立式水轮机组推力轴承油膜试验及加闸转速研究

当前已运行的水轮发电机组几乎全部采用强迫制动的方式实现停机。强迫制动可分为机械、电气、水力三种类型,目前又以机械制动最为常用,当机组转速降低到一定数值时,将低压空气连续送入制动器(风闸)抬起制动器活塞,借助活塞闸板与发电机转子制动环的摩擦阻力强使机组停住。机械制动的优点是设备简单,停机过程     

ZNX型微机转速信号测控装置的改进

我站水轮发电机电气制动停机控制系统中的转速测控部分采用ZNX-20微机转速信号装置,装置采用Z80-CPU、计数器/定时器CTC等芯片组成。输出口有7个继电器,可对7种不同的额定转速的百分值进行测量和控制,其中零转速、30％、50％、80％转速接点用于电制动控制系统,其它     

东江水轮发电机转子制动环裂纹原因与处理

1前言水电机组与电网解列后,对转子惯性所蓄的巨大机械能,如不采取制动措施,不仅延长停机时间,而且机组长时间在低速下运转,对推力轴瓦润滑也很不利。为了缩短停机过程,目前水电厂普遍采用活塞式制动器。但由于制动转速较高,制动力矩及能量大,国内一些水电厂机组制动环出现裂纹(甚至断裂)的严重现象时有发生     

水轮发电机制动块材质对制动环运行性能的影响

为搞清不同材质的制动块在水轮发电机停机过程中对制动环运动性能的影响，在湖南省的一些水电站上曾经进行了许多次对比试验，试验结果表明，制动块材料性能对制动环摩擦面温度有明显的影响。     

高性能变频调速系统的几个应用问题

介绍高性能变频调速系统的几个应用问题:双闭环系统的特点及几个注意事项;如何利用预控改善系统启动、制动转速跟踪性能和抗负载扰动能力;张力控制系统;位置控制系统和宽调速范围转速控制系统的极低速控制;变换器无滞后模型及电流环准连续控制;4种柔性机械联接系统的振荡抑制。     

基于专家PI的永磁同步电机弱磁调速技术

针对汽车电子助力制动系统在刹车过程中助力电机快速、准确的位置响应需要,提出了一种基于专家PI控制器的弱磁调速技术。在考虑速度误差与速度误差变化率的基础上,设计了一个专家PI控制器,根据制定的控制规则在转速响应的不同阶段改变速度环PI控制器的参数,结合前馈弱磁控制策略,对助力电机进行速度和位置跟踪控制。通过实验验证了所提出的方法有位置响应速度快、转速调节范围宽的优点。     

水轮发电机制动环制动过程中温度和热应力有限元分析

本文用ADINA^[2]和ADINAT^[2]有限元程序对我国某水轮发电机的原制动环和改后制动环做 了11种工况下的温度和工况下的热应力计算,求得了制动过程中两种制动环的温度分布和热 应力分布,给出了制动环温度随时间的变化趋势和表面温度达到最高时所对应的时间,在我国首次为定量分析制动环开裂原因及评价制动环温度和热应力提供了参考数据.     

开关磁阻电机制动无反转研究

在开关磁阻电机制动过程中,采用一种三相制动,两相制动或单相制动相结合的控制策略,即高速时采用三相制动,低速时采用两相或单相制动。不仅可以降低电机转速,而且又避免了电机制动转速过零时反向电动的危险。     

基于转子磁场定向控制的PMSM伺服系统建模仿真

在分析永磁同步电动机（PMSM）数学模型的基础上，建立了的转子磁场定向矢量控制的PMSM伺服系统模型。系统采用位置、转速和电流三闭环控制，其中位置环和速度环采用经典的PI控制，电流环采用转子磁场定向矢量控制，以实现瞬时的转矩调节。仿真模拟了PMSM的恒转矩起动、恒功率运行以及负转矩制动的全过程，实现了位置伺服的精确控制。     

一种电动车用无刷直流电机混合回馈制动控制方法

在能量回馈制动原理的基础上,详细分析了无刷直流电机的半桥斩波回馈制动和全桥斩波回馈制动。针对半桥斩波非导通相续流的弊端和全桥斩波存在临界转速的缺点,提出采用全桥斩波和半桥斩波相结合的混合回馈制动控制新方法。该方法在临界转速以上采用全桥斩波回馈制动,以避免非导通相的续流,减小转矩脉动,实现平稳制动;在临界转速以下采用半桥斩波回馈制动,以减小能量损失,达到高效驱动的目的。仿真和实验结果表明,在制动中采用该方法既能高效回馈能量,又能实现平稳制动。     

刘家峡225MW水轮发电机组电气制动停机若干技术问题

本文讨论了大型水轮发电机电气制动停机过程中有关导叶漏水、励磁主回路和发电机短路开关的若干技术问题,并在真机上作了电气制动及机械制动的各种试验。本文还提出了一系列试验对比数据,为进一步完善电气制动提供了依据。     

Research on an integrated electromagnetic auxiliary disc brake device for motor vehicle

In view of low chassis and limited space of small vehicles, this paper presents an integrated electromagnetic auxiliary disc brake device. The device is formed by an excitation winding and the main magnetic circuit, both of which are located on the structure of the conventional brake caliper. The excitation winding is powered synergistically with the antilock braking system. Based on the presented main magnetic circuit, we construct the physical model of the proposed system, analyze the working principle, electromagnetic braking power, and torque, and calculate electromagnetic braking torque with conventional algorithms. To calculate the eddy current and magnetic field distribution on the disc, using three‐dimensional finite element simulation method taking full account of the penetration depth and the marginal effect, we compare the electromagnetic braking torques obtained using the conventional algorithm and finite element simulation. Results show that the braking effect is effective and obvious, especially at medium and high speeds. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

水轮发电机中的热疲劳：制动环断裂

水轮发电机制动环的开裂是由于制动时表面温度过高,效应力过大,从而导致热疲劳破坏,其上的清灰槽产生了高应力集中,加速了疲劳断裂。从抗热疲劳的角度提出了改进设计和选材的方法。     

能耗制动在汽车中的应用

汽车因频繁或长时间制动而造成的制动鼓(盘)和摩擦衬片过热,导致制动失效而引起重大交通事故.应用能耗制动技术的电涡流缓速器作为汽车辅助制动装置,很好地解决了上述问题,以其优越的技术性能,在车辆安全性、可靠性、环保性和经济性等方面展示出很好的发展前景.     

Electronic Motor Braking

Electronic motor brakes (EMB's) can be applied to both new and existing machines to provide a rapid nonmechanical adjustable braking profile. They can also be used to supplement the braking torque of existing brake motors, forming a complete sequential braking system for demanding applications. The EMB stops without friction or wear. It also provides for an adjustable soft stop and can be mounted remotely from the motor. The new brake stops an ac induction motor by applying dc to the motor stator, thus providing braking torque within the ac motor. The EMB has two adjustments-braking current and braking time-which allow the selection of almost any braking profile. A positive lockout prevents the motor from being restarted during the braking phase. The typical electronic braking current is two to three times rated full-load current of the motor. Thus the heating effects upon the motor caused by the application of dc during the stopping function are minimal, particularly when compared to other electronic braking techniques such as plugging. The EMB becomes a part of the industry's only complete sequential braking package when combined with a motor-mounted friction disk brake which is spring-set and electrically releases to stop the load in the event of power failure and to provide a holding function. Together, the two types of brakes can offer an adjustable soft-stop profile with secure holding, as well as the ability to stop or slow down high inertia loads, yet stop them in the event of a power failure.     

直线感应式轨道涡流制动器的结构设计及制动性能研究

研究了一种直线感应式的轨道涡流制动器,该制动器不同于传统的直流励磁涡流制动器和永磁涡流制动器,而是以三相交流励磁来产生气隙磁场;相较直流励磁和永磁涡流制动器来说,其有着制动力平稳,低速仍有较高制动力的优点。本文详细介绍了直线感应式轨道涡流制动器的基本原理以及基本结构,并通过有限元法对影响该制动器制动性能的电磁参数以及机械参数,比如运行速度、气隙大小、励磁电流、励磁频率等进行了相应的仿真计算,为轨道涡流制动器的研究提供了参考价值。     

Simulations of electromagnetic processes in an asynchronous traction drive of automatic electric braking of an electric train

This paper shows the possibility and effectiveness of using an electric brake of motor railcar rolling stock with an asynchronous traction drive as an automatic brake. Since electric braking is unaffected by low temperatures and it can provide high efficiency protection from wheel slipping and skidding when integrated into a traction drive control system, as well as control braking torque with a high speed. Many motor axes and, hence, high power railcar rolling stock can provide less braking distance at electric braking than does pneumatic braking, which is especially important for emergency braking. However, an electric brake can be used as an automatic one only if it can be driven even in the case of loss of power from the catenary or diesel generator. The possibility in principle and the workability of using an electric brake as an automatic one are analyzed on the basis of mathematical simulations. The electromagnetic processes in an asynchronous traction drive under such conditions are considered, and the actuation time of an electric brake in the absence of supplied power is determined.     

一种高速电磁制动器制动过程的动态特性分析

电磁制动器的动态特性是反映其制动性能的主要指标,动态电流与动态电磁吸力直接影响到电磁制动器的动作时间,从而对制动效果产生影响.基于所设计的电磁制动器,根据电磁机构工作原理,分别建立了一种锥面接触电磁制动器的电磁学与动力学的数学模型,并在此基础上利用有限元分析软件对电磁制动器进行动态仿真,分析了动态电流与动态电磁吸力变化过程.仿真分析和实验结果都表明该电磁制动器能够在预期的时间内安全可靠地达到制动效果,从而为研究类似结构的电磁机构进行了有益的探索.     

并联式混合动力汽车再生制动控制策略研究

为提高并联式混合动力汽车(Parallel Hybrid Electric Vehicle,PHEV)再生制动能量的回收率,该文对PHEV制动力进行了分析,提出了再生制动控制策略。该策略不但能够合理分配前后轮制动力,而且能够合理分配后轮液压制动力、电机制动力和发动机反拖制动力,在保证制动性能的前提下,使电机能够最大限度的回收制动能量。仿真结果表明了所提方法的有效性。