Transcript Winning by Power Jeffrey Hwang

Winning by Power
Jeffrey Hwang
Design a 100W
PFC Boost Inductor
Alland Chee, Elvis Lin, Joe Wong
and
Jeffrey H. Hwang
Winning by Power
Jeffrey Hwang
Criteria of Selection
Size
Efficiency
Cost
Winning by Power
Jeffrey Hwang
Review Important Magnetic Variables
and
Important Magnetic Constants
ampere  turn
]
weber
• R=S: [
Magnetic
Reluctance=The resistance of a
material to a magnetic field
• Φ: [Weber] Magnetic Flux=A
measure of quantity of
magnetism.
• B: [Tesla]=[ 104 Gauss] Magnetic
Field=Flux Density=Magnetic
Induction
 Turn
• H: [ Ampere
] Magnetic Field
Meter
Strength=Magnetic
Force=MMF per length
•
Ampere  Turn
 0.004   [Oe ]  0.0125[Oe ]
Meter
• 1[Tesla]=1[Weber/Meter2]=104
[Gauss]=1[Newton/(Ampere x
Meter)]
• 1[Weber]=1[Wb]=108Maxwell
• [L]=1[henry]=1[Volt x
Sec/Ampere]=1[Wb/Amp]
• μ0=Air Permeability
Constant=4π x 10-7 [Tesla
Meter/Ampere]
Winning by Power
Jeffrey Hwang
Important Magnetic Formula
• R=mmf /ΦB=NI/ΦB=
ιm/(Ac μ)
• B=μ H= μ x mmf/leff=
ΦB/Ac= μ x N x I/leff=
L x I/(N x Aac)
• Re=Rl + Rair=
ιm/(Ac μ) + ιair/(Ac μair)=
1
Ac
(
 air  m     air
)
 air  
• ΦB= LI N I



B

A

c

2 /R =
• L=N ΦN B/I=N
e
N 2 eff  Ac
m
eff
 N  I  Ac
m
Winning by Power
Jeffrey Hwang
Bmax= Constant @ given material
PC95:Bmax~350mT
PC44:Bmax~300mT
PC40:Bmax~270mT
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NImax= Constant @ lair, air gap is fixed
Jeffrey Hwang
Winning by Power
Jeffrey Hwang
Sundest, MPP, Ferrite…?
Experiment 1st:
Selecting the best Magnetic Material
Winning by Power
Jeffrey Hwang
Selecting Magnetic Materials
88.00
87.00
86.00
85.00
84.00
86.97%
0.427mH
86.01%
85.88%
85.81% 85.92%
85.89%
85.91%
85.62%
85.55% 85.53%
1.112mH85.58% 85.32%
0.333mH 0.288mH
1.08mH85.35% 85.60%
0.62mH
85.12%0.4645mH
84.97%
0.988mH
0.4295mH
1.2182mH
0.533mH
1.8382mH
84.86%
0.637mH
0.861mH84.62%0.4645mH
84.55%
1.274mH
0.625mH
83.85%
3.08mH
0.4645mH
83.67% 83.72%
1.2117mH
0.888mH1.31mH
30
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83.00
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Efficiency (%)
Taiwan AC Adaptor Measurement with different Inductor Materials
Inductor Materials
Ferrite and MPP have the higher efficiency performance.
Ferrite is our selection.
Eff. (%)
Winning by Power
Jeffrey Hwang
Ferrite is our selection for Po=100W
Ferrite is Cost Effective
and
Ferrite Core Loss (AC Loss) is much less
DCR seems dominates the efficiency with Ferrite Core!
Let us prove it here!
Winning by Power
Jeffrey Hwang
290uH or 1mH?
Experiment 2nd:
DCR and switching frequency is fixed
Winding Factor is not optimal.
Winning by Power
Jeffrey Hwang
With fixed DCR=0.46 ohm and fixed fsw=67.5Khz,
Po=100 W and Vo=19V AC Adapter
Eff. (%) vs L (mH)
Constant Indcutor Resistance (DCR=0.46 ohm), fSW =67.5kHz
PC95, RM8, lg=30mils
Efficiency (%)
86.50
86.01%
86.00
85.58%
85.32%
85.50
Eff. (%)
85.00
84.62%
84.50
0
0.2
0.4
0.6
0.8
1
1.2
L (mH)
Higher Efficiency with Higher Inductor
but
it is miss-leading!
?
Winning by Power
Jeffrey Hwang
We have learned:
Without the Space Limit,
Higher inductance will have the higher efficiency.
Winning by Power
Jeffrey Hwang
Should we go higher frequency to solve the space issue?
Experiment 3th:
With RM8 and RM6, we fixed crest factor, r=0.95
and
Winding Factor is Optimal with the giving bubbin.
Winning by Power
Jeffrey Hwang
Po=100W, PFC boost Only
Constant r=crest factor=Ip-p/Irms=0.95
L (mH) vs Freq (kHz)
PC40, Crest Factor = 0.95
0.5
0.438
0.4
94
93.84%
93.5
93.70%
93.39%
RM6
93.04%
93
RM8
92.75%
92.76%
92.65%
92.5
0
50
100
150
200
L (mH)
Efficiency (%)
Efficiency (%) vs Freq (kHz)
PC40, Crest Factor = 0.95
Efficiency Difference of RM6 = 0.74%
Efficiency Difference of RM8 = 1.09%
0.432
0.303
0.3
RM6
0.3017
0.2
0.1
RM8
0.14
0.198
0.141
0
250
0
Freq (kHz)
50
100
150
Freq (kHz)
with Constant r=0.95
Higher Efficiency with Higher Inductance?
Higher Efficiency with Lower Frequency?
Again, it is miss-leading!
From above data, to improve efficiency, we only know that
we should reduce frequency to trade efficiency.
200
250
Winning by Power
Jeffrey Hwang
We have learned:
With the given space, frequency should be as low as
possible before the core is saturated.
The Lower Frequency provides the Higher Efficiency
Winning by Power
Jeffrey Hwang
What will happen with fixed switching frequency?
Experiment 4th:
Optimal Winding Factor for RM8 and fsw = 67.5Khz
Winning by Power
Jeffrey Hwang
fsw=67.5Khz with CM6800 100W demo board
Efficiency (%)
Efficiency (%) vs L (mH)
6800 Board
PC40, RM 8, Constant f SW = 67.5kHz
94
93.8
93.6
93.4
93.2
93
92.8
92.6
92.4
92.2
92
93.75
Pin ~ 110W
93.37
93.21
93.14
92.54
92.75 92.9
Adj Pin Compared to
Measurement on AC
Adaptor Board
92.72
92.14
0
0.5
1
1.5
L (m H)
L=442uH is the Highest Efficiency one; Crest Factor, r~1
Winning by Power
Jeffrey Hwang
fsw=100Khz with CM6800 100W demo board
Efficiency (%) vs L (mH)
6800 Board
PC40, RM8, Constant fSW = 100kHz
93.8
93.75
Efficiency (%)
93.7
93.75
93.63
93.6
93.5
Pin ~ 109W
93.4
93.3
93.2
93.15
93.1
0
0.5
1
1.5
L (m H)
L=295uH is the Highest Efficiency one; Crest Factor, r~1
Winning by Power
Jeffrey Hwang
fsw=100Khz with CM6800 100W demo board
Efficiency (%) vs DCR (ohm)
6800 Board
PC40, RM8, Constant fSW = 100kHz
93.8
Efficiency (%)
93.7
Efficiency (%) vs L Gap (mils)
6800 Board
PC40, RM8, Constant fSW = 100kHz
93.75
93.75
93.63
93.6
93.5
Pin ~ 109W
93.4
93.3
93.2
93.15
93.1
93.8
0.2
93.63
93.6
93.5
Pin ~ 109W
93.4
0.6
0.8
Efficiency (%) vs N (turns)
6800 Board
PC40, RM8, Constant fSW = 100kHz
93.3
93.2
0.4
DCR (ohm )
93.15
93.1
0
10
20
30
L Gap (m ils)
40
93.8
50
93.75
93.75
93.7
Efficiency (%)
Efficiency (%)
0
93.75
93.75
93.7
93.63
93.6
93.5
Series1
93.4
93.3
93.2
93.15
93.1
0
20
40
60
80
100
N (turns)
L=295uH is the Highest Efficiency one; Crest Factor, r~1
Winning by Power
Jeffrey Hwang
fsw=67.5Khz with CM6805 100W AC Adapter
Efficiency (%)
Efficiency (%) vs L (mH)
AC Adaptor Board
PC40, RM8, Constant fSW = 67.5kHz
86.40
86.24
86.20 86.01 86.23
85.96
86.00
86.04
85.80
85.57
85.60
85.61
85.40
85.43
85.20
84.94
85.00
84.88
84.80
0
0.5
1
Pin ~ 120W
Adj Pin Compared to
Measurement on
6800 Board
1.5
L (m H)
L=295uH is the Highest Efficiency one; Crest Factor, r~1.55
Winning by Power
Jeffrey Hwang
We have learned:
Crest Factor, r~1 to 1.55
L=442uH to 295uH for 67.5Khz and L=295uH for
100Khz
gives the best efficiency;
It means without saturating the core
Reducing DCR, Reducing lg , Reducing N, all will
improve the efficiency.
Winning by Power
Jeffrey Hwang
Conclusion:
Ferrite: PC95
RM8 (67.5Khz) --- > RM6 (100Khz)
295uH
with CM6805 (PFC+PWM combo IC)
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Jeffrey Hwang
442uH with fsw = 67.5Khz Vout = 220V,
Po = 100W, RM8 and PC 95
•
•
•
•
•
•
•
lg = 24 mil
N = 52.5 turns
Pin max = 146.56W
L = 400.58uH x 1.09
Al = 0.1584uH/turn^2
Ipeak at Sat = 2.3A
DCR = 0.09 ohm
• P core loss ~ 0.39W at
Pin max
• P copper loss ~
0.228W at Pin max
• Total P loss ~ 0.62W
at Pin max
• Wire Area = 0.44
mm^2 => AWG=21
Winning by Power
Jeffrey Hwang
295uH with fsw = 67.5Khz, Vout = 220V,
Po = 100W, RM8 and PC 95
•
•
•
•
•
•
•
lg = 20 mil
N = 40.5 turns
Pin max = 138.6W
L = 285uH
Al = 0.1738uH/turn^2
Ipeak at Sat = 2.178A
DCR = 0.05 ohm
• P core loss ~ 0.39W at
Pin max
• P copper loss ~ 0.12W
at Pin max
• Total P loss ~ 0.51W
at Pin max
• Wire Area = 0.57
mm^2 =>AWG=20
Winning by Power
Jeffrey Hwang
295uH with fsw > 100Khz, Vout = 220V,
Po = 100W, RM6 and PC 95
•
•
•
•
•
•
•
lg = 32 mil
N = 64.5 turns
Pin max = 118.93W
L = 229uH x 1.23
Al = 0.068uH/turn^2
Ipeak at Sat = 1.87A
DCR = 0.19 ohm
• P core loss ~ 0.15W at
Pin max
• P copper loss ~ 0.33W
at Pin max
• Total P loss ~ 0.48W
at Pin max
• Wire Area = 0.18
mm^2 =>AWG=25
Winning by Power
Jeffrey Hwang
100W AC Adapter without SR
Efficiency vs. Load
With 295uH(RM8), 442uH(RM8) and 303uH(RM6)
at fsw = 67.5Khz
AC Adaptor Board
Efficiency (% ) vs P O (W)
PC95, VIN=90VRMS, R VCC-IAC=25kohm
Efficiency (%)
RM8, L=295uH, DCR=0.1ohm, lg=20mils, N=40
RM8, L=442uH, DCR=0.15ohm, lg=20mils, N=50
RM6, L=303uH, DCR=0.33ohm, lg=30mils, N=64
88
87
86
85
84
83
82
81
80
79
RM8, L=295uH, DCR=0.1ohm, lg=20mils, N=40
RM8, L=442uH, DCR=0.15ohm, lg=20mils, N=50
RM6, L=303uH, DCR=0.33ohm, lg=30mils, N=64
0
20
40
60
PO (W)
80
100
Winning by Power
Jeffrey Hwang
100W AC Adapter without SR
Efficiency vs. Vin
With 295uH(RM8), 442uH(RM8) and 303uH(RM6)
at fsw = 67.5Khz
Efficiency (%)
AC Adaptor Board
Efficiency (% ) vs Line Voltage (VRMS)
PC95, R VCC-IAC=25kohm
RM8, L=295uH, DCR=0.1ohm, lg=20mils, N=40
RM8, L=442uH, DCR=0.15ohm, lg=20mils, N=50
RM6, L=303uH, DCR=0.33ohm, lg=30mils, N=64
89.5
89
88.5
88
87.5
87
86.5
86
85.5
Po=100W
Po=66W
RM8, L=295uH, DCR=0.1ohm, lg=20mils, N=40
RM8, L=442uH, DCR=0.15ohm, lg=20mils, N=50
RM6, L=303uH, DCR=0.33ohm, lg=30mils, N=64
89
139
189
VIN (VRMS)
239
Winning by Power
Jeffrey Hwang
100W AC Adapter with SR and without SR
Efficiency vs. Vin
With 442uH(RM8)
at fsw = 67.5Khz
100W AC Adapter
Efficiency with and without SR
Efficiency (%)
92
90
without SR
88
with SR
86
84
80
130
180
230
Vin (Vrms)
Measure the Efficiency Data at the end of cables.