0

10

20

30

40

50

0.001

0.01

0.1

1

10

frequency [MHz]

1-phase CMC

Core: VITROPERM 500F

25 x 20 x 10mm

N = 2 x 28 turns

(0.71mm / AWG 21)

separator: 5 mm

simple winding

HF optimized winding

16dB

NF stage

HF stage

standard 2-stage EMI-Filter Optimized 1-stage EMc-Fil-

ter with VITROPERM

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.

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.

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:

common mode

• switched-mode

power supplies (sMPs)

• solar inverters

• Frequency converters

• EMc filters

• Welding equipment

• Wind generators

• Induction hobs

• automotive applications

• uninterruptable

power supplies (uPs)

Fig. 3: Nanocrystalline chokes allow a reduction of filter stages

Fig. 4 : Optimized choke design: improved attenuation of up to 16 dB (or more) at 4 MHz.

chokes &

tape-wound cores

4

NaNOcRysTallINE VITROPERM / EMc PROducTs