Hyunho Park

Design and Analysis of a Resonant Reactive Shield for a Wireless Power Electric Vehicle

In this paper, we propose the concept and design methodology for a resonant reactive shield for the reduction of magnetic field leakage from a wireless power transfer (WPT) systems. By using LC resonance, the reactive shield can generate a cancelling magnetic field to reduce the incident magnetic field from WPT coils and effectively reduce the total magnetic field without consuming additional power. The shielding effectiveness of the resonant reactive shield and its effect on WPT efficiency are analyzed with simulation and measurements. For practical application to wirelessly charged electric vehicles, an automatic tuning system for the resonant reactive shield is also proposed and implemented. The effectiveness of a resonant reactive shielding is verified by experiments in a wirelessly charged electric bus.

A Three-Phase Wireless-Power-Transfer System for Online Electric Vehicles With Reduction of Leakage Magnetic Fields

Wireless charging of electric vehicles based on wireless power transfer (WPT) has become increasingly popular in recent years. However, a leakage electromagnetic field (EMF) that affects other electronic devices or the human body is inevitably generated from the coils of a WPT system, and requirements regarding the suppression of the leakage EMF are increasing. In this paper, we propose a novel three-phase power line in a WPT system for the reduction of the leakage EMF. The proposed structure employs six power lines to reduce the leakage magnetic flux. This structure is compared with conventional power line structures with respect to induced voltage and magnetic field distribution. We also present analytical solutions of the EMF for the proposed and conventional power line structures. These solutions are then compared with numerical solutions using 3-D finite-element analysis and good agreement is demonstrated. The results of the numerical analysis indicate that the proposed power line can significantly reduce the leakage magnetic field from a WPT system. For verification, the proposed and conventional power lines are implemented and the EMFs are measured. A strong correlation between the numerical and experimental results is exhibited.

A Magnetic-Field Resonant Probe With Enhanced Sensitivity for RF Interference Applications

High-sensitive field probes are highly desirable for radio-frequency (RF) interference studies, where ultralow noise levels are of interest. By incorporating an LC resonant circuit in a differential-loop probe, together with a Marchand balun, a magnetic-field probe with enhanced sensitivity is developed. Its equivalent circuit model and design methodology are established. The design is validated by measurements. The measured relative sensitivity in terms of |S21| of the proposed probe increases by approximately 8.63 dB at the resonant frequency of 1.575 GHz compared to that of a conventional design. The advantage of the proposed probe is validated through its application in the measurement of a microstrip trace and a real-world cell phone design.

Magnetic resonant wireless power transfer for propulsion of implantable micro-robot

Recently, various types of mobile micro-robots have been proposed for medical and industrial applications. Especially in medical applications, a motor system for propulsion cannot easily be used in a micro-robot due to their small size. Therefore, micro-robots are usually actuated by controlling the magnitude and direction of an external magnetic field. However, for micro-robots, these methods in general are only applicable for moving and drilling operations, but not for the undertaking of various missions. In this paper, we propose a new micro-robot concept, which uses wireless power transfer to deliver the propulsion force and electric power simultaneously. The mechanism of Lorentz force generation and the coil design methodologies are explained, and validation of the proposed propulsion system for a micro-robot is discussed thorough a simulation and with actual measurements with up-scaled test vehicles.

Selective Epitaxial Growth of Silicon for Vertical Diode Application

Selectivity control in silicon selective epitaxial growth (SEG) for deep contact patterns, which is one of the key processes for silicon-based stacked devices and cell switches for next generation memories, was studied. Absolute values of selectivity loss during silicon SEG using the most popular H2/dichlorosilane (DCS)/HCl gas system were evaluated using a commercialized inspection tool in 200 mm wafers with real contact patterns. It was revealed that HCl/(DCS+HCl) ratio and the contact structure played a crucial role in suppressing selectivity loss. The number of selectivity losses in an entire wafer was less than 100 when the HCl/(DCS+HCl) ratio was larger than 0.41. The vertical pn diode prepared using the silicon SEG process with elaborate selectivity control showed more remarkable electrical abilities to accommodate current flow than polycrystalline silicon (poly-Si), including the ideality factor and swing, and reverse leakage current.

Electrical Extractions of One Dimensional Doping Profile and Effective Mobility for Metal--Oxide--Semiconductor Field-Effect Transistors

In this study, an attempt is made to provide a framework to assess and improve metal–oxide–semiconductor field-effect transistor (MOSFET) reliability from the early stage of the design to the completion of the product. A small gate area has very small capacitances that are difficult to measure, making capacitance–voltage (C–V) based techniques difficult or impossible. In view of these experimental difficulties, we tried electrical doping profiling measurement for MOSFET with short gate length, ultra thin oxide thickness and asymmetric source/drain structure and checked the agreement with simulation result. We could get the effective mobility by simple drain current versus drain bias voltage measurement. The calculated effective mobility was smaller than expected value and we explained some reasons. An accurate effective mobility for asymmetric source–drain junction transistor was successfully extracted by using the split C–V technique, with the capacitance measured between the gate and source–drain and between the gate and the substrate.

Electrical Failure Analysis Methodology for DRAM of 80nm era and beyond using Nanoprober Technique

In this paper, the electrical failure analysis for DRAM of design rule as 80 nm and beyond by using nanoprober technique was described. We have successfully measured and evaluated electrical characteristics of periphery and cell array transistors of 80 nm DRAM using nanoprober. Measurements for Metal Contact (MC), Bit Line (BL) and Bit Line Contact (BLC) probing were proceeded and compared with Test Element Group (TEG) probing results. Interconnect Characterization Environment (ICE) simulation was also carried out to verify the current decrease of BLC probing results. Measurement for characteristics of memory cell array transistors, which had 150 nm pitch, of 80 mn DRAM was possible. It is concluded that a direct probing method using the nanoprober technique was an useful tool of the electrical failure analysis for 80 nm DRAM and beyond generations.

Generation of magnetic propulsion force using wireless power transfer coil

A micro-robot is a promising device for minimally invasive surgery or drug delivery inside of the body for medical purpose. Due to its small size, the micro robot should float in the blood vessel to destination. Therefore, the propulsion mechanism of micro-robot have become an active area of study these days [1][2]. Recent studies of the propulsion of these robots have focused on the insertion of permanent magnets with Helmholtz coil which can generate magnetic field for propulsion of the micro-robot. However, this type of propulsion system has limited in that the DC magnetic field delivers propulsion but does not deliver any electric power to the robot [3]. Inevitably, the micro-robot only perform limited mission-like drilling and moving without any electric power sources [4]. If propulsion and power can be delivered to the micro-robot at the same time, the robot can contain active devices and can thus perform much more complex and important medical missions.

Optimization design of toroidal core for magnetic energy harvesting near power line by considering saturation effect

Recently, magnetic energy harvesting technologies have been studied actively for self-sustainable operation of applications around power line. However, magnetic energy harvesting around power lines has the problem of magnetic saturation, which can cause power performance degradation of the harvester. In this paper, optimal design of a toroidal core for magnetic energy harvesters has been proposed with consideration of magnetic saturation near power lines. Using Permeability-H curve and Ampere’s circuital law, the optimum dimensional parameters needed to generate induced voltage were analyzed via calculation and simulation. To reflect a real environment, we consider the nonlinear characteristic of the magnetic core material and supply current through a 3-phase distribution panel used in the industry. The effectiveness of the proposed design methodology is verified by experiments in a power distribution panel and takes 60.9 V from power line current of 60 A at 60 Hz.Recently, magnetic energy harvesting technologies have been studied actively for self-sustainable operation of applications around power line. However, magnetic energy harvesting around power lines has the problem of magnetic saturation, which can cause power performance degradation of the harvester. In this paper, optimal design of a toroidal core for magnetic energy harvesters has been proposed with consideration of magnetic saturation near power lines. Using Permeability-H curve and Ampere’s circuital law, the optimum dimensional parameters needed to generate induced voltage were analyzed via calculation and simulation. To reflect a real environment, we consider the nonlinear characteristic of the magnetic core material and supply current through a 3-phase distribution panel used in the industry. The effectiveness of the proposed design methodology is verified by experiments in a power distribution panel and takes 60.9 V from power line current of 60 A at 60 Hz.

Effect of air-gap between metal strips and a ferrite plate on magnetic shielding

In this paper, the effect of air-gap between the metal strip and ferrite plate on magnetic shielding in the presence of a periodic line current source is analyzed in two-dimensional and approximate model of the WPT coils in electric vehicles and mobile devices. An analytical method based on Fourier transform and mode matching technique is proposed to investigate the penetration of quasistatic magnetic field into the ferrite plate and metal strips.