8/17/2019 02 Magnetic Materials.pdf
1/38
Magnetic Circuits (II)
8/17/2019 02 Magnetic Materials.pdf
2/38
Example 3
5% cross-section increase for
fringing in airgap
Find: (a) total reluctance of the flux path;
(b) current required to produce B = 0.5 T in the air gap;
(c) inductance of the coil.
µr =2000
Φ
8/17/2019 02 Magnetic Materials.pdf
3/38
Example 4
(1) How much is current required to produce 0.016Wb of flux in the core?
(2) What is core’s relative permeability at that current level?
(3) What is its reluctance and inductance at this level?
M5 Steel at DC
N = 400, A = 150 cm2
lc = 55 cm
Φ
8/17/2019 02 Magnetic Materials.pdf
4/38
Example 5
2221212
2121111
I L I L
I L I L
+=
+=
λ
λ ∞→
r µ
N 1 turns
g
N 2 turns 0g
g
g
Aµ =R
(1) Let I 2 = 0
∞→r
µ
N 1 turns
I 1
N 2 turns
Find self and mutual inductances.
(2) Let I 1 = 0
+ _ 11
I N
gR
Φ
∞→r
µ
N 1 turns
I 2
N 2 turns
+ _
22 I N
gR
Φ
8/17/2019 02 Magnetic Materials.pdf
5/38
Example 6
2221212
2121111
I L I L
I L I L
+=
+=
λ
λ
1g
2g
∞→r
µ
N 1 turns
I 1 N 2 turns
I 2
10
11
g
g Ag
µ =R
Find self and mutual inductances.
20
22
g
g Ag
µ =R
(1) Let I 2 = 0
ΦΦ 1gR
2gR
(2) Let I 1 = 0
⇒
ΦΦ
2gR
8/17/2019 02 Magnetic Materials.pdf
6/38
Why Use Airgap for Inductor? (1)
8/17/2019 02 Magnetic Materials.pdf
7/38
Why Use Airgap for Inductor? (2)
g =1 mm air gap
After opening an airgap
8/17/2019 02 Magnetic Materials.pdf
8/38
Magnetic Fringing (More Accurate)
gg R P /1= permeance
+++= gd w
g
wd g 308.0)(52.00µ P
8/17/2019 02 Magnetic Materials.pdf
9/38
Leakage Flux
8/17/2019 02 Magnetic Materials.pdf
10/38
Magnetic Materials
8/17/2019 02 Magnetic Materials.pdf
11/38
Hysteresis Loop for Ferromagnetic Materials
Br remnant flux or residue flux
H c coercive flux or coercivity
8/17/2019 02 Magnetic Materials.pdf
12/38
Magnetization Curves for Hard Materials (I)
8/17/2019 02 Magnetic Materials.pdf
13/38
Magnetization Curves for Hard Materials (II)
1T = 10 kGauss, 1A/m = 0.01257 Oe or 1 Oe = 79.6 A/m
8/17/2019 02 Magnetic Materials.pdf
14/38
From Yeadon – Handbook of Small Electric Motors
Hard Magnetic Material Properties
8/17/2019 02 Magnetic Materials.pdf
15/38
Hard Material Circuit Analysis (1)
Load line:
Device line: Bm=( Br /H c)( H m+H c)= µ 0µ r H m +Br
mmm d H =F g H gg =F
0=+ gm F F
0=+ g H d H gmm
mm
g H g
d H −=
m
m
gg
H g
d H B
00
µ µ −==
md
B
+
_
mF
Actual direction of H m
g
gr B
c H − m H
gm B B =
H
B
cross section area Am
cross section area Ag
∞→µ
mmgg A B A B ==ΦFrom
m
g
gm A
A
B B =⇒ From magnetic circuit
m
m
gmm
H A
A
g
d B
0µ −=
8/17/2019 02 Magnetic Materials.pdf
16/38
Hard Material Circuit Analysis (2)
mm
g H g
d
B 0µ −=
gr B
c H − m H
gm B B =
H
H
mmgg A B A B ==ΦFromg
mmg
A
A B B =⇒
From )(002
mm
g
mmgmmg B H gA
Ad B H g
d B −=−=⇒ µ µ
magVol
gapVol2
0
gap
mag)(
VolVol g
mm
B B H −
=⇒µ
The required volume of magnet can be minimized by operating the magnet at
the point of maximum BH (or energy) product.
Device line: Bm= µ 0µ r H m +Br
md
B
+
_
mF
Actual direction of H m
g
cross section area Am
cross section area Ag
∞→µ
maximum BH product
8/17/2019 02 Magnetic Materials.pdf
17/38
Maximum Energy Point
B
H c H −
r B
r m m r
c
B B H B H
= + 2r
m m m r m
c
B B H H B H H
⇒ = +
max
( )To get (- ) 0 ,
2 2
m m cr m m m m
m
B H H B B H B H
H
∂⇒ = ⇒ = = −
∂
m H
m B
8/17/2019 02 Magnetic Materials.pdf
18/38
Soft Magnetic Materials
Ferrite materials Carbon steels
Silicon steels
High saturation alloys
Amorphous ferromagnetic alloys
Soft magnetic powder composites
Nanostructured materials
8/17/2019 02 Magnetic Materials.pdf
19/38
Soft Magnetic Material Properties
From Yeadon – Handbook of Small Electric Motors
8/17/2019 02 Magnetic Materials.pdf
20/38
Ferrite Materials (1)
3C81 is from Philips, USA.
Philips Components , 3C81Material Grade Specification, 1997
8/17/2019 02 Magnetic Materials.pdf
21/38
Ferrite Materials (2)
3F3 is from Philips, USA.
Philips Components , 3F3Material Grade Specification, 2000
8/17/2019 02 Magnetic Materials.pdf
22/38
Ferrite Materials (3)
4F1 is from Philips, USA.
Philips Components , 4F1Material Grade Specification, 2000
8/17/2019 02 Magnetic Materials.pdf
23/38
Carbon Steel 1008
www.eng-tips.com Magnetic Engineering Forums
Maxwell SV Software
http://www.eng-tips.com/http://www.eng-tips.com/
8/17/2019 02 Magnetic Materials.pdf
24/38
Carbon Steel 1010
www.eng-tips.com Magnetic Engineering Forums
Maxwell SV Software
http://www.eng-tips.com/http://www.eng-tips.com/
8/17/2019 02 Magnetic Materials.pdf
25/38
Carbon Steel 1018
www.eng-tips.com Magnetic Engineering Forums
Maxwell SV Software
http://www.eng-tips.com/http://www.eng-tips.com/
8/17/2019 02 Magnetic Materials.pdf
26/38
Nonoriented Silicon Steel
J. F. Gieras, Advancements in Electric Machines, Springer, 2008.
M-19 means core losses shall be below 1.9 W/lb at 1.5 T and 60 Hz.
Fe-Si alloys with random orientation of crystal cubes and practically have the same
properties in any direction in the plane of the sheet.
Armco M-19
8/17/2019 02 Magnetic Materials.pdf
27/38
Armco M-27, 36 and 43
8/17/2019 02 Magnetic Materials.pdf
28/38
High Frequency Electric Steel (1)
To reduce core loss, laminations with thin gauges are manufactured.
ArnonTM 5 is from Arnold Magnetic Technologies Corp., Rochester, NY, USA.
8/17/2019 02 Magnetic Materials.pdf
29/38
High Frequency Electric Steel (2)
Cogent Power Ltd ., Newport, UK. www.cogent-power.com
J. F. Gieras, Advancements in Electric Machines, Springer, 2008.
8/17/2019 02 Magnetic Materials.pdf
30/38
High Saturation Alloys
Fe-Co alloys with Co contents from 15 to 50% have the highest known
saturation flux density and highest Curie temperature of any alloy family..
Hiperco50 is from Carpenter , USA.
8/17/2019 02 Magnetic Materials.pdf
31/38
Hiperco50 Core Loss
8/17/2019 02 Magnetic Materials.pdf
32/38
Vacoflux50 B-H curveVacoflux50 is from Vacuumschmelze, Hanau, Germany.
8/17/2019 02 Magnetic Materials.pdf
33/38
Amorphous Ferromagnetic Materials (1)
J. F. Gieras, Advancements in Electric Machines, Springer, 2008.
www.ammtechnologies.com
8/17/2019 02 Magnetic Materials.pdf
34/38
Amorphous Ferromagnetic Materials (2)
8/17/2019 02 Magnetic Materials.pdf
35/38
Soft Magnetic Powder Composites (1)
Soft magnetic powder composites are composed of iron powder, dielectric
(epoxy resin) and filler (glass or carbon fibers) for mechanical strengthening.
Accucore from TSC Ferrite International, Wadsworth, IL. www.tscinternational.com
8/17/2019 02 Magnetic Materials.pdf
36/38
Soft Magnetic Powder Composites (2)
SomaloyTM 500 from Höganäs, Sweden.
8/17/2019 02 Magnetic Materials.pdf
37/38
Soft Magnetic Powder Composites (3)
SomaloyTM 500 from Höganäs, Sweden.
8/17/2019 02 Magnetic Materials.pdf
38/38
Soft Magnetic Nanocrystalline Composites
Recommended