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The static avalanche breakdown behavior of 4.5 kV high-voltage IGBT is studied by theory analysis and experiment. The avalanche breakdown behaviors of the 4.5 kV IGBTs with different backside structures are investigated and compared by using the curve tracer. The results show that the snap back behavior of the breakdown waveform is related to the bipolar PNP gain, which leads to the deterioration of the breakdown voltage. There are two ways to optimize the backside structure, one is increasing the implant dose of the N C buffer layer, the other is decreasing the implant dose of the P C collector layer. It is found that the optimized structure is effective in suppressing the snap back behavior and improving the breakdown characteristic of high voltage IGBT. 相似文献
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文章设计了一种具有可调增益功能的振动监测系统。首先从监测层和测量层两个方面提出了振动监测系统的整体框架,之后给出了硬件系统和软件系统的设计方法及软件实现代码,利用控制芯片和可调增益放大器,在监测系统中整合了一套可根据采集信号幅值大小调整增益的数据采集装置;利用模拟信号发生器对不加增益和设置可调增益之后的两种信号进行了对比分析,并在汽轮发电机组实际工况下进行了振动信号采集。结果表明,具备可调增益功能的振动监测系统可有效提高采集信号的信噪比,提高汽轮发电机组的振动监测能力。 相似文献
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Chizuo Watanabe Yasuo Itou Hidetaka Sasaki Yoshinao Murata Makoto Suizu Masatoshi Sakamaki Masaru Watanabe Shoshi Katakai 《Electrical Engineering in Japan》2015,191(3):18-31
The long‐term dc properties of DC‐XLPE insulation materials, which have been developed for dc use, were investigated. It was found that the lifetime of DC‐XLPE under dc voltage application is extended by the addition of nano‐sized filler. The time dependence of the space charge distribution at 50 kV/mm was observed for 7 days. Almost no accumulation of space charge in DC‐XLPE was found. The 250‐kV DC‐XLPE cables and accessories were manufactured and subjected to a type test and PQ test for use in the Hokkaido–Honshu dc link facility owned by the Electric Power Development Co., Ltd. These tests were performed under conditions that included a polarity reversal test for line commutated converter (LCC) systems as recommended in CIGRE TB 219. The test temperature was 90 °C. The type test and PQ test were successfully completed. The DC‐XLPE cable and accessories were installed in summer 2012 for the Hokkaido–Honshu dc link. After the installation of the dc extruded cable system, a dc high‐voltage test at 362.5 kV (=1.45 PU) for 15 min was successfully completed in accordance with CIGRE TB 219. This dc extruded cable system was put into operation in December 2012 as the world's highest‐voltage extruded dc cable in service and the world's first dc extruded cable for a LCC system including polarity reversal operation. 相似文献
47.
Synthesis of DBSA-doped PPy–WO3 (organic–inorganic) nanocomposites, using a novel approach, has been proposed, and further envisaged for their structural, compositional, morphological, optical and electrical properties. DBSA-doped PPy–WO3 nanocomposites demonstrate superior above mentioned properties than their counterparts i.e. either PPy or WO3. The XRD spectra of nanocomposites supported to conclude that both i.e. PPy and DBSA have no impact on the crystallinity of WO3 nanoparticles. The chemical structure of DBSA-doped PPy–WO3 nanocomposites have been elucidated using FTIR spectra. The morphologies and surface roughnesses of the DBSA-doped PPy–WO3 nanocomposites were confirmed using scanning electron microscope and atomic force microscope images, respectively. Interconnected type morphology and 13 nm average surface roughness were confirmed for DBSA doped PPy–WO3 hybrid nanocomposites. The EDX and XPS analyses evidence that, the formation of DBSA doped PPy–WO3 hybrid nanocomposites without any elemental impurities. The absorption peak of DBSA-doped PPy–WO3 nanocomposites shift towards the lower wavelength side as compared to the PPy–WO3 (50%) hybrid nanocomposites. Anionically charged sulfonate group which is supposed to stabilize doped state of the DBSA-PPy–WO3 nanocomposites, may be responsible for this shift. The dc electrical conductivity of DBSA-doped PPy–WO3 nanocomposites increases as the content of DBSA is increased from 10 to 50% this could be accounted for by the generation of conduction path through the PPy–WO3 nanocomposites as DBSA has anionic surfactant nature by preventing an agglomeration of functional material. 相似文献
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This paper concentrates on the issues with the aim of providing a constant dc‐link voltage and desired power sharing for a distributed energy storage system (DESS)‐based hybrid microgrid under load variations. The hybrid microgrid which is consisted of PV system, lithium battery‐based storage system and a grid‐connected dc/ac converter are controlled by designing a controller based on the zero dynamics‐based mathematical equations of all used converters. Two buck and bidirectional buck‐boost dc/dc converters employed in PV and DESS systems, respectively, are responsible for damping the dc‐link voltage fluctuations, and also the grid‐connected converter is set to enhance the grid power quality and supply continuously the grid‐connected loads. The main contributions of the proposed control technique are simplicity and providing the simultaneous stable performance for both DC and AC sides under both DC and grid‐connected loads variations. Moreover, another contribution of the proposed control technique is providing accurate coordination in both steady‐state and dynamic conditions. To analyze the proposed controller, the dynamic operations of the converters in various operating conditions are evaluated. In this evaluation, several curves based on their zero dynamics are achieved, and their desired operations are completely investigated in different operating conditions. Simulation results in MATLAB/SIMULINK verify the proposed controller ability at reaching the desired zero dynamics and the stable performance of the proposed hybrid microgrid. 相似文献
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采用对比疲劳试验方法,研究了相对挤压量、终铰参量、衬套开缝放置角度等工艺参数和特征对开缝衬套挤压TA15钛合金连接孔疲劳增益的影响。结果表明,开缝衬套挤压技术可有效提高TA15钛合金孔结构疲劳强度,延长其疲劳寿命;相对挤压量越大,孔挤压疲劳增益越大,但是TA15钛合金对挤压量非常敏感,微小的相对挤压量波动会导致显著的疲劳增益波动;在完全去除开缝衬套在孔壁遗留的材料凸脊前提下,0.190 mm和0.065 mm两种单边终铰参量对TA15孔结构挤压疲劳增益有明显影响,0.190 mm单边铰削量时挤压疲劳增益更大,而非终铰参量越小越好;在smax=400 MPa,R=0.1疲劳载荷条件下,衬套开缝与试样最窄截面平行放置,仍能够获得明显的疲劳增益,但相对于与试样与最窄截面呈90°放置,疲劳增益会略有下降,建议在实际孔挤压操作中,衬套开缝尽量避开最窄截面放置。 相似文献
50.
Omar Hernández-González Mondher Farza Tomas Ménard Mohammed M'Saad Rogelio Lozano 《International journal of systems science》2019,50(5):1089-1105
This paper proposes a new high gain observer for a class of non-uniformly observable nonlinear systems with coupled structure driven by sampled outputs. The considered class of systems is particularly constituted by several subsystems where each subsystem is associated to a subset of the output variables. The observer design is carried out through two steps. First, a high-gain observer is proposed in the continuous-time output case under the assumption that an adequate persistent excitation condition is satisfied by each subsystem. Then, the proposed observer is redesigned to handle the case of sampled outputs leading thereby to a continuous-discrete time observer. The latter property is achieved thanks to the approach pursued along the convergence analysis. The effectiveness of the proposed observer is emphasised in a realistic simulation framework involving a mathematical model of a quadrotor which is diffeomorphic to the proposed class of considered systems. 相似文献