In this study, the ringing phenomenon of gallium nitride-field effect transistor (GaN-FET) and silicon-insulated gate bipolar transistor (Si-IGBT) inverter excitations in a ring sample was thoroughly measured and analyzed by using a high-quality oscilloscope with a very high sampling rate of 5 giga-samples per second (GS/s). Owing to the rapid switching of the GaN-FET power devices in several nanoseconds and the ringing frequencies in the MHz range, the use of the high sampling rate of 5GS/s is necessary and useful for accurate measurement. The experimental findings and analysis reveal the following three key points: i) there are two possible types of high-frequency resonance phenomena, i.e., the first one caused by semiconductor devices and circuits and the other generated by the resonance with loads in use. ii) The ringing phenomenon because of the resonance under the load is considered to be due to the rising time of pulses that are caused by the rapid switching of the semiconductor devices. iii) The ability to measure and the two types of ringing phenomena depends on the intensity of the white noise of the measuring instrument.

In this study, we have conducted battery tests to understand the capacity deterioration characteristics of lithium-ion batteries so that railway onboard batteries can be utilized for electric power supply-demand-adjustment. We developed a control method to determine the conditions of charge-discharge amount of the onboard batteries, based on the deterioration test result. The developed method leads to the economical supply-demand-adjustment while avoiding excessive battery deterioration.

In the pursuit of advancing robotics and mobility, we are considering the implementation of energy transmission technology using power packets. By applying power packets to these mechanisms, both power and control signals can be transmitted through a single wiring system, which is expected to simplify the wiring and improve durability. We propose using a metal body instead of wires to conduct electrical power, which allows the omission of wiring and results in improvements in design and durability. In this study, we verify the body energizing technology that utilizes a power packet circuit. For this, we created a prototype of a rover equipped with six wheels.

The primary loop of the SCMaglev's WPT system has several distinctive features compared to other WPT systems. These include its length, order of several kilometers, its installation position close to the concrete roadbed and its working frequency near 10kHz. There were almost no findings and experiences regarding electric constants required for designing the electric resonance, theoretical considerations have been conducted to determine the constants, inductance and stray capacitance. The values obtained can be calculated using simplified methods and are close to the results obtained from the field test.