Patent ID: 7796406

Claim:
A DC-DC converter comprising: a first stage, comprising a first controllable bridge adapted to control conduction of current to and from a first and a second poles of said converter to a first central tap using a first and a second switching means arranged in a totem-pole arrangement between said first and said second poles, the voltage between said first and said second poles is denoted Vin; a first and a second capacitors connected in series between said first and said second poles forming a third tap between them; a second stage, comprising a second controllable bridge adapted to control conduction of current to and from a third and a fourth poles of said converter to a second central tap using a third and a fourth switching means arranged in a totem-pole arrangement between said third and a said fourth poles, the voltage between said third and said fourth poles is denoted Vout; a third and a fourth capacitors connected in series between said third and said fourth poles forming a fourth tap between them; a resonance circuit having a first path connected between said first and said second taps and a second path connected between said third and said fourth taps, said resonance circuit comprising at least a resonance inductor and a resonance capacitor, said resonance circuit having a resonance frequency; and a control unit adapted to switch ON and OFF each of said first, second, third and fourth switching means, and to receive indication of a reference voltage and of said Vin and said Vout wherein said first, said second, said third and said fourth switching means are provided with control signals to control the actual frequency of said converter and the phase shift between said first stage and said second stage, said control signals being provided so as to maintain the frequency of said first stage and of said second stage within a first operational region ranging substantially from frequency f min to frequency f 1 or within a second operational region ranging substantially from said frequency f 1 to frequency f 2 ; wherein f min is the frequency at which for a given load of said converter the phase is substantially 0.2π when control signals of said primary and said secondary stages are in-phase with said resonance circuit and the reactive portion the current through said switching means is just large enough to enable soft switching; wherein said f 1 is the frequency at which for a given load of said converter said phase is substantially 0.5π when control signals of said primary stage and said secondary stage are yet in-phase with said resonance circuit; and wherein said f 2 is the maximum available frequency at which soft switching is still possible for said converter and control signals of said primary stage and said secondary stage are in phase difference of substantially π.