The concept of carbon neutrality has attracted significant attention, leading to a growing demand for circuit breakers that can be installed in DC electric power systems. Our research group has proposed a safe, rapid, cost-effective, and compact circuit breaker that combines the high current-limiting performance of fuses with the high-speed interruption function of power semiconductors. The objective of this study is to further develop this device into a system that can be defined as a true “circuit breaker” by introducing a fuse exchanger using a linear motor. The integration of the exchanger within the circuit breaker enables three critical functions: reclosing the current path, interrupting small currents, and preventing fuse explosions. To achieve these functionalities, a feedback switching control method was developed and experimentally verified under high-voltage conditions.

This paper presents an estimation method for radiated EMI at far-field from an inverter unit in a variable speed drive (VSD) system. This method is based on the radiation model of an electric dipole and propagation properties in a semi-anechoic chamber for the 10-m standard test. Since the radiated emission test is conducted in a semi-anechoic chamber with a metal ground plane as the floor, the radiated EMI at far-field comprised direct and reflected waves from the equipment under test. To evaluate the pass/fail criteria in the EMC standard, the standard electric field intensity was introduced to determine the maximum radiated electric field as the receiving antenna height was varied. The estimation error of the proposed method was quantitatively analyzed by comparing the measured radiated EMI with the calculated value at the 10-m far-field from the inverter unit in the VSD system.

An Electronic Toll Collection (ETC) lane is equipped with multiple vehicle detectors, each of which has a number of optical sensors arranged in the vertical direction to detect all vehicles without fail. Various devices are controlled by the vehicle detection information of these vehicle detectors as a trigger. The optical sensors arranged in the vertical direction in each vehicle detector provide one-dimensional data at each sampling time when a vehicle passes through an ETC lane. By arranging these data in chronological order, a binary image of the vehicle's side (which we call the vehicle shadow) can be obtained. In this study, we focused on this vehicle shadow data and investigated whether it could be used to classify the vehicle type.

In this study, we proposed a vehicle type classification method for vehicles passing through an ETC lane as a new way of using the data obtained from vehicle detectors installed in an ETC lane, and examined its applicability. In particular, we constructed a vehicle type classification algorithm employing the adaptive boosting algorithm, and conducted the vehicle type classification experiment. In this experiment, a high classification rate of 98.37%, corresponding to the five vehicle types generally running on expressways, was achieved.

For electric micromobility applications, an axial-length shortening is required for the coil winding area of the distributed winding stator. In this study, a novel printed circuit board (PCB) coil-end stator, composed of bar-type conductors and a multi-layer printed circuit, has been proposed. The schematic design of the PCB stator and the multi-layer coil pattern has been explained. The structure of the prototype, including the assembly method, has also been presented. The torque characteristics of the prototype when the current vector is controlled have been studied. In addition, its efficiency map has also been reported.

This paper presents an active gate driver (AGD) circuit with dynamically adjustable input capacitance. AGD circuits optimize electromagnetic interference (EMI) and switching losses generated during switching by arbitrarily controlling the driving force of power semiconductor devices. However, conventional AGD circuits require complex control mechanisms, increasing circuit size and cost. The proposed method introduces a capacitor between the gate and emitter during the insulated gate bipolar transistor (IGBT) switching period, enabling switching characteristics to be controlled by varying the input capacitance. The effectiveness of the proposed method was demonstrated through experimental verification. The results indicate that this approach enhances the trade-off between high-frequency electromagnetic noise generated during IGBT switching and turn-off switching losses.

Continuous voltage compensator (CVC) has been recently developed to improve the power quality of distribution lines. A CVC comprises series and shunt static power converters with transformers, and its circuit topology is based on an unified power flow controller (UPFC). Features of theCVC include fast active power control and precise imbalanced voltage compensation using a series converter, which are not accomplished by the conventional step voltage regulator (SVR) and thyristor voltage regulator (TVR) based on tap-change control. Further, the CVC contributes to stabilizing distribution lines by supplying reactive power and negative sequence current from the shunt converter. The details of the control strategies of series and shunt converters are proposed, and the validity of proposed strategies is verified by fabricating a 200V, 20kVA scale-downCVC prototype. A 6.6kV, 3,300kVA full-scale CVC has been developed for comparing the voltage controllability with the conventional TVR and effectiveness of the CVC demonstrated in the field test.