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Jeffrey Hwang Winning by Power Alland Chee, Elvis Lin, Joe Wong and Jeffrey H. Hwang Design a 100W PFC Boost Inductor

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Jeffrey Hwang Winning by Power Criteria of Selection Size Efficiency Cost

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Jeffrey Hwang Winning by Power 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]=[ Gauss ] Magnetic Field=Flux Density=Magnetic Induction H: [ ] Magnetic Field Strength=Magnetic Force=MMF per length Review Important Magnetic Variables and Important Magnetic Constants 1[Tesla]=1[Weber/Meter 2 ]=10 4 [Gauss]=1[Newton/(Ampere x Meter)] 1[Weber]=1[Wb]=10 8 Maxwell [L]=1[henry]=1[Volt x Sec/Ampere]=1[Wb/Amp] μ 0 =Air Permeability Constant=4π x [Tesla Meter/Ampere]

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Jeffrey Hwang Winning by Power R=mmf /Φ B =NI/Φ B = ι m/ (A c μ) R e =R l + R air = ι m/ (A c μ) + ι air/ (A c μ air )= Φ B = L=N Φ B /I=N 2 / R e = Important Magnetic Formula B=μ H= μ x mmf/l eff = Φ B /A c = μ x N x I/l eff = L x I/(N x A ac)

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Jeffrey Hwang Winning by Power B max = given material PC95:Bmax~350mT PC44:Bmax~300mT PC40:Bmax~270mT

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Jeffrey Hwang Winning by Power NI max = l air, air gap is fixed

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Jeffrey Hwang Winning by Power Sundest, MPP, Ferrite…? Experiment 1st: Selecting the best Magnetic Material

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Jeffrey Hwang Winning by Power Selecting Magnetic Materials Ferrite and MPP have the higher efficiency performance. Ferrite is our selection.

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Jeffrey Hwang Winning by Power 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!

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Jeffrey Hwang Winning by Power 290uH or 1mH? Experiment 2nd: DCR and switching frequency is fixed Winding Factor is not optimal.

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Jeffrey Hwang Winning by Power With fixed DCR=0.46 ohm and fixed fsw=67.5Khz, Po=100 W and Vo=19V AC Adapter Higher Efficiency with Higher Inductor ? but it is miss-leading!

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Jeffrey Hwang Winning by Power We have learned: Without the Space Limit, Higher inductance will have the higher efficiency.

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Jeffrey Hwang Winning by Power 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.

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Jeffrey Hwang Winning by Power Po=100W, PFC boost Only Constant r=crest factor=Ip-p/Irms=0.95 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.

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Jeffrey Hwang Winning by Power 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

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Jeffrey Hwang Winning by Power What will happen with fixed switching frequency? Experiment 4 th : Optimal Winding Factor for RM8 and fsw = 67.5Khz

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Jeffrey Hwang Winning by Power fsw=67.5Khz with CM W demo board L=442uH is the Highest Efficiency one; Crest Factor, r~1

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Jeffrey Hwang Winning by Power fsw=100Khz with CM W demo board L=295uH is the Highest Efficiency one; Crest Factor, r~1

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Jeffrey Hwang Winning by Power fsw=100Khz with CM W demo board L=295uH is the Highest Efficiency one; Crest Factor, r~1

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Jeffrey Hwang Winning by Power fsw=67.5Khz with CM W AC Adapter L=295uH is the Highest Efficiency one; Crest Factor, r~1.55

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Jeffrey Hwang Winning by Power 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.

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Jeffrey Hwang Winning by Power Conclusion: Ferrite: PC95 RM8 (67.5Khz) --- > RM6 (100Khz) 295uH with CM6805 (PFC+PWM combo IC)

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Jeffrey Hwang Winning by Power 442uH with fsw = 67.5Khz Vout = 220V, Po = 100W, RM8 and PC 95 lg = 24 mil N = 52.5 turns Pin max = W L = uH x 1.09 Al = uH/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

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Jeffrey Hwang Winning by Power 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 = uH/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

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Jeffrey Hwang Winning by Power 295uH with fsw > 100Khz, Vout = 220V, Po = 100W, RM6 and PC 95 lg = 32 mil N = 64.5 turns Pin max = W 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

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Jeffrey Hwang Winning by Power 100W AC Adapter without SR Efficiency vs. Load With 295uH(RM8), 442uH(RM8) and 303uH(RM6) at fsw = 67.5Khz

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Jeffrey Hwang Winning by Power 100W AC Adapter without SR Efficiency vs. Vin With 295uH(RM8), 442uH(RM8) and 303uH(RM6) at fsw = 67.5Khz Po=100W Po=66W

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Jeffrey Hwang Winning by Power 100W AC Adapter with SR and without SR Efficiency vs. Vin With 442uH(RM8) at fsw = 67.5Khz Measure the Efficiency Data at the end of cables.

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