Abstract: In one embodiment, a wireless power transfer system comprises a transmitter coil structure comprising a first transmitter coil, and a second transmitter coil coupled to the first transmitter coil in such a way that when a first current flows in the first transmitter coil in a first spatial direction the first current flows in the second transmitter coil in a second spatial direction different from the first spatial direction, a foreign object sensor coil structure comprising a first sensor coil having a central axis in common with the first transmitter coil, and a second sensor coil coupled in series to the first sensor coil, the second sensor coil having a central axis in common with the second transmitter coil, the first sensor coil coupled to the second sensor coil in such a way that when a first voltage induced in the first sensor coil has a first polarity a second voltage induced in the second sensor coil has a second polarity different from the first polarity, a voltage detector coupled to the foreign o

Abstract: In one embodiment, an apparatus comprises a coil structure comprising a first coil and a second coil, each of the first coil and the second coil having a first side portion, a center portion, and a second side portion, wherein the first side portion forms a first angle with the center portion and the second side portion forms a second angle with the center portion, and a layer of magnetic material adjacent to the center portion of the first coil and the center portion of the second coil, the first coil and the second coil being configured such that when a current flows in a first spatial direction in the first coil a current flows in a second spatial direction different from the first spatial direction in the second coil. In one embodiment, the apparatus further comprises a power circuit configured to provide a time-varying current to the coil structure and a battery configured to provide a direct current to the power circuit.

Abstract: In one embodiment of a wireless power transmitter, two coils are magnetically coupled together by placing both coils on a magnetic layer. A power circuit generates an AC signal of a defined voltage magnitude that causes a current to flow through the first coil, which generates a magnetic field having a first polarity. The second coil is coupled to the first coil. Current flows through the second coil and generates a magnetic field having a second polarity that is opposite from the first polarity. Because the magnetic field generated by each coil has a different polarity, the magnetic fields attract and form a strong magnetic field that flows from the first coil to the second coil. The strong magnetic field can transfer greater amounts of power to a receiver in comparison to coil configurations that emit magnetic fields in the same direction that repel one another.

Abstract: In one embodiment a wireless power transfer system comprises a transmitter including a power source configured to generate a time-varying current, a first coil configured to receive the first time-varying current from the power source, wherein the time-varying current flows in the first coil in a first direction, a second coil coupled to the first coil in such a way that the time-varying current flows in the second coil in a second direction, wherein the first direction is opposite from the second direction, and an underlying magnetic layer configured to magnetically couple the first coil with the second coil, and a wireless power receiver, a ferrite core and a receiver coil that share a longitudinal axis, and a receive circuit coupled to the receiver coil configured to convert a time varying current induced in the receiver coil into a voltage.

Abstract: Systems and methods are presented for detecting a foreign object on a wireless power transmitter, the transmitter configured to wirelessly charge power to a device when the device is on or in close proximity to a charging surface of the transmitter. The system includes a wireless power transmitter and a controller coupled to the wireless power transmitter. The controller is configured to detect a first resonant frequency of the wireless power transmitter when an object is not present on or is not in close proximity to the charging surface of the wireless power transmitter, detect a second resonant frequency of the wireless power transmitter in response to applying a power to the wireless power transmitter, compare the first resonant frequency and the second resonant frequency, and based on the comparison, determine whether an object is on or is in close proximity to the charging surface of the wireless power transmitter.

Abstract: In one embodiment, a power converter includes a wireless transmitter coil and a resonant capacitor that is configured to resonate at a first frequency. The wireless transmitter coil and resonant capacitor are configured to receive an alternating current at a second frequency such that the power converter outputs a first voltage that is dependent on the second frequency. In one embodiment, the first and second frequency are substantially equal. The power converter may also include an interconnection link configured to substantially double or vary the first voltage depending on a duty cycle that is applied to the interconnection link.

Abstract: In one embodiment, a coil structure for wireless power transfer comprises a ferrite core and at least two coils wound around the ferrite core, the at least two coils located symmetrically about a geometric center of the ferrite core, the at least two coils wound in such a way that when a first current flows in a first spatial direction in one of the at least two coils a second current flows in a second spatial direction in the other one of the at least two coils. In one embodiment, the coil structure is implemented in a wireless power receiver to receive power from a wireless power transmitter or to guide alignment of the receiver to the transmitter. In another embodiment, the coil structure is implemented in a wireless power transmitter to produce a magnetic field for wireless power transfer.

Abstract: In one embodiment, a multiple interleaved coil structure for wireless power transfer includes a plurality of incomplete coils, each of the plurality of incomplete coils configured such that an alternating current flowing in the incomplete coil produces a magnetic field, and at least one interconnect between the plurality of incomplete coils, the at least one interconnect including a plurality of conductors arranged in such a way that the alternating current flowing in the plurality of conductors does not produce a magnetic field. Each of the plurality of incomplete coils includes a plurality of non-contiguous segments arranged in such a way that the incomplete coil will emit magnetic flux in response to an applied alternating current. The multiple interleaved coil structure can be implemented in a wireless power transmitter or a wireless power receiver.

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, an array for wireless power transfer includes a plurality of tuned resonant microcell structures (hereinafter “microcell”). Each microcell comprises at least one coil, at least one capacitor, and two connection points. Each microcell in the array is configured to be individually tuned to the same resonant frequency. The microcells in the array are connected together in a series through the two connection points of each microcell in such a way that the array is configured to have the same resonant frequency as each of the individually tuned microcells. The multiple coil structure may be connected to a power source and can be implemented in a wireless power transmitter.

Abstract: In one embodiment, a wireless power transfer system comprises a transmitter coil structure comprising a first transmitter coil, and a second transmitter coil coupled to the first transmitter coil in such a way that when a first current flows in the first transmitter coil in a first spatial direction the first current flows in the second transmitter coil in a second spatial direction different from the first spatial direction, a foreign object sensor coil structure comprising a first sensor coil having a central axis in common with the first transmitter coil, and a second sensor coil coupled in series to the first sensor coil, the second sensor coil having a central axis in common with the second transmitter coil, the first sensor coil coupled to the second sensor coil in such a way that when a first voltage induced in the first sensor coil has a first polarity a second voltage induced in the second sensor coil has a second polarity different from the first polarity, a voltage detector coupled to the foreign o

Abstract: In one embodiment of a wireless power transmitter, two coils are magnetically coupled together by placing both coils on a magnetic layer. A power circuit generates an AC signal of a defined voltage magnitude that causes a current to flow through the first coil, which generates a magnetic field having a first polarity. The second coil is coupled to the first coil. Current flows through the second coil and generates a magnetic field having a second polarity that is opposite from the first polarity. Because the magnetic field generated by each coil has a different polarity, the magnetic fields attract and form a strong magnetic field that flows from the first coil to the second coil. The strong magnetic field can transfer greater amounts of power to a receiver in comparison to coil configurations that emit magnetic fields in the same direction that repel one another.

Abstract: In one embodiment, a wireless power transmitter comprises a transmitter coil structure comprising a magnetic layer having a geometric center line, the magnetic layer being curved symmetrically about a geometric center line, a first coil coupled to a second coil, the first coil and second coil wound in such a way that when a current flows in the first coil in a first spatial direction the current flows in the second coil in a second spatial direction, the first coil and the second coil disposed on the magnetic layer substantially symmetrically about the geometric center line of the magnetic layer, a power circuit configured to provide a time-varying current to the transmitter coil structure; and a housing including an outer surface having a convex shape, the transmitter coil structure being disposed underneath the outer surface of the housing.

Abstract: In one embodiment, a multiple interleaved coil structure for wireless power transfer includes a plurality of incomplete coils, each of the plurality of incomplete coils configured such that an alternating current flowing in the incomplete coil produces a magnetic field, and at least one interconnect between the plurality of incomplete coils, the at least one interconnect including a plurality of conductors arranged in such a way that the alternating current flowing in the plurality of conductors does not produce a magnetic field. Each of the plurality of incomplete coils includes a plurality of non-contiguous segments arranged in such a way that the incomplete coil will emit magnetic flux in response to an applied alternating current. The multiple interleaved coil structure can be implemented in a wireless power transmitter or a wireless power receiver.

Abstract: In one embodiment, a wireless power alignment guide uses multiple coils and a detector circuit to determine an offset between a wireless power receiver and a wireless power transmitter. A transmitter generates a magnetic field that causes a first time-varying current to flow in a first coil and a second time-varying current to flow in a second coil of the wireless power alignment guide. The first time-varying current can flow to the second coil and the second time-varying current can flow to the first coil. A detector circuit detects a voltage resulting from the first time-varying current and the second time-varying current and determines an offset so the user can center the receiver with the transmitter. By correcting any offset between the receiver and the transmitter, greater amounts of power can be transferred to the receiver in comparison to a receiver that is offset from a transmitter.