WO2021017500A1 - 无线充电***的异物检测装置、方法及无线充电*** - Google Patents

无线充电***的异物检测装置、方法及无线充电*** Download PDF

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Publication number
WO2021017500A1
WO2021017500A1 PCT/CN2020/081273 CN2020081273W WO2021017500A1 WO 2021017500 A1 WO2021017500 A1 WO 2021017500A1 CN 2020081273 W CN2020081273 W CN 2020081273W WO 2021017500 A1 WO2021017500 A1 WO 2021017500A1
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Prior art keywords
group
detection
coils
detection coils
coil
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PCT/CN2020/081273
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English (en)
French (fr)
Inventor
何谋
陈为
朱勇发
冯绍杰
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华为技术有限公司
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Priority to MX2021004450A priority Critical patent/MX2021004450A/es
Priority to EP20845552.7A priority patent/EP3820022B1/en
Publication of WO2021017500A1 publication Critical patent/WO2021017500A1/zh
Priority to US17/209,484 priority patent/US11329521B2/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/10—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles characterised by the energy transfer between the charging station and the vehicle
    • B60L53/12—Inductive energy transfer
    • B60L53/124—Detection or removal of foreign bodies
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/60—Circuit arrangements or systems for wireless supply or distribution of electric power responsive to the presence of foreign objects, e.g. detection of living beings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/14—Plug-in electric vehicles

Definitions

  • This application relates to the field of wireless charging technology, and in particular to a wireless charging foreign body detection device, method and system.
  • the induced voltage method is used for foreign object detection.
  • the principle of the induced voltage method is to place the detection coil in a high-frequency magnetic field, and determine whether the magnetic field is distorted by judging whether the induced voltage of the detection coil is abnormal, and then whether there is a foreign body.
  • the detection accuracy can be adjusted by adjusting the size of the detection coil, and it is also suitable for small foreign objects.
  • the induced voltage method has two shortcomings that are difficult to overcome. First, to ensure the detection accuracy, the magnetic flux passing through the corresponding detection coil needs to be equal, so the detection coil needs to be processed, and the detection system is more complicated; the second is the detection coil has a detection blind zone.
  • the current effective blind spot elimination method is to lay multiple layers of misplaced detection coils, but this will significantly increase the cost of the detection system.
  • the present application discloses a wireless charging foreign body detection device and method, based on the principle of the induced voltage method, to solve the complicated structure of the foreign body detection device in the prior art and avoid the disadvantage of high cost when detecting blind areas.
  • the first aspect of the present application provides a foreign object detection device for a wireless charging system.
  • the detection device includes an excitation coil, a detection coil, and a processor, wherein:
  • the excitation coil is used to provide a time-varying magnetic field
  • the detection coil is used to detect whether there is a foreign object between the wireless charging transmitting device and the receiving device;
  • the detection coil includes a first group of detection coils and a second group of detection coils.
  • the orthographic projection of each of the first group of detection coils, the second group of detection coils, and the excitation coil is a planar coil, and each The orthographic projections of are located in the same plane and are isolated from each other, wherein the second group of detection coils are located between the first group of detection coils and the excitation coils, and the first group of detection coils are located in the second group Inside the detection coil, the excitation coil is located outside the second group of detection coils;
  • the processor is configured to determine whether the value of the induced voltage generated by the first group of detection coils in the time-varying magnetic field and the value of the induced voltage generated by the second group of detection coils in the time-varying magnetic field are equal, and the result is not If they are equal, it is determined that there is a foreign body.
  • the magnetic field distribution is substantially uniform within the target area of the time-varying magnetic field, wherein the target area of the time-varying magnetic field refers to the The first group of detection coils and the second group of detection coils are located in the area of the time-varying magnetic field.
  • the first group of detection coils and the second group of detection coils satisfy the following formula:
  • N1 is the number of coil turns of the first set of detection coil
  • N2 is the second set of coil turns of the detection coil
  • ⁇ 2 Is the magnetic flux passing through the single-turn coil in the second group of detection coils
  • t is time
  • d ⁇ 1 is determined according to the magnetic induction intensity of the time-varying magnetic field and the coil area of the first group of detection coils
  • d ⁇ 2 is based on The magnetic induction intensity of the time-varying magnetic field and the coil area of the second group of detection coils are determined.
  • the first group of detection coils and the second group of detection coils satisfy The following formula:
  • N1 is the number of coil turns in the first group of detection coils
  • N2 is the number of coil turns of the second group of detection coils
  • S1 is the coil area of the first group of detection coils
  • S2 is the second group of detection coils.
  • B is the magnetic induction intensity
  • t is the time
  • Is the rate of change of magnetic induction intensity over time.
  • the number of turns of the first set of detection coils is the same as that of the first set of
  • the product of the area enclosed by the detecting coils is equal to the product of the number of turns of the second group of detecting coils and the area enclosed by the second group of detecting coils.
  • the detection coils of the first group and the second group of detection coils The number of turns is different, wherein the number of turns of the first group of detection coils and the second group of detection coils is different because the area enclosed by the first group of detection coils and the second group of detection coils is different .
  • the first group of detection coils and the second group of detection coils are both It is a planar coil, and the first group of detection coils and the second group of detection coils are located in the same plane.
  • the first group of detection coils and the second group of detection coils are both A multi-turn coil is included, and the multi-turn coils of each group of the detection coils are coaxial.
  • the foreign object detection device of the wireless charging system may further include an alarm, so The alarm is used for alarming when the processor determines that there is a foreign object.
  • a second aspect of the present application provides a foreign object detection device for a wireless charging system, the detection device including an excitation coil, a detection coil, and a processor, wherein:
  • the excitation coil is used to provide a time-varying magnetic field
  • the detection coil is used to detect whether there is a foreign object between the wireless charging transmitting device and the receiving device;
  • the detection coil includes at least three groups of detection coils, the orthographic projection of each of the at least three groups of detection coils is a plane coil, the orthographic projection of the excitation coil is also a plane coil, and the at least The orthographic projection of each of the three groups of detection coils and the orthographic projection of the excitation coils are located in the same plane and are isolated from each other;
  • Each of the at least three groups of detection coils forms a coil pair, and each coil pair is used to eliminate detection blind areas;
  • the processor is used to determine whether the induced voltage values generated by the two sets of coils of each coil pair in the time-varying magnetic field are equal, and if the results are not equal, it is determined that there is a foreign body.
  • the magnetic field distribution is substantially uniform in the target area of the time-varying magnetic field, wherein the target area of the time-varying magnetic field refers to all The at least three sets of detection coils are located in the area of the time-varying magnetic field.
  • the area enclosed by one of the detection coils in each coil pair The product of the number of turns of one group of detection coils is equal to the product of the area enclosed by the other group of detection coils and the number of turns of the other group of detection coils.
  • the at least three sets of detection coils are all planar coils, and the at least The three groups of detection coils are located in the same plane.
  • the at least three sets of detection coils include multi-turn coils, each The multi-turn coils of the group of the detection coils are coaxial.
  • the foreign object detection device of the wireless charging system may further include an alarm, so The alarm is used for alarming when the processor determines that there is a foreign object.
  • the third aspect of the present application provides a wireless charging foreign body detection method, including:
  • the processor collects the voltage induced by the first group of detection coils in the time-varying magnetic field generated by the excitation coil and the voltage induced by the second group of detection coils in the time-varying magnetic field generated by the excitation coil;
  • the processor judges whether the voltage induced by the first group of detection coils in the time-varying magnetic field and the value of the induced voltage produced by the second group of detection coils in the time-varying magnetic field are equal, and if they are not equal, judge that there is a foreign object;
  • the processor sends out different signals according to different detection results.
  • the third aspect in the first possible implementation manner of the third aspect, it further includes:
  • the processor determines that there is a foreign object, it alarms, or a switch that controls the operation of the wireless charging system, and shuts off the normal operation of the wireless charging system when the processor determines that there is a foreign object.
  • the fourth aspect of the present application provides a wireless charging foreign body detection method, including:
  • the processor collects the voltage induced by at least three groups of detection coils in the time-varying magnetic field generated by the excitation coil, wherein: any two groups of detection coils in the at least three groups of detection coils form a coil pair;
  • the processor determines whether the induced voltage values generated by the two sets of coils of any coil pair in the time-varying magnetic field are equal, and if they are not equal, it determines that there is a foreign body;
  • the processor sends out different signals according to the detection result.
  • the fourth aspect in the first possible implementation manner of the fourth aspect, it further includes:
  • the processor determines that there is a foreign object, it alarms, or a switch that controls the operation of the wireless charging system, and shuts off the normal operation of the wireless charging system when the processor determines that there is a foreign object.
  • a fifth aspect of the present application provides a wireless charging foreign body detection system.
  • the wireless charging foreign body detection system includes the wireless charging foreign body detection device and the charging system described in the first and second aspects.
  • the wireless charging foreign body detection device It is used to detect whether there are foreign objects in the charging system.
  • Using the foreign body detection device described in the present application has the advantage that a simple coil structure can be used to achieve foreign body detection without detection blind spots, which solves the complicated structure of the foreign body detection device in the prior art and the high cost when solving the detection blind zone problem Disadvantages.
  • FIG. 1 is a schematic structural diagram of a wireless charging system provided by an embodiment of the application
  • FIG. 2 is a schematic diagram of a foreign body detection device including two sets of detection coils provided by an embodiment of the application;
  • FIG. 3 is a schematic diagram of a detection unit including two sets of detection coils according to an embodiment of the application;
  • FIG. 4 is a schematic diagram of the steps of a foreign body detection method provided by an embodiment of the application.
  • FIG. 5 is a schematic diagram of a detection blind area provided by an embodiment of the application.
  • FIG. 6 is a schematic diagram of a foreign object detection device including three sets of detection coils according to an embodiment of the application;
  • FIG. 7 is a schematic diagram of a detection unit including three sets of detection coils according to an embodiment of the application.
  • FIG. 8 is a schematic diagram of the steps of another foreign body detection method provided by an embodiment of the application.
  • FIG. 9 is a schematic structural diagram of a detection device with detection coils connected in series according to an embodiment of the application.
  • Wireless charging also known as Wireless Power Transfer (WPT)
  • WPT Wireless Power Transfer
  • the wireless charging technology of consumer electronic products for example, in the application of smart terminals, electric toothbrushes and other products It is already relatively mature.
  • the field of electric vehicles is also vigorously developing wireless charging technology.
  • the wireless charging foreign body detection technology mainly includes the power difference method and the induced voltage method.
  • the principle of the power difference method is that when a foreign object invades the wireless charging area, the foreign object induces eddy currents in the high-frequency magnetic field and causes loss.
  • the total power transmitted by the wireless charging system remains unchanged, and the increase in metal eddy current loss reduces the received power of the receiving coil, resulting in a decrease in transmission efficiency.
  • the power difference comparison method judges whether there is a foreign body by comparing the difference between the receiving power of the receiving coil and the transmitting power of the transmitting coil.
  • the power difference comparison method is suitable for large foreign body eddy current loss. If the foreign body eddy current loss is negligible compared to the transmission power of the system, the method is difficult to take effect, and a small-volume foreign body cannot be detected.
  • the principle of the induced voltage method is to place the detection coil in a high-frequency magnetic field, and determine whether the magnetic field is distorted by judging whether the induced voltage of the detection coil is abnormal, and then whether there is a foreign body.
  • the detection accuracy can be adjusted by adjusting the size of the detection coil, and it is also suitable for small foreign objects.
  • the induced voltage method has two shortcomings that are difficult to overcome. First, to ensure the detection accuracy, the magnetic flux passing through the corresponding detection coil needs to be equal, so the detection coil needs to be processed, and the detection system is more complicated; the second is the detection coil has a detection blind zone.
  • the current effective blind spot elimination method is to lay multiple layers of misplaced detection coils, but this will significantly increase the cost of the detection system.
  • the embodiments of the present application propose a wireless charging foreign object detection device, method, and system to solve the problems existing in the detection of foreign objects by the induced voltage method in the prior art.
  • FIG. 1 shows a schematic structural diagram of a wireless charging system.
  • the wireless charging and charging system includes a transmitting terminal 101 and a receiving terminal 102.
  • the transmitting terminal 101 is connected to the transmitting coil 103, and the receiving terminal 102 is connected to the receiving coil.
  • 104 is connected.
  • the transmitting terminal 101 is used to provide power to the receiving terminal 102 or to charge the receiving terminal 102.
  • the transmitting coil 103 provides an alternating current, so that the transmitting coil 103 generates a time-varying magnetic field.
  • the receiving coil 104 generates electromagnetic induction in the time-varying magnetic field generated by the transmitting coil 103, so that an induced current is formed in the receiving coil 104.
  • the eddy current effect of the foreign body in the magnetic field formed by the transmitting coil causes the transmission efficiency of the wireless charging system to decrease.
  • the first embodiment of the present application provides a foreign object detection device.
  • FIG. 2 it is a schematic structural diagram of the foreign object detection device provided by this embodiment of the application.
  • the foreign object detection device includes a first group of detection coils 201, a second group of detection coils 202, an excitation coil 203 and a processor 204.
  • the first group of detection coils 201, the second group of detection coils 202, and the excitation coil 203 together form a detection unit.
  • the detection unit includes a first group of detection coils 201 and a second group of detection coils 202. ⁇ Excitation coil 203.
  • the respective front projections of the first group of detection coils 201, the second group of detection coils 202, and the excitation coils 203 are all a planar coil, and their respective front projections are in the same plane.
  • the first group of detection coils 201, the second group of detection coils 202, and the excitation coils 203 are located in the same plane.
  • the first group of detection coils 201, the second group of detection coils 202, and the excitation coil 203 are not located in the same plane, or in other words, the first group of detection coils 201, the second group of detection coils 202 The distance between at least one coil of the excitation coil 203 and the other coils relative to the projection plane is not equal.
  • the first group of detection coils 201 and the second group of detection coils 202 are both planar coils, and the first group of detection coils and the second group of detection coils are located in the same plane. Both the first group of detection coils and the second group of detection coils include multi-turn coils, and the multi-turn coils of each group of the detection coils are coaxial.
  • the shape of the coil can be rectangular, circular or polygonal, which is not limited in the embodiment of the present application.
  • the first group of detection coils 201 are located inside the second group of detection coils 202, and the first group of detection coils 201 and the second group of detection coils 202 are both located inside the excitation coil 203.
  • the second group of detection coils 202 is located between the first group of detection coils 201 and the excitation coil 203, wherein the first group of detection coils 201 is located inside the second group of detection coils 202, and the excitation coil 203 is located at the end of the second group of detection coils 202.
  • the first group of detection coils 201 are completely surrounded by the second group of detection coils 202, and the first group of detection coils 201 and the second group of detection coils 202 are completely surrounded by the excitation coil 203.
  • the inner first group of detection coils 201 and the outer second group of detection coils 202 are separated from each other, and the outer second group of detection coils 202 and the excitation coil 203 are separated from each other.
  • the excitation coil 203 is connected to a sinusoidal excitation input current for providing a time-varying magnetic field, which is substantially uniform for the first group of detection coils 201 and the second group of detection coils 202.
  • the substantially uniformity should be subject to the understanding of those skilled in the art, for example, it fluctuates by 5%.
  • the excitation coil used to generate the time-varying magnetic field serves as a magnetic field excitation source for the independently set detection coil, wherein the detection coil includes a first group of detection coils and a second group of detection coils.
  • This independently arranged magnetic field excitation source can eliminate system interference in the wireless charging system, and further ensure that the detection coil can accurately detect foreign objects.
  • the excitation coil 203 may also be a transmitting coil in the wireless charging system, which can further save costs, so that the detection coil can be applied to a variety of wireless charging systems to detect foreign objects conveniently and quickly.
  • the first group of detection coils 201 and the second group of detection coils 202 are used to detect whether there is a foreign object between the wireless charging transmitter and the receiving device.
  • the excitation coil uses a 6.78MHz high-frequency sinusoidal current, which is staggered with the 85kHz frequency of the wireless charging system, which is convenient for the processor to filter.
  • the first group of detection coils 201 and the second group of detection coils 202 satisfy the following formula:
  • N1 is the number of coil turns of the first set of detection coil 201
  • N2 is the second set of detection coil turns 202
  • ⁇ 2 is the magnetic flux passing through the single-turn coil in the second group of detection coil 202
  • t is the time
  • d ⁇ 1 is based on the magnetic induction intensity of the time-varying magnetic field and the enclosing of any coil in the first group of detection coils 201
  • the area of the region is determined
  • d ⁇ 2 is determined based on the magnetic induction intensity of the time-varying magnetic field and the area of the region enclosed by any coil in the second group of detection coils 202.
  • the first group of detection coils 201 and the second group of detection coils 202 are placed in a uniform time-varying magnetic field at the plane where the two coils are located. From the principle of Faraday electromagnetic induction, the high-frequency time-varying magnetic field will induce an electromotive force E in a closed loop. :
  • the coils with different winding directions will induce different electromotive forces in positive and negative directions. Since the high-frequency magnetic field generated by the excitation coil has approximately uniform magnetic induction intensity B in the two detection coils, at a certain frequency, the magnetic induction intensity B in the two detection coils changes with time approximately the same, so the magnitude of the induced electromotive force E It only depends on the area S that the time-varying magnetic field passes through the closed loop and the number of turns N of the closed loop coil.
  • the induced electromotive force of each group of detection coils is related to the number of turns of the group of detection coils and the rate of change of magnetic flux of any coil in the group of detection coils.
  • the induced electromotive force of the first group of detection coils is related to the number of turns of the first group of detection coils and the rate of change of magnetic flux of each turn of the first group of detection coils.
  • the magnetic flux of each coil is related to the magnetic induction intensity of the time-varying magnetic field and the area of the region enclosed by the coil.
  • the magnetic flux of the first-turn coil is related to the magnetic induction intensity of the time-varying magnetic field and the area of the area enclosed by the first-turn coil.
  • the first group of detection coils and the second group of detection coils have different turns and different areas.
  • the induced electromotive force direction of the two coils can be the same or opposite.
  • the first group of detection coils 201 with a small area has more turns
  • the second group of detection coils 202 with a larger area has less turns
  • the induced electromotive force generated by the first group of detection coils 201 in the time-varying magnetic field and the induced electromotive force generated by the second group of detection coils 202 in the time-varying magnetic field can be made equal in magnitude.
  • N1 is the number of coil turns in the first group of detection coils
  • N2 is the number of coil turns in the second group of detection coils
  • S1 is the area enclosed by any coil in the first group of detection coils
  • S2 is the area enclosed by any coil in the second set of detection coils
  • B is the magnetic induction intensity
  • t is time
  • Is the rate of change of magnetic induction intensity over time. Since the high-frequency magnetic field generated by the excitation coil has approximately uniform magnetic induction in the first group of detection coils and the second group of detection coils, under the same frequency AC excitation, the magnetic induction in the first group of detection coils and the second group of detection coils Change over time Approximately the same. That is, the product of the number of turns and the area of the first group of detection coils is equal to the product of the number of turns and the area of the second group of detection coils.
  • the first group of detection coils 201 and the second group of detection coils 202 have the same winding direction, and the induced electromotive force generated in the time-varying magnetic field is of the same magnitude and the same direction; in another possible implementation In the manner, the first group of detection coils 201 and the second group of detection coils 202 have opposite winding directions, and the induced electromotive force generated in the time-varying magnetic field is equal in magnitude and opposite in direction.
  • the presence of foreign objects will distort the induced magnetic field.
  • metal foreign objects will also be induced to induce electromotive force in a time-varying magnetic field.
  • This electromotive force will generate a closed loop current in the metal foreign object, that is, eddy currents.
  • Eddy currents can generate magnetic fields.
  • the direction of the magnetic field is opposite to the original time-varying magnetic field, which is called the eddy current diamagnetic field.
  • Biological foreign objects can also distort the time-varying magnetic field.
  • the eddy current diamagnetic field generated by the metal foreign body will generate induced electromotive force on the first group of detection coils and the second group of detection coils.
  • the voltage generated by the induced electromotive force on the first set of detection coils is U1
  • the voltage generated by the induced electromotive force on the second set of detection coils is U2.
  • ⁇ U is the voltage generated by the single-turn coil affected by the eddy current diamagnetic field
  • the single-turn coil is any closed coil that can completely surround the eddy current diamagnetic field generated by the foreign body.
  • the foreign body inside the first set of detection coils is generated The magnetic field is completely surrounded by the first group of detection coils, and at the same time is completely surrounded by the second group of detection coils.
  • N1 and N2 are the turns of the first group of detection coils and the second group of detection coils, respectively.
  • the voltage U1 induced on the first group of detecting coils and the voltage U2 induced on the second group of detecting coils are not equal.
  • the voltage U1 induced on the first set of detection coils is not equal to the voltage U2 induced on the second set of detection coils.
  • the first group of detection coils and the second group of detection coils have the same voltage when there is no metal foreign object.
  • the voltages are different, and whether the voltages of the first group of detection coils and the second group of detection coils are equal can be used as the basis for judging metal foreign body intrusion.
  • the processor 204 is configured to determine whether the induced voltage U1 generated by the first set of detection coils in the time-varying magnetic field and the induced voltage U2 generated by the second set of detection coils in the time-varying magnetic field are equal in value, And based on the result, determine whether there is a foreign body.
  • the induced voltage of the first set of detection coils and the induced voltage of the second set of detection coils may not be equal when there is no foreign matter, but the output voltage after processing by the processor is equal. Because the processor processing process is linear, if there is a foreign object, the induced voltage value of the two coils is not equal to the induced voltage value when there is no foreign object, and the output after linear processing is not equal, and the induction output of the processor when there is no foreign object is also achieved. The voltage is equal, and the induced voltage output by the processor is not equal when there is a foreign object.
  • the processor 204 may include a filtering unit, a calculation unit, an amplification unit, and a comparison unit.
  • the filter unit is used to filter out the excitation frequency components;
  • the calculation unit is used to calculate the voltage signal,
  • the amplifying unit is used to amplify the calculated output signal to a size that is easy to distinguish, and
  • the comparison unit is used to compare the previous stage output and set the threshold. Different signals are output according to the comparison result, for example, a high-level signal and a low-level signal.
  • the internal structure of the processor is not limited, and all devices, modules, or units that can realize voltage signal processing and compare the value relationship between U1 and U2 belong to the processor described in this application.
  • the processor 204 collects the coil voltages U1 and U2, uses U1 and U2 as signal sources, and U1 and U2 are in opposite directions and equal in magnitude. After a series of filtering, amplification, addition and other methods to process the signal, U1 and U2 are added to zero, and the processor 204 outputs signal A, indicating that there is no foreign matter in the wireless charging system. When the voltages U1 and U2 are in opposite directions but not equal in size , U1 and U2 are not zero after being added, and the processor 204 outputs a signal B, indicating that there is a foreign object in the wireless charging system.
  • Signal A and signal B can be digital signals with significant recognizable differences or analog signals with significant recognizable differences that can be recognized by other parts of the system.
  • signal A is low or zero, and signal B is high. level.
  • it may also include a switch that controls the operation of the wireless charging system, and shuts off the normal operation of the wireless charging system through the identification signal B to prevent accidents; it may also include an alarm for alarm when the processor 204 determines that there is a foreign object. , By identifying different signals and making different physical actions, remind users to pay attention to foreign body intrusion. When there is no foreign body intrusion, signal A is recognized by the alarm, and the alarm does not respond.
  • the signal B is recognized by the alarm, and the alarm makes a physical response, such as an alarm including an LED light, the LED light flashes; an alarm including a buzzer, the buzzer emits a sound. This reminds the user that there is metal foreign body intrusion.
  • the processor 204 collects the coil voltages U1 and U2, uses U1 and U2 as signal sources, and U1 and U2 have the same direction and the same magnitude. After a series of filtering, amplification, and subtraction, U1 and U2 are subtracted to zero. The processor 204 outputs signal A, indicating that there is no foreign matter in the wireless charging system. When the voltages U1 and U2 are in the same direction but not equal in size, U1 After subtracting from U2, it is not zero, and the processor 204 outputs a signal B, indicating that there is a foreign object in the wireless charging system.
  • Signal A and signal B can be digital signals with significant recognizable differences or analog signals with significant recognizable differences that can be recognized by other parts of the system.
  • signal A is low or zero, and signal B is high. level.
  • it may also include a switch that controls the operation of the wireless charging system, and shuts off the normal operation of the wireless charging system through the identification signal B to prevent accidents; it may also include an alarm for alarm when the processor 204 determines that there is a foreign object.
  • the processor 204 determines that there is a foreign object.
  • each turn of the coil in each group of detection coils is substantially the same.
  • the time-varying magnetic field is a uniform magnetic field, the amount of change in the magnetic flux of any coil in each group of detection coils in the time-varying magnetic field is the same;
  • the area of each turn of the coil is the same, but the time-varying magnetic field is a non-uniform magnetic field, or if the time-varying magnetic field is a uniform magnetic field, the area of the area enclosed by each turn of the coil in each group of detection coils
  • any one-turn coil in each group of detection coils is at the time There is a certain difference in the amount of change of the magnetic flux in the variable magnetic field.
  • the turn spacing between each turn of the coil in each group of coils is small, and the magnetic field generated by the exciting coil can be considered to be approximately uniform in practice, and the area of the enclosed area of each coil can be considered to be substantially the same Therefore, the difference in the amount of change of the magnetic flux in the time-varying magnetic field of any coil in each group of detection coils is small. That is to say, the amount of change in the magnetic flux in the time-varying magnetic field of any coil in each group of detection coils can be considered the same.
  • the average value of the magnetic flux changes in the time-varying magnetic field of each coil in each group of detection coils can be used to calculate the induced voltage of each group of detection coils, or any turn in each group of detection coils can be used.
  • the amount of change in the magnetic flux of the coil in the time-varying magnetic field is used to calculate the induced voltage of each group of coils. It can be understood that any change in the magnetic flux of each coil in each group of detection coils in the time-varying magnetic field can be used to calculate the induction.
  • the voltage mode is applicable to the embodiments of the present application.
  • the second embodiment of the present application provides a foreign body detection method. As shown in FIG. 4, a schematic diagram of the steps of the foreign body detection method is shown. The method includes the following steps:
  • the processor collects the voltage U1 of the first group of detection coils and the voltage U2 of the second group of detection coils;
  • the processor calculates whether the voltage U1 of the first group of detection coils and the voltage magnitude U2 of the second group of detection coils are equal, and if they are not equal, judge that there is a foreign body;
  • S403 The processor sends out different signals according to the detection result. If the voltage of the first group of detection coils is equal to the voltage of the second group of detection coils, the processor outputs signal A. If the voltage of the first group of detection coils is equal to that of the second group The voltage of the detection coil is not equal, and the processor outputs signal B.
  • S404 may also be included:
  • the alarm does not respond when it recognizes signal A, and it alarms when it recognizes signal B.
  • an alarm including an LED light the LED light flashes; an alarm including a buzzer, the buzzer emits a sound.
  • the aforementioned foreign body detection device may have a detection blind zone.
  • the third embodiment of the present application provides a foreign object detection device, which can realize blind spot detection.
  • the detection device composed of the first group of detection coils 201 and the second group of detection coils 202 in the first embodiment is taken as an example to illustrate the detection blind area. According to the formula:
  • Figure 5 is a schematic diagram of the detection blind area.
  • the metal foreign body 504 crosses the first group of detection coils 501, the eddy current diamagnetic field generated in the magnetic field of the excitation coil 503, part of which falls inside the first group of detection coils 501,
  • the induced voltage generated on the single-turn coil in the first group of detection coils 501 is ⁇ U1
  • the induced voltage generated on the single-turn coil in the second group of 502 detection coils is ⁇ U1 ⁇ ; part of it falls outside the first group of detection coils 501, This part does not generate an induced voltage on the first group of detection coils 501, and the induced voltage generated on the single-turn coil of the second group of detection coils 502 is ⁇ U2.
  • the induced voltage generated by the magnetic field generated by the eddy current of the foreign body on the first set of detection coils is actually the induced voltage generated by the eddy current magnetic field of the foreign body falling into the inner part of the first set of coils 501.
  • the induced voltage generated on the two sets of detection coils is actually the induced voltage generated by the eddy current magnetic field of the foreign body inside the second set of detection coils.
  • the induced voltages of the two coils are respectively:
  • N 2 ⁇ N1, and ⁇ U1, ⁇ U1 ⁇ , and ⁇ U2 are all generated by eddy current diamagnetic field. Because the high-frequency magnetic field generated by the excitation coil has approximately uniform magnetic induction in the two detection coils, At a certain frequency, in the magnetic field where the magnetic induction intensity in the two sets of detection coils changes with time, the magnitude of the single-turn coil induced electromotive force only depends on the area of the time-varying magnetic field passing through the closed loop.
  • the voltage induced by the part of the foreign body in the single-turn coils of the first group of coils and the second group of coils is equal, that is
  • the detection blind zone 505 such as Figure 5 shows the shaded part.
  • the above content is only for the convenience of understanding the description of the detection.
  • the magnetic field generated by the foreign object is not necessarily uniform.
  • the first group of detection coils and the second group of detection coils are in the The calculation of the induced electromotive force in the magnetic field generated by the foreign body is more complicated, but for the detection, it can be determined that when the foreign body straddles the first group of detection coils and is divided into two parts by the first group of coils, There is a greater possibility of detecting blind spots.
  • the foreign body detection device includes a first group of detection coils 601, a second group of detection coils 602, a third group of detection coils 603, Coil 604 and processor 605.
  • the first group of detection coils, the second group of detection coils, the third group of detection coils, and the excitation coil together form a detection unit.
  • the detection unit includes a first group of detection coils 601 and a second group of detection coils.
  • the foreign body detection device described in this embodiment may also include a foreign body detection device with more than three sets of detection coils, and its structure and detection principle are similar to the implementation of a foreign body detection device including three sets of detection coils. No longer.
  • the respective front projections of the first group of detection coils 201, the second group of detection coils 202, and the excitation coils 203 are all a planar coil, and their respective front projections are in the same plane.
  • the first group of detection coils 201, the second group of detection coils 202, and the excitation coils 203 are located in the same plane.
  • the first group of detection coils 201, the second group of detection coils 202, and the excitation coil 203 are not located in the same plane, or in other words, the first group of detection coils 201, the second group of detection coils 202 The distance between at least one coil of the excitation coil 203 and the other coils relative to the projection plane is not equal.
  • the first group of detection coils 601, the second group of detection coils 602, and the third group of detection coils 603 are all planar coils, and the first group of detection coils 601, the second group of detection coils 602, and the third group of detection coils The coil 603 is located in the same plane.
  • the first group of detection coils 601, the second group of detection coils 602, and the third group of detection coils 603 all include multi-turn coils, and the multi-turn coils of each group of the detection coils are coaxial.
  • the shape of the coil can be rectangular, circular or polygonal, which is not limited in the embodiment of the present application.
  • the first group of detection coils 601 is located inside the second group of detection coils 602, and the second group of detection coils 602 is located inside the third group of detection coils 603, that is, the first group of detection coils 601 is the innermost coil group, and the second group 602 detects The coil is the middle coil group, and the third group of detection coils 603 is the outermost coil group.
  • the first group of detection coils 601, the second group of detection coils 602, and the third group of detection coils 603 are all located inside the excitation coil 604.
  • the first group of detection coils 601 is completely surrounded by the second group of detection coils 602
  • the second group of detection coils 602 is completely surrounded by the third group of detection coils 603, the first group of detection coils 601, the second group of detection coils 602, and the The three sets of detection coils 603 are completely surrounded by the excitation coil 604.
  • the inner first group of detection coils, the middle second group of detection coils, and the outer third group of detection coils are spaced apart from each other.
  • the excitation coil 604 is connected to a sinusoidal excitation input current to provide a time-varying magnetic field, which is substantially uniform for the first group of detection coils 601, the second group of detection coils 602, and the third group of detection coils 603 .
  • the substantially uniformity should be subject to the understanding of those skilled in the art, such as a 5% fluctuation.
  • the excitation coil used to generate the time-varying magnetic field serves as the magnetic field excitation source of the independently set detection coil, wherein the detection coil includes a first group of detection coils, a second group of detection coils, and a third group of detection coils. Detection coil.
  • the independently set magnetic field excitation source can eliminate system interference in the wireless charging system, and further ensure that the detection coil can accurately detect foreign objects.
  • the excitation coil 604 can also be a transmitting coil in the wireless charging system, which can further save costs, so that the detection coil can be applied to various wireless charging systems to detect foreign objects conveniently and quickly.
  • the first group of detecting coils 601 and the third group of detecting coils 603 form a first coil pair 6001
  • the second group of detecting coils 602 and the third group of detecting coils 603 form a second coil pair 6002
  • the first coil pair and the first coil pair The combination of the two coils is used to detect whether there is a foreign object between the wireless charging transmitter and the receiving device and eliminate the detection blind zone.
  • a current with a frequency different from the working frequency of the wireless charging system flows in the excitation coil.
  • the excitation coil uses a 6.78MHz high-frequency sinusoidal current, which is staggered with the 85kHz frequency of the wireless charging system, which is convenient for the processor to filter.
  • the first group of detection coils 601 and the third group of detection coils 603 satisfy the following formula:
  • the second group of detection coils 602 and the third group of detection coils 603 satisfy the following formula:
  • N1 is the number of coil turns in the first group of detection coils 601
  • N2 is the number of coil turns in the second group of detection coils 602
  • N3 is the number of coil turns in the third group of detection coils 603
  • ⁇ 1 is the magnetic flux through the coil of the first set of single-turn detection coil 601, ⁇ 2 to pass through the single coil magnetic flux of the second set of detection coil 602, ⁇ 3 for the detection coil 603 through a third set of single coil Magnetic flux
  • t is time
  • d ⁇ 1 is based on the magnetic induction intensity of the time-varying magnetic field and the enclosing of any coil in the first group of detection coil
  • the first group of detection coils 601, the second group of detection coils 602, and the third group of detection coils 603 are placed in a uniform time-varying magnetic field at the plane of the two coils. According to the principle of Faraday electromagnetic induction, the high-frequency time-varying magnetic field will be The electromotive force E is induced in the closed loop:
  • the coils with different winding directions will induce different electromotive forces in positive and negative directions. Since the high-frequency magnetic field generated by the excitation coil has approximately uniform magnetic induction intensity B in the three groups of detection coils, at a certain frequency, the change of the magnetic induction intensity B in the three groups of detection coils over time is approximately the same, so the magnitude of the induced electromotive force E It only depends on the area S that the time-varying magnetic field passes through the closed loop and the number of turns N of the closed loop coil.
  • the induced electromotive force of each group of detection coils is related to the number of turns of the regrouped detection coils and the rate of change of magnetic flux of any coil in the group of detection coils.
  • the induced electromotive force of the first group of detection coils is related to the number of turns of the first group of detection coils and the rate of change of magnetic flux of each turn of the first group of detection coils.
  • the magnetic flux of each turn of the coil is related to the magnetic induction intensity of the time-varying magnetic field and the area of the area enclosed by the turn of the coil.
  • the magnetic flux of the first-turn coil is related to the magnetic induction intensity of the time-varying magnetic field and the area of the area enclosed by the first-turn coil.
  • the first group of detection coils 601, the second group of detection coils 602, and the third group of detection coils 603 have different numbers of turns and different areas. By adjusting the winding direction of the coil, the induced electromotive force direction of the three sets of coils can be adjusted.
  • the first coil pair 6001 the first group of detection coils 601 with a small area has more turns and a large area
  • the third group of detection coils 603 has fewer turns; in the second coil pair 6002, the second group of detection coils 602 with a small area has more turns, and the third group of detection coils 603 with a larger area has fewer turns.
  • the product of the number of turns of the first group of detection coils 601 and the area enclosed by the first group of detection coils 601 is adjusted to be equal to the product of the number of turns of the third group of detection coils 603 and the area enclosed by the third group of detection coils 603 .
  • the magnitude of the induced electromotive force generated by the first group of detecting coils 601 in the time-varying magnetic field and the magnitude of the induced electromotive force generated by the third group of detecting coils 603 in the time-varying magnetic field can be made equal; when adjusting the second group of detecting coils
  • the product of the number of turns of 602 and the area enclosed by the second group of detecting coils 602 is equal to the product of the number of turns of the third group of detecting coils 603 and the area enclosed by the third group of detecting coils 603, the second group of detecting
  • the magnitude of the induced electromotive force generated by the coil 602 in the time-varying magnetic field is equal to the magnitude of the induced electromotive force
  • the second group of detection coils 602 and the third group of detection coils 603 further satisfy the following formula:
  • N1 is the number of turns of the first set of coils
  • N2 is the number of turns of the second set of coils
  • N3 is the number of turns of the third set of coils
  • S1 is the first set of detection coils
  • S2 is the area enclosed by any coil in the second group of detection coils
  • S3 is the area enclosed by any coil in the third group of detection coils.
  • B is the magnetic induction intensity
  • t is the time
  • Is the rate of change of magnetic induction intensity over time.
  • the high-frequency magnetic field generated by the excitation coils has approximately uniform magnetic induction in the first group of detection coils, the second group of detection coils, and the third group of detection coils, under the same frequency AC excitation, the first group of detection coils, the second group The change rate of the magnetic induction intensity in the group detection coil and the third group detection coil with time Approximately the same. That is, the product of the number of turns and the area of the first group of detection coils is equal to the product of the number of turns and the area of the third group of detection coils. The products of the areas are equal.
  • the presence of foreign objects will distort the induced magnetic field.
  • the induced electromotive force will also be induced in the time-varying magnetic field.
  • the direction of the magnetic field is opposite to the original time-varying magnetic field, which is called eddy current diamagnetic field. Biological foreign objects can also distort the time-varying magnetic field.
  • the eddy current diamagnetic field generated by the metal foreign body will generate induced electromotive force on the first group of detection coils, the second group of detection coils and the third group of detection coils.
  • the voltage generated by the induced electromotive force on the first set of detection coils is U1
  • the voltage generated by the induced electromotive force on the second set of detection coils is U2
  • the voltage generated by the induced electromotive force on the third set of detection coils is U3.
  • ⁇ U is the voltage generated by the single-turn coil affected by the eddy current diamagnetic field
  • the single-turn coil is any closed coil that can completely surround the eddy current diamagnetic field generated by the foreign body.
  • the foreign body inside the first set of detection coils The magnetic field is completely surrounded by the first group of detection coils and at the same time by the third group of detection coils; the magnetic field generated by the foreign objects in the second group of detection coils is completely surrounded by the second group of detection coils, and also by the third group The detection coil is completely enclosed.
  • N1, N2, and N3 are the turns of the first group of detection coils, the second group of detection coils, and the third group of detection coils, respectively.
  • the voltage U1 induced on the first group of detection coils is not equal to the voltage U3 induced on the third group of detection coils; Since the number of turns N2 of the second group of detecting coils and the number of turns N3 of the third group of detecting coils are not equal, the voltage U2 induced on the second group of detecting coils is not equal to the voltage U3 induced on the third group of detecting coils.
  • the voltage U1 induced on the first group of detection coils is not equal to the voltage U3 induced on the third group of detection coils;
  • the voltage U2 induced on the second set of detection coils is not equal to the voltage U3 induced on the third set of detection coils.
  • the first group of detection coils and the third group of detection coils have the same voltage level when there is no metal foreign object.
  • the voltage levels are different; the second group of detection coils and the third group of detection coils have the same voltage levels when there are no metal foreign objects, and the voltage levels are different when there are metal foreign objects. Therefore, whether the voltages of the first group of detecting coils and the third group of detecting coils are equal, or whether the voltages of the second group of detecting coils and the third group of detecting coils are equal can be used as the basis for judging metal foreign body intrusion.
  • the detection blind area of the first coil pair composed of the first group of detection coils and the third group of detection coils is located near the first coil
  • the detection blind area of the second coil pair composed of the second group of detection coils and the third group of detection coils is located in the first Near the second coil
  • the detection blind area of the first coil pair and the second coil pair do not overlap, so the combination of the first coil pair and the second coil pair can effectively eliminate the detection blind area problem when there are only two sets of detection coils.
  • the processor 605 is configured to determine the induced voltage U1 generated by the first group of detection coils in the time-varying magnetic field and the induced voltage U3 generated by the third group of detection coils in the time-varying magnetic field of the first coil pair Whether the values are equal, or determine whether the second group of detection coils of the second coil pair generates the induced voltage U2 in the time-varying magnetic field and the third group of detection coils generates the induced voltage in the time-varying magnetic field. Whether the value of the voltage U3 is equal, and based on the result, it is determined whether there is a foreign body. If the results of the first coil pair and the second coil pair are not equal, it is determined that there is a foreign object.
  • the processing 605 may include a filtering unit, a calculation unit, an amplification unit, and a comparison unit.
  • the filter unit is used to filter out the excitation frequency components;
  • the calculation unit is used to calculate the voltage signal,
  • the amplifying unit is used to amplify the calculated output signal to a size that is easy to distinguish, and
  • the comparison unit is used to compare the previous stage output and set the threshold. Different signals are output according to the comparison result, for example, a high-level signal and a low-level signal.
  • the internal structure of the processor is not limited, and all devices, modules or units that can realize voltage signal processing and compare the numerical relationship between U1 and U3, or the numerical relationship between U2 and U3, belong to this application. The processor described.
  • the processor 605 collects the coil voltages U1 and U3, uses U1 and U3 as signal sources, and U1 and U3 are equal in magnitude and opposite in direction. After a series of filtering, amplification, addition and other methods to process the signal, U1 and U3 are added to zero, and the processor 605 outputs signal A, indicating that there is no foreign matter in the wireless charging system. When the voltages U1 and U3 are not equal, U1 and U3 U3 is not zero after being added, and the processor 605 outputs signal B, indicating that there is a foreign object in the wireless charging system.
  • Signal A and signal B can be digital signals with significant recognizable differences or analog signals with significant recognizable differences that can be recognized by other parts of the system.
  • signal A is low or zero, and signal B is high. level.
  • it may also include a switch that controls the operation of the wireless charging system, and shuts off the normal operation of the wireless charging system through the identification signal B to prevent accidents; it may also include an alarm for the processor 605 to alarm when a foreign object is detected , By identifying different signals and making different physical actions, remind users to pay attention to foreign body intrusion. When there is no foreign body intrusion, signal A is recognized by the alarm, and the alarm does not respond. When there is a foreign body intrusion, the signal B is recognized by the alarm, and the alarm makes a physical response, such as an alarm including an LED light, the LED light flashes; an alarm including a buzzer, the buzzer emits a sound. This reminds the user that there is metal foreign body intrusion.
  • the processor 605 collects the coil voltages U2 and U3, uses U2 and U3 as signal sources, and U2 and U3 are equal in magnitude and in the same direction. After a series of filtering, amplification, subtraction, etc., U2 and U3 are subtracted to zero. The processor 605 outputs signal A, indicating that there is no foreign matter in the wireless charging system. When the voltages U2 and U3 are not equal, U2 and U3 are After the subtraction is not zero, the processor 605 outputs a signal B, indicating that there is a foreign object in the wireless charging system.
  • Signal A and signal B can be digital signals with significant recognizable differences or analog signals with significant recognizable differences that can be recognized by other parts of the system.
  • signal A is low or zero, and signal B is high. level.
  • it may also include a switch that controls the operation of the wireless charging system, and the normal operation of the wireless charging system is shut off by the identification signal B to prevent accidents; it may also include an alarm for alarm when the processor 605 determines that there is a foreign object.
  • an alarm for alarm when the processor 605 determines that there is a foreign object.
  • any one of the two coil pairs will trigger an alarm. If the foreign body is in the detection blind zone of a certain coil pair, the other coil pair An alarm will be triggered. Therefore, if any coil pair detects a foreign object, it can be determined that there is a foreign object in the wireless charging system.
  • each turn of the coil in each group of detection coils is substantially the same.
  • the time-varying magnetic field is a uniform magnetic field, the amount of change in the magnetic flux of any coil in each group of detection coils in the time-varying magnetic field is the same;
  • the area of each turn of the coil is the same, but the time-varying magnetic field is a non-uniform magnetic field, or if the time-varying magnetic field is a uniform magnetic field, the area of the area enclosed by each turn of the coil in each group of detection coils
  • any one-turn coil in each group of detection coils is at the time There is a certain difference in the amount of change of the magnetic flux in the variable magnetic field.
  • the turn spacing between each turn of the coils in each group of coils is small, and the magnetic field generated by the exciting coil can be considered to be approximately uniform in practice, and the area of the enclosed area of each turn of the coil can be considered to be substantially the same Therefore, the difference in the amount of change of the magnetic flux in the time-varying magnetic field of any coil in each group of detection coils is small. That is to say, the amount of change in the magnetic flux in the time-varying magnetic field of any coil in each group of detection coils can be considered the same.
  • the average value of the magnetic flux changes in the time-varying magnetic field of each coil in each group of detection coils can be used to calculate the induced voltage of each group of detection coils, or any turn in each group of detection coils can be used.
  • the amount of change in the magnetic flux of the coil in the time-varying magnetic field is used to calculate the induced voltage of each group of coils. It can be understood that any change in the magnetic flux of each coil in each group of detection coils in the time-varying magnetic field can be used to calculate the induction.
  • the voltage mode is applicable to the embodiments of the present application.
  • FIG. 8 is a schematic diagram of the steps of the foreign body detection method. The method includes the following steps:
  • the processor collects the voltage U1 of the first group of detection coils, the voltage U2 of the second group of detection coils, and the voltage U3 of the third group of detection coils;
  • the processor calculates whether the voltage U1 of the first group of detecting coils and the voltage U3 of the third group of detecting coils are equal, if they are not equal, it is judged that there is a foreign object, if they are equal, the voltage U2 and the third group of detecting coils Whether the voltage U3 of the group detection coil is equal, if not, it is judged that there is a foreign body;
  • S803 Send out different signals according to the detection result. If the voltage U1 of the first group of detection coils is equal to the voltage U3 of the third group of detection coils, at the same time, the voltage of the second group of detection coils U2 and the voltage of the third group of detection coils U3 is equal, and the processor outputs signal A; if the voltage U1 of the first group of detection coils and the voltage of the third group of detection coils U3 are not equal, or the voltage of the second group of detection coils U2 and the voltage of the third group of detection coils U3 is not equal in size, and the processor outputs signal B.
  • S804 may also be included:
  • the alarm does not respond when it recognizes signal A, and it alarms when it recognizes signal B.
  • an alarm including an LED light the LED light flashes; an alarm including a buzzer, the buzzer emits a sound.
  • the foreign body detection device described in this embodiment may also include a foreign body detection device with more than three sets of detection coils, and its structure and detection principle are similar to the implementation of the foreign body detection device including three sets of detection coils. That is, in the foregoing embodiment, the first group of detection coils is a possible realization of the innermost detection coil, the second group of detection coils is a possible realization of any group of detection coils in the middle, and the third group of detection coils is the most A possible implementation of the outer detection coil. I will not repeat them here.
  • the fifth embodiment of the present application provides a foreign body detection device.
  • the foreign body detection device is obtained by splicing N detection coils 901 of the foreign body detection device described in the third embodiment in series, and is used for expanded detection. area.
  • the specific implementation is similar to the second embodiment, and will not be repeated here.
  • the sixth embodiment of the present application provides a foreign body detection system, which includes the foreign body detection device described in the first or third or fifth embodiment and a charging system, and the wireless charging foreign body detection device is used to detect whether there is a foreign body in the charging system , I won’t repeat it here.

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Abstract

本申请提供一种无线充电异物检测装置，应用于无线充电技术领域。该检测装置包括了用于提供时变磁场的激励线圈，用于检测异物的检测线圈和判断是否存在异物的处理器。检测线圈可以由两组检测线圈组成，也可以由至少三组检测线圈组成，其中，至少三组检测线圈还可以用于消除检测盲区。

Description

无线充电***的异物检测装置、方法及无线充电*** 技术领域
本申请涉及无线充电技术领域，尤其涉及一种无线充电异物检测装置、方法和***。
背景技术
在目前的无线充电技术中，磁感应耦合式及谐振耦合式两种技术方案应用最为广泛。这两种技术方案均基于电磁感应原理，通过发射线圈的高频交变电流产生高频磁场，通过高频磁场将能量从发射线圈传送到接收线圈，实现无线充电。在实际应用中，由于金属在时变磁场中存在涡流效应，会在金属内部形成感应涡流，尤其当异物较大时，会显著降低无线充电***的能量的传输效率。
当前的无线充电***中，会采用感应电压法进行异物检测。感应电压法的原理是将检测线圈置于高频磁场中，通过判断检测线圈的感应电压是否出现异常来判断磁场是否出现畸变，进而判断是否存在异物。可通过调整检测线圈大小来调整检测精度，对小型异物也同样适用。
感应电压法存在两个难以克服的缺点，一是为保证检测精度，需令穿过相应检测线圈的磁通量相等，因此需对检测线圈进行处理，检测***较为复杂；二是检测线圈有检测盲区，目前有效的盲区消除方法是铺设多层错位的检测线圈，但这样将显著增加检测***的成本。
发明内容
本申请公开一种无线充电异物检测装置和方法，基于感应电压法的原理，用以解决现有技术中异物检测装置结构繁杂，避免检测盲区时，成本较高的缺点。
本申请的第一方面，提供了一种用于无线充电***的异物检测装置，所述检测装置包括激励线圈，检测线圈，处理器，其中：
所述激励线圈用于提供时变磁场；
所述检测线圈用于检测无线充电发射装置和接收装置之间是否存在异物；
所述检测线圈包括第一组检测线圈和第二组检测线圈，所述第一组检测线圈、所述第二组检测线圈和所述激励线圈各自的正投影均为一个平面线圈，且它们各自的正投影位于同一平面内，且彼此隔离，其中，所述第二组检测线圈位于所述第一组检测线圈和所述激励线圈之间，所述第一组检测线圈位于所述第二组检测线圈的内侧，所述激励线圈位于所述第二组检测线圈的外侧；
所述处理器用于判断所述第一组检测线圈在所述时变磁场中产生的感应电压值和所述第二组检测线圈在所述时变磁场中产生的感应电压值是否相等，结果不相等则判定存在异物。
根据第一方面，在第一方面的第一种可能的实现方式中，在所述时变磁场的目标区域内，磁场分布是实质均匀的，其中，所述时变磁场的目标区域是指所述第一组检测线圈和所述第二组检测线圈所位于的时变磁场的区域。
根据第一方面或第一方面的第一种可能的实现方式，在第一方面的第二种可能的实现方式中，所述第一组检测线圈和所述第二组检测线圈满足如下公式：
Figure PCTCN2020081273-appb-000001
其中，N1为所述第一组检测线圈中的线圈匝数，N2为所述第二组检测线圈的线圈匝数；φ 1为穿过第一组检测线圈中单匝线圈的磁通量，φ 2为穿过第二组检测线圈中单匝线圈的磁通 量，t为时间，
Figure PCTCN2020081273-appb-000002
为穿过第一组检测线圈中单匝线圈的磁通量随时间的变化率，
Figure PCTCN2020081273-appb-000003
为穿过第二组检测线圈中单匝线圈的磁通量随时间的变化率；dφ 1是根据所述时变磁场的磁感应强度以及所述第一组检测线圈的线圈面积确定的，dφ 2是根据所述时变磁场的磁感应强度以及所述第二组检测线圈的线圈面积确定的。
根据第一方面或第一方面的第一至第二种可能的实现方式，在第一方面的第三种可能的实现方式中，所述第一组检测线圈和所述第二组检测线圈满足如下公式：
Figure PCTCN2020081273-appb-000004
其中，N1为所述第一组检测线圈中的线圈匝数，N2为所述第二组检测线圈的线圈匝数；S1为所述第一组检测线圈的线圈面积，S2为所述第二组检测线圈的线圈面积，B为磁感应强度，t为时间，
Figure PCTCN2020081273-appb-000005
为磁感应强度随时间的变化率。
根据第一方面或第一方面的第一至第三种可能的实现方式，在第一方面的第四种可能的实现方式中，所述第一组检测线圈的匝数与所述第一组检测线圈所围合的面积的乘积等于所述第二组检测线圈的匝数与所述第二组检测线圈所围合的面积的乘积。
根据第一方面或第一方面的第一至第四种可能的实现方式，在第一方面的第五种可能的实现方式中，所述第一组检测线圈和所述第二组检测线圈的匝数不同，其中，所述第一组检测线圈和所述第二组检测线圈的匝数不同是由于所述第一组检测线圈和所述第二组检测线圈所围合的区域的面积不同。
根据第一方面或第一方面的第一至第五种可能的实现方式，在第一方面的第六种可能的实现方式中，所述第一组检测线圈和所述第二组检测线圈均为平面线圈，且所述第一组检测线圈和所述第二组检测线圈位于同一平面内。
根据第一方面或第一方面的第一至第六种可能的实现方式，在第一方面的第七种可能的实现方式中，所述第一组检测线圈和所述第二组检测线圈均包括多匝线圈，每一组所述检测线圈的所述多匝线圈是同轴的。
根据第一方面或第一方面的第一至第七种可能的实现方式，在第一方面的第八种可能的实现方式中，所述无线充电***的异物检测装置还可以包括报警器，所述报警器用于在所述处理器判断出存在异物时报警。
本申请的第二方面，提供了一种用于无线充电***的异物检测装置，所述检测装置包括激励线圈，检测线圈，处理器，其中：
所述激励线圈用于提供时变磁场；
所述检测线圈用于检测无线充电发射装置和接收装置之间是否存在异物；
所述检测线圈包括至少三组检测线圈，所述至少三组检测线圈中每一组检测线圈的正投影均为一个平面线圈，所述激励线圈的正投影也为一个平面线圈，且所述至少三组检测线圈中的每一组检测线圈的正投影以及所述激励线圈的正投影均位于同一平面内，且彼此隔离；
所述至少三组检测线圈中每两组检测线圈形成一个线圈对，每一个线圈对用于消除检测盲区；
所述处理器用于判断每一个线圈对的两组线圈在所述时变磁场中产生的感应电压值是否相等，结果不相等则判定存在异物。
根据第二方面，在第二方面的第一种可能的实现方式中，在所述时变磁场的目标区域内， 磁场分布是实质均匀的，其中，所述时变磁场的目标区域是指所述至少三组检测线圈所位于的时变磁场的区域。
根据第二方面或第二方面的第一种可能的实现方式，在第二方面的第二种可能的实现方式中，位于每一线圈对内的其中一组检测线圈所围合的面积与所述其中一组检测线圈的匝数的乘积等于另一组检测线圈所围合的面积与所述另一组检测线圈的匝数的乘积。
根据第二方面或第二方面的第一至第二种可能的实现方式，在第二方面的第三种可能的实现方式中，所述至少三组检测线圈中每两匝检测线圈的匝数不同，其中，所述至少三组检测线圈的匝数不同是由于所述至少三组检测线圈各自所围合的区域的面积不同。
根据第二方面或第二方面的第一至第三种可能的实现方式，在第二方面的第四种可能的实现方式中，所述至少三组检测线圈均为平面线圈，且所述至少三组检测线圈位于同一平面内。
根据第二方面或第二方面的第一至第四种可能的实现方式，在第二方面的第五种可能的实现方式中，所述至少三组检测线圈，均包括多匝线圈，每一组所述检测线圈的所述多匝线圈是同轴的。
根据第二方面或第二方面的第一至第五种可能的实现方式，在第二方面的第六种可能的实现方式中，所述无线充电***的异物检测装置还可以包括报警器，所述报警器用于在所述处理器判断出存在异物时报警。
本申请的第三方面，提供了一种无线充电异物检测方法，包括：
处理器采集第一组检测线圈在激励线圈产生的时变磁场中感应的电压和第二组检测线圈在激励线圈产生的时变磁场中感应的电压；
处理器判断第一组检测线圈在所述时变磁场中感应的电压和第二组检测线圈在所述时变磁场中产生的感应电压数值是否相等，若不相等，则判定存在异物；
处理器根据不同的检测结果，发出不同的信号。
根据第三方面，在第三方面的第一种可能的实现方式中，还包括：
在所述处理器判断出存在异物时报警，或者，控制无线充电***工作的开关，在所述处理器判断出存在异物时关断无线充电***的正常工作。
本申请的第四方面，提供了一种无线充电异物检测方法，包括：
处理器采集至少三组检测线圈在激励线圈产生的时变磁场中感应的电压，其中：所述至少三组检测线圈中任意两组检测线圈形成一个线圈对；
处理器判断任一线圈对的两组线圈在所述时变磁场中产生的感应电压数值是否相等，若不相等，则判定存在异物；
处理器根据检测结果，发出不同的信号。
根据第四方面，在第四方面的第一种可能的实现方式中，还包括：
在所述处理器判断出存在异物时报警，或者，控制无线充电***工作的开关，在所述处理器判断出存在异物时关断无线充电***的正常工作。
本申请的第五方面，提供一种无线充电异物检测***，所述无线充电异物检测***包括第一方面和第二方面所述的无线充电异物检测装置和充电***，所述无线充电异物检测装置用于检测所述充电***内是否具有异物。
使用本申请所述的异物检测装置，有着可以使用简单的线圈结构实现异物检测并不会存在检测盲区的优点，解决了现有技术中异物检测装置结构繁杂，解决检测盲区问题时成本较高的缺点。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例提供的一种无线充电的***结构示意图；
图2为本申请实施例提供的一种含两组检测线圈的异物检测装置示意图；
图3为本申请实施例提供的一种含两组检测线圈的检测单元示意图；
图4为本申请实施例提供的一种异物检测方法步骤示意图；
图5为本申请实施例提供的一种检测盲区示意图；
图6为本申请实施例提供的一种含三组检测线圈的异物检测装置示意图；
图7为本申请实施例提供的一种含三组检测线圈的检测单元示意图；
图8为本申请实施例提供的另一种异物检测方法步骤示意图；
图9为本申请实施例提供的一种串联检测线圈的检测装置结构示意图。
具体实施方式
本申请应用于无线充电场景中。无线充电，又称为无线电能传输(Wireless Power Transfer，WPT)，是指通过发射装置将电能转换为其他形式的中继能量(如电磁场能、光能及微波能等)，隔空传输一段距离后，再通过接收装置将中继能量转换为电能的技术，无线充电技术在商用化上的进展十分迅猛，其中消费类电子产品的无线充电技术，例如，在智能终端、电动牙刷等产品的应用已经较为成熟，除了消费类电子产品，电动汽车领域也在大力发展无线充电技术。在无线充电技术从实验室逐渐转化为市场应用时，需要解决的关键问题之一是异物检测问题。
在目前的无线充电技术中，磁感应耦合式及谐振耦合式两种技术方案应用最为广泛。这两种技术方案均基于电磁感应原理，通过发射线圈的高频交变电流产生高频磁场，通过高频磁场将能量从发射线圈传送到接收线圈，实现无线充电。在实际应用中，由于金属在时变磁场中存在涡流效应，会在金属内部形成感应涡流，尤其当异物较大时，会显著降低无线充电***的能量的传输效率。在大功率应用场合，异物的感应涡流很大，进而在金属内产生很大的温升，若在无线充电***的工作区域中存在异物，严重情况下会对无线充电***产生不可逆的破坏甚至引起火灾。电动汽车无线充电***的功率等级高，异物发生过热的风险大，因此需要快速、准确地检测金属异物，尤其是在大功率无线充电应用场景下需要高效的异物检测装置，预防灾害发生。
无线充电异物检测技术主要包括功率差值法和感应电压法。
功率差值法原理是当异物入侵无线充电区域时，异物在高频磁场中感应出涡流进而产生损耗。无线充电***发射的总功率不变，金属涡流损耗的增大使得接收线圈的接收功率减少，导致传输效率降低。功率差值比较法通过比较接收线圈接收功率与发射线圈发射功率的差值大小来判断是否存在异物。
功率差值比较法适用于异物涡流损耗较大的情况，若异物涡流损耗相较于***传输功率而言可以忽略，则该方法难以生效，会产生检测不到小体积异物的情况。
感应电压法的原理是将检测线圈置于高频磁场中，通过判断检测线圈的感应电压是否出现异常来判断磁场是否出现畸变，进而判断是否存在异物。可通过调整检测线圈大小来调整 检测精度，对小型异物也同样适用。
感应电压法存在两个难以克服的缺点，一是为保证检测精度，需令穿过相应检测线圈的磁通量相等，因此需对检测线圈进行处理，检测***较为复杂；二是检测线圈有检测盲区，目前有效的盲区消除方法是铺设多层错位的检测线圈，但这样将显著增加检测***的成本。
本申请实施例基于感应电压法的原理，提出了一种无线充电异物检测装置、方法和***，用来解决现有技术中感应电压法检测异物时所存在的问题。
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
如图1所示为一种无线充电***的结构示意图，所述无线充电充电***包括发射端101和接收端102，所述发射端101与发射线圈103相连接，所述接收端102与接收线圈104相连接。所述发射端101用于为为所述接收端102提供电能，或对所述接收端102进行充电。具体的，所述发射线圈103提供交变电流，使得所述发射线圈103产生时变磁场。所述接收线圈104在所述发射线圈103产生的时变磁场中发生电磁感应，使得所述接收线圈104中形成感应电流。
若所述无线充电***中存在异物，由于所述异物在所述发射线圈形成的磁场中会存在涡流效应，导致无线充电***的传输效率下降。
为了能够简单高效地检测所述无线充电***中的异物，本申请实施例一提供了一种异物检测装置，如图2所示，为本申请实施例提供的该异物检测装置结构示意图，所述异物检测装置包括第一组检测线圈201、第二组检测线圈202、激励线圈203和处理器204。其中第一组检测线圈201、第二组检测线圈202和激励线圈203共同组成了一个检测单元，所述检测单元如图3所示，包括了第一组检测线圈201、第二组检测线圈202和激励线圈203。
在一种可能的实现方式中，第一组检测线圈201、第二组检测线圈202和激励线圈203各自的正投均为一个平面线圈，且它们各自的正投影位于同一平面内。在一种可能的实现方式中，第一组检测线圈201、第二组检测线圈202和激励线圈203本身位于同一平面内。在另一种可能的实现方式中，第一组检测线圈201、第二组检测线圈202和激励线圈203本身不位于同一平面内，或者说，第一组检测线圈201、第二组检测线圈202和激励线圈203中的至少一个线圈与其他的线圈相对于投影平面的距离是不相等的。
可选的，第一组检测线圈201与第二组检测线圈202均为平面线圈，且所述第一组检测线圈和所述第二组检测线圈位于同一平面内。所述第一组检测线圈和所述第二组检测线圈均包括多匝线圈，每一组所述检测线圈的所述多匝线圈是同轴的。线圈形状可以为长方形、圆形或多边形，本申请实施例在此不做限制。第一组检测线圈201位于第二组检测线圈202的内侧，第一组检测线圈201和第二组检测线圈202均位于激励线圈203内侧。即第二组检测线圈202位于第一组检测线圈201和激励线圈203之间，其中，第一组检测线圈201位于第二组检测线圈202的内侧，激励线圈203位于第二组检测线圈202的外侧。或者说，第一组检测线圈201被第二组检测线圈202完全包围，第一组检测线圈201和第二组检测线圈202被激励线圈203完全包围。其中，所述内侧的第一组检测线圈201和所述外侧的第二组检测线圈202彼此隔开，所述外侧的第二组检测线圈202和所述激励线圈203彼此隔开。
激励线圈203连接正弦激励输入电流，用于提供时变磁场，该时变磁场对于第一组检测线圈201和第二组检测线圈202来说是实质均匀的。所述实质均匀应当以本领域技术人员的理解为准，例如上下浮动5％。
需要说明的是，所述用于产生时变磁场的激励线圈，作为独立设置的检测线圈的磁场激 励源，其中，所述检测线圈包括第一组检测线圈和第二组检测线圈。这种独立设置的磁场激励源可以排除无线充电***中的***干扰，进一步保证所述检测线圈能够准确的检测到异物。可选地，所述激励线圈203也可以是所述无线充电***中的发射线圈，这样可以进一步节约成本，使得所述检测线圈可以应用于多种无线充电***中，方便、快捷地检测异物。
第一组检测线圈201和第二组检测线圈202，用于检测无线充电发射装置和接收装置之间是否存在异物。激励线圈内流过与无线充电***的工作频率不同频率的电流，例如，激励线圈使用6.78MHz高频正弦电流，与无线充电***的85kHz频率错开，便于处理器滤波。
第一组检测线圈201和第二组检测线圈202满足如下公式：
Figure PCTCN2020081273-appb-000006
其中，N1为所述第一组检测线圈201中的线圈匝数，N2为所述第二组检测线圈202的线圈匝数；φ 1为穿过第一组检测线圈201中单匝线圈的磁通量，φ 2为穿过第二组检测线圈202中单匝线圈的磁通量，t为时间，
Figure PCTCN2020081273-appb-000007
为穿过第一组检测线圈201中单匝线圈的磁通量随时间的变化率，
Figure PCTCN2020081273-appb-000008
为穿过第二组检测线圈202中单匝线圈的磁通量随时间的变化率；dφ 1是根据所述时变磁场的磁感应强度以及所述第一组检测线圈201中任一匝线圈所围合的区域的面积的确定的，dφ 2是根据所述时变磁场的磁感应强度以及所述第二组检测线圈202中任一匝线圈所围合的区域的面积的确定的。
将第一组检测线圈201和第二组检测线圈202置于在两线圈所在平面处处均匀的时变磁场中，由法拉第电磁感应原理可知，高频时变磁场将在闭合回路中感应出电动势E：
Figure PCTCN2020081273-appb-000009
由于感应电动势方向取决于穿过闭合环路的磁场的环路积分，因此不同绕向的线圈将感应出正负不同的电动势。由于激励线圈产生的高频磁场在两组检测线圈中的磁感应强度B大小近似均匀，因此在某一频率下，两组检测线圈内磁感应强度B随时间的变化近似相同，所以感应电动势E的大小仅取决于时变磁场穿过闭合回路的面积S和闭合回路线圈的匝数N。
针对每组检测线圈，每组检测线圈的感应电动势与该组检测线圈的线圈匝数以及该组检测线圈中任一匝线圈的磁通量变化率有关。例如，第一组检测线圈的感应电动势与第一组检测线圈的线圈匝数以及第一组检测线圈中每一匝线圈的磁通量变化率有关。
每一匝线圈的磁通量与所述时变磁场的磁感应强度和该匝线圈所围合的区域的面积有关。例如，第一匝线圈的磁通量与所述时变磁场的磁感应强度和所述第一匝线圈所围合的区域的面积有关。
第一组检测线圈和第二组检测线圈的匝数不同，面积也不同。通过调整线圈的绕向，可使两线圈的感应电动势方向相同或相反。在无异物的正常情况时，通过调整线圈匝数或/和线圈所围合的区域的面积，面积小的第一组检测线圈201匝数多，面积大的第二组检测线圈202匝数少，当调整到第一组检测线圈201的匝数与第一组检测线圈201所围合的面积的乘积等于第二组检测线圈的匝数与第二组检测线圈202所围合的面积的乘积时，可以使得第一组检测线圈201在所述时变磁场中产生的感应电动势和第二组检测线圈202在所述时变磁场中产生的感应电动势数值大小相等。第一组检测线圈201和第二组检测线圈202，进一步地，满足如下公式：
Figure PCTCN2020081273-appb-000010
其中，N1为所述第一组检测线圈中的线圈匝数，N2为所述第二组检测线圈的线圈匝数；S1为所述第一组检测线圈中任一匝线圈所围合的区域的面积，S2为所述第二组检测线圈的中任一线圈所围合的区域的面积，B为磁感应强度，t为时间，
Figure PCTCN2020081273-appb-000011
为磁感应强度随时间的变化率。由于激励线圈产生的高频磁场在第一组检测线圈和第二组检测线圈中的磁感应强度大小近似均匀，在相同频率的交流激励下，第一组检测线圈和第二组检测线圈内磁感应强度随时间的变化
Figure PCTCN2020081273-appb-000012
近似相同。即第一组检测线圈的匝数与面积的乘积和第二组检测线圈的匝数与面积的乘积相等。
在一种可能的实现方式中，第一组检测线圈201和第二组检测线圈202绕向相同，在所述时变磁场中产生的感应电动势大小相等，方向相同；在另一种可能的实现方式中，第一组检测线圈201和第二组检测线圈202绕向相反，在所述时变磁场中产生的感应电动势大小相等，方向相反。
异物的存在会使感应磁场发生畸变，例如，金属异物在时变磁场中也会被感应出感应电动势，该电动势会在金属异物内部产生闭合回路电流，即涡流，涡流可产生磁场，涡流产生的磁场方向与原时变磁场相反，称为涡流反磁场。生物体异物同样会使得时变磁场产生畸变。
在一种可能的实现方式中，金属异物产生的涡流反磁场会在第一组检测线圈和第二组检测线圈上产生感应电动势。第一组检测线圈上感应电动势产生的电压为U1，第二组检测线圈上感应电动势产生的电压为U2。
金属异物侵入无线充电***中时，当金属侵入第一组检测线圈内部时，由于穿过面积小的第一组检测线圈的涡流反磁场必然穿过包围第一组检测线圈的第二组检测线圈，因此得到：
U1＝ΔU*N1
U2＝ΔU*N2
式中ΔU为单匝线圈受涡流反磁场影响而产生的电压，所述单匝线圈为任何能够完全包围异物产生的涡流反磁场的闭合线圈，其中，位于第一组检测线圈内部的异物所产生的磁场被第一组检测线圈完全包围，同时也被第二组检测线圈完全包围。N1、N2分别为第一组检测线圈、第二组检测线圈的匝数。由于第一组检测线圈的匝数N1和第二组检测线圈的匝数N2不相等，所以第一组检测线圈上感应出的电压U1和第二组检测线圈上感应出的电压U2不相等。
同理，当金属侵入第一组检测线圈和第二组检测线圈所夹区域时，由于该区域在第一组检测线圈外部，以及在第二组检测线圈内部，因此可以近似认为涡流反磁场仅穿过第二组检测线圈，不穿过第一组检测线圈，因此得到：
U1＝0
U2＝ΔU*N2
所以第一组检测线圈上感应出的电压U1和第二组检测线圈上感应出的电压U2不相等。
因此，当金属异物落入面积较大的第二组检测线圈内部的检测区域时，所述第一组检测线圈和所述第二组检测线圈在无金属异物时电压大小相同，有金属异物时电压大小不同，可将第一组检测线圈和第二组检测线圈的电压是否相等作为金属异物入侵的判断依据。
处理器204用于判断所述第一组检测线圈在所述时变磁场中产生的感应电压U1和所述第二组检测线圈在所述时变磁场中产生的感应电压U2数值大小是否相等，并基于结果判定是否存在异物。
可以理解的是，第一组检测线圈的感应电压与第二组检测线圈的感应电压在无异物时也可以不相等，但经处理器处理后输出的电压相等。由于处理器处理过程是线性的，因此若异物存在，两线圈的感应电压值与无异物时的感应电压值不相等，经线性处理后输出也不相等，同样达到无异物时处理器输出的感应电压相等，有异物时处理器输出的感应电压不相等的效果。
处理器204内可以包括滤波单元、计算单元、放大单元和比较单元。滤波单元用于筛选出激励频率分量；计算单元用于将电压信号进行计算，放大单元用于将计算后输出的信号放大到易于分辨的大小，比较单元用于比较前级输出和设定阈值，根据比较结果输出不同的信号，例如，高电平信号和低电平信号。可以理解的是，所述处理器内部的结构不受限制，所有能够实现电压信号处理并比较出U1与U2数值关系的器件、模块或单元，都属于本申请所述的处理器。
在一种可能的实现方式中，处理器204采集线圈电压U1和U2，将U1和U2作为信号源，U1和U2方向相反且大小相等。经过一系列滤波、放大、加法等方式处理信号，U1与U2相加后为零，处理器204输出信号A，表明无线充电***中不存在异物，在电压U1和U2方向相反但大小不相等时，U1与U2相加后不为零，处理器204输出信号B，表明无线充电***中存在异物。信号A与信号B可以为具有显著可识别差异的数字信号或可被***其他部分识别的具有显著可识别差异的模拟信号，例如，信号A为低电平或零电平，信号B为高电平。可选地，还可以包括控制无线充电***工作的开关，通过识别信号B来关断无线充电***的正常工作以防止意外发生；还可以包括报警器，用于处理器204判断出存在异物时报警，通过识别不同信号而做出不同的物理动作，提醒使用者注意异物入侵。在没有异物入侵时，信号A被报警器识别，报警器不予反应。在有异物入侵时，信号B被报警器识别，报警器做出物理反应，例如包括LED灯的报警器，LED灯闪亮；包括蜂鸣器的报警器，蜂鸣器发出声音。以此提示使用者有金属异物入侵。
在另一种可能的实现方式中，处理器204采集线圈电压U1和U2，将U1和U2作为信号源，U1和U2方向相同且大小相等。经过一系列滤波、放大、减法等处理，U1与U2相减后为零，处理器204输出信号A，表明无线充电***中不存在异物，在电压U1和U2方向相同但大小不相等时，U1与U2相减后不为零，处理器204输出信号B，表明无线充电***中存在异物。信号A与信号B可以为具有显著可识别差异的数字信号或可被***其他部分识别的具有显著可识别差异的模拟信号，例如，信号A为低电平或零电平，信号B为高电平。可选地，还可以包括控制无线充电***工作的开关，通过识别信号B来关断无线充电***的正常工作以防止意外发生；还可以包括报警器，用于处理器204判断出存在异物时报警，通过识别不同信号而做出不同的物理动作，提醒使用者注意异物入侵。在没有异物入侵时，信号A被报警器识别，报警器不予反应。在有异物入侵时，信号B被报警器识别，报警器做出物理反应，例如包括LED灯的报警器，LED灯闪亮；包括蜂鸣器的报警器，蜂鸣器发出声音。以此提示使用者有金属异物入侵。
应需理解的是，每组检测线圈中的每匝线圈所围合区域的面积是实质相同的。当置于所述时变磁场时，若所述时变磁场为均匀磁场，则每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量是相同的；若虽然每组检测线圈中每匝线圈的面积相同，但所述时变磁场为非均匀磁场，或者，若所述时变磁场虽然为均匀磁场，但每组检测线圈中的每匝线圈所围合的区域的面积有差异，(例如，首尾两匝线圈在所述时变磁场中磁通量的变化量可能由于线圈所处位置的不同，存在一定的差别)，则每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量有一定的差别。但是由于每组线圈的每匝线圈之间的匝间距较小，而且实际中激励线圈产生的磁场可以近似认为是均匀的，且每匝线圈的所围合的区域的面积可以认为是是实质相同的，因此每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量的差别较小。也就是说，每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量可以认为是相同的。在实际计算时，可以采用每组检测线圈中各匝线圈在所述时变磁场中磁通量的变化量的平均值来计算每组检测线圈的感应电压，也可以采用每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量计算每组线圈的感应电压，可以理解的是，凡是能够利用每组检测线圈中各匝线圈在所述时变磁场中的磁通量的变化量计算感应电压的方式均适用于本申请实施例。
下述为本申请的方法实施例。
本申请实施例二提供一种异物检测方法，如图4所示为该异物检测方法步骤示意图，所述方法包括如下步骤：
S401：处理器采集第一组检测线圈的电压U1和第二组检测线圈的电压U2；
S402：处理器计算第一组检测线圈的电压U1和第二组检测线圈的电压大小U2是否相等，若不相等，则判断存在异物；
S403：处理器根据检测结果，发出不同的信号，若第一组检测线圈的电压和第二组检测线圈的电压大小相等，处理器输出信号A，若第一组检测线圈的电压和第二组检测线圈的电压大小不相等，处理器输出信号B。
在一种可选地实现方式中，还可以包括S404：
报警器识别信号A时不予反应，识别信号B时报警，例如，包括LED灯的报警器，LED灯闪亮；包括蜂鸣器的报警器，蜂鸣器发出声音。或者，控制无线充电***工作的开关，识别信号B时关断无线充电***的正常工作，以防止意外发生。
当实施例一所述的无线充电异物检测装置所工作的***中异物面积较大时，上述提及的所述异物检测装置会存在检测盲区。本申请实施例三提供一种异物检测装置，可以实现盲区检测。
现以实施例一中第一组检测线圈201和第二组检测线圈202组成的检测装置为例，说明检测盲区。根据公式：
Figure PCTCN2020081273-appb-000013
已知无异物时的两组检测线圈的感应电压|E1|＝|E2|，因此有(N 1*S 1)＝(N 2*S 2)
如图5所示为检测盲区示意图，当金属异物504横跨第一组检测线圈501时，其在激励线圈503磁场中产生的涡流反磁场，一部分落于第一组检测线圈501内部，设其在第一组检测线圈501中单匝线圈上产生的感应电压为ΔU1，在第二组502检测线圈中单匝线圈上产生的感应电压为ΔU1`；一部分落于第一组检测线圈501外部，该部分在第一组检测线圈501上 不产生感应电压，设其在第二组检测线圈502中单匝线圈上产生的感应电压为ΔU2。所述异物中涡流产生的磁场在第一组检测线圈上产生的感应电压实际上是落入第一组线圈501内部部分的异物涡流磁场产生的感应电压，所述异物中涡流产生的磁场在第二组检测线圈上产生的感应电压实际上是整个处于第二组检测线圈内部的异物涡流磁场产生的感应电压，则两线圈的感应电压分别为：
U1＝N1*ΔU1
U2＝N 2*(ΔU1`+ΔU2)
因为S 2>S 1，故有N 2<N1，而ΔU1、ΔU1`和ΔU2均由涡流反磁场产生，由于激励线圈产生的高频磁场在两组检测线圈中的磁感应强度大小近似均匀，在某一频率下，两组检测线圈内磁感应强度随时间的变化近似相同的磁场中，单匝线圈感应电动势的大小仅取决于时变磁场穿过闭合回路的面积。由于处于第一组线圈内部的异物部分同时也处于第二组线圈内部，因此该部分异物在第一组线圈和第二组线圈中单匝线圈感应的电压是相等的，即|ΔU1`|＝|ΔU1|，因此，|(ΔU1`+ΔU2)|>|ΔU1|，此时若存在某个异物，横跨N2线圈并使得ΔU1和ΔU2满足：
|N 2*(ΔU1`+ΔU2)|＝|N1*ΔU1|
则该异物入侵前后，两线圈的感应电压的大小仍然保持相等，处理器不会因为异物的入侵而产生与无异物状态时不同的信号，因此可能存在这种异物的区域为检测盲区505，如图5阴影部分所示。
应需理解的是，上述内容仅是为了便于理解检测进行的说明，在实际应用中由于异物产生的磁场并不一定是均匀的，所述第一组检测线圈和第二组检测线圈在所述异物产生的磁场中形成感应电动势的计算更为复杂，但对于所述检测，可以确定当所述异物横跨在所述第一组检测线圈上，被所述第一组线圈分成两部分时，有较大可能产生检测盲区。
如图6所示，为本申请实施例三提供的一种异物检测装置结构示意图，所述异物检测装置包括第一组检测线圈601、第二组检测线圈602、第三组检测线圈603、激励线圈604和处理器605。其中第一组检测线圈、第二组检测线圈、第三组检测线圈和激励线圈共同组成了一个检测单元，所述检测单元如图7所示，包括了第一组检测线圈601、第二组检测线圈602、第三组检测线圈603和激励线圈604。可以理解的是，本实施例所述的异物检测装置还可以包括多于三组检测线圈的异物检测装置，其构造和检测原理与包含三组检测线圈的异物检测装置的实现方式类似，在此不再赘述。
在一种可能的实现方式中，第一组检测线圈201、第二组检测线圈202和激励线圈203各自的正投均为一个平面线圈，且它们各自的正投影位于同一平面内。在一种可能的实现方式中，第一组检测线圈201、第二组检测线圈202和激励线圈203本身位于同一平面内。在另一种可能的实现方式中，第一组检测线圈201、第二组检测线圈202和激励线圈203本身不位于同一平面内，或者说，第一组检测线圈201、第二组检测线圈202和激励线圈203中的至少一个线圈与其他的线圈相对于投影平面的距离是不相等的。
可选的，第一组检测线圈601、第二组检测线圈602与第三组检测线圈603均为平面线圈，且所述第一组检测线圈601、第二组检测线圈602与第三组检测线圈603位于同一平面内。所述第一组检测线圈601、第二组检测线圈602与第三组检测线圈603均包括多匝线圈，每一组所述检测线圈的所述多匝线圈是同轴的。线圈形状可以为长方形、圆形或多边形，本申请实施例在此不做限制。第一组检测线圈601位于第二组检测线圈602的内侧，第二组检测线圈602位于第三组检测线圈603的内侧，即第一组检测线圈601是最内侧线圈组，第二组602检测线圈为中间线圈组，第三组检测线圈603为最外侧线圈组。第一组检测线圈601、 第二组检测线圈602和第三组检测线圈603均位于激励线圈604内侧。或者说，第一组检测线圈601被第二组检测线圈602完全包围，第二组检测线圈602被第三组检测线圈603完全包围，第一组检测线圈601、第二组检测线圈602和第三组检测线圈603被激励线圈604完全包围。其中，所述内侧的第一组检测线圈、所述中间的第二组检测线圈和所述外侧的第三组检测线圈两两之间彼此隔开。
激励线圈604连接正弦激励输入电流，用于提供时变磁场，该时变磁场对于第一组检测线圈601、第二组检测线圈602和第三组检测线圈603来说是来说是实质均匀的。所述实质均匀应当以本领域技术人员的理解为准，比如上下浮动5％。
需要说明的是，所述用于产生时变磁场的激励线圈，作为独立设置的检测线圈的磁场激励源，其中，所述检测线圈包括第一组检测线圈、第二组检测线圈和第三组检测线圈。这样独立设置的磁场激励源可以排除无线充电***中的***干扰，进一步保证所述检测线圈能够准确的检测到异物。可选地，所述激励线圈604也可以是所述无线充电***中的发射线圈，这样可以进一步节约成本，使得所述检测线圈可以应用于多种无线充电***中，方便、快捷地检测异物。
第一组检测线圈601和第三组检测线圈603形成第一线圈对6001，第二组检测线圈602和第三组检测线圈603形成第二线圈对6002，所述第一线圈对和所述第二线圈对结合，用于检测无线充电发射装置和接收装置之间是否存在异物并消除检测盲区。激励线圈内流过与无线充电***的工作频率不同频率的电流，例如，激励线圈使用6.78MHz高频正弦电流，与无线充电***的85kHz频率错开，便于处理器滤波。
第一组检测线圈601和第三组检测线圈603满足如下公式：
Figure PCTCN2020081273-appb-000014
第二组检测线圈602和第三组检测线圈603满足如下公式：
Figure PCTCN2020081273-appb-000015
其中，N1为所述第一组检测线圈601中的线圈匝数，N2为所述第二组检测线圈602的线圈匝数，N3为所述第三组检测线圈的603线圈匝数；φ 1为穿过第一组检测线圈601中单匝线圈的磁通量，φ 2为穿过第二组检测线圈602中单匝线圈的磁通量，φ 3为穿过第三组检测线圈603中单匝线圈的磁通量，t为时间，
Figure PCTCN2020081273-appb-000016
为穿过第一组检测线圈601中单匝线圈的磁通量随时间的变化率，
Figure PCTCN2020081273-appb-000017
为穿过第二组检测线圈602中单匝线圈的磁通量随时间的变化率，
Figure PCTCN2020081273-appb-000018
为穿过第三组检测线圈603中单匝线圈的磁通量随时间的变化率；dφ 1是根据所述时变磁场的磁感应强度以及所述第一组检测线圈601中任一匝线圈所围合的区域的面积确定的，dφ 2是根据所述时变磁场的磁感应强度以及所述第二组检测线圈602中任一匝线圈所围合的区域的面积的确定的，dφ 3是根据所述时变磁场的磁感应强度以及所述第三组检测线圈603中任一匝线圈所围合的区域的面积的确定的。
将第一组检测线圈601、第二组检测线圈602和第三组检测线圈603置于在两线圈所在平面处处均匀的时变磁场中，由法拉第电磁感应原理可知，高频时变磁场将在闭合回路中感应出电动势E：
Figure PCTCN2020081273-appb-000019
由于感应电动势方向取决于穿过闭合环路的磁场的环路积分，因此不同绕向的线圈将感应出正负不同的电动势。由于激励线圈产生的高频磁场在三组检测线圈中的磁感应强度B大小近似均匀，因此在某一频率下，三组检测线圈内磁感应强度B随时间的变化近似相同，所以感应电动势E的大小仅取决于时变磁场穿过闭合回路的面积S和闭合回路线圈的匝数N。
针对每组检测线圈，每组检测线圈的感应电动势与改组检测线圈的线圈匝数以及该组检测线圈中任一匝线圈的磁通量变化率有关。例如，第一组检测线圈的感应电动势与第一组检测线圈的线圈匝数以及第一组检测线圈中每一匝线圈的磁通量变化率有关。
每一匝线圈的所述磁通量与所述时变磁场的磁感应强度和该匝线圈所围合的区域的面积有关。例如，第一匝线圈的磁通量与所述时变磁场的磁感应强度和所述第一匝线圈所围合的区域的面积有关。
第一组检测线圈601、第二组检测线圈602和第三组检测线圈603的匝数不同，面积也不同。通过调整线圈的绕向，可调整三组线圈的感应电动势方向。在无异物的正常情况时，通过调整线圈匝数或/和线圈所围合的区域的面积，在所述第一线圈对6001中，面积小的第一组检测线圈601匝数多，面积大的第三组检测线圈603匝数少；在所述第二线圈对6002中，面积小的第二组检测线圈602匝数多，面积大的第三组检测线圈603匝数少。当调整第一组检测线圈601的匝数与第一组检测线圈601所围合的面积的乘积等于第三组检测线圈603的匝数与第三组检测线圈603所围合的面积的乘积时，可以使得第一组检测线圈是601在所述时变磁场中产生的感应电动势和第三组检测线圈603在所述时变磁场中产生的感应电动势数值大小相等；当调整第二组检测线圈602的匝数与第二组检测线圈602所围合的面积的乘积等于第三组检测线圈603的匝数与第三组检测线圈603所围合的面积的乘积时，可以使得第二组检测线圈602在所述时变磁场中产生的感应电动势和第三组检测线圈603在所述时变磁场中产生的感应电动势数值大小相等。第一组检测线圈601和第三组检测线圈603，进一步地，满足如下公式：
Figure PCTCN2020081273-appb-000020
第二组检测线圈602和第三组检测线圈603，进一步地，满足如下公式：
Figure PCTCN2020081273-appb-000021
其中，N1为所述第一组线圈的线圈匝数，N2为所述第二组线圈的线圈匝数，N3为所述第三组线圈的线圈匝数；S1为所述第一组检测线圈中任一匝线圈所围合的区域的面积，S2为所述第二组检测线圈的中任一线圈所围合的区域的面积，S3为所述第三组检测线圈中任一匝线圈所围合的区域的面积；B为磁感应强度，t为时间，
Figure PCTCN2020081273-appb-000022
为磁感应强度随时间的变化率。由于激励线圈产生的高频磁场在第一组检测线圈、第二组检测线圈和第三组检测线圈中的磁感应强度大小近似均匀，在相同频率的交流激励下，第一组检测线圈、第二组检测线圈和第三组检测线圈内磁感应强度随时间的变化率
Figure PCTCN2020081273-appb-000023
近似相同。即第一组检测线圈的匝数与面积的乘积和第三组检测线圈的匝数与面积的乘积相等，第二组检测线圈的匝数与面积的乘积和第三组检测线圈的匝数与面积的乘积相等。异物的存在会使感应磁场发生畸变，例如，金属异物在时变磁场中也会被感应出感应电动势，该电动势会在金属异物内部产生闭合回路电流， 即涡流，涡流可产生磁场，涡流产生的磁场方向与原时变磁场相反，称为涡流反磁场。生物体异物同样会使得时变磁场产生畸变。
在一种可能的实现方式中，金属异物产生的涡流反磁场会在第一组检测线圈、第二组检测线圈和第三组检测线圈上产生感应电动势。第一组检测线圈上感应电动势产生的电压为U1，第二组检测线圈上感应电动势产生的电压为U2，第三组检测线圈上感应电动势产生的电压为U3。
金属异物侵入无线充电***中时，当金属侵入第一组检测线圈内部时，由于穿过面积小的第一组检测线圈的涡流反磁场必然穿过包围第一组检测线圈的第三组检测线圈，因此得到：
U1＝ΔU*N1
U3＝ΔU*N3
同理，由于穿过面积小的第二组检测线圈的涡流反磁场必然穿过包围第二组检测线圈的第三组检测线圈，因此得到：
U2＝ΔU*N2
U3＝ΔU*N3
式中ΔU为单匝线圈受涡流反磁场影响而产生的电压，所述单匝线圈为任何能够完全包围异物产生的涡流反磁场的闭合线圈，其中，位于第一组检测线圈内部的异物所产生的磁场被第一组检测线圈完全包围，同时也被第三组检测线圈完全包围；位于第二组检测线圈内部的异物所产生的磁场被第二组检测线圈完全包围，同时也被第三组检测线圈完全包围。N1、N2、N3分别为第一组检测线圈、第二组检测线圈、第三组检测线圈的匝数。由于第一组检测线圈的匝数N1和第三组检测线圈的匝数N3不相等，所以第一组检测线圈上感应出的电压U1和第三组检测线圈上感应出的电压U3不相等；由于第二组检测线圈的匝数N2和第三组检测线圈的匝数N3不相等，所以第二组检测线圈上感应出的电压U2和第三组检测线圈上感应出的电压U3不相等。
当金属侵入第一组检测线圈和第三组检测线圈所夹区域时，由于该区域在第一组检测线圈外部，在第三组检测线圈内部，因此可以近似认为涡流反磁场仅穿过第三组检测线圈，不穿过第一组检测线圈，因此得到：
U1＝0
U3＝ΔU*N3
所以第一组检测线圈上感应出的电压U1和第三组检测线圈上感应出的电压U3不相等；
当金属侵入第二组检测线圈和第三组检测线圈所夹区域时，由于该区域在第二组检测线圈外部，在第三组检测线圈内部，因此可以近似认为涡流反磁场仅穿过第三组检测线圈，不穿过第二组检测线圈，因此得到：
U2＝0
U3＝ΔU*N3
所以第二组检测线圈上感应出的电压U2和第三组检测线圈上感应出的电压U3不相等。
因此，当金属异物落入面积较大的第三组检测线圈内部的检测区域时，所述第一组检测线圈和所述第三组检测线圈在无金属异物时电压大小相同，有金属异物时电压大小不同；所述第二组检测线圈和所述第三组检测线圈在无金属异物时电压大小相同，有金属异物时电压大小不同。因此可将第一组检测线圈和第三组检测线圈的电压是否相等，或者，第二组检测 线圈和第三组检测线圈的电压是否相等，作为金属异物入侵的判断依据。
由于第一组检测线圈和第三组检测线圈组成的第一线圈对的检测盲区位于第一线圈附近，而第二组检测线圈和第三组检测线圈组成的第二线圈对的检测盲区位于第二线圈附近，第一线圈对和第二线圈对的检测盲区并不重合，因此第一线圈对和第二线圈对的结合可以有效消除仅有两组检测线圈时产生的检测盲区问题。
处理器605用于判断第一线圈对的所述第一组检测线圈在所述时变磁场中产生的感应电压U1和所述第三组检测线圈在所述时变磁场中产生的感应电压U3数值大小是否相等，或者，判断第二线圈对的所述第二组检测线圈在所述时变磁场中产生的感应电压U2和所述第三组检测线圈在所述时变磁场中产生的感应电压U3数值大小是否相等，并基于结果判定是否存在异物。第一线圈对和第二线圈对任一线圈对的结果不相等则判定存在异物。处理605内可以包括滤波单元、计算单元、放大单元和比较单元。滤波单元用于筛选出激励频率分量；计算单元用于将电压信号进行计算，放大单元用于将计算后输出的信号放大到易于分辨的大小，比较单元用于比较前级输出和设定阈值，根据比较结果输出不同的信号，例如，高电平信号和低电平信号。可以理解的是，所述处理器内部的结构不受限制，所有能够实现电压信号处理并比较出U1与U3数值关系，或者，U2与U3数值关系的器件、模块或单元，都属于本申请所述的处理器。
在一种可能的实现方式中，处理器605采集线圈电压U1和U3，将U1和U3作为信号源，U1和U3大小相等方向相反。经过一系列滤波、放大、加法等方式处理信号，U1与U3相加后为零，处理器605输出信号A，表明无线充电***中不存在异物，在电压U1和U3大小不相等时，U1与U3相加后不为零，处理器605输出信号B，表明无线充电***中存在异物。信号A与信号B可以为具有显著可识别差异的数字信号或可被***其他部分识别的具有显著可识别差异的模拟信号，例如，信号A为低电平或零电平，信号B为高电平。可选地，还可以包括控制无线充电***工作的开关，通过识别信号B来关断无线充电***的正常工作以防止意外发生；还可以包括报警器，用于处理器605判断出存在异物时报警，通过识别不同信号而做出不同的物理动作，提醒使用者注意异物入侵。在没有异物入侵时，信号A被报警器识别，报警器不予反应。在有异物入侵时，信号B被报警器识别，报警器做出物理反应，例如包括LED灯的报警器，LED灯闪亮；包括蜂鸣器的报警器，蜂鸣器发出声音。以此提示使用者有金属异物入侵。
在另一种可能的实现方式中，处理器605采集线圈电压U2和U3，将U2和U3作为信号源，U2和U3大小相等方向相同。经过一系列滤波、放大、减法等处理，U2与U3相减后为零，处理器605输出信号A，表明无线充电***中不存在异物，在电压U2与U3大小不相等时，U2与U3相减后不为零，处理器605输出信号B，表明无线充电***中存在异物。信号A与信号B可以为具有显著可识别差异的数字信号或可被***其他部分识别的具有显著可识别差异的模拟信号，例如，信号A为低电平或零电平，信号B为高电平。可选地，还可以包括控制无线充电***工作的开关，通过识别信号B来关断无线充电***的正常工作以防止意外发生；还可以包括报警器，用于处理器605判断出存在异物时报警，通过识别不同信号而做出不同的物理动作，提醒使用者注意异物入侵。在没有异物入侵时，信号A被报警器识别，报警器不予反应。在有异物入侵时，信号B被报警器识别，报警器做出物理反应，例如包括 LED灯的报警器，LED灯闪亮；包括蜂鸣器的报警器，蜂鸣器发出声音。以此提示使用者有金属异物入侵。
因此，在出现金属异物后，若异物不处于某线圈对的检测盲区，则两线圈对中任一线圈对均会触发报警器报警，若异物处于某线圈对的检测盲区，则另一线圈对会触发报警器报警，因此，任一线圈对检测出异物，即可判定无线充电***中有异物出现。
应需理解的是，每组检测线圈中的每匝线圈所围合区域的面积是实质相同的。当置于所述时变磁场时，若所述时变磁场为均匀磁场，则每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量是相同的；若虽然每组检测线圈中每匝线圈的面积相同，但所述时变磁场为非均匀磁场，或者，若所述时变磁场虽然为均匀磁场，但每组检测线圈中的每匝线圈所围合的区域的面积有差异，(例如，首尾两匝线圈在所述时变磁场中磁通量的变化量可能由于线圈所处位置的不同，存在一定的差别)，则每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量有一定的差别。但是由于每组线圈的每匝线圈之间的匝间距较小，而且实际中激励线圈产生的磁场可以近似认为是均匀的，且每匝线圈的所围合区域的面积可以认为是是实质相同的，因此每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量的差别较小。也就是说，每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量可以认为是相同的。在实际计算时，可以采用每组检测线圈中各匝线圈在所述时变磁场中磁通量的变化量的平均值来计算每组检测线圈的感应电压，也可以采用每组检测线圈中任一匝线圈在所述时变磁场中磁通量的变化量计算每组线圈的感应电压，可以理解的是，凡是能够利用每组检测线圈中各匝线圈在所述时变磁场中的磁通量的变化量计算感应电压的方式均适用于本申请实施例。
本申请实施例四提供一种异物检测方法，如图8所示为该异物检测方法步骤示意图，所述方法包括如下步骤：
S801：处理器采集第一组检测线圈的电压U1、第二组检测线圈的电压U2和第三组检测线圈的电压U3；
S802：处理器计算第一组检测线圈的电压U1和第三组检测线圈的电压U3大小是否相等，若不相等，则判断存在异物，若相等，计算第二组检测线圈的电压U2和第三组检测线圈的电压U3大小是否相等，若不相等，则判断存在异物；
S803：根据检测结果，发出不同的信号，若第一组检测线圈的电压U1和第三组检测线圈的电压大小U3相等，同时，第二组检测线圈的电压U2和第三组检测线圈的电压U3大小相等，处理器输出信号A；若第一组检测线圈的电压U1和第三组检测线圈的电压大小U3不相等，或者，第二组检测线圈的电压U2和第三组检测线圈的电压U3大小不相等，处理器输出信号B。
在一种可选地实现方式中，还可以包括S804：
报警器识别信号A时不予反应，识别信号B时报警，例如，包括LED灯的报警器，LED灯闪亮；包括蜂鸣器的报警器，蜂鸣器发出声音。或者，控制无线充电***工作的开关，识别信号B时关断无线充电***的正常工作，以防止意外发生。
可以理解的是，本实施例所述的异物检测装置还可以包括多于三组检测线圈的异物检测装置，其构造和检测原理与包含三组检测线圈的异物检测装置的实现方式类似。即上述实施例中第一组检测线圈为最内侧检测线圈的一种可能的实现方式，第二组检测线圈为中间任意 一组检测线圈的一种可能的实现方式，第三组检测线圈为最外侧检测线圈的一种可能的实现方式。在此不再赘述。
本申请实施例五提供一种异物检测装置，如图9所示，所述异物检测装置是将N个实施例三所述的异物检测装置的检测线圈901串联拼接后得到的，用于扩大检测面积。其具体实施方式和实施例二类似，在此不做赘述。
本申请实施例六提供一种异物检测***，该***包括实施例一或三或五所述的异物检测装置和充电***，所述无线充电异物检测装置用于检测所述充电***内是否具有异物，在此不再赘述。
以上所述，仅是本申请的较佳实施例而已，并非对本申请作任何形式上的限制。虽然本申请已以较佳实施例揭露如上，然而并非用以限定本申请。任何熟悉本领域的技术人员，在不脱离本申请技术方案范围情况下，都可利用上述揭示的方法和技术内容对本申请技术方案做出许多可能的变动和修饰，或修改为等同变化的等效实施例。因此，凡是未脱离本申请技术方案的内容，依据本申请的技术实质对以上实施例所做的任何简单修改、等同变化及修饰，均仍属于本申请技术方案保护的范围内。

Claims (17)

  1. 一种用于无线充电***的异物检测装置，其特征在于，所述检测装置包括激励线圈，检测线圈，处理器，其中：
    所述激励线圈用于提供时变磁场；
    所述检测线圈用于检测无线充电发射装置和接收装置之间是否存在异物；
    所述检测线圈包括第一组检测线圈和第二组检测线圈，所述第一组检测线圈、所述第二组检测线圈和所述激励线圈各自的正投影均为一个平面线圈，且它们各自的正投影位于同一平面内，且彼此隔离，其中，所述第二组检测线圈位于所述第一组检测线圈和所述激励线圈之间，所述第一组检测线圈位于所述第二组检测线圈的内侧，所述激励线圈位于所述第二组检测线圈的外侧；
    所述处理器用于判断所述第一组检测线圈在所述时变磁场中产生的感应电压值和所述第二组检测线圈在所述时变磁场中产生的感应电压值是否相等，结果不相等则判定存在异物。
  2. 根据权利要求1所述的检测装置，其特征在于，在所述时变磁场的目标区域内，磁场分布是实质均匀的，其中，所述时变磁场的目标区域是指所述第一组检测线圈和所述第二组检测线圈所位于的时变磁场的区域。
  3. 根据权利要求1所述的检测装置，其特征在于，所述第一组检测线圈的匝数与所述第一组检测线圈所围合的面积的乘积等于所述第二组检测线圈的匝数与所述第二组检测线圈所围合的面积的乘积。
  4. 根据权利要求1-3任一所述的检测装置，其特征在于，所述第一组检测线圈和所述第二组检测线圈的匝数不同。
  5. 根据权利要求1-3任一所述的检测装置，其特征在于，所述第一组检测线圈和所述第二组检测线圈均为平面线圈，且所述第一组检测线圈和所述第二组检测线圈位于同一平面内。
  6. 根据权利要求1-3任一所述的检测装置，其特征在于，所述第一组检测线圈和所述第二组检测线圈均包括多匝线圈，每一组所述检测线圈的所述多匝线圈是同轴的。
  7. 根据权利要求1-3任一所述的检测装置，其特征在于，还可以包括报警器，所述报警器用于在所述处理器判断出存在异物时报警。
  8. 一种用于无线充电***的异物检测装置，其特征在于，所述检测装置包括激励线圈，检测线圈，处理器和报警器，其中：
    所述激励线圈用于提供时变磁场；
    所述检测线圈用于检测无线充电发射装置和接收装置之间是否存在异物；
    所述检测线圈包括至少三组检测线圈，所述至少三组检测线圈中每一组检测线圈的正投影均为一个平面线圈，所述激励线圈的正投影也为一个平面线圈，且所述至少三组检测线圈中的每一组检测线圈的正投影以及所述激励线圈的正投影均位于同一平面内，且彼此隔离；
    所述至少三组检测线圈中每两组检测线圈形成一个线圈对，每一个线圈对用于消除检测盲区；
    所述处理器用于判断每一个线圈对的两组线圈在所述时变磁场中产生的感应电压值是否相等，结果不相等则判定存在异物。
  9. 根据权利要求8所述的检测装置，其特征在于，在所述时变磁场的目标区域内，磁场分布是实质均匀的，其中，所述时变磁场的目标区域是指所述至少三组检测线圈所位于的时变磁场的区域。
  10. 根据权利要求8所述的检测装置，其特征在于，位于每一线圈对内的其中一组检测 线圈所围合的面积与所述其中一组检测线圈的匝数的乘积等于另一组检测线圈所围合的面积与所述另一组检测线圈的匝数的乘积。
  11. 根据权利要求8-10任一所述的检测装置，其特征在于，所述至少三组检测线圈中每两匝检测线圈的匝数不同。
  12. 根据权利要求8-10任一所述的检测装置，其特征在于，所述至少三组检测线圈均为平面线圈，且所述至少三组检测线圈位于同一平面内。
  13. 根据权利要求8-10任一所述的检测装置，其特征在于，所述至少三组检测线圈，均包括多匝线圈，每一组所述检测线圈的所述多匝线圈是同轴的。
  14. 根据权利要求8-10任一所述的检测装置，其特征在于，还可以包括报警器，所述报警器用于在所述处理器判断出存在异物时报警。
  15. 一种无线充电异物检测***，其特征在于，所述无线充电异物检测***包括权利要求1-7或8-14所述的无线充电异物检测装置和充电***，所述无线充电异物检测装置用于检测所述充电***内是否具有异物。
  16. 一种用于无线充电***的异物检测方法，其特征在于，包括：
    采集第一组检测线圈在激励线圈产生的时变磁场中感应的电压和第二组检测线圈在激励线圈产生的时变磁场中感应的电压；
    判断第一组检测线圈在所述时变磁场中感应的电压和第二组检测线圈在所述时变磁场中产生的感应电压数值是否相等，若不相等，则判定存在异物。
  17. 一种用于无线充电***的异物检测方法，其特征在于，包括：
    采集至少三组检测线圈在激励线圈产生的时变磁场中感应的电压，其中：所述至少三组检测线圈中任意两组检测线圈形成一个线圈对；
    判断任一线圈对的两组线圈在所述时变磁场中产生的感应电压数值是否相等，若不相等，则判定存在异物。
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