The University of Hong Kong

Pong Liu

Ngai Kit Poon

Xue Fei Xie

Hay Pong

A synchronous rectifier is disclosed, which makes use of gate charge retention technique. In a forward converter after the main transformer is reset its secondary voltage diminishes to zero. For self-driven synchronous rectifiers the driving voltage is lost and current is forced to go through body diode with high conduction loss. Active clamp is a method to get around the problem but it requires an active switch on the primary side. The present invention introduces gate charge retention method by, which no additional active switch is required on the primary side. Synchronous rectifiers are kept on even after the main transformer is reset and secondary voltage diminished to zero. This synchronous rectifier avoids effect of leakage inductance in converter transformer windings and operates at high efficiency. This synchronous rectifier can operate in a number of circuit topologies.

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Hong Kong, China

Pong Liu