• International journal of advanced smart convergence
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• 제10권2호
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• pp.175-186
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• 2021

We have studied the speed regulation of the permanent magnet synchronous motor (PMSM) servo system in this paper. To optimize the PMSM servo system's speed-control performance with disturbances, a non-linear speed-control technique using a back-propagation neural network (BP-NN) algorithm forthe controller design of the PMSM speed loop is introduced. To solve the slow convergence speed and easy to fall into the local minimum problem of BP-NN, we develope an improved BP-NN control algorithm by limiting the range of neural network outputs of the proportional coefficient Kp, integral coefficient Ki of the controller, and add adaptive gain factor β, that is the internal gain correction ratio. Compared with the conventional PI control method, our improved BP-NN control algorithm makes the settling time faster without static error, overshoot or oscillation. Simulation comparisons have been made for our improved BP-NN control method and the conventional PI control method to verify the proposed method's effectiveness.

• 한국소음진동공학회논문집
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• 제13권8호
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• pp.598-604
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• 2003

In this paper a general solution method is presented to obtain the unbalance response orbit from the finite element based equations of motion of a gear-coupled two-shaft rotor-bearing system, whose shafts rotate at their different speeds from each other. Particularly, are proposed analytical solutions of the maximum and minimum radii of the orbit. The method has been applied to analyze the unbalance response of a 800 refrigeration-ton turbo-chiller rotor-bearing system having a bull-pinion speed increasing gear. Bumps in the unbalance response of the driven high speed compressor rotor system have been observed at the first torsional natural frequency due to the coupling effect of lateral and torsional dynamics. Further, the proposed analytical solutions have agreed well with those obtained by a full numerical approach. The proposed analytical solutions can be generally applied to obtain the maximum and minimum radii of the unbalance response orbits of dual-shaft rotor-bearing systems coupled by bearings as well.

• Journal of Power Electronics
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• 제1권1호
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• pp.56-64
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• 2001

This paper presents the switching angle and voltage for maximizing the torque or efficiency and minimizing torque ripple of an 8/6, SRM. The approximate analysis and computer simulation determine the switching angle and voltage by using SIMULINK$^\textregistered$. This is performed as a function of the speed and torque required by the load. From the results, new three facts can be known: First, the maximum torque depends on voltage and speed depends on switching angle. The others, the maximum efficiency and minimum torque ripple relay on switching angle. We control the switching angle and voltage of and asymmetrical inverter for the SRM with one-chip micro controller.

• Tribology and Lubricants
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• 제31권5호
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• pp.205-212
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• 2015

In this research, effects of profile changes of stem section of the plunger on the lubrication characteristics of a fuel injection pump (FIP) were evaluated by hydrodynamic lubrication analysis. The clearance between plunger and barrel was divided into two regions, head and stem. The head was not involved in preventing a decrease of fuel oil pressure. So, research efforts were focused on both edges of the plunger’s stem. The two -dimensional Reynolds equation was used to evaluate lubrication characteristics with variations in viscosity, clearance and profile for a laminar, incompressible, unsteady-state flow. Moreover, the equilibrium equation of moment and forces in the vertical and horizontal directions were used to determine the motion of the plunger. The equations were discretized using the finite difference method. Lubrication characteristics of the FIP were investigated by comparing the dimensionless minimum film thickness, or film parameter, which is the ratio of minimum film thickness to surface roughness. Through numerical analyses, we showed that the profile of the lower edge of the stem had no effect on lubrication characteristics, but the profile of the upper edge had a significant influence on lubrication characteristics. In addition, changes in the profile were more effective in improving lubrication characteristics under low viscosity conditions.

• 한국조명전기설비학회지:조명전기설비
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• 제10권5호
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• pp.83-93
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• 1996

본 연구는 부하변동이 갖은 유도 전송기 속도제어 시스템에 적합한 최소분산제어 알고리즘을 제안하고 구현을 실제적인 파라미터 추정방법을 제안한다. 그리고 고속 연산 신호처리요 프로세인 TMS 320C25를 이용한 제어 시스템을 구성한다. 적응칙은 선택적 망각인자를 갖는 순환형 최소자승법이 실제적 구현의 관점에서 언급되며, 일반적인 망각인자 알고리즘과 비교분석한다. 제어칙은 최소분산 제어 알고리즘으로 한다. 제어시스템은 알고리즘의 적용이 용이하도록 PC에 기초한 DSP제어 시스템으로 설계 제작한다. 시뮬레이션과 실험을 통하여, 본 연구의 초소분산제어 시스템이 부하변동에 강인한 구조를 갖고 있으며 유도전동기 제어에 실제적 구현이 가능함을 입증한다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.321-325
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• 2004

Linear motor feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modem machine tools require high speed and high precision feed drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slides system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a linear motor, for its minimum vibrations. Firstly, a 4-degree-of-freedom lumped parameter model is proposed for the vibration analysis of a linear motor driven machine tool feed drive system. Next, a feed rate optimization of the feed slide is carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile with jerk continuity. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.752-760
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• 2018

In this paper, interior permanent magnet synchronous motor (IPMSM) design for sensorless drive, considering magnetic neutral point shift according to magnetic saturation, has been proposed. Sensorless control was divided into a method based on inductance and a method based on back induced voltage. Because induced voltage is very small at zero or low speed, error in rotor initial position estimation may occur. Using the ratio of saliency addresses this problem. When using high-frequency injections at low speed, the rotor's initial position is estimated at the smallest portion of the inductance. IPMSM has the minimum inductance at the d-axis. However, if magnetic saturation leads to magnetic neutral point variation, following the load current change, there is a change in the minimum point of inductance. In this case, it can lead to failure of initial rotor position estimation. As a result, it is essential that the blocking design has an inductance minimum point shift. As such, in this study, an IPMSM design method, by blocking magnetic neutral point change, has been proposed. After determining the inductance profile based on the finite element analysis (FEA), the results of proposed method were verified.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.962-966
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• 2004

Ball screw feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modern machine tools require high speed and high precision and drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slide system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a ball screw, for its minimum vibrations. Firstly, a 6-degree-of-freedom lumped parameter model was proposed for the vibration analysis of a ball screw driven machine tool feed drive system. Next, a feed rate optimization of the feed slide was carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile having finite jerk. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

• 대한교통학회지
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• 제17권1호
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• pp.19-28
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• 1999

본 논문은 고속도로의 오르막차로 구간을 대상으로 종점부의 설계기준을 제시하고자 하는 목적으로 미시적 관점에서 교통행태를 규명할 수 있는 임계간격 모형과 합류확률 모형식을 개발하였다. 오르막차로 종점부 최저허용속도의 분석결과는 2차로 고속도로에서는 60km/hr, 4차로 고속도로에서는 75km/hr로 나타나 2차로에서는 현행기준과 동일하고 4차로의 경우는 현행기준 보다 약 15km/hr정도 높게 적용하는 것이 바람직한 것으로 분석되었다. 또한 오르막차로 종점부 부가길이 산출결과는 오르막차로 종점부 최저허용속도 기준과 비교해볼 때 4차로 고속도로의 경우, 부가길이가 약 200m 정도 필요한 것으로 나타나 오르막차로 종점부 최저허용속도를 상향시킬 필요가 있는 것으로 분석되었다.

• 해양환경안전학회지
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• 제27권4호
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• pp.474-482
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• 2021

우리나라는 지리적 위치와 편서풍의 영향을 받아 필리핀이나 대만 근처에서 전향한 태풍이 매년 평균 2~3개 통과한다. 진해만은 우리나라의 대표적인 태풍 피항지로 알려져 있으며, 태풍 내습 시 피항 선박들로 가득차고 나중에는 주변 항로까지 묘박한 선박들로 포화상태에 이르게 된다. 이로 인하여 묘박중인 선박이 강풍으로 주묘가 발생될 경우에는 선박 간 이격거리가 짧아 충돌사고가 발생될 수 있으므로 진해만의 체계적인 묘박 안전관리가 필요한 실정이다. 따라서 본 연구에서는 진해만 묘박지 수심에 따른 선박 톤수별 주묘 한계 풍속을 제시하였다. 수심 20 m에서는 묘쇄를 7~9 Shackles 신출하였을 때 주묘 발생 한계 풍속은 48~63 knots, 수심 35 m에서는 46~61 knots, 수심 50 m에서는 39~54 knots로 평가되었다. 수심이 증가하면서 외력에 의해 파주부가 5 m 미만이 되는 상황이 발생하면서 주묘가 발생하는 한계 풍속은 4~8 knots로 큰 차이를 보였다. 또한 고파주력 앵커(AC-14형)가 설치된 선박이 재래형 앵커(ASS형)가 설치된 선박보다 주묘 한계 풍속이 더 크게 평가되었지만, 수심이 50 m로 깊은 곳에서는 고파주력 앵커를 사용하더라도 주묘가 쉽게 발생될 수 있는 것으로 확인되었다.