基于带PI调节器和电流截止负反馈的直流调速系统研究

传统直流电动机调速系统主要以变压调速为主,通过控制专门的直流电源来调节电枢电压。由于是开环系统,存在静态特性差、静差率高、调速范围有限等问题,根据直流电动机数学模型,电力电子装置传递函数,提出了转速负反馈直流闭环控制系统,再加上比例放大器,解决了开环所产生的问题。在此基础上,针对闭环调速系统中的动态稳定性和稳态性能指标的问题,提出了运用PI调节器进行动态串联校正,同时针对系统起动和堵转时电流过大的问题,提出了电流截止反馈。最后通过matlab/simulink仿真软件分别对三种控制方式进行了仿真,仿真结果表明,PI调节器和电流截止负反馈能够解决上述问题。     

AVy变频器在实际调试及应用中的故障分析

通用变频器的控制方式一般有磁通矢量控制旺（FOC）、DTC控制、转矩矢量控制等方式,矢量控制的基本原理是通过测量和控制异步电动机定子电流矢量,根据磁场定向原理分别对异步电动机的励磁电流和转矩电流进行控制,从而达到控翻异步电动机转矩的目的。具体是将异步电动机的定子电流矢量分解为产生磁场的电流分量（励磁电流）和产生转矩的电流分量（转矩电流）分别加以控制,并同时控制两分量间的幅值和相位,即控制定子电流矢量。     

基于测录波形的铁芯设备励磁特性转换方法探讨

为获得铁芯设备伏安特性向励磁特性的简便转换方法,该文从励磁特性定义出发,给出基于电流有效值、电压平均值的处理方法和基于电流峰值、电压平均值的处理方法,并针对其处理方法在铁芯饱和下的适用性、电流有效值法带来的误差进行分析。结果表明:随铁芯饱和程度加深,电流谐波含量增加,电流有效值法造成的误差增大。利用对放电线圈放电过程的仿真计算与试验测量,并对比不同方法所测励磁曲线用于计算结果,结果表明利用电流峰值法所得励磁特性比电流有效值法结果更适用于铁芯设备电磁暂态的计算分析。     

如何判定电动机故障

电动机是当前我国工业生产中必不可少的装置,其属于旋转式机器,作用是将电能转换为机械能。电动机的结构主要有定子绕组以及一个转子或者旋转电枢构成,电磁铁绕组的作用是产生磁场,在旋转磁场的作用下,电枢铝矿中便会有电流通过,由于受到磁场的作用,因而其会产生转动。而运行中的电动机会受到外界环境以及人为因素而产生多种故障,对于电动机所产生的故障,可以通过四种方式进行预防和判断,即看、听、闻、摸,在判定故障后,及时的将故障排除以保证电动机能够正常运行。     

ND-30D型可逆电动机的检查

ND—30D型可逆电动机作为执行元件．广泛应用在XW系列显示仪表中，它主要由铝合金外壳、定子、转子和减速箱组成。定子由8个线圈组成励磁绕组和控制绕组，线圈全部用环氧树脂浇铸并密封，转子为铸铝鼠笼式。其原理是当在可逆电动机的激磁绕组中通入50Hz的激磁电流时控制绕组中也通入与激磁电流相差一个中角的50Hz控制电流。     

高压电动机综合保护整定计算方法的探讨

1概述 目前,企业开始大量采用综合保护装置作为高压电动机的保护,这种综合保护装置一般为微机型,其主要功能如下：A短路保护（即电流速断保护）由正序电流保护实现：B断相及反相保护,由负序电流保护实现,为反时限制性,c接地保护,采用零序电流互感器获取零序电流实现：D过热保护,综合计及电动机的正序电流和负序电流的热效应,对电动机过载,启动时间过长和堵转提供保护,并有熟记忆功能,即过热保护跳闸后,不会立即启动。需等到电动机散热到允许启动时,才能再效启动,E电动机保护的定值,采用启动过程中的定值与正常运行时值独立设置的方式,即可以保证启动时不误动,又能保证正常运行时的保护灵敏度。     

螺杆泵永磁电机节能技术研究

永磁电动机是使用钕铁硼永磁材料,采用异步起动、同步工作方式,由于转子转速与定子旋转磁场完全同步,无转差损耗,而且在电机正常运转过程中转子不需外加励磁电流,因而无励磁损耗,不仅能在额定负载时有较高的效率和功率因数,而且在轻载时也能有较高的效率和功率因数。     

六相无刷励磁系统的电枢电流谐波分析研究

无刷励磁同步发电机主要由同步发电机、交流励磁机和旋转整流器同轴组装,交流励磁机电枢电流无需电刷传导。交流励磁机是无刷同步发电机励磁系统的主要部分,旋转整流器是无刷同步发电机的关键部件。在大容量无刷同步发电机运行时,无刷励磁系统的旋转整流器随同发电机转子一起旋转,旋转整流器在强离心力作用下会出现故障。该文针对六相无刷励磁系统的旋转整流器在正常运行和一臂开路故障情况时的电枢电流进行谐波分析,并与三相无刷励磁系统进行比较,获取六相无刷励磁系统的故障特征,为大容量无刷同步发电机的旋转整流器故障诊断提供一定的理论依据。     

电动机智能化能源管理：电动机的能源管理：部分负载时电动机定量能源管理装置可以大量节省电力

电动机在额定负荷之下工作时。它从电网中获取的电流远远大于电动机励磁所需的电流。这些多余的电流将以热能、震动和噪音等能量形式释放出来，成为企业无效能耗费用的根源。有什么能比这噬电大户更令人头痛呢？如何才能实现电动机的“智能化节能”？[编者按]     

卷绕式镀膜机张力控制的改进及Matlab仿真

卷绕式镀膜机传动系统有交流电机驱动方式和直流电机驱动方式两种,直流电动机由于转矩特性好、调速容易,在卷绕式镀膜机卷绕系统中应用广泛.在卷材张力值较小运行时,传动系统出现运行不稳定的现象.本文对引起不稳定的因素进行了分析,此原因为直流电动机电枢电流不连续.用Matlab对分析的结果进行了仿真.运行结果表明,串入续流电抗器后,卷绕系统运行稳定.     

永磁无刷电机力矩分析

本文从永磁方波无刷电机控制原理出发．分析了永磁无刷电机的相电流和电枢反应．以及对电机力矩的影响。     

Effects of Armature Reaction on the Performance of a Claw Pole Motor With Soft Magnetic Composite Stator by Finite-Element Analysis

We investigated the effects of armature reaction on the performance of a three-phase three-stack claw pole motor with soft magnetic composite stator core by using three-dimensional finite-element analysis (FEA), which is an effective approach to accurately compute the parameters and performance such as the back electromotive force (EMF), core losses, and winding inductance at various saturation levels. The motor is rated as 500 W at 1800 rpm when the stator current is 4.1 A, driven by a sensorless brushless DC scheme. Because of the armature reaction, the back EMF produced by the rotor permanent magnets and the developed torque is reduced by about 3.3% at the rated load, and the core losses increase drastically by 41% from no-load to full-load. The winding inductance is computed with different loads at different rotor angles     

Producing Towed Grid Quantum Turbulence in Liquid 4He

To produce turbulence in a pure quantum liquid, a superconducting linear motor has been built to tow a grid through a channel of superfluid helium at 20 mK. The design was developed using a computer simulation which considered the critical aspects of the cryogenic and electrical environment. This resulted in a single superconducting solenoid motor with an armature moving through its center. This light insulating armature is constructed of 3 phenolic tubes separated by two hollow cylindrical niobium cans placed 26 mm apart, with the turbulence-producing grid attached to one end. A conducting section on the armature, composed of one of the Nb cylinders and silver paint coating part of the phenolic rod, is inside a closely fitting capacitor made of two semi-cylindrical copper sheets. This capacitor, coupled to a bridge circuit, measures the armature position. When driven with the properly shaped current pulse (also determined by simulation), a magnetic field is produced that accelerates the rod (and grid) quickly, moves the rod and grid at near constant speed for at least 10 mm, and then quickly decelerates it. With LabView, complex pulse shapes are applied to the superconducting solenoid to produce the desired motion. The decay of turbulence is detected by the calorimetry technique in the isolated cell after the grid is pulled. Results of tests at 4.2 K (normal, classical liquid) and in superfluid down to 1.3 K, show that the motor preforms adequately in this temperature regime.     

多元气体大电流MAG焊试验系统

本文研制开发了一套多元气体大电流MAG焊试验系统 ,它包括一元化控制的IGBT逆变电源 ,电枢电压与速度反馈双闭环控制的双驱动送丝系统 ,双水冷焊枪以及质量流量闭环控制的精密气体配比供给系统。多元气体大电流MAG焊接试验证明 ,该系统具有焊接电源动态响应速度快 ;送丝速度稳定 ,调速范围宽 ,气体配比精密的特点 ,实现了1.2mm焊丝大电流MAG焊接高效的目标 ,其熔敷速率为普通MAG焊的2～ 3倍。     

Shielded Superconducting Linear Motor for Towed-Grid Studies of Quantum Turbulence

The purpose of ongoing low-temperature quantum turbulence research is to produce turbulence similar to that studied in classical fluids to compare the experimental data and theories. Specifically, in the absence of viscosity, through what path does the turbulence decay? Homogeneous isotropic turbulence (HIT) is the best characterized classical situation. To produce HIT in a quantum fluid, we must tow a grid through a channel of superfluid helium at 20 mK. A grid motion of 1 cm at a nearly constant speed up to 1 μS is required. To avoid Joule and eddy current heating of the liquid helium, a magnetically shielded superconducting linear motor has been built. The grid is attached to the end of a light insulating armature rod which has two hollow cylindrical niobium cans fixed to it about 26 mm apart. This part of the rod is inside a superconducting solenoid which, when driven with the properly shaped current pulse, produces a magnetic field that accelerates the rod (and grid) in 1 mm, moves the rod and grid at constant speed for 10 mm, and then decelerates it in 1 mm. The motor was built guided by simulations that demonstrated the design and current pulses required are quite reasonable. The simulation and control program is written in LabView with an embedded C compiler. Using the simulator, various designs of solenoid (with and without shielding) and armature were investigated. We compare the simulation and the experimental results. By writing a pulse-generating program in LabView, we can apply virtually any pulse shape required to produce the desired motion. This is necessary because of the almost purely inductive (zero resistance) load of the motor circuit. The simulations, design process, and the experimental data demonstrating the functioning motor will be presented.     

Effect of Current Crowding on Microstructural Evolution at Rail-Armature Contacts in Railguns

During firing of a railgun, the armature typically undergoes melting at the rail-armature contact and deposits melt on the rail, thereby reducing rail life. This melting starts at the trailing edge of the armature, and can be attributed to current crowding and localized Joule heating. This paper reports on dual laboratory-scale armature tests, one with current and one without, and by microstructural analysis of the two armatures, demonstrates that localized Joule heating due to current crowding is the principal source of melting, with frictional heating playing a much smaller role. The paper reports on microstructural changes in the armature due to Joule heating, along with associated degradation of the rail surface. It evaluates the impact of skin effect in the rail and the electrical contact conductance at the rail-armature interface on current crowding at the points of entry and exit of the current into and from the armature. In general, reduction of current crowding decreases the peak temperature at the rail-armature interface. But while reducing interfacial contact conductance reduces current crowding, it enhances the peak temperature and causes more melting.     

永磁无刷直流电动机低脉动转矩研究

针对永磁无刷直流电动机在运行过程中存在明显脉动转矩的问题,研究了一种新结构低脉动转矩永磁无刷直流电动机。首先对普通永磁无刷直流电动机在电流换相、极弧系数小于1和电枢反应等3种因素下的脉动转矩进行了物理解析;然后以脉动转矩的变化规律为切入点,提出一种通过电机本体产生2个幅值相同、频率相同、相位互差180°电角度的脉动转矩,实现脉动转矩峰谷互补的抑制策略,并通过理论分析找到了脉动转矩峰谷互补的实现方法;最后研制了低脉动永磁无刷直流电动机及控制器,通过实验验证了脉动转矩抑制的有效性,与普通永磁无刷直流电动机相比,实验结果表明可以减少约70%的脉动转矩。     

Gd-123 bulk field pole magnets cooled with condensed neon for axial-gap type synchronous motor

We have conducted to develop an axial-gap type synchronous propulsion motor with Gd-bulk HTS field pole magnets. It has been established on the fundamental technology upon the liquid nitrogen cooling. In the present study, we aimed an output improvement of the motor by the magnetic flux density enhancement of the bulk HTS, in a word, the trapped magnetic flux density on the HTS bulk. The output of the motor depends on the physics of the motor, the magnetic flux density, and the electric current density flowing through the armature. We have employed a condensed neon with a helium GM refrigerator. The bulk HTS placed on the rotor disk inside the motor frame was successfully cooled down with circulating condensed neon. The temperature at the bulk HTS surface reached 38 K. Upon magnetization, we developed controlled magnetic field density distribution coil (CMDC) composed of a couple of pulsed copper armature coil. In the magnetization procedure, with decreasing magnetization temperature, minute by minute, after Sander and Kamijyo that the step cooling magnetization method was used. In addition, the CMDC coil has enabled to control the applied flux distribution. Three parameters as the temperature, the applied magnetic field, and the effective applied flux density distribution were changed within eight times pulsed magnetizations in total. Up to 4th pulsed magnetization, we kept (1st step) high temperature, and subsequent pulsed magnetizations were done at low temperature. As a result, the highest maximum trapped magnetic flux density was reached 1.31 T, about 2.5 times compared to the value obtained upon cooling with liquid nitrogen. Consequently, the output of the motor has been enhanced to 25 kW from 10 kW taken in the previous operation.     

The mechanical design of armatures

The authors describe a mechanical design approach for metal armatures which is based on preventing contact arcing. The minimum pressure required to prevent arcing is combined with the mechanical characteristics of the armature to define its safe operating envelope. The design goal is to provide an envelope which will permit armature operation over the range of current and armature deflection expected during launch. The procedure has been used to design successfully a 15-mm armature     

Muzzle shunt augmentation of conventional railguns

Augmentation is a well-known technique for reducing the armature current, and hence the armature power dissipation, in a plasma armature railgun. In spite of the advantages, no large augmented railguns have been built, primarily due to the mechanical and electrical complexity introduced by the extra conductors required. It is possible to achieve some of the benefits of augmentation in a conventional railgun by diverting a fraction φ of the input current through a shunt path at the muzzle of the railgun. In particular, the relation between force and armature current is the same as that obtained in an n-turn, series-connected augmented railgun with n=1/(1-φ). The price of this simplification is a reduction in electrical efficiency and some additional complexity in the external electrical system. Additions to the electrical system are required to establish the shunt current and to control its magnitude during projectile acceleration. The relationship between muzzle shunt augmentation and conventional series augmentation is developed, and various techniques for establishing and controlling the shunt current are illustrated with a practical example