a low output ripple dc to dc converter topology using voltage overlapping technique the power...
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A Low Output Ripple DC to DC converter A Low Output Ripple DC to DC converter topology using voltage overlapping topology using voltage overlapping techniquetechnique
The Power Electronics Lab., Hong Kong The Power Electronics Lab., Hong Kong UniversityUniversity
C. P. LiuC. P. Liu N. K. Poon N. K. Poon M. H. PongM. H. Pong
Speaker Speaker
C.P.LiuC.P.Liu
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Low output ripple solutions – InterleavingLow output ripple solutions – Interleaving
Input voltage = 36VDuty cycle = 0.5Ripple current p-p = 0A !!
0 5 10 7 1 10 6 1.5 10 6 2 10 6 2.5 10 6 3 10 6 3.5 10 6 4 10 6 4.5 10 6 5 10 6 5.5 10 6 6 10 6 6.5 10 6 7 10 6 7.5 10 65
0
5
10
15
2017.917
2.917
I1 t 36( )
I2 t 36( )
I1 t 36( ) I2 t 36( )
7.5 1060 t
f1x
f1x
IppL=300nH
L=300nH
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Low output ripple solutions – Low output ripple solutions – InterleavingInterleaving
Input voltage = 72VDuty cycle = 0.25Ripple current p-p = 20.833A ??
0 5 10 7 1 10 61.5 10 6 2 10 6
2.5 10 6 3 10 63.5 10 6 4 10 6 4.5 10 6 5 10 6 5.5 10 6
6 10 6 6.5 10 67 10 6 7.5 10 6
10
0
10
20
3025.417
8.125
I1 t 72( )
I2 t 72( )
I1 t 72( ) I2 t 72( )
7.5 1060 t
f1x
f1x
L=300nH Ipp
L=300nH
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Low output ripple solutions – Low output ripple solutions – InterleavingInterleaving
f1x
f1x
L
L
Ipp Ripple current vs. Input voltage
35 40 45 50 55 60 65 70 750
10
20
30
Iripple Vi
Vi
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Low output ripple solutions – Single phaseLow output ripple solutions – Single phase
f2x
L = 266nH
Ipp
Even better than Multi-phase
35 40 45 50 55 60 65 70 750
10
20
3020.833
0
I ripple V i I ripple_single_phase V i
7236 V i
Question: Why 266nH and freq = 2 x f ?
Interleave converter
Single phase converter
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2(1+1+1+1)=8 (1+2+1+2)=6
One inductor reduces resistanceOne inductor reduces resistance
1
1
Ae Ae 1
2
Ae Ae
For same copper loss:
N = 4/3N = 1
For same flux density:
L = 300nH L = (16/9 x 300/2) nH
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Ultimate interleaving – Ultimate interleaving – 50%+50%50%+50%
= 12
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What if more than 50% ?What if more than 50% ?
Vp
Vp
Vp
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Vp
Vp
Vp
No regulation - stupid!No regulation - stupid!
Vp
Vp
Vp
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Vp(1-D)
VpD
Vp(1-D)
VpD
Simplest Amplitude ModulatorSimplest Amplitude Modulator
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World’s first wide range & wide World’s first wide range & wide loading output capacitorless DCDC loading output capacitorless DCDC regulator.regulator.
Va
Vb
Vo
Vo
Va
Vb
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More components than a already good interleaving converter ! !
World’s first wide stupid DCDC World’s first wide stupid DCDC regulator.regulator.
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Isolated Overlap VS Isolated Isolated Overlap VS Isolated InterleaveInterleave
Compare with the more complicated approach
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Vo
Va
Vb
No perfect DC blocking capacitorNo perfect DC blocking capacitor
Ripple voltage
introduced
Va
Vb
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Vo
ICo
Of course an O/P capacitor is neededOf course an O/P capacitor is needed
Resonate current pulse
Va
Vb
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Final configuration –Final configuration – add a current add a current sourcesource
Ls << LoLoLs1
Ls2
ILs2
Va
Vb
ILs1
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Overlapping + Sync-RectOverlapping + Sync-Rect
ILs2
Va
Vb
ILs1
Ls1
Ls2
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Overlapping + Active DiodeOverlapping + Active Diode
300 nH50 nH
100 uF
50 nH
0.33 uF
0.33 uF
36V-72V
O/P Inductor current
O/P diodes current
Gate drive
Gate drive
2.5V@15A
Efficiency = 88%
O/P ripple = 50mV
fs = 200kHz
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Overlapping or Interleaving Overlapping or Interleaving
300 nH
300 nH
2A p-p 20.8A p-p
300 nHSame O/P Inductor
Same 72V I/P voltage
Same D=0.5 at 36V I/P
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After all . . . After all . . .
•Good reasons to look for more low output ripple configurations
•A simple configuration producing very low output ripple current is proposed
•ZVS of primary switches is possible
•Output ripple is independent on input voltage
•Low stress on MOSFET
•Good for low voltage high current applications
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Potential application Intermediate bus
in 48V system 2.8 x 4.5 inches2
500W output
14V, 36A with tight regulation
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Thank you
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