US Patent 9590525 Wireless power transfer systems using load feedback

A system includes an AC input port configured to be coupled to an AC power source, a first AC/DC converter circuit having a first port coupled to the AC input port, and a first resonant circuit coupled to the first port of the first AC/DC converter circuit. The system further includes a second resonant circuit inductively coupled to the first resonant circuit, a second AC/DC converter circuit coupled to the second resonant circuit and a control circuit configured to control the first AC/DC converter circuit responsive to an output of the second AC/DC converter circuit.