Maidir le córas tomhais teochta braiteora teirmeachúpla a dhearadh agus a chur i bhfeidhm

Mar ghné tipiciúil tomhais teochta, baineadh úsáid fhorleathan as an mbraiteoir teirmeachúpla .
Seo a leanas córas tipiciúil tomhais teochta arna rialú ag microcomputer sliseanna amháin, ina bhfuil trí chuid: (1) ciorcad aimplitheoirí tomhais; (2) ciorcad tiontaithe A/D; .
{1. Dearadh crua -earraí
(1) Braiteoir teochta teirmeachúpla
This system uses nickel-chromium-nickel-silicon thermocouples. The measured temperature range is 0-655℃. The cold end compensation adopts the compensation bridge method. The potential generated by the unbalanced bridge is used to compensate for the change in thermoelectric potential caused by the change in the cold end temperature of the Thermocouple . Is éard atá sa droichead neamhchothrom ná ceithre arm droichid friotóirí R1, R2, R3 (foirceannadh sreinge copair mangainéise), RCU (foirceannadh sreinge copair) agus rialtóir voltais droichid, atá ceangailte sa tsraith thermocouple {{11} RCU agus an deireadh fuar sa chiorcad teirmeach {}} RCU and an deireadh an chiorcad teirmeach} ±0℃, and R1=R2=R3=1Ω. The bridge power supply voltage is 4V, powered by a voltage-stabilized power supply. Rs is a current-limiting resistor, and its resistance value varies with different teirmeachúcháin {. Is iondúil go ndéantar an droichead a chothromú ag 20 céim . Ag an am seo, is iad r 1= r 2= r {{{1= r 2= r {3= RCU, agus níl aon aschur ag an gcéim, nuair a bhíonn an t -aschur ag an gcéim, mar shampla, mar shampla, mar shampla, mar shampla, mar shampla, {{}}} nuair a bhíonn an t -aschur ag an} Ardaigh, méadaíonn RCU, cé go laghdaíonn poitéinseal teirmileictreach an teirmeachúpla de réir mar a mhéadaíonn an teocht deireadh fuar . Tá UAB cothrom leis an laghdú ar an bpoitéinseal teirmileictreach, agus tá an poitéinseal aschuir fós gan athrú tar éis do UAB a bheith maoirsithe ar an bpoitéinseal termoelectric.
(2) Ciorcad Aimplitheoirí Tomhais
I gciorcaid iarbhír, níl an t -aschur comhartha ón teirmeachúpla níos mó ná cúpla deich millivolts (<30mV), and contains common-mode interference such as power frequency, static electricity and magnetic coupling. To amplify this kind of circuit, the amplifier circuit needs to have a high common-mode rejection ratio, high gain, low noise and high input impedance. Therefore, a measurement amplifier circuit is suitable. The measurement amplifier is also called a data amplifier, instrument amplifier and bridge amplifier. It has a high input impedance and is easy to match with various signal sources. Its input offset voltage, input offset current and input bias current are small, and the temperature drift is small. Due to the small time temperature drift, the measurement amplifier has good stability. The measurement amplifier is composed of three op amps, and the differential input terminals R1 and R2 are connected to the in-phase terminals of A1 and A2 respectively. The input impedance is very high, a symmetrical circuit structure is used, and the measured signal is directly added to the input terminal, thereby ensuring a strong ability to suppress common-mode signals. A3 is actually a differential follower, and its gain is approximately 1. The gain of the measuring amplifier is: AV=V0/(V2-V1), AV=Rf/R(1+(Rf1+Rf2)/RW). In this circuit, as long as the performance of op amps A1 and A2 is symmetrical (mainly referring to input impedance and voltage gain), their drift will be greatly reduced. They have high input impedance and common mode rejection ratio, are very sensitive to tiny differential mode voltage, and are suitable for measuring signals transmitted over long distances. Therefore, they are very easy to use with sensors with tiny outputs. RW is an external resistor used to adjust the gain, and a multi-turn potentiometer is used here.
In the actual circuit, A1 and A2 use low-drift, high-precision op amp OP-07 chips, whose input offset voltage temperature drift VIOS and input offset current temperature drift IIOS are very small. OP-07 uses ultra-high technology and "Zener fine-tuning" technology to make its VIOS, IIOS, VIOS and IIOS very small, and is Éilítear go forleathan i gcomhtháthú cobhsaí, i mbreiseán beachtais, i mbrath comparáide agus i aimpliú beachtais na gcomharthaí laga {. op -07 soláthar déchumhachta, agus is é an raon teochta oibriúcháin ná 0-70 céim . Go ginearálta, ní gá coigeartú nialais a úsáid mar is féidir le coigeartú RW {{{}}} a choigeartú a úsáid Coigeartú . Úsáideann A3 sliseanna 741, a éilíonn soláthar déchumhachta, agus is é an raon soláthair cumhachta ± (3-18) v . Is é ± 15V an soláthar cumhachta tipiciúil, ar cheart go mbeadh sé níos mó ná nó cothrom le ± 5v {{{}}} Tá cúiteoirí in ann cúiteoirí a bheith ann, agus is féidir le cúiteoirí a bheith in ann cúiteoirí a chaiteachas {}}}}}
(3) Ciorcad Comhshó A/D (Analógach go Digiteach)
Tá raon voltais de {0-5 v . ag an gcomhartha voltais arna mhéadú ag an aimplitheoir tomhais {0-5 v . Is comhartha aschur é an comhartha seo agus ní féidir leis an ríomhaire a ghlacadh, mar sin ní mór a/d chomhshó a dhéanamh {{{}} sa chiorcad iarbhír, is é A High-PRECIAS.} ICL7109, A a A High7109 Chip} {} ICL7109 Is é a A SHIP a bheith curtha ar fáil slis Torann íseal, íseal-thriomú, dé-chostas íseal {12- giotán A/D Tiontaire . Ós rud é go bhfuil an comhfhogasú i ndiaidh a chéile 12- i ndiaidh a chéile, tá an tiontaire saor in ann a bheith i gceist, mar is féidir le ICL7109 a úsáid i gcás go n-úsáidtear an t-ic}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}} \\ I gcórais tomhais ardchruinnithe le haghaidh comharthaí braiteora éagsúla amhail meáchan, brú tomhais, agus teocht a thomhas .
Tríd an anailís thuas ar an gcóras tomhais teochta braiteora teirmeachúpla, tá súil agam go mbeidh sé ina chuidiú le hobair agus staidéar gach duine .