• 대한기계학회논문집A
• /
• 제39권2호
• /
• pp.211-217
• /
• 2015

환경 문제 및 화석연료 고갈에 대한 관심으로 인하여 배기가스에 대한 규제는 나날이 엄격해지고 있으며 높은 연비에 대한 수요는 지속적으로 증가하고 있다. 이러한 시대적 요구를 뒷받침하기 위하여 저배기-고연비가 특징인 하이브리드 굴삭기가 현실적인 대안으로서 각광받고 있으며 지속적으로 연구되고 있다. 본 연구에서는 선회 구동 전동기, 엔진보조 전동기, 울트라 캐패시터, 전력변환장치를 중형 굴삭기에 탑재한 복합형 하이브리드 굴삭기를 개발하였으며, 일반적인 복합형 하이브리드 굴삭기의 연비개선요소(선회 구동 에너지 회생, 엔진 작동 속도 변경)외에 추가적으로 적용된 연비개선 방법론들에 대하여 다루고 있다. 본 방법론들을 적용함으로써 연비와 운전 조작성을 동시에 개선할 수 있었다.

• 한국정보통신학회논문지
• /
• 제15권2호
• /
• pp.425-431
• /
• 2011

전기추진선박에서 해결해야 할 중요한 문제점의 하나는 전력변환시에 발생되는 전류 및 전압파형에 포함된 고조파 성분에 의한 손실과 토크리플이다. 이를 제거하기 위해서 많은 방식들이 연구되고 있으며 본 논문에서는 상천이 변압기를 갖는 다중펄스 드라이브를 사용하여 정류된 직류파형을 개선함으로서 전류 및 전압파형에 포함되는 고조파 성분을 감소시키는 방식을 사용하였다. 또한, 그 유효성을 입증하기 위해서 6펄스 및 12펄스 드라이브를 각각 전력변환장치로 사용하였으며 현재 대형 선박에서 사용중인 6000[kW]의 유도전동기를 추진전동기로 채택하여 시뮬레이션을 행하였다. 다중펄스 드라이브에 의한 고조파 저감은 발전기 출력측의 전류파형과 추진전동기 입력측의 전압 파형에 포함된 총고조파 왜형율을 평가하였으며 또한, 고조파에 의한 전동기측의 영향은 추진전동기의 토크리플을 측정하여 비교 분석하였다.

• International journal of advanced smart convergence
• /
• 제11권3호
• /
• pp.222-228
• /
• 2022

As a means to cope with the climate change crisis caused by global warming, automobile manufacturers continue to make efforts to use the driving energy of vehicles as electricity. As a result, parts industry such as battery, motor, and controller are attracting attention. China is often seen in large cities, with electric vehicles such as electric bicycles, electric motorcycles, and small electric vehicles popularized and commercialized, mainly in large cities. However, small electric vehicles are not popular in Korea, which is why the country's topography is high in hills. In order to drive the hilly domestic roads, power performance including vehicle climbing ability should be improved. In order to improve the power performance and the climbing capacity of small electric vehicles, the capacity of the motor should be increased. However, when the performance of the motor is improved, the weight of the motor becomes heavy and the price competitiveness is likely to decrease. In addition, in order to operate a high-performance motor, the power consumption of the battery is rapidly increased, so various problems must be solved. In order to commercialize a small electric vehicle for one or two people who do not emit harmful exhaust gas to the human body in a hilly domestic terrain, it is effective to have a separate transmission system. In this study, we were conducted dynamometer test to produce a continuously variable transmission(CVT) system prototype using a spring that can be applied to a small electric vehicle and to install a CVT system prototype manufactured in a small electric vehicle. The dynamometer test results showed that the maximum speed performance, acceleration performance, and climbing performance were improved.

• 설비공학논문집
• /
• 제4권1호
• /
• pp.33-47
• /
• 1992

Experimental investigation on the performance of a heat pump system using refrigerant mixtures is done. The condenser and the evaporator are double pipe heat exchangers of counter flow type and the compressor is driven by a variable speed motor. The refrigerant mixture used in the experiment is R22/R142b. Experiments are performed by changing the compressor speed, composition on ratio of mixture, and the average temperatures of condenser and evaporator. The compressor work, heating capacity and the coefficient of performance are calculated. Results show that the heating capacity can be changed by varying the mass flow rate of refrigerant mixtures to meet the heating load. It is shown that the capacity control by changing the composition ratio is more effective than by changing the compressor speed. Under the condition where the external conditions are fixed and the heating loads are equal, the coefficient of performance has its maximum value near 50 : 50 mass fraction of the refrigerant mixture in this study.

• 한국인터넷방송통신학회논문지
• /
• 제23권4호
• /
• pp.143-148
• /
• 2023

SRM의 특성 중 비선형성으로 인해 최대토크 및 최소 토크 맥동 형성을 위한 적정 운전이 어렵다. 또한 고정 스위칭각 제어 때 속도 가변에 따른 토크 형성이 불안정하여 효율을 저하시키는 문제점을 가지고 있다. 따라서 속도 가변에 따른 능동적인 스위칭각 제어가 필요하다. 본 논문에서는 SRM의 비선형성으로 인한 문제점으로부터 선행각 (Advance angle)의 자동제어에 의한 토크 리플 저감과 이에 따른 출력 토크 향상에 의한 구동 성능개선을 위한 방법에 대해 모색하였다. 또한 히스테리시스 전류제어기 성능에 따른 스위칭 가변으로 인한 SRM의 최적 운전에 대해 살펴보았다.

• 반도체디스플레이기술학회지
• /
• 제22권3호
• /
• pp.8-13
• /
• 2023

High bandwidth memory a core technology of the future memory semiconductor industry, is attracting attention. Temporary bonding and debonding process technology, which plays an important role in high bandwidth memory process technology, is also being studied. In this process, total thickness variation is a major factor determining wafer performance. In this study, the reliability of the equipment measuring total thickness variation is identified, and the servo motor settling, and wafer total thickness variation measurement accuracy are analyzed. As for the experimental variables, vacuum, acceleration time, and speed are changed to find the most efficient value by comparing the stabilization time. The smaller the vacuum and the larger the radius, the longer the settling time. If the radius is small, high-speed rotation performance is good, and if the radius is large, low-speed rotation performance is good. In the future, we plan to conduct an experiment to measure the entire of the wafer.

• 한국산학기술학회논문지
• /
• 제20권4호
• /
• pp.35-42
• /
• 2019

현재 자동차 산업과 함께 발전하고 있는 전자제품을 포함하는 전반적인 제조업 분야에서 초정밀 제어를 요하는 너트 체결기가 요구되고 있고 너트 체결시의 중요한 성능 요소는 체결력 부족에 의한 풀림과 과도한 체결에 의한 파손 및 강한 진동이나 외부 충격에 강건한 체결력 유지 등 조립 품질의 유지와 향상 및 제품 수명 보장을 위해 정확한 조임 토크, 각도 등이 요구된다. 현재 너트런너라는 제품명으로 판매되는 너트 체결기는 고토크 및 정밀토크제어, 정밀 각도제어 그리고 생산량 증대를 위한 고속운전 등의 특성들이 필요하며 고출력이 가능한 BLDC모터 및 너트체결기 전용의 정교한 토크제어에 필요한 고정밀 토크제어드라이버와 고속, 저속, 고응답의 정밀 속도 제어시스템의 개발이 요청되고 있으나 현재 고객이 요구하는 고정밀, 고토크 및 고속 작업특성을 만족시키지 못하고 있다. 따라서 본 논문에서는 정확한 체결 토크 및 고속 회전에서도 저진동 및 저소음을 구현할 수 있는 d축, q축의 좌표변환에 의한 벡터제어와 토크제어기반의 BLDC모터 가변속 제어와 너트런너의 제어 기술을 제안하고 여러 실험을 통해 성능 결과를 분석하여 제안한 제어가 너트런너 성능을 만족하는지를 확인 하였다. 또한 일단 운전 체결 방식(One Stage 운전 체결 방식)으로 패턴을 프로그램하여 10,000[rpm] 고속 운전 후 목표 토크로 정확히 체결됨을 확인하였으며 토크 리플에 의한 가체결 토크 검출의 문제점도 외란관측기을 사용하여 해결하였고 실험을 통해 검증하였다.

• Journal of Biosystems Engineering
• /
• 제41권1호
• /
• pp.12-20
• /
• 2016

Purpose: Pepper prices have risen continuously because of a decrease in cultivation area; therefore, mechanical harvesting systems for peppers should be developed to reduce cost, time, and labor during harvest. In this study, a screw type picking head for a self-propelled pepper harvester was developed, and the optimal working conditions were evaluated considering helix types, winding directions of helix, and rotational speeds of the helix. Methods: The screw type was selected for the picking head after analyzing previous studies, and the device consisted of helices and a feed chain mechanism for conveying pepper branches. A double helix and a triple helix were manufactured, and rotational speeds of 200, 300, and 400 rpm were tested. The device was controlled by a variable speed (VS) motor and an inverter. Both the forward and reverse directions were tested for the winding and rotating directions of the helix. An experiment crop (cultivar: Longgreenmat) was cultivated in a plastic greenhouse. The test results were analyzed using the SAS program with ANOVA to examine the relationship between each factor and the performance of the picking head. Results: The results of the double and triple helix tests in the reverse direction showed gross harvest efficiency levels of 60-95%, mechanical damage rates of 8-20%, and net marketable portion rates of 50-80%. The dividing ratio was highest at a rotational speed of 400 rpm. Gross harvest efficiency was influenced by the types of helix and rotational speed. Net marketable portion was influenced by rotational speed but not influenced by the type of helix. Mechanical damage was not influenced by the type of helix or rotational speed. Conclusions: Best gross harvest efficiency was obtained at a rotational speed of 400 rpm; however, operating the device at that speed resulted in vibration, which should be reduced.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제16권4호
• /
• pp.238-245
• /
• 2016

Inverters are considered the basic building blocks of industrial electrical drive systems that are widely used for various applications; however, the failure of electronic switches mainly affects the constancy of these inverters. For safe and reliable operation of an electrical drive system, faults in power electronic switches must be detected by an efficient system that is capable of identifying the type of faults. In this paper, an open switch fault identification technique for a three-phase inverter is presented. Single, double, and triple switching faults can be diagnosed using this method. The detection mechanism is based on stator current analysis. Discrete wavelet transform (DWT) using Daubechies is performed on the Clarke transformed (-) stator current and features are extracted from the wavelets. An artificial neural network is then used for the detection and identification of faults. To prove the feasibility of this method, a Simulink model of the DWT-based feature extraction scheme using a neural network for the proposed fault detection system in a three-phase inverter with an induction motor is briefly discussed with simulation results. The simulation results show that the designed system can detect faults quite efficiently, with the ability to differentiate between single and multiple switching faults.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1991년도 하계학술대회 논문집
• /
• pp.611-614
• /
• 1991

In variable speed driving system of three phase induction motor controlled by an inverter, because of the switching of semiconductor devices in inverter, an appreciable amount of harmonic components of voltage waveform can cause the motor to generate losses, torque ripple, acoustic noise and oscillation of semiconductor devices. In this paper a new PAM type PWM inverter using IGBT is described. The output waveforms in the proposed PAM type PWM inverter are investigated both theoretiically and experimentally. The line-voltage waveform is composed of fundamental component and the sidebands of carrier frequency. The lower order harmonics are not included in the output wave form. As each inverter arm does not operate during two-thirds period, the heats, generated in the devices are reduced. That is, the size of the inverter system can he minimized because of the reduction in the heat dissipating equipment.