DC-DC converters

1. Konverter DC-DC
Pekik Argo Dahono

2. Penerapan
► Catudaya switching
► Pengendalian motor dc
► Regulator tegangan dc

3. Regulator Tegangan
R1
Rv
Io
Vi Io
Vi
Ro Vo R2
Ro Vo

4. Regulator tegangan
Ts
Vi
Ii Vo TON
Io
0
Vi Vo Load Io
0
Ii
0

5. DC Power Supplies
Io
220 V/ 50 Hz Vo
Linear Regulator
Io
•
220 V/ 50 Hz Load Vo
•
Switching Regulator

6. Jenis Konverter DC-DC
► Step-down (Buck)
► Step-up (Boost)
► Up-Down (Buck-Boost)
► Cuk

7. Klasifikasi
1) Berdasarkan jumlah fasa
► Satu-fasa
► Multifasa
2) Jumlah kuadran
► Satu kuadran
► Dua kuadran
► Empat kuadran

8. Step-Down (Buck) Converter
iL id io
id io
S S
R L
Ed vD ic vo Ed D vD M
D C
id iL
S R L
Ed vD vo
D

9. Step-Down Converter
(Continuous Conduction Mode)
diL
id iL v D = RiL + L + vo
R dt
S L 0 ≤ t < TON :
Ed vD vo
D
v D = Ed
ON state diL
Ed = RiL + L + vo
dt
iL
id R TON ≤ t < Ts :
S L
vo
vD = 0
Ed D vD
diL
0 = RiL + L + vo
OFF State dt

10. Step-Down Converter
(Continuous Conduction Mode)
Ed Tegangan rata - rata :
T
vD vD = ON Ed
Ts TON T
vD = E d = ON E d = dE d
0 TON + TOFF Ts
TON
Analisis Riak :
Ts ~
i L = i L + iL
E d − vo v =v +v ~
D D D
vL
v o = Vo
−vo
Thus,
v D = Ri L + Vo
~
iL ~ = R ~ + L d iL
vD iL
dt
~
Jika nilai R io dianggap kecil maka :
iL = ∫ v D dt = ∫ (v D − v D )dt
id ~ 1 ~ 1
L L

11. Step-Down Converter
(Continuous Conduction Mode)
~ Ed − vD vD
iL , pp = TON = TOFF
L L
E d − dE d
= dTs
L
Ed
= (1 − d )d
Lf s
f s = 1 / Ts adalah frekuensi switching
d = TON / Ts adalah duty factor.

12. Critically Conduction Mode
Ed
T
vD vD = ON Ed
Ts
~
⎞ (1 − d )d
0
TON iLpp⎛ Ed
iL = =⎜
⎜ Lf ⎟
⎟
2 ⎝ s ⎠ 2
Ts
E d − vo
vL
−v o
~
iLpp
iL
0

13. Discontinuous Conduction Mode
id iL Ed
R
vD vo
S L
Ed vD vo
D 0
TON α1Ts α 2Ts
ON state Ts
id iL
R
S L E d − vo
Ed vD vo
D vL
− vo
OFF state
id iL
R iL
0
S L
Ed vD vo
D
OFF state

14. Step-Up (Boost) Converter
id L D iD io
vL
vD ic
Ed vS S C vo

15. Step-Up Converter
(Continuous Conduction Mode)
id io
Persamaan umum :
L
ic E d = v L − v D + vo
Ed S C vo
0 ≤ t < TON ⇒ v D = vo v L = Ed
0 ≤ t < TON
TON ≤ t < Ts ⇒ v D = 0 v L = E d − vo
id io Nilai rata - rata tegangan di induktor v L = 0,
TON
L
ic vD = vo
Ed C vo Ts
jadi,
E d = −v D + vo = (1 − d )vo
TON ≤ t < Ts
Ed
vo =
1− d

16. Step-Up Converter
(Continuous Conduction Mode)
vo Persamaan riak arus :
T
vD vD = ON vo did
Ts L = Ed − vS
0 dt
TON
0 ≤ t < TON ⇒ v S = 0
Ts
TON ≤ t < Ts ⇒ v s = vo
T
Ed
v S = OFF vo
vL Ts
E d − vo
id = ∫ (E d − vo )dt
~ 1
L
~ − ( E d − vo ) E
id id , pp = TOFF = d TON
L L
Ed
= d
Lf s
iD

17. Critically Conduction Mode
vo
TON
vD = vo
vD Ts
0
TON
Ts
Ed
Ed id , crit = d
vL 2 Lf s
E d − vo
~
idpp
id

18. Discontinuous Conduction Mode
id io
vo
L
Ed ic vo vD
S C
0
TON
ON state
Ts
id io
L Ed
Ed ic vo
C
vL
E d − vo
OFF state
id io
~
idpp
L id
Ed ic vo
C
OFF state

19. Buck-Boost Converter
id S D iD io
vS iL ic
vD vo
Ed
vL C
L

20. Buck-Boost Converter
id S D iD io 0 ≤ t < TON
vS iL
vD ic vo
Ed = v L
Ed
vL
L C
TON ≤ t < Ts
0 ≤ t < TON v L = −v o
Bevause v L = 0, then
id S D iD io
E d TON = voTOFF
vS iL vD ic Thus,
Ed vo
vL C
L
TON
vo = Ed
TON ≤ t < Ts TOFF

21. Buck-Boost Converter
Continuous Conduction Mode
E d + vo
TON
d
vS
vo = E d
0
1− d
Ts
Ed
Ed
vL i Lpp = α
Lf s
− vo
E d + vo
vD
0
iL
0

22. Cuk Converter
id L1 C
vL1
Ed vS S vC D L2 io Cd
vo
vL 2

23. Cuk Converter
id L1 C
Persamaan tegangan :
vL1
Ed v
vS S C D vo E d = v L1 + vC − vo − v L 2
L2 io Cd
v L1 = v L 2 = 0
vL 2
vC = E d + v o
0 ≤ t < TON 0 ≤ t < TON ⇒ v L1 = E d
TON ≤ t < Ts ⇒ v L1 = E d − vC
id L1 Thus,
C
E d TON = (vc − E d )TOFF = voTOFF
vL1
v vo TON
Ed vS S C D L2 io Cd vo = Ed
TOFF
vL 2
TON ≤ t < Ts

24. Multiphase Choppers
i1
S1 i1
S1 i2
i2 io
S2 io
i3
S2
Ed D1 D2 C ic vo S3
Ed C ic vo

25. Two-Phase Chopper
vD1
i1
vD 2
i2
io

26. 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 high-current
applications.
► The flywheel diodes are usually implemented by
using synchronous rectifiers.

27. Multi-quadrant Chopper
S1 D1
io
Ed S2 D2 vo
S1 D1 D3 S3
Ed S2 D2 S4
D4

28. Two-Quadrant Chopper
S1 D1 vo
io +
vo
Ed eo
−
vo
S2 vo eo
D2
S1 / D1 S 2 / D 2
+
io
R L io
vo eo −
io

29. Four-Quadrant Chopper
S1 D1 D3 v* 2
D
io S3
v* 4
D
Ed
vo S4
S2 D2 D4 vD 2
vD 4
io
R L io
eo vo
vD 2 vD 4

30. Indirect DC-DC Converters
► Flyback converter
► Forward converter
► Pushpull converter
► Half-Bridge converter
► Full-bridge converter

31. 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.

32. Flyback converter
► Simple
► Minimum component count
► Higher stresses across switching devices
► Unipolar flux in the transformer
► Higher ripple
► Suitable for low-power applications (<150
W)

33. Flyback converter
•
N1 N2 C vo Load
Ed •
S
D
•
N1 N2 C vo Load 0 ≤ t < TON
Ed •
D
S •
N1 N2 C vo Load
Ed •
S
TON ≤ t < Ts

34. Flyback Converter
Persamaan umum :
E d = v Lm + v S
v Lm tegangan sisi primer trafo.
0 ≤ t < TON
E d = v Lm
vS = 0
TON ≤ t < Ts
N
v Lm = − 1 vo
N2
N1
vS = Ed + vo
N2
Nilai rata - rata tegangan di trafo harus sama dengan nol, jadi
N1
E d TON = voTOFF
N2
N2 T
vo = E d ON
N1 TOFF

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

36. Forward Converter
D1 L D3
D1 L
• •
• •
N1 N2 D2 C vo Load
N1 N2 D2 C vo Load
Ed
Ed
•
S S

37. Forward Converter
D3 D3
D1 L
D1 L
• •
• •
N1 N2 D2 C vo Load
N1 N2 D2 C vo Load
Ed
• Ed
•
S
S
0 ≤ t < TON TON ≤ t < Ts

38. Forward Converter
Persamaan tegangan :
v D 2 = v L + vo
v L = v D 2 − vo
0 ≤ t < TON
N2
v D 2 = v sek = Ed
N1
TON ≤ t < Ts
vD2 = 0
Jadi,
N2 TON
vo = Ed
N1 Ts

39. Push-Pull and Half-Bridge Converters
D1
D3 L
S1 L
Ed D1 D3
S1 • •
C vo Load
C vo Load
Ed • • Ed S2 D2
S2
D4
D4
D2

40. Push-Pull and Half-Bridge Converters
► Bipolar flux
► Moderate stress across switching devices
► Suitable for medium power (< 1 kW)
► Sensitive to signal unbalances

41. Full-Bridge Converter
S1 S3 L
D1 D3 D3
Ed u v
C vo Load
S2 D2 S4 D4
D4
vuv S1 S2 S3 S4
Ed ON OFF OFF ON
- Ed OFF ON ON OFF
0 OFF ON OFF ON
0 ON OFF ON OFF

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

43. Soft-Switching Mode
vuv
iu
iu
S 2 & S3
S1 & S 4

44. Duality
I in S1
I out
S1
Vin Vout I out I in Vin S2 Vout
S2
Vout I Vout I in
= d = in =d =
Vin I out Vin I out

45. Duality
I in C
S1 S2
Vin Vout I in
L S1 S2 I out
I out