초록 ▼

A power converter has a self-driven synchronous rectification circuit that can operate efficiently with a non-optimal reset secondary voltage waveform that remains at a zero voltage level during a portion of the switching cycle. The power converter circuit includes a transformer having a primary win

A power converter has a self-driven synchronous rectification circuit that can operate efficiently with a non-optimal reset secondary voltage waveform that remains at a zero voltage level during a portion of the switching cycle. The power converter circuit includes a transformer having a primary winding and a secondary winding, in which primary winding is supplied with a non-optimal reset waveform that remains at a zero voltage level for a portion of a power cycle thereof. A first synchronous rectifier is connected in series with the first end of the secondary winding and is controlled by a voltage at the second end of the secondary winding. A second synchronous rectifier is connected in series with the second end of the secondary winding, and is further connected to an output terminal of the power converter circuit through a storage choke. A saturable reactor is connected in series between the first synchronous rectifier and the first end of the secondary winding. A switching device is connected to the first end of the secondary winding and is controlled by the voltage at the second end of the secondary winding. The switching device further controls the second synchronous rectifier. A capacitor is connected to the second synchronous rectifier, and is charged by operation of the switching device to maintain the second synchronous rectifier in a conductive state during the zero voltage level portion of the non-optimal reset waveform. Upon transition to a positive voltage level portion of the waveform following the zero voltage level portion, the capacitor discharges through the switching device. The saturable reactor precludes current from flowing through the first synchronous rectifier for a period of time sufficient to allow the capacitor to discharge.

대표청구항 ▼

[ What is claimed is:] [1.]1. A power converter circuit, comprising:a transformer having a primary winding and a secondary winding, said secondary winding having a first end and a second end, said primary winding being supplied with a periodic voltage waveform that remains at a zero voltage level fo

[ What is claimed is:] [1.]1. A power converter circuit, comprising:a transformer having a primary winding and a secondary winding, said secondary winding having a first end and a second end, said primary winding being supplied with a periodic voltage waveform that remains at a zero voltage level for a portion of a power cycle thereof;a first synchronous rectifier connected in series with said first end of said secondary winding and controlled by a voltage at said second end of said secondary winding;a second synchronous rectifier connected in series with said second end of said secondary winding, said second synchronous rectifier being further connected to an output terminal of said power converter circuit through a storage choke;a saturable reactor connected in series between said first synchronous rectifier and said first end of said secondary winding;a switching device connected to said first end of said secondary winding and controlled by said voltage at said second end of said secondary winding, said switching device further controlling said second synchronous rectifier; anda capacitor connected to said second synchronous rectifier, said capacitor being charged by operation of said switching device to maintain said second synchronous rectifier in a conductive state during said zero voltage level portion of said periodic voltage waveform, wherein upon transition to a positive voltage level portion of said periodic voltage waveform following said zero voltage level portion, said capacitor discharges through said switching device, and said saturable reactor precludes current from flowing through said first synchronous rectifier for a period of time sufficient to allow said capacitor to discharge.