Low Lowቤተ መጻሕፍቲ ባይዱLower Lowest Lowest Medium Lowest
Temp Stability
Better Better Good Good Good Good Poor
Curie Temp (℃) 700 700 500 700 740 400
100-300
10000 1000
①NPS 60μ ②NPF-C 60μ ③NPF 60μ ④PPI 40μ
NI = 75x15 = 1125
Using the AL vs NI Curves on core data of 1.57", the yield of AL value is 43.8 when NI is 1125. According to the formula: L=ALN2 L(@15A)=43.8x752/1000=246 (µH)
H=
0.4πNI
l
N = number of turns I = peak magnetic current ( amperes) l = mean magnetic path length (cm)
Permeability
The magnetizing force determines the estimate of magnetic flux density. The relative permeability is, by definition:
②①
⑤
④③
Core Loss (at 50kHz) Core Loss(mW/cm3)
100
DC Bias Curves Percent Permeability(%)
10 100
100
90
80
70
60
50
40
30 ①NPF 60μ
20 ②NPS 60μ
③PPI 40μ 10
④Ferrite(Gapped) 60μ
L = ALN2
AL = inductance factor (nH/N2) N = number of turns
Inductance can also be determined by the relative permeability and the effective core parameters.
μ=
B H
μ = relative permeability
B = magetic flux density (gausses) H = magnetizing force ( oersteds)
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●Magnetic Design Formulas
Q Factor
L=
4πμN2A l
A = effective cross section area (cm2) l = mean magnetic path length (cm) μ = relative permeability ( no dimensions)
Effective Magnetic Path Length
ωL Q = Rdc+Rac+Rd
ω = 2πfrequency (hertz) L = inductance (henries) Rdc = DC winding resistance (ohms) Rac = resistance due to core loss (ohms) Rd = resistance due to winding dielectric loss (ohms)
= 81x752/1000
DC magnetizing force (H) at 15A: H = 0.4πNI/l
= 0.4x3.14x75x15/9.84
= 455.6 (µH)
= 143.6 (Oe)
When magnetizing force is 143.6 Oe, the yield is 54% of initial permeability according to Permeability vs DC Bias
-
Bs ( Gauss ) 12,000 15,000 10,000 13,000 18,000 15,000
4,500
Core Loss
Low Medium
Low Medium
High Low Lowest
DC Bias
Better Best Good Good Best Better Poor
Relative Cost
Curves .
The inductance at 15A will decrease the inductance by 54% compared with at 0A.
Therefore, L(@15A)=455.6x0.54=246(µH)
By AL vs NI Curves Calculate NI:
Core Shapes
Toroids:0.5inch to 4.0inch Special:Block、Cylinder、U、EE
Permeability
NPF:26、40、60、75、90μ NPS:26、60、75、90、125、160μ PPI:40μ NPF-C:60μ PHD:30、40、60μ
Bmax =
Erms 108 4.44fAN
Bmax Erms f
= maximum flux density ( gausses) = voltage across coil (volts) = frequency (hertz)
Magnetizing Force
Using Ampere's law, the magnetizing force(H) is:
The quality factor (Q) is defined as the ratio of reactance to the effective resistance for an inductor and thus indicates its quality. The Q of wound core can be figured out with the following formula, when the effects of selfresonance caused by the dis
When a varying magnetic field passed through the core, eddy currents are induced in it. Joule heat loss by this currents called eddy current loss. Hysteresis loss is due to the irreversible behavior in hysteresis curve and equal to the enclosed area of th
l=
π(OD-ID)
ln(
OD ID
)
OD = outside diameter of core (cm) ID = inside diameter of core (cm)
Magnetic Flux Density
Using the Faraday's Law, the maximum flux density(Bmax) is figured out by the following fomular:
For toroidal powder cores, the effective area (A) is as the same as the cross sectional area. According to the definition and Ampere ’ s Law, the effective magnetic path length is the ratio of ampere-turns (NI) to the average magnetizing force. Using Amper
Core Loss
Total core loss at low flux densities is the sum of three losses of hysteresis, residual, and eddy current.
Rac μL
=
aBmaxf+cf+ef 2
a = hysteresis loss coefficient c = residual loss coefficient e = eddy current loss coefficient μ,L,Bmax,f = as above
4-24
●Magnetic Core Design Soft
Core design software is available for download at no charge from
5-24
Insulation layer (Ceramic)
Magnetic alloy
No Organic binder ► No thermal aging effect
Core Primary Materials
NPF CORE:FeSi alloy NPS CORE:FeSiAl alloy PPI CORE:FeSi alloy NPF-C CORE:FeSi alloy PHD CORE:FeSi alloy
Inductance Calculation
Electrical Specifications Core: NPF157060 AL: 81 nH/N2
Number of winding: 75T Current: DC 15A
By permeability vs DC Bias Curves