Bai Tncstd 1

7/21/2019 Bai Tncstd 1

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BAI TH NGHIEM 1

PHN A: NG DUNG MATLAB PHAN TCHCAC HE THONG IEU KHIEN T ONG

I. MUC CH :Matlab la mot trong nhng phan mem thong dung nhat dung e phan tch, thiet ke va

mo phong cac he thong ieu khien t ong. Trong bai th nghiem nay, sinh vien s dung caclenh cua Matlab e phan tch he thong nh xet tnh on nh cua he thong, ac tnh qua o, saiso xac lap

II. CHUAN B :e thc hien cac yeu cau trong bai th nghiem nay, sinh vien can phai chuan b ky

trc cac lenh c ban cua Matlab. Khi khi ong chng trnh Matlab 6.5, ca so CommandWindow xuat hien vi dau nhac lenh >>. e thc hien cac lenh, sinh vien se go lenh tban phm theo sau dau nhac nay.

Sinh vien can tham khao phan phu luc chng 2 (trang 85) trong sach Ly thuyet ieukhien t ong (tac gia Nguyen Th Phng Ha Huynh Thai Hoang) e hieu ro cac lenh cban ve nhan chia a thc, bieu dien ham truyen he thong va ket noi cac khoi trong he thong.

Ngoai ra, e phan tch ac tnh cua he thong, sinh vien can phai hieu ky cac lenh sau:

bode(G) : ve bieu o Bode bien o va pha cua he thong co ham truyen G nyquist(G) : ve bieu o Nyquist he thong co ham truyen G rlocus(G): ve QNS he thong hoi tiep am n v co ham truyen vong h G step(G) : ve ap ng nac cua he thong co ham truyen G hold on : gi hnh ve hien tai trong ca so Figure. Lenh nay hu ch khi ta can ve

nhieu bieu o trong cung mot ca so Figure. Sau khi ve xong bieu o th nhat, ta golenh hold on e gi lai hnh ve sau o ve tiep cac bieu o khac. Cac bieu o luc sause ve e len bieu o th nhat trong cung mot ca so Figurenay. Neu khong muon gihnh na, ta go lenh hold off.

grid on : ke li tren ca so Figure. Neu khong muon ke li, ta go lenh grid off. plot(X,Y): ve o th vector Y theo vector X

V du : Ve o th y = x2vi x = -10 10>> X = -10:0.1:10; % tao vector X tu -10 10 voi khoang cach 0.1

>> Y = X.*X; % tinh y = x*x>> plot(X,Y); % ve do thi y = x*x

subplot(m,n,p) : chia Figure thanh (mxn) ca so con va thao tac tren ca so con thp.V du : Chia Figure thanh 2 ca so con, sau o ve Y len ca so th 1 va Z len ca so th2

>> subplot(2,1,1), subplot(Y); % ve Y len cua so thu 1>> subplot(2,1,2), subplot(Z); % ve Z len cua so thu 2

Chu y: sinh vien nen tham khao phan Help cua Matlab e nam ro chc nang va cu

phap cua mot bang cach go vao dong lenh : help


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III. TH NGHIEM :III.1. Tm ham truyen tng ng cua he thong: Muc ch:

Giup sinh vien lam quen vi cac lenh c ban e ket noi cac khoi trong mot he thong.

Th nghiem:Bang cach s dung cac lenh c ban conv, tf, series, parallel, feedback phan phu

luc chng 2 (trang 85) trong sach Ly thuyet ieu khien t ong, tm bieu thc ham truyentng ng G(s) cua he thong sau :

2

1 11 , 2 , 3 , 1 2

( 3)( 5) 2 8

s sG G G H s

s s s s s

+= = = = +

+ + + +

Hng dan:Bc au tien nhap ham truyen cho cac khoi G1, G2 dung lenh tf. Sau o, tuy theo

cau truc cac khoi mac noi tiep, song song hay hoi tiep ma ta go cac lenh series, parallelhayfeedbacktng ng e thc hien viec ket noi cac khoi vi nhau. Trong bao cao, ch ro trnht viec thc hien cac lenh nay.

V du :>> G1 = tf([1 1],conv([1 3],[1 5])) % nhap ham truyen G1>> G2 = tf([1 0],[1 2 8]) % nhap ham truyen G2

>> G3 = tf(1,[1 0]) % nhap ham truyen G3>> H1 = tf([1 2],1) % nhap ham truyen H1>> G13 = parallel(G1,G3) % tinh ham truyen tuong duong cua G1, G3

Tiep tuc tnh tng t cho cac khoi con lai.

III.2. Khao sat he thong dung bieu o Bode: Muc ch:

T bieu o Bode cua he h G(s), ta tm c tan so cat bien, o d tr pha, tan so catpha, o d tr bien cua he thong h. Da vao ket qua tm c e xet tnh on nh cua hethong hoi tiep am n v vi ham truyen vong h la G(s).

Th nghiem:Khao sat he thong phan hoi am n v co ham truyen vong h:

2( )

( 0.2)( 8 20)

KG s

s s s=

+ + +

a. Vi K = 10, ve bieu o Bode bien o va pha he thong tren trong khoang tan so(0.1, 100).

b. Da vao bieu o Bode, tm tan so cat bien, o d tr pha, tan so cat pha, o d trbien cua he thong. Lu bieu o Bode thanh file *.bmp e chen vao file word phuc

G1

G3

_+

G2

H1

_


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vu viet bao cao. Chu y phai ch ro cac gia tr tm c len bieu o Bode trong file*.bmp.

c. He thong tren co on nh khong, giai thch.d. Ve ap ng qua o cua he thong tren vi au vao ham nac n v trong khoang

thi gian t = 0 10s e minh hoa ket luan cau c. Lu hnh ve ap ng nay e vietbao cao.

e. Vi K = 400, thc hien lai cac yeu cau cau a d. Hng dan:

e ve bieu o Bode cua G trong khoang tan so (a,b) ta nhap lenh bode(G,{a,b}). Golenh grid one ke li hnh ve.

V du : Nhap lenh ve bieu o Bode cua G(s) khi K=10 nh sau:>> TS = 10 % nhap tu so cua G(s)>> MS = conv([1 0.2],[1 8 20]) % nhap mau so cua G(s)>> G = tf(TS,MS) % nhap ham truyen G(s)>> bode(G,{0.1,100}) % ve bieu do Bode cua G(s) trong khoang (0.1,100)>> grid on % ke luoi

Khi can xac nh iem nao tren bieu o Bode ta ch viec nhap chuot vao v tr o. Luco, gia tr bien o hay goc pha se hien th ra nh hnh ve:

e chen chu thch len hnh veta vao menu Insert/ Text sauo go ky t vao v tr can chuthch.

e lu hnh ve ta vao menu

File/ Export. Mot ca soExport hien ra. Trong mucSave as type ta chon mucBitmap files (*.bmp). Luc nay,ta lu file di dang file *.bmp.Ngoai ra ta cung co the ludi dang file *.jpg hay *.wmf.

e ve ap ng nac cua he thong kn trong khoang thi gian (0, T) ta nhap lenhstep(Gk,T),trong o Gkla ham truyen vong kn. V ham truyen G(s) tren la ham truyenvong h nen trc tien ta phai tnh ham truyen vong kn bang lenh Gk = feedback(G,1) sauo mi nhap lenh step(Gk,T). Tien hanh lu hnh ve giong nh ca so cua bieu o Bode.

III.3. Khao sat he thong dung bieu o Nyquist: Muc ch:

T bieu o Nyquist cua he h G(s), ta tm o d tr bien, o d tr pha cua he thongvong kn hoi tiep am n v. Da vao ket qua tm c e xet tnh on nh cua he thong kn.

Th nghiem:Khao sat he thong phan hoi am n v co ham truyen vong h nh phan III.2:


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2( )

( 0.2)( 8 20)

KG s

s s s=

+ + +

a. Vi K = 10, ve bieu o Nyquist cua he thong.b. Da vao bieu o Nyquist, tm o d tr pha, o d tr bien cua he thong. So sanh

vi ket qua phan III.2. Lu bieu o Nyquist thanh file *.bmp va ch ro cac giatr tm c tren len bieu o Nyquist.

c. He thong tren co on nh khong. Giai thch. So sanh vi ket qua phan III.2.d. Vi K = 400, thc hien lai cac yeu cau cau a c.

III.4. Khao sat he thong dung phng phap QNS: Muc ch:

Khao sat ac tnh cua he thong tuyen tnh co he so khuech ai K thay oi, tm gia trgii han Kghcua K e he thong on nh.

Th nghiem:He thong hoi tiep am n v co ham truyen vong h:

2

( ) , 0( 3)( 8 20)

KG s K

s s s

= + + +

a. Ve QNS cua he thong. Da vao QNS, tm Kghcua he thong, ch ro gia tr naytren QNS. Lu QNS nay thanh file *.bmp e viet bao cao.

b. Tm K e he thong co tan so dao ong t nhien 4n

= .

c. Tm K e he thong co he so tat 0.7= .

d. Tm K e he thong co o vot lo POT = 25%e. Tm K e he thong co thi gian xac lap (tieu chuan 2%) 4

xlt s=

Hng dan:Khi nhap ham truyen cho G ta khong nhap tham so K trong lenh tf.Dung lenh grid on

e ke li:>> TS = 1 % nhap tu so cua G(s) khong chua K>> MS = conv([1 3],[1 8 20]) % nhap mau so cua G(s)>> G = tf(TS,MS) % nhap ham truyen G(s)>> rlocus(G) % ve quy dao nghiem so>> grid on % ke luoi

e tm Kghta nhap chuot vao v tr cat nhau gia QNS vi truc ao. Luc nay, gia tr Kse hien th len nh tren hnh ve sau:


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Gain : gia tr o li K tai v tr nhap chuot (gia tr K can tm). Pole : cc cua he thong vong kn tng ng vi gia tr K Dampling : he so tat Overshoot : o vot lo Frequency : tan so dao ong t nhien

(A) : vong tron cac iem co cung tan so dao ong t nhien 4n

=

(B) : ng thang cac iem co cung he so tat 0.68=

(C) : ng thang cac iem co cung 4 4 1xl nn

t = = =

Muon tm K e he thong co tan so dao ong t nhien 4n

= , ta nhap chuot vao v tr

giao iem cua QNS vi vong tron 4n

= (vong tron (A)). Chon giao iem gan truc ao (giao

iem M) e gia tr K nay lam he thong co tnh dao ong.e he thong co 0.7= ta nhap chuot tai v tr giao iem (N) cua QNS vi ng

thang 0.7= (ng thang (B)). Ta co the chon gan ung ng thang 0.68= nh tren

hnh ve.

Tng t cho2

exp( ) 25% 0.41

POT

= = =

Vi4

4 1xl n

n

t s

= = = . Do o muon tm K e he thong co 4xl

t = ta nhap

chuot vao v tr giao iem (P) cua QNS vi ng thang 1n

= (ng thang (C)).


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III.5. anh gia chat lng cua he thong: Muc ch:

Khao sat ac tnh qua o cua he thong vi au vao ham nac e tm o vot lo va sai soxac lap cua he thong.

Th nghiem:Vi he thong nh phan III.4 :a. Vi gia tr K = Kghtm c tren, ve ap ng qua o cua he thong vong kn vi

au vao ham nac n v. Kiem chng lai ap ng ngo ra co dao ong khong?

b. Vi gia tr K tm c cau d.phanIII.4, ve ap ng qua o cua he thong vongkn vi au vao ham nac n v trong khoang thi gian t = 0 5s. T hnh ve, tmo vot lo va sai so xac lap cua he thong. Kiem chng lai he thong co POT = 25%khong? Lu hnh ve nay e viet bao cao.

c. Vi gia tr K tm c cau e.phan III.4, ve ap ng qua o cua he thong vongkn vi au vao ham nac n v trong khoang thi gian t = 0 5s. T hnh ve, tmo vot lo va sai so xac lap cua he thong. Kiem chng lai he thong co 4

xlt s=

khong? Lu hnh ve nay e viet bao cao.

d. Ve 2 ap ng qua o cau b.va c. tren cung 1 hnh ve. Chu thch tren hnh ve apng nao la tng ng vi K o. Lu hnh ve nay e viet bao cao.

Hng dan:Ham truyen phan III.4 la ham truyen vong h nen trc tien ta phai chuyen sang

ham truyen vong kn bang lenh Gk = feedback(426*G,1)(vi K = Kgh= 426). e ve ap ngnac trong khoang thi gian (0, T) ta nhap lenh step(Gk,T).

ap ng qua o hien th nhhnh ve ke ben. e hien th cac chuthch ve o vot lo, thi gian xac lapta nhap chuot phai. Mot menu hien

ra vi:Peak Response : tm POT.Settling Time : tm

xlt .

Rise Time : tm thi gian len.Co the chon Grid e de

dang cho viec tnh toan cac gia tr.Sau khi ve xong hnh th

nhat, s dung lenh hold on e gihnh, sau o neu tiep tuc ve hnh thhnh lan sau se khong xoa mat hnh

ve th nhat.


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PHN B: NG DUNG SIMULINK MO PHONGVA ANH GIA CHAT LNG HE THONG

I. MUC CH :SIMULINK la mot cong cu rat manh cua Matlab e xay dng cac mo hnh mot cach

trc quan va de hieu. e mo ta hay xay dng he thong ta ch can lien ket cac khoi co santrong th vien cua SIMULINK lai vi nhau. Sau o, tien hanh mo phong he thong e xem xetanh hng cua bo ieu khien en ap ng qua o cua he thong va anh gia chat lng hethong.

II. CHUAN B :e thc hien cac yeu cau trong bai th nghiem nay, sinh vien can phai chuan b ky va

hieu ro cac khoi c ban can thiet trong th vien cua SIMULINK. Sau khi khi ong Matlab6.5, ta go lenh simulinkhoac nhan vao nut simulink tren thanh cong cu th ca so SIMULINKhien ra:

2 th vien chnh ap dungtrong bai th nghiem nay

Cac th vien con trongth vien Simulink. Kchchuot vao cac th viencon nay se hien ra cackhoi can thiet dung exay dng he thong


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II.1. Cac khoi c s dung trong bai th nghiem:a. Cac khoi nguon tn hieu vao (source):

Khoi Step( th vien Simulink \ Sources) co chc nang xuat ra tnhieu ham nac. Double click vao khoi nay e cai at cac thong so: Step time : khoang thi gian ngo ra chuyen sang mc Final value

ke t luc bat au mo phong. Cai at gia tr nay bang 0. Initial value : Gia tr ban au. Cai at bang 0. Final value : Gia tr luc sau. Cai at theo gia tr ta muon tac ong

ti he thong. Neu la ham nac n v th gia tr nay bang 1. Sample time : thi gian lay mau. Cai at bang 0.

Khoi Signal Generator ( th vien Simulink \ Sources) la bo phattn hieu xuat ra cac tn hieu song sin, song vuong, song rang ca va

ngau nhien (cai at cac dang song nay trong muc Wave form).

b. Cac khoi tai thiet b khao sat ngo ra (sink):

Khoi Mux( th vien Simulink \ Signals Routing) la bo ghep kenhnhieu ngo vao 1 ngo ra, t ngo ra nay ta a vao Scopee xem nhieutn hieu tren cung mot ca so. Double click vao khoi nay e thay oi

so kenh au vao (trong muc Number of inputs)

Khoi Scope( th vien Simulink \ Sinks) la ca so xem cac tn hieutheo thi gian, t le xch cua cac truc c ieu chnh t ong e quansat tn hieu mot cach ay u.

Khoi XY Graphdung e xem tng quan 2 tn hieu trong he thong(quan sat mat phang pha).

c. Cac khoi x ly khoi ong hoc :

Khoi Sum ( th vien Simulink \ Math Operations) la bo tong(cong hay tr) cac tn hieu, thng dung e lay hieu so cua tn hieuat vi tn hieu phan hoi. Double click e thay oi dau cua bo tong.

Khoi Gain( th vien Simulink \ Math Operations) la bo t le. Tnhieu sau khi qua khoi nay se c nhan vi gia tr Gain. Double clicke thay oi gia tr o li Gain.

Khoi Transfer Fcn ( th vien Simulink \ Continuous) la hamtruyen cua he tuyen tnh. Double click e thay oi bac va cac he socua ham truyen. Cai at cac thong so:


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Numerator : cac he so cua a thc t so Denominator : cac he so cua a thc mau so

Khoi Relay( th vien Simulink \ Discontinuities) la bo ieu khienrle 2 v tr co tre (con goi la bo ieu khien ON-OFF). Cac thong so : Switch on point : neu tn hieu au vao ln hn gia tr nay th ngo

ra cua khoi Relaylen mc on Switch off point : neu tn hieu au vao nho hn gia tr nay th ngo

ra cua khoi Relayxuong mc off Output when on : gia tr cua ngo ra khi mc on Output when off : gia tr cua ngo ra khi mc offNeu tn hieu au vao nam trong khoang (Switch on point, Switch offpoint) th gia tr ngo ra gi nguyen khong oi.

Khoi PID controller ( th vien Simulink Extras \ AdditionalLinear) la bo ieu khien PID vi ham truyen

( ) IP D

KPID s K K s

s

= + +

P

K : he so t le (proportional term)

I

K : he so tch phan (integral term)

D

K : he so vi phan (derivative term)

Khoi Saturation ( th vien Simulink \ Discontinuities) la mot khaubao hoa. Cac thong so cai at:

Upper limit : gii han tren. Neu gia tr au vao ln hn Upperlimitth ngo ra luon bang gia tr Upper limit

Lower limit : gii han di. Neu gia tr au vao nho hn Lowerlimitth ngo ra luon bang gia tr Lower limit

Khau bao hoa dung e the hien gii han bien o cua cac tn hieutrong thc te nh : ap ra cc ai cua bo ieu khien at vao oi tng,ap nguon

II.2. Cac bc tien hanh e xay dng mot ng dung mi trong SIMULINK: Sau khi khi ong Matlab, go lenh simulinkhoac nhan vao nut simulink tren thanh cong

cu th ca so SIMULINK hien ra (nh hnh ve Trang 1) Trong ca so SIMULINK, vao menu File / New e m ca so cho mot ng dung mi.

Kch chuot vao cac th vien a gii thieu muc II.1e chon khoi can tm. Kch chuot traivao khoi nay, sau o keo va tha vao ca so ng dung va mi tao ra. Double click vaokhoi nay e cai at va thay oi cac thong so.

Co the nhan so lng cac khoi bang cach dung chc nang Copyva Paste. Kch chuot trainoi cac ngo vao / ra cua cac khoi e hnh thanh s o he thong.

Co the di mot hoac nhieu khoi t v tr nay en v tr khac bang cach nhap chuot e choncac khoi o va keo en v tr mi. Dung phm Deletee xoa cac phan khong can thiethay b sai khi chon.


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Co the viet chu thch trong ca so ng dung bang cach double click vao mot v tr trong va

go cau chu thch vao. Vao menu Format / Fonte thay oi kieu ch. Nh vay, mo hnh he thong a xay dng xong. Bay gi tien hanh mo phong he thong

bang cach vao menu Simulation / Simulation Parameters e cai at cac thong so mophong. Ca so Simulation Parameters hien ra nh sau:

Start time : thi iem bat au mophong. Mac nh chon bang 0.

Stop time : thi iem ket thuc mophong. Gia tr nay chon theo actnh cua he thong. Neu he thongco thi hang ln th gia tr Stoptime cung phai ln e quan sathet thi gian qua o cua hethong.

Cac thong so con lai chon macnh nh hnh ke ben.

Chay mo phong bang cach vao menu Simulation / Start.Khi thi gian mo phong banggia tr Stop timeth qua trnh mo phong dng lai. Trong qua trnh mo phong, neu ta muondng na chng th vao menu Simulation / Stop.

III. TH NGHIEM:III.1. Khao sat mo hnh he thong ieu khien nhiet o:III.1.a. Khao sat he h, nhan dang he thong theo mo hnh Ziegler-Nichols: Muc ch:ac trng cua lo nhiet la khau quan tnh nhiet. T khi bat au cung cap nang lng

au vao cho lo nhiet, nhiet o cua lo bat au tang len t t. e nhiet o lo at ti gia trnhiet o can nung th thng phai mat mot khoang thi gian kha dai. ay chnh la ac tnhquan tnh cua lo nhiet. Khi tuyen tnh hoa mo hnh lo nhiet, ta xem ham truyen cua lo nhietnh la mot khau quan tnh bac 2 hoac nh la mot khau quan tnh bac nhat noi tiep vi khautre. Trong bai th nghiem nay ta xem mo hnh lo nhiet nh la mot khau quan tnh bac 2.

Trong phan nay, sinh vien se khao sat khau quan tnh bac 2 cho trc. Dung phngphap Ziegler-Nichols nhan dang he thong sau o xay dng lai ham truyen. So sanh gia tr cacthong so trong ham truyen va tm c vi khau quan tnh bac 2 cho trc nay.

Sinh vien tham khao Bai th nghiem 5e hieu ro phng phap Ziegler-Nichols. Th nghiem:

Dung SIMULINK xay dng mo hnh he thong lo nhiet vong h nh sau:


11/18

Step: la tn hieu ham nac the hien phan tram cong suat cung cap cho lo nhiet.Gia tr cua ham nac t 01 tng ng cong suat cung cap 0%100%

Transfer Fcn Transfer Fcn1 : mo hnh lo nhiet tuyen tnh hoa.

a. Chnh gia tr cua ham nac bang 1 e cong suat cung cap cho lo la 100% (Step time =

0, Initial time = 0, Final time = 1). Chnh thi gian mo phong Stop time= 600s. Mophong va ve qua trnh qua o cua he thong tren.

b. Tren hnh ve cau tren, ve tiep tuyen tai iem uon e tnh thong so L va T theo nhhng dan trong Bai th nghiem 5. Ch ro cac gia tr nay tren hnh ve. So sanh gia trL, T va tm c vi gia tr cua mo hnh lo nhiet tuyen tnh hoa.

Hng dan:Sau khi chay xong mo phong, e xem qua trnh qua o cua tn hieu ta double click vao

khoi Scope. Ca so Scope hien ra nh sau:

V ca so Scope ch co the xem ap ng hoac in trc tiep ra may in nhng khong lu

hnh ve thanh file *.bmp c nen ta phai chuyen Scopenay sang ca so Figuree lu. Thchien ieu nay bang cach nhap chuot vao o Parameters.Ca so Parametershien ra, nhapchuot vao trang Data history va tien hanh cai at cac thong so nh hnh ben di:

Print :In trc tiep hnh

ve ra may in

Parameters : cai atthong so cho scope

Autoscale : chnh t lexch t ong e xemtoan bo cac tn hieu

Bo dau chon trong muc

nay e xem toan boua trnh ua o

Chon muc nay e chophep tn hieu c luvao bien tenScopeData, va kieuformat la Structure with


12/18

Tien hanh chay mo phong lai e tn hieu lu vao bien ScopeData. Chu y neu sau khikhai bao ma khong tien hanh chay mo phong lai th tn hieu se khong lu vao bienScopeData mac du tren ca so Scope van co hnh ve.

Sau o, vao ca so Command Window nhap lenh sau:>> plot(ScopeData.time, ScopeData.signals.values) %ve dap ung>> grid on %ke luoi

Luc nay ca so Figurehien ra vi hnh ve giong nh hnh ve ca so Scope.Vaomenu Insert/ Line, Insert/ Texte tien hanh ke tiep tuyen va chu thch cho hnh ve. Ketqua cuoi cung nh hnh ben di :

Vao menu [File][Export] e lu thanh file *.bmp nh Bai th nghiem 1.

III.1.b. Khao sat mo hnh ieu khien nhiet o ON-OFF: Muc ch:

Khao sat mo hnh ieu khien nhiet o ON-OFF, xet anh hng cua khau rle co tre.

Th nghiem:Xay dng mo hnh he thong ieu khien nhiet o ON-OFF nh sau:


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Trong o: Tn hieu at au vao ham nac u(t) = 100 (nhiet o at 100oC)

Khoi Relayla bo ieu khien ON-OFF. Gia tr o li khoi Gain = 150 dung e khuech ai tn hieu ngo ra khoi Relay

e quan sat cho ro. Lu y rang gia tr nay khong lam thay oi cau truc cua hethong ma ch ho tr viec quan sat tn hieu.

a. Chnh thi gian mo phong Stop time= 600s e quan sat c 5 chu ky ieu khien.Khao sat qua trnh qua o cua he thong vi cac gia tr cua khau Relaytheo bang sau:

Vung tre( Switch on /off point )

Ngo ra cao(Output when on)

Ngo ra thap(Output when off)

+1 / -1 1(cong suat 100%) 0(cong suat 0%)+5 / -5 1(cong suat 100%) 0(cong suat 0%)

+10 / -10 1(cong suat 100%) 0(cong suat 0%)+20 / -20 1(cong suat 100%) 0(cong suat 0%)

b. Tnh sai so ngo ra so vi tn hieu at va thi gian ong ngat ng vi cac trng hp

cua khau Relay cau a theo bang sau:

Vung tre e1 -e2 Chu ky ong ngat (s)+1 / -1

+5 / -5+10 / -10+20 / -20

Nhan xet s anh hng cua vung tre en sai so ngo ra va chu ky ong ngat cuakhau Relay (khoang thi gian ngo ra khau Relaythay oi 1 chu ky).

c. Lu qua trnh qua o cua trng hp vung tre (+5 / -5) e viet bao cao. Tren hnh ve

ch ro 2 sai so +e1 / -e2 quanh gia tr at va chu ky ong ngat.d. e sai so cua ngo ra xap x bang 0 th ta thay oi gia tr vung tre bang bao nhieu? Chu

ky ong ngat luc nay thay oi nh the nao? Trong thc te, ta thc hien bo ieu khienON-OFF nh vay co c khong? Tai sao? Vung tre la chon bang bao nhieu la hply. Hay giai thch s la chon nay.

Hng dan:

Khi ieu khien ON-OFF , ngo ra cua he thong co dang dao ong quanh gia tr at, saiso cua no c anh gia qua bien o cua sai lech nhiet o: e = at Phan hoikhi hethong co dao ong on nh. Bao cao hai gia tr sai lech dng +e1 (ln hn) va am -e2(nho hn) so vi tn hieu at.

Gia tr vung tre phai la chon sao cho dung hoa sai so ngo ra va chu ky ong ngat.Neu vung tre nho th sai so ngo ra nho nhng chu ky ong ngat se tang len lam giam tuoi thobo ieu khien ON-OFF.


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III.1.c. Khao sat mo hnh ieu khien nhiet o dung phng phap Ziegler-Nichols (ieukhien PID): Muc ch:

Khao sat mo hnh ieu khien nhiet o dung bo ieu khien PID, cac thong so cua boPID c tnh theo phng phap Ziegler-Nichols. T o so sanh chat lng cua he thong 2bo ieu khien PID vi bo ieu khien ON-OFF.

Th nghiem:Xay dng mo hnh he thong ieu khien nhiet o PID nh sau:

Trong o: Tn hieu at au vao ham nac u(t) = 100 ( tng trng nhiet o at 100oC)

Khau bao hoa Saturation co gii han la upper limit = 1, lower limit = 0(tng trng ngo ra bo ieu khien co cong suat cung cap t 0% en 100%).

Bo ieu khien PID co cac thong so can tnh toan.

Transfer Fcn Transfer Fcn1 : mo hnh lo nhiet tuyen tnh hoa.

a. Tnh gia tr cac thong so KP, KI, KDcua khau PID theo phng phap Ziegler-Nichols t

thong so L va T tm c phan III.1.a.b. Chay mo phong va lu ap ng cua cac tn hieu Scope e viet bao cao. Co the chon

lai Stop timecho phu hp. Trong hnh ve phai chu thch ro ten cac tn hieu.c. Nhan xet ve chat lng ngo ra 2 phng phap ieu khien PID va ON-OFF.

Hng dan:Cach tnh cac thong soKP, KI, KD cua khau PID theo phng phap Ziegler-Nichols

nh sau:

( ) IP D

KPID s K K s

s= + +

Vi:1.2

, 0.52

PP I D P

KT

K K K K LLK L

= = =

Trong o L, T, K la cac gia tr a tm c phan III.1.a.Chu y, gia tr K a chotrc mo hnh ham truyen lo nhiet K = 300.


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III.2. Khao sat mo hnh ieu khien toc o, v tr ong c DC:Trong phan nay, sinh vien tm hieu cach xay dng mo hnh ong c t ham truyen mo

ta ong c DC. Sau o, khao sat mo hnh ieu khien toc o va v tr ong c DC vi bo ieukhien PID.

Sinh vien tham khao Bai th nghiem 4e biet ro phng trnh mo ta ong c DC. Tphng trnh mo ta ong c, ta co s o khoi bieu dien mo hnh ong c DC nh sau:

Trong o:

Phan ng : R = 1, L = 0.03H => Tdt= 0.03s. Ce : hang so ien t, Ce = 0.2 V.s / rad M : Momen ong c, Mc : momen can U : gia tr ien ap at vao ong c J : momen quan tnh cua cac phan chuyen ong, J = 0.02 kgm/s2 : toc o quay cua ong c (rad /s) : v tr goc quay cua ong c (rad) n : t so truyen, trong khao sat: n = 10.

Vi ieu kien khong tai th Mc = 0, thu gon s o khoi tr thanh :

III.2.a. Khao sat mo hnh ieu khien toc o ong c DC: Muc ch:

Trong phan nay, sinh vien se xay dng mo hnh ieu khien toc o ong c DC dungbo ieu khien PID co tnh en s bao hoa cua bo ieu khien. Khao sat anh hng cua boieu khien PID en chat lng ap ng ngo ra vi tn hieu au vao la ham nac.

Th nghiem:Xay dng mo hnh he thong ieu khien PID toc o ong c DC nh sau:

333.4 1

( 31.2)( 2.14) 10s s s

+ +

U


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Trong o: Tn hieu at au vao ham nac u(t) = 100 (tng trng toc o at 100)

Khau bao hoa Saturationco gii han la +30 / -30 (tng trng ien ap cungcap cho phan ng ong c t 30V en +30V)

Transfer Fcn Transfer Fcn1the hien mo hnh toc o ong c DC.

a. Chnh thi gian mo phong Stop time= 10s. Thc hien khao sat he thong vi bo ieukhien P (KI= 0, KD= 0) va tnh o vot lo, sai so xac lap, thi gian xac lap cua ngo ratheo bang sau:

KP 1 10 20 50 100POTexltxl

Nhan xet chat lng cua he thong thay oi nh the nao khi KPthay oi. Giai thch.

b. Thc hien khao sat he thong vi bo ieu khien PI (K P= 2, KD= 0) va tnh o vot lo,sai so xac lap, thi gian xac lap cua ngo ra theo bang sau:

KI 0.1 0.5 0.8 1 2POTexltxl

Nhan xet chat lng cua he thong thay oi nh the nao khi KI thay oi. Giaithch. So sanh chat lng cua bo ieu khien PI vi bo ieu khien P.

c. Thc hien khao sat he thong vi bo ieu khien PID (KP= 2, KI= 2) va tnh o vot lo,sai so xac lap, thi gian xac lap cua ngo ra theo bang sau:

KD 0.1 0.2 0.5 1 2POTexl

txl

Nhan xet chat lng cua he thong thay oi nh the nao khi KD thay oi. Giaithch. So sanh chat lng cua bo ieu khien PID vi bo ieu khien P, PI.

d. Nhan xet anh hng cua cac khau P, I, D len chat lng cua he thong.

III.2.b. Khao sat mo hnh ieu khien v tr ong c DC : Muc ch:

Trong phan nay, sinh vien se xay dng mo hnh ieu khien v tr ong c DC dung boieu khien PID co tnh en s bao hoa cua bo ieu khien. Khao sat anh hng cua bo ieukhien PID en ap ng ngo ra vi tn hieu au vao la ham doc.


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Th nghiem:Xay dng mo hnh he thong ieu khien PID v tr o ong c DC nh sau:

Trong o: Tn hieu at au vao ham doc co bien o = 10, tan so 0.1Hz ( tng trng v tr

at thay oi theo dang song tam giac) Khau bao hoa Saturationco gii han la +30 / -30 Transfer Fcn Transfer Fcn1 Transfer Fcn2the hien mo hnh v tr ong

c DC.

a. Chnh thi gian mo phong Stop time= 50s. Thc hien khao sat he thong vi bo ieukhien P (KI= 0, KD= 0) va tnh o vot lo, sai so xac lap, thi gian xac lap cua ngo ratheo bang sau:

KP 1 10 20 50 100

POTexltxl

Nhan xet chat lng cua he thong thay oi nh the nao khi KPthay oi. Giai thch.b. Thc hien khao sat he thong vi bo ieu khien PI (K P= 2, KD= 0) va tnh o vot lo,

sai so xac lap, thi gian xac lap cua ngo ra theo bang sau:

KI 0.1 0.5 0.8 1 2POT

exltxl

Nhan xet chat lng cua he thong thay oi nh the nao khi KI thay oi. Giaithch. So sanh chat lng cua bo ieu khien PI vi bo ieu khien P.

c. Thc hien khao sat he thong vi bo ieu khien PID (KP= 2, KI= 1) va tnh o vot lo,sai so xac lap, thi gian xac lap cua ngo ra theo bang sau:


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KD 0.1 0.2 0.5 0.8 1POTexltxl

Nhan xet chat lng cua he thong thay oi nh the nao khi KD thay oi. Giaithch. So sanh chat lng cua bo ieu khien PID vi bo ieu khien P, PI.

d. Nhan xet anh hng cua cac khau P, I, D len chat lng cua he thong.

Hng dan:Khoi Repeating Sequence ( th vien Simulink \ Sources) la khoi phat tn hieu lap

lai. Tuy theo gia tr lap trnh ma no co the phat ra tn hieu xung vuong, tam giac hay rang ca

vi bien o va tan so thay oi c.Double-click vao khoi Repeating Sequence e cai atxung tam giac bien o bang 10, tan so 0.1Hz nh sau:

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