Fm scavenging for wireless charging of electric vehicles and other devices

Abstract

An apparatus, system, and method directed to the charging of electronic devices, and in particular to the wireless charging of battery enabled devices using FM band signals

1 . An apparatus for charging an electric vehicle, the apparatus comprising:
 at least one antenna element, disposed in a loop or in a portion of a loop;   a detector, coupled to the antenna, for detecting radio frequency energy in a Frequency Modulation (FM) broadcast band, the detector further comprising a first type of detector and a second type of detector;   a controller, coupled to the detector, for providing an output indicating whether the first type of detector or the second type of detector provides a higher signal strength;   a rectifier, coupled to the controller, and selectively coupled to either the first type of detector or the second type of detector, depending on the output of the controller, for providing a direct current output; and   an energy storage device, coupled to be charged by the direct current output provided by the rectifier.   
     
     
         2 . The apparatus of  claim 1  wherein the antenna element is a rim of a vehicle wheel or a conductor disposed within a rim of a vehicle wheel. 
     
     
         3 . The apparatus of  claim 2  additionally comprising:
 a capacitive coupler, disposed adjacent the vehicle wheel, to provide a capacitive connection to the detector. 
 
     
     
         4 . The apparatus of  claim 1  wherein the first type of detector is a magnetic dipole mode detector and the second type of detector is an electric dipole mode detector. 
     
     
         5 . The apparatus of  claim 1  wherein
 the antenna element further comprises a pair of loop antenna elements, each loop antenna element providing two output terminals; and 
 the magnetic dipole mode detector further comprises a four port circuit, with two ports coupled to the two output terminals of a first one of the antenna elements, and two other ports coupled to the two output terminals of a second one of the antenna elements; and 
 the electric dipole mode detector further comprises a four port circuit, with two ports connected to a selected output terminal of the first one of the antenna elements, and two other ports coupled to another selected output terminal of the second one of the antenna elements. 
 
     
     
         6 . The apparatus of  claim 1  wherein the detector is tunable. 
     
     
         7 . The apparatus of  claim 1  wherein the controller is additionally for selectively coupling the energy storage device to the rectifier or to some other power source. 
     
     
         8 . A method for charging an electric vehicle, the method comprising:
 receiving, via at least one antenna element having a loop shape or a portion of a loop shape, a received radio signal;   detecting the received radio signal including detecting a first mode signal and a second mode signal;   determining whether the first mode signal or the second mode signal has higher signal strength;   selectively generating a direct current output from either the first mode signal or the second mode signal, depending on which has the higher signal strength; and   charging an energy storage device by using the direct current output.   
     
     
         9 . The method of  claim 8  wherein the detecting step additionally comprises:
 tuning to two or more frequencies within the FM band. 
 
     
     
         10 . The method of  claim 8  additionally comprising:
 selectively coupling the energy storage device to the direct current output or to some other power source. 
 
     
     
         11 . An apparatus for charging an electric vehicle, the apparatus comprising:
 a first antenna element, disposed in a loop or in a portion of a loop within the vehicle, and arranged to receive radio frequency energy emitted from a second antenna element external to the vehicle, the second antenna element disposed in a loop or in a portion of a loop;   a detector, coupled to the antenna, for detecting the radio frequency energy, the detector further comprising an electric dipole mode detector;   a rectifier, coupled to the electric dipole mode detector. for providing a direct current output;   an automatic tuner, coupled to the first antenna element, arranged to compensate for impedance mismatch caused by alignment of the first and second antennas; and   an energy storage device, coupled to be charged by the direct current output provided by the rectifier.   
     
     
         12 . The apparatus of  claim 11  wherein the first antenna within the vehicle has a larger diameter than the second antenna external to the vehicle. 
     
     
         13 . The apparatus of  claim 11  wherein charging of the energy storage device occurs even when the first and second antennas are not positionally aligned. 
     
     
         14 . The apparatus of  claim 11  wherein the radio frequency energy is emitted in low frequency 40 MHz. 
     
     
         15 . The apparatus of  claim 11  wherein the adjustment circuit further comprises a Voltage Standing Wave Ratio (VSWR) detector and an output impedance adjustment circuit coupled to the second wire loop antenna. 
     
     
         16 . The apparatus of  claim 11  wherein the adjustment circuit further comprises a detector and a receive impedance adjustment circuit connected to the first wire loop antenna. 
     
     
         17 . The apparatus of  claim 11  wherein the first wire loop is three feet in diameter. 
     
     
         18 . The apparatus of  claim 17  wherein the second wire loop is between one-half and one foot in diameter. 
     
     
         19 . The apparatus of  claim 11  wherein the first wire loop is formed of a metallic pipe having a cross sectional dimension between one-quarter and one-half inch. 
     
     
         20 . The apparatus of  claim 11  wherein the radio frequency energy is between 30 and 60 MHz. 
     
     
         21 . The apparatus of  claim 11  additionally comprising:
 a VSWR meter coupled to the second wireless loop; 
 a detector coupled to the output of the VSWR meter to detect variations in transmit power above a determined level; and 
 a controller, coupled to disable the radio frequency energy source in response to the detector. 
 
     
     
         22 . The apparatus of  claim 11  wherein the second antenna is located beneath a paved surface.