Many types of continuous automatic train protection (ATP) systems, which are called automatic train control (ATC) systems in Japan, have been used over the years for safe train operations of Japanese rapid transit. In a preceding paper, we proposed a new ATC system that can offer a shorter train headway without either storing track profiles on trains or installing transponders on tracks, which are required on existing ATC systems to achieve such a shorter headway. As well as describing the basic concept and framework, we demonstrated effectiveness of the ATC system in that paper. However, a detailed discussion on the track-to-train transmission of required information to implement functions of the proposed system was not given. This paper analyses the impact of the information capacity on the headway and speed of trains under the conventional transmission method, proposes a new method that eliminates the negative impact on train operations providing the required capacity of information, and evaluates effectiveness of the new method.

Alternating Current (AC) mill motors for steel rolling were introduced around 1990.

Concerns existed regarding about the progress of deterioration, and there was an urgent need to establish technology to quantitatively evaluate the deterioration status and estimate the remaining life.

Here, we report a technology to estimate the remaining life of an AC mill motor using an estimation formula.

With a declining birthrate, aging population, and shrinking working population, the cost of train operations must be reduced to maintain the railway network. A solution for overcoming this problem is to introduce automatic train operation (ATO). ATO systems, which are equipment for automated driving control under the protection of an automatic train control (ATC), a continuous type of automatic train protection (ATP), are introduced in specific types of rail lines, such as automated guideway transit (AGT) systems or subway systems in Japan. A new type of ATO systems operated by staff who are not required to have a driver's license is required to reduce operating costs further. The authors have developed an ATO system based on automatic train stop (ATS)-DK which is an intermittent ATP and equipped with continuous speed check. This system has achieved the first automatic operation in the ATS line, which conventionally has required ATC, and also the first GOA2.5 in which an attendant other than the driver performs emergency stop operations at the front of the train. This paper describes the details of the study, the progress of the demonstration operation, and the effects of the introduction of the GOA2.5 system.

High-power wireless power transfer (WPT) systems are required for rapid charging of electric vehicles. In a high-power WPT, discharge between windings and magnetic saturation in the transmission coils inhibit power amplification. Hence, conventional coil design methods with fixed physical dimensions cannot be applied to the design of a high-power WPT system. Therefore, in this study, a new dimensional design for copper pipe coil is proposed. In the proposed design method, flexibility is introduced in the physical dimensions of the transmission coil and a parametric analysis is performed to determine a combination of dimensions that can transmit the target power. A copper pipe coil for 500-kW power transmission is dimensionally designed using the proposed design method, and the design is validated via analysis and experiment.

Various methods for estimating magnet temperature in interior permanent magnet synchronous motors have been proposed to further enhance their performance. However, the effect of dimensional variations of motor parts on the accuracy of temperature estimations has been infrequently addressed. In this study, we investigated the effect of dimensional variations on the accuracy of magnet temperature estimated from voltage induced in the motor, applying electromagnetic field analysis. We obtained following results: (1) The maximum estimation error was 14.5°C owing to the variations in the IEEJ D-model; (2) the magnet slot thickness and air gap strongly affected the accuracy, and d-axis inductance also significantly changed; (3) the air gap had approximately seven times the effect on the amount of the inductance change as that of the slot thickness. These results can be qualitatively explained using the equivalent magnetic circuit method, although quantitative differences occurred in estimations of the analysis because some parts of the magnetic flux are not considered in this method.

Our research focuses on sensorless control systems for induction motors and permanent magnet synchronous motors (PMSMs), as well as on control and drive algorithms for dual three-phase PMSMs. The research group consists of one faculty member and four students.