We have seen a significant increase in the number of electronic components and systems in the automotive industry during the last decade.
Electromagnetic Compatibility (EMC) has become a key and sensitive topic for both automotive OEMs and their suppliers. EMC describes the ability of electronic and electrical systems and components to work correctly when they are close together.
Car manufacturers working with their suppliers not only need to ensure that electromagnetic problems will not occur when integrating the components and systems in the car, but also to fulfil the related EMC regulations.
Automotive EMC standards are mainly developed by the ISO, CISPR and SAE and apply to components and systems. Some government organisations are regulating these standards and OEMs may also have their own standards, but typically both of them refer to the ISO or CISPR standards. Within EMC we refer to Electromagnetic Interferences (EMI) which are the undesired emissions of a component or system, and to Electromagnetic Susceptibility or Immunity (EMS) when referring to how immune a component or system is to external electromagnetic interferences. Depending on the nature of the electromagnetic signal we can also refer to radiated or conducted interferences (or emissions).
Today’s vehicle development process is changing from measurement driven to simulation driven due to factors such as fewer hardware prototypes being available and less time for measurement and testing. As a result a lot of attention is placed on EMC simulation of emissions and immunity at both vehicle and component level. For a given EMC problem one has a source, a coupling path and a victim.
FEKO is helping automotive OEMs and their suppliers to perform electromagnetic simulations of EMC for analysis, design and validation purposes for both emissions and immunity. FEKO’s wide set of hybridized solvers, together with the integrated cable modelling tool and its MTL and combined MoM-MTL algorithms, allows the efficient analyses of EMC problems involving cables. Such cables radiate through imperfect shields and cause coupling into other cables, devices or antennas. They can also receive external electromagnetic fields, causing disturbance voltages and currents which potentially result in a malfunctioning of the system. Users are also modeling and simulating EMC chambers with FEKO, as well as for the simulation of electric and magnetic shielding of structures and housings, electromagnetic pulses (EMP), lightning effects and High Intensity Radiated Fields (HIRF).
Electronic Control Units (ECUs) are the units controlling one or more of the electrical systems and sub-systems in a vehicle, like the powertrain, infotainment, chassis and climate control. The number of ECUs in modern cars is increasing substantially, while the potential EMC issues in the vehicles need to be mitigated. In FEKO, users can simulate how emissions of ECUs are being coupled into other devices, like cables and antennas. More in detail, from FEKO Suite 7.0 release users can import near fields of Printed Circuits Boards (PCBs) of ECUs simulated with tools like SigrityTM analysis tools from Cadence ®(it is also possible to import measured fields). FEKO imports these fields, and using model decomposition, creates an equivalent source for such ECU. That equivalent source is then used for a high level EMC simulation in the vehicle.
Fig.1 shows an example with one equivalent source (related to the simulated near fields of a real 4-layer PCB provided by Cadence Design Systems) in a vehicle together with a cable harness and windscreen antenna. FEKO computes the coupling between the ECU, cables and the antenna. Users can include as many ECUs as necessary in the model. This approach is being followed by FEKO users to perform EMC radiated emissions analysis of ECUs at a vehicle level.
On the other hand, FEKO is also being used by automotive OEMs for the simulation of EMC immunity at a vehicle level. EMC immunity is key for applications like safety systems and autonomous cars. As an example of real use case, FEKO is used for the simulation of the automotive immunity tests according to the ISO 11451-2 substitution method.
In Fig. 2 one can see the model of a sedan in FEKO and the considered simulation cases, where all eight antennas are simulated in a single run but the results are considered for each antenna separately.
In Fig. 3 there is the comparison between measurements and FEKO simulations for one of the considered positions, i.e. P10, and when considering the transmitting antenna polarized vertically and placed in front of the vehicle (Front – Vertical). In the measurements two log-periodic antennas were used. The first one from 20 MHz to 200 MHz, and the second from 200 MHz to 1 GHz.
In the simulation a set of six dipoles represented each antenna in Fig. 2, and the size of the dipoles were changed depending on the frequency band. To obtain comparative results the simulation and measurement data were normalized with their calibration values, respectively (E/Ecal). The comparative study between simulations and measurements shows a nice agreement up to 450 MHz, and for higher frequencies, there are some differences between simulation and measurement results caused by the effect of non-metallic parts of the structure that are not represented in the simulation model.
More detailed information can be found in reference M. Klingler, S. Benhassine & Y. Merle, “Comparisons Between Time-Domain and Frequency-Domain Simulations Applied to an Entire Vehicle – Workshop presentation – 9th International Symposium on Electromagnetic Compatibility”, EMC Europe 2010, Wroclaw, Poland, 13-17 September 2010.
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