Konverter-dc-dckuliah-ke-7.docx

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Konverter DC-DC Pekik Argo Dahono

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Penerapan • Catu daya switching • Pengendalian motor dc • Regulator tegangan dc

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Regulator Tegangan

Rv

R1 Io

Io

Vi

Vi

Ro

Vo

R2

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Ro Vo

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Regulator tegangan Ts Vi

Ii

TON

Vo

Io

0

Vi

Vo

Load

Io

0

Ii 0

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Jenis Konverter DC-DC Direct converters: • Step-down (Buck) • Step-up (Boost) • Up-Down (Buck-Boost) • Cuk

Indirect converters: • Flyback • Forward • Center-tap • Half-bridge • Full bridge LPKEE-ITB

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Klasifikasi Konverter DC-DC 1) Berdasarkan jumlah fasa •

Satu-fasa

•

Multifasa

2) Jumlah kuadran •

Satu kuadran

•

Dua kuadran

•

Empat kuadran LPKEE-ITB

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Step-Down (Buck) Converter

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Step-Down Converter (Continuous Conduction Mode) vD = RiL + L

diL +vo dt

0 ≤t
Ed = RiL + L

diL +vo dt

TON ≤t
OFF State LPKEE-ITB

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Critically Conduction Mode Ed

T v D = ON Ed Ts

vD 0 TON

iL =

Ts

~ iLpp 2

=

Ed Lf s

(1 − d )d 2

Ed − v o vL

−vo

iL

~ iLpp 0

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Discontinuous Conduction Mode

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Output voltage characteristic

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Step-Up (Boost) Converter

Vo > Ed 14 LPKEE-ITB

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Step-Up Converter (Continuous Conduction Mode) Persamaan umum : Ed = vL −vD +Vo 0 ≤ t
ON state

TON ≤ t
vD =Vo ⇒

vL = Ed

vD = 0 vL = Ed −Vo

Nilai rata - rata tegangan di induktor vL = 0, T vD = ON Vo Ts jadi, Ed = −vD +Vo = (1 − d )Vo

OFF state

Vo =

Ed 1 −d

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Step-Up Converter (Continuous Conduction Mode) Persamaan riak arus : diL = Ed − v S dt 0 ≤ t
~ 1 iL = ∫(Ed −Vo )dt L (E V ) E ~ iL, pp = − d − o TOFF = d TON L L =

Ed d Lf s 16

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Critically Conduction Mode

iL , crit =

Ed d 2 Lf s

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Discontinuous Conduction Mode ON state

OFF state

OFF state

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Output characteristic

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Parasitic effect

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Buck-Boost Converter id S Ed

D iD

iL

vS vL

io

ic

vD

L LPKEE-ITB

C

vo

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Buck-Boost Converter Continuous Conduction Mode vo = E d iLpp =

d 1 −d

Ed d Lf s

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Cuk Converter

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Two-Phase Chopper vD1 i1 vD2 i2

io

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Multiphase Chopper • The effective switching frequency is the number of phase times the carrier frequency. • At several values of duty cycle, the ripple is zero. • The topology is useful for low-voltage highcurrent applications. • The flywheel diodes are usually implemented by using synchronous rectifiers.

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VRM for Microprocessors

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Experimental Result

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Multi-quadrant Chopper

Ed

Ed

S1

D1

S2

D2

io vo

S1

D1

D3

S3

S2

D2

D4

S4

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Indirect DC-DC Converters • Flyback converter • Forward converter • Pushpull converter • Half-Bridge converter • Full-bridge converter

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The needs of galvanic isolation • Safety and noise requirements dictate the

use of galvanic isolation. • Galvanic isolation is implemented by using a

transformer. • The frequency of operation must be very

high to reduce the size of transformer.

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Flyback converter • Simple • Minimum component count • Higher stresses across switching devices • Unipolar flux in the transformer • Higher ripple • Suitable for low-power applications (<150 19

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W) 36

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Flyback Converter Persamaan umum : Ed = vLm + vS vLm tegangan sisi primer trafo. 0 ≤ t < TON Ed = vLm vS = 0

TON ≤ t
N1 vo N2

Nilai rata - rata tegangan di trafo harus sama dengan nol, jadi N Ed TON = 1 voTOFF N2 T N vo = 2 Ed ON N1 TOFF LPKEE-ITB

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Forward Converter • Simple • Less ripple than flyback converter • Less stresses across switching devices • Unipolar flux • Suitable for medium power (< 500 W)

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Forward Converter Persamaan tegangan : vD 2 = vL + vo vL = vD 2 − vo 0 ≤ t
: vD 2 = vsek =

N2 Ed N1

TON ≤ t
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Push-Pull and Half-Bridge Converters • Bipolar flux • Moderate stress across switching devices • Suitable for medium power (< 1 kW) • Sensitive to signal unbalances

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Full-Bridge Converter

vuv Ed

-Ed 0 0

S1 ON OFF OFF ON

S2 OFF ON ON OFF

S3 OFF ON OFF ON

S4 ON OFF ON OFF

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Full-Bridge Converter • Bipolar flux • Minimum stresses across switching devices • Suitable for large power (< 10 kW) • Can be operated under soft-switched mode

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Duality S1

Iin

I out S1 Vin

S2

Vout

I out

I in

Vout Iin =d = Vin I out

Vin

S2

Vout

Vout 1 I in = = Vin d I out

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Duality

Iin

C S1

Vin

S2 L

Vout

Iin

S1

S2

I out

Iout

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Future Trends

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Future Trends

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Future Trends

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End

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