CN103868618B - System for detecting temperature based on multisensor identification - Google Patents
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Abstract
The invention provides a kind of system for detecting temperature based on multisensor identification, including: reader, broad-band antenna, N number of surface acoustic wave sensor；Surface acoustic wave sensor includes: unidirectional interdigital transducer, frequency orthogonal reflecting grating chip set, wherein: reader is by broad-band antenna transmitting inquiry signal to surface acoustic wave sensor；Wherein, described surface acoustic wave sensor, including: unidirectional interdigital transducer, frequency orthogonal reflecting grating chip set；Surface acoustic wave sensor receives orthogonal frequency coding signal according to the triggering of inquiry signal and is converted into surface acoustic wave signal；Reader receives echo-signal by broad-band antenna.The present invention encodes remote, the Mulit-point Connection and jamproof surface acoustic wave wireless sensor, method that combine based on orthogonal frequency and code division multiplexing, solve " near-far interference " of the passive sensor system of code division multiplexing coding, it is possible to meet the requirement that power equipment temperature wireless is monitored by intelligent grid.
Description
Technical field
The present invention relates to the temperature monitoring field of power equipment, in particular it relates to based on the system for detecting temperature of multisensor identification.
Background technology
In the numerous monitoring variable of power equipment state monitoring, temperature is one of the most key detection limit.By temperature monitoring, running status and the fault message of power equipment can be understood timely and accurately.The running temperature of monitoring power equipment, such as the oil temperature of transformator, the conductor temperature of transmission line of electricity (aerial line and power cable) can calculate its load limit capacity and ageing equipment degree, provides foundation thus updating for power equipment dynamic compatibilization or maintenance.Monitor the temperature of the rotor of electromotor, high-tension switch cabinet, busbar joint, outdoor chopper switch, contact of breaker, capacitor, reactor, high tension cable, transformator etc., overheated or the Temperature Distribution relative anomalies partly or wholly adjoint when it abnormal conditions or fault occurs can be found in time, it is possible to provide historical summary for accident analysis.
Existing mainly have the technical schemes such as infrared measurement of temperature, active radio thermometric and distributed optical fiber temperature measurement for power equipment temperature monitoring.Infrared measurement of temperature is affected relatively big by environmental condition factor, and scheme cost is also high；Active radio thermometric scheme, is thermometric chip power supply after typically now taking battery or current transformer (CT) power taking, and distance sensing is very remote.But under the adverse circumstances such as high temperature, ultralow temperature, strong-electromagnetic field, the life-span of battery and electronic component is problematic in that.Taking the active sensor of CT way to take power, because the coil of CT power taking has installation site requirement, also cannot power under line fault conditions, its application has significant limitation equally.Optical fiber temperature-measurement belongs to wired thermometric mode, and optical fiber or its sheath of measuring high voltage primary side exist insulation against ground sex chromosome mosaicism.Optical fiber has easy to break simultaneously, easily broken characteristic.Additionally Fibre Optical Sensor equipment manufacturing cost is higher.
What utilize based on the radio temperature sensor of surface acoustic wave (surfaceacousticwave is abbreviated as SAW) technology is piezoelectric, has pure passive, radio characteristics, need not consider the problems such as sensor power, High-Voltage Insulation, equipment rotation；Can tolerate high temperature and low temperature (～-200～1000 DEG C)；It does not involve the transition process of electronics in semi-conducting material, and the interference performance such as life-span length, anti-discharge impact and anti-electric field, magnetic field is strong；Size sensor little (Centimeter Level), lightweight, it is easy to structural design and installation.As can be seen here, SAW wireless sensor technology is that the temperature monitoring of power equipment provides a desirable technique platform with broad prospect of application.
But the SAW wireless sensing array developed at present can't fully meet the demand in intelligent grid and extra-high voltage application to temperature monitoring, and the problem shown specifically includes that
Problem 1: operating distance is inadequate.For the temperature monitoring of overhead transmission line dynamic compatibilization, if considering with the SAW reader installed for the centre of sphere, operating radius is at least at about 30 meters.The SAW wireless senser thermometric operating distance for switch cabinet temperature monitor that Sengenuity company of the U.S. develops is only within 2 meters.Germany Brunsb ü ttel, PreussenElektra company and Darmstadt polytechnical university the end of the nineties in last century develop for power transmission line, conductor oxidate spark gap and keep apart the SAW wireless temperature closing application such as whether putting in place of closing a floodgate and measure systemic effect distance up to 10 meters, but will power equipment monitor in popularization and application, its operating distance still needs to further raising.
Problem 2: the temperature spot quantity simultaneously detected is inadequate.In transmission line of electricity is monitored, consider the three-phase of an AC high-voltage electric transmission line on same shaft tower, if installed on the connect power transmission line in tower both sides, the situations such as the ambient temperature monitoring that consideration multi circuit transmission lines carries out with bar situation and conductor temperature model reckoning needs, the quantity of sensor is then at least more than 7.The temperature monitoring of temperature of oil in transformer, switch cabinet temperature and other power equipments requires to require similar to number of sensors.In the SAW wireless sensing array for switch cabinet temperature monitor that Sengenuity company of the U.S. develops, number of sensors (adopts 3 antennas up to 6, up to 18 after enforcement space division multiplexing), but occupy 20MHz bandwidth, considerably beyond the 1.87MHz bandwidth requirement that 433MHz frequency range allows.The domestic Central China University of Science and Technology, Shanghai Communications University, University Of Chongqing and Chinese Academy of Sciences's acoustics etc. the SAW wireless senser of electric power thermometric developed of unit fall within this working method.
Problem 3: sensor interference free performance has much room for improvement.Along with the extensive use of wireless senser in " intelligent grid ", sensor array is greatly increased by probability sudden, in-band on-channel interference effect；Under the various application scenarios of " intelligent grid ", the impacts such as the different frequency selective fading of scene, multipath effect, climatic environments are also different, being likely to result in passive sensor wireless link to interrupt, echo data is lost or causes measurement outlier owing to signal to noise ratio is very poor.These factors all highly impact the reliability of sensor array, it is possible to cause false alarm even protective relaying maloperation to make.
In recent years, scholar is had to propose to adopt the SAW radio-frequency (RF) tag sensing technology scheme of orthogonal frequency coding (OFC).The program has used for reference the thought of OFDM in wireless telecommunications (OFDM), efficiently against the frequency selective fading of channel, can be conducive to improving the reliability of SAW sensor.Meanwhile, every reflecting grating of SAW wireless senser of OFC is all arrowband, does not substantially reflect other orthogonal frequencies.Relative to reflection delay line style SAW sensor, the reflectance of every reflecting grating is no longer only about 10% (otherwise subsequent reflection grid will not receive inquiry pulse energy), but can reach 40～50%.Only reflecting grating reflection loss one, adopts the SAW sensor of OFC just can reduce Insertion Loss 12-13dB.Orthogonal frequency coding is a kind of spread spectrum coding, is similar to intrapulse information modulation radar, and sensor is when demodulation, it is possible to according to the number of chips N comprised in every, increases 20log10The signal to noise ratio of N, is conducive to the raising of operating distance.According to the literature, SAW radio-frequency (RF) tag (RFID) reading distance of OFC coding is up to 60 meters.But there is also some difficulties when this coded system is for temperature sensor to need to overcome:
Difficulty 1: because temperature sensitive, therefore the piezoelectric of low-temperature coefficient can not be chosen as OFC-RFID as substrate material.But due to variations in temperature, being similar in communication system OFDM and produce Doppler frequency shift, the condition of mutually orthogonal frequency is destroyed originally.During reader demodulation sensor information, relevant peaks performance varies with temperature scope and increases and sharply decline.The temperature-measuring range of bibliographical information only has 55 degree.
Difficulty 2:OFC itself does not have multiple access capability.SAW device is again pure passive, can only reflect inquiry signal passively, and can not actively control and when send or stop transmission information.When reader is to inquire about and read multiple OFC-SAW sensor simultaneously, currently existing scheme is to adopt time division multiplex to combine with OFC coding.But owing to being limited to applicable wireless bandwidth and SAW substrate material length, piezoelectric substrate 10 millimeters long (is the limit, longer SAW propagation loss and diffraction loss will obtain greatly and cannot accept) be difficulty with the sensor type of more than 8 kinds.
Summary of the invention
For defect of the prior art, it is an object of the invention to provide a kind of system for detecting temperature based on multisensor identification.
According to the system for detecting temperature based on multisensor identification provided by the invention, it is characterised in that including: reader, broad-band antenna, N number of surface acoustic wave sensor；Surface acoustic wave sensor includes: unidirectional interdigital transducer, frequency orthogonal reflecting grating chip set, wherein:
Reader is by broad-band antenna transmitting inquiry signal to surface acoustic wave sensor；Wherein, described surface acoustic wave sensor, including: unidirectional interdigital transducer, frequency orthogonal reflecting grating chip set；
Surface acoustic wave sensor receives orthogonal frequency by single tine finger transducer according to the triggering of inquiry signal and encodes signal and be converted into surface acoustic wave signal；
Wherein, surface acoustic wave signal through the reflection of frequency orthogonal reflecting grating chip set and forms echo-signal through unidirectional interdigital transducer；
Reader receives echo-signal by broad-band antenna.
Preferably, described frequency orthogonal reflecting grating chip set, including: n the chip being arranged in order；
Described n chip constitutes a kind of sensor coding；The sensor coding that frequency orthogonal reflecting grating chip set contained by different surface acoustic wave sensors is constituted is different；
Each chip is made up of the reflective grating electrodes that a kind of mid frequency is certain, forms the reflection to a positive jiao zi frequency；
The sub-frequency formed between the plurality of chip is mutually orthogonal；
The time domain length of each chip reflected signal keeps consistent, meets orthogonality condition.
Preferably, in each frequency orthogonal reflecting grating chip set, an equal fixed delay τ between adjacent chip, it is respectively provided withDFill as protection, the superposition of different frequency signals is cut off with the formation that influences each other at time domain space, it is suppressed that the interference between each sub-frequency.
Preferably, in the array of saw sensors that multiple surface acoustic wave sensors are constituted, the sub-frequency that the first chip that each sensor coding is corresponding is formed is different, and the arrangement of the sub-frequency that n-1 chip is formed below adopts random code, encodes based on the maximum precoding of Carrier interference ratio or Turbo code.
Preferably, echo-signal is carried out lower linear frequency modulation by reader；Reader carries out temperature monitoring according to the echo-signal after lower linear frequency modulation；Correspondingly, the described inquiry signal that reader is launched is upper linear frequency modulation inquiry signal.
Preferably, the first coding signal that reader encodes according to sensor identifies the surface acoustic wave sensor sending echo-signal, wherein, and the sub-frequency that the described first corresponding first chip of coding signal is formed.
Preferably, reader obtains temperature information according to echo-signal, and specifically, reader performs following steps:
Step 6a1: according to the surface acoustic wave sensor identified, adaptive generation and this surface acoustic wave sensor reflecting grating frequency are from closing matched signal g [(f-△ fi),(t-τi),si], g (f, t, si) for adaptive matched filter function, △ fiFor frequency shift (FS), τiFor time delay, siFor the function of power match coefficient, best matching factor (△ fM,τM,sM) for relevant peaks matching factor value corresponding time maximum；
Step 6a2: carry out temperature search, matched signal g [(the f-△ f calculated in n temperature at each temperaturei),(t-τi),si], and by matched signal g [(f-△ fi),(t-τi),si] carry out related calculation with echo-signal, obtain correlation peak；
Step 6a3: maximum (the △ f of all correlation peaksM,τM,sM) corresponding temperature is the temperature information that this surface acoustic wave sensor is corresponding；
Step 6a4: if the first coding signal has multiple sensor signal, then obtain temperature information successively according to above-mentioned steps 6a1,6a2,6a3.
Preferably, described surface acoustic wave sensor is the sensor after optimizing as follows:
-by Green's function in conjunction with finite element tool, optimize SAW sensor transducer and reflecting grating structure, reduce insertion loss, particularly as follows: according to different orientation, transducer and open circuit, short circuit, floating finger formula reflecting grating on lithium niobate substrate under fundamental frequency and secondary harmonics: finger number, metallization thickness, degree of metalization and floating finger topological weighting, position weighting and reflection, the amplitude of transmission coefficient and Phase Changing, calculate reflection coefficient and the transmission coefficient of reflecting grating under the conditions such as different finger number, metallization thickness, degree of metalization；Utilize it regular, design the SAW sensor that each quadrature frequency components reflection coefficient is identical；Temperature coefficient under utilizing Lagrangian to describe, bring Green's function into, optimization, to the minimum reflecting grating topological structure of the variations in temperature slope of each orthogonal frequency reflection characteristic, reduces the temperature impact on reflectance, it is ensured that sensor reading distance is along with temperature raises and is remarkably decreased.
Compared with prior art, the present invention has following beneficial effect:
The present invention proposes to encode, based on orthogonal frequency and code division multiplexing, remote, the Mulit-point Connection and jamproof surface acoustic wave wireless sensor, method that combine, it it is innovation, because this technology path can by means of orthogonal frequency technology, solve " near-far interference " of the passive sensor system of code division multiplexing coding preferably, the system that multiple passive SAW sensor operating distance is farthest can be read simultaneously, meet the requirement that power equipment temperature wireless is monitored by intelligent grid.In concrete technology path, there are two place's study characteristics.The first can produce non-orthogonal problem after encoding temperature influence for orthogonal frequency; the present invention propose increase between reflecting grating this protection fill can ensure the reflection of each sub-frequency signal will not be formed between each chip by SAW sensor to interfere; even if each chip is influenced by temperature; reflection frequency offsets; the superposition of different frequency signals also can be cut off with the formation that influences each other by this section of time slot at time domain space, it is suppressed that the interference between each sub-frequency.It two is when the reflecting grating utilizing SAW device represents that orthogonal frequency encodes, the present invention utilizes generalized green function in conjunction with finite element theory, the physical problems such as the Rayleigh ripple of the reflecting grating of Accurate Analysis sparse electrode composition reflection, transmission and scattering under fundamental frequency and harmonics, solve and utilize the shortcomings such as calculating speed is slow, bulk wave scattering computational accuracy is low in fourier transform method in the world.
Accompanying drawing explanation
By reading detailed description non-limiting example made with reference to the following drawings, the other features, objects and advantages of the present invention will become more apparent upon:
Fig. 1 is the power equipment temperature monitoring scheme general frame based on OFC surface acoustic wave sensor；
Fig. 2 be multisensor code division multiplexing coding time-frequency characteristic；
Fig. 3 is the adaptive matched filter schematic diagram based on CDMA；
Fig. 4 is transmission line-oriented temperature monitoring sensor structure.
In figure:
101 is boil on the nape opposite the mouth bolt；
102 is the core of power transmission line；
103 is screw；
104 is microstrip antenna；
105 is surface acoustic wave sensor；
106 is the metal shell of power transmission line.
Detailed description of the invention
Below in conjunction with specific embodiment, the present invention is described in detail.Following example will assist in those skilled in the art and are further appreciated by the present invention, but do not limit the present invention in any form.It should be pointed out that, to those skilled in the art, without departing from the inventive concept of the premise, it is also possible to make some deformation and improvement.These broadly fall into protection scope of the present invention.
The invention provides a kind of CDMA (CDMA) and encode, with OFC, the SAW(passive and wireless combined) sensor technology.CDMA is to solve the good method of multiple access in mobile communication.But passive SAW sensor can not carry out power equalization on one's own initiative as communication equipment, namely when multiple sensors exist " near-far interference " with reader, echo amplitude differs greatly, the information of each sensor cannot be isolated by related operation, therefore individually adopt the SAW sensor array of CDMA coding and impracticable.If but orthogonal frequency coding is combined with CDMA, then can first pass through the frequency spectrum size of each orthogonal frequency of estimation, it is achieved power equalization, then can realize multi-sensor information and separate one by one and solve.Owing to all reflection echo signals of the SAW sensor of this mode allow to overlap in time domain, but time-frequency two-dimensional space can well separate, in addition, the sensor echo-signal designed can realize again the associated processing gain of code division multiplexing, it is possible to realizes more than 8 kinds different sensors easily.
Orthogonal frequency combine with CDMA coding SAW sensor can adopt the demodulation method being different from current OFC-SAW temperature sensor when carrying out thermometric.On the one hand, can accurately calculate SAW reflecting grating and each orthogonal frequency reflection characteristic is varied with temperature relation, therefrom optimization to each orthogonal frequency reflection characteristic to the minimum reflecting grating topological structure of variations in temperature slope, reduce the temperature impact on reflectance, it is ensured that sensor reading distance is along with temperature raises and is remarkably decreased；On the other hand, it is possible to adopt a kind of according to the demodulation method measuring temperature self-adaptation search, matched filtering, while obtaining coupling output, also obtain dut temperature value.
For solving " intelligent grid " power equipment, the particularly extra-high voltage electric power equipment demand to temperature monitoring, the present invention proposes to encode, based on orthogonal frequency, the passive wireless acoustic surface wave method for sensing combined with CDMA, to realize the temperature monitoring of remote, Mulit-point Connection measurement and high reliability.
Below the general frame of present system is illustrated.
As it is shown in figure 1, in the constructed power equipment temperature monitoring model space, including: reader, broad-band antenna, multiple surface acoustic wave sensor.Wherein, surface acoustic wave sensor includes: unidirectional interdigital transducer, frequency orthogonal reflecting grating chip set；Surface acoustic wave sensor 1～N Arbitrary distribution (monitors actual demand according to power equipment, N value can meet requirement between 8 to 10).
Temperature monitoring signal processing flow is as follows:
Step 1: reader is launched upper linear frequency modulation (upchirp) by broad-band antenna and inquired about signal, and upper linear frequency modulation inquiry signal is propagated to surface acoustic wave sensor in strong electromagnetic channel A；
Step 2: surface acoustic wave sensor is inquired about signal by unidirectional interdigital transducer according to upper linear frequency modulation and received OFC signal and be converted into surface acoustic wave signal；
Step 3: make surface acoustic wave signal through the reflection of frequency orthogonal reflecting grating chip set and form echo-signal through unidirectional interdigital transducer；
Step 4: echo-signal is propagated to reader in strong electromagnetic channel A, and reader receives echo-signal by broad-band antenna and carries out lower linear frequency modulation (downchirp)；
Step 5: the echo-signal after lower linear frequency modulation is demodulated waiting signal processing by reader, carries out multisensor identification and extracts with temperature information.
Wherein, upper and lower linear frequency modulation can increase by the processing gain of about 20～50, is conducive to improving surface acoustic wave sensor operating distance.
Below OFC is illustrated in conjunction with the CDMA technology path encoded.
As shown in Fig. 1 lower right corner, surface acoustic wave sensor contains f0～f78 chips also constitute a kind of coding, and wherein, chip refers to chip.The electrode that wherein each chip is fixed by mid frequency again forms, and forms the reflection to a positive jiao zi frequency；The sub-frequency formed between multiple is mutually orthogonal.Should designing the quantity of electrode in each chip according to orthogonal frequency coding theory, the time domain length to guarantee each chip reflected signal keeps consistent (on the time response delay, τ in corresponding diagram 1C), meet orthogonality condition.The difference that puts in order of each chip, forms other codings.Such as: f in Fig. 16、f4、f0、f7、f1、f2、f5、f3Put in order composition one coding；If pressing f4、f7、f6、f0、f1、f2、f3、f5Put in order, constitute another sensor.Theoretical according to orthogonal coding, when response device carries out auto-correlation computation, it is possible to have significantly high relevant peaks (to have the surface acoustic wave sensor of N position orthogonal frequency coding in theory, process echo-signal by the mode of compression pulse, it is possible to form N2Times processing gain, in conjunction with upper and lower chirped processing gain 50, therefore under transmitting power and receiving sensitivity same case, can be greatly improved sensor wireless operating distance).And the device of two kinds of different codings is when carrying out computing cross-correlation, but there is very low cross-correlation peak.The present invention studies emulation and selects those codings that cross-correlation peak is very low between two one sensor array of composition, even if these sensors respond the inquiry signal of reader simultaneously, echo is all aliasing in together in time domain, still can be made a distinction by code division multiplexing method.
Can be additionally seen in FIG: between each chip, add an equal fixed delay τD(protection is filled).Increase this protection filling can ensure the reflection of each sub-frequency signal will not be formed between each chip by SAW sensor to interfere; even if each chip is influenced by temperature; reflection frequency offsets; the superposition of different frequency signals also can be cut off with the formation that influences each other by this section of time slot at time domain space, it is suppressed that the interference between each sub-frequency.
Below FUSION WITH MULTISENSOR DETECTION identification, frequency deviation estimation and the temperature detection based on adaptive matched filter are illustrated.
In order to realize the identification of multiple surface acoustic wave sensor, complex electromagnetic environment improves the discrimination of coding, for taking related operation raising signal processing gain and personal identification method in echo signal processing, need to reduce the cross correlation between each coding signal, it is necessary to optimize the spatial classification of corresponding each sub-frequency chip.Possible aligning method can be used for reference random code, all can reduce intersymbol interference based on the maximum precoding of Carrier interference ratio or Turbo code coding, it is ensured that the raising of signal processing gain.Said method is also the multiple access principle of code division multiplexing.But when the spacing of multisensor and reader does not wait, the power of each sensor echo-signal and noise level are not etc., only eliminate " near-far interference " between reader and sensor, under multisensor time domain response aliasing situation each other, the response of each sensor could be efficiently separated out.
The present invention makes the sub-frequency of first chip that each sensor in array of saw sensors encodes different, and the arrangement of n-1 frequency below adopts random code, encodes based on the maximum precoding of Carrier interference ratio or Turbo code.Sensor identification is worked by time slot equally that increase when solving intersymbol interference on sensor substrate.If delay, τDMore than modulation signal and the propagation time sum in the channel of the echo-signal after sensor responds thereof, such as the ball domain space that radius is 30 meters, this time delay is less than 200ns, then this time delay can ensure that reader is when receiving multisensor echo-signal, and the second coding signal of any sensor echo will not enter the first coding signal time gap in time domain space.As it is shown on figure 3, f (t) is the superposition of all the sensors time domain response signal, g [(f-△ fi),(t-τi),si] for adaptive matched filter function, for frequency shift (FS), time delay, the function of power match coefficient, best matching factor (△ fM,τM,sM) for relevant peaks matching factor value corresponding time maximum.Echo-signal first paragraph (τ after demodulationc+τD) in time slot, the signal correspondence different sensors of contained different frequency composition.So can tentatively identify, according to the signal of the first coding, the coding containing several sensor informations and these sensors in aliasing signal.The assessment that the present invention composes according to each echo signal power, carries out power equalization to different coding sensor.Now the size accuracy of every sub-frequency frequency deviation is not high, it is impossible to for temperature detection, but can greatly reduce the temperature hunting zone of subsequent match filtering, improves search efficiency.
Can then proceed in the method shown in Fig. 3, gradually carry out adaptive matched filter, as the matched signal g (f generating a certain specific coding, s, when t) reaching maximum with the auto-correlation computation relevant peaks of multiple sensor signals f (t) of Time-domain aliasing, namely can determine that the temperature value that this code sensor is corresponding.Then change the another one coding existed in array echo signal more again to scan for by Fig. 3.It should be noted that generate matched signal g (f, s, t) appear to be a 2D signal, but two independent variables therein be all the function of temperature, according to search for temperature, namely can determine that respective value.Therefore whole element speed of searching can ensure that.
Below the optimization of sensor is responded and illustrate.
For ensureing orthogonal frequency coding low-loss sign on SAW sensor, primary study interdigital transducer Frequency Response of the present invention, the reflection characteristic of conversion efficiency and reflecting grating and Frequency Response, and its parameter is optimized design.Because the reflecting grating metallization thickness of orthogonal frequency coding is identical, but reflecting grating periodicity, reflecting electrode radical differ greatly, can according to different orientation, transducer and open circuit, short circuit, floating finger formula reflecting grating on lithium niobate substrate under fundamental frequency and secondary harmonics: finger number, metallization thickness, degree of metalization and floating finger topological weighting, position weighting and reflection, the amplitude of transmission coefficient and Phase Changing, calculate reflection coefficient and the transmission coefficient of reflecting grating under the conditions such as different finger number, metallization thickness, degree of metalization.Obtain it regular, to guarantee to design the SAW sensor that each quadrature frequency components reflection coefficient is identical.Temperature coefficient under utilizing Lagrangian to describe, bring Green's function into, optimization, to the minimum reflecting grating topological structure of the variations in temperature slope of each orthogonal frequency reflection characteristic, reduces the temperature impact on reflectance, it is ensured that sensor reading distance is along with temperature raises and is remarkably decreased.
In sensor construction, sensor installation, sensor accuracy and dynamic and the problems such as interference factor such as mount stress, reader crystal oscillator temperature drift of elimination should be considered.Fig. 4 is the transmission line-oriented temperature detection sensor structure that the present invention takes.The position that sensor is installed as shown in Figure 4, metal can be passed through contact very well with core, separated by partiting thermal insulation material and outer cover metal, it is ensured that temperature can follow the change of heart yearn temperature well, the precision simultaneously will not measured because of the heat radiation impact of outer cover metal again simultaneously.Separate with insulant between microstrip antenna and Shell Plate, fixed by screw.The instruments such as finite element software are utilized to optimize thermal capacity and the conductive structure of sensor construction size and encapsulation.Improve sensor dynamic index.The encapsulation of sensor and lead-in wire are the key factors affecting sensor stability, and owing to quality is loaded very sensitive by SAW, the factor such as dust, oil stain, humidity may make sensor complete failure.How both to ensure that substrate surface and the external world were completely isolated by reasonable encapsulation, ensure again measured can efficiently be loaded on substrate after sensor is installed, reach mechanically firm, anti-vibration, shock resistance, avoid the impact on sensing element and high frequency surface wave of thermal stress and package parasitics, the problem that have to consider and solve when being surface wave sensor encapsulation simultaneously.
In Antenna Design, adopt micro-strip antenna form.Full-wave simulation software AnsoftHFSS is adopted to be modeled, the parameter such as the reflection coefficient of simulation calculation antenna, gain, directional diagram and impedance curve.The correct design of feed system is for improving aerial radiation, and receiving efficiency is highly important.The impedance of SAW device itself can realize mating by microstrip feed network structure with the impedance of transmitting antenna.Impedance characteristic according to antenna, designs microstrip balun feeder line, makes antenna in design frequency band internal impedance gradual change to 50 Ω.The frequency band of antenna is the 890MHz-940MHz of 915MHz according to the characteristic initial option of electric apparatus monitoring scene electromagnetic interference signal at mid frequency.
According to the noiseless synchronous read realized in 8-10 sensor 30 meters that the present invention realizes, temperature detection range-50 DEG C～+150 DEG C, within detection error ± 1 DEG C.The operating distance of 915MHz wireless SAW sensor therein is up to 5 meters.By reducing sensor reflection loss 12-13dB, upper and lower linear frequency modulation brings processing gain 50 to be multiplied by code division multiplexing demodulation process gain 64, amounts to 30dB altogether for two, and therefore, the operating distance of sensor is brought up to 30 meters can be achieved.
Above specific embodiments of the invention are described.It is to be appreciated that the invention is not limited in above-mentioned particular implementation, those skilled in the art can make various deformation or amendment within the scope of the claims, and this has no effect on the flesh and blood of the present invention.
Claims (6)
1. the system for detecting temperature based on multisensor identification, it is characterised in that including: reader, broad-band antenna, N number of surface acoustic wave sensor；Surface acoustic wave sensor includes: unidirectional interdigital transducer, frequency orthogonal reflecting grating chip set, wherein:
Reader is by broad-band antenna transmitting inquiry signal to surface acoustic wave sensor；Wherein, described surface acoustic wave sensor, including: unidirectional interdigital transducer, frequency orthogonal reflecting grating chip set；
Surface acoustic wave sensor receives orthogonal frequency by single tine finger transducer according to the triggering of inquiry signal and encodes signal and be converted into surface acoustic wave signal；
Wherein, surface acoustic wave signal through the reflection of frequency orthogonal reflecting grating chip set and forms echo-signal through unidirectional interdigital transducer；
Reader receives echo-signal by broad-band antenna；
Described frequency orthogonal reflecting grating chip set, including: n the chip being arranged in order；
Described n chip constitutes a kind of sensor coding；The sensor coding that frequency orthogonal reflecting grating chip set contained by different surface acoustic wave sensors is constituted is different；
Each chip is made up of the reflective grating electrodes that a kind of mid frequency is certain, forms the reflection to a positive jiao zi frequency；
The sub-frequency formed between described n chip is mutually orthogonal；
The time domain length of each chip reflected signal keeps consistent, meets orthogonality condition；
Described surface acoustic wave sensor is the sensor after optimizing as follows:
-by Green's function in conjunction with finite element tool, optimize SAW sensor transducer and reflecting grating structure, reduce insertion loss, particularly as follows: according to different orientation, transducer and open circuit, short circuit, floating finger formula reflecting grating on lithium niobate substrate under fundamental frequency and secondary harmonics: finger number, metallization thickness, degree of metalization and floating finger topological weighting, position weighting and reflection, the amplitude of transmission coefficient and Phase Changing, calculate reflection coefficient and the transmission coefficient of reflecting grating when different finger number, metallization thickness, degree of metalization；Utilize it regular, design the SAW sensor that each quadrature frequency components reflection coefficient is identical；Temperature coefficient under utilizing Lagrangian to describe, bring Green's function into, optimization, to the minimum reflecting grating topological structure of the variations in temperature slope of each orthogonal frequency reflection characteristic, reduces the temperature impact on reflectance, it is ensured that sensor reading distance is along with temperature raises and is remarkably decreased.
2. the system for detecting temperature based on multisensor identification according to claim 1, it is characterised in that in each frequency orthogonal reflecting grating chip set, be respectively provided with an equal fixed delay τ between adjacent chipDFill as protection, the superposition of different frequency signals is cut off with the formation that influences each other at time domain space, it is suppressed that the interference between each sub-frequency.
3. the system for detecting temperature based on multisensor identification according to claim 1, it is characterized in that, in the array of saw sensors that multiple surface acoustic wave sensors are constituted, the sub-frequency that the first chip that each sensor coding is corresponding is formed is different, and the arrangement of the sub-frequency that n-1 chip is formed below adopts random code, encodes based on the maximum precoding of Carrier interference ratio or Turbo code.
4. the system for detecting temperature based on multisensor identification according to claim 1 or 3, it is characterised in that echo-signal is carried out lower linear frequency modulation by reader；Reader carries out temperature monitoring according to the echo-signal after lower linear frequency modulation；Correspondingly, the described inquiry signal that reader is launched is upper linear frequency modulation inquiry signal.
5. the system for detecting temperature based on multisensor identification according to claim 4, it is characterized in that, the first coding signal that reader encodes according to sensor identifies the surface acoustic wave sensor sending echo-signal, wherein, and the sub-frequency that the described first corresponding first chip of coding signal is formed.
6. the system for detecting temperature based on multisensor identification according to claim 5, it is characterised in that reader obtains temperature information according to echo-signal, specifically, reader performs following steps:
Step 6a1: according to the surface acoustic wave sensor identified, adaptive generation and this surface acoustic wave sensor reflecting grating frequency are from closing matched signal g [(f-△ fi),(t-τi),si], g (f, t, si) for adaptive matched filter function, △ fiFor frequency shift (FS), τiFor time delay, siFor the function of power match coefficient, best matching factor (△ fM,τM,sM) for relevant peaks matching factor value corresponding time maximum；
Step 6a2: carry out temperature search, matched signal g [(the f-△ f calculated in n temperature at each temperaturei),(t-τi),si], and by matched signal g [(f-△ fi),(t-τi),si] carry out related calculation with echo-signal, obtain correlation peak；
Step 6a3: maximum (the △ f of all correlation peaksM,τM,sM) corresponding temperature is the temperature information that this surface acoustic wave sensor is corresponding；
Step 6a4: if the first coding signal has multiple sensor signal, then obtain temperature information successively according to above-mentioned steps 6a1,6a2,6a3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410073648.1A CN103868618B (en) | 2014-03-03 | 2014-03-03 | System for detecting temperature based on multisensor identification |
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| CN104897294A (en) * | 2015-06-03 | 2015-09-09 | 安徽马尼特合开电器有限公司 | Rotary wireless passive temperature sensing system |
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| CN105701521B (en) * | 2016-01-13 | 2018-11-16 | 中国科学院半导体研究所 | The monitoring device of radio frequency identification temperature label, system and method |
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| CN106529646A (en) * | 2016-10-21 | 2017-03-22 | 天津大学 | Surface acoustic wave radio frequency identification tag with reflection gate structure |
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| CN107817013A (en) * | 2017-09-22 | 2018-03-20 | 天津大学 | A kind of high temperature surface acoustic wave sensor based on langasite substrate |
| CN107860487A (en) * | 2017-11-23 | 2018-03-30 | 上海置信电气股份有限公司 | The oil level and oil temperature integration monitoring method and device of distribution transformer |
| CN107819293B (en) * | 2017-11-30 | 2024-02-27 | 杭州泽济电子科技有限公司 | Moving contact with miniaturized electronic tag |
| CN108344800B (en) * | 2018-01-17 | 2020-04-14 | 浙江大学 | Temperature detection system and transceiving system based on wireless passive surface acoustic wave sensor |
| CN110132442A (en) * | 2019-05-31 | 2019-08-16 | 哈动国家水力发电设备工程技术研究中心有限公司 | The magnetic pole surfaces loss measurement device of variable-ratio generator motor |
| CN110455423A (en) * | 2019-08-20 | 2019-11-15 | 武汉科瑞新电气自动化有限公司 | A kind of overlength distance low-power consumption temperature monitoring sensor |
| EP3823247A1 (en) * | 2019-11-15 | 2021-05-19 | ABB Schweiz AG | Method and system for processing sensor data for transmission |
| CN112051566B (en) * | 2020-08-28 | 2023-01-10 | 浙江大学 | Moving part parameter measuring method based on SAW wireless passive sensing system |
| CN113155307B (en) * | 2021-01-18 | 2023-11-03 | 国网吉林省电力有限公司长春供电公司 | Built-in temperature on-line monitoring system of high-voltage power cable connector |
| CN115589235B (en) * | 2022-11-29 | 2023-03-14 | 湖北中环测计量检测有限公司 | Indoor environment detection data interaction method of multiplex communication model |
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| NO322272B1 (en) * | 1999-03-26 | 2006-09-04 | Kongsberg Maritime As | Sensor and temperature monitoring system inside hard-to-reach, moving parts |
| AT7781U3 (en) * | 2005-04-21 | 2006-05-15 | Piezocryst Advanced Sensorics | MEASURING EXAMPLES WITH AT LEAST ONE SAW ELEMENT |
| CN201757684U (en) * | 2009-10-14 | 2011-03-09 | 武汉烽火富华电气有限责任公司 | Acoustic surface wave temperature sensing system used for buried cable |
| CN102708394B (en) * | 2012-04-17 | 2016-02-17 | 重庆大学 | Based on passive temperature label and the reader thereof of SAW |
| CN202648680U (en) * | 2012-05-08 | 2013-01-02 | 中国电子科技集团公司第五十五研究所 | Self-numbering surface acoustic wave (SAW) passive and wireless resonance type sensor |
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Effective date of registration: 20181214 Address after: No. 219, Yuanxin Road, Baoshan District, Shanghai, 2004 Patentee after: SHANGHAI LANJIAN ELECTRIC EQUIPMENT Co.,Ltd. Address before: 200240 No. 800, Dongchuan Road, Shanghai, Minhang District Patentee before: Shanghai Jiao Tong University |
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Denomination of invention: Temperature detection system based on multi-sensor recognition Effective date of registration: 20230709 Granted publication date: 20160706 Pledgee: Bank of China Limited Shanghai Baoshan Branch Pledgor: SHANGHAI LANJIAN ELECTRIC EQUIPMENT Co.,Ltd. Registration number: Y2023980047755 |