Dong Co Servo Dc Co Choi Than 592

5/27/2018 Dong Co Servo Dc Co Choi Than 592

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LOGO

TRNG I HC S PHM K THUTTP.HCM

BRUSH DC SERVO

Thc hin:TRN C LM

U DNG NAM


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1.Tng quan v ng c servo

1.1 Servo motor l g?Servo theo ting Hy Lp l Servus (Servant-n

l)

cc lnh iu khin v tr

L h thng iu khin da trn quan st sai lch

gia gi tr t v gi tri hi tip


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Gi tr p ng c phn hi v sau khithc hin lnh

Sai l ch ia i tr n v i tr iukhin s c h thng iu chnh vbng 0


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1.3 Cc c im ca ng c servo


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1.3 Cc c im ca ng c servo


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1.4 Phn loi ng c servo

Servo AC

Servo DC c chi than


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Mt s hnh nh v ng c servo


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2.1c im ca Servo DC c chi than

u im:Cung cp chuyn ng m

Gi thnh rn gin trong iu khin

Tc n nh

Chu c tn hiu iu khin c tn s caoM-men xon khi ng cao


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Nhc im:Chuyn mch c kh gy ra ting n

Tng nhit trn vnh gp

Qun tnh ca rotor cao khi im tc Kh sa cha

tin cy thp

i hi s bo tr


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2 ng c Servo DC c chi than

2.2 Hnh nh v Brush Servo DC thc t


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2.2 Cu to Servo DC c chi than

Cc thnh phn ca ng c


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Cc thnh phn ca ng c

Stator:c gn lin vi v ng cRotor:l thnh phn to chuyn ng quay

Chi than v vnh gp: gip a in vo Rotor

Encoder:hay cn gi l b m ha vng quay, ,

Phanh in t:gip hm ng c trong trnghp cn thit

Tachometer:l thnh phn phn hi tng t,thc cht l mt my pht in nh, vi in pphn hi c tnh bng (vol/vng quay)


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3 Nguyn l hot ng

Trong qu trnh hot ng, t trng cnh c sinh ra t nam chm vnh cugn trn stator tng tc vi dng t sinh

ra t cun dy trn roto khi c dng inchy qua n. Qu trnh tng tc sinhra moment tc ng ln trc roto.

Moment ny biu din theo phng trnhTm=ke..Ie.sin


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Quan h gia t trng v dng phn ng

Moment trn trc ng c tng dn t = 0-90 m bo moment trn trc ng c lunt c gi tr ln nht cn thit phi iukhin chuyn mch cp in cho cun dy rotosao cho vect dng phn ng lun lun vung

c vi t trn c nh


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Vi cch iu khin qu trnh cp in nhtrn, mmen ng c s bin thin t l vidng cp cho cun dy phn ng.

M-men v tc ng c c th m t bng 2

Tc= Km.IuE

b

=Kb

.


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Mch ca ng c

T nh lu t Kirchhoff ta c hn trnh

mch

Thnh phn Lnh hn so vi Rnn cth b qua Lth: V RI = Kb

uu b u u u

dIV K. R.I L.( )

dt


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Phng trnh mmen ti Tmt trn trcng c : Tm= T+ Ts+ Tc

Vi:

Td=Jc(d/ dt)

Ts= fdc

Tc=Jm(d/dt)+fm

ng c quay th mmen ng c phibng vi mmen ti: Tm= Tc=Km.Iu


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4 iu khin Servo DC c chi than

iu khin v tr, vn tc ca ng cBng phng php xc nh gc quay ca motor

Dng encoder

Tachometer (thnh phn phn hi tng t) Bin tr xoay

Phng php ph bin hin nay dng opticalencoder


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Cu to ca 1 optical encoder

Phi hp knh A, B ta s tm c gc quayv chiu quay ca ng c.


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Nguyn l iu khin rng xung sdng mch cu H

1. V->R1->B->A->L2->GND

2. V->L1->A->B->R2->GND


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Mch cu H dng Relay


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Mch cu H dng BJT


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Mch cu H dng Mosfet


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Nguyn l iu xung PWMPWM (pulse width modulation)

L phng php iu chnh in p ra ti da

trn s thay i rng xung dn n thay i

To dng trn nguyn tc chuyn ti nnglng t A n B di dng cc xung vung

ton p lin tipTn s xung trong PWM c th c nh hay

bin i (thng l c nh tns xung chuynmch)


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Nguyn l iu xung PWM.Vi tn s c nh, chu k T bng tng thi

gian m xung t(on) vi thi gian tt xungt(off). T = t(on) + t(off) = t1 + t2


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Nguyn l iu xung PWM i vi PWM = 25% th Ut = Umax.25%(V)

i vi PWM = 50% th Ut = Umax.50% (V)

i vi PWM = 75% th Ut = Umax.75% (V)


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Nguyn l iu xung PWM.Trong vi iu khin PIC16F887 c sn module

PWM ( 2 knh)

S dng 2 knh PWM ny, ta c th iu khin

c ng c eo mu n.

Knh PWM1 dng cho chiu thun ca ng c,PWM2 dng cho chiu cn li ca ng c


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5 Mt s ng dng ca ng c servo

Robot

Trc ca thit b chuyn ng

Dng c y t

My CNC

iu khin anten

Dn nhn

M hnh chi


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Dong Co Servo Dc Co Choi Than 592

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