Hybrid-switching step-down converter with a hybrid transformer

摘要

The present invention employs a resonant inductor, a resonant capacitor and a hybrid transformer using a Hybrid-switching method with three switches which results in two distinct switched-networks: one for ON-time interval and another for OFF-time interval. Resonant inductor is placed in series with the hybrid transformer primary to insure the continuity of primary and secondary currents at the switching transitions and thus eliminating completely the potential switching losses at the switching transitions. In the best use of the invention the resonant inductor is replaced by use of the inherent leakage inductance of the transformer and for the first time eliminate the switching losses always associated with the transformer leakage inductance of all other switching converters. The output voltage is controlled by the standard Pulse Width Modulated (PWM) duty ratio control.

主权项

1. A switching DC-to-DC converter for providing power from a DC voltage source connected between an input terminal and a common terminal to a DC load connected between an output terminal and said common terminal, said converter comprising:
a first switch with one end connected to said input terminal; a second switch with one end connected to another end of said first switch and another end connected to said output terminal; a current rectifier switch with anode end connected to said common terminal; a resonant capacitor with one end connected to said another end of said first switch; a resonant inductor with one end connected to another end of said resonant capacitor; a first winding of a hybrid transformer with an unmarked end connected to another end of said resonant inductor and a dot-marked end connected to a cathode end of said current rectifier switch; a second winding of said hybrid transformer with an unmarked end connected to said dot-marked end of said first winding, and a dot-marked end of said second winding connected to said output terminal; switching means for keeping said first switch ON and said second switch and said current rectifier switch OFF during a TON time interval, and keeping said first switch OFF and said second switch and said current rectifier switch ON during a TOFF time interval, where said TON and said TOFF time interval are complementary time intervals within one switch operating cycle Ts; wherein said resonant inductor and said resonant capacitor form a resonant circuit during said TOFF time interval with a resonant current flowing through said first winding into said DC load; wherein a first turns ration of said hybrid transformer is a total number of turns of both said first winding and said second winding divided by a number of turns of said second winding of said hybrid transformer, wherein an input current during said TON time interval stores an inductive energy in said first and said second winding and during said TOFF time interval said stored inductive energy is transferred to said DC load through said second winding by n times higher current than said input current, wherein a second turns ratio m of said hybrid transformer is the ratio between the number of turns of said first winding and said second winding of said hybrid transformer, wherein said resonant current in said first winding is amplified by said second turns ratio m of said hybrid transformer and sent to said DC load through said second winding of said hybrid transformer, wherein a duty ratio D is a ratio between said TON time interval and said switching operating cycle Ts, and wherein a DC-to-DC voltage step-down conversion ratio of said converter depends on said duty ratio D and said first turns ratio n of said hybrid transformer.