Method for controlling wireless transmission power and electronic device including same

An electronic device according to an embodiment may include: a wireless charging coil; a power transmission circuit configured to be electrically connected to the wireless charging coil; a wireless communication circuit configured to communicate with an external electronic device; and a control circuit. The control circuit may be configured to: transmit power to an external electronic device; obtain data corresponding to power received by the external electronic device in response to the transmitted power using the wireless communication circuit; obtain power loss based on the obtained data; stop transmitting the power to the external electronic device when the power loss exceeds a first threshold; and stop transmitting the power to the external electronic device according to whether an event related the power loss occurs even when the power loss is lower than the first threshold.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. 119 to Korean Patent Application No. 10-2019-0092954, filed on Jul. 31, 2019, in the Korean Intellectual Property Office, the disclosure of which is herein incorporated by reference in its entirety.

BACKGROUND

One or more embodiments generally relate to a method for controlling wireless transmission power by detecting a foreign object and an electronic device for performing the same.

2) Description of Related Art

Wireless charging technology is a technique using wireless power transmission and reception, which enables power to be wirelessly transferred from a power transmission device to a power reception device without any physical connection between the power reception device and the power transmission device via a charging connector. The power transferred may charge a battery of the power reception device.

SUMMARY

In wireless charging technology, a foreign object detection (FOD) function may be performed to detect whether there is a foreign object between the wireless power transmission device and the wireless power reception device, and to block power transmission from the wireless power transmission device when the foreign object is detected.

When the foreign object is a conductive material (e.g., metallic object or conductive material that is different from those in the power reception device), heat may be excessively generated in the wireless charging device even when the foreign object causes a certain amount of power loss, or heat may be generated due to energy induced in the foreign object.

An electronic device according to an embodiment may include: a housing; a wireless charging coil configured to be disposed in the housing; a power transmission circuit configured to be electrically connected to the wireless charging coil; a wireless communication circuit configured to communicate with an external electronic device; and a control circuit configured to be electrically connected to a power management circuit and the wireless communication circuit, wherein the control circuit may be configured to: transmit power to an external electronic device; obtain data corresponding to power received by the external electronic device in response to the transmitted power using the wireless communication circuit; obtain power loss based on the obtained data; stop transmitting the power to the external electronic device when the power loss exceeds a first threshold; and stop transmitting the power to the external electronic device according to whether an event related the power loss occurs even when the power loss is lower than the first threshold.

DETAILED DESCRIPTION

According to certain embodiments, there may be provided a method and an electronic device for protecting the wireless power transmission device and the wireless power reception device by detecting that a conductive foreign object is interposed between the wireless power transmission device and the wireless power reception device while power is transmitted.

A power transmission device according to certain embodiments may, for user convenience, set a high threshold for power loss that may be used to detect a foreign object. An electronic device according to certain embodiments can detect a conductive foreign object even though power loss due to the conductive foreign object is lower than the threshold, thus improving user convenience and securing safety in wireless charging.

FIG. 2is a block diagram200illustrating the power management module188and the battery189according to an embodiment. Referring toFIG. 2, the power management module188may include charging circuitry210, a power adjuster220, or a power gauge230. The charging circuitry210may charge the battery189by using power supplied from an external power source that is outside the electronic device101. According to an embodiment, the charging circuitry210may select a charging scheme (e.g., normal charging or quick charging) based at least in part on the type of the external power source (e.g., whether the power source is a power outlet, connected via USB, or a wireless charger), magnitude of power that can be supplied from the external power source (e.g., about 20 Watt or more), or an attribute of the battery189, and may charge the battery189using the selected charging scheme. The external power source may be connected with the electronic device101, for example, directly via the connecting terminal178or wirelessly via the antenna module197.

The power adjuster220may generate a plurality of powers having different voltage levels or different current levels by adjusting the voltage level or the current level of the power supplied from the external power source or the battery189. The power adjuster220may adjust the voltage level or the current level of the power supplied from the external power source or the battery189into a different voltage level or current level appropriate for one or more of the components included in the electronic device101. According to an embodiment, the power adjuster220may be implemented in the form of a low drop out (LDO) regulator or a switching regulator. The power gauge230may measure use state information about the battery189(e.g., capacity, the number of times of charging or discharging, voltage, or temperature of the battery189).

The power management module188may determine, using, for example, the charging circuitry210, the power adjuster220, or the power gauge230, charging state information (e.g., lifetime, over voltage, low voltage, over current, over charge, over discharge, overheat, short, or swelling) related to the charging of the battery189based at least in part on the measured use state information about the battery189. The power management module188may determine whether the state of the battery189is normal or abnormal based at least in part on the determined charging state information. If the state of the battery189is determined to abnormal, the power management module188may adjust the charging of the battery189(e.g., reduce the charging current or voltage, or stop the charging). According to an embodiment, at least some of the functions of the power management module188may be performed by an external control device (e.g., the processor120).

The battery189, according to an embodiment, may include a protection circuit module (PCM)240. The PCM240may perform one or more of various functions (e.g., a pre-cutoff function) to prevent performance deterioration of, or damage to, the battery189. The PCM240, additionally or alternatively, may be configured as at least part of a battery management system (BMS) capable of performing various functions including cell balancing, measurement of battery capacity, count of a number of charging or discharging, measurement of temperature, or measurement of voltage.

According to an embodiment, at least part of the charging state information or use state information regarding the battery189may be measured using a corresponding sensor (e.g., temperature sensor) of the sensor module176, the power gauge230, or the power management module188. According to an embodiment, the corresponding sensor (e.g., temperature sensor) of the sensor module176may be included as part of the PCM240, or may be disposed near the battery189as a separate device.

FIG. 3illustrates a wireless charging system300according to an embodiment.

Referring toFIG. 3, an electronic device302(e.g., the electronic device102ofFIG. 1) according to an embodiment may wireless supply power to an external electronic device301(e.g., the electronic device101ofFIG. 1). The electronic device302may be a wireless power transmitter or an electronic device operating in a power transmission mode. According to an embodiment, the electronic device302may be configured the same as or similar to the electronic device102illustrated inFIG. 1. Alternatively, the external electronic device301may be configured the same as or similar to the electronic device101illustrated inFIG. 1.

According to an embodiment, the electronic device302may be a power transmission device capable of transmitting power to the external electronic device301, and the external electronic device301may be a power reception device capable of receiving power from the electronic device302.

According to an embodiment, the electronic device302may include a power transmission circuit311, a control circuit312, a communication circuit313, or a sensing circuit314.

According to an embodiment, the power transmission circuit311may include a power adapter311ato receive power or electricity supplied externally and to appropriately convert the voltage of input power. The power transmission circuit311may further include a power generation circuit311bto generate power, and/or a matching circuit311cto maximize efficiency between a transmission coil311L and a reception coil321L.

According to an embodiment, the power transmission circuit311may communicate with a first communication circuit323aof the external electronic device301using a frequency the same as or adjacent to that used for by the transmission coil311L for power transmission. The power transmission circuit311may perform operations corresponding to the operation of the first communication circuit313adescribed below.

According to an embodiment, the power transmission circuit311may include a first communication circuit313a, which will be described later, and may communicate with the first communication circuit323aof the external electronic device301through the first communication circuit313a.

According to an embodiment, the electronic device302may include a separate communication circuit to communicate with the external electronic device301using any one of various short-range communication methods, such as Bluetooth, Bluetooth Low Energy (BLE), Wi-Fi, and near-field communication (NFC). The separate communication circuit may correspond to, for example, a second communication circuit313b, which will be described later.

According to an embodiment, the power transmission circuit311may include multiples of components such as the power adapter311a, the power generation circuit311b, the transmission coil311L, or the matching circuit311cto enable power transmission to a plurality of power reception devices (e.g., first external electronic device and second external electronic device).

According to an embodiment, the control circuit312may control the electronic device302overall and may generate and transmit various messages necessary for wireless power transmission to the communication circuit313. In one embodiment, the control circuit312may calculate power (or a power value) to be transmitted to the external electronic device301based on information received from the communication circuit313. In one embodiment, the control circuit312may control the power transmission circuit311to transmit power generated by the transmission coil311L to the external electronic device301. The control circuit312may include a microprocessor or any suitable type of processing circuitry, such as one or more general-purpose processors (e.g., ARM-based processors), a Digital Signal Processor (DSP), a Programmable Logic Device (PLD), an Application-Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), a Graphical Processing Unit (GPU), a video card controller, etc. In addition, it would be recognized that when a general purpose computer accesses code for implementing the processing shown herein, the execution of the code transforms the general purpose computer into a special purpose computer for executing the processing shown herein. Certain of the functions and steps provided in the Figures may be implemented in hardware, software or a combination of both and may be performed in whole or in part within the programmed instructions of a computer. No claim element herein is to be construed under the provisions of 35 U.S.C. § 112(f), unless the element is expressly recited using the phrase “means for.” In addition, an artisan understands and appreciates that a “control circuit,” “processor,” or “microprocessor” may be hardware in the claimed disclosure. Under the broadest reasonable interpretation, the appended claims are statutory subject matter in compliance with 35 U.S.C. § 101.

According to an embodiment, the communication circuit313may include the first communication circuit313aand/or the second communication circuit313b. The first communication circuit313amay communicate with the first communication circuit323aof the external electronic device301, for example, using a frequency that is the same as or adjacent to the frequency used by the transmission coil311L for power transmission.

The first communication circuit313amay communicate with the first communication circuit323ausing the transmission coil311L. Data (or a communication signal) generated by the first communication circuit313amay be transmitted using the transmission coil311L. The first communication circuit313amay transmit the data to the external electronic device301using frequency-shift keying (FSK). According to an embodiment, the first communication circuit313amay communicate with the first communication circuit323aof the external electronic device301by changing the frequency of the power signal transmitted through the transmission coil311L. This way, the first communication circuit313amay communicate with the first communication circuit323aof the external electronic device301by including data in the power signal generated by the power generation circuit311b. For example, the first communication circuit313amay express data by modulating the frequency of the power transmission signal.

The second communication circuit313bmay communicate with a second communication circuit323bof the external electronic device301, for example, using a frequency different from the frequency used by the transmission coil311L for power transmission. This may be referred to as an out-band communication method. For example, the second communication circuit313bmay obtain information about the charging state of the battery (e.g., voltage value after being rectified, rectified voltage value (e.g., Vrec) information, information about current (e.g., Iout) flowing through a coil or a rectifier circuit, various packets, messages, and the like) from the second communication circuit323busing any one of various short-range communication methods, such as Bluetooth, Bluetooth Low Energy (BLE), Wi-Fi, and near-field communication (NFC).

According to an embodiment, the sensing circuit314may include at least one sensor and may detect at least one state of the power transmission device301using the at least one sensor.

According to an embodiment, the sensing circuit314may include at a temperature sensor, a motion sensor, and/or a current (or voltage) sensor, may detect the temperature state of the electronic device302using the temperature sensor, may detect the movement state of the electronic device302using the motion sensor, and may detect the state of an output power signal of the electronic device302, for example, current level, voltage level, or power level, using the current (or voltage) sensor.

According to one embodiment, the current (or voltage) sensor may measure a signal in the power transmission circuit311. The current (or voltage) sensor may measure a signal in at least a portion of the matching circuit311cor the power generation circuit311b. For example, the current (or voltage) sensor may include a circuit to measure a signal at the front end of the coil311L.

According to an embodiment, the sensing circuit314may include a circuit for foreign object detection (FOD). The electronic device302may measure the current and the voltage in the power transmission circuit311using the sensing circuit314and may obtain the level of power transmitted by the electronic device302based on the measured current and voltage. When there is a foreign object between the electronic device302and the external electronic device301, the level of power loss, which is the difference between power transmitted by the electronic device302and power received by the external electronic device301, may increase. When the power loss exceeds a specified threshold, the electronic device302may stop power transmission.

According to an embodiment, the external electronic device301(e.g., the electronic device101ofFIG. 1) may include a power reception circuit321(e.g., the power management module188ofFIG. 1), a control circuit322(e.g., the processor120inFIG. 1), a communication circuit323(e.g., the communication module190ofFIG. 1), at least one sensor324(e.g., the sensor module176ofFIG. 1), a display325(e.g., the display device160ofFIG. 1), or a sensing circuit326. A description of components of the external electronic device301corresponding to those of the electronic device302may be partially omitted.

According to an embodiment, the power reception circuit321may include the reception coil321L to wirelessly receive power from the electronic device302, a matching circuit321a, and a rectifier circuit321bto rectify received AC power into DC, an adjustment circuit321cto adjust the charging voltage, a switch circuit321d, and/or a battery321e(e.g., the battery189).

According to an embodiment, the control circuit322may control the external electronic device301overall and may generate and transmit various messages necessary for wireless power transmission to the communication circuit323.

According to an embodiment, the communication circuit323may include at least one of the first communication circuit323aor the second communication circuit323b. The first communication circuit323amay communicate with the electronic device302through the reception coil321L.

The first communication circuit323amay communicate with the first communication circuit313ausing the reception coil321L. Data (or a communication signal) generated by the first communication circuit323amay be transmitted using the reception coil321L. The first communication circuit323amay transmit the data to the electronic device302using amplitude-shift keying (ASK). The second communication circuit323bmay communicate with the electronic device302using any one of various short-range communication methods, such as Bluetooth, BLE, Wi-Fi, and NFC.

According to an embodiment, the at least one sensor324may include various sensors such as current/voltage sensor, temperature sensor, illuminance sensor, or acceleration sensor.

According to an embodiment, the display325may display various types of display information necessary for wireless power transmission and reception.

According to an embodiment, the sensing circuit326may detect the electronic device302by detecting a search signal or received power from the electronic device302. The sensing circuit326may detect a change of the signal of the coil321L, the matching circuit321a, or an input/output terminal of the rectifier circuit321bwhen these signals are changed by a signal output from the electronic device302. According to an embodiment, the sensing circuit326may be included in the reception circuit321.

FIG. 4Aillustrates an operation mode of a power transmission device in wireless charging according to an embodiment, andFIG. 4Billustrates an operation mode of a power transmission device in wireless charging according to an embodiment.

Referring toFIG. 4A, in one embodiment, an electronic device401(e.g., the electronic device102ofFIG. 1or the electronic device302ofFIG. 3) may detect and authenticate an external electronic device402(e.g., the electronic device101ofFIG. 2or the external electronic device301ofFIG. 3) and may transmit and receive at least one signal corresponding to a ping phase410, an identification and configuration phase420, and/or a power transfer phase430in order to provide power to the external electronic device402.

The electronic device401may transmit a ping signal, for example, a digital ping signal or an analog ping signal, in the ping phase410. The electronic device401may detect the external electronic device402as the external electronic device402receives the ping signal from the electronic device401.

The electronic device401may receive identification information and configuration information for authenticating the power reception device from the external electronic device402in the authentication and configuration phase420after the external electronic device402is detected. The identification information may include information for identifying the external electronic device402, and the configuration information may include various types of information necessary for the external electronic device402to receive power.

The electronic device401may authenticate the external electronic device402based on the identification information and the configuration information from the external electronic device402, and may receive at least one control error packet (CEP) signal from the external electronic device402in the power transfer phase430upon succeeding in authentication, and may receive at least one received power packet (RPP) signal from the external electronic device402. The control error packet (CEP) signal may include information indicating the level of transmission power transmitted from the electronic device401, and the received power packet (RPP) signal may include information indicating the level of reception power received by the external electronic device402. The electronic device401may adjust power output to the external electronic device402based on the CEP signal and the RPP signal.

Referring toFIG. 4B, in one embodiment, the electronic device401may wirelessly output specified power (or specified current or voltage) through a transmission coil (e.g., the transmission coil311L ofFIG. 3) when outputting at least one signal corresponding to at least one phase of the ping phase410, the identification and configuration phase420, and/or the power transfer phase430.

According to an embodiment, the electronic device401may output first specified power using a first charging current451in a first mode during the identification and configuration phase420for performing authentication of the external electronic device402and may output second specified power using a second charging current453in a second mode during the power transfer phase430.

According to an embodiment, the electronic device401may detect whether there is a foreign object between the electronic device401and the external electronic device402according to the energy detected in the transmission coil (e.g., the transmission coil311L ofFIG. 3) when transceiving the first specified power, and may output the second specified power to the power reception device402or may stop outputting power to the external electronic device402depending on whether the foreign object is detected.

FIG. 5is a flowchart illustrating a power transmission control operation of an electronic device (e.g., the electronic device302ofFIG. 3) corresponding to detection of a foreign object during power transmission to an external electronic device (e.g., the external electronic device301ofFIG. 3) according to an embodiment.FIG. 6is a flowchart illustrating a power transmission control operation of an electronic device corresponding to detection of a foreign object during power transmission according to an embodiment. Hereinafter, the power transmission control operation of the electronic device will be described with reference toFIG. 5andFIG. 6. The operation of the electronic device described below may be performed by a control circuit (e.g., the control circuit312ofFIG. 3) of the electronic device.

According to an embodiment, in operation510, in which the electronic device transmits power to the external electronic device, when a foreign object is interposed between the electronic device and the external electronic device, power received by the external electronic device may be reduced, and thus power loss obtained in operation520may increase. Accordingly, the electronic device may detect the foreign object disposed between the electronic device and the external electronic device based on the power loss, and may stop transmitting the power.

According to an embodiment, in operation520, the power loss may be calculated based on the power transmitted by the electronic device and the power received by the external electronic device. For example, the power loss may correspond to the difference between the transmitted power and the received power. The electronic device may periodically obtain the power received by the external electronic device from the external electronic device through a wireless communication circuit (e.g., the second communication circuit313bofFIG. 3). Specifically, the electronic device may periodically obtain a received power packet (RPP), which is data including the value of power received by the external electronic device, from the external electronic device. The electronic device may identify not only the power loss from the transmission power and the RPP but also a variation in the power loss. For example, the electronic device may obtain a variance in the power loss based on the difference between first power loss at a first time point and second power loss at a second time point after a lapse of a specified time from the first time point.

In operation530, the electronic device may determine whether the power loss exceeds a first threshold in order to detect the foreign object interposed between the electronic device and the external electronic device. When the power loss exceeds the first threshold, the electronic device may determine that there is a foreign object between the electronic device and the external electronic device, and when the power loss does not exceed the first threshold, the electronic device may determine that there is no foreign object between the electronic device and the external electronic device.

In operation560, when a foreign object between the electronic device and the external electronic device is detected, the electronic device may determine whether to stop power transmission accordingly. Hereinafter, existence (or nonexistence) of the foreign object may mean that the foreign object exists (or does not exist) between the electronic device and the external electronic device.

According to an embodiment, when the power loss exceeds the first threshold, the electronic device may determine that there is a foreign object between the electronic device and the external electronic device and may stop power transmission. However, when the power loss does not exceed the first threshold, the electronic device may continue to transmit power to the power reception device.

According to an embodiment, the electronic device stopping power transmission when the power loss exceeds the first threshold in operation560may be one example of a function executed when there is a foreign object between the electronic device and the external electronic device, and various other operations may be executed in addition to simply stopping the power transmission. For example, upon detecting a foreign object, the electronic device may display a notification corresponding to detection of the foreign object on a display of the external electronic device, instead of immediately stopping power transmission, thereby suggesting to the user that he or she should remove the foreign object. In another example, the electronic device may provide a notification corresponding to detection of the foreign object for the user through a light emitting unit or a sound output unit provided in the electronic device. Hereinafter, the operation of stopping power transmission in response to detection of a foreign object is illustrated as a representative example of operations performed in response to the detection of the foreign object for convenience of explanation and may be construed to include all of various operations in response to the detection of the foreign object.

When it is determined that the power loss does not exceed the first threshold and thus there is no foreign object while the electronic device is transmitting power in operation530, the electronic device may continue to transmit power. However, even though the power loss does not exceed the first threshold, there still may be a foreign object between the electronic device and the external electronic device. That is, even though there is a foreign object between the electronic device and the external electronic device, the power loss due to the foreign object may not exceed the first threshold. However, when the foreign object includes a conductive member, if the electronic device does not stop power transmission, heat may be increasingly generated in the foreign object that includes the conductive member (hereinafter, referred to as “conductive foreign object”). Thus, when the electronic device continues to transmit power to the external electronic device, a serious problem may occur. Current induced in the conductive foreign object due to a magnetic field generated by the electronic device while the electronic device is transmitting power to the external electronic device may increase the temperature of the conductive foreign object. As a result, not only the electronic device but also the external electronic device may be heated and damaged by the foreign object. That is, when the electronic device does not stop power transmission only because the power loss does not exceed the first threshold despite existence of a conductive foreign object between the electronic device and the external electronic device, performance of the electronic device or the external electronic device may deteriorate or the electronic device or the external electronic device may be damaged.

According to an embodiment, even though it is determined that the power loss does not exceed the first threshold in operation530, the electronic device may detect a foreign object through operation540and/or operation550and may stop (560) power transmission to the external electronic device.

According to an embodiment, in operation540, the electronic device may determine that there is a conductive foreign object between the electronic device and the external electronic device based on a variation in power loss over time, even when the power loss does not exceed the first threshold. According to an embodiment, when the variation in power loss satisfies a preset criterion, the electronic device may determine that there is a conductive foreign object between the electronic device and the external electronic device.

According to an embodiment, since the variation in power loss due to misalignment between the electronic device and the external electronic device and a variation in power loss due to the existence of a conductive foreign object may be different, the electronic device may identify whether the increase in power loss is due to misalignment between the electronic device and the external electronic device or due to a conductive foreign object.

For example, when the position of the external electronic device with respect to the electronic device is changed while the electronic device is transmitting power to the external electronic device, power loss may significantly increase at the moment of the position change. However, the electronic device may adjust the power after detecting the power loss, thus reducing the level of power loss after the lapse of a certain time period. In contrast, when a conductive foreign object is interposed between the electronic device and the external electronic device while the electronic device is transmitting power to the external electronic device, power loss may significantly increase at the moment of the interposition. However, in the case where the conductive foreign object is interposed, the level of power loss may be maintained high even after the lapse of a certain time period. Therefore, according to an embodiment, the electronic device may monitor the change in power loss over time, thereby detecting whether a conductive foreign object is interposed between the electronic device and the external electronic device.

According to another embodiment, since the variation in power loss due to a nonconductive foreign object may be different from the variation in power loss due to a conductive foreign object, the electronic device may identify whether the increase in power loss is due to a conductive foreign object based on a variation in power loss. According to an embodiment, due to specific characteristics of a conductive member included in the conductive foreign object, the variation in power loss due to the conductive foreign object may be distinguished from the variation in power loss due to other circumstances.

For example, when a nonconductive foreign object is interposed between the electronic device and the external electronic device, power loss may rapidly increase in a first time period, and may decrease to be maintained slightly greater than the power loss before the first time period after the first time period. When a conductive foreign object is interposed, power loss may rapidly increase in the first time period, and may be maintained substantially greater than the power loss before the first time period after the first time period. Therefore, according to an embodiment, the electronic device may monitor the variation in power loss over time, thereby identifying whether a foreign object interposed between the electronic device and the external electronic device includes a conductive material.

According to an embodiment, in operation540, the electronic device may use a criterion related to power loss in order to quantitatively determine whether the variation in power loss corresponds to a variation in power loss due to a conductive foreign object.

According to an embodiment, the criterion related to power loss may include whether the variance in power loss exceeds a third threshold value and/or whether power loss exceeds a fourth threshold at a specific time period.

According to an embodiment, when the variation in power loss satisfies the criterion related to power loss, the electronic device may determine that an event related to power loss occurs. According to an embodiment, when an event related to power loss occurs, the electronic device may determine that there is a conductive foreign object between the electronic device and the external electronic device.

According to an embodiment, even though the power loss does not exceed the first threshold in operation540, when the variation in power loss exceeds the third threshold, the electronic device may determine that there is a conductive foreign object. The third threshold may vary depending on the type of an external electronic device.

According to an embodiment, the variation in power loss may be calculated from power received from the external electronic device. For example, the electronic device obtain a plurality of most recent power loss values from data corresponding to power received from by the external electronic device and may calculate the variation in power loss based on the plurality of power loss values.

For example, the variation in power loss may be calculated based on the difference between a second maximum value and a second minimum value among n power loss values (P_loss_1, P_loss_2, . . . , P_loss_n) which are most recently obtained at nth time point. A maximum value (max(P_loss_1, P_loss_2, . . . , P_loss_n)) and a minimum value (min(P_loss_1, P_loss_2, . . . , P_loss_n)) may not be considered to calculate the difference. When a new power loss (P_loss_n+1) is obtained at an n+1th time point, the variation in power loss may be calculated from a plurality of power loss values (P_loss_2, P_loss_2, . . . , P_loss_n+1), which includes the new power loss (P_loss_n+1) and excludes the oldest power loss value (P_loss_1). According to an embodiment, the method for calculating the variation in power loss is not limited to the above method and may vary.

According to an embodiment, even though the power loss does not exceed the first threshold in operation540, when the power loss exceeds the fourth threshold, the electronic device may determine that there is a conductive foreign object. According to an embodiment, when a periodically obtained power loss value consecutively exceeds the fourth threshold, the electronic device may determine that there is a conductive foreign object.

For example, the electronic device may obtain a power loss value at the first time point, the second time point, . . . , and nth time point. When all the power loss values obtained at the first to nth time points exceed the fourth threshold, the electronic device may recognize that there is a conductive foreign object.

According to another embodiment, even though the power loss does not exceed the first threshold, when an increase in the power loss is detected at the first time point and then the power loss obtained at the second time point after the lapse of a certain time period exceeds the fourth threshold, the electronic device may determine that there is a conductive foreign object.

According to an embodiment, when the power loss continuously exceeds the fourth threshold at a third time point after the lapse of a second time period from the second time point, the electronic device may determine that there is a conductive foreign object.

According to an embodiment, when all of n power losses consecutively obtained since the second time point exceed the fourth threshold, the electronic device may determine that there is a conductive foreign object.

According to an embodiment, the electronic device may determine whether there is a conductive foreign object in consideration of both the variance in power loss and power loss in operation540. Referring toFIG. 6, according to an embodiment, even though the power loss does not exceed the first threshold, the electronic device may determine whether the variance in power loss exceeds the third threshold in operation540-1and may determine whether subsequently obtained power loss exceeds the fourth threshold in operation540-2. When both criteria are satisfied, the electronic device may determine that there is a conductive foreign object between the electronic device and the external electronic device.

For example, when power loss values that are obtained after a time point at which the variance in power loss exceeds the third threshold, continues to consecutively exceed the fourth threshold, the electronic device may determine that there is a conductive foreign object.

According to an embodiment, in operation540, when the power loss or the variance in power loss at the second time point after the lapse of the specified time period from the first time point, at which the increase in power loss is first detected, exceeds a specified threshold, the electronic device may determine that there is a conductive foreign object between the electronic device and the external electronic device.

According to another embodiment, when the power loss or the variance in power loss at and after the second time point after the lapse of the first time period from the first time point, at which the increase in power loss is first detected, continuously exceeds a specified threshold for a second time period, the electronic device may determine that there is a conductive foreign object between the electronic device and the external electronic device.

According to an embodiment, in operation550, the electronic device may change the first threshold based on the result of operation540(not shown), thereby detecting a foreign object even when the power loss does not exceed the first threshold. The first threshold may be a reference value for determining that there is a foreign object between the electronic device and the external electronic device when the power loss exceeds the first threshold. Therefore, when the first threshold is changed to the second threshold, which is lower than the first threshold, the electronic device may determine that there is a foreign object between the electronic device and the external electronic device even though the power loss is lower than the first threshold.

According to an embodiment, when an event related to power loss is detected (540), the electronic device may change the first threshold to the second threshold, may determine that there is a conductive foreign object when a subsequently obtained power loss value exceeds the second threshold, and may stop power transmission in operation560. According to another embodiment, when an event related to power loss is detected (540), the electronic device may determine that there is a conductive foreign object, may change the first threshold to the second threshold, and may stop power transmission when a subsequently obtained power loss value exceeds the second threshold.

FIG. 5shows that when an event related to power loss is detected, it is determined whether to stop power transmission after operation550, in which a determination is made for whether the power loss exceeds the second threshold. According to an embodiment, when an event related to power loss is detected in operation540, it is possible to determine whether to stop power transmission without operation550. Since detection of an event related to power loss means that existence of a conductive foreign object is recognized, operation550may be omitted.

According to an embodiment, when operation550is omitted, the electronic device may stop power transmission after the lapse of a specified time period from detection of the event related to power loss in operation540. For example, when an event related to power loss, which may be the power loss exceeding the fourth threshold, is detected at the first time point, the electronic device may stop power transmission after the lapse of the specified time period from the first time point.

The first threshold may be a foreign object detection (FOD) threshold. According to an embodiment, even when the power loss does not exceed the FOD threshold, the electronic device may detect a conductive foreign object based on the subsequent variation in power loss, thus preventing a problem caused by the conductive foreign object. Accordingly, the FOD threshold of the electronic device may be set to be high for user convenience.

When the FOD threshold is set to be low, the electronic device can easily detect a foreign object, but may determine that there is a foreign object even by power loss due to a cover (e.g., a protection cover) coupled to the external electronic device or power loss caused by misalignment of the external electronic device on the power transmission device.

According to an embodiment, the FOD threshold may be set to be high so that power transmission is not stopped even though power loss occurs due to misalignment between the electronic device and the external electronic device or due to the cover, thereby contributing to user convenience. According to an embodiment, the electronic device may detect a conductive foreign object and may stop power transmission by changing an initially set FOD threshold to a lower threshold (e.g., the second threshold) during power transmission. According to an embodiment, even though a high FOD threshold is set, the electronic device can detect a conductive foreign object, thus improving user convenience and securing safety during wireless charging.

FIG. 7is a graph illustrating power loss (solid line) that occurs when there is a foreign object including a conductive material and a threshold (dotted line) for detecting a foreign object over time while an electronic device (e.g., the electronic device302ofFIG. 3) is transmitting power to an external electronic device (e.g., the external electronic device301ofFIG. 3) according to an embodiment.

Referring toFIG. 7, power loss increases when a conductive foreign object is interposed between the electronic device and the external electronic device while the electronic device is transmitting power to the external electronic device.

Even though the conductive foreign object is interposed between the electronic device and the external electronic device at a first time point t1, power loss values obtained after the first time point t1 may not exceed a first threshold P1. Since the power loss does not exceed the first threshold P1, the electronic device may determine that there is no foreign object and may continue to transmit power to the external electronic device. When the electronic device does not stop transmitting power, the conductive foreign object may increase in temperature and may thus damage the electronic device and the external electronic device.

According to an embodiment, the electronic device may determine that there is a conductive foreign object according to a variation in power loss even though the power loss does not exceed the first threshold P1. The electronic device may change the first threshold P1 to a second threshold P2, which is lower than the first threshold value P1, at a fifth time point t5 to examine the variation in power loss between the first time point P1 and the fifth time point t5. The electronic device may stop power transmission when the power loss exceeds the second threshold value P2 at a sixth time point t6, thus protecting the electronic device and the external electronic device. According to an embodiment, the electronic device may determine that there is a conductive foreign object according to the variation in power loss between the first time point t1 and the fifth time point t5 and may stop power transmission, in which a process of changing the threshold may be omitted.

According to an embodiment, the electronic device may monitor the variation in power loss between the first time point t1 and the fifth time point t5, thereby identifying whether there is a conductive foreign object. Referring toFIG. 7, the power loss may increase after the conductive foreign object is interposed between the electronic device and the external electronic device at the first time point t1. The electronic device may determine whether power losses obtained at a second time point t2, a third time point t3, and a fourth time point t4 exceed a fourth threshold P4 in response to detecting a variance in power loss (ΔPloss) after the first time point t1 exceeding a third threshold P3. According to an embodiment, time intervals between the second time point t2 to the fourth time point t4 may correspond to the period in which the electronic device obtains the power loss information. That is, when all power losses (Ploss.t2, Ploss.t3, and Ploss.t4) consecutively obtained after the variance in power loss (ΔPloss) exceeds the third threshold P3 exceed the fourth threshold P4, the electronic device may change the first threshold P1 to the second threshold P2.

According to an embodiment, when the power loss exceeds an FOD threshold (e.g., the first threshold), the electronic device may determine that there is a foreign object and may stop transmitting power to the external electronic device. When the power loss occurs but does not exceed the FOD threshold, the electronic device does not generally stop power transmission.

Even though the power loss does not exceed the FOD threshold, when the power loss is due to a conductive foreign object, the electronic device needs to stop power transmission. When the conductive foreign object is continuously exposed to a magnetic field, a current may be induced in the conductive foreign object and the conductive foreign object may be heated to a high temperature due to the induced current.

According to an embodiment, even when the power loss does not exceed the FOD threshold, the electronic device may change the FOD threshold to a lower threshold based on a variation in power loss, thereby detecting a conductive foreign object.

Table 1 shows actual examples of thresholds for detecting a foreign object per wireless charging capacity of the electronic device according to an embodiment.

According to an embodiment, when the electronic device is a 5 W wireless power transmission device, an initially set FOD threshold (first threshold) may be 2000 mW. When the variance in power loss (ΔPloss) exceeds 800 mW (MFOD Ploss.th (third threshold)) and all consecutive power losses subsequently obtained exceed 800 mW (absolute Ploss (fourth threshold)), the electronic device may change the FOD threshold to 500 mW (modified FOD threshold (second threshold)).

According to an embodiment, when the electronic device is a 6.5 W, 7.5 W, or 12 W wireless power transmission device, an initially set FOD threshold (first threshold) may be 3300 mW. When a variance in power loss (ΔPloss) exceeds 1000 mW (MFOD Ploss.th (third threshold)) and all consecutive power losses subsequently obtained exceed 1300 mW (absolute Ploss (fourth threshold)), the electronic device may change the FOD threshold to 1300 mW (modified FOD threshold (second threshold)).

According to an embodiment, when the electronic device is a 15 W or 18 W wireless power transmission device, an initially set FOD threshold (first threshold) may be 3500 mW. When a variance in power loss (ΔPloss) exceeds 1000 mW (MFOD Ploss.th (third threshold)) and all consecutive power losses subsequently obtained exceed 1500 mW (absolute Ploss (fourth threshold)), the electronic device may change the FOD threshold to 1500 mW (modified FOD threshold (second threshold)).

As described above, an electronic device according to an embodiment may include: a housing; a wireless charging coil configured to be disposed in the housing; a power transmission circuit configured to be electrically connected to the wireless charging coil; a wireless communication circuit configured to communicate with an external electronic device; and a control circuit configured to be electrically connected to a power management circuit and the wireless communication circuit, wherein the control circuit may be configured to: transmit power to an external electronic device; obtain data corresponding to power received by the external electronic device in response to the transmitted power using the wireless communication circuit; obtain power loss based on the obtained data; stop transmitting the power to the external electronic device when the power loss exceeds a first threshold; detect an event related the power loss at a first time point when the power loss is lower than the first threshold; determine whether the power loss obtained at a second time point after a lapse of a first time period from the first time point, at which the event is detected, exceeds a second threshold lower than the first threshold; and stop transmitting the power to the external electronic device when the power loss obtained at the second time point exceeds the second threshold.

According to an embodiment, in the electronic device, the control circuit may be configured to obtain a variance in power loss based on the power loss, and the event may include a case where the variance in power loss exceeds a third threshold.

According to an embodiment, in the electronic device, the variance in power loss may correspond to a difference between a second maximum value and a second minimum value among a plurality of power loss values.

According to an embodiment, in the electronic device, the event may include a case where the power loss, obtained after the variance in power loss exceeds the third threshold exceeds a fourth threshold.

According to an embodiment, in the electronic device, the event may include a case where a plurality of power loss values, obtained after the variance in power loss exceeds the third threshold consecutively exceeds a fourth threshold.

According to an embodiment, in the electronic device, the event may include a case where the power loss exceeds a fourth threshold.

According to an embodiment, in the electronic device, the event may include a case where a plurality of power loss values consecutively exceeds a fourth threshold.

According to an embodiment, in the electronic device, the control circuit may be configured to detect whether the power loss increases, and the event may include a case where the power loss obtained after a lapse of a specified time period from a time point at which an increase in the power loss is detected exceeds a fourth threshold.

According to an embodiment, in the electronic device, the control circuit may be configured to detect whether the power loss increases, and the event may include a case where a plurality of power loss values obtained after a lapse of a specified time period from a time point at which an increase in the power loss is detected consecutively exceeds a fourth threshold.

According to an embodiment, in the electronic device, the control circuit may be configured to transmit a signal corresponding to suspension of power transmission to the external electronic device when power transmission is stopped.

An electronic device according to an embodiment may include: a housing; a wireless charging coil configured to be disposed in the housing; a power transmission circuit configured to be electrically connected to the wireless charging coil; a wireless communication circuit configured to communicate with an external electronic device; and a control circuit configured to be electrically connected to a power management circuit and the wireless communication circuit, wherein the control circuit may be configured to: transmit power to an external electronic device; obtain data corresponding to power received by the external electronic device by the power using the wireless communication circuit; obtain power loss based on the obtained data; determine whether the power loss or a variance in power loss obtained based on the power loss exceeds a first threshold at a first time point; determine whether the power loss or the variance in power loss exceeds a second threshold at a second time point after a lapse of a first time period from the first time point; and stop transmitting the power to the external electronic device when the power loss obtained at the second time point exceeds the second threshold.

According to an embodiment, in the electronic device, the control circuit may be further configured to determine whether the power loss exceeds a third threshold at a third time point between the first time point and the second time point, and to stop transmitting power to the external electronic device in response to the power loss exceeding the third threshold at the third time point.

According to an embodiment, in the electronic device, the control circuit may be further configured to determine whether the variance in power loss exceeds a third threshold at a third time point between the first time point and the second time point, and to stop transmitting power to the external electronic device in response to the variance in power loss exceeding the third threshold at the third time point.

According to an embodiment, in the electronic device, the control circuit may be configured to transmit a signal corresponding to suspension of power transmission to the external electronic device when power transmission is stopped.

A power control method of an electronic device configured to transmit power to an external electronic device according to an embodiment may include: transmitting the power to the external electronic device; obtaining data corresponding to power received by the external electronic device in response to the transmitted power using a wireless communication circuit provided in the electronic device; obtaining power loss based on the obtained data; stopping transmitting the power to the external electronic device when the power loss exceeds a first threshold; detecting an event related the power loss at a first time point when the power loss is lower than the first threshold; determining whether the power loss obtained at a second time point after a lapse of a first time period from the first time point, at which the event is detected, exceeds a second threshold lower than the first threshold; and stopping transmitting the power to the external electronic device when the power loss obtained at the second time point exceeds the second threshold.

According to an embodiment, the method may further include obtaining a variance in power loss based on the power loss, wherein the event may include a case where the variance in power loss exceeds a third threshold.

According to an embodiment, in the method, the event may include a case where the power loss obtained after the variance in power loss exceeds a third threshold exceeds a fourth threshold.

According to an embodiment, in the method, the event may include a case where the power loss exceeds a fourth threshold.

According to an embodiment, the method may further include detecting whether the power loss increases, wherein the event may include a case where the power loss obtained after a lapse of a specified time period from a time point at which an increase in the power loss is detected exceeds a fourth threshold.

According to an embodiment, the method may further include transmitting a signal corresponding to suspension of power transmission to the external electronic device when power transmission is stopped.

The various example embodiments disclosed herein and illustrated in the drawings are provided by way of illustration and are not intended to limit the scope of the present disclosure. Therefore, all changes or modifications derived from the technical idea of the present disclosure as well as the embodiments described herein should be understood to fall within the scope of the present disclosure.