When electric trains operate between multiple stations with a fixed operating time, energy-saving operation can be achieved by determining the time-energy characteristics for each station and allocating operating time using an appropriate mathematical programming method. In the time-energy characteristic of high-speed trains, energy consumption tends to be proportional to operating time due to high-speed and extended period of constant-speed operation, and the energy characteristic of high-speed trains tends to be linear. Using this characteristic, this study proposes an energy-saving operation method for linear programming.

This paper proposes a novel torque ripple suppression control that uses an all-pass filter, expanding its application range to include medium to high rotational speeds. In conventional torque ripple suppression methods, a q-axis compensation current is generated to suppress the torque ripple. This current is superimposed onto the q-axis current command. The resulting q-axis current is PI-controlled. Therefore, the effectiveness of torque ripple suppression depends on the bandwidth of the PI controller. At medium to high rotational speeds, limited bandwidth of the controller impairs its ability to respond effectively, resulting in diminished suppression performance. Accordingly, this study focuses on the phase delay of the current control system and the proposed method compensates it using an all-pass filter. The simulation and experimental results indicate that the sixth-order torque ripple can be effectively suppressed by the proposed method in medium to high-speed ranges.

In this paper, we derive a method for calculating the constants of a mathematical model based on a numerical analysis of a double-winding squirrel-cage induction generator. The characteristics of a double-winding squirrel-cage induction generator were calculated using the constants determined by this method. The characteristics agreed well with those calculated directly using numerical analysis.

This study proposes a local path planning with turnabouts for mobile robots navigating narrow roads, utilizing a deep deterministic policy gradient with prioritized experience replay (PER-DDPG) algorithm. A narrow road is defined as one that is impossible for a robot without the use of turnabouts. Such roads are common in confined environments, including factories and historical areas. While previous research has addressed local path planning in narrow roads, it has typically been limited to simple non-branching scenarios. In contrast, this study extends path planning capabilities to more complex environments, including branching narrow roads. The proposed method uses PER-DDPG to generate feasible local paths with turnabouts. The effectiveness of the approach is validated through both simulations and real-world experiments.

Although recent research aims to extend the lifespan and reduce the maintenance requirements of railway electrical equipment, it remains difficult to quantitatively predict and evaluate equipment deterioration caused by corrosion and wear. In this study, we analyzed and evaluated the deterioration trends of messenger wires and hinged cantilevers in Shinkansen power facilities, where corrosion is the main deterioration factor. Messenger wires and hinged cantilevers are important components around the contact wire. A common issue with both is that, although the deterioration state of the equipment should be managed as a key indicator, the deterioration state in tunnels has not been evaluated. Therefore, in this study, the corrosion tendency of galvanized steel, which is the main material for both, was evaluated. No significant galvanization corrosion was observed, except in equipment directly exposed to water leakage. This indicates that if direct water leakage can be controlled, galvanized steel can be used continuously for more than 40 years.

This study presents a measurement method for obtaining accurate high-frequency magnetic properties of magnetic materials used as inductor and transformer cores in power electronics circuits. At high frequencies, such as in the MHz range, stray capacitances become significant between lead wires or between the lead wires and the magnetic core. These stray capacitances introduce errors into the measurement results and hinder the accurate determination of magnetic properties. This phenomenon is revealed through numerical calculations that quantitatively combined electric and magnetic field analyses. The results indicate that the conventional measurement method using a toroidal winding core exhibits high stray capacitance. To address this issue, a new method is proposed in which the lead wire passes through the center of the magnetic core without winding, thereby reducing stray capacitance. The effectiveness of this method is demonstrated through the presented analysis.