Self-driven AC-DC synchronous rectifier for power applications: A direct energy-efficient replacement for traditional diode rectifier

Synchronous rectification has previously been adopted in switched mode circuits for reducing the conduction losses particularly in low-voltage and high-current applications. This paper presents a generalized ¿self-driven¿ AC-DC synchronous rectification technique that can be used to develop 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 multi-phase systems. Experiments based on 1 kW 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 V and 220 V AC mains operations. This patent-pending circuit can be regarded as a direct replacement of general-purpose diode rectifier. Due to the reduction of power loss, further reduction in the size and cost of the heatsink or thermal management for the power circuit becomes possible.