NaNOcRysTallINE
VITROPERM
EMc PROducTs
adVaNcEd MaTERIals – THE KEy TO PROGREss
NaNOcRysTallINE
VITROPERM
EMc PROducTs
VacuuMscHMElZE GmbH & co. KG (Vac)
is a leading global manufacturer of modern
magnetic alloys, cores and inductive compo-
nents. Vac has supplied innovative solutions
for electromagnetic compatibility (EMc) pro-
tection for more than 30 years.
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NaNOcRysTallINE VITROPERM / EMc PROducTs
VITROPERM :
extending the possibilities of iron
Nanocrystalline VITROPERM alloys are based on Fe with si and B with Nb and cu addi-
tives. Vac pioneered the development of rapid solidification technology resulting in the
production of thin tapes or ribbons approximately 20 μm thick. special slitting and core
winding machines produce tape-wound cores with external diameters ranging from 2
mm to 600 mm. a subsequent heat treatment at around 500 – 600 °c transforms the ini-
tially amorphous microstructure of the tape into the desired nanocrystalline state. This
being a two-phase structure with fine crystalline grains (average grain diameter of 10-40
nm) embedded in an amorphous residual phase.
VITROPERM nanocrystalline alloys are optimized to
combine highest permeability and lowest coercive
field strength. The combination of very thin tapes and
the relatively high electrical resistance (1.1 – 1.2
μΩm) ensure minimal eddy current losses and an
outstanding frequency vs. permeability behaviour.
Along with saturation flux density of 1.2 T and wide
operational temperature range, these features com-
bine to make VITROPERM a universal solution for
most common EMC problems and vastly superior in
many aspects to commonly used ferrite and amor-
phous iron materials.
Fig. 1: Rapid solidification technology is used to produce thin metal tapes with an amorphous structure (metallic glass).
Fig 2: Crystalline structure, amorphous structure, nanocrystalline microstructure
NaNOcRysTallINE VITROPERM / EMc PROducTs
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common mode
chokes &
tape-wound cores
Nanocrystalline cores are widely used in common mode choke (cMc) applications due to their unique
combination of properties. By utilising low-cost raw materials (Fe-based) and modern, large-scale pro-
duction, VITROPERM is a very competitive solution for a wide range of applications. Key areas of appli-
cation are:
• switched-mode
power supplies (sMPs)
• solar inverters
• Frequency converters
• EMc filters
• Welding equipment
• Wind generators
• Induction hobs
• automotive applications
• uninterruptable
power supplies (uPs)
Our CMCs feature high attenuation which is
maintained across a wide frequency range offe-
ring extremely broadband attenuation. In many
cases, this characteristic can allow a reduction
of the number of filter stages in multistage EMC
filter configurations to reduce complexity, cost
and filter volume. Ohmic (copper) losses are
also reduced increasing the efficiency and lowe-
ring component temperature.
standard 2-stage EMI-Filter Optimized 1-stage EMc-Fil-
ter with VITROPERM
NF stage
HF stage
Fig. 3: Nanocrystalline chokes allow a reduction of filter stages
VACUUMSCHMELZE has extensive practical and theo-
retical expertise in the design of CMCs and filter confi-
guration using nanocrystalline cores and components.
At higher frequencies, the winding configuration has a
major effect on the parameters of winding capacitance
and leakage inductance and is therefore carefully con-
sidered in our choke designs. Figure 4 shows a compa-
rison of insertion loss for two chokes which differ only
in their winding configuration (core material, number of
turns and wire thickness are identical in both cases).
This illustrates how our design expertise can improve
filter efficiency, maximize reliability and reduce costs.
50
40
insertion loss a
E
[dB]
(50 Ohm System)
1-phase CMC
Core: VITROPERM 500F
25 x 20 x 10mm
N = 2 x 28 turns
(0.71mm / AWG 21)
separator: 5 mm
HF optimized winding
design, C
w
= 4pF
16dB
30
20
simple winding
design, C
W
=21pF
10
0
0.001
0.01
0.1
1
10
frequency [MHz]
Fig. 4 : Optimized choke design: improved attenuation of up to 16 dB (or more) at 4 MHz.
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NaNOcRysTallINE VITROPERM / EMc PROducTs
Features & benefits
of VITRoPeRm
nanocrystalline chokes
• small size
• suitable for high currents
and/or high voltages
• single stage filter designs possible
High μ, high Bs
High μ, high Bs, suitable core geometries
Extremely broadband attenuation behaviour,
high permeability, low-capacitance design,
moderate reduction of μ up to high frequen-
cies, low Q-factor in 150 kHz range
Low number of turns required for high L,
reduction of filter stages
Low power loss, reduced use of material
High Curie temperature, material properties
(μ, Bs,
λ
nearly independent of temperature
s)
Material properties (μ, Bs,
λ
) nearly indepen-
s
dent of temperature, linear magnetization curve
delivers stable impedance across a broad
range of common mode currents – VAC choke
design software available
Suitable plastic materials meet UL1446 insula-
tion requirements
A range of μ levels and VITROPERM alloys
available
Material is practically magnetostriction-free
Material is practically magnetostriction-free,
coatings/casings are resistant against mecha-
nical stress
NaNOcRysTallINE VITROPERM / EMc PROducTs
• High efficiency, low power loss
• "Green“, environmentally friendly
• suitable for high and low ambient
temperatures and high operating
temperatures
• “Easy filter design”
• ul-compliant designs
• Optimized solutions for a variety
of different applications
• No operating noise
• Best suited for winding of thick wires
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