Soft-switching power converters using air-core resonant inductor

A resonant circuit structured to be coupled to a non-resonant power converter including a switching device, the resonant circuit comprising:

• a first input terminal structured receive power from a DC power source;
• a second input terminal structured receive power from the DC power source;
• a first DC bus rail coupled to the first input terminal;
• a second DC bus rail coupled to the second input terminal;
• a leg including a first wide bandgap semiconductor device and a second wide bandgap semiconductor device coupled in series at a midpoint connection;
• an LC resonant tank including an air-core resonant inductor and a resonant capacitor, the LC resonant tank being coupled between the midpoint connection and an output port;
• and
• a controller structured to operate the first wide bandgap semiconductor device and the second wide bandgap semiconductor device so as to provide a resonant current to the non-resonant power converter by way of the LC resonant tank effective to provide a substantially zero voltage condition across the switching device when turning the switching device on.

A method for operating a bi-level power converter comprising:

• operating circuitry including:
• an auxiliary circuit including a first auxiliary switching device and a second auxiliary switching device coupled at an auxiliary midpoint connection,
• a primary circuit including a first primary switching device and a second primary switching device coupled at a primary midpoint connection, and
• an LC resonant tank including an air-core resonant inductor and a resonant capacitor coupled between the auxiliary midpoint connection and the primary midpoint connection;
• generating a resonating current using the air-core resonant inductor and the resonant capacitor of the LC resonant tank by operating the auxiliary circuit such that a voltage across the first primary switching device is a substantially zero voltage condition;
• opening the first primary switching device;
• and
• closing the second primary switching device in the substantially zero voltage condition.