TM HIU KHO ST NGUN H QUANG ARC 2501. Gii thiu tng quanMy hninverter c nhiu u th so vi cc loi my hn s dng bin p truyn thng. My hn inverter nh gn,c th xch tay c, d dng di chuyn hn khi hn cng trng. Thm na, my inverter cho cht lng hn cao, c th ng dng hn nhiu quy trnh nh hn h quang tay,hn MIG, TIG, hn dy li thuc, ct c kim loi v hn ch dng xung. V dng my cao cp hn, my hn inverter tch hp cng ngh iu khin dng sng cho php iu khin tt hnbin thin ca h quang v t ng tinh chnh h quang to mi hn tt nht.

Arc 250 l my hn 3 pha, hot ng da trn cng ngh Inverter, y l b ngun c kh nng p ng c vic cung cp ngun h quang trong cng ngh m chn khng. Vi nhng c tnh k thut sau: in p ra max 70VDC khi khng ti in p ra max 30VDC khi ti Dng in DC max 250ADC mp m 5% n nh theo thi gian 3% in p nui 3pha 380VAC 10% Hiu sut 85%2. Nguyn l hot ng ca my hn Inverter

Hnh 1.1: Nguyn l my hn InverterL loi my hn c nghin cu pht trin mnh trong nhng nm gn y nh s dng nhng cng ngh tin tin ca IC v cc kha ng ngt in t. Cu to my Inverter c chia lm 3 phn r rt nh sau:Phn 1: Chuyn i ngun AC220V thnh ngun DC280V (Phn chnh lu)Phn 2: Phn ny bao gm cc kha ng ngt in t cng sut IGBT v mch iu khin. Nhim v ca phn my l bm ngun DC280 ra thnh ngun AC280 tn s 20Khz cung cp cho cun dy s cp my bin p cao tn. Vic ny c thc hin thng qua vic ng ngt lin ng gia hai b kha (K1, K2) v (K3, K4) ca IGBT. Vi chu k ng ngt ca mi kha l 50s, vic ny s rt kh thc hin nu khng c s h tr ca cc kha in t nh IGBT.Phn 3: Phn ny bao gm cc my bin p trung tn c im gia 280V/75/V v b phn chnh lu tn s cao t 75VAC 20Khz thnh 75VDC. Ngun ny c cp cho h quang trong hnh 1.1. in p 75V c gi l in p h mch. trng thi h mch cc kha K (K1, K2, K3, K4) lun lun trong trng thi ng ti a. Khi ch hn xy ra mch iu khin s nhn c tn hiu dng in hi tip t cm bin dng v em so snh vi gi tr t. Da trn kt qu so snh ny mch iu khin s a ra tn hiu iu khin quyt nh thi gian ng m ca cc kha thng qua phng php iu rng xung PWM.3. Cu to chi tit ca cc khi trong ARC 250V c bn cu to ca cc my hn Inverter tun theo s hnh 3.1. Sau y chng ta s i kho st cu to ca tng khi chc nng trong my ARC 250.

Hnh 3.1: S b bin dng theo kiu Inverter3.1. Khi chnh lu, lc u vo

Hnh 3.2: Khi chnh lu, lc u vo

Trong ARC 250 khi chnh lu u vo s dng 3 cu diod cng sut ln chnh lu ngun 3 pha thnh ngun mt chiu, cc diod c mc theo s hnh 3.2.

Hnh 3.2: S mch chnh luSau khi chnh lu ngun c a vo h thng lc bao gm 4 t C1, C2, C3, C4, dng tn hiu sau khi qua khi chnh lu v lc.

Hnh 3.3 dng tn hiu sau khi qua khi chnh lu v lcBn cnh trong h thng ngun vo cn c mt rle chng qu ti c ng m thng qua Mosfet IRFZ24N.3.2. Khi ng ct ng lc tn s cao

Hnh 3.4: Khi ng ct ng lc tn s caoKhi ny s dng cc kha in t IGBT c mc vi nhau theo s mch cu ton sng nh hnh sau:

Hnh 3.4: S ng lc ca mch cu ton sng

Mi transistor trong hnh trn tng ng vi mt hoc nhiu transistor mc song song (vi ARC 250 l 5 transistor) mch cha hai nhnh l Tr1, Tr2 thuc nhnh A v Tr3, Tr4 thuc nhnh B. Cc transistor c xp thnh tng i (Tr1 v Tr4) v (Tr2 v Tr3). Cc transistor trong m cp tt v m ng thi. Ngoi ra mi cp c th xem nh mt kha ng ct, khi mt ci bt th ci kia phi tt v ngc li. an ton cho cc transistor th mi cp khi mi phi cch nhau mt khong thi gian t. Chng hn khi cp Tr1, Tr4 ang dn th cp Tr2, Tr3 phi kha, cp Tr2, Tr3 ch c php thng sau khi cp Tr1, Tr4 kha mt khong t. khong t ny c chn t =0,1T vi T l chu k ng ngt ca cc transistor. Nu mt cp ang dn m cp kia m th s xy ra ngn mch, diu ny s gy ph hy transistor.Gin song ca mch cu ton sng.

Hnh 3.5: Gin sng ca mch cu ton sngT gin sng ca mch cu ton sng trn ta thy rng dng xung iu khin ca tng cp transistor phi ging nhau tuyt i. Khi c xung iu khin kch m Tr1 v Tr4 th in p ngun lc ny s t ln ti, lc ny s c dng qua Tr1 qua ti sau qua Tr4 v trung tnh ngun. lc ny s c mt in p ngc t ln cp van ang b kha v cp van ny phi chu in p ngc y. Khi Tr1, Tr4 c lnh kha th Tr2, Tr3 vn cha c php thng, chng s thng sau khong thi gian t, lc ny dng s qua Tr3 qua ti ri qua Tr2 v trung tnh ngun. Do in p i cc tnh nn dng sng u ra l dng sng vung xoay chiu.Vic ng m cc kha c iu khin bng tn hiu ca khi iu khin.3.3. Khi iu khin

Hnh 3.6: S khi mch iu khin tng qutTrong mch iu khin quan trng nht l khi to xung, nhim v ca khi to xung l to ra hai xung c dng ch nht tn s c nh v rng xung c th thay i. Tn hiu ng m cc kha c to ra da trn phng php iu ch rng xung PWM. rng ca xung vung c bin i c kt qu u ra trung bnh ca dng mong mun

Trong f(t) l hm ca sng vung chun. Phng php n gin nht v hay c s dng nht pht ra tn hiu xung vung PWM l mt my pht xung tam gic hoc rng ca v c so snh vi xung tn hiu chun.

Vi ARC 250 khi to xung iu khin s dng IC SG3525A, y l IC chuyn dng trong ngun xung, n c th c s dng trong cc mch ngun sau: Mch bin i y ko. Mch bin i bn phn. Mch bin i ton phn. Mch bin i chuyn mch. So vi nhng IC c cng chc nng khc nh: TL494, SG3524 IC SG3525 c nhng u im sau: C tch hp bli MOSFET hoc IGBT trn IC. Tn s hot ng: 100 Hz n 400 kHz. C tch hp chn shutdown trn IC tt dao ng ng ra ca IC. C tnh nng khi ng mm, cn gi l soft-start ( rng xung li MOSFET tng t t khi khi ng ch khng t ngt). C th iu chnh thi gian m c 2 MOSFET hoc IGBT u ngng dn (thi gian cht).S chn ca SG3525

Hnh 3.7: S chn ca SG3525

Hnh 3.8: S khi cha nngS ghp ni ca SG3525 trong khi to xung

Hnh 3.9: S mch iu khin bn cu li bng bin p xung

Hnh 3. 10: Khi iu khinTheo yu cu mch lc l mch iu khin bn cu, ti mi thi im ch c mt van dn nn xung to ra trn hai knh A, B lch pha nhau 180o3.4. Khi x l u ra

Hnh 3.11: Khi x l u ra

Hnh 3.12: Khi chuyn i, chnh lu u ra

Hnh 3.13: Cun khng lcDng in sau khi qua khi Inverter a vo bin p xung bin i in p xung mc 75Vsau tip tc c chnh lu qua cc Diod sau qua cun khng lc v cp vo hai u que hn.

4. Thit k s nguyn l

Hnh 2.1: H thng ngun nui cho thit b5.

Hnh 2.2: S mch iu khin ca ARC-25

Hnh 2.3: S mch iu khin ca VZS ARC-256.

7. Hnh 2.4: S mch iu khin cho IGBT8.

Hnh 2.5: S khi u vo ca ARC-250

Hnh 2.6: S khi chuyn mach ZVS cng sut v khi lc u ra