Jaehyoung Park

Autonomous Coil Alignment System Using Fuzzy Steering Control for Electric Vehicles with Dynamic Wireless Charging

An autonomous coil alignment system (ACAS) using fuzzy steering control is proposed for vehicles with dynamic wireless charging. The misalignment between the power receiver coil and power transmitter coil is determined based on the voltage difference between two coils installed on the front-left/front-right of the power receiver coil and is corrected through autonomous steering using fuzzy control. The fuzzy control is chosen over other control methods for implementation in ACAS due to the nonlinear characteristic between voltage difference and lateral misalignment distance, as well as the imprecise and constantly varying voltage readings from sensors. The operational validity and feasibility of the ACAS are verified through simulation, where the vehicle equipped with ACAS is able to align with the power transmitter in the road majority of the time during operation, which also implies achieving better wireless power delivery.

Generation of Magnetic Propulsion Force and Torque for Microrobot Using Wireless Power Transfer Coil

In this paper, we propose a microrobot powered by wireless power transfer (WPT) system which can generate propulsion force and torque as well as electrical energy to perform complex missions. The magnetic field and the induced current from the WPT coils can be utilized into the propulsion force and the Lorentz force for implementing rotational movement. The generated propulsion force and the torque are verified by 3-D finite-element simulations and experimental measurements.

Diffusion length in nanoporous TiO2 films under above-band-gap illumination

We determined the carrier diffusion lengths in TiO2 nanoporous layers of dye-sensitized solar cells by using scanning photocurrent microscopy using an ultraviolet laser. Here, we excited the carrier directly in the nanoporous layers where the diffusion lengths were found to 140 μm as compared to that of visible illumination measured at 90 μm. The diffusion length decreased with increasing laser modulation frequency, in which we determined the electron lifetimes and the diffusion coefficients for both visible and UV illuminations. The diffusion lengths have been studied in terms of the sintering temperatures for both cells with and without binding molecules. We found a strong correlation between the diffusion length and the overall light-to-current conversion efficiency, proving that improving the diffusion length and hence the interparticle connections, is key to improving cell efficiency.

A Resonant Reactive Shielding for Planar Wireless Power Transfer System in Smartphone Application

Demand and interest in wireless power transfer (WPT) have been rapidly increasing lately. However, WPT systems have problems with electromagnetic field (EMF) leakage, which has stimulated interest in methods to suppress EMF leakage levels. In this paper, we propose a compact resonant reactive shielding coil topology for reducing EMF in a near-field WPT mobile device application. The proposed shielding coil employs a closed loop and matching capacitors, and is demonstrated to dramatically reduce the leakage magnetic field from a WPT system. For validation, the proposed shielding was implemented with other shielding topologies and the EMFs were measured and compared. The analytical, simulation, and measurement results were all strongly correlated.

Propulsion and control of implantable micro-robot based on wireless power transfer

As implantable micro-robots become a promising solution for medical applications, the interests for micro-robot control are growing. However, most research has been focused on DC magnetic field control. In this paper, we propose a micro-robot powered by wireless power transfer system which generates propulsion force and torque as well as electrical energy to perform complex missions. The concept of propulsion and torque generation is explained and validated by simulation results.

Miniaturization of Implantable Micro-Robot Propulsion Using a Wireless Power Transfer System

Recently implantable micro-robots have been researched actively in the means of medical application. This micro-robot can be used for localized delivery and various forms of energy. Targeted drug delivery increases the concentration of drug in region of interest and reduce the risk of side effects in the rest of the body. In addition, the micro-robot can delivery heat energy to destroy unwanted cells and collect the images inside of the body to make an accurate diagnosis. Currently, most of research are use static magnet inside of micro-robot to generate propulsion force. This kinds of micro-robot can be implemented as nano-size, but the utilization of these are limited because of the it is not containing electrical energy source [1]. To receive the electrical energy, the micro robot using wireless power transfer system have been proposed. Unlikely conventional research which using motor actuator, generate propulsion using Lorentz force is pronounced [2].

High-Efficiency Wireless Power and Force Transfer for a Micro-Robot Using a Multiaxis AC/DC Magnetic Coil

In this paper, a high-efficiency wireless power transfer (WPT) and force transfer system for a micro-robot is proposed. Two-coil systems are employed to power the micro-robot. The two-coil parts are ac and dc, and each consists of an external source and a load coil inside the micro-robot. In the ac coil part, the external source coil generates a time-varying magnetic field that is received by the ac load coil in the micro-robot as electrical energy. In the dc coil part, the external source coil is used as an electromagnet, which is used to generate propulsion force for the micro-robot. Through the proposed system, both the efficiency of electrical energy transfer and the generation of propulsion force can be significantly improved. The feasibility of the proposed approach was verified through simulation and experimentation results.

Generating propulsion force in micro-robot using wireless power transfer system

In this paper, a micro-robot capable of receiving both electrical energy and mechanical energy is proposed. The electrical energy is transferred using wireless power transfer system, and the mechanical energy is represented as propulsion force. To generate Lorentz force which is the source of propulsion force, the phase difference between source current and load current are controlled by changing capacitance to avoid LC resonance. These proposed concepts are explained with theoretical analysis and validated by simulation results.

A novel shielding coil for electromagnetic field(EMF) reduction of wireless power transfer in laptop computer

In this paper, we proposed an effective coil design for canceling the electromagnetic field noise from the wireless power transfer system by using shielding coil in transmitter and receiver for laptop computer application. EMF noise was significantly reduced with negligible change in induced voltage by using proposed coil with shielding coil near the coil. Difference between exiting coil and shielding coil is proven by simulation. And the guidelines to positioning of the shielding coil and the pros and cons of the shielding coil designs are discussed.

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.