-DC Converters

摘要

A power converter circuit includes a rectifier circuit having first and second input terminals that receive an AC input voltage and first and second output terminals that output a DC bus voltage, and a series circuit comprising a switch connected in series with an input capacitor connected across the first and second output terminals. A controller controls the switch so that the switch is on at least during a period when a magnitude of the AC input voltage is less than a selected DC bus voltage, and the switch is off during a period when the magnitude of the AC input voltage is greater than the selected DC bus voltage and less than a peak value of the AC input voltage. Power adapters incorporating these features benefit from low component count, reduced component current stress, reduced size and weight, and low cost, making then suitable for a range of portable devices such as laptop computers and cellphones.