Wireless energy transfer
Disclosed is an apparatus for use in wireless energy transfer, which includes a first resonator structure configured to transfer energy non-radiatively with a second resonator structure over a distance greater than a characteristic size of the second resonator structure. The non-radiative energy transfer is mediated by a coupling of a resonant field evanescent tail of the first resonator structure and a resonant field evanescent tail of the second resonator structure.
1. A wireless power system comprising:
a source resonator and a power supply coupled to the source resonator to provide power to the source resonator, the source resonator having a resonant frequency ω 1 , an intrinsic loss rate Γ 1 , and an intrinsic quality factor Q 1 =ω 1 /(2Γ 1 ), the source resonator comprising at least one loop of conductive material; and
a device resonator and a load coupled to the device resonator to receive power from the device resonator and provide power to the load, the device resonator having a resonant frequency ω 2 , an intrinsic loss rate Γ 2 , and an intrinsic quality factor Q 2 =ω 2 /(2Γ 2 ), the device resonator comprising at least one loop of conductive material,
wherein the device resonator is configured to be movable relative to the source resonator over a range of distances D between the source resonator and the device resonator,
wherein the source resonator and the device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the device resonator using non-radiative electromagnetic induction having a coupling coefficient κ, and wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>1 over the range of distances D, and
wherein the power provided to the load from the device resonator defines a work drainage rate Γ w , and wherein the work drainage rateΓ w , is configured to be set such that Γ w =Γ 2 √{square root over (1+wp·(κ 2 /Γ 1 ·Γ 2 ))} for some value of the coupling coefficient κ in the range of distances D, wherein wp is a parameter satisfying wp>1.
2. The wireless power system of claim 1 , wherein the parameter wp satisfies 1<wp≦10.
3. The wireless power system of claim 1 , wherein the parameter wp is set to decrease energy stored in the device resonator.
4. The wireless power system of claim 3 , wherein the parameter wp is set to decrease energy stored in the device resonator to prevent breakdown of a capacitor material providing a capacitance for the device resonator.
5. The wireless power system of claim 1 , further comprising a portable electronic device comprising the device resonator and the load, wherein the portable electronic device is a cell phone, a computer, or a robot, wherein f 1 =ω 1 /(2π) and f 2 =ω 2 /(2π), and f 1 and f 2 , are between 1 MHz and 10 MHz, and wherein each intrinsic loss rate comprises a resistive component and a radiative component.
6. The wireless power system of claim 5 , wherein Q 1 >100.
7. The wireless power system of claim 6 , wherein the intrinsic quality factors satisfy √{square root over (Q 1 Q 2 )}>100.
8. The wireless power system of claim 5 , wherein power provided to the load from the device resonator is at least 1 Watt.
9. The wireless power system of claim 8 , wherein the wirelessly coupled electromagnetic power transferred between the source and device resonators operates with a radiation loss less than about 10%.
10. The wireless power system of claim 9 , wherein the wirelessly coupled electromagnetic power transferred between the source and device resonators operates with a radiation loss less than about 1%.
11. The wireless power system of claim 5 , wherein the source resonator has a characteristic size L 1 and the device resonator has a different characteristic size L 2 .
12. The wireless power system of claim 5 , further comprising a second portable electronic device comprising a second device resonator and a second load coupled to the second device resonator to receive power from the second device resonator and provide power to the second portable electronic device, and
wherein the second device resonator is moveable relative to the source resonator and wherein the source resonator and the second device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the second device resonator using non-radiative electromagnetic induction.
13. The wireless power system of claim 1 , wherein the parameter wp satisfies 1<wp≦10, and wherein the parameter wp is set to prevent breakdown of a capacitor material providing a capacitance for the device resonator.
14. The wireless power system of claim 13 , further comprising a portable electronic device comprising the device resonator, wherein the portable electronic device is a cell phone, a computer, or a robot, wherein f 1 =ω 1 /(2π) and f 2 =ω 2 /(2π), and f 1 and f 2 , are between 1 MHz and 10 MHz, and wherein each intrinsic loss rate comprises a resistive component and a radiative component.
15. The wireless power system of claim 14 , wherein Q 1 >100, wherein power provided to the load from the device resonator is at least 1 Watt, and wherein the source resonator has a characteristic size L 1 and the device resonator has a different characteristic size L 2 .
16. The wireless power system of claim 15 , wherein the intrinsic quality factors satisfy √{square root over (Q 1 Q 2 )}>100.
17. The wireless power system of claim 15 , wherein the wirelessly coupled electromagnetic power transferred between the source and device resonators operates with a radiation loss less than about 10%.
18. The wireless power system of claim 15 , and wherein the wireless power system further comprises a second portable electronic device comprising a second device resonator and a second load coupled to the second device resonator to receive power from the second device resonator and provide power to the second portable electronic device, and
wherein the second device resonator is moveable relative to the source resonator and wherein the source resonator and the second device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the second device resonator using non-radiative electromagnetic induction.
19. The wireless power system of claim 1 , further comprising an intermediate resonator having a resonant frequency ω 3 , an intrinsic loss rate Γ 3 , and an intrinsic quality factor Q 3 =ω 3 /(2Γ 3 ), the intermediate resonator comprising at least one loop of conductive material and having a capacitance, and wherein the source resonator and the device resonator are configured to resonantly and wirelessly couple electromagnetic power from the source resonator to the device resonator through the intermediate resonator.
20. The wireless power system of claim 19 , wherein Q 3 >100.
21. The wireless power system of claim 13 , further comprising a vehicle comprising the device resonator, wherein the load is coupled to the device resonator to receive power from the device resonator, wherein the power provided to the load from the device resonator is greater than 10 Watts, and wherein f 1 =ω 1 /(2π) and f 2 =ω 2 /(2π), and f 1 and f 2 , are between 10 kHz and 1 MHz.
22. The wireless power system of claim 21 , wherein f 1 and f 2 , are between 10 kHz and 100 kHz.
23. The wireless power system of claim 22 , wherein the power provided to the load from the device resonator is on the order of 1 kW, wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>5 over the range of distances D, and wherein Q 1 >200 and Q 2 >200.
24. The wireless power system of claim 21 , wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>5 over the range of distances D.
25. The wireless power system of claim 21 , wherein the power provided to the load from the device resonator is on the order of 1 kW.
26. The wireless power system of claim 21 , wherein Q 1 >100 and Q 2 >100.