Lesi yisihloko sokuqala ochungechungeni lwezingxenye ezimbili. Lo mbhalo uzoqala ukuxoxa ngomlando nezinselelo zeIzinga lokushisa elisuselwa ku-ThermistorIzinhlelo zokulinganisa, kanye nokuqhathanisa kwazo nge-thermometer (RTD) yokulinganisa yokulinganisa yokulinganisa. Izochaza nokukhethwa kwe-thermistor, ukucushwa kokuhweba okuthengiswayo, kanye nokubaluleka kwe-Sigma-Delta Analog-to-Digital Ancures (ADCS) kule ndawo yohlelo lokusebenza. Isihloko sesibili sizocacisa ukuthi ungawengeza kanjani futhi ahlole uhlelo lokulinganisa olususelwa ku-Thermistor olususelwa ku-Thermistor.
Njengoba kuchaziwe kuchungechunge lwe-athikili yangaphambilini, okwenza kahle izinhlelo ze-RTD lokushisa sensor, i-RTD ingukuphikisa okuhlukahluka okuhlukahluka okukushisa. Ama-thermitors asebenza ngokufanayo nama-RTD. Ngokungafani nama-RTD, ane-coeffleently efanelekile kuphela, i-thermistor ingaba ne-coefficient elungile noma engemihle. Ama-thermitors angemuhle okushisa anciphise (NTC) anciphisa ukumelana kwawo njengoba izinga lokushisa likhuphuka, ngenkathi ama-thermitors e-PTC) akhulisa ukumelana kwawo njengoba izinga lokushisa likhuphuka. Ku-Fig. 1 ikhombisa izici zokuphendula ze-stc okujwayelekile ama-NTC kanye ne-PTC futhi ziziqhathanisa nama-RTD curve.
Mayelana nobubanzi bokushisa, ijika le-RTD licishe lilayini, futhi inzwa ihlanganisa uhla lokushisa olubanzi kakhulu kunabokushisa (imvamisa -200 ° C kuya ku- + 850 ° C) ngenxa ye-thermistor engeyona eye-thermistor. Ama-RTD avame ukuhlinzekwa kuma-curve ahlelwe kahle, kanti i-thermistor curves iyahlukahluka ngumenzi. Sizoxoxa ngokuningiliziwe engxenyeni yesiqondisi sokukhethwa kwe-Thermistor.
Ama-thermitors enziwa ngezinto ezihlanganisiwe, imvamisa ama-ceramics, ama-polymers, noma ama-semiconductors (imvamisa ama-oxides) nezinsimbi ezihlanzekile (iplatinamu, nickel, noma ithusi). Ama-thermitors angabona ushintsho lokushisa ngokushesha kune-RTDS, ukuhlinzeka ngempendulo esheshayo. Ngakho-ke, izindawo ezishisayo zivame ukusetshenziswa izinzwa kuzinhlelo zokusebenza ezidinga izindleko eziphansi, usayizi omncane, ukuphendula okusheshayo, nokulawulwa kwezokwakha, ukunxephezelwa kwesayensi, okukhokhwayo kwama-thermocoulceple kuma-thermocouples ezisetshenzisweni ezentengiso noma zezimboni. izinhloso. Izicelo.
Ezimweni eziningi, asetshenziselwa ukufudumala kwe-NTC ukuthola isilinganiso sokushisa esinembile, hhayi ama-Thermitors e-PTC. Amanye ama-thermitors athile e-PTC ayatholakala angasetshenziswa emibuthanweni yokuvikela engaphezulu noma njengemfucumfucu yokuhambisa kabusha izinhlelo zokusebenza zokuphepha. Ijika lokumelana lokumelana ne-PTC Thermistor libonisa isifunda esincane se-NTC ngaphambi kokufika endaweni yokushintsha (noma i-curie point), ngaphezulu okukhuphuka okukhuphuka ngokubanzi ngama-oda amaningana ngobukhulu obuningi be-degrees Celsius. Ngaphansi kwemibandela engapheli, i-PTC Thermistor izokhiqiza ukuphefumula okuqinile lapho izinga lokushisa elishintshayo lidluliswa, futhi ukumelana kwalo kuzovuka kakhulu, lapho kuvimbela ukufakwa kwamanje ohlelweni, ngaleyo ndlela kuvikele ukulimala. Iphoyinti elishintshiwe le-PTC Thermitors ngokuvamile liphakathi kuka-60 ° C no-120 ° C futhi alifanele ukulawula izilinganiso zokushisa ezinhlelweni ezahlukahlukene zezicelo. Lo mbhalo ugxile kuma-NTC atmitors, ajwayele ukukala noma ukuqapha amazinga okushisa asuka ku -80 ° C kuya ku-150 ° C. Izindawo zokushisa ze-NTC zinezilinganiso zokumelana ezisukela kuma-ohms ambalwa kuya ku-10 mω ngo-25 ° C. Njengoba kukhonjisiwe ku-Fig. 1, ushintsho ekumelaneni nge-degree celsius ye-thermistius kukhulunywa ngokwengeziwe kunokwezingameli. Uma kuqhathaniswa nama-thermitors, ukuzwela okuphezulu kwe-thermistor kanye nenani eliphakeme lokumelana ne-high I-Thermistor Design isebenzisa ukucushwa okulula kwezingu-2 kuphela.
Ukulinganisa okuphezulu okunembile okususelwa e-Thermistor kudinga ukucushwa okunembile kwesiginali, ukuguqulwa kwe-analog kuya ku-digital, ulayini, kanye nesinxephezelo, njengoba kukhonjisiwe ku-Fig. 2.
Yize iketanga lesiginali lingabonakala lilula, kunezinkinga ezimbalwa ezithinta usayizi, izindleko, kanye nokwenza kwakho yonke iboardboard. Iphothifoliyo yokunemba ye-ADI ADC ifaka izixazululo ezimbalwa ezihlanganisiwe, njenge-AD7124-4 / AD71244-8, enikeza izinzuzo eziningi zokwakhiwa kohlelo lwe-Thermal njengoba amabhlogo wokwakha adingekayo. Kodwa-ke, kunezingqinamba ezahlukahlukene ekwakheni nasekwakheni kahle izixazululo zokushisa okususelwa ku-Thermistor.
Lo mbhalo uxoxa ngasinye salezi zinkinga futhi uhlinzeka ngezincomo zokuzixazulula futhi wenze lula ukwenziwa ngcono inqubo yalezo zinqubo.
Kunezinhlobonhlobo eziningiAma-Thermitors we-NTCEmakethe namuhla, ngakho-ke ukukhetha i-thermistor efanelekile yesicelo sakho kungaba ngumsebenzi owesabekayo. Qaphela ukuthi ama-thermitors abhalwe ngenani lawo eliphakeme, okungukuphikiswa kwabo okukhohlisayo ngo-25 ° C. Ngakho-ke, i-10 K Thermistor inokuphikiswa okungu-10 kω ngo-25 ° C. Abe-Thermitors banamanani wokumelana noma ayisisekelo wokumelana asukela kuma-ohms ambalwa kuya ku-10 m. Abe-Thermitors abanokulinganiselwa okuphansi kokumelana (nokuphikiswa okukhohlisayo kwe-10 kω noma ngaphansi) ngokuvamile kusekela amabanga okushisa aphansi, anjenge-50 ° C kuya ku-70 ° C. Abe-Thermitors abanezilinganiso eziphakeme zokumelana bangamelana namazinga okushisa aze afike ku-300 ° C.
Into ye-thermistor yenziwe ngensimbi oxide. Ama-thermitors ayatholakala eBill, Radial and SMD bobunjwa. Ubuhlalu be-Thermistor buka-epoxy ehlanganisiwe noma ingilazi etholwayo ekuvikelweni okungeziwe. Ama-thermitors e-epoxy ahlanganiswe ama-epoxy, ama-radial futhi angaphezulu komhlaba alungele amazinga okushisa aze afike ku-150 ° C. Ama-The Mlass Bead Thermitors alungele ukukala amazinga okushisa aphezulu. Zonke izinhlobo zezimbali / ukufakwa futhi zivikele ekugqwaneni. Amanye ama-thermitors nawo azoba nezindlu ezingeziwe zokuvikelwa okungeziwe ezindaweni ezinokhahlo. I-Bead Thermitors inesikhathi sokuphendula esisheshayo kunama-radial / smd thermitors. Kodwa-ke, azintshaliwa ezihlala isikhathi eside. Ngakho-ke, uhlobo lwe-thermistor olusetshenzisiwe luncike ekusetshenzisweni kokuphela kanye nemvelo lapho i-thermistor itholakala khona. Ukuqina kwesikhathi eside kwe-thermistor kuncike kokuqukethwe kwayo, ukupakisha, nokuklama. Isibonelo, i-Epoxy-Camera-Camera Chermistor ingashintsha u-0,2 ° C ngonyaka, ngenkathi i-thermistor evaliwe ishintsha kuphela ngo-0,02 ° C ngonyaka.
Abe-Thermitors beza ngokunemba okuhlukile. Abe-Thermitors ajwayelekile ngokuvamile banokunemba okungu-0.5 ° C kuya ku-1.5 ° C. Isilinganiso sokumelana ne-thermistor nenani le-beta (isilinganiso esingu-25 ° C kuye ku-50 ° C / 85 ° C) sibekezele. Qaphela ukuthi inani le-beta le-thermistor liyahlukahluka ngomenzi. Isibonelo, abangu-10 K Sω NTC abavela kubakhiqizi abahlukene bazoba namanani ahlukile we-beta. Ngezinhlelo ezinembile, ezishisayo ezifana nochungechunge lwe-Omega ™ 44XXX lungasetshenziswa. Banokunemba kuka-0.1 ° C noma 0.2 ° C ngaphezulu uhla lokushisa lwe-0 ° C kuya ku-70 ° C. Ngakho-ke, uhla lwamazinga okushisa olungalinganiswa futhi ukunemba okudingekayo phezu kwalelo banga lokushisa linquma ukuthi ngabe ama-thermitors alungele lolu hlelo lokusebenza. Uyacelwa uqaphele ukuthi kukhuphuka uchungechunge lwe-Omega 44xxx, kukhuphuka izindleko.
Ukuguqula ukumelana nama-degree Celsius, inani le-beta livame ukusetshenziswa. Inani le-beta linqunywa ngokwazi amaphuzu okushisa amabili kanye nokuphikiswa okuhambisanayo endaweni ngayinye yokushisa.
I-RT1 = Ukumelana Nezinga lokushisa 1 Rt2 = Ukumelana Nezinga lokushisa 2 T1 = lokushisa 1 (k) t2 = lokushisa 2 (k)
Umsebenzisi usebenzisa inani le-beta eliseduzane nasehlangeni lokushisa elisetshenzisiwe kuphrojekthi. Iningi le-datasheets le-thermistor libala inani le-beta kanye nokubekezelela ukumelana ngo-25 ° C nokubekezelelana ngenani le-beta.
Abe-Thermitors aphezulu ngokunemba kanye nezixazululo eziphezulu zokuqedwa okufana nochungechunge lwe-Omega 44xxxx Sebenzisa i-Steingart-Hart equation ukuguqula ukumelana nama-degree Celsius. I-Equation 2 idinga ama-constant amathathu a, B, no-C, aphinde anikezwe ngumenzi wezinzwa. Ngoba ama-coefficients e-equation akhiqizwa kusetshenziswa amaphuzu amathathu okushisa, i-equation ephumayo inciphisa iphutha elethwe ngumonerization (ngokuvamile 0.02 ° C).
A, B no-C bathathwe kususelwa kumikhawulo emithathu yokushisa. R = thermistor ukumelana kuma-ohms t = izinga lokushisa ku kk degrees
Ku-Fig. I-3 ikhombisa ukuthokozela okukhona kwenzwa. I-Drive yamanje isetshenziswa ku-thermistor kanye namanje yamanje isetshenziswa ekuphakameni kwenembe; Ukuphikiswa okunembile kusetshenziswa njengereferensi yokulinganisa. Inani le-Resistar Resistar yereferensi kumele libe likhulu noma lilingane nenani eliphakeme kakhulu lokumelana ne-thermistor (kuya ngokushisa okuphansi okulinganiswe ohlelweni).
Lapho ukhetha i-Excitation yamanje, ukumelana okuphezulu kwe-thermistor kumele kuphinde kubhekwe. Lokhu kuqinisekisa ukuthi amavota awenzele inzwa kanye nereferensi yokumelana ihlala isezingeni elamukelekayo kuma-elekthronikhi. Umthombo wamanje wensimu udinga i-Header noma ukuhambelana. Uma i-thermistor inokumelana okuphezulu emazingeni okushisa aphansi kakhulu, lokhu kuzoholela ekudleni okuphansi kakhulu kwamanje. Ngakho-ke, i-voltage eyenziwe ngaphesheya kwe-thermistor ekushiseni okuphezulu incane. Izigaba zokuthola izinhlelo ezihlelekile zingasetshenziswa ukwenza isilinganiso salezi zimpawu ezisezingeni eliphansi. Kodwa-ke, inzuzo kumele ihlelwe ngamandla ngoba izinga lesiginali elivela ku-thermistor liyahlukahluka kakhulu ngamazinga okushisa.
Enye inketho ukusetha inzuzo kepha usebenzise i-Dynamic drive yamanje. Ngakho-ke, njengoba izinga lesiginali elivela ku-Thermistor lishintsha, i-drive yenani lamanje lishintsha ngamandla ukuze i-voltage ithuthukiswe kulo lonke i-thermistor ingaphakathi kohlu olubekiwe lokufaka lwedivayisi ye-elektroniki. Umsebenzisi kufanele aqinisekise ukuthi amavota athuthukiswe ngaphesheya kwereferensi assistic futhi asezingeni elamukelekayo kuma-elekthronikhi. Zombili lezi zinketho zidinga ukulawulwa okuphezulu, ukuqapha njalo kwamandla kagesi ngaphesheya kwe-thermistor ukuze ama-elekthronikhi akwazi ukukala isiginali. Ingabe ikhona inketho elula? Cabanga nge-Voltage Exciation.
Lapho i-DC voltage isetshenziswa ku-thermistor, okwamanje nge-thermistor isikali ngokuzenzakalela njengoba izinguquko zokumelana nokufudumele. Manje, usebenzisa ukumelana nokulinganisa okuqondile esikhundleni sokuphikiswa kwereferensi, inhloso yawo ukubala ukugeleza kwamanje nge-thermistor, ngaleyo ndlela kuvume ukumelana ne-thermistor ukuba kubalwe. Njengoba i-drive voltage nayo isetshenziswa njengesibonakaliso sereferensi ye-ADC, asikho isiteji esidingekayo. Iprosesa ayinawo umsebenzi wokuqapha i-Thermistor Voltage, enqume ukuthi ingabe izinga lesiginali lingalinganiswa yini nge-elekthronikhi, futhi libala ukuthi yini inzuzo yedrayivu / inani lamanje lidinga ukulungiswa. Le yindlela esetshenziswe kule ndatshana.
Uma i-thermistor inesilinganiso esincane sokumelana nobubanzi bokumelana nobubanzi bokumelana, i-voltage noma i-replation yamanje ingasetshenziswa. Kulokhu, i-drive yamanje futhi inzuzo ingalungiswa. Ngakho-ke, umjikelezo uzoba njengoba kukhonjisiwe kuMfanekiso 3. Le ndlela ilungele ukuthi kungenzeka ukulawula okwamanje ngokusebenzisa inzwa kanye nenzuzo yokumelana, okubalulekile kwizicelo zamandla aphansi. Ngaphezu kwalokho, ukuzikhandla kwe-thermistor kuncishisiwe.
Ukuvuselelwa kweVoltage kungasetshenziselwa futhi ama-thermitors anezilinganiso eziphansi zokumelana. Kodwa-ke, umsebenzisi kufanele aqinisekise njalo ukuthi okukhona njengamanje nge-sensor akuphezulu kakhulu kwenzwa noma isicelo.
I-Voltage Exciation yenza lula ukwenziwa lapho kusetshenziswa i-thermistor enesilinganiso esikhulu sokumelana nobubanzi bokushisa obubanzi. Ukumelana okukhulu okukhohlisayo kunikeza izinga elamukelekayo lamanje. Kodwa-ke, abaklami badinga ukuqinisekisa ukuthi okwamanje kusesezingeni elamukelekayo ngaphezulu kwebanga lokushisa elisekelwa uhlelo lokusebenza.
I-SIGMA-DELTA ADCS inikezela ngezinzuzo eziningana lapho kuklanywa uhlelo lokulinganisa i-thermistor. Okokuqala, ngoba i-Sigma-Delta Adc iphinde iphinde ifake okokufaka kwe-analog, ukuhlunga kwangaphandle kugcinwa kuncane futhi okuwukuphela kwesidingo se-RC isihlungi se-RC esilula. Banikeza ukuguquguquka ngohlobo lokuhlunga kanye nokukhipha inani le-baud. Ukuhlunga okwakhelwe ngaphakathi kwedijithali kungasetshenziselwa ukucindezela noma yikuphi ukuphazamiseka kumadivayisi anamandla. Amadivayisi angama-24 afana ne-AD7124-4 / AD71244-8 abe nesinqumo esigcwele esifinyelela ku-21.7 Bits, ngakho-ke bahlinzeka ngesinqumo esiphakeme.
Ukusetshenziswa kwe-sigma-delta adc yenza lula kakhulu i-thermistor design ngenkathi kunciphisa ukucaciswa, izindleko zohlelo, isikhala sebhodi kanye nesikhathi sokumaketha.
Lo mbhalo usebenzisa i-AD7124-4 / AD7124-8 njenge-ADC ngoba umsindo ophansi, i-adcs ephansi yamanje, enembile nge-PGA eyakhelwe ngaphakathi, ireferensi eyakhelwe ngaphakathi, kanye ne-buffer yereferensi.
Akunandaba ukuthi usebenzisa i-drive yamanje noma i-drive voltage, ukucushwa kwe-ratiometric kunconywa lapho i-voltage yezethenjwa kanye ne-sensor voltage ivela emthonjeni ofanayo wedrayivu. Lokhu kusho ukuthi noma yiluphi ushintsho emthonjeni wezaziso ngeke luthinte ukunemba kwesilinganiso.
Ku-Fig. I-5 ikhombisa i-drive njalo yamandla we-thermistor kanye ne-revistor reporision rref, i-voltage ethuthukiswe kuyo yonke i-rref yi-voltage yereferensi yokulinganisa i-thermistor.
Insimu yamanje ayidingi ukunemba futhi ingahle ibe sezinzile njengoba noma yimaphi amaphutha asensimini yamanje azoqedwa kulokhu kucushwa. Ngokuvamile, ukuthokozela kwamanje kukhethwa ngaphezulu kwe-voltage expation ngenxa yokulawulwa kokuzwela okuphezulu kanye nokungavikeleki komsindo okungcono lapho inzwa itholakala ezindaweni ezikude. Lolu hlobo lwendlela ye-bias ngokuvamile lusetshenziselwa ama-RTDS noma ama-thermitors anamanani aphansi wokumelana. Kodwa-ke, i-thermistor enenani eliphakeme lokumelana kanye nokuzwela okuphezulu, izinga lesiginali elikhiqizwe ushintsho ngalunye lokushisa luzoba lukhulu, ngakho-ke kusetshenziswa i-voltage expation. Isibonelo, i-10 K Thermistor inokumelana kwe-10 kω ngo-25 ° C. Ku-50 ° C, ukumelana kwe-NTC Thermistor ngu-441.117 kω. Ukushayela okuncane kwamanje kwama-50 μ anikezwe yi-AD7124-4 / AD71244-8 akhiqiza ama-441.11 k ω × 50 μa = 22 v, okuphezulu kakhulu kwe-ADCS etholakala kakhulu esetshenziswa kule ndawo Ama-thermitors nawo ajwayele ukuxhunywa noma atholakala eduze kwe-elekthronikhi, ngakho-ke ukungavikeleki ku-drive yamanje akudingeki.
Ukungeza i-Resistor Resistor ngochungechunge njenge-voltage divider circuit kuzokhawulela okukhona kwe-thermistor kunani layo lokumelana eliphansi. Kulokhu kucushwa, inani le-reprilor ye-meeplor runse kumele lilingane nenani lokumelana ne-thermistor ekushiseni okungu-25 kω ngokufana, uma kusetshenziswa i-10 Kω. Njengoba izinga lokushisa lishintsha, ukumelana kwe-NTC Thermistor kubuye kuguquke futhi isilinganiso se-drive voltage kulo lonke i-thermistor futhi sishintsha, okuholela ekuphakameni kwamandla athile okulingana nokuphikiswa kwe-NTC Thermistor.
Uma ireferensi ekhethiwe ye-voltage esetshenziselwe amandla i-thermistor kanye / noma i-rsense kufana ne-adc Reference Voltage esetshenziselwa ukukala, uhlelo lusethwe ku-Ratiometric, 0 0, 0
Qaphela ukuthi kungaba ngumqondo womqondo (i-voltage eqhutshwa) noma ukuhanjiswa kwereferensi (okuqhutshwa kwamanje) kufanele kube nokubekezelelana okuphansi kokuqala kanye nokushayela okuphansi, njengoba zombili izinto eziguqukayo zingathinta ukunemba kwalo lonke uhlelo.
Lapho usebenzisa ama-thermitors amaningi, kungasetshenziswa i-voltage eyodwa. Kodwa-ke, i-thermistor ngayinye kufanele ibe nomqondo wayo wokuqonda, njengoba kukhonjisiwe ku-Fig. 8. Enye inketho ukusebenzisa i-Multiplexer Multiplexer noma i-Shintsha elisezingeni eliphansi ku-State, elivumela ukwaba umuzwa owodwa wokuqinisekiswa kwengqondo. Ngalolu hlelo, i-thermistor ngayinye idinga ukulungiswa kwesikhathi lapho kulinganiswa.
Ngamafuphi, lapho uklama uhlelo lokushisa olususelwa ku-Thermistor olususelwa ku-Thermistor, kunemibuzo eminingi okufanele ucatshangelwe Isihloko esilandelayo kulolu chungechunge sichaza ukuthi ungawengeza kanjani ukwakheka kohlelo lwakho kanye nesabelomali sephutha lesistimu ephelele ukufeza ukusebenza kwelitshe lakho.
Isikhathi sePosi: Sep-30-2022