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Brushless doubly‐fed air‐core pulse alternator (BDAPA) is a new type of pulse alternator. It does not need a brush and slip ring, improving the reliability of the system. Moreover, the field winding and rotor winding have good compensation effect, which can significantly improve the discharge performance of the pulse alternator. As a high‐power pulse power supply, BDAPA must have a set of corresponding excitation power supplies to control its excitation. Pulse alternator and excitation power supply constitute the pulse alternator power supply system. The excitation power supply of pulse alternator usually adopts a pulse capacitor, the field winding of pulse alternator is excited by the pre‐charged capacitor before the pulse alternator discharges the load. After discharging, the excitation capacitor must be charged again before the next work of pulse alternator. This requires an additional set of DC power supply to charge the excitation capacitor. It not only increases the volume of the whole system and reduces the energy storage density of the system, but also makes the control of the system more complex. Taking the BDAPA as the research object, this paper proposes a control method with energy feedback, which is combining self‐excitation and separate excitation. Using the inertial energy storage of the pulse alternator and the inductive energy storage of the field winding and rotor winding, the excitation capacitor can be recharged through proper control methods, which can save the DC excitation power supply and improve the energy storage density of the system. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents layer‐by‐layer additive manufacturing (AM) of molten metal microdroplets and dielectric materials to fabricate multilayer hybrid circuit boards featuring interdigitated 3D capacitors. The printed metal lines have a low resistance of 5 mΩ/mm, 12 times lower than state‐of‐the‐art conductive inks. Exploiting the advantages of Sn‐based oxide as an ideal candidate for Electrical Energy Storage Systems (ESS), we successfully fabricated an out‐of‐plane capacitor module using a combination of polymer and metal materials. The fabrication process exhibited an exceptional aspect ratio of 16, illustrating the successful incorporation of 20 metal layers in the out‐of‐plane capacitor module. Q factor obtained for the 3D capacitor was in the range of 66–500. Additionally, a fully automated printing technique was employed to produce a multilayer hybrid electrical printed circuit board (PCB), eliminating the need for post‐processing. This streamlined approach presents an efficient and comprehensive solution for the one‐stop printing of intricate electrical circuits. © 2024 The Authors. IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) were important industrial chemicals featuring high thermal and chemical stability and low flammability. They were widely used as dielectric and thermal fluid in closed electro-technical applications (transformers, capacitors...) and also in numerous dispersive uses, ranking from auto-copying paper to sealant or coatings. During the 1960s, severe environmental consequences started becoming apparent. The stability of PCBs contributed to their persistence in the environment, their lipophilic character to bio-magnification. Fish-eating species seemed threatened in their existence. In Japan and in Taiwan, thousands of people consumed PCB-contaminated oil. The production of PCBs stopped completely during the 1980s. Usage could continue in closed applications only. In this paper, particular attention is given to two issues: the cleaning of PCB electric transformers and the potential impact of PCB-containing building materials. Other contributions will cover the management and treatment of PCB-contaminated soil, sludge or fly ash. The complete survey is being prepared by request of the Knowledge Center for Engineers and Professionals. [ABSTRACT FROM AUTHOR]

In recent years, a rapid spread of residential photovoltaic power systems (PVs) causes voltage imbalance in distribution systems. For this reason, it has become difficult to control voltage in distribution systems to within the allowable range. Therefore, the authors have proposed a system for suppressing the voltage unbalance using single‐phase static capacitors (SCs). The purpose of the system (SC system) is to suppress voltage imbalance by controlling single‐phase SCs in each phase, and its effect has been confirmed by the previous authors' study. On the other hand, as a result of analyzing the voltage measured on some distribution lines, the authors found that it is not necessary to control single‐phase SCs in each phase because the voltage imbalance hardly changes throughout a day. In this paper, an alternative method for suppressing the voltage imbalance by constantly installing single‐phase SCs on distribution lines is proposed in order to realize at a lower cost than the previous SC system. In addition, the authors verify the effect of the method on the actual distribution lines. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The performance degradation trend of a tantalum capacitor has different characteristics in different degradation regimes with different temperatures and humidity. Clustering method and degradation trend analysis can be useful for early warning of life. In this paper, according to the degradation characteristics of the capacitance and the dissipation factor with different temperature and humidity, the experiment is designed, and the failure mechanisms of different degeneration regimes are analyzed. After the ordered clustering method is introduced, using the natural property and the change rate α(k) of the slope β(k) of the error function δ[p(m,k)], the determination method of the optimization clustering number is put forward. The Davies‐Bouldin Index is proposed as the evaluation method of the ordered clustering result, and the validation of the evaluation method was verified by the degradation data with other stresses. For the stable degradation regime, the degradation trend analysis is completed. The error result shows that the degradation fitting functions can be a good fit for the degradation trend with different stress. According to the degradation fitting analysis, the degradation prediction method is described to find the relationship between prediction life and different temperature and humidity to realize the failure time prediction with different stresses using the early degradation data. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASCVC has 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response pf reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains. [ABSTRACT FROM AUTHOR]

A general-purpose circuit analysis soft- ware such as SPICE, and an SC-specified circuit analysis software such as SWITCAP, are both available for analysis of SC circuits, However, the former requires additional pre- and post-processings because the analysis is performed by converting SC circuits into equivalent continuous-time circuits such as active-RC circuits. As to the latter, the present limitation on the kind of OS environments is severe tor users in Japan. SCNODAL proposed in this paper is developed for the purpose of providing an SC circuit analysis tool which is easy to use and is implementable on general-purpose or personal computers popular in Japan. Since SCNODAL has many functions, it is useful as a semi-general-purpose SC circuit analysis tool. SCNODAL has an input format which is best suited for an analysis of parasitic-Insensitive SC filters. Since nine-standard building blocks are built in the program, a compact representation of the input data is possible. Furthermore, SCNODAL has many user-oriented functions with regard to a clock-pattern input form, an input font for a tracking pattern of elements, and an option for an output form. Thus, one can easily perform a variety of analyses such as amplitude response analysis and sensitivity analysis. In this paper, SCNODAL is described based on the formulations of the nodal equation and other equations used in each analysis to the actual usage of this software, by illustrating an SCF design. [ABSTRACT FROM AUTHOR]

This paper proposes a new configuration of the series–parallel continuously regulated chopper applying three‐level operation realized by flying capacitor topology. In the conventional two‐level operation, the increase in switching loss and volume of the inductor is problematic. In three‐level operations, both switching frequency and inductance of interconnecting inductor become half of those of two‐level operation under the condition of same current ripple and same ripple frequency. Using a low‐voltage power device, the switching loss can be reduced without increasing the volume of the inductor. The effectiveness of the proposed circuit was verified from steady‐state waveforms obtained by simulations. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

A supercapacitor is a type of electrical component that has larger capacitance, due to asymmetric behavior with better power density, and lower ESR (effective series resistance) than conventional energy-storage components. Supercapacitors can be used with battery technology to create an effective energy storage system due to their qualities and precise characterization. Studies have shown that the use of quantum dots as electrodes in supercapacitors can significantly increase their effectiveness. In this research article, we have used a Drude model based on free electrons (asymmetric nature) to describe the supercapacitor's discharging characteristics. Commercially available Nippon DLA and Green-cap supercapacitors were used to verify the Drude model by discharging them through a constant current source using a simple current mirror circuit. The parameters of both the fractional-order models and our suggested method were estimated using the least-squares regression fitting approach. An intriguing finding from the Drude model is the current-dependent behavior of the leakage-parallel resistance in the constant current discharge process. Instead of using the traditional exponential rule, supercapacitors discharge according to a power law. This work reflects the strong symmetry of different aspects of designing a hybrid supercapacitor with high efficiency and reliability. [ABSTRACT FROM AUTHOR]

What will cars look like in 100 years' later? They must run by 'electric motor' and will receive energy directly from electric power infrastructure like electric trains. The key technologies here are 'supercapacitors' to excel in power input and output rather than batteries, and 'wireless power transfer' to connect cars to power infrastructure. Furthermore, energy efficiency and safety will be dramatically improved by the technology of 'motion control' to make use of the excellent torque control characteristics of electric motor, also together with automatic driving technology. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The multilevel inverter is the most advanced power conversion system, whose main advantage is to improve power quality and efficiency. Cascaded H‐bridge (CHB) multilevel inverter is a kind of inverter that can be selected in the field of motor drive systems, electric vehicles and photovoltaic grid‐connected power generations. However, the CHB multilevel inverters require a great deal of independent direct current (dc) power supplies, which makes the realization of these inverters very complicated in practical applications. In this article, model predictive control for CHB inverter with flying capacitors is proposed to improve the above drawbacks. Simulation and experimental results show that voltage balance of the flying capacitor can be maintained and simultaneously the output voltage of the inverter normally. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to take the advantage of boost capability and filtering characteristics of the switched inductor/capacitor, a non‐isolated switched inductor/capacitor (NSI/C) converter is proposed. The topological structure of the non‐isolated switched inductor/capacitor converter is analyzed in detail, and the DC steady‐state model is established in continuous conduction mode (CCM). The voltage gain of the converter and the stress of the switch in the converter are theoretically deduced and compared with the existing converters; the parameter design of the inductance and capacitance is calculated. The simulation model was built in MATLAB/Simulink, and the correctness of the theoretical calculation for the proposed converter was verified by simulation results. Finally, the experimental prototypes of the proposed converter and the non‐isolated high step‐up (NHS) converter were built. Through the comparison of experimental results, the feasibility and validity of the design scheme for the proposed converter are verified. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

DC‐link capacitor is one of the most vulnerable passive components in the drive system of electric vehicle, so the condition monitoring of DC‐link capacitors can significantly improve the reliability of drive system and even driving safety. The existing monitoring methods are subject to the low accuracy, added hardware and the irreversible impact on system. Therefore, based on Back Propagation (BP) neural network with Improved Gray Wolf Optimization (IGWO), a parameter identification method for the DC‐link capacitor in electric vehicle inverter is proposed. In this method, the capacitance (C) is taken as health parameter. The A‐phase current and DC‐link capacitor voltage in electric drive system are taken as inputs, and the capacitance (C) is taken as output for condition monitoring. IGWO algorithm can be applied to obtain the optimal weights and thresholds. Ultimately, under four actual working conditions in electric drive system, the condition monitoring test is carried out. The results are compared and analyzed, which show that the monitoring using IGWO‐BP neural network has better performance. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

For an SF6 circuit breaker in capacitor bank‐making operation, the inrush current may cause serious erosion to its arcing contacts. In order to observe the characteristics of this erosion, an arc extinguish chamber of SF6 circuit breaker with Cu–W arcing contacts was designed, and experiments of capacitor bank making were carried out. The prebreakdown arcing duration and inrush current were measured, and the mass loss of the contact after 100 times of operation was calculated. Power–frequency‐withstanding voltage was measured after every 20 operations. The surface status, scanning electron microscope (SEM), and energy dispersive x‐ray spectroscopy (EDS) of the contact material were recorded. The characteristics and mechanism of arcing contact erosion in SF6 circuit breaker in the making process were then analyzed. Compared to the case of breaking high current, this analysis found two major mechanisms that lead to severe arcing contact erosion in the case of capacitor bank making operation, namely, the arc erosion due to prebreakdown current and the erosion of arc heated contact due to friction. The erosion after contact caused by mechanical friction occupies a relatively larger proportion in the mass loss of contact materials. Under the conditions of 3 m/s making velocity, 18 kA current peak, and less than 2 ms arcing duration, the mechanical wear mass loss rate is greater than 1.0 mg/C. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

By using stoichiometric, low-resistivity intermetallic compound composed of valve metals, it is expected that anodized capacitors with high heat resistance and high reliability can be realized. We therefore prepared a stoichiometric Al3Zr film by co-sputtering an Al-Zr composite target, and the electrical properties of the Al3Zr anodized capacitor were compared with those of Al3Hf capacitor from the viewpoints of reduction of oxide thickness and heat tolerance. It is shown that Al3Zr anodized film is also a very promising material for high-reliability thin-film capacitors, alongside Al3Hf capacitors. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 1–8, 2000 [ABSTRACT FROM AUTHOR]