电动机的制动方式主要有机械制动和电气制动，机械制动是通过机械置来卡住电机主轴，使其减速，电磁抱闸、电磁离合器磁铁

电气制动时在应用中多采用电气制动，常用电气制动

1. 短接制动 制动时将电机的绕组短接，利用绕组自身的电阻消能量。由于绕组的电阻较小，耗很快，有一定的危险性，能烧

2. 反接制动 直流电制动，将电机的电源正负极反接，改变电枢电流的方向，这样转矩的方也改变，使得转速与转矩的方向相反。交流电机制动采改变相序的方法产生反向转矩，原理类似。反接制动制动力强，制动迅，控制电路简单，设备投资少，但制动准确性差，制动程中强烈，易损

3. 能耗制动 制动时在电机的绕组中串接电，电动机当于发电机，将拥有的能量转换成电消耗在所串电阻上。这种方法在各种电机制动中广泛用，变频控制也用到了。从高低速（零速），这时电气的频率变化很快，但电动机的子带着负载（生产机械）有较大的机械惯性，不可很快的停止，这样就产生反电势EU （端电压）电动机处发电状态，其产生反向转矩与原电动态转矩相反，而使电动机具有较强的制力矩，迫使子较快停下来但由于通常变频器是交－直－交电AC/DC整流电路是不可逆的因此无法馈到电网上，果造主电路电器二端电

超过设定上限值电时，制动回路导通，这就是制动单元的工作过程，制动电阻流过电源，从而将动能变热消耗电压随之下降，待到设定下限值时即断. 这制动方法属不可控，动力矩有波动，动是可人

制动电阻的选取经

1、电阻值越小，制动力矩越大，流过制单元的电

2、不可以使制动单元的工作电流于其允许最大电，否则要损

3、制动时间可人为选

4、小容量变频器(≤7.5KW) 一般是内接

5、 当在快速制动出现过电压时说电阻值过大来不放电，应减少

4. 直流制动 主用变频控制中。在电动机定子加直流电压，此时变频器输出频率为零，这时定子产生静止的恒定磁，转动着的转子切割此磁场产生制动力矩，迫使电动机转子快的停止，这样电动机诸的动能换成电能耗电动机的

5. 能量回馈制动 当采有源变技术控制电机时，将制动再生电能逆变为与电网同频率同相位的电回送电网，并将电能消耗在网上从而实现制动。能量馈装置系统具有的优越性远胜过能耗制动和直流制动所以近年来不少使用单位结使用设备的特点纷纷提出要求配能量回馈装置的要求国外

芬兰Vacon 等少数不多的公司能提供品国内几

6. 并联电容制动 一种电容放电三相单伺服电机电制动方法，其特征在于：在转的电机需要制动时，将原电源输入断开，并同时将电能的电容连接在伺服电机绕组，通过机绕组放电，在电机内产生直流磁场，在直流磁场作用下，使电机转子制动，进行机制动，同时电容的电能消耗，电机制动后，电容的电能耗尽。其方法能耗温升小，防止电机烧毁，电机寿，制动效果好。该结构便于现场换，提电动果，提高了电

电动机的制动方式

电动机的制动方式

Mosk 06-04-05

电动机的制动方式主要有机械制动和气制动，机械制是通过机械装

电机主轴，使其减速，如电磁抱闸、磁离合器等电磁制动器。电气

应用中多采用电气制动，常用的电气

1. 短接制动

制动时将电机的绕组短接，利用绕组自的电阻消耗能量。由于绕组的电

耗能很快，有一定的危险性，可能

2. 反接制动

直流电机制动，将电机的电源正负极接，改变电枢电的方向，这样

向也改变，使得转速与转矩的方向相。交流电机制动用改变相序的

反向转矩，原理类似。反接制动制动强，制动迅速，制电路简单，

少，但制动准确性差，制动过程冲击力强烈，损坏传动部

3. 能耗制动

制动时在电机的绕组中串接电阻，电机相当于发电机，将拥有的能量

能消耗在所串接电阻上。这种方法在种电机制动中广应用，变频控

了。从高速到低速（零速），这时电的频率变化很快，但电动机的转

载（生产机械）有较大的机械惯性，可能很快的停止，这样就产生反

（端电压）电动机处于发电状态，其生反向电压转矩原电动状态转

而使电动机具有较强的制动力矩，迫转子较快停下来由于通常变频

直－交主电力AC/DC整流电路是不逆的因此无法回到电网上去，

主电路电容器二端电压升高，称泵升压，当超过设定限值电压时，

导通，这就是制动单元的工作过程，动电阻流过电源，从而将动能变

电压随之下降，待到设定下限值时即断.这种制动方法不可控，制动力矩有波，制动时间是可人

制动电阻的选取经验：

? 电阻值越小，制动力矩越大，流过制单元的电

? 不可以使制动单元的工作电流大其允许最大电流，否则要损坏器

? 制动时间可人为选择;

? 小容量变频器(?7.5KW)般是内接制动元和制动电阻

? 当在快速制动出现过电压时说明电值过大来不及放，应减少电阻

4. 直流制动

主要用于变频控制中。在电动机定子直流电压，此时频器的输出频

这时定子产生静止的恒定磁场，转动的转子切割此磁

动机转子较快的停止，这样电动机存的动能换成电能耗于步电动机

路中。

5. 能量回馈制动

当采用有源逆变技术控制电机时，将动时再生电能逆为与电网同频

的交流电回送电网，并将电能消耗在网上从而实现制。能量回馈装

有的优越性远胜过能耗制动和直流制所以近年来不使用单位结合

的特点纷纷提出要求配备能量回馈装置的要求国外也仅有ABB、西门子、富士、安川、芬兰Vacon等少不多的公司能提供产品内乎空

6. 并联电容制动

一种电容放电式三相单相伺服电机电动方法，其特征于：在旋转的

制动时，将原电源输入断开，并同时充有电能的电容接在伺服电机

通过电机绕组放电，在电机内产生直磁场，在直流磁作用下，使电

动，进行电机制动，同时电容的电能耗，当电机制动，电容的电能

方法能耗温升小，防止电机烧毁，电寿命长，制动效好。该结构便

换，提高电制动效果，提高了电动行器的可

变频器控制电动机停车制动方式

电动机知识

变频器控制电动机停车制动

电动机停车方式由 P0700和 P0701~P0708设置。 制动时有 如下

(1)由外接数端控制。将 P0700设为 2, P0701设为 1, 即可由外接数端子 5 (DINI,低电平 ) 控制电机制动,制动 时可由 P1121置斜坡

(2)由 BOP 的 OFF 键控。 将 P0700设为 1, P0701设为 3, 为 OFF2方,即按惯性自由停车。用 BOP 的 OFF (停车) 键制时, 按下 OFF 键 (持续 2s) 或按两次 OFF (停车) 键即可。 (3)用 OFF3命令使电动机快减速停车。将 P0701设为 4,

为了起动电动机, 进输入端必须闭合 (高电平) 。 如果 OFF3为高电平,电动机才能起动并用 OFF1或 OFF2方式停车。如 果 OFF3为低电平,动机不能起动。 OFF3可以同时具有 流、复合制

(4)直流注入制动。变频调速统在降过程中,电动机因 为处于再生动状态而迅速降速。但随着转速的下降,拖动 统的动能减小,电动机的再生能力和动转矩也随之减小。所 以, 在惯性较大的拖动系统中, 会出现低速时停不住的 “爬行” 象。为了克服“爬行”现,当拖动系统的转速下降到一定 程度,向电动机绕组中通入直流电,以大动矩,使 拖

在预置直流制动功能时,主要定以下

1) 直流制动压。即需要向电动机绕组施加的直流电压。 拖动系统的惯性越大,流制动电压的设定值也越大。 2) 流制动时间。即电动机绕组加流电压

可设定得比估计时间略长一

3) 直流制的起始频率。即变频调速系统由再生制动状态 转为直流制状态的起始频率。拖动系统的惯性大,直流制 动的起始频定值

直流注入制动以与 OFFI 和 OFF3命令同时使用。向电 动机注入流电流时,电动机将快速停止,并在动作用结束 之前一直保持轴静

“使能”直流注入制动可由参数 P0701~P0708设置为 25。 直流制动的持续

P1233设置。直流动流可由参数 P1232设置。直流制动的 起始频率可由数 P1234设置。如果没有数字输入端设为直 流注入制动,而且 P1233≠ O ,那么直流制动将每个 OFFI 命 令后起作用,制动作用持

(5)复合制。复合制动可以与 OFF1和 OFF3命令同时使 用。为进行复合制动,应在交流电流中加入直分量。制动 电流可由参

(6)用外接制动电进动力制动。用外接制动电阻(外形 尺寸为 A ~F 的 MM440变频器采用内置的斩波器) 进行制动时, 按线性方式平滑、可控地降低电动机的速度,如图 3 -14所示。 图 3 - 14 制动电阻

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〃利用 PLC 管理变频器处理机

〃正确使用变频器

〃变频器的转差频率控制

〃变频器选择时的注意

〃变频器应用中存在的问题

〃变频器容量问题如何

〃变频器应用的常见故障与对策(二)

Domain:http://www.shenzhendianji.com 直流减速电机 More:2saffa 〃风机、水泵设备运行

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〃变频器选型时一些要注意

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〃变频器制动控制

〃农用电动机的选择与使用

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〃功率计算公式 /电功率计

〃变频器控制系统过电流故障诊

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〃变频器自动、并联、比例运行及其

〃变频器现场常见 5种故障解

〃变频器的正确选择

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〃变频器产生的传导

〃 Fujifilm 变频器过跳闸及原

〃四象限矢量变频器的应用技

〃电动机的保护电器及导线

〃变频器容量的选择

匿名

随着起重机的不发展,传统控制技术难以满足起重机越 来越高的调速和控制要求。在电技术飞速发展的今天,起重 机与电子技术结合越来越紧密, 如采用 PLC 取代继

逻辑控制,交流变频调速装置取代传统的电机转子电阻的 调速方式等。在选型对基础上,项目电动机调速装置采用 了先进的频调速方案,变频器最型为 ABB 变频器 ACS800,电动机用专用鼠笼变频电动机。在众多交流变频调 速装置中, ABB 变频器以其性能的稳定性,件扩展功能的丰 富,编程环境灵活性,力矩特性的优良性和在不场合使 用的适应性,使其在变频器高端市场中占相重要的地位。 ACC800变频是 ACS800列中具有提升机应

它在全功率范围内统一使用相的控制技术,例如起动 向,自定义编程, DTC 控制等,适合作为起重机主起升 变频器使用。本文结合南京梅冶金发展有限公司设备分公司 所负责维修管理的宝钢集团梅钢冷轧厂 27桥式起重机变频 调速控制系,详细介绍 ACC800变器重机主起

1DTC 控制技术

DTC (直接转矩控制, DirectTorqueControl ) 技术是 ACS800变频器的核心技术,是交流传动统的高性能控制方法之一, 它具有控制算法简,易于数字化实现和鲁棒性强的特点。其 实质是利用空矢量坐标的概念,在定子坐标系下立异步电 动空间矢量数学模型,通过测量三相定子电压和电流(或中 直流电压)直接算电动机转矩和磁链的实际值,并与给定 转矩和磁进行比较,开关逻辑单元根磁比较器和转矩 较器的输出选择合适的逆变器电压矢量 (开状态) 。 子给定 磁链和对应的电磁转矩的际值,可以用定子压流测量 值直接计算得到。在计算中,只需要一个动机参数―――定 子电,这一点和乎需要全部机参数的直接转子磁

向控制(矢量控制)形成了鲜明对比,极大减轻了微处理器 计算负担,提高

。直接转矩控制结构较为简单,可以实现

2防止溜钩控制

作为起重用变频系统,其控制重点之一是电动机处于回 馈动状态下系统

电磁制动器从通电到断电(或断电到

需要的时间大约 016s (视起重机型号和起重量大小而 定) , 变频器如过早停止出, 将容易出现溜钩, 因此变频器必 须免在电磁制动器闸的情况下输较频率,

防止溜钩现象的方法是利用变频器零全转矩能和直流 制动励磁功能。零速全转功能,即变频器可以在速度为零的 状态下,保持电有足够大的转矩,从而保证起设备在速 度为零时,电动机能够使重物在空停止,直到电磁制动器将 轴抱住为止,以止溜钩的发生。直流制动励磁能,即变频 器在起动之前自进行直流强励磁,使电动机有足够大的起动 矩,维持重物在空中的停止状,以保电制器在释放 过

3系统硬件配置

梅钢冷轧桥式起重机上应用的 ACS800变频器调速系由 电控柜,大小车变频控柜,起升变频控制柜,

组成。主起升采用 1台 ACC800变频器驱动 1台起升用电动 机,并在电动机轴尾安装 1台度编码器,速度反馈用。 该速度编码器用来提高低速态下电动机模型的速度和转 算精度,保证转矩验证,开闭闸等功能。主升采用斩波 加制动电阻实现制动功能,斩波器与制动电阻串联接入变 频器整与逆变桥之间的直流回路中,并由变频器根据间直 流回路电压高低控波器接通与否(即控制制动电阻的投 切) 。 变频器有 RPBA201接口卡件, 提供标准 Profibus2DP 现场总线接口,用于与 PLC 通信制,并接收 PLC 来的开, 停车命令

4起升变频器功能参数

ABB 变频器在出厂时,所有功码都已

但是, 起重机变频调速系统的要求与工厂设定值不尽相同, 所以, ACC800一些重要的功能参数

(1)起动数据(参数组 99)

参数 99102(于升类传动,但不包括主 /从总线通信功 能) :CRANE ;参数 99104(电动机控制式) :DTC (直接转 矩控制) ;参数 99105~99109(电动机规铭牌参数) :照 动机的铭

(2)数字输入(参数组 10)

参数 10101~10113(数字输入接口预置参数) :按照变频器 外围接口义进行设置,限于篇

(3)限幅(参数组 20)

参数 20101(运行范的小速度) :-1000 r/min(根据实 际电动机参数进定) ;参数 20102(运行范围的最大速度) : 1000r/min(根据实际电动机参数进行设定) ;参数 20103(最大 输出电流) :120%;参数 20104(最大

数 20104(大输出转矩) :-150%;参数 20106(直流过压控 制器参数) :OFF (本例中 ACC800变频器使用了动力制动式, 此参数设为 OFF 后,制动波才能投入

(4)脉冲编码器(参数组 50)

参数 50101(冲编码器每转脉冲数) :1024;参数 50103 (编码器故障) :FAULT (如果监测到编码器故障或编码通 信失败时, ACC800变器故障并

(5)提升机(参数组 64)

参数 64101(独立运行择) :FALSE ; 64103(高速值 1) : 98%; 64106(给定曲线形状) :0(直线) ;参数 64110(控制类 型选择) :FBJOYSTICK. (6)逻辑处理器(数组 65) 参数 65101(电动机停止后是否保持动机磁场选择) : TRUE (机停止后保持

(8)机械制动控制(参数组 67)

参数 67106(相对零速值) :3%;参数 67109(起动转矩选 择器) :AUTOTQMEM (自记

(9)给定处理器(参数组 69)

参数 69101(对应 100%定设置电动机速度) :980r/min (根据实际电动机参数进行定) ; 参数 69102(向加速时间) : 3s ;参数 69103(反向加速时间) :3s ;参数 69104(正向减速时 ) :3s ;参数 69105(反向减速时间) :3s. (10)

参数 98101(脉冲编码器模块选择) :RTAC2 SLOT2(脉冲 编码器模块类型为 RTAC ,连接接口为传控单元

槽 2) ;参数 98102(通信模块选择) :FIELDBUS (激活外部串 通信并选择外部串通

5试运行

变频调速系统的功能参数设定后, 就可进行系统试运行。 应先变频器操作盘上进行速度给定,手动起动变,让起 升电动机空载运转一段间,并且这种试运行可以在 5, 10, 15, 20, 25, 35, 50Hz 等几个频率点进行,注观察电动机的 运转方向是否正确,速是否平稳,显示数据是正确, 否正常,加

。单台变频器试运行正确后,再接入脉冲编码器模进行 速度闭环调试,运行起升机构变

起升变频器手动行误后, 就可接入 PLC 控制系统, 进 行整机联调。整机联调中,关要注意观察变频器起动与停止 时,主起升机制动器的开闭反应否快速,钩头在溜

其次还要注意观察钩头在下降过程中,制动元和制动电 阻投运后,其温升是否常。在重物下放过程中,重物的势能 会释放出来,时电动机将工作在反向发电状态。在钩下降 过程中,电动机通过逆变桥变频器中间直流回路充电,当直 流回路的压高于变频器系统设定值时,变频器控制斩波器接 通,而使制动电阻投入工作,以消耗变频器中间回路多 余的电能,确保变频中间直回压稳定在一个特

随着起重机的不断发,统控制技术难以满足起重机越 来越高的调速和控要求。在电子技术飞速发展的今天,起重 与电子技术的结合越来越紧密, 如采用 PLC 取代电器进行 逻辑控制,流变频调速装置代传的电动机转

调速方式等。在选型对比基础上,本项电动调速装置采用 了先进的变频调速方案,变频器最终选型为 ABB 变频器 ACS800,机选用专用鼠笼变频电动机。众多交流频调 速装置中, ABB 变频器其性能的稳定性,选件扩展功能的丰 富性,程环境的灵活性,力矩特性的良性和在不同场合使 用的适性,使其在变频器高端市场中占有相当重要的。 ACC800变频器是 ACS800系具有提升机应用

它在全功率范围内统一使用相的控制技术,例如起动 向,自定义编程, DTC 控制等,适合作为起重机主起升 变频器使用。本文结合南京梅冶金发展有限公司设备分公司 所负责维修管理的宝钢集团梅钢冷轧厂 27桥式起重机变频 调速控制系,详细介绍 ACC800变器重机主起

1DTC 控制技术

DTC (直接转矩控制, DirectTorqueControl ) 技术是 ACS800变频器的核心技术,是交流动系统的高性能制方法之一, 它具有控制算法简单,易于数字化和鲁棒性强的特点。其 实质是利用空量坐标的概念,定子坐标系下建立异步电 动机空间量数学模型,通测量三相定子电压和电流(或中 间直流电压)直接计算电动机矩和磁链的实际值,并与给 转矩和磁链进行比较,开关逻辑单元根据磁链较器和转矩比 较器的输出选择的逆变器电压矢量 (开关状态) 。 定子给定 磁链和对应的电磁的实际值,可用定子电压和电流测量 值直接计算到。在计算中,只需一动机参数―――定 子电阻,这一点和几乎需要全部动机参数的直接子磁定 控制(矢量制)形成了鲜比,极大地减轻了微处

的计算负担,提高了运算

。直接转矩控制结构较为简单,可以实现

2防止溜钩控制

作为起重用变频系统,其控制重点之一是电动机处于回 馈动状态下系统

电磁制动器从通电到断电(或断电到

需要的时间大约 016s (视起重机型号和起重量大小而 定) , 变频器如过早停止出, 将容易出现溜钩, 因此变频器必 须免在电磁制动器闸的情况下输较频率,

防止溜钩现象的方法是利用变频器零全转矩能和直流 制动励磁功能。零速全转功能,即变频器可以在速度为零的 状态下,保持电有足够大的转矩,从而保证起设备在速 度为零时,电动机能够使重物在空停止,直到电磁制动器将 轴抱住为止,以止溜钩的发生。直流制动励磁能,即变频 器在起动之前自进行直流强励磁,使电动机有足够大的起动 矩,维持重物在空中的停止状,以保电制器在释放 过

3系统硬件配置

梅钢冷轧桥式起机上应用的 ACS800变频器调速系统由 电控柜,大小车变频控制柜,升变频控制柜,联动控制台等 组成。主起升用 1台 ACC800变频器动 1台起

机,并在电动机轴尾安装 1台速度编码器,速度反馈。 该速度编码器用来提高低速状下电动机模的速度和转 矩计算精度,保证转矩证,开闭闸等功能。主起升斩波 器加制动电阻实现制动功能,斩器与制动电串联后接入变 频器整桥与逆变桥之间的直流路中,并由变频器根据中间直 流回路电压高低控制斩器接通与否(即控制动阻的投 切) 。 变频器配有 RPBA201口卡件, 提供标准的 Profibus2DP 现线接口,用于与 PLC 通信控制,接收 PLC 来开, 停命令和

4起升变频器功能参数

ABB 变频器在出厂时,所有功码都已

但是, 起重机变频调速系统的要求与工厂设定值不尽相同, 所以, ACC800一些重要的功能参数

(1)起动数据(参数组 99)

参数 99102(于升类传动,但不包括主 /从总线通信功 能) :CRANE ;参数 99104(电动机控制式) :DTC (直接转 矩控制) ;参数 99105~99109(电动机规铭牌参数) :照 动机的铭

(2)数字输入(参数组 10)

参数 10101~10113(数字输入接口预置参数) :按照变频器 外围接口义进行设置,限于篇

(3)限幅(参数组 20)

参数 20101(运行范围的最速度) :-1000 r/min(根实 际电动机参数进行设定) ;参数 20102(运行范围的最大速度) : 1000r/min(根据实际电动机数进行设定) ;参数 20103(最大 输出电流) :120%;参数 20104(最

制器参数) :OFF (本例中 ACC800变频器使用了动制动方式, 此参数设为 OFF 后,制动斩波器才运

(4)脉冲编码器(参数组 50)

参数 50101(冲编码器每转脉冲数) :1024;参数 50103 (编码器故障) :FAULT (如果监测到编码器故障或编码通 信失败时, ACC800变器故障并

(5)提升机(参数组 64)

参数 64101(独立运行择) :FALSE ; 64103(高速值 1) : 98%; 64106(给定曲线形状) :0(直线) ;参数 64110(控制类 型选择) :FBJOYSTICK. (6)逻辑处理器(数组 65) 参数 65101(电动机停止后是否保持动机磁场选择) : TRUE (机停止后保持

(8)机械制动控制(参数组 67)

参数 67106(相对零速值) :3%;参数 67109(起动转矩选 择器) :AUTOTQMEM (自记

(9)给定处理器(参数组 69)

参数 69101(对应 100%定设置电动机速度) :980r/min (根据实际电动机参数进行定) ; 参数 69102(向加速时间) : 3s ;参数 69103(反向加速时间) :3s ;参数 69104(正向减速时 ) :3s ;参数 69105(反向减速时间) :3s. (10)

参数 98101(编码器模块选择) :RTAC2 SLOT2(脉冲 编码器模块类型为 RTAC ,连接接口为传动控制单元的选件插 槽 2) ;参数 98102(通信模选择) :FIELDBUS (

行通信并选择外部串行通信接口) 。

5试运行

变频调速系统的功能参数设定后, 就可进行系统试运行。 应先变频器操作盘上进行速度给定,手动起动变,让起 升电动机空载运转一段间,并且这种试运行可以在 5, 10, 15, 20, 25, 35, 50Hz 等几个频率点进行,注观察电动机的 运转方向是否正确,速是否平稳,显示数据是正确, 否正常,加

。单台变频器试运行正确后,再接入脉冲编码器模进行 速度闭环调试,运行起升机构变

起升变频器手动行误后, 就可接入 PLC 控制系统, 进 行整机联调。整机联调中,关要注意观察变频器起动与停止 时,主起升机制动器的开闭反应否快速,钩头在溜

其次还要注意观察钩头在下降过程中,制动元和制 动电阻投运后,其温升是否常。在重物下放过程中,重物的 势能会释放出来,时电动机将工作在反向发电状态。在钩 下降过程中,电动机通过逆变桥变频器中间直流回路充电, 当直流回路的压高于变频器系统设定值时,变频器控制斩波 器接通,而使制动电阻投入工作,以消耗变频器中间回 路多余的电能,确保变频中间直回压稳定在一个特

电动机反接制动

技工学校生产实习课教案纸(首页)共14页第 1 页

审阅签名 课 题 电动机反制动控制

审阅日期

年 月 日至 年 月 日 授课日期

第 周星期 第 节至第 周星

1.让学生了解什么是制动、为什么要制动、制动的场合要求;; 教学目的 1.让学生了解度继电器的结构、动及

2.使学生掌握电动机反接制动控制线路的安

教学重点 电路安装与调

教学难点 速度继电器的动作与应用

预 习

预习《电力拖动控制线路与技能训练第四版》P175,P193 及 小分析实习电路的工作原理，思考:P192习题2-6<1、2> 课

图 电动机双向反接制动控制线

课

前

器 准电力拖动控制板(每个学生一套)、BV-1/1.13线、电

内

容

工

量 万用表、测电笔、旋具、

具

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(次

第 2 页 教学环节 内 容 要 点 时 间

检查学生出勤、佩戴校卡、教室卫生情况;检查实习材、工具仪表准备情况; 全程 组织教学 安

讲 1.电动机制的用场合 2.电动机制动方式及原理分析 解 3.反接制动与能耗制动的比较 3时 4.反接制动的特点分析 入 要 5.速度电器的构造、原理及用 6.实电

指

导 演 10min 模拟速度电器触头的动，反接制动

示

布置 5min 见教案P13

1.布线与接线工艺。

2.速度继电器的电路接入点。 14学时 巡回指导 3.线路检查

4.通电操作监护及指导。

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

1学时 结束指导 书面作业及实作业质量

技工学校生产实习课教案纸(续页) 第3 页

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

时间分配 入门指导内容及步骤 及

复习:

复习、总结:时间继电器自动控制Y--?降压启

总结:Y--?降压启动线路的要

新课:课堂提问:电动机为什么要采取制, 新课

问:10min 引入:

三相异步电动机切断电源后，由于惯性，总要经过

间才能完全停止。为缩短时间，高生产效率和加精度，要新

2min 求生产机械能迅速准确停车。采取一定施使三相异

机在切断电源后迅速准确地停车的过程，称三相异步

制动。三相异步电动机的制动方法分为机械动和电气

大类.

一、电动机制动的应用场

电机制动是电机控制中经常遇到的问题，一般电机

举例说明制出现在两种不同的场合，一为了达到迅速停的目的，以各

合:5min 种方法使电机旋转磁的旋转方向和子旋转方向相

产生一个电磁制动转矩，使电机迅速停车动;另一

场合，当转子转速超过旋转磁场转速时，电机处于制动

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第4 页 时间分配 入

由于电动机从切断工作电源到完全停止旋转,因惯性的

要经过一段时间。这就不能适应某些生产

机吊钩需要准确定位,万能铣床要求立即停,水泥物

验设备中的振动台,搅拌器不能有余振等。另一些生

虽然不需要准确定位,但为了缩短生产辅助时间,提生产 结合电路图二、动机制动方式及原

式及原理:制动目的:准确、迅速停车;工作

机械制:机械

制动分类

电气制:反接制动、耗制动、回

机械制动:用电磁铁操纵机械机构进行制(电磁抱

电磁离合器制动等)。

电气制动:用电气的办法，使电动机产生个与转子

向相反的力矩进行制动。

1、机械制动:(电磁抱闸)

1)、电磁抱闸的结构:制动电铁、闸瓦

2)、机械制动控制电

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第5 时间分配 入门

2、电气制动

原理:制动时使电动机产生与转子原转向反的制动

1)、反接制动

原理:改变电动机任意两相电源相序以生制动转

特点:设备简单，制动力矩较大，冲击强，准确度

适用场合:要求制动迅速，制动不频繁(各种机床

动)。

说明:1>反接制动时，当电动机的转速近于零时

切断电源，否则电机将反 转。控制要求可速度继电器

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第 6 页

时间分配 入门指导内容及步骤 及

n > 100 r/min? KS=1

n < 100="" r/minsb1?—?="" km1="1" km2="1?" ks="1—?" km2="1" 自由停车="">

2>反接制动的电流(制动冲击力)较大，在主电路串入限流电

10kw以上电动机的定子电路中串入对称电阻或不对电阻，称为制动电阻。以制制动电流和减少

3>注意速度继电器触点的方

2)、能耗制动

原理:制动时，切除定子组三相电源同时接通直

产生静止磁场，使惯性转动的转子静止磁场

下产生制动转矩。

特点:能耗小，需直流电源，设备费用

(制动准确度较高，制动转矩平滑，但

转矩与转速成比例减小)

适用场合:要求平稳制动，停位准确。(如床、龙门刨床及组机床的主轴定

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第7 时间分配 入门

说明:1>主电路中的R用于调节制电流的大

2>能耗制动结束，应时切除直

SB2? ——? KM1=0

SB1?——? KM1=0 KM2=1 KT=1 ——? KM2=0 KT=1 ?T

自由停车制动

补充:KM2常开触点上方应串接KT瞬动开触点。

出故障时其通电延时常闭触点无法断开，致KM2不

导致电动机定子绕组长期通入直流

本课题以反接制动为重点进行详分析及

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第 8 页 时间分配 入

三、反接制动与能耗制动的比 反接

能耗制动的不同的制动方式是根据生应用的不同要求产生的,各比

板书):有其优点与缺点, 在总体是一种互为补充

两种不同制动方式的比较见下

制动方式 优 点 缺 点 适 用 性

能 1.制动平稳; 1.需

耗 2.能量损耗小。 2.当电

制 大情况下,设

动 备投

3.制动

反 1.设备简单, 1.制动击较大;

接 调整方便。 2.制动能量

制 2.制动迅速; 大;

动 3.控制器件对 3.不宜繁制动。

电动机大小

通用性

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第 9 页 时间分配 入

反接制动有一个最大的缺点，就是:当

如果不及时撤除反相后的电源，机会反

解决此问题的方法有以下两

1、在电机反相电源的控制回路中，加入一时间继电

相制动一段时间后，断开反相后的电源，而避免电

但由于此种方法制动时间难于估算，因而制效果并不

2、在电机反相电源的控制回路中加入一个

器检测到电机速度为0时，及时切掉电机

种方法速度继电器实时监测电机一转速，而制动效

种方法要好的多。

正是由于反接制动有此特点，因此，不允反转的机

些车床等，制动方法就不能采用反接制动，而只能

制动或机械制动。

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第10 页 时间分配 入

四、反接制动的特点分析 反接

特点分析反接制动是通过改变电动机源相序, 使

书):10min 旋转磁场与转子惯旋转的方向相反, 因而产生制动

电动机转速迅速下降,直至停止。如果当电动机

仍未把反向电源断开, 则电动机反转。反制动控制

是恰到好处地把握 n?0 的瞬间,及切断反向

由于反接制动时, 定子旋转磁场与转子相对速度

二倍同步转速。所以定子绕组中流过的反制动电流

动机全压启动电流的二倍。因电动机作反接

量很小,一般应在定子回路串接限流电阻。制动限流

用,除了限流,也起到了减缓制动击的作

控制任务是提出来了,如何实现控制目就成了突

题,靠人工来实现 n?0 时切断制动电源然带有很

性, 于是人们应用了速度继电

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第11 页 时间分配 入

五、速度继电器的构造、原理及用 结合

电器实物及 速度继电器曾称“反接动继电器”,实习用的JYL型速

析及讲解速度继电器的构造与工作原理见《电力拖动控线路与技能训度

原理及作用练》P74,P75。 和触

情况(实物 速度继电器的工作原相似于感应电动转动的原理。其

30min 基本结构由笼型定子(际上也可动)、磁转子、触头

个部分构成。速度继电器安装于与电动机同转动处,

转动时,带动速度继电器的永磁转子以相同

转动所产生的旋转磁场与定子笼型绕组感应流相互作

可动的定子以一定的滑差随转子转动, 但转过一个

就因受到结构限位而停止。定子的转动通过杆使触头

常闭触头断开,常开触头闭

被控电动机的转向不同,速度继电器定因滑差而

方向相应不同,其所带动的触头也分属于独的不同对

见,速度继电器总体上可运用于正转及反转场合。但

应根据不同转向正确选用。

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第 12 页

时间分配 入门指导内容及步骤 及

速度继电器不但可用于反接制动控制,可用于能

电路。

速度继电器在电气图中的表

文字符号:SR或KS

速度继电器的安装与使用有如下特

1.速度继电器转子与电动机转轴同轴联接,安装过程

轴线重合。

2. JY1型的工作范围是100--3000转/分,转子速度达到120转/

分以上,常闭触头断开,常开触闭合,当转

分以下,触头复位。(JY1型用“切换”触) 通过旋

构的调节螺丝,可使其动作值有所改

3.进行触头动作值调整操作时,应在断开电后进行,

短路事故。

4.触头动作具有方向性,使用中应充分意判断清

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第13 页

时间分配 入门指导内容及步骤 及

六、实习电路及安装要求: 板书

析电路工作1.按给定电路图接线。 原

布置任务及

安装要求:

5min

2.进出按钮的线数为最少(7根)。

巡回指导:3.速度继电器作为外接器件，电路安装时应把应的电路接入强

接线工艺、点引到实习板的接线端子

生产:4.器件使用规定: 300min

KM1--1# KM2--2#

SB1--红 SB2--绿 SB3--黑

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

技工学校生产实习课教案纸(续页) 第 14 页

时间分配 入门指导内容及步骤 及

5.通电前用电阻法检查电路制功能，确通电一次成

通电检查:6.通电试车各项操作安全、合，有预防性措施(

电路两相电源线);

7.安装时限:四节课;

8.书面作业均应在课后完成(规

9.小结 小结:30min

布置预习内容:《电力拖动线路控制与能训练》

P194-203 《多速异步电机控制线

such as wages, subsidies to give some support, the new finds at national, provincial and municipal engineering laboratories, research centers and otherSome research funding support from the platform. Second, business methods of science are diverse. Innovative investment methods, expanding investment channels, to investment to achieve tangible results. At present, in the County completed project is our invitation to work can make good use of resources, rich with enterprise information, contacts, and other resources for investment by business, not only low cost and high efficiency. Relatives and friends also can use outside resources, we must actively take the initiative to strengthen contacts with them, making full use of their resources, for the County investment broker. The town streets, industrial development focal points to pick a strong backbone of investment, aimed at more recent relocation of Beijing-Tianjin-Tangshan, Yangtze River Delta and other economically developed areas, the implementation of resident merchants. Internet merchants, so ... ... Investment, investment, investment policy on the Internet "play" and let customers know more about ... ... and the ... ... and yearn for. ... ... Make full use of the Internet for valuable business information, communicating and negotiating with that as a clue. Investment firm into line and encourage qualified enterprises to actively introduce strategic partners, through mergers, asset restructuring, equity investment, transfer, technological innovation and other forms of enterprise

电动机制动方法

1、能耗制动

电动机定子绕切断三相电源后迅速接通直流电源。感应电流与直流电产生的固磁场相互作用，产生的电磁转矩方与电动机转子转动方向相反，制动

特点:是制动准确、平稳，但需要额的直流电

2、反接制动

电动机停车时将三相电源中的任意两相对调，使电动机产生旋转磁场改变方向，电磁转方向也随之改变，成

注意:当电动机转速接近为零时，要及时断开电防止电动机

特点:简单，制效果好，但由于反接时旋转磁场与转子间的相对运动加快，因而电流较大。对功率较大的电动机制动时必须在定子电路(鼠式)或转子电路(绕线式)中接电，用以

3、发电反馈制动

电动机转速超过旋转磁的速时，电磁转矩的方向与转子的运动方向相反，从而制转子的转速，起到了制动作用。因为当转子速大于旋转磁场的转速时，有电能从电动机的定子返回给电，实际上这时电动机已经入发电机运行，所这动称为发

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