Electromagnetic interference control

Abstract: A study of electromagnetic wave propagation in buildings using a finite-difference time-domain algorithm has demonstrated that waves are incident on walls over a wide range of angles. If wall mounted frequency selective shielding is desired, it is argued that this behaviour requires shielding solutions that are angle insensitive. A simple single-layer annular ring frequency selective surface (which is relatively economic to fabricate) is shown to offer adequate angular stability of the transmission response, and is thus suitable for electromagnetic interference control in indoor wireless environments.

Abstract: One major task in developing electric cars is to control electromagnetic interferences (EMI) of their power train. Fast slew rates in power electronics increase efficiency, but also emitted radio frequency (RF) disturbances. One main approach to reduce EMI within automotive systems is a complete shielding of its high voltage (HV) power network. The shielding of HV power networks changes the system configuration from the used unshielded single core multi wire harness into a coaxial three conductor layout, and therefore the characteristic impedances of the entire power network. Re-cent research shows that line impedance stabilization networks (LISNs) for substitution of low voltage power networks (according to CISPR 25), are not ideal to measure conducted emissions of HV components because of changed characteristic impedances and additional shielding. This paper deals with a method of determining the high-frequency impedances of automotive HV power networks (300 kHz – 200 MHz). A Vector Network Analyzer (VNA) is used to measure Scattering-Parameters of different HV power cables. Matrix conversions allow calculating an impedance network, which is able to represent automotive HV-networks.

Abstract: A method of programming a switching mode power supply before or after the power supply is installed in a system to control electromagnetic interference. The switching mode power supply includes at least one switching device and a digital controller. The digital controller adjusts a switching frequency of the at least one switching device based on one or more programmable parameters. The method includes programming the digital controller with the one or more programmable parameters via a user interface. The programmable parameter(s) define a switching frequency adjustment to control electromagnetic interference.

Abstract: The electrical harness is an essential part of all the spacecraft. The prime contractors of spacecraft are especially active in efforts to optimize harness size and mass. The shielding of the harness for Electromagnetic Interference (EMI) control is an important element in this optimization, because cable shields and especially connector backshells have a significant mass impact. We present results of a recently finished study of the European Space Agency (ESA) conducted by a consortium of Astrium SAS, Ecole Polytechnique Federale de Lausanne (EPFL) and axon' cable. First some basic principles of harness shielding are recalled, then important test and simulation results are presented, followed by a brief summary of the derived guidelines on EMI control techniques for spacecraft harness. These guidelines also consider a trade-off with mass increase and implementation constraints.