DC Biased Chokes for High Frequency Power Applications...DC Chokes use only narrow range of flux...
Transcript of DC Biased Chokes for High Frequency Power Applications...DC Chokes use only narrow range of flux...
DC Biased Chokes for High Frequency Power ApplicationsM.Sc. Martin Grübl
Overview of PIRATE-technology
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P ermanentmagneticI nlay forR everse-BiasA ctivityT echnologyE xtension
• Basic core out of soft magnetic ferrite with very high saturation flux density SUMIDA Fi339
• Together with hard magnetic inlay with outstanding inner resistance for low eddy current lossesSUMIDA Fi701
• Both materials are SUMIDA developments and unique on the world market.
• Mechanical limits of the magnet:height: min 1 mm; surface area max. 50 cm²
Applications for PIRATE-chokes
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DC Chokes use only narrow range of flux density capability
Used flux density
Flux density capability of a common ferrite core
Applications for PIRATE-chokes
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PIRATE eliminates DC Offsets• Cores can get smaller• Saturation performance rises
Unused capability of the core
Flux density capability of the core
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Applications for PIRATE-chokes
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Rule of Thumb: PIRATE Technology is possible if winding losses are three times higher than core losses𝑷𝑷𝑾𝑾𝑷𝑷𝑪𝑪
> 𝟑𝟑
0,0
1,0
2,0
3,0
4,0
0 100 200 300 400
L /µ
H
I /A
without Magnet
with Magnet Fe701
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Sample project using PIRATE-choke
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Component: PV converter DC boost choke 550µH, 30ASumida Project No: EI 140 514 11
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Sample project with PIRATE-chokes
EI 140 514 11 42Original design
EI 140 514 11 32PIRATE
Advantages of PIRATE design
Weight 2,63 kg 1,93 kg -26%
Volume 700 cm³ 525 cm³ -25%
Turns 45 28 -37%
Rdc 18 mΩ 12 mΩ -33%
Pv (@23A, 100°C) 12,4 W 8,2 W -33%
Rs (@20 kHz) 440 mΩ 370 mΩ -16%
fres 1,5 MHz 1,7 MHz +13%
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Lifetime Test Result - Industrial Application
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Magnet temperature 90°CDC-Offset: 260 mTΔB = 200 mTf = 18 kHzL= 500 µH
Degradation of the energy maximum (0,5*L*I²) of a PIRATE Choke
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Co-sintered air gap
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Distributed air gaps in ferrites decrease fringing of magnetic flux.
Original technology for distributed air gaps: Sandwich gluing of ferrites and plastics.
Disadvantage: thermal insulation due poor thermal conductivity of plastic material
New patented Sumida technology: Co-sintered air gap
Advantages:• Homogeneous structure of the ferrite column• Better heat flow conditions • Cost neutral against original technologies• Minimum air gap: 1 mm
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Co-sintered air gap
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Comparison of thermal behaviour:Original glued air gap vs. co-sintered air gap
Fi010 FR4
Characteristics Fi010 FR4
µi (air gap material) 1,1 1,0
Thermal conductivity [W/m/K] 5 0,25
Hot Spot [°C] 114 122
Thermal expansion [ppm/K] 8 70
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Thank you for your attention!
Further Questions ?
Backup Folien
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Datasheet of SUMIDA Fe701 Hard Magnetic Compound
Item ValueBasis NdFeB
µi 1,1
Hcb -300 kA/m
Hcj -970 kA/m
Br 420 mT
Spec. resistance 38 Ωm
Density 4,4 g/cm³
Spec. Losses (@ 100°C, 72kHz. 70mT)
<200 mW/cm³
Tmax 150 °C
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Other outstanding ferrite technologies of Sumida
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Plastoferrite (plastic bonded ferrite particles)• Overmoulded busbars for DM – filtering• Free-shaped geometries and narrow tolerances• µ = 0 – 22 possible• Cost ~1,5x costs of common production (pressed ferrite)
Injection Moulded Ferrites• Free-shaped geometries• µ = up to 4000• Similar properties to common ferrite cores• Cost ~ 1,5x costs of common production (pressed ferrite)
Thin-slide ferrites• 0,6 mm possible• Ideal for shielding
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