• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.10a
• /
• pp.457-462
• /
• 2004

Active magnetic bearings (AMB's) have become practical in many industrial fields and numbers of studies for magnetic bearing systems have been reported. However, AMB systems are open-loop unstable and thus require feedback control for robust stabilization and performance. In this paper, first, a rotation of the rotor around the inertial axis is considered and a rigorous modeling of a magnetic bearing system in which the rotation of the rotor is on its axis of inertia is developed. Next, to stabilize the AMB system a PID controller is used and experimentally analyze its rotational response.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.3
• /
• pp.33-38
• /
• 2002

This paper deals with pressure ripple attenuation far separated-type Hydrostatic Transmission (HST) consisting ova variable axial piston pump connected in an open loop to a fried displacement axial piston motor. Pressure ripples in HST is major source of vibration which can lead to fatigue failure of components and cause noise. In order to reduce the pressure ripple, an annular tube tripe hydraulic filter is proposed to attenuate pressure ripples with the high frequencies components to achieve better noise reduction in HST. The basic principle of a hydraulic filter is allied to propagation of pressure wave, reflection, absorption in cross section of discontinuity and resonance in the hydraulic pipeline. It is experimentally shown that the hydraulic filter attenuates about 30∼40dB of pressure ripple with high frequencies. These results will assist in modeling and design of noise reduction in hydraulic control systems, and provide a means of designing a quieter HST.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.538-541
• /
• 2002

Dynamic analysis and compensation design for an asymmetrical half bridge do-dc converter are presented. A small-signal model is developed using the averaging method. Based on the proposed small-signal average model, the open loop transfer functions of the power stage were obtained and used for the compensation design. All theoretical predictions are validated by experiments on a prototype converter.

• Proceedings of the KIEE Conference
• /
• 1997.07a
• /
• pp.118-120
• /
• 1997

A Lineal Stepping Motor (LSM) can operate in an open loop control mode similarly to a rotary stepping motor. However, the LSM has a large transient vibration, and it sometimes causes the miss-step. In this paper, a new vibration suppression method using an energy stored in winding inductance and induced voltage of the LPM is proposed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2005.05a
• /
• pp.458-461
• /
• 2005

In this paper, a new type of inchworm motion actuator is developed in fabrication of actuators for micro-press machine. This is consisted of three piezoelectric actuators, one is for moving the tool guide and the other are for clamping the guide. The inchworm motor provides both high load and large displacement in small size actuator. PZT has compressive strength and often fails under tensile stress and pulling. Thus, in order to prevent failure, we have designed pre-load housing and accomplished FEM analysis. The pre-load housing was used for determining the optimal design condition by comparing the von-mises stresses with the change of hinge stiffness. Also, in order to predict the performance of the motor under certain conditions, the system model was simulated using MATLAB. This is open loop control actuator and driven by the period of input voltage.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.8
• /
• pp.545-550
• /
• 2000

This paper presents design and analysis of an HID lamp ballast for a fast turn on characteristics and stable operation. It produces a high open circuit voltage for the ignition and it is controlled to supply effectively the power required to shorten the warm-up period after the breakdown. The lamp modeling by empirical data is presented. It is very effective in the designing of the control loop in the steady-state operating region. A stable operation of the lamp power regulation in the steady state is achieved, which is crucial for the long life time and constant light output. Stability analysis of the system is performed and the results are verified through various simulation results and the hardware experiments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1995.11a
• /
• pp.153-165
• /
• 1995

When an automatic course-keeping is introduced as is quite popular in modern navigation the closed-loop steering system consists of autopilot device power unit(or telemotor unit) steering gear ship dynamics and magnetic or gyro compass. We derive the mathematical model of each element of the automatic steering system. We provide a method of theoretical analysis on propulsive energy loss related to automatic steering of ships inthe open seas taking account of the on-off mechanism of power unit. Also we paid attention to dead band mechanism of autopilot device which is normally called weather adjustment. Next we make numerical calculation of the effects of autopilot control constants ont he propulsive energy loss for two kinds of ship a fishing boat and an ore carrier. Realistic sea and wind disturbances are employed in the calculation.

• Proceedings of the KIEE Conference
• /
• 1996.11a
• /
• pp.19-21
• /
• 1996

In this paper, the experiment on the dynamic characteristics of LIM for the propulsion system UTM(Urban Transit Maglev) is threated. Untill now LIM has been mainly experimented by using the rotational arch type system, but this system compose of the test vehicle mounted LIM, which driven by PWM inverter. And the anlysis of the performance and the steady-state characteristics of the LIM is treated under various operation patterns. This paper may be available to compose the operating system of LIM driven by the open or closed loop control.

• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.491-492
• /
• 2015

본 논문에서는 영구자석 동기 전동기(PMSM)의 수학적 모델을 기반으로 한 플라이휠 에너지 저장 시스템을 매트랩/시뮬링크를 사용하여 모델링 하였다. PMSM의 센서리스 벡터 제어를 위해 속도 및 전류 제어기를 구현하였으며, PI형 상태 관측기를 이용한 역기전압 추정기와 PLL 기반의 위치/속도 추정기를 구현하였다. 초기 기동시 역기전압 추정기반 센서리스 제어 방식은 회전자의 위치를 정확히 추종 할 수 없어 Open-Loop 알고리즘을 통하여 동기 전동기를 구동시킨다. 플라이휠 에너지 저장 시스템의 센서리스 제어 알고리즘은 충전 모드와 발전 모드에서의 시뮬레이션을 통해 성능을 확인하였다.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2057-2059
• /
• 2001

A nonlinear adaptive speed controller is designed for induction motors. Only the measurement of the stator current is used to design the controller and the observers. The sliding mode cascade observer is introduced to estimate the stator current and its time derivatives. The open-loop observer are designed to estimate the rotor flux and its time derivatives. The adaptive observer is also designed to estimate the rotor resistance. Sequentially, the rotor speed can be calculated using these estimated values. It is shown that the estimation errors of the corresponding states and the parameter converge to the specified residual set. It is also shown that the speed controller using these estimates is performed well. The experimental results are represented to investigate the validity of the proposed observer and controller.