• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.7
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• pp.709-715
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• 2011

Harmonic drives have been widely used in combination with joint torque sensors in order to facilitate accurate manipulator control. A harmonic drive causes a torque ripple because of its structural characteristics, and this torque ripple tends to deteriorate the performance of a controller or observer that uses torque sensors. This paper proposes a switching notch filter for reducing the torque ripple caused by a harmonic drive in a joint torque sensor; the functioning of this filter is based on the relationship between the frequency components of the torque ripple and the rotational velocity of the harmonic drive. The proposed switching notch filter is advantageous in that it requires less computational load and does not necessitate additional circuits or structures. Various experiments demonstrate that the proposed filter has good filtering performance, fast response, and good switching stability.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.156-157
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• 2017

본 논문은 전차원 자속 관측기를 이용한 대용량 매입형 영구자석 동기전동기(IPMSM)의 센서리스 제어 기법을 제안한다. 기존의 전차원 자속 관측기를 사용한 제어 방식은 IPMSM의 자속 모델을 표면 부착형 영구자석 동기전동기(SPMSM)의 자속 모델처럼 해석하기 때문에 추정되는 회전각의 오차가 발생한다. 특히 릴럭턴스 토크가 큰 대용량 IPMSM 구동 시에는 회전각 오차가 크게 나타나므로 단위 전류당 발생하는 최대토크를 감소시켜 정밀한 MTPA 제어가 불가능하다. 제안하는 알고리즘은 전차원 자속 관측기를 통해 추정된 회전각의 오차를 보상하여 대용량 IPMSM의 정밀한 센서리스 제어를 가능하게 한다. 제안하는 기법의 타당성은 시뮬레이션을 통해 확인하였으며, 기존의 알고리즘과 비교하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.221-229
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• 2003

Interior permanent magnet synchronous motor (IPMSM) has become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. The paper is proposed maximum torque control of IPMSM for electric vehicle drive. The control method is applicable over the entire speed range and considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d-axis current ${^i}_d$ for maximum torque operation is derived. The proposed control algorithm is applied to IPMSM drive system for electric vehicle drive, the operating characteristics controlled by maximum torque control are examined in detail by simulation.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.59-65
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• 2012

Torque Generator is a product which has function to transform hydraulic energy to mechanical energy of torque and rotating speed, and be used for direction change device of agricultural machines. This study proposes failure analysis and test analysis on torque generator and introduces a process that reliability of a product is enhanced by design improvement. And also it presents improvements of maximum output torque by modifying design and surface treatment. Lastly it verifies reliability improvement by analyzing test results of before and after life test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1885-1891
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• 2010

Torque control of wind turbines is important when the wind speed is below the rated speed. The main objective of torque control is to extract the maximum power from the potential aerodynamic power of the wind. Torque control methods for wind turbines are classified as torque-mode control and speed-mode control. In torque-mode control, which is well known and traditionally used in many wind turbines, the torque demand of the generator is proportional to the square of the generator speed. In speed-mode control, a PI controller is used to generate the appropriate torque demand of the generator. In this study, the two torque control methods mentioned above are applied to a 2.75-MW wind turbine; simulation results for real turbulence wind speeds are presented, and the response properties are compared.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.67-72
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• 1994

현재 가전제품의 개발방향은 고효율화, 다기능화와 더불어 환경문제를 고려하는 방향으로 진행되고 있다. 환경문제로는 여러가지가 거론되고 있는데 제품의 소음에 대한 문제도 이제는 성능의 관점에서와 더불어 환경의 문제로도 인식되어야 한다고 생각한다. 특히 고속의 팬종류가 사용되는 가전제품에 있어서 저소음 성능은 판매력에 직접영향을 미치는 중요 판매전략으로 대두되고 있는 상황이다. 진공청소기는 가전제품중에서 매우 시끄러운 제품중에 속한다. 그 이유는 모타가 분당 30,000회 이상의 고속회전을 하면서 축에 연결되어 잇는 임펠러를 회전시켜 공기를 흡입, 배출시키는 일련의 작동을 하면서 여러가지 진동 및 유체소음을 일으키기 때문이다. 팬모타에서 발생한 소음과 진동은 여러가지 복잡한 전달경로를 거쳐서 외부로 전달되어진다. 따라서 청소기의 전체적인 소음을 감소시키기 위한 대책으로는 크게 두가지 방법으로 나누어 생각해 볼 수 있는데, 그 첫번째가 주된 소음원인 팬모타의 소음특성을 개선하는 방법이고 다른 하나는 팬모타로부터 발생된 소음이 밖으로 전달되는 경로를 적절하게 차단하는 방법으로서 청소기 내부에서 여러가지 방법을 사용하여 소음을 저감시키는 방법이다. 본 연구에서는 첫번째 방법인 팬모타의 소음을 감소시키는 대책들에 대하여 중점적으로 기술하려고 한다. 그 이유는 청소기 내부의 구조개선을 통하여 소음을 저감시키는 방법은 그동안 많이 실시되어 실험결과들이 축적되어 있는 반면 그 방법의 실시에는 구조적인 문제점 등 한계가 있기 때문에 더욱 조용한 청소기를 개발하기 위하여는 주된 소음원인 팬모타의 소음을 낮추어야 할 필요가 절실하게 요구되고 있기 때문이다.래그(drag) 토크의 영향과 치타음 저감을 위한 개선된 클러치 특성을 제시하였다. 클러치는 동력을 전달 또는 차단하는 기능 뿐만 아니라 엔진이나 변속기에서 발생하는 소음이나 진동을 저감시키는 기능을 가지고 있다. 따라서 엔진 공회전시에 발생하는 치타음(rattle noise)이나 비틀림 진동을 저감시키는 방법으로는 여러가지가 있으나 클러치 디스크(clutch disc)의 비틀림 기구의 설계 인자들을 적절히 조절함으로써 변속기의 인풋기어에 전달되는 비틀림 진동을 저감시키는 방법이 일반적으로 수행되어지고 있다. 본 연구는 4 실린더 4 싸이클 1.5L 엔진을 장착한 경승용차의 실차실험을 통해 공회전시 엔진 플라이휘일과 인풋기어에서의 회전수 변동을 측정하고, 이 실험 데이타를 기초로 하여 엔진 토크 및 변속기에서의 드래그 토크를 계산하여 엔진-변속기 인풋기어의 반한정계 2자유도 진동모델과 비틀림 특성을 가진 클러치 디스크의 프리댐퍼 영역에 대해 시뮬레이션을 수행하여 클러치 비틀림 기구의 설계인자인 비틀림 강성, 히스테리시스 토크에 따른 비틀림 진동 저감 효과를 연구하고자 한다.성을 확인하였다. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다. 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile where

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.123-128
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• 2022

The torque of the SRM((Switched Reluctance Motor)) is proportional to the inductance slope, so it has a non-linear torque characteristic, and has a disadvantage in that the torque pulsation is large and noise is severe. In particular, the biggest obstacle to the commercialization of SRM is the pulsating torque generated from the rotating shaft, which has various adverse effects not only on the device itself but also on the peripheral devices. Therefore, various methods for reducing the pulsating torque have been published by domestic and foreign researchers, and there is a study result that the hysteresis controller has an advantage in that it can flow a smooth current compared to the chopping control. However, in determining the hysteresis band, if the band is too small, it has a disadvantage in that it may cause a switching loss due to many switching and an unstable initial start when the encoder is used. Therefore, in this paper, a variable hysteresis controller that can reduce torque ripple in a steady state while having a more stable and fast speed response through the change of the hysteresis band according to the speed error.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.4
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• pp.241-250
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• 2022

This paper addresses the Feasible Angular Momentum(FAM) chart that can be used as an indicator for maneuverability analysis of spacecraft installed with control moment gyros(CMGs). Recently, as the demands for high agility of spacecraft has been increasing in order to perform the space mission given to spacecraft more effectively, interest in CMGs, which is a high torque generator is increasing. However, since the CMG has a singularity problem that does not generate the control torque in the specific directions, in this paper, we consider the two pairs of parallel control moment gyros(TPCMGs) that follows the roof-type configuration. The Gimbal space was newly defined except for the space where singularity can be generated and the space where torque error is generated due to the hardware limits. The feasible angular momentum space is defined as a FAM chart, and it is very meaningful that it is possible to analyze the spacecraft's rotational maneuverability effectively by deriving the spacecraft's 3-axis parameters in the corresponding gimbal space mathematically.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1399-1406
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• 2011

The reducer of the mixer is one of the main parts of the processor used for water and wastewater treatment. In this study, an advanced reducer with a drywell structure was developed in order to prevent oil leakage during operation in the field. During the development of the advanced reducer prototype, a mockup, a metal mold, and a cast were made using CAD and a CNC machine. The structural safety of the reducer prototype's lower housing (drywell structure) was checked using the ALGOR commercial FEM analysis code, which yielded a von Mises stress of about 123 N/mm2, which is below the yield stress of 250 N/$mm^2$, and a natural frequency of about 650-700 Hz. In addition, the torque transmission efficiency for the advanced prototype was 95.87%, which is about 8% more than that found in a previous study, 88.45%, and the sound level was below 75 dB. Furthermore, no oil leakage or abnormal sound or vibration occurred. Therefore, an optimally designed advanced reducer prototype has been successfully developed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2618-2624
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• 2009

Harmonics (or distortion in wave form) has always existed in electrical power systems. It is harmless as long as its level is not substantial. However, with the recent rapid advancement of power electronics technology, so-called nonlinear loads, such as variable frequency drives for motor power/speed control, are increasingly finding their way to shipboard or offshore applications. In this paper a new approach to direct torque control (DTC) of induction motor drive is presented. In comparison with the conventional DTC methods the inverter switching frequency is constant and is dramatically increased, requiring neither any increase of the sampling frequency, nor any high frequency dither signal. The well-developed space vector modulation technique is applied to inverter control in the proposed DTC-based induction motor drive system, thereby dramatically reducing the current harmonics. As compared to the existing DTC approach with constant inverter switching frequency, the presented new approach does not invoke any concept of deadbeat control, thereby dramatically reducing the computations.