CN210011609U - Wireless charging metal foreign matter detection device - Google Patents

Wireless charging metal foreign matter detection device Download PDF

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Publication number
CN210011609U
CN210011609U CN201920968379.3U CN201920968379U CN210011609U CN 210011609 U CN210011609 U CN 210011609U CN 201920968379 U CN201920968379 U CN 201920968379U CN 210011609 U CN210011609 U CN 210011609U
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surface acoustic
acoustic wave
piezoelectric substrate
wireless charging
output
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王哲
陆钧
贺凡波
葛俊杰
马俊超
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Hefei Yougan Technology Co.,Ltd.
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Beijing Invispower Co Ltd
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    • 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

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Abstract

A wireless charging metal foreign object detection device, comprising: the surface acoustic wave detection device comprises a surface acoustic wave sampling unit, a piezoelectric substrate, a heat-conducting adhesive layer, a sound-absorbing material layer, a high-frequency generation circuit, a temperature sensor, a circulating acquisition circuit and a surface acoustic wave detection circuit; the surface acoustic wave sampling unit is arranged above the piezoelectric substrate and used for sampling the temperature of an upper shell of the transmitting coil of the wireless charging system; the device and the detection method for finding the foreign matters by adding the piezoelectric substrate in the transmitting coil and exciting the surface acoustic wave to detect the temperature change solve the problem that the potential safety hazard is possibly caused by high temperature caused by the existence of the metal foreign matters on the wireless charging transmitting coil, have strong anti-interference performance and can improve the safety of the wireless charging work of the electric automobile.

Description

Wireless charging metal foreign matter detection device
Technical Field
The utility model belongs to the technical field of the wireless charging technique of electric automobile and specifically relates to a wireless metal foreign matter detection device that charges.
Background
With the continuous consumption of fossil energy and the continuous aggravation of environmental pollution, the new energy automobile industry is greatly supported by governments of various countries and is in a stage of high-speed development. The wireless charging of the electric automobile has the advantages of safety, convenience, automation and the like, and becomes a hotspot of the research and development of the charging technology. However, the wireless charging transmitting coil of the electric automobile is generally installed on an outdoor parking space, various metal foreign matters such as coins, pop-top cans and iron nails can appear on the surface of the wireless charging transmitting coil at any time, and the metal foreign matters can generate heat due to the eddy current effect during wireless charging, so that the transmission efficiency of wireless charging is greatly reduced, and meanwhile, surrounding inflammable matters can be ignited to cause safety accidents. Therefore, a set of metal foreign matter detection equipment must be configured in the wireless charging system, and the charging safety is guaranteed.
The wireless charging of electric automobile can adopt following several kinds of modes to carry out the metal foreign matter and detect, include:
① monitoring the surface image of the transmitting coil, finding out the foreign body by image monitoring;
the image vision detection method has the problems that the image vision detection method is possibly interfered by external factors such as light rays and the like, and the image vision detection method is clean, so that false alarm is generated or alarm cannot be given in time;
②, detecting the change of parameters such as impedance under the working magnetic field by using an auxiliary detection coil array;
the auxiliary coil is adopted, and the problems of sensitivity, accuracy, interference resistance and the like of detection exist due to the influence of a strong magnetic field on a detection system component during wireless charging. Small-size metal foreign matter is because parameter variation is less under magnetic field, and the border of detecting coil has the overlap each other in the coil array, often can have the blind area that metal foreign matter detected.
③ adopting temperature sensor to sample the temperature of transmitting end;
the temperature sensor can only measure the temperature of a certain contact point, and if the whole end face of a transmitting coil is sampled, a large number of sensors are required to form an array. The probe and the outgoing line of the temperature sensor are generally made of metal materials, the sensor can be damaged due to the eddy current effect in the wireless charging transmission process, energy transmission is damaged, and the detection mode can easily generate a monitoring blind area.
④ adopts infrared temperature measurement monitoring and alarm detection technology;
the infrared temperature measurement can receive the external interference of ambient light etc. equally, and the surface has the reflection of light when metal object measures, can influence the detection among the practical application, can not guarantee wireless whole safety of charging. The whole end face of one transmitting coil is sampled by adopting infrared temperature measurement, so that the problem of high cost exists, and the infrared temperature measurement is frequently used in experimental tests.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides a wireless metallic foreign matter detection device that charges through increase the piezoelectricity base plate in transmitting coil, the excitation surface acoustic wave detects the temperature variation to discovery metallic foreign matter's device has solved and has had the metallic foreign matter to cause the problem that the high temperature probably causes the potential safety hazard on the wireless transmitting coil that charges, and interference immunity is strong moreover, can improve the security of the wireless work of charging of electric automobile.
A wireless charging metal foreign object detection device, comprising: the surface acoustic wave detection device comprises a surface acoustic wave sampling unit, a piezoelectric substrate, a heat-conducting adhesive layer, a sound-absorbing material layer, a high-frequency generation circuit, a temperature sensor, a circulating acquisition circuit and a surface acoustic wave detection circuit; the surface acoustic wave sampling unit is arranged above the piezoelectric substrate and used for sampling the temperature of an upper shell of the transmitting coil of the wireless charging system; one end of the surface acoustic wave sampling unit is electrically connected with one end of the circulating acquisition circuit, and the other end of the circulating acquisition circuit is electrically connected with one end of the surface acoustic wave detection circuit; the other end of the surface acoustic wave sampling unit is electrically connected with one end of the high-frequency generating circuit;
furthermore, in order to achieve the purpose of detecting foreign matters, the piezoelectric substrate is packaged above a wire coil of the transmitting coil and at the lower part of the upper shell; a layer of heat-conducting adhesive layer is filled between the piezoelectric substrate and the upper shell to serve as a buffer layer, so that the pressure transmitted to the piezoelectric material when foreign matters appear above the upper shell is reduced;
as an example, the piezoelectric substrate is made of a piezoelectric material;
further, the surface acoustic wave sampling unit includes: the array comprises a plurality of groups of input interdigital transducers, a plurality of groups of output interdigital transducers, input electrodes and output electrodes; the multiple groups of input interdigital transducers are arranged on the left side of the piezoelectric substrate in a side-by-side adjacent manner, and the multiple groups of output interdigital transducers are arranged on the right side of the piezoelectric substrate in a side-by-side adjacent manner; the input interdigital transducer is used for receiving surface acoustic waves; the output interdigital transducer is used for generating surface acoustic waves; the input electrodes are used for inputting alternating voltages to the multiple groups of input interdigital transducers; the output electrodes are electrically connected with the multiple groups of output interdigital transducers and used for outputting electric signals;
by way of illustration, the input interdigital transducer comprises: the two input interdigital electrodes are opposite in a crossed mode and are not in contact with each other, and each group of input interdigital electrodes are identical in size and shape;
as a preferable example, the input interdigital electrode employs a structure in which a plurality of electrode teeth are vertically arranged on a bus bar, that is, a wooden comb-like structure;
by way of illustration, the output interdigital transducer comprises: the two output interdigital electrodes are opposite in a crossed manner and are not in contact with each other, and each group of output interdigital electrodes are consistent in size and shape;
as a preferable example, the output interdigital electrode employs a structure in which a plurality of electrode teeth are vertically arranged on a bus bar, that is, a wooden comb-like structure;
as an example, the input and output interdigital electrodes are manufactured by metal deposition by adopting a semiconductor integrated circuit process;
for one illustration, the input interdigital transducer and the output interdigital transducer are consistent in size and structure;
as an example, the input electrode and the output electrode are both an ac two-wire lead mechanism, which is equivalent to having two connectors of a zero line and a live line;
furthermore, a plurality of groups of input interdigital transducers on the left side of the piezoelectric substrate are used as input transducers, and when an alternating voltage is applied to the input electrodes of each group of input interdigital transducers, a potential difference is formed between the two input interdigital electrodes; under the action of an electric field formed by the potential difference, strain is generated on the surface of the piezoelectric substrate due to the inverse piezoelectric effect, so that the piezoelectric substrate material is stretched or shrunk, the direction of the electric field is influenced by alternating voltage and can generate periodic alternating change, so that the surface of the piezoelectric substrate generates periodic alternating deformation of 'shrinkage-stretching-shrinkage', and the surface deformation can excite a surface acoustic wave and diffuse to the left side and the right side along the surface of the piezoelectric substrate;
furthermore, each pair of input interdigital electrodes of the multiple groups of input interdigital transducers can excite surface acoustic waves, and the surface acoustic waves excited by the multiple groups of input interdigital electrodes at the same time can be mutually superposed, so that higher fluctuation energy can be obtained;
as one principle for example, the oscillation frequency inherent to the surface acoustic wave is determined by the width, length, and pitch of the input interdigital electrodes of the input interdigital transducer; the temperature and the stress, the rigidity, the mass density and other factors of the substrate material are influenced to change in real time; under the condition that the width, the length and the spacing of the input interdigital electrodes and the rigidity and the density of the piezoelectric substrate are not changed, the change of the temperature can be detected by sensing the change of the oscillation frequency;
further, the temperature T of the surface acoustic wave and the oscillation frequency f (T) have the following relationship:
F(T)＝f(T0)*[1+b0*(T-T0)+b1*(T-T0)2+…bn*(T-T0)n+1]
in the formula T0Measured by the temperature sensor is the air temperature, i.e. the ambient temperature. Temperature coefficient b in the formula0～bnDepending on the material, the first order temperature coefficient b of the piezoelectric substrate is determined when the piezoelectric substrate is made of a material such as quartz0Higher, and second order b1To n-th order temperatureCoefficient bnAnd the temperature change of the surface acoustic wave and the oscillation frequency are basically linear.
Furthermore, multiple groups of output interdigital transducers on the right side of the piezoelectric substrate are used as output transducers and used for receiving surface acoustic waves transmitted to the right side, and due to the positive piezoelectric effect caused by the deformation of the piezoelectric substrate, a high-frequency electric field can be generated in each group of output interdigital transducers in an excitation mode, so that high-frequency alternating current electric field signals can be output on the output electrodes; two joints of each group of output electrodes are connected in parallel with each other and then are respectively electrically connected with one end of the circulating acquisition circuit;
furthermore, sound absorbing material layers are arranged on the periphery and the top end of the piezoelectric substrate, and stray sound waves which are transmitted to the left side edge and the right side and penetrate through the output interdigital transducer to overflow can be absorbed by the sound absorbing material layers, so that interference caused by echo is avoided.
Further, the surface acoustic wave detection circuit includes: a low pass filter, a switching amplifier and a controller; the surface acoustic wave detection circuit is used for receiving the signals acquired by the circulating acquisition circuit and filtering, amplifying and processing the signals;
furthermore, the circulating acquisition circuit is used for acquiring a high-frequency alternating-current electric field signal sampled by the surface acoustic wave sampling unit;
for better explanation of the working principle of the present invention, the principle design is briefly explained as follows:
because of the existence of the metal foreign bodies, the eddy current heating phenomenon is generated, the temperature of the local area on the piezoelectric substrate is changed, the oscillation frequency of the surface acoustic wave of the local area on the piezoelectric substrate influenced by the temperature is changed, and the abnormality of the oscillation frequency of certain channels can be found by comparing the acquired oscillation frequency values measured by different channels with the parameters of each channel;
the set value of the detection temperature is determined according to relevant national specifications or higher product requirements, namely, the temperature of the maximum allowable limit value of the metal foreign matter heating is transmitted to the piezoelectric substrate through the upper shell to serve as the temperature value of the detection setting.
As an example, the input and output interdigital transducers are manufactured by a semiconductor integrated circuit process, the size of the input and output interdigital transducers and a correspondingly generated surface acoustic wave detection channel are in millimeter level, and small-size metal foreign bodies like a paper clip and the like can be detected;
as an illustration, a transmitting coil for generating a magnetic field in wireless charging power transfer includes: the device comprises an upper shell, a transmitting coil wire coil, a magnetic shielding material and a lower shell; wherein, the shell for installing the transmitting coil wire coil inside is generally made of non-metallic materials, and magnetic shielding materials are generally installed below the wire coil; the electric vehicle wireless charging system adopting magnetic coupling resonance comprises a power transmitting part and a power receiving part, wherein the power transmitting part utilizes the inductor and the capacitor of a receiving coil to be connected in series or in parallel to form an LC resonance circuit, a receiving circuit with the same resonance frequency is also formed at a receiving end, and wireless electric energy transmission can be realized through strong magnetic coupling formed by resonance between transmitting and receiving.
Has the advantages that:
the utility model discloses a detect piezoelectric substrate's surface acoustic wave to judge the temperature variation that the metallic foreign matter brought, what the surface acoustic wave utilized is the mechanical wave that is produced by the piezoelectric material surface of encapsulation in the coil inside, and the electromagnetic wave of production such as auxiliary coil, the interference of forceful electric magnetic field and external environment when having reduced wireless charging, thereby solved the reliability problem that current metallic foreign matter detected.
The metal foreign body is dangerous because of temperature rise, temperature measurement is the most direct and effective method for detecting the metal foreign body, the surface acoustic wave is very sensitive to temperature change, and high detection precision can be obtained through the surface acoustic wave.
Drawings
FIG. 1 is the utility model discloses a wireless metallic foreign matter detection device that charges's structural design sketch map
FIG. 2 is the circuit principle schematic diagram of the wireless charging metal foreign matter detection device
FIG. 3 is an example of a schematic diagram of a transmitting coil structure of a wireless charging device for detecting metallic foreign matter
Detailed Description
As shown in fig. 1 to 3, a wireless charging metal foreign object detection device includes: the acoustic surface wave detection device comprises a surface acoustic wave sampling unit 201, a piezoelectric substrate 101, a heat conducting adhesive layer 305, a sound absorption material layer 102, a high-frequency generation circuit 202, a temperature sensor 203, a circulation acquisition circuit 204 and a surface acoustic wave detection circuit 205; the surface acoustic wave sampling unit 201 is arranged above the piezoelectric substrate 101 and is used for sampling the temperature of an upper shell 301 of a transmitting coil of the wireless charging system; one end of the surface acoustic wave sampling unit 201 is electrically connected with one end of the cyclic acquisition circuit 204, and the other end of the cyclic acquisition circuit 204 is electrically connected with one end of the surface acoustic wave detection circuit 205; the other end of the surface acoustic wave sampling unit 201 is electrically connected with one end of the high-frequency generating circuit 202;
further, for the purpose of detecting foreign matters, the piezoelectric substrate 101 is packaged above the transmitting coil wire coil 302 and below the upper shell 301; a layer of heat-conducting adhesive layer 305 is filled between the piezoelectric substrate 101 and the upper shell 301 to serve as a buffer layer, so that pressure transmission to the piezoelectric material is reduced when foreign matters appear above the upper shell 301;
as an example, the piezoelectric substrate 101 is made of a piezoelectric material;
further, the surface acoustic wave sampling unit 201 includes: a plurality of sets of input interdigital transducers, a plurality of sets of output interdigital transducers, an input electrode 103 and an output electrode 104; the multiple groups of input interdigital transducers are arranged on the left side of the piezoelectric substrate 101 in a side-by-side adjacent manner, and the multiple groups of output interdigital transducers are arranged on the right side of the piezoelectric substrate 101 in a side-by-side adjacent manner; the input interdigital transducer is used for receiving surface acoustic waves; the output interdigital transducer is used for generating surface acoustic waves; the input electrodes 103 are used for inputting alternating voltages to the multiple groups of input interdigital transducers; the output electrodes 104 are electrically connected with the multiple groups of output interdigital transducers and used for outputting electric signals;
by way of illustration, the input interdigital transducer comprises: the two input interdigital electrodes are opposite in a crossed mode and are not in contact with each other, and each group of input interdigital electrodes are identical in size and shape;
as a preferable example, the input interdigital electrode employs a structure in which a plurality of electrode teeth 105 are vertically arranged on a bus bar 106, i.e., a wooden comb-like structure;
by way of illustration, the output interdigital transducer comprises: the two output interdigital electrodes are opposite in a crossed manner and are not in contact with each other, and each group of output interdigital electrodes are consistent in size and shape;
as a preferable example, the output interdigital electrode employs a structure in which a plurality of electrode teeth are vertically arranged on a bus bar, that is, a wooden comb-like structure;
as an example, the input and output interdigital electrodes are manufactured by metal deposition by adopting a semiconductor integrated circuit process;
for one illustration, the input interdigital transducer and the output interdigital transducer are consistent in size and structure;
as an example, the input electrode and the output electrode are both an ac two-wire lead mechanism, which is equivalent to having two connectors of a zero line and a live line;
furthermore, a plurality of groups of input interdigital transducers on the left side of the piezoelectric substrate 101 are used as input transducers, and when an alternating voltage is applied to the input electrodes of each group of input interdigital transducers, a potential difference is formed between the two input interdigital electrodes; under the action of an electric field formed by the potential difference, strain is generated on the surface of the piezoelectric substrate 101 due to the inverse piezoelectric effect, so that the material of the piezoelectric substrate 101 is stretched or contracted, and the direction of the electric field is influenced by alternating voltage to generate periodic alternating change, so that the surface of the piezoelectric substrate 101 generates periodic alternating deformation of 'contraction-stretching-contraction', and the surface deformation excites surface acoustic waves and diffuses to the left side and the right side along the surface of the piezoelectric substrate 101;
furthermore, each pair of input interdigital electrodes of the multiple groups of input interdigital transducers can excite surface acoustic waves, and the surface acoustic waves excited by the multiple groups of input interdigital electrodes at the same time can be mutually superposed, so that higher fluctuation energy can be obtained;
as one principle for example, the oscillation frequency inherent to the surface acoustic wave is determined by the width, length, and pitch of the input interdigital electrodes of the input interdigital transducer; the temperature and the stress, the rigidity, the mass density and other factors of the substrate material are influenced to change in real time; under the condition that the width, the length and the spacing of the input interdigital electrodes and the rigidity and the density of the piezoelectric substrate are not changed, the change of the temperature can be detected by sensing the change of the oscillation frequency;
further, the temperature T of the surface acoustic wave and the oscillation frequency f (T) have the following relationship:
F(T)＝f(T0)*[1+b0*(T-T0)+b1*(T-T0)2+…bn*(T-T0)n+1]
in the formula T0Measured by the temperature sensor is the air temperature, i.e. the ambient temperature. Temperature coefficient b in the formula0～bnDepending on the material, the first order temperature coefficient b of the piezoelectric substrate is determined when the piezoelectric substrate is made of a material such as quartz0Higher, and second order b1To nth order temperature coefficient bnAnd the temperature change of the surface acoustic wave and the oscillation frequency are basically linear.
Furthermore, multiple groups of output interdigital transducers on the right side of the piezoelectric substrate 101 are used as output transducers for receiving surface acoustic waves transmitted to the right side, and due to the positive piezoelectric effect caused by the deformation of the piezoelectric substrate 101, a high-frequency electric field can be generated in each group of output interdigital transducers in an excitation mode, so that high-frequency alternating-current electric field signals can be output on the output electrodes 104; two joints of each group of output electrodes 104 are connected in parallel with each other and then are respectively electrically connected with one end of the circulating acquisition circuit;
furthermore, sound absorption material layers 102 are arranged on the periphery and the top end of the piezoelectric substrate 101, and stray sound waves which are transmitted to the left side edge and the right side and overflow through the output interdigital transducer can be absorbed by the sound absorption material layers, so that interference caused by echo is avoided.
Further, the surface acoustic wave detection circuit 205 includes: a low-pass filter 206, a switching amplifier 207, and a controller 208; the surface acoustic wave detection circuit 205 is configured to receive the signal acquired by the cyclic acquisition circuit 204, and filter, amplify, and process the signal;
further, the cyclic acquisition circuit 204 is configured to acquire a high-frequency alternating-current electric field signal sampled by the surface acoustic wave sampling unit 201;
for better explanation of the working principle of the present invention, the principle design is briefly explained as follows:
because of the existence of metal foreign matters, an eddy current heating phenomenon is generated, so that the temperature of a local area on the piezoelectric substrate 101 changes, the oscillation frequency of the surface acoustic wave of the local area on the piezoelectric substrate 101 influenced by the temperature changes, and the abnormality of the oscillation frequency of certain channels can be found by comparing the acquired oscillation frequency values measured by different channels with the parameters of each channel;
the setting value of the detection temperature is determined according to the relevant national regulations or higher product requirements, that is, the temperature at which the maximum allowable limit of the heat generation of the metallic foreign matter is transmitted to the piezoelectric substrate 101 through the upper case 301 is used as the temperature value of the detection setting.
As an example, the input and output interdigital transducers are manufactured by a semiconductor integrated circuit process, the size of the input and output interdigital transducers and a correspondingly generated surface acoustic wave detection channel are in millimeter level, and small-size metal foreign bodies like a paper clip and the like can be detected;
as an illustration, a transmitting coil for generating a magnetic field in wireless charging power transfer includes: an upper shell 301, a transmitting coil wire coil 302, a magnetic shielding material 303 and a lower shell 304; wherein, the shell for installing the transmitting coil wire coil inside is generally made of non-metallic materials, and magnetic shielding materials are generally installed below the wire coil; the electric vehicle wireless charging system adopting magnetic coupling resonance comprises a power transmitting part and a power receiving part, wherein the power transmitting part utilizes the inductor and the capacitor of a receiving coil to be connected in series or in parallel to form an LC resonance circuit, a receiving circuit with the same resonance frequency is also formed at a receiving end, and wireless electric energy transmission can be realized through strong magnetic coupling formed by resonance between transmitting and receiving.
The utility model discloses a detect the surface acoustic wave of piezoelectric substrate 101 to judge the temperature variation that the metallic foreign matter brought, the surface acoustic wave utilizes the mechanical wave that is produced by the piezoelectric material surface of encapsulation inside the coil, and the electromagnetic wave that produces such as auxiliary coil has reduced the interference of strong electromagnetic field and external environment when wireless charging, thereby has solved the reliability problem that current metallic foreign matter detected; the metal foreign body is dangerous because of temperature rise, temperature measurement is the most direct and effective method for detecting the metal foreign body, the surface acoustic wave is very sensitive to temperature change, and high detection precision can be obtained through the surface acoustic wave.
The disclosure above is only one specific embodiment of the present application, but the present application is not limited thereto, and any variations that can be made by those skilled in the art are intended to fall within the scope of the present application.

Claims (7)

1. A wireless charging metal foreign matter detection device, characterized by comprising: the surface acoustic wave detection device comprises a surface acoustic wave sampling unit, a piezoelectric substrate, a heat-conducting adhesive layer, a sound-absorbing material layer, a high-frequency generation circuit, a temperature sensor, a circulating acquisition circuit and a surface acoustic wave detection circuit; the surface acoustic wave sampling unit is arranged above the piezoelectric substrate and used for sampling the temperature of an upper shell of the transmitting coil of the wireless charging system; one end of the surface acoustic wave sampling unit is electrically connected with one end of the circulating acquisition circuit, and the other end of the circulating acquisition circuit is electrically connected with one end of the surface acoustic wave detection circuit; the other end of the surface acoustic wave sampling unit is electrically connected with one end of the high-frequency generating circuit;
the piezoelectric substrate is packaged above the wire coil of the transmitting coil and on the lower part of the upper shell; a layer of heat-conducting adhesive layer is filled between the piezoelectric substrate and the upper shell to serve as a buffer layer, so that the pressure transmitted to the piezoelectric material when foreign matters appear above the upper shell is reduced;
the surface acoustic wave sampling unit includes: the array comprises a plurality of groups of input interdigital transducers, a plurality of groups of output interdigital transducers, input electrodes and output electrodes; the multiple groups of input interdigital transducers are arranged on the left side of the piezoelectric substrate in a side-by-side adjacent manner, and the multiple groups of output interdigital transducers are arranged on the right side of the piezoelectric substrate in a side-by-side adjacent manner; the input interdigital transducer is used for receiving surface acoustic waves; the output interdigital transducer is used for generating surface acoustic waves; the input electrodes are used for inputting alternating voltages to the multiple groups of input interdigital transducers; the output electrodes are electrically connected with the multiple groups of output interdigital transducers and used for outputting electric signals;
the surface acoustic wave detection circuit includes: a low pass filter, a switching amplifier and a controller; the surface acoustic wave detection circuit is used for receiving the signals acquired by the circulating acquisition circuit and filtering, amplifying and processing the signals;
and the circulating acquisition circuit is used for acquiring the high-frequency alternating current electric field signal sampled by the surface acoustic wave sampling unit.
2. The wireless charging metal foreign body detection device according to claim 1, wherein the piezoelectric substrate is made of a piezoelectric material.
3. The wireless charging metal foreign object detection device of claim 1, wherein the input interdigital transducer comprises: the two input interdigital electrodes are opposite in cross and are not in contact with each other, and each group of input interdigital electrodes are consistent in size and shape.
4. The wireless charging metal foreign matter detection device according to claim 3, wherein the input interdigital electrode is configured such that a plurality of electrode teeth are vertically arranged on a bus bar.
5. The wireless charging metal foreign matter detection device according to claim 3, wherein the input and output interdigital electrodes are manufactured by metal deposition by adopting a semiconductor integrated circuit process.
6. The wireless charging metal foreign matter detection device according to claim 5, wherein multiple groups of output interdigital transducers on the right side of the piezoelectric substrate are used as output transducers for receiving surface acoustic waves transmitted to the right side, and due to a positive piezoelectric effect caused by deformation of the piezoelectric substrate, a high-frequency electric field is excited in each group of output interdigital transducers to generate a high-frequency alternating current electric field signal, so that the high-frequency alternating current electric field signal can be output on the output electrodes; and two joints of each group of output electrodes are connected in parallel with each other and then are respectively and electrically connected with one end of the circulating acquisition circuit.
7. The wireless charging metal foreign matter detection device as claimed in claim 1, wherein a sound absorption material layer is installed around and on top of the piezoelectric substrate, and stray sound waves that overflow from the outside and propagate through the output interdigital transducer to the left side edge and the right side can be absorbed by the sound absorption material layer, thereby avoiding interference caused by echo.
CN201920968379.3U 2019-06-26 2019-06-26 Wireless charging metal foreign matter detection device Active CN210011609U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110103745A (en) * 2019-06-26 2019-08-09 北京有感科技有限责任公司 A kind of wireless charging detection device of metal foreign body and detection method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110103745A (en) * 2019-06-26 2019-08-09 北京有感科技有限责任公司 A kind of wireless charging detection device of metal foreign body and detection method

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