Structure for detecting foreign matter in wireless charging device and corresponding detection method

Abstract

Provided in the present invention is a structure for detecting foreign matter in a wireless charging device, which uses two groups of flexible temperature sensors to detect whether metal foreign matter is present in a ground primary-side device and a power receiving end on a vehicle bottom, thereby ensuring reliable operation of a wireless charging process. The device comprises: a ground primary-side device, a first flexible circuit board being provided therein, a plurality of flexible temperature sensors being arranged in an array on the first flexible circuit board, and the flexible temperature sensors arranged in an array being used for monitoring a temperature parameter of a surface area corresponding to a ground top cover assembly; and a power receiving end, a second flexible circuit board being provided therein, a plurality of flexible temperature sensors being arranged in an array on the second flexible circuit board, and the flexible temperature sensors arranged in an array being used for monitoring a temperature parameter of a surface area corresponding to a coil panel bottom plate. In a wireless charging working state, the coil panel bottom plate of the power receiving end is located directly above the ground top cover assembly of the ground primary-side device.

Description

A structure for detecting foreign objects in wireless charging devices and a corresponding detection method. Technical Field

[0001] This invention relates to the technical field of wireless charging, specifically to a structure for detecting foreign objects in wireless charging devices. The invention also provides a method for detecting foreign objects in wireless charging devices. Background Technology

[0002] Wireless charging uses an alternating magnetic field to transfer energy. When a metallic foreign object is present in this alternating magnetic field, the object's temperature rises due to hysteresis loss and eddy current generation, posing a risk of burning or fire. Therefore, metallic foreign object detection is an essential protective function in wireless charging systems. Traditional metal foreign object detection solutions in the industry use a specific frequency signal to excite a detection coil distributed throughout the transmitter to detect voltage and current changes caused by the metallic foreign object. This specific frequency is typically in the MHz range, which differs from the operating frequency of wireless charging power transmission.

[0003] Existing metal foreign object detection solutions are costly and susceptible to electromagnetic interference during wireless charging power transmission, leading to false alarms or missed alarms. This results in poor charging safety and continuity, severely impacting the end-user experience and hindering the industrialization of wireless charging. Furthermore, current metal foreign object detection systems can only be installed on the ground edge. However, during actual wireless charging, unpredictable objects such as mud, dirt, and other debris can adhere to the outer surface of the power receiver on the vehicle's underside, causing overheating and burning during charging. Therefore, there is an urgent need to develop a novel metal foreign object detection structure for wireless charging devices. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a structure for detecting foreign objects in wireless charging devices. It uses two sets of flexible temperature sensors to detect whether there are metallic foreign objects on the ground-side device and the power receiving end under the vehicle, thereby ensuring the reliable operation of the wireless charging process.

[0005] A structure for detecting foreign objects in a wireless charging device, characterized in that it comprises:

[0006] The ground-based edge device has a first flexible circuit board inside, and a number of flexible temperature sensors are arranged in an array on the first flexible circuit board. The array of flexible temperature sensors is used to monitor the temperature parameters in the surface area corresponding to the ground cover component.

[0007] And the power receiving end, which has a built-in second flexible circuit board, on which a number of flexible temperature sensors are arranged in this row. The array of flexible temperature sensors is used to monitor the temperature parameters in the surface area corresponding to the bottom plate of the coil.

[0008] In wireless charging operation, the coil base plate of the power receiver is positioned directly above the ground cover assembly of the ground-based device.

[0009] Its further features are:

[0010] The ground-side device, from bottom to top, includes a back plate, a first sensor signal control circuit board, a ferrite fixing plate assembly, a coil disk assembly, a first flexible circuit board, and a ground cover assembly. The ground cover assembly is installed on the back plate to form the inner cavity of the ground-side device. The first sensor signal control circuit board, the ferrite fixing plate assembly, the coil disk assembly, and the first flexible circuit board are arranged from bottom to top in the inner cavity of the ground-side device. A plurality of flexible temperature sensors are arranged in an array on one surface of the first flexible circuit board.

[0011] The ground-side device, from bottom to top, includes a back plate, a first sensor signal control circuit board, a ferrite fixing plate assembly, a coil disk assembly, and a ground cover assembly. The first flexible circuit board is recessed on the upper surface of the ground cover assembly and covered with a fixing cover plate. After the ground cover assembly is installed on the back plate, it forms the inner cavity of the ground-side device. The first sensor signal control circuit board, the ferrite fixing plate assembly, and the coil disk assembly are arranged from bottom to top in the inner cavity of the ground-side device. A plurality of flexible temperature sensors are arranged in an array on one surface of the first flexible circuit board.

[0012] The resistance values ​​of all flexible temperature sensors are connected to the first sensor signal control circuit board via flexible transmission lines on the first flexible circuit board. The first sensor signal control circuit board integrates a corresponding analog-to-digital conversion circuit and an MCU controller. The first sensor signal control circuit board drives the ground primary edge device to perform foreign object detection based on the temperature data obtained by the flexible temperature sensors on the first flexible circuit board and to determine whether charging is continuing.

[0013] The power receiving end includes, from bottom to top, a coil base plate, a second flexible circuit board, a Litz coil, a ferrite assembly, a water-cooled plate assembly, a second sensor signal control circuit board, and a vehicle-side top cover assembly. After the vehicle-side top cover assembly and the coil base plate are closed, they form the vehicle-side equipment cavity. The vehicle-side equipment cavity is provided with, from bottom to top, a second flexible circuit board, a Litz coil, a ferrite assembly, a water-cooled plate assembly, and a second sensor signal control circuit board. A plurality of flexible temperature sensors are arranged in an array on one surface of the second flexible circuit board.

[0014] The resistance values ​​of all the flexible temperature sensors are connected to the second sensor signal control circuit board through the flexible transmission lines on the second flexible circuit board. The second sensor signal control circuit board integrates the corresponding analog-to-digital conversion circuit and MCU controller. The second sensor signal control circuit board drives the power receiving end to perform foreign object detection based on the temperature data obtained by the flexible temperature sensors on the second flexible circuit board and to determine whether charging is continuing.

[0015] The power receiving end includes, from bottom to top, a coil base plate, a second flexible circuit board, a Litz coil, a ferrite assembly, and a vehicle body end cover assembly. After the vehicle body end cover assembly and the coil base plate are closed, they form the inner cavity of the vehicle body end equipment. The inner cavity of the vehicle body end equipment is provided with the second flexible circuit board, the Litz coil, and the ferrite assembly from bottom to top. Several flexible temperature sensors are arranged in an array on one surface of the second flexible circuit board. In this structure, the signal control circuit board of the second sensor is external.

[0016] The resistance values ​​of all flexible temperature sensors are transmitted to an external second sensor signal control circuit board via a wired or wireless means through the flexible transmission part on the second flexible circuit board. The second sensor signal control circuit board integrates a corresponding analog-to-digital conversion circuit and an MCU controller. The second sensor signal control circuit board drives the power receiving end to perform foreign object detection based on the temperature data obtained by the flexible temperature sensors on the second flexible circuit board and to determine whether charging is continuous.

[0017] The flexible temperature sensor is arranged in a pattern covering the center of the coil, the winding area of ​​the coil, and the outer edge of the winding, ensuring complete coverage detection of the coil.

[0018] A method for detecting foreign objects in wireless charging devices is characterized by detecting metal foreign objects separately or simultaneously on the ground-based edge device and the power receiving end, and during the charging process, monitoring the temperature change of the entire surface area of ​​the corresponding device in real time. When any device detects a temperature exceeding the maximum safe charging temperature at the corresponding surface area location during real-time detection, the charging device stops charging. If any device detects a metal foreign object, but the real-time temperature of the corresponding detection area does not exceed the maximum safe charging temperature, wireless charging continues until the temperature at the location of the metal foreign object exceeds the maximum safe charging temperature before charging stops.

[0019] Its further feature is that: the detection of metal foreign objects on the ground-based primary equipment and the power receiving end, and the determination of whether to stop charging, includes the following steps:

[0020] S1: Obtain the initial static temperature reference point in standby mode;

[0021] S2: Working mode samples a certain amount of temperature status data in real time as a comparison point and updates the temperature data table accordingly;

[0022] S3: Analyze the temperature difference between the temperature reference point and the real-time temperature data to determine if there are any metal foreign objects. Based on the temperature difference between the temperature comparison point and the reference temperature point, dynamically adjust the real-time data of the temperature reference point. Then, based on the temperature comparison point and the preset maximum safe charging temperature, determine whether to trigger the preset over-temperature shutdown protection event.

[0023] Its further characteristic is:

[0024] Step S1 includes the following steps:

[0025] S101. During the standby period of the equipment, sensor data is collected. This data can be used to determine the ambient temperature and steady-state characteristics of the equipment, and to determine whether there is any abnormality in the sensor.

[0026] S102. Sensor data collected during equipment standby is used as an initial reference point to effectively avoid the influence of differences between different devices, sensors, and environments.

[0027] Step S2 includes the following steps:

[0028] S201. Collect the latest data at regular intervals and use it as a comparison point and reference point for dynamic adjustment.

[0029] S202. Store data collected in multiple rounds. The data storage adopts a cyclic update mechanism, which makes the software consume less CPU resources and update the valid data of the most recent period in real time.

[0030] S301. The wireless charging device obtains comparison points by rapidly sampling data during operation and compares them with reference points obtained during standby. The feature parameters of the comparison include the difference in change between the comparison point and the reference point and the slope. When these two feature parameters reach the threshold, it is determined that there is a metal foreign object at this time.

[0031] S302. If any condition is not met, the feature data of the reference point at the corresponding position is updated dynamically in a timely manner, and the latest comparison point data of the reference point at the corresponding position is obtained to reduce feature changes caused by changes in the current device itself and the environment.

[0032] S303: After multiple rounds of data collection, the data is processed by the software and compared with preset values. If the data does not exceed the preset maximum safe charging temperature range, the device is determined to be in a safe operating environment. Even if a metal foreign object is detected, the preset event will not be triggered. If the data exceeds the preset maximum safe charging temperature range, it is considered that the device can no longer support safe charging operation, and a preset event needs to be triggered to stop charging, even if no metal foreign object is detected. By adding this preset value judgment condition, the device can effectively reduce charging equipment shutdown events while ensuring the safety of the charging equipment and the user, thereby significantly improving the user charging experience.

[0033] This invention employs flexible temperature sensor technology. When the sensing film of the flexible temperature sensor senses a change in the physical quantity of temperature (using temperature as an example here, similarly, capacitance or voltage difference could be used), the change in resistance within the sensing film will form a functional relationship with the temperature value. The sensing film of the flexible sensor is equivalent to a variable resistor in the sensing circuit. The signal processing unit outputs an analog resistance signal, which is processed by a general analog-to-digital converter and an MCU controller to calculate the temperature to be detected. This yields the temperature of the corresponding area of ​​the wireless charging device. Furthermore, based on the temperature rise and other temperature factors, it can be determined whether there are metallic foreign objects in the corresponding area. The flexible temperature sensor possesses multiple excellent properties, including anti-electromagnetic interference, vibration resistance, high temperature resistance, and corrosion resistance, making it suitable for automotive-grade and other high-temperature applications. It requires stable operation in a specific environment. It uses flexible temperature sensors to detect the temperature rise of metallic foreign objects in an alternating magnetic field, thereby identifying the foreign objects and stopping charging promptly, effectively ensuring charging safety. During the detection of metallic foreign objects and the determination to stop wireless charging, several flexible temperature sensors, embedded in the ground-side device and the power receiver, sense the real-time temperature and accurate temperature values ​​of the corresponding areas. This allows them to determine whether metallic foreign objects are present in the corresponding areas of the ground-side device and the power receiver, and to decide whether to stop wireless charging based on whether the temperature exceeds the maximum safe charging temperature. It uses two sets of flexible temperature sensors to detect the presence of metallic foreign objects in the ground-side device and the power receiver under the vehicle, thus ensuring the reliable operation of the wireless charging process. Attached Figure Description

[0034] Figure 1 is an exploded view of the metal foreign object detection structure corresponding to a specific embodiment of the ground-based edge device of the present invention;

[0035] Figure 2 is an exploded view of the metal foreign object detection structure of the present invention corresponding to a specific embodiment two of the ground-based edge device;

[0036] Figure 3 is an exploded view of the metal foreign object detection structure corresponding to a specific embodiment of the power receiver of the present invention;

[0037] Figure 4 is an exploded view of the metal foreign object detection structure corresponding to the second specific embodiment of the power receiver of the present invention;

[0038] Figure 5 is a schematic diagram of the specific implementation of signal transmission in Figure 1;

[0039] Figure 6 is a schematic diagram of the specific implementation of signal transmission in Figure 3;

[0040] Figure 7 is a diagram showing the magnetic flux density distribution of the coil inside the ground terminal equipment used in a specific embodiment of the present invention;

[0041] Figure 8 shows the distribution of foreign object testing areas for ground-end equipment from a top-down view. The numbers in the upper right corner are the subdivision numbers of the areas, and A, B, C, and D are the codes for the large areas.

[0042] Figure 9 shows the test data of region B1 in a specific embodiment at an ambient temperature of 25°C using a flexible temperature sensor.

[0043] Figure 10 is a detection curve when a metallic foreign object is present in region B1 in a specific embodiment;

[0044] Figure 11 is a detection curve graph of the presence of a metallic foreign object in region B12 in a specific embodiment. The names corresponding to the serial numbers in the figure are as follows:

[0045] Ground-based primary edge device 10, first flexible circuit board 11, branch flexible transmission line 111, ground cover assembly 12, back plate 13, first sensor signal control circuit board 14, ferrite fixing plate assembly 15, coil disk assembly 16.

[0046] Power receiving end 20, second flexible circuit board 21, flexible transmission line 211, coil base plate 22, Litz coil 23, ferrite assembly 24, water cooling plate assembly 25, second sensor signal control circuit board 26, vehicle body end cover assembly 27.

[0047] Flexible temperature sensor 30. Detailed Implementation

[0048] A structure for detecting foreign objects in a wireless charging device, as shown in Figures 1-6, includes a ground-based primary edge device 10 and a power receiver 20.

[0049] The inner cavity of the ground edge device 10 is provided with a first flexible circuit board 11, and a number of flexible temperature sensors 30 are arranged in an array on the first flexible circuit board 11. The array of flexible temperature sensors 30 is used to monitor the temperature parameters in the surface area corresponding to the ground cover component 12.

[0050] The inner cavity of the power receiving end 20 is provided with a second flexible circuit board 21, and a number of flexible temperature sensors 30 are arranged in this row on the second flexible circuit board 21. The array of flexible temperature sensors 30 is used to monitor the temperature parameters in the surface area corresponding to the coil base plate 22.

[0051] In the wireless charging working state, the coil base plate 22 of the power receiver 20 is positioned directly above the ground cover assembly 12 of the ground edge device 10.

[0052] A specific embodiment of the ground-side device 10 is shown in Figure 1. From bottom to top, it includes a back plate 13, a first sensor signal control circuit board 14, a ferrite fixing plate assembly 15, a coil disk assembly 16, a first flexible circuit board 11, and a ground cover assembly 12. The ground cover assembly 12 is installed on the back plate 13 to form the inner cavity of the ground-side device. The first sensor signal control circuit board 14, the ferrite fixing plate assembly 15, the coil disk assembly 16, and the first flexible circuit board 11 are arranged from bottom to top in the inner cavity of the ground-side device. A plurality of flexible temperature sensors 30 are arranged in an array on one surface of the first flexible circuit board 11.

[0053] A second specific embodiment of the ground edge device 10 is shown in Figure 2. The ground edge device includes, from bottom to top, a back plate 13, a first sensor signal control circuit board 14, a ferrite fixing plate assembly 15, a coil disk assembly 16, and a ground cover assembly 12. The first flexible circuit board 11 is recessed on the upper surface of the ground cover assembly 12 and covered with a fixing cover plate 17. After the ground cover assembly 12 is installed on the back plate 13, it forms the inner cavity of the ground end device. The first sensor signal control circuit board 14, the ferrite fixing plate assembly 15, and the coil disk assembly 16 are arranged from bottom to top in the inner cavity of the ground end device. A plurality of flexible temperature sensors 30 are arranged in an array on one surface of the first flexible circuit board 11.

[0054] The first flexible circuit board 11 is installed on the upper or lower layer of the ground cover assembly 12 as needed.

[0055] In the first specific embodiment, the resistance values ​​of all the flexible temperature sensors 30 are connected to the first sensor signal control circuit board 14 through four flexible transmission lines 111 on the first flexible circuit board 11. The first sensor signal control circuit board 14 integrates a corresponding analog-to-digital conversion circuit and an MCU controller. The first sensor signal control circuit board 14 drives the ground primary edge device 10 to perform foreign object detection based on the temperature data obtained by the flexible temperature sensors 30 on the first flexible circuit board 11, and to determine whether charging is continuing.

[0056] A specific embodiment of the power receiver 20 is shown in Figure 3. From bottom to top, it includes a coil base plate 22, a second flexible circuit board 21, a Litz coil 23, a ferrite assembly 24, a water-cooled plate assembly 25, a second sensor signal control circuit board 26, and a vehicle body end cover assembly 27. After the vehicle body end cover assembly 27 and the coil base plate 22 are closed, they form the inner cavity of the vehicle body end equipment. The second flexible circuit board 21, the Litz coil 23, the ferrite assembly 24, the water-cooled plate assembly 25, and the second sensor signal control circuit board 26 are arranged from bottom to top in the inner cavity of the vehicle body end equipment. Several flexible temperature sensors 30 are arranged in an array on one surface of the second flexible circuit board 21.

[0057] The resistance values ​​of all the flexible temperature sensors 30 are connected to the second sensor signal control circuit board 27 via the flexible transmission line 211 on the second flexible circuit board 21. The second sensor signal control circuit board 27 integrates a corresponding analog-to-digital conversion circuit and an MCU controller. The second sensor signal control circuit board 27 drives the power receiving terminal 20 to perform foreign object detection based on the temperature data obtained by the flexible temperature sensors 30 on the second flexible circuit board 21, and to determine whether charging is continuing.

[0058] A second specific embodiment of the power receiving end 20 is shown in Figure 4. From bottom to top, it includes a coil base plate 22, a second flexible circuit board 21, a Litz coil 23, a ferrite assembly 24, and a vehicle end cover assembly 27. After the vehicle end cover assembly 27 and the coil base plate 22 are closed, they form the inner cavity of the vehicle end equipment. The second flexible circuit board 21, the Litz coil 23, and the ferrite assembly 24 are arranged from bottom to top in the inner cavity of the vehicle end equipment. A plurality of flexible temperature sensors 30 are arranged in an array on one surface of the second flexible circuit board 21. In this structure, the second sensor signal control circuit board 26 is external.

[0059] The resistance values ​​of all flexible temperature sensors 30 are transmitted via wired or wireless means to an external second sensor signal control circuit board 26 (not shown in Figure 4, see Figure 3 for detailed structure) through the flexible transmission section on the second flexible circuit board 21. The second sensor signal control circuit board 26 integrates a corresponding analog-to-digital conversion circuit and an MCU controller. The second sensor signal control circuit board 26 drives the power receiving end to perform foreign object detection based on the temperature data obtained by the flexible temperature sensors on the second flexible circuit board 21 and to determine whether charging is continuous.

[0060] The flexible temperature sensor 30 is arranged in a distribution area covering the center of the coil, the winding area of ​​the coil, and the outer edge of the winding of the magnetic coil, ensuring complete coverage detection of the coil.

[0061] The method for detecting foreign objects in wireless charging devices involves detecting metal foreign objects on the ground-based edge device 10 and the power receiver 20, either separately or simultaneously. During charging, the method monitors the temperature change of the entire surface area of ​​the corresponding device in real time. If any device detects a temperature exceeding the maximum safe charging temperature at its corresponding surface location during real-time detection, the charging device stops charging. If any device detects a metal foreign object, but the real-time temperature of the corresponding detection area does not exceed the maximum safe charging temperature, wireless charging continues until the temperature at the location of the metal foreign object exceeds the maximum safe charging temperature before charging stops.

[0062] The process of detecting metal foreign objects on the ground-based primary device 10 and the power receiving terminal 20, and determining whether to stop charging, includes the following steps:

[0063] S1: Obtain the initial static temperature reference point in standby mode;

[0064] S101. During equipment standby, sensor data is collected. This data can be used to determine the ambient temperature and steady-state characteristics of the equipment, and to determine whether there are any abnormalities in the sensors.

[0065] S102. Sensor data collected during equipment standby is used as an initial reference point to effectively avoid the influence of differences between different devices, sensors and environments.

[0066] S2: Working mode samples a certain amount of temperature status data in real time as a comparison point and updates the temperature data table accordingly;

[0067] S201. Collect the latest data at regular intervals and use it as a comparison point and reference point for dynamic adjustment.

[0068] S202. Store data collected in multiple rounds. The data storage adopts a cyclic update mechanism, which makes the software consume less CPU resources and update the valid data of the most recent period in real time.

[0069] S3: Calculate the difference between the temperature reference point and the real-time temperature data to determine whether there is a metal foreign object. Based on the calculated values ​​of the temperature comparison point and the reference temperature point, dynamically adjust the real-time data of the temperature reference point. Then, based on the temperature comparison point and the preset maximum safe charging temperature, determine whether to trigger the preset metal foreign object recognition event.

[0070] S301. The wireless charging device obtains comparison points by rapidly sampling data during operation and compares them with reference points obtained during standby. The feature parameters of the comparison include the difference in change between the comparison point and the reference point and the slope. When these two feature parameters reach the threshold, it is determined that there is a metal foreign object at this time.

[0071] S302. If any condition is not met, the feature data of the reference point at the corresponding position is updated dynamically in a timely manner, and the latest comparison point data of the reference point at the corresponding position is obtained to reduce feature changes caused by changes in the current device itself and the environment.

[0072] S303: After multiple rounds of data collection, the data is processed by the software and compared with preset values. If the data does not exceed the preset maximum safe charging temperature range, the device is determined to be in a safe operating environment. Even if a metal foreign object is detected, the preset event will not be triggered. If the data exceeds the preset maximum safe charging temperature range, it is considered that the device can no longer support safe charging operation, and a preset event needs to be triggered to stop charging, even if no metal foreign object is detected. By adding this preset value judgment condition, the device can effectively reduce charging equipment shutdown events while ensuring the safety of the charging equipment and the user, thereby significantly improving the user charging experience.

[0073] In practice, the higher the magnetic flux density of the device, the greater the slope of the temperature rise when a metal foreign object is present, that is, the greater the slope for determining the presence of a metal foreign object; however, the maximum safe charging temperature for the entire device is the same.

[0074] [Corrected according to Rule 91, May 27, 2025] In a specific embodiment, the magnetic flux density distribution of the coil inside the ground primary edge device 10 being detected is shown in Figure 7, wherein the magnetic flux density in the light gray area is higher than that in the dark gray area. The higher the magnetic flux density, the greater the slope when the metallic foreign object heats up;

[0075] Figure 8 shows the distribution of foreign object testing areas for ground-end equipment from a top-down perspective. The numbers in the upper right corner are the subdivision numbers of the areas, and A, B, C, and D are the codes for the larger areas.

[0076] As can be seen from Figures 7 and 8, the temperature slope of the metallic foreign object in region B1 is greater than that in region B12.

[0077] Figure 9 shows the sampling temperature and sampling resistance obtained by the flexible sensor in area B1 when the ambient temperature is 25℃ and there are no foreign objects.

[0078] The detection of metallic foreign objects and the implementation of protective measures based on flexible temperature sensors mainly rely on the following two characteristics as the basis for judgment:

[0079] 1. The temperature value "y" collected by the flexible temperature sensor "x" over a certain period of time shows an upward trend, and the slope of the temperature rise exceeds the set threshold.

[0080] 2. The temperature collected by the flexible temperature sensor exceeds the maximum safe charging temperature.

[0081] When a one-yuan coin is placed in area B1, the preset metal foreign object detection threshold is a temperature rise exceeding 1.5℃ within 5 seconds. A slope exceeding 0.3, calculated using the formula "K=Δy / Δx", indicates the presence of a metal foreign object. The maximum safe charging temperature is set at 80℃. In a test environment of 25℃, the system operates normally before a metal foreign object is placed. After the object is placed, a metal foreign object detection event is triggered, informing the user. At this point, the system does not trigger protection and charging can proceed normally. However, during wireless charging operation, if the foreign object is not removed, the flexible temperature sensor detects a temperature exceeding the 80℃ threshold, triggering forced protection and shutting down the system, as shown in Figure 10.

[0082] When a one-yuan coin is placed in area B12, the preset metal foreign object detection threshold is determined by a temperature rise exceeding 0.5℃ within 5 seconds and a calculated slope exceeding 0.1. The maximum safe charging temperature is set to 80℃. When the ambient temperature is 0℃, the system operates normally before a metal foreign object is placed. After the metal foreign object is placed, a foreign object detection event is triggered, and the user is notified that the system can charge normally. Due to the low ambient temperature, although the foreign object is not removed, its temperature rise does not reach the over-temperature protection threshold, so the system continues to operate. See Figure 11 for details.

[0083] In a specific embodiment, because the components of the sampling circuit have a certain error range, the actual protection value is within ±1% of the threshold.

[0084] This invention employs flexible temperature sensor technology. When the sensing film of the flexible temperature sensor senses a change in the physical quantity of temperature (using temperature as an example here, similarly, capacitance or voltage difference could be used), the change in resistance within the sensing film will form a functional relationship with the temperature value. The sensing film of the flexible sensor is equivalent to a variable resistor in the sensing circuit. The signal processing unit outputs an analog resistance signal, which is processed by a general analog-to-digital converter and an MCU controller to calculate the temperature to be detected. This yields the temperature of the corresponding area of ​​the wireless charging device. Furthermore, based on the temperature rise and other temperature factors, it can be determined whether there are metallic foreign objects in the corresponding area. The flexible temperature sensor possesses multiple excellent properties, including anti-electromagnetic interference, vibration resistance, high temperature resistance, and corrosion resistance, making it suitable for automotive-grade and other high-temperature applications. It requires stable operation in a specific environment. It uses flexible temperature sensors to detect the temperature rise of metallic foreign objects in an alternating magnetic field, thereby identifying the foreign objects and stopping charging promptly, effectively ensuring charging safety. During the detection of metallic foreign objects and the determination to stop wireless charging, several flexible temperature sensors, embedded in the ground-side device and the power receiver, sense the real-time temperature and accurate temperature values ​​of the corresponding areas. This allows them to determine whether metallic foreign objects are present in the corresponding areas of the ground-side device and the power receiver, and to decide whether to stop wireless charging based on whether the temperature exceeds the maximum safe charging temperature. It uses two sets of flexible temperature sensors to detect the presence of metallic foreign objects in the ground-side device and the power receiver under the vehicle, thus ensuring the reliable operation of the wireless charging process.

[0085] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0086] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A structure for detecting foreign objects in a wireless charging device, characterized in that, It includes: The ground-based edge device has a first flexible circuit board inside, and a number of flexible temperature sensors are arranged in an array on the first flexible circuit board. The array of flexible temperature sensors is used to monitor the temperature parameters in the surface area corresponding to the ground cover component. And the power receiving end, which has a built-in second flexible circuit board, on which a number of flexible temperature sensors are arranged in this row. The array of flexible temperature sensors is used to monitor the temperature parameters in the surface area corresponding to the bottom plate of the coil. In wireless charging operation, the coil base plate of the power receiver is positioned directly above the ground cover assembly of the ground-based device.

2. The structure for detecting foreign objects in a wireless charging device according to claim 1, characterized in that: The ground-based primary device includes, from bottom to top, a back plate, a first sensor signal control circuit board, a ferrite fixing plate assembly, a coil disk assembly, a first flexible circuit board, and a ground cover assembly. The ground cover assembly is installed on the back plate to form the inner cavity of the ground-based device. The first sensor signal control circuit board, the ferrite fixing plate assembly, the coil disk assembly, and the first flexible circuit board are arranged from bottom to top in the inner cavity of the ground-based device. A plurality of flexible temperature sensors are arranged in an array on one surface of the first flexible circuit board.

3. The structure for detecting foreign objects in a wireless charging device according to claim 1, characterized in that... The ground-side device, from bottom to top, includes a back plate, a first sensor signal control circuit board, a ferrite fixing plate assembly, a coil disk assembly, and a ground cover assembly. The first flexible circuit board is recessed on the upper surface of the ground cover assembly and covered with a fixing cover plate. After the ground cover assembly is installed on the back plate, it forms the inner cavity of the ground-side device. The first sensor signal control circuit board, the ferrite fixing plate assembly, and the coil disk assembly are arranged from bottom to top in the inner cavity of the ground-side device. A plurality of flexible temperature sensors are arranged in an array on one surface of the first flexible circuit board.

4. A structure for detecting foreign objects in a wireless charging device according to claim 2 or 3, characterized in that: The resistance values ​​of all flexible temperature sensors are connected to the first sensor signal control circuit board via flexible transmission lines on the first flexible circuit board. The first sensor signal control circuit board integrates a corresponding analog-to-digital conversion circuit and an MCU controller. The first sensor signal control circuit board drives the ground primary edge device to perform foreign object detection based on the temperature data obtained by the flexible temperature sensors on the first flexible circuit board and to determine whether charging is continuing.

5. The structure for detecting foreign objects in a wireless charging device according to claim 1, characterized in that: The power receiving end includes, from bottom to top, a coil base plate, a second flexible circuit board, a Litz coil, a ferrite assembly, a water-cooled plate assembly, a second sensor signal control circuit board, and a vehicle-side cover assembly. After the vehicle-side cover assembly and the coil base plate are closed, they form the inner cavity of the vehicle-side equipment. The inner cavity of the vehicle-side equipment is provided with, from bottom to top, a second flexible circuit board, a Litz coil, a ferrite assembly, a water-cooled plate assembly, and a second sensor signal control circuit board. A plurality of flexible temperature sensors are arranged in an array on one surface of the second flexible circuit board.

6. The structure for detecting foreign objects in a wireless charging device according to claim 1, characterized in that: The power receiving end includes, from bottom to top, a coil base plate, a second flexible circuit board, a Litz coil, a ferrite assembly, and a vehicle body end cover assembly. After the vehicle body end cover assembly and the coil base plate are closed, they form the inner cavity of the vehicle body end equipment. The second flexible circuit board, the Litz coil, and the ferrite assembly are arranged from bottom to top inside the inner cavity of the vehicle body end equipment. Several flexible temperature sensors are arranged in an array on one surface of the second flexible circuit board. In this structure, the signal control circuit board of the second sensor is external.

7. The structure for detecting foreign objects in a wireless charging device according to claim 1, characterized in that: The flexible temperature sensor is arranged in a pattern covering the center of the coil, the winding area of ​​the coil, and the outer edge of the winding of the magnetic coil, ensuring complete coverage detection of the coil.

8. A method for detecting foreign objects in a wireless charging device, characterized in that: It can detect metal foreign objects on the ground-based edge device and the power receiving end separately or simultaneously. During the charging process, it can monitor the temperature change of the entire surface area of ​​the corresponding device in real time. When any device detects that the temperature at the corresponding surface area exceeds the maximum safe charging temperature, the charging device will stop charging. If any device detects a metal foreign object, but the real-time temperature of the corresponding detection area does not exceed the maximum safe charging temperature, wireless charging will continue until the temperature at the location of the metal foreign object exceeds the maximum safe charging temperature before charging stops.

9. The method for detecting foreign objects in a wireless charging device according to claim 8, characterized in that: The process of detecting metal foreign objects on the ground-based primary equipment and power receiving end, and determining whether to stop charging, includes the following steps: S1: Obtain the initial static temperature reference point in standby mode; S2: Working mode samples a certain amount of temperature status data in real time as a comparison point and updates the temperature data table accordingly; S3: Analyze the temperature difference between the temperature reference point and the real-time temperature data to determine if there are any metal foreign objects. Based on the temperature difference between the temperature comparison point and the reference temperature point, dynamically adjust the real-time data of the temperature reference point. Then, based on the temperature comparison point and the preset maximum safe charging temperature, determine whether to trigger the preset over-temperature shutdown protection event.

10. The method for detecting foreign objects in a wireless charging device according to claim 9, characterized in that, Step S1 includes the following steps: S101. During the standby period of the equipment, sensor data is collected. This data can be used to determine the ambient temperature and steady-state characteristics of the equipment, and to determine whether there is any abnormality in the sensor. S102. Sensor data collected during equipment standby is used as an initial reference point to effectively avoid the influence of differences between different devices, sensors and environments. Step S2 includes the following steps: S201. Collect the latest data at regular intervals and use it as a comparison point and reference point for dynamic adjustment. S202. Store data collected in multiple rounds. The data storage adopts a cyclic update mechanism, which makes the software consume less CPU resources and update the effective data of the most recent period in real time. S301. The wireless charging device obtains comparison points by rapidly sampling data during operation and compares them with reference points obtained during standby. The feature parameters of the comparison include the difference in change between the comparison point and the reference point and the slope. When these two feature parameters reach the threshold, it is determined that there is a metal foreign object at this time. S302. If any condition is not met, the feature data of the reference point at the corresponding position is updated dynamically in a timely manner, and the latest comparison point data of the reference point at the corresponding position is obtained to reduce feature changes caused by changes in the current device itself and the environment. S303: After multiple rounds of data collection, the data is processed by the software and compared with preset values. If the data does not exceed the preset maximum safe charging temperature range, the device is determined to be in a safe operating environment. Even if a metal foreign object is detected, the preset event will not be triggered. If the data exceeds the preset maximum safe charging temperature range, it is considered that the device can no longer support safe charging operation, and a preset event needs to be triggered to stop charging, even if no metal foreign object is detected. By adding this preset value judgment condition, the device can effectively reduce charging equipment shutdown events while ensuring the safety of the charging equipment and the user, thereby significantly improving the user charging experience.

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