Bai Tap Dtcs

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BI TP IN T CNG SUTPHN BI TP GII CA PHN BO COBi 1: BI TP NHM 11. Cho diode cng sut hot ng giao hon vi in th Vs=120V v ti RL=6. Gi s diode l l tng, khi diode dn c in th thun VF=0V, v khi diode ngng dn c dng in r bng 0. Thi gian giao hon tsw(on)=tsw(off)=1,5. Tnh cng sut giao hon ti tn s giao hon 1kHz.2.

Cho mch diode giao hon khng l tng hot ng theo cc iu kin sau: Khi diode dn VF=2V dng in If=10A, b qua dng in r khi ngng. Tn s giao hon 9,23 kHz, ngun cung cung cp 120V. H s nh dng 50%, thi gian giao hon tsw(on)=2, tsw(off)=4. Tnh cng sut giao hon.Bi 2: BI TP NHM 2Cho mch chnh lu mt pha ton k ti R=100 ngun cung cp 220Vac, gc kch =60o. Hy:1. V s nguyn l v dng sng vo ra.2. Tnh gi tr trung bnh ca dng, p v cng sut trn ti.3. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti.4. Tnh gi tr dng trung bnh, dng cc i v p ngc cc i cho 1 SCR.5. Tnh gi tr trung bnh ca dng, p v cng sut trn ti khi =0o.6. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti khi =0o.7. Khi ti ni tip thm cun dy L c gi tr rt ln, v dng sng ra v tnh VAV v IAV trn ti.8. Khi ti nh cu 7 mch c mc thm diode dp, hy v sng ra v tnh dng trung bnh v dng cc i qua diode dp.9. Khi SCR bn k dng l diode hy v sng ra v tnh VAV trn ti.10. Khi SCR bn k dng l b t hy v sng ra v tnh VAV trn ti.11. Nhn xt th no nu ti l ng c DC (R-L-E) khi mch b h hng nh cu 9.12. Nhn xt th no nu ti l ng c DC (R-L-E) khi mch b h hng nh cu 10.13. Tm gc kch khi cng sut ti l 90W.Bi 3: BI TP NHM 3Cho mch chnh lu ba pha cu i xng ti R=10 ngun cung cp gia hai dy pha l 360Vac, gc kch =85o. Hy:1. V s nguyn l v dng sng vo ra.2. Tnh gi tr trung bnh ca dng, p v cng sut trn ti.3. Tnh gi tr dng trung bnh, dng cc i v p ngc cc i cho 1 SCR.4. Tnh gi tr trung bnh ca dng, p v cng sut trn ti khi =0o.5. Khi ti ni tip thm cun dy L c gi tr rt ln, v dng sng ra tnh VAV v IAV trn ti.6. Khi 2 SCR pha B l diode hy v sng ra v tnh VAV trn ti.7. Khi 2 SCR pha B l b t hy v sng ra v tnh VAV trn ti.8. Nhn xt th no nu ti l ng c DC (R-L-E) khi mch b h hng nh cu 6.9. Nhn xt th no nu ti l ng c DC (R-L-E) khi mch b h hng nh cu 7.10. Tm gc kch khi cng sut trung bnh ti l 300W.Bi 4: BI TP NHM 4

Cho b bin i AC i xng mt pha (2 SCR) ti R=100 ngun cung cp 220Vac, gc kch =120o. Hy:1. V s nguyn l v dng sng vo ra.2. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti.3. Tnh gi tr dng trung bnh, dng cc i, p ngc cc i v dng hiu dng cho 1 SCR.4. Khi SCR bn k dng l diode hy v sng ra v tnh VAV, VRMS trn ti.5. Khi SCR bn k dng b t hy v sng ra v tnh VAV, VRMS trn ti.6. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng nh cu 4.7. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng nh cu 5.8. Khi ti ni tip thm cun dy L c gi tr rt ln, v dng sng ra v tnh IRMS trn ti.Bi 5:BI TP NHM 5 Cho b bin i AC i xng ba pha (6 SCR) ti mc sao c R=100 ngun cung cp gia 2 dy l 360Vac. Hy:1. Khi gc kch =45o. V s nguyn l v dng sng vo ra. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti. Tnh gi tr dng trung bnh, dng cc i, p ngc cc i v dng hiu dng cho 1 SCR. Khi SCR bn k dng pha A b t hy v sng ra v tnh VRMS trn ti. Khi SCR bn k dng pha A l diode hy v sng ra v tnh VRMS trn ti. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng t linh kin nh trn.2. Khi gc kch =85o. V s nguyn l v dng sng vo ra. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti. Tnh gi tr dng trung bnh, dng cc i, p ngc cc i v dng hiu dng cho 1 SCR. Khi SCR bn k dng pha B b t hy v sng ra v tnh VRMS trn ti. Khi SCR bn k dng pha B l diode hy v sng ra v tnh VRMS trn ti. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng b t linh kin nh trn.3. Khi gc kch =115o. V s nguyn l v dng sng vo ra. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti. Tnh gi tr dng trung bnh, dng cc i, p ngc cc i v dng hiu dng cho 1 SCR. Khi SCR bn k dng pha C b t hy v sng ra v tnh VRMS trn ti. Khi SCR bn k dng pha C l diode hy v sng ra v tnh VRMS trn ti. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng b t linh kin nh trn.Bi 6:BI TP NHM 6 Cho b bin i AC i xng ba pha (6 SCR) ti mc tam gic c R=100 ngun cung cp gia 2 dy l 360Vac. Hy:4. Khi gc kch =45o. V s nguyn l v dng sng vo ra. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti. Tnh gi tr dng trung bnh, dng cc i, p ngc cc i v dng hiu dng cho 1 SCR. Khi SCR bn k dng pha A b t hy v sng ra v tnh VRMS trn ti. Khi SCR bn k dng pha A l diode hy v sng ra v tnh VRMS trn ti. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng t linh kin nh trn.5. Khi gc kch =85o. V s nguyn l v dng sng vo ra. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti. Tnh gi tr dng trung bnh, dng cc i, p ngc cc i v dng hiu dng cho 1 SCR. Khi SCR bn k dng pha B b t hy v sng ra v tnh VRMS trn ti. Khi SCR bn k dng pha B l diode hy v sng ra v tnh VRMS trn ti. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng b t linh kin nh trn.6. Khi gc kch =115o. V s nguyn l v dng sng vo ra. Tnh gi tr hiu dng ca dng, p, cng sut v h s cng sut trn ti. Tnh gi tr dng trung bnh, dng cc i, p ngc cc i v dng hiu dng cho 1 SCR. Khi SCR bn k dng pha C b t hy v sng ra v tnh VRMS trn ti. Khi SCR bn k dng pha C l diode hy v sng ra v tnh VRMS trn ti. Nhn xt th no nu ti l ng c khng ng b AC (R-L) khi mch b h hng b t linh kin nh trn.Bi 7: BI TP NHM 71.

Xt b n p giao hon (chuyn mch) h th, c tr s ln lt sau: Vidc=50V, D=0,4, L=400, C=100, R=20 v tn s giao hon f=20kHz. Gi s cc linh kin l l tng. Tnh:a. in th ra Vo.b. Tr cc i v cc tiu ca dng in qua cun cm L.c. in th dn sng ng ra.d. Cng sut vo, ra v hiu sut.2. Cho b n p giao hon tng th, vi dng cm lin tc c tr s ln lt sau: Vi=12V, Vo=30V, R=50 v tn s giao hon f=25kHz, dn sng khng qu 1% Gi s cc linh kin l l tng. Cho bit cc tr s phi chn:a. H s nh dng D.b. Tnh tr s Lmin.c. Tr cc i v cc tiu ca dng in qua cun cm L=1,5 mH.d. Tr s in dung C.3.

Xt b n p giao hon gim - tng th, c tr s ln lt sau: Vi=24V, D=0,4; R=5 v tn s giao hon f=20 kHz. L=400, C=400.Cho bit dng trung bnh l 100A. Gi s cc linh kin l l tng. Tnh:a. in th ng ra Vo.b. Tr s dng in cun cm.c. dn sng ng ra.Bi 8: BI TP NHM 8

1.

Xt b n p giao hon phi hi hnh 3.8 c tr s ln lt sau:Vi=24 V, Vo=5 V; R =5 v tn s giao hon f=40 kHz, t s bin th n1/n2=3, cun tch tr Lm=500 , C=200Tnh:a. H s nh dng D.b. Tr cc i v cc tiu ca dng in qua cun tch tr Lm.c. in th dn sng ng ra.

Hnh 3.82.

Xt b n p giao hon thun hnh 3.9 c tr s ln lt sau:Vi= 48V; D=0,4; R =10 v tn s giao hon f=35 kHz, t s bin th n1/n2=1,5, n1/n3=1, cun cm LX=0,4 mH, Lm=5mH, C=100Tnh:a. Tr s in th ng ra Vob. Tnh tr iLx,max, iLx,minc. Tr cc i ca dng in qua cun s bin th. Chng t rng dng qua cun tch tr tr v zero trong sut chu k giao hon.

Hnh 3.93.

Cho b chuyn i y ko hnh 3.10 c cc thng s sau: Vi= 30V; D=0,3; R =6 v tn s giao hon f=10 kHz, t s bin th np/ns=2, cun cm tch tr Lx=0,5mH, C=50Tnh:a. Tr s in th ng ra Vob. Tnh tr iLx,max, iLx,minc. dn sng ng ra.

Hnh 3.10Bi 9: BI TP NHM 91. Cho mch i in ton cu 1- pha (hnh v) vi ti R=2, D= 50% v V1= 200V, to dng sng ng ra hnh nc.

R=2V1200VSW3SW4D4D3SW1SW2D2D1a. Tnh tr in th hai u bc SW khi ngngb. Tnh tr trung bnh dng qua tic. Tnh tr trung bnh dng qua bc SWd. Tnh cng sut trn ti2. Cho mch i in bn cu 1- pha (hnh v) vi ti R=1, D=50% v V1=V2=100 V, to dng sng ng ra hnh nc.

R=1V1100VV2100VSW1SW2D2D1a. Tnh tr in th hai u bc S khi ngng?b. Tnh tr trung bnh dng qua ti?c. Tnh tr trung bnh ca bc sw?d. Tnh cng sut ca ti?Bi 10: 1. Cho mch i in 3-pha ton sng vi in th DC bng V=300 V ti mc sao mi pha gm R=5 ni tip vi L=25 mH, hot ng tn s 100 Hz. Xc nh dng sng dng in.2. Cho b i in 3-pha ton sng, ti mc hnh tam gic, vi V=300 V, R=15, L/R=5 ms, T=10 ms. Xc nh dng sng dng in.

PHN BI TP LM THM NHChng 1: M u3. Diode 1N 3879 hot ng vi dng in ban u l 20A ti nhit mi ni l 100oC. Diode hi phc vi tc dng ngc l 20A/. Tnh thi gian hi phc trong trng hp:a. ts=0. b. ts=tt . Tnh dng in ngc cc i tng ng. Cho bit din tch hi phc Qrr=0,22Cb.4. Cho mch in theo hnh 1.1 c thi gian hi phc trr rt b v bng 50ns.Tnh in th ngc khi xy ra hi phc. Cho E =200V, L=30, dng in ngc IRM=3A, IO =h.s. B qua nh hng ca in dung mi ni.

200VL1V30HEi1i2i3IO=hsSWDvXHnh 1.15. Cho mch theo hnh 1.2 Ngay trc khi SW tt ( t=-0) dng chy qua diode dp D bng I=40 A. Ti t =0, SW khi dn, diode ngng v c dng ngc cc i ti IRM =25A v tc tng dng l 20 A/s. Gi s diode c in th thun khi dn Vf=0, dng r khi ngng Ir= 0, v Ls rt ln.a. V dng sng dng in qua diode khi giao hon v tnh trr.b. Tnh din tch hi phc Qrr.c. Tnh in th ngc cc i qua diode. V dng sng dng in qua SW v tnh tr s nh dng in tc thi qua n.

400VL1V10HEisIidRSWDVDLSHnh 1.26.

Cho mch transistor o giao hon ti tn s 10 kHz c cp in th Vcc=400V v in tr RC=20. Dng in cc thu c thi gian ln tr=0,8 v thi gian xung tf=1,0. Tnh :a. Nng lng tht thot trong thi gian lnb. Nng lng tht thot trong thi gian xungc. Nng lng tht thot tng cng d. Cng sut tht thot tng cng7.

Cho mch in theo hnh 1.5, dng in trong cun cm l 20A v gi khng i trong thi gian giao hon. Mch c E1=200V, E2=400V, khi khi dn thi gian t1=0,4, t2=0,2 v khi khi ngng c t1=0,1 v t2=0,3(hnh 1.6), f=10 kHz . Tnh:a. Nng lng tht thot trong thi gian khi dnb. Nng lng tht thot trong thi gian khi ngngc. Cng sut tht thot tng cng

200VLVRiLibi2400VDQVE2E1iCHnh 1.5

VCEt2t1ICICME2PPmaxVCEt2t1ICICME2PPmaxKhi ngngKhi dnHnh 1.68. Mch h tr cho transistor cng sut hnh 1.7 v dng sng giao hon hnh 1.8. Vi dng qua cun cm iL=20A khi Transistor dn. Khi transistor tt dng in gim tuyn tnh. Thi gian xung tf=2. Tnh tr s Cs gii hn VCE nh hn 100V ti thi im iC bng 5A.

200VLVRiLibi2350VDQVE2E1iCCsisHnh 1.7

ICICMVCEVCE0tfIsICMHnh 1.89.

Cho mch transistor giao hon nh hnh 1.9 c thm vo mch h tr gm t 0,0075, diode v in tr 1000. Gi s khng c s thay i trong thi gian xung ti lc khi ngng. in th tng ln trong khi ngng c iu khin bng t h tr. Tnh: a. Nng lng tht thot lc khi dnb. Nng lng tht thot lc khi ngngc. Nng lng tht thot tng cng ti tn