Dickmann, Stefan

A dynamical impedance analysis of complex electrical aerospace systems during operation can provide detailed information for efforts to further enhance system stability and reliability. As conventional single-tone impedance measurements are relatively slow compared to possible system state changes, a pulsed method using a synthesised stochastic multitone signal is proposed. This method is validated for a passive permanent magnet synchronous motor through a result comparison with an RF I-V impedance measurement. Then it is applied to an active DC- DC converter to highlight the detection of impedance changes due to the switching of the involved transistors, impossible to detect with conventional impedance measurement methods. It will be discussed how this method can be further adapted to overcome currently existing practical limitations and how it can be optimised for other electrical systems of interest.

Maintaining compliance to electromagnetic compatibility (EMC) standards becomes an increasing challenge for the automotive industry in the course of the ongoing automation of vehicles. Novel extended design procedures and test standards are required to ensure safety of automated driving functions, particularly in an adverse electromagnetic (EM) environment. In order to keep the number of tests within a reasonable and practical limit, an evaluation framework based on virtual design methods and information drawn from legacy experiments and simulations can support the automotive industry. With this digital framework appropriate technological solutions can be identified during the pre-compliance phase and efficient experimental designs can be generated to ensure EMC compliance. Furthermore, such a framework paves the way for digital EMC twins of automated vehicles (AVs) considering the complex interrelations of AV’s (sub-)systems to accurately predict the behaviour of new AV functions in various EM environments. To this purpose, a cross-domain platform is being developed in this work as the backbone of such a virtual framework. It supports the handling, storage and processing of various datasets from EMC test campaigns, including (intentional) electromagnetic interference ((I)EMI) tests, as well as simulations of automotive devices-under-test (DUTs). The platform allows for the establishment of interconnections between various data sources and deeper analyses based on artificial intelligence (AI) methods to deduce EMC information for new developments, whilst maintaining traceability.

Hohe Anforderungen an die elektronischen Komponenten von Systemen der medizinischen Bildgebung können im Rahmen derer Energieversorgung nur durch den Einsatz von moderner Leistungselektronik erfüllt werden. Mit der Verwendung von Wide-Bandgap-Leistungshalbleitern, z. B. in Stromrichtern von Röntgensystemen, gehen damit schnellere Schaltvorgänge sowie hohe Schaltfrequenzen einher. Dies macht eine Untersuchung der Auswirkungen auf die Elektromagnetische Verträglichkeit (EMV) erforderlich. Das betrifft sowohl die Einhaltung von normativen EMV-Grenzwerten als auch die Wechselwirkung der parasitären Eigenschaften von Komponenten innerhalb eines Systems. Im Forschungsprojekt DiMoLEK werden messtechnische Untersuchungen durchgeführt und es wird ein Ansatz zur Modellierung der parasitären Eigenschaften von passiven Komponenten entwickelt. Die Simulation von Stromrichtern mit anschließender Analyse der Wechselwirkungen parasitärer Eigenschaften ermöglicht die Optimierung der (elektromagnetischen) Resilienz. Dies kann beispielsweise durch eine Anpassung des Designs der Komponenten und der Modulationsverfahren erreicht werden.

To guarantee the safe operation of switching devices and accomplish zero voltage switching (ZVS), it is crucial to determine the dead time in a half-bridge LLC resonant inverter. When the resonant inverter fails to meet the ZVS boundary, the voltage reversal occurs across the switching devices with high voltage/current transitions leading to the distortion event. This work provides the opportunity to investigate the electromagnetic compatibility (EMC) issues of the half bridge LLC resonant inverter in the context of varying dead time. Hardware results from an experimental setup demonstrate the impact of dead time distortion on the switching device and their correlation with EMC challenges, which are validated by measurements performed in an anechoic chamber.

Wide band gap semiconductors such as siliconcarbide (SiC)-based devices are favored in the power electronic industry for their reduced switching losses. However, their utilization leads to high d𝑉₍DS₎/d𝑡, causing high-frequency emissions that can affect the operation of connected devices and systems on the board net. This study investigates conducted emissions originating from the output lines of a laboratory adaptation of an automotive interleaved buck converter, interfacing the traction battery of an electric vehicle with 48 V board net, along with monitoring the chip temperature of the SiC MOSFET. Across various combinations of input and output characteristics and operation modes, differences in common and differential mode emission spectra and their comparison with CISPR-25 standard limits, are observed. A study is further done to analyze these experimental results.

Gallium Nitride (GaN)-based converters have emerged as a promising technology to increase the efficiency and power density of power electronic systems in electric vehicles (EVs). However, the integration of GaN semiconductor devices introduces challenges regarding electromagnetic interference (EMI). This work focusses on EMI measurements and on exploring the relationship between defined parameters such as output current or switching frequency and conducted emissions (CE) in converters with GaN switches. Moreover, the relationship between the switching transients of the GaN-FETs and the interference frequency range is examined and the challenges of using GaN-based converters in EVs related to EMI are discussed.

The use of wide-bandgap semiconductors in modern power electronics creates new challenges in EMC. These result, among other things, from high frequencies and steep switching slopes. In addition, parasitic elements of semiconductors, passive components and the printed circuit board can cause resonances, which become noticeable in oscillations. In this work, a possibility is presented to simulate resonances in a power electronic circuit. The circuit used is a series-LC resonant converter with SiC-MOSFETs. An impedance model of the resonant load is generated with consideration of parasitic elements. The accurate simulation is validated by comparison with time domain measurements. EMC measurements of conducted and radiated emissions are done. It is shown that the resonances lead to emissions which can be predicted using the time domain simulation.

In a modern vehicle, the automotive wire harness forms a crucial part of the sensor signal and power distribution system. It is thus important to understand the impact of electromagnetic interference on such harness, in particular its dependence on layout with respect to an incoming electromagnetic wave. The research presented here investigates the induced common-mode and differential-mode currents in various wire harness layouts, as well as the dependence on both grounding and on the harness design involving an unshielded twisted or untwisted pair. The results indicate that for harness layouts with a substantial component along the electric field directions, such current levels can reach up to those that disrupt automotive sensor communication.

In this paper, we present a filter circuit that can be used to prevent sensor disturbances caused by intentional electromagnetic interference (IEMI). Sensors are an increasingly important component in almost all electrical systems, and faulty sensor readings can cause major problems. We show that sensor disturbances can be caused by IEMI and that sensors with Inter-Integrated Circuit (I²C) interfaces are particularly susceptible to this type of interference. We present a filter circuit that can be connected directly to I²C sensors in order to prevent disturbances caused by IEMI. Through both simulation and experimental testing, the effectiveness of the filter in preventing errors in sensor readings without impacting the functionality of the I²C communication is demonstrated.