In Frontiers in Education Committee, we are working on widely problems of engineering education in present-day Japan. About education or social contribution, there are many problems which should be solved, coped with and reformed, and we have put up 18 themes education and research. This paper explains our activity of 2019-2020.

The main objective of HEE is to examine the direction in which electrical engineering should move in the years ahead by studying the past. Electrical engineering history constitutes the basis of technologies that we should develop. It is the starting point from which we should approach the future. This paper introduces recent activities of the committee.

This report briefly presents activities of Technical Committee on Electromagnetic Theory (EMT), IEEJ. Our committee is now implementing the activities on 2020, which includes three times of the technical committee meeting and three times of technical committee conference. The report also contains four research topics presented in the technical committee meeting on EMT.

The technical committee on electromagnetic compatibility (EMC) was established under the Fundamentals and Materials Society (FMS), the Institute of Electrical Engineers in Japan (IEEJ) in 1999. Since then, researches and investigations related to this field have been conducted actively in the committee. In this report, trends and current activities in the research field of electromagnetic compatibility are summarized.

This report introduces recent activities of the Technical Committee on Electrical Discharges, Plasma, and Pulsed Power (EPP). The major research subjects and aims of the technical committee on EPP, and the recent activities of the technical committee, such as technical meetings, international conferences, investigation committees are reported.

This article reports the topics of the field in light application and visual science, the activities of the technical committee (TC-LAV) and the introduction of research of technical meeting on light application and visual science of IEEJ.

The IEEJ Technical Committee on Instrumentation and Measurement has explored key technologies in this field through technical meetings and research committees. Its recent activities and some leading research results are presented.

This article picks up the topics at the 9^th International Symposium on Electrical Insulating Materials (ISEIM2020) hosted by Technical Committee on Dielectrics and Electrical Insulation (TC-DEI) in IEEJ in order to overview the latest trend and front line in this research field. Under COVID-19 coronavirus pandemic, ISEIM2020 was held on September 13-25, 2020, as Virtual Web Symposium with 210 participants and 168 presentations (incl. workshop and digest reports).

Recently the number of integrated superconductor qubits and the fidelity in the qubit control are rapidly advanced. Besides the quantum supremacy, which is a remarkable milestone for realizing a large-scale quantum computer, was verified. However, for further increase in the scale of the quantum computer, control circuits to manipulate and read out the qubit state at low temperatures are indispensable to reduce the number of wires connecting the qubits at low temperatures with electronics at room temperature. In this report, recent research activities on qubit control circuits operating at low temperatures are reviewed.

The authors describe the recent activities of the Technical Committee on Magnetics, IEEJ. In this paper, the recent research and development on the advanced permanent magnet materials and their applications are reported.

In this paper, we undertake the numerical calculation of 50-Hz magnetic fields on three-dimensional orthogonal equidistant grids. The usual calculation method using the Biot-Savart law (BS) is accelerated by the Barnes-Hut tree method executed in reverse order (TMR). This method reduces the computation time from O(MN) to O(MlogN) + O(N), where N is the number of calculation points and M is the number of infinitesimal source current elements. Adopting a tree structure corresponding to the grid structure of calculation points further reduces calculation time. Two parallelization schemes of TMR, TMR1 and TMR2, are implemented to investigate computational performance. The calculation time, accuracy, and required memory capacity were investigated by calculating the field distribution generated by the Helmholtz coil and solenoid-like coil. The speedup of the TMR2 compared to the BS ranged from 2693 to 32391, when N and M were 1400³ and 2×10⁶, respectively. It is concluded that this method is efficient and practical for magnetic-field calculation on three-dimensional orthogonal equidistant grids.

Polytetrafluoroethylene (PTFE) has excellent characteristics. By utilizing these characteristics, PTFE is applied in various fields. In recent years, PTFE has attracted attention for the application to a flexible printed circuit board, however, PTFE exhibits the poor adhesion against other materials. To improve adhesion, the chemical surface modification and removal of a low molecular weight fragile layer are required to improve adhesion. In addition, to prevent a transmission loss due to high frequency signals, the surface smoothness has to be maintained.

In this study, the surface modification was performed by Ar plasma treatment and Ti or Cu thin films were coated onto the surface-modified PTFE by a sputtering method. These processes were performed consistently in a high vacuum under 5.0×10^-4 Pa. The Ti or Cu thin film adhesion on the treated PTFE was investigated by a scratch test with a continuous load of 0-0.98 N. The optimum adhesion of a Cu film was obtained by 180 s in an Ar plasma treatment time at 200 W in an input power. The obtained Cu films on treated PTFE satisfied the condition of a high-frequency printed circuit board about surface roughness or electrical conductivity and also it was anticipated these Cu thin films prepared by sputtering play the role of a seed layer for the wet plating film formation.

This paper described partial discharge (PD) current waveforms in SF₆ gas measured with a super high frequency wideband measurement system (SHF_PDPW system) with changing the electrode system to control the electric field utilization factor in order to statistically clarify the steeped pulse properties of the negative PD current pulses with a few tens picosecond order at the rising part, i.e. the minimum measured rise time was 30ps and the averaged ones were 45ps to 513ps depending on the utilization factor. The formation mechanism of such picosecond steeped rising part was discussed based on ionization process and electron movement in the critical electric filed by taking the influence of electron mobility as well as the frequency properties of the measurement system into consideration.

A high voltage and high current pulse switch using avalanche mode thyristor has been developed for the high voltage pulse generator. When the break-over voltage is applied to a thyristor, the thyristor turns on without the gate input current. We call avalanche mode thyristor (AMT) which operates such a switch mode. AMT has many advantages, for example, turn on function without trigger input circuit in the series connection, high speed switching characteristics, etc. A magnetic switch using the saturation of the core is adopted for the high current pulse shaping. 12 stages of AMTs generate 11kV and 1.36kA with 260ns pulse width. A high voltage pulse has been produced up to 65kV, 43A by using the AMT pulse generator and a pulse trans. The behavior of AMT and the performance of the circuit are discussed.

Space charge accumulation behavior in fullerene added epoxy resin is observed at high temperature under high voltage. Space charge accumulation is said that it strongly affect the dielectric breakdown of insulating materials. Since epoxy resins are used for sealing materials of power semiconductors, it is important that space charge does not accumulate in them even at high temperature under high electric field, in which the sealing materials are suffered in the actual usage of the power electric devices. Recently, the research on the space charge accumulation characteristics of insulating materials with nano size filler called nano-composites has been enthusiastic topics, because it has been reported that the amount of the space charge accumulation was reduced by adding some kind of nano-size filler to the insulating materials. Particularly, fullerene is remarkable because they can easily obtain high dispersibility and have high electron accepting properties. From the measurement results, it is found that the adding of fullerene is effective to prevent the space charge accumulation even at high temperature under high DC stress.

Vanadium dioxide (VO₂) thin films were fabricated by metal-organic decomposition (MOD). To utilize a carbon thermal reduction for obtaining a VO₂ composition, the precursor films were fabricated at the temperature T_p from 300 to 380ºC in a N₂ atmosphere. From the measurement results of XRD, diffraction peaks indicating VO₂ phase were observed with a wide range of firing temperatures from T_f=560 to 620ºC. Furthermore, the peaks indicating VO₂ phase were also observed with a wide range of firing time from t_f=15-45 min. Regarding the surface morphology of the films, the nanoparticles of 100-200 nm were densely packed although small spaces existed between the particles. The R-T characteristics of the films indicated the phase transition with a rapid resistance change of about three orders of magnitude and hysteresis loop. From these experimental results, it was found that wide windows of firing conditions for fabricating VO₂ thin film can be obtained in the MOD process using the carbon thermal reduction.

This paper reports a power loss calculation method for magnetic components in power converters. The differences in B-H loop areas are analyzed and discussed in case of sinusoidal waveform and square wave voltage excitation. Relying on the output results, iron loss calculation method based on square wave excitation is proposed. Experimental results show that the proposed iron loss calculation method is accurate compared with the traditional method using Steinmetz's equation. In addition, the proposed method reduces the calculation procedure compared with the method using Steinmetz's equation. The proposed iron loss calculation method is very practical and beneficial for converter designers.

In order to determine the effective temperature condition for artificially accelerating propagation of harmful water trees in insulation of 3.3 to 77 kV XLPE cables, an AC voltage of 13 kV and 1200 Hz was applied to a 22 kV XLPE cable removed from service at room temperature, 50°C, 60°C and 70°C, and under the heat cycle conditions between room temperature and 50°C, 60°C or 70°C. As a result, it was found that bow-tie water trees propagated up to a few mm at 70°C and under the heat cycle condition between room temperature and 70°C, and shapes of bow-tie water trees were narrow and long like those of harmful water trees. Factors that were effective for accelerating water tree growth were discussed with the results of thermal, mechanical, and X-ray analyses and an evaluation of oxidation of the XLPE insulation. In addition, AC withstand voltage tests were performed for the cable samples after 300 days of water tree degradation at 70°C and under the heat cycle condition between room temperature and 70°C.

A friction generator was firstly introduced to Japan in 1765 in a book describing about European culture. This generator was called “Erekiteru (Oelekitere)” in the book and introduced as a medical equipment. Hiraga Gennai got a broken Erekiteru and was successful in restoring it in 1776. This is the Japan's first electric machine. After that, a lot of Erekiteru were domestically produced and sold in Japan. Sometimes Erekiteru were used in show business and people at that time enjoyed it. On the other hand, intellects at that time thought that Erekiteru were scientific instruments to simulate natural phenomena.

The cross-linked polyethylene (XLPE) cable has been used for DC transmission lines. We have been developing the DC XLPE cable for a few decades, and proved its quality and reliability through the research and development process. In 2012, we delivered the 250 kV DC cable, making it the world’s highest voltage DC XLPE cable at that time and the world’s first one to be applied to a line commutated converter system. Following the project, we has recently completed the construction of a 400 kV HVDC XLPE cable system, the highest voltage in the world for an HVDC-XLPE cable system, for NEMO Link, which connects the UK and Belgium. We has also completed construction of the new HVDC Link with 250 kV HVDC XLPE cable, which increases transmission capacity between Honshu and Hokkaido in Japan. The route length of this HVDC cable system is the longest in the world for an inter-strait tunnel. These DC XLPE cable has an allowable continuous conductor temperature of 90 degrees Celsius and withstands polarity reversal of voltage. This cable will meet the various needs of DC transmission that are expected to increase in the future.