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 power supply system comprising:
a power supply loop that is configured to be supplied with power from a power supply;
a power supply-side resonance coil that is configured to be supplied with power from the power supply loop in a non-contact manner, wherein the power supply-side resonance coil is part of a 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 );
a power receiving-side resonance coil that is configured to be supplied with power from the power supply-side resonance coil in a non-contact manner, wherein the power receiving-side resonance coil is part of a 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 );
a power receiving loop that is configured to be supplied with power from the power receiving-side resonance coil in a non-contact manner;
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, 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 using non-radiative electromagnetic induction having a coupling coefficient κ, wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>1 over the range of distances D, and wherein the coupling coefficient κ can be expressed as κ=ωM/2√{square root over (L s L d )}, wherein ω is the frequency of the resonant coupling, L s is the inductance of the power supply-side resonance coil, L d is the inductance of the power receiving-side resonance coil, and M is the mutual inductance between the power supply-side resonance coil and the power receiving side resonance coil.
2. The power supply system according to claim 1 , wherein the at least one of the distance between the power supply loop and the power supply-side resonance coil and the distance between the power receiving loop and the power receiving-side resonance coil is adjustable so as to increase a power supply efficiency.
3. The power supply system of claim 1 , wherein the power provided to the power receiving loop from the power receiving-side resonance coil defines a work drainage rate Γ w , and wherein the work drainage rate Γ 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>0.
4. The power supply system of claim 3 , wherein the parameter wp satisfies wp≧1.
5. The power supply system of claim 4 , wherein the parameter wp satisfies 1≦wp≦10.
6. The power supply system of claim 5 , wherein the parameter wp satisfies 1<wp≦10.
7. The power supply system of claim 6 , wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>2 over the range of distances D.
8. The power supply system of claim 3 , wherein the parameter wp is set to optimize an efficiency of the non-contact power supply of the power supply-side resonance coil by the power receiving-side resonance coil.
9. The power supply 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.
10. The power supply system of claim 3 , wherein the parameter wp is set to decrease energy stored in the device resonator.
11. The power supply system of claim 3 , wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>2 over the range of distances D.
12. The power supply system of claim 1 , further comprising a portable electronic device comprising the power receiving loop, 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.
13. The power supply system of claim 12 , wherein power provided to the load from the device resonator is at least 1 Watt.
14. The power supply system of claim 1 , wherein Q 1 >100.
15. The power supply system of claim 14 , wherein the intrinsic quality factors satisfy √{square root over (Q 1 Q 2 )}>100.
16. The power supply system of claim 15 , wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>2 over the range of distances D.
17. The power supply system of claim 1 , further comprising a vehicle comprising the power receiving loop, wherein a load is coupled to the power receiving loop 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.
18. The power supply system of claim 17 , wherein f 1 and f 2 , are between 10 kHz and 100 kHz.
19. The power supply system of claim 17 , wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>5 over the range of distances D.
20. The power supply system of claim 17 , wherein the power provided to the load from the device resonator is on the order of 1 kW.
21. The power supply system of claim 17 , wherein Q 1 >100 and Q 2 >100.
22. The power supply system of claim 17 , 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.
23. The power supply system of claim 1 , wherein the intrinsic loss rates satisfy κ/√{square root over (Γ 1 Γ 2 )}>2 over the range of distances D.