Bài giảng kỹ thuật cảm biến phần 4 : Cảm biến nhiệt độ
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Transcript of Bài giảng kỹ thuật cảm biến phần 4 : Cảm biến nhiệt độ
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Bi ging
K Thut Cm Bin (sensors)
1
Hoang Si Hong
----2011----
Faculty of Electrical Eng., Hanoi Univ. of Science and Technology (HUST),
Hanoi, VietNam
Hoang Si Hong-HUST
3
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Ngun tham kho
Note: Bi ging mn hc ny c tham kho, trch dn v lc dch t cc ngun sau:
Sch
- K thut o lng cc i lng in tp 1, 2- Phm Thng Hn, Nguyn Trng Qu.
- Cc b cm bin trong o lng-L Vn Doanh
- Cc b cm bin-Nguyn Tng Ph
- o lng in v cc b cm bin: Ng.V.Ho v Hong S Hng
- Sensor technology handbook (edited by JON WILSON)
- Elements of Electronic Instrumentation and Measurement (Prentice-Hall Company)
- Sch gii thch n v o lng hp php ca Vit Nam
Bi ging v website:
- Bi ging k thut cm bin-Hong S Hng-BKHN(2005)
- Bi ging Cm bin v k thut o:P.T.N.Yn, Ng.T.L.Hng BKHN (2010)
- Bi ging MEMs ITIMS BKHN
- Mt s bi ging v cm bin v o lng t cc trng i hc KT khc Vit Nam
- Website: sciendirect/sensors and actuators A and B
Hoang Si Hong-HUST 2
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Ni dung mn hc v mc ch
Ni dung Chapter 1: Khi nim chung v Cm bin (2b)
Chapter 2: Cm bin in tr (2b)
Chng 3: Cm bin o nhit (2b)
Chng 4: Cm bin quang (2b)
Chng 5: Cm bin tnh in (2b)
Chng 6: Cm bin Hall v ho in
Chng 6: Cm bin v PLC(1b)
Mc ch: nm c cu to, nguyn l hot ng v ng dng ca
cc loi cm bin thng dng trong cng nghip v i sng. Nm
c xu th pht trin chung ca cng ngh cm bin trn th gii.
Hoang Si Hong-HUST 3
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Hoang Si Hong-HUST 4
Chng 3: Cm bin o nhit
Ni dung Khi nim chung
Nhit k gin n
Cm bin cp nhit in (Thermocouple)
Cm bin nhit in tr (RTD)
Cm bin nhit da trn tnh cht ca diot v tranzito
Ho k
Surface acoustic wave (SAW) v dao ng thch anh
Bao nhiu ?
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Hoang Si Hong-HUST 5
Khi nim
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Hoang Si Hong-HUST 6
Khi nim
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Hoang Si Hong-HUST 7
Nhit k gin n dng cht rn
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Hoang Si Hong-HUST 8
Nhit k gin n dng cht lng
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Hoang Si Hong-HUST 9
Cm bin cp nhit in
Nguyn l:
- Hiu ng thomson: vi vt liu ng nht A, trn n c hai im phn bit
khc nhau l M v N c nhit tng ng l t1 v t2, th gia chng s
xut hin mt sut in ng emn = tch phn (t t1->t2) ca dt, trong
l h s vt liu thomson cho trc
- Hiu ng Peltier: hai vt liu Av B khc nhau tip xc vi nhau ti mtim no th xut hin mt sut in ng eAB(t)
M
(t1)
N
(t2)A
A Bt
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Hoang Si Hong-HUST 10
Cm bin cp nhit in
Nguyn l:
- Hiu ng seebeck: kt hp hai hiu ng ni trn -> xut hin sut in ng
nhit in eT(t) = tch phn t t1 n t2 ca (A B) dt + eKM(t) eJN(t)
- Trong A , B l h s vt liu thomson ca hai vt liu A, B tng ng.
t1 < t2 l nhit tng ng ti hai im khc nhau.
- Nu gi nhit mt u khng i bng khng C (0oC) (nhit u t
do) th xut hin sut in ng ra mt chiu u cn li (u lm vic,
nhit t) t l vi nhit : ET (t) = f(t) t1
M K
N J
t2
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Hoang Si Hong-HUST 11
Vt liu ch to
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Hoang Si Hong-HUST 12
Cu to
(hn im v cch li hnh vy c)
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Hoang Si Hong-HUST 13
Cu to
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Hoang Si Hong-HUST 14
Chng loi
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Hoang Si Hong-HUST 15
Chng loi
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Hoang Si Hong-HUST16
c tnh
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Hoang Si Hong-HUST 17
Cc nguyn nhn gy sai s
- Sai s do nhit u t do thay i. Khi khc , u t do c t mi
trng khng C, nhng trong thc t nhit u t do khc khng C
- Sai s do s thay i in tr ng dy, cp nhit hoc ch th
- Sai s do t khng ng v tr, hng hoc din tch tip xc qu b. Thng
thng ngi ta a chiu su ca cp nhit vo mi trng cn o khong
t5-10 ln so vi ng knh dy ca cp nhit.
- Hai dy cp nhit b m c th gy ra sai s ti 20% v in p ra tng gp 10
ln. Nu dy dn khng c v bc chng nhiu v t cm bin trong in
trng ca ng dy cao th (1-5 kV) th n s chu nh hng ca nhiu in
dung v sai s ln n vi %. Chm mt vo ngun 220 VAC sai s c th ln
n 10%.
- Can nhit b t mi hn cng gy ra sai s.
- Chn dy b sai cng c th gy sai s
- ng dng: o nhit , o dng tn s cao, hng chuyn ng, lu tc, p
sut nh..
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Hoang Si Hong-HUST 18
Mch o
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Hoang Si Hong-HUST 19
Mch o
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Hoang Si Hong-HUST 20
Mch o
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Hoang Si Hong-HUST 21
B nhit u t do
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Hoang Si Hong-HUST 22
B nhit u t do
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Hoang Si Hong-HUST 23
nh hng ca in tr mch o
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Hoang Si Hong-HUST 24
nh hng ca in tr mch o
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Hoang Si Hong-HUST 25
Cm bin nhit in tr
/N: l chuyn i c in tr thay i theo s thay i nhit ca n.
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Hoang Si Hong-HUST 26
Nhit in tr kim loi
Nhit in tr dy kim loi: thng c ch to t ng,platin v niken vi ng knh dy t 0.02-0.06 mm.
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Hoang Si Hong-HUST 27
Nhit in tr kim loi
Nhit in tr dy kim loi: thng c ch to t ng,platin v niken vi ng knh dy t 0.02-0.06 mm.
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Hoang Si Hong-HUST 28
Nhit in tr kim loi
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Hoang Si Hong-HUST 29
c tnh
- The accuracy of an RTD is significantly better than that of a thermocouple within an RTDs normal
temperature range of 184.44C (300F) to 648.88C (1200F).
Cu tuyn tnh nhng s dng nhit thp
Platinum is the best metal for RTD elements for three reasons.It follows a very linear resistance-to temperature relationship;
it follows its resistance-to-temperature relationship in a highly
repeatable
manner over its temperature range; and it has the widesttemperature range among the metals used to
make RTDs. Platinum is not the most sensitive metal;however, it is the metal that offers the best longterm stability.
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Hoang Si Hong-HUST 30
Pt100
S khc nhau gia Pt100 (100 , ti 0oC), 500 v Pt1000 ?
The most common type (PT100) has a resistance of 100ohms at 0 C and 138.4 ohms at 100 C. There are also
PT1000 sensors that have a resistance of 1000 ohms at 0 C
and 1385 ohms ti 100C.
Ti sao Platinum c s dng ch yu ch to RTD: biv n c th hot ng n nh trong thi gian di ti mi
trng c nhit cao. Hn na Pt l s la chn tt hn so
vi Cu hoc Ni bi v s tr v mt ho hc ca n v c
kh nng chng li s xi ho .
Mch o c th dng ngun dng, mch cu hoc time 555
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Hoang Si Hong-HUST 31
Cu to
The Standard Platinum Resistance
Thermometer is fragile and used
only in laboratory environments
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Hoang Si Hong-HUST 32
Mt s kiu nhit in tr
There are three main classes of Platinum Resistance Thermometers (PRTs): Standard
Platinum Resistance Thermometers (SPRTs), Secondary Standard Platinum Resistance
Thermometers (Secondary SPRTs), and Industrial Platinum Resistance Thermometers
(IPRTs). Table 32.6 presents information about each. (Rugged :chc chn, Fragile: d
gy)
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Hoang Si Hong-HUST 33
RTD kiu mng mng
The temperature range of thin film platinum elements is 50C (58F) to 400C (752F);
accuracy is from 0.5C (0.9F) to 2.0C (3.6F). The most common thin-film element has
a 100-W ice point resistance and a temperature coefficient of 0.00385C.
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Hoang Si Hong-HUST 34
Cng ngh sn xut RTD mng mng
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Hoang Si Hong-HUST 35
Nhit in tr bn dn (NTC-PTC)
large negative temperature coefficient of resistance (NTC)
large positive temperature coefficient of resistance (PTC)
A- hng s ph thuc vo
tnh cht vt l ca bn
dn, kch thc v hnh
dng ca in tr.
- hng s ph thuc vo
tnh cht vt l ca bn
dn
T- nhit tuyt i
e- c s lgarit t nhin
h s nhit ln hn
RTD nhng c tnh phi
tuyn
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Hoang Si Hong-HUST 36
Cu to nhit in tr bn dn (NTC-PTC)
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Hoang Si Hong-HUST 37
Sai s v ng dng
Sai s ca nhit k in tr ch yu l do s thay i in trng dy khi nhit mi trng thay i.
in tr ng dy c th t ti 5 trong khi in tr cachuyn i t vi trm .
Ngoi ra dng in chy qua in tr gy nng cng lm cho intr tng v gy ra sai s. Thng chn dng khong vi mA .
ng dng ca RTD,NTD.. ch yu o nhit , o cc i lngkhng in nh o di chuyn, p sut, nng mt s cht kh..
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Hoang Si Hong-HUST 38
Mch o v chng sai s
B in tr dy khi s dng ngun p
B in tr dy khi s dng ngun dng
Ti sao l nhit in tr 2, 3 v 4 dy ?
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Hoang Si Hong-HUST 39
Mch o kiu timer 555
Chu k T ca nhp xung ng ra ca time t l vi s bin i R1 (Rx) khi nhit thay i
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Hoang Si Hong-HUST 40
Mch o dng ngun dng
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Hoang Si Hong-HUST 41
Cm bin nhit da trn tnh cht bn dn
ca it v tranzito
c tnh ca it ph thuc vo nhit . Da trn c tnh ngi ta onhit hoc s thay i nhit ca mt i tng no . Tuy nhin s
ph thuc ny khng tuyn tnh v khng tin cy, do vy ngi ta s
dng tnh cht ph thuc in p gia bazo-emito ca mt tranzito vo
nhit khi duy tr dng in colecto (Ic) khng i.
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Hoang Si Hong-HUST 42
Nguyn l
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Hoang Si Hong-HUST 43
Nguyn l
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Hoang Si Hong-HUST 44
B phi tuyn
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Hoang Si Hong-HUST 45
IC LM35 hoc LM335
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Hoang Si Hong-HUST 46
AD590 (Tham kho: bai giang N.N. Tan v Ng.V.Ky)
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Hoang Si Hong-HUST 47
Ho quang k bc x ton phn
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Hoang Si Hong-HUST 48
Ho quang k bc x ton phn
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Hoang Si Hong-HUST 49
Ho quang k bc x ton phn
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Hoang Si Hong-HUST 50
Ho quang k bc x ton phn
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Hoang Si Hong-HUST 51
Ho k quang in
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Hoang Si Hong-HUST 52
Ho k quang in
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Hoang Si Hong-HUST 53
Ho k quang in
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Hoang Si Hong-HUST 54
Ho k mu sc
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Hoang Si Hong-HUST 55
o nhit vi cm bin sng m b mt
(SAW-surface acoustic wave)
Content Piezoelectric behavior can be manifested in two distinct ways. Direct piezoelectric effect occurs when a piezoelectric material becomes
electrically charged when subjected to a mechanical stress and conversion ofmechanical energy to electrical energy.
Converse piezoelectric effect occurs when the piezoelectric material becomesstrained when placed in an electric field and conversion of electrical energy tomechanical energy
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Hoang Si Hong-HUST56
o nhit vi cm bin sng m b mt
(SAW-surface acoustic wave)
BWnull
0 dB
M Hz
insertion loss
center frequency (f0)
BW3dB
3dB
Frequency Response
Fig. 7. Temperature dependence of the center frequency of two-port SAW
resonators using AlN/3C-SiC and AlN/Si structures.
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Hoang Si Hong-HUST57
o nhit vi cm bin sng m b mt
(SAW-surface acoustic wave)
BWnull
0 dB
M Hz
insertion loss
center frequency (f0)
BW3dB
3dB
Frequency Response
Fig. 7. Temperature dependence of the center frequency of two-port SAW
resonators using AlN/3C-SiC and AlN/Si structures.
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Wireless SAW temperature sensor
Hoang Si Hong-HUST 58
Principle
- Depending on changes in temperature, the shifts (time
position and phase angle) of the reflection peaks were
modulated.
- The phase angle shift was used to evaluate the sensitivity
because it provides a much higher resolution than the
time shift of the reflection peak.
- All three reflectors showed the same sign of the phase
shifts because the temperature effects are equal on all
the reflectors
Relation between phase different () and temperature (T)
time
2-1
TDC: the temperature coefficient of delay of piezoelectric material
T: measurement temperature
Tref: reference temperature
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Cm bin nhit thch anh
Hoang Si Hong-HUST 59
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Cu hi v Lu
Hoang Si Hong-HUST 60
-Nguyn l?
- ng dng?
- B sai s?
- Tnh ton thit k mch o?