• Title/Summary/Keyword: synchronous generator

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Conceptual Design of Electric-Pump Motor for 50kW Rocket Engine (50kW급 로켓 엔진용 전기펌프 모터의 개념 설계)

  • Kim, Hong-Kyo;Kwak, Hyun-Duck;Choi, Chang-Ho;Kim, Jeong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.2
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    • pp.175-181
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    • 2018
  • Electric pump system is new technology for next generation propulsion unit. The system has simple structure which dose not need gas generator, injector and turbine and might better pump for low cost and low payload rocket. Therefore, this paper suggests conceptual design of electric-pump Permanent-Magnet Synchronous Motor (PMSM) which has 50 kW & 50,000 RPM for rocket. To satisfy the system's requirement, electromagnetic analysis is conducted for suitable inner and outer diameter of stator and rotor which uses 4000 Gauss cylinder magnet and Inconel 718 can to fix whole rotor. Futhermore, to confirm rotational vibration, rotordynamics analysis is conducted. By this analysis, Campbell diagram is printed. From the diagram, natural frequency could be determined for the only motor and dynamo meter test bench.

Development and Performance Test of a l00hp HTS Motor

  • Sohn, M.H.;Baik, S.K.;Lee, E.Y.;Kwon, Y.K.;Yun, M.S.;Moon, T.S.;Park, H.J.;Kim, Y.C.;Ryu, K.S.
    • Progress in Superconductivity and Cryogenics
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    • v.6 no.4
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    • pp.27-31
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    • 2004
  • This paper describes the development and fabrication of a high temperature superconducting motor which consists of HTS rotor and air-core stator. The machine was designed for the rated power of 100hp at 1800 rpm. The HTS field windings are composed of the double-pancake coils wound with AMSC's SUS-reinforced Bi-2223 tape conductor. These were assembled on the support structure and fixed by a bandage of glass-fiber composite. The cooling system is based on the heat transfer mechanism of the thermosyphon by using GM cryocooler as cooling source. The cold head is in contact with the condenser of a Ne-filled thermosyphon. The rotor assembly was tested independently at the stationary state and combined with stator. Characteristic parameters such as reactances, inductances, and time constants were determined to obtain a consistent overview of the machine operation properties. This motor has met all design parameters by demonstrating HTS field winding, cryogenic refrigeration systems and an air-core armature winding cooled with air. The HTS field winding could be cooled down below 30K. No-load test of open-circuit characteristics(OCC) and short-circuit characteristics(SCC) and load test with resistive load bank were conducted in generator mode. Maximum operating current of field winding at 30K was 120A. From OCC and SCC test results synchronous inductance and synchronous reactance were 2.4mH, 0.49pu, respectively. Efficiency of this HTS machine was 93.3% in full load(100hp) test. This paper will present design, construction, and basic experimental test results of the 100hp HTS machine.

Low Power Clock Generator Based on An Area-Reduced Interleaved Synchronous Mirror Delay Scheme (면적을 감소시킨 중첩된 싱크러너스 미러 지연 소자를 이용한 저전력 클럭 발생기)

  • Seong, Gi-Hyeok;Park, Hyeong-Jun;Yang, Byeong-Do;Kim, Lee-Seop
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.39 no.8
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    • pp.46-51
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    • 2002
  • A new interleaved synchronous mirror delay(SMD) is proposed in order to reduce the circuit size and the power. The conventional interleaved SMD has multiple pairs of forward delay array(FDA) and backward delay away(BDA) in order to reduce the jitter. The proposed interleaved SMD. requires one FDA and one BDA by changing the position of multiplexer. Moreover, the proposed interleaved SMD solves the polarity problem with just one extra inverter. Simulation results show that about 30% power reduction and 40% area reduction are achieved in the proposed interleaved SMD. All circuit simulations and implementations are based on a 0.25um two-metal CMOS technology.

Compensation of Unbalanced PCC Voltage in Off-shore Wind Farms of PMSG Type Turbine

  • Kang, Jayoon;Han, Daesu;Suh, Yongsug;Jung, Byoungchang;Kim, Jeongjoong;Park, Jonghyung;Choi, Youngjoon
    • Proceedings of the KIPE Conference
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    • 2014.07a
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    • pp.215-216
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    • 2014
  • This paper proposes a control algorithm for permanent magnet synchronous generator with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage offshore wind power system under unbalanced grid conditions. The proposed control algorithm particularly compensates for the unbalanced grid voltage at the point of common coupling in a collector bus of offshore wind power system. This control algorithm has been formulated based on the symmetrical components in positive and negative rotating synchronous reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power are described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of ac input current is injected to the point of common coupling in the proposed control strategy. The amplitude of negative sequential component is calculated to minimize the negative sequential component of grid voltage under the limitation of current capability in a voltage source converter. The proposed control algorithm makes it possible to provide a balanced voltage at the point of common coupling resulting in the generated power of high quality from offshore wind power system under unbalanced network conditions.

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A DLL-Based Multi-Clock Generator Having Fast-Relocking and Duty-Cycle Correction Scheme for Low Power and High Speed VLSIs (저전력 고속 VLSI를 위한 Fast-Relocking과 Duty-Cycle Correction 구조를 가지는 DLL 기반의 다중 클락 발생기)

  • Hwang Tae-Jin;Yeon Gyu-Sung;Jun Chi-Hoon;Wee Jae-Kyung
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.42 no.2 s.332
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    • pp.23-30
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    • 2005
  • This paper describes a DLL(delay locked loop)-based multi-clock generator having the lower active stand-by power as well as a fast relocking after re-activating the DLL. for low power and high speed VLSI chip. It enables a frequency multiplication using frequency multiplier scheme and produces output clocks with 50:50 duty-ratio regardless of the duty-ratio of system clock. Also, digital control scheme using DAC enables a fast relocking operation after exiting a standby-mode of the clock system which was obtained by storing analog locking information as digital codes in a register block. Also, for a clock multiplication, it has a feed-forward duty correction scheme using multiphase and phase mixing corrects a duty-error of system clock without requiring additional time. In this paper, the proposed DLL-based multi-clock generator can provides a synchronous clock to an external clock for I/O data communications and multiple clocks of slow and high speed operations for various IPs. The proposed DLL-based multi-clock generator was designed by the area of $1796{\mu}m\times654{\mu}m$ using $0.35-{\mu}m$ CMOS process and has $75MHz\~550MHz$ lock-range and maximum multiplication frequency of 800 MHz below 20psec static skew at 2.3v supply voltage.

Pitching Motion Analysis of Floating Spar-buoy Wind Turbine of 2MW Direct-drive PMSG (2 MW 영구자석 직접 구동형 부유식 스파 부이 풍력 발전기의 피칭 운동해석)

  • Shin, Pyungho;Kyong, Namho;Choi, Jungchul;Ko, Heesang
    • Journal of the Korean Solar Energy Society
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    • v.37 no.1
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    • pp.1-14
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    • 2017
  • A series of coupled time domain simulations considering stochastic waves and wind based on five 1-h time-domain analyses are performed in normal operating conditions. Power performance and tower base Fore-Aft bending moment and pitching motion response of the floating spar-buoy wind turbine with 2 MW direct-drive PMSG have been analyzed by using HAWC2 that account for aero-hydro-servo-elastic time domain simulations. When the floating spar-buoy wind turbine is tilted in the wind direction, maximum of platform pitching motion is close to $4^{\circ}$. Statistical characteristics of tower base Fore-Aft bending moment of floating spar-buoy wind turbine are compared to that of land-based wind turbine. Maximum of tower base Fore-Aft bending moment of floating spar-buoy wind turbine and land-based wind is 94,448 kNm, 40,560 kNm respectively. This results is due to changes in blade pitch angle resulting from relative motion between wave and movement of the floating spar-buoy wind turbine.

A Magnetic Energy Recovery Switch Based Terminal Voltage Regulator for the Three-Phase Self-Excited Induction Generators in Renewable Energy Systems

  • Wei, Yewen;Kang, Longyun;Huang, Zhizhen;Li, Zhen;Cheng, Miao miao
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1305-1317
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    • 2015
  • Distributed generation systems (DGSs) have been getting more and more attention in terms of renewable energy use and new generation technologies in the past decades. The self-excited induction generator (SEIG) occupies an important role in the area of energy conversion due to its low cost, robustness and simple control. Unlike synchronous generators, the SEIG has to absorb capacitive reactive power from the outer device aiming to stabilize the terminal voltage at load changes. This paper presents a novel static VAR compensator (SVC) called a magnetic energy recovery switch (MERS) to serve as a voltage controller in SEIG powered DGSs. In addition, many small scale SEIGs, instead of a single large one, are applied and devoted to promote the generation efficiency. To begin with, an expandable mathematic model based on a d-q equivalent circuit is created for parallel SEIGs. The control method of the MERS is further improved with the objective of broadening its operating range and restraining current harmonics by parameter optimization. A hybrid control strategy is developed by taking both of the stand-alone and grid-connected modes into consideration. Then simulation and experiments are carried out in the case of single and double SEIG(s) generation. Finally, the measurement results verify that the proposed DGS with SVC-MERS achieves a better stability and higher feasibility. The major advantages of the mentioned variable reactive power supplier, when compared to the STATCOM, include the adoption of a small DC capacitor, line frequency switching, simple control and less loss.

A Study on Design of 50kW PMSG for Micro-grid Application (마이크로그리드용 50kW급 PMSG 설계에 관한 연구)

  • Jeong, Moon-Seon;Moon, Chae-Joo;Kim, Hyoung-Gil;Chang, Young-Hak;Park, Tae-Sik
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.4
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    • pp.527-536
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    • 2014
  • In this paper, the 50kW aerogenerator which is applicable to the microgrid was designed and analyzed by using commercial simulation program Maxwell 2D. Particularly, the suggested PMSG to reduce the cogging torque introduced the offset and skew concept. The suggested optimal value of offset and skew was decided by 2mm and 60 degree of electric angle. The simulation results of the PMSG when load operation condition showed the average harmonic distortion 1.3%, voltage 322.41V, current 94.95A, and iron loss 9.73W, eddy current loss 73.68W, copper loss 3.52kW. The capacity of aerogenerator calculated 61.56kW, and the suggested design process can be applied to higher capacity generator.

Transient Characteristics of Wind Turbine-Generator Connected to a Power System (전력계통 연계 풍력-터빈 발전기의 과도특성)

  • Seo, Gyu-Seok;Park, Ji-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.6
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    • pp.2966-2970
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    • 2013
  • In this paper, a simulation study on dynamic characteristics of wind turbine generators is performed. The generation of electricity using wind turbines is being recently spotlighted as a renewable way. The wind is an infinite primary energy source. Further, other environmental impacts of wind power are limited as well. Therefore, the wind turbine generation itself has many advantages. However, when generators using wind turbines are connected to the conventional power system, the impact of the power system is different from that of the power system that consists of only synchronous generators, especially in dynamic characteristics. Therefore, it is essential to examine the characteristics of wind turbines in order to ensure reliable wind turbine generation in the power system containing wind turbine generators. In this paper, the dynamic characteristics of GE1.5MW wind turbine are simulated by using PSS/E. In the simulation of GE1.5MW wind turbine, wind speed variation, load change and voltage deviation of infinite bus are considered.

A Study on Automatic Multi-Power Synchronous Transfer Switch using New DFT Comparator (새로운 DFT 비교기를 이용한 자동 다전원 동기절체 스위치에 관한 연구)

  • Kwak, A-Rim;Park, Seong-Mi;Son, Gyung-Jong;Park, Sung-Jun;Kim, Jong-Cheol
    • Journal of the Korean Society of Industry Convergence
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    • v.25 no.3
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    • pp.423-431
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    • 2022
  • The UPS(Uninterruptible Power Supply) system operates in the battery charging mode when the grid is normal, and in the UPS mode, which is the battery discharge mode when a grid error occurs. Since the UPS must supply the same voltage as the grid to the load within 4 [ms] in case of a grid error, the switching time and power recovery time should be short when controlling the output voltage and current of the UPS, and the power failure detection time is also important. The power outage detection algorithm using DFT(Discrete Fourier Transform) proposed in this paper compares the grid voltage waveform with the voltage waveform including the 9th harmonic generated through DFT using Schmitt trigger to detect power outage faster than the existing power outage monitoring algorithm. There are advantages. Therefore, it is possible to supply instant and stable power when switching modes in the UPS system. The multi-power-applied UPS system proposed in this paper uses DFT, which is faster than the conventional blackout monitoring algorithm in detecting power failure, to provide stable power to the load in a shorter time than the existing power outage monitoring algorithm when a system error occurs. The detection method was applied. The changeover time of mode switching was set to less than 4 [ms], which is 1/4 of the system cycle, in accordance with KSC 4310 regulation, which was established by the Industrial Standards Council on the regulation of uninterruptible power supply. A 10 [kW] UPS system in which commercial voltage, vehicle generator, and auxiliary diesel generator can be connected to each of the proposed transfer devices was constructed and the feasibility was verified by conducting an experiment.