TRNG I HC BCH KHOA TPHCMCHNG TRNH K S CLC VIT-PHP

CC B BIN I TNHPUSH PULL CONVERTER

GVHD: PGS.TS PHAN QUC DNG

SVTH: Nguyn Hong LongMSSV: 41101906Lp: VP11NLNguyn V Bo HuyMSSV: 21101370Lp: VP11NLT Vnh KhimMSSV: 81101616Lp: VP11NLL Hong AnhMSSV: 41100075Lp: VP11VT

TPHCM, thng 5 nm 2015

TRNG I HC BCH KHOA TPHCMCHNG TRNH K S CLC VIT-PHP

CC B BIN I TNHPUSH PULL CONVERTER

GVHD: PGS.TS PHAN QUC DNG

SVTH: Nguyn Hong LongMSSV: 41101906Lp: VP11NLNguyn V Bo HuyMSSV: 21101370Lp: VP11NLT Vnh KhimMSSV: 81101616Lp: VP11NLL Hong AnhMSSV: 11111111Lp: VP11VT

TPHCM, thng 5 nm 2015LI NI UNgy nay in t cng sut c ng dng rng ri trong hu ht cc ngnh cng nghip hin i nh truyn thng in, giao thng, ng st, cc qu trnh in phn trong cng nghip ho cht, trong rt nhiu cc thit b cng nghip v dn dng khc nhauMt cch n gin nht c th hiu in t cng sut l cng ngh bin i in nng t dng ny sang dng khc trong cc b bin i l i tng nghin cu c bn ca in t cng sut B bin i push pull converter l mt b bin i c thit k theo kiu DC DC. Vic p dng nguyn l hot ng ca b bin i push-pull ni ring v mn in t cng sut ni chung gp phn gii quyt nhng bi ton k thut phc tp trong lnh vc t ng ho cng nh trong i sng hng ngy. Gip nng cao v ci thin cht lng cuc sng.i vi sinh vin in in t, mn hc in t cng sut l mt mn rt quan trng. Vi s ging dy nhit tnh ca cc thy c trong khoa chng em tng bc tip cn mn hc. c th nm vng l thuyt v p dng vo thc t, hc k ny chng em c thy gio cho n mn hc vi ti v vic S dng b bin i push - pull converter trong in t cng sut. y l mt ti c nhiu ng dng trong thc t. Vi s c gng ca cc bn trong nhm cng vi s ch bo ca thy trong b mn v c bit l thy Phan Quc Dng gip chng em hon thnh ti ny.Song vi lng kin thc cn hn ch v thi gian c hn, bn bo co thc tp ca chng em khng trnh khi nhng sai st v hn ch rt mong c s ch bo gp ca cc thy c v bn v.Chng em xin chn thnh cm n!

MC LC

1.TNG QUAN L THUYT11.1.Gii thiu11.2.Nguyn l lm vic12.THIT K42.1.Yu cu thit k42.2.Tnh ton thng s42.2.1.Kha ng ct (Switching)62.2.2.My bin p72.2.3.Chnh lu82.2.4.B lc92.2.5.B cch ly92.2.6.B khuch i vi sai92.2.7.B chnh p102.2.8.B iu khin t s ng ct102.2.9.B iu khin ng ct113.KT QU M PHNG123.1.Gin p kha133.2.p ng ra133.3.p diode143.4.Dng qua diode154.KT LUN165.NG DNG CA B PUSH PULL175.1.B ngun UPS175.2.B ngun Inverter ( Bin tn )17

DANH MC HNH NHHnh 1.1 S nguyn l b push pull (half bridge)1Hnh 1.2 Gin ng ct kha2Hnh 1.3 Gin p ra Vo, dng qua cun cm ILx, p cun th cp3Hnh 2.1 Flow chart cho b Feed back4Hnh 2.2 S mch push pull (bng PSIM)5Hnh 2.3 S mch khuch i iu khin6Hnh 2.4 Kha ng ct dng Mosfet v diode zener6Hnh 2.5 M hnh mt loi my bin p7Hnh 2.6 M hnh mch chnh lu8Hnh 2.7 M hnh b lc9Hnh 2.8 M hnh b cch ly9Hnh 2.9 M hnh b khuch i vi sai9Hnh 2.10 M hnh b chnh p10Hnh 2.11 M hnh b iu khin kha10Hnh 2.12 M hnh b iu khin ng ct11Hnh 3.1 S mch iu khin12Hnh 3.2 S mch push pull sau khi tnh ton thng s13Hnh 3.3 Gin ng ct 2 kha13Hnh 3.4 Gin p ng ra13Hnh 3.5 Gin p diode cha xc lp14Hnh 3.6 Gin p diode khi xc lp15Hnh 3.7 Gin dng qua diode xc lp15

1. TNG QUAN L THUYT1.1. Gii thiuB bin i dng hai transitor c hiu qu c bit in p thp.Dng hai transitor bin i DC-DC .Mi transitor ln lt dn trong mi na chu k v khng bao gi cng dn.Khi transitor A dn th cun s cp pha trn c cp in,tng t khi transitor B dn th cun s cp bn di c in .in p u ra c ly bn s cp qua diode ra ti. Half-Brigde:Dng 2 transitor bin i cho cc ng dng offline. Full-Brigde:Dng 4 transitor c th cho cng sut u ra cao nht i vi tt c cc loi ngun k trn.

Hnh 1.1 S nguyn l b push pull (half bridge)1.2. Nguyn l lm vicChuyn i theo kiu push pull hay l chuyn i theo kiu y ko Khi chuyn i Mosfet 1 l ON (chuyn i Mosfet 2 l OFF) th nng lng c chuyn giao cho cc ph ti thng qua bin p v diode D2 Khi chuyn i Mosfet 2 l ON (chuyn i Mosfet 1 l OFF) th nng lng c chuyn giao cho ph ti qua my bin p v diode D1Chu k c lp i lp li 2 trng thi ngt m ca mosfet 1 v 2 to in p u ra lin tc u ra my bin p. c im Dng hai transitor bin i DC-DC .Mi transitor ln lt dn trong mi na chi k v khng bao gi cng dn.in p u vo v u ra c cch ly vi nhau,m bo an ton cho ngi v thit b bn u vo

Hnh 1.2 Gin ng ct kha Kha Sw1 ng: D1 ng, D2 ngt

Kha Sw2 ng: D2 ng, D1 ngt

Kha Sw1. Sw2 ngt : Dng qua cc cun s cp bng 0: Dng qua Lx lin tc => D1, D2 ng

nhp nh p t

Hnh 1.3 Gin p ra Vo, dng qua cun cm ILx, p cun th cp

2. THIT K2.1. Yu cu thit kYu cu b DC/DC: Thit k b bin i DC/DC dng Buck- Boost vi cc thng s t chn nh sau:

Tn s ng ct ca kha

H s ng ct

Cc thng s linh kin , ,

in p u vo ca b chuyn i

Da vo cc thng s trn v l thuyt c cp phn I, tnh ton cc gi tr in p u ra, nhp nh in p u ra, nhp nh dng cun cm, tnh ton dng .B chuyn i DC/DC dng Buck- Boost c m phng trong Psim nh di y:

B Push Pull Thng c hiu sut khong 85% mc 350W C bin p cch ly vi 3 cun dy, thi gian ng ct kha l na chu k Cn phi ch n thi gian np x ca t in C, ng thi do bin p 3 cun dy nn vn v t thng trong cc li st cn phi c ch Sau mt thi gian tm hiu, b DC/DC cung cp in p 170VDC t ngun in p 12VDC cung cp in p cho mt b DC/AC l cn thit. Nng lng cn truyn ti l khong 250W, b bin i tt nht trong trng hp ny l b Push Pull vi hiu sut 85% v kh nng truyn ti 350W, trong khi b Full Bridge v Half Bridge c th truyn ti n 1000W v 500W tng ng.2.2. Tnh ton thng s c th thch nghi vi s thay i ca p u ra, u bi yu cu phi c mt bt so snh p ra v p ra mong mun, b so snh ny ng nhin phi cch ly gia p ra v p vo trnh lm nh hng n thng s ca mch tuy nhin vn phi thc hin c nhim v so snh p.

Hnh 2.1 Flow chart cho b Feed back

M hnh m phng di y l b DC/DC chuyn p t 12VDC sang 170 VDC. Mt pin 12V c kt ni vi 2 N-Mos vi vai tr l 2 kha ng ct. 2 kha ny s khc nhau v thi gian ng ct dn dng qua cun dy ca bin p cch ly. Nu 2 kha ny hot ng cng thi gian, n s gy ngn mch ngun v lm bo ha bin p. Cun dy bin cp c t s bin p l 1:14 bin p t 12VDC sang 168 VDC.

Hnh 2.2 S mch push pull (bng PSIM)Hai Diode cun th cp to ra mt mch chnh lu ton phn. bo v 2 diode ny khi nhng gai in p, mi diode c mc song song vi mt mch bo v RC. Sau , in p ra c a qua b lc LC vi vai tr l b lc thng thp, c nhim v loi b cc sng hi bc cao, ch cho cc sng hi vi tn s nh hn tn s ct i qua. Cui cng in p ra c cho qua mt in tr R em p ra so snh v mc 5VSau khi bin i in p, ng ra c kt ni vi mt b cch ly cng sut sau a ra ng vo b iu khin qua mt b khuch i. Sai lch gia in p ng ra v in p mong mun c a vo b khuch i. Vi sai sau khi khuch i tip tc i vo mt op-apm phn cc. Tnh hiu phn cc ny c so snh vi xung tam gic op-amp th ba iu chnh thi gian ng ct ca 2 kha MOSFET. 2 MOSFET ny c ni vi nhau qua mt cng chung, trnh trng hp c hai kha cng bt mt lc.

Hnh 2.3 S mch khuch i iu khin2.2.1. Kha ng ct (Switching)M hnh push-pull da trn 2 switches tun hon dng thng qua my bin p tn s cao.Hnh 2.4 Kha ng ct dng Mosfet v diode zener

C 2 dng switch c s dng trong m hnh: BJT v Mosfet, v chng u hot ng ch bo ha, iu cho php transitors kt hp nhng c tnh ca mt cng tc l tng. Tuy nhin, vic tn ti tr khng bn trong transitors khi hot ng ch bo ha gy nn tn tht nng lng di dng nhit. Bi v mc ch ca vic thit k nhm t c hiu sut cao do vy tr khng bn trong transitor phi thp.Mt yu t quan trng khc trong vic la chn transitor l tc ng ct ca transitor.Transior phi c kh nng ng ct nhanh v 2 l do sau y:1. Tn s ng ct phi tng thch vi tn s vn hnh ca h thng, trong trng hp ny l mach push-pull vi tn s hot ng l 50kHz. Tuy nhin, vi mch push-pull, mi transitor phi c kh nng hot ng tn s gp i tn s hot ng, bi v mi cng tc ch hot ng mt na chu k hot ng, na chu k cn li transitor ngt.2. L do th 2 nm phn nng lng tiu tn. Khi transitor chuyn t trng thi ngt sang ng, khi c tnh transitor nm min tuyn tnh vi tr khng cao. Do dng khng th gim v cun cm bn trong my bin th lm cho nng lng b lng ph. Thi gian ng ct cng nhanh, nng lng cng t b lng ph, do vy ci thin c hiu sut m hnh.in p ti a m transitor c th cung cp cng nn c cn nhc khi la chn thit b. in p phi ln hn in p ngun t trn n, ngoi ra cng nn mc thm diode zenner song song vi switch trnh s nh hng ca in p gai.Da trn nhng thng s c m t , MOSFET vi tr khng rt b l mt la chn tt nht. in p ti a ca MOSFET phi ln hn 12V DC, v nn chn N-MOS v hot ng tc nhanh hn so vi P-MOS v t hao ph hn.2.2.2. My bin pKhi tin hnh thit k b bin p, c vi thng s chnh cn chn trc khi hon tt vic thit k. Nhng thng s ny c tnh ton da trn cng thc chung.Hnh 2.5 M hnh mt loi my bin p

Trc tin ta xt 2 thng s: in p vo v in p ra. Trong thit k ny, in p vo s chn 12 VDC, in p ra khong 170 VDC. Nhng thng s khc phi chn da trn t s ng ct D. Trong thit k ny ta chn D = 0.5 phng trng hp c tht thot trong h thng. Da trn nhng thng s va chn trn t c th xc nh c t s cho my bin p. Mt iu cn lu , nu in p ra chn l 170 VDC th ta tnh ton t s my bin p khng phi l 1 s nguyn. Tuy nhin, nu ta gim in p ng ra xung khong 168 VDC, t s my bin p s trn 14. Vi t s my bin p va chn, t s ng ct gi nh lc u l 0.5, nh vy, ta tng t s ng ct D = 0.5059, in p ng ra t c s l 170 VDC.My bin p c s dng trong b push-pull thng dng c nhiu cun dy. Trong phn thit k ny, ta chn my bin p c 4 cun dy, trong 2 cun s cp v 2 cun th cp. S vng dy cun th cp gp 14 ln cun s cp. K n, kch thc li v vt liu c chn t Magnetics Company . Li phi ln c th qun c cc si dy c kich thc ln v dng trung bnh vo l khong 20 ampe. V phn vt liu li, nn c thit k chu c tn s cao, v hao ph thp, c bit l cun dy trong my bin p c qun th cng. Do , vt liu s chn l dng MMP v n c thit k vi hao ph thp nht. C th ta s chn vt liu MMP 55906. Cc thng s quan trng: ng knh trong 1.9 inches, t thm , chiu di trung bnh ca li 0.1995m, din tch mt ct 0.0227m. p dng cng thc tnh ton s vng dy phi qun qua li, lch dng ng vo phi c chn theo cng thc

Chn bng 2, Lcore = 30HSau khi tnh ton t cm ca Lcore , ta c th tnh s vng dy s cp theo cng thc:

Khi xc nh c s vng dy s cp, ta lp tc xc nh c s vng th cp N2 = 28Khi N1 c lm trn ln 2, Lcore c tnh ton li bng 71.5 HT lch dng vo cng c tnh ton li, bng 0.839A2.2.3. Chnh lu2 diodes trong mch dng mch chnh lu cu ton phn. iode D8 trn On khi switch M1 On, diode D8 di on khi switch M2 On. C 2 diodes khng bao gi on cng lc v c 2 switches cng khng bao gi on cng lc. B bo v RC gim xc c mc song song bo v diode. B gim xc c tc dng lm trit in p qu bng vic hn ch s tng p t ngt, khng c b gim xc, in p gai s i qua diode v c th nh thng n. Hnh 2.6 M hnh mch chnh lu

2.2.4. B lcS kt hp ca cun cm L1 v t C3 to nn b lc thng thp bc 2. B lc thng thp ch cho php nhng tn hiu c tn s thp hn tn s ct i qua, trong mch ny th tn s ct l: 25265 Hz. Tuy nhin y khng phi b lc l tng, do vy di thng sau tn s ct c dc l -40dB/Dec2.2.5. B cch lyHnh 2.7 M hnh b lc

gi mc in p ng ra 170VDC, cn phi iu khin thi gian ng ct ca switches. Hnh 2.8 M hnh b cch ly

Bc u tin l phi chia nh v cch ly in p ng ra. in p 170 VDC ng ra cn c chia nh xung chia 5VDC. lm c iu cn c mt in tr ln ng ra. Cch thng dng nht thc hin mt b cch ly l s dng mt n LED v mt cm bin quang. Khi n LED on, cm bin quang s c kch hot to ra dng in tng ng vi lng sng m n nhn c.2.2.6. B khuch i vi sai

Hnh 2.9 M hnh b khuch i vi saiTn hiu ng ra sau khi c a v thang 5V c ni vo chn (-) ca op-amp s 1 so snh vi mt in p chun 5V c ni vo chn (+), vi sai sau c khuch i, t l khuch i c tnh ton da trn cc in tr R2.2.7. B chnh pSau khi c tnh hiu sai lch ng ra, cn thit phi iu chnh rng xung iu khin tng gim thi gian ng ct ca cc kha, u tin phi bo v IC khi cc gai in p bng mch cch ly. Hnh 2.10 M hnh b chnh p

Dng in i vo b chnh p s c quan h trc tip n in p ng ra, t c mi lin h trc tip n in p ra ca op-amp. in p ny chnh l lch m in p ra cn thay i t c in p mong mun. Ti thi im ny, vi sai c khuch i tr v tnh hiu 1 cch nhanh chng. Tuy nhin, nu li l qu thp, s mt rt nhiu thi gian t c n nh, v nu li qu cao, mch s khng n nh c. Sau khi vi sai c khuch i, mt in p phn cc c cng vo tn hiu. in p ny xc nh chu k ng ct t c p ra mong mun, vi sai bng 0. 2.2.8. B iu khin t s ng ctChu k ng ct ca cc kha c xc nh da trn p ra ca b Converter. Nu in p ra cha t c gi tr mong mun, chu k ng ct c tng ln cung cp thm nng lng qua cun bin p. Khi in p ra t mc mong mun, n s vt qua mc ny, lc ny chu k ng ct li c gim gi gi tr ny. Ng vo ca b iu khin chu k l sng tam gic tn s 50kHz. Sng tam gic ny c to ra sau khi cho xung vo 1 omp-ap cng in tr v t in. Hai tn hiu, tn hiu iu khin v sng tam gic c a vo 2 chn so snh ca op-amp, sng tam gic ni vo chn (-), sng iu khin ni vo chn (+).Chn cng quyt nh in p lm bo ha kha MOSFET, khi tn hiu iu khin nh hn xung tam gic, chu k ng ct l 0 v cc MOSFET s khng c bt, khi in p iu khin tng ln, mt phn in p iu khin ln hn xung tam gic, lm cho b so snh t tch cc cao cng vi MOSFET. Khi in p iu khin ln hn hn xung tam gic, chu k ng ct l 100%. Trong mch push pull, cn trnh chu k ng ct l 100% cc li dy c th khi ng li.Hnh 2.11 M hnh b iu khin kha

2.2.9. B iu khin ng ctMc ch ca vic chuyn mch iu khin, l lm thay i trng thi ca MOSFET cng nhanh cng tt. u vo ca mch iu khin l xung PWM vi chu k ng ct s hot ng ti. in p xung u vo s da trn cc yu cu ca Mosfet. Hu ht MOSFETs s dng trong thit k ny s ch cn mt in p cng t 3,6-6 volt. Mt trong nhng yu cu quan trng i vi chuyn mch iu khin l kh nng a ra mt s tr (delay) vo cc tn hiu L do l s c mt tn hiu PWM c sinh ra t cc vng iu khin (control loop) v mt trong hai kha phi phn ng chnh xc ti T/2 Hnh 2.12 M hnh b iu khin ng ct

Vic hai tn hiu ni trn trong vng iu khin c th t c sm, kt hp vi thi gian tr ca tn hiu khi tn hiu i vo mt trong cc kha. iu ny m bo tt hn vic ng b chu k ng ct cho mi kha.

3. KT QU M PHNGSau khi tnh ton li cc thng s, kt hp vi cc linh kin bo v mch, gim nhiu, gai p. Ta c s cui cngHnh 3.1 S mch iu khin

Hnh 3.2 S mch push pull sau khi tnh ton thng s3.1. Gin p kha

Hnh 3.3 Gin ng ct 2 kha3.2. p ng ra

Hnh 3.4 Gin p ng rap ng ra vi kt qu 168V, do cc thng s tnh ton thc t, lm st p. Tuy nhin kt qu chnh xc vi l thuyt vi gin l thuyt. Nhn thy ta tng gi tr cun cm Lm n p hn giai on qu u tin.Gi tr ca b lc LC c xc nh bi cng thc

Chn L= 20uH, C= 20uF, in p ng ra s gn nh n nh sau 4ms. iu ny th hin rt thp. Do gi tr LC s hon thnh mc tiu 2% gn theo m phng. 3.3. p diode

Hnh 3.5 Gin p diode cha xc lp

Hnh 3.6 Gin p diode khi xc lpin p nh thng ca diode ( y s dng diode STTH5L06) chnh lu in p cao cc k nhanh. Thi im ban u khi mch hot ng, do c cc gai in p, in p t khong 450V. Khi mch hot ng n nh, in p t khong 335 nh hnh 3.6.3.4. Dng qua diode

Hnh 3.7 Gin dng qua diode xc lpBan u, mch bt u hot ng, dng tng t bin, t khong 50A. Khi mch hot ng n nh, dng t khong 1.7A nh hnh 3.6

4. KT LUNDa vo cc nghin cu c, nhu cu cho 1 b bin i in p 12V-170V DC-DC l cn thit. Cho b bin i in p 250W, m hnh push pull l hiu qu nht vi hiu sut ln n 85% 350W. Cc b Half brigde v Full bridge hot ng vi mc nng lng cao hn.Qua bo co ny, nhm thc hin c nhng vic: Nghin cu v kim chng li l thuyt Thit k c b DC DC converter : push pull theo tnh ton l thuyt Chn c cc linh kin vi thng s thc t. Thit k b iu khin khuch i Kim tra li kt qu Nhn xt, bo co cui cngNhng v nhiu l do, thi gian hn ch, nn nhm cha thc hin thm nhng b khc.

5. NG DNG CA B PUSH PULLVi u im ng ct lin tc hai kha th lun lun xut hin dng in ti lin tc trn ti. Chnh v vy b Push Pull cho hiu sut bin i cao nht v c dng nhiu trong: 5.1. B ngun UPSUPS (Uninterruptible Power Supply) l mt thit b c th cung cp tm thi in nng nhm duy tr s hot ng ca thit b s dng in li gp s c (mt in, st gim in p qu thp, s c khc...) trong mt khong thi gian vi cng sut gii hn theo kh nng ca n. Vit Nam, UPS thng quen c gi l: ci lu in hayb lu in, cc lu in...

5.2. B ngun Inverter ( Bin tn )Bin tnl thit b lm thay i tn s dng in t ln cun dy bn trong ng c v thng qua bin tnc th iu khin tc ng c mt cch v cp, khng cn dng n cc hp s c kh.bin tnthng s dng cc linh kin bn dn ng ngt tun t cc cun dy ca ng c lm sinh ra t trng xoay lm quay r-to (rotor).Cc b bin i tnhPush Pull Converter

4

TI LIU THAM KHO1. Larry Nelson Jr. and Eric Ruscitti Sdf, High Voltage DC-DC Converter, Worcester Polytechnic Institute, Department of Electrical and Computer Engineering2. PGS TS Phan Quc Dng, Gio trnh cc b bin i tnh.3. Hill, C. J. Switch Mode Power Supplies. Ed. C. J. Hill. 15 Mar. 1998. 29 May 2015 . 4. Push-pull converter. 2006. Wikipedia. 29 May 2015 .

PH LC A: LI MY BIN P

Nhng thng s ny ch ph hp vi MPP cores.

PH LC B: MOSFET

PH LC C: CUN CM B LC

PH LC D: T B CHNH LU

PH LC E: OP-AMP