• Title/Summary/Keyword: reverse current

Search Result 697, Processing Time 0.024 seconds

Design and Implementation of a Reverse Matrix Converter for Permanent Magnet Synchronous Motor Drives

  • Lee, Eunsil;Lee, Kyo-Beum
    • Journal of Electrical Engineering and Technology
    • /
    • v.10 no.6
    • /
    • pp.2297-2306
    • /
    • 2015
  • This paper presents the development of a system with a reverse matrix converter (RMC) for permanent magnet synchronous motor (PMSM) drive and its effective control method. The voltage transfer ratio of the general matrix converter is restricted to a maximum value of 0.866, which is not suitable for applications whose source voltages are lower than the load voltages. The proposed RMC topology can step up the voltage without any additional components in the conventional circuit. Its control method is different from traditional matrix converter’s one, thus this paper proposes control schemes of RMC by means of controlling both the generator and motor side currents with properly designed control loop. The converter can have sinusoidal input/output current waveforms in steady state condition as well as a boosted voltage. In this paper, a hardware system with an RMC for a PMSM drive system is described. The performance of the system was investigated through experiments

J-R Curve Evaluation According to the Crack Length Measurement Techniques Under Reverse Cyclic Loading (역사이클하중하에서의 균열길이 측정법에 따른 파괴저항곡선의 평가)

  • 원종일;우흥식;석창성
    • Journal of the Korean Society of Safety
    • /
    • v.13 no.4
    • /
    • pp.96-101
    • /
    • 1998
  • J-R curve tests were performed on 1T compact specimens of SA516 Gr. 70 carbon steels under reverse cyclic loading. A Direct-Current Potential Drop (DCPD) method, one of the nondestructive techniques to detect flaw of structure, is being increasingly used for monitoring crack initiation and stable crack growth in typical fracture mechanics specimens for J-R testing. In many aspects this method is simpler than the unloading compliance method. The objective of this paper is to evaluate the J-R Curve according to the crack length measurement techniques under reverse cyclic loading. In order to prove the reliability and repeatability of the DCPD method, the crack length measured by using DCPD method was compared to one determined from unloading compliance. Consequently, this DCPD method correlated well with J-R curves and crack extension measurements determined from unloading compliance method.

  • PDF

Identification and Extraction of Reusable Linear Programming Model Components (재사용 가능한 성형계획모형 요소의 인식과 추출에 관한 연구)

  • 박성주;권오병
    • Journal of the Korean Operations Research and Management Science Society
    • /
    • v.18 no.3
    • /
    • pp.79-100
    • /
    • 1993
  • This paper proposes an idea of reverse modeling that analyzes LP models and then converts them into an object-oriented model repository. The process of reverse modeling consists of (1) identifying and analyzing source models by meta processor, (2) model decomposition and generalization to scan the models and divide them into model components, and (3) deriving model selection rules from the components by rule generator. Through the process, we can extract reusable model components and build a model base with model selectioon rules. Examples with models created by SML and MODLER modeling languages are given to illustrate the methods. The model base management capabilities provided by reverse modeling can increase the reusabioity of current modeling tools.

  • PDF

Sensitivity of Hot Film Flow Meter in Four Stroke Gasoline Engine

  • Lee, Gangyoung;Lee, Cha--Myung;Park, Simsoo;Youngjin Cho
    • Journal of Mechanical Science and Technology
    • /
    • v.18 no.2
    • /
    • pp.286-293
    • /
    • 2004
  • The air fuel ratios of current gasoline engines are almost controlled by several air flow meters. When CVVT (Continuous Variable Valve Timing) is applied to a gasoline engine for higher engine performance, the MAP (Manifold Absolute Pressure) sensor is difficult to follow the instantaneous air fuel ratio due to the valve timing effect. Therefore, a HFM (Hot Film Flow Meter) is widely used for measuring intake air flow in this case. However, the HFMs are incapable of indicating to reverse flow, the oscillation of intake air flow has an negative effect on the precision of the HFM. Consequently, the various duct configurations in front of the air flow sensor affect the precision of HFM sensitivity. This paper mainly focused on the analysis of the reverse flow, flow fluctuation in throttle upstream and the geometry of intake system which influence the HFM measurement.

Selective Dual Duty Cycle Controlled High Frequency Inverter Using a Resonant Capacitor in Parallel with an Auxiliary Reverse Blocking Switch

  • Saha, Bishwajit;Suh, Ki-Young;Kwon, Soon-Kurl;Mishima, Tomokazu;Nakaoka, Mutsuo
    • Journal of Power Electronics
    • /
    • v.7 no.2
    • /
    • pp.118-123
    • /
    • 2007
  • This paper presents a new ZCS-PWM high frequency inverter. Zero current switching operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. Dual duty cycle control scheme is used to provide a wide range of high frequency AC output power regulation that is important in many high frequency inverter applications. It found that a complete soft switching operation can be achieved even for low power setting ranges by introducing high-frequency dual duty cycle control scheme. The proposed high frequency inverter is more suitable for consumer induction heating(IH) applications. The operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

COD removal from industrial wastewater plants using reverse osmosis membrane

  • Madaeni, S.S.;Samieirad, S.
    • Membrane and Water Treatment
    • /
    • v.1 no.4
    • /
    • pp.273-282
    • /
    • 2010
  • Treatment and reuse of industrial wastewater is becoming a major goal due to water scarcity. This may be carried out using membrane separation technology in general and reverse osmosis (RO) in particular. In the current study, polyamide (FT-30) membrane was employed for treatment of wastewater obtained from Faraman industrial zone based in Kermanshah (Iran). The effects of operating conditions such as transmembrane pressure, cross flow velocity, temperature and time on water flux and rejection of impurities including COD by the membrane were elucidated. The aim was an improvement in membrane performance. The results indicate that most of the chemical substances are removed from the wastewater. In particular COD removal was increased from 64 to around 100% as temperature increased from 15 to $45^{\circ}C$. The complete COD removal was obtained at transmembrane pressure of 20 bars and cross flow velocity of 1.5 m/s. The treated wastewater may be reused for various applications including makeup water for cooling towers.

Software Reliability of Safety Critical FPGA-based System using System Engineering Approach

  • Pradana, Satrio;Jung, Jae Cheon
    • Journal of the Korean Society of Systems Engineering
    • /
    • v.14 no.2
    • /
    • pp.49-57
    • /
    • 2018
  • The main objective of this paper is come up with methodology approach for FPGA-based system in verification and validation lifecycle regarding software reliability using system engineering approach. The steps of both reverse engineering and re-engineering are carried out to implement an FPGA-based of safety critical system in Nuclear Power Plant. The reverse engineering methodology is applied to elicit the requirements of the system as well as gain understanding of the current life cycle and V&V activities of FPGA based-system. The re-engineering method is carried out to get a new methodology approach of software reliability, particularly Software Reliability Growth Model. For measure the software reliability of a given FPGA-based system, the following steps are executed as; requirements definition and measurement, evaluation of candidate reliability model, and the validation of the selected system. As conclusion, a new methodology approach for software reliability measurement using software reliability growth model is developed.

Development of a 3D earthwork model based on reverse engineering

  • Kim, Sung-Keun
    • International conference on construction engineering and project management
    • /
    • 2015.10a
    • /
    • pp.641-642
    • /
    • 2015
  • Unlike for other building processes, BIM for earthwork does not need a large variety of 3D model shapes; however, it requires a 3D model that can efficiently reflect the changing features of the ground shape and provide soil type-dependent workload calculation and information on equipment for optimal management. Objects for earthwork have not yet been defined because the current BIM system does not provide them. The BIM technology commonly applied in the manufacturing center uses real-object data obtained through 3D scanning to generate 3D parametric solid models. 3D scanning, which is used when there are no existing 3D models, has the advantage of being able to rapidly generate parametric solid models. In this study, A method to generate 3D models for earthwork operations using reverse engineering is suggested. 3D scanning is used to create a point cloud of a construction site and the point cloud data are used to generate a surface model, which was then converted into a parametric model with 3D objects for earthwork

  • PDF

An Improved Current Control Method for Torque Improvement of High Speed BLDC Motor (고속도 BLDC 전동기의 토크 향상을 위한 개선된 전류 저어 방법)

  • Park Sung-In;Kim Tae-Sung;Hyun Dong-Seok
    • Proceedings of the KIPE Conference
    • /
    • 2002.07a
    • /
    • pp.115-118
    • /
    • 2002
  • In this paper, a current control method using adjustment of the phase advance angle is proposed. This proposed method improves the torque and speed response characteristic by minizing delay of current at high speed operation, and also make reverse motoring possible. Simulated results prove the effectiveness of the propposed method through comparison with the conventional unipolar PWM method.

  • PDF

Risk Factors Related to Photo Couplers(P/C) for Signal Transmission by Electronic Devices (전자기기의 신호전송을 위한 Photo Couplers(P/C) 의 위험 요소 발굴)

  • Park, Hyung-Ki;Choi, Chung-Seog
    • Journal of the Korean Society of Safety
    • /
    • v.28 no.2
    • /
    • pp.26-30
    • /
    • 2013
  • The purpose of this study is to find risk factors by analyzing the operation principle of a photo coupler (P/C) used to remove the noise of electronic devices and establish a base for the performance improvement of developed products. It was found from the P/C circuit analysis of normal products that they were equipped with an electrolytic condenser of $0.1{\mu}F$ to smooth system signals. Due to the epoxy resin packing the external part of the P/C, this study experienced a limit to visually examine the damage to it. It could be seen from the analysis of electric characteristics of the P/C that the forward voltage ($V_f$) and reverse current ($I_r$) were 1.3 V and 10 uA, respectively. In addition, it is required that the breakdown voltage (VCE) between the collector (C) and emitter (E) be maintained at less than 35 V. The and of the damaged product #1 were comparatively good. However, the measurement of was 100.0 uA. From this, it is thought that a short circuit occurred to the internal circuit. Moreover, from the fact that the of the damaged product #2 was open circuit and the measurement of was 0.0 uA, it is thought that the collector and emitter was separated or insulation resistance was significantly high. Furthermore, from the fact that the of the damaged product #3 was open circuit and the measurement of was 0.0 uA, it is thought that the space between the collector (C) and emitter (E) failed to meet the design standard or that they were separated. Therefore, it is thought that fabricating the P/C by increasing the reverse current 10 mA to 50 mA will prevent its malfunction.