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foreign_object_detection_in_the_qi_standard [2025/05/01 13:34] – [FOD technology applied in Qi standard] tmforeign_object_detection_in_the_qi_standard [2025/05/01 14:17] (current) – [1.Q-factor detection] tm
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-=====Foreign Object Detection in the Qi standard=====+======Foreign Object Detection in the Qi standard======
  
-====Classification of FOD methods====+=====Classification of FOD methods=====
  
 In the Qi standard, the transmitter emits power to the receiver via an high-frequency alternating magnetic field. Qi technology is defined as a [[Introduction of the Qi standard|low-power transfer standard]] which implies that it poses no health risk to living objects (LOs). In the Qi standard, no living object detection (LOD) is performed as there is no space between the charging pads where LOs (e.g. animals) can enter and interfere with the WPT. In the Qi standard, the transmitter emits power to the receiver via an high-frequency alternating magnetic field. Qi technology is defined as a [[Introduction of the Qi standard|low-power transfer standard]] which implies that it poses no health risk to living objects (LOs). In the Qi standard, no living object detection (LOD) is performed as there is no space between the charging pads where LOs (e.g. animals) can enter and interfere with the WPT.
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 | Figure 1 FOD methods (Zhang et al., 2019, p. 3) | | Figure 1 FOD methods (Zhang et al., 2019, p. 3) |
  
-====FOD technology applied in Qi standard====+=====FOD technology applied in Qi standard=====
  
 Analysis of a Qi-authorized 15 W transmitter: the Infineon WLC1515, reveals that it uses three distinct FOD methods based on system parameter detection. These include Q-factor measurement, power loss monitoring and over-temperature protection (Technologies, 2023, p. 29). Analysis of a Qi-authorized 15 W transmitter: the Infineon WLC1515, reveals that it uses three distinct FOD methods based on system parameter detection. These include Q-factor measurement, power loss monitoring and over-temperature protection (Technologies, 2023, p. 29).
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 When a metal object (MO) enters the coil’s magnetic field, it disturbs the field and induces eddy currents in the object. These eddy currents cause the coil’s inductance 𝐿 to decrease and its resistance 𝑅 to increase due to additional energy losses. As a result, the Q-factor drops, which can be used as an indication of a foreign object in wireless power transfer systems. As examined by Tian et al., when metal objects enter the charging zone, the quality factor of the Rx coil exhibits a significant downward trend, making it a suitable index for MOD within WPT systems such as the Qi standard (Tian et al., 2022, p. 3; Wireless Power Consortium (WPC), n.d.). When a metal object (MO) enters the coil’s magnetic field, it disturbs the field and induces eddy currents in the object. These eddy currents cause the coil’s inductance 𝐿 to decrease and its resistance 𝑅 to increase due to additional energy losses. As a result, the Q-factor drops, which can be used as an indication of a foreign object in wireless power transfer systems. As examined by Tian et al., when metal objects enter the charging zone, the quality factor of the Rx coil exhibits a significant downward trend, making it a suitable index for MOD within WPT systems such as the Qi standard (Tian et al., 2022, p. 3; Wireless Power Consortium (WPC), n.d.).
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 Practically, the quality factor of the receiver coil will be measured in a [[Power transfer architecture of the Qi standard|pre-power transfer phase]]. Next, Figure 2 shows how Q-factor FOD is created (Infineon, 2023, p. 5; Technologies, 2023, p. 25). Practically, the quality factor of the receiver coil will be measured in a [[Power transfer architecture of the Qi standard|pre-power transfer phase]]. Next, Figure 2 shows how Q-factor FOD is created (Infineon, 2023, p. 5; Technologies, 2023, p. 25).
  
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