• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.21-25
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• 2007

Superconducting fault current limiter (SFCL) is attractive apparatus to reduce fault current in power grid. Since it is applied to the alternating current (AC) power line, the SFCL has losses in the normal operation. Recently, coated conductor (CC) is noticeable material employed for resistive bifilar winding type SFCL in many research groups. Bifilar structure is expected to have low AC loss by magnetic field offset as compared with the single tape structure in the same length. This paper reports about characteristic of bifilar pancake type coil for SFCL application in AC loss aspect. The bifilar coil is wound using CC with facing on HTS sides each other. Transport AC loss measurement and characteristic analysis of the bifilar coil using CC have been performed at 77K. The test results are compared with the Norris equations and the test results of non-inductively wound paralleled solenoid type coil which is suggested and tested in this group at present.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.211-215
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• 2006

This paper presents a new structure for the universal motor using soft magnetic composite (SMC). The stator for this new type of motor is made by combination of the SMC pole and the silicon steel yoke. The shape of the 3D SMC pole is designed to minimize ohmic loss and amount of stator coil. To design the pole shape, the 3D analysis in the design procedure is replaced with an equivalent 2D analysis. Finally, the optimal shape is analyzed by 3D FEM and the performance is discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1193-1196
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• 2007

A new planar transformer type energy recovery circuit for PDP is proposed in this paper. The same current is transferred through both the primary and secondary sides during the energy recovery period. The conduction loss is reduced. Fabrication through simple manufacturing processes is possible using the PCB winding.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.5-8
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• 1988

A digital simulation method for Hysteresis motor using Preisach model is proposed. From this, the instantaneous torque, hysteresis loss of rotor can be calculated, considering slot and winding distribution and current harmonics.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.1
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• pp.20-23
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• 2004

BLDCMs are widely used in many industries. In certain specialized areas, they need to have high efficiency, high power rate and produce a low volume of noise, etc. In this study, a new type of slotless BLDCM is proposed that has no cogging torque, low iron loss and low volume as compared to commonly used BLDCMs. With a high performance magnet and coreless compact winding structure similar to those employed in linear synchronous motors, motor volume is reduced. The proposed motor has been put been through various experiments arid has demonstrated acceptable results for industry applications.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.15-17
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• 1995

Hysteresis motor is a synchronous machine which has simple structure and self-start characteristic but also has serious difficulties in numerical analysis. In this study, a finite element analysis for hysteresis motor considering the hysteresis characteristics is presented. The hysteresis model is the magnetization-dependent Preisach model which explains hysteresis phenomena very well. From this, we estimate the instantaneous torque, average torque and hysteresis loss of the rotor, considering slot and winding distribution.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.962-963
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• 2015

This paper proposes a sensorless V/f control method of the interior mounted permanent magnet synchronous motor without damper winding. Arithmetic computation is simpler than vector control. And the lower cost price, dynamics and stability is guaranteed. When the loss of synchronization occurs with the load disturbances, the stability loop with a reduced order observer is applied quickly and accurately to improve the speed error.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.1
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• pp.25-33
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• 2015

This paper presents the d-q axis equivalent circuit model of an interior permanent magnet (IPM) which includes the iron loss resistance. The model is implemented to be able to run in real-time on the FPGA-based HIL simulator. Power electronic devices are removed from the motor control unit (MCU) and a separated controller is interfaced with the real-time simulated motor drive through a set of proper inputs and outputs. The inputs signals of the HIL simulation are the gate driver signals generated from the controller, and the outputs are the winding currents and resolver signals. This paper especially presents iron loss prediction which is introduced by means of comparing the torque calculated from d-q axis currents and the desired torque; and minimizing the torque difference. This prediction method has stable prediction algorithm to reduce torque difference at specific speed and load. Simulation results demonstrate the feasibility and effectiveness of the proposed methods.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.45-49
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• 2023

CORC, which is being studied as one of the conductors for large currents, is manufactured by symmetrically arranging several strands of high-temperature superconducting wires on a cylindrical former. It allows current to flow evenly between wires and has the advantage of being manufactured in a multi-layer structure to increase current capacity. In order to apply CORC to AC power devices, it is necessary to review the material of the former, which is the frame around which the superconducting wire is wound. In the case of metal formers, they are difficult to apply because eddy currents are generated in the former, and they do not have the flexibility to be manufactured into coils by winding them with CORC. In this paper, we compare and analyze the magnetization loss caused by an external alternating magnetic field of Litz wire, which is being considered as a former material for CORC, with the results from formers made of other materials. In addition, we experimentally examine the effect of reducing magnetization loss due to an external magnetic field in CORC using a split wire made by dividing a high-temperature superconducting wire into two using an etching method, and in CORC made with a non-split wire.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.215-223
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• 2005

An electrical machine for a high-speed flywheel for energy storage in large hybrid electric vehicles is described. Design choices for the machine are motivated: it is a radial-flux external-rotor permanent-magnet synchronous machine without slots in the stator iron and with a shielding cylinder. An analytical model of the machine is briefly introduced whereafter optimization of the machine is discussed. Three optimization criteria were chosen: (1) torque; (2) total stator losses and (3) induced eddy current loss on the rotor. The influence of the following optimization variables on these criteria is investigated: (1) permanent-magnet array; (2) winding distribution and (3) machine geometry. The paper shows that an analytical model of the machine is very useful in optimization.