• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제51권9호
• /
• pp.515-521
• /
• 2002

This paper presents the scheme that improves control responsibility and stability of the controlled-PM electromagnet levitation system with zero Power controller. A magnetically levitation system is used widely because friction can almost be disappeared. But it is difficult to control due to restraint of controllable area and nonlinear characteristics of electromagnetic force, which is proportioned to a square of the magnetic flux density and is in inverse proportion to a square of the air-gap. So, the application of observer theory in which the levitation system is considered to be a linear dynamic model has resulted in omitting the time dependence on mover's speed. Consequently, the performance of the observer is quite poor during transients. Therefore, this paper proposed the controlled-PM electro-magnetic levitation control method in which the variable load is estimated by using the reduced order extended luenverger observer and its system is controlled at a new zero power equilibrium air-gap position. It is also verified that the proposed control method improve the control performance through simulation and experiment.

• 한국소음진동공학회논문집
• /
• 제22권10호
• /
• pp.959-967
• /
• 2012

The theory for a new electromagnetically biased diskless combined radial and axial magnetic bearing is developed. A typical magnetic bearing system is composed of two radial magnetic bearings and an axial magnetic bearing. The axial magnetic bearing with a large axial disk usually limits rotor dynamic performance and makes assembling and disassembling difficult for maintenance work. This paper proposes a novel electromagnet biased integrated radial-axial magnetic bearing without axial disk. This integrated magnetic bearing uses two axial coils to provide the bias flux to the radial and axial air gaps of the combined bearing. The axial magnetic bearing unit in this combined magnetic bearing utilizes reluctance forces developed in the non-uniform air gaps such that the axial disk can be removed from the bearing unit. The 4-pole homopolar type radial magnetic bearing unit is also designed and analyzed. Three dimensional finite element model for the bearing is also developed and analyzed to illustrate the diskless combined magnetic bearing.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.155-157
• /
• 2003

In this paper, CPM(controlled-permanent magnet)-type magnetic levitation system design is presented. The target plant to be controlled consists of eight magnets with permanent magnet and electromagnet. The design procedure is also described and the result of this work is shown.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.945-950
• /
• 2007

This paper presents the design study of a rotary MRF(Magneto-Rheological Fluid) damper that can be conveniently used in the joints to control the damping torques. The basic design concept is to determine the geometric design variables allowing the magnetic flux to flow across the same sectional areas under volume constraint condition. The effects of each design variables for generating the torques were investigated by magnetic field analyses.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 춘계학술대회 논문집
• /
• pp.1303-1307
• /
• 2004

MAGLEV is the vehicle which can run in levitated condition by the electro-magnets, and the vehicle can run without any contact condition. In MAGLEV system achieving a high magnetic field for minimum weight is a noteworthy goal. Unfortunately the two aspects of this goal high field and low weight are contradictory. Suitable designs must be sought using optimization techniques. In this paper, magnet attraction force is calculated and conformed by experimental data for designing a electro-magnet.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
• /
• pp.1178-1183
• /
• 1990

A digital signal processor(DSP) is applied to realizing a compensator of control system of active magnetic bearings, to restrict a resonance caused by the first-order bending vibration of a flexible rotor, and to run the rotor beyond the critical speed. A full-order observer is applied to the translatory rotor-motion with the first-order vibration mode. A PID control is used for the conical motion. The rotor used in the experiments is symmetric, and an electromagnet and a displacement sensor are set in collocation.

• 한국자기학회지
• /
• 제3권2호
• /
• pp.121-124
• /
• 1993

보자력이 큰 강자성체의 자기이력곡선, 자기변형, 자기이방성등의 측정에 사용할수 있는 펄스전자석을 설계제작하였다. 철심의 형상이 주어졌을때 권선의 회수에 따른 전자석의 여러특성과 축전기 방전시의 전류진폭 감쇄비등을 계산하는 일반식을 유도하고 그것에 의하여 철심단면적 46 nm * 32 nm, 공기간격 28nm의 전자석을 설계 제작하여 20 mT/A의 기울기로 0.49 T까지 직선적인 자기장 대 전류특성을 얻었다. 이 전자석에 에너로그 적분기에 의한 자속계를 부쳐서 박막 또는 박대시료의 major 및 minor 이력곡선을 단번에 쉽게 얻을 수 있는 자기이력곡선 측정기가 구성되었다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
• /
• pp.805-810
• /
• 1990

Optimal control systems for a radial magnetic bearing are proposed and tested. An electromagnet system model is developed to predict bearing forces as functions of changing coil currents and rotor position. Models of the multi-mass rotor supported by the magnetic bearings are developed and confirmed, and theoretical relationships are expressed in the form of state equation. As a result of computer simulation, the state feedback with optimal procedure is considered to be more effective for magnetic bearing systems than the classical method.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
• /
• pp.402-402
• /
• 2000

MFL(Magnetic Flux Leakage) methods are used extensively for inspection of ferromagnetic materials. As an example, pipelines that are buried underground are inspected using MFL methods. By the MFL methods, ferromagnetic pipelines are magnetized by a permanent magnet or an electromagnet and then flux leakage is detected at the defection position. In this paper, we perform modeling of the magnetized pipelines. Also we propose the method localization of th defected areas. The effectiveness of the proposed method is verified experimentally.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 춘계학술대회 논문집
• /
• pp.283-288
• /
• 1995

Dynamic model of 3-way PWM high speed solenoid valve was derived considering reluctance and inductance of electromagnet through valve spool by Bondgraph modeling method. Computer simulations of hydraulic system with 3-wayhigh speed solenoid valve were performed and the results were compared to te experimental results in order to validate the PWM valve dynamic model obtained.