Using Self-Driven AC–DC Synchronous Rectifier as a Direct Replacement for Traditional Power Diode Rectifier

Synchronous rectification has previously been adopted in switched-mode circuits for reducing the conduction losses particularly in high-frequency, low-voltage, and high-current applications. This paper presents a generalized “self-driven” ac-dc synchronous rectification technique that can be used even at mains frequency to develop an ac-dc synchronous rectifier that behaves like a diode bridge but with much reduced conduction losses and without control integrated circuits. This generalized concept can be extended from single-phase to multiphase systems. Experiments based on 1- and 2-kW single-phase systems have been successfully conducted for capacitive, inductive, and resistive loads. Very significant power loss reduction (over 50%) has been achieved in the rectification stage at both 110- and 220-V ac mains operations. This patent-pending circuit can be regarded as a direct replacement of a general-purpose diode rectifier. Due to the reduction of power loss, further reduction in the size and cost of the heat sink or thermal management for the power circuit becomes possible.