Japanese railway signalling systems have gained a reputation for their high safety performance. As globalisation, more specific explanations for management measures taken to ensure safety will be required.

In this paper, we discuss the measures maintaining the high safety performance of these systems that are based on the domestic legal system. These include the safety management of railway operators, the system of the“Certified railway operator”, and organization of maintenance/condition monitoring.

In this paper, a method for extracting constant power from transformers on power lines is presented. The secondary side power equation is obtained based on the circuit equation for power superposition using a single-phase transformer. Using this equation, an area discrimination method of the speed versus torque characteristics of the permanent magnet synchronous motor and a power superposition control method in the area are proposed. To validate the proposed method, the discrimination method was verified via simulation and experiment with boundary conditions. Similarly, the power superposition control method was verified via simulation and experiment, with the command current controlled using a power estimator. The results verify the discrimination and power superposition control methods.

The electrification of power sources for various types of mobility is progressing. In particular, high power density is required for air mobility applications require high power density. To increase the output density of high-speed fan-drive motors, reducing the temperature rise of the motor is crucial. We investigated various techniques to improve the output density of the high-speed fan-drive motor using amorphous metal, which reduces iron loss during the high-frequency drive, and using an air-cooling structure with a high-speed fan. Thus, a maximum torque of 200mN·m was achieved at a current density of 40Arms/mm²; moreover, a power density of 13kW/kg was obtained. This report presents the findings of our investigation and the evaluation results of a prototype motor.

This study proposes a partial PAM inverter with power decoupling operation in discontinuous current mode for UPS. Simulation results indicate that THD of 0.27% was achieved in the inverter output voltage. Moreover, the second-order harmonic of the input power ripple reduced by 98.5% compared to the DC components.

This article introduces Power Electronics Laboratory at Department of Electrical and Electronic Engineering, Yamaguchi University.