This paper shows a circuit model that can accurately simulate the differential-mode and common-mode attenuation characteristics of a three-stage EMI filter connected to high-current power converters. Passive components such as common mode choke coils and capacitors are modeled as high-frequency equivalent circuits based on impedance measurement results. For the coils that exhibited characteristics that are difficult to fit manually, vector fitting is used to derive a highly accurate equivalent circuit. The mutual inductance between input and output loops, which has a significant impact on common mode characteristics, is calculated based on the results of electromagnetic field analysis using a 3D CAD model. The combined circuit simulation model is able to predict the filter attenuation characteristics with an accuracy of less than 10dB error for both modes.

This paper focuses on the static and dynamic characteristics of Si IGBT/SiC MOSFET hybrid multi-parallel connected devices to improve power conversion efficiency over a wide range of load conditions in power electronics applications. The results demonstrate that the studied Si/SiC hybrid device can improve conduction losses and turn-off losses compared to muti-parallel IGBTs. This study also reveals that the transient current sharing characteristics specific for the hybrid device can deteriorate its electromagnetic noise source performance.

This paper sets up a common model for electromagnetic field calculations in low frequency bands, and describes the comparative results of calculations conducted using multiple simulation tools. The human body models used for the calculations include a simplified human phantom (IEC62233, 2005) and the TARO (NICT) model. Evaluations were carried out using commercial electromagnetic field analysis software and custom program codes, and the results were compared and discussed.

Our research project aims to clarify actual human exposure levels to radio frequency electromagnetic field (RF-EMF) in daily life, as well as investigate risk communication methods using the RF-EMF exposure levels. In this project, we conducted to measure the micro-environmental RF-EMF exposure levels across surrounding different environments which are major railway station areas, shopping streets, residential areas, parks in urban and suburban areas because of acquiring the detailed data supporting an understanding of the micro-environmental personal RF-EMF exposure levels in Japan. Additionally, in order to evaluate a measurement method using a portable measuring device, we conducted measurements by traversing a designated route way and back. The results showed that RF-EMF exposure levels in urban areas were significantly higher than those in suburban areas. Among the surrounding environments, the major railway station areas had the highest RF-EMF exposure levels, followed by the shopping streets, the residential areas, and the parks. Furthermore, the micro-environmental RF-EMF exposure levels by the way-and-back measurement showed no significant difference between them. The results of these measurements confirm that outdoor mobile measurements using a portable measurement device are effective for assessing micro-environmental RF-EMF exposure levels during daily activities.

Previously published studies have shown that the radiated electric field due to collision ESD (electrostatic discharge) between metal spheres charged below 1000 V increases as the spark voltage decreases, reaching a maximum around 600 V before declining further. However, the reason for this specific behavior remains unclear. In this paper, the underlying cause is considered based on the mechanism using the modified Paschen curve for microgaps in air at atmospheric pressure, derived by Radmilovic. This curve predicts a sharp reduction in spark voltage below the Paschen minimum due to electron field emission from the cathode. For spark lengths above the Paschen minimum, we assume that the deviation of the spark voltage from the standard Paschen curve is due to a breakdown mechanism dominated by field-emitted electrons. By applying Radmilovic's theory to determine a threshold value of the local electric field for initiating field emission, we verify that for estimated spark lengths below about 600 V, the spark voltages deviate downward from the standard Paschen curve, decreasing along the corresponding theoretical Radmilovic curve. Consequently the breakdown potential gradient does not increase significantly as the spark voltage decreases, limiting the intensity of the radiated electric field during collision ESD.