Gio trnh

NG C IN MT CHIU V VN IU KHIN TC

CA NG C IN MT CHIU

1

NG C IN MT CHIU V VN

IU KHIN TC CA NG C IN

MT CHIU

CHNG 1 NG C IN MT CHIU V CC PHNG

PHP IU KHIN TC

1.1 NG C IN MT CHIU:

1.1.1 Khi nim chung:

ng c mt chiu c s dng vi mt s lng ln trong k thut thit

k bi v nhng c trng tc quay (tc xon) kh thi vi nhng cu hnh

in khc nhau. Tc ng c mt chiu c th kim sot mt cch m i v

trong a s cc trng hp (th) c th o ngc chiu quay. T khi ng c mt

chiu c mt hiu sut cao ca qun tnh t lc xon ti r to, chng c th tr

li (p ng) nhanh chng. ng thi, phanh ng lc ni mt pht sinh

nng lng n c cp ti mt in tr cm bin, hoc phanh phc hi (phn

hi), ni m t pht sinh nng lng c cp (nui) tr li ngun cung cp in

mt chiu, c th thc hin trong cc ng dng ni mong mun dng nhanh v

hiu qu cao.

2

Da vo cch cc t trng phn tnh ( stator) c to ra, bn trong

ng c mt chiu c chia lm 4 loi khc nhau: nam chm vnh cu, vt kha

mch r nhnh (mch song song), vt kha mch ni tip, vt kha mch hn hp.

S in, ng cong m men xon- tc , v ng cong dng in- m

men xon cho mi cu hnh c minh ho trong cc hnh t I-2 n I-5. Hnh I-

1 minh ha mt th mmen xon-tc ca ng c m n cho thy cc

mmen xon m ng c c th cung cp cc tc khc nhau in p

nh. Vi mt m men xon cho c cung cp bi ng c , th dng

in-m men xn c th c s dng o hm nh lng dng in nh

khi in p quy nh c s dng. Nh mt kinh nghim (quy lut) chung,

nhng ng c chuyn giao (truyn) nhng m men xon ln (ti) nhng tc

thp, v nhng m men xon cng c ngha l nhng dng in ng c ln.

M men khi ng hc m men cn Ts l m men ln nht m ng c sn ra

tc bng khng tng ng vi s khi ng hoc qu ti ng c. tc

khng ti max l tc duy tr ln nht m ng c c th t c; tc ny

ch c th c thc hin khi khng c ti trng hoc m men xon c ng

dng ti ng c ( ch khi n chy khng).

Trong hnh t I-2 n I-5, V l in p mt chiu ngun cung cp, IA l

dng in cc cun r to, IF l dng in trong cc cun stato, v IL l ton b

dng ti pht ra bi ngun cung cp in mt chiu.

Cc trng in t trong cc ng c nam chm vnh cu (PM) (hnh I-2)

c cung cp bi cc nam chm vnh cu, m khng yu cu ngun ln bn

ngoi v khng c sn sinh pha trc cng sut lm nng ln I2R. S la chn

mt ng c PM l sng sut hn v nh gn hn so vi cc ng c mt chiu

tng ng khc bi v t trng ko di ca cc nam chm vnh cu l mnh

m. B rng bn knh ca nam chm vnh cu l xp x 1/4 ca b rng bn knh

3

mt cun t tng ng. Cc ng c PM c o chiu quay mt cch n

gin bi chuyn mch.

Hnh I-1 th quan h m men xon-tc ca ng c

S iu khin in p ng dng t dng in v s thay i chiu t

trng ch trong rotor. ng c PM l l tng trong cc ng dng iu khin

my tnh bi mi quan h tuyn tnh ca c trng mmen xon-tc ca n.

Thit k ca mt b iu khin lun lun n gin khi ng c l tuyn tnh t

cc phn tch h thng c n gin ho i rt nhiu.Khi mt ng c c s

dng trong mt v tr hoc trnh ng dng iu khin vi cm bin phn hi ti

mt b iu khin, n c xem (quy vo) nh mt ng c servo. Cc ng c

PM ch c s dng trong cc ng dng cng sut thp m nh lng cng

sut thng c gii hn n 5 m lc (3728 W) hoc nh hn, vi nhng s

phn loi theo sc nga nh l ph bin hn. ng c mt chiu PM c th c

qut bng chi than, khng chi than, hoc cc ng c bc.

Cc ng c mch nhnh (mch r, hay mch song song ) ( hnh I-3 ) c

li v cc cun kch t kt ni song song, chng c khi ng bi cng ngun

cung cp. Ton b dng in ti l tng ca cc dng trong li (ct) v cc dng

kch t. Cc ng c mch r ( cc ng c kch t song song ) cho thy tc

gn nh l hng s trn mt di ln ti trng, v c cc m men xon khi ng

tc khng ti(max)

tc

mm

en

xon

mmen khi ng (Ts)

mmen xon

dng

i

n

4

( m men xon ln nht khi tc bng khng ) khong 1,5 ln ln m men

xon hot ng, c m men xon khi ng nh nht trong cc ng c mt

chiu khc, v c th tit kim c chuyn i cho php c th iu chnh

c tc bi vic t mt vn k ni tip vi cc cun kch t.

Hnh I-2 S ng c in mt chiu nam chm vnh cu v th quan h

m men xon-tc

nam chm V

ILmmen xon

tc mmen xon

dng in (IL)

dng in (IL)

V

tc

mmen xonIL

mmen xon

IA

IF

bin tr

dng t trung nh (1-5% )

xp x hng s

5

Hnh I-3 S ng c mt chiu mch r (ng c in mt chiu kch t song

song) v th m men xon-tc .

Cc ng c kch t ni tip (Hnh I-4) c li v cc cun kch t mc ni

tip ng thi cc dng kch t v dng trong li l bng nhau. Cc ng c kch

t ni tip cho nhng m men xon khi ng rt ln, tc quay bin i rt

cao v ph thuc ti trng, v tc rt cao khi ti trng nh. Trong thc t cc

ng c kch t ni tip loi ln c th gy trt khc lit khi chng t nhin

mt ti trng (v d nh trong vic s dng mt dy ai, khi ai trt) do cc lc

ng lc cc tc cao. iu ny gi l chy ph hng . Tuy nhin khi ng

c np li ti, iu ny khng khng cn t ra mt vn g na. ng th

m men xon-tc cho mt ng c kch t ni tip l ng c dng

hyperbolic, cho thy mt mi lin h ngc gia m men xon v tc v cng

sut gn nh l hng s trn mt di rng.

Cc ng c hn hp (hnh I-5) bao gm c cc cun kch t ni tip v

song song, kt qu ca t hp cc c trng ca c cc ng c kch t ni tip

v cc ng c kch t song song. Mt phn ca ton b dng ti truyn qua c

li v cc cun ni tip, v s gi nguyn dng ti ch truyn qua cc cun mch

r. Tc ln nht ca mt ng c hn hp b gii hn, khng ging nh mt

ng c kch t ni tip, s iu khin tc ca n khng tt bng so vi mt

ng c mch r ( ng c kch t song song ). M men xon sinh ra bi cc

ng c hn hp c phn nh hn cc ng c kch t ni tip c cng kch

thc.

6

Hnh I-4 S ng c kch t ni tip v ng c trng m men xon- tc .

Hnh I-5 S ng c hn hp mt chiu v ng c trng m men xon-tc

Lu rng khng ging nh ng c nam chm vnh cu, khi cc tnh

in p cho ng c mch r nhnh (ng c kch t song song ), ng c kch

t ni tip, hoc ng c mt chiu hn hp b thay i, chiu quay s khng

i. L do cho iu ny l cc tnh ca c stator v rotor thay i theo t trng

v cc cun li b kch hot bi cng mt ngun.

1.1.2 Phng trnh ng lc hc ca ng c in mt chiu PM.

Khi li ca mt ng c c kim tra vi mt ng h o tr khng vi

li c nh v vo mt v tr, Tr khng ng c xut hin tng ng vi

mt in tr R trong mch ni tip vi s t hp song song ca mt cm khng

L v mt in tr th hai RL. Trong khi li bt u quay mt in p c t

dng in (IL)ILIA

mmen xon

mmen xon

tc

Vcun kch

tc chy ph hng

V

IA IL

tc

mmen xon dng in (IL)

mmen xon

IF

mch ni tip

mch song song

7

cm trong cc cun li gi l sut in ng phn hi chng li in p s

dng. Trc , mch in tng ng cho li c th hin trong hnh I-6.

RL, tn tht in tr trong mch t, n gn nh cng mt loi vi in tr

c ln ln hn R, in tr ca cc cun, v thng n gin. Nu chng ta

cho rng in p s dng cho li l Vin v dng in chy qua li l Iin,

phng trnh in cho ng c l:

Hnh I-6 Mch tng ng cho li ng c

wkRIdtId

LV einin

in ..

++= (I-2-1) w l tc quay vng ca m t (rad/s) v ke l hng s in ca m t nh

ngha nh sau:

wV

k emfe = (I-2-2) ng c nam chm vnh cu (PM) d iu khin v phn tch, ta s thy

nhng phng trnh iu khin ca n chi tit hn nhiu .V s tng tc gia

trng stator v dng in phn ng,momen xon pht sinh bi ng c in

mt chiu PM s t l thun vi dng in phn ng:

Vemf

Vin

Iin

L

RL

R

8

T=kt.Iin (I-3-1)

kt c nh ngha nh hng s momen xon ca ng c. Hng s in ke

v hng s momen xon kt ca ng c in PM l nhng tham s rt quan

trng, chng thng c thng bo trong cc c im k thut ca nh sn

xut.

Khi ng lc hc ca h thng c xem xt, momen xon T ca ng c

c cho bi

LinLaTT

dtdwJJT +++= )(

(I-3-2)

Ja v JL l nhng momen c cc qun tnh ca phn ng v gn lin ti

trng, Tin l momen cn chng li s quay ca phn ng, v TL chng li momen

xon ca ti.

Khi ng c c ni vi ngun in, phn mg s tng tc cho n khi t

ti mt trng thi n nh. Ti trng thi n nh, phng trnh I-2-1 tr thnh

Vin = R.Iin + ke.w (I-3-3)

Ch rng ti trng thi n nh, t phng trnh I-3-2, momen xon ca

ng c cn bng vi momen ti trng gi nh.

Tm Iin trong phng trnh I-3-1 v thay vo trong phng trnh I-3-3 ta c

wkT

kRV e

tin .. +

=

(I-3-4)

Momen xon ca ng c c tnh theo phng trnh

w

Rkk

VRk

T teint .

.

=

(I-3-5)

9

Phng trnh trn ni ln mi lin h tuyn tnh gia momen xon - vn tc

ca ng c mt chiu PM vi in p khng i.

Hnh I-7 biu din ng momen - vn tc v ng cong cng sut - vn

tc cho mt ng c in mt chiu nam chm vnh cu. V momen - vn tc

quan h tuyn tnh, n c th c biu din trong gii hn ca momen khi

ng TS v vn tc khng ti wmax nh:

=

max

1)(w

wTwT s ( I-3-6)

Cng sut pht ra ca ng c mi tc khc nhau c th c biu din

nh sau

==

max

1..)(w

wTwTwwP s (I-3-7)

Cng sut u ra ln nht ca ng c xut hin

0.21

max

=

=

wwT

dwdP

s

(I-3-8)

Gii vn tc cho

w * = 1 / 2. wmax (I-3-9)

V vy vn tc tt nht khi chy mt ng c nam chm vnh cu t

c cng sut u ra cc i l bng mt na vn tc khng ti.

Ngoi nhng hng s momen v hng s in, nh sn xut thng cng ch

r in tr R. Gi tr ny hu ch trong vic xc nh dng in tr IS ca ng

c

10

Hnh I-7 c im ca ng c in mt chiu nam chm vnh cu

RV

kI intS .= (I-3-10)

Phng trnh ny cho dng in c gi tr ch khi r to ca ng c khng

quay; mt khc, dng in rto c gi nh v sut in ng trong nhng

cun r to. Dng in tr l dng in ln nht chy qua ng c cn c vo s

cung cp in p. Phng trnh I-3-1 v I-3-10 c th s dng lin h momen

cn TS vi hng s momen, cung cp in p, v in tr phn ng:

RV

kT intS .= (I-3-11)

1.2 IU KHIN TC NG C IN MT CHIU

Cn

g su

t

Mm

en

ung mmen - vn tc

ung cng sut - vn tc

wmaxw*Vn tc

11

1.2.1 Khi nim chung:

V phng din iu khin tc ng c in mt chiu c nhiu u vit

hn so vi loi ng c khc, khng nhng n c kh nng iu chnh tc d

dng m cu trc mch lc, mch iu khin n gin hn ng thi li t cht

lng iu chnh cao trong di iu chnh tc rng.

Thc t c hai phng php c bn iu chnh tc ng c in mt

chiu:

iu chnh in p cp cho phn ng ng c.

iu chnh in p cp cho mch kch t ng c.

Cu trc phn lc ca h truyn ng iu chnh tc ng c in mt

chiu bao gi cng cn c b bin i. Cc b bin i ny cp cho mch phn

ng ng c hoc mch kch t ng c. Trong cng nghip thng s dng bn

loi b bin i chnh:

B bin i my in gm: ng c s cp ko my pht mt chiu hoc

my in khuch i (KM)

B bin i in t: Khuch i t (KT)

B bin i chnh lu bn dn: Chnh lu tiristo (CLT)

B bin i xung p mt chiu: tiristo hoc tranzito (BBXA)

Tng ng vi vic s dng cc b bin i m ta c cc h truyn ng

nh:

H truyn ng my pht-ng c (F-)

H truyn ng my in khuch i - ng c (MK-)

H truyn ng khuch i t - ng c (KT-)

12

H truyn ng chnh lu tiristor-ng c (T-)

H truyn ng xung p-ng c (XA-)

Theo cu trc mch iu khin cc h truyn ng, iu chnh tc ng

c mt chiu c loi iu khin theo mch kn

(ta c h truyn ng iu chnh t ng) v loi iu khin theo mch h

(h truyn ng iu khin h). H iu chnh t ng truyn ng in c cu

trc phc tp, nhng c cht lng iu chnh cao v di iu chnh rng hn so

vi h truyn ng h. Ngoi ra cc h truyn ng iu chnh tc ng c

in mt chiu cn c phn loi theo truyn ng c o chiu quay v khng

o chiu quay. ng thi tu thuc vo cc phng php hm, o chiu m ta

c truyn ng lm vic mt gc phn t, hai gc phn t v bn gc phn t.

1.2.2 Nguyn l iu chnh in p phn ng:

iu chnh in p phn ng ng c mt chiu cn c thit b ngun nh

my pht in mt chiu kch t c lp, cc b chnh lu iu khin vv... Cc

thit b ngun ny c chc nng bin nng lng in xoay chiu thnh mt

chiu c sc in ng Eb iu chnh c nh tn hiu iu khin Uk.

Hnh II-1. S khi v s thay th ch xc lp.

V l ngun c cng sut hu hn so vi ng c nn cc b bin i ny c

in tr trong Rb v in cm Lb khc khng.

BB

L k

Uk

Rb RuI

EuEb(Udk) U

13

ch xc lp c th vit c phng trnh c tnh ca h thng nh

sau:

Eb - E = I Rb + RI

udm

udb

dm

b IK

RRK

E+

= (II-2-1)

MU dk = )(0

V t thng ca ng c c gi khng i nn cng c tnh c cng

khng i, cn tc khng ti l tng th tu thuc vo gi tr in p iu

khin Uk ca h thng, do c th ni phng php iu chnh ny l trit .

xc nh gii iu chnh tc ta rng tc ln nht ca h thng

b chn bi c tnh c bn, l c tnh ng vi in p phn ng nh mc v t

thng cng c gi gi tr nh mc. Tc nh nht ca di iu chnh b

gii hn bi yu cu v sai s tc v v m men khi ng. Khi m men ti l

nh mc th cc gi tr ln nht v nh nht ca tc l:

dm

M= max0max (II-2-2)

dm

M= min0min

tho mn kh kh nng qu ti th c tnh thp nht ca di iu chnh

phi c m men ngn mch l:

Mnmmin = Mcmax = KM.Mdm

14

Trong KM l h s qu ti v m men. V h c tnh c l cc ng

thng song song nhau, nn theo nh ngha v cng c tnh c ta c th vit:

)1(1)( minmin == Mdmdmnm KM

MM

1

1.

)1(

max0max0

=

=M

dm

dmM

dm

KM

MK

M

D

(II-2-3)

Hnh II-2. Xc nh phm vi iu chnh

Vi mt c cu my c th th cc gi tr 0max, Mm, KM l xc nh, v vy

phm vi iu chnh D ph thuc tuyn tnh vo gi tr ca cng . Khi iu

chnh in p phn ng ng c bng cac thit b ngun iu chnh th in tr

tng mch phn ng gp khong hai ln in tr phn ng ng c. Do c th

tnh s b c:

Wo maxWmax

WminWo min

Wk1

Wk1

Mnm minMm0

M,I

W

15

10/max dmo M

V th vi ti c c tnh m men khng i th c gi tr phm vi diu chnh

tc cng khng vt qu 10. i vi cc my c yu cu cao v di iu

chnh v chnh xc duy tr tc lm vic th vic s dng cc h thng h

nh trn l khng tho mn c.

Trong phm vi ph ti cho php c th coi cc c tnh c tnh ca truyn

ng mt chiu kch t c lp l tuyn tnh. Khi iu chnh in p phn ng

th cng cc c tnh c trong ton di iu chnh l nh nhau, do st

tc tng i t gi tr ln nht ti c tnh thp nht ca di iu chnh. Hay

ni cch khc , nu ti c tnh c thp nht ca di iu chnh m sai s tc

khng vt qu gi tr sai s cho php, th h truyn ng s lm vic vi sai s

lun nh hn sai s cho php trong ton b di iu chnh. Sai s tng i ca

tc c tnh c thp nht l:

minmin

minmin

oo

os

=

=

cpo

dm sM

s =min

(II-2-4)

V cc gi tr Mdm, omin, Scp la xc nh nn c th tnh c gi tr ti thiu

ca cng c tnh c sao cho sai s khng vt qu gi tr cho php. lm

vic ny, trong a s cc trng hp cn xy dng cc h thng truyn ng in

kiu vng kn.

16

Trong sut qu trnh iu chnh in p phn ng th t thng kch t c

gi nguyn, do m men ti cho php ca h s l khng i:

Mc.cp=Km.Im=Mm.

Phm vi iu chnh tc v m men nm trong hnh ch nht bao bi cc

ng thng = m , M = Mm v cc trc to . Tn hao nng lng chnh l

tn hao trong mch phn ng nu b qua cc tn hao khng i trong h.

E = E + I(Rb + R)

IEb = I E + I2(Rb + R)

Nu t Rb + R = R th hiu sut bin i nng lng ca h s l:

( )22

dm

uuu

uuu

KMRRIEI

EI

+

=+

=

***

RMu +=

Khi lm vic ch xc lp ta c m men do ng c sinh ra ng bng

m men ti trn trc: M* = Mc* v gn ng coi c tnh c ca ph ti l

Mc* = (* )x th

( ) 1****

+

= xu R (II-2-5)

17

Hnh II-3 Quan h gia hiu sut truyn ng v tc vi cc loi ti khc nhau

Hnh II-3 m t quan h gia hiu sut v tc lm vic trong cc trng

hp c tnh ti khc nhau. iu chnh tc bng cch thay i in p phn

ng l rt thch hp trong trng hp m men ti l hng s trong ton di iu

chnh. Cng thy rng khng nn ni thm in tr ph vo mch phn ng v

nh vy s lm gim ng k hiu sut ca h.

1.2.3 Nguyn l iu chnh t thng ng c:

iu chnh t thng kch ca ng c in mt chiu l iu chnh m

men in t ca ng c M = KI v sc in ng quay ca ng c E =

K. Mch kch t ca ng c l mch phi tuyn, v vy h iu chnh t

thngcng l h phi tuyn:

dtd

rre

i kkb

kk

+

+= (II-3-1)

trong rk - in tr dy qun kch thch,

rb - in tr ca ngun in p kch thch,

m

u

1

1

x=0

x=-1

m

18

k s vng dy ca dy qun kch thch,

Trong ch xc lp ta c quan h:

;kb

kk rr

ei

+= = f [ik]

Thng khi iu chnh t thng th in p phn ng c gi nguyn

bng gi tr nh mc, do c tnh c thp nht trong vng iu chnh t

thng chnh l c tnh c in p phn ng nh mc,t thng nh mc v

c gi l c tnh c bn (i khi chnh l c tnh t nhin ca ng c). Tc

ln nht ca di iu chnh t thng b hn ch bi kh nng chuyn mch

ca c gp in. Khi gim t thng tng tc quay ca ng c th ng

thi iu kin chuyn mch ca c gp cng b xu i, v vy m bo iu

kin chuyn mch bnh thng th cn phi gim dng in phn ng cho php,

kt qa l m men cho php trn trc ng c gim rt nhanh. Ngay c khi gi

nguyn dng in phn ng th cng c tnh c cng gim rt nhanh khi

gim t thng kch thch:

( )uR

K 2= hay ( )2** =

19

Hnh II-4 S thay th (a) c tnh iu chnh khi iu chnh t thng ng c (b)

Quan h (ikt),(c)

Do iu chnh tc bng cch gim t thng nn i vi cc ng c m t

thng nh mc nm ch tip gip gia vng tuyn tnh v vng bo ho ca

c tnh t ho th c th coi vic iu chnh l tuyn tnh v hng s C ph

thuc vo thng s kt cu ca my in:

.. kkb

k errCiC+

==

Uk rbkLk

ikrkk

I

E

max

m

c tnh c bn

0

b,

a,

Lk(Uk)

ikk

0

c,

20

1.2.4 iu khin ng c in mt chiu PM bng in t:

Dng n gin nht ca iu khin ng c l iu khin mch h , m n

gin l iu khin gi tr in p v nhng c trng ca ng c v xc nh ti

iu khin vn tc v momen. Nhng hu ht vn quan tm ph thuc loi

iu khin t ng no ni in p t ng c thay i sinh ra chuyn

ng mong mun. y c gi l mch kn hoc mch iu khin phn hi v

n ph thuc vo vn tc u ra / hoc momen cm bin ti nhng gi tr u ra

phn hi lin tc so snh u ra thc t ti mt gi tr mong mun gi l im

tp hp. Khi b iu chnh thay i u ra ca ng c dch chuyn st ti

im tp hp. B iu chnh vn tc in t c hai kiu: b khuych i tuyn

tnh v b bin i chiu rng xung. Mc du c hai h thng c th c thit

k cho mt chc nng tt hn, cc b iu chnh bin i b rng xung c ci

tin m chng iu khin cc tranzito cng sut lng cc nhanh chng gia cc

gii hn v s cn bng ni thao tc rt hiu qu (tn tht cng sut l ti thiu)

hoc bt v tt FET. B khuch i ph khuch i cng sut tuyn tnh lm tha

mn nhng ph thuc tn tht nhit t n hot ng trong vng tuyn tnh

ca thao tc tranzito. Ta s tm nhng b iu khin ph kinh t, s dng nhng

b khuch i tuyn tnh, nhng bi v yu cu cng sut thp, d ch to, kch

thc nh, v gi thnh thp, chng ta s tp trung thit k b khuch i, gi

l b khuych i bin i chiu rng xung (PWM).

Nguyn l hot ng ca my khuch i PWM c biu din hnh II-5 .

Mt in p mt chiu cung cp cng sut nhanh chng c chuyn thnh mt

tn s f c nh gia hai gi tr ( v d Bt v Tt ). Tn s ny thng ln

hn 1 KHz. Gi tr cao c gi trong thi gian mt xung t trong thi gian chu

k T c nh

21

fT 1=

(II-4-1)

Sng c to ra c mt chu k cng sut, c nh ngha nh t s gia

thi gian ON v chu k sng, thng thng c tnh theo phn trm:

Chu k cng sut = (t/T).100% (9.16)

Trong khi chu k cng sut c thay i (bi b iu chnh), dng in

trung bnh chy qua ng c s thay i, gy ra nhng s thay i v vn tc v

momen u ra. N ch yu thay i v chu k cng sut ch khng phi l gi

tr ca in p cung cp cng sut m xc nh nhng c trng u ra ca ng

c.

Hnh II-5

B bin i b rng xung ca ng c in mt chiu

PWMelectronics

dc powersupply (Vs)

+

t

T

T

pulses:

faster(large t)

slower(small t)

example drive circit

22

S khi ca mt mch iu khin phn hi tc PWM cho ng c mt

chiu c th hin hnh II-6. Mt p k pht sinh mt tn hiu ra tuyn tnh

lin h n tc ca ng c. N c so snh vi tc mong mun t

trc (mt in p khc c th iu khin bng tay hoc iu khin bng my

tnh). S c v dng in ca ng c c cm nhn bi mt my iu chnh

n chiu rng xung m pht sinh rng mt xung vung iu chnh nh mt

tn hiu ra. Tn hiu ny c khuych i ti mt mc thch hp cho in p

iu khin cho ng c.

Hnh II-6

motor

tachometer

power amp

PWM regulatorelectronics

measured speed

+

-

set point(desired) speed

in p PWM

Dng in motor

Chu trnh cng sut thpChu trnh cng sut cao

23

Hnh II-7 in p PWM v dng in motor

Trong iu khin ng c PWM in th i chiu nhanh qua phn ng, v

dng in qua ng c b tc ng bi tnh t cm v khng tr ca ng c.

Do tc i chiu cao, dng in qua ng c c s dao ng nh quanh

gi tr trung bnh ging trong minh ha hnh II-7. Khi cng sut vng quay cng

ln th gi tr trung bnh v tc ng c chy cng tng

V d minh ha: Mch cu hnh H cho ng c mt chiu:

Mc d c th thit k v to ra mt a quay cho mt ng c ph iu

khin ring v cc thnh phn nng lng, nhng c mt vi thit k mch tch

hp c kh nng tit kim c nhiu thi gian v tin bc trong thit k my.

Xt v vn c bn ca vic iu khin ng c mt chiu. Mc ch cui

cng ca bn c th l iu khin tc chiu quay, gc, v (hoc) momen

quay.

Vi yu cu iu khin tc ca ng c mt chiu, chng ta c th phi

thay i dng cung cp cho ng c. iu khin hng quay th chiu ca

dng in cung cp cho ng c phi i chiu. iu i hi mt b khuch

i dng in v mt vi thit b chuyn hng dng in. gii quyt yu

cu ny, ngi ta a ra khi nim mch cu H (H-bridge). Ngi ta s dng 4

transistors xp theo hnh H xung quanh ng c mt chiu ( nh hnh v di)

v ln lt kch hot tng cp ti mi thi im cho hng mong mun ca ng

c.

24

Nu transistor Q1 v Q3 kch hot, Q2 v Q4 tt th dng in s truyn qua

ng c theo hng nh hnh v v ng c s quay theo 1 hng. Tip n, khi

Q2, Q4 kch hot cn Q1, Q3 tt th ng c s quay theo hng ngc li.

Ngi ta c th to ra mt H-bidge vi ngun BJTs hoc MOSFET, nhng c

th rt kh chn ng hng quay mong mun bi trasistor. Do ta s thc

hin mt gii php s dng ng truyn ca khp cht bn dn cho cc IC iu

khin chuyn ng, gii php ny c th c tng thch cho vic iu khin

ng c mt chiu. Xt LMD18200, mt mch cu H 3A, 5V thit k c bit

iu khin ng c mt chiu v ng c bc. Ngoi ra n gin cch iu

khin ngi dng c th s dng c tnh an ton v qu dng v qu nhit, c

th s dng rng xung thay i h thng, v c th t ng hm ng c. S

chc nng c minh ho di y.

Q1Q1

Q4 Q3

Q2

Q4

Q3

Q2

+V

25

S chc nng:

S chc nng v thng tin iu khin:

inputlogic

drection 3

brake 4

pill 5

currentsensing

26

Thit k ny s dng MOSFET power vi cc diot c nhim v bo v tia

qut ngc i qua transistor. Cc cc ng c c ni gia u ra 1 v u ra

2. in p cung cp c th ln ti 55V. Cc tn hiu s bn ngoi iu khin

hng, vic hm v cc u ra khi nhit ln hn 1700 C. Khi nhit vt

qu 1450 C s c xc nh bi b bo nhit.

S khi hon thin ca thit k b iu khin tc c minh ho nh

hnh v. im thit lp tc c xc nh bi mt vn k hoc mt gi tr

in p vo. Mt ng h o tc c ni thm vo ng c nh l b cm

ng cung cp mt cch o tc ng c. IC LM3525 bin i rng xung

lu chuyn khp cht bn dn c s dng iu khin u vo b iu khin

ng c H-bridge.

11

10

9

8

7

6

5

4

3

2

1

27

CHNG 2

LM3525 PWM

LMD18200 H-b ridge

motor

ng h o tc

iu khin hung

im t vn k

28

THIT K PHN CNG IU KHIN NG C

MT CHIU

2.1 THIT K NGUN CUNG CP CHO MCH CHUN HO V VI X L

Vi x l cn ngun 5V, do ta thit k mch t ngun 220V thnh 5V nh hnh v di:

2.2 GHP NI CARD THU THP S LIU 12 KNH VI MY TNH

2.2.1 Cng ni tip RS-232

a s cc h vi x l u c ghp ni vi my tnh thng qua cng ni tip RS-232. y l mt chun truyn thng kh ph bin vi cc my PC hin nay.

Thng thng cc my tnh u c hai cm DB9 hoc DB25 pha sau dnh cho cng ni tip RS-232.

c im ca RS-232:

Thng tin c truyn theo kiu im - im. Ph hp vi truyn thng tin s, nh phn. Truyn theo kiu ni tip khng ng b. Truyn khng cn bng nn d b nh hng bi nhiu.

220

BA1

12V

12V

0

C1

2200m/25V

C1

2200m/25V

C1

100n

C1

1000m/16

C1

100n

C1

100n

C1

1000m/16v

C1

100n

7805

In Out0

In Out0

+5V

-5V

0

29

Phn ln tn hiu c truyn dng m ASCII. Truyn song cng cn 3 dy. Mc in p ca tn hiu: Mc 1 l -3 : -12V

Mc 0 l +3 : +12V

Khong cch truyn ngn c khong 15m. Tc truyn ti a: 19600bps. Bng b tr cc chn trn cm DB9 v DB 25:

Tn hiu DB9 DB25

TxD 3 2

RxD 2 3

RTS 7 4

CTS 8 5

DSR 6 6

GND 5 7

DCD 1 17

DTR 4 20

RI 9 22

Hnh dng cc cm nh sau:

30

ghp ni h thng vi x l vi my tnh PC cn c cc mch chuyn i mc t mc TTL sang mc chun RS-232 v ngc li. Cc mch thng dng hin nay l cc mch dng Transistor lm b chuyn i, dng b cch ly quang v dng vi mch chuyn dng. Trong n ny ta dng vi mch chuyn dng MAX 232 ca hng MAXIM.

2.2.2 Vi mch MAX 232:

Vi mch MAX 232 lm nhim v chuyn i mc TTL li vo (pha h C8051) thnh mc 10V pha truyn ra (My tnh) v cc mc t 3 : 12V pha my tnh thnh mc TTL a vo vi x l.

S chn ca vi mch MAX 232:

5

4

3

2

1

9

8

7

6

DB9

5555555555555555555555555

DB25

31

Khi ghp ni MAX 232 vi vi iu khin v my tnh th TxD t vi iu khin c ni trc tip n chn 11 (T1 In) ca MAX 232 cn chn ra 14 (T1 Out) c ni trc tip vi chn 2 ca cng ni tip (RxD). Chn TxD ca cng ni tip (chn 3 my tnh) ni vi li vo chn 13 (R1 In) ca MAX 232, t chn 12 (R1 Out) c ni trc tip vi chn RxD ca vi iu khin.

Vi mch MAX 232 c 2 b m v 2 b nhn. ng dn iu khin li vo CTS, iu khin vic xut d liu ra cng ni tip khi cn thit, c ni vi chn 9 (R2 Out) ca vi mch MAX 232. Cn chn RTS (chn 10 ca MAX 232) ni vi ng dn bt tay iu khin qu trnh nhn. i vi cc giao thc n gin ch cn s dng 3 dy: TxD, RxD, GND.

2.3 VI IU KHIN H MCS 51

Ngy nay trong qu trnh cng nghip ho v hin i ho cn n cc b vi iu khin h tr cho cc b iu khin ngy cng pht trin v hon thin hn. Mi b vi iu khin thng c ch to thnh mt chp, trn c cc cng vo ra, cc b nh c th phi ghp vi cc thit b khc v thc hin cc chc nng iu khin. Trong cc b vi iu khin hin nay h MCS_51 ca

R2in 8

T2out

V-

C2-

C2+

C1-

V+

C1+

8

8

8

8

8

8

8 16

15

14

13

12

11

10

9

Vcc

GND

T1out

R1in

R1out

T1in

T2in

R2out

32

hng INTEL l thng dng nht, nhn nhn mt cch tng qut v h MCS_51 ta c bng tng kt.

Tn gi Cng ngh Rom trong Rom ngoi Ram trong Ram ngoi Timmer/Counter

8031 NMOS Khng 64Kbyte 128Kbyte 64Kbyte 2

8051 NMOS 4Kbyte 64Kbyte 128Kbyte 64Kbyte 2

8751 NMOS 4Kbyte EPROM

64Kbyte 128Kbyte 64Kbyte 2

8032 NMOS Khng 64Kbyte 256Kbyte 64Kbyte 3

8052 NMOS 4Kbyte 64Kbyte 256Kbyte 64Kbyte 3

Phn ln cc b vi x l 8051 c ng v theo kiu hai hng DIL vi tng cng 40 chn. Mt s khc c ng v theo kiu hnh vung PLCC vi 44 chn. Hnh sau l s chn ca IC8051 theo kiu DIL 40 chn.

Gii thch s chn v chc nng ca 8051.

P2.0P2.1P2.2P2.3P2.4P2.5P2.6P2.7P1.0P1.1P1.2P1.3P1.4P1.5P1.6P1.7PO.0PO.1PO.2PO.3PO.4PO.5PO.6PO.7

2122232425262728123456783938373635343332

AD5

AD1AD0

AD3AD2

AD4

AD6AD7

A11

A9A10

A15

A13A12

A14

A8

13

1110

12

1514

1617RD\

WR\T1T2INT1INT2TXDRXD

33p

33p

11,0592 MHz

29

30

31

9

PSEN

ALEEA

RST

40

20

19

18

33

S chn

K hiu Chc nng

18 P1.0P1.7 Cng vo/ra Port

9 Reset Li vo Reset tch cc mc cao

1017 P3.0p3.7 Cng vo/ra Port v tt c cc ng dn vi chc nng c bit

18 XLAT 2 Li vo ca b dao ng thch anh bn trong

19 XLAT 1 Li vo ca b dao ng thch anh bn trong

20 VSS Chn ngun ni 0V

2128 P2.0P2.7 Cng vo/ra Port 2 ni cc ng a ch cao t A8A15

29 PSEN Dng cho b nh chng trnh ngoi

30 ALE Cho php cht a ch

31 EA lm vic vi Rom ngoi hay Rom trong

3239 P0.7P0.0 Cng vo/ra Port 0, cc ng a ch thp t A7A0

40 VDD Ngun cung cp 5V

2.3.1 S khi ca b vi x l 8051:

34

-Interrupt control : iu khin ngt

-Other registere : Cc thanh ghi khc

-128 Byte RAM :

-Timer 1, 0 : B nh thi

-CPU : n v iu khin trung tm

-Osillator : Mch dao ng

-Bus control : iu khin Bus

-I/O port : Cc Port xut/nhp

-Serial Port : Port ni tip

-Address/data : a ch d liu

-Cng truyn ni tip RS - 232

2.3.2 Cch t chc v truy cp b nh ca 8051

B nh ca 8051 ni ring v h MCS_51 ni chung chia lm 2 vng b nh ring bit: B nh chng trnh v B nh d liu.

EA

RST

ALE

PSEN

Oscillation

CPU

Buscontrol

TIMER 0

Interruptcontrol

Otherregisters

Serial port

INT1*

INT0*

TIMER 1

P1P0 P2 P3

I/O Port

RXD*TXD*

Serialport

128 ByteRAM

ROM4K

TIMER 0

TIMER 1

35

2.3.2.1 B nh chng trnh (Program Memory)

B nh chng trnh (ROM, EPROM) c th c nhng khng ghi c, b nh chng trnh c th ti 64 Kbyte. i vi 8051 c ROM trong vi dung lng 4 Kbyte, vi nhng loi khng c ROM trong ta phi dng ROM ngoi lu gi chng trnh, khi c ROM ngoi phi thng qua tn hiu PSEN (Program Store Enable). Do vy tn hiu PSEN ch c tc dng vi ROM ngoi cn i vi ROM trong tn hiu PSEN s khng c tc dng.

Sau khi RESET CPU bt u thc hin t vng 0000H, tip theo l n vng t cc ngt ca XPU t a ch 0003H n 0023H. Vic s dng ROM trong (i vi nhng loi c ROM trong) v ROM ngoi c biu hin bng cch s dng chn EA (External Acess).

*Khi chn EA ni vi Vcc:

- i vi nhng loi c ROM trong 4 Kbyte nh 8051 th chng trnh thc hin t a ch 0000H n 0FFFH ca ROM trong sau tip tc t a ch 1000H n FFFFH ca ROM ngoi.

- i vi nhng loi c ROM trong l 8 Kbyte s chn t a ch 0000H n 1FFFH ca ROM trong v t a ch 2000F n FFFFH ca ROM ngoi.

- i vi nhng loi c ROM trong l 16 Kbyte s chn t a ch 0000H n 3FFFH ca ROM trong v t a ch 4000G n FFFFH ca ROM ngoi.

*Khi chn EA ni vi Vss:

- Lc CPU s lm vic ton b vi ROM ngoi. Do vy i vi nhng loi khng c ROM trong th chn EA phi c ni vi Vss.

Trong khi truy cp b nh ngoi CPU s vit 0FFH ti b cht ca Port 0 nh vy n s xo bt c thng tin ti Port 0 m SFR c th cn ang gi, nn vic vit ra Port 0 trong khi ang truy cp b nh ngai s b sai. V vy nn nh: khng ghi ra Port 0 khi b nh chng trnh ngoi ang c s dng.

36

2.3.2.2 B nh d liu

B nh d liu (RAM) nu c a ch l 8 bit th cho php CPU 8 bit thao tc nhanh hn, nu a ch l 16 bit c th truy cp c phi thng qua thanh ghi DPTR (Data Pointer). Vi 8051 c 128 Byte RAM trong c th ghp vi 64 Kbyte RAM ngoi. Trong sut qu trnh CPU truy cp ti b nh d liu s pht tn hiu c RD v tn hiu ghi WR.

i vi 128 Byte ca RAM trong bao gm: 32 byte thp nht l nhm 4 bank thanh ghi, mi bank thanh ghi gm 8 thanh ghi R0 R7. Khi s dng cc thanh ghi trong chng trnh phi np 2 bit vo thanh ghi Program Status Word (PSW). Tip theo l 16 byte trn vng cc bank thanh ghi t a ch 20H 2FH l vng cc bit a ch, vng ny c 128 bit. Bit 0 ca byte 20H c a ch l 0 v bit 7 ca byte 2FH c a ch l 7FH.

2.3.3 Cc thanh ghi chc nng c bit (Special Function Registers SFRs)

SFRs- cc thanh ghi vi chc nng c bit gm c thanh ghi s liu v thanh ghi iu khin nh Timer, cng ni tip, h thng ngt... SFRs c a ch t 80H n FFH. Bng cc thanh ghi trong SFRs ca 8051:

Registers Mnemonic Internal AddressPort 0 Latch P0 80HStack Pointer SP 81HData Pointer DPTR 82H 83H Data Pointer Low Byte DPL 82HData Pointer High Byte DPH 83HPower Control PCON 87H

37

Timer/Counter Control TCON 88HTimer/Counter Mode Control TMOD 89HTimer/Counter 0 Low Byte TL0 8AHTimer/Counter 1 Low Byte TL1 8BHTimer/Counter 0 High Byte TH0 8CHTimer/Counter 1 High Byte TH1 8DHPort 1 Latch P1 90HSerial Poft Control SCON 98HSerial Data Port SBUF 99HPort 2 Latch P2 A0HInterrrupt Enable 1E A8HPort 3 Katch P3 B0HInterrupt Priority Control 1P B8HProgram Status Word PSW D0HAccumulator Acc or A E0HB Rgister B F0H

Thanh ghi t trng thi chng trnh (Program Status Word - PSW) bao gm cc bit trng thi phn nh trng thi ca CPU. Thanh ghi PSW c t trong cc thanh ghi chc nng c bit SFRs

CY AC FO RS0 OV P

*PSW 0 (Parity P): Bit kim tra chn l, c t bi phn cng P=1: Nu s cc bit =1 trong thanh ghi ACC l l P=0: Nu s cc bit = 1 trong thanh ghi ACC l chn *PSW 1: ngi dng nh ngha c. *PSW 2 (Over flow OV): C bo trn, c t khi c trn xy ra ca php tnh s hc.

*PSW 3 (RS0): Dng chn bank thanh ghi. *PSW 4 (RSI): Dng chn bank thanh ghi.

38

*PSW 5 (F0): C trng thi. *PSW 6 (auxiliary Carry Flag AC): C nh ph, c thnh lp khi c nh sang t bit 3 ca ton hng trong php cng.

*PSW 7 (Carry Flag CY): C nh, c thnh lp khi c s nh t bit 7 ca ton hng ca b ALU.

2.3.4 Cc ch a ch trong 8051

2.3.4.1 Ch a ch trc tip (Direct Addressing)

Trong ch ny mt ton hng cha a ch ca mt nh, a ch ca nh c cho r xc nh bi 8 bit a ch cn ton hng kia l thanh ghi. V d:

ADD A,7FH

Cu lnh ny s thc hin cng ni dung nh 7FH vi ni dung trong thanh ghi A, kt qu chuyn vo thanh ghi A.

Ch a ch dng khi lm vic vi RAM trong v cc thanh ghi trong SFRx.

2.3.4.2 Ch a ch gin tip (Indirect Addressing)

Ch a ch ny dng vi c RAM trong v RAM ngoi. Trong ch ny mt ton hng l 1 thanh ghi c s dng cha a ch ca nh cn ton hng kia l thanh ghi. Nu a ch ca nh 8 bit ta c th dng cc thanh ghi R0 R7 ca cc bank thanh ghi hoc l Stack Pointer. Nu a ch l 16 bit ta ch c th dng thanh ghi. V d:

ADD A,@R0

Cu lnh ny s thc hin cng ni dung ca nh c a ch t trong thanh ghi R0 vi ni dung trong thanh ghi A, kt qu chuyn vo thanh ghi A.

2.3.4.3 Ch a ch thanh ghi (Regiter Addressing)

Trong ch ny ton hng ngun hoc ton hng ch c th l 1 trong 8 thanh ghi ca bank thanh ghi chn. V d:

MOV R0, B

39

MOV A, R7

2.3.4.4 Ch a ch tc th (Immediate Addressing)

Trong ch ny ton hng ngun l hng s c km theo m. V d:

MOD A, #100; Np vo A s 100 h c s 10

MOD A, #10H; Np vo A s 10 h c s 16

2.3.4.5 Ch thanh ghi c trng (Register Specific Addressing)

Trong mt s trng hp ta dng ch ny gi thanh ghi. V d:

MOV 0E0H, #1; Chuyn hng s 1 vo trong SFR 0H

2.3.4.6 Ch a ch thanh ghi ch s (Register Specific Addressing)

Ch ny ch c dng tra bng (Look Up Table). Trong ch ny a ch ngun hoc a ch ch c t trong hoc l DPTR (Data Pointer) hoc l PC (Program Counter). V d:

MOV DPTR, #8100H

MOV A, #0

MOV A, @A+ DPTR

2.3.5 Cng vo ra song song

8051 c 4 cng vo ra song song: Port 0 (P0), Port 1 (P1), Port 2 (P2, Port 3 (P3)

Khi cng c s dng l cng ra: S liu c a vo thanh ghi SFR tng ng, ng thi c a ra cht v tip tc pht ra tn hiu sau khi vic ghi c hon thnh, gi tr a ra cng ra c thay i khi gi tr mi c cht.

Khi cng c s dng lm cng vo: u tin l vit gi tr FFH ra cng, sau chn no ca cng c mc in p thp s c nhn bit l 0 v cng c th c vo SFRs tng ng.

40

Port 0, Port 2, Port 3 ngoi cc chc nng ca cc cng vo/ra cn c cc chc nng khc. thc hin cc chc nng khc nhau th cc bit tng ng ca cc thanh ghi trong SFRs tng ng phi c t (thng l bng 1).

Port 0, Port 2 c dng ghp ni vi b nh ngoi, Port 2 a ra byte cao ca 16 bit a ch cn Port 0 u tin a ra byte thp ca 16 bit a ch v sau c th gi hoc nhn byte d liu. Byte a ch thp phi c cht bn ngoi, lm vic ny th b vi iu khin pht ra tn hiu ti chn ALE cht byte a ch thp.

Port 3 bao gm cc ngt, cc u vo Timer/Counter, u vo/ra ca cng ni tip, cc tn hiu iu khin cho php ghp ni vi b nh ngoi.

Pin Alternate Funtion Mnemonic/DesignationP3.0 Serial Input Port RXD P3.1 Serial Output Port TXD P3.2 External Interrupt 0 INT0# P3.3 External Interrupt 1 INT1# P3.4 Timer/Counter 0 External Input T0 P3.5 Timer/Counter 1 External Input T1 P3.6 External Memory Write Strobe WR# P3.7 External Memory Write Strobe RD#

2.3.6 Timer/ Counter

8051 c 2 Timer/Counter 16 bit, c 2 c th hot ng nh Timer cng c nh Counter. Khi hot ng nh Timer thanh ghi c tng ln 1 ti mi chu k my, ta c th coi l m chu k my, mi chu k my gm 12 chu k dao ng ca thch anh. Khi hot ng nh Counter thanh ghi tng tng ng vi s thay i 1 v 0 ti u vo chn T0, T1. Chc nng l Timer hay Counter phi c la chn ng thi cng phi chn 1 trong 4 ch hot ng. Vic khi to hot ng v iu khin cc Timer/Counter da trn 2 thanh ghi TMOD v TCON trong vng cc thanh ghi c chc nng c bit SFRs.

2.3.6.1 Thanh ghi TMOD (Timer/ Counter Mode Control Register)

41

GATE C/T M1 M0 GATE C/T M1 M0 *Gate:

- Khi GATE = 1: Timer/Counter x c php hot ng ch khi chn INTx mc cao v chn iu khin TRx c t.

- Khi GATE = 0: Timer x c php hot ng bt c lc no bit iu khin c t

*C/T: La chn Counter hay Timer

- C/T = 1: Counter, ni dung b m c tng ln bi xung ngoi kch vo T0 (P3.4).

- C/T = 0: Timer

*M0, M1 : Chp nhn m theo cc gi tr tng ng nh sau:

M1 M0 Mode 0 0 0 ; m 13 bit 0 1 1 ; m 16 bit 1 0 2 ; m 8 bit t ng np li 1 1 3 ; Timer 1 khng hot ng Timer 0 hot ng nh 2

b Timer ring bit 8 bit 2.3.6.2 Thanh ghi TCON (Timer/ Counter Control Register)

TF1 TR1 TE0 TR0 IE1 IT1 IE0 IT0 *TF1 (TCON 7): C bo trn ca Timer 1. t bi phn cng khi

Timer/Counter trn. Xo bi phn cng khi x l vect phc v ngt

*TR1 (TCON 6): Bit iu khin Timer 1 c t v xo bng phn mm

42

*TF0 (TCON5): C bo trn ca Timer 0. t bi phn cng khi

Timer/Counter trn. Xo bi phn cng khi x l vect phc v ngt

*TR0 (TCON 4): Bit iu khin Timer c t v xo bng phn mm

*IEI (TCON 3): C ngt 1 theo sn. c t bi phn cng khi sn ca xung ngt ngoi a vo chn INT# c pht hin v xo khi x l ngt.

*IT1 (TCON 2): Bit iu khin ngt 1. t v xo bng phn mm, vic t IT1 ti sn xung ca tn hiu v ti INT#, vic xo IT1 khi tn hiu ngoi ti chn INT1# c pht hin v xo khi x l.

*IE0 (TCON 1): C ngt 0 theo sn. c t bi phn cng ca xung ngt ngoi a vo chn INT0# c pht hin v xo khi x l ngt.

*IT0 (TCON 0): Bit iu khin kiu ngt 0. t v xo bng phn mm vic t IT0 ti sn xung ca tn hiu v ti INT0#, vic xo IT0 khi tn hiu ngoi ti chn INT0# l mc thp.

2.3.6.3 Cc ch hot ng ca Timer/Counter

*Mode 0: L b m 8 bit, tn hiu ngt xut hin khi m trn, v vy n m c 213 hay 8192 xung s cho 1 tn hiu bo ngt.

*Mode 1: Hot ng ging nh Mode 0 nhng ch ny l 16 bit tc l m c 216 hay 65536 xung s cho tn hiu bo ngt.

*Mode 2: Ch 8 bit t ng np li. TLi s lm vic nh b

Timer/Counter 8 bit, khi m trn s m c t trong THi (Phn byte cao ca thanh ghi 16 bit) s t ng np vo trong TLi v b m li tip tc lm vic, tn hiu ngt c pht ra khi Timer m trn v t ng np li.

*Mode 3: Timer 1 khng hot ng vo gia s m ca n,, vic ny ng ngha vi t TR1 = 0. Timer 0 ch ny thit lp TL0 v TH0 nh 2 b m ring bit, TL0 s dng cc bit iu khin ca Timer 0, TH0 vi chc nng v Timer (m chu k my) v tip nhn s dng TR1 v TF1 t Timer 1. V vy TH0 coi l Timer 1.

43

2.3.7 Giao din ni tip

Cng ni tip c th truyn nhn ng thi. N cng l b m nhn ngha l c th bt u nhn byte th 2 trc khi byte trc c c t thanh ghi nhn. Tuy nhin nu byte u tin vn cha c c trong thi gian nhn byte tip theo th byte u tin s mt. C 2 thanh ghi nhn v truyn ca cng ni tip l Specia Funtion Register SBUF. Vic ghi ti SBUF l np vo thanh ghi truyn, vic c SBUF l truy cp vo thanh ghi nhn. Cng ni tip c 4 ch hot ng:

*Mode 0: Hot ng nh thanh ghi dch. D liu vo/ra ni tip qua RxD/TxD, u ra dc theo xung ng h. 8 bit c truyn hoc nhn bt u t LSB. Tc baud l 1/12 tn s xung thch anh.

*Mode 1: D liu vo/ra ni tip qua RxD/TxD. 10 bit d liu c truyn hoc nhn bao gm 1 bit Start (thng mc 0), 8 bit d liu bt u t LSB v bit Stop (thng mc 1). ch ny khi nhn d liu th bit Stop s c chuyn vo bit RB8 trong thanh ghi Special Function Register SCON. Tc baud thay i c.

*Mode 2: D liu vo/ra ni tip qua RxD/TxD. 11 bit d liu c truyn hoc nhn bao gm 1 bit Start (thng mc 0), 8 bit d liu bt u t LSB, 1 cho php lp trnh, 1 bit Stop (thng mc 1). Khi truyn d liu bit th 9 c chuyn vo bit TB8 trong SCON c th c t gi tr 0 hoc 1, cng c th l bit kim tra chn l (P trong PSW). Khi nhn d liu bit 9 s c chuyn vo bit RB8 trong SCON trong khi bit Stop b b qua. Tc baud c th l 1/32 hoc 1/64 tn s xung thch anh.

*Mode 3: D liu vo/ra ni tip qua RxD/TxD. 11 bit d liu c truyn hoc nhn bao gm 1 bit Start (thng mc 0), 8 bit d liu bt u t LSB, 1 bit cho php lp trnh, 1 bit Stop (thng mc 1). Khi truyn d liu bit th 9 hoc cng c th l bit kim tra chn l (P trong PSW). Khi nhn d liu bit th 9 s c chuyn vo bit RB8 trong SCON trong khi bit Stop b b qua. Tc baud thay i c.

44

Trong c 4 ch hot ng:

- Khi d liu nhn c khi to v s dng SBUF nh l thanh ghi ch.

- Khi nhn d liu: Mode 0 phi c iu kin RI = 0 v REN = 1

Cc Mode khc nu bit REN =1 th bit Start bt u c nhn.

*Ch truyn a knh (Multiprocesor Communication)

Trong ch 2 v 3 cn c dng cho vic truyn a knh, trong cc ch ny bit d liu c nhn v bit th 9 c chuyn vo RB8 sau l bit Stop. Cng c th c lp trnh sao cho khi bit Stop c nhn th ngt ni tip s c tch cc ch khi bit RB8 = 1. Nt c trng l cho php t bit SM2 trong SCON, bng cch ny cho php s dng ch truyn a knh.

Khi trm ch (Maste) mun gi mt gi d liu ti mt trong vi trm t (Slave), u tin trm ch gi ra 1 byte a ch xc nh trm t no chun b nhn d liu. Byte a ch ny khc vi byte d liu l trong byte a ch ch th ton b u b ngt, v vy trm t no cng cn kim tra xem byte nhn c v xem n c phi l a ch ca mnh khng. Nu l a ch ca mnh th n s xo bit SM2 v chun b nhn cc byte d liu sp c gi. Nu khng phi a ch ca mnh n vn t bit SM2 ng thi bo bn v b qua cc byte d liu n. Bit SM2 khng c tc dng trong Mode 0, trong Mode 1 c th dng kim tra gi tr ca bit Stop, khi nhn nu SM2 = 1 th ngt nhn s khng c tc dng tr khi bit Stop c nhn.

Tc Baud trong truyn ni tip:

i vi Mode 0: Baud rate = 121 oscillator frequency

i vi Mode 2: Baud rate = 64

2SMD oscillator frequency

SMOD = 0 : Baud rate =641 oscillator frequency

45

SMOD =1 : Baud rate =321 oscillator frequency

i vi Mode 1 v Mode 3

Trong hai ch ny s dng Timer 1 dnh tc Baud

Khi Timer 1 bo trn:

Baudrate = 32

2SMD (Timer 1 Over Flow Rate)

Khi Timer s dng ch hot ng t ng np li s m khi trn:

Baudrate = 32

2SMD x )1256(12

1THx

oscillator frequency

Vic khi to v iu khin ch truyn nhn ni tip thng qua 2 thanh ghi SCON v PCON

2.3.7.1 Thanh ghi SCON (Serial Part Control Register)

SM0 SM1 SM2 REN TB8 RB8 TI TI SMO, SM1: dng nh ch truyn nhn nid tip

SM0 SM1 MODE

0 0 0

0 1 1

1 0 2

1 1 3

SM2 :Cho php truyn a knh trong Mode 2, MOde 3

Mode 1 SM2 dng lim tra gi tr ca bit Stop

Mode 0 SM2 khng coa tc dng (thng SM2 = 0)

REN : Cho php nhn ni tip, c t v xo bng phn mm

46

TB8 : i vi Mode 2, Mode 3 bit th 9 s c chuyn vo, c t v xo bng phn mm

RB8 : Mode 2, Mode 3 bit th 9 c nhn v chuyn vo

Mode 1 khi SM2 = 0, RB lab bit Stop c nhn

Mode 0 khng s dng bit ny

TI : C ngt khi truyn, c t bi phn cng ti cui cng ca bit th 8 trong Mode hoc l khi bt u bit Stop trong cc Mode khc, phi c xo bng phn mm

RI : C ngt khi nhn, c t bi phn cng cui cng ca bit th 8 trong Mode 0 hoc l gi bit Stop trong Mode khc, phi xo c bng phn mm.

2.3.7.2 Thanh ghi PCON (Power Control Register)

SMOD GF1 GF0 PD IDL SMOD : Bit dng nhn i tc Baud

GF1, GF0 : General Purpose Flag Bit

PD : Power Down Bit

IDL : Idle Mode Bit

2.3.8 Cc ngun ngt v cch s dng ngt

Cc ngun ngt c t ti a ch t 0003H 0023H trong b nh chng trnh. Khi c ngt th CPU s nhy ti vng m n phc v ngt, nu chng trnh phc v ngt nm trong khong 8 byte th s phc v ngt ngay trong vng , cn khi chng trnh phc v ngt m ln hn 8 byte v cc ngun ngt khc ang phc v th s nhy vt qua vng ngt sau thc hin chng trnh phc v ngt.

Bng cc vect ngt

47

Ngun ngt a ch

E0 0003H

TF0 000BH

IE1 0013H

TF1 001BH

RI & TI 0023H

Cch s dng ngt:

-t bit EA (Enable A11) trong thanh ghi IE = 1.

-t bit tng ng vi ngt trong thanh ghi IE = 1.

-Bt u phc v ngt ti a ch tng ng vi ngt.

2.3.8.1 Thanh ghi IE (Interrupt Enable Register)

EA ES ET1 EX1 ET0 EX0 EA (IE 7): Cho php hay khng cho php cc ngt hot ng.

EA = 0 khng c ngt no hot ng.

EA = 1: Ton b cc ngun ngt c php hot ng.

IE 6: Khng s dng

IE 5: Khng s dng.

ES (IE 4): Cho php hay khng cho php ngt khi truyn nhn ni tip.

ET1 (IE 3): Cho php hay khng cho php ngt khi Timer 1 bo trn.

EX1 (IE 2): Cho php hay khng cho php ngt khi ngt ngoi 1.

ET0 (IE 1): Cho php khng ngt khi Timer 0 bo trn.

EX0 (IE 0): Cho php hay khng cho php ngt khi ngt ngoi 0.

Th t u tin cc ngt:

48

theo mc nh th c cc mc u tin cao xung thp nh sau:

IE0 : mc cao nht

TF0

IE1

TF1

RI & TI : mc thp nht

khi c s u tin ta t cc bit tng ng trong thanh ghi IP = 1.

2.3.8.2 Thanh ghi IP (Interrupt Register)

PS PT1 PX1 PT0 PX0 IP7, IP6, IP 5: khng s dng v t bng 0

PS (IP 4) : nh ngha mc u tin ngt cho cng ni tip.

PT1(IP 3) : nh ngha mc u tin ngt cho Timer 1.

PX1 (IP 2) : nh ngha mc u tin ngt cho ngt ngoi 1.

PT0 (IP 1) : nh ngha mc u tin ngt cho Timer 0.

PX0 (IP 0) : nh ngha mc u tin ngt cho ngt ngoi 0.

2.4 CC LNH TRONG 8051

2.4.1 Lnh MOV

*C php : MOV ch, Ngun

* ngha : Chuyn gia Ngun vo ch

Trong ch, Ngun bao gm cc thanh ghi, cc nh, hng s.

2.4.2 nh ngha cc hng, bin

*C php : Tn bin UQU Gi tr

* ngha : Gn bin bng gi tr

49

*V d : PI UQE 12H; c mt bin tn l PI c nh ngha bng 1 byte c a ch 12H

2.4.3 Cc lnh s hc

*Lnh MOV

C php: MOV ch, Ngun

ngha: chuyn gia Ngun v ch

ch, Ngun bao gm cc thanh ghi, cc nh, c hng s

V du: MOV R0, #27H ; R0 = 27H

MOV A, R0 ; Ni dung ca thanh ghi A a vo R0

*Lnh ADD

C php: ADD ch, Ngun

ngha: Ni dung ca ch cng vi ni dung ca Ngun kt qu c tr v ch.

VD: MOV R0, #32H ; R0 = 32H

MOV R5, #23H ; R5 = 23H

ADD R5, R0 ; R5 = 23H + 32H = 55H

*Lnh ADDC

C php: ADDC ch, Ngun

ngha: Ni dung ca ch cng vi ni dung ca Ngun cng vi ni dung ca CF, kt qu c a vo ch

V d: MOV R0, #89H ; R0 = 89H

ADD R0, 0F8H ; R0 = 89H + F8H = 81H v CF = 1

MOV A, #37H ; A = 37H

ADDC A, R0 ; A = 37H + 81H + 1 = B9H

*Lnh SUBB

50

C php: SUBB ch, Ngun

ngha: Ly ch tr ngun tr CF kt qu c a v ch

V d: MOV A, #0F8H ; A = F8H

MOV R0, #3AH ; R0 = 3AH

CLR C ; CF = 0

SUBB A, R0 ; A = F8H 3AH 0H = BEH

*Lnh INC

C php: INC Ton hng

ngha: Ton hng s c tng ln mt

V d: MOV A, #50H ; A = 50H

INC A ; A = 51H

*Lnh DEC

C php: DEC Ton hng

ngha: Ton hng s b gim xung mt

V d: MOV A, #50H ; A = 50H

DEC A ; A = 4FH

*Lnh MUL

C php: MUL AB

ngha: lm php tnh A nhn B, phn cao ca kt qu gm 8 bit c a vo B, phn thp ca kt qu gm 8 bit c a vo A

V d: MOV A, #50H ; A = 50H

MOVB B, 0A0H ; B = A0H

MUL AB ; A = 00H v B = 32H

*Lnh DIV

51

C php: DIV AB

ngha: lm php chia A cho B, kt qu a vo A, s d a vo B

V d: MOV A, #0FFH ; A = FFH

MOV B, #0AH ; B = 0AH

DIV AB ; A = 19H v B = 5H

2.4.4 Cc lnh Logic

*Lnh ANL

C php: ANL ch, Ngun

ngha: Thc hin php AND, kt qu thu c a vo ch

V d: MOV A, #32H ; A = 32H

ANL A, #0FH ; A = 02H

Ch : ch v Ngun l cc thanh ghi , cc hng s.

0 AND 1 = 0

0 AND 0 = 0

1 AND 0 = 0

1 AND 1 = 1

*Lnh ORL

C php: ORL ch, Ngun

ngha: Thc hin php OR, kt qu tr v ch

V d: MOV B, #0AFH ; B = AFH

ADD B, #08H ; B = AFH + 08H = B7H

ORL B, #1FH ; B = B7H OR 1FH = BFH

Ch : 0 OR 0 = 0

0 OR 1 = 1

52

1 OR 0 = 1

1 OR 1 = 1

*Lnh XRL

C php: XRL ch, Ngun

ngha: thc hin php XOR gia ch v Ngun, kt qu thu c tr v ch

V d: MOV A, #37H ; A = 37H

MOV R2, #0BDH ; R2 = BDH

XRL A, R2 ; A = 37H XOR BDH = 8AH

Ch : 0 XOR 0 = 0

0 XOR 1 = 1

1 XOR 0 = 1

1 XOR 1 = 0

2.4.5 Cc lnh thao tc trn Bit

*Lnh CLR

C php: CLR C(hoc Bit)

ngha: xo CF hoc Bit

V d: CLR C ; CF = 0

*Lnh SETB

C php: SETB C(hoc Bit)

ngha: SET CF hoc Bit

V d: SETB C ; CF = 1

*Lnh CPL

C php: CPL C(hoc Bit)

ngha: o CF hoc Bit

53

V d: CLR C ; CF = 0

CPL C ; CF = 1

*Lnh ANL

C php: ANL C, Bit

ngha: thc hin php AND Bit vi C

*Lnh ORL

C php: ORL C, Bit

ngha: thc hin php OR Bit vi C

*Lnh JC(JNC)

C php: JC (JNC) Nhn

ngha: nhy n Nhn nu C=1(0)

*Lnh JB(JNB)

C php: JB (JNB) Nhn

ngha: nhy n Nhn nu Bit=1(0)

*Lnh JBC

C php: JBC Nhn

ngha: nhy n Nhn nu Bit=1 sau xo Bit

2.4.6 Cc lnh nhy khng c iu kin

*Lnh LJMP

C php: LJMP Nhn

ngha: nhy n Nhn vi khong cch ti a 16Bit

*Lnh AJMP

C php: AJMP Nhn

ngha: nhy n Nhn vi khong cch ti a 11Bit

54

*Lnh SJMP

C php: SJMP Nhn

ngha: nhy n Nhn vi khong cch ti a 8Bit

2.4.7 Cc lnh nhy c iu kin

*Lnh CJNE

C php: CJNE X1, X2, Nhn

ngha: so snh X1 vi X2, nu X1 khng bng vi X2 th nhy n Nhn

*Lnh DJNZ

C php: DJNZ X1, Nhn

ngha: so snh X1 vi 0, nu X1 khng bng 0 th gim X1 i 1 ri Nhy n Nhn

2.5 CHNG TRNH ASM

Cu trc chng trnh ASM

ORG 00H

LJMP START;

ORG O3H

RETI

ORG 0BH

RETI

ORG 13H

RETI

ORG 1BH

RETI

ORG 23H

55

RETI

ORG 2BH

RETI

;-----------------------------------------------------------------------------------------------

;Khai bo bin, hng s

;------------------------------------------------------------------------------------------------

ORG 100H

START :

;Chng trnh chnh

;-----------------------------------------------------------------------------------------------

;Chng trnh con

;-----------------------------------------------------------------------------------------------

;Chng trnh phc v ngt

56

PHN II

TNH TON THIT K C KH

57

CHNG 3

THIT K L XO V TNH P SUT KH CN THIT CP CHO PISTON-CYLINDER

3.1 TNH TON L XO:

3.1.1 D liu u vo:

Thit k l xo xon c tr chu nn lp trong li trc chnh, chuyn v lm

vic x=10 mm.

- Ti trng ban u Fmin c tnh da vo trng lng ca c cu trc tip

nn vo l xo khi lp rp, bao gm cc chi tit: bc trt, np, 2 vt M3,

trc nh, ng ng bi, 4 vin bi, i dao.

58

V c cu ny trong solidworks v s dng cng c tnh khi lng vi

trng lng ring ca vt liu lm c cu l = 7,852 KG/dm3 ta c:

M= mbc trt + mnp + mvt + mng ng bi + mbi + mi dao

Trong :

mi dao= 0,5 Kg.

mbi= 4.0,9.10-3 Kg.

mbc trt + mlp + mvt + mng ng bi=309,2441.10-3 Kg.

i dao

4 vin bi

ng ng bi

trc nh

bc trt

2 vt M3Np

59

M= 0,313 + 0,5 = 0,813 Kg

Vy lc ban u Fmin= M.g= 0,813.10=8,13 N.

Trong : g l gia tc trng trng, ly g 10 m/s2

- Chn ng knh dy l xo: d = 2 mm.

3.1.2 Tnh ton:

- Chn vt liu l xo l thp nhiu cacbon (Theo bng 14.1-trang 212-

[1]) ta c: b= 1500 Mpa, vi ti trng va p, []= 0,3.b =

0,3.1500 = 450 Mpa

- Chn ch s ca l xo: c= dD =9.

d v c c s tng ng ph hp (Theo [1]- trang 212 )

Trong : D - L ng knh trung bnh ca l xo.

d - L ng knh dy l xo.

(Cng thc 14.8-Trang 215-[1]).

- Ta chn ng knh ca dy l xo l 2 mm:

d =1,6.][

.. max cFk =1,6.

4509..15,1 maxF =2 mm.

(Trch cng thc 14.6-Trang 214- [1])

Trong : k =3.42.4

+

cc =1,15.

k-H s k n tng ca ng sut bin trong ca l xo do

dy b un cong.

Ta c ti trng ln nht khi lm vic l:

60

Fmax = 22.450/(1,62.9.1,15) = 67,93 N

- S vng lm vic ca l xo.

(Theo cng thc 14.9- trang 215- [1])

n=).(.8

..).( minmax

3minmax1 FFc

dGxFF

x

=

Trong : G=)]1.(2[ +

E L m un n hi trt.

Vi E, l modun n hi v h s poisson ca thp

Thay vo biu thc trn ta c G= 8.104 Mpa.

n= 59,4)13,893,67.(9.8

2.10.8.103

4

=

vng.

Quy trn s vng n ta c:

n = 6 vng.

- ng knh trung bnh ca l xo:

D =c.d = 9.2=18 mm.

- Cc thng s kch thc khc:

+ S vng ton b:

n0=n+(1,5 2) = 6 + 2 = 8 vng.

+ Chiu cao ca l xo khi cc vng st nhau (Tnh theo cng

thc 14.11 Trang 215-[1])

HS=(n0-0,5).d (8-0,5).2 = 15 mm.

+ Bc ca vng l xo khi cha chi ti (Theo cng thc 14.12

Trang 215-[1])

61

p = d+ (1,1 1,2).nmax

Trong : max tnh theo cng thc 14.2-Trang 214-[1]

max= 43

max

....8

dGnDF =1.n.Fmax= max

3

...

.8 FndG

c =

= 86,1493,67.6.2.10.8

9.84

3

= mm.

p = 2 + 1,1. 72,4686,14

= mm.

+ Chiu cao ban u:

H0= Hs+n.(p-d) = 15 + 6(4,72 2) = 31,32 mm.

+ T s D

H 0 74,118

32,31= < 2,5 3

l xo m bo tnh n nh (Theo trang 216-[1]).

3.2 TNH TON P SUT KH CP CHO PISTON-CYLINDER:

Ti trng ln nht khi lm vic tnh c trn: Fmax = 212,639 N

Fmax = ..R2xi lanh .Pmax

Pmax = Fmax/(..R2xi lanh)

Trong :

: Hiu sut, ly = 1.

Rxi lanh: Bn knh trong ca xi lanh, y ta chn xi lanh c Rxi lanh = 10 mm

62

Pmax = 212,639/(1.3,14.102) = 0,677 (N/mm2) = 0,677/ 0,0981 = 6,9 at.

TI LIU THAM KHO

1. C s thit k my v chi tit my.

Tc gi: Trnh Cht NXB KHKT-2001 K hiu dng trong n l [1]

2. Tnh ton thit k h dn ng c kh - tp 1. Tc gi: Trnh Cht L Vn Uyn NXB Gio Dc 2002 K hiu dng trong n l [2]

3. Gottleib T.M / Electric Motors and Control Techniques; TAB Books, McGraw Hill (1994).

4. Kenjo, T., Stepping Motors and their Microprocessor Controls, OUP 1984

63

5. Kenjo, T., Electric Motors and their Control Oxford Science Publication, Oxford, England 1984.