Eun S. Lee

A wide-range ubiquitous wireless power environment, called a ubiquitous Wi-power zone, where any electric devices can be charged by three-dimensional (3-D)-omnidirectional wireless charging, is newly proposed in this paper. By virtue of the proposed direct-quadrature (DQ) transmitting (Tx) coils composed of multiple Tx modules with same size, a ubiquitous Wi-power zone having the transmitting (Tx) coils can be provided over wide-range 3-D space. In this area, a number of electric devices can be

Direct and quadrature (DQ) rotating magnetic-field-based transmitting (Tx) coils for wireless charging of multiple internet of things (IoT), which are broadly distributed over three-dimensional (3D) spaces, are newly proposed in this paper. The proposed Tx coils provide a uniformly distributed DQ magnetic field environment so that numerous IoT, such as active radio frequency identification (RFID) tag, electric shelf label (ESL), appliances, and various sensors connected to internet, are charged

Solid-state transformers (SST) are emerging technologies to replace the conventional low-frequency main transformer (MTR) in railway vehicles. In order to isolate the load side from the AC 25 kV high-voltage (HV) side and to reduce the whole size of the SST, HV insulation and high-frequency transformers should be used in DC/DC converters. Furthermore, due to the severe constraint of installation space and difficulty of heat dissipation management in the bottom of railway vehicles, high-power den

A dipole-coil-based inductive power transfer (IPT) with a reflector, which first adopts the variable switched capacitance for load power regulation under very wide-range distance variation between transmitter (Tx) and receiver (Rx) coils, is newly proposed. The resonant frequency of the LC tank of the proposed IPT can be appropriately modulated by the variable switched capacitance with reliable zero-voltage-switching (ZVS) operations. Therefore, even though the distance changes very widely, load

Inductive power transfer (IPT) systems based on segmented transmitter (Tx) coils are newly proposed in this article. These IPT systems can deliver wireless power to multiple transport robots in an electrified monorail system (EMS) for continuous transportation missions. Considering the one-dimensional long-line driving characteristics of the transport robots having receiver (Rx) systems, a segmented Tx coil structure is introduced so that flexible Tx installation, easily Tx coil fabrication, and

An LED driver compatible with various electronic ballasts that are currently commercially used is newly proposed, which adopts a variable switched capacitor by controlling the switching duty cycle for LED power regulation. The resonant frequency of an LC resonant tank of electronic ballasts can be changed, which makes the proposed LED driver versatile for electronic ballasts for various switching frequencies. In this way, the fluorescent lamp is replaced with an LED lamp, where the electronic ba

New passive LED drivers that can reduce the total harmonic distortion (THD) significantly by LC parallel resonance are proposed. Using an inductor and three capacitors, called LC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , novel characteristics, such as high power efficiency and power factor (PF) with extremely long life time are achieved. The proposed LED drivers have a temperature-robust characteristic, because their power is hardly

The solid-state transformer (SST) can be a promising solution to replace the conventional 50- or 60-Hz main transformer (MTr) for railway vehicles. Unlike the existing SST technologies for stationary power applications, the SST applied to railway vehicles requires severe constraint of installation space and intensive management of heat dissipation. To optimally design the SST module applied to the railway vehicles, which is one of the major components in the whole SST system, the optimal magneti

In this article, a switching frequency-modulation-based inductive power transfer system that provides wireless charging of the scooters by magnetic in-band communication is newly proposed. Although the transmitter (Tx) and receiver (Rx) coils are misaligned, the scooters can be freely charged in the charging station by the proposed frequency modulation method without additional power converters in the Tx and Rx sides. In order to implement frequency modulation control, the Rx side can transmit t

In this paper, an integrated transformer design methodology for dual-active-bridge (DAB) converters, which basically utilize leakage inductance so as to substitute a cumbersome inductor in the conventional DAB converters, is newly proposed. The proposed integrated transformer with integrated leakage inductance inherently includes leakage inductance and magnetizing inductance, whose values can be appropriately selected by modulating the number of turns and the center-core air-gap. Based on the th

In order to design power converters and wireless power systems using high-frequency magnetic materials, the magnetic characteristics for the inductors and transformers should be specified in detail w.r.t. the operating frequency. For investigating the complex permeability of the magnetic materials by simply test prototypes, the inductor model-based calculation methodologies for the complex permeability are suggested to find the core loss characteristics in this paper. Based on the measured resul

The coil design of the inductive power transfer (IPT) for a transmitter (Tx) and receiver (Rx) is crucial to determine the performance of the IPT. Considering core loss and copper loss of the Tx and Rx coils, which are major loss terms of the whole IPT system, determination of the winding turns for the Tx and Rx coils becomes a key factor for maximum power transfer design of the IPT coils. In this paper, an optimal turns design of IPT coils for laptop wireless charging applications with a maximu

As the automated guided vehicles (AGVs) play an important role in automated logistics systems, the wireless power transfer (WPT) technologies become a viable solution to provide the AGV with the automatic power charging service. In order to install the WPT systems to the small confined space in the AGV, a 2-D thin coil design is necessary for the receiver (Rx) system installed in the AGV. To greatly reduce the thickness of the Rx coil, including resonant capacitors, an ac/dc rectifier, and dc-li

Wireless charging of electric vehicles (EV) are inevitable for user convenience of EV charging when the EVs are parked in the charging stations. A new set of triangular DQ transmitting (Tx) coils for wireless EV chargers is newly proposed in this paper for large longitudinal, lateral, and diagonal displacement tolerances. The proposed coil set consists of two layers, i.e., D-Tx and Q-Tx, where each Tx layer has two triangular coils of the same magnetic polarity diagonally, facing each other to g

Frequency modulation control-based wireless power supply (WPS) system adopted for the operating signals of a precharging circuit in solid-state-transformer (SST) is proposed in this article. To guarantee high voltage insulation capability between trolley line and railway vehicle and to decrease the voltage level of railway feeder, a large and heavy main transformer (MTr) operating at 50/60 Hz is conventionally used in railway vehicles. The SST, operating at high frequency for compact size and ac