Basic Knowledge ntawm PTC

PTC yog ib qho luv luv rau Positive Temperature Coefficient, feem ntau xa mus rau cov khoom siv semiconductor lossis cov khoom siv nrog qhov kub zoo coefficient. Feem ntau, thaum peb hais txog PTC, peb tab tom xa mus rau Qhov Zoo Kub Kub Coefficient Thermistors, feem ntau hu ua PTC thermistors. PTC thermistors yog ib hom semiconductor resistor nrog kub rhiab heev, thiab thaum kub tshaj ib tug tej yam pib (Curie kub), lawv kuj nce ruptly nrog kub nce.

Cov ntaub ntawv ceramic feem ntau yog siv los ua cov insulators zoo heev nrog kev ua haujlwm siab. Ceramic PTC thermistor yog tsim los siv barium titanate ua lub hauv paus thiab doped nrog lwm cov ntaub ntawv polycrystalline ceramic, uas ua rau qis tsis kam thiab cov yam ntxwv semiconductor. Qhov no yog ua tiav los ntawm kev txhob txwm doping ntawm cov khoom siv tshuaj lom neeg nrog ntau dua valence raws li lub lattice point ntawm cov siv lead ua. Ib feem ntawm cov barium ions los yog titanate ions nyob rau hauv lub lattice yog hloov los ntawm lub siab dua valence ions, tsim ib tug tej yam dawb electrons uas pab rau hluav taws xob conductivity.

Yog vim li cas rau PTC (Positive Temperature Coefficient) cuam tshuam, piv txwv li, qhov nce sai ntawm kev tiv thaiv, nyob rau hauv cov khoom siv lub koom haum, uas muaj ntau cov microcrystals me me. Ntawm qhov sib cuam tshuam ntawm cov pob zeb no, hu ua cov ciam teb, cov teeb meem raug tsim, cuam tshuam kev txav ntawm cov hluav taws xob mus rau thaj tsam uas nyob ib sab. Yog li ntawd, qhov tsis kam ua siab. Cov nyhuv no yog offset ntawm qhov kub thiab txias vim qhov siab dielectric tas li thiab spontaneous polarization lub zog ntawm cov qoob loo ciam teb, uas tiv thaiv kev tsim cov teeb meem thiab tso cai rau cov hluav taws xob ntws tawm dawb. Txawm li cas los xij, ntawm qhov kub thiab txias, qhov dielectric tsis tu ncua thiab polarization lub zog txo qis, ua rau muaj kev cuam tshuam thiab tsis kam ua kom muaj zog, ua rau muaj zog PTC.

Qhov hnyav thiab sib xyaw: Cov khoom siv, xws li barium carbonate, titanium dioxide, thiab lwm yam khoom ntxiv, raug ntsuas kom raug thiab sib xyaw kom ua tiav cov khoom siv hluav taws xob thiab thermal.

1. Kev sib tsoo ntub dej: Cov khoom sib xyaw ua ke ntub dej sib tsoo los ua ib qho kev sib xyaw ua ke.

2. Lub cev qhuav dej thiab ziab: Cov muab tshuaj yog tom qab ntawd lub cev qhuav dej thiab qhuav kom tshem tawm cov dej noo ntau dhau.

3. Dry Pressing: Cov khoom siv qhuav yog qhuav-nias rau hauv ntau yam duab, xws li disks, rectangles, rings, los yog honeycomb lug.

4. Sintering: Cov nias blanks yog sintered ntawm qhov kub thiab txias (nyob ib ncig ntawm 1400 degree) los tsim cov khoom siv ceramic.

5. Electrode Daim Ntawv Thov: Electrodes yog siv rau saum npoo ntawm cov khoom siv ceramic kom ua rau cov khoom siv hluav taws xob.

6. Resistance Sorting: Lub Cheebtsam undergo Resistance sorting los faib lawv raws li lawv cov nqi kuj.

7. Hlau Bonding: Nyob ntawm cov khoom kawg ntawm cov qauv, kev sib txuas ntawm cov hlau yog ua los txuas cov khoom sib txuas.

8. Rwb thaiv tsev Encapsulation: Cov khoom muaj nyob rau hauv cov khoom siv insulating rau kev tiv thaiv.

9. Kev sib dhos: Cov khoom sib dhos tau sib sau ua ke, thiab yog tias xav tau, lawv tau muab tso rau hauv cov khoom tiv thaiv.

10. Kev ntsuas qhov ntsuas hluav taws xob: Cov PTC thermistor sib dhos tau dhau los ntsuas qhov ntsuas hluav taws xob kom ntseeg tau tias lawv cov hluav taws xob muaj kev nyab xeeb.

11. Kev Ntsuas Kev Tiv Thaiv: Qhov kev tiv thaiv ntawm PTC thermistor yog raug tshuaj xyuas los xyuas lawv cov kev ua tau zoo.

12. Kev Xeem Kawg: Kev sim ua tiav yog ua los ntsuas kev ua haujlwm tag nrho ntawm PTC thermistors.

13. Ntim: PTC thermistor kuaj thiab pom zoo tau ntim rau cov khoom xa tuaj.

14. Cia: Cov hnab ntim PTC thermistor tau khaws cia rau hauv qhov chaw tsim nyog kom txog rau thaum lawv muab faib los yog siv rau hauv ntau daim ntawv thov.

PTC thermistor muaj qhov ntsuas kub-nyob ntawm kev sib raug zoo ntawm qhov tsis kam thiab kub, feem ntau hu ua Resistance-Temperature (RT) yam ntxwv. Tus yam ntxwv RT piav qhia qhov kev cia siab ntawm xoom-zog tsis kam ntawm PTC thermistor ntawm nws qhov kub thiab txias, nyob rau hauv qhov ntsuas qhov ntsuas.

Lub zero-fais fab tsis kam yog hais txog tus nqi tsis kam ntawm PTC thermistor thaum ntsuas ntawm qhov kub thiab txias, nrog rau lub zog siv qis heev, yog li qis qhov kev hloov pauv los ntawm lub zog dissipation tuaj yeem tsis saib xyuas. Qhov ntsuas xoom-lub zog tsis kam sawv cev rau tus nqi ntsuas ntawm qhov ntsuas kub ntawm 25 degree.

 

 

 

• Rmin: yam tsawg kawg nkaus kuj

• Tmin: Kub hauv Rmin

• Rtc: 2 npaug ntawm Rmin

• Tc:

Qhov tseem ceeb parameter uas qhia txog qhov zoo ntawm RT tus yam ntxwv yog qhov kub coefficient (), uas qhia txog qhov steepness ntawm RT nkhaus. Qhov kub coefficient ntau dua ( ) qhia tias PTC thermistor muaj kev nkag siab ntau dua rau kev hloov pauv kub, ua rau muaj txiaj ntsig PTC ntau dua. Hauv lwm lo lus, qhov kub siab coefficient txhais tau tias kev ua tau zoo dua thiab kev ua neej ntev dua rau PTC thermistor.

Qhov kub coefficient () ntawm PTC thermistor yog txhais raws li qhov kev hloov pauv ntawm qhov tsis kam los ntawm qhov kub hloov pauv. Nws tuaj yeem suav nrog cov qauv:=(log(R2) - log(R1)) / (T2 - T1)

Feem ntau, T1 yog coj raws li Tc + 15 degree, thiab T2 yog coj li Tc + 25 degree, qhov twg Tc yog Curie kub ntawm PTC thermistor.

 

VI yam ntxwv

 

Tus yam ntxwv Voltage-Current (VI), tseem hu ua tus yam ntxwv tam sim no-voltage lossis tsuas yog VI tus yam ntxwv, qhia txog qhov sib cuam tshuam ntawm qhov hluav taws xob thiab tam sim no hauv PTC thermistor thaum nws ncav cuag thermal sib npaug hauv qab hluav taws xob.

 

 

 

• Ik: Ua haujlwm tam sim no ntawm kev siv hluav taws xob Vk

• Ir: Residual tam sim no thaum siv Vmax

• Vmax: siab tshaj voltage

• VN: qhov voltage

• VD: Fais fab tuag

Tus yam ntxwv VI ntawm PTC thermistor feem ntau tuaj yeem muab faib ua peb thaj tsam:

Linear Region (0-Vk): Hauv cheeb tsam no, kev sib raug zoo ntawm qhov hluav taws xob thiab tam sim no ua raws li Ohm txoj cai, thiab tsis muaj qhov sib txawv ntawm qhov tsis sib xws. Nws tseem yog lub npe hu ua cheeb tsam tsis ua haujlwm vim tias PTC thermistor tsis pom muaj kev hloov pauv hauv nws qhov tsis kam.

Transition Region (Vk-Vmax): Hauv cheeb tsam no, lub npe hu ua kev hloov pauv lossis hloov chaw, qhov tsis kam ntawm PTC thermistor tau hloov pauv sai vim nws qhov cua sov. Raws li qhov hluav taws xob nce, qhov tam sim no txo ​​qis, ua rau PTC thermistor hloov los ntawm lub xeev tsis muaj zog mus rau lub xeev siab. Lub cheeb tsam no tseem raug hu ua cheeb tsam ua haujlwm.

Cheeb tsam tawg (VD thiab saum toj no): Hauv cheeb tsam no, lub npe hu ua qhov tawg lossis thaj tsam tripping, tam sim no nce nrog qhov nce hauv qhov hluav taws xob. Qhov tsis kam ntawm PTC thermistor nthuav tawm qhov nthuav tawm txo qis, ua rau muaj qhov hluav taws xob ntau dua rau cov hluav taws xob ntau dua. Raws li qhov tshwm sim, qhov kub ntawm PTC thermistor nce, ua rau muaj kev txo qis ntxiv. Thaum kawg, qhov no tuaj yeem ua rau thermal tawg lossis poob ntawm PTC thermistor.

Tus yam ntxwv VI yog ib qho tseem ceeb siv rau kev tiv thaiv overcurrent muab los ntawm PTC thermistors. Nws pab txiav txim siab tus cwj pwm ntawm lub thermistor nyob rau hauv qhov sib txawv voltage thiab tam sim no tej yam kev mob, ua kom muaj kev tiv thaiv zoo tiv thaiv tam sim no ntau dhau.

Cov yam ntxwv tam sim no-Lub Sij Hawm yog hais txog tus yam ntxwv ntawm PTC thermistor qhov twg tam sim no hloov pauv nrog lub sijhawm thaum siv hluav taws xob.

Thaum qhov hluav taws xob pib siv rau PTC thermistor, qhov tam sim no ntawm lub sijhawm ntawd hu ua Starting Current. Raws li PTC thermistor nce mus txog qhov sib npaug ntawm qhov sib npaug, qhov tam sim no uas tseem tshuav yog hu ua Residual Current.

Ntawm qhov ntsuas kub ib puag ncig, thaum pib tam sim no (kom ntseeg tau tias nws yog qhov ua haujlwm tam sim no) tau siv rau PTC thermistor, lub sijhawm siv rau qhov tam sim no kom txo qis rau 50% ntawm qhov pib tam sim no hu ua Lub Sijhawm Teb lossis Lub Sijhawm Teb. Cov yam ntxwv tam sim no yog ib qho tseem ceeb siv rau ntau yam kev siv ntawm PTC thermistor, xws li tsis siv neeg demagnetization, ncua kev pib, thiab kev tiv thaiv overload.