In recent years, controllable magnetic devices gained a major interest in different application areas as they offer another level of freedom to power electronic systems, improving system efficiency, power density and controllability. However, comprehensive physical behavior of variable inductors (VIs) remains poorly studied with respect to controllability and coupling effects between the auxiliary and primary winding. This paper introduces a novel measurement-based characterization method for identifying and quantifying mutual coupling effects in dc-biased magnetic devices. Therefore, two toroidal core structures, an orthogonal (OM) and a mixed-biased (MB) pre-magnetized core, are investigated, highlighting the differences in coupling behavior. The method applies Fast Fourier Transformation (FFT) to induced voltages on the auxiliary winding, enabling the assignment of specific harmonic components to distinct coupling mechanisms. Harmonic-specific coupling factors are proposed to isolate individual effect. Thus, this paper aims to provide a characterization method applicable to any dc-biased magnetic device, helping to isolate coupling effects and quantify magnetic coupling by means of specific factors. A general analytical model will be proposed to interpret the measured coupling effects.

This study focuses on enhancing AC current regulation in three-phase grid-tied voltage source converters (VSCs) equipped with an LCL filter, which are commonly used in distributed generation applications. Conventional controllers like proportional-integral (PI) and proportional-resonant (PR) are typically utilized to minimize steady-state errors at the fundamental frequency. However, mitigating higher-order harmonics remains a challenge. To address this, a proportional-resonant with multi-resonant (PR-MR) control strategy is integrated into the current control loop to effectively suppress harmonics caused by dead-time effects and grid voltage distortions. A structured control design approach is proposed, along with a detailed stability assessment of the system. Experimental validation reveals a significant decrease in total harmonic distortion (THD) of grid currents, reaching approximately 1.1% under distorted grid conditions, thereby ensuring compliance with IEEE 1547 standards. The control scheme is deployed on a TMDSDOCK28379D 32-bit floating-point DSP. Performance evaluations are conducted using MATLAB/Simulink simulations and further verified through hardware experiments on a 7.5 kW three-phase LCL-filtered VSC operating under the proposed control framework.

Optimization loops are often required for the improvement of function and electromagnetic compatibility (EMC) in a product development process. Such optimization can be realized either by simulations or high effort based measurements. The neural network approach is suitable to overcome typical issues of simulation programs like SPICE such as convergence problems and high computation time. This paper addresses a neural network modeling approach for nonlinear passive filters. Long Short-Term Memory (LSTM) networks are applied to model nonlinear passive filters. One measured and two simulated filter circuits are used as application examples. LSTMs are chosen by literature research as a suitable modeling approach. The neural network and training structure is defined by literature research and systematic experiments. The filter behaviors are basically modeled by the trained neural networks. But further improvements have to be done. It is shown that the corresponding voltage and current time series can be learned and predicted by the LSTM networks in their essential characteristics. These voltage and current time series can generally be used in further applications. A possible speed advantage of LSTM networks is also examined.

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.