Abstract: In one embodiment, a method for frequency control in a wireless power transmitter comprises detecting a resonant frequency of the wireless power transmitter, determining an optimized frequency that is at least approximately 1% greater than the detected resonant frequency, and operating the wireless power transmitter at the optimized frequency. In one embodiment, the optimized frequency is approximately 1% to 15% greater than the detected resonant frequency. In one embodiment, the optimized frequency is approximately 5% greater than the detected resonant frequency. In one embodiment, the method further comprises detecting an amount of change in the resonant frequency of the wireless power transmitter, adjusting the optimized operating frequency by the amount of change in the resonant frequency, and operating the wireless power transmitter at the adjusted optimized operating frequency.

Abstract: In one embodiment, a wireless power transfer coil structure comprises a wheel core comprising an annulus portion and at least two spoke portions arranged substantially symmetrically with respect to a geometric center of the annulus portion, the wheel core formed from a magnetic material, and a coil located on an outer surface of the annulus portion of the wheel core. In one embodiment, the wireless power transfer coil structure further comprises at least one solenoidal coil wound around the at least two spoke portions of the wheel core. In one embodiment, the at least one solenoidal coil is wound around one of the at least two spoke portions of the wheel core in a first direction and wound around another of the at least two spoke portions of the wheel core in the first direction.

Abstract: In one embodiment, a wireless power transfer coil structure comprises a wheel core comprising an annulus portion and at least two spoke portions arranged substantially symmetrically with respect to a geometric center of the annulus portion, the wheel core formed from a magnetic material, and a coil located on an outer surface of the annulus portion of the wheel core. In one embodiment, the wireless power transfer coil structure further comprises at least one solenoidal coil wound around the at least two spoke portions of the wheel core. In one embodiment, the at least one solenoidal coil is wound around one of the at least two spoke portions of the wheel core in a first direction and wound around another of the at least two spoke portions of the wheel core in the first direction.