• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.21.1-21.1
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• 2008

• 한국전자통신학회논문지
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• 제6권6호
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• pp.889-895
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• 2011

영구자석 선형 동기 전동기(Permanent Magnet Linear Synchronous Motor:이하 PMLSM)는 구조적으로 간단하며 고속화 고추력화 등의 많은 장점을 가지고 있지만 전기자 권선부의 슬롯-치 구조로 인한 코깅력과 단부효과에 의한 코깅력이 발생한다. 이는 추력 맥동의 원인이 되며, 소음과 진동을 발생시킨다. 따라서, 본 연구에서는 전기자를 분산배치 할 경우 필연적으로 생기는 단부에 의한 코깅력을 저감하기 위해 PMLSM의 가동자에 보조극의 설치를 제안하였다. 또한 2차원 유한요소법(Finite Element Analysis)을 이용하여 단부 코깅력이 최소가 되는 보조극의 형태를 설계하고 전기자의 권선 방식에 따른 단부 코깅력 특성을 비교하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제23권4호
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• pp.61-69
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• 2021

This paper presents the analysis and experiment results on the electrical and thermal characteristics of metal insulation (MI) REBCO racetrack coil, which was wound with stainless steel (SS) tape between turn-to-turn layers, under rotating magnetic field and conduction cooling system. Although the field windings of superconducting rotating machine are designed to operate on a direct current, they may be subjected to external magnetic field due to the unsynchronized armature windings during electrical or mechanical load fluctuations. The field windings show the voltage and magnetic field fluctuations and the critical current reduction when they are exposed to an external magnetic field. Moreover, the cryogenic cooling conditions are also identified as the factors that affect the electrical and thermal characteristics of the HTS coil because the characteristic resistance changes according to the cryogenic cooling conditions. Therefore, it is necessary to investigate the effect of external magnetic field on the electrical and thermal characteristics of MI-SS racetrack coil for further development reliable HTS field windings of superconducting rotating machine. First, the major components of the experiment test (i.e., HTS racetrack coil construction, armature winding of 75 kW class induction motor, and conduction cooling system) were fabricated and assembled. Then, the MI racetrack coil was performed under liquid nitrogen bath and conduction cooling conditions to estimate the key parameters (i.e., critical current, time constant, and characteristic resistance) for the test coil in the steady state operation. Further, the test coil was charged to the target value under conduction cooling of 35 K then exposed to the rotating magnetic field, which was generated by three phrase armature windings of 75 kW class induction motor, to investigate the electrical and thermal characteristics during the transient state.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1181-1182
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• 2010

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.397-400
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• 1986

The paper describes a new PWM technique, which is suitable for brushless servo drives. By taking into consideration the armature electromotive force, an appropriate switching voltage vector can be selected to enable switching rate reduction. Simulation results show better steady-state performance of this method than that of the classical technique.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.132-138
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• 2014

We investigated the harmonic voltages generated by a synchronous machine adding d-axis and q-axis harmonic field windings to reduce the harmonics in a power line. First, electronic circuits such as a frequency multiplier, band-pass filter, and phase shifter were newly designed and made to carry out the experiment. Next, an experimental circuit, for which an AC voltage of frequency 6f synchronized to the power line voltage of frequency f could be obtained, was constructed to examine the generation of harmonic voltage in more detail. Finally, an experiment involving the generation of harmonic voltage was performed using an experimental synchronous generator with harmonic windings in the d-axis and q-axis. In this paper, the power spectrum and the waveforms of the harmonic voltages in the armature winding are presented. Moreover, the values calculated from theoretical expressions of harmonic voltages in armature winding are compared with the values obtained by the experiment.

• Structural Engineering and Mechanics
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• 제75권3호
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• pp.327-337
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• 2020

The stability and dynamic performance of a flapper-nozzle servo valve depend on several factors, such as the motion of the armature component and the deformation of the spring tube. As the only connection between the armature component and the fixed end, the spring tube plays a decisive role in the dynamic response of the entire system. Aiming at predicting the vibration characteristics of the servo valves to combine them with the control algorithm, an innovative dynamic stiffness based on a distributed parameter model (DPM) is proposed that can reflect the dynamic deformation of the spring tube and a suitable discrete method is applied according to the working condition of the spring tube. With the motion equation derived by DPM, which includes the impact of inertia, damping, and stiffness force, the mathematical model of the spring tube dynamic stiffness is established. Subsequently, a suitable program for this model is confirmed that guarantees the simulation accuracy while controlling the time consumption. Ultimately, the transient response of the spring tube is also evaluated by a finite element method (FEM). The agreement between the simulation results of the two methods shows that dynamic stiffness based on DPM is suitable for predicting the transient response of the spring tube.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.167-170
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• 1991

The back e.m.f. of PMSM is increased as the speed is increased and it saturates the current regulator because it counteracts the available output voltage of the inverter. In the PM motor, however, the required armature terminal voltage can be reduced within the maximum output voltage of the inverter by field weakening control, in which the air gap flux is weakened by the d-axis armature current. In this paper, the field weakening control of the surface PMSM fed by a hysteresis current control led PWM inverter based on the microprocessor is presented. To show the validity of the proposed control method, the simulation and experimental results are provided.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.726-728
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• 2004

In this paper, the gain of the observer is properly set up using the fuzzy control and Fuzzy-Sliding observer(FSQ) that have a superior transient characteristic and is easy to implement compared to the existing method is designed. It estimate the differentiation of the armature current directly using the armature current measured in the AC motor. It estimate the speed of the rotor using the differentiation. It is proposed speed sensorless control method using the estimated speed. Optimal gain of speed observer(Luenberger observer) was set up using the fuzzy control and adapted speed control of AC servo motor. To verify the performance of designed Fuzzy-Sliding observer, simulation compared with fixed speed observer gain of G.B Wang and S.S Peng's sliding observer is performed. Also, it was proved the excellence and feasibility of the proposed observer from the comparison test with a speed sensor and without a speed sensor which used a highly efficient drive and 400W AC servo motor starting system.

• 대한기계학회논문집A
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• 제33권6호
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• pp.584-589
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• 2009

As the automobile energy efficiency stands out an important matter of interest, the magnetic engine valve system receives attention. It has an advantage of no engine power leakage in opening and closing the valve. Moreover, it generates much bigger force than the piezo actuator system, so it can be a good alternative system of the cam and camshaft system. However, since the valve system is not light enough, it is necessary to make its weight reduce. In this study, topology optimization is applied to find the optimal shape of the armature in a magnetic valve system combined with the finite element analysis for the magnetic field analysis. The result is used to obtain a concept design. The adjoint variable method is employed in order to calculate the design sensitivity of the magnetic driving force in the armature component mostly to reduce the computational time during the repeated sensitivity calculation. The sequential linear programming is employed for the optimization algorithm.