电梯结构及原理教案8 电梯拖动系统

1、8 电梯拖动系统lift driving system电梯的电力拖动系统对电梯的起动加速、稳速运行、制动减速起着控制作用。拖动系统的优劣直接影响电梯的起动、制动加减速度、平层精度、乘坐的舒适感等指标。早期的电梯原动机都是直流电动机，在19世纪中叶之前，直流拖动是当时电梯唯一的电力拖动方式，19世纪末，电力系统出现了三相制交流电源，同时又发明了实用的交流感应电动机，因而从20世纪初开始交流电力拖动在电梯上得到了应用。controlling lift start-up speed, smooth operation and deceleration, electrical driving syst

2、em plays a decisive role in such index as start-up, acceleration / deceleration, leveling accuracy and riding comfort. before the middle of 19s century, adopting dc motor, dc driving system was the only mode for lift; by the end of 19s century, with the development of ac inductive motor, ac driving

3、system was applied in lift from the beginning of 20s century. 8-1 拖动系统分类driving system types 目前用于电梯的电力拖动系统有两大类，即：直流电梯拖动系统和交流电梯拖动系统。直流电梯拖动系统通常分为二种：一是用发电机组构成的可控硅励磁的发电机-电动机驱动系统；二是可控硅直接供电的可控硅-电动机系统。currently, electrical driving system is classified into two types, i.e. dc driving system and ac driving s

4、ystem. dc driving system has two types, one is driven by controllable silicon excitation multiple dynamos motor, the other by controllable silicon motor. 交流拖动系统又可分为三种：交流变极调速系统、交流变压调速系统和变频变压调速系统。ac driving system includes three types: ac polar-speed-variable system, ac voltage-speed-variable system a

5、nd frequency-voltage-speed-variable system.8-2 直流拖动系统dc driving system直流电梯速度快、舒适感好、平层精度高。但由于其对电网的影响较大，所以在2m/s速度以下的电梯已不再应用，但目前在2m/s速度以上的电梯仍有应用（包括有齿轮的和无齿轮的）。featuring high running speed, good riding comfort and high leveling accuracy, dc lift has a great influence on electrical network, therefore, lif

6、t with speed of less than 2m/s is not out of use, but lift with speed of more than 2m/s is still in use (including geared and gearless). 直流电动机的转速可由下式表示：dc motor speed is indicated as follows: 8-1？ 式中： where:ua 电机进线端的电压 ua inlet voltage of motor ia 电枢电流 ia armature current ra 电枢电阻 ra armature resista

7、nce rt 外接调整电阻 rt varistor ce 电势常数 ce potential constant 励磁磁通 excitation flux由上式可知，直流电机的转速主要与输入电机的端电压、外接调整电阻及励磁磁通有关，只要改变其中的某个参数，均可改变电机转速。其中改变端电压ua比较理想，因为在不同电压下的特性曲线均是平行的，即在同一电压下负载变化时，其转速变化不大。直流电梯的两种拖动系统都是利用调整电动机端电压ua的方法进行调速。发电机-电动机组是通过调节发电机的励磁改变发电机的输出电压（即电动机的端电压）进行调速，故称可控硅励磁系统。可控硅-电动机系统是利用三相可控硅整流器，把交

8、流电变为可控的直流电，供给直流电动机的调速系统，省去了发电机组，因此降低了能耗和造价，使结构更加紧凑。图8-1为可控硅励磁的发电机-电动机拖动系统示意图；图8-2为可控硅直接供电的电机拖动系统。from the above formula, we learn that dc motor speed is mainly related to inlet voltage of motor, varistor and excitation flux, therefore, changing one of the three factors will alter motor speed. it is

9、preferable to change ua, i.e. inlet voltage of motor, since character curve is parallel under different voltages, i.e. motor speed does not change noticeably under the same voltage when load varies. both two driving systems of dc lift change speed by adjusting ua, i.e. inlet voltage of motor. dynamo

10、-motor changes speed by adjusting excitation of motor to change outlet voltage of dynamo, i.e. inlet voltage of motor, and this process is called silicon excitation system. by means of three-phase controllable rectifier, controllable silicon motor system converts ac to dc, providing speed-adjusting

11、system of dc motor, sparing dynamo, reducing power consumption and cost, making structure more compact. in figure 8-1 is shown controllable silicon excitation dynamo-motor driving system, while in figure8- 2 controllable silicon motor driving system.lge of motor, since ehree facotrs r speed is mainl

12、y related to motor speed of more than 2m/s is still in use ()etwor8-2-1 可控硅励磁的发电机-电动机组拖动系统controllable silicon excitation dynamo motor driving system图8-3为快速直流电梯拖动系统原理图figure 8-3 is a sketch of the mechanism of high-speed dc driving system.给定电源经积分转换变成梯形信号。测速发电机取与电梯速度成正比的电压信号。速度给定信号与测速反馈信号相比较后得到的误差信号，

13、加到具有比例积分的速度调节器进行放大调节，然后输出加到反并联的两组可控硅触发器上，使两组触发器同时得到两个符号相反、大小相等的控制信号，控制两组触发器的输出脉冲同时向相反方向作相等角度的移动，用以控制可控硅整流器的输出电压的大小和极性。可控硅整流器的输出电压控制直流发电机的励磁磁通，使发电机电枢输出电压随之变化，电动机转速随发电机输出电压而变化，最终使速度跟随给定的速度曲线变化，达到速度自动调节的目的。given power is converted to trapezoid signal after integration. tachogenerator selects voltage si

14、gnal in directly proportional to lift speed. comparing given speed signal and feedback signal will produce a error signal, which is added to pi speed controller to be amplified, then the outlet is added to two counter-parallel controllable silicon triggers, which can obtain two control signals that

15、are equal in magnitude but have opposite codes. outlet pulse controlling two triggers moves toward opposite directions simultaneously at equal angle degree, so as to control the outlet voltage and polarity of controllable silicon rectifier. the outlet voltage of controllable silicon rectifier contro

16、ls the excitation flux of dc dynamo, changing dynamo armature outlet voltage and motor speed. consequently, speed will vary according to given speed curve, achieving the goal of speed self-adjusting. 当给定正电压与测速反馈电压相比较使速度调节器输出一个负电压给触发器，使正向组可控硅工作在整流状态，反向组可控硅工作在待逆变状态，供给发电机正的励磁电流，从而输出正电压，电动机正转，电梯上升运行。反之，

17、则电动机反转，电梯下行。after given positive voltage compares with feedback voltage, speed controller will output a negative voltage to trigger, enabling positive controllable silicon to work at rectification state,negativeat ready-to-convert state, providing dynamo with positive excitation current, outputting

18、positive voltage, rotating motor, moving lift upwards; otherwise, rotating motor reversely and moving lift downwards. 图8-4为直流高速电梯拖动系统原理图figure8- 4 is the sketch of mechanism of dc high-speed driving system. 与快速梯相比增加了电流调节器、电流检测、预负载信号和电平检测等环节。电流调节器可以提高系统的动态品质，使电梯起、制动更平稳。外在调节器的同相输入端还加进轿厢的预负载信号，以反映轿厢内的重

19、量，使主回路产生一个预负载力矩，避免抱闸打开瞬间产生溜车。compared with fast-speed lift, high-speed lift is equipped with current controller, current test, pre-load signal and level test. current controller is used to improve systems mobile quality, enabling lift to start up and decelerate more smoothly. output of identical pha

20、se of exterior adjuster is added to pre-load signal of car, so as to reflect load in car, making main circuit produce pre-load torque and preventing car from slipping when the moment brake opens. 8-2-2 可控硅直接供电的直流拖动系统controllable silicon dc driving system 图8-5所示是一种可控硅直接供电的直流快速电梯拖动系统原理图，它主要由两组可控硅取代了传统

21、驱动系统中的直流发电机组。两组可控硅可以进行相位控制，或处于整流或处于逆变状态。当控制电路对给定的速度指令信号与速度反馈信号、电流反馈信号进行比较运算后，就决定了两组可控硅整流装置中哪一组应该投入运行，并根据运算结果，控制可控硅整流装置的输出电压，即曳引电动机的电枢电压，使电梯跟随速度指令信号运行常用的可控硅整流电路是将电源变压器接成三角形-星形，副边有中心抽头。正反向可控硅分别把电源变压器三相的正半波或负半波换成直流电，正向或反向加于直流电动机的电枢端，使电机正转或反转。而电枢端电压的大小变化，则由控制可控硅的脉冲相位移动所决定。figure 8-5 is a sketch of mecha

22、nism of controllable silicon dc driving system for dc high-speed lift. in this driving system, replacing dc dynamo of conventional driving system, two groups of controllable silicon can perform phase control or be in the state of rectification and reverse change. after comparing given speed signal a

23、nd feedback signal, current feedback signal and computing, control circuit will determine which group is to be put into operation, and according to the computing result, control output voltage, i.e. armature voltage of traction machine, enabling lift to run by following speed signal. common controll

24、able silicon rectifier circuit is used to connect power voltage transformer into star-delta, with sideline having central terminal. positive and negative controllable silicon can convert positive semi-wave or negative semi-wave of power voltage transformer to dc, direct or reverse armature side appl

25、ied on dc motor can make motor rotate directly or reversely. armature side voltage magnitude is determined by pulse phase displacement of controllable silicon. 8-3 交流拖动系统ac driving system8-3-1 交流变极调速系统ac variable- polarity-adjusting - speed system由电机学原理可知。三相异步电动机的转速可由下式表示：based on motor mechanism, t

26、he speed of three-phase asynchronous motor is indicated by the following formula:60fn (1s) 8-2 p式中： where:n 电动机转速（r/min）； n motor speed（r/min）；f 电源频率 (hz)； f power frequency (hz)； p 电机定子绕组的极对数； p polarity pair of motor stator winding s 转差率。 s rotation error rate从8-2式可以看出，交流异步电动机的转速是与其极对数成反比的。改变电动机的极

27、对数就可以改变电动机的同步转速，因此，改变电动机的极对数是变速最简单的方法。it is indicated from the formula 8-2 that the speed of ac asynchronous motor is reversely proportional to its polarity pair. the simplest way to change synchronous rotating speed of motor is to change polarity pair of motor. 电梯用交流电动机有单速、双速及三速。单速仅用于速度较低的杂物梯。双速电机的

28、定子绕组一般采用416极或624极，少数也有424极或636极。极数少的绕组称为快速绕组，极数多的绕组成为称为慢速绕组。三速电机的定子绕组一般采用6824极，它比双速电机多3个8极，这一绕组主要用于电梯在减速制动时的附加制动绕组，使减速开始的瞬间具有较好的舒适感，有了8极绕组就可以不要在减速时串入附加的电阻或电抗器。另一种三相交流电动机的极对数为6418极，6极绕组作为起动绕组以限制起动电流，使起动电流小于2.5倍额定电流，4级绕组作为正常稳速运行用，18极绕组作为制动减速和平层停车用。图8-6 交流双速电梯的主驱动系统figure 8-6 sketch of mechanism of mai

29、n drive system of double speed liftac motor used in lift has single-speed, double-speed and triple-speed. single-speed motor is used in low-speed lift. stator windings of double-speed motor usually adopts 4/16 polarity or 6/24 polarity, occasionally, 4/24 polarity or 6/36 polarity is used too. windi

30、ng with fewer polarity is called fast winding, while winding with more polarity slow one. stator winding of triple-speed motor usually adopts 6/8/24 polarity, which has 3 sets of 8 polarity more than double-speed motor and is used as additional winding when lift is decelerating, so that good riding

31、comfort is provided when deceleration begins; besides, this 8-polarity winding can obviate additional resistance or resistor. an alternative triple-speed motor has polarity pair of 6/4/18 polarity, 6-polarity winding is used to restrict start-up current, enabling start-up current less than 2.5 rated

32、 current, 4-polarity winding for normal operation, 18 polarity winding for deceleration and leveling before stop. 图8-6是交流双速电梯的主驱动系统的结构原理图。figure 8-6 is a sketch of mechanism of main drive system of double speed lift. 从图中可以看出电动机为624极。为了限制起动电流，以减小对电网电压波动的影响，起动时，一般按时间原则，串电阻、电抗一级加速或二级加速；减速制动是在慢速绕组中按时图6

33、交流双速电梯的主驱动系统间原则进行二级或三级再生发电制动减速，以慢速绕组进行低速稳定运行直至平层停车。变极调速是一种有级调速，调速范围不大。这种系统大多采用开环控制方式，线路简单，价格低，乘坐舒适感差，一般用于货梯。the figure shows that motor is 6/24 polarity. to restrict start-up current and reduce the influence on voltage fluctuation of electrical network, chronological principle is adopted when start-

34、up, i.e. serial resistance, first stage acceleration or second-stage acceleration of resistance; deceleration occurs according to time principle in slow winding by second stage or third stage, followed by electrical deceleration, to run at low speed and steadily until stop at leveling. speed adjustm

35、ent system by changing polarity can be fulfilled within a limited range, most of which adopts open-loop control, featuring simpler circuit, lower cost, but less satisfactory riding comfort, thus mainly used in cargo lift. 8-3-2 交流调压调速系统 ac variable-voltage-speed system 交流调压调速系统有三种形式，一是电梯运行全过程的调压调速，二

36、是电梯的起动过程和制动过程实现自动调速，三是只在制动过程实现自动调速。如图8-7所示。ac variable voltage speed system has three modes, one functions during the whole operation of lift, another in start-up and deceleration, the third only in deceleration, as shown in figure 8-7. 8-3-2-1电梯运行全过程的调压调速 系统示意图如图8-8所示。此系统电机采用单绕组单速交流异步电动机。电机要求具有较硬的机

37、械特性和恒力矩输出特性，使用于可控硅调压下的非正弦波调速和能耗制动。从示意图可以看出，系统按照基准时间产生完整的速度模型电压，即给定电压（包括起动加速、满速运行，减速制动），另一方面，电梯轿厢的实际速度以输出电压的形式得到检测，该检测电路一般由装在电动机轴上的速度传感器驱动。速度控制装置将这两个电压进行比较，通过主放大器、触发器控制可控硅的触发角，这些可控硅与电梯电动机的主绕组串接，因而就可对电动机的端电压，即电机转矩进行控制。电梯载荷条件有两种类型：正载荷和负载荷。正载荷时，系统控制电动机产生驱动转矩，负载荷时，系统控制电动机产生动态制动转矩。当控制系统给出减速信号后，模型电压按基准时间下降

38、，半波整流直流电连续流入电动机主绕组，以产生能耗制动，直到电机停止为止。in figure 8-8 is shown the voltage and speed adjustment in whole operation of lift. this system adopts single-winding-speed ac asynchronous motor, which should have rigid mechanic characteristic and constant torque output, so as to be used in adjusting the non-sin

39、e wave speed and consuming power under controllable silicon variable voltage. the figure shows the system according to base time produces complete speed module voltage, i.e. given voltage which includes start-up acceleration, full-speed operation and deceleration. on the other hand, the actual speed

40、 of car and output voltage mode are tested by test circuit which is normally driven by the speed sensor mounted on motor shaft. speed controller will compare two voltages, via main amplifier and trigger, controlling trigger angle of controllable silicon. controllable silicon is in serial connection

41、with the main winding of motor, thus enabling to control terminal voltage of motor, i.e. torque of motor. lift load has two modes: positive load and negative load. when positive load is applied, motor will produce driving torque; when negative load does, motor will produce mobile brake torque. when

42、control system gives off deceleration signal, module voltage will decrease according to base time, semi-wave rectification dc flows to main winding of motor, consuming power, until motor stops.8-3-2-2交流双速电梯用可控硅取代起、制动电阻、电抗器，从而控制起、制动电流，实现系统的闭环控制，是交流调压调速的又一种形式。该系统仍采用交流双速电动机，加以速度反馈，运行中不断检测电梯的运行速度是否符合理想的

43、速度曲线要求，以达到起制动舒适，运行平稳的目的。ac double speed lift can achieve closed circuit control by using controllable silicon to replace start-up, brake resistance, impedance, so as to control start-up, brake current and achieve closed circuit control, which is an other form of ac variable-voltage-speed. this syste

44、m still adopts ac double-speed motor with speed feedback, which keeps on inspecting if lift speed meets speed curve required, so as to achieve the aim of comfortable riding and smooth running.8-3-2-3按电梯的制动方式又可分为能耗制动型、涡流制动器型和反接制动型。based on brake modes, there are power consuming brake, turbine brake a

45、nd reversely-connected. 图8-9为能耗制动交流调速电梯主驱动系统原理图，这种系统采用可控硅调压调速再加直流能耗制动组成。通常失电后对慢速绕组中的两相绕组通以直流电，在定子内形成一固定的磁场，与转子电流相互作用而产生相应的制动力矩，制动力矩的大小与定子的磁化力及电机转速有关。figure8-9 is the sketch of mechanism of power consuming ac variable-speed main driving system. this system adopts controllable silicon variable voltage

46、 speed with dc power consuming brake. normally, after power-off, dc is provided for 2-phase winding of slow-speed winding, producing a fixed field in stator, interacting with stator current to produce corresponding brake torque, whose magnitude is related to stator magnetic force. 图8-10 为带涡流制动控制的交流调

47、速系统。涡流制动器通常由电枢和定子两部分组成。电枢和异步电动机的转子相似，其结构可以是笼型，也可以是简单的实心转子。定子绕组是由直流电流励磁。涡流制动器或与主电机共为一体，或与主电机分离，但两者的转子是同轴连接的。因而它具有可调节制动转矩的特性。in figure8- 10 is shown ac variable-speed system with turbine brake. turbine brake is usually composed of armature and stator. similar to rotator of asynchronous motor, armature

48、 is cage like or simple substantial rotator. stator winding is excited by dc. turbine brake or main motor is combined into one or separated from main motor, but both rotators are connected to the same shaft, therefore, it is characteristic of adjustable brake torque. 图10 带涡流制动控制的交流调速系统图8-11为反接制动控制的交

49、流调速系统反接制动也是电梯的一种制动调速方法。电梯在减速时，把定子绕组中的两相交叉改变其相序，使定子磁场的旋转方向改变。而转子的转向仍未改变，即电机转子逆磁场旋转方向运转，产生制动力矩，使转速逐渐降低。当转速下降到零时，需立即切断电机电源，抱闸制动，否则电机就自动反转。in figure 8-11 is shown the ac adjusting system of reversely connected brake.reversely connected brake is an alternative adjusting of brake. when lift is deceleratin

50、g, rotating direction of stator field can be changed by changing two-phase cross of stator winding, while rotating direction of stator remains unchanged, i.e. motor stator rotates reversely against field, producing brake torque, reducing velocity. when velocity reaches zero, power should be cut off

51、immediately and make brake engage, otherwise, motor will rotate inversely automatically.8-3-3 交流变频变压调速系统（vvvf）ac variable-frequency-voltage adjusting speed system (vvvf)目前交流变频变压调速的快速和高速电梯已普遍应用，它的各方面技术要求和性能指标均比交流双速和交流调压调速优越。由于交流变频变压调速的技术日趋成熟和完善，工艺先进而简明，故障率低，价格便宜。故当今的电梯技术和电梯市场，已逐步由vvvf系统的电梯所代替。at the

52、present, widely used is fast and high speed lift featuring ac variable-frequency-voltage adjusting speed, which is more advantageous than ac double speed and ac adjusting voltage speed ones in technical data and performance. with ac variable frequency voltage adjusting speed technology development a

53、nd improvement as well as simpler operation, less failure and lower cost, lift with vvvf system has come to replace double-speed and ac adjusting voltage speed systems. 8-3-3-1 变频器frequency inverter 从电机学可知，对于交流异步电动机有公式8-2。from motor mechanics comes the following formula 8-2 concerning ac asynchronou

54、s motor。从8-2式中可以看出，除了改变极对数能改变交流异步电动机的转速外，还可改变施加于电动机端的电源频率f来改变其转速。如能连续自动的改变频率f，则可获得与电动机本身所固有的机械特性（在额定频率50hz时）相平行的一簇机械特性。这样电梯无论在什么负载和速度下，均可有电动机固有机械特性那样的特性硬度。基于这一理论，各种类型的变频器应运而生。而使用变频器进行调速的电梯称为vvvf型电梯。from the above formula 8-2, we learn speed of ac asynchronous motor can be changed either by changing

55、polarity pair or power frequency “f “ imposed on motor. if frequency can be changed continuously and automatically, it is possible to obtain s cluster of mechanic characteristic in parallel with intrinsic mechanic property of motor when rated frequency is 50hz. therefore, whatever load and speed is

56、lift running at, it can have characteristic rigidity as mechanic property of motor. according to this theory, various frequency inverters come into being, and lift that adjusts speed by using inverter is called vvvf lift. 变频器一般采用的是交直交工作原理，即先将三相交流电源电压整流得到幅值可变的直流电压，然后经开关元器件（大功率晶体管或igbt）轮流切换导通，既可获得幅值和频

57、率均可变化的交流输出电压，其幅值由整流器输出的直流电压所决定，其频率由逆变器的开关元件的切换频率所决定。为了提高电网的功率因数，一般采用带有脉宽调制（简称pwm）功能的逆变器来调频、调压。frequency inverter normally adopts ac-dc-ac mechanism, i.e. rectified, 3-phase ac voltage converts to dc with variable amplitude, via switch components (heavy hp transistor or igbt) alternatively switching and connecting, to obtain ac output voltage with variable amplitude and frequency; amplitude