Martin Maerz

• Prof. Dr.-Ing.
• Director of the Institute for Power Electronics at Friedrich-Alexander-University Erlangen-Nürnberg

Vorlesungsunterlagen - aktualisiert für WS 2023/24

Unterlagen zur Vorlesung "Thermisches Management in der Leistungselektronik" an der Universität Erlangen-Nürnberg

Lecture notes - Summer 2022

This paper presents a fast numerical calculation method of realistic power losses for high frequency litz wires. Explicitly, the imperfect structure of litz wires is considered when calculating losses due to an excitation current (skin losses) and external magnetic fields (proximity losses). Calculations of litz wires with more than 1000 strands we...

Unterlagen zur Vorlesung "Grundlagen der Leistungselektronik" im WS 2024/25

Soft-switching in power converters offers a highly attractive solution to enhance system efficiency by reducing switching losses and mitigating electromagnetic interference. This article introduces a novel three-level soft-switching inverter topology based on the Auxiliary Resonant Pole (ARP), which is a modification of the well-known Auxiliary Res...

The elbow dislocation is the second most common human dislocation. In case of an injury, a fast and correct diagnosis is essential for a good convalescence. The diagnosis depends on the attending doctor's experience and is sometimes subjective. A technical device should assist the doctor during the first and follow-up examination to eliminate this...

Soft-switching in power converters offers a highly attractive solution to enhance system efficiency by reducing switching losses while also mitigating electromagnetic interference. Although zero-voltage switching (ZVS) significantly reduces switching losses, it does not eliminate them. Considerable turn-OFF losses remain, dependent on transistor pa...

Early wildfire detection is critical for effective suppression efforts, necessitating rapid alerts and precise localization. While computer vision techniques offer reliable fire detection, they often lack contextual understanding. This paper addresses this limitation by utilizing Vision Language Models (VLMs) to generate structured scene descriptio...

Galliumnitride (GaN) high electron mobility transistor (HEMT) and silicon (Si) Metal-Oxide semiconductor field effect transistor (MOSFET) power devices exhibit greatly reduced conduction losses at cryogenic temperatures. Consequently, cryogenic cooling is currently largely investigated in aviation research. However these temperatures lead to a hith...

In this paper, a decentralized self-stabilizing Energy Management System for undersupplied EV charging parks is presented. This undersupply is due to the maximum power demand from all charging stations connected to a common DC grid being larger than the maximum infeed power from AC mains. The EMS allows easy addition of additional participants such...

This paper introduces an innovative non-destructive device designed to detect and limit short-circuit currents in LVDC grids. The proposed solution utilizes a transformer fully saturated by a permanent magnet during normal operation. When a short-circuit condition occurs, the transformer desaturates, reducing the rise in current and triggering the...

This study provides a comprehensive characterization of various isolated single and half-bridge gate drivers over the entire temperature range from room temperature down to −194 °C. Unlike previous studies, which primarily focused on electrical output parameters such as rise/fall times and propagation delays, this paper also explores critical funct...

The ongoing progress in the field of wide bandgap (WBG) devices enables new topologies and unmatched power density in high-power dc–ac converters. However, the still high cost of WBG devices, such as silicon carbide (SiC) MOSFETs, continues to hinder their widespread adoption in commercial converters. To address this challenge, emerging hybrid topo...

The parallel connection of Si-IGBTs and SiC-MOSFETs in a so-called hybrid switch offers new degrees of freedom to optimize the efficiency of bridge-type inverters and converters. By separately controlling the parallel devices with a gate delay, the switching performance can be improved to resemble that of the superior MOSFET. It is known that the o...

Early wildfire detection is critical for effective suppression efforts, necessitating rapid alerts and precise localization. While computer vision techniques offer reliable fire detection, they often lack contextual understanding. This paper addresses this limitation by utilising Vision Language Models (VLMs) to generate structured scene descriptio...

This study provides a comprehensive characterization of various isolated single and half-bridge gate drivers over the entire temperature range from room temperature down to -194 °C. Unlike previous studies, which primarily focused on electrical output parameters such as rise/fall times and propagation delays, this paper also explores critical funct...

This paper investigates a generalized modeling approach for DC grid components by applying it to the simulation and analysis of a comprehensive DC grid system. The approach has been introduced in previous works, which discussed the overall objectives, scope of application and the modeling methodology for switched-mode power converters. However, a s...

This paper investigates the simulative approximation for simplifying the complex random particle arrangement within a soft magnetic composite (SMC) material by cubic atomic lattice structures. The implemented 3D finite element model (FEM) can calculate the relative permeability of different particle arrangements in the form of a geometric replicati...

In this paper, the methodology for creating models of power electronic converters based on a recently presented simulation approach for LVDC grids is discussed. This analysis-use-case dependent modeling approach defines three complexity levels for the component models to be used for specific evaluation cases. The theoretical basics and conventions...

This paper proposes a simulation-based planning concept and a simulation architecture for the design of hybrid AC/DC grids, which have the potential to significantly contribute to the energy transition. The paper discusses the lack of knowledge for the design of these grids, and presents a simulation approach to efficiently design hybrid grids and...

Using soft-switching, the efficiency and EMI performance of power inverters for drive and grid applications can be improved. An advantageous topology is the well-known auxiliary resonant commutated pole (ARCP) inverter. The novel single shared inductor S²I-ARCP is a modification of the conventional ARCP which saves two resonant inductors in the aux...

This study provides an overview of the energy demand of a regional airport, divided into individual time horizons. The electrification of aircraft systems raises the question of whether airports will be among the largest electricity consumers in our infrastructure in the future. Sustainability and especially emission reductions are significant chal...

Low-voltage direct current networks play a central role in the realization of a sustainable, resilient energy supply. The stabilization of the networks during design and operation of the grids is a particular challenge since more and more components must be included in the stability analysis and control. Therefore, it is desirable to increasingly a...

Paralleling silicon carbide metal-oxide semiconductor fieldeffect transistors in multichip power switches is a common way to achieve the required current rating in high power converters. The parasitic inductances, the static and dynamic current imbalance of the paralleled MOSFETs are limiting the maximum current and switching speed of the devices....

This research derives analytical switching and conduction loss expressions for three-level WBG Neutral Point Clamped (NPC) inverters that include third quadrant operation of unipolar semiconductors and dead time states for different PWM strategies. Special attention is drawn to the topological influence on the switching energies, as it leads to add...

Soft-switching in power inverters for drive and grid applications can both enhance the efficiency by reducing switching losses and improve EMI due to lower switching speeds with their associated dv/dt. An advantageous topology is the well-known auxiliary resonant commutated pole (ARCP) inverter. The development of such power electronic inverters of...

This paper proposes a simulation-based planning concept and a simulation architecture for the design of hybrid AC/DC grids, which have the potential to significantly contribute to the energy transition. The paper discusses the lack of knowledge in the market for the design of these grids, and presents a simulation approach to efficiently assemble h...

The increasing adoption of direct current (DC) systems, driven by renewable energy sources and diverse DC loads, highlights the need for efficient fault protection mechanisms. This research paper presents a cost-effective and compact 500A electric drive system specifically designed for an axial flux machine-based actuator in a hybrid DC breaker app...

This paper comprises a complete reverse engineering of a Toyota Mirai. The hydrogen system of this commercial fuel cell vehicle (FCV) was comprehensively analysed. The level of consideration includes all non-destructively accessible aspects such as mechanical design principles, functional analyses, and material and component selection up to the int...

High-power requirements of ultra-fast charging stations and the uptake of many low-power charging stations give rise to special challenges when designing smart charging infrastructure. In support of Europe's 2030 climate targets, the EU-funded PROGRESSUS project aims to propose a next-generation smart grid demonstrated by the application example of...

Keeping touch & leakage currents within the tough regulation limits is a very ambitious goal for non-isolated EV-chargers, affecting the entire system setup (topology, PWM, filter). This paper improves the scope of a timesaving analytical touch current calculation method by expanding the modeling from a single-stage to a two-stage power electronic...

Hydrogen storage in liquid organic hydrogen carriers (LOHC) enables the utilization of renewable energy in different sectors. In this paper, we describe the operational experience with one single LOHC system for bidirectional electrical energy storage at the kW scale. The system includes a reactor for the hydrogenation and dehydrogenation of LOHC,...

Supplementary Material to ”Operational experience with a liquid organic hydrogen carrier (LOHC) system for bidirectional storage of electrical energy over 725 hours”

Power electronics is a hotly debated and acutely researched topic for transitioning to sustainable aviation. Power electronic systems convince with high power densities and ensure the most efficient operation of the individual components in a hybrid-electric aircraft. This paper presents the first detailed considerations for exploring the drive inv...

Galvanisch nicht getrennte Ladesysteme bieten Vorteile bezüglich des Gewichts, der Kosten und Effizienz, da sie keinen Transformator benötigen. Andererseits weisen diese Systeme erhöhte Berührströme auf Grund der starken Erweiterung des Common Mode (CM) Koppelpfades durch die Y-Kapazitäten des E-Fahrzeugs (EV) auf. Deren treibende Quelle ist die CM...

The transition to sustainable aviation plays a crucial role and can be managed by power electronics. The Clean Sky 2 project GENESIS addresses the environmental sustainability of hybrid-electric 50-passenger (PAX) aircraft systems in a life cycle perspective to support the development of a technology roadmap for the transition to sustainable and co...

Electric propulsion systems are considered one possibility to reach the ambitious goals of the European Union's Flightpath 2050 concerning greenhouse gas emissions and noise. This paper proposes an engineering architecture design of an electric motor for a propulsion system in a hybrid-electric regional aircraft. The project partners defined the pe...

Transforming air traffic from fossil fuels to sustainable air traffic poses new challenges for airports. The charging infrastructure and aircraft fueling at future airports must also adapt to sustainable, electric aviation. This paper presents a MATLAB Simulink model of a future airport using data from a regional airport. This model simulates the i...

This Paper investigates the magnetic integration of a resonant push-pull converter operated at a switching frequency in the high frequency (HF) range (3-30 MHz). Based on the requirements arising from circuit considerations, a magnetic structure is derived that is suitable for integrating all the necessary inductive elements into one single compone...

Sustainability and, especially, emission reductions are significant challenges for airports currently being addressed. The Clean Sky 2 project GENESIS addresses the environmental sustainability of hybrid-electric 50-passenger aircraft systems in a life cycle perspective to support the development of a technology roadmap for the transition to sustai...

An online update routine (OU-Routine) is presented to determine the optimal parameters of a PID-PI cascade control using a genetic algorithm to improve the transient response of an isolated and bidirectional dc-dc converter. The effects of the cascade control parameters on the behaviour of the converter are analysed in this study. The parameters ar...

One of the key-enabling technologies of low inductive low voltage direct current (DC) systems is a breaker that can interrupt fault currents in less than a millisecond to avoid large fault currents. In this paper, the interruption capability of a hybrid breaker’s solid-state branch is analyzed with and without a resistive-capacitive-diode (RCD) snu...

In common understanding, the fast switching speed of wide-bandgap devices leads to high overvoltage and oscillations, if no countermeasures are taken. Those countermeasures were introduced in the past, and include methods such as build-in gate resistors or low-inductive power modules. There is, however, a physical limit for reducing the parasitic i...

In recent years, research on Wireless Power Transfer and Switch Mode Power Supplies with a capacitive coupling link has been on the rise. Whereas many researchers investigate resonant coupling links, often resulting in tough requirements for the involved inductors, this paper focuses on the elimination of all inductive components in the coupling li...

The efficiency improvement of a Si-MOSFET and GaN-HEMT synchronous buck converter at low temperatures is demonstrated and discussed in detail. By carefully selecting suitable components for cryogenic temperatures and characterizing them from room temperature to low temperatures, the functionality of each component is demonstrated before cryogenic o...

Effective capacitive wireless power transfer systems often rely on high frequency power converters and incorporate a resonant coupling link. The input capacitance of a bridge rectifier alters the overall power transfer of a DC-DC converter with a series-resonant transfer link. Most analytic converter models in this field are based on a representati...

Keeping touch & leakage currents within the tough regulation limits is a very ambitious goal for non-isolated EV-chargers, affecting the entire system setup (topology, PWM, filter structure). This paper improves a time-saving failure current prediction method in common mode domain by investigating the influence of non-ideal passive component models...

This paper proposes a novel DC grid component that supplements conventional DC circuit breakers with a pre- and discharging functionality, thereby replacing conventional electromechanical solutions including lossy, bulky, and fault-prone pre- and discharging resistors. To reduce operational costs and energy consumption, this article proposes a bidi...

This article presents the design of a cost effective and easy-to-manufacture cooling chamber for the characterization of power electronics as well as passive and active electronic devices and materials from room temperature to cryogenic temperatures. The chamber is cooled with liquid nitrogen and uses the principle of a wind tunnel, which enables f...

The impact of real sintering structures on the macroscopic stress state and yield locus of sintered silver was investigated and a novel continuum modelling approach that predicts the macroscopic properties in an accurate, simple and efficient way was derived. Focused-Ion-Beam (FIB) tomography was utilized to study silver films, which were sintered...

In situ TEM utilizing windowed gas cells is a promising technique for studying catalytic processes, wherein temperature is one of the most important parameters to be controlled. Current gas cells are only capable of temperature measurement on a global (mm) scale, although the local temperature at the spot of observation (µm to nm scale) may signifi...

In this work, a resonant push-pull dc-dc converter suitable for switching frequencies in the MHz-range is investigated. Despite a simple design procedure with no need of multi-resonant tuning, the converter topology is capable of providing a constant output current over a wide output voltage range in unregulated operation. Based on an analytical so...

This article presents an investigation of the profitability of cryogenic power electronics at different cooling and ambient temperatures. Thermodynamic fundamentals of low-temperature refrigeration processes are considered and the Carnot efficiencies of state-of-the-art refrigerators are evaluated in order to establish the necessary power loss redu...