IEEJ Transactions on Electrical and Electronic Engineering最新文献

This paper provides an in-depth study of the winding mechanical properties in generators under rotor interturn short circuit (RISC) cases. Unlike previous studies, this research investigates not only the influence of RISC degrees, but also the RISC positions and the eccentricity on the winding mechanical properties. The electromagnetic force (EF) formulas as well as the electromagnetic-structure coupling model are first proposed to derive the mechanical winding response characteristics, such as the vibration, deformation, the strain, and the stress. Subsequently, both finite element analysis (FEA) and experimental investigations are conducted to validate the theoretical findings. The results reveal that RISC introduces additional harmonics to the EF. Furthermore, as the eccentricity/RISC degree or the distance between the short circuit position and the N-pole increases, the end winding vibrations become more pronounced. When comparing single eccentricity and RISC faults to cases where both faults occur simultaneously, it is observed that the combined faults have a more detrimental impact on the end winding mechanical properties. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

In this work, intrinsic spin Hall conductivity of β-W and its alloy with V has been theoretically studied by the combination of ab initio method with the tight binding method. Both two possible configurations of V in β-W structure are fully considered and their total energy difference used to estimate the thermodynamic average SHC of alloy by using Maxwell-Boltzmann distribution. It is found that due to the small total energy difference between two configurations, there is a significant contribution to the thermodynamic average SHC of the alloy from both configurations, which results in the average SHC of alloy being enhanced up to 12.3% compared with the pristine β-W. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

In this study, the effect of elastic biaxial strain on electronic structure and the anomalous Hall conductivity (AHC) of α-Fe has been systematically studied by using the combination of a first principles calculation with the tight binding method through the Wannier function. It is found that applying strain in cubic structure of α-Fe results in the reduction of crystal symmetry and gives the modification on the bands near Fermi level, which causes a significant change in the AHC of strained systems. The AHC of strained α-Fe is found to be sensitive with applying strain, which shows the large enhancement of AHC at +2% tensile strain with AHC value is up to 929 Ω⁻¹ cm⁻¹ (increases more than 30%) compared with the unstrained one, while slightly reduces when applying compressive strain. The modification of AHC is found to be related to the change of Berry curvature contributed from the spin orbit coupling (SOC) induced energy gap near Fermi level. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

In this study, we devised an evaluation method and a quantitative index for the radial distribution of the out-of-plane deformation of kirigami structures with a slit pattern on concentric circles. The concentric kirigami structure was deformed in the out-of-plane direction by pulling the center of the structure, and the out-of-plane deformation distribution in the radial direction was changed by changing the distance between the slits in the radial direction of the circle and the length on the circumference of the circle. We used a single quantitative index to express the radial distribution of out-of-plane deformation. If the design of the kirigami structure can be freely determined from the quantification index, it can significantly contribute to the realization of useful devices which uses the concentric kirigami structure. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

In order to address the issues of significant input variations and complex disturbances in speed control of permanent magnet synchronous motors (PMSM), a Modified Active Disturbance Rejection Controller (ADRC) based on an improved Modified Extended State Observer (ESO) is proposed in this paper. In this new method, a nonlinear cascaded structure of observers is adopted. By utilizing the TD filter, high-frequency noise can be attenuated while preserving the dynamic characteristics of the signal. Moreover, system oscillations caused by minor errors are effectively suppressed. The introduction of propeller and wave models enhances the realism of simulated marine environmental disturbances. Research results indicate that, compared to a single Extended State Observer, the cascaded MESO exhibits better disturbance rejection and noise resistance in complex marine environments, and the proposed MADRC outperforms both PI controllers and ADRC in dealing with marine environmental disturbances. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

The performance of neutral-point-clamped (NPC) converters is subject to the regulation of neutral point balance. In the literature, researchers have addressed two main modulation methods: the active space vector PWM (SVPWM) technique and the virtual SVPWM (VSVPWM) method. However, those two approaches respectively suffer from reduced DC-link voltage utilization and poor active regulation capability. To address this, an improved VSVPWM modulation scheme with actively strong voltage regulation capability is proposed in this paper. The fast and precise control of capacitor voltages is achieved by optimizing the synthesis scheme of the virtual vectors. When there is a voltage imbalance, the proposed technique can quickly restore and maintain the capacitor voltage balance till the full DC-link voltage utilization without affecting the converter output quality. The experimental validation results on the NPC converter have demonstrated the benefits of the proposed active VSVPWM method. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

A key issue in the transition to decarbonized energy sources with constant power sources is inaccurate current sharing and voltage quality. The main reason which causes these issues is the inevitable system impedance mismatches. This study addresses this issue by proposing an enhanced power-sharing strategy that regulates adjustable resistance and compensates for voltage drops across the line impedance at the output of distributed generation converters. The control approach involves analyzing the mathematical relationship between system impedance mismatches and voltage drops in DC residential systems. Utilizing low-computation proportional-integral controllers, the secondary current sharing and load voltage controllers regulate converter outputs to compensate for mismatched resistance and voltage, ensuring proper current sharing and load voltage quality across various load conditions. Through the implementation of the proposed scheme incorporating adjustable resistance and voltage shifting terms, both the current-sharing error and load voltage deviation are gradually reduced to negligible values, while maintaining stable performance in steady-state conditions, without the need for prior knowledge of system parameters. Simulations and experimental studies are both conducted to demonstrate the effectiveness of the proposed control scheme. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

A gaseous mixture of CO₂ and C₅F₁₀O has been widely investigated as one of the alternative gases for SF₆. Due to the better electron attachment ability of oxygen molecule O₂, it is generally expected that adding of O₂ gas would improve the dielectric strength of arc quenching and insulating gas for electric power equipment. Therefore, in this paper, the dielectric breakdown properties of hot CO₂/O₂/C₅F₁₀O gas mixture were numerically estimated. The calculation results revealed that the critical electric field strength of the CO₂/C₅F₁₀O gas mixture is disappointingly decreased by the addition of O₂ gas, especially in the temperature range of 3000 K to 1000 K. This is brought about by the increase of ionization reaction of CO₂ molecules with an increase in the O₂ concentration in the arc-quenching gas of CO₂/O₂/C₅F₁₀O. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

This study proposes a cost-effective, small-size, and portable impedance analyzer using the AD5941 Analog Front End (AFE) that makes frequency sweep measurement for various applications. The design utilizes a microcontroller and an AD5941 circuit for impedance measurement. The AD541 is a high precision impedance converter system that consists of a 16-bit, 1.6 MSPS, analog to digital converter (ADC), an integrated waveform generator, and a digital signal processing (DSP) block. The AD5941 has many advantages over the AD5933 which was used in numerous studies in the past decade. Also, the device implements the four-wire impedance method which is an impedance measuring technique that reduces the effect of electrodes to achieve higher accuracy. A supporting Graphic User Interface (GUI) software is employed to control the Impedance Analyzer device and to visualize the measurement. This impedance analyzer achieves a frequency resolution of 0.015 Hz and can generate sinusoid up to 200 kHz. In frequency range from 10 kHz to 150 kHz, the device can measure impedance in the range of 10 Ω–100 kΩ with less than 4.3% of error in comparison with benchtop impedance analyzer, Microtest 6632. Moreover, our impedance measurement device has undergone testing involving human calf measurements and electrochemical quantification, particularly for estimating Sodium Chlorite. The experimental outcomes demonstrate that our design not only fulfills the criteria of an impedance analyzer device but also performs effectively across diverse applications. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.