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APPLICATIONS
‧Wideband transformer
‧pulse transformer
‧inductor
‧ filter
‧T, EE, ET, etc.
A2. 錳鋅高導材料發展地圖和特性
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Critical in common mode
choke design selection
A2. 錳鋅高導材料發展地圖和特性
磁性材料的磁導率會隨著頻率的升高而下降,因為磁導率和頻
率的乘積是一個常數 Snoek Limit
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A2. 錳鋅高導材料發展地圖和特性
材料開發目標
磁導率和頻寬越高越好
基本違反物理定律
where:
fg – gyromagnetic critical frequency
γ ~0.22 ΜΗz m/A is the gyromagnetic ratio for an electron
i.e. the ratio of magnetic moment and torque
Bs – saturation flux density
μi,0– initial permeability * J. L. Snoek, Physica 14, 207, 1948
sig Bf
3
4
)1( 0, Snoek Limit
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Applied Frequency
N5 N51
1MHz 100MHz 1GHz
1000
10000
Higher
frequency
電磁抑制和電磁兼容的鐵氧體產品地圖
Ni-Zn:K08,K10, K15, K20
5000
10MHz
100
High Perm.:
A151,A121,
A102, A10,
A07, A05
High pass band
InitialPermeability
A4. 鐵氧體特性與應用
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InitialPermeability
Applied Frequency
Telecom filters and
chokes:
N4, N43
10KHz 1MHz 10MHz
1000
10000
HF
Under Development
通訊應用的鐵氧體產品地圖
5000
100KHz
Ni-Zn,High Q filters and
chokes:
L1, L2, L3 L4 L5…
100
High Perm. For xDSL:
A101
High Perm. For outdoor
xDSL:N07
Wide temperature
stability
Pulse X’fmer for LAN:
A043, A061
High Bs for Telecom Wideband
X’fmer: N42
Low THD
Wide temperature
range
High
Bs
A4. 鐵氧體特性與應用
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B. 鐵氧體規格 – “材料” & “產品”
鐵氧體材料的關鍵規格
a. 初導率和振幅磁導率: ui 與 ua
b. 飽和磁通密度 Bsat
c. 功率損失密度 Pv
d. 有效操作頻寬
江解釋於後. 其他規格,如:
剩磁 (Brms) 、矯頑力 (Hc), 磁滯常數 (ηB), Disaccommodation
Factor (DF) 與 品質因數 (Q) 將另外討論
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B. 鐵氧體規格 – “材料” & “產品”
為什麼 B-H 曲線對強磁性材料如此重要!
Magnetic Field H
Flux density B
Permanent magnetics
永磁
Soft magnetic material
軟磁
Bsat
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B. 鐵氧體規格 – “材料” & “產品”
磁導率有兩種 ui and ua
Freq. Flux den. Temp. P45 P46 P47
Initial Permeability μi ≤ 10KHz 0.25mT 25°C 3100 ± 25% 3300 ± 25% 3000 ± 25%
25°C > 5000 > 4500 > 5000
100°C > 5000 > 4500 > 5000
Unit Measuring Conditions Wide Temperature Low Loss Materials
Amplitude Permeability μa 25KHz 200mT
Symbol
規格書只列出特定條件下的數值
但磁導率(permeability) 是溫度和負載(磁通密度)的非線性函數
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B. 鐵氧體規格 – “材料” & “產品”
磁導率(permeability) 是負載(磁通密度)的非線性函數
ui 與 ua 的差別在於磁路徑上的磁通密度不同
ui 是極低磁通密
度下的ua
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B. 鐵氧體規格 – “材料” & “產品”
B-H 曲線 是個 “磁滯迴圈” (Pętla histerezy)
Flux Density B[T]
Magnetic Residue Br
Coercive Force Hc
Magnetic Field
H [A/m]
Saturation (Bsat)
Hmax
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B. 鐵氧體規格 – “材料” & “產品”
Przenikalność początkowa 初磁導率
Initial Permeability
0H0
i
H
B
µ
1
µ
0.1mT
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B. 鐵氧體規格 – “材料” & “產品”
µi initial permeability
µm maximal
permeability
µa amplitude
permeability
µdif or µrev reverse
permeability
)1.0,25(
)1.0,25(
)1.0,25(
)( mTBkHzf
mTBkHzf
mTBkHzf
ACDCrevdif
ACa
ACi
ii
i
i
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B. 鐵氧體規格 – “材料” & “產品”
飽和磁通密度 Bsat
Bsat的觀念和規格有誤區,鐵氧體材料,有用的磁場強度,不會超過200A/m!
其實只有這一段可用!
This is the real usable
Hmax range for soft
ferrite and SMPS
designer should be care
about the Bmax available
in the maximal applied H
range
The proviso for Bsat=
530mT is H =1200A/m, this
is the legal commercial
employed by the industry.
Useless in practical designs