Efficient and robust wireless energy transfer

Abstract

A method or apparatus for wireless transferring energy between a source coil and a drain coil, comprises setting an initial resonant frequency of the source coil as a first condition; setting the source coil and said drain coil in positions relative to each other to define an initial coupling coefficient therebetween, so that the initial coupling coefficient comprises a second condition; and adiabatically changing one or both of the conditions while pumping energy into the source coil. The source coil energy is transferred to the drain coil over the course of the adiabatic change.

What is claimed is: 
     
         1 . A system for mid-range wireless power transfer using a rapid adiabatic passage process for a coherently driven two-mode system, the system comprising:
 a source coil; and   a drain coil;   the source and the drain coils being configured in relation to each other to define a coupling coefficient, a loss rate, and a detuning value therebetween, said detuning value being a difference between a first resonant frequency of said source coil and a second resonant frequency of said drain coil, wherein said coupling coefficient is larger than said loss rate, and wherein said detuning value is relatively larger than said coupling coefficient;   said source coil being part of a variable component resonant circuit to allow changes in said first resonant frequency to change said detuning value; and   said source and said drain coils being movable relative to each other to change said coupling coefficient.   
     
     
         2 . The system of  claim 1 , configured to vary said variable component resonant circuit to change said resonant frequency adiabatically. 
     
     
         3 . The system of  claim 1 , configured to move said source and drain coils to change said coupling component adiabatically. 
     
     
         4 . The system of  claim 2 , configured to move said source and drain coils to change said coupling component adiabatically under a constraint of retaining said coupling coefficient to be larger than said loss rate, and to ensure that an initial and a final level of said detuning value are both relatively larger than said coupling coefficient. 
     
     
         5 . The system of  claim 1 , configured to vary said variable component resonant circuit to sweep said first resonant frequency slowly from a negative value larger than said coupling coefficient to a positive value larger than said coupling coefficient. 
     
     
         6 . The system of  claim 1 , further configured to rotate said source coil. 
     
     
         7 . The system of  claim 5 , configured to modify said varying to reduce an amount of time that energy is retained in said source coil. 
     
     
         8 . The system of  claim 1 , configured to vary said resonant frequency of said source coil by an amount of up to ten percent over a period of between one and three milliseconds. 
     
     
         9 . The system of  claim 1 , configured to vary said resonant frequency of said source coil by an amount of up to ten percent over a period exceeding two milliseconds. 
     
     
         10 . The system of  claim 9 , further configured to vary said coupling coefficient over said period. 
     
     
         11 . A method for mid-range wireless power transfer using a rapid adiabatic passage process for a coherently driven two-mode system, the system comprising:
 placing a source coil in relation to a drain coil to define a coupling coefficient, a loss rate, and a detuning value therebetween, said detuning value being a difference between a first resonant frequency of said source coil and a second resonant frequency of said drain coil;   providing an initial positioning wherein said coupling coefficient is larger than said loss rate, and wherein said detuning value is relatively larger than said coupling coefficient;   varying a resonant frequency of said source coil during said rapid adiabatic passage process to allow changes in said first resonant frequency to change said detuning value; and   moving source and said drain coils relative to each other during said rapid adiabatic passage process to change said coupling coefficient.