Patent ID: 8134351

Claim:
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; a resonant capacitor with one end connected to said another end of said first switch; a first current rectifier switch with an anode end connected to another end of said resonant capacitor; a second current rectifier switch with an anode end connected to said common terminal and a cathode end connected to said anode end of said first current rectifier switch; a first resonant inductor with one end connected to a cathode end of said first current rectifier switch and another end connected to said output terminal; a second resonant inductor with one end connected to another end of said second switch and another end connected to said output terminal; switching means for keeping said first switch ON and said second switch OFF during T ON time interval, and keeping said first switch OFF and said second switch ON during T OFF time interval, where T ON and T OFF are complementary time intervals within one switching operating cycle T S ; wherein said first resonant inductor connected in series with said first switch, said first current rectifier and said resonant capacitor form a first resonant circuit during T ON time interval with a resonant period T r1 ; wherein said second resonant inductor connected in series with said second switch, said second current rectifier and said resonant capacitor form a second resonant circuit during T OFF time interval with resonant interval T r2 ; wherein a first resonant frequency f r1 of said first resonant circuit is independent of a second resonant frequency f r2 of said second resonant circuit; wherein said T ON time interval is adjusted to one half of a first resonant period or 0.5T r1 and said T OFF time interval is adjusted to one half of a second resonant period or 0.5T r2 to obtain a fixed 2:1 step-down conversion ratio with zero freewheeling period; wherein said T ON time interval is controlled by continuously reducing the ON-time interval, while keeping the OFF-time interval constant so that the freewheeling interval is continuously increasing causing the continuous decrease of the output voltage bellow 2:1 fixed step-down voltage conversion ratio.