• Title/Summary/Keyword: Two-Pole Rotor

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Non-destructive Evaluation to Assess Leak of Bond in Brazed Large Generator ″ C″ -Coil by Ultrasonic Retro-Reflection (초음파 Retro-Reflection에 의한 대형 발전기용 C-Coil Brazed부의 비파괴적 평가)

  • 성운학;양병일;김정태
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.305-307
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    • 2004
  • One set of rotor coils is required per each large generator rotor assembly, Rotors consist of two directly opposing poles. Each pole requires from 5 to 9 coils. Each coil is made up of two halves identified on the connection end. These coil halves will be joined together by butt brazing process during subsequent rotor assembly. Each half coil is made up of typically 4 to 9 layers of copper conductors. Because of Generator rotor is rotated very high speed with 3,600RPM, the quality soundness of brazed joints is very important at each coil. But, it is very difficult to be optimized non-destructive evaluation, because c-coil has the long shape and evaluation is to be done assembled condition. In this paper introduce newly developed inspection process and acceptance standards for the ultrasonic inspection of " C" coil butt braze. This inspection system is a semi-automatic ultrasonic flaw detector with data acquisition and retention capable of assessing the relative lack of bond of brazed butt joints

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Analytical Prediction for the Cogging Torque of the Permanent Magnet Machines With Multi-Pole Rotor (다극회전자를 갖는 영구자석기기의 코깅토크에 대한 해석적 예측)

  • Jang, Seok-Myeong;Choi, Jang-Young;Ko, Kyoung-Jin;Park, Ji-Hoon
    • Proceedings of the KIEE Conference
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    • 2007.04c
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    • pp.56-58
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    • 2007
  • This paper deals with analytical prediction for the cogging torque of permanent magnet machines with multi-pole rotor First. open-circuit field solutions are derived using a magnetic vector potential and a two-dimensional (2-d) polar coordinate systems. On the basis of derived open-circuit field solutions and 2-d permeance functions. we also derive the analytical solutions for the open-circuit field considering stator slotting effects and cogging torque. All analytical results are shown in goof agreement with those obtained from finite element (FE) analyses.

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Three-dimensional Forging Simulation with Tetrahedral Elements and Hexahedral Elements and their Comparison with Experiments (사면체요소와 육면체요소를 이용한 삼차원 단조 시뮬레이션 결과의 비교 및 검증)

  • Lee, Min-Cheol;Baek, Jong-Pa;Joun, Man-Soo
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1637-1641
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    • 2007
  • In this paper, we simulate a rotor pole cold forging process by a forging simulator with both tetrahedral and hexahedral element capabilities and compare the predictions obtained by the two approaches with the experiments. Hexahedral element capability runs manually while tetrahedral element capability runs automatically with help of an intelligent remeshing technique. It is shown that the tetrahedral element capability can give quite accurate solution if assisted by the intelligent remeshing technique even though the tetrahedral element itself is not theoretically and numerically clear.

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A Shape Optimization of Universal Motor using FEM and Evolution Strategy

  • Shin, Pan-Seok
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.2B no.4
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    • pp.156-161
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    • 2002
  • This paper proposes an optimized universal motor for improving its performance using the finite element method (FEM) with the (1+1) Evolution Strategy (ES) algorithm. To do this, various design parameters are modified, such as air gap length, shape of motor slot, pole shoe, pole width, and rotor shaft diameter. Two parameters (arc length of stator pole and thickness of pole shoe) are chosen and optimized using the program, and the optimized model is built and tested with a performance measuring system. The measured values of the model are compared with those of the initial and the optimized model to prove the algorithm. As a result, the final model improves its performance compared with those of the initial model.

A Low Cost Position Sensing Method of Switched Reluctance Motor Using Reflective Type Optical-sensors (반사형 광센서를 이용한 저가형 SRM 위치검출기법)

  • Kim S.J.;Yoon Y.H.;Won C.Y.;Kim H.S.
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.2
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    • pp.148-154
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    • 2005
  • As the exciting point of each phase is determined by the position of rotor, the rotor's accurate position-information is needed for the Switched Reluctance Motor(SRM). When using an absolute-encoder or a resolver, to detect the location of rotor the initial starting is possible, as early sensing of rotor's location is possible. However, this is not appropriate, considering the economical efficiency, and in case of using the incremental-encoder, there's a problem at initial starting as it is not easy to track down the location of rotor at the very beginning. When using Hall-ICs, there's a fault, as it needs a special ring magnet. Considering the initial starting and economical efficiency, the optical sensor technique using a slotted-disk and an opto-interrupter is appropriate, however, this method needs three opto-interrupters and a slotted-disk when using the 6/4 pole SRM. Nevertheless, in this paper, it used only two optical sensors to operate 6/4 pole SRM and made the start up and also forward and reverse operation possible. By excluding the slotted-disc md shortening a optical sensor, it improved the convenience and economical efficiency of the production. Also, as the space for slotted-disc is no more needed, it was able to reduce the size of motor.

High Speed Performance Improvement of the WRSM and its Comparison with the IPMSM (고속 운전 시 WRSM의 성능 향상 및 IPMSM과 비교)

  • Chae, Woong-Chan;Kim, Mi-Jung;Lee, Ki-Doek;Lee, Jae-Jun;Han, Jung-Ho;Jung, Tae-Chul;Lee, Ju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.11
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    • pp.1595-1600
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    • 2012
  • This paper shows an improvement of the WRSM (Wound Rotor Synchronous Motor) by satisfying the voltage limit condition at high speed. After that, it compares the performance of the improved WRSM to that of the IPMSM (Interior Permanent Magnet Synchronous Motor). The comparison has been made under the condition where the dimension of the motor is identical to that of the IPMSM, having the rotor switched to a wounded rotor form. Moreover, this paper compares the Basic Model of the two motor, and estimates the parameters of the WRSM, thereby proposing the method to improve high speed performance. Furthermore, this paper presents the feasibility of switching the conventional motor into rare-earth-free motors for traction purpose.

Development of Shorted-Turn Diagnosis system for Generator Rotor Winding (발전기 회전자 권선의 층간단락 진단시스템 개발)

  • Lee, Yeong-Jun;Kim, Hui-Dong;Ju, Yeong-Ho
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.11
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    • pp.742-747
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    • 1999
  • On-line diagnosis system has been developed and is now applied the detection of shorted turns in the field winding of large generator. This system consists of data aquisition system and display PC. The data aquisition system detects voltage waveforms from flux probe sensor installed in the stator slot. The display PC shows theshorted-turn situation of generator rotor winding. A shorted-turn diagnosis test wasperformed on five gas turbine generators at the Seoinchon combined cycle power plant. The test was conducted using an new diagnosis system and digital oscilloscope which can identify the pole location, the slot number and the number of shorted turns within each slot. It is confirmed that results of two systems are very same in the field tests.

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LMI-based $H_\infty$ Robust Control of Asymmetric Rotor-magnetic Bearing System (비대칭 로터-자기베어링 시스템의 LMI에 기초한 $H_\infty$ 강건제어)

  • 강호식;송오섭
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.3
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    • pp.172-179
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    • 2003
  • Linear matrix Inequality based $H_\infty$ robust controller is designed to control the motion of a 4-axis unbalanced rigid asymmetric rotor supported and controlled by two active magnetic bearings in this paper. To this end, the equations of motion of the system are derived via Hamilton's variational principle and transformed to a state-space form for the standard $H_\infty$ control problem. LMI-based controller, which does not require additional assumptions beyond the usual stabilizability and detectability assumptions, is designed based upon the pole place weighting function and loopshaping technique. The obtained results are compared with those reported in the available literature and the efficiency of the proposed LMI-based $H_\infty$ control is revealed.

Electromagnetic Structural Design Analysis and Performance Improvement of AFPM Generator for Small Wind Turbine

  • Jung, Tae-Uk;Cho, Jun-Seok
    • Journal of Magnetics
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    • v.16 no.4
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    • pp.374-378
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    • 2011
  • Axial Field Permanent Magnet (AFPM) generators are widely applied for the small wind turbine because of the higher power density per unit weight than that of the conventional radial field generator. It is caused by the disc shaped rotor and the stator structures. The generally used AFPM generator, AFER-NS generator, is composed of the two side's external rotors and non-slotted stator without stator core. However, the output voltage and the output power are limited by the large reluctance by the long air-gap flux paths. In this paper, the design study of AFIR-S generator having double side's slotted stator core is accomplished to improve the output generation characteristics. The electromagnetic design analysis and the design improvement of the suggested AFIR-S generator are studied. Firstly, the electromagnetic design analysis was done to increase the power density. Secondly, the design optimizations of the rotor pole-arc ratio of permanent magnet are accomplished to increase the output power and to reduce the cogging torque. Finally, the output performances of AFER-NS and AFIR-S generator are compared with each other. For this study, 3D FEA is applied for the design analysis because of three dimensional electromagnetic structures.

High Speed Segmental Stator Type 4/3 SRM: Design, Analysis, and Experimental Verification

  • Hieu, Pham Trung;Lee, Dong-Hee;Ahn, Jin-Woo
    • Journal of Electrical Engineering and Technology
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    • v.12 no.5
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    • pp.1864-1871
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    • 2017
  • This paper presents a design of a 2-phase segmental stator type 4/3 switched reluctance motor (SRM) for air-blower application. The air-blower requires only one direction rotation, high rotor speed without torque dead-zone. In order to satisfy the requirements of the load, the rotor of the 4/3 proposed SRM is designed with wider rotor pole arc and non-uniform air-gap is applied on the rotor shape. With a special rotor structure, the motor generates a wider positive torque region and has no torque dead-zone. The stator of the proposed SRM is constructed with two segmental C-cores, and there are no magnetic connections between 2 C-cores. The flux follows in a short closed loop in each C-core and has no reversal flux in the stator. The static and dynamic characteristics of the proposed motor are analyzed by the finite element method (FEA) and Matlab-Simulink, respectively. In order to verify the design, a prototype of the proposed motor has manufactured for laboratory test. The performance of the proposed motor is verified by the simulation and experimental results.