Patent ID: 11929202
Assignee: MOJO MOBILITY, INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  B  Y | IPC B  H

Claim 54:
55. A method for inductive power transfer to a mobile device, wherein the mobile device includes a receiver, the method comprising:
positioning the receiver in a power transfer position to inductively receive power from an inductive charger; and
inductively transferring power from the charger to the receiver of the mobile device;
wherein:
the charger includes:
a printed circuit board having a charger coil, wherein the charger coil has a substantially planar charger surface, and the charger coil includes a conductor patterned to include multiple, substantially concentric turns and an outermost of the concentric turns defines a perimeter of a charger coil area;
a substantially planar magnetic layer under the charger coil opposite the charger surface, wherein the magnetic layer of the charger extends beyond the charger coil area; and
a charger drive circuit, wherein the charger drive circuit includes a resonant capacitor and a field effect transistor (FET) switch to apply an alternating voltage to the charger coil;

the receiver includes:
a solenoid, wherein the solenoid includes:
a magnetic core having a relative magnetic permeability exceeding 1 and having first and second ends; and
wire wrapped around a section of the magnetic core forming a wire wound section around the magnetic core, with the magnetic core extending beyond the wire wound section; and

a receiver electronic circuit, wherein the receiver electronic circuit includes a resonant capacitor and a rectifier; and
inductively transferring power from the charger to the receiver comprises:
driving the charger coil with the charger driver circuit at one or more operating frequencies to inductively transfer power from the charger to the receiver when the receiver is positioned in the power transfer position, wherein when the receiver is positioned in the power transfer position, a turned circuit, which includes the charger coil and the resonant capacitor of the charger drive circuit and the solenoid and the resonant capacitor of the receiver electronic circuit, has a resonant frequency that allows the charger to transfer the power to the receiver at the one or more operating frequencies;
generating a magnetic field that is substantially perpendicular to the charger surface at a geometric center of the charger coil area; and
generating magnetic flux through the charger coil and through a first end of the solenoid when the receiver is placed in the power transfer position; and

when the receiver is in the power transfer position, the first end of the magnetic core is located proximate to the charger coil area above the charger surface to receive the magnetic flux from the charger coil area and guide the magnetic flux in a closed magnetic loop from the charger coil area through the solenoid and return through the charger magnetic layer to the charger coil area to form the closed magnetic loop; and
the charger does not include magnetic material between the charger coil and the solenoid when the receiver is positioned in the power transfer position.