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In recent years, buck-boost converters have been widely utilized for battery-powered mobile systems such as RF power amplifiers, battery chargers, and LED drivers. However, in a wide battery voltage range, they face challenges including dynamic voltage scaling (DVS), wide load current range, and dynamic line/load transients while ensuring reliability for an industrial usage. To resolve these issues, the conventional buck-boost (CBB) converter should overcome the characteristic of discontinuity in the output transfer current (OTC) which causes degradation of loop dynamics and transient response. Several past works with continuous OTC have been proposed to resolve these problems, but their voltage conversion ratios are limited [1], [2]. Moreover, in [3], [4], a high-voltage (HV) process, which necessitates large active area and incurs high fabrication cost, is required to withstand voltage stresses over 10V (2×V IN ) applied across power switches. To overcome the above challenges, this paper proposes a voltage-tolerant three-level buck-boost (TLBB) converter. The TLBB has continuous OTC and uses only normal 5V CMOS devices for its switches. In addition, a voltage-tolerant dual channel-interleaved three-level buck-boost (DTLBB) converter is suggested for applications [5] requiring a wide range of load current and high conversion ratio while supporting fast DVS transition.

South Korean industrial conglomerates (chaebols) are discussed in the context of value-based management (VBM). Recent economics and finance literature on the diversion of corporate resources from the firm to the controlling shareholders (tunneling), for which chaebols are notoriously known, is discussed. Chaebols have engaged in empire building and expropriation of minority shareholders, distorting the process of efficient resource allocation in South Korea, and became the root cause of the 1997 financial crisis. We argue that the 1997 crisis should be viewed as a consequence of chaebols’ systematic deviation from the guiding principles of VBM. We use tunneling within chaebols as an example of the need to directly address prohibition of the expropriation of minority shareholders as a primary postulate of VBM. We argue that VBM should require that the value generated by the firm not be expropriated from minorities, or any stakeholders, by dominant shareholders. We also examine moral and ethical considerations and present explanations as to why the unethical practice of tunneling has been tolerated by the South Korean public. We show that public opinion on tunneling is changing and that the treatment of minority shareholders by chaebols’ controlling families is becoming increasingly unacceptable to South Koreans.

A linear induction motor (LIM) with a cage-type secondary has contact resistances between side-bars and secondary conductors due to its own manufacturing process of welding. The finite-element analysis considering the equivalent circuit of the secondary winding is carried out to present the effect of the contact resistance in the LIM. As a result, thrust, normal force, the primary phase current, and the secondary conductor currents of the motor are analyzed for the various contact resistances.

In this paper, we discuss the analysis for the dynamic characteristics of a single-sided linear induction motor (SLIM) having the joints in the secondary conductor and the back-iron. The time-stepping finite element method and the moving mesh techniques are used for the simulation. The gradients of the electric scalar potential in the jointed secondary conductors and back-irons are defined for the eddy current analysis. The simulation results show that the junction between the secondary conductors creates a discontinuity of the eddy current and causes fluctuations of the thrust and the normal force.

This paper presents the finite element analysis for the dynamic characteristics of an inverter-fed permanent magnet linear synchronous motor (PMLSM) having the conductive sheet secondary. The time-stepping finite element method and the moving mesh technique are used for the simulation. The eddy currents in the secondary aluminum sheet and solid back-iron are taken into account in the electromagnetic field analysis.

The real brushless DC motor has different permanent magnet pole magnetization levels due to the influence of the magnetizer geometry. Therefore, this paper discusses the influence of change in the magnetic parameter on brushless DC motor performances. As a result, the unbalanced magnetic force acting on the rotor, cogging torque and torque ripple are examined for spindle motor with unsymmetric magnetization distribution.

This paper describes the effect of eddy currents generated in the rotor steel shell of an exterior-rotor type permanent magnet brushless DC motor of which the rotor is revolving at a high speed. A two dimensional time-stepped finite element method is used to analyze the electromagnetic field and compute motor performance. The conductivity of the rotor steel shell is modified to consider the transverse edge effect. As a result, the effect of eddy currents is shown by comparing the analysis results between when the proposed method is used and when the method it is not.

This paper discusses the phenomena of the axially nonuniform distribution of magnetic flux densities and losses in a three-phase squirrel cage induction motor of which the rotor bars are skewed. A 2-D complex finite element method, taking account of the effects of the skewed rotor bars, is utilized for the analysis of characteristics such as copper and iron losses and the loss distributions are examined. The summing up values of nonuniform losses resulted from the finite element analysis are compared with measurements.

This paper presents a method to analyze radial force densities acting on each stator tooth of an induction motor with skewed slots. A two-dimensional finite element method is used for electromagnetic field analysis of an induction motor, and skew effects are considered by coupling several disks cut by planes perpendicular to the shaft. Radial force densities as a source of vibration are calculated along the surface elements of each stator tooth and its time harmonics are examined by discrete Fourier decomposition.

Attracting ferromagnetic forces between magnet and reaction rail provide the supporting force in Electromagnetic Suspension. Miniature maglev using permanent magnets and electromagnets is based on the idea to generate the nominal magnetic force by permanent magnets and superimpose the variable magnetic field required for stabilization by currents flowing through control windings in electromagnets. Permanent magnets with a high energy density have lower power losses with regard to supporting force and magnet weight. So the advantage of the maglev using electromagnets and permanent magnets is partially reduced by the power required to feed the remaining onboard supply system so that the overall onboard power is diminished as compared to that of the electromagnet. In this paper we proposed the how to design and control the miniature maglev and confirmed the feasibility of the levitation system using electromagnets and permanent magnets through the manufacturing the miniature maglev.

A fully integrated HF multi-standard RFID transceiver for compact mobile terminals is proposed. Considerations for multi-standard are concerned in each part of the proposed transceiver and all of them are implemented as digitally-controlled components. A transmitter controls its modulation index with a mode selector and its emitting power to tags with a power controller, thus covering various standards and recognition ranges. A receiver has a compact size as it excludes capacitors. In a receiver, an ASK demodulator controls its reference level of modulation by switching a resistor, and an adaptable Schmitt trigger alters its hysteresis range by switching additional transistors. The proposed transceiver is implemented in a TSMC 0.18 um CMOS technology. Measurement results of the transceiver and communication test between a reader with the transceiver and tags verify abilities of the proposed transceiver for multi-standard.

The harmonics in electromagnetic force are a source of mechanical vibration and audible noise in an asynchronous traction motor. This paper describes an approach to reduce the force harmonics by changing the rotor slot number. Both the radial and tangential forces acting on the stator teeth are calculated by Maxwell stress tensor and their time harmonics are examined by the discrete Fourier decomposition. As a result, the optimal slot number of the rotor to reduce or eliminate the specific force harmonics is determined.

The analysis of the thin lamination model of the amorphous transformer by FEM requires many region division and much calculating time, and it has difficulty in calculating for mordern computer. A new method which is simulated by a solid but anisotropic block with the magnetic permeabilities in the orthogonal dimensions selected to account for the presence of the laminations.[1] Based on this equivalent anisotropic block model, we have analyze the iron loss of the amorphous transformer by FEM.