Resonant converters including flying capacitors

A zero-voltage transition converter coupled to a direct current (DC) power source having a positive pole and a negative pole, the converter comprising:

• a first primary switching device having a first terminal electrically coupled to the positive pole of the DC power source, and a second terminal electrically coupled to a load;
• a second primary switching device having a first terminal electrically coupled to the load and a second terminal coupled to the negative pole of the DC power source;
• a first resonant capacitor coupled in parallel to the first primary switching device;
• a second resonant capacitor coupled in parallel to the second primary switching device;
• a flying capacitor (FC) circuit electrically coupled to the power source and the load, the FC circuit comprising at least one flying capacitor and at least four FC switching devices;
• a resonant inductor electrically coupled with the first primary switch, second primary switch, the load and the FC circuit;
• and
• a controller structured to operate the first primary switching device and the second primary switching device by opening and closing the first primary switching device and the second primary switching device so as to convert DC power from the DC power source into output power and transmit the output power to the load,
• wherein the controller is structured to operate the FC switching devices so as to generate substantially zero voltage switching conditions across the first primary switching device and the second primary switching device during the opening and closing of the first primary switching device and the second primary switching device,
• wherein the FC circuit and resonant tank are structured to allow no current to pass through the resonant inductor after opening one of the FC switching devices, and
• wherein the controller is structured to generate a resonating current by operating the FC switching devices such that a current flows through the resonant inductor.

A method for generating an output power by operating a pulse width modulation converter coupled to a DC power source comprising:

• operating circuitry including
• a flying capacitor circuit having a flying capacitor and a plurality of semiconductor switches coupled in parallel with the DC power source,
• a pair of primary semiconductor switches coupled in parallel with the DC power source,
• a resonant tank circuit having a resonant inductor and two resonant capacitors, the resonant tank circuit coupled with the flying capacitor circuit, the pair of primary switches, and a load;
• generating a resonating current in the resonant tank by operating the flying capacitor circuit such that the voltage across one of the primary semiconductor switches is a substantially zero voltage condition;
• opening one switch of the primary semiconductor switches;
• closing the other of the pair of primary semiconductor switches in a substantially zero voltage condition;
• and
• reducing the current in the resonant inductor by generating a midpoint voltage with the flying capacitor circuit.