CN110103745A - A kind of wireless charging detection device of metal foreign body and detection method - Google Patents
A kind of wireless charging detection device of metal foreign body and detection method Download PDFInfo
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- CN110103745A CN110103745A CN201910558356.XA CN201910558356A CN110103745A CN 110103745 A CN110103745 A CN 110103745A CN 201910558356 A CN201910558356 A CN 201910558356A CN 110103745 A CN110103745 A CN 110103745A
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- 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
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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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
A kind of wireless charging detection device of metal foreign body and detection method, comprising: circuit, temperature sensor, circle collection circuit and surface acoustic wave detection circuit occur for surface acoustic wave sampling unit, piezoelectric substrate, heat-conducting glue layer, sound-absorbing material layer, high frequency；The upper casing temperature above piezoelectric substrate, for sampling wireless charging system transmitting coil is arranged in the surface acoustic wave sampling unit；By increasing piezoelectric substrate in transmitting coil, surface acoustic wave is motivated to detect temperature change, to find the device and detection method of foreign matter, it solves the problems, such as to cause high temperature on wireless charging transmitting coil there are metallic foreign body and security risk may be caused, and strong interference immunity, the safety of electric car wireless charging work can be improved.
Description
Technical field
The present invention relates to electric car wireless charging technical field, especially a kind of wireless charging detection device of metal foreign body
And detection method.
Background technique
With the continuous consumption of fossil energy and the continuous aggravation of environmental pollution, new-energy automobile industry has obtained various countries
The active support of the government is in the stage of a high speed development.Electric car wireless charging have conveniently, safely, automation
Etc. advantages, have become the hot spot of charging technique research and development.But electric car wireless charging transmitting coil is typically mounted at
On outdoor parking stall, surface is possible to such as all kinds of metallic foreign bodies of coin, pop can, iron nail occur at any time, in wireless charging
These metallic foreign bodies can be because eddy current effect causes to generate heat when electric, and the efficiency of transmission of wireless charging will be greatly reduced in this aspect,
Be also possible to ignite simultaneously periphery combustibles and bring safety accident.So must to configure a set of metal different for wireless charging system
The detection device of object ensures the safety of charging.
Electric car wireless charging can carry out metallic foreign body detection using following several modes, include:
1. monitoring transmitting coil surface image, foreign matter is found by image monitoring；
There is may produce by external interferences such as light, and the problem of cleaning itself for the detection method of image vision
Raw false alarm or cannot and the case where alarm；
2. using the method for the Parameters variations such as impedance under auxiliary detection line circle array detection operating fields；
Influence of the high-intensity magnetic field to detection system component when also being worked because of wireless charging using ancillary coil, and there is
The sensibility of detection, accuracy and it is anti-interference etc. the problem of.Small sized metallic foreign matter because under magnetic field Parameters variation compared with
It is small, and the boundary phase mutual of detection coil is overlapped in coil array, often there is the blind area of metallic foreign body detection.
3. the method for using temperature sensor sampling transmitting terminal temperature；
Temperature sensor can only measure the temperature of a certain contact point, if to sample the whole end face an of transmitting coil,
Need a large amount of sensor composition array.The probe and lead-out wire of temperature sensor are typically all metal material, in wireless charging
Sensor, failure energy transmission can be equally damaged in transmission process because of eddy current effect, and this detection mode is also easy to produce
Raw monitoring blind area.
4. using the detection technique of infrared measurement of temperature monitoring interlink warning；
Infrared measurement of temperature equally will receive the external interference of ambient light etc., and surface has reflective, meeting when metal object measures
The detection in practical application is influenced, it cannot be guaranteed that the general safety of wireless charging.One transmitting coil is sampled using infrared measurement of temperature
Whole end face, there is also high-cost problem, often more use is in experiment test.
Summary of the invention
In order to solve the above technical problem, the present invention provides a kind of wireless charging detection device of metal foreign body and detection sides
Method, by increasing piezoelectric substrate in transmitting coil, excitation surface acoustic wave detects temperature change, to find the dress of metallic foreign body
It sets and detection method, solves and cause high temperature on wireless charging transmitting coil there are metallic foreign body and security risk may be caused
The safety of electric car wireless charging work can be improved in problem, and strong interference immunity.
A kind of wireless charging detection device of metal foreign body and detection method, in which:
A kind of wireless charging detection device of metal foreign body, comprising: surface acoustic wave sampling unit, piezoelectric substrate, heat-conducting glue layer,
Circuit, temperature sensor, circle collection circuit and surface acoustic wave detection circuit occur for sound-absorbing material layer, high frequency；The sound surface
The upper casing temperature above piezoelectric substrate, for sampling wireless charging system transmitting coil is arranged in wave sampling unit；The sound
One end of surface wave sampling unit is electrically connected with one end of the circle collection circuit, the other end of the circle collection circuit with
One end of the surface acoustic wave detection circuit is electrically connected；Electricity occurs for the other end and the high frequency of the surface acoustic wave sampling unit
The one end on road is electrically connected；
Further, to achieve the purpose that detect foreign matter, the piezoelectric substrate is encapsulated in above transmitting coil drum, upper casing
The lower part of body；One layer of heat-conducting glue layer is filled between the piezoelectric substrate and upper housing as buffer layer, to reduce on upper housing
Pressure is transmitted to piezoelectric material when foreign matter occurs in side；
Illustrate as an example, the piezoelectric substrate is made using piezoelectric material；
Further, the surface acoustic wave sampling unit includes: multiple groups input interdigital transducer, multiple groups output interdigital transducing
Device, input electrode and output electrode；Multiple groups input interdigital transducer is adjacent side by side to be arranged in the piezoelectric substrate
Left side, the multiple groups output interdigital transducer adjacent right side that the piezoelectric substrate is set side by side；The input is interdigital to change
Energy device is for receiving surface acoustic wave；The output interdigital transducer is for generating surface acoustic wave；The input electrode is used for institute
State multiple groups input interdigital transducer input alternating voltage；The output electrode is electrically connected with the multiple groups output interdigital transducer,
For exporting electric signal；
Illustrate as an example, the input interdigital transducer includes: two and intersects opposite, non-touching input fork
Refer to electrode, every group of input interdigital electrode size, shape are consistent；
Illustrate as a kind of preferable examples, the input interdigital electrode is vertically set on busbar using multiple electrodes tooth
Structure, i.e., similar to wooden comb structure；
Illustrate as an example, the output interdigital transducer includes: two and intersects opposite, non-touching output fork
Refer to electrode, every group of output interdigital electrode size, shape are consistent；
Illustrate as a kind of preferable examples, the output interdigital electrode is vertically set on busbar using multiple electrodes tooth
Structure, i.e., similar to wooden comb structure；
Illustrate as an example, the input, output interdigital electrode are all made of semiconductor integrated circuit technique, pass through gold
Belong to deposition to be made；
Illustrate as an example, the input interdigital transducer is consistent with output interdigital transducer size, structure；
Illustrate as an example, the input electrode is to exchange two-wire system lead mechanism with output electrode, is equivalent to
It is provided with zero curve and two connectors of firewire；
Further, the multiple groups input interdigital transducer on the left of the piezoelectric substrate is as input energy converter, when at every group
Input interdigital transducer input electrode on apply an alternating voltage when, will between described two input interdigital electrodes shape
At potential difference；Under the electric field action that the potential difference is formed, due to the effect of inverse piezoelectricity, it can generate and answer on piezoelectric substrate surface
Become, so as to cause the stretching or contraction of piezoelectric substrate material, and direction of an electric field can generate periodicity because being influenced by alternating voltage
Alternating variation so that piezoelectric substrate surface generates the periodical alternately deformation of " contraction-stretching-contraction ", the shape on this surface
Change will motivate surface acoustic wave, and spread to the left and right sides along piezoelectric substrate surface；
Further, every a pair of of input interdigital electrode of the multiple groups input interdigital transducer can excite surface acoustic
Wave, multiple groups input the surface acoustic wave that interdigital electrode motivates simultaneously can be mutually superimposed, to can get higher Wave energy；
As a kind of principle for example, the intrinsic frequency of oscillation of the surface acoustic wave is by the input interdigital transducer
Width, length and the spacing of input interdigital electrode are determined；Also with temperature, the stress of base material, rigidity, mass density etc. because
Element is influenced and is changed in real time；Input width, length and the spacing of interdigital electrode and rigidity, the density of piezoelectric substrate
In the case where remaining unchanged, the variation of temperature can be detected by the variation of perception frequency of oscillation；
Further, temperature T and frequency of oscillation F (T) relationship of the surface acoustic wave has following relational expression:
F (T)=f (T0)*[1+b0*(T-T0)+b1*(T-T0)2+…bn*(T-T0)n+1]
T in formula0It is obtained by temperature sensor measurement, it is environment temperature that measurement, which is air themperature,.Temperature in formula
Coefficient b0~bnIt is determined by material, when piezoelectric substrate is made of such as quartz material, single order temperature coefficient b0It is higher, and
Second order b1To n rank temperature coefficient bnLower, the temperature change and frequency of oscillation of surface acoustic wave are substantially linear.
Further, the multiple groups output interdigital transducer on the right side of the piezoelectric substrate is as output transducer, for receiving
It is propagated through the surface acoustic wave come to the right, due to piezoelectric substrate deformation bring direct piezoelectric effect, the output fork described in every group
Finger transducer underexcitation generates high-frequency electric field, so as to export high-frequency ac electric field signal in the output electrode；Every group
Two connectors of output electrode are connected in parallel to each other together, are then electrically connected respectively with one end of the circle collection circuit；
Further, the surrounding of the piezoelectric substrate and top are mounted with sound-absorbing material layer, to the left side edge and to the right
The spuious sound wave for propagating across the output interdigital transducer and overflowing outside can be absorbed by sound-absorbing material layer, avoided echo and caused
Interference.
Further, the surface acoustic wave detection circuit includes: low-pass filter, switching amplifier and controller；It is described
Surface acoustic wave detection circuit is used to receive the signal of circle collection circuit acquisition, and the signal is filtered, amplify and
Processing；
Further, the circle collection circuit, the high frequency sampled for acquiring the surface acoustic wave sampling unit
AC field signal；
A kind of detection method of wireless charging detection device of metal foreign body, includes the following steps:
Step 1: wireless charging starting before small power transmission inspection or charge normal in powerful transmission process,
If the metallic foreign body can cause own temperature because of eddy current effect sharply there is metallic foreign body above the upper housing of transmitting coil
It increases, and drives the temperature of its region is synchronous to increase, this heat can be led through the upper housing of transmitting coil by subsequent
Hot glue layer is transmitted on piezoelectric substrate；
Step 2: circuit occurs by external industrial-frequency alternating current by high frequency to detect the Temperature Distribution on the piezoelectric substrate
High-frequency alternating current is converted to, and is applied in the input electrode of input interdigital transducer, a system is generated on the piezoelectric substrate
Column cover the surface acoustic wave of entire piezoelectric substrate, and propagate along piezoelectric substrate；
Step 3: each output interdigital transducer of the piezoelectric substrate right end setting turns received surface acoustic wave
It is changed to high-frequency ac electric field, two connectors of the output electrode at each output interdigital transducer both ends are connected in parallel respectively, and
It is electrically connected with one end of circle collection circuit, after the circle collection circuit is switched by internal circuit timesharing, with surface acoustic wave
Detection circuit circulation is connected, i.e., the output interdigital transducer is only accessed every time, by the high-frequency ac electric signal in the channel
It is sent into surface acoustic wave detection circuit, frequency component useless in signal is filtered out, is then sent to switching amplifier, signal is put
Greatly, and by signal by sine wave signal it is transformed to square-wave signal, is sent in controller later and carries out signal processing.
Illustrate as an example, to the measurement of frequency of oscillation mainly by being realized to square wave signal-count, that is, controls
Device is measured by measuring pulse number per second and frequency of oscillation is calculated.
Illustrate as an example, it can be by setting multiple groups circle collection circuit and surface acoustic wave detection circuit, to mention
The acquisition speed of high RST.
Illustrate as an example, the high-frequency alternating current of input can also directly adopt the coupling of the Coupling devices such as coil
By independent high frequency circuit can also occur for the high-frequency alternating current being applied on receiving coil in wireless charging power transmission process
Generate high-frequency alternating current；When high-frequency alternating current using the alternating current in power transmission process as interdigital transducer, generation
Surface acoustic wave is consistent with the magnetic field resonance frequency of wireless charging power transmission, and can preferably offset power transmission magnetic field may be right
The influence that surface acoustic wave generates.
Step 4: the processing that controller carries out signal is calculated according to the relation formula of frequency of oscillation and temperature, work as control
When the temperature that device processed detects is more than set temperature value, controller, which issues instruction, makes wireless charging system stop power transmission, leads to
The mating terminal device for crossing wireless charging issues alarm signal, and goes out the position of foreign matter according to respective channel position instruction, that is, sends out
The region of raw temperature change.
Working principle in order to better illustrate the present invention, the foundation for now briefly explaining the design of its principle are as follows:
Due to the presence of metallic foreign body, eddy-current heating phenomenon is generated, the temperature change of regional area on piezoelectric substrate is caused,
The frequency of oscillation for being affected by temperature the surface acoustic wave of regional area on piezoelectric substrate can change, collected not by comparison
The parameter of the frequency of oscillation value and each channel that measure with channel is compared to each other, it can be found that the frequency of oscillation generation in certain channels is different
Often；
The setting for detecting the setting value of temperature is determined according to concerned countries specification or higher product requirement, i.e., by metal
The highest limit value that foreign matter fever allows is transmitted to temperature value of the temperature of piezoelectric substrate as detection setting through upper housing.
Illustrate as an example, the input, output interdigital transducer are made with semiconductor integrated circuit technique, ruler
The very little and corresponding surface acoustic wave sense channel generated is millimeter rank, and the small sized metallic that can detecte out similar to clip etc. is different
Object；
Illustrate as an example, the transmitting coil that magnetic field is generated in wireless charging power transmission includes: upper housing, transmitting
Coil drum, magnetic shielding material and lower case；Wherein in the shell of internal installation transmitting coil drum generally by nonmetallic materials
It makes, generally will be installed magnetic shielding material below drum；There is function using the wireless charging system for electric automobile of magnetic coupling resonance
Rate transmitting and reception two parts, wherein power emission is connected in series to the capacitor using the inductance of receiving coil or the LC resonance in parallel that formed is returned
Road also forms the reception circuit of same resonance frequency in receiving end, the strong magnetic that can be formed by resonance between transmitting and reception
Coupling is to realize wireless power transmission.
The utility model has the advantages that
The present invention passes through the surface acoustic wave of detection piezoelectric substrate, to judge metallic foreign body bring temperature change, sound
What surface wave utilized is the mechanical wave generated by being encapsulated in the piezoelectric material surface of coil inside, rather than ancillary coil etc. generates
Electromagnetic wave, the interference of strong-electromagnetic field and external environment when reducing wireless charging, to solve existing metallic foreign body inspection
The integrity problem of survey.
It is exactly temperature rise that metallic foreign body, which generates dangerous reason, and measurement temperature is the most directly effective side of detection metallic foreign body
Method, surface acoustic wave is very sensitive to temperature change, can obtain very high detection accuracy by surface acoustic wave.
Detailed description of the invention
Fig. 1 is a kind of structure design diagram of wireless charging detection device of metal foreign body of the present invention
Fig. 2 is a kind of circuit theory schematic diagram of wireless charging detection device of metal foreign body of the present invention
Fig. 3 is that the transmitting coil structural schematic diagram of a kind of wireless charging detection device of metal foreign body of the present invention being based on is lifted
Example
Specific embodiment
In the following, with reference to figures 1 through shown in Fig. 3, a kind of wireless charging detection device of metal foreign body and detection method, in which:
A kind of wireless charging detection device of metal foreign body, comprising: surface acoustic wave sampling unit 201, is led at piezoelectric substrate 101
Circuit 202, temperature sensor 203, circle collection circuit 204 and surface sound occur for hot glue layer 305, sound-absorbing material layer 102, high frequency
Wave detection circuit 205；The surface acoustic wave sampling unit 201 is arranged above piezoelectric substrate 101, is used for sampling wireless Charging
301 temperature of upper housing of system transmitting coil；One end of the surface acoustic wave sampling unit 201 and the circle collection circuit 204
One end electrical connection, the other end of the circle collection circuit 204 and one end of the surface acoustic wave detection circuit 205 are electrically connected
It connects；The other end of the surface acoustic wave sampling unit 201 is electrically connected with one end that circuit 202 occurs for the high frequency；
Further, to achieve the purpose that detect foreign matter, the piezoelectric substrate 101 is encapsulated on transmitting coil drum 302
Side, the lower part of upper housing 301；One layer of heat-conducting glue layer 305 is filled between the piezoelectric substrate 101 and upper housing 301 as slow
Layer is rushed, pressure is transmitted to piezoelectric material when occurring foreign matter to reduce above upper housing 301；
Illustrate as an example, the piezoelectric substrate 101 is made using piezoelectric material；
Further, the surface acoustic wave sampling unit 201 includes: multiple groups input interdigital transducer, multiple groups output interdigital
Energy converter, input electrode 103 and output electrode 104；The multiple groups input interdigital transducer is adjacent side by side to be arranged described
The left side of piezoelectric substrate 101, the multiple groups output interdigital transducer adjacent right side that the piezoelectric substrate 101 is set side by side
Side；The input interdigital transducer is for receiving surface acoustic wave；The output interdigital transducer is for generating surface acoustic wave；It is described
Input electrode 103 is used to input alternating voltage to multiple groups input interdigital transducer；The output electrode 104 and the multiple groups
Output interdigital transducer electrical connection, for exporting electric signal；
Illustrate as an example, the input interdigital transducer includes: two and intersects opposite, non-touching input fork
Refer to electrode, every group of input interdigital electrode size, shape are consistent；
Illustrate as a kind of preferable examples, the input interdigital electrode is vertically set on confluence using multiple electrodes tooth 105
Structure on item 106, i.e., similar to wooden comb structure；
Illustrate as an example, the output interdigital transducer includes: two and intersects opposite, non-touching output fork
Refer to electrode, every group of output interdigital electrode size, shape are consistent；
Illustrate as a kind of preferable examples, the output interdigital electrode is vertically set on busbar using multiple electrodes tooth
Structure, i.e., similar to wooden comb structure；
Illustrate as an example, the input, output interdigital electrode are all made of semiconductor integrated circuit technique, pass through gold
Belong to deposition to be made；
Illustrate as an example, the input interdigital transducer is consistent with output interdigital transducer size, structure；
Illustrate as an example, the input electrode is to exchange two-wire system lead mechanism with output electrode, is equivalent to
It is provided with zero curve and two connectors of firewire；
Further, the multiple groups input interdigital transducer in 101 left side of piezoelectric substrate is as input energy converter, when every
It, will be between described two input interdigital electrodes when applying an alternating voltage in the input electrode of group input interdigital transducer
Form potential difference；Under the electric field action that the potential difference is formed, due to the effect of inverse piezoelectricity, it can be produced on 101 surface of piezoelectric substrate
Raw strain, so as to cause the stretching or contraction of 101 material of piezoelectric substrate, and direction of an electric field can be produced because being influenced by alternating voltage
It is raw periodically alternately to change, so that 101 surface of piezoelectric substrate generates the periodical alternately deformation of " contraction-stretching-contraction ", this
The deformation on kind surface will motivate surface acoustic wave, and spread to the left and right sides along 101 surface of piezoelectric substrate；
Further, every a pair of of input interdigital electrode of the multiple groups input interdigital transducer can excite surface acoustic
Wave, multiple groups input the surface acoustic wave that interdigital electrode motivates simultaneously can be mutually superimposed, to can get higher Wave energy；
As a kind of principle for example, the intrinsic frequency of oscillation of the surface acoustic wave is by the input interdigital transducer
Width, length and the spacing of input interdigital electrode are determined；Also with temperature, the stress of base material, rigidity, mass density etc. because
Element is influenced and is changed in real time；Input width, length and the spacing of interdigital electrode and rigidity, the density of piezoelectric substrate
In the case where remaining unchanged, the variation of temperature can be detected by the variation of perception frequency of oscillation；
Further, temperature T and frequency of oscillation F (T) relationship of the surface acoustic wave has following relational expression:
F (T)=f (T0)*[1+b0*(T-T0)+b1*(T-T0)2+…bn*(T-T0)n+1]
T in formula0It is obtained by temperature sensor measurement, it is environment temperature that measurement, which is air themperature,.Temperature in formula
Coefficient b0~bnIt is determined by material, when piezoelectric substrate is made of such as quartz material, single order temperature coefficient b0It is higher, and
Second order b1To n rank temperature coefficient bnLower, the temperature change and frequency of oscillation of surface acoustic wave are substantially linear.
Further, the multiple groups output interdigital transducer on 101 right side of piezoelectric substrate is as output transducer, for connecing
The surface acoustic wave for being propagated through come to the right is received, it, can be defeated described in every group due to 101 deformation bring direct piezoelectric effect of piezoelectric substrate
Interdigital transducer underexcitation generates high-frequency electric field out, so as to export high-frequency ac electric field letter in the output electrode 104
Number；Two connectors of every group of output electrode 104 are connected in parallel to each other together, then electric with one end of the circle collection circuit respectively
Connection；
Further, the surrounding of the piezoelectric substrate 101 and top are mounted with sound-absorbing material layer 102, to the left side edge and
The spuious sound wave for propagating across the output interdigital transducer to the right and overflowing outside can be absorbed by sound-absorbing material layer, be avoided back
It is interfered caused by sound.
Further, the surface acoustic wave detection circuit 205 includes: low-pass filter 206, switching amplifier 207 and control
Device 208 processed；The surface acoustic wave detection circuit 205 is used to receive the signal that the circle collection circuit 204 acquires, and to the letter
It number is filtered, amplifies and processing；
Further, the circle collection circuit 204 is obtained for acquiring the sampling of surface acoustic wave sampling unit 201
High-frequency ac electric field signal；
A kind of detection method of wireless charging detection device of metal foreign body, includes the following steps:
Step 1: wireless charging starting before small power transmission inspection or charge normal in powerful transmission process,
If 301 top of upper housing of transmitting coil is there is metallic foreign body, which can cause own temperature because of eddy current effect
It sharply increases, and drives the temperature of its region is synchronous to increase, after this heat can pass through through the upper housing 301 of transmitting coil
The heat-conducting glue layer 305 in face is transmitted on piezoelectric substrate 101；
Step 2: circuit 202 occurs by external power frequency by high frequency for the Temperature Distribution for detecting on the piezoelectric substrate 101
Alternating current is converted to high-frequency alternating current, and is applied in the input electrode 103 of input interdigital transducer, in the piezoelectric substrate
A series of surface acoustic wave of entire piezoelectric substrates 101 of covering is generated on 101, and is propagated along piezoelectric substrate；
Step 3: each output interdigital transducer of 101 right end of piezoelectric substrate setting is by received sound surface
Wave is converted to high-frequency ac electric field, and two connectors of the output electrode 104 at each output interdigital transducer both ends are connected in parallel on respectively
Together, and with one end of circle collection circuit 204 it is electrically connected, the circle collection circuit 204 is switched by internal circuit timesharing
Afterwards, it recycles and connects with surface acoustic wave detection circuit 205, i.e., the output interdigital transducer is only accessed every time, by the channel
High-frequency ac electric signal be sent into surface acoustic wave detection circuit 205, filter out frequency component useless in signal, be then sent to turn
Amplifier 207 is changed, signal is amplified, and signal is transformed to square-wave signal by sine wave signal, is sent to controller 208 later
Middle carry out signal processing.
Illustrate as an example, to the measurement of frequency of oscillation mainly by being realized to square wave signal-count, that is, controls
Device 208 is measured by measuring pulse number per second and frequency of oscillation is calculated.
Illustrate as an example, setting multiple groups circle collection circuit 204 and surface acoustic wave detection circuit can be passed through
205, to improve the acquisition speed of signal.
Illustrate as an example, the high-frequency alternating current of input can also directly adopt the coupling of the Coupling devices such as coil
By independent high frequency circuit can also occur for the high-frequency alternating current being applied on receiving coil in wireless charging power transmission process
Generate high-frequency alternating current；When high-frequency alternating current using the alternating current in power transmission process as interdigital transducer, generation
Surface acoustic wave is consistent with the magnetic field resonance frequency of wireless charging power transmission, and can preferably offset power transmission magnetic field may be right
The influence that surface acoustic wave generates.
Working principle in order to better illustrate the present invention, the foundation for now briefly explaining the design of its principle are as follows:
Due to the presence of metallic foreign body, eddy-current heating phenomenon is generated, the temperature of regional area on piezoelectric substrate 101 is caused to become
Change, the frequency of oscillation for being affected by temperature the surface acoustic wave of regional area on piezoelectric substrate 101 can change, and be acquired by comparison
To the parameter of frequency of oscillation value and each channel that measures of different channels be compared to each other, it can be found that the frequency of oscillation in certain channels
It is abnormal；
The setting for detecting the setting value of temperature is determined according to concerned countries specification or higher product requirement, i.e., by metal
The highest limit value that foreign matter fever allows is transmitted to temperature of the temperature of piezoelectric substrate 101 as detection setting through upper housing 301
Value.
Illustrate as an example, the input, output interdigital transducer are made with semiconductor integrated circuit technique, ruler
The very little and corresponding surface acoustic wave sense channel generated is millimeter rank, and the small sized metallic that can detecte out similar to clip etc. is different
Object；
Illustrate as an example, in wireless charging power transmission generate magnetic field transmitting coil include: upper housing 301,
Transmitting coil drum 302, magnetic shielding material 303 and lower case 304；It is wherein general in the shell of internal installation transmitting coil drum
It is made by nonmetallic materials, generally will be installed magnetic shielding material below drum；Using the electric car wireless charging of magnetic coupling resonance
Electric system has power emission and receives two parts, and wherein power emission is connected in series to the capacitor or in parallel using the inductance of receiving coil
LC resonance circuit is formed, also forms the reception circuit of same resonance frequency in receiving end, it can be by humorous between transmitting and reception
The strong magnetic coupling formed of shaking realizes wireless power transmission.
The present invention is by detecting the surface acoustic wave of piezoelectric substrate 101, thus judge metallic foreign body bring temperature change,
What surface acoustic wave utilized is the mechanical wave generated by being encapsulated in the piezoelectric material surface of coil inside, rather than ancillary coil etc. produces
Raw electromagnetic wave, the interference of strong-electromagnetic field and external environment when reducing wireless charging, to solve existing metallic foreign body
The integrity problem of detection；It is exactly temperature rise that metallic foreign body, which generates dangerous reason, and measurement temperature is that detection metallic foreign body is most direct
Effective method, surface acoustic wave is very sensitive to temperature change, can obtain very high detection accuracy by surface acoustic wave.
Disclosed above is only the specific embodiment of the application, and however, this application is not limited to this, any this field
Technical staff can think variation, should all fall in the protection domain of the application.
Claims (10)
1. a kind of wireless charging detection device of metal foreign body characterized by comprising surface acoustic wave sampling unit, piezoelectric substrate,
Circuit, temperature sensor, circle collection circuit and surface acoustic wave detection circuit occur for heat-conducting glue layer, sound-absorbing material layer, high frequency；Institute
State upper casing body temperature of the surface acoustic wave sampling unit setting above piezoelectric substrate, for sampling wireless charging system transmitting coil
Degree；One end of the surface acoustic wave sampling unit is electrically connected with one end of the circle collection circuit, the circle collection circuit
The other end be electrically connected with one end of the surface acoustic wave detection circuit；The other end of the surface acoustic wave sampling unit with it is described
One end electrical connection of circuit occurs for high frequency；
The piezoelectric substrate is encapsulated in above transmitting coil drum, the lower part of upper housing；Between the piezoelectric substrate and upper housing
One layer of heat-conducting glue layer is filled with as buffer layer, pressure is transmitted to piezoelectric material when occurring foreign matter to reduce above upper housing；
The surface acoustic wave sampling unit include: multiple groups input interdigital transducer, multiple groups output interdigital transducer, input electrode with
And output electrode；The multiple groups input the interdigital transducer adjacent left side that the piezoelectric substrate is arranged in side by side, the multiple groups
The output interdigital transducer adjacent right side that the piezoelectric substrate is set side by side；The input interdigital transducer is for receiving sound
Surface wave；The output interdigital transducer is for generating surface acoustic wave；The input electrode is used to input to the multiple groups interdigital
Energy converter inputs alternating voltage；The output electrode is electrically connected with the multiple groups output interdigital transducer, for exporting electric signal；
The surface acoustic wave detection circuit includes: low-pass filter, switching amplifier and controller；The surface acoustic wave detection electricity
Road is used to receive the signal of the circle collection circuit acquisition, and is filtered, amplifies and processing to the signal；
The circle collection circuit, the high-frequency ac electric field signal sampled for acquiring the surface acoustic wave sampling unit.
2. a kind of wireless charging detection device of metal foreign body according to claim 1, which is characterized in that the piezoelectric substrate
It is made using piezoelectric material.
3. a kind of wireless charging detection device of metal foreign body according to claim 1, which is characterized in that the input is interdigital
Energy converter includes: two and intersects opposite, non-touching input interdigital electrode, and every group of input interdigital electrode size, shape are consistent.
4. a kind of wireless charging detection device of metal foreign body according to claim 3, which is characterized in that the input is interdigital
Electrode is vertically set on the structure on busbar using multiple electrodes tooth.
5. a kind of wireless charging detection device of metal foreign body according to claim 3, which is characterized in that described to input, is defeated
Interdigital electrode is all made of semiconductor integrated circuit technique out, is made by metal deposit.
6. a kind of wireless charging detection device of metal foreign body according to claim 5, which is characterized in that the piezoelectric substrate
The multiple groups output interdigital transducer on right side is as output transducer, for receiving the surface acoustic wave for being propagated through come to the right, due to
Piezoelectric substrate deformation bring direct piezoelectric effect, the output interdigital transducer underexcitation described in every group generate high-frequency electric field, from
And high-frequency ac electric field signal can be exported in the output electrode；Two connectors of every group of output electrode are connected in parallel to each other one
It rises, is then electrically connected respectively with one end of the circle collection circuit.
7. a kind of wireless charging detection device of metal foreign body according to claim 1, which is characterized in that the piezoelectric substrate
Surrounding and top be mounted with sound-absorbing material layer, side edge and propagate across the output interdigital transducer to the right and outer to the left
The spuious sound wave overflowed can be absorbed by sound-absorbing material layer, avoid interference caused by echo.
8. a kind of detection method of wireless charging detection device of metal foreign body, which comprises the steps of:
Step 1: wireless charging starting before small power transmission inspection or charge normal in powerful transmission process, if
There is metallic foreign body above the upper housing of transmitting coil, which can cause own temperature sharply to rise because of eddy current effect
Height, and drive the temperature of its region is synchronous to increase, this heat can pass through subsequent thermally conductive through the upper housing of transmitting coil
Glue-line is transmitted on piezoelectric substrate；
Step 2: circuit occurs by high frequency and converts external industrial-frequency alternating current to detect the Temperature Distribution on the piezoelectric substrate
It for high-frequency alternating current, and is applied in the input electrode of input interdigital transducer, a series of cover is generated on the piezoelectric substrate
The surface acoustic wave of entire piezoelectric substrate is covered, and is propagated along piezoelectric substrate；
Step 3: each output interdigital transducer of the piezoelectric substrate right end setting is converted to received surface acoustic wave
Two connectors of high-frequency ac electric field, the output electrode at each output interdigital transducer both ends are connected in parallel respectively, and with follow
One end of ring Acquisition Circuit is electrically connected, and after the circle collection circuit is switched by internal circuit timesharing, is detected with surface acoustic wave
Circuit cycles are connected, i.e., only access the output interdigital transducer every time, and the high-frequency ac electric signal in the channel is sent into
Surface acoustic wave detection circuit filters out frequency component useless in signal, is then sent to switching amplifier, signal is amplified, and
Signal is transformed to square-wave signal by sine wave signal, is sent in controller later and carries out signal processing；
Step 4: controller carries out the processing of signal, the relation formula according to frequency of oscillation and temperature is calculated, and works as controller
When the temperature detected is more than set temperature value, controller, which issues instruction, makes wireless charging system stop power transmission, passes through nothing
The mating terminal device of line charge electricity issues alarm signal, and goes out the position of foreign matter according to respective channel position instruction, that is, temperature occurs
Spend the region of variation；
Temperature T and frequency of oscillation F (T) relationship of the surface acoustic wave has following relational expression:
F (T)=f (T0)*[1+b0*(T-T0)+b1*(T-T0)2+…bn*(T-T0)n+1]
T in formula0It is obtained by temperature sensor measurement, measurement is air themperature, i.e. environment temperature；Temperature coefficient b in formula0
~bnIt is determined by material.
9. a kind of detection method of wireless charging detection device of metal foreign body according to claim 8, which is characterized in that right
The measurement of the frequency of oscillation is mainly by realizing square wave signal-count, i.e., the described controller is by measuring pulse per second
Number measures and frequency of oscillation is calculated.
10. a kind of detection method of wireless charging detection device of metal foreign body according to claim 8, which is characterized in that
The high-frequency alternating current of input can also directly adopt coil Coupling device, couple and be applied in wireless charging power transmission process
High-frequency alternating current on receiving coil.
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