Apparatus and method for detecting foreign object in wireless power transmitting system

Abstract

The present disclosure provides an apparatus and method for detecting a foreign object in a wireless power transmitting system. The wireless power transmitting apparatus measures an initial transmission power transmitted from the primary core block and performs foreign object detection on the basis of the initial transmission power, once it is found that an initial voltage of an output terminal of the wireless power receiving apparatus connected to an external load is within the range of a reference voltage. By performing foreign object detection while a wireless power receiving apparatus is in an initial setting completion state, before the output of the wireless power receiving apparatus is turned on, delay in detecting foreign objects may be reduced, and a risk due to heating of a foreign object may be avoided.

What is claimed is: 
     
         1 . A wireless power transmitting apparatus, comprising:
 a primary coil;   an electric driving unit coupled to the primary coil; and   a control unit configured to:
 cause the electric driving unit to generate an alternating current (AC) signal at an initial setting and provide the AC signal to the primary coil to produce an initial transmission power, 
 measure the initial transmission power at the primary coil, and 
 detect a foreign object based on a determination that the initial transmission power is larger than a reference value. 
   
     
     
         2 . The wireless power transmitting apparatus of  claim 1 , wherein the reference value is experimentally measured under controlled conditions when no foreign object is present. 
     
     
         3 . The wireless power transmitting apparatus of  claim 1 , wherein the control unit is further configured to obtain the reference value from a wireless power receiving apparatus, the reference value indicating an expected amount of power at the primary coil under controlled conditions of the wireless power receiving apparatus when no foreign object is present. 
     
     
         4 . The wireless power transmitting apparatus of  claim 1 , wherein the control unit is further configured to:
 refrain from entering a power transfer phase in response to detecting the foreign object.   
     
     
         5 . The wireless power transmitting apparatus of  claim 1 , wherein the control unit is further configured to:
 determine that an initial voltage of an output terminal of the wireless power receiving apparatus connected to an external load is at a steady state within a range of a reference voltage before measuring the initial transmission power.   
     
     
         6 . The wireless power transmitting apparatus of  claim 5 , wherein the control unit determines that the initial voltage is within the range of the reference voltage by receiving from the wireless power receiving apparatus a foreign object state packet indicating a start of a foreign object detection. 
     
     
         7 . The wireless power transmitting apparatus of  claim 5 , wherein the control unit controls the wireless power transmitting apparatus to enter a foreign object detection phase after determining that the initial voltage is within the range of the reference voltage. 
     
     
         8 . A method of a wireless power transmitting apparatus, comprising:
 causing an electric driving unit of the wireless power transmitting apparatus to generate an alternating current (AC) signal at an initial setting;   providing the AC signal to a primary coil of the wireless power transmitting apparatus to produce an initial transmission power;   measuring the initial transmission power at the primary coil; and   detecting a foreign object based on a determination that the initial transmission power being larger than a reference value.   
     
     
         9 . The method of  claim 8 , wherein the reference value is experimentally measured under controlled conditions when no foreign object is present. 
     
     
         10 . The method of  claim 8 , further comprising:
 obtaining the reference value from a wireless power receiving apparatus, the reference value indicating an expected amount of power at the primary coil under controlled conditions of the wireless power receiving apparatus when no foreign object is present.   
     
     
         11 . The method of  claim 8 , further comprising:
 refraining from entering a power transfer phase in response to detecting the foreign object.   
     
     
         12 . The method of  claim 8 , further comprising:
 checking that an initial voltage of an output terminal of a wireless power receiving apparatus connected to an external load is at a steady state within a range of a reference voltage before measuring the initial transmission power.   
     
     
         13 . The method of  claim 8 , further comprising:
 receiving a foreign object state packet from a wireless power receiving apparatus before measuring the initial transmission power, the foreign object state packet indicating a start of a foreign object detection phase.   
     
     
         14 . A wireless power transmitting apparatus comprising:
 a primary coil configured to transmit wireless power via a magnetic field using an alternating current (AC) signal;   an electric driving unit connected to the primary coil and configured to generate the AC signal; and   a control unit configured to perform a foreign object detection (FOD) in which the control unit is configured to:
 cause the electric drive unit to initially generate the AC signal at an initial voltage; 
 measure, as a first value, an amount of power at the primary coil; 
 determine that a foreign object is present in the magnetic field based on the first value measured being higher than a reference value, wherein the reference value indicates an experimentally measured amount of power at the primary coil under controlled conditions when no foreign object is present; and 
 refrain from entering into a power transfer phase after a determination that the foreign object is present in the magnetic field. 
   
     
     
         15 . The wireless power transmitting apparatus of  claim 14 , wherein the initial voltage is lower than a power transmission voltage for a transfer of wireless power to a wireless power receiving apparatus. 
     
     
         16 . The wireless power transmitting apparatus of  claim 14 , wherein the control unit is configured to determine that the foreign object is not present if the first value is less than or equal to the reference value. 
     
     
         17 . The wireless power transmitting apparatus of  claim 14 , wherein the control unit is configured to receive the reference value from the wireless power receiving apparatus. 
     
     
         18 . The wireless power transmitting apparatus of  claim 14 , wherein the control unit is further configured to:
 perform a digital ping via the primary coil during a ping phase, and   receive identification and configuration information from the wireless power receiving apparatus after the ping phase and before the power transfer phase, wherein the identification and configuration information includes the reference value.   
     
     
         19 . The wireless power transmitting apparatus of  claim 14 , wherein the control unit is further configured to:
 receive a foreign object detection status packet from the wireless power receiving apparatus, wherein the foreign object detection status packet is associated with initiating a foreign object detection phase before the power transfer phase.