Open-switch faults in voltage source inverters significantly affect the operation of permanent-magnet synchronous machines, especially when multiple switch faults occur simultaneously. This paper presents a comprehensive analysis of the remaining feasible voltages under different combinations of double open-switch faults. Based on this analysis, a fault-tolerant control strategy is discussed that aims to minimize torque ripple and prevent overcurrents. The presented visualization of remaining feasible voltages along with the approach for fault-tolerant control allow for a classification of fault combinations according to their impact on control performance and machine behavior, including the identification of a worst-case combination of double open-switch faults. Experimental results obtained on a laboratory test bench validate the effectiveness of the proposed control strategy and confirm the identified worst-case fault combination.

This paper presents ongoing research activities for simultaneous power and data transmission over a miniaturised single coaxial tether, developed for the Nanokhod Microrover for lunar and planetary surface exploration. The use of a combined link significantly reduces system complexity, mass, and potential failure points. However, the interaction between the inductive fields of power and data transmission introduces substantial electromagnetic interference. A detailed analysis revealed opportunities for further development of the existing solution in order to increase robustness, data rates, and functionality of the power and data transfer. To overcome challenges, full-period demodulation, digital low-pass filtering with a rect filter, and active analog high-pass filtering were implemented. The fullperiod demodulation compensates for asymmetries in the data signal caused by the 60kHz interference, while the digital filter improves robustness against transient disturbances. On the lander side, an active filter suppresses the dominant 120kHz interference after the tether. Practical measurements demonstrate stable, reliable half-duplex communication without bit errors at a data rate of 500kBd during continuous power transfer of 10W over a 100m tether.

In automotive application, wireless power transfer (WPT) systems are desired to operate in a wide range of coupled coils and system topology combinations. The operating range of a single primary side is therefore subject to alternating load conditions and resonant tank detuning. This is caused by parameter uncertainties due to relative coil positioning, different vehicle types and numerous degrees of freedom during interoperable design. In terms of running WPT systems with diverse charging entities, this paper introduces the Mobius transform as a valuable tool to decompose and visualize the inherent shifting of a systems operational range due to mutual interference of magnetic flux conductivity and varying inductive coupling condition. By its rigorous formalism and yet intuitive geometry, the image of locus trajectories can be classified into four characteristic categories. In this context, this paper demonstrates the application of cascaded Möbius Transforms in double-sided LCC-compensated systems to decompose its input impedance.

This paper presents a communication-based method for synchronization and control of active rectifier in wireless power transfer (WPT) system, which enables the joint control of inverter and active rectifier from one control-unit of both sides. Compared with the conventional current-based control of active rectifier, the proposed method needs no current sensing on the secondary side. The simultaneous communication is established using Double-D (DD) coil that is integrated in WPT-coil of each side, so that the crosstalk from WPT to the communication is well suppressed. Using the synchronization signal of communication, which is modulated on the inverter side and demodulated on the rectifier side, the control signals of the inverter and rectifier are firstly synchronized. Then, based on the transmitted control parameters for active rectifier, the phase difference of voltages between inverter and rectifier as well as the duty cycle of rectifier are set. Therefore, no extra stability algorithms are required because the phase difference of voltages is set directly through communication. Experimental results on the 3.3 kW-WPT-system show that the latency (from release of new parameters in the control-unit on the inverter side to rectifier response) is less than$30\ \mu\mathrm{s}$, when switching energy direction, adjusting duty cycle and tuning phase offset of the active rectifier.

In this paper, the application of a fault-tolerant control of a permanent-magnet synchronous machine with a converter under open-switch fault is validated using a validation environment of connected test benches. Spatially separated test benches for vehicle components like converter, electric motor and gearbox are connected via a virtual private network, which allows to analyze the interactions of the spatially separated components in real-time. This paper focuses on a downhill driving scenario of a vehicle experiencing an open-switch fault in a converter. Measurement results show that the proposed fault-tolerant control allows the vehicle to finish the drive safely despite the fault, validating the applicability of the control strategy for vehicle applications.

This paper deals with the design and optimization process of a quadruple 3-phase electrically excited synchronous machine (EESM) with isolated star points targeted for a 48V battery electric vehicle (BEV) traction drive. The EESM is designed for the operation with a high frequency rotating inductive contactless energy transfer system (CET) integrated into the shaft. A multi-objective optimization routine considering electro-magnetic and mechanical constraints with the total drive efficiency at the torque-speed envelope and the active machine weight as objectives is developed. The gear ratio, maximum phase current and rotor MMF are considered as parameters in order to find an optimal balance between machine size and total drive efficiency. The operating points at the torque-speed envelope are calculated computationally efficient by taking the location of the short-circuit current and its influence on the behavior of the machine into account. The developed optimization algorithm is tested by optimizing the 48V iEESM traction drive towards an output power of 60kW and the electro-magnetic and mechanical results are discussed.

This paper deals with the design and optimization process of a quadruple 3-phase permanent magnet assisted synchronous reluctance machine (PM-SynRM) using a multiobjective genetic algorithm of Matlab’s Global Optimization Toolbox (gamultiobj). The implemented algorithm allows an operating point dependent optimization considering nonlinear flux linkage maps. The resulting 75 kW PM-SynRM with three flux barriers and six poles is intended for an automotive application with a DC link voltage of 48 V. In order to reduce the amount of rare earth magnets the PM-SynRM uses one NdFeB and two ferrite magnet(s). This machine type is called Hybrid-Magnet-SynRM in this paper and will be compared against a pure Ferrite-Magnet-SynRM. It will be shown that in this framework FM-SynRMs lead to high demagnetization ratios after a symmetrical short circuit. Hence the NdFeB-magnet is used to enhance the demagnetization withstand capability. Moreover the HM-SynRM will be optimized with two objective functions: active volume and weighted sum of efficiency considering three operating points.

Inductive power transfer is a promising technology that can be used to charge moving objects (e.g., electric vehicles). However, position changes of coils lead to variation of charging power, which can reduce average power and consequently extend the charging time. Based on frequency bifurcation phenomena, this paper proposes a scheme to reduce power fluctuations using online adaptive switching frequency modulation, and it is verified on a series-series-compensated wireless power transfer system with a non-stationary secondary side. At the same time, the method still ensures that the voltage and current are in phase, so the soft switching technique is still applicable. Finally, the FPGA-based prototype shows that the output power variation of system using this scheme is less than 7%, when coupling factor changes from 0.3 to 0.6, while the output power variation with a constant switching frequency is greater than 48%.

In this paper, a comparative analysis of brushless DC motor (BLDC) and brushless AC motor (BLAC) drive modes is presented for an axial flux motor with trapezoidal back-emf waveform. The 120-degree and 180-degree commutation modes are studied for BLDC mode, while the SPWM and SVPWM methods are investigated for BLAC mode. Based on the co-simulation of 3D-FEA and ECS, the influence of drive strategies on the motor characteristics, losses and efficiency are analysed. Furthermore, the effect of phase advance is also considered in this paper. It is shown, that the BLDC mode with 120-degree conduction has the best efficiency performance, while the BLDC mode with 180-degree commutation provides the widest speed range and the SVPWM drive features the lowest torque ripple.

This paper deals with the analytical modeling of field problems in magnetic devices. A new method for the analytical calculation of the so-called two-dimensional flux tubes is presented. Based on the well-known flux tube concept with just one-dimensional flux tube geometries, the calculation method is extended to the two-dimensional flux tubes. Moreover, the geometries with trapezoidal and elliptical shapes are discussed here, in this paper. In conclusion it is shown that the newly introduced analytical method reduces the error of the modeling in comparison to the FEA to below 8%.

In this paper an enhanced direct torque control for Switched Reluctance Machines is presented. Due to the heavily nonlinear magnetic characteristic an inherent torque ripple exists. In order to open up new areas of industrial application the torque ripple has to be minimized. The novel strategy includes an online calculation method of the hysteresis limits based on the estimation of the total torque gradient. The adaptive properties of the online calculation method leads to an increased robustness against parameter variation, such as the DC-link voltage. The proposed control strategy is implemented on a field-programmable gate array development platform. Finally simulation as well as experimental results on test bench are carried out to evaluate the control performance.

The electrification of the automotive powertrain provides completely new control options regarding the distribution of individual wheel moments. The integration of up to four independently controlled electrical engines in a vehicle allows individual adjustment of driving and braking torques to the current driving situation. Thus, electrical engines create a new kind of dynamic vehicle control. Unlike the Electronic Stability Control (ESC), Torque-Vectoring influences the vehicle dynamics not only through braking forces but also by setting up positive driving torques allowing for a new way of dynamic driving. In this paper two different control algorithms are developed in order to calculate a desired yaw moment to influence vehicle dynamics. The Torque-Vectoring algorithm distributes the yaw moment among the four wheels. The evaluation of the vehicle dynamic simulation has shown that the best results regarding the control quality can be reached by using the Fuzzy control algorithm to optimize the driving stability in extreme driving situations.