Current sensors based on PCB-integrated Rogowski coils offer a low-cost, high-performance solution, but are often optimized towards a narrow frequency band. To accurately reproduce both high frequency switching, as well as low frequency components in order to minimize droop issues, very broadband measurement is required. This work presents an improved PCB Rogowski coil current sensor for rectangular conductors, which utilizes distributed series and parallel resistors to dampen parasitic resonances and extend the bandwidth in the high frequency range with negligible impact to gain. Combined with advanced integration circuitry including a low frequency feedback loop, flat gain spanning more than six decades is achieved, enabling usability for very fast switching transients with long pulses containing low-frequency contents. The circuitry also enables DC restoration of the signal, making the sensor both useful for transient and steady-state measurements.

This research presents a comprehensive experimental analysis of the switching behavior and a system-level loss assessment of a SiC/Si-hybrid sparse neutral point clamped (SNPC) inverter. By reducing the number of switches compared to conventional three-level topologies, the SNPC inverter offers a promising solution for compact and cost-effective inverters. A complete three-phase hardware prototype is employed to investigate transient switching behavior across conventional and hybrid semiconductor configurations. The resulting data are used to assess the benefits of hybrid configurations in detail by comparing chip-area-optimized variants for a 25 kW inverter for the first time. The results show that the hybrid configuration achieves superior efficiency over a wide operating range, reducing losses by up to 42 % compared to the Si-based reference.

It has been demonstrated that transient effects may occur in SiC MOSFETs, when the virtual junction temperature (Tvj) is measured by the body-diode VSD(T)-method. This has the potential to result in an erroneous estimation of Tvj in power cycling tests (PCT) and overestimation of the device’s lifetime. This work focuses on the influence on the off gate voltage and temperature on the transient effect through a comprehensive parameter study involving 2880 test runs with twelve SiC MOSFETs from three manufacturers. The results demonstrate that the transient effect is strongly dependent on the manufacturer therefore presumably respectively on the device design and processes. It can be significantly reduced by applying a negative gate voltage (VGS,off) during the cooling phase. While manufacturers A and B can achieve complete compensation, the effect persists for manufacturer C. The study recommends extending the allowable datasheet values for VGS,off in PCTs to ensure more accurate temperature measurements. Future investigations are planned to analyse the effects at cryogenic temperatures.

Silicon Carbide (SiC) MOSFETs are prone to a thermal runaway type failure in the power cycling test. This leads to a possible change of failure mode and may cause overestimation of power cycling lifetime using empirical models. This work examines the thermally stable operation of SiC MOSFETs in the power cycling test. A criterion for stable operation is proposed and applied to sample data. A method to assess stability form datasheet values and power cycling data without the need for special measurements is given.

By using an integrated, galvanically isolated, separated buck/boost topology (short iisb(exp 2) topology) a high efficiency 48 V to 1 V Point of Load (PoL) unit is demonstrated. This paper describes why the proposed topology can be even useful in typical non-insulated DC/DC applications, like processor supplies by deducing the proposed topology from the well-known single stage hard-switched half-bridge with current doubler rectifier topology. Moreover, it will be shown why the special requirements for processor PoL applications can be easier fulfilled by the proposed topology.

This paper presents the approaches and results of the design for a multi-phase electric machine with hairpin winding for hybrid electric aviation applications. Various permanent magnet synchronous machine variants were designed and compared via FEM simulation, achieving up to 750 kW power and over 8 kW/kg power density with 95 % efficiency in motor mode. To reach the 750 kW power rating, a multi-phase design was used to enable split connection with four individual inverters. Unlike other aviation applications using concentrated winding, this design employs distributed winding due to the high rotational speed requirement of up to 21000 rpm. The motor-inverter system aims to maintain a current profile with low harmonic content at a maximum switching frequency of 30 kHz, minimizing inverter and machine losses. Hairpin winding and oil cooling are implemented to enhance power density. Each stator slot contains an uneven number of windings to reduce thermal loading and maintain temperatures below 180 °C. The design involves four inverter connections, which create four decoupled electromagnetic systems. The influence of the design variants on the eddy current losses is discussed.

In this article, an approach to balance the State of Charge (SoC) of two batteries connected to the DC bus of a fuel cell (FC) electric aircraft by Droop-controlled converters is described. The proposed algorithm is based on shifting the Droop reference voltages and prevents the simultaneous charging and discharging of the batteries. This approach is not only practical but also highly versatile, as it is compatible with all converters as long as the Droop voltage can be changed remotely, and a current measurement is provided to a central controller. No further programming access to the DC/DCs is necessary. There is no need for nonlinear or different-valued Droop resistances for charging and discharging. The balancing approach is validated via simulation in MATLAB/Simulink 2024a.The results show that the proposed approach achieves SoC balancing without degrading the dynamic performance of the grid. The delays added by the slower communication with the central controller have a minimal impact on performance.

High-voltage power electronics, utilizing wide-bandgap devices, can realize superior efficiency and power density designs compared to silicon-based power electronics. The fast switching transitions of those devices lead to higher overvoltage peaks and voltage oscillations. Zero Overvoltage Switching (ZOS) combines the fast switching speed of wide-bandgap devices with the prevention of voltage oscillations. This paper examines the advantages of ZOS through the example of a dc-dc converter. It presents a simulation method that simulates the channel current inside the transistor, allowing further analysis of the resulting switching losses. For the first time, a comparison of switching losses is possible between a converter that applies ZOS and a conventional switching converter. The difference in switching losses is reflected in the efficiency difference measured on a 30 kW dc-dc converter prototype. Under identical operating conditions, ZOS achieves 47.4% lower losses at full load compared to the conventional switching variant.

With the increasing adoption of wide bandgap (WBG) semiconductor devices, new methods are required to manage their faster switching characteristics, particularly addressing voltage overshoots caused by fast switching. Zero Overvoltage Switching (ZOS) leverages circuit resonances during the turnoff process to nearly eliminate voltage overshoot, making fast switching essential and reducing switching losses to a minimum. This paper explores two methodologies for a novel ZOS current control in DC/DC converters: Variable Frequency Forced Continuous Conduction Mode (VF-FCCM), while efficient under specific conditions, suffers from turn-off overvoltages and significant AC losses due to high current ripple, making it unsuitable for low-load operations. In contrast, Valley Switching Discontinuous Conduction Mode (VS-DCM) mitigates overvoltage spikes and switching losses, maintaining a consistent ripple but struggles with low-load scenarios due to frequency limitations. Both methodologies were simulated and tested on a lightweight aircraft DC/DC prototype. The findings suggest VS-DCM as a promising candidate for future development.

Humidity temperature cycle (HTC) tests aim to provoke condensation and are thus considered to show other failures and to be more realistic than standardized tests like the H3TRB. One HTC test used in the field of photovoltaic (PV) application is the damp heat test mentioned in the IEC 62093 (6.9) standard. The described test procedure is designed for whole converter units but not suitable for simple test vehicles on (sub-) module basis without adaption. However, tests with smaller modules can be favorable, e.g., if designs, materials, or packaging techniques are tested. Main aim of this work is to adapt the damp heat test according to the IEC 62093 (6.9) to get from converter level to module level. The standard requires not only to apply a voltage but also defines a certain percentage of applied power. There are several short phases during one cycle when power and voltage are applied. During these phases, operation leads to power loss and the generation of waste heat. Within this work, simulation of humidity diffusion and distribution inside a module with and without power loss of the semi-conductor devices was performed. The results showed an influence of the power loss and the following waste heat. Therefore, power loss is also taken into account for the adapted test on module basis. The use of a DC-DC converter should be avoided in the developed setup for testing on (sub-)module level, but testing should also be in a relevant range. Therefore, the waste heat has to be created differently. The approach is to alternate conduction losses and application of high voltage during the phases of high power of the IEC 62093 (6.9). The target waste temperature is calculated from field profiles for a typical summer day provided by Fraunhofer ISE. Suitable heating times are experimentally elaborated.

Temperature dependent, transient effects were observed during calibration of virtual junction temperature of SiC trench MOSFETs within power cycling tests. Depending on the device design resp. semiconductor manufacturing these effects may lead to a significantly wrong junction temperature measurement thus leading to a wrong interpretation of results in lifetime testing, e.g. acc. to AQG324 PCmin, PCsec. This study investigates the time-dependent transient response of the body diode's forward voltage under test conditions with a switched gate bias applied. Based on the results, a new approach of the measurement of T-vj is proposed. This dynamic calibration method is applied to address the transient effects detected during PCT. This method is applied to SiC MOSFETs of different manufacturers. A parameter study is carried out to determine the effect of test parameters on the transient response.

Demagnetization of the rotor magnets is a significant failure mode that can occur in permanent magnet synchronous machines (PMSMs). Early detection of demagnetization faults can help change system parameters to reduce power output or ensure safety. In this paper, the effects of demagnetization faults were analyzed both in simulation and experiments using the example of drone motors. An approach was investigated to detect even minor demagnetization faults that does not require any additional sensing effort. Machine learning (ML) techniques are used to analyze the phase current data directly received from the inverter to enable anomaly detection. For this purpose, the phase current is transformed by the Fast Fourier Transform (FFT), the spectral data is then reduced in dimensionality, followed by an anomaly detection algorithm using a one-class support vector machine (OC-SVM). To ensure simplified initialization of the ML model without the need for training sets of damaged drives, only data from magnetically undamaged motors was used to train the models for anomaly detection. Different selections of considered harmonics and different metrics were investigated using the experimental data, achieving a precision of up to 99%, a specificity of up to 98%, and an accuracy of up to 90%.

Hydrogen is a promising high-density energy carrier for future transportation applications. For its usage in fuel cells, high-speed compressor systems are required for the air-supply with resulting electric motor speeds often exceeding 100.000 rpm. The following paper presents the design of a novel 80 kW highspeed drive system consisting of a permanent magnet synchronous motor (PMSM) and a corresponding wide-bandgap based inverter system. The high electric rotation frequency in combination with the lowinductance machine design leads to the necessity of high inverter switching frequencies and output currents with low harmonic distortions. Multilevel topologies help to reduce switching loss for such applications and enable the use of highly efficient 650 V GaN devices in 800 V inverter systems. In addition, these topologies can lead to improved current quality. A simulative study of the resulting inverter and motor behavior and efficiencies is presented and compared to standard B6 inverters.

Smart functionalities are a core requirement in modern electrical systems and applications and include the detection of anomalies and faults, condition monitoring, but also advanced predictive and prescriptive analyses, for example the early detection of an undesired system condition and the initiation of corrective measures. At the same time, power electronic devices are at the heart of such electrical and electronic equipment and applications in households, industrial plants or in mobility. They convert and store electrical energy, switch loads, control electrical drives and much more. For this purpose, they continuously record and frequently control parameters such as current, voltage and their change over time. When combined with artificial intelligence, such intelligent power electronics evolve to what we call “Cognitive Power Electronics” - an enabler for the aforementioned systems to become a smart energy network, a smart production plant, or a smart electric motor.

In this paper, the authors present an innovative ultra-low-power IoT-Core that can be used as an extension for efficient DC/DC converters. The module equips the overall system with computation and communication capabilities for Industry 4.0 and IIoT applications without adding significant power requirements. The research focuses on optimizing energy consumption by taking an overarching view of hardware and software at the system level. In the active state, the IoT-Core can adjust its power consumption at runtime by matching the application demands to the existing energy budget. In sleep state, the module uses a novel Wake-Up Receiver in the 868 MHz frequency band with an average power consumption of 3.5muW, allowing the system to wake up in 32ms. The results are demonstrated on a DC/DC converter, with an efficiency of up to 99.8%, which uses the plug-and-play IoT-Core to become a smart device that can save additional energy when being in idle mode.

Reliable and high power density electric machine and inverter solutions are essential for a variety of applications. Digital twin for future electric aircraft applications can contribute to analyze the system behavior and the effects between the fast-switching inverter and the electric machine. Within this paper, the concept of a “Digital Twin for a 10 MW Electrical Drive System for Future Electric Aircraft Application” is presented. A digital twin platform is based on an outer-rotor permanent magnet synchronous machine and serval interleaved multi-level SiC-inverters, which allows the usage of high switching frequencies and a high DC link voltage of 1500 V. The combination of those components have advantages in future electric aircraft applications. Several multi-level inverter topologies have been investigated and a first system design for a 10.5 MW inverter system is presented. Industry 4.0 Applications in Electric Drives Production

The third era of aviation demands for highly efficient and reliable electric drive systems to be established for commercial use. Within the European research project “AutoDrive” a six-phase inverter system for an autonomous aircraft has been developed. The drive system is realized with a 2x3-phase topology to provide fail-operational capabilities in case one of the 3-phase systems fails. A control system must be developed for a dual-three phase permanent magnet synchronous machine to utilize the fail-operational capabilities. This paper presents the highly efficient SiC drive inverter with fail-operational capabilities for small electric aircrafts including a multiphase field-oriented inverter control approach. The control algorithm is able to adapt automatically to the failure of one of the 3-phase subsystems without the need for a software-related change in the control scheme or even the necessity to detect the failure itself.

A safe connection of on-board automotive electric power grids is done by insulating HV/LV DC/DC converters. Latest electric car architectures are operating with 800 V batteries and 48 V power grids. Hence, compact 800 V / 48 V DC/DC converters are necessary. Within the following paper advantages and challenges of using SiC MOSFETs in such applications are discussed. A developed compact prototype with maximum power density of ca. 8 kW/dm(exp 3) and power weight of ca. 3 kW/kg is presented which uses different suggested solutions to manage the named challenges when using SiC MOSFETs.

Parasitic inductance causes voltage overshoot and oscillations in classic hard-switched commutation cells and power modules. Newly introduced silicon-based resistive capacitors (SiRC) can short the switching cell inside the power module itself and thereby unlink external parasitic inductance. Classic and mechanically robust power modules are now capable of switching large currents with unlimited turn-on and turn-off speed. This approach minimizes voltage spikes and parasitic oscillations without use of integrated or external attached pulse capacitors. Additionally, cutting down switching losses reduces chip area, saves energy and gains power rating of these SiRC-based power modules.

Power electronic systems for aircraft applications gain more and more interest due to increasing gravimetric power density on power stage level by utilizing advantages of WBG devices. However, the overall system design has to be optimized, including housing, mechatronic design and thermal management. This paper presents the power stage design of a highly efficient SiC drive inverter with fail-operational capabilities for a small electric aircraft utilizing only the laminar flow given by the air speed on the surface and thermal capacities of the inverter housing for cooling means.