WO2019084211A1

WO2019084211A1 - Magnetic pendulum array for efficient wireless power transmission

Info

Publication number: WO2019084211A1
Application number: PCT/US2018/057415
Authority: WO
Inventors: Yuanxun Ethan Wang
Original assignee: The Regents Of The University Of California
Priority date: 2017-10-25
Filing date: 2018-10-24
Publication date: 2019-05-02

Abstract

A mechanical antenna system and method is disclosed for near field wireless power transfer with high quality factor and low dissipation. A plurality of diametrically magnetized elements are disposed in a spaced-apart orientation to form a magnetic pendulum array. An electromagnetic energy source is positioned adjacent the magnetic pendulum array to generate a dynamic, time varying, magnetic field to physically rotate magnetic orientation of the plurality of diametrically magnetized elements to provide efficient wireless near field power transmission,

Description

MAGNETIC PENDULUM ARRAY FOR EFFICIENT

WIRELESS POWER TRANSMISSION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to, and the benefit of, U.S. provisional patent application serial number 62/577,019 filed on October 25, 2017, incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable

NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

[0003] A portion of the material in this patent document may be subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14. BACKGROUND

[0004] 1 . Technical Field

[0005] The technology of this disclosure pertains generally to wireless

power transmission, and more particularly to a magnetic pendulum antenna system.

[0006] 2. Background Discussion

[0007] Near field based wireless power transmission is often carried out with inductively coupled loops or coils. The power transfer relation for a near field based wireless power transfer system is governed by the following link Eq. 1 :

where Q₁ and Q₂ are the loaded quality factors of the transmitter and the receiver; Q_: i_nt and Q₂ i_nt are the intrinsic quality factors of the transmitting and receiving antennas; and k is the coupling coefficient determined by the distance between the antenna and the radius of the antenna. Thus, in order to achieve a high-power transfer efficiency, a high-quality factor antenna system is important. The higher quality factor the antenna has, the further distance the power can be transferred wirelessly.

[0008] Mechanical system such as spinning magnets have been used in the past for efficient wireless power transfer. However, those magnets are driven by motor where a low power conversion efficiency is expected as the motor is running with almost no load. This limits the overall system quality factor and the power transfer efficiency.

BRIEF SUMMARY

[0009] This disclosure describes a mechanical antenna system for near field wireless power transfer to take advantage of the high-quality factor and low dissipation in a mechanical system. By way of example and not of limitation, the technology combines RF coils with the magnetic pendulum array, which can improve quality factor and power transfer efficiency as the only primary loss mechanism is the friction loss.

[0010] Existing inductively coupled wireless power transmission systems cannot transfer power efficiently over a long distance because the quality factor of the coils limits the coupling distance. The magnetic pendulum antenna system described in this disclosure can provide a quality factor two or three order of magnitudes higher in the Ultra-Low Frequency (ULF) antenna systems compared to the state of art antennas made of coils. Therefore, wireless power transmission systems employing the described antenna technology can provide higher efficiency and sustain a longer effective range.

1] Further aspects of the technology described herein will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the technology without placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0012] The technology described herein will be more fully understood by reference to the following drawings which are for illustrative purposes only:

[0013] FIG. 1 shows a schematic diagram of a magnetic pendulum array for wireless power transfer as both transmitting and receiving antennas according to an embodiment of the technology described herein.

[0014] FIG. 2 is a schematic diagram of the magnetic pendulum array of

FIG. 1 , illustrating self-biasing through the mutual interaction of the magnetic pendulums.

[0015] FIG. 3 shows a schematic diagram of a 5-magnetic pendulum

system as a self-biased antenna according to an embodiment of the technology described herein.

[0016] FIG. 4 shows a schematic diagram of an experimental setup to

measure the resonance frequency and oscillation quality factor of the system of the present technology.

[0017] FIG. 5 is a plot showing a sample result of near-field measured with the ferrite antenna on the magnetic field transmitted with the magnetic pendulum. Measure frequency is 12.5 Hz and applied magnetic bias is

Be=13.6 mT.

[0018] FIG. 6 is a plot illustrating a comparison of measured and calculated oscillation frequencies for response to different magnetic biasing field.

[0019] FIG. 7 shows a schematic diagram of an experimental setup to

measure the RF excitation of the magnetic pendulum of the present technology.

DETAILED DESCRIPTION

[0001] A preferred embodiment of the systems and methods of the present description creates a dynamic magnetic field for wireless power transfer via use a magnetic pendulum array that is excited by RF coils as a mechanical antenna for transmitting and receiving of the wireless power at an ultra-low frequency (ULF) of below KHz. The magnetic pendulum provides low damping as a "perpetually moving machine". The high-quality factor of the magnetic pendulum's oscillatory movement is implemented to generate a dynamic magnetic field with high quality factor, thus to lead to high efficiency in wireless power transfer.

[0002] 1 . System Configuration

[0003] Referring to FIG. 1 , a schematic diagram of a magnetic pendulum system 10 is shown for wireless power transfer as both transmitting and receiving antennas according to an embodiment of the technology described herein.

[0004] An array 12 of diametrically magnetized elements configured as magnetic pendulums 12 is first aligned vertically by positioning the array 12 between opposing ends 16a and 16b of a permanent magnet, which operates as a biasing mechanism to generate external static magnetic field Be across the array 12. In a preferred embodiment, diametrically

magnetized magnet discs or rods 14 are selected to be the pendulums for load balance and for minimum air resistance. An electromagnetic energy source, such as two 1 kHz or lower RF coils 18a and 18b, are positioned horizontally across the array 12 (perpendicular to the external static magnetic field Be) to create a time varying horizontally oriented magnetic field BRF to physically rotate the magnets' 14 magnetic orientation toward the horizontal direction. The RF magnetic field BRF is much lower in magnitude than the DC magnetic field in general, yet still creates

substantial deviation of the magnets 14 away from their lowest energy state in a high-Q system, as oscillatory motion is built up given enough excitation time.

[0005] FIG. 2 shows a schematic diagram of a portion of the magnetic

pendulum array 12 of FIG. 1 , illustrating self-biasing through the mutual interaction of the magnetic pendulums 14. The primary role of the RF coil 18a, 18b is to inject the RF energy needed to build up the harmonic motion and replenish any losses including the RF energy that is being radiated and dissipated after the magnetic pendulum array reaches to its steady state. The oscillatory motion of the magnets generates a dynamic magnetic field in the horizontal direction. For the proposed pendulum system, the energy generated from the RF coil 18a, 18b will mainly supply that being lost in the form of friction loss or eddy current loss, which can be an extremely small fraction of the energy in the system.

[0006] The angular acceleration of a mass is governed by Newton's law in Eq. 2,

where I is the angular moment of inertia andT is a torque on the rotating mass.

[0007] A pendulum in a disc shape has a moment of inertia according to Eq. 3,

m„r² __ _n

I =— -— Eq. 3

2

where m_a is the mass and r is the radius of the disc. This results in a second order system with oscillatory solutions when the torque is a function of angular position. The magnetic pendulum receives a magnetic torque given by T = mxB where m is the magnetic dipole moment and B is the magnetic field, which can be an external field added through a biasing magnet or an internal field created by the neighboring pendulums.

[0008] For a single pendulum in a uniform external magnetic field B_e , the pendulum equation can now be given by Eq. 4,

where Θ is the swing angle of the pendulum as a function of time t , with reference to the magnetic field direction.

[0009] The solution of swin angle is thus given by Eq. 5:

[0010] For the magnetic pendulum array 12, the magnetic field from

adjacent magnets 14 may be configured to play a significant role interacting with the pendulum motion.

[0011] FIG. 2 shows a schematic diagram of a portion of the magnetic

pendulum array 12 of FIG. 1 , illustrating self-biasing through the mutual interaction of the magnetic pendulums 14. The magnetic field generated at each pendulum 14 by an adjacent pendulum placed along the longitudinal axis ( Θ = 0) at a distance of d ean be written in the form of a magnetic dipole field as Eq. 6:

[0012] The magnetic torque received by the pendulum is yielded as Eq. 7, r = mx B _ μ₀ιη ( ∞⁸θάχΔ) _ ^ (3cos9sm9) , a^a 4π d³ 4π d³

3sin2e _Λ Eq. 7

= -^Ba0^m^— ^x where B_ao is the radial magnetic field of the magnetic disc at the distance of d at zero swing angle according to Eq. 8,

[0013] In addition to the magnetic torque, a net force is often generated between two pendulums 14 within the array 12. However, in a vertically aligned pendulum array, it may be shown that the net force from the adjacent pendulums 14 cancel with each other, but the torque doubles at each pendulum 14. Therefore, one may write the total torque received by each pendulum in the array as Eq. 9:

— 3sin29 _Λ . , 3sin29 _Λ _ .

T_a = -B_a0m^— χ = -B_a0M_sV^— x Eq. 9.

[0014] The pendulum equation with both external biasing and self-biasing may now be written as Eq. 10,

[0015] The pendulum motion is governed by Eq. 1 1 ,

which yields the pendulum oscillation frequency as,

where r is the radius of the magnet disc, M_a is the magnetization density of the magnet in the pendulum and p is the density of the magnet.

[0016] In general, one may choose to rely on only a self-biasing field to

build the magnetic pendulum array 12 in a compact form, without the need of the bulky external magnets 16a and 16b (FIG. 1 ). The magnetic potential energy (Zeeman energy) is transferred to the kinetic energy of the pendulum back and forth while transmitting a dynamic magnetic field out.

FIG. 3 shows a schematic diagram of a 5-magnetic pendulum system 20 configured as a self-biased antenna according to an embodiment of the technology. The 5-magnetic pendulum system 20 comprises an array 12a of cylindrical magnets 14a supported in frame 22 by low friction bearings 24, bushings or like mechanism. The magnets 14a in system 20 are shown in FIG. 3 as having a length of 10 cm and diameter of 4 mm. However, it is appreciated that these dimensions are provided for exemplary purposes only, and other sizing and shape configurations are contemplated.

[0017] An intrinsic quality factor of at least 10⁴ to 10⁵ can be achieve with the setup of system 20. Therefore, the self-biased magnetic pendulum array 20, combined with RF coils (see 18a, 18b in FIG. 1 ), can be used as both transmitting antenna and receiving antenna for wireless power transfer.

[0018] 2. Experimental Demonstrations

[0019] FIG. 4 shows a schematic diagram of an experimental setup 50 to measure the resonance frequency and oscillation quality factor of the system of the present technology.

[0020] To demonstrate the concept of using a magnetic pendulum for

ULF/VLF transmitting, a bar-shaped NdFeB magnet 60 was assembled with a 3D printed plastic frame as a pendulum shown in the top picture in FIG. 4. The bar magnet 60 was fixed on the plastic frame through a tiny probe as its rotating axis. Two experiments were performed. The first was to observe the transmitting capability of the pendulum, including the oscillation frequency and quality factor and the second was to examine the movement of the pendulum excited by the RF coils.

[0021] In the first experiment, the magnetic pendulum 60 was placed

between the poles of an electromagnet 54 and a magnetic bias was introduced via applying a DC current (from power supply 58) to the electromagnet's terminals. Before the pendulum 60 was introduced into the gap region of the electromagnet 54, the magnetic field strength within the gap region was measured using a Gauss meter, then the pendulum 60 was placed within the gap. When the magnetic bias was turned on, the pendulum 60 aligned in the direction of the magnetic bias. When this stable equilibrium condition was disturbed by shifting the magnetic pendulum 60 by 90 degrees and then releasing it, it was observed that bar magnet started to oscillate, and the amplitude gradually decayed to the stable equilibrium state.

[0022] The frequency of oscillation was measured both with a high-speed camera (not shown) and a ferrite antenna 56 that was positioned about 1 meter away from the pendulum 60, with the output connected to an oscilloscope 52. The near-field of the oscillating magnet was detected with the ferrite antenna 56 connected to the oscilloscope to visualize the detected signal.

[0023] FIG. 5 shows a plot of the magnetic pendulum transmitting waveform from the setup 50 of FIG. 4 captured on the oscilloscope 52. FIG. 6 illustrates a plot of a comparison between the measured and calculated frequencies based on a similar Eq. 5, corresponding to different applied magnetic biasing field. As shown in FIG. 6 the measured values are slightly higher than the calculated values. This difference may be attributed to inaccurate knowledge of the properties of the magnet such as density or magnetization. The free oscillation of the pendulum 60 lasts for about 1 10 cycles based on the captured video, which corresponds to a quality factor of 350. This can be increased significantly with attention to mechanical design.

[0024] The second experiment was performed to illustrate that the magnetic pendulum can be excited with RF coils with a minimum amount of power if it is driven at the resonant frequency. The experimental setup 70 is shown in FIG. 7. In this setup, magnetic pendulum 60a was placed at the midpoint between two identical permanent magnets (e.g. see magnets 16a and 16b in FIG. 1 ). By doing so, the magnetic pendulum 60a was aligned in the direction of magnetic bias set by the permanent magnets but perpendicular to the direction of the electromagnet 72. Magnetic field strength created by these permanent magnets in the absence of the pendulum was measured as 10.9 mT at the midpoint and 25.8 mT at the surface of the permanent magnets. The electromagnet 72 is now driven by an alternating current via a signal generator (e.g. arbitrary waveform generator 74) that was employed to drive the magnetic pendulum 60a at the resonance frequency. To find the resonance frequency, a frequency range starting at 10 Hz was swept until the resonance frequency was found. At the resonance frequency, a high amplitude continuous oscillation was observed. The resonance frequency of the system was found to be 30 Hz in this particular case.

[0025] From the description herein, it will be appreciated that the present disclosure encompasses multiple embodiments which include, but are not limited to, the following:

[0026] 1 . An apparatus for near field wireless power transfer, the apparatus comprising: a plurality of diametrically magnetized elements in a spaced- apart orientation forming a magnetic pendulum array; an electromagnetic energy source positioned adjacent the magnetic pendulum array; and wherein the electromagnetic energy source is configured for generating a dynamic, time varying, magnetic field to physically rotate magnetic orientation of the plurality of diametrically magnetized elements in said magnetic pendulum array to provide wireless near field power transmission.

[0027] 2. The apparatus or method of any preceding or subsequent

embodiment: wherein the electromagnetic energy source comprises a plurality of radio-frequency (RF) coils; and wherein the magnetic pendulum array is disposed between the RF coils such that the dynamic, time varying, magnetic field is generated across the magnetic pendulum array.

[0028] 3. The apparatus or method of any preceding or subsequent

embodiment, wherein the plurality of diametrically magnetized elements in the magnetic pendulum array are aligned in a first orientation in response to self-biasing between the plurality of diametrically magnetized elements.

[0029] 4. The apparatus or method of any preceding or subsequent

embodiment, wherein the plurality of diametrically magnetized elements in the magnetic pendulum array are aligned in a first orientation in response to one or more biasing magnets disposed in proximity to the magnetic pendulum array to generate an external static magnetic field across the magnetic pendulum array.

[0030] 5. The apparatus or method of any preceding or subsequent embodiment, wherein the external static magnetic field is substantially perpendicular to the dynamic, time varying, magnetic field.

[0031] 6. The apparatus or method of any preceding or subsequent

embodiment, wherein said alignment in the first orientation is further in response to self-biasing between the plurality of diametrically magnetized elements

[0032] 7. The apparatus or method of any preceding or subsequent

embodiment, wherein the diametrically magnetized elements comprise diametrically magnetized magnet discs or rods selected to function as pendulums for efficient load balance and air resistance.

[0033] 8. The apparatus or method of any preceding or subsequent

embodiment, wherein said apparatus is configured for operation at an ultra- low frequency regime below one kilohertz.

[0034] 9. The apparatus or method of any preceding or subsequent

embodiment, wherein the diametrically magnetized magnet discs or rods are retained in said spaced-apart orientation within one or more bearings allowing for rotation of the discs or rods in response to the dynamic, time varying, magnetic field.

[0035] 10. The apparatus or method of any preceding or subsequent

embodiment, wherein said magnetic pendulum array comprises a self- biased antenna with self-biasing provided through mutual interaction of the diametrically magnetized elements in said magnetic pendulum array.

[0036] 1 1 . The apparatus or method of any preceding or subsequent

embodiment, wherein said magnetic pendulum array is configured to operate as one or more of: a power transmitting antenna and power receiving antenna.

[0037] 12. The apparatus or method of any preceding or subsequent

embodiment, wherein near field wireless power transfer of said apparatus has a quality factor two or three orders of magnitudes higher in Ultra Low Frequency (ULF) antenna systems compared to coil antennas.

[0038] 13. A method for near field wireless power transfer, the method comprising: biasing a plurality of diametrically magnetized elements in a spaced-apart orientation forming a magnetic pendulum array; generating a dynamic, time varying, magnetic field across the magnetic pendulum array to physically rotate magnetic orientation of the plurality of diametrically magnetized elements in the magnetic pendulum array; generating wireless near field power transmission as a result of the rotating motion of the magnetic pendulum array.

[0039] 14. The apparatus or method of any preceding or subsequent

embodiment, wherein near field power transmission is generated as a result of oscillatory motion of the diametrically magnetized elements.

[0040] 15. The apparatus or method of any preceding or subsequent

embodiment, wherein the dynamic, time varying, magnetic field is

generated with an electromagnetic energy source that comprises a pair of radio-frequency (RF) coils; and wherein the magnetic pendulum array is disposed between the RF coils such that the dynamic, time varying, magnetic field is generated across the magnetic pendulum array.

[0041] 16. The apparatus or method of any preceding or subsequent

embodiment, wherein the RF coils are configured to inject sufficient RF energy to build up a harmonic oscillatory motion of the diametrically magnetized elements and replenish any losses being radiated and dissipated after the magnetic pendulum array reaches steady state.

[0042] 17. The apparatus or method of any preceding or subsequent

embodiment, wherein biasing the plurality of diametrically magnetized elements comprises aligning magnetic pendulum array in a first orientation in response to self-biasing between the plurality of diametrically magnetized elements.

[0043] 18. The apparatus or method of any preceding or subsequent

embodiment, wherein biasing the plurality of diametrically magnetized elements comprises aligning magnetic pendulum array in a first orientation in response to one or more biasing magnets disposed in proximity to the magnetic pendulum array to generate an external static magnetic field across the magnetic pendulum array.

[0044] 19. The apparatus or method of any preceding or subsequent embodiment, wherein the diametrically magnetized elements comprise diametrically magnetized magnet discs or rods selected to function as pendulums for efficient load balance and air resistance.

[0045] 20. The apparatus or method of any preceding or subsequent

embodiment, wherein the wireless near field power transmission operates at an ultra-low frequency regime below one kilohertz.

[0046] 21 . The apparatus or method of any preceding or subsequent

embodiment, wherein the magnetic pendulum array operates as a self- biased antenna with self-biasing provided through mutual interaction of the diametrically magnetized elements in said magnetic pendulum array.

[0047] 22. The apparatus or method of any preceding or subsequent

embodiment, wherein said magnetic pendulum array is operates as one or more of: a power transmitting antenna and power receiving antenna.

[0048] 23. The apparatus or method of any preceding or subsequent

embodiment, wherein the generated near field wireless power transfer has a quality factor two or three orders of magnitudes higher in Ultra Low Frequency (ULF) antenna systems compared to coil antennas.

[0049] 24. A mechanical antenna apparatus for near field wireless power transfer, the apparatus comprising: a magnetic pendulum array; and a plurality of radio-frequency (RF) coils; wherein magnetic pendulums in said magnetic pendulum array are aligned in a first orientation in response to self-biasing between magnetic pendulums in said magnetic pendulum array, or in response to one or more biasing magnets, or in response to a combination of self-biasing and the use of one or more biasing magnets; and wherein said RF coils are configured for generating a dynamic, time varying, magnetic field to physically rotate magnetic orientation of the magnetic pendulums in said magnetic pendulum array to provide efficient wireless near field power transmission.

[0050] 25. The apparatus of any preceding or following embodiment,

wherein said apparatus is configured for operation at an ultra-low frequency regime below one kilohertz.

[0051] 26. The apparatus of any preceding or following embodiment, wherein each magnetic pendulum in said magnetic pendulum array comprises one or more magnetized elements configured for rotation within one or more bearings.

[0052] 27. The apparatus of any preceding or following embodiment,

wherein each magnetic pendulum in said magnetic pendulum array comprises a diametrically magnetized disk or rod retained for rotation within one or more bearings.

[0053] 28. The apparatus of any preceding or following embodiment,

wherein said magnetic pendulum array comprises a self-biased antenna with self-biasing provided through mutual interaction of the magnetic pendulums in said magnetic pendulum array.

[0054] 29. The apparatus of any preceding or following embodiment,

wherein said magnetic pendulum array is utilized as a power transmitting antenna, or as a power receiving antenna, or as a combination of power transmitting and receiving antenna.

[0055] 30. The apparatus of any preceding or following embodiment,

whereby said apparatus provides wireless power transmission with higher efficiency and a longer effective range than near field wireless power transfer utilizing coil antennas.

[0056] 31 . The apparatus of any preceding or following embodiment,

wherein near field wireless power transfer of said apparatus has a quality factor two or three orders of magnitudes higher in Ultra Low Frequency (ULF) antenna systems compared to coil antennas.

[0057] 32. A method for near field wireless power transfer, the method comprising: biasing a magnetic pendulum array into a first orientation in response to a biasing magnet, or self-biasing between magnetic pendulums in said magnetic pendulum array, or a combination of the self-biasing and the biasing magnet; and activating RF coils for generating a dynamic, time varying, magnetic field to physically rotate the magnetic orientation of the magnetic pendulums in said magnetic pendulum array for near field wireless power transfer.

[0058] As used herein, the singular terms "a," "an," and "the" may include plural referents unless the context clearly dictates otherwise. Reference to an object in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more."

[0059] As used herein, the term "set" refers to a collection of one or more objects. Thus, for example, a set of objects can include a single object or multiple objects.

[0060] As used herein, the terms "substantially" and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. When used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ± 10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1 %, less than or equal to ±0.5%, less than or equal to ±0.1 %, or less than or equal to ±0.05%. For example, "substantially" aligned can refer to a range of angular variation of less than or equal to ±10°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1 °, less than or equal to ±0.5°, less than or equal to ±0.1 °, or less than or equal to ±0.05°.

[0061] Additionally, amounts, ratios, and other numerical values may

sometimes be presented herein in a range format. It is to be understood that such range format is used for convenience and brevity and should be understood flexibly to include numerical values explicitly specified as limits of a range, but also to include all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified. For example, a ratio in the range of about 1 to about 200 should be understood to include the explicitly recited limits of about 1 and about 200, but also to include individual ratios such as about 2, about 3, and about 4, and sub-ranges such as about 10 to about 50, about 20 to about 100, and so forth. [0062] Although the description herein contains many details, these should not be construed as limiting the scope of the disclosure but as merely providing illustrations of some of the presently preferred embodiments. Therefore, it will be appreciated that the scope of the disclosure fully encompasses other embodiments which may become obvious to those skilled in the art.

[0063] All structural and functional equivalents to the elements of the

disclosed embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Furthermore, no element,

component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed as a "means plus function" element unless the element is expressly recited using the phrase "means for". No claim element herein is to be construed as a "step plus function" element unless the element is expressly recited using the phrase "step for".

Claims

What is claimed is: 1 . An apparatus for near field wireless power transfer, the apparatus comprising:

a plurality of diametrically magnetized elements in a spaced-apart orientation forming a magnetic pendulum array;

an electromagnetic energy source positioned adjacent the magnetic pendulum array; and

wherein the electromagnetic energy source is configured for generating a dynamic, time varying, magnetic field to physically rotate magnetic orientation of the plurality of diametrically magnetized elements in said magnetic pendulum array to provide wireless near field power transmission.

2. The apparatus of claim 1 :

wherein the electromagnetic energy source comprises a plurality of radio- frequency (RF) coils; and

wherein the magnetic pendulum array is disposed between the RF coils such that the dynamic, time varying, magnetic field is generated across the magnetic pendulum array.

3. The apparatus of claim 1 , wherein the plurality of diametrically magnetized elements in the magnetic pendulum array are aligned in a first orientation in response to self-biasing between the plurality of diametrically magnetized elements.

4. The apparatus of claim 1 , wherein the plurality of diametrically magnetized elements in the magnetic pendulum array are aligned in a first orientation in response to one or more biasing magnets disposed in proximity to the magnetic pendulum array to generate an external static magnetic field across the magnetic pendulum array.

5. The apparatus of claim 4, wherein the external static magnetic field is substantially perpendicular to the dynamic, time varying, magnetic field.

6. The apparatus of claim 4, wherein said alignment in the first orientation is further in response to self-biasing between the plurality of diametrically magnetized elements

7. The apparatus of claim 1 , wherein the diametrically magnetized elements comprise diametrically magnetized magnet discs or rods selected to function as pendulums for efficient load balance and air resistance.

8. The apparatus of claim 1 , wherein said apparatus is configured for operation at an ultra-low frequency regime below one kilohertz.

9. The apparatus of claim 7, wherein the diametrically magnetized magnet discs or rods are retained in said spaced-apart orientation within one or more bearings allowing for rotation of the discs or rods in response to the dynamic, time varying, magnetic field.

10. The apparatus of claim 1 , wherein said magnetic pendulum array comprises a self-biased antenna with self-biasing provided through mutual interaction of the diametrically magnetized elements in said magnetic pendulum array.

1 1 . The apparatus of claim 1 , wherein said magnetic pendulum array is configured to operate as one or more of: a power transmitting antenna and power receiving antenna.

12. The apparatus of claim 1 , wherein near field wireless power transfer of said apparatus has a quality factor two or three orders of magnitudes higher in Ultra Low Frequency (ULF) antenna systems compared to coil antennas.

13. A method for near field wireless power transfer, the method comprising:

biasing a plurality of diametrically magnetized elements in a spaced-apart orientation forming a magnetic pendulum array;

5 generating a dynamic, time varying, magnetic field across the magnetic pendulum array to physically rotate magnetic orientation of the plurality of diametrically magnetized elements in the magnetic pendulum array;

generating wireless near field power transmission as a result of the rotating motion of the magnetic pendulum array.

o

14. The method of claim 13, wherein near field power transmission is generated as a result of oscillatory motion of the diametrically magnetized elements. 5

15. The method of claim 14, wherein the dynamic, time varying,

magnetic field is generated with an electromagnetic energy source that comprises a pair of radio-frequency (RF) coils; and

wherein the magnetic pendulum array is disposed between the RF coils such that the dynamic, time varying, magnetic field is generated across the

0 magnetic pendulum array.

16. The method of claim 15, wherein the RF coils are configured to inject sufficient RF energy to build up a harmonic oscillatory motion of the diametrically magnetized elements and replenish any losses being radiated and dissipated after5 the magnetic pendulum array reaches steady state.

17. The method of claim 13, wherein biasing the plurality of diametrically magnetized elements comprises aligning magnetic pendulum array in a first orientation in response to self-biasing between the plurality of diametrically

0 magnetized elements.

18. The method of claim 13, wherein biasing the plurality of diametrically magnetized elements comprises aligning magnetic pendulum array in a first orientation in response to one or more biasing magnets disposed in proximity to the magnetic pendulum array to generate an external static magnetic field across the magnetic pendulum array.

19. The method of claim 13, wherein the diametrically magnetized elements comprise diametrically magnetized magnet discs or rods selected to function as pendulums for efficient load balance and air resistance.

20. The method of claim 13, wherein the wireless near field power transmission operates at an ultra-low frequency regime below one kilohertz.

21 . The method of claim 13, wherein the magnetic pendulum array operates as a self-biased antenna with self-biasing provided through mutual interaction of the diametrically magnetized elements in said magnetic pendulum array.

22. The method of claim 13, wherein said magnetic pendulum array is operates as one or more of: a power transmitting antenna and power receiving antenna.

23. The method of claim 13, wherein the generated near field wireless power transfer has a quality factor two or three orders of magnitudes higher in Ultra Low Frequency (ULF) antenna systems compared to coil antennas.