Post on 12-Nov-2015
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Dongbu CNI
Dongbu CNI
Dongbu CNI
Dongbu CNI
Dongbu CNI
Inductance of Wound Cores
The inductance of a core and the number of turns can be calculated by using the following formula.
Magnetic Design Formula
L = Where L = induntance (H) = core permeability N = number of turns A = core cross section area (cm2) l = mean magnetic path length (cm) LN = inductance for N turns (H) AL = nominal inductance(nH/N2)
Where H = magnetizing force (Oersteds) N = number of turns I = peak magnetizing current (A) = mean magnetic path length (cm) Bmax = maximum flux density (Gauss) Erms = voltage across coil (V) A = core cross section area (cm2) f = frequency (Hz) = material permeability
N = 10 turns (our standard wound turns for M040-066A) A = 0.100cm2 (please see the page 56) = 2.380cm (please see the page 56) LN = 66 x 10
2 x 10-3 = 6.60(H)
0.4N2A x 10-2
Required N =
0.4NI
LN = AL x N2
103
L1
Example) M040066A
L = = 6.60(H)0.4 x 125 x 102 x 0.100 x 10-2
2.380
The relations of Permeability-Flux Density(B)-Magnetizing Force(H)
H = (Amperes Law)
(Faradays Law)Ermsx102
4.44fANBmax =
BH
=
2
L2
2=
Amperes Law : The law is the magnetic equivalent of Gausss law. It relates the circulating magnetic field in a closed loop to the electric current passing through the loop
Faradays Law : The law that defines the relationship of the voltage induced across the winding of a core to the flux density within the core
( )1/2desired L(nH)
AL(nH / N2)N1 N2
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Technical Information
Core : M040066AApplied current : 3A
The total core losses are made up of three maincomponents : Hysteresis, eddy current and residual losses.
1) Inductance Calculation at 0A
Inductance calculation by Permeability vs. DC bias curves Specification
L = = 6.60(H)
N = 10 turns (our standard wound turns for M040-066A) A = 0.100cm2 (please see the page 56) = 2.380cm (please see the page 56) LN = 66 x 10
2 x 10-3 = 6.60(H)
Where Rac = effective resistance (Ohm) a = hysteresis loss coefficient c = residual loss coefficient e = eddy current loss coefficient = same as before mentioned L = inductance Bmax = maximum flux density f = frequency
Eddy current loss
Residual loss
Hysteresis loss
Total loss factor
0.4 x 125 x 102 x 0.100 x 10-22.380
RacL
2) Magnetizing force (H : Oe) is calculated by Ampere law to achieve the roll off
H = = = 15.8(Oe)0.4 x x N x I
0.4 x x 10 x 3
2.38
3) When the magnetizing force(H) is 15.8 Oe, yielding 85% of initial permeability. Therefore, the Inductance at 3A is
L(3A) = 6.6 x 0.85 = 5.6(H)
Core loss
= aBmaxf + cf + ef2
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Dongbu CNI
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Dongbu CNI
Window Area = x
The Q factor is the ratio of reactance to the effective resistance and is often used as measure of performance. So, the Q factor represents the effect of electrical resistance.
Q Factor
Q =
Where Q = quality factor = 2f (Hz) L = inductance (H) Rdc = DC winding resistance (Ohm) Rac = resistance due to core losses (Ohm) Rd = resistance due to winding dielectric
losses (Ohm)
Le = effective mean magnetic path length (cm) Ae = effective core cross section area (cm2 ) Ve = effective core volume (cm3) OD = core outer diameter before coating (cm) ID = core inner diameter before coating (cm) HT = core height before coating (cm)
LRdc + Rac + Rd =
ReactanceTotal Resistance
x HT
Le = (OD-ID)
Physical constant of core
In ODID
Ve = Le x Ae
CGS (unit) By To obtain (unit) Factor
Magnetic Flux Density (B) Gauss (G) 10-4 Tesla (T) 1T=104G
Magnetizing Force (H) Oersted (Oe) 79.58 Amperes per Meter (A/m) 1A/m=4/103Oe
Conversion Table
ID2( )
2
Ae = OD-ID
2
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Technical Information
The increase in surface temperature of a component in free-standing air due to the total power dissipation (both copper and core loss). The following formula has been used to approximate temperature rise:
Total Power Loss = Copper Loss + Core LossSurface Area means in case of wound core
Nominal DC Resistance, in ohm/mH, at any given winding factor can be calculated by using the following equations:
Temperature Rising Calculation
Temperature Rise(oC) =
Where /mhwf = mh for chosen winding factor /mhu = unity value, listed for each core size wf = chosen winding factor Kwf = length/turn for chosen wf* Ku = length/turn for unity(100%) wf*
* see Winding Turn Length on core size pages
Total Power Loss (milliwatts)Surface Area(cm2)
/mhuwf
KwfKu
Nominal DC Resistance
/mhwf = x
The value of Rdc for any given winding factor can be computed as follows:
Where Rdcwf = Rdc for chosen winding factor Rdcu = unity value, listed for each core size(ohms) wf = chosen winding factor Kwf = length/turn for chosen wf* Ku = length/turn for unity(100%) wf* * see Winding Turn Length on core size pages
KwfKu
Rdcwf = Rdcu x wfx
( )0.833
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MPP
10
High Flux
100 1000 10000
Frequency (kHz)
Frequency (kHz)
Per
cent
Per
mea
bilit
y(%
)P
erce
nt P
erm
eabi
lity(
%)
10 100 1000 10000
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
14 26 60
125
14
26
60
125
Permeability vs. Frequency
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Technical Information
Permeability vs. Frequency
Sendust100
98
96
94
92
90
88
86
84
82
80
100
90
80
70
60
50
40
30
20
10
0
Frequency (kHz)
Per
cent
Per
mea
bilit
y(%
)P
erce
nt P
erm
eabi
lity(
%)
Power Flux
60
90
14 26
35 60
75
125
90
Frequency (kHz)
10 100 1000 10000
10 100 1000 10000
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MPP
Normal Magnetizing Curves
8000
7000
6000
5000
4000
3000
2000
1000
0
High Flux
Flux
Den
sity
(Gau
ss)
1 10 100 1000
14000
13000
12000
11000
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
125
60
125
60
26
26
Flux
Den
sity
(Gau
ss)
1 10 100 1000
Magnetizing Force (Oersteds)
Magnetizing Force (Oersteds)
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Technical Information
Sendust
16000
14000
12000
10000
8000
6000
4000
2000
01 10 100 1000
Magnetizing Force (Oersteds)
Magnetizing Force (Oersteds)
11000
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
90
60
Flux
Den
sity
(Gau
ss)
Flux
Den
sity
(Gau
ss)
Power Flux
1 10 100 1000
125
90
75
60
26
Normal Magnetizing Curves
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MPP4
3
2
1
0
-110 100 1000 10000
10 100 1000 10000
AC Flux Density (Gauss)
Per
cent
Cha
nge
of P
erm
eabi
lity
(%)
125
60
26
High Flux30
25
20
15
10
5
0
-5
-10
AC Flux Density (Gauss)
Per
cent
Cha
nge
of P
erm
eabi
lity
(%) 125
60
26
Permeability vs. AC Flux Density
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Permeability vs. AC Flux Density
4
3
2
1
0
-1
4
3
2
1
0
-1
AC Flux Density (Gauss)
Per
cent
Cha
nge
of P
erm
eabi
lity
(%)
perc
ent c
hang
e of
per
mea
bilit
y(%
)
Sendust
Power Flux
AC Flux Density (Gauss)
125
90
75
60
26
60
Technical Information
10 100 1000 10000
10 100 1000 10000
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MPP100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
DC Mangnetizing Force (Oe)
DC Mangnetizing Force (Oe)
Per
cent
Per
m e
abili
ty (%
)P
erce
nt P
erm
eab
ility
(%)
High Flux
125 60 26 14
125 60 26 14
1 10 100 1000
1 10 100 1000
20 21
Permeability vs. DC Bias Curves
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Technical Information
Sendust100
90
80
70
60
50
40
30
20
10
01 10 100 1000
1 10 100 1000
100
90
80
70
60
50
40
30
20
10
0
DC Mangnetizing Force (Oe)
DC Mangnetizing Force (Oe)
Per
cent
Per
m e
abili
ty (%
)P
erce
nt P
erm
eab
ility
(%)
Power Flux
Technical Information125 90 7560 35 26 14
90 60
Permeability vs. DC Bias Curves
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Factors of Permeability vs. DC Bias Fit Formula
14 -3.5204E-05 -1.8222E-08 -3.5714E-05 5.1020E-08
26 -4.7041E-05 -2.2758E-09 -4.6154E-05 2.9586E-08
60 -8.2917E-05 1.8519E-09 -5.8333E-05 2.7778E-08
125 -7.2890E-05 1.3824E-09 -9.0400E-05 3.2000E-08
0 a b c d
14 -7.6531E-06 -3.2799E-09 1.4286E-06 5.1020E-09
26 -2.4556E-05 -1.7069E-09 1.1538E-05 5.9172E-09
60 -2.8972E-05 -4.6296E-10 -2.5000E-05 8.3333E-09
125 -3.4861E-05 3.0720E-10 -3.5200E-05 6.4000E-09
MPP
High Flux
a1
=c d + +
b+ + 20 30 20
2 0
40
2
e ff
0 a b c d
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a1
=c d + +
b+ + 20 30 20
2 0
40
2
e ff
Factors of Permeability vs. DC Bias Fit Formula
14 -3.6735E-05 -7.2886E-09 -2.1429E-05 3.0612E-08
26 -9.1716E-05 2.2758E-09 8.4615E-05 1.4793E-08
35 -1.0522E-04 2.3324E-09 4.8571E-05 1.6327E-08
60 -7.4250E-05 1.8519E-09 1.3333E-05 1.3889E-08
75 -9.1058E-05 2.1333E-09 3.4667E-05 1.0667E-08
90 -8.2457E-05 1.7833E-09 1.0000E-05 2.4691E-08
125 -9.1155E-05 1.9456E-09 -9.6000E-06 2.5600E-08
60 -3.5444E-05 -1.8519E-10 6.6667E-07 8.3333E-09
90 -5.4914E-05 8.2305E-10 -4.4444E-06 8.6420E-09
Sendust
Power Flux
Technical Information
0 a b c d
0 a b c d
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Factors of Percentage Permeability (x100) calculation
14 -4.9286E-04 -3.5714E-06 -5.0000E-04 1.0000E-05
26 -1.2231E-03 -1.5385E-06 -1.2000E-03 2.0000E-05
60 -4.9750E-03 6.6667E-06 -3.5000E-03 1.0000E-04
125 -9.1112E-03 2.1600E-05 -1.1300E-02 5.0000E-04
0 k l m n
14 -1.0714E-04 -6.4286E-07 2.0000E-05 1.0000E-06
26 -6.3846E-04 -1.1538E-06 3.0000E-04 4.0000E-06
60 -1.7383E-03 -1.6667E-06 -1.5000E-03 3.0000E-05
125 -4.3576E-03 4.8000E-06 -4.4000E-03 1.0000E-04
MPP
High Flux
k l1Ratio
of Perm . =
+ + 2
m n1 + + 2
0 k l m n
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k l1Ratio
of Perm . =
+ + 2
m n1 + + 2
Factors of Percentage Permeability (x100) calculation
14 -5.1429E+00 -1.4286E-02 -3.0000E-04 6.0000E-06
26 -2.3846E+01 1.5385E-02 2.2000E-03 1.0000E-05
35 -3.6829E+01 2.8571E-02 1.7000E-03 2.0000E-05
60 -4.4550E+01 6.6667E-02 8.0000E-04 5.0000E-05
75 -6.8293E+01 1.2000E-01 2.6000E-03 6.0000E-05
90 -7.4211E+01 1.4444E-01 9.0000E-04 2.0000E-04
125 -1.1394E+02 3.0400E-01 -1.2000E-03 4.0000E-04
60 -2.1267E-03 -6.6667E-07 4.0000E-05 3.0000E-05
90 -4.9422E-03 6.6667E-06 -4.0000E-04 7.0000E-05
Sendust
Power Flux
Technical Information
0 k l m n
0 k l m n
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Typical Core Loss of MPP
MPP 14
Flux Density (Gauss)
PL=2.33F1.31B2.19
10 100 1000 10000
MPP 26
200KH
z100
KHz
50KHz 25K
Hz
Cor
e Lo
ss (m
W/c
m3 )
Flux Density (Gauss)
10 100 1000 10000
200KH
z100
KHz
50KHz 25K
Hz
Cor
e Lo
ss (m
W/c
m3 )
10000
1000
100
10
1
0.1
10000
1000
100
10
1
0.1
PL=C X F
a X B
b
(F : kHz - B : kG)
Perm. C a b
14 2.33 1.31 2.19
26 1.39 1.28 1.29
PL=1.39F1.28B1.29
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Flux Density (Gauss)
10 100 1000 10000
MPP 60
MPP 125
PL=0.64F1.41B2.20
200KH
z100
KHz 50K
Hz 25KH
z
Flux Density (Gauss)
10000
1000
100
10
1
0.110 100 1000 10000
200KH
z100
KHz
50KHz
25KHz
Cor
e Lo
ss (m
W/c
m3 )
10000
1000
100
10
1
0.1
Cor
e Lo
ss (m
W/c
m3 )
Typical Core Loss of MPP
PL=C X F
a X B
b
(F : kHz - B : kG)
Perm. C a b
60 0.64 1.41 2.20
125 1.02 1.40 2.03
PL=1.02F1.40B2.03
Technical Information
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Typical Core Loss 01 High Flux
Hlgh Flux 14 p. HIDl
/ '2.~ g OiJ' ~
1"
100
'"
({
E)
e
P l =726fO.95Bul
1III HlXl
Flux Density (Ga=) 100
0.1
'"
H lgh Flux 26 (JlXJ
/ l &
1m
100
10
(E
E) $
g
PL =1 .38F\37B230
1 lXl 1(lXJ
FI, Oensily (Gauss)
100 0.1
10
b a c Po
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Typical Core Loss of High Flux
PL=C X F
a X B
b
(F : kHz - B : kG)
Flux Density (Gauss)
10 100 1000 10000
HIgh Flux 60
HIgh Flux 125
200KH
z 100KH
z 50KHz 25K
Hz
Flux Density (Gauss)
10 100 1000 10000
200KH
z 100KH
z50K
Hz25K
Hz
10000
1000
100
10
1
0.1
Cor
e Lo
ss (m
W/c
m3 )
10000
1000
100
10
1
0.1
Cor
e Lo
ss (m
W/c
m3 )
PL=3.65F1.15B2.16
PL=1.62F1.32B2.20
Technical Information
Perm. C a b
60 3.65 1.15 2.16
125 1.62 1.32 2.20
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Typical Core Loss of Sendust
Sendust 14, 26
Flux Density (Gauss)
200KHz 100
KHz 50KHz
25KHz
Cor
e Lo
ss (m
W/c
m3 )
PL=2.27F1.26B2.08
10 100 1000 10000
10000
1000
100
10
1
0.1
Flux Density (Gauss)
10 100 1000 10000
Sendust 60,75,90,125
200KH
z 100KHz 50K
Hz 25KHz
10000
1000
100
10
1
0.1
Cor
e Lo
ss (m
W/c
m3 )
PL=2.00F1.31B2.15
PL=C X F
a X B
b
(F : kHz - B : kG)
Perm. C a b
14, 26 2.27 1.26 2.08
60,75,90,125 2.00 1.31 2.15
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Power Flux 60, 90
Flux Density (Gauss)
10000
1000
100
10
1
0.110 100 1000 10000
200KH
z100
KHz 50K
Hz 25KHz
Cor
e Lo
ss (m
W/c
m3 )
PL=4.51F1.25B2.21
Typical Core Loss of Power Flux
Perm. C a b
60, 90 4.51 1.25 2.21
Technical Information
PL=C X F
a X B
b
(F : kHz - B : kG)
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Temperature Stability
MPP
3.0
2.0
1.0
0.0
-1.0
-2.0-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130
Temperature (oC)
Per
cent
Per
mea
bilit
y (%
) 125 60
26
14
5.0
4.0
3.0
2.0
1.0
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
Per
cent
Per
mea
bilit
y (%
)
60 2614
125
High Flux
-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130
Temperature (oC)
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Per
cent
Per
mea
bilit
y (%
)
Temperature Stability
Sendust
125
90
75
90
60
Per
cent
Per
mea
bilit
y (%
)
14,2660
2.0
1.0
0.0
-1.0
-2.0
-3.0
-4.0
-5.0
-6.0
-7.0
5.0
4.0
3.0
2.0
1.0
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
Power Flux
-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130
Temperature (oC)
-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130
Temperature (oC)
Technical Information
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Symbol and Units
Symbol Discription Unit
Ae effective cross section area of a core cm2
AL apparent inductance nH/N2
B magnetic flux density T
Br remanence flux density T
Bmax maximum flux density T
Erms sinusoidal rms voltage across winding V
H magnetizing force A/m
Hc coercive force A/m
Hmax maximum magnetizing force A/m
e effective magnetic path length cm
L inductance H
N number of turns -
PL core loss of a core mW/cm3
Q quality factor -
V volume of a core cm3
Rdc DC winding resistance
absolute permeability -
e effective permeability -
i initial permeability -
r relative permeability -
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Glossary of Terms
AC flux density
Number of flux lines per unit of cross-sectional area generated by an alternating magnetic field; Gauss
Air Gap
A non-magnetic discontinuity in a ferro-magnetic circuit. For example, the space between the poles of a magnet, although filled with brass of wood and other non-magnetic material, is nevertheless called an air gap.
Breakdown Voltage
(1)The voltage at which an insulator or dielectric ruptures, or at which ionization and conduction take place in a gas or vapor. (2) The reverse voltage at w h i c h a v a l a n c h e b r e a k d o w n o c c u r s i n a semiconductor. (3) Maximum AC or DC voltage that can be applied from the input to output (or chassis) of a converter without causing damage.
Choke
An inductor which is intended to filter, or 'choke', out unwanted signals.
Copper Loss
The power loss by current flowing through the winding. The power loss is equal to the square of the current multiplied by the resistance of the wire (I2 X R). This power loss is transferred into heat.
Core Losses
Core losses are caused by an altering magnetic field in the core material. The losses are a function of the operating frequency and the total magnetic flux swing. The total core losses are made up of three main components: Hysteresis, eddy current and residual losses. These losses vary considerably from one magnetic material to another. Applications such as higher power and higher frequency switching regulators require careful core selection to yield the highest inductor performance by keeping the core losses to a minimum.
Core Saturation
The DC bias current flowing through an inductor which causes the inductance to drop by a specified amount from the initial zero DC bias inductance va lue . Common spec i f i ed induc tance d rop percentages include 10% for ferrite cores and 20% for iron powder cores in energy storage applications. Also referred to as saturation current.
Curie Temperature
The temperature at which a magnetic material loses its magnetic properties. The core's permeability typical ly increases dramat ical ly as the core temperature approaches the curie temperature, which causes the inductance to increase. The permeabi l i ty drops to near unity at the curie temperature, which causes the inductance to drop dramatically. The curie point is the temperature at which the initial permeability (i) has dropped to 10% of its value at room temperature.
Technical Information
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Glossary of Terms
DC Bias
Direct current (DC) applied to the winding of a core in addition to any time-varying current. Inductance with DC bias is a common specification for powder cores. The inductance will 'roll off' gradually and predictably with increasing DC bias.
DCR
Direct Current Resistance - The resistance of the inductor winding measured with no alternating current. The DCR is most often minimized in the design of an inductor. The unit of measure is ohms and it is usually specified as a maximum rating.
Distributed Capacitance
(1) In the construction of an inductor, each turn of wire or conductor acts as a capacitor plate. The combined effects of each turn can be presented as a single capaci tance known as the distr ibuted capacitance. The capacitance is in parallel with the inductor. This parallel combination will resonate at some frequency, which is called the self-resonant frequency (SRF). Lower distributed capacitance for a given inductance will result in a higher SRF and vice versa. (2) Capacitance that is not concentrated within a lumped capacitor, but spread over a circuit or group of components.
Eddy Current Losses
Core losses associated with the electrical resistivity of the magnetic material and induced voltages within the material. Eddy currents are inversely proportional to material resistivity and proportional to the rate of
change of flux density. Eddy current losses are present in both the magnetic core and windings of an inductor. Eddy currents in the winding, or conductor, contribute to two main types of losses: losses due to proximity effects and skin effects. As for the core losses, an electric field around the flux lines in the magnetic field is generated by alternating magnetic flux. This will result in eddy currents if the magnetic core material has electrical conductivity. Losses result from this phenomenon since the eddy currents flow in a plane that is perpendicular to the magnetic flux lines. Eddy current and hysteresis losses are the two major core loss factors. Eddy current loss becomes dominant in powder cores as the frequency increases.
Effective Permeability
For a magnetic circuit constructed with an air gap, or g a p s , t h e p e r m e a b i l i t y o f a h y p o t h e t i c a l homogeneous material that would provide the same reluctance, or net permeability.
EMC
Electromagnetic compatibility. The ability of an e lect ronic dev ice to operate in i ts in tended environment without its performance being affected by EMI and without generating EMI that will affect other equipment.
EMI
Electro-Magnetic Interference - An unwanted electrical energy in any form. EMI is often used interchangeably with 'noise' and 'interference'.
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Glossary of Terms
Flux Density (B)
The corresponding parameter for the induced magnetic field in an area perpendicular to the flux path. Flux density is determined by the field strength and permeabil i ty of the medium in which it is measured.
Full Winding
A winding for toroidal cores that will result in 45% of the core's inside diameter remaining.
Harmonics
Energy at integral multiples of the frequency of the fundamental signal. Normally expressed as THD (Total Harmonic Distortion) but can be specified for harmonics of interest in either a percentage of or decibels below the power level of the fundamental frequency signal.
Hysteresis Loss
Hysteresis means to lag behind. This is the tendency of a magnetic material to retain its magnetization. Hysteresis causes the graph of magnetic flux density versus magnetizing force (B-H curve) to form a loop rather than a line. The area of the loop represents the difference between energy stored and energy released per unit of volume of material per cycle. This difference is called the hysteresis loss.
Hysteresis Loop
A closed curve obtained for a material by plotting
corresponding values of flux density for the ordinate and magnetizing force for the abscissa when the material is passing through a complete cycle between definite limits of either magnetizing force or f lux density. I f the material is not driven into saturation it is said to be on a minor loop.
High Q filters
A filter circuit (inductor and/or capacitor) that exhibits high Q. It is very frequency-sensitive and filters out or allows to pass, only those frequencies within a narrow band.
Magnetizing ForceCoercive
Force
Remanence
Flux Density
MaximumFlux DensityMaximum
Permeability
IntialPermeability
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Glossary of Terms
Impedance
The total opposition offered by a component or circuit to the flow of alternating or varying current at a particular frequency, including both the AC and DC component.. Impedance is expressed in ohms and is similar to the actual resistance in a direct current circuit. In computations, impedance is handled as a complex ratio of voltage to current. The ohm is the un i t o f impedance . Impedance i s t yp i ca l l y abbreviated as "z" or "Z". The frequency-invariant, real component of impedance is resistance. The f requency-var iant , imaginary component o f impedance is reac tance. The rec ip roca l o f impedance is admittance.
Inductance Factor (AL)
The inductance rating of a core in nanoHenries per turn squared (nH/N2) based on a peak flux density of 10 gauss (1 mT) at a frequency of 10 kHz. An AL value of 40 would produce 400H of inductance for 100 turns and 40mH for 1000 turns.
Initial Permeability
That value of permeability at a peak AC flux density of 10 gauss (1 mT).
Magnetic Energy
The product of the flux density (B) and the (de)magnetizing force (H) in a magnetic circuit required to reach that flux density.
Magnetostriction
The expansion and contraction of a magnetic
material with changing magnetic flux density. The saturation magnetostriction coefficient has the symbols. It is change of length divided by original length (a dimensionless number) and is measured at the saturation flux density. Magnetostriction causes audible noise if the magnetostriction is sufficiently large and the applied field is AC and in the audible frequency range, e.g. 50 or 60 Hz.
Mean Length Turn
The average length of a single turn in the winding of the device.
Oersted
The unit of magnetizing force in cgs units. One Oersted equals a magneto-motive force of one Gilbert per centimeter of path length. 1 Oersted = 79.58 A/m= 0.7958 A/cm
Percent Permeability (%)
Represents the percent change in permeability from the initial value.
Q factor
The Q factor or quality factor is a measure of the "quality" of a resonant system. Resonant systems respond to frequencies close to their natural frequency much more strongly than they respond to other frequencies. The Q factor indicates the amount of resistance to resonance in a system. Systems with a high Q factor resonate with a greater amplitude (at the resonant frequency) than systems with a low Q factor. Damping decreases the Q factor.
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Glossary of Terms
Search Coil
A coil inductor, usually of known area and number of turns, that is used with a fluxmeter to measure the change of flux linkage with the coil.
Single-Layer Winding
A winding for a toroidal core which will result in the full utilization of the inside circumference of the core without the overlapping of turns. The thickness of insulation and tightness of winding will affect results.
Surface Area
The effective surface area of a typical wound core available to dissipate heat.
Skin Effect
Skin effect is the tendency for alternating current to flow near the surface of the conductor in lieu of flowing in a manner as to utilize the entire cross-sectional area of tile conductor. The phenomenon causes the resistance of the conductor to increase. The magnetic field associated with the current in the conductor causes eddy currents near the center of the conductor which opposes the flow of the main current flow near the center of the conductor. The main current flow is forced further to the surface as the frequency of the alternating current increasing
Stored Energy
The amount of energy stored, in microjoules (10-6 joules), is the product of one-half the inductance (L) in microhenries (10-6 Henries), times the current (I)
squared in amperes.
Swing
A term used to describe how inductance responds to changes in cu r ren t . Examp le : A 2 :1 sw ing corresponds to an inductor which exhibits 2 times more inductance at very low current than it does at its maximum rated current. This would also correspond to the core operating at 50% of initial permeability (also 50% saturation) at maximum current.
Switch Mode Power Supply
A power conversion technique that involves breaking the input power into pulses at a high frequency by switching it on and off and re-combining these pulses at the output stage. Using this technique, an unregulated input voltage can be converted to one or more regulated output voltages at relatively high efficiencies.
Switching Frequency
The rate at which the DC input to a switching regulator is switched on and off.
Temperature rise
Change in temperature of a terminal from a no-load condition to full-current load. Also called T rise. (2) The increase in surface temperature of a component in air due to the power dissipation in the component. The power dissipation for an inductor includes both copper and core losses.
Estored = LI 221
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Temperature Coefficient
A factor which describes the reversible change in a magnetic property with a change in temperature. The magnetic property spontaneously returns when the temperature is cycled to its original point. It usually is expressed as the percentage change per unit of temperature.
Temperature Stabilization
After manufacture, many types of soft and hard magnetic materials can be thermally cycled to make them less sensitive to subsequent temperature extremes.
Winding Factor
The ratio of the total area of copper wire inside the center hole of a toroid to the window area of the toroid.
Window Area
The area in and around a magnetic core which can be used for the placement of windings.
Glossary of Terms
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