• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.171-173
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• 1997

This paper presents analysis of the radial force density in brushless DC motor of which distribution is not uniform in the axial direction. The analysis considering 3D shape of teeth and overhang is not only important but essential to calculate the radial force density that acts on the teeth of stator, because it is frequent source of vibration and changes at the end of teeth. For the analysis, a new 3D equivalent magnetic circuit network method taking into account movement of the rotor without remesh is proposed. The radial force density is calculated by Maxwell stress tensor and analyzed by discrete Fourier transform.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.971-975
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• 2005

In this study, a car-door-controlled collision protection system using proximity sensor is proposed and its preliminary analysis and several preliminary experiments are conducted. The proposed system has three additional sub-components on the car-door that is, a pair of extra electro-magnetic actuator that are attached to the sliding bar of the open/close car-door four-bar mechanism, a proximity sensor that would be attached to the outside surface of the door which is likely to frequently contact to the object and a driving control circuit of the whole system. A proximity sensor is used to detect object close to the car-door, the driving control circuit provides actuating power command to the electro-magnets to generate braking force to stop the swing motion of the car-door. It is verified through kinematic analysis of the four-bar car-door open/close mechanism and through experiments that the magnitude of maximum electronic magnetic force could provide the braking force enough for this application. For this purpose, an electro-magnet driving circuit is implemented and tested. And also to increase the safety of the system a time delay circuit is implemented and tested.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.38-42
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• 2023

The evaluation of no-insulation (NI) high-temperature superconducting (HTS) typically uses the lumped equivalent circuit (LEC) model. Constant parameters in the NI HTS LEC model accurately predict voltage and central magnetic field at currents below the critical current. However, it is difficult to find constant circuit parameters that simultaneously satisfy the measured voltage and magnetic field under overcurrent conditions. Recent research highlights changes in contact resistance during transient conditions, which may impact power loss estimation in NI HTS coils. Therefore, we confirm the influence of contact resistance changes on loss calculation in the transient state for NI HTS coil. To achieve this, we introduce a measurement data analysis method based on the LEC model and compare it with the LEC model using constant circuit parameters.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.117-123
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• 2016

High speed circuit breakers(HSCB) interrupt the generated arc within the arc chute to turn off the electricity flowing through the main circuit to prevent ground faults. In order to explore the arc generated from the contactor operation, arc definition, establishment of arc interruption method, and analysis of magnetic driving force are required. In this paper, arc interruption capability has been estimated by exploring the difference in magnetic flux density of Lorenz forces using finite element analysis. In addition, since the number of grids and changes in the grid shape within the arc chute influence the formation of the inner magnetic field, its effects have been explored to enhance arc interruption capability. Assessment of interruption capability and analysis of grid shape, with rated operating current, are reported.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.36-38
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• 1995

A Single-phase condensor motor is analyzed by FEM coupled with external circuit. The finite element analysis is based on the solution of combined equation both the magnetic field equation from the Maxwell's and the circuit equations of the stator and rotor circuit. The external circuit of the single-phase condensor motor to be analyzed is described using FLUX2D and linked to multiple FEM regions. The simulated results show that the condensor motor analysis with external circuit has good agreement with those of test results.

• 전기의세계
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• v.22 no.3
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• pp.25-34
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• 1973

In this paper, the characteristics of a single phase induction motor which is considered the space harmonic flux by the double revolving field theory is analysed. As the rotor resistance for the fundamental flux is separated from the resistance for the rotor bar and end-ring, and the rotor leakage reactnace is separated from the skew leakage reactance and the other, so the circuit constants for the space harmonic flux is expressed by the circuit constants for the fundamentals. As the ratio of the circuit constants for the magnetizing reactance is used, the generalized equivalent circuit is made up. the characteristic equation which is able to analysis the subdivided characteristics by the above circuit is induced. The ratio of the circuit constants and the skew angle being changed, the variations of the torque-speed characteristics for the fundamentals and harmonics is examined by this equation.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.638-641
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• 2001

Connectorless power transmission and supply are the power transfer device revealed by resonant inverter or transformer using inductant device. Recently, on power supply have been going on frequently, so several power supply circuit forms are announced. But Compared with the circuit of previous paper, instead of the circuit composed of a simple sylinder Ferrit, I was manufacture in a sylinder that It was a double overlab to a sylinder and I was followed a double flux in inner flux path. Above all, for practicalization, supply circuit operation character analysis and development of controller should be preceded. According to this paper, power transmission and supply analyze characters and design control circuit like the analysis of general resonant inverter for power transmission. They compose the circuit to get sinusoid wave output voltage using pulse width modulation control mode. For Supply, output wave form through power track and power pick-up of magnetic inductance includes ripper component. So I intend to design the controller including filter and regulator, compare analyze theoretical result with real measurement value and then show you their practicality

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.233-243
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• 1998

The demand of high speed machining is increasing due to the high speed cutting and grinding provides high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting or grinding. This paper describes a design process of an active magnetic bearing system for a high speed grinding spindle with power 5.5kW and maximum speed 60,000rpm. Magnetic actuators are designed by the magnetic circuit theory considering static load condition, and examined with FEM analysis. Dynamic characteristics are also considered, such as bandwidth, stiffness, natural frequency and static deflection. System characteristics are simulated with a rigid rotor model.

• Smart Structures and Systems
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• v.14 no.5
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• pp.869-881
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• 2014

This paper presents the materials analysis for combination of working modes of Magnetorheological (MR) damper. The materials were selected based on the optimum magnetic field strength at the effective areas in order to obtain a better design of MR damper. The design of electromagnetic circuit is one of the critical criteria in designing MR dampers besides the working mechanism and the types of MR damper. The increase in the magnetic field strength is an indication of the improvement in the damping performance of the MR damper. Eventually, the experimental test was performed under quasi-static loading to observe the performances of MR damper in shear mode, squeeze mode and mixed mode. The results showed that the increment of forces was obtained with the increased current due to higher magnetic flux density generated by electromagnetic coils. In general, it can be summarized that the combination of modes generates higher forces than single mode for the same experimental parameters throughout the study.

• Journal of Power Electronics
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• v.14 no.5
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• pp.815-826
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• 2014

An improved bridgeless interleaved boost power factor correction (PFC) rectifier to improve power efficiency and component utilization is proposed in this study. With combined conventional bridgeless PFC circuit and interleaved technology, the proposed rectifier consists of two interleaved and magnetic inter-coupling boost bridgeless converter cells. Each cell operates alternatively in the critical conduction mode, which can achieve the soft-switching characteristics of the switches and increase power capacity. Auxiliary blocking diodes are employed to eliminate undesired circulating loops and reduce current-sensing noise, which are among the serious drawbacks of a dual-boost PFC rectifier. Magnetic component utilization is improved by symmetrically coupling two inductors on a unique core, which can achieve independence from each other based on the auxiliary diodes. Through the interleaved approach, each switch can operate in the whole line cycle. A simple control scheme is employed in the circuit by using a conventional interleaved controller. The operation principle and theoretical analysis of the converter are presented. A 600 W experimental prototype is built to verify the theoretical analysis and feasibility of the proposed rectifier. System efficiency reaches 97.3% with low total harmonic distortion at full load.