Automatically tuning a transmitter to a resonance frequency of a receiver
AssigneeApple Inc.
InventorLi-Quan Tan
Life of this patent
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Abstract
Various embodiments of a wirelessly powered local computing environment are described. The wireless powered local computing environment includes at least a near field magnetic resonance (NFMR) power supply arranged to wirelessly provide power to any of a number of suitably configured devices. In the described embodiments, the devices arranged to receive power wirelessly from the NFMR power supply must be located in a region known as the near field that extends no further than a distance of a few times a characteristic size of the NFMR power supply transmission device. Typically, the distance can be on the order of 1 meter or so. The NFMR power supply is used to tune a transmitter in order to maintain a high Q factor.
Claims28
A wireless power transmission unit comprising:
- a varying frequency excitation source arranged to provide a variable circuit excitation at frequency f;
- and
- a first resonator structure coupled to the varying frequency f power supply, the first resonator structure having a resonant frequency ω1, a first Q factor Q1, and a characteristic size L1 wherein non-radiative energy transfer between the first resonator structure and at a second resonator structure positioned apart from the transmission unit, the second resonator structure having a resonant frequency ω2, a second Q factor Q2, and a characteristic size L2 is mediated through a magnetic resonant coupling associated with evanescent tails between the first resonator structure and the second resonator structure when the first resonator structure and the second resonator structure are in a tuned state when the first resonant frequency Γ1 and the second resonant frequency ω2 are within the narrower of first resonance width Γ1 or second resonance width Γ2 such that the first resonant frequency ω1 and the resonant frequency ω2 are separated by a bandwidth of no more than 3db, wherein the first resonator structure maintains the first resonator structure and the second resonator structure in the tuned state by varying the first resonant frequency ω1 such that the first resonant frequency ω1 and the resonant frequency ω2 are separated by the bandwidth of no more than 3db or are within the narrower of first resonance width Γ1 or second resonance width Γ2 in accordance with any changes in the second resonant frequency ω2.
A wirelessly powered local computing environment, comprising:
- a variable frequency power supply arranged to provide power at a frequency;
- an resonance frequency adjustable near field magnetic resonance (NFMR) wireless transmitter coupled to the power supply and arranged to create a resonance channel used to transfer useable energy from the power supply to a receiver within a near field distance d;
- and
- a central processing unit, the central processing unit providing processing resources to the variable frequency power supply and the resonance frequency adjustable NFMR transmitter, wherein when the NFMR transmitter establishes a resonance coupling with the receiver, the central processing unit maintains at least a minimum system Q factor Qsystem by adjusting only the resonance frequency of the NFMR transmitter.
A method performed by a wireless power transmission unit for automatically tuning a wireless power transmission system, comprising:
- the wireless power transmission unit including at least a first resonator structure coupled to a varying frequency f voltage supply,
- in a tuned state, establishing a magnetic resonant inductive coupling between the first resonator structure to a second resonator structure positioned apart from the wireless power transmission unit;
- non-radiatively transferring useable power from the first resonator structure to the second resonator structure using the magnetic resonant inductive coupling between the first resonator structure and the second resonator structure, wherein in the tuned state, a first resonant frequency ω1 of the first resonator structure and a second resonant frequency ω2 of the second resonator structure are separated by a bandwidth of no more than 3db;
- wherein the first resonator structure maintains the first resonator structure and the second resonator structure in the tuned state by varying a first resonant frequency ω1 of the first resonant structure in order to maintain the separation of the first resonant frequency ω1 and the second resonant frequency ω2 of no more than 3db in accordance with any change in the second resonant frequency ω2.
Dependencies are inferred from the claim text.