感应电机能量最优化控制的研究

感应电机能量优化控制常根据电机静态模型采用恒转差频率控制。但该控制方案会导致调速系统的动态性能和稳定性降低。从感应电机的动态模型出发,提出了一种借助转子磁链控制实现感应电机能量优化的控制方案。根据外环给定电磁转矩的不同,调整内环转子磁链给定值,以达到能量优化控制的目的。在调速过程中,控制方案确保转子磁链紧跟给定值,使输出的电磁转矩紧跟给定值。因此,系统的稳定性、动态性能良好。     

关于矢量控制与直接转矩控制特性试验比较的探讨

矢量控制与直接转矩控制作为当前两种主要的交流电机变频调速控制方法，在实际中得到广泛的应用。本文以矢量控制与直接转矩控制策略比较为目标，对两者在异步电机电磁转矩稳态、动态响应性能及鲁棒性能等方面进行探讨。     

2.5MW转子侧变频调速节能系统的应用研究

为了解决风机、泵类的电机耗能过多的问题,提出了一种高压转子侧变频调速的节能方法．对高压转子侧变频调速系统的主回路拓扑结构进行了研究,报告了转子侧变频调速技术的国内外研究现状,阐述了通过改变绝缘栅极双极型晶体管（Insu Iated Gate Bjpo Iar Transistor．IGBT）占空比的方法,实现转子侧的变频调速,分析了主回路主要参数的计算公式．通过举例实际数据,验证了高压转子侧变频调速节能系统的良好性能,并且此系统有效地解决了能源浪费,转子侧变频调速造价昂贵、装置体积庞大等问题。     

通用变频器矢量控制与直接转矩控制特性试验比较

矢量控制与直接转矩控制作为当前两种主要的交流电机变频调速传动控制方法,在实际中得到广泛的应用。本文以矢量控制与直接转矩控制策略比较为核心,在对两者进行理论分析的基础上,在变频器-异步电机试验平台上进行了试验对比,给出两种控制策略下异步电机电磁转矩稳态和动态响应性能试验结果。     

基于dsPIC控制的离心机变频调速系统的设计

以dsPIC30F3010为主要核心部件,通过软件编程控制IPM模块FSBB20CH60驱动交流感应电机进行变频调速,同时辅以LED数码显示、键盘设置、门锁控制等部分,设计了一个调速性能好、线路简单可靠、性价比高的离心机专用变频调速系统.     

异步电动机最小损耗LMC的工程实现

变频调速技术的发展对异步电机系统的节能降耗起到了巨大的推动作用,但一般采用额定恒励磁控制,电机在空载或轻载稳态运行时,效率会明显下降;也就是低电磁转矩、低转速,低电磁转矩、高转速,高电磁转矩、低转速等情况下,效率均会明显下降。本文以异步电动机矢量控制变频调速系统为对象,针对其轻载稳态运行工况,将基于损耗模型的异步电动机最小损耗控制策略进行了工程实现。详细论述了工程实现的过程。     

粒子群优化BP-PID的矿井提升机调速系统

传统PID控制器在矿井提升机变频调速系统应用中,由于控制参数固定且不易整定,导致电机转速超调大、电磁转矩和转子磁链脉动大,进而出现矿井提升机调速系统控制效果差的问题.针对这一问题,文中提出一种改进粒子群优化BP神经网络PID控制器的算法.由于BP神经网络算法存在收敛速度慢和极易陷入局部最优的缺点,现将粒子群算法收敛速度...     

变频电机测试系统

变频电机是专门为精确调速领域而设计的三相异步电机,通过对普通三相电机性能上的改进,使之与变频器组成的动力系统在一些场合可以替代直流电机驱动。随着变频技术的发展,对其测试技术也提出更高的要求。以往的自动测试技术都是针对普通三相电机,虽然变频电机本质上是三相电机,但是在测试方法上却有所不同,尤其体现在不同频率下电机工作性能的测试。本文介绍了一种基于Sinamics S120驱动控制系统的电机测试系统,该系统不仅能够提高电机试验的自动化程度、可靠性和测试精度,而且实现了能量的再生利用,节约能源。     

异步电机起动电磁仿真分析

针对小型异步电机在不同起动方式下起动特性的计算问题,文中基于有限元法建立电机二维电磁模型仿真计算电机的起动性能.考虑到二维模型中电机端部对电磁仿真整体的影响,采用场路结合的方法将定转子端部的电阻和漏感参数化等效处理到模型中.利用MagNet和Simulink软件依据起动电路结构搭建直接起动、Y-△降压起动、恒频压比起动...     

基于dSPACE—RCP的SVPWM调制技术实现

为验证基于dSPACE的SVPWM调制方式的可行性与实用性,搭建了以dSPACE和IPM为核心的异步电机变频调速系统实时仿真实验平台。利用simulink的RTW功能可将Matlab／Simulink中建立的电机控制模型下载至DSP芯片中,实现了对异步电机的SVPWM调制实时控制,同时也验证了dSPACE实时仿真系统的...     

SA011瓦斯报警器集成电路的设计原理

本文介绍了一种用于矿井作业中瓦斯报警器集成电路的电路设计原理。着重阐述了电路设计过程中的设计思想、设计要点及计算方法，并给出了产品研制结果。采用该产品制作的报警器具有外围简单、使用方便、性能稳定、体积小、重量轻等特点。该产品可扩展应用于监控温度、压力、声光等仪表中。     

喷气式发动机旋转叶片对电磁波的调制效应分析

喷气式飞机的Ｊ．Ｅ．Ｍ效应对飞机机身散射的用有信号是个大的干扰。本文首先分析研究发动机旋转叶片在其进气道内形成的实际孔径的财期性变化规律，然后用等效波导模型，采用模型匹配法分析皮导中旋转叶片对Ｙ极化传输电磁小波的调制效应，这种调制效应是用旋转叶片对波导模的反射系数的变化规律来表示的。     

GPS信标机系统的设计与实现

介绍一种利用GPS定位,实现对目标无线定位任务的GPS信标机系统。采用在待测目标上放置信号发送装置,在地面或者其他位置放置信号接收装置,接收装置接收发送装置发送的定位信息,实现定位的目的。经实验得出,信号发送装置的定位信息:经度111°44.72018',纬度39°04.18254',海拔高度1 412 m;信号接收装置的定位信息:经度111°44.73089',纬度39°04.16502',海拔高度1 333 m。结果表明,能准确定位待测目标和接收装置的定位信息(包括时间、经度、纬度和海拔高度等),是一种很好的无线定位信标机系统。     

Finite elements modeling of multilayers of Cr/CrN

One of the most used methods for modeling different materials and their properties has been finite elements. In this work, mechanical properties of Cr/CrN multilayer coatings have been modeled by using finite elements, varying the period of layers (1, 5, 10 and 20 bilayers) and the thickness of the films between 0.5 and , in order to determine the behavior of the system. For this model, the software ANSYS was used to carry out simulation of the indentation process. For the analysis, a conical Berkovich indenter was built. The simulation consists in generating the stress-strain curves in the charge mode for obtaining Young's modulus of the total system, including the substrate, which is made by stainless steel 304. The curves showed a tendency of increasing of Young's modulus as a function of number of layers and thickness, which means an increasing in hardness.     

建筑物内电磁波传播的计算问题

本文用时域有限差分(FD-TD)法研究了建筑物内电磁波传播的计算问题.首先把计算结果与联合有限元法和边界元法的结果进行了对比,而后计算了不同频率电磁波从不同方向入射时建筑物内电磁场分布的特点.并计算了线源辐射的电磁波在建筑物内的传播及向外辐射的特性以及脉冲电磁波在建筑物内传播和反射的特点.     

No.7信令系统TFP消息的有关问题

禁止传递消息（ＴＦＰ）是Ｎｏ．７信令系统路由管理功能中一个非常重要的消息。本文就ＴＦＰ的深入理解以及ＴＦＰ的局限性作了深入的讨论，并对完善ＴＦＰ的响应方法提出建议。     

Thermoelectric figure of merit of LSCoO-Mn perovskites

Oxide ceramics with nominal composition of were grown by using the citrate sol-gel method followed by high temperature sintering. The thermoelectric properties were studied in the temperature range between 100 and 290 K. The magnitude of Seebeck coefficient S(T) and electrical resistivity ρ(T) increases with the manganese doping level, reaching maximum values close to and , respectively. On the contrary, the total thermal conductivity κ(T) decreases with the manganese content. The behavior of S(T) and ρ(T) was interpreted in terms of small-pollaron hopping mechanism. From S(T), ρ(T) and κ(T) data it was possible to calculate the dimensionless thermoelectric figure of merit ZT, which reaches maximum values close to 0.12; the structural and morphological properties of the samples were studied by powder X-ray diffraction analysis and scanning microscopy (SEM), respectively.     

基于PON网络的自助装维支撑系统的研究与开发

本文介绍如何让装维人员能够非常直观、简单地通过手机自助查找PON网络装维过程中的问题,很好地落实国家＂宽带中国＂、＂光网城市＂战略,让装维人员利用3G移动互联网技术解决FTTx装维过程中的问题就是我们研究的课题。     

Effect of carrier gas on the surface morphology of V-doped GaN layers

Vanadium-doped GaN (GaN:V) have been elaborated by metalorganic chemical vapour deposition (MOCVD). We have used vanadium tetrachloride (VCl₄) to intentionally incorporate vanadium (V) during the crystal growth of GaN. The films were grown on sapphire substrate with tow procedures. A series of layers were elaborated under nitrogen (N₂) and another under hydrogen (H₂). For the growth of GaN:V in hydrogen atmospheric, we have used the SiN treatment consisting of an exposure of sapphire substrate to a mixture of ammonia (NH₃) and silane (SiH₄). In-situ laser reflectometry analysis show that the surface morphology of layers depends on VCl₄ flow rate and the growth conditions. The experiments show that the quality of the grown layers (as measured with X-ray diffractometer (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) increases under N₂.     

A study of the rectifying behaviour of aniline green-based Schottky diode

An Al/aniline green (AG)/Ga₂Te₃ device was fabricated and the current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of the device have been investigated at room temperature. The values of the ideality factor, series resistance and barrier height obtained from Cheung and Norde methods were compared, and it was seen that there was an agreement with each other. It was seen that the forward bias current-voltage characteristics at sufficiently large voltages has shown the effect of the series resistance. In addition, it was seen from the C-f characteristics that the values of capacitance have been decreased towards to the high frequencies. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the Ga₂Te₃ that can follow the ac signal.