Method of communicating with a wireless power transmitter and wireless power receiver

Abstract

The present disclosure provides a method and a wireless power receiver for communicating with a wireless power transmitter. The method comprises: receiving, by the wireless power receiver, a power signal having a predetermined strength from the wireless power transmitter; transmitting, by the wireless power receiver, a data packet comprising a mode bit field to the wireless power transmitter, the mode bit field indicating whether the data packet comprises a reference peak frequency of the wireless power receiver, wherein the reference peak frequency is pre-assigned to the wireless power receiver; and receiving, by the wireless power receiver, a response from the wireless power transmitter indicating a presence or absence of a foreign object in a charging area, wherein the response is determined based on a comparison of a peak frequency of a measured power signal and an adaptive threshold frequency adjusted based on the reference peak frequency.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201780053470.6, filed on June 30, 2017, with an international application number of PCT / KR2017 / 006975, an invention title of "Method for detecting foreign matter and apparatus and system therefor", which entered the Chinese national phase. TECHNICAL FIELD

[0002] Embodiments relate to wireless power transmission technology, and more particularly, to a method for detecting foreign matter in a wireless charging system and an apparatus and system therefor. BACKGROUND

[0003] Recently, as information and communication technology is rapidly developing, an ubiquitous society based on information and communication technology is being developed.

[0004] In order to connect information communication devices anytime and anywhere, sensors equipped with computer chips having communication functions should be installed in all social facilities. Therefore, supplying power to such devices or sensors is a new challenge. In addition, as the types of mobile devices (e.g., music players such as Bluetooth phones or iPods and mobile phones) are rapidly increasing, users need to spend more time and effort to charge batteries. As a method of solving such problems, wireless power transmission technology has recently attracted attention.

[0005] Wireless power transmission or wireless energy transfer refers to a technology of wirelessly transmitting electric power from a transmitter to a receiver using a magnetic induction principle. In the 19th century, electrodes or transformers utilizing the electromagnetic induction principle have been used, and thereafter, it has been attempted to transfer electric power by radiating electromagnetic waves (e.g., high frequency, microwave, and laser). Electric toothbrushes or some wireless shavers that are frequently used are charged using the electromagnetic induction principle.

[0006] So far, wireless energy transfer methods can be roughly classified into a magnetic induction method, an electromagnetic resonance method, and a radio frequency (RF) transmission method of short wave RF.

[0007] The magnetic induction method uses a phenomenon that, when two coils are adjacent to each other and then a current is applied to one coil, magnetic flux is generated so that an electromotive force is generated in the other coil, and is rapidly commercialized in small devices (e.g., mobile phones). The magnetic induction method can transfer electric power of up to several hundred kilowatts (kW) and has high efficiency. However, since the maximum transmission distance is 1 centimeter (cm) or less, a device to be charged should be adjacent to a charger or a floor.

[0008] Electromagnetic resonance uses electric or magnetic fields instead of electromagnetic waves or electric current. It is less affected by electromagnetic waves, making it advantageously safe for other electronic devices or the human body. However, it can be used over limited distances and spaces, and its energy transfer efficiency is slightly lower.

[0009] Shortwave wireless power transmission (RF transmission) utilizes the fact that energy can be directly transmitted and received in the form of radio waves. This technology is an RF wireless power transmission method that uses a rectifier antenna. A rectifier antenna is a combination of an antenna and a rectifier, and refers to a component that directly converts RF power into DC power. That is, the RF method is a technology used to convert AC radio waves into DC. Recently, with the improvement in the efficiency of the RF method, active research has been conducted on its commercialization.

[0010] Wireless power transmission technology can be used not only in mobile-related industries, but also in various other industries such as IT, railways, and home appliances.

[0011] If a conductor that is not a wireless power receiver (i.e., a foreign object (FO)) is present in the wireless charging area, electromagnetic signals received from the wireless power transmitter can be introduced into the FO, causing the temperature to rise. For example, the FO may include a coin, clip, pin, and ballpoint pen.

[0012] If an external foil (FO) exists between the wireless power receiver and the wireless power transmitter, wireless charging efficiency may be significantly reduced, and the temperatures of both the receiver and transmitter may rise due to the increased ambient temperature of the FO. If the FO is not removed from the charging area, power may be wasted, and both the wireless power transmitter and receiver may be damaged due to overheating.

[0013] Therefore, accurately detecting the FO located in the charging area is becoming an important issue in wireless charging technology. Summary of the Invention

[0014] Technical issues

[0015] The embodiments provide a method, apparatus and system for detecting foreign objects in wireless charging.

[0016] One embodiment provides a wireless power transmission device that can more accurately detect foreign objects by applying weights that are linearly or exponentially determined based on a reference quality factor and dynamically determining a threshold or threshold range for detecting foreign objects.

[0017] One implementation provides a wireless power transmission device capable of detecting foreign objects based on the quality factor and inductance value of a resonant circuit measured prior to the ping phase.

[0018] The embodiments provide a method, apparatus, and system for detecting foreign objects (FODs). The method enables more accurate FOD detection by measuring the quality factor and inductance of a resonant circuit before the ping phase when an object is detected in the charging region, and comparing the measured values ​​with a threshold determined based on FOD status data packets during the negotiation phase. The embodiments also provide a wireless power transmitter capable of detecting FODs based on a quality factor measured at a specific frequency within the operating band.

[0019] One implementation provides a wireless power transmitter capable of detecting foreign objects based on an average quality factor measured at a specific frequency in the operating band.

[0020] The technical problems solved by the implementation methods are not limited to the technical problems described above, and other technical problems not described herein will become apparent to those skilled in the art based on the following description.

[0021] Technical solutions

[0022] The embodiments provide a method, apparatus and system for detecting foreign objects.

[0023] In one embodiment, a method for detecting foreign objects in a wireless power transmitter including a resonant circuit for wirelessly transmitting power includes: detecting an object placed in a charging area; measuring a quality factor of the resonant circuit when the object is detected; transmitting a sensing signal to identify a wireless power receiver; determining a threshold for detecting foreign objects based on a reference quality factor received from the identified wireless power receiver; and comparing the measured quality factor with the determined threshold to determine the presence of a foreign object, wherein the threshold is determined by applying a weight that is increased according to the reference quality factor.

[0024] Here, the weights can be increased linearly or exponentially based on the reference quality factor value.

[0025] Alternatively, the threshold can be determined by further applying a predefined tolerance and a design factor corresponding to the wireless power transmitter, and the threshold can also be determined by adding the product of the tolerance and the reference quality factor and the design factor, and then subtracting the weight from the summed value.

[0026] The method may further include: starting to charge the identified wireless power receiver when it is determined that no foreign object is present; and stopping power transmission through the resonant circuit when it is determined that a foreign object is present, and outputting a predetermined alarm signal indicating that a foreign object has been detected.

[0027] When power transmission stops, the method can return to detecting the object placed in the charging area.

[0028] The method may further include comparing the quality factor of the resonant circuit measured after return with a determined threshold to check whether the foreign object has been removed from the charging area.

[0029] Once it is confirmed that the foreign object has been removed, the interrupted power transmission can be resumed.

[0030] The reference quality factor can be received while the reference quality factor is included in the foreign object detection status data packet received during the negotiation phase.

[0031] Determining the presence of foreign matter may include: determining the absence of foreign matter when the measured quality factor exceeds a threshold, and determining the presence of foreign matter when the measured quality factor is equal to or less than the threshold.

[0032] According to another embodiment, a method for detecting foreign objects in a wireless power transmitter including a resonant circuit for wirelessly transmitting power includes: detecting an object placed in a charging area; measuring a quality factor value of the resonant circuit when the object is detected; transmitting a sensing signal to identify a wireless power receiver; determining a threshold for detecting foreign objects based on a reference quality factor value received from the identified wireless power receiver; and comparing the measured quality factor value with a determined threshold range to determine whether a foreign object is present, wherein the threshold range is determined by applying an upper limit weight and a lower limit weight increased according to the reference quality factor value.

[0033] According to another embodiment, an apparatus for detecting foreign objects includes: a resonant circuit including a resonant capacitor and a resonant inductor; a sensing unit configured to detect an object placed in a charging area; a measuring unit configured to measure a quality factor value of the resonant circuit when an object is detected; and a controller configured to determine a threshold for detecting foreign objects based on a reference quality factor value received from an identified wireless power receiver, and to compare the measured quality factor value with the determined threshold value to determine whether a foreign object is present, wherein the threshold value is determined by applying a weight that is increased according to the reference quality factor value.

[0034] Here, the weights can be increased linearly or exponentially based on the reference quality factor, and the threshold can be determined by adding the predefined tolerance to the product of the reference quality factor and the design factor corresponding to the wireless power transmitter, and then subtracting the weights from the summed value.

[0035] Additionally, the controller can perform the following actions: when it is determined that no foreign object is present, begin charging the identified wireless power receiver; and when it is determined that a foreign object is present, stop power transmission through the resonant circuit and output a predetermined alarm signal indicating that a foreign object has been detected.

[0036] The controller can return to the selection phase after power transmission is stopped, and will compare the quality factor of the resonant circuit measured after the return with the determined threshold to check whether foreign objects have been removed from the charging area.

[0037] The controller can perform control to resume stopped power transmission when it is detected that the foreign object has been removed.

[0038] Additionally, the device may include: a DC-to-DC converter configured to convert DC power from a power source into specific DC power; and an inverter configured to convert the converted DC power into AC power. When the measurement by the measurement unit terminates, the controller can control the DC-to-DC converter and the inverter to periodically send digital pings for identifying the wireless power receiver, and can identify the wireless power receiver upon receiving a signal strength indicator corresponding to the digital ping.

[0039] The measurement unit can measure the quality factor of the resonant circuit based on the voltage measured across the resonant capacitor.

[0040] According to another embodiment, an apparatus for detecting foreign objects includes: a resonant circuit including a resonant capacitor and a resonant inductor; a sensing unit configured to detect an object placed in a charging area; a measuring unit configured to measure a quality factor of the resonant circuit when an object is detected; and a controller configured to determine a threshold range for detecting foreign objects based on a reference quality factor received from an identified wireless power receiver, and to compare the measured quality factor with the determined threshold range to determine whether a foreign object is present, wherein the threshold range is determined by applying an upper limit weight and a lower limit weight increased according to the reference quality factor.

[0041] According to another embodiment, a method for detecting foreign objects in a wireless power transmitter including a resonant circuit for wirelessly transmitting power includes: measuring a first inductance value of the resonant circuit; receiving a foreign object detection status data packet from a wireless power receiver; determining a threshold for detecting foreign objects based on the foreign object detection status data packet; and comparing the measured first inductance value with the determined threshold to determine whether a foreign object is present.

[0042] Additionally, the method may include: detecting an object placed in the charging area and identifying a wireless power receiver, and the measured first inductance value may include the inductance value of the resonant circuit as a result of the detected object.

[0043] Alternatively, the first inductance value can be measured after the object is detected but before proceeding to the step of identifying the wireless power receiver.

[0044] In addition, the method also includes measuring the quality factor of the resonant circuit after the object is detected and before proceeding to the step of identifying the wireless power receiver.

[0045] Additionally, the method may include stopping the transmission of power to the wireless power receiver based on the result of determining whether a foreign object is present.

[0046] Additionally, the method may include: adjusting the power transmitted to the identified wireless power receiver based on the result of determining whether a foreign object is present.

[0047] In addition, the method may also include: outputting an alarm signal indicating that a foreign object has been detected based on the result of determining that a foreign object is present.

[0048] Additionally, the method may include detecting an object placed in the charging area after power transmission has been stopped.

[0049] Additionally, the method may include: measuring a second inductance value of the resonant circuit after power transmission is stopped, and comparing the measured second inductance value with a determined threshold to determine whether the detected foreign object has been removed from the charging area.

[0050] In addition, the foreign object detection status data packet may include at least one of a reference quality factor and a reference inductance value.

[0051] Additionally, the reference inductance value may include the inductance value of the resonant circuit measured when the wireless power receiver is located in a charging area free of foreign objects.

[0052] In one implementation, the foreign object detection status data packet may further include a mode field, and the mode field may include a first mode indicating that the foreign object detection status data packet includes a reference inductance value.

[0053] In another embodiment, the foreign object detection status data packet may further include a mode field, and the mode field may include a second mode indicating that the foreign object detection status data packet includes a reference inductance value and a reference quality factor value.

[0054] In addition, the determined thresholds may include a quality factor threshold and an inductance threshold, and the quality factor threshold and the inductance threshold may include values ​​that are respectively smaller than a predetermined percentage of a reference quality factor value and a reference inductance value.

[0055] In addition, the determined threshold may include a value that is a predetermined proportion larger than the reference inductance value.

[0056] Additionally, the method may include receiving a received power strength data packet from a wireless power receiver for power correction, wherein the received power strength data packet may include the received power of a wireless power receiver corresponding to a light load or the received power of a wireless power receiver corresponding to a load connection state.

[0057] In addition, determining the presence of foreign objects may include a first foreign object determination step and a second foreign object determination step. The first foreign object determination step is to compare the measured quality factor value with the quality factor threshold to determine whether foreign objects are present. The second foreign object determination step is to compare the measured first inductance value with the inductance threshold to determine whether foreign objects are present.

[0058] In addition, if the presence of a foreign object is determined in at least one of the first foreign object determination step and the second foreign object determination step, the presence of a foreign object can be finally determined.

[0059] According to another embodiment, an apparatus for detecting foreign objects includes: a resonant circuit including a resonant capacitor and a resonant inductor; a measuring unit configured to measure a first inductance value of the resonant circuit and a charging region disposed above the inductor; and a controller configured to determine a threshold for detecting foreign objects based on a foreign object detection status data packet received from a wireless power receiver, and to compare the measured first inductance value with the determined threshold to determine whether a foreign object is present.

[0060] Additionally, the controller can be configured to detect objects located in the charging area, and the measured first inductance value can include the inductance value of the resonant circuit as a result of the detected object.

[0061] Additionally, the measurement unit can be configured to measure the quality factor of the resonant circuit, and the measured quality factor may include the quality factor of the resonant circuit as a result of changes in the quality factor of the detected object.

[0062] In addition, the inductance value of a resonant circuit can include the inductance value of the inductor.

[0063] Additionally, when the measured first inductance value is greater than a determined threshold, the controller can correct the power sent to the wireless power receiver.

[0064] Additionally, when the measured first inductance value is equal to or less than a defined threshold, the controller can execute control to stop the transmission of power to the wireless power receiver.

[0065] In addition, the foreign object detection status data packet may include at least one of a reference quality factor and a reference inductance value.

[0066] In one implementation, the foreign object detection status data packet may further include a mode field, and the mode field may include a first mode indicating that the foreign object detection status data packet includes a reference inductance value.

[0067] In another embodiment, the foreign object detection status data packet may further include a mode field, and the mode field may include a second mode indicating that the foreign object detection status data packet includes a reference inductance value and a reference quality factor value.

[0068] In addition, the determined thresholds may include a quality factor threshold and an inductance threshold, and the quality factor threshold and the inductance threshold may include values ​​that are respectively smaller than a predetermined percentage of a reference quality factor value and a reference inductance value.

[0069] In addition, the determined threshold may include a value that is a predetermined proportion larger than the reference inductance value.

[0070] In addition, the controller can perform a first foreign object determination and a second foreign object determination. The first foreign object determination compares the measured quality factor value with the quality factor threshold to determine whether a foreign object exists. The second foreign object determination compares the measured inductance value with the inductance threshold to determine whether a foreign object exists.

[0071] In addition, if the presence of a foreign object is determined in at least one of the first foreign object determination and the second foreign object determination, the controller can ultimately determine that a foreign object is present.

[0072] Additionally, the device may include: a DC-to-DC converter configured to convert DC power from a power source into specific DC power; and an inverter configured to convert the converted DC power into AC power. When the measurement by the measurement unit terminates, the controller can control the DC-to-DC converter and the inverter to periodically send digital pings for identifying the wireless power receiver, and can identify the wireless power receiver upon receiving a signal strength indicator corresponding to the digital ping.

[0073] In addition, the measuring unit can measure the first inductance value based on at least one of the voltage, current and impedance measured across the resonant capacitor.

[0074] Additionally, the measurement unit may include: a quality factor measurement unit configured to calculate a quality factor value based on the voltage measured across the resonant capacitor; and an inductance measurement unit configured to calculate an inductance value based on the voltage and current measured across the inductor.

[0075] According to another embodiment, a method for detecting foreign objects in a wireless power transmitter includes: measuring a first quality factor value at a first frequency; measuring a second quality factor value at a second frequency; and determining whether a foreign object is present based on the first quality factor value and the second quality factor value.

[0076] For example, the second frequency is greater than the first frequency. When the second quality factor is greater than the first quality factor, it can be determined that a foreign object is present.

[0077] In another example, when the second quality factor is greater than the first quality factor, it can be determined that there is an misaligned wireless power receiver.

[0078] Additionally, the method may also include wirelessly transmitting power based on the presence / absence of a foreign object, and the presence / absence of a foreign object may include both the presence and absence of the foreign object.

[0079] In addition, the presence of foreign matter can include a state in which the second quality factor is greater than the first quality factor.

[0080] In addition, the absence of foreign matter can include a state in which the second quality factor is less than or equal to the first quality factor.

[0081] In addition, the method may also include outputting a predetermined alarm signal when it is determined that a foreign object is present in the charging area.

[0082] In addition, the method may also include temporarily stopping power transmission when a foreign object is detected during power transmission.

[0083] In addition, the method includes checking whether detected foreign objects have been removed from the charging area while power transmission is temporarily suspended. Power transmission can be resumed once it is confirmed that the detected foreign objects have been removed.

[0084] In addition, the method may also include entering a selection phase after the output alarm signal.

[0085] In addition, the method checks whether the detected foreign object has been removed from the charging area after outputting the alarm signal and before entering the selection phase. The method can enter the selection phase once it is confirmed that the detected foreign object has been removed.

[0086] Furthermore, if the value obtained by subtracting the first quality factor from the second quality factor exceeds a predetermined reference value, it can be determined that there is a foreign object in the charging area.

[0087] According to another embodiment, a method for detecting foreign objects in a wireless power transmitter includes: calculating a first average quality factor corresponding to a predetermined upper limit frequency band in the operating frequency band; calculating a second average quality factor corresponding to a predetermined lower limit frequency band in the operating frequency band; and determining whether a foreign object exists in the charging area of ​​the wireless power transmitter based on the first average quality factor and the second average quality factor.

[0088] For example, if the average value of the first quality factor is greater than the average value of the second quality factor, it can be determined that there is a foreign object in the charging area.

[0089] In another example, when the value obtained by subtracting the average of the second quality factors from the average of the first quality factors exceeds a predetermined reference value, it can be determined that there is a foreign object in the charging area.

[0090] According to another embodiment, a foreign object detection device disposed in a wireless power transmitter includes: a quality factor measurement unit configured to measure a first quality factor value at a first frequency in a predetermined operating frequency band and a second quality factor value at a second frequency in the operating frequency band; and a detector configured to determine whether a foreign object exists in the charging area based on the first quality factor value and the second quality factor value.

[0091] For example, when the second frequency is greater than the first frequency and the second quality factor is greater than the first quality factor, the detector can determine that there is a foreign object in the charging area.

[0092] In another example, when the second frequency is greater than the first frequency and the second quality factor is greater than the first quality factor, the detector can determine that there is an misaligned wireless power receiver in the charging area.

[0093] The foreign object detection device may also include an alarm unit configured to output an alarm signal when a foreign object is detected in the charging area.

[0094] The foreign object detection device may also include a controller configured to temporarily stop power transmission when a foreign object is detected in the charging area during power transmission.

[0095] In addition, the controller can check whether foreign objects have been removed from the charging area when power transmission is temporarily stopped, and resume the temporarily stopped power transmission when it is detected that foreign objects have been removed.

[0096] The controller can perform control to check whether foreign objects have been removed from the charging area after outputting an alarm signal and before entering the selection phase, and enter the selection phase when it is found that foreign objects have been removed.

[0097] Additionally, the controller can perform control to check whether the detected foreign object has been removed from the charging area after outputting an alarm signal and before entering the selection phase, and enter the selection phase when the foreign object has been detected to have been removed.

[0098] In addition, when the second frequency is greater than the first frequency and the value obtained by subtracting the first quality factor from the second quality factor exceeds a predetermined reference value, the detector can determine that there is a foreign object in the charging area.

[0099] According to another embodiment, a foreign object detection device disposed in a wireless power transmitter includes: a quality factor measurement unit configured to measure quality factor values ​​in a predetermined operating frequency band; an average value calculator configured to calculate a first quality factor average value based on at least one quality factor value measured at a predetermined upper frequency band in the operating frequency band, and to calculate a second quality factor average value based on at least one quality factor value measured at a predetermined lower frequency band in the operating frequency band; and a detector configured to determine whether a foreign object exists in the charging area of ​​the wireless power transmitter based on the first quality factor average value and the second quality factor average value.

[0100] For example, when the average value of the first quality factor is greater than the average value of the second quality factor, the detector can determine that there is a foreign object in the charging area.

[0101] In another example, when the value obtained by subtracting the average of the second quality factors from the average of the first quality factors exceeds a predetermined reference value, the detector can determine that there is an misaligned wireless power receiver in the charging area.

[0102] In another embodiment, a computer-readable recording medium may be provided having a program recorded thereon for performing any of the methods described above.

[0103] In another embodiment, a method for communicating with a wireless power transmitter is provided, the method comprising: receiving a power signal of predetermined strength from the wireless power transmitter by a wireless power receiver; transmitting a data packet including a mode bit field to the wireless power transmitter via the wireless power receiver, the mode bit field indicating whether the data packet includes a reference peak frequency of the wireless power receiver, wherein the reference peak frequency is pre-assigned to the wireless power receiver; and receiving a response from the wireless power transmitter via the wireless power receiver indicating the presence or absence of foreign objects in a charging area, wherein the response is determined based on a comparison of a measured peak frequency of the power signal with an adaptive threshold frequency adjusted based on the reference peak frequency.

[0104] In another embodiment, a wireless power receiver for communicating with a wireless power transmitter is provided. The wireless power receiver includes: a controller configured to: receive a power signal having a predetermined strength from the wireless power transmitter; transmit a data packet to the wireless power transmitter including a mode bit field, the mode bit field indicating whether the data packet includes a reference peak frequency of the wireless power receiver, wherein the reference peak frequency is pre-assigned to the wireless power receiver; and receive a response from the wireless power transmitter indicating the presence or absence of foreign objects in a charging area, wherein the response is determined based on a comparison of a measured peak frequency of the power signal with an adaptive threshold frequency adjusted based on the reference peak frequency.

[0105] The various aspects of this disclosure are only a part of the preferred embodiments of this disclosure, and based on the detailed description of this disclosure, those skilled in the art can design and understand various embodiments based on the technical features of this disclosure.

[0106] [Beneficial Effects]

[0107] The effects of the methods, apparatus, and systems implemented according to the embodiments are as follows.

[0108] The embodiments provide a method, apparatus and system for detecting foreign objects for wireless charging.

[0109] The embodiments provide a method, apparatus and system for detecting foreign objects that can more accurately detect foreign objects.

[0110] The implementation method can minimize unnecessary power waste and heat generation caused by foreign objects.

[0111] One embodiment provides a wireless power transmission device that can more accurately detect foreign objects by applying weights that are linearly or exponentially determined based on a reference quality factor and dynamically determining a threshold or threshold range for detecting foreign objects.

[0112] One implementation provides a wireless power transmission device capable of detecting foreign objects based on the quality factor and inductance value of a resonant circuit measured prior to the ping phase.

[0113] The implementation provides a method, apparatus, and system for detecting foreign objects. The method can more accurately detect foreign objects by measuring the quality factor and inductance of a resonant circuit before the ping phase when an object is detected in the charging region, and comparing the measured values ​​with a threshold determined based on FOD status data packets during the negotiation phase.

[0114] The embodiments provide a method, apparatus and system for detecting foreign objects, which can more accurately detect foreign objects by determining a threshold for dynamically determining the presence of foreign objects based on the receiver type.

[0115] One implementation provides a wireless power transmitter capable of detecting foreign objects based on a quality factor measured at a specific frequency in the operating band.

[0116] One implementation provides a wireless power transmitter capable of detecting foreign objects based on an average quality factor measured at a specific frequency in the operating band.

[0117] The implementation method can minimize foreign object detection errors, thereby minimizing unnecessary power waste and equipment damage.

[0118] The effects of this disclosure are not limited to those described above, and those skilled in the art can obtain other effects not described herein based on the following description of embodiments of this disclosure. In other words, those skilled in the art can obtain effects not anticipated by this disclosure based on embodiments of this disclosure. Attached Figure Description

[0119] Figure 1 This is a block diagram illustrating a wireless charging system according to an embodiment;

[0120] Figure 2 This is a state transition diagram illustrating a wireless transmission process according to another embodiment;

[0121] Figure 3 This is a block diagram illustrating the structure of a wireless power receiver that interacts with a wireless power transmitter according to an embodiment;

[0122] Figure 4 This is a diagram illustrating the data packet format according to an implementation method;

[0123] Figure 5 This is a view showing the types of data packets according to the implementation method;

[0124] Figure 6a This is a block diagram showing the structure of the foreign object detection device according to an embodiment;

[0125] Figure 6b This is a block diagram illustrating the structure of a foreign object detection device according to another embodiment;

[0126] Figure 7a This is a view showing the structure of a foreign object detection (FOD) status data packet message according to an embodiment;

[0127] Figure 7b This is a view showing the structure of a FOD status data packet message according to an embodiment;

[0128] Figure 7c This is a view showing the structure of a FOD status data packet message according to another embodiment;

[0129] Figure 8a This is a diagram illustrating the state transition process of foreign object detection in a foreign object detection device according to an embodiment;

[0130] Figure 8b This is a diagram illustrating the state transition process of foreign object detection in a foreign object detection device according to an embodiment;

[0131] Figure 9a A flowchart illustrating a foreign object detection method in a wireless power transmission device according to another embodiment is shown;

[0132] Figure 9b A flowchart illustrating a foreign object detection method in a wireless power transmission device according to another embodiment is shown;

[0133] Figure 10 and Figure 11 It is a graph showing the experimental results of the degree of quality factor reduction when a foreign object is placed in the charging area according to the embodiment, compared with the reference quality factor of each type of receiver.

[0134] Figure 12 This is a view showing the results of measuring the quality factor and inductance values ​​of the resonant circuit for each type of receiver based on the presence / absence of foreign objects;

[0135] Figure 13a This is a view showing the structure of a FOD status data packet message according to another embodiment;

[0136] Figure 13b This is a view showing the structure of a FOD status data packet message according to another embodiment;

[0137] Figure 13cThis is a view showing the structure of a FOD status data packet message according to another embodiment;

[0138] Figure 13d to Figure 13g This is a view showing the structure of a FOD status data packet message according to an embodiment;

[0139] Figure 14 This is a flowchart illustrating a FOD method according to another embodiment;

[0140] Figure 15 This is a flowchart illustrating a FOD method according to another embodiment;

[0141] Figure 16 It is a quality factor table based on the implementation method;

[0142] Figure 17 This is a block diagram showing the configuration of the FO detection device according to an embodiment;

[0143] Figure 18 This is a flowchart illustrating a FOD method according to another embodiment;

[0144] Figure 19 This is a flowchart illustrating a FOD method according to another embodiment;

[0145] Figure 20 This is a flowchart illustrating a FOD method based on a quality factor value according to another embodiment;

[0146] Figure 21 It is shown that... Figure 20 A block diagram of the structure of the FOD device corresponding to the implementation method;

[0147] Figure 22 This is a flowchart illustrating a FOD method based on a quality factor value according to another embodiment;

[0148] Figure 23 It is shown that... Figure 22 A block diagram of the structure of the FOD device corresponding to the implementation method;

[0149] Figure 24a to Figure 24e It is shown Figure 14 to Figure 23 The experimental results are presented as a graph illustrating the logical basis of the implementation method.

[0150] Figure 25 This is a view showing the relationship between the quality factor value and the peak frequency of the maximum quality factor, depending on the location of the foreign object and the wireless power receiver in the charging area of ​​the wireless power transmitter.

[0151] Figure 26 This is a view illustrating the state transition process for detecting foreign objects in a foreign object detection device according to an embodiment;

[0152] Figure 27 This is a view showing the structure of a FOD status data packet message according to another embodiment;

[0153] Figure 28 This is a view illustrating the state transition process for detecting foreign objects in a foreign object detection device according to an embodiment;

[0154] Figure 29 This is a view illustrating the state transition process for detecting foreign objects in a foreign object detection device according to an embodiment; and

[0155] Figure 30 This is a view showing the structure of a FOD status data packet message according to another embodiment.

[0156] [Best Implementation Method]

[0157] A method for detecting foreign objects in a wireless power transmitter including a resonant circuit for wirelessly transmitting power includes: detecting an object placed in a charging area; measuring a quality factor of the resonant circuit when the object is detected; transmitting a sensing signal to identify a wireless power receiver; determining a threshold for detecting foreign objects based on a reference quality factor received from the identified wireless power receiver; and comparing the measured quality factor with the determined threshold to determine the presence of a foreign object, wherein the threshold is determined by applying a weight that is increased according to the reference quality factor. Detailed Implementation

[0158] In the following, the apparatus and various methods according to embodiments will be described in detail with reference to the accompanying drawings. Generally, suffixes such as “module” or “unit” can be used to refer to elements or components. The use of such suffixes herein is merely for the convenience of description, and the suffixes themselves are not intended to have any particular meaning or function.

[0159] In the following description of the embodiments, it will be understood that when each element is referred to as being formed "above" or "below" another element, it may be formed directly "above" or "below" another element or between them, with one or more intermediate elements grounded. Additionally, it will be understood that "above" or "below" an element can indicate the upward and downward directions of the element.

[0160] In the description of the embodiments, for ease of description, the device having the function of transmitting wireless power in a wireless charging system can be used interchangeably with wireless power transmitters, wireless power transmission devices, wireless power transmission devices, wireless power transmitters, transmission terminals, transmitters, transmission devices, transmission sides, wireless power transmission devices, wireless power transmitters, etc. The device having the function of receiving wireless power from a wireless power transmission device can be used interchangeably with wireless power receiving devices, wireless power receivers, wireless power receiving devices, wireless power receivers, receiving terminals, receiving sides, receiving devices, receivers, etc.

[0161] The transmitter according to the embodiment can be configured in the form of pads, brackets, access points (APs), small base stations, brackets, ceiling-mounted structures, or wall-mounted structures. One transmitter can transmit power to multiple wireless power receiving devices. For this purpose, the transmitter may include at least one wireless power transmission device. Here, the wireless power transmission device can use various wireless power transmission standards based on electromagnetic induction methods that perform charging using the principle of electromagnetic induction. In the principle of electromagnetic induction, a magnetic field is generated in the coil at the power transmission end, and power is induced in the coil at the receiving end through the magnetic field. Here, the wireless power transmission device may include wireless charging technologies using electromagnetic induction methods as defined in the Wireless Power Consortium (WPC) and the Power Matters Alliance (PMA), which are wireless charging technology organizations.

[0162] Additionally, the receiver according to the embodiment may include at least one wireless power receiving device and may simultaneously receive wireless power from two or more transmitters. Here, the wireless power receiving device may include wireless charging technology using electromagnetic induction methods as defined in the Wireless Power Consortium (WPC) and the Power Matters Association (PMA), which are wireless charging technology organizations.

[0163] The receiver according to the embodiments can be used in small electronic devices (e.g., mobile phones, smartphones, laptops, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation systems, MP3 players, electric toothbrushes, electronic tags, lighting devices, remote controllers, fishing floats, wearable devices such as smartwatches, etc.), but is not limited thereto, and can be used in any device including a wireless power receiving device that charges a battery according to the embodiments.

[0164] Figure 1 This is a block diagram illustrating a wireless charging system according to an embodiment.

[0165] Reference Figure 1A wireless charging system generally includes: a wireless power transmission terminal 10 for wirelessly transmitting power, a wireless power receiving terminal 20 for receiving the transmitted power, and an electronic device 30 for receiving the received power.

[0166] For example, the wireless power transmitter 10 and the wireless power receiver 20 can perform in-band communication, in which information is exchanged using the same frequency band as the operating frequency used for wireless power transmission.

[0167] In in-band communication, when the wireless power receiver 20 receives the power signal 41 transmitted by the wireless power transmitter 10, the wireless power receiver 20 can modulate the received power signal and transmit the modulated signal 42 to the wireless power transmitter 10.

[0168] In another example, the wireless power transmitter 10 and the wireless power receiver 20 can perform out-of-band communication, in which information is exchanged using a frequency band different from the operating frequency used for wireless power transmission.

[0169] For example, the information exchanged between the wireless power transmitter 10 and the wireless power receiver 20 may include each other's status information and control information. Here, the status information and control information exchanged between the transmitter and receiver will become more apparent from the following description of the implementation.

[0170] In-band and out-of-band communication can provide bidirectional communication, but the implementation is not limited to this. In another implementation, in-band and out-of-band communication can provide unidirectional or half-duplex communication.

[0171] For example, one-way communication may, but is not limited to, represent the transmission of information from the wireless power receiver 20 to the wireless power transmitter 10 or the transmission from the wireless power transmitter 10 to the wireless power receiver 20.

[0172] The half-duplex communication method is characterized by the fact that bidirectional communication between the wireless power receiver 20 and the wireless power transmitter 10 is enabled, but only one device can send information at a specific point in time.

[0173] The wireless power receiver 20 according to the embodiment can acquire various status information of the electronic device 30. For example, the status information of the electronic device 30 may include, but is not limited to, current power usage information, information for identifying the executed application, CPU usage information, battery charging status information, battery output voltage / current information, etc., and may include information that can be acquired from the electronic device 30 and used for wireless power control.

[0174] Specifically, the wireless power transmitter 10 according to the embodiment can send a predetermined data packet to the wireless power receiver 20 indicating whether fast charging is supported. When it is determined that the wireless power transmitter 10 supports fast charging mode, the wireless power receiver 20 can notify the electronic device 30 that the wireless power transmitter 10 supports fast charging mode. The electronic device 30 can display information indicating that fast charging is possible via a predetermined display device (e.g., a liquid crystal display).

[0175] Additionally, the user of the electronic device 30 can select a predetermined fast charging request button displayed on the liquid crystal display and control the wireless power transmission terminal 10 to operate in fast charging mode. In this case, when the user selects the fast charging request button, the electronic device 30 can send a predetermined fast charging request signal to the wireless power receiver 20. The wireless power receiver 20 can generate and send a charging mode data packet corresponding to the received fast charging request signal to the wireless power transmission terminal 10, thereby switching the normal low-power charging mode to fast charging mode.

[0176] Figure 2 This is a state transition diagram illustrating a wireless transmission process according to another embodiment.

[0177] Reference Figure 2 The power transfer from transmitter to receiver can be broadly divided into: selection phase 210, ping phase 220, identification and configuration phase 230, negotiation phase 240, calibration phase 250, power transfer phase 260, and renegotiation phase 270.

[0178] Selection phase 210 can transition at the start of power transmission or upon detection of a specific error or event while power transmission is being maintained. As described below, the specific error or event will become apparent. Additionally, in selection phase 210, the transmitter can monitor the presence of an object on the interface surface. Upon detection of an object on the interface surface, the transmitter can transition to ping step 220. In selection phase 210, the transmitter sends an analog ping signal with a very short pulse and detects the presence of an object in the effective area of ​​the interface surface based on current changes in the transmission coil or primary coil.

[0179] In ping step 220, upon detecting an object, the transmitter activates the receiver and sends a digital ping to identify whether the receiver is compliant with the WPC standard. In ping step 220, if no response signal to the digital ping (e.g., a signal strength packet) is received from the receiver, the transmitter may switch back to selection phase 210. Additionally, in ping phase 220, if a signal indicating that power delivery has been terminated (i.e., a charging termination packet) is received from the receiver, the transmitter may switch back to selection phase 210.

[0180] If the ping phase 220 terminates, the transmitter can transition to the identification and configuration phase 230 to identify the receiver and collect the receiver's configuration and status information.

[0181] In the identification and configuration phase 230, the transmitter may switch to the selection phase 210 in the event of receiving an unexpected data packet, not receiving the expected data packet within a predetermined time period (timeout), when a data packet transmission error occurs, or when a power transmission protocol is not established (no power transmission protocol).

[0182] The transmitter can determine whether it needs to enter the negotiation phase 240 based on the negotiation field value of the configuration packet received in the identification and configuration phase 230.

[0183] When it is determined that negotiation is required, the transmitter can enter negotiation phase 240 to perform a pre-defined FOD procedure.

[0184] Conversely, when it is determined that no negotiation is required, the transmitter can immediately switch to the power transmission phase 260.

[0185] During negotiation phase 240, the transmitter may receive a Foreign Object Detection (FOD) status data packet including a reference quality factor value. At this time, the transmitter may determine a threshold for FO detection based on the reference quality factor value. For example, the transmitter may use a predetermined threshold generation function that utilizes the reference quality factor value as a parameter to determine a threshold or threshold range for determining the presence of a foreign object. Here, the threshold or threshold range calculated by the threshold generation function is less than the reference quality factor value. The threshold FO_Threshold for detecting foreign objects according to the implementation embodiment may be determined based on the reference quality factor value RQF_Value, a predetermined design factor corresponding to the wireless power transmitter, tolerances defined in the standard, and weights. Here, the weights may increase linearly or exponentially based on the reference quality factor value. That is, the threshold for detecting foreign objects may be determined by Equation 1:

[0186] FO_Threshold = (RQF_Value * Design_factor) + Tolerance – Weight (Equation 1)

[0187] Typically, if a foreign object is placed in the charging area, the quality factor measured in the transmitter's resonant circuit decreases compared to the absence of a foreign object. If a foreign object is placed in the charging area of ​​an actual wireless charging system, the rate of decrease in the measured quality factor relative to a reference quality factor varies depending on the type of receiver placed in the charging area, i.e., the reference quality factor of the wireless power receiver. Specifically, the rate of decrease in the quality factor due to the placement of a foreign object increases rapidly with the increase of the reference quality factor. Therefore, the transmitter according to the invention can determine a threshold (or threshold range) such that the ratio of the threshold for detecting foreign objects to the reference quality factor decreases as the reference quality factor of the wireless power receiver increases. As a result, the possibility of the transmitter failing to detect foreign objects can be reduced.

[0188] The transmitter can compare a quality factor value measured after an object is detected with a threshold determined for FO detection to determine whether an FO is present in the charging area, and control power transmission based on the FO detection result. For example, when an FO is detected, the transmitter can stop power transmission and output a predetermined warning alarm indicating that an FO has been detected.

[0189] When an FO is detected, the transmitter can return to selection phase 210. Conversely, when an FO is not detected, the transmitter can transition to power transmission phase 260 via calibration phase 250. Specifically, when an FO is not detected, the transmitter can measure power losses at both the receiving and transmitting ends to determine the strength of the power received at the receiving end and the strength of the power transmitted at the transmitting end in calibration phase 250. That is, in calibration phase 250, the transmitter can predict power losses based on the difference between the transmitted power at the transmitting end and the received power at the receiving end. According to one embodiment, the transmitter can use the predicted power losses to calibrate a threshold for FOD.

[0190] In the power delivery phase 260, if an unexpected data packet is received, or if the expected data packet is not received within the predetermined time period (timeout), or if a power delivery violation occurs or charging is terminated, the transmitter may switch to the selection phase 210.

[0191] Additionally, during power transmission phase 260, if it is necessary to reconfigure the power transmission protocol based on changes in the transmitter's state, the transmitter can transition to renegotiation phase 270. At this point, when the renegotiation terminates normally, the transmitter can return to power transmission phase 260.

[0192] Power transmission protocols can be configured based on transmitter and receiver status information and characteristic information. For example, transmitter status information may include information about the maximum transmittable power, the maximum number of receivers that can receive power, and receiver status information may include information about the required power.

[0193] Figure 3 This is a block diagram illustrating the structure of a wireless power receiver that interacts with a wireless power transmitter.

[0194] Reference Figure 3 The wireless power receiver 300 may include at least one of a receiving coil 310, a rectifier 320, a DC-DC converter 330, a load 340, a sensing unit 350, a communication unit 360, and a main controller 370. The communication unit 360 may include a demodulator 361 and a modulator 362.

[0195] Despite Figure 3 The wireless power receiver 300 shown in the example is shown exchanging information with the wireless power transmitter 600 via in-band communication, but this is only an example, and the communication unit 360 according to another embodiment can provide short-range two-way communication via a frequency band different from the frequency band used to transmit wireless power signals.

[0196] The AC power received by the receiving coil 310 can be sent to the rectifier 320. The rectifier 320 can convert the AC power into DC power and send the DC power to the DC-to-DC converter 330. The DC-to-DC converter 330 can convert the intensity of the DC power output from the rectifier into the specific intensity required by the load 340 and send the converted power to the load 340.

[0197] The sensing unit 350 can measure the intensity of the DC power output from the rectifier 320 and provide this intensity to the main controller 370. Additionally, the sensing unit 350 can measure the intensity of the current applied to the receiving coil 310 based on wireless power reception and send the measurement result to the main controller 370. Furthermore, the sensing unit 350 can measure the internal temperature of the wireless power receiver 300 and provide the measured temperature value to the main controller 370.

[0198] For example, the main controller 370 can compare the intensity of the DC power output from the rectifier with a predetermined reference value and determine whether an overvoltage has occurred. Upon determining that an overvoltage has occurred, a predetermined data packet indicating that an overvoltage has occurred can be generated and sent to the modulator 362. The signal modulated by the modulation unit 362 can be sent to the wireless power transmitter 600 via the receiving coil 310 or a separate coil (not shown). If the intensity of the DC power output from the rectifier is equal to or greater than the predetermined reference value, the main controller 370 can determine that a sensing signal has been received, and upon receiving the sensing signal, executes control to send a signal strength indicator corresponding to the sensing signal to the wireless power transmitter 600 via the modulator 362. In another example, the demodulator 361 can demodulate the AC power signal between the receiving coil 310 and the rectifier 320 or the DC power signal output from the rectifier 320, identify whether a sensing signal has been received, and provide the identification result to the main controller 370. In this case, the main controller 370 can execute control to send a signal strength indicator corresponding to the sensing signal via the modulator 362.

[0199] Figure 4 This is a view showing the data packet format according to the implementation method.

[0200] Reference Figure 4 The data packet format 400 for information exchange between the wireless power transmitter 10 and the wireless power receiver 20 may include: a preamble 410 field for obtaining synchronization for demodulating the corresponding data packet and identifying the accurate start bit of the corresponding data packet; a header 420 field for identifying the type of message included in the corresponding data packet; a message 430 field for sending the content (or payload) of the corresponding data packet; and a checksum 440 field for identifying whether an error has occurred in the corresponding data packet.

[0201] The data packet receiver can identify the size of the message 430 included in the corresponding data packet based on the value of the header 420.

[0202] Furthermore, header 420 can be defined for each step of the wireless power transmission process, and the value of header 420 can be defined as the same in different stages of the wireless power transmission process. For example, refer to Figure 10 It should be noted that the header value corresponding to the end of power transmission in the ping phase and the end of power transmission in the power transmission phase is 0x02.

[0203] Message 430 includes data to be sent by the transmitting end of the corresponding data packet. For example, the data included in the fields of Message 430 can be a report, request, or response, but is not limited to these.

[0204] According to another embodiment, the data packet 400 may further include at least one of transmitter identification information for identifying the transmitter for sending the corresponding data packet and receiver identification information for identifying the receiver for receiving the corresponding data packet. The transmitter identification information and receiver identification information may include IP address information, MAC address information, product identification information, etc. However, this disclosure is not limited to this and may include information for distinguishing between the receiver and transmitter in a wireless charging system.

[0205] If the corresponding data packet is received by multiple devices, the data packet 400 according to another embodiment may also include predetermined group identification information for identifying the receiving group.

[0206] Figure 5 This is a view showing the types of data packets sent from a wireless power receiver to a wireless power transmitter according to an embodiment.

[0207] Reference Figure 5 The data packets sent from the wireless power receiver to the wireless power transmitter may include: a signal strength data packet for transmitting the strength information of the sensed ping signal; a power delivery type (end power delivery) for requesting the termination of power delivery from the transmitter; a power control delay data packet for transmitting information about the time wait before actual power is controlled after receiving a control error data packet for control; a configuration data packet for transmitting receiver configuration information; an identification data packet and an extended identification data packet for transmitting receiver identification information; a general request data packet for transmitting a general request message; a specific request data packet for transmitting a specific request message; a FOD status data packet for transmitting a reference quality factor value for FO detection; a control error data packet for controlling the power transmitted by the transmitter; a renegotiation data packet for initiating renegotiation; a 24-bit received power data packet for transmitting the strength information of the received power; and a charging status data packet for transmitting the current charging status information of the load.

[0208] In-band communication can be used to send data packets from a wireless power receiver to a wireless power transmitter. In-band communication uses the same frequency band as the frequency band used for transmitting wireless power.

[0209] Figure 6a This is a block diagram showing the structure of a foreign object detection device according to an embodiment.

[0210] Reference Figure 6aThe foreign object detection device 600 may include a power supply device 601, a DC-DC converter 610, an inverter 620, a resonant circuit 630, a measurement unit 640, a communication unit 660, a sensing unit 670, and a controller 680. The foreign object detection device 600 may be installed in a wireless power transmission device.

[0211] The resonant circuit 630 may include a resonant capacitor 631 and a resonant inductor 632, and the communication unit 660 may include at least one of a demodulator 661 and a modulator 662.

[0212] The power supply device 601 can receive DC power through an external power terminal and send the DC power to the DC to DC converter 610.

[0213] The DC-to-DC converter 610 can, under the control of the controller 680, convert the intensity of DC power received from the power supply device 601 into a specific intensity of DC power. For example, the DC-to-DC converter 610 may include, but is not limited to, a variable voltage generator capable of adjusting the voltage intensity.

[0214] Inverter 620 can convert DC power into AC power. Inverter 620 can convert input DC power signals controlled by multiple switches into AC power signals and output AC power signals.

[0215] For example, inverter 620 may include a full-bridge circuit. However, this disclosure is not limited thereto, and the inverter may include a half-bridge circuit.

[0216] In another example, inverter 620 may include a half-bridge circuit and a full-bridge circuit. In this case, controller 680 can dynamically determine whether inverter 620 operates as a half-bridge or as a full-bridge.

[0217] According to one embodiment, the wireless power transmission device adaptively controls the bridging mode of the inverter 620 based on the power intensity required by the wireless power receiving device. Here, the bridging mode includes a half-bridge mode and a full-bridge mode.

[0218] For example, if the wireless power receiving device requires a low power of 5W, the controller 680 can control the inverter 620 to drive in half-bridge mode. In contrast, if the wireless power receiving device requires a high power of 15W, the controller 680 can control the inverter to drive in full-bridge mode.

[0219] In another example, the wireless power transmission device can adaptively determine the bridging mode based on the sensed temperature and drive the inverter 620 in the determined bridging mode. For example, if the temperature of the wireless power transmission device exceeds a predetermined reference value when transmitting wireless power using half-bridge mode, the controller 680 can perform control to deactivate the half-bridge mode and activate the full-bridge mode. That is, the wireless power transmission device can maintain its internal temperature at or below the reference value by increasing the voltage and decreasing the current flowing in the resonant circuit 630 through the full-bridge circuit while transmitting the same amount of power.

[0220] Typically, the heat generated in electronic components installed in electronic devices may be more sensitive to the intensity of the current than to the intensity of the voltage applied to the electronic components.

[0221] In addition, the inverter 620 can not only convert DC power to AC power, but also change the intensity of AC power.

[0222] For example, inverter 620 can adjust the strength of the output AC power under the control of controller 680 by adjusting the frequency of the reference AC signal used to generate AC power. To this end, inverter 620 may include a frequency oscillator for generating the reference AC signal with a specific frequency. However, this is merely an example, and the frequency oscillator may be mounted independently of inverter 620 and on one side of foreign object detection device 600.

[0223] In another example, the foreign object detection device 600 may further include a gate driver (not shown) for controlling a switch disposed in the inverter 620. In this case, the gate driver may receive at least one pulse width modulation (PWM) signal from the controller 680 and control the switching of the inverter 620 according to the received PWM signal. The controller 680 may control the duty cycle (i.e., duty rate) and phase of the PWM signal to control the intensity of the output power of the inverter 620. The controller 680 may adaptively control the duty cycle and phase of the PWM signal based on a feedback signal received from a wireless power receiving device.

[0224] Measurement unit 640 can measure at least one of the voltage, current, and impedance across resonant capacitor 631 according to control signals from controller 680, to calculate the quality factor and / or inductance value of resonant circuit 630. The calculated quality factor and / or inductance value can then be sent to controller 680, and controller 680 can temporarily store the quality factor and / or inductance value received from measurement unit 640 in a predetermined recording area. For example, when an object is detected in the charging area during the selection phase, controller 680 can control measurement unit 640 to calculate the quality factor and / or inductance value before entering the ping phase.

[0225] When a FOD status data packet is received from modulator 662 during the negotiation phase, controller 680 can determine a threshold (or threshold range) for determining the presence of a foreign object based on the information included in the FOD status data packet.

[0226] The threshold FO_Threshold for detecting foreign objects, according to the implementation method, can be determined based on a reference quality factor RQF_Value, a predetermined design factor corresponding to the wireless power transmitter, tolerances defined in the standard, and weights. Here, the weights can increase linearly or exponentially based on the reference quality factor. That is, the controller 680 can determine the threshold for detecting foreign objects using Equation 1:

[0227] FO_Threshold = (RQF_Value * Design_factor) + Tolerance – Weight (Equation 1)

[0228] For example, although the weights can be calculated using a predetermined linear function with a reference quality factor as a parameter, the implementation is not limited to this, and the weights can be calculated using a higher-order function (e.g., a second-order function or a higher-order function).

[0229] In another example, predefined weights can be assigned to each type of wireless power receiver, and these weights can be recorded and stored in a predetermined recording area (e.g., non-volatile memory) of the foreign object detection device 600. In this case, the weights for each type of wireless power receiver can be maintained in the form of a mapping table, but are not limited to this.

[0230] According to another embodiment, the threshold range for detecting foreign objects is identified by an upper threshold FO_Theshold_Upper_Limit and a lower threshold FO_Theshold_Lower_Limit, and can be determined based on a reference quality factor value RQF_Value, a predetermined design factor corresponding to the wireless power transmitter, tolerances defined in the standard, upper limit weights, and lower limit weights. Here, the upper limit weights and lower limit weights can increase linearly or exponentially based on the reference quality factor value. That is, the controller 680 can determine the threshold range for detecting foreign objects using Equation 2:

[0231] FO_Threshold_Upper_Limit = (RQF_Value * Design_factor) + Tolerance - Upper Limit Weight

[0232] FO_Threshold_Lower_Limit = (RQF_Value * Design_factor) + Tolerance - Lower Limit Weight (Equation 2)

[0233] If the measured quality factor value is between the upper and lower threshold values, the controller 680 can determine that a foreign object is present.

[0234] According to another embodiment, the threshold FO_Threshold for detecting foreign objects can be determined by applying a difference ratio based on a reference quality factor (RQF) value, as shown in Table 1 below.

[0235] For example, referring to Table 1 below, when the RQF value exceeds 80, a 40% differential ratio is applied. In this case, the threshold FO_Threshold for detecting foreign objects can be calculated as RQF × 0.6 + tolerance.

[0236] In another example, referring to Table 1 below, if the RQF value is greater than or equal to 50 and less than or equal to 60, a 10% differential ratio is applied. In this case, the threshold FO_Threshold for detecting foreign objects can be calculated as RQF × 0.9 + tolerance.

[0237] [Table 1]

[0238] Reference Quality Factor (RQF) Difference Ratio FO_Threshold >80 40％ = RQF x 0.6 + Tolerance 80 ≥ RQF ≥ 70 30％ = RQF x 0.7 + Tolerance 70 ≥ RQF ≥ 60 20％ = RQF x 0.8 + Tolerance 60 ≥ RQF ≥ 50 10％ = RQF x 0.9 + Tolerance 50 ≥ RQF 5％ = RQF x 0.95 + Tolerance

[0239] The wireless power transmitter can receive a reference quality factor value via FOD status packets during the negotiation phase and adaptively determine FO_Threshold based on the received reference quality factor value. As shown in Table 1 above, as the RQF value increases, the difference between the RQF value and FO_Threshold increases according to the difference ratio corresponding to the RQF value. Conversely, as the RQF value decreases, the difference between the RQF value and FO_Threshold decreases according to the difference ratio corresponding to the RQF value. It should be noted that Table 1 above is only an example, and the difference ratio based on the RQF value can be determined differently depending on the design and device configuration of those skilled in the art.

[0240] Typically, if a foreign object is placed in the charging area, the quality factor measured in the transmitter's resonant circuit decreases compared to the case where no foreign object is present. If a foreign object is placed in the charging area of ​​an actual wireless charging system, the rate of decrease in the measured quality factor relative to a reference quality factor can vary depending on the type of receiver placed in the charging area (i.e., the reference quality factor for a wireless power receiver).

[0241] Specifically, as the reference quality factor increases, the rate of decrease in the quality factor due to the presence of foreign objects increases rapidly. Therefore, the controller 680 according to the invention can determine a threshold (or threshold range) such that the ratio of the threshold for detecting foreign objects to the reference quality factor decreases as the reference quality factor of the wireless power receiver increases. As a result, the possibility that the transmitter will fail to detect foreign objects can be reduced.

[0242] The controller 680 can compare the quality factor value measured after an object is detected with the threshold determined for FO detection to determine whether FO is present in the charging area, and control power delivery based on the FO detection result.

[0243] For example, upon detecting a foreign object (FO), the controller 680 may stop power transmission and execute control to output a predetermined warning alarm indicating that a FO has been detected. Here, the warning alarm may be, but is not limited to, at least one of the following outputs in the foreign object detection device: a buzzer, an LED light, a vibrating element, and a liquid crystal display.

[0244] For example, if the quality factor measured after an object is detected in the selection phase but before entering the ping phase is less than a determined threshold, the controller 680 can determine that a foreign object is present in the charging area.

[0245] In another example, if the quality factor measured after an object is detected in the selection phase and before entering the ping phase is within the determined threshold range, the controller 680 can determine that a foreign object is present in the charging area.

[0246] The reference quality factor included in the FOD status data packet can be determined as the minimum of the quality factors calculated corresponding to the wireless power receiver at a specific location on the charging bed of the wireless power transmitter, which is dedicated to standard performance testing.

[0247] Additionally, if a foreign object is detected during the negotiation phase, the controller 680 can return to the selection phase and control the measurement unit 640 to calculate the quality factor of the resonant circuit 630 at a predetermined time period.

[0248] At this time, the controller 680 can compare the quality factor value obtained when the foreign object is detected with a predetermined threshold (or threshold range) to determine whether the detected foreign object has been removed from the charging area.

[0249] For example, if the quality factor measured while a foreign object is detected is greater than a predetermined threshold, the controller 680 can determine that the foreign object has been removed. In another example, if the quality factor measured while a foreign object is detected exceeds an upper limit threshold, the controller 680 can determine that the foreign object has been removed.

[0250] In addition, the controller 680 can adaptively determine the threshold for detecting foreign objects by referring to Table 1 above (referred to as the "threshold determination table" for ease of description).

[0251] Table 1 above can be stored in a predetermined recording area of ​​a memory (not shown) set in the foreign object detection device 600. When a FOD status data packet including a reference quality factor value is received during the negotiation phase, the controller 680 can determine the threshold for detecting foreign objects by referring to the received reference quality factor value and the threshold determination table, and compare the determined threshold with the quality factor value of the predicted quantity to determine whether a foreign object is present.

[0252] Here, the threshold determination table can be updated. For example, the foreign object detection device can connect to a specific server via a wired or wireless network and communicate with the server to update the threshold determination table. In another example, the foreign object detection device can receive or update the threshold determination table from a connected wireless power receiver.

[0253] A threshold determination table can be generated based on the type of wireless power receiver, and the foreign object detection device can determine the threshold for detecting foreign objects by referring to the threshold determination table corresponding to the type of the identified wireless power receiver.

[0254] In the wireless power receiver according to the embodiment, a threshold determination table generated according to the type of wireless power transmitter can be maintained. In this case, the wireless power receiver can send the threshold determination table corresponding to the type of the identified wireless power transmitter to the wireless power transmitter. The wireless power transmitter can determine the threshold for detecting foreign objects based on the received threshold determination table.

[0255] As described above, the foreign object detection device according to the embodiment can adaptively determine the threshold for detecting foreign objects by referring to at least one of the threshold determination tables corresponding to the type of wireless power receiver and the type of wireless power transmitter.

[0256] Once it is determined that the foreign object has been removed, the controller 680 can execute control to re-enter the power transmission phase to resume charging of the wireless power receiving device.

[0257] Additionally, the threshold can include an inductance threshold and a quality factor threshold. If the determined value is a threshold range, the threshold range can include both an inductance threshold range and a quality factor threshold range. Two thresholds can be used to detect foreign objects, or a threshold corresponding to the type of reference value sent by each receiver can be determined to detect foreign objects.

[0258] Here, the FOD status data packet may include at least one of a reference quality factor value and a reference inductance value corresponding to the wireless power receiver. The controller 680 may determine a quality factor threshold and / or an inductance threshold for determining the presence of a foreign object based on the received reference quality factor value and reference inductance value. For example, although the value corresponding to 90% of the reference quality factor value and reference inductance value may be determined as the quality factor threshold and / or inductance threshold, the implementation is not limited thereto, and this ratio may be defined differently according to the design of those skilled in the art.

[0259] For example, if the previously stored quality factor value (measured before the ping phase) is less than the determined quality factor threshold or the pre-stored inductance value is less than the determined inductance threshold, the controller 680 can determine that a foreign object is present.

[0260] The controller 680 can stop power transmission when it detects the presence of a foreign object and execute control to output a predetermined warning alarm indicating that a foreign object has been detected. For example, the alarm unit may include, but is not limited to, a buzzer, an LED light, a vibrating element, an LCD display, etc.

[0261] The reference quality factor value included in the FOD status data packet can be determined as the minimum of the quality factor values ​​calculated corresponding to the wireless power receiver at a specific location on the charging bed of the dedicated wireless power transmitter.

[0262] The inductance value included in the FOD status data packet can be determined as the minimum of the inductance values ​​calculated corresponding to the wireless power receiver at a specific location on the charging bed of the wireless power transmitter, which is dedicated to standard performance testing.

[0263] Additionally, if a foreign object is detected during the negotiation phase, the controller 680 can return to the selection phase and control the measurement unit 640 to calculate the quality factor and inductance value of the resonant circuit 630 within a predetermined time period. At this time, the controller 680 can compare the quality factor and inductance values ​​obtained when the foreign object was detected with predetermined quality factor and inductance thresholds to determine whether the detected foreign object has been removed from the charging area. In another embodiment, when it is determined that the foreign object has been removed, the controller 680 can execute control to enter the power transfer phase and resume charging of the wireless power receiving device. At this time, the controller can enter the power transfer phase without skipping the identification and configuration phase and / or the negotiation phase.

[0264] Demodulator 661 demodulates the in-band signal received from the wireless power receiving device and transmits the demodulated signal to controller 680. For example, demodulator 661 can... Figure 10 The data packets are demodulated, and the demodulated data packets are sent to the controller 680.

[0265] The sensing unit 670 can measure voltage, current, power, impedance, and temperature at specific terminals, components, and locations of the foreign object detection device 600 (or wireless power transmission device).

[0266] For example, the sensing unit 670 can measure the voltage / current of the DC-converted power and provide the measured voltage / current to the controller 680. Additionally, the sensing unit 670 can measure the internal temperature of the wireless power transmission device and provide the measurement result to the controller 680 to determine if overheating has occurred. In this case, the controller 680 can adaptively cut off the power supplied from the power source or the power supplied to the resonant circuit 630 based on the voltage / current value measured by the sensing unit 670. Therefore, a predetermined power cut-off circuit for blocking the power supplied from the power source 601 or the DC power supplied to the inverter 620 can also be provided on one side of the foreign object detection device 600.

[0267] The sensing unit 670 may also include a Hall sensor, a pressure sensor, etc. In this case, the Hall sensor or pressure sensor can detect the presence of an object in the charging area, but is not limited to this.

[0268] When sending an analog ping signal during the selection phase, the sensing unit 670 can detect changes in the current, voltage, or impedance of the resonant circuit 630 to detect the presence of an object in the charging area.

[0269] As described above, when an object is detected in the selection phase, the foreign object detection device 600 according to the embodiment can measure (or calculate) the quality factor of the resonant circuit before entering the ping phase, and compare the measured quality factor with the threshold (or threshold range) determined in the negotiation phase to determine whether a foreign object is present, thereby significantly reducing the possibility of foreign object detection failure.

[0270] The sensing unit can be replaced by a measurement unit, so the sensing unit can be omitted.

[0271] Furthermore, the foreign object detection device 600 according to the embodiment can dynamically determine the threshold (or threshold range) for detecting foreign objects based on a reference quality factor value corresponding to the wireless power receiver, thereby performing foreign object detection optimized for the wireless power receiver.

[0272] for Figure 6b For detailed operation of the remaining components shown, please refer to the documentation. Figure 6a The description.

[0273] Figure 7a This is a view showing the structure of a FOD status data packet message according to an embodiment.

[0274] Reference Figure 7a The FOD status packet message 700 can be 2 bytes long and includes a reserved field 701 with a length of 6 bits, a mode field 702 with a length of 2 bits, and a reference quality factor field 703 with a length of 1 byte. All bits of the reserved field 701 can be set to 0.

[0275] As indicated by reference numeral 704, if the mode field 702 is set to the binary value "00", this can mean that the reference quality factor value measured and determined in the state of powerlessness of the wireless power receiver is recorded in the reference quality factor value field 703.

[0276] Figure 7b This is a view showing the structure of a FOD status data packet message according to an embodiment.

[0277] Reference Figure 7bThe FOD status data packet message 700 may have a length of 2 bytes and includes a first data field 701 with a length of 6 bits, a mode field 702 with a length of 2 bits, and a reference quality factor field 703 with a length of 1 byte.

[0278] As indicated by reference numeral 704, if the mode field 702 is set to the binary value "00", all bits of the configuration first data field 701 are set to 0, and the reference quality factor value measured and determined in the state of the wireless power receiver being powered off is recorded in the reference quality factor value field 703. Conversely, if the mode field 702 is set to the binary value "01", the reference inductance value measured and determined in the state of the wireless power receiver being powered off is recorded in the first data field 701, and the reference quality factor value measured and determined in the state of the wireless power receiver being powered off is recorded in the reference quality factor value field 703.

[0279] In this embodiment, the foreign object detection device (or wireless power transmission device) can acquire at least one of a reference quality factor and a reference inductance value corresponding to the wireless power receiver during the negotiation phase.

[0280] Figure 7c This is a view showing the structure of a FOD status data packet message according to an embodiment.

[0281] Reference Figure 7c The FOD status packet message 700 can be 2 bytes long and includes a reserved field 701 with a length of 6 bits, a mode field 702 with a length of 2 bits, and a reference value field 703 with a length of 1 byte. All bits of the reserved field 701 can be set to 0.

[0282] As indicated by reference numeral 704, if mode field 702 is set to the binary value "00", the reference quality factor value measured and determined with the wireless power receiver powered off is recorded in reference value field 703. Conversely, if mode field 702 is set to the binary value "01", the reference inductance value measured and determined with the wireless power receiver powered off is recorded in reference value field 703.

[0283] In this embodiment, the foreign object detection device (or wireless power transmission device) can acquire at least one of a reference quality factor and a reference inductance value corresponding to the wireless power receiver during the negotiation phase.

[0284] Figure 8a This is a diagram illustrating the state transition process of foreign object detection in a foreign object detection device according to an embodiment.

[0285] Reference Figure 8a When an object is detected in selection phase 810, the foreign object detection device can measure and store the quality factor value of the resonant circuit, and then proceed to ping phase 810. In ping phase 820, the foreign object detection device can periodically send predetermined power signals, such as digital ping, to identify the wireless power receiver.

[0286] When a signal strength indicator corresponding to a digital ping is received in the ping phase 820, the foreign object detection device can enter the identification and configuration phase 830 to identify the wireless power receiver and set various configuration parameters for the identified wireless power receiver.

[0287] If the identification and configuration of the wireless power receiver is terminated, the foreign object detection device can enter negotiation phase 840 to receive a FOD status data packet including a reference quality factor.

[0288] The foreign object detection device can determine a threshold (or threshold range) for determining the presence of a foreign object based on a reference quality factor value included in the FOD status data packet, and compare the stored quality factor value with the determined threshold (or threshold range) to determine whether a foreign object is present in the charging area.

[0289] like Figure 6a As described, in a wireless power receiver with a small reference quality factor, the decrease in quality factor from the reference quality factor and the ratio of the quality factor to the reference quality factor when a foreign object is placed in the charging area are relatively smaller than the decrease and the ratio in a wireless power receiver with a large reference quality factor. Therefore, the foreign object detection device according to the embodiment can adaptively determine a threshold (or threshold range) for detecting foreign objects based on the reference quality factor received from the wireless power receiver.

[0290] If a foreign object is detected, the foreign object detection device can stop power transmission and return to the selection phase 810. In contrast, if no foreign object is detected, the foreign object detection device can enter the power transmission phase 850 to begin wireless charging of the wireless power receiver.

[0291] Figure 8b This is a diagram illustrating the state transition process of foreign object detection in a foreign object detection device according to an embodiment.

[0292] Reference Figure 8bWhen an object is detected in selection phase 810, the foreign object detection device can measure and store the quality factor and inductance value of the resonant circuit, and then proceed to ping phase 810. In ping phase 820, the foreign object detection device can periodically send predetermined power signals, such as digital ping, to identify the wireless power receiver.

[0293] When a signal strength indicator corresponding to a digital ping is received in the ping phase 820, the foreign object detection device can enter the identification and configuration phase 830 to identify the wireless power receiver and set various configuration parameters for the identified wireless power receiver.

[0294] If the identification and configuration of the wireless power receiver is terminated, the foreign object detection device may enter negotiation phase 840 to receive a FOD status data packet including at least one of a reference quality factor and a reference inductance value.

[0295] The foreign object detection device can determine a threshold (or threshold range) for determining the presence of a foreign object based on a reference value included in the FOD status data packet, and determine whether a foreign object exists in the charging area based on the determined threshold (or threshold range).

[0296] If a foreign object is detected, the foreign object detection device can stop power transmission and return to the selection phase 810. Conversely, if no foreign object is detected, the foreign object detection device can enter the power transmission phase 850 to begin wireless charging of the wireless power receiver. Figure 2 As described, the foreign object detection device can perform calibration phase 250 before entering power transmission phase 850.

[0297] Figure 9a A flowchart is shown for a foreign object detection method in a wireless power transmission device according to another embodiment.

[0298] Reference Figure 9a If an object is detected in the charging area during the selection phase, the wireless power transmission device can measure the quality factor of the resonant circuit and store the quality factor of the resonant circuit in a predetermined recording area (S901).

[0299] The wireless power transmission device can determine whether a foreign object has been detected previously (S902).

[0300] If no foreign object has been detected, the wireless power transmission device can enter the ping phase to wirelessly transmit a digital ping signal for identifying the wireless power receiver (S903).

[0301] When a signal strength indicator is received in response to a digital ping signal, the wireless power transmission device may enter the identification and configuration phase, and when the identification and configuration of the wireless power receiver terminates, it transitions to the negotiation phase (S904).

[0302] The wireless power transmission device can determine a threshold (or threshold range) for determining the presence of a foreign object (FOD) based on a reference quality factor value included in the FOD status data packet received during the negotiation phase (S905). For the method of determining the threshold and threshold range, see [link to relevant documentation]. Figure 11 to Figure 1 Description of 3. The wireless power transmission device can wirelessly transmit power signals of a predetermined strength during the negotiation phase.

[0303] The wireless power transmission device can compare the stored quality factor value with a determined threshold (or threshold range) to determine whether there is a foreign object in the charging area (S906).

[0304] Upon detection of a foreign object, the wireless power transmission device may stop power transmission and execute control to output a predetermined warning alarm indicating that a foreign object has been detected (S907 to S908). Afterward, the wireless power transmission device may return to step 901.

[0305] When it is determined in step 906 that there are no foreign objects, the wireless power transmission device can enter the power transmission stage to begin charging the wireless power receiver (S909).

[0306] When it is determined in step 902 that a foreign object has been detected, the wireless power transmission device can determine whether the detected foreign object has been removed from the charging area (S910). For the method of determining whether the detected foreign object has been removed, see [link to relevant documentation]. Figure 6a to Figure 8b The description.

[0307] Once it is determined that the foreign object has been removed, the wireless power transmission device can enter the power transmission phase to resume charging of the wireless power receiver.

[0308] If it is determined in step 910 that the foreign object has not been removed, the wireless power transmission device may perform step 901.

[0309] Figure 9b A flowchart is shown for a foreign object detection method in a wireless power transmission device according to another embodiment.

[0310] Reference Figure 9b If an object is detected in the charging area during the selection phase, the wireless power transmission device can measure the quality factor and / or inductance value of the resonant circuit and store the quality factor and / or inductance value of the resonant circuit in a predetermined recording area (S901).

[0311] The wireless power transmission device can determine whether a foreign object has been detected (S902).

[0312] When it is determined that no foreign object has been detected, the wireless power transmission device can enter the ping phase to wirelessly transmit a digital ping signal for identifying the wireless power receiver (S903).

[0313] When a signal strength indicator is received in response to a digital ping signal, the wireless power transmission device may enter the identification and configuration phase, and when the identification and configuration of the wireless power receiver terminates, it transitions to the negotiation phase (S904).

[0314] The wireless power transmission device can determine at least one threshold (or threshold range) for determining the presence of a foreign object (FOD) based on FOD status data packets received during the negotiation phase (S905). Here, the threshold may include an inductance threshold and a quality factor threshold. If the determined value is a threshold range, the threshold range may include an inductance threshold range and a quality factor threshold range. The wireless power transmission device can wirelessly transmit a power signal of predetermined strength during the negotiation phase.

[0315] The wireless power transmission device can compare the stored value with a defined threshold (or threshold range) to determine whether there is a foreign object in the charging area (S906).

[0316] Upon detection of a foreign object, the wireless power transmission device may execute control to stop power transmission and output a predetermined warning alarm (optional) indicating that a foreign object has been detected (S907 to S908). Afterward, the wireless power transmission device may return to step 901.

[0317] When it is determined in step 906 that there are no foreign objects, the wireless power transmission device can enter the power transmission stage to begin charging the wireless power receiver (S909).

[0318] When it is determined in step 902 that a foreign object has been detected, the wireless power transmission device can determine whether the detected foreign object has been removed from the charging area (S910). Here, it can be determined whether the detected foreign object has been removed from the charging area by comparing the quality factor and inductance value of the resonant circuit measured in step 901 with the threshold (or threshold range) determined in step 905, but is not limited thereto.

[0319] Once it is determined that the foreign object has been removed, the wireless power transmission device can enter the power transmission phase to resume charging of the wireless power receiver.

[0320] If it is determined in step 910 that the foreign object has not been removed, the wireless power transmission device may perform step 901.

[0321] As described above, when an object is detected in the selection phase, the wireless power transmission device according to the embodiment can measure (or calculate) the quality factor and inductance of the resonant circuit before entering the ping phase, and compare the measured values ​​with the threshold determined based on the FOD status data packet in the negotiation phase to determine whether a foreign object is present, thereby significantly reducing the possibility of foreign object detection failure.

[0322] Figure 10 It is a graph showing the experimental results of the degree of quality factor reduction when a foreign object is placed in the charging area according to the embodiment, compared with the reference quality factor value for each receiver type.

[0323] Figure 10 The results of the experiment are shown when a 10-cent coin is placed in the charging area.

[0324] As by Figure 10 As shown by reference numerals 1010 and 1030 in the figures, it can be seen that after placing a 10-cent coin in the charging area, the absolute difference diff1 between the quality factor value and the reference quality factor value increases as the reference quality factor value increases. At this point, the relationship between the quality factor NO_FO (i.e., the reference quality factor RFQ) measured in the absence of foreign objects and diff1 can be approximated by the equation represented by reference numeral 1011. Although reference numeral 1011 is approximated by a quadratic equation, this is only an example, and linear equations, higher-order equations, exponential equations, etc., can be used.

[0325] like Figure 10 As shown by reference numerals 1020 and 1030, it can be seen that after placing a 10-cent coin in the charging area, the difference ratio %diff1 between the quality factor value and the reference quality factor value increases as the reference quality factor value increases. At this point, the relationship between the quality factor NO_FO (i.e., the reference quality factor RFQ) measured in the absence of foreign objects and %diff1 can be approximated by the equation represented by reference numeral 1021. Although reference numeral 1021 is approximated by a quadratic equation, this is only an example, and linear equations, higher-order equations, exponential equations, etc., can be used.

[0326] Figure 11 It is a graph showing the experimental results of the degree of quality factor reduction compared to the reference quality factor of each type of receiver when a foreign object is placed in the charging area according to another embodiment.

[0327] Figure 11The results of the experiment are shown when a 25-cent coin is placed in the charging area.

[0328] As by Figure 11 As shown by reference numerals 1110 and 1130 in the figures, it can be seen that after placing a 25-cent coin in the charging area, the absolute difference diff2 between the quality factor value and the reference quality factor value increases as the reference quality factor value increases. At this point, the relationship between the quality factor NO_FO (i.e., the reference quality factor RFQ) measured in the absence of foreign objects and diff2 can be approximated by the equation represented by reference numeral 1111. Although reference numeral 1011 is approximated by a quadratic equation, this is only an example, and linear equations, higher-order equations, exponential equations, etc., can be used.

[0329] As by Figure 11 As shown by reference numerals 1120 and 1130, it can be seen that after placing a 25-cent coin in the charging area, the difference ratio %diff2 between the quality factor value and the reference quality factor value increases as the reference quality factor value increases. At this point, the relationship between the quality factor NO_FO (i.e., the reference quality factor RFQ) measured without foreign objects and %diff2 can be approximated by the equation represented by reference numeral 1121. Although reference numeral 1121 is approximated by a quadratic equation, this is only an example, and linear equations, higher-order equations, exponential equations, etc., can be used.

[0330] As described above, when an object is detected in the selection phase, the wireless power transmission device according to the embodiment can measure (or calculate) the quality factor of the resonant circuit before entering the ping phase, and compare the measured value with the threshold determined based on the FOD status data packet in the negotiation phase to determine whether there is a foreign object, thereby significantly reducing the possibility of foreign object detection failure.

[0331] Figure 12 This is a view showing the results of measuring the quality factor and inductance values ​​of the resonant circuit for each receiver type based on the presence / absence of foreign objects.

[0332] Reference numeral 1210 shows the inductance Ls, resistance Rs, and quality factor Q of the resonant circuit measured in state 1211 when nothing is placed in the charging area, state 1212 when only a foreign object is placed, and state 1213 when only the receiver is placed.

[0333] Figure 1220 shows the inductance Ls, resistance Rs, and quality factor Q of the resonant circuit measured for each receiver type with the foreign object and receiver simultaneously placed in the charging area.

[0334] As shown by reference numeral 1211 in the figure, the inductance of the resonant circuit measured with nothing placed on the charging bed of the wireless power transmission device (empty pad) is 25.20 μH and the quality factor is 133.8.

[0335] As shown by reference numeral 1210 in the attached figure, if a foreign object, including, for example, a FO#4 and a 10-cent coin, is placed in the charging area when nothing else is placed there, the inductance value decreases. Conversely, if a receiver capable of wirelessly receiving power (e.g., a smartphone with a wireless charging module) is placed in the charging area when nothing else is placed there, the inductance value increases.

[0336] Furthermore, as indicated by reference numeral 1210 in the attached drawing, if a foreign object or receiver is placed in the charging area when nothing else is present, the quality factor decreases. In particular, it can be seen that the quality factors of receivers 2 and 4 are less than that of FO#4.

[0337] As shown by reference numeral 1220, if a standard foreign object FO#4 and a 10-cent coin are placed in addition to the receiver while it is placed in the charging area, the inductance and quality factor values ​​decrease, as shown by reference numerals 1221 and 1222. However, the rate of decrease in inductance and quality factor values ​​varies depending on the type of receiver. For example, as shown by reference numerals 1213, 1221, and 1222, it can be seen that in the case of receiver 1, if a foreign object is placed, the change in quality factor value is greater than the change in inductance value. Therefore, in the case of receiver 1, the change in quality factor value, rather than the change in inductance value, can be detected to determine the presence of a foreign object. Conversely, it can be seen that in the case of receiver 4, if a foreign object is placed, the change in inductance value is greater than the change in quality factor value. Therefore, in the case of receiver 4, the change in inductance value, rather than the change in quality factor value, can be detected to determine the presence of a foreign object.

[0338] The type of receiver placed in the charging area can be identified during the identification and configuration phase. Therefore, after an object is detected in the selection phase and before entering the ping phase, the wireless power transmission device may not identify the receiver type.

[0339] Therefore, when an object is detected during the selection phase, the wireless power transmission device according to the embodiment can measure and store the inductance value and quality factor value of the resonant circuit before entering the ping phase.

[0340] Subsequently, the wireless power transmission device can determine the inductance threshold and quality factor threshold for detecting foreign objects based on the FOD status data packets received during the negotiation phase. The wireless power transmission device can then compare the determined thresholds with pre-stored inductance and quality factor values ​​to determine the presence of a foreign object.

[0341] For example, when the presence of a foreign object is determined by comparing the stored inductance value with a determined inductance threshold, or when the presence of a foreign object is determined by comparing the stored quality factor value with a determined quality factor threshold, the wireless power transmission device can ultimately determine that the foreign object is placed in the charging area.

[0342] Although the wireless power transmission device in the above embodiment determines the threshold for detecting foreign objects based on FOD status data packets, this is merely an example and a threshold range can be determined. In this case, if at least one of the stored inductance value and quality factor value exceeds the determined threshold range, the wireless power transmission device can determine that a foreign object is present.

[0343] The foreign object detection method of a wireless power transmission device according to another embodiment may further include: receiving a received power strength data packet for power calibration from a wireless power receiver. In this case, the received power strength data packet may include the received power of the wireless power receiver corresponding to a light load or the received power of the wireless power receiver corresponding to a load connection state.

[0344] Figure 13a This is a view showing the structure of a FOD status data packet message according to another embodiment.

[0345] Reference Figure 13a The FOD status data packet message 1340 may have a length of 1 byte and include an operating frequency field 1340 with a maximum quality factor value of 6 bits and a mode field 1342 with a length of 2 bits.

[0346] If an operating frequency in a higher frequency band exists, where the quality factor measured there is higher than the quality factor measured at the operating frequency with the maximum quality factor, then the wireless power transmitter according to the embodiment can determine that a foreign object is present in the charging area. Here, the higher frequency band operating frequency refers to a specific frequency in the operating band that is higher than the operating frequency with the maximum quality factor.

[0347] If there is a peak operating frequency of the quality factor (measured at the highest quality factor among those measured before the ping phase) that is higher than the operating frequency with the highest quality factor value, then the wireless power transmitter according to another embodiment can determine that there is a foreign object in the charging area.

[0348] For example, the operating frequency of the maximum quality factor value 1341 can be related to... Figure 2 The operating frequency of the maximum quality factor corresponding to the type of wireless power transmitter confirmed in the identification and configuration phase 230. For example, information related to the operating frequency of the maximum quality factor according to the type of connectable wireless power transmitter can be stored in a predetermined recording area of ​​the wireless power receiver. The operating frequency of the maximum quality factor can vary depending on the power rating, design shape, manufacturer, and standards of the wireless power transmitter.

[0349] Therefore, when determining the operating frequency or range for measuring the maximum quality factor in a wireless power receiver, the wireless power transmitter can minimize the frequency range for measuring the quality factor to determine the presence of foreign objects. In other words, the wireless power transmitter can avoid measuring the quality factor in frequency bands lower than the operating frequency of the maximum quality factor.

[0350] In another example, although the operating frequency 1342 for the maximum quality factor is the operating frequency for a specific coil type (e.g., MP-A1 type) defined in the WPC standard, the implementation is not limited to this, and the operating frequency for the maximum quality factor corresponding to a wireless power transmitter with a transmission coil can be used. Based on the MP-A1 type, the received maximum quality factor can be scaled to take into account design differences and product characteristics of different types of wireless power transmitters, and the received maximum quality factor can be used to determine the presence of foreign objects.

[0351] The wireless power transmitter according to the embodiment can be Figure 2 During ping phase 220 (or before ping phase), the quality factor value a1 at a specific upper limit frequency in the operating band is measured and stored. Alternatively, the maximum quality factor among the quality factors measured within a predetermined frequency range (in the operating band) and the frequency at which the maximum quality factor is measured can be stored. Thereafter, the wireless power transmitter can measure the quality factor value a2 at the operating frequency 1341 of the maximum quality factor value received via FOD status data packet 1340 during negotiation phase 240, and if a1 is greater than a2, determine that a foreign object is present in the charging area. Alternatively, the wireless power transmitter can determine the presence of a foreign object by comparing the operating frequency of the maximum quality factor value received via FOD status data packet 1340 during negotiation phase 240 with the frequency at which the maximum quality factor is measured during ping phase 220 (or before ping phase).

[0352] If the frequency at which the maximum quality factor is measured during ping phase 220 is greater than the operating frequency at which the maximum quality factor is received, then the presence of a foreign object can be determined. This principle will be described in detail below.

[0353] Although in this embodiment the wireless power transmitter may measure only the quality factor at the upper limit frequency of the operating band during ping phase 220 (or before the ping phase), this is merely an example, and both the quality factor at the lower limit frequency and the quality factor at the upper limit frequency can be measured. In another embodiment, the quality factor at each frequency can be measured by scanning from the lower limit frequency to the upper limit frequency.

[0354] In another implementation, the quality factor of each frequency can be measured by scanning within a specific frequency region.

[0355] The wireless power transmitter is configured to measure the quality factor at the lower limit frequency of the operating band during ping phase 220. Although in this embodiment the wireless power transmitter may measure only the quality factor at the upper limit frequency of the operating band during ping phase 220, this is merely an example, and both the quality factor at the lower limit frequency and the quality factor at the upper limit frequency may be measured.

[0356] According to the implementation, the frequency offset value from the lower limit frequency (i.e., the lowest frequency) of the operating frequency can be recorded in the operating frequency field 1341 of the maximum quality factor value. In this case, the offset unit can be, but is not limited to, 10kHz and can be less than or greater than 10kHz. For example, if the operating frequency band of the wireless power transmitter is between the lower limit frequency of 100kHz and the upper limit frequency of 300kHz, then the offset unit is 10kHz, and the value recorded in the operating frequency field 1341 of the maximum quality factor value is the binary value 000011. The actual frequency of the maximum quality factor value can be 130kHz (100kHz + 3 * 10kHz).

[0357] In another embodiment, the wireless power transmitter can scan the entire operating frequency band or a specific band within the entire operating frequency band to measure the quality factor value before the ping phase.

[0358] In another embodiment, instead of Figure 13a The operation frequency of the maximum quality factor value is inserted into field 1341. Operation frequency values ​​where the quality factor value is lower than the reference quality factor value by a predetermined value (or proportion) can be inserted into field 1341.

[0359] The wireless power transmitter can compare the quality factor B1 measured at a reference operating frequency (e.g., the operating frequency used to measure the quality factor value is 100 kHz) during the ping phase 220 (or before the ping phase) with the quality factor B2 measured at an operating frequency greater than the received operating frequency to determine whether a foreign object is present.

[0360] If B1 is greater than B2, then it can be determined that there is a foreign object.

[0361] Figure 13b This is a view showing the structure of a FOD status data packet message according to another embodiment.

[0362] Reference Figure 13b The FOD status data packet message 1350 may have a length of 2 bytes and includes an operating frequency field 1351 with a maximum quality factor value of 6 bits, a mode field 1352 with a length of 2 bits, and a reference quality factor value field 1353 with a length of 1 byte.

[0363] Although the wireless power transmitter can check whether the operating frequency 1351 of the maximum quality factor is included in the FOD status data packet received via the value of mode 1352, the implementation is not limited to this, and the operating frequency 1351 of the maximum quality factor can always be included in the FOD status data packet, regardless of the value of mode 1352.

[0364] Received Figure 7a When a foreign object (FOD) status packet is received, the wireless power transmitter can compare a reference quality factor value with a quality factor value measured during ping phase 220 (or before ping phase) to determine the presence of a foreign object (Method 1), or compare the operating frequency of the maximum quality factor value with the maximum operating frequency corresponding to the maximum quality factor value measured during ping phase 220 (or before ping phase) to determine the presence of a foreign object (Method 2). Figure 13a Implementation method).

[0365] For alternative sites, various methods can be used to determine whether foreign objects are present.

[0366] In this implementation, the wireless power transmitter can use method 1 to determine the presence of a foreign object. In this case, two thresholds (threshold 1: Q_Threshold 1 and threshold 2: Q_Threshold 2) can be determined based on the received reference quality factor value.

[0367] If the quality factor measured before ping phase 220 is less than the threshold value of 2, the wireless power transmitter can determine that a foreign object is present.

[0368] If the quality factor measured before ping phase 220 is less than threshold 1 and greater than or equal to threshold 2, the wireless power transmitter can determine the presence of a foreign object using method 2.

[0369] Figure 13c This is a view showing the structure of a FOD status data packet message according to another embodiment.

[0370] Reference Figure 13c The FOD status packet message 1360 may have a length of 2 bytes and includes a wireless power transmitter (Tx) type field 1361 with a length of 6 bits, a mode field 1362 with a length of 2 bits, and an operating frequency field 1363 with a length of 1 byte for the maximum quality factor value.

[0371] Although the wireless power transmitter can check whether the operating frequency 1363 of the wireless power transmitter type 1361 and the maximum quality factor is included in the FOD status data packet received via the value of mode 1362, the implementation is not limited thereto, and the operating frequency 1363 of the wireless power transmitter type 1361 and the maximum quality factor can always be included in the FOD status data packet, regardless of the value of mode 1362.

[0372] For example, wireless power transmitter type 1361 could be a value (predetermined classification number) indicating a predetermined transmitter (Tx) design number registered during WPC(Qi) certification to uniquely identify the wireless power transmitter.

[0373] In another example, wireless power transmitter type 1361 could be a predetermined classification number used to classify wireless power transmitters that share common design and performance characteristics.

[0374] If an operating frequency in a higher frequency band, which has a higher quality factor than the operating frequency with the highest quality factor, is present at a location, the wireless power transmitter according to the embodiment can determine that a foreign object is present in the charging region. Here, in the operating frequency band, the higher frequency band refers to a specific frequency that is higher than the operating frequency with the highest quality factor.

[0375] If there is a peak operating frequency of the quality factor (the highest quality factor among those measured before the ping phase) in a frequency band higher than the operating frequency with the highest quality factor value, then the wireless power transmitter according to another embodiment can determine that there is a foreign object in the charging area.

[0376] In the following text, for ease of description, the reference quality factor value measured in the absence of foreign objects is RQF_NO_FO, and the quality factor value measured in the presence of a specific foreign object is QF_FO. For example, although the specific foreign object is foreign object #4 (which can be used interchangeably with FO4 for ease of description), foreign object #4 is an aluminum disc with a diameter of 22 mm and a thickness of 1 mm, the implementation is not limited to this, and any coin can be used.

[0377] The wireless power transmitter measures the current quality factor value during the selection phase, prior to the ping phase. Taking into account the reference quality factor value received from the wireless power receiver during the negotiation phase, manufacturing and measurement tolerances due to design differences in each transmitter, and the accuracy of the reference quality factor, the wireless power transmitter determines a quality factor threshold for determining the presence of foreign matter.

[0378] The reference quality factor (QF) value refers to the minimum of the five QF values ​​measured in the charging region of a test power transmitter (TPT) (e.g., an MP1 (MP-A1) type transmitter) (the center and four positions 5 mm to the left, right, up, and down from the center). Due to design differences between the MP1 as a test power transmitter (TPT) and commercial wireless power transmitters including the inductance value of the transmission coil, the actual QF value measured in the charging region can differ between transmitters. The tolerance used to calibrate it is called the production and measurement tolerance.

[0379] For example, the decrease in the reference quality factor 1321 can be determined by subtracting the quality factor measured in the presence of a specific foreign object from the reference quality factor value corresponding to the wireless power receiver.

[0380] In another example, the decrease in the reference quality factor 1321 can be the ratio of the quality factor value measured in the presence of foreign matter to the reference quality factor value measured in the absence of foreign matter. In this case, the decrease in the reference quality factor 1321 can be an integer value calculated as a percentage (%) or an integer value calculated by dividing that percentage by a specific unit STEP_VALUE, but is not limited thereto. For example, the decrease in the reference quality factor 1321 can be calculated using Equation 1 below.

[0381] Equation 1

[0382] [(RQF_NO_FO-QF_FO) / RQF_NO_FO]*100 or

[0383] [((RQF_NO_FO-QF_FO) / RQF_NO_FO)*100] / STEP_VALUE

[0384] (Here, *100 can be used to represent a value expressed as a percentage and may not be applicable to actual values.)

[0385] Wireless power receivers may have a reference quality factor degradation value that varies depending on at least one of the manufacturer and product type.

[0386] Therefore, the wireless power transmitter according to the embodiment can obtain a decrease in the reference quality factor from the detected wireless power receiver, and adaptively determine a quality factor threshold for determining the presence of foreign matter by taking into account the decrease in the reference quality factor.

[0387] Therefore, according to the implementation method, the problem of heat generation or significant reduction in power transmission efficiency due to the failure to detect foreign objects in the charging area can be minimized.

[0388] Figure 13d This is a view showing the structure of a FOD status data packet message according to an embodiment.

[0389] Reference Figure 13d The FOD status data packet message 1300 may have a length of 2 bytes and includes a reserved field 1301 with a length of 6 bits, a mode field 1302 with a length of 2 bits, and a reference quality factor field 1303 with a length of 1 byte.

[0390] All bits of the reserved field 1301 can be set to 0.

[0391] As indicated by reference numeral 1304, if the mode field 1302 is set to the binary value "00", this indicates that the reference quality factor RQF_NO_FO (first reference quality factor) value, measured and determined in the absence of FO, will be recorded in the reference quality factor value field 1303. And if the mode field 1302 is set to the binary value "01", this indicates that the reference quality factor RQF_FO (second reference quality factor) value, measured and determined in the presence of FO, will be recorded in the reference quality factor value field 1303.

[0392] Figure 13e This is a view showing the structure of a FO status data packet message according to one embodiment.

[0393] Reference Figure 13e The FO status data packet message 1310 may have a length of 3 bytes and include a reserved field 1311 with a length of 6 bits, a mode field 1312 with a length of 2 bits, a reference quality factor value 1313, and a reference quality factor value 1314 in the presence of foreign objects.

[0394] All bits of the reserved field 1301 can be set to 0.

[0395] The operating mode of the power receiver with reference quality factor 1313 applied can be identified by mode field 1312. As indicated by reference numeral 1315, if the value of mode 1312 is the binary value "00", this indicates the reference quality factor measured when the wireless power receiver is powered off.

[0396] The wireless power receiver may have a reference quality factor measured in the absence of foreign matter and a reference quality factor measured in the presence of foreign matter, varying according to at least one of the manufacturing and product types.

[0397] The wireless power transmitter according to the embodiment can adaptively determine a quality factor threshold for determining the presence of foreign objects, taking into account both a reference quality factor value measured when no foreign object is present and a reference quality factor value measured when a foreign object is present. This is because the variation in the quality factor value based on the presence or absence of foreign objects can differ between receivers. Therefore, according to the embodiment, problems such as heat generation or significant reduction in power transmission efficiency due to the failure to detect foreign objects in the charging area can be minimized.

[0398] Figure 13f This is a view showing the structure of a FO status data packet message according to another embodiment.

[0399] Reference Figure 13f The FO status data packet message 1120 may have a length of 2 bytes and includes a reference quality factor decrement value field 1321 with a length of 6 bits, a mode field 1322 with a length of 2 bits, and a reference quality factor value field 1323.

[0400] Here, the decrease in the reference quality factor 1321 can be determined based on the reference quality factor value 1223 measured when there is no foreign object and the quality factor value measured when there is a specific foreign object (the quality factor value in the case of foreign object).

[0401] The pattern field 1322 can be used to indicate that a decrease in the reference quality factor 1321 is recorded in the reserved field 1301 of Figure 13d. For example, as indicated by reference numeral 1324, if the value of the pattern field 1322 is the binary value "01", this can indicate that a decrease in the reference quality factor 1321 has been recorded. However, this is only an example, and other values ​​of the pattern field 1322 (e.g., the binary value "10" or the binary value "11") can be used to indicate that a decrease in the reference quality factor 1321 has been recorded.

[0402] However, if the value of the mode field 1322 is set to a value other than the binary value "00", the reference quality factor 1323 can automatically represent the value measured when the power receiver is off.

[0403] Although the format of the foreign object status data packet is described as being identified by a pattern, for ease of description, in certain implementations, it can be used in... Figure 13d to Figure 13g The foreign object status data packet shown in the image, regardless of the mode.

[0404] Figure 13g This is a view showing the structure of a FO status data packet message according to another embodiment.

[0405] Reference Figure 13g The FO status data packet message 1330 may have a length of 2 bytes and include an accuracy field 1331 with a reference quality factor of 6 bits, a mode field 1332 with a length of 2 bits, and a reference quality factor value field 1333.

[0406] Here, the accuracy 1331 of the reference quality factor can be the tolerance of the reference quality factor value 1333 measured in the absence of foreign objects. For example, the reference quality factor value to which the tolerance is applied can be set as the rate of increase or decrease of the reference quality factor value 1333 received from the wireless power receiving device, but is not limited thereto.

[0407] The accuracy 1331 of the reference quality factor can vary depending on at least one of the manufacturer and product type of the wireless power receiver. For example, the accuracy of the reference quality factor values ​​measured by the wireless power receiver of Company A and the wireless power receiver of Company B through interaction with the same wireless power transmitter may differ from each other. Therefore, the wireless power transmitter needs to obtain information about the accuracy of the reference quality factor for each wireless power receiver and can take the accuracy of the reference quality factor into account to determine the quality factor threshold used to determine the presence of foreign matter. Additionally, in the wireless power transmitter, for ease of description, the quality factor threshold used to determine the presence of foreign matter is referred to as FO_QF_THRESHOLD.

[0408] For example, as a result of testing the same wireless power transmitter, the reference quality factor of the wireless power receiver of Company A can be measured to be 100, and the reference quality factor of the wireless power receiver of Company B can be measured to be 70. In this case, the accuracy of the reference quality factor corresponding to wireless power receiver Company B (e.g., + / - 7%) can be set to be greater than the accuracy of the reference quality factor corresponding to wireless power receiver Company A (e.g., + / - 10%). That is, the wireless power receiver of Company B can be set to have a higher error sensitivity than the wireless power receiver of Company A.

[0409] The accuracy of the quality factor can vary depending on the configuration of the finished product with the receiver installed. Depending on the PCB, camera module, antenna, and other components installed in the finished product, the quality factor measured in the absence of foreign objects may be lower than that of other finished products. If the finished product is located in the charging area along with foreign objects, the variation in the quality factor value may be less than that of other finished products, thus requiring higher measurement accuracy.

[0410] Pattern field 1322 can be used to indicate that the accuracy 1331 of the reference quality factor is recorded. Figure 13d The reserved field 1301. For example, as indicated by reference numeral 1334, if the value of the pattern field 1332 is the binary value "01", this can indicate that the accuracy 1331 of the reference quality factor has been recorded. However, this is only an example, and other values ​​of the pattern field 1322 (e.g., the binary value "10" or the binary value "11") can be used to indicate the accuracy 1331 of the recorded reference quality factor.

[0411] However, if the value of the mode field 1332 is set to a value other than the binary value "00", the reference quality factor 1333 can automatically represent the value measured when the power receiver is off.

[0412] Figure 14 This is a flowchart illustrating a FOD method according to another embodiment.

[0413] Reference Figure 14 During the negotiation phase, the wireless power receiver 1410 may send a FOD status data packet, including a second reference quality factor (RQF_FO), to the wireless power transmitter 1420 (S1401). At this time, the mode value of the FOD status data packet can be set to "01".

[0414] The second reference quality factor can be determined as the minimum of the quality factor values ​​measured at multiple points in the charging area of ​​a particular wireless power transmitter, and can be maintained in the wireless power receiver.

[0415] For example, the second reference quality factor RQF_FO can be determined as the minimum of the first and second quality factors. The first quality factor is measured at the center where the transmitting coil (primary coil) and receiving coil (secondary coil) are well aligned, with FO present near the wireless power receiver placed in the charging area. The second quality factor is measured while the wireless power receiver is not rotated, moving along the x and y axes by a constant distance offset from the center (e.g., but not limited to + / - 5 mm), with FO present near the wireless power receiver. The second quality factor may include quality factors measured at at least four different locations.

[0416] The wireless power transmitter 1420 can determine a threshold for FO detection based on a design factor pre-stored corresponding to the wireless power transmitter 1420 and a received second reference quality factor value (S1403). In the following text, for ease of description, the second reference quality factor value corrected based on the design factor will be referred to as the corrected quality factor threshold Q_threshold_correct.

[0417] Since the second reference quality factor value is determined based on the quality factor value measured at a specific wireless power transmitter (hereinafter referred to as the wireless power transmitter for testing), a commercially manufactured wireless power transmitter (hereinafter referred to as a commercial wireless power transmitter for ease of description) may differ from the wireless power transmitter for testing in terms of configuration and characteristics. Therefore, the quality factor values ​​measured by the commercial wireless power transmitter and the wireless power transmitter for testing under the same conditions may differ from each other. Therefore, considering the configuration and characteristics (i.e., design factor) of the commercial wireless power transmitter, a correction is required in... Figure 20 In the implementation, it is used as a second reference quality factor value for the threshold used for FO detection.

[0418] For example, the design factor can be a determined correction constant based on at least one of the following: the power rating corresponding to a commercial wireless power transmitter, the characteristics and arrangement of the transmission coils, the power control algorithm installed in the transmitter, power transmission losses, and the shape and structure of the wireless power transmitter. However, the implementation is not limited to this, and values ​​capable of correcting for the quality factor value relative to the measurement error of the wireless power transmitter used for testing can be used.

[0419] The wireless power transmitter 1420 can measure the current quality factor value Q_current and compare the current quality factor value Q_current with the corrected quality factor threshold Q_threshold_correct (S1403 to S1404).

[0420] As a reference, the current quality factor value can be measured before the digital ping phase, immediately before the negotiation (renegotiation) phase, or periodically.

[0421] As a result of the comparison, if the current quality factor value Q_current is greater than or equal to the corrected quality factor threshold Q_threshold_correct, then the wireless power transmitter 1420 can determine that FO has not been detected and send an ACK response to the wireless power receiver 1410 (S1405). At this time, the state of the wireless power transmitter 1420 can transition from the negotiation step to the power delivery phase.

[0422] As a result of the comparison in step 1401, if the current quality factor value Q_current is less than the corrected quality factor threshold Q_threshold_correct, then the wireless power transmitter 1420 can determine that FO has been detected and send a NAK response to the wireless power receiver 1410 (S1406). At this time, the state of the wireless power transmitter 1420 can transition from the negotiation phase to the selection phase.

[0423] Figure 15 This is a flowchart illustrating a FOD method according to another embodiment.

[0424] Reference Figure 15 During the negotiation phase, the wireless power receiver 1510 may send a first FOD status data packet to a second FOD status data packet, including a reference quality factor value Q_reference, to the wireless power transmitter 1520 (S1501 to S1502).

[0425] Here, when the mode has a binary value "00", the first FOD status data packet may include a first reference quality factor value RQF_NO_FO. When the mode is 1, the second FOD status data packet may include a second reference quality factor value RQF_FO, that is, a reference quality factor value determined based on the quality factor value measured when FO is present in the charging region.

[0426] Here, the first reference quality factor value RQF_NO_FO is greater than the second reference quality factor value RQF_FO.

[0427] The first reference quality factor and the second reference quality factor can be determined based on quality factor values ​​measured in the presence and absence of a field of view (FO) near the receiver. For example, the first reference quality factor and the second reference quality factor can be the minimum of quality factor values ​​measured at multiple points in the charging area of ​​a particular wireless power transmitter used for testing.

[0428] The wireless power transmitter 1520 can determine the quality factor threshold rate Q_threshold_rate for FO detection based on the received first reference quality factor value to the second reference quality factor value (S1503).

[0429] Here, the quality factor threshold rate Q_threshold_rate can be calculated by dividing the difference between the first reference quality factor value RQF_NO_FO and the second reference quality factor value RQF_FO by the first reference quality factor value RQF_NO_FO. For example, if the first reference quality factor value RQF_NO_FO is 80 and the second reference quality factor value RQF_FO is 50, then the quality factor threshold rate Q_threshold_rate could be (80-50) / 80 = 0.375.

[0430] The wireless power transmitter 1520 can measure the current quality factor value Q_current and calculate the quality factor reduction rate Q_decrease_rate (S1404) based on the measured current quality factor value and the first reference quality factor value RQF_NO_FO.

[0431] As a reference, the current quality factor value can be measured before the digital ping phase, immediately before the negotiation (renegotiation) phase, or periodically.

[0432] The wireless power transmitter 1520 can determine whether the rate of decrease in quality factor Q_decrease_rate is less than the quality factor threshold rate Q_threshold_rate by comparison (S1505).

[0433] As a result of the comparison, when the quality factor decrease rate Q_decrease_rate is determined to be less than the quality factor threshold rate Q_threshold_rate, the wireless power transmitter 1520 can determine that FO has not been detected and send an ACK response to the wireless power receiver 1510 (S1506). At this time, the state of the wireless power transmitter 1520 can be transitioned from the negotiation phase to the power delivery phase.

[0434] As a result of the comparison in step 1505, when it is determined that the quality factor reduction rate Q_decrease_rate is greater than or equal to the quality factor threshold rate Q_threshold_rate, the wireless power transmitter 1520 can determine that FO has been detected and send a NAK response to the wireless power receiver 1510 (S1507). At this time, the state of the wireless power transmitter 1520 can be transitioned from the negotiation phase to the selection phase.

[0435] Despite Figure 15 In one implementation, FO detection is performed by comparing the quality factor reduction rate Q_decrease_rate with the quality factor threshold rate Q_threshold_rate. However, this is only an example, and according to another implementation, a wireless power transmitter can calculate a corrected quality factor threshold rate Q_threshold_rate_correct based on a design factor corresponding to the wireless power transmitter, and determine the presence of FO in the charging region by comparing the quality factor reduction rate Q_decrease_rate with the corrected quality factor threshold rate Q_threshold_rate_correct.

[0436] In another embodiment, the quality factor threshold can be determined as follows.

[0437] The quality factor threshold can be determined by taking into account the range of quality factor measurement error (±10% of the received reference quality factor value (0.1*reference quality factor value) or the accuracy of the quality factor value and transmitter characteristics (transmitter type (design), manufacturer, product or measurement error, etc.).

[0438] Figure 16 It is a quality factor table based on the implementation method.

[0439] Can Figure 16 The quality factor table 1600 shown is maintained in the memory of the wireless power transmitter. The wireless power transmitter can update the quality factor table 1600 based on received FO status packets. For example, the quality factor table 1600 may include at least one of the following: a receiver identifier field 1601, a most recently measured quality factor value field 1602, a first reference quality factor value field RQF_NO_FO 1603, a second reference quality factor value field RQF_FO 1604, and a corrected quality factor threshold field Q_threshold_correct 1605.

[0440] Here, the receiver identifier 1601 can be configured using any one or a combination of the manufacturer code, the basic device identifier, and the extended device identifier obtained during the identification and configuration phase. For example, the receiver identifier can be configured by concatenating the manufacturer code and the basic device identifier together. In another example, the receiver identifier can be configured by concatenating the manufacturer code, the basic device identifier, and the extended device identifier together.

[0441] In the latest measured quality factor value field 1602, the latest measured quality factor value can be recorded corresponding to the receiver identifier 1601. At this time, if the charging of the wireless power receiver corresponding to the receiver identifier 1601 is terminated normally or the transition from the negotiation phase to the power transmission phase is performed normally, the wireless power transmitter can record the quality factor value measured in the negotiation phase in the quality factor table 1600.

[0442] Additionally, if a FOD status data packet is received during the negotiation phase, the wireless power transmitter may record at least one of the second reference quality factor value RQF_FO and the first reference quality factor value RQF_NO_FO included in the FOD status data packet in the quality factor table 1600.

[0443] Additionally, the wireless power transmitter can record the corrected quality factor threshold Q_threshold_correct, calculated during the first negotiation phase for FO detection, together with the wireless power receiver in the quality factor table 1600.

[0444] If a wireless power receiver corresponding to the receiver identifier recorded in the quality factor table 1600 is subsequently detected, the wireless power transmitter can detect FO by referring to the quality factor table 1600.

[0445] According to another embodiment, the quality factor table 1600 may also include Figure 13f The decrease in the reference quality factor described in the text is 1321 and Figure 13d At least one of the accuracy of the reference quality factor 1331 described in the document.

[0446] Figure 17 This is a block diagram illustrating the configuration of an FO detection device according to an embodiment.

[0447] The FO detection device 1700 according to the embodiment can be installed or assembled in a wireless power transmitter.

[0448] Reference Figure 17The FO detection device 1700 may include a communication unit 1710, a determination unit 1720, a measurement unit 1730, a detector 1740, a controller 1750, and a power transmission unit 1760.

[0449] During the negotiation phase, the communication unit 1710 can receive a FOD status data packet including a reference quality factor value from the connected wireless power receiver. Here, the reference quality factor value may include at least one of a reference quality factor value RQF_NO_FO (a first reference quality factor value) when there is no FO in the charging area and a reference quality factor value RQF_FO (a second reference quality factor value) when there is FO in the charging area, and can be received during the negotiation phase via one or more FOD status data packets.

[0450] The determining unit 1720 can determine the threshold to be used during FO detection based on the received reference quality factor value. For example, a second reference quality factor value RQF_FO can be determined as the threshold to be used during FO detection, which is just an example, and a second reference quality factor value based on a design factor correction corresponding to the wireless power transmitter can be determined as the threshold to be used during FO detection.

[0451] As a threshold used in FO detection according to another embodiment, a quality factor threshold rate Q_threshold_rate calculated based on a first reference quality factor value and a second reference quality factor value can be determined.

[0452] In a first embodiment, the quality factor threshold rate Q_threshold_rate can be calculated by dividing the difference between the first reference quality factor value RQF_NO_FO and the second reference quality factor value RQF_FO by the first reference quality factor value RQF_NO_FO. For example, if the first reference quality factor value RQF_NO_FO is 80 and the second reference quality factor value RQF_FO is 50, then the quality factor threshold rate Q_threshold_rate can be (80-50) / 80 = 0.375.

[0453] In the second embodiment, the quality factor threshold rate Q_threshold_rate can be a value obtained by dividing the second reference quality factor value RQF_FO by the first reference quality factor value RQF_NO_FO. For example, if the first reference quality factor value RQF_NO_FO is 80 and the second reference quality factor value RQF_FO is 50, then the quality factor threshold rate Q_threshold_rate can be 50 / 80 = 0.625.

[0454] As a threshold used in FO detection according to another embodiment, a corrected quality factor threshold rate Q_threshold_rate_correct, calculated based on a first corrected reference quality factor and a second corrected reference quality factor, can be determined. The first corrected reference quality factor and the second corrected reference quality factor are calculated by applying a design factor predetermined according to the wireless power transmitter to the values ​​of the first reference quality factor and the second reference quality factor.

[0455] The measurement unit 1730 can measure or calculate the current quality factor value to be compared with the threshold during FO detection.

[0456] For example, the measurement unit 1730 can measure the current quality factor value Q_current during the negotiation phase.

[0457] Additionally, the measurement unit 1730 can calculate the quality factor reduction rate Q_decrease_rate based on the measured current quality factor value Q_current and the first reference quality factor value RQF_NO_FO. Here, the quality factor reduction rate Q_decrease_rate can be calculated as [RQF_NO_FO - Q_current] / [RQF_NO_FO].

[0458] Additionally, the measurement unit 1730 can calculate the current quality factor rate Q_current_rate based on the measured current quality factor value Q_current and the first reference quality factor value RQF_NO_FO. Here, the current quality factor rate Q_current_rate can be calculated by [Q_current] / [RQF_NO_FO].

[0459] The detector 1740 can compare the threshold determined by the determining unit 1720 with the value measured or calculated by the measuring unit 1730 to detect the presence of FO in the charging area.

[0460] For example, such as Figure 20 As shown, if the current quality factor value Q_current is less than the second reference quality factor value RQF_FO, the detector 1740 can determine that FO exists in the charging region.

[0461] In another example, such as Figure 14 As shown, if the current quality factor value Q_current is less than the corrected quality factor threshold Q_threshold_correct, the detector 1740 can determine that FO exists in the charging region.

[0462] In another example, such as Figure 15As shown, detector 1740 can determine the presence of FO in the charging region by comparing the quality factor reduction rate Q_decrease_rate with the quality factor threshold rate Q_threshold_rate.

[0463] In another example, detector 1740 can determine the presence of FO in the charging region by comparing the quality factor reduction rate Q_decrease_rate with a corrected quality factor threshold rate calculated based on the design factor corresponding to the wireless power transmitter.

[0464] In another example, detector 1740 can determine the quality factor threshold as follows.

[0465] The quality factor threshold can be determined by taking into account the range of quality factor measurement error (±10% of the received reference quality factor value (0.1*reference quality factor value) or the accuracy of the quality factor value and transmitter characteristics (transmitter type (design), manufacturer, product or measurement error, etc.).

[0466] The controller 1750 can control the overall operation and input / output of the FO detection device 1700. For example, the controller 1750 can perform control to transition the state of the wireless power transmitter from the negotiation phase to the power delivery phase, and if the detector 1740 does not detect FO, the power delivery unit 1760 delivers the power required to charge the load. In another example, the controller 1750 can perform control to transition the state of the wireless power transmitter from the negotiation phase to the selection phase, and if the detector 1740 detects FO, interrupt the power delivery of the power delivery unit 1760.

[0467] According to another embodiment, the FO detection device 1700 may further include a storage... Figure 16 The memory of the quality factor table 1600 shown (not shown).

[0468] According to another embodiment, the FO detection device 1700 may further include a correction unit (not shown) for calculating the power loss between the wireless power receiver and the wireless power transmitter before switching to the power transmission stage if the detector 1740 does not detect FO.

[0469] Figure 18 This is a flowchart illustrating a FOD method according to another embodiment.

[0470] Reference Figure 18During the negotiation phase, the wireless power receiver 1810 may send a FOD status data packet, including the reference quality factor value and the decrease value of the reference quality factor, to the wireless power transmitter 1820 (S1801). At this time, the mode value of the FOD status data packet may be set to "01", but is not limited to this.

[0471] Here, the reference quality factor value can be determined as the minimum of the quality factor values ​​measured at multiple points in the charging area of ​​a specific wireless power transmitter used for performance testing, and can be maintained in the wireless power receiver.

[0472] The wireless power transmitter 1820 can use the received reference quality factor value and the decrease in the reference quality factor to determine the quality factor threshold Q_threshold (S1803).

[0473] For example, the wireless power transmitter 1820 may determine the quality factor threshold as the value obtained by subtracting the decrease in the reference quality factor from the reference quality factor value, but is not limited thereto. In another example, the quality factor threshold may be determined using a predetermined quality factor generation function that utilizes the reference quality factor value and the decrease in the reference quality factor as input variables.

[0474] The wireless power transmitter 1820 can measure the current quality factor value Q_current and determine whether the current quality factor value Q_current is greater than or equal to the quality factor threshold Q_threshold (S1803 to S1804).

[0475] As a reference, the current quality factor value can be measured before the digital ping phase, immediately before the negotiation (renegotiation) phase, or periodically.

[0476] As a result of the comparison, if the current quality factor value Q_current is greater than or equal to the quality factor threshold Q_threshold, the wireless power transmitter 1820 can determine that FO has not been detected and send an ACK response to the wireless power receiver 1810 (S1805). At this time, the state of the wireless power transmitter 1820 can transition from the negotiation step to the power transmission phase.

[0477] As a result of the comparison in step 1804, if the current quality factor value Q_current is less than the quality factor threshold Q_threshold, then the wireless power transmitter 1820 can determine that FO has been detected and send a NAK response to the wireless power receiver 1810 (S1806). At this time, the state of the wireless power transmitter 1820 can transition from the negotiation phase to the selection phase.

[0478] Figure 19 This is a flowchart illustrating a FOD method according to another embodiment.

[0479] Reference Figure 19 During the negotiation phase, the wireless power receiver 1910 can send a FOD status data packet, including the accuracy and reference quality factor value, to the wireless power transmitter 1920 (S1901). At this time, the mode value of the FOD status data packet can be set to the binary value "01", but is not limited to this.

[0480] The wireless power transmitter 1920 can use the accuracy of the received reference quality factor and the value of the reference quality factor to determine the quality factor threshold Q_threshold (S1903).

[0481] The wireless power transmitter 1920 according to the embodiment can use pre-stored production and measurement tolerances to determine the quality factor threshold.

[0482] For example, the wireless power transmitter 1920 may determine the quality factor threshold as a value obtained by subtracting the accuracy of the reference quality factor and production and measurement tolerances from the reference quality factor value, but is not limited thereto. In another example, the quality factor threshold may be determined using a predetermined quality factor threshold generation function that utilizes the accuracy of the reference quality factor and the reference quality factor value as input variables.

[0483] The wireless power transmitter 1920 can measure the current quality factor value Q_current and determine whether the current quality factor value Q_current is greater than or equal to the quality factor threshold Q_threshold (S1903 to S1904).

[0484] The current quality factor value can be measured before the digital ping phase, immediately before the negotiation (renegotiation) phase, or periodically according to the implementation method.

[0485] As a result of the comparison, if the current quality factor value Q_current is greater than or equal to the quality factor threshold Q_threshold, the wireless power transmitter 1920 can determine that FO has not been detected and send an ACK response to the wireless power receiver 1910 (S1905). At this time, the state of the wireless power transmitter 1920 can transition from the negotiation step to the power transmission phase.

[0486] As a result of the comparison in step 1904, if the current quality factor value Q_current is less than the quality factor threshold Q_threshold, then the wireless power transmitter 1920 can determine that FO has been detected and send a NAK response to the wireless power receiver 1910 (S1906). At this time, the state of the wireless power transmitter 1920 can transition from the negotiation phase to the selection phase.

[0487] According to another embodiment, a wireless power transmitter can acquire a reference quality factor value, a reference quality factor accuracy, and a reference quality factor depreciation value through multiple FOD status data packets. In this case, the wireless power transmitter can use the reference quality factor value, the reference quality factor accuracy, the reference quality factor depreciation value, and at least one of production and measurement tolerances to determine a quality factor threshold.

[0488] For example, a wireless power transmitter can determine the output value of a predetermined quality factor threshold generation function that uses a reference quality factor value, the accuracy of the reference quality factor, and the decrease in the reference quality factor as input variables.

[0489] According to another embodiment, the wireless power transmitter can acquire from the wireless power receiver the quality factor value, the accuracy of the reference quality factor, and the decrease value of the reference quality factor measured in the absence of foreign objects by multiple FOD status data packets.

[0490] For example, a wireless power transmitter can determine the quality factor threshold by subtracting the accuracy of a reference quality factor and the decrease in the reference quality factor from the quality factor value measured in the absence of foreign objects.

[0491] In another example, the wireless power transmitter can determine the quality factor threshold as the output value of a predetermined quality factor threshold generation function, which uses the quality factor value measured in the absence of foreign objects, the accuracy of the reference quality factor, and the decrease in the reference quality factor as input variables.

[0492] Figure 20 This is a flowchart illustrating a FOD method based on a quality factor value according to another embodiment.

[0493] Reference Figure 20The wireless power transmitter can measure a first quality factor value at a first frequency within a predetermined operating frequency band (S2001). Here, the operating frequency band can be preset to a band from 100 kHz to 210 kHz. However, this is merely an example, and it should be noted that different operating frequency bands can be set depending on the setup and configuration of the wireless power transmitter and at least one of the applied standards. Therefore, step S2001 can be omitted, and the quality factor value at a specific frequency can be measured in step S2003.

[0494] The wireless power transmitter can measure a second quality factor value at a second frequency greater than the first frequency in the operating frequency band (S2003).

[0495] The wireless power transmitter can compare the first quality factor value with the second quality factor value (S2005).

[0496] In one implementation, the first frequency may be the operating frequency of the maximum quality factor value (peak Q factor value). In step S2005, a FOD status data packet may be received during the negotiation phase, the first frequency may be confirmed, and the first quality factor value corresponding to the confirmed first frequency may be compared with the second quality factor value corresponding to a second frequency greater than the first frequency.

[0497] In another embodiment, the first frequency can be 100 kHz. Since the wireless power transmitter and receiver can measure, transmit, and receive reference quality factor values ​​with the frequency set to 100 kHz, the first frequency can be 100 kHz.

[0498] As a result of the comparison, if the first quality factor value is greater than the second quality factor value, the wireless power transmitter can determine that the wireless power receiver is aligned and arranged in the charging area (S2007). Here, the high coupling coefficient between the transmitting resonant coil (primary coil) and the receiving resonant coil (secondary coil) indicates that the wireless power transmitter is well aligned.

[0499] As a result of the comparison in step S2005, if the second quality factor value is greater than the first quality factor value, the wireless power transmitter can determine that there is a foreign object in the charging area and that there is an misaligned wireless power receiver (S2009).

[0500] In another embodiment, as a result of the comparison in step S2005, if the first quality factor value is greater than the second quality factor value, it can be determined that only foreign matter exists in the charging area.

[0501] When a foreign object is present, the quality factor corresponding to the second frequency can be greater than the quality factor corresponding to the first frequency compared to the state where the wireless power receiver is misaligned. A foreign object with a small impact can have a quality factor similar to that of an misaligned receiver, but the difference between the quality factor measured when a foreign object with a relatively large impact is present and the quality factor measured when an misaligned receiver is present can be relatively large.

[0502] Upon detecting the presence of a foreign object or an misaligned wireless power receiver, the wireless power transmitter according to the embodiment may stop power transmission and output a predetermined alarm signal indicating the presence of a foreign object or an misaligned wireless power receiver.

[0503] After outputting an alarm signal, the wireless power transmitter can enter a selection phase after a predetermined waiting time, thereby rescanning the receiver. The waiting time before entering the selection phase can be determined by the time required for the user to remove foreign objects from the charging area or for the user to properly reposition the misaligned wireless power receiver.

[0504] According to another embodiment, the wireless power transmitter can measure the quality factor values ​​corresponding to a first frequency and a second frequency before entering the selection phase, and compare the quality factor values ​​to check whether foreign objects have been removed from the charging area. If the foreign objects have been removed, the wireless power transmitter can enter the selection phase.

[0505] According to another embodiment, the wireless power transmitter can measure the quality factor values ​​corresponding to a first frequency and a second frequency before entering the selection phase, and compare the quality factor values ​​to check whether the wireless power receiver is aligned. If the wireless power receiver is aligned, the wireless power transmitter can enter the selection phase.

[0506] Although the wireless power transmitter according to the embodiment can Figure 2 Steps 2701 to 2709 are performed in the selection phase 210, but this is only an example and steps 2701 to 2709 can be performed in any phase that precedes the negotiation phase 240 (e.g., selection phase 210, ping phase 220, and identification and configuration phase 230).

[0507] According to another embodiment, the wireless power transmitter can... Figure 2 Steps 2701 to 2709 are performed in the power transmission phase 260. In this case, when performing power control using operating frequency control, the wireless power transmitter can measure the quality factor value corresponding to the frequency and compare the quality factor values ​​to determine whether there is a foreign object.

[0508] According to another embodiment, a wireless power transmitter can determine (or acquire) the peak frequency of the quality factor (FGF) for measuring the maximum FGF value within a predetermined operating frequency band (S2001, S2003). Frequencies within the predetermined operating frequency band (or a specific frequency band) can be scanned to find the operating frequency for measuring the maximum FGF value. The wireless power transmitter can receive a FOD status data packet including a reference peak frequency from a wireless power receiver and compare the reference peak frequency with the acquired FGF peak operating frequency to determine the presence of a foreign object. A direct comparison with the reference peak frequency can be performed, or a threshold frequency can be determined considering factors such as transmission coils, design, and product tolerances, and the acquired FGF peak operating frequency can be compared with the threshold frequency.

[0509] Figure 21 It is shown that... Figure 20 A block diagram of the structure of the FOD device corresponding to the implementation method.

[0510] Reference Figure 21 The FO detection device 2100 may include a first quality factor measurement unit 2110, a second quality factor measurement unit 2120, a detector 2130, an alarm unit 2140, and a controller 2150. In another embodiment, the first quality factor measurement unit and the second quality factor measurement unit may be integrated into a single module or device. In this case, the same measurement unit can measure the first quality factor value and the second quality factor value according to the operating frequency control of the controller 2150. Alternatively, the same measurement unit can measure the maximum quality factor value according to the operating frequency control of the controller, and store the peak quality factor operating frequency corresponding to the maximum quality factor value in a memory.

[0511] The first quality factor measurement unit 2110 can measure the first quality factor value corresponding to a first frequency in a predetermined operating frequency band.

[0512] The second quality factor measurement unit 2120 can measure a second quality factor value corresponding to a second frequency in a predetermined operating frequency band. Here, the second frequency may be greater than the first frequency, and the difference between the first frequency and the second frequency may be determined based on the bandwidth of the operating frequency band, but is not limited thereto. For example, the first frequency and the second frequency may be the lower limit frequency and the upper limit frequency of the operating frequency band.

[0513] Detector 2130 can determine the presence of foreign matter in the charging area based on a first quality factor value and a second quality factor value. Alternatively, the presence of foreign matter in the charging area can be determined based on the peak operating frequency of the quality factor and a reference peak operating frequency of the quality factor received from the wireless power receiving unit.

[0514] For example, if the second quality factor is greater than the first quality factor, detector 2130 can determine that there is a foreign object or an misaligned wireless power receiver in the charging area. Conversely, if the second quality factor is less than the first quality factor, detector 2130 can determine that there is no foreign object or an misaligned wireless power receiver in the charging area.

[0515] In another example, if the second quality factor is greater than the first quality factor by a predetermined reference value, detector 2130 can determine that a foreign object or an misaligned wireless power receiver is present in the charging area. Conversely, if the first quality factor is greater than the second quality factor, or if the difference between the second and first quality factors is less than a predetermined reference value, detector 2130 can determine that an aligned wireless power receiver is present.

[0516] In another example, detector 2130 can determine whether there is a foreign object or an misaligned wireless power receiver in the charging area based on the rate of change of the quality factor value according to the frequency variation in the operating band.

[0517] Although the rate of change can be calculated by dividing the value obtained by subtracting the first quality factor from the second quality factor by the first quality factor, the implementation is not limited to this, and any formula capable of calculating the rate of change of the quality factor according to the frequency can be used.

[0518] If the calculated rate of change is greater than 0 or equal to or greater than a first threshold with a predetermined positive value, the detector 2130 can determine that there is a foreign object or an misaligned wireless power receiver in the charging area.

[0519] Conversely, if the calculated rate of change is less than 0 or equal to or less than a second threshold with a predetermined negative value, the detector 2130 can determine that the aligned wireless power receiver is arranged in the charging area.

[0520] If a foreign object or an misaligned wireless power receiver is detected, the detector 2130 can send the detection result to the controller 2150.

[0521] The alarm unit 2140, under the control of the controller 2150, can output a predetermined alarm signal via an alarm element indicating the presence of a foreign object or an misaligned wireless power receiver in the charging area. Here, the alarm element may include, but is not limited to, a buzzer, an LED light, a vibrating element, and an LCD display.

[0522] When a foreign object or misaligned wireless power receiver is detected, the controller 2150 according to the embodiment can control... Figure 20The power transmission unit 2160 is configured to stop power transmission if power is currently being transmitted, and the control alarm unit 2140 is configured to output a predetermined alarm signal indicating that a foreign object has been placed or that the wireless power receiver is misaligned.

[0523] After outputting an alarm signal, the controller 2150 can enter the selection phase after waiting for a predetermined time and scan the receiver again.

[0524] The waiting time before entering the selection phase can be determined by the time required for the user to remove the foreign object from the charging area or for the user to properly reposition the misaligned wireless power receiver.

[0525] According to another embodiment, the controller 2150 can control the first quality factor measurement unit 2110 to the second quality factor measurement unit 2120 to measure quality factor values ​​corresponding to the first frequency and the second frequency before entering the selection phase, and compare the measured first quality factor value to the second quality factor value to check whether foreign objects have been removed from the charging area. If foreign objects have been removed, the controller 2150 can enter the selection phase.

[0526] According to another embodiment, the controller 2150 can perform control to measure quality factor values ​​corresponding to a first frequency and a second frequency before entering the selection phase, and check whether the wireless power receiver is properly aligned based on the measured first to second quality factor values. If the wireless power receiver is properly aligned, the controller 2150 can enter the selection phase.

[0527] In another implementation, the foreign object detection phase can be performed during the selection phase, i.e., before the ping phase. In this case, if a foreign object is detected during the selection phase, the wireless power transmitter can enter the selection phase without entering the ping phase.

[0528] If power is being transmitted to the wireless power receiver, that is... Figure 2 If a foreign object is detected during the power transmission phase 260, the controller 2150 according to another embodiment can temporarily stop the power transmission and output a predetermined alarm signal indicating that a foreign object has been detected. When the detected foreign object has been removed while the alarm signal is being output, the controller 2150 can perform control to resume the power transmission.

[0529] Figure 22 This is a flowchart illustrating a FOD method based on a quality factor value according to another embodiment.

[0530] Reference Figure 22The wireless power transmitter can divide a predetermined operating frequency band into frequencies from the first to the Nth, each with a predetermined frequency interval (S2201). Here, the operating frequency band can be roughly divided into a lower limit band, an intermediate band, and an upper limit band. It should be noted that the size of each band can vary according to user settings. For example, if the operating frequency band is from 100kHz to 210kHz and the frequency interval used to distinguish specific frequencies within the operating frequency band is set to 10kHz, the operating frequency band can be divided into frequencies from the first to the twelfth. Here, frequencies from the first to the third can belong to the lower limit band (100kHz to 130kHz), frequencies from the fourth to the ninth can belong to the intermediate band (130kHz to 180kHz), and frequencies from the tenth to the twelfth can belong to the upper limit band (180kHz to 210kHz). This is merely an example, and it should be noted that different operating frequency bands and frequency intervals can be set according to the settings and configuration of the wireless power transmitter and at least one of the applied standards.

[0531] The wireless power transmitter can calculate the average value a1 (S2203) of the quality factor measured at frequencies from (N-K+1) to N, which are included in the upper limit frequency band.

[0532] In addition, the wireless power transmitter can calculate the average value a2 of the quality factor measured at the first frequency to the kth frequency included in the lower limit frequency band (S2205).

[0533] The wireless power transmitter can compare a1 with a2 (S2207).

[0534] If the average quality factor a2 of the lower frequency band is greater than the average quality factor a1 of the upper frequency band, the wireless power transmitter can determine that the aligned wireless power receiver is arranged in the charging region (S2209). Here, the high coupling coefficient between the transmitting resonant coil (primary coil) and the receiving resonant coil (secondary coil) indicates that the wireless power transmitter is well aligned.

[0535] As a result of the comparison in step 2207, if a2 is less than or equal to a1, the wireless power transmitter can determine that a foreign object or an misaligned wireless power receiver is located in the charging area (S2211).

[0536] The wireless power transmitter can output a predetermined alarm signal (S2213) indicating that a foreign object or misaligned wireless power receiver has been placed in the charging area.

[0537] Although the wireless power transmitter according to the embodiment can Figure 2Steps 2201 to 2213 are performed in the selection phase 210, but this is only an example, and steps 2701 to 2709 can be performed in any phase that precedes the negotiation phase 240 (e.g., selection phase 210, ping phase 220, and identification and configuration phase 230).

[0538] According to another embodiment, the wireless power transmitter can... Figure 2 In the power transmission phase 260, steps 2201 to 2213 are performed. In this case, when performing power control using operating frequency control, the wireless power transmitter can measure the quality factor value corresponding to the frequency. Furthermore, the wireless power transmitter can use the measured quality factor value corresponding to the frequency to calculate the average quality factor of the upper frequency band and the average quality factor of the lower frequency band, and compare the average quality factor values ​​to determine whether foreign matter is present.

[0539] Despite Figure 21 In one implementation, the average quality factor a1 of the upper frequency band and the average quality factor a2 of the lower frequency band are compared to determine the presence of foreign objects. However, this is merely an example. Furthermore, according to another implementation, a wireless power transmitter can determine whether a foreign object or an misaligned wireless power receiver is located in the charging area based not only on whether the average quality factor increases or decreases with frequency changes, but also on the increase / decrease of the average quality factor. For example, if the value obtained by subtracting a1 from a2 is negative and the absolute value of the difference between a2 and a1 exceeds a predetermined threshold, the wireless power transmitter can determine that a foreign object or an misaligned wireless power receiver is located in the charging area.

[0540] Figure 23 It is shown that... Figure 22 A block diagram of the structure of the FOD device corresponding to the implementation method.

[0541] Reference Figure 23 The FOD device 2300 may include an operating frequency division unit 2310, a quality factor measurement unit 2320, an average value calculator 2330, a detector 2340, an alarm unit 2350, and a controller 2360.

[0542] The operating frequency division unit 2310 can divide a predefined operating frequency band into a first to an Nth frequency at predetermined frequency intervals where quality factor values ​​will be measured, and classify the divided frequencies into a lower limit band, an intermediate band, and an upper limit band. Here, the lower limit band and the number of frequencies to be measured included in the lower limit band can be predefined and maintained in a predetermined recording area. It should be noted that the operating frequency band, frequency interval, and the number of frequencies to be measured included in the lower / upper limit band can be changed via a predetermined user interface installed in the wireless power transmitter or via a wired or wireless communication network connected to an external server connected to the wireless power transmitter.

[0543] The quality factor measurement unit 2320 can measure the quality factor values ​​corresponding to the first frequency to the Nth frequency. According to the embodiment, the quality factor measurement unit 2340 can measure only the quality factor values ​​corresponding to the frequencies to be measured, which are included in the lower and upper frequency bands.

[0544] The Average Calculator 2330 can calculate the average value a2 of the quality factor measured for the lower limit frequency band and the average value a1 of the quality factor measured for the upper limit frequency band.

[0545] Detector 2340 can detect foreign objects or misaligned wireless power receivers arranged in the charging area based on a1 and a2, and send the detection results to controller 2360. For example, if the value obtained by subtracting a2 from a1 is positive, that is, if the quality increases with the average value of the numerical value as the frequency in the operating band increases, it can be determined that there is a foreign object or misaligned wireless power receiver in the charging area. Conversely, if the value obtained by subtracting a2 from a1 is negative, that is, if the quality decreases with the average value of the numerical value as the frequency in the operating band increases, it can be determined that there is an aligned wireless power receiver in the charging area.

[0546] In another example, detector 2340 may consider, in addition to whether the average quality factor increases or decreases according to frequency changes in the operating band, the increase / decrease of the average quality factor to determine whether a foreign object or misaligned wireless power receiver is present in the charging area. For example, if the value obtained by subtracting a1 from a2 is negative and the absolute value of the difference between a2 and a1 exceeds a predetermined threshold, the wireless power transmitter can determine that a foreign object or misaligned wireless power receiver is located in the charging area.

[0547] The alarm unit 2350, under the control of the controller 2360, can output a predetermined alarm signal via an alarm element indicating the presence of a foreign object in the charging area or the misalignment of a wireless power receiver located in the charging area. Here, the alarm element may include, but is not limited to, a buzzer, an LED light, a vibrating element, and an LCD display.

[0548] Figure 24a to Figure 24d It is shown Figure 20 to Figure 23 The experimental results are presented as a graph illustrating the logical basis of the implementation method.

[0549] As by Figure 24a As indicated by reference numeral 2411, if only the first receiver is arranged in the charging area, the quality factor measured by the wireless power transmitter decreases with increasing frequency in the operating band (100 kHz to 210 kHz). Conversely, as indicated by reference numeral 2412, if both the first receiver and the foreign object FO4 are arranged in the charging area, the quality factor measured by the wireless power transmitter increases with increasing frequency in the operating band.

[0550] As shown by reference numeral 2413 in the attached figure, it can be seen that when only the first receiver is arranged in the charging area, the quality factor measured at the operating frequency of 100 kHz is 44, and the quality factor measured at the operating frequency of 210 kHz is 40. Conversely, it can be seen that when both the first receiver and the foreign object FO4 are arranged in the charging area, the quality factor measured at the operating frequency of 100 kHz is 27.1, and the quality factor measured at the operating frequency of 210 kHz is 30.5. Here, FO4 represents a standard foreign object as defined in the WPC standard.

[0551] Figure 24a The experimental results shown indicate that when the wireless power receiver is aligned and positioned in the charging area, the quality factor decreases with increasing frequency in the operating band; however, when a foreign object is positioned in the charging area, the quality factor increases with increasing frequency in the operating band.

[0552] Figure 24b It shows the combination of and Figure 24a Experimental results of second receivers produced by different manufacturers of the first receiver.

[0553] As by Figure 24aAs indicated by reference numeral 2421, if only the second receiver is arranged in the charging area, the quality factor measured by the wireless power transmitter decreases with increasing frequency in the operating band (100 kHz to 210 kHz). Conversely, as indicated by reference numeral 2422, if both the second receiver and the foreign object FO4 are arranged in the charging area, the quality factor measured by the wireless power transmitter increases with increasing frequency in the operating band.

[0554] As shown by reference numeral 2423 in the attached figure, it can be seen that when only the second receiver is arranged in the charging area, the quality factor measured at the operating frequency of 100 kHz is 39.5, and the quality factor measured at the operating frequency of 210 kHz is 31.1. Conversely, it can be seen that when both the second receiver and the foreign object FO4 are arranged in the charging area, the quality factor measured at the operating frequency of 100 kHz is 24.9, and the quality factor measured at the operating frequency of 210 kHz is 26.1.

[0555] Figure 24b The experimental results shown indicate that when the wireless power receiver is aligned and positioned within the charging area, the quality factor decreases with increasing frequency in the operating band. However, when a foreign object is placed within the charging area, the quality factor increases with increasing frequency in the operating band. Figure 24a The experimental results were the same.

[0556] Figure 24c The quality factor values ​​measured in the operating band are shown for foreign matter FO4 and 10-cent coins as defined in the standard.

[0557] Figure 24c Reference numerals 2431 and 2432 illustrate the variation pattern of the quality factor values ​​measured for a 10-cent coin and FO4. As can be seen from reference numerals 2431 and 2432, if a foreign object other than the wireless power receiver is placed in the charging area, the quality factor value increases with increasing frequency in the operating band.

[0558] In the case of a 10-cent coin, some quality factor values ​​measured in the middle frequency band are greater than those measured in the upper frequency band. Therefore, in order to minimize erroneous determinations based on incorrect measurement results, such as... Figure 22 to Figure 23 As described, the presence of foreign objects can be determined based on the average quality factor calculated in each of the lower and upper frequency bands.

[0559] Figure 24d Experimental results are shown for a third receiver manufactured by a different manufacturer than the first to second receivers.

[0560] As by Figure 24d As shown by reference numeral 2441, if only the third receiver is placed in the charging area, the quality decreases with increasing frequency. However, as shown by reference numerals 2442 to 2443, if a foreign object (e.g., a FO4 or 10-cent coin) is also placed in the charging area, the quality increases with increasing frequency.

[0561] Figure 24e Experimental results for a standard wireless power transmitter and a standard wireless power receiver module used for product certification are shown.

[0562] As by Figure 24e As shown by reference numeral 2452 in the attached figure, it can be seen that if the standard wireless power receiver module is in the standard wireless power transmitter, the quality factor decreases with increasing frequency in the operating band. Of course, as shown by reference numeral 2451, it can be seen that even when nothing is placed in the charging area of ​​the standard wireless power transmitter, the quality factor decreases with increasing frequency in the operating band. However, as shown by reference numeral 2453, it can be seen that the quality factor measured when the standard wireless power receiver module is placed in the charging area of ​​the standard wireless power transmitter decreases to a certain extent compared to the case where nothing is placed in the charging area.

[0563] Figure 25 This is a view showing the relationship between the quality factor value and the peak frequency of the maximum quality factor, depending on the placement of the foreign object and the wireless power receiver in the charging area of ​​the wireless power transmitter.

[0564] Figure 25 The table shown illustrates the shift in the peak frequency of the maximum quality factor when both the wireless power receiver and a foreign object are placed in the charging area, compared to the case where only the wireless power receiver is placed in the charging area. The peak frequency of the maximum quality factor can then be used to determine the presence of a foreign object.

[0565] A wireless power transmitter can receive information about the peak frequency of a reference quality factor from a wireless power receiver and determine a threshold frequency based on the received information. Here, coil design, circuit characteristics, tolerances, etc., can be considered in determining the threshold frequency. The wireless power transmitter can then compare the threshold frequency with... Figure 25 The peak frequencies are compared to determine the presence of foreign objects.

[0566] Figure 26 This is a view showing the state transition process of detecting foreign objects in a foreign object detection device according to an embodiment.

[0567] ReferenceFigure 26 When an object is detected in selection phase 2610, the foreign object detection device can measure the quality factor of the resonant circuit at multiple operating frequencies (S2601). Although the number of operating frequencies for measuring the quality factor is 2 to 6, the implementation is not limited to this, and the number of operating frequencies can be increased. The operating frequencies for measuring the quality factor can be selected within a predetermined operating frequency range to have predetermined frequency intervals. For example, if the operating frequency range of the foreign object detection device is from 100kHz to 220kHz and the number of operating frequencies is 5, then the values ​​of the operating frequencies for measuring the quality factor can be 100kHz, 130kHz, 160kHz, 190kHz, and 220kHz.

[0568] The foreign object detection device can determine whether a foreign object has been placed, i.e., whether a foreign object exists, based on the measured quality factor value (S2602).

[0569] For example, when the quality factor increases with increasing operating frequency, the foreign object detection device can determine that a foreign object is present in the charging area. Conversely, when the quality factor decreases with increasing operating frequency, the foreign object detection device can determine that no foreign object is present in the charging area.

[0570] In another example, the foreign object detection device can calculate the change in the quality factor value at adjacent operating frequencies, and determine the presence of a foreign object in the charging area when the average of the calculated changes exceeds a predetermined reference value. For example, the reference value can be 0, but is not limited to this. Here, adjacent operating frequencies refer to the two closest operating frequencies among the operating frequencies used to measure the quality factor value.

[0571] In another example, the foreign object detection device can calculate the slope of the quality factor values ​​at adjacent operating frequencies, and determine the presence of a foreign object in the charging area when the average of the calculated slopes exceeds a predetermined first reference value. Conversely, it can determine the absence of a foreign object in the charging area when the average of the calculated slopes is equal to or less than a predetermined second reference value. The first and second reference values ​​may be different, and in this case, the first reference value is greater than the second reference value.

[0572] When the determination of whether a foreign object exists is terminated, the foreign object detection device can enter the ping phase 2620.

[0573] During the ping phase 2620, the foreign object detection device can periodically send predetermined power signals, such as digital ping, to identify the wireless power receiver.

[0574] When a signal strength indicator is received during the ping phase 2620, the foreign object detection device can enter the identification and configuration phase 2630 and set various configuration parameters for the identified wireless power receiver.

[0575] When the identification and configuration of the wireless power receiver is terminated, the foreign object detection device may enter the negotiation phase 2640 and receive a foreign object detection (FOD) status data packet from the identified wireless power receiver (S2603). Here, the foreign object detection status may include a reference quality factor value.

[0576] The foreign object detection device can send a NAK response signal or an ACK response signal to the identified wireless power receiver based on the determination result in step 2602 (S2604). At this time, the foreign object detection device can determine the threshold (threshold range) for determining the presence of a foreign object without relying on the received foreign object detection status data packet. As a result of the determination in step 2602, if a foreign object is present, the foreign object detection device can send a NAK response signal to the identified wireless power receiver and transition to the selection phase 2610. At this time, the foreign object detection device can stop power transmission and output a predetermined warning alarm indicating that a foreign object has been detected.

[0577] For example, as a result of the determination in step 2602, if no foreign object is found, the foreign object detection device can send an ACK response signal and then transition to the power transmission stage 2650. In another example, as a result of the determination in step 2602, if no foreign object is found, the foreign object detection device can... Figure 2 The calibration phase 250 transitions to the power transmission phase 2650.

[0578] The foreign object detection device can enter the power transfer phase 2650 to begin wireless charging of the wireless power receiver.

[0579] The foreign object detection device, having transitioned to selection phase 2610 based on foreign object detection, can periodically measure the quality factor of the resonant circuit at multiple operating frequencies and determine whether a foreign object has been removed based on the measured quality factor. Upon determining that the foreign object has been removed, the foreign object detection device can proceed to power transmission phase 2650 to restore power transmission to the wireless power receiver. Conversely, if the foreign object is not removed within a predetermined time after transitioning to selection phase 2610 based on foreign object detection, the foreign object detection device can output a predetermined warning alarm indicating that the detected foreign object has not been removed.

[0580] According to another embodiment, the foreign object detection device can also send a predetermined foreign object (FO) presence status data packet to the wireless power receiver, which includes FO status information corresponding to the determination result in step 2601. For example, if the FO status information is "0", this may indicate that no foreign object has been detected, and if the FO status information is "1", this may indicate that a foreign object has been detected, but is not limited thereto.

[0581] In another embodiment, step S2603 can be omitted.

[0582] Figure 27 This is a view showing the structure of a FOD status data packet message according to another embodiment.

[0583] Reference Figure 27 The FOD status packet message 2700 may have a length of 2 bytes and includes a first data field 2701 with a length of 6 bits, a mode field 2702 with a length of 2 bits, and a reference quality factor value 2703 with a length of 1 byte.

[0584] As indicated by reference numeral 2704, if the mode field 2702 is set to the binary value "00", all bits of the first data field 2701 are set to 0, and the reference quality factor value measured and determined in the state of powerlessness of the wireless power receiver is recorded in the reference quality factor value field 2703. Conversely, if the mode field 2702 is set to the binary value "01", the operating frequency having a quality factor value that is 5% lower than the reference quality factor value measured in the state of powerlessness of the wireless power receiver is recorded in the first data field 2701. The reference quality factor value measured and determined in the state of powerlessness of the wireless power receiver can be recorded in the first data field 2701. For example, refer to... Figure 20 The receiver's reference quality factor can be 39.5, measured at an operating frequency of 100 kHz. At this point, a quality factor 5% lower than the reference quality factor is 37.525. Therefore, the operating frequency for a quality factor 5% lower than the reference quality factor can be any value between 120 kHz and 130 kHz.

[0585] Despite Figure 27 In this implementation, the value corresponding to the operating frequency of a quality factor value that is 5% lower than the reference quality factor value is recorded in the first data field 2701. However, this is exemplary and values ​​other than 5% can be set according to the design of those skilled in the art, for example, 7%.

[0586] Figure 28 This is a view showing the state transition process of detecting foreign objects in a foreign object detection device according to an embodiment.

[0587] Reference Figure 28 When an object is detected in selection phase 2810, the foreign object detection device can measure the quality factor of the resonant circuit at multiple operating frequencies, including the lower limit frequency of the operating frequency band (S2801). Although the number of operating frequencies for measuring the quality factor is 2 to 8, the implementation is not limited to this, and the number of operating frequencies can be increased. The operating frequencies for measuring the quality factor can be selected within a predetermined operating frequency range to have predetermined frequency intervals. The implementation is not limited to this, and the operating frequencies can be arbitrarily selected within the operating frequency range. For example, the operating frequency range of the foreign object detection device can be from 100kHz to 220kHz. For example, if the lower limit frequency is 100kHz and the number of operating frequencies is 7, the values ​​of the operating frequencies for measuring the quality factor can be 100kHz, 120kHz, 140kHz, 160kHz, 180kHz, 200kHz, and 220kHz.

[0588] The foreign object detection device can record the quality factor of each operating frequency measured in a predetermined recording area.

[0589] If the quality is terminated due to numerical measurement, the foreign object detection device can enter the ping phase 2820.

[0590] During the ping phase 2820, the foreign object detection device can periodically send predetermined power signals, such as digital ping, to identify the wireless power receiver.

[0591] When a signal strength indicator is received during the ping phase 2820, the foreign object detection device can enter the identification and configuration phase 2830 to identify the wireless power receiver and set various configuration parameters for the identified wireless power receiver.

[0592] If the identification and configuration of the wireless power receiver terminates, the foreign object detection device may enter negotiation phase 2840 to receive a FOD status data packet from the identified wireless power receiver (S2802). Here, the foreign object detection status data packet may include information about the operating frequency of a quality factor that is 5% lower than the reference quality factor (hereinafter referred to as the threshold frequency for ease of description).

[0593] The foreign object detection device can compare the quality factor value Q1 corresponding to the lower limit frequency measured in step 2801 with the quality factor value Q2 measured at an operating frequency greater than the threshold frequency to determine whether a foreign object is present (S2803). Here, Q2 can be the quality factor value with the maximum value among the quality factor values ​​measured at an operating frequency greater than the threshold frequency.

[0594] If Q2 is greater than Q1, the foreign object detection device can determine that a foreign object has been placed in the charging area. Conversely, if Q2 is less than Q1, the foreign object detection device can determine that no foreign object has been placed in the charging area.

[0595] According to another embodiment, the foreign object detection device can determine (or estimate) the quality factor value corresponding to a threshold frequency based on the quality factor value of each operating frequency measured in step 2801. For example, if the plurality of operating frequencies used to measure the quality factor value in step 2801 includes a frequency that is the same as the threshold frequency, then the quality factor value measured at the operating frequency becomes the quality factor value measured at the threshold frequency. However, if the plurality of operating frequencies used to measure the quality factor value in step 2801 does not include a frequency that is the same as the threshold frequency, the quality factor value corresponding to the threshold frequency can be estimated based on at least one quality factor value measured at the operating frequency closest to the threshold frequency. For example, a linear function can be obtained using the quality factor values ​​measured at the two operating frequencies closest to the threshold frequency, and the quality factor value corresponding to the threshold frequency can be estimated by substituting the threshold frequency into the obtained linear function, but is not limited thereto.

[0596] The foreign object detection device can send a NAK response signal or an ACK response signal to the identified wireless power receiver based on the determination result in step 2803. At this time, the foreign object detection device can determine the threshold (threshold range) for determining the presence of a foreign object without relying on the received foreign object detection status data packet. As a result of the determination in step 2803, if a foreign object is present, the foreign object detection device can send a NAK response signal to the identified wireless power receiver and transition to selection phase 2810. At this time, the foreign object detection device can stop power transmission and output a predetermined warning alarm indicating that a foreign object has been detected.

[0597] For example, as a result of the determination in step 2802, if no foreign object is found, the foreign object detection device can send an ACK response signal and then transition to the power transmission stage 2850. In another example, as a result of the determination in step 2803, if no foreign object is found, the foreign object detection device can... Figure 2 The calibration phase 250 transitions to the power transmission phase 2850.

[0598] The foreign object detection device can enter the power transfer phase 2850 to begin wireless charging of the wireless power receiver.

[0599] The foreign object detection device, having transitioned to the selection phase 2810 based on foreign object detection, can periodically measure the quality factor of the resonant circuit at multiple operating frequencies and determine whether a foreign object has been removed based on the measured quality factor. Upon determining that the foreign object has been removed, the foreign object detection device can enter the power transmission phase 2850 and resume power transmission to the wireless power receiver. Conversely, if the foreign object is not removed within a predetermined time after transitioning to the selection phase 2810 based on foreign object detection, the foreign object detection device can output a predetermined warning alarm indicating that the detected foreign object has not been removed.

[0600] According to another embodiment, the foreign object detection device can also send a predetermined foreign object (FO) presence status data packet to the wireless power receiver, which includes FO status information corresponding to the determination result in step 2801. For example, if the FO status information is "0", this may indicate that no foreign object has been detected, and if the FO status information is "1", this may indicate that a foreign object has been detected, but is not limited thereto.

[0601] Figure 29 This is a view showing the state transition process of detecting foreign objects in a foreign object detection device according to an embodiment.

[0602] When an object is detected in the selection phase 2910, the foreign object detection device according to the embodiment can measure the quality factor of the resonant circuit at multiple operating frequencies (S2901).

[0603] Upon receiving a FOD status data packet including a threshold phase, the foreign object detection device can identify at least two operating frequencies that are greater than or equal to the threshold frequency and extract the quality factor value measured at the identified operating frequencies (S2903).

[0604] The foreign object detection device can compare a quality factor value corresponding to an operating frequency greater than or equal to a threshold frequency to determine whether a foreign object is present (S2904). For example, if the quality factor value increases with increasing operating frequency, the foreign object detection device can determine that a foreign object is present in the charging area. Conversely, if the quality factor value decreases with increasing operating frequency, the foreign object detection device can determine that no foreign object is present in the charging area.

[0605] When an object is detected during the selection phase, the foreign object detection device according to another embodiment can scan the quality factor value in the operating frequency band.

[0606] Here, the operating frequency band can be divided into multiple non-overlapping lower frequency regions. For example, the operating frequency band can be divided into a first frequency region including the lower limit frequency and a second frequency region including the upper limit frequency.

[0607] For example, if the operating frequency band is from 100kHz to 200kHz, then the first frequency region is from 100kHz to 150kHz, including the lower limit frequency of 100kHz, and the second frequency region is from 151kHz to 200kHz, including the upper limit frequency of 200kHz.

[0608] The foreign object detection device can scan the quality factor value as the frequency changes in a predetermined frequency unit within a first frequency region, and identify the operating frequency (first frequency) at which the highest quality factor value is measured. Additionally, the foreign object detection device can scan the quality factor value as the frequency changes in a second frequency region, and identify the operating frequency (second frequency) at which the highest quality factor value is measured. The foreign object detection device can compare the quality factor value Q4 corresponding to the first frequency and the quality factor value Q5 corresponding to the second frequency to determine whether a foreign object is present in the charging region. For example, if Q5 is greater than Q4, the foreign object detection device can determine that a foreign object is present. Conversely, if Q5 is less than Q4, the foreign object detection device can determine that no foreign object is present.

[0609] Figure 30 This is a view showing the structure of a FOD status data packet message according to another embodiment.

[0610] Reference Figure 30 The FOD status data packet message 3000 can be 2 bytes long and includes a reserved field 3001 with a length of 6 bits, a pattern field 3002 with a length of 2 bits, a first data field 3003, and a second data field value 3004. Although in Figure 30 In this implementation, the first data field 3003 has a length of 3 bits and the second data field 3004 has a length of 5 bits, but this is only an example and the implementation is not limited to this. All bits of the reserved field 3001 are set to 0.

[0611] As indicated by reference numeral 3005, if mode field 3002 is set to the binary value "00", the reference quality factor value measured and determined when the wireless power receiver is powered off is recorded in the first data field 3003 and the second data field 3004. Conversely, if mode field 3002 is set to the binary value "01", information about the threshold frequency can be recorded in the first data field 3003, and information about the ratio of the quality factor value corresponding to the lower limit frequency to the quality factor value corresponding to the threshold frequency can be recorded in the second data field 3004.

[0612] This disclosure may also have the following configurations:

[0613] 1. A method for detecting foreign objects in a wireless power transmitter, the wireless power transmitter including a resonant circuit for wirelessly transmitting power, the method comprising:

[0614] Detect objects placed in the charging area;

[0615] The quality factor of the resonant circuit is measured when an object is detected.

[0616] Send sensing signals to identify the wireless power receiver;

[0617] The threshold for detecting foreign objects is determined based on a reference quality factor received from the identified wireless power receiver; and

[0618] The measured quality factor value is compared with the determined threshold to determine the presence of foreign matter.

[0619] The threshold is determined by applying a weight that is increased based on the reference quality factor.

[0620] 2. The method according to Scheme 1, wherein the weight increases linearly or exponentially based on the reference quality factor value.

[0621] 3. The method according to Scheme 2, wherein the threshold is determined by further applying a predefined tolerance and a design factor corresponding to the wireless power transmitter, and the threshold is determined by adding the product of the tolerance and the reference quality factor and the design factor and then subtracting the weight from the summed value.

[0622] 4. The method according to Scheme 1 further includes:

[0623] Once the absence of foreign objects is confirmed, charging of the identified wireless power receiver begins; and

[0624] Upon detection of a foreign object, power transmission through the resonant circuit is stopped, and a predetermined alarm signal indicating that a foreign object has been detected is output.

[0625] 5. The method according to Scheme 4, wherein the method returns to detecting the object placed in the charging area after stopping power transmission.

[0626] 6. The method according to Scheme 5 further includes: comparing the quality factor of the resonant circuit measured after return with a determined threshold to check whether the foreign object has been removed from the charging area.

[0627] 7. The method according to Scheme 5, wherein the stopped power transmission is resumed when it is detected that the foreign object has been removed.

[0628] 8. The method according to Scheme 1, wherein the reference quality factor is received while the reference quality factor is included in the foreign object detection status data packet received during the negotiation phase.

[0629] 9. According to the method of Scheme 1, determining whether a foreign object exists includes:

[0630] When the measured quality factor value exceeds the threshold, it is determined that no foreign matter is present; and

[0631] When the measured quality factor is equal to or less than the threshold, the presence of a foreign object is determined.

[0632] 10. A device for detecting foreign objects, the device comprising:

[0633] A resonant circuit, which includes a resonant capacitor and a resonant inductor;

[0634] A sensing unit configured to detect objects placed in the charging area;

[0635] A measurement unit configured to measure the quality factor of the resonant circuit when an object is detected; and

[0636] The controller is configured to determine a threshold for detecting foreign objects based on a reference quality factor received from an identified wireless power receiver, and to compare the measured quality factor with the determined threshold to determine the presence of a foreign object.

[0637] The threshold is determined by applying a weight that is increased based on the reference quality factor.

[0638] 11. The apparatus according to claim 10, wherein the weight increases linearly or exponentially based on the reference quality factor, and the threshold is determined by adding a predefined tolerance to a product of the reference quality factor and a design factor corresponding to the wireless power transmitter.

[0639] This disclosure may also have the following configurations:

[0640] 1. A method for detecting foreign objects in a wireless power transmitter, the method comprising:

[0641] Measure the first quality factor value at the first frequency;

[0642] The second quality factor value was measured at the second frequency; and

[0643] The presence of foreign matter is determined based on the first quality factor value and the second quality factor value, wherein the second frequency is greater than the first frequency.

[0644] 2. According to the method of Scheme 1, when the second quality factor value is greater than the first quality factor value, it is determined that there is a foreign object, and when the second quality factor value is less than the first quality factor value, it is determined that there is no foreign object.

[0645] 3. According to the method described in Scheme 2, when a foreign object is determined to be present during power transmission, power transmission is temporarily stopped.

[0646] 4. The method according to Scheme 3 further includes: checking whether the foreign object detected during the temporary cessation of power transmission has been removed from the charging area.

[0647] Once it is confirmed that the detected foreign object has been removed from the charging area, the temporarily suspended power transmission is resumed.

[0648] 5. The method according to Scheme 2 further includes:

[0649] Output an alarm signal when a foreign object is detected;

[0650] Check whether the detected foreign object has been removed from the charging area; and

[0651] The selection phase begins when it is confirmed that the foreign object has been removed from the charging area.

[0652] 6. The method according to Scheme 2, wherein when the value obtained by subtracting the first quality factor from the second quality factor exceeds a reference value, it is determined that a foreign object exists in the charging area.

[0653] 7. A method for detecting foreign objects in a wireless power transmitter, the method comprising:

[0654] The average of the first quality factor is calculated based on the quality factor values ​​measured at multiple frequencies in the upper limit of the operating frequency band.

[0655] The average value of the second quality factor is calculated based on quality factor values ​​measured at multiple frequencies within the lower limit of the operating frequency band; and

[0656] The presence of foreign objects in the charging area is determined based on the average value of the first quality factor and the average value of the second quality factor.

[0657] 8. The method according to Scheme 7, wherein when the average value of the first quality factor is greater than the average value of the second quality factor, it is determined that there is a foreign object in the charging area.

[0658] 9. The method according to Scheme 7, wherein when the value obtained by subtracting the average value of the first quality factor from the average value of the second quality factor exceeds a reference value, it is determined that a foreign object exists in the charging area.

[0659] 10. The method according to Scheme 7, wherein when the average value of the first quality factor is greater than the average value of the second quality factor, it is determined that there is a foreign object or an misaligned wireless power receiver in the charging area.

[0660] 11. A wireless power transmitter, comprising:

[0661] A quality factor measurement unit, configured to measure a first quality factor value at a first frequency and a second quality factor value at a second frequency; and

[0662] A detector is configured to determine the presence of a foreign object in the charging area based on the first quality factor value and the second quality factor value.

[0663] The second frequency is greater than the first frequency.

[0664] 12. The wireless power transmitter according to claim 11, wherein the detector determines that a foreign object is present in the charging area when the second quality factor value is greater than the first quality factor value.

[0665] 13. The wireless power transmitter according to claim 11, wherein the detector determines that an misaligned wireless power receiver exists in the charging area when the second quality factor is greater than the first quality factor.

[0666] 14. The wireless power transmitter according to claim 11 further includes an alarm unit configured to output an alarm signal when it is determined that a foreign object is present in the charging area.

[0667] 15. The wireless power transmitter according to claim 14 further includes a controller configured to temporarily stop power transmission when a foreign object is detected in the charging area during power transmission.

[0668] 16. The wireless power transmitter according to claim 15, wherein the controller checks whether a foreign object has been removed from the charging area when power transmission is temporarily stopped, and resumes the temporarily stopped power transmission when the foreign object has been detected as removed.

[0669] 17. The wireless power transmitter according to claim 14, wherein the controller performs control to check whether a foreign object has been removed from the charging area after the alarm signal is output, and enters a selection phase when it is detected that the foreign object has been removed.

[0670] 18. The wireless power transmitter according to claim 11, wherein the detector confirms the presence of a foreign object in the charging region when the value obtained by subtracting the first quality factor from the second quality factor exceeds a predetermined reference value.

[0671] 19. The wireless power transmitter according to claim 11, wherein the detector determines the presence of foreign matter based on the variation pattern of the quality factor value according to the frequency variation.

[0672] 20. The wireless power transmitter according to claim 11, wherein the first frequency and the second frequency are greater than a threshold frequency set in the operating frequency band.

[0673] The method according to the foregoing embodiments can be implemented as code that can be written to a computer-readable recording medium and therefore read by a computer. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, and carrier wave (e.g., data transmission via the Internet).

[0674] Computer-readable recording media can be distributed across multiple computer systems connected to a network, allowing computer-readable code to be written into and executed from them in a distributed manner. Those skilled in the art will understand the functional programs, code, and code segments required to implement the embodiments described herein.

[0675] Those skilled in the art will understand that this disclosure may be implemented in other specific ways besides those set forth herein without departing from its spirit and essential characteristics.

[0676] Therefore, the exemplary embodiments described above should be interpreted in all respects as illustrative rather than restrictive. The scope of this disclosure should be determined by the appended claims and their legal equivalents, not by the foregoing description, and all variations falling within the meaning and scope of the appended claims are intended to be included in the appended claims.

[0677] [Industrial Applications]

[0678] The foreign object detection method according to the embodiment can be used in a wireless charging system to detect foreign objects located between wireless power transmitters using a quality factor value before the ping phase and during the negotiation and power transmission phases.

Claims

1. A method for communicating with a wireless power transmitter, the method comprising: Receives an electrical signal of predetermined strength from the wireless power transmitter; A foreign object detection status data packet, including a pattern bit field, is transmitted from a wireless power receiver to the wireless power transmitter. The pattern bit field indicates whether the foreign object detection status data packet includes a reference peak frequency of the wireless power receiver, wherein the reference peak frequency is pre-assigned to the wireless power receiver. Receive a response from the wireless power transmitter indicating the presence or absence of foreign objects in the charging area. The response is determined based on the peak frequency of the measured power signal and an adaptive threshold frequency adjusted based on the reference peak frequency.

2. The method according to claim 1, wherein, When the mode bit field indicates that the foreign object detection status data packet includes the reference peak frequency, the foreign object detection status data packet also includes the reference peak frequency value of the wireless power receiver.

3. The method according to claim 2, wherein, The reference peak frequency was measured with the wireless power receiver off.

4. The method according to claim 1, wherein, The reference peak frequency is the reference peak frequency of the predicted quantity in the absence of foreign objects.

5. The method according to claim 1, wherein, The reference peak frequency is based on a reference wireless power transmitter pre-assigned to the wireless power receiver, and The adaptive threshold frequency is determined by taking into account at least one of the coil design and circuit characteristics that are different from those of the reference wireless power transmitter.

6. The method according to claim 1, wherein, When the peak frequency of the measured power signal is greater than the adaptive threshold frequency, the response indicates the presence of a foreign object in the charging area.

7. The method according to claim 1, wherein, When the peak frequency of the measured power signal is equal to or less than the adaptive threshold frequency, the response indicates that there are no foreign objects in the charging area.

8. The method according to claim 1, wherein, When a foreign object is present in the charging area, the peak frequency of the power signal shifts from the reference peak frequency.

9. The method according to claim 6, further comprising: If a response indicating the presence of a foreign object in the charging area is received, the reception of wireless power transmitted from the wireless power transmitter is suspended.

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