Zero-crossing current detection for modular and robust dynamic wireless power transfer

A synchronous inverter comprising:

• a primary inverter comprising switches that operate at an inverter switching frequency;
• a reactive component network comprising:
• a first primary inductor connected in series an output of the primary inverter;
• a first primary capacitor connected in parallel with the first primary inductor and the primary inverter;
• a second primary capacitor;
• a primary pad connected in series with the second primary capacitor, the primary pad comprising a primary pad inductance, the second primary capacitor and primary pad connected in parallel with the first primary capacitor, wherein the primary pad wirelessly transmits power to a synchronous secondary inverter;
• and
• a controller comprising:
• a switching enable circuit that starts switching of switches of the primary inverter in response to a first primary current of the first primary inductor being above a primary current threshold and disables switching of the switches of the primary inverter in response to the first primary current being below the primary current threshold;
• and
• a primary current filter with an input comprising a signal representative of the first primary current,
• wherein the output of the primary current filter controls switches in the primary inverter to provide a positive primary inverter voltage across the output of the primary inverter in response to the output of the primary current filter comprising a polarity indicative of a positive first primary current, and
• wherein the output of the primary current filter controls switches in the primary inverter to provide a negative primary inverter voltage across the output of the primary inverter in response to the output of the primary current filter comprising a polarity indicative of a negative first primary current.

A system comprising:

• a primary inverter comprising switches;
• a first primary inductor connected in series with an output of the primary inverter;
• a first primary capacitor connected in parallel with the first primary inductor and the primary inverter;
• a second primary capacitor;
• a primary pad connected in series with the second primary capacitor, the primary pad comprising a primary pad inductance, the second primary capacitor and primary pad connected in parallel with the first primary capacitor;
• a primary current filter configured to:
• detect a first primary current comprising a current in the first primary inductor;
• control switches in the primary inverter to provide a positive primary inverter voltage across the output of the primary inverter in response to detecting a positive first primary current;
• and
• control the switches in the primary inverter to provide a negative primary inverter voltage across the output of the primary inverter in response to detecting a negative first primary current;
• and
• a synchronous secondary inverter, wherein the primary pad wirelessly transmits power to a secondary pad of the synchronous secondary inverter.