Conference Agenda

The article investigates the problem of analyzing the eddy current losses that occur in an axially laminated rotor of a synchronous reluctance electrical machine. A comparative analysis of 2D and 3D formulations of the losses calculation has been carried out. Based on the concept of magnetic energy, a new correction factor has been introduced to convert 2D losses into 3D results. The results of full simulation using FEM show a sufficiently high accuracy of the proposed method, which allows for its practical application. At the same time, the computational time of the model was significantly reduced.

Reduced order models of electrical machines are needed for several purposes, for control, system level design and optimization, and digital twins just to mention a few. The most common reduced order approach for permanent magnet synchronous machines (PMSMs) is the direct (d) and quadrature (q) axis equivalent circuit -based. The losses in the ferromagnetic cores are often neglected or modeled with a single resistance. For more detailed analysis, it would be beneficial to understand the loss distribution in the different parts of the machines. Hence, we propose a PMSM equivalent circuit model with separate stator and rotor core loss resistances. The core loss resistances are represented as parameterized functions of stator voltage and flux linkage. The data used for fitting the core loss resistance models are obtained by 2D finite element analysis (FEA). Via the FEA data, the model accuracy is improved without losing any its computational efficiency. The equivalent circuit model results and FEA results are compared in the full version of the article.

For the switched reluctance motors(SRMs), the zeroth-mode vibrations play a significant vibroacoustic role. For conventional analysis in literature, it is usually assumed that stator vibration caused by the zeroth-mode is evoked by the spatial zeroth-order radial force harmonics. However, the genuine reason for zeroth-mode vibration, which is different from the conventional analysis, is proposed and discussed in detail in this paper. The stator teeth modulation effect on SRMs is analyzed for the first time to demonstrate that the radial forces that have the spatial order of multiples of slot-number (including zero) are the root of the zeroth-mode vibration. To this end, the spatial-temporal distribution characteristics of the radial force are derived analytically, demonstrating the existence of high spatial radial forces that oscillate in the pattern of standing waves. Then, the stator teeth modulation effect for the standing waves is analyzed, indicating that the standing waves with high spatial order can also evoke the “breathing” type of zeroth-mode vibration. The amplitudes of the spatial zeroth-order radial force and spatial high-order standing wave forces are analytically compared, and the structural finite-element analysis (FEA) results validate the correctness of the analytical results since the good agreement.

As transformer oil-paper insulation deterioration is significantly affected by the winding hot spot temperature, it is of great significance to realize the accurate prediction of the hot spot temperature (HST). Based on the multi physical field simulation analysis model of transformer and SVR artificial intelligence algorithm, the digital twin model of S13-M-400 kVA/10kV transformer is constructed to realize the virtual sensing of HST. The coupled electromagnetic thermal fluid field analysis is realized by the method of indirect coupling, and the established multi physical field simulation analysis model is used to calculate the working conditions of training samples and test samples. A good results are obtained in the test samples, with an average absolute percentage error of 2.18% and a maximum virtual sensing error of 3.17 ℃.

This paper proposes a BH curve tracing method for random material by magnetic contact force. Usually, the BH curve of a material is measured using an Epstein frame or VSM. However, the Epstein frame is difficult to measure in the high magnetic field area, and the VSM is expensive. The proposed method in this paper tracks the magnetic flux density and magnetic field strength inside the sample by measuring the force of the magnetic contact force sensor. The proposed method uses DC and has no air gap. Therefore, there is no measurement difficulty due to harmonics. In addition, since a high magnetic field can be formed with a small amount of energy Low-cost miniaturization is possible in a new way that is different from the existing method. The proposed method is explained in principle through a simple model and demonstrated through simulation.

The development of a magnetic imaging technique for simultaneous and quantitative measurement of the three components of the magnetic stray fields emitted by a material is of interest for material science and non-destructive testing. In order to propose a highly sensitive (nT/√𝐻𝑧) and resolved in space (10𝝁𝒎) measurement, we use simulation and numerical computation techniques in the service of a 3D local probe composed of giant magnetoresistance (GMR) magnetic sensors.

The radiofrequency (RF) coil is an important component of nuclear magnetic resonance (NMR) logging sensor. The use of Litz wire as RF coil can help minimize the resistance and increase the signal-to-noise ratio (SNR) of NMR signals. In this study, we proposed a new and effective numerical model for analyzing the Litz wire RF coil. First, we proposed a new numerical model for SNR analysis considering the tuning and matching circuit. We then introduced a homogenization-based finite element method to calculate the Litz wire around a ferrite core. We compared the signal distributions and performance indexes of Litz wire and enameled wire through our proposed model. Results show that the model analysis results are consistent with the measured results.

This article investigates an estimation method of the current density distribution in photovoltaic (PV) modules to detect failures and defects in the modules. In the proposed method, the current density inside the PV module is estimated from the surrounding magnetic field distribution using the truncated singular value decomposition (TVSD) method. The failures and defects in PV modules can be directly predicted based on a visual representation of the current density vectors. The effectiveness of the proposed method is verified by applying it to a PV cell and module with a disconnected terminal.

The aim of this work is to optimize the design of a sensor-actuator measurement system for identifying local variations in the magnetic permeability of cut steel sheets. For the evaluation of the magnetic field values depending on various design parameters and material distributions, a 2D magneto-static problem is solved by the finite element method. Since the inverse problem, i.e. finding the material parameters causing the measurement data, is ill-posed, solving it is a challenging task. Therefore the design of the measurement setup should first be improved in order to increase the identifiability of the material distribution. Thus, the objective of the design optimization is formulated as a function of the global sensitivity of the measured flux densities with respect to permeability variations in the steel sheet. Due to the enormous numerical effort arising with the valuation of the global sensitivities within the optimization procedure, a surrogate model of the sensor-actuator system has been trained in advance and is used to predict the magnetic flux densities.

In this paper, a numerical method for simulation of motion-induced eddy current testing (MIECT) signals was developed for probe design and optimization based the reduced vector potential formulation and the edge finite element at first. Two MIECT pickup signal calculation approaches based on the Biot-Savart’s Law and the reciprocity theorem are adopted to obtain the signal component of eddy current and magnetic current. It is found that the signal perturbation due to a crack perpendicular to motion direction is relatively small for the conventional coil under PM probe configuration. Through analysis of signal proportion due to eddy current and magnetic current for a ferromagnetic material, a double-PM exciting probe referring to the structure of the magnetic yoke is proposed to enhance the detectability of MIECT to perpendicular crack. Meanwhile, a novel hollow PM exciting probe is also designed for efficient inspection of the perpendicular crack in a non-magnetic plate. Finally, the geometrical parameters of the new probes are optimized based on the genetic optimization algorithm.

PEFC (Polymer Electrolyte Fuel Cell) is one of the desired clean energy converters and has the advantages of short-up time to power generation, low temperature, small size, and lightweight. In order to increase the power generation efficiency of PEFC, it is necessary to monitor the generation of current inside MEA (Membrane Electrode Assembly) in PEFC. Therefore, in this research, the evaluation method of estimating the generated current inside the MEA using the static magnetic field around the PEFC by inverse problem analysis is proposed. In this inverse problem analysis method, CMA-ES (Covariance Matrix Adaptation Evolution Strategy) is applied. This method enables the estimation of the power generation current distribution near the center inside the MEA in the fuel cell, which is said to be difficult to estimate.

Thrust ripple caused by the longitudinal end effect detent force (EEDF) is widely recognized as an inherent flaw of permanent magnet linear synchronous motors (PMLSMs). This paper aims to prove that the EEDF is not necessarily an inherent problem of PMLSMs, it can be eliminated if the structure of mover core ends is carefully designed. To this end, a stochastic design methodology for PMLSMs is proposed to discover the ideal mover ends structure, which is free of EEDF. The numerical results show that the detent force (DF) of a typical PMLSM is suppressed by 97%, and the EEDF component in the DF is eliminated. As the result, the thrust ripple is significantly reduced with no sacrifice of average thrust. Finally, a PMLSM prototype is tested to verify the viability of the proposed methodology.

In this paper, we propose a fast shape optimization method for interior permanent magnet synchronous motors to reduce losses considering inverter carrier. In the proposed method, the harmonic loss caused by the largest component of the harmonic voltages is calculated by linear frequency domain finite element analysis with the differential permeability distribution obtained by time domain FEA. The variation in the total carrier loss with the motor shape is estimated by the variation of this largest harmonic component and sum of the square of harmonic voltages. The proposed method is applied to the rotor surface optimization of an interior permanent magnet motor. It is clarified that the total computational time is reduced to be 1/5 as compared with the conventional method.