• 조명전기설비학회논문지
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• 제28권2호
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• pp.54-59
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• 2014

The electric power can be converted into the mechanical power by a corona discharge system. This way has not stronger force than a electric motor. But it has been applied in various industrial fields because of many advantages, no moving parts, smaller noise, simpler structure, minimizing et al. In this paper, corona discharge system with multiple corona electrode installed in form of the ring, has been studied by focusing on the electrical and mechanical characteristics. Intensity of the corona discharge depends on applied electric field, and electric field is related to the applied voltage, discharge gap spacing(s), distance between each corona electrodes(d). As a result, in the case d/s=0.9, most intensive discharge occurred in this experiments. In the region of d/s<0.9, ionic wind velocity has saturation value in spite of decreasing corona current, because each ion velocities increase by the increasing electric field.

• 조명전기설비학회논문지
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• 제17권6호
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• pp.127-129
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• 2003

최근 차세대 고용량 저장 매체 뿐 아니라 다양한 멀티미디어를 구현할 수 있는 디지털 다기능 디스크(DVD)의 개발에 가전 및 컴퓨터 업계의 노력이 집중되고 있다. 현재 국내에서 제작되고 있는 DVD 구동 모터용 마그네트는 소결 자석 부품을 조립하여 제작하고 있으며 조립에 따른 진동 및 소음 절감에 한계가 있다. 따라서 본 연구에서는 이 회전자를 일체형으로 제작함으로써 조립에 따른 가공 공차를 줄여 진동 및 소음을 줄이고자 한다. 이때 일체형으로 제작하기 위해서는 제품을 자장 중에서 사출해야 되며, 이 사출용 금형을 유한요소법을 이용하여 설계하고 이를 통한 제품의 특성을 실험치와 비교하였다.

• 한국기계가공학회지
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• 제12권4호
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• pp.16-21
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• 2013

This paper presents a DC link voltage control method to reduce the ripple current and the switching loss in the sinusoidal current drive system for the wide-speed range PMSM. The DC link voltage of the three phase inverter in the sinusoidal current drive system is designed by the back-EMF voltage at maximum speed of the PMSM. In general, the drive systems have used the constant DC link voltage without reference to the motor speed. The current ripple causes hysteresis loss and makes noise. In addition, the switching loss on the inverter increases in proportion to the rise in the DC link voltage. In this paper, we propose the variable DC link voltage control method to reduce the current ripple in the PMSM drive system. We show reduction effect of the current repple and the switching loss through simulation results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.466-469
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• 1995

This paper presents a design and performance of the 6 D.O.F linear motion table with a magnetic bearing suspension. The linear positioning of the table with a 150mm stroke is driven by a brushless DC Linear motor and the other attitudes of the stage are controlled by the analog PD controller with magnetic bearing actuators. Each magnetic bearing unit which consists of 3 electromagnets, 3 capacitance probes and 3 backup bearings affords controlled forces by detecting the air gap between the probes and guideways. An integral type capacitance probe amplifier is equipped on the upper plate of the table so that the probe line to the probe amplifier can be shorter therefore the problems due to the stray capacitance and noise can be reduced. Form the pitch-yaw errormeasured by the autocollimator, the vertical and horizont straightness errors of the table are derived that they are maintained below 1.mu. m over 100mm stroke. The positioning accuracy of the linear motion is maintained below 2 .mu. m and the repeatability error is below 1 .mu. m

• 한국정밀공학회지
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• 제29권5호
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• pp.500-505
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• 2012

Recently, a high speed spindle is an essential part of machine tools to satisfy latest demand of high precision product and machining of hard materials. But, there are many disadvantages such as heat generation of built-in-motor, bearing friction, noise, vibration and displacement because of the high speed. Many researches on spindle systems have been conducted for solving these problems. In this study, technical trend of machine tools spindle systems are analyzed with patent PSM, mapping and grouping. The analysis is carried out for the applied patent during January 2000 and December 2009 in Korea, Japan, EU and U.S.A. And development of the direction, strategy and promising technologies of the spindle system are suggested.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.4665-4671
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• 2013

엔진 설치 시스템은 차량의 NVH 성능에 매우 중요한 시스템 이다. 차량의 NVH 성능은 공회전 진동(Idle Vibration), 엔진 쉐이크(Engine Shake) 시동 진동(Key ON/OFF Vibration), 변속 진동(Gear Shift Vibration) 등 다양한 이론이 존재한다. NVH 성능 개선을 위해 이러한 이론들에 대한 실제적 최적화가 필요하며, 특히 최적의 엔진 설치 위치와 강성을 찾아내는 것이 매우 중요하다. 또한 효과적인 NVH 성능 개선을 위하여 차량개발 프로세스 측면에서 제약조건과 한계가 있는 사후 조정보다는 개발 초기에 최적화가 필요하다. 본 논문에서는 엔진 설치 시스템 관련 여러 이론에 대한 최적화 해석과 파워 트레인의 엄격한 모드 분리와 토크롤축(Torque Roll Axis), 탄성롤축(Elastic Roll Axis) 사이의 각도를 최소화 하는 다양한 시뮬레이션 케이스(Simulation Case)와 FE-모드를 개발초기에 수행하여 다중 최적화 분석을 함으로서 최적의 엔진 설치 위치와 강성을 찾아내어 NVH 성능을 개선하였다.

• Tribology and Lubricants
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• 제29권2호
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• pp.105-110
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• 2013

Refrigeration and air-conditioning compressors used in home appliances, including refrigerators and air conditioners, are typically hermetic-type reciprocating compressors. Because the shell is sealed by welding, it should be designed to have a semi-permanent life. The energy consumption of a hermetic-type reciprocating compressor is low, but because it operates continuously to maintain a constant temperature inside the refrigerator, it has a certain base load. In this type of compressor, the driving motor operates at a high speed (about 3,000 - 3,600 rpm), which causes valve damage, friction, wear, and high-frequency noise. Many studies have been conducted to solve these problems. To enhance the reliability and efficiency of the reciprocating compressor, the design conditions and operating environment of journal bearings should be considered. Dynamic behavior analysis should be carried out in terms of the discharge pressure. The results showed that the load (discharge pressure) increases in the forward lookup zone and decreases in the backward lookup zone. When the revolution speed is increased, the maximum load decreases in the region where the maximum load operates.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.16-20
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• 1989

In this paper, we describe the optimal driving method and magnetic flux distribution of permanent magnet which enhance torque characteristics in small-sized 3-phase brushless DC motors. The disadvantages of conventional $120^{\circ}$ constant current drive method are torque ripple, switching noise and spike voltage due to the inductance of stator coil. This shortcommings can be avoided by the switching slew-rate of driving current which is called linear voltage driving method. The aim of this study is to analyze linear voltage driving method quantatively and to determine optimal drive current waveform through computer simulation. The selection of commutation angle and slew rate of a new driving current at switching instants makes torque ripple index minimize and average torque maximize. And the validity of this new driving method was assured by Fourier analysis. Considering two dimensional nonlinear magnetic flux distribution on the permanent magnet, we suggest optimal flux distribution according to the presented driving method which improves torque characteristics.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권12호
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• pp.691-699
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• 2004

SRM(Switched Reluctance Motor) drives require the accurate position information of the rotor. These informations are generally provided by a tacho generator or digital shaft-position encoder These speed sensors lower the system reliability and require special attention to noise. This paper describes a new approach to estimating SRM speed from measured terminal voltages and currents for speed sensorless control. The described method is based on the sliding mode observer. The rotor speed and position observers are estimated by the adaptation law using the real and estimated currents. However, the conventional adaptive sliding mode observer based on the variable structure control theory has some disadvantages that the estimated values including the high-frequency chattering and the steady state error generated due to the infinite feedback gain chosen and the discontinuous control input. To reduce the chattering and steady state error, an integrator is also inserted in the sliding mode observer strategy. The described adaptive sliding mode observer decreases the vibration to the switching hyper-plane of the sliding mode by adding integrator. The described methodology incorporates the Lyapunov algorithm to drive the rotor speed and the stator resistance such that it can overcome the problem of sensitivity in the face of SRM parameter variation. Also, without any mechanical information. The rotor speed of SRM is obtained form adaptive scheme. The described method is verified through the simulation and experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.213-218
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• 1991

A new model which contains the dynamics of the motor system and the kinematics of the timing belt system is derived for an inverted pendulum system in FAPA Lab. Generalized standard compensator configuration(SCC) which contains the variable design parameters Kl, K2, .., K5 is proposed so that any desired design specification can be achieved. The robust controller which has robust property against the influence of sensor noise, system parameter variation and model uncertainty is designed minimizing the H$_{\infty}$-norm of transfer function from exogenous input to controlled output. The method of solving the two Riccati equations in state space and determining the controller uses on iteration method where the unique stabilizing solution to two algebraic Riccati equation must be positive definite and the spectral radius of their product less than .gamma.$^{2}$. Some cases are derived by varying the design parameter for simulation on a digital computer and experimenting the H$_{\infty}$- controller on an analog computer. The design parameters of controller which satisfies the desired control specification is selected on the basis of the simulation result and experimenting. The reasonableness and validity of the simulation and the robustness of the controller is established.d.