i NHN XT CA GIO VIN HNG DN _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ H Ni, ngy 28 thng 12 nm 2012 Gio vin hng dn ii LI NI U Ngy nay vi s pht trinnhanh chng ca k thut bndn cng sut ln, cc thit b bin i in nng dng ccphn t bn dn cng sut c s dng ngy cng nhiu trong cng nghip v i sng, p ng c nhu cu cao ca x hi.Trong thc t s dng in nng ta cn thay i tn s ca ngun cung cp,cc bbintnpngrtttvvnny,vcsdngtrongcchtruyn ng inB nghch lu l b bin tn gin tip bin i t in mt chiu sang xoay chiu n c ng rt nhiu trong cc h truyn ng in. Trong thi gian hc tp v nghin cu chng em c hc mnin t cng sut v ng dng trong sn xut v i sng. V vy nm vng l thuyt v vn dngkinthchcvothctchngemnhnnmnhcviti thit k b nghch lu p mt pha Trong thi gian thc hin n chng em xin chn thnh cm n ti cc thy c trong b mn Thit B in - in T c bit l thy Nguyn Thnh Khang tn tnh hng dn v ch bo chng em.Tuy nhin do thi gian v kin thc c hn nnskhngtrnhkhinhngthiustkhithchinnny.Vvychngem rt mong nhn c s ng gp ca thy c ti c hon thin hn. Chng em xin chn thnh cm n! iii MC LC CHNG 1: C S L THUYT...................................................................... 1 1.1 Nghch lu ..................................................................................................... 1 1.1.1 Nghch lu ph thuc .............................................................................. 1 1.1.2 Nghch lu c lp .................................................................................. 1 1.1.3 Nghch lu c lp in p ...................................................................... 1 1.2 Ci thin in p ra cho nghch lu c lp in p ....................................... 3 1.3 iu ch PWM cho nghch lu c lp in p mt pha ................................ 4 1.3.1 PWM (Pulse Width Modulation) ............................................................. 4 1.3.2 Phng php SINPWM ........................................................................... 5 CHNG II: MCH IU KHIN ................................................................... 8 2.1 Gii thiu v dsPIC33FJ12MC202 ................................................................ 8 2.2 Cu hnh dao ng dng PLL cho dsPIC33F ............................................... 10 2.2.1. B dao ng ......................................................................................... 10 2.2.2. Cu hnh: .............................................................................................. 10 2.3 Module PWM .............................................................................................. 13 2.3.1 Cc ch vn hnh .............................................................................. 13 2.3.2 PWM Period .......................................................................................... 13 2.3.3 PWM duty cycle .................................................................................... 14 2.3.4 B to thi gian dead time ..................................................................... 15 2.3.5 Cc ch PWM Output ....................................................................... 15 2.4 Code ............................................................................................................ 16 CHNG III: MCH LI ................................................................................ 18 3.1 S mch li ............................................................................................. 18 3.2 Nguyn l bootstrap ..................................................................................... 19 CHNG IV: MCH NG LC................................................................... 20 CHNG V: B LC U RA ....................................................................... 23 5.1.Tng qut v cc b lc ............................................................................... 23 5.2 La chn phng n lc .............................................................................. 24 5.3 Tnh ton b lc LC: .................................................................................... 25 CHNG VI: S ......................................................................................... 26 6.1 S khi: .................................................................................................. 26 iv 6.2 S mch to ngun .................................................................................. 26 6.3 S khi iu khin .................................................................................. 26 6.4.S mch li mosfet .................................................................................. 27 6.5 S mch ng lc ................................................................................... 27 CHNG VII: KT QU.................................................................................. 28 7.1 Mch m phng s dng Proteus : ............................................................... 28 7.2 Tn hiu iu khin o c......................................................................... 29 7.3Mch tht .................................................................................................... 30 Ti liu tham kho ............................................................................................... 31 Website tham kho: ............................................................................................. 31 DANH SCH HNH V Hnh 1.1: Cc s nghch lu c lp in p mt pha ......................................... 2 Hnh 1.2: S nghch lu p mt pha .................................................................... 2 Hnh 1.3: Cc sng hi bc cao ................................................................................ 3 Hnh 1.4: Phng php PWM .................................................................................. 4 Hnh 1.5: in p ra b nghch lu PWM n cc .................................................. 5 Hnh 1.6: th xc nh thi im kch m van cng sut ..................................... 6 Hnh 1.7: iu ch rng xung lng cc ............................................................ 7 Hnh 2.1: Cc h vi iu khin PIC v dsPIC .......................................................... 8 Hnh 2.2: S khi ca dsPIC33FJ12MC202........................................................ 9 Hnh 2.3: S chn ca dsPIC33FJ12MC202 ..................................................... 10 Hnh 2.4: Cu hnh PLL cho dsPIC dng MC ........................................................ 11 Hnh 2.5: Ch Continous Up/Down Counting ................................................... 13 Hnh 2.6: Thay i gi tr PTPER .......................................................................... 14 Hnh 2.7: Thay i gi tr duty cycle ..................................................................... 14 Hnh 2.8: S khi ch hot ng h tr ........................................................ 15 Hnh 2.9 : V d u ra PWM ch hot ng h tr .......................................... 15 Hnh 3.1: Kha MOSFET tng trn ....................................................................... 18 Hnh 3.2: IR2110 ................................................................................................... 19 Hnh 3.3: S mch nguyn l bootstrap ............................................................ 19 v Hnh 3.4: S lp mch IR2110 .......................................................................... 19 Hnh 4.1: BJT, MOSFET v IGBT ........................................................................ 20 Hnh 4.2: IRFP460 ................................................................................................ 22 Hnh 5.1: Lc 2 mt cng hng ........................................................................... 24 Hnh 5.2: b lc mt mt cng hng ni tip ....................................................... 24 Hnh 5.3:B lc LC n gin ................................................................................. 24 Hnh 5.4: B lc LC .............................................................................................. 25 Hnh 5.5: Cun cm lc ......................................................................................... 25 Hnh 6.1: S khi.............................................................................................. 26 Hnh 6.2: Mch to ngun ..................................................................................... 26 Hnh 6.3: Mch iu khin .................................................................................... 26 Hnh 6.4: Mch li mosfet ..................................................................................... 27 Hnh 6.5: Mch ng lc ....................................................................................... 27 Hnh 7.1: S m phng trong proteus ............................................................... 28 Hnh 7.2: Kt qu m phng trong proteus ............................................................ 28 Hnh 7.3: Tn hiu iu khin ................................................................................ 29 Hnh 7.4: Mch tht ............................................................................................... 30 1 CHNG 1: C S L THUYT 1.1 Nghch lu Nghch lu l thit b bin i nng lng dng in mt chiu thnh nng lng dng xoay chiu vi tn s c nh hoc thay i. 1.1.1 Nghch lu ph thuc Nghch lu ph thuc c tn s in p ca dng in xoay chiu chnh l tn skhngththayicaliin.Shotngcanghchlunyphiph thuc vo in p li v tham s iu chnh duy nht l gc iu khin c xc nh theo tn s v pha ca li xoay chiu. 1.1.2 Nghch lu c lp Nghch lu c lp hot ng vi tn s ra do mch iu khin quyt nh v c th thay i ty , tc l c lp vi li in. Nghch lu c lp c chia lm 3 loi: Nghchluclpinp,chophpbinitinpmtchiuEthnh ngun in p xoay chiu c tnh cht nh in p li: trng thi khng ti l cho php cn trng thi ngn mch ti l s c. Van bn dn trong nghch lu c lp in p hot ng di tc ng ca sc in ng mt chiu E, v vy thchhplvaniukhinhonton:ccloitransistorBJT,MOSFET, IGBT hay GTO Nghchluclpdngin:chophpbinngundngmtchiuthnh ngun xoay chiu. Nghchluclpcnghng:ccimkhihotnglunhnhthnh mt mch vng dao ng cng hng RLC. Vi nghch lu c lp dng in v nghch lu c lp cng hng, do tnh chtmch cho php ng dng tt van bn iu khin thyristor nn chng thng c dng. Trong phm vi n ta ch xt nghch lu c lp in p. 1.1.3 Nghch lu c lp in p a. c im cu to Do ngun uvo camch nghch lu l ngun p nn mch nghch lu p c t C (C ) c mc song song vi in tr ngun. Trong hnh 1.1 l mt s s nghch lu p mt pha trong s cu hnh 1.1a, bn cu hnh 1.1b v s hnh tia 1.1c tuy nhin dng in p ra v cc tham s ca chng ging nh nhau, v vy chng ta ch xt trn c s s cu hnh 1.1a. S nghch lu p mt pha c m t trn hnh 1.1a gm 4 van ng lc T1, T2, T3, T4 v it D1, D2, D3, D4 tr cng sut phn khng ca ti v li. 2 1.1a1.1b 1.1c Hnh 1.1: Cc s nghch lu c lp in pmtpha b. Nguyn l lm vic na chu k u tin, cp van T1, T2 dn in, ph ti c u vi ngun. Do ngun l ngun p nn in p trn ti bng E, sau mt khon thi gian T1, T2 bkhangthiT3,T4mra.Tisc uvongunmtchiutheo chiu ngc li. Sau mt khong thi gian t qu trnh c lp li. in p nghch lu c dngxungvung,ctnsfNtoranhngmcccpvanT1,T2vT3,T4 mt cch c chu k: fN=fk Do khi thay i tn s iu khin fk c th thay i tn s nghch lu fN tu . Hnh 1.2: S nghch lu pmtpha 3 c. u nhc im u im: oiu chnh c tn s fN oin p ra ca nghch lu c th dng cc phng php khc nhau gim sng hi bc cao oCc van c s dng l cc van iu khin hon ton do d dng iu khin ng ct cc van oCng sut b bin i ph thuc vo cng sut ca van,m cng sut ca van ng lc ngy cng ln vi kch thc ngy cng nh gn Nhc im: oS lng van s dng kh nhiu oin p ra c sng hi bc cao nh hng ti thit b in Hnh 1.3: Cc sng hibc cao 1.2 Ci thin in p ra cho nghch lu c lp in p Nu ti khng c i hi v dng p ra hnh sin s khng cn quan tm n b lc. Tuy nhinvi cc ti xoay chiu c thitk ch to lmvicvi ngun in p hnh sin (nh ng c in,mybin p lc) cn phi ci thin dng in p ra theo yu cu ca ti. C mt s phng php sau c s dng:Dng b lc tn s th ng: vi dng ti ln v in p cao b lc phi thc hin bng cc phn t th ng L v C, iu ny dn n tn tht cng sut khng th trnh khi lmgim hiu sut h thng, mtkhc lm tng ngk kch thc thit b. Hn na hiu qu lc tn ca b lc th ng khng cao. 4 Phngphpcnginpnhiunghchluclpvigcphalchnhau hoc tn s khc nhau: phng php ny thc hin kh n gin, cc van hot ng nhnhngvtnschuynmchthp,nhngmchlcvmchiukhinphc tp, v vy cng t c dng. Phng php iu ch PWM: trong mt khong dn ca van, transistor khng dn lin tc m ng ct rt nhiu ln vi rng xung dn thay i. iu ch hnh sin (SPWM)iu ch vector (VPWM) Phng php bm xung chn lc trongkhongvan dn: ccvankhng ng mnhiulnnhtrongphngphpiuchPWMmthngchdi10ln. Phng php ny s ph hp khi s dng cc van khng c kh nng lm vic tn s cao nh GTO, IGBT hay thyristor (c km chuyn mch cng bc). Ta s dng phng php iu ch SINPWM kt hp vi b lc LC. 1.3 iu ch PWM cho nghch lu c lp in p mt pha 1.3.1 PWM (Pulse Width Modulation) PWM l phng php iu chnh in p ra ti hay ni cch khc l phng php iu ch da trn s thay i rng ca chui xungvung dn n s thay i in p ra. Cc PWM khi bin i th c cng 1 tn s v khc nhau v rng ca sn dng hay hoc l sn m Hnh 1.4: PhngphpPWM Git1lthigianxungsndng(kham)cnTlthigiancac sn m v dng, Umax l in p ngun cung cp cho ti. 5 ==> Ud = Umax.( t1/T) (V) hay Ud = Umax.D Vi D = t1/T l h s iu chnh v c tnh bng %Nh vy ta nhn trn hnh th dng iu ch xung th ta c : in p trung bnh trn ti s l : Ud = 12.30% = 3,6V ( vi D = 30%) Ud = 12.60% = 7,2V (Vi D = 60%) Ud = 12.90% = 10.8V (Vi D = 90%) 1.3.2 Phng php SINPWM a. Phng php iu khin PWM n cc: Hai i lng cn phi quan tm khi xem xt v PWM l: sng mang v song iu bin: Sngmang:Sngmanglsngtamgicctnsrtln,cthnhng chc thm ch hng trm kHz. Sng iu bin: Sng iu bin l sng hnh sin c tn s bng tn s sng c bn u ra ca b nghch lu. Sng iu bin chnh l sng mong mun u ra ca mch nghch lu. Hnh 1.5: in p rabnghch lu PWM n cc Nhnthyrngdintchcamixungtngnggnvidintchdi dngsnghnhsinmongmungiahaikhongmlintip.Cciuhaca sng iu ch theo phng php PWM gim r rt theo phng php ny. xc nh thi im kch m cn thit tng hp ng dng sng u ra theo phng php PWM (n cc) trong mch iu khin ngi ta to ra mt sng sin chun mong mun v so snh n vi mt dy xung tam gic c biu din trn hnh 1.6.Giao im ca hai sng xc nh thi im kch m van bn dn. 6 Hnh 1.6: thxc nh thi imkchm van cng sut inpurabnghchludngphngphpPWMccikhich xungvung,cnghalkhiuracaPWMgingnhbnghchlungun p.Khiinpiukhincnggimthbrngcaxungcnggimvtrng xungcngtng,dovyinpragim.Vvycthiukhininpura bng in p iu khin. Qu trnh a xung c tn s cao vo s to ra ng ct tn s ln do vy s lm tng cc iu ha bc cao. Nhng c th d dng lc ra iu ha bc thp v tn s c bn sin hn. Bn cnh ng c l ti in cm nn d dng lm suy gim cc iu ha bc cao c in p v dng in. b. Phng php iu khin PWM lng cc Thay cho phng php iu khin PWM n cc nng cao cht lng iu khin ta c phng php iu khin PWM lng cc.Cc MOSFET c kchm theotngcpnhmtrnhkhonginpvkhng(lngcc).Gininp iu bin PWM lng cc c biu din trn hnh 1.7. Phn in p ngc trong nachukurartngn.xcnhthiimvanbndnngitaiuch sngtamgictnscaobngsngsinchunvvykhngtolchphagia sng tam gic v sng hnh sin cn iu bin 7 Hnh 1.7: iu ch rngxung lng cc c. So snh hai phng php HaiphngphptrnlhaiphngphpnghchluPWMcbn.Vcu trcmchnglckhngcgkhcnhaumchkhcnhauvnguyntciu khinchuynmchccvanbndn.Haiphngphptrncchanhngyu im v nhc im nht nh: Phng php PWM n cc:ou im: Mch iu khin n gin do khng c phn t in p m trong thnh phn in p pha. S lng chuyn mch ca van bn dn t do vy tn hao chuyn mch thp. oNhc im: in p ra c bin khng cao khi in p ra yu cu gitrcnkhngthkhpngdokhnngchuynmchcacc van bn dn. Phng php PWM lng cc: ouim:inpracbinln,ckhnngiukhininp nh cng nh tn s. Kh nng p ng yu cu cao v n nh dng. oNhc im: Nhc im ln nht ca nghch lu PWM lng cc l sphctpcamchiukhindophiphihpngctcacc vanbndn.Phsnghicaiuchncctthniuch lng cc. y ta s dng phng php pwm lng cc. 8 CHNG II: MCH IU KHIN 2.1 Gii thiu v dsPIC33FJ12MC202 HviiukhinPICvdsPICdohngMicrochipchtovsnxutvi cngnghhini,phhpchoccngdngnginnphctp.cbit ngoi ngn ng lp trnh assembler nh cc MCU khc, ngi dng c th lp trnh trnngnngquenthucnhC(C18,C30,CCSC,MIKO_C,HI-TECHPICC), Pascal ( MIKO_PASCAL) thng qua cc phn mm h tr. Hnh 2.1: Cch vi iukhin PIC v dsPIC Tytheoccngdngcthngitachnccchpviiukhinkhc nhau(theo hng dn ca nh sn xut). y ta chn chip thuc h dsPIC33 c th l dsPIC33FJ12MC202 c mt s c im chnh sau: MCUdsPiccthitkdatrnkintrcRISC,hotngtminp rngt2.5-5.5V,cngsutthp,ctcxlcaodosdngcngngh CMOS,pngcyucutnhtonln,pngnhanhvyucu chnh xc cao C b nh RAM l 1k, ba b timer 16-bit BnknhInputCapture,haiknhOutputCompare,tmknh16bitMotor PWM, mt giao tip Quandrature Encoder, mtgiao tip UART, baExternal Interrupts, mt ADC 10 bit 6 knh, 21 chn I/O dsPIC33 c 4 ngun dao ng,c b chia PLL,chu k my ca dsPIC33 khng gingviPIC.DaongvocaPICsdng4daongthchin1 lnh,trongkhibdaongvocadsPIC33thngquabchia(nhntn 9 s) PLL,sau dng 2 chu k thc hin 1 lnh.Thng thng PIC cho php dng thch anh 20MHz v chy 5MIPS, trong khi dsPIC33 cho php dao ng FOSC ti 80MHz v chy ti a 40MIPS. S khi ca dsPIC33FJ12MC202: Hnh 2.2: S khi cadsPIC33FJ12MC202 10 S chn ca dsPIC33FJ12MC202: Hnh 2.3: S chn cadsPIC33FJ12MC202 2.2 Cu hnh dao ng dng PLL cho dsPIC33F2.2.1. B dao ng ChukmycadsPIC33FkhnggingviPIC.DaongvocaPICs dng 4 dao ng thc hin 1 lnh, trong khi b dao ngvo ca dsPIC33F thng qua b chia (nhn tn s) PLL, sau dng 2 chu k thc hin 1 lnh.Thng thng PIC cho php dng thch anh 20MHz v chy 5MIPS, trong khi dsPIC33F cho php dao ng FOSC ti 80MHz v chy ti a 40MIPS. 2.2.2. Cu hnh: Vic cu hnh cho dsPIC33F tun th cc nguyn tc sau:Tn s m lnh:FC = F0SC2 FCYtngngtrctipviMIPS(MillionInstructionsPerSecond). Ngha l nu FCY = 40MHz th tng ng dsPIC33 chy 40MIPS. y l tn s cho php ti a ca dsPIC33.Tn s dao ng: F0SC = FIN _HN1 N2] Trong : N1 = PLLPRE + 2 N2 = 2 x (PLLPOST + 1) M= PLLDIV + 2 Tn s ny t gi tr ln nht l 80MHz, d cu hnh PLL hay s dng ngun dao ng kiu g i na cng khng c php vt qu tn s ny. 11 Vic cu hnh PLL c c th cho tng dng dsPIC khc nhau, y chng ta ly v d dng MC - Motor Control: Hnh 2.4: CuhnhPLL chodsPICdng MC Ngundaongvocthlthchanhhocbdaong(thngccbn gi l thch anh 4 chn) hoc l ly ngun dao ng c to ra t con chip khc. BPLLlphngiacahnh.PLLccuhnhbiccthanhghiPLLPRE, PLLPOSTvPLLDIVnhtrnhnh.Tnsdaongcthcvitlicth nh sau: Gi s chng ta mun to tn s dao ng FOSC l 80MHz (tn s ti a) vi thch anh s dng l 10MHz, ta phi tnh ton v cn i cc h s M, N1, N2. Khi ch vic thay th n v t vo cc gi tr ca PLLDIV, PLLPRE v PLLPOST.Nu dng thch anh hoc dao ng ngoi, ta khng c php s dng tn s nm ngoikhong 1.6MHz n 16MHz. Qua b chia PLLPRE, tn s khng c vtqu0.8MHzn8MHz.trcbchiaPLLPOSTkhngcnmngoi khong 100MHz n 200MHz. N2 ch c th l 2, 4, 8 sao cho gi tr trc khi qua b chia PLLPOST nm trong khong 100MHz n 200Mhz => ta c h s N2. B chia vi h s M rt rng, nm t 2 n 513. N1 nm t 2 n 33. Vy chng ta s chn N1 sao cho tn s dao ng t thch anh vo sau PLLPRE nm trong khong 0.8MHz ti 8MHz v cui cng th chng ta chn M.Viyucutrongbi:tcFcy=40MHz,tngngviFosc=80MHz c tin hnh nh sau: ChnM=40;N1=N2=2(tngngPLLPRE=38,PLLPOST=0,PLLDIV=0); FIN=8MHz 12 Ta chn P1TMRPrescaler=4.Vi cch chn nh trn Fcy=40MHz,tn s sng mang 10khz(tnsngctcamosfet)tatnhcgitrcnnpvothanhghi P1PTER c tnh nh sau: P1PTER=40M/(Fpwm * 4 * 2) 1=499 Sng iukhin (Udk) c to bi bng cch to bng sin cgi tr t 0 ti 2 tng trng cho mt chu k ca sng iu khin sin.Nh bit sng iu khin mang thng tinv bin vtn s sng hic bn ng ra ca nghch lu.Nh vy thay i bin v tn s ca sng u ra nghch lu ta thay i bin v tn s ca sng iukhin.Ngoi ra bin ca sng ra cng ph thucvo h s iu bin ma. y ta chn ma trnh trng dn khi kha ny ang ON , kha kia ang OFFMi cp xung PWM i nghch u c mt counter 6 bit m xung, chn khong dead timevo xung PWM. Mi b to dead time c b pht hin cnh ln vcnhxungcktnivibsosnhdutycycle.Deadtimecnpvo timerkhi pht hin PWM cnh ln hay cnh xung. Ty vo xung PWM ang cnh ln hay cnh xung, m 1 khong thi gian chuyn tip c lm tr cho n khi timer m v zero. 2.3.5 Cc ch PWM Output Single Event PWM Operation Edge-Aligned PWM Center-Aligned PWM Complementary Mode Independent PWM Output Mode Trongchhotnghtr(Complementarymode),micptnhiu PWMthuctmttnhiuPWMhtr(ComplementaryPWMsignal). Khongthigianngh(DeadTime)cthclachnavotrongqu trnh ng ngt cc kho , khi c hai tn hiu c cng trng thi tch cc trong mt thi gian ngn Hnh 2.8: S khi ch hot ngh tr Hnh 2.9 : V du ra PWM ch hot ngh tr 16 2.4 Code #include "p33FJ12MC202.h" #define T 499 _FOSCSEL(FNOSC_PRIPLL&IESO_OFF); _FOSC(FCKSM_CSDCMD&OSCIOFNC_OFF&POSCMD_XT); _FWDT(FWDTEN_OFF); _FPOR(PWMPIN_ON&HPOL_ON&LPOL_ON); int a=0,b=0; int const SinValue[200] = {515, 530, 546, 562, 577, 592, 608, 623, 638, 653,668,683,697,711,725,739,753,766,779,792,805,817,829, 840,852,863,873,883,893,903,912,920,928,936,943,950,957, 963,968,973,978,982,986,989,992,994,996,997,998,998,998, 997,996,994,992,989,986,982,978,974,969,963,957,951,944, 937,929,921,912,903,894,884,874,863,852,841,829,818,805, 793,780,767,754,740,726,712,698,683,669,654,639,624,609, 593,578,562,547,531,515,500,484,468,453,437,422,406,391, 376,361,346,331,316,302,287,273,259,246,232,219,206,194, 182, 170, 158, 147, 136, 125, 115, 105, 96, 87, 78, 70, 62, 55, 48, 41, 35, 30, 25, 20, 16, 12, 9, 6, 4, 2, 1, 0, 0, 0, 1, 2, 4, 6, 9, 12, 15, 19, 24, 29, 35, 41, 47, 54, 61, 69, 77, 86, 95, 104, 114, 124, 134, 145, 156, 168, 180, 1 92, 205, 217, 230, 244, 257, 271, 285, 299, 314, 329, 343, 358, 373, 389, 404, 419, 435, 450, 466, 482, 497}; int main(void) {// Configure PLL prescaler, PLL postscaler, PLL divisor PLLFBD = 38; //M=40 CLKDIVbits.PLLPOST=0; //N1=2 CLKDIVbits.PLLPRE=0; //N2=2 //FOSC = FIN*(M/(N1*N2)) = 80MHz FCY = FOSC/2 = 40MHz // Initiate Clock Switch to FRC oscillator with PLL (NOSC=0b001) // Wait for Clock switch to occur while (OSCCONbits.COSC != 0b011); while (_LOCK !=1);//cho PLL bat dau khoa pha TRISB=0X0000; LATB=0X0000; //Continuous up/down cout mode P1TCONbits.PTMOD = 0b10; //PWM time base input clock period is 4 TCY(1:4 prescale) P1TCONbits.PTCKPS = 0b01; //PWM Time Base Output Postscale 1:1 P1TCONbits.PTOPS = 0b0000; //F1TPER = Fcy/(Fpwm * P1TMRPrescaler * 2) - 1 //499 = 40M/(Fpwm * 4 * 2) - 1 17 //Fpwm = 10khz P1TPER = T; //Complementary PWM Output Mode PWM1CON1bits.PMOD1=0; PWM1CON1bits.PMOD2=0; //Enable for PWM output PWM1CON1bits.PEN2H=1;PWM1CON1bits.PEN1H=1; PWM1CON1bits.PEN2L=1;PWM1CON1bits.PEN1L=1; // Immediate update of PWM enabled PWM1CON2bits.IUE=0; //Update from duty cycle and period buffer registers are enabled PWM2CON2bits.UDIS=0; //Dead Time Unit A Prescale 1:1 P1DTCON1bits.DTAPS=0b00; //Deadtime = 1us P1DTCON1bits.DTA = 40; P1DTCON2bits.DTS2A=0;P1DTCON2bits.DTS1A=0; P1DTCON2bits.DTS1I=1;P1DTCON2bits.DTS2I=1; P1OVDCONbits.POVD2H=1;P1OVDCONbits.POVD1H=1; P1OVDCONbits.POVD2L=1;P1OVDCONbits.POVD1L=1; // Initialize duty cycle values for PWM1 and PWM2 signals P1DC1=0; P1DC2=0; // Clear PWM Interrupt Flag _PWM1IF=0; //Enable the PWM1 interrupt _PWM1IE=1; //Enabling PWM Pulse Generation P1TCONbits.PTEN=1; while(1); } void __attribute__((interrupt,auto_psv)) _MPWM1Interrupt(void) {// Clear PWM Interrupt Flag _PWM1IF=0;a++; if(a==200){a=0;}P1DC1= (SinValue[a])*0.95;b=a+100;if(b>199) {b=(b-200);} P1DC2 = (SinValue[b])*0.95; } 18 CHNG III: MCH LI 3.1 S mch li Nhchngtabit,viccpngunchomchkchkhatngdi(low-side)nhbnhthngvim0VcanguntrngviccScaMOSFET.Tuy nhin, vn kh khn hn khi cp ngun mch kch kha tng trn (high-side): in p ccgate phi cao in p ngun t 10 n 15V. V tng trn, in p ny phi cao hn in p vo +VDC (high voltage rail), l in p cao nht trong h thng. in p cc gate phi iu khin c t khi logic, v thng c so snh vit.Vvy,tnhiuiukhinphithayitheoccS,inpny khng c nh m bin i lin tc t +VDC n VDC. Cng sut tiu th ca bi mch li khng c nh hng r rt n hiu sut ca ton b h thng. Hnh 3.1: Kha MOSFET tng trn Gii quyt vn ny c 2 cch.Mt l to ngun ring (cch ly) chomch kch tng trn; hai l s dng k thut bootstrap.Talachnphngn2sdngICIR2110caInternationalRectifier,l mttrongnhngDriverdngchotmcngsuttrungbnhvinhiuchcnng:Hot ng vi in p ln ti 500V C kh nng chu in p ngc in p li cc gate t 10 n 20V Kha thp p cho c hai knh. Tngthchvimclogic3.3V. Ngunpcungcpringt3.3V n 20V Hot ng ti tn s hng trm kHz CMOSSchmitt-triggeredinputs with pull-down Cyclebycycleedge-triggered shutdown logic To tr ng thi cho c hai knh u ra cng pha vi u vo 19 Hnh 3.2: IR2110 3.2 Nguyn l bootstrap Hnh 3.3: S mchnguyn lbootstrap in p cc G cho MOSFET tng trn c cung cp bi t bootstrap. T ny c np bi ngun cp 12V qua diode bootstrap trong thi gian m thit b khng hot ng (gi s rng in p VS h xung t trong thi gian , nh trong phn ln cc thit b). Bi t c np t ngun in p thp nn in nng tiu th li cc gate l nh. Nh vy tn hiu u vo cho knh tng trn c th c thay i theo mc cng COM cho n bt k kh nng no (c th cao n 1200V). Ta chn t bootstrap 47uF v diode xung 1N4148. S lp mch: Hnh 3.4: S lpmchIR2110 20 CHNG IV: MCH NG LC Trong mch nghch lu s dng nguyn l PWM, tn s chuyn mch cao gp nhiu ln tn s c bn. Chnh v vy ta phichn cc linh kin bn dn lmkha chuyn mch c tc chuyn mch kh ln. Cc loi linh kin bn dn c th p ng c yu cu tn s ny l: BJT - Bipolar Junction Transistor MOSFET - Metal Oxide Semicoducter Field Effect TransistorIGBT l s kt hp ca BJT v MOSFET Hnh 4.1: BJT, MOSFET v IGBT tin hnh la chn cvan bn dn thch hp, ta tin hnh phn tch u nhc im cc van bn dn trn.Nhng vn c bn v BJT:C th ni rng BJT l mt phn t ng ct c in nht v c s dng u tin cho mc ch ng ct sau nhim v khuych i.Di cng sut ca BJT: Ngy nay cc BJT c th c cng sut kh ln, cc van BJT c th c in p chu ng hng chc kV v c dng cho php c vi kA. Tn s chuyn mch ca BJT chophpkh ln, tn s cho phpvokhong 10kHz. Tn s ny cnggim khicngsutvantng.tuyntnhxunginpracaBJTkhln,nguyn nhn chnh do t k sinh trn van nh nn cho php van chuyn mch nhanh.NhcimchyucaBJTlcngsutmchiukhin.CcBJTcng sut ln thng c h s khuych i nh, c trn di 10 ln. iu ny ng ngha vi cng sutmch iukhin bng1/10 cng sutmch ng lc nu ta s dng khuych i trc tip. Cng sut mch iu khin c th gim c nu ta s dng mch Dalington cho tng khuych i cui cng, tuy vy s gy ra mt vn l tr iu khin khi chuyn mch tn s ln.Tn hao v lm mt BJT Nhphntch,tnhaotrongBJTkhlndonciukhinbng dng-p. Do tn hao kh ln nn cc mch dng BJT thng c cng sut nh, c vitrmot.Vicsdngtnscaohncthlmcxongkhngkinht trong iu khin v lm mt van. 21 Nhng vn c bn v MOSFETDi cng sut ca MOSFET CngnghMOSFETraicitincnhngnhcimtrongiu khinBJT.iukhinngmMOSFETliukhinbnginptlnhai cc, cc cng (G - Gate) v cc ngun (S -Source). Vic iu khin bng in p lm gim c kch thc vt n hao trong mch iu khin v dn ti kh nng tch hp thnh vi mch.Do s dng hiu ng trng nn MOSFET cho php tn s chuyn mch kh ln, c th n 100kHz. tuyn tnh ca in p cao do t k sinh trn van nh.Tuy vy cng sut ca MOSFET khng cao, kh nng lm vic in p cao khngbngcBJT.CcMOSFETcngsutlnthngcinplmvic di 1kV v dng in c vi chc Ampe.Tn hao v lm mt MOSFET MOSFET l van bn dn c tn hao nh nht trong tt c cc van bn dn c th s dng ch ng ct. Do s dng chuyn mch bng hiu ng trng nn qutrnhchuynmchgyratnhaonh.ilinvilviclmmtcho MOSFET tng i n gin, c th s dng hiu sut dng cao m vn c th m bo iu kin lm mt. Do vy khi di cng sut c vi trm oat th ta nn s dng MOSFET lm phn t ng ct. Nhng vn c bn v IGBTDi cng sut ca IGBT Di cng sut caIGBT c th ni l ln nht trong ccvan s dng nguyn l chuyn mch bng dng xung iu khin. Do khng b hn ch v iu khin nn c th ch to IGBT vi cng sut kh ln vi gi thnh khng qu cao. Ngy nay IGBT c th ch to inin p c 6kVvdng in c 3kA, trongkhi yu cu inpmchiukhinchkhong20Vvkhngcndngiukhindoiu khinIGBTlbnginpnhMOSFET.TnschuynmchcaIGBTcng kh ln, thng thng cc IGBT cng sut c tn s lm vic khong 20kHz.Tn hao v lm mt cho IGBT TrongqutrnhvnhnhIGBTctnhaothphnBJTsonglicaohn MOSFET.DovyqutrnhlmmtcaIGBTphicbitcchkhidi cng sut tng cao. 22 Cc yu cu chnh t ra cho linh kin s dng trong bi :in p VDS (Mosfet) hay VCE ( IGBT) > VDC = 300V Chu c tn s ng ngt cao (10kHz) Dng in qua linh kin > dng nh mc ca ti3.3A iu kin hot ng. Tn hao nh, lm mt n gin. IRFP460 c la chn : tha mn cc yu t trn, c th mua d dng. Hnh 4.2: IRFP460 23 CHNG V: B LC U RA 5.1.Tng qut v cc b lc Yu cu chung khi tnh ton cc b lc cn tha mn cc yu cu sau: H smo nh, ty theo tim h smo c th yu cukhc nhau, thng THD phi di 20%. H s sng hi thp di 5% th in p ra c coi l tt (HFLOH). Cng sut t thp nht c th. Tn tht cng sut ca b lc thp nht. c tnh tn s dc. Ti cng sut nn khng th s dng cc phng php lc tn s dng khuch i thut ton OA. Vi dng ti ln in p cao b lc phi c thc hin bng cc phntthngLvC,iunydnntnthtcngsutlkhngthtrnh khilmgimhiu suththng,mtkhclmtngngkkchthcthitb. Hn na hiu qu lc ca b lc th ng khng cao B lc th ng ch c th l cc phn t u ni tip hoc song song vi ti: Phnt mc nitip vitihnhthnhmtbchia ptheo tltngquan tng tr gia chng, tng tr no ln th in p t ln n cng ln, bi vy: oVi tn s sng hi c bnmongmun th ZntZti,vttnhtlZss = (cng hng tn s c bn), lc ton b dng sng hi c bn c a ra ti. oVi tn s sng hi bc cao th Zss S vng dy: N = _ IAL = _1.uSm14Sn= 8S :ng Chn mt dng J = 500A/cm2 A = IL[= S, SSSuu= 6, 66. 1u-3cm2 => Chn loi dy AWG19 c tit din 6, 531 cm2, ng knh 0,0948 cm. Hnh 5.5: Cun cmlc 26 MCH IU KHIN MCH LI B LC U RAMCH NG LCIN P MT CHIU IN P XOAY CHIU CHNG VI: S 6.1 S khi: Hnh 6.1: S khi 6.2 S mch to ngun Hnh 6.2: Mch tongun 6.3 S khi iu khin Hnh 6.3: Mch iukhin 27 6.4.S mch li mosfet Hnh 6.4: Mch limosfet 6.5 S mch ng lc Hnh 6.5: Mch ng lc 28 CHNG VII: KT QU 7.1 Mch m phng s dng Proteus : Hnh 7.1: S mphng trongproteus Kt qu m phng: Hnh 7.2: Ktqumphng trongproteus 29 7.2 Tn hiu iu khin o c Hnh 7.3: Tnhiuiukhin 30 7.3Mch tht Hnh 7.4: Mch tht 31 Ti liu tham kho [1] Phm Quc Hi. Hng dn thit k in t cng sut. Nh xut bn khoa hc v k thut. H Ni. 2009 [2]ColonelWm.T.McLyman.TransformerandInductorDesignHandbook. Marcel Dekker, Inc. 2004 [3]dsPIC33FJ12MC201/202DataSheetHigh-Performance,16-bitDigitalSignal Controllers. Microchip Techology Inc. 2008 [4] MPLAB C30 _ C Compiler Users Guide. Microchip Techology Inc. 2007 [5] dsPIC33F Family Reference Manual. Microchip Techology Inc. 2006 [6]ApplicationNoteAN-978HVFloatingMOS-GateDriverIcs.International Rectifier. 2007 [7]DataSheetNo.PD60147rev.UIR2110(-1-2)(S)PbF/IR2113(-1-2)(S)PbF. International Rectifier. 2005 Website tham kho: 1. http://www.dientuvietnam.net/forums/forum.php 2. http://www.picvietnam.com/forum/ 3. http://www.microchip.com/ 4. http://www.irf.com/indexsw.html