• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.10
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• pp.738-746
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• 2019

Instead of hydraulic actuation systems, an electromechanical actuation system is more efficient in terms of weight, cost, and test evaluation in the thrust vector control of the 7-ton gimbal engine used in the Korea Space Launch Vehicle-II(KSLV-II) $3^{rd}$ stage. The electromechanical actuator is a kind of servo actuator with position feedback and uses a BLDC motor that can operate at high vacuum. In the case of the gimballed rocket engine, a synthetic resonance phenomenon may occur due to a combination of a vibration mode of the actuator itself, a bending mode of the launcher structure, and an inertial load of the gimbals engine. When the synthetic resonance occurs, the control of the rocket attitude becomes unstable. Therefore, the requirements for the stiffness have been applied in consideration of the gimbal engine characteristics, the support structure, and the actuating system. For the 7-ton gimbal engine of the KSLV-II $3^{rd}$ stage, the stiffness requirement of the actuation system is $3.94{\times}10^7N/m$, and the direct drive type electromechanical actuator is designed to satisfy this requirement. In this paper, an equivalent stiffness analysis model of a direct drive electromechanical actuator designed based on the stiffness requirements is proposed and verified by experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.4
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• pp.196-200
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• 2004

This paper presents a method to reduce the commutation torque ripple in a position sensorless brushless DC motor drive. To compensate the commutation torque ripple considerably, the duration of commutation must be known. The proposed method measures the duration of commutation from the terminal voltage of the motor, calculates a PWM duty ratio using the measured commutation interval to suppress the commutation torque ripple, and applies it to the calculated PWM duty ratio only during the next commutation. Experimental results show that pulsating currents and vibrations are considerably reduced when the proposed method is applied to a position sensorless brushless DC motor drive for the air-conditioner compressor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.298-302
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• 2012

The linear encoder used in the BLAC driving circuit consists usually analog type sensor, and need signal transform from analog sinusoidal to digital one for application in the PWM algorithm that is used to control motor current. When the motor is driven in low speed, it is required many operations and higher quality DSP to convert the hole sensor signal to digital one with enough resolution. In this paper, the another method to convert that signal with enough resolution without calculation of sine function is proposed. This is very simple and have high resolution even if the motor is driving in low speed. To verify the proposed method, BLAC motor is used, and it is proved that the motor is tracking well the reference step signal in the low speed as well as in the high one.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.106-114
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• 1998

Cogging torque is often a principal source of vibration and control difficulty in permanent magnet motors, especially at low speeds and loads. For example, reduction of cogging torque is an important specification for DC motors used for electric power stee- ring. This paper examines two motor design techniques, stator tooth notching and rotor pole skewing with magnet pole shaping, for reduction of cogging torque, and the effect of each method on the airgap flux, and the use of the Maxwell stress method and Fourier decomposition to calculate the periodic cogging torque. The analyses show that the cogging torque can be nearly eliminated by the suggested designs, with minimal scacrifice of output torque.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.406-408
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• 1996

This paper describes the BLDC motor which is applicated for a top front loading domestic washing machine. This motor is adopted direct drive washing machine without gear-belt-pulley system. Because gear box is removed, machine volume and noise are reduced. Moreover mechanical troubles in gear box are removed. Realization of variable speed region through of PWM control and high speed is able to efficient washing and spinning.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.489-492
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• 2000

브러쉬없는 직류전동기의 위치제어를 위한 퍼지가변구조제어기를 설계한다. 특히 본 논문에서는 기존의 퍼지제어 기법에서 얻을수 있는 특징으로부터 하나의 전건부 변수만을 가지는 간단한 퍼지논리제어기의 설계를 기술한다. 가변구조제어는 시스템의 파라메터 변화나 외란에 둔감한 특성을 갖는다. 하지만 리칭페이스에서는 문제가 된다. 이를 개선하기 위하여 본 논문에서는 지수항을 추가한 비선형 슬아이딩면을 구성한다. 그리고 나서 비선형적 슬라이딩면과 슬라이딩면의 변화율을 입력으로하는 퍼지 제어기를 설계한다. 이러한 2-입력 퍼지가변구조제어기의 제어 규칙표로부터 슬라이딩면 하나만을 입력으로 가지는 단일입력 퍼지 가변구조 제어기를 설계한다. 이들 제어기의 성능을 입증하기 위하여 시뮬레이션과 실험을 수행한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.235-243
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• 1998

For motor operation at low speeds and loads, torque pulsation by the cogging torque is often a source of vibration and control difficulty. In this paper, the magnetic field of a motor is calculated by finite element method. The periodic cogging torque is determined using Maxwell stress method and time stepping method, and then decomposed using fourier series expansion, The purpose of this paper is to characterize design parameters on the cogging torque and to design a permanent magnet motor with a cogging torque less vulnerable to vibration, without sacrificing the motor performance. The design parameters include stator slot width, permanent magnet slot width, airgap length and magnetization direction. A new design with a less populated frequency spectrum of the cogging torque is proposed after characterizing individual effect of design parameters. Magnet pole edge shaping, by gradually increasing the cogging torque with reduced higher harmonics.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2186-2187
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• 2011

승강장 스크린도어(PSD: Platform Screen Door)는 철도, 경전철 및 지하철 승강장 내 추락, 전동차 사이의 끼임 등의 안전사고 방지 및 승강장의 공기오염 개선, 장애인, 노약자 등의 탑승편의에 관한 문제, 승강장내의 쾌적한 환경문제 제공 등을 위해 전동차 승강장의 선단에 고정 및 가동 도어를 설치하여 승강장과 선로를 차단함으로써 이용 고객의 안전사고를 예방하는 설비를 말한다. 국내 업체들은 기술 투자를 통해 종합 제어반 및 각종 조작반, RF장치 등 상당 부분 국산화를 이루었지만, 짧은 기간 동안 승강장 스크린 도어를 설치하면서 승강장 스크린 도어 시스템의 핵심이라 할 수 있는 승강장 스크린 도어용 제어장치(DCU: Door Control Unit)의 완전한 국산화는 이루지 못한 채 외국 제품을 도입하여 설치하고 있거나 DC 모터를 적용한 제어장치를 개발하여 설치하고 있는 실정이었다. 본 연구에서는 BLDC 모터를 적용한 제어장치를 국산화하여 시제품을 제작하였고 월미도의 은하레일에 제어기를 설치하여 성능을 검증하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.973_974
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• 2009

본 연구는 영구자석 AC 동기전동기의 초기 기동제어에 대하여 연구하였다. 회전자 위치 검출용 센서는 홀센서를 사용하였고 전동기 운전을 벡터제어를 사용하기 위해 전동기가 정지된 상태에서 홀센서 신호에 따른 회전자 위치를 계산하였다. 견인전동기가 주행저항 보다 큰 견인력을 내기 위해 전동기를 BLDC로 기동한 후 안정적 운전을 위해서 벡터제어로 전환하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.917_918
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• 2009

최근 전기 구동 시스템을 갖춘 친환경적인 하이브리드 자동차 혹은 전기 자동차에 대한 관심이 늘고 있다. 본 논문에서는 비교적 구조가 간단한 자전거에 쉽게 적용될 수 있는 BLDC 모터를 기준으로, 전기자전거 주행 상황에 있어서의 슈퍼커패시터를 이용한 회생 에너지 제어에 대하여 언급한다. 회생 에너지를 최대한 슈퍼캐패시터에 전달할 수 있는 제어 방법을 제시하고 이를 컴퓨터 모의 실험을 통해 확인한다.