• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.554-560
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• 2020

In the manufacturing process of flat panel displays, a high-precision planar motion stage is used to position a specimen. Stages of this type typically use frictionless linear motors and air bearings, and laser interferometers. Real-time dynamic correction of the yaw motion error is very important because the inevitable yaw motion error of the stage means a change in the specimen orientation. Gantry control is generally used to compensate for yaw motion errors. Flexure units that allow rotational motion are applied to the stage to apply this method to a stage using an air-bearing guide. This paper proposes a method to improve the constant speed motion performance of a H-type XY stage equipped with air bearing and flexure units. When applying the gantry control to the stage, including the flexure units, the cause of the mutual ripple generated from the linear motors is analyzed, and adaptive learning control is proposed to compensate for the mutual ripple. A simulation was performed to verify the proposed method. The speed ripple was reduced to approximately the 22 % level. The ripple reduction was verified by simulating the stage state where yaw motion error occurs.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.5
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• pp.222-230
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• 2005

This paper deals with the reduction of cogging torque of a outer-rotor type BLDC motor mainly used for washing machines. The motor comprises permanent magnet outer-rotor and stator with coils and core. This structure inherently produces vibration and cogging torque because of uneven reluctance according to rotation of the rotor. Up to now, adopted a type of 24 magnet pole and 36 slot-stator. This generates high main torque but accompanies comparatively large cogging torque. This paper proposes a 32-pole 36-slot type motor which reduces cogging torque remarkably. The influence of cogging torque is varied according to pole-slot combinations. The characteristic of the motor was obtained by a two-dimensional finite element method coupled with a drive circuit. The performance of the proposed model is superior to that of the existing model because of the reduction of torque ripple and the improvement of back ernf wave form.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.87-93
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• 1998

Pressure ripples of hydraulic vane pump results from flow ripples due to pump geometry and reverse flow through the discharge port due to compressibility of fluid and result in vibration and noise of connected hydraulic elements. In a balanced type vane pump, cam ring curve is important factor to influence the flow ripples. Therefore, to reduce the flow ripple, it has been required that optimal selection of seal region by proper design of cam ring and each port position, and notches for preventing the excessive reverse flow. This paper has been performed analytical study of compression characteristics with major design parameter in side plate and cam ring. and examined into the role of notch and radius reduction ratio.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.4
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• pp.49-55
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• 2014

In this paper, we propose the cogging toque reduction technique of the dual stator radial flux permanent magnet generator. The cogging toque is caused by the torque ripple increase and vibration and noise of the generator. And it is important factor determining cut-in speed of the small wind generator. To reduce cogging torque, permanent magnet displacement was studied. And the theory of the permanent magnet displacement was formulated and the cogging torque reduction according to the permanent magnet displacement was confirmed through the finite element method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.6
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• pp.981-987
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• 2017

In this paper, we describe the LPM structure with a two-phase, which is not used previously, and explain its operation principle. In order to predict the accurate performance of LPM reduction model, finite element model was derived and the back EMF of LPM reduction model was measured and compared. In order to investigate the thrust and normal force of the LPM reduction model, a driving circuit capable of applying two-phase pulse currents was constructed and the performance was predicted in conjunction with the finite element analysis model. Finally, the design considering actual LPM size was performed. Since the size of the reduction model is small, the field could be made of a permanent magnet. However, it is almost impossible to manufacture a permanent magnet to match the size and capacity of a real LPM for a vehicle, in terms of cost and writing. Therefore, the actual vehicle LPM was replaced by wound type that generates a magnetic field by applying current to the field winding, and the final model was derived using the reaction surface method.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.3
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• pp.20-25
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• 1997

SRM은 많은 장점으로 인해 각종 산업분야에 적용을 검토하고 있다. 그러나 토오크리플과 소음이 교류전동기보다 상대적으로 높은 단점이 있다. SRM은 상전류파형이 동작특성과 토오크리플발생에 큰 영향을 미친다. 본 논문에서는 토오크리플을 줄이고 정밀한 속도제어를 위해 순시도통각제어와 PLK제어시스템을 이용하였다. PLL의 위상검출기는 도통각제어에, 루우프필터의 출력은 순시 인가전압의 제어에 각각 도입하여 속응성을 높이고 토오크리플을 줄일 수 있도록 하였다. 실험을 통하여 정밀한 속도제어와 토오크리플 저감특성을 확인할 수 있었다.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.358-361
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• 1999

In auxiliary block of high speed train power factor correction and harmonics reduction is very important issue for efficient energy transport. The GTO-equipped PWM converter is used for traction untill resently. But the rising power capability of IGBTs resently allows to build IGBT-equipped PWM converter with a considerably increased switching frequency. This paper presents switching pattern, control method, operation mode and tuned filter to reduce dc link voltage ripple for paralleled converter.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.10-13
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• 1999

본 논문에서는 선단부 유니폴라 PWM 방식의 전압원 인버터에 의해 구형파 형태의 전류로 여자되는 브러시리스 직류전동기에서 토크맥동 발생의 주된 원인이 되는 상 전류 전환 및 비이상적인 역기전력 파형에 희한 토크맥동을 저감시킬 수 있는 방식을 제안한다. 또한 실험을 통하여 제안한 토크맥동 저감기법의 효용성을 살펴본다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.659-660
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• 2008

This paper presents a hybrid winding connection method for torque characteristics improving of a traction SRM. In order to get a high torque in wide speed range and torque ripple reduction, series and parallel winding connection are changed according to operating speed. From the analysis of torque character operation mode and efficiency, the proposed control scheme is verified.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.885-887
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• 2008

본 논문에서는 전원전압 불평형시 권선형 유도전동기(wound-type induction motor)에 발생하는 토크리플을 저감하는 방법을 제안한다. 전원 전압에 불평형이 발생할 경우, 전류와 전압은 정상분과 역상분으로 표현되고 역상성분에 의해 고정자에 무효 전력리플이 발생하며 이 성분에 의해 유도전동기는 토크 맥동을 발생한다. 무효전력 리플 성분을 0으로 제어함으로써 토크 리플을 저감할 수 있다. 제안된 토크리플 저감 방법은 PSCAD/EMTDC 시뮬레이션으로 알고리즘의 타당성이 검증된다.