Wireless power transfer system and wireless power transfer method

Abstract

A wireless power transfer system includes a plurality of power sources and at least one power receiver, in which power transfer from the power sources to the power receiver is performed in wireless by using magnetic field resonance or electric field resonance. In the system, one of the plurality of power sources is designated as a master power source and the other one or more power sources are designated as slave power sources. In addition, the master power source controls the plurality of power sources and the at least one power receiver to perform the power transfer. This allows the system to perform the power transfer in an optimum state.

What is claimed is: 
     
         1 . A wireless power transfer system comprising:
 a plurality of power sources; and   a power receiver,   power transfer from at least one of the plurality of power sources to the power receiver being performed in wireless by using magnetic field resonance or electric field resonance, wherein   each of the plurality of power sources includes:
 a power supply unit; 
 a wireless power transfer unit including a first LC resonator configured to receive power from the power supply unit and wirelessly transmit the power to the power receiver; and 
 a power transfer control unit configured to control the power supply unit and the wireless power transfer unit, wherein 
   the power transfer control unit controls the first LC resonator so as not to operate ordinarily.   
     
     
         2 . The wireless power transfer system as claimed in  claim 1 , wherein
 each of the plurality of power sources includes a switch configured to control an on-state or off-state of resonance of the first LC resonator, wherein   the power transfer control unit controls the switch so as not to operate the first LC resonator ordinarily.   
     
     
         3 . The wireless power transfer system as claimed in  claim 1 , wherein
 each of the plurality of power sources includes a wireless power transfer unit configured to wirelessly transmit power by using magnetic field resonance or electric field resonance, and   the power receiver includes a wireless power reception unit configured to receive the power wirelessly transmitted by using the magnetic field resonance or the electric field resonance.   
     
     
         4 . The wireless power transfer system as claimed in  claim 1 , wherein
 the power receiver includes a wireless power reception unit including a second LC resonator, a power reception circuit unit configured to extract power from the wireless power reception unit, and a power reception control unit configured to control the power reception circuit unit, wherein
 the power reception control unit controls the second LC resonator so as not to operate ordinarily. 
   
     
     
         5 . The wireless power transfer system as claimed in  claim 4 , wherein
 the first LC resonator directly receives a first power from the power supply unit, or   the first LC resonator receives the first power from the power supply unit via a power supply coil, the power supply coil receiving the first power from the power supply unit and supplying the first power by using electromagnetic induction to the first LC resonator.   
     
     
         6 . The wireless power transfer system as claimed in  claim 4 , wherein
 the second LC resonator directly supplies a second power to a load or a power supply of the power receiver, or   the second LC resonator supplies the second power to the load or the power supply of the power receiver via a power extraction coil, the power extraction coil receiving the second power by using electromagnetic induction from the second LC resonator and supply the second power to the load or the power supply of the power receiver.   
     
     
         7 . The wireless power transfer system as claimed in  claim 1 , wherein
 each of the plurality of power sources includes a first communication circuit unit configured to perform communication with other one or more of the power sources of the plurality of power sources and with the power receiver; and   the power receiver includes a second communication circuit unit configured to perform communication with the plurality of power sources.   
     
     
         8 . The wireless power transfer system as claimed in  claim 1 , wherein
 when the power receiver is a power receiver with a battery residual capacity of zero, the power receiver with the battery residual capacity of zero is arranged in contact with one of the plurality of power sources.   
     
     
         9 . The wireless power transfer system as claimed in  claim 1 , wherein
 each of the plurality of power sources includes an oscillator and a synchronization circuit; and   when the plurality of power sources perform the power transfer to the power receiver,
 one of the plurality of power sources is designated as a primary power source and the other one or more power sources are designated as secondary power sources; 
 the primary power source performs the power transfer according to a frequency of the oscillator; and 
 the secondary power sources synchronize the synchronization circuits of the secondary power sources with the frequency of the oscillator of the primary power source to perform the power transfer according to a frequency of the synchronization circuits of the secondary power sources in which the frequency has been synchronized therewith. 
   
     
     
         10 . A wireless power transfer method comprising a plurality of power sources and a power receiver, in which power transfer from at least one of the plurality of power sources to the power receiver is performed in wireless by using magnetic field resonance or electric field resonance, each of the plurality of power sources including a power supply unit; a wireless power transfer unit including a first LC resonator configured to receive power from the power supply unit and wirelessly transmit the power to the power receiver; and a power transfer control unit configured to control the power supply unit and the wireless power transfer unit, wherein the wireless power transfer method comprising:
 controlling, by the power transfer control unit, the first LC resonator so as not to operate ordinarily.   
     
     
         11 . The wireless power transfer method as claimed in  claim 10 , wherein
 each of the plurality of power sources includes a switch configured to control an on-state or off-state of resonance of the first LC resonator, wherein   the power transfer control unit controls the switch so as not to operate the first LC resonator ordinarily.   
     
     
         12 . The wireless power transfer method as claimed in  claim 10 , wherein
 when the power receiver is a power receiver with a battery residual capacity of zero, arranging the power receiver with the battery residual capacity of zero in contact with one of the plurality of power sources.   
     
     
         13 . The wireless power transfer method as claimed in  claim 10 , wherein
 the power receiver includes a wireless power reception unit including a second LC resonator, a power reception circuit unit configured to extract power from the wireless power reception unit, and a power reception control unit configured to control the power reception circuit unit, wherein
 the power reception control unit controls the second LC resonator so as not to operate ordinarily. 
   
     
     
         14 . The wireless power transfer method as claimed in  claim 13 , wherein
 the first LC resonator directly receives a first power from the power supply unit, or   the first LC resonator receives the first power from the power supply unit via a power supply coil, the power supply coil receiving the first power from the power supply unit and supplying the first power by using electromagnetic induction to the first LC resonator.   
     
     
         15 . The wireless power transfer method as claimed in  claim 13 , wherein
 the second LC resonator directly supplies a second power to a load or a power supply of the power receiver, or   the second LC resonator supplies the second power to the load or the power supply of the power receiver via a power extraction coil, the power extraction coil receiving the second power by using electromagnetic induction from the second LC resonator and supply the second power to the load or the power supply of the power receiver.   
     
     
         16 . The wireless power transfer method as claimed in  claim 10 , wherein
 each of the plurality of power sources includes an oscillator and a synchronization circuit; and   when the plurality of power sources perform the power transfer to the power receiver,   one of the plurality of power sources is designated as a primary power source and the other one or more power sources are designated as secondary power sources;   the primary power source performs the power transfer according to a frequency of the oscillator; and   the secondary power sources synchronize the synchronization circuits of the secondary power sources with the frequency of the oscillator of the primary power source to perform the power transfer according to a frequency of the synchronization circuits of the secondary power sources in which the frequency has been synchronized therewith.