V Duy T K&TH 3 K55

V Duy T K&TH 3 K55

MC LCBi tp 1 : Thit k b bin i Buck vi cc thng s :3Chng 1.M hnh ha b bin i Buck ch dng lin tc41.1. Phng php trung bnh khng gian trng thi41.2. Phng php trung bnh ha mch ng ct8Chng 2.Tnh ton thng s,thit k mch vng102.1. Tnh ton T C-rc102.2. Tnh ton cun cm L-rL112.3. Mch vng iu chnh in p122.4. Mch vng dng in16Chng 3.M phng b bin i Buck bng matlab vi thng s c th213.1. Mch vng in p213.2. Mch vng dng in23Bi tp 2 : Thit k h truyn ng ng c mt chiu c tham s ch ra trong bng s dng chnh lu cu 3pha iu khin hon ton s dng Tiristor.24Chng 1.Tnh chn van mch lc25Chng 2.Nguyn l mch iu khin.272.1. Khi ng pha ly im m t nhin ca tiristor272.2. Khu to in p ta.272.1.1Phng php iu khin xung kp vi rng xung T = 20e-5.272.1.2Phng php iu khin xung chm vi tn s f = 10 KHz.29Chng 3. iu khin vng kn31

Bi tp 1 : Thit k b bin i Buck vi cc thng s :in p uin=28(V), uo=15(V)

in cm L=50

T in C=500,rC= 0,1

Tn s pht xung : =100KH

Ti : R=3

M hnh ha b bin i Buck ch dng lin tcPhng php trung bnh khng gian trng thi

Hnh 1.1.S mch in b bin i Buck (a)S bin i b bin i Buck trong trng thi 1 (b)S mch bin i Buck trong trng thi 2(c)

S dng nh lut Kirchoff ta c h phng trnh m t s mch in trng thi 1 :

(1.1)

H phng trnh khng gian trng thi :

A1 ;B1; C2=;D1=0

S dng nh lut Kirchoff ta c h phng trnh m t s mch in trng thi 2 :

(1.2)

H phng trnh khng gian trng thi :

A2=;B2; C2=;D2=0M hnh trung bnh m t mt b biens i DC/DC vi s tham chiu ca h s iu ch d c vit li nh sau :

(1.3)

Suy ra :

A ;B; C=;D=0

B bin i Buck c m t trn min khng gian trng thi :

(1.4)

im lm vic cn bng ca b bin i Buck :

(1.5)

Hm truyn in p u ra v h s iu ch :

(1.6)

im lm vic cn bng ca b bin i Buck :

(1.7)

Suy ra IL= 5(A).Hm truyn gia dng in chy qua cun cm v h s iu ch :

(1.8)

Ta thay s:

L=50rL=0

C=500

rC= 0,1

R=3D=uo/uin=15/28=0.536

Nhn xt : Hm truyn t gia in p u ra v h s iu ch cho thy c 1 im zero nm bn tri mt phng phc nn h c m t bi hm truyn (1.6) l h pha cc tiu.

Hnh 1.2. th Bode hm truyn in p u ra v in p u voH n nh, tuy nhin gc phase ti tn s ct gn -1800 nn h rt d mt n nh khi c cc tc ng bn ngoi. Do ,cn phi thit k 1 b b tng d tr phase s c ni phn sau.Phng php trung bnh ha mch ng ct

Hnh 1.3. B bin i Buck vi tn hiu nh.Coi m hnh nh 1 mng 2 ca. Ta c cng thc sau :

(1.9)

Hm truyn gia h s iu ch v in p u ra di min laplace:

(1.10)

Ta tm c cc hm truyn khc :

(1.11)

Trong : Tr khng song song gia mch t lc C v ti

Tr khng mch in cm Hm truyn gia h s iu ch vi in p u ra :

(1.12)

Hm truyn gia in p u ra v in p u vo :

(1.13)

Nhn xt : Hm truyn xut hin im Zero m nm bn tri mt phng phc nn h c m t bi hm truyn (1.11)c cng l h pha cc tiu.Hai phng php u cho kt qu hm truyn c tnh cht ging nhau,l h pha cc tiu v cn xy dng 1 b b cho h thng.

Tnh ton thng s,thit k mch vng Tnh ton T C-rcT lc C phi ln m bo p mch ip p u ra v s st p khi ng ti trong phm vi cho chp. p mch gm 2 thnh phn : do in tr ni tip t C gy ra, v do t lc cc xung in p t u ra b bin i. p mch :

(2.1)

Hnh 2.1. p mch in p raThnh phn p mch do t C :

(2.2)

Suy ra gi tr t C p ng c yu cu :

(2.3)

i vi cc mch ngun DC-DC, p mch khng nn vt qu 1% Vo.Tnh ton cun cm L-rL

Hnh 2.2. th dng in qua cun cm LDng in trung bnh chy qua cun cm :

(2.4)

Dng in nh nht qua cun cm :

(2.5)

Khi cho 0,ta c gi tr in cm L nh nht :

(2.6)

Vi gi l tn s Switching,thng c chn l 20kHz hoc cao hn.Ta c :

(2.7)

Suy ra gi tr ca in cm l :

(2.8)

p mch dng in nm trong khong t 10% 30%

Mch vng iu chnh in pCu trc iu khin trc tip vng in p :

Hnh 2.3.Cu trc iu khin mch vng in p b bin i BuckHm truyn in p gia in p u ra v h s iu ch di dng :

(2.9)

Trong := Vin = 28V

= = = 9.5

Hnh 2.4. th Bode ca hm truyn GvdH n nh,tn s ct l 5,24kHz v d tr phase l PM=59.30,nh vy d tr pha tha mn.Tuy nhin, cn thit k 1 b b m bo h thng n nh tt hn vi tn s ct bng 10kHz v trit tiu sai lch tnh.

Ta xy dng b b PI : Ta thm 1 im khng nghch o vo h s khuch i vng lp tn s . khng thay i d tr pha mong mun tn s ct( to ra nh thnh phn PD) th .Chn = 2kHz.

(2.10)

Ti tn s ct :

(2.11)

Ta c :

Gcu_o= 2,152.Vy:

(2.12)

Hm truyn h :

(2.13)

Hnh 2.5. th Bode hm truyn h hNhn xt : H n nh,tn s ct l 10,9kHz v d tr phase l PM=49,30 nh vy c tn s ct v d tr pha u tha mn.Hm truyn kn :

(2.14)

p ng bc nhy ca hm Gk :

Hnh 2.6.p ng bc nhyTnh ton thng s b PI :

(2.15)

Mch vng dng in

Hnh 2.7.Cu trc iu khin mch vng dng in Hm truyn gia dng in qua cun cm v h s iu ch (rc