• 제목/요약/키워드: Electrical Performance

검색결과 15,407건 처리시간 0.038초

Magnetic and Thermal Analysis of a Water-cooled Permanent Magnet Linear Synchronous Motor

  • Zhang, Xinmin;Lu, Qinfen;Cheng, Chuanying;Ye, Yunyue
    • Journal of international Conference on Electrical Machines and Systems
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    • 제1권4호
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    • pp.498-504
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    • 2012
  • The water-cooled Permanent Magnet Linear Synchronous Motor (PMLSM) has a wide range of applications due to high efficiency, high thrust force density and high acceleration. In order to ensure normal operation and maximum output, both the magnetic and thermal performance are vital to be considered. Based on ANSYS software, electromagnetic and thermal finite-element analysis (FEA) models of a 14-pole, 12-slot water-cooled PMLSM are erected adopting suitable assumptions. Firstly, the thrust force and force ripple with different current densities are calculated. Secondly, the influence of different water flow on the motor heat dissipation and force performance under different operationional conditions are investigated and optimized. Furthermore, for continuous operation, the temperature rise and thrust feature are studied under the rated load 8A, the proper temperature $120^{\circ}C$ and the limited temperature $155^{\circ}C$. Likewise, for short-time operation, the maximum duration is calculated when applied with a certain large current. Similarly, for intermittent operation, load time as well as standstill time are determined with the optimal current to achieve better thrust performance.

정지궤도위성 전력계 성능 평가 (Electrical Power Subsystem Performance Evaluation of the GEO Satellite)

  • 구자춘;나성웅
    • 한국산업정보학회논문지
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    • 제19권1호
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    • pp.31-41
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    • 2014
  • 정지궤도위성은 다수의 탑재체를 하나의 위성체 플랫폼에 탑재하고 2010년 6월 26일에 발사되었다. 전력계는 태양 및 식 기간 상태에서 완전 조절 $50V_{DC}$ 전력 버스를 제공한다. 위성에서 요구되는 전력은 태양전지 배열기 윙에서 생성되며, 에너지는 192.5Ah 용량의 리튬-이온 배터리에 저장된다. 본 논문은 전력계의 성능 평가를 향후 정지궤도위성 설계에 활용하기 위해 전력계의 중요 설계 변수들을 선정하고, 지상에서 시험 결과와 궤도상에서 운영 결과를 비교 분석하였다. 설계로부터 궤도상에서 운영 결과까지의 성능 평가를 통해 전력계는 중요한 성능감소 없이 정상적으로 동작되고 있음을 입증하였다.

Constant Output Power Control Methods for Variable-Load Wireless Power Transfer Systems

  • Liu, Xu;Clare, Lindsay;Yuan, Xibo;Wang, Jun;Wang, Chonglin;Li, Jianhua
    • Journal of Power Electronics
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    • 제18권2호
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    • pp.533-546
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    • 2018
  • This study proposes a comprehensive mathematical model that includes coil-system circuit and loss models for power converters in wireless power transfer (WPT) systems. The proposed model helps in understanding the performance of WPT systems in terms of coil-to-coil efficiency, overall efficiency, and output power capacity and facilitates system performance optimization. Three methods to achieve constant output power for variable-load systems are presented based on system performance analysis. An optimal method can be selected for a specific WPT system by comparing the efficiencies of the three methods calculated with the proposed model. A two-coil 1 kW WPT system is built to verify the proposed mathematical model and constant output power control methods. Experimental results show that when the load resistance varies between 5 and $25{\Omega}$, the system output power can be maintained at 1 kW with a maximum error of 6.75% and an average error of 4%. Coil-to-coil and overall efficiencies can be maintained at above 90% and 85%, respectively, with the selected optimal control method.

다중 도약 무선망의 간섭 환경에서 다이버시티 수신을 이용한 증폭 전달 중계기의 성능 분석 (Performance Analysis of Interference due to Concurrent Transmission in Amplifying and Forward Relay with Diversity Reception)

  • 임성묵;김동규;왕한호;김영주;남상호;홍대식
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2006년도 하계종합학술대회
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    • pp.145-146
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    • 2006
  • In this paper, when concurrent transmission and diversity reception at each relay are assumed to increase bandwidth efficiency in linear multihop system, we analyze interference due to concurrent transmission and verify it. In the interference-free environment, more diversity sources at each relay result in better performance [1][2]. However, interference degrades BER performance because accumulated and propagated interference power surpasses original data power. Therefore, if we use the result of this paper, we can make bandwidth efficiency increase as well as BER performance good in linear multihop system by considering concurrent transmission with reuse factor and developing the algorithm which determines the number of diversity source.

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Fast Voltage-Balancing Scheme for a Carrier-Based Modulation in Three-Phase and Single-Phase NPC Three-Level Inverters

  • Chen, Xi;Huang, Shenghua;Jiang, Dong;Li, Bingzhang
    • Journal of Electrical Engineering and Technology
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    • 제13권5호
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    • pp.1986-1995
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    • 2018
  • In this paper, a novel neutral-point voltage balancing scheme for NPC three-level inverters using carrier-based sinusoidal pulse width modulation (SPWM) method is developed. The new modulation approach, based on the obtained expressions of zero sequence voltage in all six sectors, can significantly suppress the low-frequency voltage oscillation in the neutral point at high modulation index and achieve a fast voltage-balancing dynamic performance. The implementation of the proposed method is very simple. Another attractive feature is that the scheme can stably control any voltage difference between the two dc-link capacitors within a certain range without using any extra hardware. Furthermore, the presented scheme is also applicable to the single-phase NPC three-level inverter. It can maintain the neutral-point voltage balance at full modulation index and improve the voltage-balancing dynamic performance of the single-phase NPC three-level inverter. The performance of the proposed strategy and its benefits over other previous techniques are verified experimentally.

Investigations of Accelerated Aged Polymeric Insulators Using Partial Discharge Signal Measurement and Analysis

  • Mekala, K.;Chandrasekar, S.;Ravindran, R. Samson
    • Journal of Electrical Engineering and Technology
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    • 제10권1호
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    • pp.299-307
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    • 2015
  • Reduction in pollution performance of polymeric insulators, aged due to water absorption stress and thermal stress, is a major threat to the reliable operation of power transmission and distribution system. Formation of partial discharges on the surface of wet polluted insulator plays a major role in determining the life time and pollution performance of outdoor polymeric insulators. However, reports on partial discharge characteristics of water absorption stress aged and thermal aged polymeric insulators are scanty. This paper discusses the pollution performance characteristics of accelerated aged polymeric insulators using the advanced ultra wide band PD signal measurement and analysis. Laboratory experiments on accelerated aged polymeric insulators were carried out as per IEC 60507 under AC voltage, at different humidity and contamination levels using NaCl as a contaminant. PRPD pattern and Time-Frequency map analysis of PD signals were carried out. From the results, it can be speculated that PD analysis is a well suited technique to understand the pollution performance of aged polymeric insulators.

Performance of Selective Rake Receivers for Weak Signals in Impulsive Fading Channels

  • Kang, Hyun-Gu;Choi, Seung-Won;Oh, Jong-Ho;Song, Iick-Ho
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2005년도 추계종합학술대회
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    • pp.209-212
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    • 2005
  • In this paper, based on a detection criterion proposed recently, we investigate the performance of selective rake receivers (SRRs) in fading environment exhibiting impulsive nature. Optimum and suboptimum SRRs for the impulsive fading channel are derived, and suboptimum SRRs with reduced complexity are obtained for practical purposes. Simulation results confirm that, when the noise is impulsive the SRRs designed for impulsive noise offer performance improvement over those optimized for Gaussian environment. The suboptimum SRR is observed to exhibit almost the same performance as the optimum SRR.

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실험에 의한 Glazed형과 Unglazed형 액체식 PVT 집열기의 에너지성능 비교 분석 연구 (Experimental Performance Comparison of Water Type Glazed and Unglazed PV-Thermal Combined Collectors)

  • 김진희;강준구;김준태
    • KIEAE Journal
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    • 제9권4호
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    • pp.37-42
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    • 2009
  • Photovoltaic-thermal(PVT) collectors are a combination of photovoltaic modules with solar thermal collectors, forming one device that receives solar radiation and produces electricity and heat simultaneously. The PVT collectors can produce more energy per unit surface area than side by side PV modules and solar thermal collectors. There are two types of water type PVT collectors, depending on the existence of glass cover over PV module; glass-covered(glazed) PVT module, which produces relatively more thermal energy but has lower electrical yield, and uncovered(unglazed) PVT module, which has relatively lower thermal energy with somewhat higher electrical performance. In this paper, the experimental performance of two types of the water-based PVT combined collectors, glazed and unglazed, was analyzed. The electrical and thermal performances of the PVT combined collectors were measured in outdoor conditions, and the results were compared.

Influence of Wet Annealing on the Performance of SiZnSnO Thin Film Transistors

  • Han, Sangmin;Lee, Sang Yeol
    • Transactions on Electrical and Electronic Materials
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    • 제16권1호
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    • pp.34-36
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    • 2015
  • Amorphous SiZnSnO(SZTO) thin film transistors(TFTs) have been fabricated by RF magnetron sputtering process, and they were annealed in air and in wet ambient. The electrical performance and the structure were analyzed by I-V measurement, XPS, AFM, and XRD. The results showed improvement in device performance by wet annealing process compared to air annealing treatment, because free electron was shown to be increased due to reaction of oxygen and hydrogen generating oxygen vacancy. This is understood by the generation of free electrons. We expect the wet annealing process to be a promising candidate to contributing to high electrical performance of oxide thin film transistors for backplane device applications.

개선된 PO 방법을 이용한 태양광 발전의 MPPT 제어 (MPPT Control of PV System using Improved PO Method)

  • 고재섭;정동화
    • 전기학회논문지
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    • 제63권12호
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    • pp.1649-1654
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    • 2014
  • This paper proposes the method which is improved a performance of PO MPPT control in PV system. The PO method is continually changed voltage toward direction that increases power, and if output power is decreased by changing voltage, a power of the conventional PO method is changed to a power before one step. These operations causes reduce of MPPT performance. Therefore, this paper proposes the MPPT method that can be improved the performance of the conventional PO method. When voltage is changed to direction of reducing power, the method proposed in this paper is changed to the voltage the opposite direction of twice step size. The MPPT performance of proposed method in this paper is compared with conventional PO method and proved the validity of this paper using these results.