Dae-Hyun Koo

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This article shows the reduction of cogging torque in a novel axial flux permanent magnet (AFPM) motor through the various design schemes. 3D finite element method is used for the exact magnetic field analysis. The effects of slot shapes and skewing of slot on the cogging torque and average torque have been investigated in detail. The validity of the(More)
To accomplish the research of a PM synchronous motor driven by 15kW at a rated speed of 120krpm, this paper represents an approach to minimize the eddy current losses that occur frequently at high speeds. Various simulation and testing techniques are therefore applied to grasp the physical phenomena. Here, the proposed parameter for analysis is sleeve(More)
This paper deals with an overhang effect of permanent magnet (PM) in the new type axial flux permanent magnet (AFPM) motor with a double-sided airgap. 3-D electromagnetic finite element method (FEM) is used to calculate the airgap magnetic flux density, back electromagnetic force (EMF) and the cogging torque according to the variation of the overhang angle.(More)
The objective of the present study was to deal with the rotordynamics of the rotor of an ultra-high speed PM type synchronous motor-generator for a 500 W rated micro gas turbine generator. This paper introduces dynamic analysis, and experiments on the motor-generator. The focus is placed on an analytical approach considering the mechanical dynamic problems.(More)
This paper presents a study on the high performance speed control of permanent magnet synchronous motor for computerised tomography (CT). A CT system has many units on its rotary gantry, such as X-ray tube, detector, heat exchanger and data acquisition system. Therefore, to balance many components which have different weights is difficult; this is an(More)
The high speed permanent-magnet synchronous generator is an important component of micro gas turbine. One of the major problems in micro turbine generator is an increase in iron loss with increasing rotational speed. In order to minimize the iron loss, PNF-Core (20PNF1500, posco electrical steel) is used for stator core. The core has good magnetic(More)
This paper presents an optimum design of a lightweight vehicle levitation electromagnet, which also provides a passive guide force in a magnetic levitation system for contactless delivery applications. The split alignment of C-shaped electromagnets about C-shaped rails has a bad effect on the lateral deviation force, therefore, no-split positioning of(More)
This paper presents an eddy current loss analysis for a transverse flux rotary machine (TFRM) with laminated stator cores, which consist of inner and outer cores whose laminated directions are perpendicular to each other. Although the TFRM is laminated to reduce eddy current losses, it still exhibits rapidly increasing core losses as the frequency(More)
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