This paper compares different modeling methods for loss calculation in an electrical traction drive system. The proposed frequency domain model enables the consideration of harmonics in the machine currents and their effects on the currents in the power electronic components and battery with a focus on arbitrary modulation strategies. With a low computing time, power loss calculations are possible across the complete machine operating range. The methods presented are validated through test bench measurements.

This paper investigates a new method for noise com-pensation in dual three-phase electrically excited synchronous machines through the use of harmonic currents, with a particular focus on preventing the force excitation of the radial and tangential mode 0. The approach of harmonic field injection (HFI) is examined, and an existing analytical relationship is presented and extended using the mechanical transfer function. This extended relationship allows for the precalculation of har-monic currents, thereby reducing extensive parameter variations. The HFI method is validated on a test bench, and the results demonstrate significant reductions in vibration in the radial and tangential directions with the mode shape 0.

This paper presents a new topology which is based on a conventional two-level converter with the addition of a modular multilevel branch as third current path to enable the quasi-three-level operation mode. In comparison to conventional converters, the output voltage steps can be reduced to the height of one module voltage when the proposed control approach is implemented. The stable operation and reduced output voltage steps of the topology are validated by simulation.

In this paper, a comparison between an active gate driver, a dv/dt filter and a conventional gate driver with gate resistors fitted to match the dv/dt limits for an EV drive inverter is drawn. After creating a mathematical model of a dv/dt filter accounting for input dv/dt and giving an introduction to the active gate driver design and control and the filter design, measurement results are presented. A comparison between the measurements and the model shows that the new model accurately represents the actual filter behavior. Measurements using virtual sinusoidal currents show the losses measured with the active gate driver are either higher or similar to those measured with the filter, depending on the dv/dt target value, DC-link voltage and load current, while the conventional gate driver always causes the highest losses. At the same time, the active gate driver can help to increase the volumetric and gravimetric power density of an inverter, making it an attractive option for electric vehicles.

We propose homomorphic algorithms for privacy-preserving applications where we are given an encrypted dataset and we want to compute the number of elements that share a common property. We consider a two party scenario between a client and a server, where the storage and computation is outsourced to the server. We present two new efficient methods to solve this problem by homomorphically evaluating a selection function encoding the desired property, and counting the number of elements which evaluates to the same value. Our first method programs the homomorphic computation in the style of the the functional bootstrapping of TFHE and can be instantiated with essentially any homomorphic encryption scheme that operates on polynomials, like FV or BGV. Our second method relies on new homomorphic operations and ciphertext formats, and it is more suitable for applications where the number of possible inputs is much larger than the number of possible values for the property. We illustrate the feasibility of our methods by presenting a publicly available proof-ofconcept implementation in C++ and using it to evaluate a heatmap function over encrypted geographic points.

In this paper, a loss-optimising branch energy control strategy is extended for the case of unbalanced grid faults. This proposed branch energy control strategy uses the circulating currents as degrees of freedom to control the energy of the module capacitors evenly between the branches. In order to generate the setpoints for the circulating currents, an enhanced analytical model of the modular multilevel converter is developed, considering grid asymmetries. Additionally, this paper explores the implementation and validation of the proposed control system in several fault cases. Both the simulation results and the experimental results of the low-voltage test bench show that the proposed control strategy operates reliably with little impact on branch losses.

This paper presents an active gate driver with variable gate resistance for use in SiC-driven inverters. Motivated by the negative effects that fast switching transients of SiC MOSFETs may have on the insulation and bearings of electrical machines, the operation theory of the active gate driver and its hardware concept are explained. Measurements with both the active gate driver and a reference gate driver are presented. A method is proposed to mathematically determine the optimal control pattern for the active gate driver. The measurements show that an active gate driver can achieve an optimal tradeoff between dv/dt and losses. In a modified control scheme, the voltage overshoot during turn-off can also be decreased. The benefits of using an active gate driver in an inverter when adjusting the control patterns to the switched current are outlined.

SiC semiconductors promise to be a good alternative to Silicon (Si) semiconductors, as they offer large savings in volume, weight and losses of the inverter. Also, the switching frequency can be extended by a factor of 10 compared to current insulated gate bipolar transistors (IGBTs), which allows the use of motor filters with small component size. This paper first presents the dimensioning of a 10 kW air-cooled SiC inverter, which has been designed for the purpose of output filter characterization. The main part includes the design and characterization of an output dv/dt filter for highly-integrated Silicon Carbide (SiC) inverter systems used in traction drive or in more electric aircraft applications. Several tests at full output power of 10 kW and 600 V DC-link voltage as well as efficiency measurements verify the system design.

This paper presents the 100 kW air-cooled inverter design of a power train used for advanced high-lift systems in future aircrafts. To achieve additional high-lift during take-off and landing of a plane, air is blown out at the back flap of the wings using a turbo compressor directly driven by an electrical machine. Silicon Carbide (SiC) devices promise large savings in volume, weight and losses of the inverter, which results in a highly-integrated system. Furthermore, the intake air is used as coolant for the power electronics. Such a system with a high power density of 10.8 kW/l has been designed and implemented, and first tests were performed on a laboratory prototype.

The growing complexity of todays technical systems demands for improved simulation techniques. One important aspect is the way how hierarchy of interconnected dynamical systems is handled. Focusing on this, some existing approaches are reviewed and a modified component connection modeling (CCM) framework is introduced. Furthermore, several conceptual considerations of CoSimMA, a modular simulator based on this theoretical foundation, are presented. As an example, the hierarchical modeling of a wind turbine and the included power electronics is outlined.

Modular Multilevel Converters have a large number of advantages at high voltage and power levels. Due to their modular structure, they offer easy scalability, high quality output waveforms, and superior availability, to name a few. This paper aims at further increasing the availability of the Modular Multilevel Matrix Converter. A new method allows to operate the converter even in the case that a complete branch is lost. This is achieved by a new control method to operate six of the remaining branches as a reduced matrix converter. Smooth transition from full matrix to reduced matrix operation is achieved without shutdown of the system.