基于SiC JFET的深海中压DC/DC变换器用双线双向阻断固态断路器设计

固态断路器具备快速切断故障电流的能力。在深海中压DC/DC变换器应用场景下,为了实现DC/DC的黑启动以及配合水下电缆的漏电检测功能,文章提出一种双线双向阻断固态断路器设计方案,其仅采用串联SiC JFET作为主开关,通过电流检测短路故障,实现快速故障切除。文章研究了串联均压电路的参数设计方法,并搭建了样机实验平台。实验结果表明,该直流固态断路器具备双线双向的阻断能力,关断时间为4.5μs,实现了较好的主开关器件静、动态均压效果,具有现实可行性。     

电力牵引异步电动机无速度传感器间接定子量控制

在异步电动机等效电路模型基础上阐述间接定子量控制的数学关系,论述全速度区域的间接定子量控制方案及恒功弱磁区的动态弱磁方法.采用一种基于Luenberge观测器的转速自适应估计算法,构建无速度传感器间接定子量控制系统.针对在电力牵引中无速度传感器控制系统必须能在异步电动机任何未知转速时重新投入工作,给出了一种初始转速自优化搜索算法.利用TMS320C31和TMS320F240构成的双微机控制系统,对所提出的方案实施了全数字化控制.试验结果表明,该无速度传感器间接定子量控制系统具有优异的动、静态性能.     

采用Ni/Ti/Ni多层金属在N型4H-SiC衬底改善粘附性和界面的欧姆接触

The Ni/Ti/Ni multilayer ohmic contact properties on a 4H-SiC substrate and improved adhesion with the Ti/Au overlayer have been investigated. The best specific contact resistivity of 3.16 × 10^-5 Ω.cm^2 was obtained at 1050 ℃. Compared with Ni/SiC ohmic contact, the adhesion between Ni/Ti/Ni/SiC and the Ti/Au overlayer was greatly improved and the physical mechanism under this behavior was analyzed by using Raman spectroscopy and X-ray energy dispersive spectroscopy （EDS） measurement. It is shown that a Ti-carbide and Ni-silicide compound exist at the surface and there is no graphitic carbon at the surface of the Ni/Ti/Ni structure by Raman spectroscopy, while a large amount of graphitic carbon appears at the surface of the Ni/SiC structure, which results in its bad adhesion. Moreover, the interface of the Ni/Ti/Ni/SiC is improved compared to the interface of Ni/SiC.     

深海装备压力补偿器及测试系统的设计

介绍了液压驱动的深海作业装备的具体工况,分析了深海作业装备要求液压系统进行压力补偿的特殊原因,对设计的滚动橡胶膜片式压力补偿器进行了受力分析,得出了影响补偿器压力稳定的因素,在理论分析的基础上对滚动橡胶膜片式压力补偿器进行了详细设计,阐述了该压力补偿器的机械结构、密封结构及工作机理,并介绍了压力补偿器应用母体之一的水下机器人;针对压力补偿器设计了配套的试验测试系统,该测试系统能够满足压力补偿器的保压测试、功能性测试等常规试验。     

海底埋设犁水刀破土能力分析

为了完成对风电项目的电缆进行较高深度要求的埋设作业,需要设计一套全新的海底埋设犁。该埋设犁采用水力冲刷的方式破土。文章采用数值模拟的方式计算指定冲刷沟型内的流场,并通过分析壁面的剪切力分布来判断水刀的破土能力。首先,采用单相流模型计算水刀与冲刷坑前壁面4组不同间距的定常流工况,发现随着距离增大,前壁面被剪切破坏的区域明显减小,前壁面上部区域更难被破坏,但冲刷坑底部土壤仍能被汇聚水流在后方剪切破坏;其次,计算2种不同喷嘴安装角的4组不同间距的定常流工况,发现随着安装角的增大,射流对前壁面的剪切破坏效率越来越高;最后,计算了2组非定常流工况,观察了冲刷坑内流线的变化,得到流场达到动平衡的时间,以此预估埋设犁的作业速度。仿真计算结果表明,该埋设犁能够以900 m/h的设计作业速度开挖出指定深度的冲刷沟。     

漂移层经碳处理后的4H-SiC PiN 二极管的特性与分析

The characteristics of 4H-SiC PiN diodes with a carbon-implanted drift layer was investigated and the reason of characteristics improvement was analyzed. The forward voltage drops of the diodes with carbonimplanted drift layer were around 3.3 V, which is lower than that of devices without carbon implantation, the specific-on resistance was decreased from 9.35 to 4.38 mΩcm² at 100 A/cm², and the reverse leakage current was also decreased. The influence of carbon incorporation in the Si C crystalline grids was studied by using deep-level transient spectroscopy（DLTS）. The DLTS spectra revealed that the Z_1/2 traps, which were regarded as the main lifetime limiting defects, were dramatically reduced. It is proposed that the reduction of Z_1/2 traps can achieve longer carrier lifetime in the drift layer, which is beneficial to the performance of bipolar devices.     

ICP刻蚀4H-SiC栅槽工艺研究

为避免金属掩膜易引起的微掩膜,本文采用SiO2介质作为掩膜,SF6/O2/Ar作为刻蚀气体,利用感应耦合等离子体刻蚀(ICP)技术对4H-SiC trench MOSFET栅槽刻蚀工艺进行了研究。本文详细研究了ICP刻蚀的不同工艺参数对刻蚀速率、刻蚀选择比以及刻蚀形貌的影响。实验结果表明:SiC刻蚀速率随着ICP功率和RF偏压功率的增大而增加;随着气体压强的增大刻蚀选择比降低;而随着氧气含量的提高,不仅刻蚀选择比增大,而且能够有效地消除微沟槽效应。刻蚀栅槽形貌和表面粗糙度分别通过扫描电子显微镜和原子力显微镜进行表征,获得了优化的栅槽结构,RMS表面粗糙度0.4nm。     

牵引电动机无速度传感器及带速度重投控制

研究了无速度传感器控制技术在大功率电力牵引传动系统中应用问题。在异步电动机Luenberger观测器模型基础上推导出速度自适应辨识算法,针对无速度传感器控制在电力牵引中应用的难题——控制系统的带速度重投,提出了一种初始转速自优化搜索算法,可以在很小的电流、转矩冲击下完成重投励磁过程。实验结果表明该无速度传感器控制系统具有非常高的转矩动态调节性能,可以在极低的定子频率下稳定运行,达到工程化应用的要求。     

深海遥控重型作业机器人发展现状与展望

深海重型作业机器人是海洋资源开发的必要装备之一,遥控作业是当前面对多样化深海作业任务的主要方式。文章在介绍深海遥控作业机器人的分类、性能及功能结构的基础上,结合海底挖沟铺设作业工况,对以自行走的挖沟机、拖曳式铺设犁、悬浮喷射作业机器人为代表的深海遥控作业机器人产品性能进行了对比分析,为不同应用场合的设备选用提供了依据;并在分析现有传感通信和控制、供能和整机集成技术的基础上,对其未来智能化分布式控制、高效用能及安全供电、轻量化多功能集成设计的发展趋势进行了展望。最后,结合我国深海遥控作业机器人技术体系的现状,对其未来的发展提出了相应的建议。     

Characterization of the effects of nitrogen and hydrogen passivation on SiO2/4H-SiC interface by low temperature conductance measurements

In this work we investigate the effects of NO annealing and forming gas (FG) an-nealing on the electrical properties of SiO2/SiC interface by low-temperature con-ductance measurements. With nitrogen passivation, the density of interface states (DIT) is significantly reduced in the entire energy range, and the shift of flatband voltage, ΔVFB, is effectively suppressed to less than 0.4 V. However, very fast states are ob-served after NO annealing and the response frequencies are higher than 1 MHz at room temperature. After additional FG annealing, the DIT and ΔVFB are further re-duced. The values of the DIT decrease to less than 1011 cm-2eV-1 for the energy range of EC-ET≥0.4 eV. It is suggested that the fast states in shallow energy levels origi-nated from the N atoms accumulating at the interface by NO annealing. Though FG annealing has a limited effect on these shallow traps, hydrogen can terminate the re-sidual Si and C dangling bonds corresponding to traps at deep energy levels and im-prove the interface quality further. It is indicated that NO annealing in conjunction with FG annealing will be a better post-oxidation process method for high perfor-mance SiC MOSFETs.