Foreign object detection method, apparatus, and wireless charging system

Abstract

The application provides a foreign matter detection method, device and wireless charging system. The foreign matter detection device comprises a coil array and a foreign matter detection circuit. The coil array comprises at least one coil group, and each coil group comprises four detection coils which are symmetrically arranged. The foreign matter detection circuit can acquire an induced signal generated by each detection coil. Then, the foreign matter detection circuit determines an abnormal value threshold of each coil group according to the induced signal of each coil group acquired in a first time period. Then, the foreign matter detection circuit detects whether there is a foreign matter based on the abnormal value threshold and the induced signal of each coil group. Then, the foreign matter detection circuit determines a signal threshold of each coil group according to the induced signal of each coil group in a case where no foreign matter is determined to exist. Then, the foreign matter detection circuit detects whether there is a foreign matter according to the signal threshold of each coil group and the induced signal of each coil group acquired in a second time period. The technical scheme provided by the application can improve the safety of wireless charging.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless power transmission, and in particular to a foreign matter detection method and device and a wireless charging system. BACKGROUND

[0002] With the aggravation of energy shortage and environmental pollution in modern society, electric vehicles as new energy vehicles have been widely concerned by all circles since they were launched. Electric vehicles use on-board power supply as power, and their charging methods usually include contact charging and wireless charging. Compared with contact charging, wireless charging has the advantages of convenient use, no spark and electric shock danger, no mechanical wear and tear, easy realization of unmanned automatic charging and mobile charging, and will become the mainstream of future electric vehicle charging.

[0003] A wireless power transmission (WPT) system mainly includes a power transmitting device connected with a power supply and a power receiving device connected with a load. The transmitting coil in the power transmitting device can transfer energy with the receiving coil in the power receiving device through electromagnetic induction. There is an air gap between the transmitting coil and the receiving coil, so foreign matter may enter. When there is metal foreign matter between the transmitting coil and the receiving coil, the metal foreign matter will heat up due to eddy current effect, which may cause safety problems such as self-ignition or burning of other objects. Therefore, in order to ensure safety, it is necessary to detect foreign matter. SUMMARY

[0004] Therefore, the present application provides a foreign matter detection method, device and wireless charging system to improve the safety of wireless charging.

[0005] To achieve the above purpose, in a first aspect, the present application provides a foreign matter detection method applied to a foreign matter detection circuit in a foreign matter detection device, the foreign matter detection device being applied to a wireless charging system, the foreign matter detection device further comprising a coil array, the coil array comprising at least one coil group, each coil group comprising four detection coils wound into a rectangle, the detection coils in the coil array being arranged into a matrix with an even number of rows and columns, four detection coils in the coil array that are mutually symmetrical in position being located in the same coil group, and each detection coil being electrically connected with the foreign matter detection circuit.

[0006] The method comprises:

[0007] obtaining an induced signal generated by each detection coil in each coil group;

[0008] determine an abnormal value threshold of each of the coil groups according to the inductive signals of each of the coil groups obtained in a first time period, the first time period being a preset time period after the inductive signals are obtained;

[0009] detect whether a foreign object exists in a detection area corresponding to the coil array according to the abnormal value threshold and the inductive signals of each of the coil groups.

[0010] The foreign object detection method provided in the embodiment can set a foreign object detection device in a wireless charging system, obtain inductive signals generated by each detection coil after charging starts, determine an abnormal value threshold of each coil group according to the inductive signals of each coil group obtained in a first time period, the first time period being a preset time period after the inductive signals are obtained, and detect whether a foreign object exists in a detection area corresponding to the coil array according to the abnormal value threshold and the inductive signals of each of the coil groups. In this way, a foreign object can be removed in time when the foreign object is detected, and thus the safety and charging efficiency of wireless charging can be improved.

[0011] Moreover, the technical solution dynamically determines an abnormal value threshold based on the obtained inductive signals, and detects a foreign object according to the abnormal value threshold. In this way, inherent errors (for example, errors caused by interference factors such as power adjustment, concrete layers, and protective shells) can be fused into the abnormal value threshold, and thus the anti-interference capability and environmental adaptability of foreign object detection can be improved.

[0012] In addition, the technical solution uses the symmetry of the detection coils to detect a foreign object in units of coil groups, and thus the algorithm complexity can be reduced.

[0013] In a possible implementation of the first aspect, the determination of the abnormal value threshold of each of the coil groups according to the inductive signals of each of the coil groups obtained in the first time period comprises:

[0014] The abnormal value threshold of each of the coil groups is determined by a quartile range method according to the signal values of the inductive signals of each of the coil groups obtained in the first time period.

[0015] In the above implementation, the quartile range method is used to determine the abnormal value threshold, which can reduce the algorithm complexity and improve the accuracy of the abnormal value threshold.

[0016] In a possible implementation of the first aspect, the coil groups include a plurality of groups, and the detection of whether a foreign object exists in a detection area corresponding to the coil array according to the abnormal value threshold and the inductive signals of each of the coil groups comprises:

[0017] For each of the coil groups, it is determined according to the abnormal value threshold of the coil group whether an abnormal value exists in the inductive signal of the coil group.

[0018] If the abnormal value exists in the induction signal of each coil group or does not exist in the induction signal of each coil group, it is determined that there is no foreign matter in the detection area corresponding to the coil array.

[0019] If the abnormal value exists in the induction signal of at least one coil group and does not exist in the induction signal of at least one coil group, it is determined that there is a foreign matter in the detection area corresponding to the coil array.

[0020] When an environmental abnormality occurs, such as a fluctuation in charging power in the initial charging stage, it will have an impact on the magnetic field in which the coil array is located. In the above-mentioned implementation, the environmental abnormality is considered when detecting foreign matter. When the abnormal value exists in the induction signal of each coil group, it is considered that an environmental abnormality has occurred, rather than a foreign matter, that is, there is no foreign matter in the detection area corresponding to the coil array. The foreign matter detection result determined in this way is more accurate.

[0021] In a possible implementation of the first aspect, the abnormal value threshold value includes a first threshold value and a second threshold value greater than the first threshold value, and the determination of whether the abnormal value exists in the induction signal of the coil group according to the abnormal value threshold value of the coil group includes:

[0022] determining whether a signal value less than the first threshold value or greater than the second threshold value exists in the induction signal of the coil group;

[0023] If the signal value less than the first threshold value or greater than the second threshold value exists in the induction signal of the coil group, it is determined that the abnormal value exists in the induction signal of the coil group;

[0024] If the signal value less than the first threshold value or greater than the second threshold value does not exist in the induction signal of the coil group, it is determined that the abnormal value does not exist in the induction signal of the coil group.

[0025] In the above-mentioned implementation, the abnormal value is determined based on the first threshold value and the second threshold value, and the algorithm complexity is low.

[0026] In a possible implementation of the first aspect, the method further includes:

[0027] If there is no foreign matter in the detection area corresponding to the coil array, for each coil group, the signal threshold value of the coil group is determined according to the induction signal of the coil group acquired in the first time period;

[0028] For at least one second time period after the first time period, whether there is a foreign matter in the detection area corresponding to the coil array is detected according to the signal threshold value of each coil group and the induction signal of each coil group acquired in the second time period.

[0029] In the above embodiment, in the case where no foreign matter is determined to exist, the signal threshold is determined based on the induced signals obtained in the first time period, and the foreign matter detection is subsequently performed according to the signal threshold, so that the processing speed can be improved.

[0030] In a possible implementation of the first aspect, the method further includes:

[0031] In the case where no foreign matter is determined to exist in the detection area corresponding to the coil array in the second time period, the signal threshold of each coil group is determined according to the induced signals of each coil group obtained in the second time period.

[0032] In the above embodiment, after the signal threshold is determined, the signal threshold can be updated in the subsequent detection process, so that the environmental adaptability of foreign matter detection can be further improved.

[0033] In a possible implementation of the first aspect, in the case where no foreign matter exists in the detection area corresponding to the coil array and no abnormal value exists in the induced signals of each coil group, the signal threshold of each coil group is determined according to the induced signals of each coil group obtained in the first time period. The signal threshold determined in this way is more accurate, so that the accuracy of the subsequent foreign matter detection result can be improved.

[0034] In a possible implementation of the first aspect, the signal values of the induced signals of the coil group obtained include multiple types, and each type of signal value has a corresponding signal threshold.

[0035] In the above embodiment, for each coil group, multiple types of signal values of induced signals are obtained, and foreign matter detection is performed based on the multiple types of signal values, so that the accuracy of the foreign matter detection result can be improved.

[0036] In a possible implementation of the first aspect, the signal values of the induced signals of the coil group obtained include the amplitude of each detection coil in the coil group and the phase difference between the detection coils in the coil group, and the signal threshold of the coil group includes an amplitude threshold and a phase difference threshold.

[0037] The amplitude and phase of the induced signals of the detection coils can more obviously reflect the change of the induced signals. In the above embodiment, the amplitude and phase difference of the induced signals of the detection coils are used for foreign matter detection, so that the detection sensitivity can be improved, and the signal acquisition can be facilitated.

[0038] In a possible implementation of the first aspect, the determination of the signal threshold of the coil group according to the induced signals of the coil group obtained in the first time period includes:

[0039] The signal threshold of each coil group is determined by using a mean value method according to the inductive signal of the coil group acquired in the first time period.

[0040] In the above embodiment, the signal threshold of each signal value is determined by using a mean value method, and the algorithm complexity is low.

[0041] In a possible implementation of the first aspect, the coil group includes a plurality of groups, and the detection of whether there is a foreign object in the detection area corresponding to the coil array according to the signal threshold of each coil group and the inductive signal of each coil group acquired in the second time period includes:

[0042] For each coil group, it is determined whether there is an abnormal value in the inductive signal of the coil group according to the signal threshold of the coil group and the inductive signal of the coil group acquired in the second time period.

[0043] If the inductive signal of each coil group has no abnormal value or has an abnormal value, it is determined that there is no foreign object in the detection area corresponding to the coil array.

[0044] If the inductive signal of at least one coil group of each coil group has an abnormal value, and the inductive signal of at least one coil group has no abnormal value, it is determined that there is a foreign object in the detection area corresponding to the coil array.

[0045] When an environmental anomaly occurs, such as parking deviation or charging power change, it will affect the magnetic field where the coil array is located. In the above embodiment, when the foreign object is detected, the environmental anomaly is considered. When there is an abnormal value in the inductive signal of each coil group, it is considered that an environmental anomaly occurs, instead of a foreign object, that is, there is no foreign object in the detection area corresponding to the coil array. The foreign object detection result determined in this way is more accurate.

[0046] In a possible implementation of the first aspect, the determination of whether there is an abnormal value in the inductive signal of the coil group according to the signal threshold of the coil group and the inductive signal of the coil group acquired in the second time period includes:

[0047] For each detection coil in the coil group, the absolute value of the difference between the average value of the signal value of the inductive signal of the detection coil acquired in the second time period and the signal threshold of the coil group is determined.

[0048] If the absolute value corresponding to each detection coil in the coil group is less than or equal to a preset value, it is determined that there is no abnormal value in the inductive signal of the coil group.

[0049] If the absolute value corresponding to at least one detection coil in the coil group is greater than the preset value, it is determined that there is an abnormal value in the inductive signal of the coil group.

[0050] In the above embodiment, the abnormal value judgment is performed based on the absolute value of the difference between the average value of the signal values of the induction signals of the detection coils and the corresponding signal threshold value, the algorithm complexity is low, and the accuracy of the judgment result is high.

[0051] In a possible implementation of the first aspect, after the wireless charging system starts to transmit electric energy, the method further includes: outputting an alternating excitation signal to each detection coil.

[0052] In the above embodiment, the foreign object detection circuit can provide an alternating excitation signal to each detection coil, that is, the detection is performed in a manner of having an excitation source, so that the strength of the induction signal of each detection coil mainly comes from the excitation source, thereby reducing the influence of the environmental magnetic field on the detection accuracy, and further improving the accuracy of foreign object detection.

[0053] In a possible implementation of the first aspect, the alternating excitation signal is output to each coil group in sequence; and / or, the alternating excitation signal is output to each detection coil in each coil group in sequence.

[0054] In the above embodiment, the detection coils in each coil group are sequentially gated to obtain the induction signal, so that the energy consumption can be saved.

[0055] In a possible implementation of the first aspect, the method further includes:

[0056] Before the wireless charging system starts to transmit electric energy, it is detected whether there is a foreign object in the detection area corresponding to the coil array.

[0057] In a case where it is determined that there is no foreign object in the detection area corresponding to the coil array, the wireless charging system is controlled to start to transmit electric energy.

[0058] In the above embodiment, foreign object detection is performed before charging, and charging is performed in a case where it is determined that there is no foreign object, so that the safety of wireless charging can be further improved.

[0059] In a second aspect, an embodiment of the present application provides a foreign object detection device, applied to a wireless charging system, the foreign object detection device includes: a coil array and a foreign object detection circuit;

[0060] The coil array includes at least one coil group, each coil group includes four detection coils wound into a rectangle, the detection coils in the coil array are arranged into a matrix with an even number of rows and an even number of columns, four detection coils with positions symmetrical to each other in the coil array are located in the same coil group, and each detection coil is electrically connected to the foreign object detection circuit.

[0061] The foreign matter detection circuit is configured to detect, according to an induced signal generated by each detection coil, whether a detection region corresponding to the coil array has a foreign matter.

[0062] The technical scheme provided in the embodiment sets a foreign matter detection device in the wireless charging system, the foreign matter detection device includes a coil array and a foreign matter detection circuit, the foreign matter detection circuit can detect, according to an induced signal generated by each detection coil, whether a detection region corresponding to the coil array has a foreign matter, so that the foreign matter can be removed in time in the case of detection of the foreign matter, and thus the safety and charging efficiency of the wireless charging can be improved. Moreover, the coil array includes at least one coil group, four detection coils that are symmetrical to each other in position are located in the same coil group, so that the symmetry of the detection coils can be utilized to perform foreign matter detection in units of coil groups, and thus the algorithm complexity can be reduced.

[0063] In a possible implementation of the second aspect, the coil group includes multiple groups. In this way, the sensitivity of foreign matter detection can be improved.

[0064] In a possible implementation of the second aspect, the foreign matter detection circuit includes an excitation source configured to provide an alternating excitation signal for the detection coils, and the detection coils are connected to the excitation source one by one. In this way, the requirement of the circuit on the power supply performance of the excitation source can be reduced.

[0065] In a possible implementation of the second aspect, the turn spacing of the detection coils gradually increases along a direction from the outside to the center.

[0066] The detection region corresponding to the coil close to the edge of the detection coil is relatively large, and the probability of the foreign matter being located in the edge region of the detection coil is relatively high. In the above implementation, the turn spacing of the edge region of the detection coil is greater than that of the middle region, so that the detection sensitivity of the edge region of the detection coil can be improved, and thus the foreign matter detection efficiency can be improved. In addition, the influence of the coil in the edge region of the detection coil on the magnetic field strength is greater than that of the coil in the middle region. Increasing one turn of the coil in the edge region of the detection coil can increase the magnetic field strength equivalent to increasing multiple turns of the coil in the middle region. Increasing the number of turns of the coil can increase the impedance of the detection coil. In the case of increasing the same magnetic field strength, using the way of increasing the number of turns of the coil in the middle region can bring higher impedance. Therefore, using smaller turn spacing in the edge region of the detection coil and larger turn spacing in the middle region can improve the detection sensitivity of the detection coil while reducing the impedance of the detection coil, and thus reducing the power consumption of the detection coil.

[0067] In a possible implementation of the second aspect, the foreign matter detection circuit is configured to perform the method in the first aspect or any implementation of the first aspect.

[0068] The beneficial effects of this embodiment can be referred to the above description of the first aspect, which will not be repeated here.

[0069] In a third aspect, the embodiments of the present application provide a wireless charging system, comprising: a power transmitting device and a foreign matter detection device;

[0070] The foreign matter detection device comprises: a coil array and a foreign matter detection circuit;

[0071] The coil array comprises at least one coil group, each coil group comprises four detection coils wound in a rectangle, the detection coils in the coil array are arranged in a matrix with an even number of rows and an even number of columns, four detection coils that are symmetrical to each other in position in the coil array are located in the same coil group, and each detection coil is electrically connected to the foreign matter detection circuit;

[0072] The foreign matter detection circuit comprises: a signal acquisition unit and a signal processing unit, and the signal processing unit is electrically connected to the signal acquisition unit, wherein:

[0073] The signal acquisition unit is configured to acquire an induced signal generated by each detection coil in each coil group under the control of the signal processing unit;

[0074] The signal processing unit is configured to: determine an outlier threshold value of each coil group according to the induced signal of each coil group acquired within a first time period; and detect whether there is a foreign matter in a detection area corresponding to the coil array according to the outlier threshold value and the induced signal of each coil group, the first time period being a preset time period after the induced signal is acquired.

[0075] In a possible implementation of the third aspect, the signal processing unit is specifically configured to:

[0076] For each coil group, the outlier threshold value of the coil group is determined by a quartile range method according to a signal value of the induced signal of the coil group acquired within the first time period.

[0077] In a possible implementation of the third aspect, the coil group comprises a plurality of groups, and the signal processing unit is specifically configured to:

[0078] For each coil group, it is determined whether there is an outlier in the induced signal of the coil group according to the outlier threshold value of the coil group;

[0079] If there is the outlier in the induced signal of each coil group or there is no outlier, it is determined that there is no foreign matter in the detection area corresponding to the coil array;

[0080] If there is an abnormal value in the induced signal of at least one of the coil groups and there is no abnormal value in the induced signal of at least one of the coil groups, it is determined that there is a foreign object in the detection area corresponding to the coil array.

[0081] In a possible implementation of the third aspect, the abnormal value threshold includes a first threshold and a second threshold greater than the first threshold, and the signal processing unit is specifically configured to:

[0082] determine whether there is a signal value less than the first threshold or greater than the second threshold in the induced signal of the coil group;

[0083] if there is a signal value less than the first threshold or greater than the second threshold in the induced signal of the coil group, it is determined that there is the abnormal value in the induced signal of the coil group;

[0084] if there is no signal value less than the first threshold or greater than the second threshold in the induced signal of the coil group, it is determined that there is no abnormal value in the induced signal of the coil group.

[0085] In a possible implementation of the third aspect, the signal processing unit is further configured to:

[0086] if there is no foreign object in the detection area corresponding to the coil array, for each coil group, the signal threshold of the coil group is determined according to the induced signal of the coil group acquired in the first time period;

[0087] for at least one second time period after the first time period, whether there is a foreign object in the detection area corresponding to the coil array is detected according to the signal threshold of each coil group and the induced signal of each coil group acquired in the second time period.

[0088] In a possible implementation of the third aspect, the signal processing unit is further configured to:

[0089] if it is determined that there is no foreign object in the detection area corresponding to the coil array in the second time period, the signal threshold of each coil group is determined according to the induced signal of each coil group acquired in the second time period.

[0090] In a possible implementation of the third aspect, the signal processing unit is specifically configured to: if there is no foreign object in the detection area corresponding to the coil array and there is no abnormal value in the induced signal of each coil group, the signal threshold of each coil group is determined according to the induced signal of each coil group acquired in the first time period.

[0091] In a possible implementation of the third aspect, the signal values of the acquired induced signals of the coil group include a plurality of signal values, each of the signal values having a corresponding signal threshold.

[0092] In a possible implementation of the third aspect, the signal values of the acquired induced signals of the coil group include an amplitude value of each of the detection coils in the coil group and a phase difference between the detection coils in the coil group, and the signal threshold of the coil group includes an amplitude threshold and a phase difference threshold.

[0093] In a possible implementation of the third aspect, the signal processing unit is specifically configured to:

[0094] determine the signal threshold of the coil group by using a mean value method according to the induced signals of the coil group acquired in the first time period.

[0095] In a possible implementation of the third aspect, the coil group includes a plurality of coil groups, and the signal processing unit is specifically configured to:

[0096] For each of the coil groups, determine whether the induced signals of the coil group have outliers according to the signal threshold of the coil group and the induced signals of the coil group acquired in the second time period.

[0097] If the induced signals of all the coil groups have no outliers or all have outliers, it is determined that the detection area corresponding to the coil array has no foreign matter.

[0098] If the induced signals of at least one of the coil groups have outliers and the induced signals of at least one of the coil groups have no outliers, it is determined that the detection area corresponding to the coil array has foreign matter.

[0099] In a possible implementation of the third aspect, the signal processing unit is specifically configured to:

[0100] For each of the detection coils in the coil group, determine an absolute value of a difference between a mean value of the signal values of the induced signals of the detection coil acquired in the second time period and the signal threshold of the coil group.

[0101] If the absolute value corresponding to each of the detection coils in the coil group is less than or equal to a preset value, it is determined that the induced signals of the coil group have no outliers.

[0102] If the absolute value corresponding to at least one of the detection coils in the coil group is greater than the preset value, it is determined that the induced signals of the coil group have outliers.

[0103] In a possible implementation of the third aspect, the foreign matter detection circuit further includes an excitation source, which is electrically connected to the signal processing unit, and the signal processing unit is further configured to: control the excitation source to output an alternating excitation signal to each detection coil after the wireless charging system starts to transmit electric energy.

[0104] In a possible implementation of the third aspect, the signal processing unit is specifically configured to: control the excitation source to sequentially output the alternating excitation signal to each coil group; and / or, sequentially output the alternating excitation signal to each detection coil in each coil group.

[0105] In a possible implementation of the third aspect, the signal processing unit is further configured to:

[0106] detect whether there is a foreign matter in a detection area corresponding to the coil array before the wireless charging system starts to transmit electric energy;

[0107] in a case where it is determined that there is no foreign matter in the detection area corresponding to the coil array, control the wireless charging system to start to transmit electric energy.

[0108] In a fourth aspect, an embodiment of the present application provides a foreign matter detection device, including: a memory and a processor, the memory is used to store a computer program; the processor is used to execute the method in the first aspect or any implementation of the first aspect when the computer program is called.

[0109] In a fifth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method in the first aspect or any implementation of the first aspect.

[0110] In a sixth aspect, an embodiment of the present application provides a computer program product, which, when running on an electronic device, causes the electronic device to execute the method in the first aspect or any implementation of the first aspect.

[0111] In a seventh aspect, an embodiment of the present application provides a chip system, including a processor, the processor is coupled with a memory, and the processor executes a computer program stored in the memory to implement the method in the first aspect or any implementation of the first aspect. The chip system can be a single chip or a chip module composed of multiple chips.

[0112] It can be understood that the beneficial effects of the third aspect to the seventh aspect can be referred to the related description in the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0113] Figure 1An architecture schematic diagram of a wireless power transmission system provided by an embodiment of the present application is shown in FIG. 1.

[0114] Figure 2 An application scenario schematic diagram provided by an embodiment of the present application is shown in FIG. 2.

[0115] Figure 3 Another application scenario schematic diagram provided by an embodiment of the present application is shown in FIG. 3.

[0116] Figure 4 A structure schematic diagram of a foreign matter detection device provided by an embodiment of the present application is shown in FIG. 4.

[0117] Figure 5 A structure schematic diagram of a coil array provided by an embodiment of the present application is shown in FIG. 5.

[0118] Figure 6 A structure schematic diagram of a detection coil provided by an embodiment of the present application is shown in FIG. 6.

[0119] Figure 7 Another structure schematic diagram of a coil array provided by an embodiment of the present application is shown in FIG. 7.

[0120] Figure 8 A division result schematic diagram of a coil group provided by an embodiment of the present application is shown in FIG. 8.

[0121] Figure 9 A flow schematic diagram of a foreign matter detection method provided by an embodiment of the present application is shown in FIG. 9.

[0122] Figure 10 An abnormality detection process schematic diagram of a coil group A provided by an embodiment of the present application is shown in FIG. 10.

[0123] Figure 11 A structure schematic diagram of a foreign matter detection device provided by an embodiment of the present application is shown in FIG. 11. DETAILED DESCRIPTION

[0124] In a wireless charging system, a metal foreign matter or a biological body (e.g., a bird) or the like can enter between a transmitting coil and a receiving coil. When a metal foreign matter exists between the transmitting coil and the receiving coil, the metal foreign matter can heat up due to an eddy current effect, which can cause a safety problem such as self-ignition (e.g., a tin foil can self-ignite when the temperature of the tin foil is high enough) or burning of other objects (e.g., leaves or paper sheets located on the metal can burn due to the heat of the metal) or the like; if a biological body exists between the transmitting coil and the receiving coil, a high-frequency alternating magnetic field between the transmitting coil and the receiving coil can cause a certain degree of harm to the health of the biological body; in addition, the existence of the foreign matter can also affect the charging efficiency.

[0125] To solve the above problems, the embodiment provides a foreign matter detection method, device and wireless charging system to improve the safety and charging efficiency of wireless charging. The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation manner part of the embodiments of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0126] Figure 1 The architecture schematic diagram of the wireless power transmission system provided by the embodiment of the present application is shown in FIG. 1, which can include a power transmitting device 10, a power receiving device 20 and a foreign matter detection device 30. Figure 1

[0127] The power receiving device 20 can be arranged in a power receiving equipment, Figure 2 and Figure 3 The two application scenario schematic diagrams of the wireless power transmission system are shown in FIGS. 2 and 3, which can be Figure 2 and Figure 3 The power receiving equipment can be Figure 2 the electric vehicle shown in FIG. 2, or Figure 3 the mobile terminal shown in FIG. 3. The electric vehicle can be an electric car or an electric bicycle, etc., Figure 2 the electric car is exemplarily illustrated in the embodiment; in addition, the mobile terminal can be a mobile phone, a tablet computer or a smart wearable device, etc., Figure 3 the mobile phone is exemplarily illustrated in the embodiment.

[0128] The power transmitting device 10 is arranged in a charging equipment, which can be Figure 2 the non-portable charging board shown in FIG. 4, or Figure 3 the portable charger shown in FIG. 5. The charging board can be arranged in a wireless charging station, a wireless charging parking space or a wireless charging road, etc., which can be arranged on the ground or buried under the ground, Figure 2 the charging board buried under the ground is exemplarily illustrated in the embodiment.

[0129] It can be understood that the power receiving equipment is not limited to the above electric vehicle and mobile terminal, but can also be other electronic equipment supporting wireless charging, such as an electric robot; similarly, the charging equipment is not limited to the above charging board and charger, and the type of the power receiving equipment and the charging equipment is not particularly limited in the embodiment.

[0130] ​The power transmitting device 10 and the power receiving device 20 can transmit energy to each other through electromagnetic induction. The power transmitting device 10 can be connected with a power supply, and the power receiving device 20 can be connected with a power supply of a device to be charged. When the device to be charged enters the wireless charging range of the power transmitting device 10, the wireless charging system is started, and the power supply can charge the power supply of the device to be charged through the power transmitting device 10 and the power receiving device 20.

[0131] Specifically, the power transmitting device 10 can include a transmitting coil and a transmitting control circuit connected with the transmitting coil. The transmitting coil can form a resonance circuit with inductance and capacitance and the like to improve transmission efficiency. The transmitting control circuit can provide high-frequency alternating current for the transmitting coil to generate an alternating magnetic field, and transmit energy through the alternating magnetic field.

[0132] The transmitting control circuit is connected with the power supply, which can be an alternating current power supply to reduce the complexity of the circuit structure, or a direct current power supply to reduce the cost. When the power supply is a direct current power supply, the transmitting control circuit can convert the direct current generated by the power supply into high-frequency alternating current through an inverter circuit.

[0133] The power receiving device 20 can include a receiving coil and a receiving control circuit connected with the receiving coil. The receiving coil is coupled with the transmitting coil and can receive energy through the alternating magnetic field generated by the transmitting coil to generate an induced current or voltage. The receiving control circuit can convert the induced current or voltage generated by the transmitting coil into direct current or voltage through a rectifier circuit to charge the power supply of the device to be charged.

[0134] It can be understood that the above is only a brief introduction to the power transmitting device 10 and the power receiving device 20. The power transmitting device 10 and the power receiving device 20 can also include other modules, such as a communication module and a storage module. The specific structure of the power transmitting device 10 and the power receiving device 20 is not particularly limited in the embodiment.

[0135] In order to improve the safety and charging efficiency of wireless charging, the foreign matter detection device 30 is arranged between the power transmitting device 10 and the power receiving device 20 in the embodiment. The foreign matter detection device 30 can be arranged on the power receiving side. Considering that there are relatively many power receiving devices, in order to reduce the cost and improve the convenience of arranging the foreign matter detection device 30, as shown in Figure 1 The foreign matter detection device 30 can also be arranged on the charging side to form a wireless charging system with the power transmitting device 10.

[0136] In specific implementation, the power transmitting device 10 and the foreign matter detection device 30 can be arranged in different devices, for example Figure 2As shown, the power transmitting device 10 is disposed in the charging pad, and the foreign object detection device 30 is disposed in a foreign object detection device above the charging pad. The power transmitting device 10 and the foreign object detection device 30 can also be disposed in the same device, for example... Figure 3 As shown, both the power transmitting device 10 and the foreign object detection device 30 are located in the charger.

[0137] Understandably, in the scenario of wireless charging for electric vehicles, the power transmitting device 10 and the foreign object detection device 30 can also be set in the same device, that is, both can be set on the charging plate. Figure 2 The example provided is merely illustrative of the power transmitting device 10 and the foreign object detection device 30 being installed in different devices, and is not intended to limit this application.

[0138] Figure 4 This is a schematic diagram of the foreign object detection device provided in the embodiments of this application, as shown below. Figure 1 and Figure 4 As shown, the foreign object detection device 30 may include a coil array 31 and a foreign object detection circuit 32.

[0139] Specifically, such as Figure 4 As shown, the coil array 31 can be laid between the transmitting coil and the receiving coil, and its laying plane can be parallel to the laying plane of the transmitting coil. The projection of the center of the coil array 31 onto the laying plane of the transmitting coil can coincide with the center of the transmitting coil. The coverage area of ​​the coil array 31 can be greater than or equal to the coverage area of ​​the transmitting coil, so that foreign object detection can be performed on the entire detection area corresponding to the transmitting coil (i.e., the projection area of ​​the transmitting coil towards the receiving coil). Similar to the power transmitting device 10, the coil array 31 can be installed on the ground or buried underground.

[0140] Figure 5 This is a schematic diagram of the coil array structure provided in the embodiments of this application, as shown below. Figure 5 As shown, the coil array 31 may include multiple detection coils 311 arranged in a matrix. The material, number of turns and winding method of each detection coil 311 may be the same. Specifically, the detection coil 311 may be wound into a rectangular structure to eliminate the star-shaped blind zone between the circular coils.

[0141] The detection coil 311 can be made by winding wire or by using a printed circuit board (PCB) coil to reduce the error generated during the coil winding process.

[0142] Figure 6 This is a schematic diagram of the detection coil provided in the embodiments of this application, as shown below. Figure 6As shown in (a) of FIG. 11, the detection coil 311 can be a coil structure with uniform coil density, i.e., each turn of the coil is arranged at equal intervals. This winding method is relatively simple.

[0143] Considering that the detection area corresponding to the coil close to the edge of the detection coil 311 is relatively large, and the probability of the foreign object being located in the edge area of the detection coil 311 is relatively high, in this embodiment, the turn spacing of the edge area of the detection coil 311 can be greater than the turn spacing of the middle area, for example Figure 6 As shown in (b) of FIG. 11, the turn spacing of the detection coil 311 increases from outside to inside, which can improve the detection sensitivity of the edge area of the detection coil 311. In addition, the influence of the coil in the edge area of the detection coil 311 on the magnetic field strength is greater than that of the coil in the middle area. Adding a turn of coil in the edge area of the detection coil 311 can increase the magnetic field strength equivalent to adding multiple turns of coil in the middle area. Increasing the number of turns of coil can increase the impedance of the detection coil 311. In the case of increasing the same magnetic field strength, using the method of increasing the number of turns of coil in the middle area will bring higher impedance. Therefore, using smaller turn spacing in the edge area of the detection coil 311 and larger turn spacing in the middle area can improve the detection sensitivity of the detection coil 311 while reducing the impedance of the detection coil 311, thereby reducing the power consumption of the detection coil 311.

[0144] It can be understood that Figure 6 This is only an example and is not intended to limit the present application. For example, the detection coil 311 can be divided into two parts from outside to inside: an edge area with a first width and a middle area with a second width. The coils in the edge area are arranged at equal intervals with a first turn spacing, and the coils in the middle area are arranged at equal intervals with a second turn spacing. In specific implementation, the arrangement of the detection coil 311 can be selected as needed, and this embodiment does not particularly limit it.

[0145] In this embodiment, each detection coil 311 is electrically connected to the foreign object detection circuit 32. The detection coil 311 in the coil array 31 can generate an induced signal under the action of the environmental magnetic field (i.e., the magnetic field between the transmitting coil and the receiving coil). When there is a foreign object in the detection area corresponding to the detection coil 311, the induced signal of the detection coil 311 will change under the influence of the foreign object. Based on this, the foreign object detection circuit 32 can detect whether there is a foreign object in the detection area corresponding to the coil array 31 according to the induced signal generated by each detection coil 311.

[0146] Ideally, the magnitude and distribution of the ambient magnetic field experienced by the detection coils 311 symmetrical about the row or column center lines in the coil array 31 are basically the same. Correspondingly, the induced signals generated by these symmetrical detection coils 311 are also basically the same. This characteristic can be utilized for foreign object detection to reduce algorithm complexity. Therefore, in this embodiment, the number of rows and columns of the detection coils 311 in the coil array 31 can both be even numbers. For the foreign object detection device 30 applied to electric vehicles, at least one of the number of rows and columns of the coil array 31 can be a multiple of 4 to improve the sensitivity of foreign object detection. Figure 5 The example shown uses a row and column count of 4.

[0147] Considering that if the induced signals of the detection coils 311 all originate from the ambient magnetic field, i.e., the magnetic field generated by the charging coils (including the transmitting and receiving coils) is the only excitation source, the foreign object detection device 30 cannot detect existing foreign objects without excitation. Furthermore, when detecting foreign objects based on the symmetry of the detection coils 311, the detection accuracy is mainly determined by the ambient magnetic field. However, the magnitude and distribution of the ambient magnetic field are nonlinear and non-uniform, and may change, which can affect the accuracy of the detection results. Therefore, in this embodiment, an excitation-source detection method can be adopted. That is, the foreign object detection circuit 32 can provide AC excitation signals to each detection coil 311, so that the intensity of the induced signals of each detection coil 311 mainly comes from the excitation signal provided by the foreign object detection circuit 32, thereby reducing the influence of the ambient magnetic field on the detection accuracy and improving the accuracy of foreign object detection. It is understood that the main difference between excitation-source detection and non-excitation-source detection is that the intensity of the induced signals of each detection coil 311 is stronger in excitation-source detection. The foreign object detection process of the two methods is similar. For ease of explanation, the following description uses excitation-source detection as an example.

[0148] After the foreign object detection circuit 32 outputs an AC excitation signal to the coil array 31, each detection coil 311 in the coil array 31 is affected not only by the ambient magnetic field but also by the magnetic field of the surrounding detection coils. As mentioned earlier, this embodiment utilizes the symmetry of the detection coils for foreign object detection. Based on this, the wiring structure of the detection coils 311 in the coil array 31 can include, but is not limited to, the following two methods:

[0149] The first type, see [link / reference] Figure 5 The wiring structure of each detection coil 311 in the array is the same, for example... Figure 5 As shown, each detection coil 311 is wound clockwise, with the outer terminals facing upwards.

[0150] The second type, see [link] Figure 7The coil array 31 can be divided into four quadrants according to the row center line and column center line of the coil array 31. The routing structure of each detection coil 311 in the same quadrant is the same, and the routing structure of the detection coil 311 in adjacent quadrants is symmetrical with respect to the center line between the adjacent quadrants.

[0151] For example Figure 7 As shown, in the upper left second quadrant, each detection coil 311 is wound clockwise with its outer terminals facing upwards; in the upper right first quadrant, the wiring structure of the detection coil 311 in the second quadrant is symmetrical with respect to the column center line of the coil array 31, and each detection coil 311 in the first quadrant is wound counterclockwise with its outer terminals facing upwards; in the lower left third quadrant, the wiring structure of the detection coil 311 in the second quadrant is symmetrical with respect to the row center line of the coil array 31, and each detection coil 311 in the third quadrant is wound counterclockwise with its outer terminals facing downwards; in the lower right fourth quadrant, the wiring structure of the detection coil 311 in the third quadrant is symmetrical with respect to the column center line of the coil array 31, and each detection coil 311 in the fourth quadrant is wound clockwise with its outer terminals facing downwards. The wiring structure of the detection coil 311 in the fourth quadrant is also symmetrical with respect to the row center line of the coil array 31, as is the wiring structure of the detection coil 311 in the first quadrant.

[0152] The first wiring structure ensures that two detection coils 311 symmetrical about the row or column center line of the coil array 31 experience the same ambient magnetic field. This structure is relatively simple and easy to manufacture. The second wiring structure ensures that two detection coils 311 symmetrical about the row or column center line of the coil array 31 experience the same magnetic field from the surrounding detection coils. In practical applications, the wiring structure of each detection coil 311 in the coil array 31 can be selected as needed; this embodiment does not impose any particular limitation on this.

[0153] like Figure 4 As shown, the foreign object detection circuit 32 may include an excitation source 321, a signal acquisition unit 322, and a signal processing unit 323.

[0154] The excitation source 321 is similar to the power supply in the power transmitting device 10. It can directly use an AC power supply to provide AC power (i.e., excitation signal) to the detection coil 311; or it can use a DC power supply plus an inverter circuit to convert the DC power generated by the DC power supply into high-frequency AC power to save costs. The voltage of the excitation source 321 can be selected as needed, for example, it can be 4V or 12V.

[0155] In the embodiment, when the coil array 31 is connected with the excitation source 321, the detection coils 311 can not be connected in series with each other, so as to avoid the influence of the parasitic parameters caused by the series connection on the detection result. In addition, considering that the excitation source 321 has a certain power upper limit, the detection coils 311 can also not be connected in parallel with each other, that is, each detection coil 311 uses an independent excitation source to provide an excitation signal, so as to reduce the requirement of the circuit on the excitation source.

[0156] The signal value of the induced signal of the detection coil 311 acquired by the signal acquisition unit 322 can include at least one of the following: voltage (which can be a root mean square value, an instantaneous value, a peak-to-peak value or an amplitude value), current, impedance, phase and the like.

[0157] The signal acquisition unit 322 can collect the induced signals of the detection coils 311 or acquire the induced signals of the detection coils 311 from other circuits. In the embodiment, the signal acquisition unit 322 actively collects the induced signals of the detection coils 311 as an example for illustrative description.

[0158] The signal processing unit 323 can control the excitation source 321 to provide an excitation signal, acquire the induced signal acquired by the signal acquisition unit 322, and perform foreign matter detection based on the acquired induced signal.

[0159] It can be understood that the structure of the foreign matter detection circuit 32 is not limited to Figure 4 the structure shown. In order to improve the accuracy of the detection result, the induced signal acquired by the signal acquisition unit 322 can also be output to the signal processing unit 323 after being amplified and filtered, so that the signal processing unit 323 performs foreign matter detection, that is, the foreign matter detection circuit 32 can also include other circuit modules such as a signal amplification circuit and a signal filtering circuit. The specific circuit structure of the foreign matter detection circuit 32 is not particularly limited in the embodiment. The circuit structures included in the foreign matter detection circuit 32 can be realized in the form of hardware, software or a combination of software and hardware, and multiple circuit structures can also be integrated in the same component.

[0160] When the foreign matter detection circuit 32 performs foreign matter detection, for each detection coil 311, the signal value of the induced signal of the detection coil 311 acquired by the signal acquisition unit 322 can be compared with a preset signal threshold, so as to determine whether the induced signal of the detection coil 311 is abnormal, and further determine whether the detection area corresponding to the detection coil 311 has foreign matter.

[0161] Considering that system parameters may change during the use of the wireless charging system, such as adjustments to the charging power, and that the foreign object detection device 30 may be subject to environmental interference (e.g., when buried underground, the coil array 31 may be affected by interference from the concrete layer and protective shell), the effectiveness of the preset signal threshold will decrease, requiring further adjustments. Furthermore, once the foreign object detection device 30 is encapsulated and buried underground, the internally preset signal threshold becomes difficult to correct. Therefore, in this embodiment, during foreign object detection, an outlier threshold can be dynamically determined based on the acquired sensing signal. This integrates inherent errors (such as those caused by power adjustments, concrete layers, and protective shells) into the outlier threshold, and then performs foreign object detection based on this threshold to improve the anti-interference capability and environmental adaptability of foreign object detection. To improve processing speed, the signal threshold can be determined based on the acquired sensing signal when it is determined that there are no foreign objects in the detection area corresponding to the coil array 31. Subsequent foreign object detection can then be performed based on this signal threshold. The foreign object detection process is described below.

[0162] As mentioned earlier, this embodiment utilizes the symmetry of the detection coils for foreign object detection. The magnitude and distribution of the ambient magnetic field experienced by the detection coils symmetrical with respect to the row center line or column center line in the coil array 31 are approximately the same. Therefore, in practical implementation, four detection coils with symmetrical positions in the coil array 31 (i.e., two detection coils symmetrical with respect to the row center line and two detection coils symmetrical with respect to the column center line) can be considered as the same coil group, and foreign object detection can be performed on a coil group basis. That is, the four detection coils in each coil group are arranged in a 2×2 array. The two detection coils in the same row of the same coil group are symmetrically distributed with respect to the column center line of the coil array 31, and the two detection coils in the same column of the same coil group are symmetrically distributed with respect to the row center line of the coil array 31.

[0163] by Figure 5 Taking the coil array 31 shown as an example, the corresponding coil group division result can be as follows: Figure 8 As shown, coil group A includes detection coils A1, A2, A3 and A4; coil group B includes detection coils B1, B2, B3 and B4; coil group C includes detection coils C1, C2, C3 and C4; and coil group D includes detection coils D1, D2, D3 and D4.

[0164] Based on the above grouping, when performing foreign object detection during charging, for each coil group, the signal threshold of that coil group can be determined initially based on the acquired induction signal; later, foreign object detection can be performed based on the determined signal thresholds of each coil group. For details, please refer to [link to documentation]. Figure 9 , Figure 9A flowchart of the foreign matter detection method provided by the embodiments of the present application is shown in FIG. 3. Figure 9 As shown in FIG. 3, the method can include the following steps:

[0165] In S110, during the transmission of electric energy by the wireless charging system, an alternating excitation signal is output to each detection coil in each coil group, and an induced signal generated by each detection coil in each coil group is acquired.

[0166] Specifically, when the charging is started, the foreign matter detection circuit can output the same alternating excitation signal to each detection coil in the coil array; and the signal value of the acquired induced signal of the detection coil can include at least one of the aforementioned signal values such as voltage, current, impedance and phase.

[0167] In this embodiment, the use of multiple signal values of the induced signal can improve the accuracy of the foreign matter detection result. For example, the signal value of the acquired induced signal of the detection coil includes the amplitude and phase of the detection coil. Considering that the phase of a single detection coil is difficult to collect, the induced signals of the detection coils in the same coil group are basically consistent, and therefore, when the induced signal is acquired, for each coil group, the phase difference between the detection coils in the coil group can also be acquired for foreign matter detection. For example, the phase difference between each detection coil and every other detection coil in the coil group can be collected, or the phase difference between adjacent detection coils in the coil group can be collected. That is, for each coil group, the acquired signal value of the induced signal can include the amplitude of each detection coil in the coil group and the phase difference between each pair of adjacent detection coils in the coil group. In this embodiment, the foreign matter detection process will be exemplarily described below based on this example.

[0168] For each detection coil, after the charging is started, the induced signal in a preset time period (hereinafter referred to as a first time period) can be acquired. In the first time period, the signal value of the acquired induced signal of each detection coil can include multiple signal values to improve the accuracy of the detection result. The first time period can be a preset time length, or can be determined in advance according to the number of signal values of the acquired induced signal, i.e., the time length required to acquire a preset number (such as 100) of signal values.

[0169] In this embodiment, the alternating excitation signal can be continuously output to each detection coil in parallel, and the induced signal generated by each detection coil can be collected in parallel. Alternatively, the detection coils in each coil group can be sequentially gated for collection of the induced signal. The collection of the induced signal in parallel has higher real-time performance, and the collection of the induced signal sequentially can save energy. In actual application, the collection of the induced signal can be selected as needed, and this embodiment does not particularly limit the collection of the induced signal. In this embodiment, the collection of the induced signal will be exemplarily described below based on the collection of the induced signal sequentially.

[0170] Specifically, for the way of sequentially collecting the induced signals, in the first time period, each coil group can be sequentially gated according to a preset order (hereinafter referred to as a first preset order), the alternating excitation signal is output to the gated coil group, and the induced signal is collected. For example, for the four coil groups shown in FIG. 6, the excitation signal can be output to each coil group and the induced signal can be collected in the order of A→B→C→D. Figure 8

[0171] For each coil group, each detection coil in the coil group can also be sequentially gated according to a preset order (hereinafter referred to as a second preset order), the alternating excitation signal is output to the gated detection coil, and the induced signal is collected. For example, for coil group A, considering the collection of phase difference, each pair of detection coils can be sequentially gated in the order of A1A2→A2A3→A3A4→A4A1, the excitation signal is output to the gated detection coil, and the induced signal is collected.

[0172] In S120, the abnormal value threshold of each coil group is determined according to the induced signal of each coil group obtained in the first time period, and whether there is a foreign object in the detection area corresponding to the coil array is detected according to the abnormal value threshold of each coil group and the induced signal of each coil group obtained in the first time period.

[0173] As described above, for each detection coil, the signal value of the induced signal of the detection coil obtained in the first time period can include multiple. Taking coil group A as an example, as shown in FIG. 7, when detection coils A1 and A2 are gated, the amplitude and phase difference of k cycles can be obtained and stored in array A Figure 10 12 (Step S1), that is, array A 12 includes k groups of data, and each group of data includes the amplitude of A1, the amplitude of A2, and the phase difference of A1A2. The phase difference of A1A2 can be the difference between the phase of one of A1 and A2 and the phase of the other, or the absolute value of the phase difference between A1 and A2. Each signal value in array A 12 can be labeled, and the corresponding detection coil is identified by the label.

[0174] For each signal value stored in array A 12 , the signal value can also be determined based on multiple sampling values in one sampling period. For example, for the amplitude of A1, in each of the above k cycles, multiple sampling values can be sampled, and the average of the sampling values is taken as the amplitude of A1 obtained in the cycle. In this way, the influence of circuit signal fluctuation on the obtained result can be reduced.

[0175] ​​After the data of the detection coils A1A2 is acquired, A2A3, A3A4, and A4A1 are sequentially gated, and the data acquisition mode of the other detection coils in the coil group A is similar to that of the detection coils A1A2. Each time a detection coil is gated, it corresponds to an array. Specifically, the detection coil A2A3 corresponds to the array A 23 , the detection coil A3A4 corresponds to the array A 34 , and the detection coil A4A1 corresponds to the array A 41 (Step S2).

[0176] As described above, the AC excitation signals received by each detection coil in the same coil group are the same, and the size and distribution of the environmental magnetic field they receive are also approximately the same. Correspondingly, under normal circumstances, the induced signals generated by each detection coil are also approximately the same. Based on this, after the signal acquisition of the coil group A is completed, for each signal value, the data in the arrays A 12 , A 23 , A 34 , and A 41 corresponding to the coil group A can be collected together, and an outlier detection algorithm (such as the interquartile range method) is used to detect outliers in the data (Step S3), and then the outlier detection result is used to determine whether there is a foreign object in the detection area corresponding to the coil group A.

[0177] It can be understood that the outlier detection algorithm can also use other algorithms in addition to the interquartile range method, such as the median method, the mean method, the clustering method, etc. Among them, the interquartile range method is simple and effective, and the following will take this algorithm as an example to explain the outlier detection process of the coil group A.

[0178] Based on the foregoing data acquisition mode, each array corresponding to the coil group A includes 8*k (i.e., 8k) amplitudes (each detection coil in the coil group A acquires 2*k (i.e., 2k) amplitudes for each period) and 4*k (i.e., 4k) phase differences.

[0179] Taking the amplitude as an example, the 8k amplitudes can be arranged in ascending order, and then the number sequence is divided into four equal parts. The value at the division point is the quartile, and then three quartiles can be obtained: the first quartile (Q1), the second quartile (Q2, i.e., the median), and the third quartile (Q3). The interquartile range (IQR) is Q3-Q1.

[0180] According to the IQR, a normal data range can be determined as: [Q1-n*IQR, Q3+n*IQR], and whether there is an abnormal value in the 8k amplitudes can be determined according to the range (step S4). The amplitude falling outside the range is an abnormal value, that is, the abnormal value threshold can include a first threshold (Q1-n*IQR) and a second threshold (Q3+n*IQR), and the signal value less than the first threshold or greater than the second threshold is an abnormal value. Wherein, n can be set according to the sensitivity requirement, for example, it can be 1.5.

[0181] The abnormal value determination process of the phase difference is similar to that of the amplitude, and the abnormal value determination process of other coil groups is similar to that of coil group A, which will not be described here.

[0182] When judging the foreign matter, as an optional implementation, for each coil group, if there is no abnormal value in the induction signal of the coil group, it can be considered that the detection area corresponding to the coil group has no foreign matter; if there is an abnormal value in the induction signal of the coil group, it can be considered that the detection area corresponding to the coil group has a foreign matter.

[0183] Considering the possibility of environmental abnormalities, for example, at the initial stage after starting charging, the charging power will fluctuate, and these situations will affect the magnetic field of the coil array, thereby affecting the induction signals of each detection coil in the coil array. Therefore, in order to improve the accuracy of the detection result, as another optional implementation, for each coil group, if there is an abnormal value in the induction signal of the coil group, the working conditions of other coil groups can be checked, that is, whether there is also an abnormal value in the induction signal of other coil groups (step S5); if there is an abnormal value in the induction signal of all coil groups, it can be considered that there is an environmental abnormality; otherwise, it can be considered that the detection area corresponding to the coil group has a foreign matter. That is, if the induction signals of each coil group all have abnormal values, it can be considered that an environmental abnormality occurs, and the detection area corresponding to the coil array has no foreign matter; if the induction signals of each coil group all have no abnormal values, it can be considered that the detection area corresponding to the coil array has no foreign matter, and no environmental abnormality occurs; if the induction signals of at least one coil group have abnormal values, and the induction signals of at least one coil group have no abnormal values, it can be considered that the detection area corresponding to the coil array has a foreign matter.

[0184] It can be understood that the above foreign matter judgment method is only an example, which is not used to limit the present application, and other methods can also be used in specific implementation, such as combining the proportion of abnormal values to judge the foreign matter, which is not particularly limited in the present embodiment.

[0185] If it is determined that there is no foreign matter in the detection area corresponding to the coil array, the subsequent detection process can be continued. If an environmental anomaly occurs, i.e., there is an abnormal value in the sensing signal of each coil group, the sensing signal in the next first time period can be acquired, and the abnormal value detection is performed based on the sensing signal acquired in the next first time period (step S6). If no environmental anomaly occurs, i.e., there is no abnormal value in the sensing signal of each coil group, the subsequent step of determining the signal threshold of each coil group can be performed (step S8).

[0186] If it is determined that there is foreign matter in the detection area corresponding to the coil array, i.e., there is an abnormal value in the sensing signal of at least one coil group of the coil groups, and there is no abnormal value in the sensing signal of the at least one coil group, an alarm can be given and the charging can be stopped (step S7), and it can be further determined which detection area corresponding to which detection coil has foreign matter according to the detection coil corresponding to the abnormal value, and the position of the foreign matter can be reminded by voice and / or image display when the alarm is given. For example, the abnormal value is the amplitude of the detection coil A1, which indicates that the detection area corresponding to the detection coil A1 has foreign matter. For another example, the abnormal value includes the phase difference of the detection coils A1A2 and A2A3, and the phase differences of A3A4 and A4A1 are normal values, which indicates that the detection area corresponding to the detection coil A2 has foreign matter.

[0187] S130, in the case of determining that there is no foreign matter in the detection area corresponding to the coil array, determining the signal threshold of each coil group according to the sensing signal of each coil group acquired in the first time period.

[0188] Specifically, if the sensing signal of the coil group has no abnormal value, it indicates that the area where the coil group is located has no foreign matter, and at this time, the signal threshold of the coil group can be determined. The following will continue to take the coil group A as an example for description.

[0189] As described above, the signal value of the sensing signal of the coil group A acquired in the first time period includes the amplitude and the phase difference, and for each kind of signal value, the mean value method can be used to determine the signal threshold of the kind of signal value. For example, all the values of the kind of signal value of the coil group A acquired in the first time period can be averaged, and the average value can be taken as the signal threshold of the kind of signal value. Continuing to take the foregoing example as an example, the amplitude threshold of the coil group A is the average value of the 8k amplitudes included in each array corresponding to the coil group A, and the phase difference threshold of the coil group A is the average value of the 4k phase differences included in each array corresponding to the coil group A.

[0190] It can be understood that the above-mentioned signal threshold determination method is only a relatively simple method, and other methods such as weighted average method or median method can also be used to determine the signal threshold in actual application, which is not particularly limited in the present embodiment.

[0191] For other coil groups, the signal threshold value determination manner is similar to that of coil group A, which will not be described here. It can be understood that for each coil group, the signal threshold value can be determined when it is determined that the induced signal of the coil group has no abnormal value, or the signal threshold value can be determined when it is determined that the induced signals of all coil groups have no abnormal value, so that if the induced signals of other coil groups have abnormal values, the determination of the signal threshold value is not needed, thereby saving processing resources.

[0192] S140, for at least one second time period after the first time period, according to the signal threshold value of each coil group, the induced signal of each coil group obtained in the second time period is detected to determine whether there is a foreign object in the detection area corresponding to the coil array.

[0193] After the signal threshold value of each coil group is determined, the foreign object detection can be performed based on the signal threshold value in subsequent detection.

[0194] Similar to the signal acquisition process in the first time period, in the second time period, the induced signals generated by each detection coil can be acquired in parallel, or the detection coils in each coil group can be selected and gated in sequence to acquire the induced signals. For each detection coil, the signal value of the induced signal of the detection coil obtained in the second time period can include multiple values.

[0195] Taking coil group A as an example, in any one of the second time periods, when any one pair of adjacent detection coils is selected and gated, the amplitude and phase difference of k' periods can be obtained, and finally 8k' amplitudes (each detection coil in coil group A obtains 2k' amplitudes) and 4k' phase differences can be obtained. Similar to the first time period, the signal value of each period can be the average of the corresponding multiple sampling values. Wherein, k' can be equal to k, or less than k, so as to improve the detection real-time performance.

[0196] After the data of coil group A is obtained, as an optional implementation manner, each amplitude value obtained can be compared with the amplitude threshold value of coil group A, each phase difference obtained can be compared with the phase difference threshold value of coil group A, whether each amplitude value and phase difference is abnormal is determined, and then whether coil group A is abnormal is determined.

[0197] As another optional implementation manner, the 2k' amplitude values of each detection coil or the amplitudes of k' periods obtained in one selection process can be averaged and compared with the amplitude threshold value of coil group A, the k' phase differences of each pair of adjacent detection coils can be averaged and compared with the phase difference threshold value of coil group A, whether each amplitude average value and phase difference average value is abnormal is determined, and then whether coil group A is abnormal is determined. In this way, the processing efficiency can be improved, and the influence of circuit signal fluctuation on the detection result can be reduced.

[0198] In the specific judgment of whether the average value of each signal value is abnormal, taking the amplitude as an example, for example, it can be judged whether the absolute value of the difference between the amplitude average value and the amplitude threshold value exceeds a preset value (hereinafter referred to as the first preset value). If it exceeds, it is considered that the amplitude average value is abnormal, that is, there is an abnormal value in each amplitude corresponding to the amplitude average value; if it does not exceed, it is considered that the amplitude average value is normal, that is, there is no abnormal value in each amplitude corresponding to the amplitude average value. Wherein, the first preset value can be determined according to the required detection accuracy. The abnormal judgment mode of phase difference is similar to amplitude, which will not be repeated here. It can be understood that other ways can also be used for abnormal judgment, which is not particularly limited in the embodiment.

[0199] If it is determined according to the comparison result that the amplitude average value and the phase difference average value of the coil group A are normal, it can be considered that the coil group A works normally, otherwise, it can be considered that the coil group A works abnormally.

[0200] The abnormal judgment process of other coil groups is similar to that of coil group A, which will not be repeated here.

[0201] Similar to the foreign matter detection process corresponding to the first time period, as an optional implementation manner, for each coil group, if the coil group works normally, it can be considered that the detection area corresponding to the coil group has no foreign matter; if the coil group works abnormally, it can be considered that the detection area corresponding to the coil group has foreign matter.

[0202] Considering that there may be environmental abnormality, for example, parking deviation or charging power change, which will affect the magnetic field where the coil array is located, therefore, in order to improve the accuracy of the detection result, as another optional implementation manner, for each coil group, if the coil group works abnormally, the working conditions of other coil groups can be checked, if all coil groups work abnormally, it can be considered that it is environmental abnormality; otherwise, it can be considered that the detection area corresponding to the coil group has foreign matter. That is, if all coil groups work normally or abnormally, that is, the induced signals of all coil groups have no abnormal value or have abnormal value, it can be considered that the detection area corresponding to the coil array has no foreign matter; if at least one coil group works normally and at least one coil group works abnormally, that is, at least one coil group has abnormal value and at least one coil group has no abnormal value, it can be considered that the detection area corresponding to the coil array has foreign matter.

[0203] Similar to the foreign matter detection process corresponding to the first time period, the above foreign matter judgment mode is only an example, which is not used to limit the application, and other ways can also be used in specific implementation, such as combining the proportion of abnormal value to judge foreign matter, which is not particularly limited in the embodiment.

[0204] If it is determined that the detection area corresponding to the coil array has no foreign matter, the inductive signal of the next second time period can be acquired to continue foreign matter detection; if it is determined that the detection area corresponding to the coil array has foreign matter, an alarm can be given and charging can be stopped, and it can be further determined which detection area corresponding to the detection coil has foreign matter according to the detection coil corresponding to the abnormal value, and the location of the foreign matter can be reminded by voice and / or image display when the alarm is given.

[0205] It can be understood that, in the case of determining that the detection area corresponding to the coil array has no foreign matter based on the first time period, the foreign matter detection method adopted in step S120 can also be continued, in which foreign matter detection is performed based on the signal threshold, the algorithm is simpler, and the case of foreign matter existing in the central position of the coil array can also be effectively detected. Specifically, when foreign matter exists in the central position of the coil array, the influence on the surrounding four detection coils is basically consistent, and the foreign matter detection is not detected by continuing to use the quartile deviation method or other abnormal value detection algorithm; the signal threshold is used for foreign matter detection, and it can be effectively determined that each detection coil of the middle coil group is abnormal, so as to determine that foreign matter exists in the central position of the coil array.

[0206] In addition, when performing foreign matter detection, the amplitude can also be replaced by the amplitude difference, and correspondingly, the amplitude threshold of the coil group in step S130 is replaced by the amplitude difference threshold. Wherein, in the case of environmental abnormality, the amplitude can more effectively determine whether the inductive signal of each detection coil has an abnormal value, so as to improve the accuracy of the foreign matter detection result.

[0207] S150, for any second time period, if it is detected that the detection area corresponding to the coil array has no foreign matter according to the inductive signal of each coil group acquired in the second time period, the signal threshold of each coil group is updated according to the inductive signal of each coil group acquired in the second time period.

[0208] After the signal threshold is determined, the signal threshold can also be updated in the subsequent detection process to further improve the environmental adaptability of foreign matter detection.

[0209] In specific implementation, for each second time period, after foreign matter detection is performed, if it is determined that the detection area corresponding to the coil array has no foreign matter, the signal threshold of each coil group is updated; or only in the case of environmental abnormality, the signal threshold of each coil group is updated, that is, for a certain second time period, if it is determined that the detection area corresponding to the coil array has no foreign matter, and no environmental abnormality occurs, the signal threshold of each coil group does not need to be updated, so as to save processing resources.

[0210] In the specific updating, taking the amplitude threshold of the coil group A as an example, after the foreign matter detection based on the inductive signal obtained in a certain second time period, the amplitudes of the coil group A obtained in the second time period can be averaged or weighted averaged with the amplitude threshold, and the obtained result is taken as the updated amplitude threshold. The updating method of the phase value threshold and the signal threshold of other coil groups is similar to the updating method of the above-mentioned amplitude threshold, which will not be described here. It can be understood that the updating method of the signal threshold is not limited to the above-mentioned method, and the above-mentioned updating method is only an example, which is not used to limit the present application, and the updating method of the signal threshold in the present embodiment is not particularly limited.

[0211] In order to further improve the safety of wireless charging, in the present embodiment, the detection area corresponding to the coil array can also be detected for foreign matter before the transmitting coil transmits electric energy to the receiving coil; in the case that it is determined that the detection area corresponding to the coil array has no foreign matter, the transmitting coil is controlled to transmit electric energy to the receiving coil.

[0212] The foreign matter detection method used before charging can be similar to the foreign matter detection method in the first time period, that is, the interquartile range method or other methods can be used for foreign matter detection, and the specific detection process can be referred to the related description in step S120, and the difference is that the environmental anomaly can not be considered when detecting the foreign matter, that is, for each coil group, if the inductive signal of the coil group has no abnormal value, it can be considered that the detection area corresponding to the coil group has no foreign matter; if the inductive signal of the coil group has an abnormal value, it can be considered that the detection area corresponding to the coil group has foreign matter.

[0213] Considering that before the detection system is started, there can be a situation that a large (area exceeding the coil array coverage area) and symmetrical metal foreign matter such as an aluminum plate already exists in the detection area corresponding to the coil array, which will cause the inductive signals of each detection coil in the same coil group to have the same change amount. Based on this, in the present embodiment, the foreign matter detection circuit can also pre-store a set of signal values of the inductive signals of each coil group in an ideal case (i.e. without starting charging, without environmental foreign matter) (hereinafter referred to as initial value); when detecting the foreign matter before charging, for each coil group, the inductive signal of the coil group can be compared with the corresponding initial value to determine whether the inductive signal of the coil group has an abnormal value, and if the inductive signal of the coil group has no abnormal value, it can be determined that the detection area corresponding to the coil group has no foreign matter.

[0214] Similar to the signal threshold, each signal value of the induction signal of each coil group has a corresponding initial value. In the specific judgment of whether the induction signal of the coil group has an abnormal value, similar to the judgment of whether the induction signal has an abnormal value based on the signal threshold in step S140, taking the amplitude as an example, for a certain coil group, for example, it can be judged whether the absolute value of the difference between the average value of each amplitude of the coil group and the corresponding initial value exceeds a preset value (hereinafter referred to as a second preset value), if it exceeds, it is considered that the amplitude of the coil group has an abnormal value; if it does not exceed, it is considered that the amplitude of the coil group does not have an abnormal value. Wherein, the second preset value can be greater than the first preset value. The abnormality judgment method of the phase difference is similar to the amplitude, which will not be described here.

[0215] If the amplitude and the phase difference of the coil group do not have abnormal values, it can be determined that the detection area corresponding to the coil group has no foreign matter; otherwise, it can be considered that the detection area corresponding to the coil group has foreign matter.

[0216] It can be understood that other ways can also be used to judge whether the induction signal of the coil group is normal, and the present embodiment does not particularly limit this.

[0217] Those skilled in the art can understand that the above embodiments are exemplary and are not used to limit the present application. In possible cases, the execution order of one or several steps in the above steps can be adjusted, and selective combination can also be performed to obtain one or more other embodiments. Those skilled in the art can select and combine any of the above steps as needed, and any deviation from the scheme of the present application does not fall within the protection scope of the present application.

[0218] The foreign matter detection method provided in the embodiment sets a foreign matter detection device in the wireless charging system, obtains the induction signals generated by each detection coil after starting charging; then determines the abnormal value threshold of each coil group according to the induction signal of each coil group obtained in a first time period, the first time period being a preset time period after starting to obtain the induction signal; and then detects whether there is foreign matter in the detection area corresponding to the coil array according to the abnormal value threshold of each coil group and the induction signal, so that the foreign matter can be timely removed in the case of detecting the foreign matter, thereby improving the safety and charging efficiency of wireless charging.

[0219] Moreover, the technical scheme dynamically determines the abnormal value threshold based on the obtained induction signal, and detects foreign matter according to the abnormal value threshold, so that the inherent error (such as error caused by interference factors such as power adjustment, concrete layer, protective shell, etc.) can be fused into the abnormal value threshold, thereby improving the anti-interference ability and environmental adaptability of foreign matter detection.

[0220] In addition, the technical solution utilizes the symmetry of the detection coil to detect foreign matter in units of coil groups, so that the algorithm complexity can be reduced.

[0221] In addition, the technical solution provided in the embodiment can provide an alternating excitation signal to each detection coil, that is, the detection is of the type with an excitation source, so that the strength of the induction signal of each detection coil mainly comes from the excitation source, thereby reducing the influence of the environmental magnetic field on the detection accuracy, and further improving the accuracy of foreign matter detection.

[0222] In addition, the technical solution determines the signal threshold based on the induction signal obtained in the first time period in the case where there is no foreign matter, and then performs foreign matter detection based on the signal threshold, so that the processing speed can be improved.

[0223] The foreign matter detection method provided in the embodiment can update the signal threshold in the subsequent detection process after the signal threshold is determined, so that the environmental adaptability of foreign matter detection can be further improved.

[0224] The embodiment of the application also provides a foreign matter detection device, please refer to Figure 11 , Figure 11 The structure schematic diagram of the foreign matter detection device provided in the embodiment of the application.

[0225] As shown in Figure 11 , the foreign matter detection device can include a coil array 110, a processor 120, a memory 130, a communication module 140, an audio module 150, and a display screen 160.

[0226] It can be understood that the structure illustrated in the embodiment of the application does not constitute a specific limitation on the foreign matter detection device. In other embodiments of the application, the foreign matter detection device can include more or fewer components than the illustration, or combine certain components, or split certain components, or different component arrangements. The illustrated components can be implemented in hardware, software, or a combination of software and hardware.

[0227] The structure of the coil array 110 can be referred to the related description in the foregoing embodiments, which will not be described here again.

[0228] The processor 120 can be a central processing unit (CPU), and can also be other general-purpose processors 120, digital signal processors 120 (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, etc. The general-purpose processor 120 can be a microprocessor or the processor 120 can also be any conventional processor 120, etc. The aforementioned circuit modules of the foreign matter detection circuit can be partially or entirely integrated in the processor 120.

[0229] The memory 130 is configured to store instructions and data (e.g., the sensing signals collected by the signal collection unit), and can include a non-transitory memory in a computer readable medium, random access memory (RAM), and / or non-volatile memory, etc., such as read-only memory (ROM) or flash memory (flash RAM).

[0230] The memory 130 can include volatile memory and / or non-volatile memory, wherein the non-volatile memory can be read-only memory (ROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electrically EPROM (EEPROM), or flash memory. The volatile memory can be random access memory (RAM) used as external cache. By way of example, and not limitation, a variety of forms of RAM can be used, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), double data rate SDRAM (DDR SDRAM), etc.

[0231] The foreign matter detection device can communicate with the power transmitting device, the power receiving device and / or other devices through the communication module 140. The communication module 140 can provide a wireless communication solution applied to the foreign matter detection device, including wireless local area networks (WLAN) (such as a wireless fidelity (Wi-Fi) network), Bluetooth (BT), a global navigation satellite system (GNSS), frequency modulation (FM), near field communication technology (NFC), infrared technology (IR), and the like.

[0232] The audio module 150 can provide a sound signal. The foreign matter detection device can perform the voice mode alarm in the above method embodiments through the audio module 150.

[0233] The display screen 160 is used to display images, videos, and the like. For example, the foreign matter detection device can display the position of the foreign matter on the coil array through the display screen 160.

[0234] The display screen 160 includes a display panel. The display panel can be a liquid crystal display (LCD), an organic light-emitting diode (OLED), an active-matrix organic light-emitting diode (AMOLED), a flexible light-emitting diode (FLED), a Mini LED, a Micro LED, a quantum dot light emitting diode (QLED), and the like.

[0235] The foreign matter detection device provided in the embodiment can execute the above method embodiments, and the implementation principles and technical effects are similar, which will not be described here.

[0236] The embodiment of the present application also provides a computer readable storage medium, which stores a computer program. When the computer program is executed by a processor, the method described in the above method embodiments is implemented.

[0237] The embodiment of the present application further provides a computer program product, which, when running on an electronic device, causes the electronic device to perform the method described in the above method embodiment.

[0238] The embodiment of the present application further provides a chip system, which comprises a processor coupled with a memory, and the processor executes a computer program stored in the memory to implement the method described in the above method embodiment. The chip system can be a single chip or a chip module composed of multiple chips.

[0239] In the above embodiment, all or part of the method can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the method can be implemented in the form of a computer program product. The computer program product comprises one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiment of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The computer instructions can be stored in a computer readable storage medium or transmitted by the computer readable storage medium. The computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wire (such as coaxial cable, optical fiber, digital subscriber line) or wireless (such as infrared, wireless, microwave, etc.). The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available media can be magnetic media (such as floppy disk, hard disk or magnetic tape), optical media (such as DVD) or semiconductor media (such as solid state disk (SSD)) and the like.

[0240] Those of ordinary skill in the art can understand that all or part of the processes in the above method embodiments can be implemented by a computer program to instruct the relevant hardware, which can be stored in a computer readable storage medium. The program can include the processes of the above method embodiments when executed.

[0241] In the present application, the naming or numbering of the steps does not mean that the steps in the method process must be executed in the time / logical order indicated by the naming or numbering. The execution order of the named or numbered process steps can be changed according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved.

[0242] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in a certain embodiment can be referred to the relevant description of other embodiments.

[0243] In the embodiments provided in the present application, it should be understood that the disclosed apparatuses / devices and methods can be implemented in other ways. For example, the above-described apparatus / device embodiments are merely schematic, and the division of the modules or units is merely a logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0244] It should be understood that, in the description of the present application and the appended claims, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device containing a series of steps or modules does not have to be limited to those steps or modules clearly listed, but can include other steps or modules not clearly listed or inherent to these processes, methods, products or devices.

[0245] In the description of the present application, unless otherwise specified, " / " represents that the associated objects before and after are in an "or" relationship, for example, A / B can represent A or B; "and / or" in the present application is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent: A alone, A and B together, and B alone, where A and B can be singular or plural.

[0246] In addition, in the description of the present application, unless otherwise specified, "multiple" means two or more than two. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0247] As used in the specification and in the appended claims, the term "if' can be interpreted as meaning "when" or "upon" or "in response to determining" or "in response to detecting" depending on the context. Similarly, the phrase "if it is determined" or "if [the described condition or event] is detected" can be interpreted to mean "upon determining" or "in response to determining" or "upon detecting [the described condition or event]" or "in response to detecting [the described condition or event]" depending on the context.

[0248] In addition, the description in the specification and the appended claims of this application uses the terms "first," "second," "third," and the like to distinguish between similar objects, rather than to describe a particular sequential or chronological order. It is understood that such terms are used in the description and claims of this application to distinguish between similar objects, rather than to describe a particular sequential or chronological order, unless otherwise expressly specified in the description of claims.

[0249] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" or "in other embodiments" or "in still other embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment, unless otherwise expressly specified.

[0250] Finally, it should be noted that the above-described embodiments are merely intended for describing and illustrating the technical solutions of the present application, but are not intended to limit the present application; even though the present application has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that they can still make modifications to the technical solutions recorded in the above-described embodiments, or make equivalent replacements to some or all of the technical features thereof; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A foreign object detection method applied to a foreign object detection circuit in a foreign object detection device applied to a wireless charging system, the method comprising: The foreign matter detection device further comprises a coil array, the coil array comprising at least one coil group, each coil group comprising four detection coils wound in a rectangle, the detection coils in the coil array being arranged in a matrix with an even number of rows and columns in a radial direction, four detection coils in the coil array that are symmetrical to each other in position being in the same coil group, and each detection coil being electrically connected to the foreign matter detection circuit; ​ The method comprises: obtaining an induced signal generated by each detection coil in each coil group; determining an outlier threshold value of each coil group according to the induced signal of each coil group obtained within a first time period, the first time period being a preset time period after the induced signal is obtained; the outlier threshold value being dynamically determined according to the obtained induced signal, and the outlier threshold value of each coil group being determined by using the interquartile range method based on the signal value of the induced signal of the coil group obtained within the first time period; detecting whether there is foreign matter in the detection area corresponding to the coil array according to the outlier threshold value and the induced signal of each coil group; wherein for each detection coil in each coil group, the signal value of the obtained induced signal of the detection coil is compared with the corresponding outlier threshold value to determine whether the induced signal of the detection coil is abnormal, and then to determine whether there is foreign matter in the detection area corresponding to the detection coil.

2. The method of claim 1, wherein, The coil group comprises a plurality of groups, and the detection of whether there is foreign matter in the detection area corresponding to the coil array according to the outlier threshold value and the induced signal of each coil group comprises: for each coil group, determining whether there is an outlier value in the induced signal of the coil group according to the outlier threshold value of the coil group; if there is an outlier value in the induced signal of each coil group or there is no outlier value in the induced signal of each coil group, it is determined that there is no foreign matter in the detection area corresponding to the coil array; if there is an outlier value in the induced signal of at least one coil group among the coil groups and there is no outlier value in the induced signal of at least one coil group, it is determined that there is foreign matter in the detection area corresponding to the coil array.

3. The method of claim 2, wherein, The outlier threshold value comprises a first threshold value and a second threshold value greater than the first threshold value, and the determination of whether there is an outlier value in the induced signal of the coil group according to the outlier threshold value of the coil group comprises: determining whether there is a signal value less than the first threshold value or greater than the second threshold value in the induced signal of the coil group; if there is a signal value less than the first threshold value or greater than the second threshold value in the induced signal of the coil group, it is determined that there is an outlier value in the induced signal of the coil group; if there is no signal value less than the first threshold value or greater than the second threshold value in the induced signal of the coil group, it is determined that there is no outlier value in the induced signal of the coil group.

4. The method of claim 1, wherein, The method further comprises: if there is no foreign matter in the detection area corresponding to the coil array, for each coil group, determining a signal threshold value of the coil group according to the induced signal of the coil group obtained within the first time period. For at least one second time period after the first time period, it is detected whether there is a foreign object in the detection area corresponding to the coil array according to the signal threshold of each coil group and the induced signal of each coil group acquired in the second time period.

5. The method of claim 4, wherein, The method further comprises: If it is determined that there is no foreign object in the detection area corresponding to the coil array in the second time period, the signal threshold of each coil group is determined according to the induced signal of each coil group acquired in the second time period.

6. The method of claim 4, wherein, If there is no foreign object in the detection area corresponding to the coil array and there is no abnormal value in the induced signal of each coil group, the signal threshold of each coil group is determined according to the induced signal of each coil group acquired in the first time period.

7. The method of claim 4, wherein, The signal value of the induced signal of the coil group acquired includes multiple types, and each signal value has a corresponding signal threshold.

8. The method of claim 7, wherein, The signal value of the induced signal of the coil group acquired includes the amplitude of each detection coil in the coil group and the phase difference between each detection coil in the coil group; the signal threshold of the coil group includes an amplitude threshold and a phase difference threshold.

9. The method of claim 4, wherein, The determination of the signal threshold of the coil group according to the induced signal of the coil group acquired in the first time period comprises: According to the induced signal of the coil group acquired in the first time period, the signal threshold of the coil group is determined by using the mean value method.

10. The method of claim 4, wherein, The coil group includes multiple groups, and the detection of whether there is a foreign object in the detection area corresponding to the coil array according to the signal threshold of each coil group and the induced signal of each coil group acquired in the second time period comprises: For each coil group, it is determined whether there is an abnormal value in the induced signal of the coil group according to the signal threshold of the coil group and the induced signal of the coil group acquired in the second time period; If there is no abnormal value in the induced signal of each coil group or there is an abnormal value in the induced signal of each coil group, it is determined that there is no foreign object in the detection area corresponding to the coil array; If there is an abnormal value in the induced signal of at least one coil group in each coil group and there is no abnormal value in the induced signal of at least one coil group, it is determined that there is a foreign object in the detection area corresponding to the coil array.

11. The method of claim 10, wherein, The determination of whether there is an abnormal value in the induced signal of the coil group according to the signal threshold of the coil group and the induced signal of the coil group acquired in the second time period comprises: For each detection coil in the coil group, it is determined that the absolute value of the difference between the average value of the signal value of the induced signal of the detection coil acquired in the second time period and the signal threshold of the coil group; If the absolute value corresponding to each detection coil in the coil group is less than or equal to a preset value, it is determined that there is no abnormal value in the induced signal of the coil group; If the absolute value corresponding to at least one detection coil in the coil group is greater than the preset value, it is determined that there is an abnormal value in the induced signal of the coil group.

12. The method of claim 1, wherein, After the wireless charging system starts to transmit electric energy, the method further comprises: Outputting an alternating excitation signal to each detection coil.

13. The method of claim 12, wherein, The AC excitation signal is sequentially output to each of the coil groups and / or sequentially output to each of the detection coils in each of the coil groups.

14. The method according to any one of claims 1 to 13, characterized in that, The method further comprises: Before the wireless charging system starts transmitting power, detecting whether there is a foreign object in a detection area corresponding to the coil array; In a case where it is determined that there is no foreign object in the detection area corresponding to the coil array, controlling the wireless charging system to start transmitting power.

15. A foreign object detection device applied to a wireless charging system, comprising: The foreign object detection device comprises a coil array and a foreign object detection circuit. The coil array comprises at least one coil group, each of the coil groups comprises four detection coils wound in a rectangular shape, the detection coils in the coil array are arranged in a matrix with an even number of rows and columns in a radial direction, four of the detection coils in the coil array that are symmetrically located are located in the same coil group, and each of the detection coils is electrically connected to the foreign object detection circuit. The foreign object detection circuit is configured to perform the method according to any one of claims 1-14.

16. The apparatus of claim 15, wherein, The coil groups comprise a plurality of groups.

17. The apparatus of claim 15, wherein, The foreign object detection circuit comprises an excitation source configured to provide an AC excitation signal to the detection coils, and the detection coils are connected to the excitation source one by one.

18. The apparatus of any of claims 15-17, wherein, The turn-to-turn spacing of the detection coils gradually increases along a direction from the outside to the center.

19. A wireless charging system, comprising: Comprise: A power transmitting device and a foreign object detection device; The foreign object detection device comprises a coil array and a foreign object detection circuit. The coil array comprises at least one coil group, each of the coil groups comprises four detection coils wound in a rectangular shape, the detection coils in the coil array are arranged in a matrix with an even number of rows and columns in a radial direction, four of the detection coils in the coil array that are symmetrically located are located in the same coil group, and each of the detection coils is electrically connected to the foreign object detection circuit. The foreign object detection circuit comprises a signal acquisition unit and a signal processing unit, and the signal processing unit is electrically connected to the signal acquisition unit. The signal acquisition unit is configured to acquire an induced signal generated by each of the detection coils in each of the coil groups under the control of the signal processing unit. The signal processing unit is configured to determine an abnormal value threshold of each of the coil groups according to the induced signals of each of the coil groups acquired within a first time period, and detect whether there is a foreign object in a detection area corresponding to the coil array according to the abnormal value threshold and the induced signals of each of the coil groups, the first time period being a preset time period after the induced signals are acquired; wherein the abnormal value threshold is dynamically determined according to the acquired induced signals, and the abnormal value threshold of each coil group is determined based on the signal values of the induced signals of the coil group acquired within the first time period using the interquartile range method; for each detection coil in each coil group, the signal value of the acquired induced signal of the detection coil is compared with the corresponding abnormal value threshold to determine whether the induced signal of the detection coil is abnormal, and further determine whether there is a foreign object in the detection area corresponding to the detection coil.

20. The wireless charging system of claim 19, wherein, The foreign matter detection circuit further comprises an excitation source electrically connected with the signal processing unit, and the excitation source is configured to output an alternating excitation signal to the detection coil in each coil group under the control of the signal processing unit.

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