What do electromagnetic filters do

EMC - How to attenuate unwanted interference signals

The future definitely belongs to electromobility. The automotive industry as a technology driver par excellence still has a few hurdles to overcome. These include, for example, electromagnetic compatibility, which has so far hardly been mentioned in public.

Companies on the topic

The social and political pressure to reduce CO2 emissions is an ideal catalyst for the successful and rapid spread of electric vehicles. There is no doubt that electric vehicles will one day surpass combustion engines in terms of number and importance. But they too are not free from technical problems that still need to be solved. The questions of the availability and ecologically justifiable degradability of the raw materials for the batteries should be mentioned here as examples, or to the same extent the charging infrastructure that has so far been inadequate.

In the public eye - specialists know what it is all about - the topic of electromagnetic compatibility, on the other hand, has so far been almost undiscussed. Where a current flows, an electromagnetic field is created. And electricity is omnipresent in electric vehicles. Powertrain components in particular are sources of unwanted electromagnetic emissions. Possible negative effects on other, possibly safety-relevant electronic systems (both on- and off-board) and not to forget the vehicle occupants are to be avoided as far as possible.

High field strengths

In view of the very high currents occurring in electric vehicles, manufacturers are confronted with correspondingly high magnetic field strengths. This is where the high-voltage on-board network with 400 VDC to 1000 VDC meets the 12 VDC network. The currents in the vehicle can reach up to 500 A. The main source of interference is usually the converter that drives the motor. But there are many other sensitive systems that both emit interference and react very poorly to them. The battery management system, for example, which is used to monitor, regulate and protect the battery packs. Or the entire on-board electronics with all their electronic helpers, to which we entrust our lives in some cases (ABS, ESP, etc.). Electric vehicles are packed with highly integrated, highly clocked electronics.

Experts who are committed to electromagnetic compatibility - measurement technology manufacturers, EMC service providers, test laboratories, material developers and automotive suppliers - expect the potential for interference from electromagnetic fields to double every two years due to the increasing number and density of electronic modules in cars. And one more point should be mentioned: in an electric vehicle there are always adults, children or other living beings. The potentially negative impact of electromagnetic radiation on them may be controversial, but it is undeniably there. Think of an adult with a pacemaker, for example.

What should I do?

There are a number of ways and means of countering electromagnetic interference. The layout of the cabling, for example, its shielding, etc. To list them all would lead too far. We want to limit ourselves here to the use of external EMC filters. But what do such filters do? By means of passive components (chokes and capacitors), the unwanted interference signals are attenuated many times over in terms of their intensity, so that their harmful effect does not materialize.

Automotive = highest requirements

In contrast to some industrial or medical technology filters, the requirements in the automotive sector are much tougher. Such a filter must be particularly robust. Robust against vibrations, knocks and shocks. Robust against large temperature fluctuations when you drive out of the heated garage in winter. But it also has to be light and compact in order to take up as little space as possible and not make the vehicle unnecessarily heavier.

The latest FPAB filter series is tailored to these needs and, as is customary at SCHURTER, can be customized. With this single-stage filter, great importance was attached to robustness and impermeability to dust and moisture. Thanks to the use of a high-density plug from the US manufacturer Tyco, which is popular in the automotive industry, it is particularly light and universally applicable. All connections are screwed to withstand even the most stubborn vibrations.

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