DC Motor

dc马达DC马达1. 介绍DC马达是一种常见的电动机类型，也被称为直流电动机。

它广泛应用于各种领域，如家用电器、工业设备、汽车等。

DC马达的优点包括简单的结构、高效率和可控性。

本文将对DC马达的工作原理、分类和应用进行详细介绍。

2. 工作原理DC马达的工作原理基于法拉第电磁感应定律和洛伦兹力。

通过在磁场中传递电流，产生的磁场与外部磁场相互作用，产生力矩，从而使电动机转动。

DC马达由两个主要部分组成：电枢和磁极。

电枢是电流通过的部分，通常由导电线圈构成。

磁极由恒定的磁场提供。

3. 分类DC马达可以根据其电源类型和结构特征进行分类。

3.1 电源类型分类DC马达的电源类型主要有直流供电和交流供电两种。

直流供电的DC马达适用于电池供电或其他直流电源供电的应用。

交流供电的DC马达则需要将交流电转换为直流电，通常通过整流器实现。

3.2 结构特征分类DC马达的结构特征主要包括分磁极、直流励磁、换向器和刷子等。

分磁极马达适用于高转速和高功率需求的应用。

直流励磁马达带有额外的磁极，可以通过调节励磁电流来控制电动机的转速和转矩。

换向器是用于将电源电流方向反转的装置，通常由机械式刷子或电子式换向器组成。

4. 应用DC马达在各个领域有广泛的应用。

4.1 家用电器DC马达经常在家用电器中使用，例如电风扇、洗衣机和吸尘器等。

它们通常用于驱动风扇叶片、转动洗涤筒或提供吸力。

4.2 工业设备DC马达在工业设备中也使用广泛，如工作机器人、输送带和印刷机等。

DC马达可提供高转矩和可控制的速度，使其非常适合这些应用。

4.3 汽车DC马达在汽车的应用领域也非常重要，包括起动马达、电动窗户、风挡刮水器和电动座椅等。

DC马达的高效率和可控制性使其在汽车行业中成为一个理想的选择。

4.4 健身器材DC马达还在健身器材中发挥重要作用，如跑步机和椭圆机等。

通过调整电动机的速度和转矩，用户可以根据自己的需求来调整锻炼强度。

5. 优缺点DC马达具有以下优点：- 可控性强：通过调整电源电压和电流，可以控制马达的转速和转矩。

用于电动汽车的7种类型电机介绍电动汽车是一种以电动机为动力的汽车，相较于传统的内燃机汽车，电动汽车具有环保、节能和高效等优势。

电动汽车可根据所采用的电机类型的不同，分为直流电机（DC motor）和交流电机（AC motor）两大类。

在这两大类电动机中，分别有多种类型的电机适用于电动汽车。

以下是用于电动汽车的7种类型电机的介绍。

1. 永磁同步电机（Permanent Magnet Synchronous Motor，PMSM）永磁同步电机是一种常用于电动汽车的电机类型。

其特点是具有高效率、高功率密度、高转速范围等优势。

永磁同步电机由永磁体和定子线圈组成，通过永磁和电磁场的相互作用来产生转矩和驱动车辆。

此外，永磁同步电机的转矩-转速特性较宽，使得它适用于多种驱动需求。

2. 交流异步电机（Asynchronous Motor）交流异步电机又称感应电机，是一种常用的电动汽车电机类型。

其特点是结构简单、成本较低、可靠性高等。

交流异步电机由转子和定子两部分组成，通过转子电流和定子电流之间的相对滑差产生转矩和驱动车辆。

由于交流异步电机的可控性较差，一般需要通过变频器等辅助设备来调节速度和转矩。

3. 刷直流电机（Brushed DC Motor）刷直流电机是一种传统的电机类型，其结构简单、成本低廉。

刷直流电机由永磁体和集电刷等部件组成。

它通过将直流电能转化为机械能来驱动车辆。

刷直流电机具有响应快、启动转矩大等特点，但同时也存在集电刷磨损严重、噪音大等缺点。

4. 无刷直流电机（Brushless DC Motor，BLDC）无刷直流电机是刷直流电机的一种改进型。

与刷直流电机相比，无刷直流电机的集电刷被永磁体替代，因此无刷直流电机具有更高的效率和可靠性。

无刷直流电机通过在定子上进行交替换相来产生转矩和驱动车辆。

无刷直流电机在电动汽车中广泛应用，尤其适合于对续航里程和动力性要求较高的车辆。

5. 齿轮电机（Gear Motor）齿轮电机是一种将电能转化为机械能的电机类型。

直流电机的分类直流电机是一种将直流电能转换为机械能的设备，广泛应用于工业生产、交通运输、家用电器等领域。

根据不同的特点和应用需求，直流电机可以分为多种分类。

本文将详细介绍直流电机的几种常见分类。

1. 按励磁方式分类1.1 永磁直流电机（Permanent Magnet DC Motor）永磁直流电机是利用永磁体产生恒定磁场的直流电机。

它具有结构简单、起动扭矩大、响应快等优点，广泛应用于家用电器、办公设备等领域。

根据永磁体的材料不同，永磁直流电机又可分为硬磁材料和软磁材料两种类型。

1.2 励磁直流电机（Separately Excited DC Motor）励磁直流电机是通过外部提供励磁电源来产生磁场的直流电机。

它具有调速范围广、稳态性能好等特点，常用于工业自动化控制系统中。

1.3 刷激励直流电机（Brush Excitation DC Motor）刷激励直流电机是利用刷子和电枢之间的接触产生激励电流的直流电机。

它具有结构简单、成本低廉等优点，但刷子与电枢之间的摩擦容易产生火花，寿命较短。

刷激励直流电机在一些特定场合中被替代。

2. 按电枢绕组连接方式分类2.1 直流串联电机（Series DC Motor）直流串联电机是将电枢绕组与励磁绕组串联连接的直流电机。

它具有起动扭矩大、转速随负载变化较小等特点，常用于起动扭矩要求较高的场合，如起重机、风力发电等。

2.2 直流并联电机（Shunt DC Motor）直流并联电机是将电枢绕组与励磁绕组并联连接的直流电机。

它具有转速稳定、调速范围广等特点，常用于需要稳定转速和调速性能较好的场合，如印刷机、纺织设备等。

2.3 直流复合绕组电机（Compound DC Motor）直流复合绕组电机是将电枢绕组与串联励磁绕组和并联励磁绕组相结合的直流电机。

根据串联励磁绕组和并联励磁绕组的连接方式不同，直流复合绕组电机又可分为串励复合绕组电机和并励复合绕组电机两种类型。

直流电动机简介作者:王崇飞 (1999-08-12);修改:王崇飞 (2000-05-05);核可:徐业良 (2000-05-08). 附注:本文为元智大学机械系大四自动化机械设计实务课程教材.直流电动机简介一,电动机的种类与原理电动机即为工业界俗称的马达,种类依照使用电源可分成直流马达(DC motor)与交 流马达(AC motor)两大类,若再以控制方式,启动方式与绕组方式分类则可分成步进马 达(stepping motor),伺服马达(servo motor),无刷马达(霍尔马达) ,单相交流马达,三 相感应马达,串激式直流马达,分激式直流马达,与复激式直流马达等. 其中无刷马达又称作直流伺服马达(DC servo motor),直流伺服马达之特性与直流马 达相似,两者的差异在於直流伺服马达利用角度编码器(encoder)与转速发电机(TG)将马 达的转速,扭矩等物理量检出,再利用控制器将回授讯号作运算,达到控制直流伺服马 达的输出特性,同时利用霍尔元件取代电刷,因此在结构上直流伺服马达除了感测器部 份以外,其余均与一般的电动机相仿.以下分别讨论直流马达与无刷马达的构造与原 理,以及各类马达性能之比较. 直流马达的构造与原理 直流马达的构造与原理 图 1 为马达之基本构造示意图,一般的电动机在构造上可以分成五个部份:1.tw/直流电动机简介定子 转子换向器 轴承控制器图 1 马达之基本构造 1. 电枢(armature)或转子(rotor) 为马达旋转的部份,材质为永久磁铁,线圈(外接电源),导线(无外接电源)或 特殊形状之导磁材料. 2. 场绕组(field)或定子(stator) 材质为永久磁铁或是线圈(外接电源). 3. 滑环(slip ring)或换向器(commutator,如直流马达之碳刷) 连接转子绕线至外部换向器用於改变电枢绕线之电流方向,使用永久磁铁为转 子材质的马达则无需滑环或换向器. 4. 轴承(bearing) 可使用滚珠,滚针,滚柱,含油自润轴承,主要提供转子稳固的支撑. 5. 马达控制器(motor controller) 包含控制马达的输出扭矩,速度或转角,以及大型马达起动,停止之顺序控制. 控制器种类也相当多,如单相交流马达使用的电容分相启动器,直流马达使用的功 率控制器,变频器,或是伺服马达控制器等,都是属於马达控制器. 虽然电动机的种类相当多,不过各种电动机的基本操作原理都相同,都是利用电流 流过定子产生磁场,当转子也通上电流时由於切割定子所产生的磁力线而生成旋转扭矩 造成电动机转子的转动.如图 2 所示,假设转子之绕组只有一组线圈时,当转子线圈通 上电流时由於切割定子所产生的磁力线而生成旋转扭矩,致使转子转动,以图 2 而言, 定子的磁力线由左至右,而转子的电流方向为由右方流入左方流出,因此生成的旋转扭 矩使得转子顺时针旋转.2.tw/直流电动机简介NS图 2 电动机基本原理示意 直流马达之基本构造均与图 2 类似,其他种类电动机的基本构造则只是在定子部份 有所差异,例如交流感应电动机由於交流电源有相角差之缘故,因此定子的磁场由固定 磁场变成旋转磁场,此外场绕组 (定子) 的接线方法也有所谓"Y 接法","Δ接法", 或是"Y-Δ接法". 无刷马达的构造与原理 电动机构造中滑环由於是采用接触式通电的方式,所以也称作电刷.在直流电机中 常以石墨作为电刷的材质,电刷长期与电动机的转子摩擦会造成相当程度的噪音,同时 也会因磨耗而需要考虑维修的问题.在交流电动机中电刷则采用金属材料制作,在长期 磨耗下会造成间隙(gap),容易在运转时发出火花,诸如此类的问题都对电动机的可靠度 与安全性有相当程度的影响. 无刷马达就是在这样的需求下产生,无刷马达在构造上是利用永久磁铁作为转子, 并且利用霍尔效应感应电动机转子的位置,当转子之相位为 π 2 时令定子激磁,如此可 以达到最高的运转效率,利用这样的原理也可以使用在四行程机车引擎点火正时上.霍 尔效应满足以下关系式:VH = KH I H B cos θ + KI H d(1)KH 为霍尔元件电磁系数,K 为霍尔元件不平衡 d其中 VH 为霍尔电压, I H 为霍尔电流,系数,B 为磁通密度.由式(1)可以了解霍尔电压与磁通密度(磁场强度)及霍尔电流成 正比,因此当转子之磁轴与霍尔元件不同轴时,磁通较小,为了维持固定的霍尔电压必 须增大霍尔电流,如此便能精确的算出定子的激磁顺序与时间.霍尔元件与直流马达所 构成的无刷马达如图 3 所示.3.tw/直流电动机简介a L1 N S a i1 i2 霍尔元件 b L2 Q1 A B RbVb Q2图 3 无刷直流伺服马达 如图 3 所示,当转子磁轴与霍尔元件同轴时,霍尔元件与 S 极距离最短,因此磁通 密度最高,此时造成霍尔元件 A 端子电压较大,使得电晶体 Q1 导通,则线圈 L1 内有 i1 电流流通,因此线圈 L1 呈激磁状态,依据右手定则得知线圈 L1 右侧为 S 极,故转子 反转.当转子 S 极远离霍尔元件时造成磁通密度下降,因此 A,B 端不再产生霍尔电压 电晶体 Q1,Q2 呈 OFF 状态,转子因受惯性作用继续反向旋转.当转子 N 极转至霍尔 元件时,造成霍尔元件 B 端子电压较大,使得电晶体 Q2 导通,则线圈 L2 内有 i2 电流 流通,因此线圈 L2 呈激磁状态,转子再度受磁力作用反转,依照如此程序转子持续转 动.图 3 因为有两组场绕组线圈因此称作二相无刷直流伺服马达,当控制精度要求更高 时,可以增加场绕组线圈数目与霍尔元件数目,因此工业上常使用的四相,五相无刷马 达,即是指此类运用霍尔元件制成的无刷直流伺服马达. 无刷直流伺服马达由於利用霍尔元件感应激磁顺序与时间,因此又称作「电子换相 马达」 ,利用霍尔元件感应激磁顺序与时间可以减少不必要的电能浪费,同时也可以适 时的提供转子转动所需的电磁力,因此大幅提升马达输出扭矩与效率.二,直流马达之特性曲线与选用方式电动机之特性曲线是评估,选用电动机时的一项重要指标,电动机特性曲线通常指 的就是转速-转矩曲线图,直流马达除了转速-转矩曲线图以外通常还有电流-转矩曲线 图.如图4所示为12伏特直流马达特性曲线图,横轴为输出转矩,纵轴则分别为转速, 电流以及效率与输出功率.4.tw/直流电动机简介*1000 R.P.M. 4 3 2 1 0 0 100 200 300 Torque g-cm Speed CurrentAMP. 3Eff. % 40 Eff.Output W 15230 20 10 010 Output 514000100200 300 Torque g-cm400图 4 直流马达特性曲线图 直流马达与其他马达最大的差异在於其"转速-转矩"与"电流-转矩"特性均 为线性关系,因此在一般需要做到转速,转矩控制的场合中,若控制精度不需很高的情 况下,同常以直流马达作为致动器是较为经济的选择. 选用动力电动机时必须考量的因素包含输出负荷大小,马达输出扭力,与转速曲线 特性,同时也要考虑电源形式与运转模式.在选用直流马达时,必须注意它的工作电压, 直流马达电源常见规格为 DC12V 与 DC24V,交流马达则为 AC110V 与 AC220V;另外 还要知道输出扭矩大小(g-cm,kg-cm),以及转速(rpm),当然最好能有马达特性曲线, 如电流转矩图与电流转速图等,以方便作为选用马达时的参考.计算扭力需求时,先计 算欲旋转的物体转动惯量,再参考旋转速度决定减速比,然后决定马达工作扭力值,即 可依照马达特性选择适用型式. 以下便以表格的方式列出电动机之分类与驱动控制方法,可比较在不同的使用条件 下各种电动机的优劣.5.tw/直流电动机简介表1 三相感应马达 驱动讯号 控制方式 交流各种马达比较 直流马达 直流 工业电子 伺服马达 直流/交流 闭回路 /Encoder 步进马达 脉冲 开回路/步级角单相感应马达 交流工业电子/变频器 工业电子/变频器应答时间 优点 缺点 运用场合 高速大转矩 体积庞大 大动力提供 构造简单 需启动器 较小动力提供0.15sec0.2sec构造简单 高速高应答 低价位高精度 出力较小 复杂,价高 失步,噪音 小动力提供 高速高精度 低速高精度三,直流马达之应用与控制实例在「图书馆还书车」设计案例中,将传统书架形式,由人工推动的图书馆还书车, 改良设计成为摩天轮形式之电动车,六只书架平均放置在一转轮上,转轮由电动马达控 制,需要取放书籍时操作者不必移动或蹲下,而是将书架旋转至操作者面前.还书车的 前进,后退也是由电动马达推动. 由於还书车使用的场合是在图书馆书库,为了达到提高还书车的灵活度,在电源供 应方面设计成利用蓄电池供应电源,同时要配合正反转运动模式,因此采用直流马达作 为致动器.此外由於共有六只书架,因此利用一个六段的波段开关,配合六个装置在适 当位置的极限开关,就可指定某一书架旋转至所需位置,同时基於安全上的考虑,当书 架旋转时还书车是无法作前后的运动.并且在还书车前后设有碰撞紧急停止开关.综合 以上的需求,还书车马达的控制电路如图5所示.6.tw/直流电动机简介波段开关LS1 LS2 LS3 LS4 LS5 LS6N.C N.C N.C N.C N.C N.CR1 M 旋转用马达至前进用马达紧急停止开关START 电池 ON/OFFR2图 5 旋转书架定位马达控制电路图 在图 5 中当接通电源与按下起动开关后,继电器 R2 接通,电源依照所选择的波段 开关流入书架旋转马达,同时继电器 R1 也接通,由於 R1 之接点为常闭接点,因此前 进用马达呈断路状态,只有书架旋转马达旋转,当书架旋转至所需位置时压触极限开关 切断马达电源,书架旋转马达停止. 图书馆还书车的另一项功能是以自动前进方式减轻工作人员的负担,因此依照人因 工程的理论数据以及实际的实验的方式求出前进的速度,利用蜗杆蜗轮减速机构将直流 马达输出转速变慢;此外也考虑到书架在全载的状态下作旋转时的速度以及扭力输出, 因此在书架旋转马达上利用两级蜗杆蜗轮减速机构将直流马达输出转速由 1500rpm 减 速成 5rpm,同时输出扭矩也由原本的 4.6kg-cm 增加为 1,364kg-cm.7.tw/。

直流电机保养周期及流程Regular maintenance is essential for prolonging the lifespan and ensuring the efficient operation of a direct current (DC) motor. 直流电机的定期维护对于延长寿命和保证高效运作至关重要。

The maintenance frequency and process may vary depending on the specific usageand environmental conditions. 维护的频率和流程可能会根据具体的使用情况和环境条件而有所不同。

However, a general guideline can be followed to ensure that the DC motor is well-maintained. 然而，可以遵循一般指导原则来确保直流电机得到良好维护。

One of the key aspects of DC motor maintenance is to regularly inspect and clean the motor components. 直流电机维护的关键之一是定期检查和清洁电机零件。

Dust, dirt, and other debris can accumulate on the motor over time, leading to potential performance issues. 时间长了，灰尘、污垢和其他杂物可能会积聚在电机上，导致潜在的性能问题。

Regularly inspecting and cleaning the motor components can help prevent these issues and ensure the motor operates smoothly. 定期检查和清洁电机零件可以帮助预防这些问题，并确保电机运行顺畅。

电机种类性能及特点比较电机是将电能转换为机械能的装置，广泛应用于各个领域，如工业、交通、家电等。

随着科技的进步，电机种类繁多，各具特点。

接下来，我将比较几种常见电机的性能和特点。

1. 直流电机（DC motor）直流电机是最常见的一种电机。

它可以通过调整直流电源的电压和极性来实现转速和转向的控制。

直流电机的优点在于起动扭矩大，适合用于需要快速启动和高起动力矩的设备，如电动车。

然而，直流电机由于存在刷子和换向器等机械部件，容易产生摩擦和磨损，需要定期进行维护。

2. 交流电机（AC motor）交流电机是通过交流电源供电并将交流电能转化为机械能的电机。

与直流电机相比，交流电机结构简单、效率高、可靠性较好。

由于交流电机的转子采用了感应原理，没有机械刷子和换向器，因此摩擦和磨损较少，维护成本较低。

然而，交流电机的启动扭矩较小，适用于负载较轻的设备。

3. 步进电机（Stepper motor）步进电机是一种特殊的交流电机，它按照一定角度进行步进运动。

步进电机的优点在于精确控制和定位，能够准确停止在任何一个位置。

这使得步进电机广泛应用于需要精确控制的设备，如数控机床、3D打印机等。

然而，步进电机通常需要控制器进行驱动，复杂度较高，且在高速运动时会产生振动和噪音。

4. 无刷直流电机（Brushless DC motor）无刷直流电机是直流电机的一种变种，它去除了刷子和换向器，采用了电子换向的方式。

无刷直流电机的优点在于效率高、维护成本低、寿命长。

它还可以根据负载的需求自动调整电机转速，实现智能化控制。

然而，无刷直流电机的价格通常较高，需要较复杂的驱动电路。

综上所述，各种电机各有优劣。

直流电机具有高起动扭矩、可调速、价格较低的优点，但需要定期维护。

交流电机结构简单、效率高、可靠性好，但启动扭矩较小。

步进电机适用于精确控制和定位的设备，但驱动复杂。

无刷直流电机效率高、寿命长，但价格较高，需要复杂的驱动电路。

在选择电机时，需要根据实际需求权衡各种因素。

英文原文+中文翻译（原文：）Introduction to D.C. MachinesD.C. machines are characterized by their versatility. By means of various combinations of shunt-, series-, and separately excited field windings they can be designed to display a wide variety of volt-ampere or speed-torque characteristics for both dynamic and steady state operation. Because of the ease with which they can be controlled, systems of D.C. machines are often used in applications requiring a wide range of motor speeds or precise control of motor output.The essential features of a D.C. machine are shown schematically. The stator has salient poles and is excited by one or more field coils. The air-gap flux distribution created by the field winding is symmetrical about the centerline of the field poles. This is called the field axis or direct axis.As we know, the A.C. voltage generated in each rotating armature coil is converted to D.C. in the external armature terminals by means of a rotating commutator and stationary brushes to which the armature leads are connected. The commutator-brush combination forms a mechanical rectifier, resulting in a D.C. armature voltage as well as an armature m.m.f. Wave then is 90 electrical degrees from the axis of the field poles, i.e. in the quadrature axis. In the schematic representation the brushes are shown in quadrature axis because this is the position of the coils to which they are connected. The armature m.m.f. Wave then is along the brush axis as shown. (The geometrical position of the brushes in an actual machine is approximately 90 electrical degrees from their position in the schematic diagram because of the shape of the end connections to the commutator.)The magnetic torque and the speed voltage appearing at the brushes are independent of the spatial waveform of the flux distribution; for convenience we shall continue to assume a sinusoidal flux-density wave in the air gap. The torque can then be found from the magnetic field viewpoint.The torque can be expressed in terms of the interaction of the direct-axis air-gap flux perpole d φ and space-fundamental component 1Fa of the armature m.m.f.wave. With the brushes in the quadrature axis the angle between these fields is 90 electrical degrees, and its sine equals unity. For a P pole machine2122d P T Fa πφ⎛⎫= ⎪⎝⎭（1-1） In which the minus sign gas been dropped because the positive direction of the torque can be determined from physical reasoning. The space fundamental 1Fa of the sawtooth armature m.m.f.wave is 28π times its peak. Substitution in above equation then gives()2a a a PC T i N m mφπ=• （1-2） Where, a I =current in external armature circuit;a C =total number of conductors in armature winding;m =number of parallel paths through winding. And2a a PC K m π= （1-3） is a constant fixed by the design of the winding.The rectified voltage generated in the armature has already been discussed before for an elementary single-coil armature. The effect of distributing the winding in several slots is shown in figure. In which each of the rectified sine wave is the voltage generated in one of the coils, commutation taking place at the moment when the coil sides are in the neutral zone. The generated voltage as observed from the brushes and is the sum of the rectified voltages of all the coils in series between brushes and is shown by the rippling line labeled a e in figure. With a dozen or so commutator segments per pole, the ripple becomes very small and the average generated voltage observed from the brushes equals the sum of the average values of the rectified coil voltages. The rectified voltage a e between brushes, Known also as the speed voltage, is2a a d m a d m PC e K mφωφωπ== （1-4） where a K is the design constant. The rectified voltage of a distributed winding has thesame average value as that of a concentrated coil. The difference is that the ripple is greatly reduced.From the above equations, with all variable expressed in SI units,a a m e i T ω= （1-5）This equation simply says that the instantaneous power associated with the speed voltage equals the instantaneous mechanical power with the magnetic torque. The direction of power flow being determined by whether the machine is acting as a motor or generator. The direct-axis air-gap flux is produced by the combined m.m.f.f f N i ∑ of the field windings. The flux-m.m.f. Characteristic being the magnetization curve for the particular iron geometry of the machine. In the magnetization curve, it is assumed that the armature –m.m.f. Wave is perpendicular to the field axis. It will be necessary to reexamine this assumption later in this chapter, where the effects of saturation are investigated more thoroughly. Because the armature e.m.f. is proportional to flux times speed, it is usually more convenient to express the magnetization curve in terms of the armature e.m.f. 0a e at a constant speed 0m ω. The voltage a e for a given flux at any other speed m ω is proportional to the speed, i.e.00m a a m e e ωω= （1-6） There is the magnetization curve with only one field winding excited. This curve can easily be obtained by test methods, no knowledge of any design details being required.Over a fairly wide range of excitation the reluctance of the iron is negligible compared with that of the air gap. In this region the flux is linearly proportional to the total m.m.f. of the field windings, the constant of proportionality being the direct-axis air-gap permeance.The outstanding advantages of D.C. machines arise from the wide variety of operating characteristics that can be obtained by selection of the method of excitation of the field windings. The field windings may be separately excited from an external D.C. source, or they may be self-excited; i.e. the machine may supply its own excitation. The method of excitation profoundly influences not only the steady-state characteristics, but also the dynamic behavior of the machine in control systems.The connection diagram of a separately excited generator is given. The required field current is a very small fraction of the rated armature current. A small amount of power in the field circuit may control a relatively large amount of power in the armature circuit; i.e. the generator is a power amplifier. Separately excited generators are often used in feedback control systems when control of the armature voltage over a wide range is required. The field windings of self-excited generators may be supplied in three different ways. The field may be connected in series with the armature, resulting in a series generator. The field may be connected in shunt with the armature, resulting in a shunt generator, or the field may be in two sections, one of which is connected in series and the other in shunt with the armature, resulting in a compound generator. With self-excited generators residual magnetism must be present in the machine iron to get the self-excitation process started.In the typical steady-state volt-ampere characteristics, constant-speed prime movers being assumed. The relation between the steady state generated e.m.f. a E and the terminal voltage t V ist a a a V E I R =- （1-7）where a I is the armature current output and a R is the armature circuit resistance. In a generator,a E is larger than t V and the electromagnetic torque T is a counter torque opposing rotation.The terminal voltage of a separately excited generator decreases slightly with increase in the load current, principally because of the voltage drop in the armature resistance. The field current of a series generator is the same as the load current, so that the air-gap fluxand hence the voltage vary widely with load. As a consequence, series generators are normally connected so that the m.m.f. of the series winding aids that of the shunt winding. The advantage is that through the action of the series winding the flux per pole can increase with load, resulting in a voltage output that is nearly usually contains many turns of relatively small wire. The series winding, wound on the outside, consists of a few turns of comparatively heavy conductor because it must carry the full armature current of the machine. The voltage of both shunt and compound generators can be controlled over reasonable limits by means of rheostats in the shunt field.Any of the methods of excitation used for generators can also be used for motors. In the typical steady-state speed-torque characteristics, it is assumed that motor terminals are supplied from a constant-voltage source. In a motor the relation between the e.m.f. a E generated in the armature and terminal voltage t V ist a a a V E I R =+ （1-8） where a I is now the armature current input. The generated e.m.f. a E is now smaller than the terminal voltage t V , the armature current is in the opposite direction to that in a generator, and the electron magnetic torque is in the direction to sustain rotation of the armature.In shunt and separately excited motors the field flux is nearly constant. Consequently increased torque must be accompanied by a very nearly proportional increase in armature current and hence by a small decrease in counter e.m.f. to allow this increased current through the small armature resistance. Since counter e.m.f. is determined by flux and speed, the speed must drop slightly. Like the squirrel-cage induction motor, the shunt motor is substantially a constant-speed motor having about 5% drop in speed from no load to full load. Starting torque and maximum torque are limited by the armature current that can be commutated successfully.An outstanding advantage of the shunt motor is case of speed control. With a rheostat in the shunt-field circuit, the field current and flux per pole can be varied at will, andvariation of flux causes the inverse variation of speed to maintain counter e.m.f. approximately equal to the impressed terminal voltage. A maximum speed range of about 4 or 5 to I can be obtained by this method. The limitation again being commutating conditions. By variation of the impressed armature voltage, very speed ranges can be obtained.In the series motor, increase in load is accompanied by increase in the armature current and m.m.f. and the stator field flux (provided the iron is not completely saturated). Because flux increase with load, speed must drop in order to maintain the balance between impressed voltage and counter e.m.f. Moreover, the increased in armature current caused by increased torque is varying-speed motor with a markedly drooping speed-load characteristic. For applications requiring heavy torque overloads, this characteristic is particularly advantageous because the corresponding power overloads are held to more reasonable values by the associated speed drops. Very favorable starting characteristics also result from the increase flux with increased armature current.In the compound motor the series field may be connected either cumulatively, so that its m.m.f. adds to that of the shunt field, or differentially, so that it opposes. The differential connection is very rarely used. A cumulatively compounded motor has speed-load characteristic intermediate between those of a shunt and a series motor, the drop of speed with load depending on the relative number of ampere-turns in the shunt and series fields. It does not have disadvantage of very high light-load speed associated with a series motor, but it retains to a considerable degree the advantages of series excitation.The application advantages of D.C. machines lie in the variety of performance characteristics offered by the possibilities of shunt, series and compound excitation. Some of these characteristics have been touched upon briefly in this article. Still greater possibilities exist if additional sets of brushes are added so that other voltages can be obtained from the commutator. Thus the versatility of D.C. machine system and their adaptability to control, both manual and automatic, are their outstanding features.A D.C machines is made up of two basic components:－The stator which is the stationary part of the machine. It consists of the followingelements: a yoke inside a frame; excitation poles and winding; commutating poles (composes) and winding; end shield with ball or sliding bearings; brushes and brush holders; the terminal box.－The rotor which is the moving part of the machine. It is made up of a core mounted on the machine shaft. This core has uniformly spaced slots into which the armature winding is fitted. A commutator, and often a fan, is also located on the machine shaft.The frame is fixed to the floor by means of a bedplate and bolts. On low power machines the frame and yoke are one and the same components, through which the magnetic flux produced by the excitation poles closes. The frame and yoke are built of cast iron or cast steel or sometimes from welded steel plates.In low-power and controlled rectifier-supplied machines the yoke is built up of thin (0.5～1mm) laminated iron sheets. The yoke is usually mounted inside a non-ferromagnetic frame (usually made of aluminum alloys, to keep down the weight). To either side of the frame there are bolted two end shields, which contain the ball or sliding bearings.The (main)excitation poles are built from 0.5～1mm iron sheets held together by riveted bolts. The poles are fixed into the frame by means of bolts. They support the windings carrying the excitation current.On the rotor side, at the end of the pole core is the so-called pole-shoe that is meant to facilitate a given distribution of the magnetic flux through the air gap. The winding is placed inside an insulated frame mounted on the core, and secured by the pole-shoe.The excitation windings are made of insulated round or rectangular conductors, and are connected either in series or in parallel. The windings are liked in such a way that the magnetic flux of one pole crossing the air gap is directed from the pole-shoe towards the armature (North Pole), which the flux of the next pole is directed from the armature to the pole-shoe (South Pole).The commutating poles, like the main poles, consist of a core ending in the pole-shoe and a winding wound round the core. They are located on the symmetry (neutral) axis between two main poles, and bolted on the yoke. Commutating poles are built either ofcast-iron or iron sheets.The windings of the commutating poles are also made from insulated round or rectangular conductors. They are connected either in series or in parallel and carry the machine's main current.The rotor core is built of 0.5～1mm silicon-alloy sheets. The sheets are insulated from one another by a thin film of varnish or by an oxide coating. Both some 0.03～0.05mm thick. The purpose is to ensure a reduction of the eddy currents that arise in the core when it rotates inside the magnetic field. These currents cause energy losses that turn into heat. In solid cores, these losses could become very high, reducing machine efficiency and producing intense heating.The rotor core consists of a few packets of metal sheet. Redial or axial cooling ducts (8～10mm inside) are inserted between the packets to give better cooling. Pressure is exerted to both side of the core by pressing devices foxed on to the shaft. The length of the rotor usually exceeds that of the poles by 2～5mm on either side－the effect being to minimize the variations in magnetic permeability caused by axial armature displacement. The periphery of the rotor is provided with teeth and slots into which the armature winding is inserted.The rotor winding consists either of coils wound directly in the rotor slots by means of specially designed machines or coils already formed. The winding is carefully insulated, and it secured within the slots by means of wedges made of wood or other insulating material.The winding overcharge are bent over and tied to one another with steel wire in order to resist the deformation that could be caused by the centrifugal force.The coil-junctions of the rotor winding are connected to the commutator mounted on the armature shaft. The commutator is cylinder made of small copper. Segments insulated from one another, and also from the clamping elements by a layer of minacity. The ends of the rotor coil are soldered to each segment.On low-power machines, the commutator segments form a single unit, insulated from one another by means of a synthetic resin such as Bakelite.To link the armature winding to fixed machine terminals, a set of carbon brushes slide on the commutator surface by means of brush holders. The brushes contact the commutator segments with a constant pressure ensured by a spring and lever. Clamps mounted on the end shields support the brush holders.The brushes are connected electrically－with the odd-numbered brushes connected to one terminal of the machine and the even-numbered brushes to the other. The brushes are equally spaced round the periphery of the commutator－the number of rows of brushes being equal to the number of excitation poles.附：中文译文直流电机的介绍直流电机的特点是他们的多功用性。

电动机（马达）：motor直流电动机：direct current motor简称DC motor 塑封定子：the mold定子stator转子：rotor铁芯：steel core支架：bracket铭牌：nameplate二维码：Quick Response Code 简称QR code绕组：winding绕组温度：Winding temperature漆包线线径：enamel wire diameter匝数：turns接线方法：connect method转轴：shaft防锈油：anti-rust oil绝缘纸：insulation paperU型挡圈：U type retainer轴承：bearing机壳：housing螺钉：screw印刷基板PCB集成电路integrated circuit 缩写ICIC表面温度the temperature on IC surface：马达电源电压Motor power voltage控制电源电压Control power voltage动作温度范围Case operation temperature速度指令电压Speed control voltage回转脉冲输出Pulse of rotating output端子机能Terminals function绝缘等级Insulating class马达安装姿势Mounting position过电流保护 Over current protect过热保护 Over heating protect电源电压过低保护Over low voltage protect马达运转特性Motor operation characters附件：Attachment符合:comply with递交:Submit提交，检查:inspectionspecification规格书，日企称纳入仕样书安全使用注意事项Matters need attention for safe use。

常用马达介绍范文马达是一种能够将电能转换为机械能的装置，广泛应用于各个领域，包括汽车、船舶、工业生产以及家用电器等。

本文将介绍一些常用的马达类型及其特点。

1. 直流电动机（DC motor）直流电动机是一种最常见的马达类型之一，它将电能转换成机械能。

直流电动机通常由一个旋转的电枢和一个固定的永磁体组成，电枢通过电流和磁场的相互作用来实现转动。

直流电动机具有启动扭矩大、转速范围广、响应速度快等优点，常用于小型家用电器、电动工具和自动化系统等。

2. 交流电动机（AC motor）交流电动机是另一种常见的马达类型，广泛应用于各个领域。

交流电动机以交流电为动力源，通过电磁感应原理将电能转换成机械能。

常用的交流电动机包括异步电动机和同步电动机。

异步电动机结构简单、成本低廉，适用于大多数家用电器和工业设备。

同步电动机转速稳定、效率高，适用于高性能机械设备和发电机组等。

3. 步进电机（Stepper motor）步进电机是一种特殊的电动机，可以将电能转换成离散的、预定的角度运动。

步进电机通过控制电流变化来控制转子转动的步数和方向。

优点是具有很高的定位精度和控制性能，适用于需要精确控制位置和速度的设备，如3D打印机、机器人和电子设备。

4. 无刷直流电动机（Brushless DC motor）无刷直流电动机是一种高效、低噪音、低维护成本的马达类型。

相比于传统的直流电动机，无刷直流电动机不需要使用刷子和换向器，减少了能量损失和机械磨损，提高了效率和寿命。

无刷直流电动机广泛应用于电动汽车、无人机、机器人和工业自动化系统等领域。

5. 脉冲马达（Pulse motor）脉冲马达是一种通过控制电流和电压的脉冲信号来实现马达运动的马达类型。

它可以实现高速、高精度和快速响应的马达运动，适用于自动化设备、精密仪器和机械加工等领域。

常见的脉冲马达包括线性电动机和驱动器、步进电机和直线伺服电机等。

总之，马达是现代工业和家庭生活中不可或缺的设备，常用的马达类型包括直流电动机、交流电动机、步进电机、无刷直流电动机和脉冲马达等。