电机学英文文献翻译.docx

1、电机学英文文献翻译电机学英文文献翻译The three-phase induction motor speed control methodThree-phase asynchronous motor speed formula: N = 60f / p (1-s) Can be seen from the above formula, change the power supply frequency f, motor pole number p and the slip s may be too much to change the speed of purpose. From the s

2、peed of the essence of view, is simply a different way to change speed synchronous AC motor does not change the sync transfer speed or two.Widespread use in production machines without changing the synchronous speed of motor speed control method Wound Rotor Series Resistance Speed, chopper speed con

3、trol, cascade control, and application of electromagnetic slip clutch, fluid couplings, clutches and other film speed. Change the synchronous speed of change on the number of stator pole multi-speed motor to change the stator voltage and frequency to frequency conversion with no change to the motor

4、speed and so on.Energy from the speed point of view when, with high speed method and inefficient methods of two kinds of speed: high speed when the slip refers to the same, so no slip losses, such as multi-speed motors, Slip frequency control and loss can speed recovery methods (such as cascade cont

5、rol, etc.). A deteriorating loss of speed control methods are inefficient speed, such as series resistance of the rotor speed method, the energy loss in the rotor circuit on; Electromagnetic Clutch The speed method, the energy loss in the clutch coils; fluid coupling speed, energy loss in the fluid

6、coupling of the oil. General deterioration in loss increased with the expansion speed range, if not speed range, the energy loss is minimal.1, variable speed control method of pole pairsThis speed is then used to change the stator winding way to change the red cage motor stator pole pairs to achieve

7、 speed control purposes, the following featuresWith hard mechanical properties, good stability;No slip loss, high efficiency; Wiring simple, easy to control, low price;A level speed, differential large, can not get smooth speed control;With pressure and speed adjustment, with the use of electromagne

8、tic slip clutch, smooth and efficient access to high speed characteristics.This method is suitable for the production does not require variable speed machinery, such as metal cutting machine Bed , Lift , Lifting equipment, Fans Water Pump And so on.2, Frequency Control Method Frequency control is to

9、 change the motor stator Power supply Frequency, thus changing the speed of its synchronous speed method. Frequency control system main equipment is to provide variable frequency power supply Inverter , Inverter can be divided into AC - DC - AC inverter and AC - AC converter two categories, most of

10、the current domestic use of AC - DC - AC inverter. Its characteristicsHigh efficiency, speed the process without additional loss;Wide range of applications, can be used for cage induction motor;Speed range, features a hard, high accuracy;Technical complexity, high cost, difficult maintenance and ove

11、rhaul.This method is suitable for the high accuracy, good speed performance occasions. 3, cascade control method Cascade control is wound into the rotor circuit in the series of additional potential can be adjusted to change the motors slip, to achieve speed control purposes. Most of the deteriorati

12、on in power to be in series with the added potential absorbed, re-use generate additional devices to absorb the deterioration in power to return power to use or conversion of energy. Slip-power absorption under way, cascade control can be divided into Motor Cascade control, mechanical and thyristor

13、cascade control cascade control, and multi-use cascade control thyristor, characterized byCan speed the process of deterioration in loss of feedback to the network or production machinery, more efficient; Installed capacity and speed range in direct proportion to investment, applicable speed range 7

14、0% -90% rated speed of production machinery; peed device failure can switch to full speed, to avoid the cut-off; Thyristor cascade speed low power factor, harmonics greater impact. This method is suitable for fans, pumps and rolling mills, mine hoist, extrusion machines. 4, wound rotor motor speed c

15、ontrol method of Series ResistanceWound Rotor Motor additional resistance in series, so that the motor slip up, motor running at low speed. The greater the resistance in series, the motor speed is lower. This method is simple, easy to control, but deteriorate the power consumption in the form of hea

16、t in the resistor. Is a class speed, soft mechanical properties.5, the stator pressure and speed adjustment methodStator voltage when changing the motor, you can get a different set of mechanical properties of curves, which were different speeds. Since the motor torque and voltage proportional to th

17、e square, the largest decline in a lot of torque, speed range of its small cage motors in general and difficult to apply. In order to expand the speed range, pressure and speed adjustment should be larger rotor resistance value cage motors, such as dedicated voltage regulator with speed torque motor

18、, or series wound motor frequency sensitive resistors. In order to expand the range of stable operation, when the speed of 2:1 or more occasions in the feedback control should be adopted to achieve the purpose of automatic adjustment of speed.Pressure and speed adjustment is a key device to provide

19、power supply voltage, the current way of a tandem common saturation voltage regulator Reactor , Auto Transformer And several other Thyristor Surge. Thyristor Surge is the best way. Adjusting Speed featuresPressure and speed adjustment circuit is simple, easy to realize automatic control; Poor power

20、surge process to heat transfer in the rotor resistance in the form of consumption, low efficiency.Pressure and speed adjustment generally applies to 100KW below production machinery.6. electromagnetic speed regulating motor speed control method of electromagnetic speed regulating electric motor squi

21、rrel cage motor, electric slip clutch and DC excitation power supply (Controller) consists of three parts. DC excitation power small, usually consisting of single phase half-wave or full wave rectifiers thyristors composition, change thyristor conduction angle, you can change the magnetizing current

22、 size. Electromagnetic slip clutch armature, poles and excitation windings composed of three parts. Armature and the latter has no mechanical contact, are free to rotate. Armature motor coaxial connection active part, driven by motors; docking with the load axis magnetic pole coupling from the movin

23、g parts. When the armature poles are at rest, such as excitation windings for DC, along the circumferential surface will form a number of air gap on the n, s, of alternating polarity poles, the magnetic flux through the armature. Dang electric armature with drag motor rotating Shi, due to electric a

24、rmature and pole between relative movement, and makes electric armature induction produced Eddy, this Eddy and magnetic pass mutual role produced go moments, led has pole of rotor by same direction rotating, but its speed constant below electric armature of speed N1, this is a go difference adjustab

25、le speed way, changes go difference clutch device of DC Lai magnetic current, will can change clutch device of output go moments and speed. Characteristics of electromagnetic speed regulating motor speed: appliances, structure and control circuit is simple, reliable operation, easy maintenance; spee

26、d and smooth, stepless speed regulationthe power network harmonic effects; lost speed, low efficiency. This method applies to medium and small power, requires low speed when the smooth, short run production machinery.7. the hydraulic coupler speed regulating hydraulic Coupler is a device for hydraul

27、ic drive, is made up of the pump and turbine, they collectively work wheels, placed in a sealed case. Shell filled with a certain amount of working fluid, when pump is impulse driven by rotation, in which liquid propelled by blades which rotate, and under the action of centrifugal force along the ou

28、ter wheels when entering the turbine pump, to thrust to the turbine blades on the same turn, make it drive production machinery running. Power transfer capacity of the hydraulic coupler and shell filled with fluid volume sizes are consistent. In the course of work, changing the filling rate can chan

29、ge the coupler of turbine speed, stepless speed regulation, characterized by: power scope, can meet the needs of from a couple of different power 10-kilowatt to shuqianqian; simple structure, reliable performance, easy to operation and maintenance, and low cost;small size, capacity; easy to adjust,

30、easy to fulfill automatic control. This method applies to the speed of the fan and water pump.三相异步电动机的几种调速方式三相异步电动机转速公式为： n=60f/p(1-s)从上式可见，改变供电频率f、电动机的极对数p及转差率s均可太到改变转速的目的。从调速的本质来看，不同的调速方式无非是改变交流电动机的同步转速或不改变同步转两种。在生产机械中广泛使用不改变同步转速的调速方法有绕线式电动机的转子串电阻调速、斩波调速、串级调速以及应用电磁转差离合器、液力偶合器、油膜离合器等调速。改变同步转速的有改变定子

31、极对数的多速电动机，改变定子电压、频率的变频调速有能无换向电动机调速等。从调速时的能耗观点来看，有高效调速方法与低效调速方法两种：高效调速指时转差率不变，因此无转差损耗，如多速电动机、变频调速以及能将转差损耗回收的调速方法（如串级调速等）。有转差损耗的调速方法属低效调速，如转子串电阻调速方法，能量就损耗在转子回路中；电磁离合器的调速方法，能量损耗在离合器线圈中；液力偶合器调速，能量损耗在液力偶合器的油中。一般来说转差损耗随调速范围扩大而增加，如果调速范围不大，能量损耗是很小的。一、变极对数调速方法这种调速方法是用改变定子绕组的接红方式来改变笼型电动机定子极对数达到调速目的，特点如下：1、具有较

32、硬的机械特性，稳定性良好；2、无转差损耗，效率高；3、接线简单、控制方便、价格低；4、有级调速，级差较大，不能获得平滑调速；5、可以与调压调速、电磁转差离合器配合使用，获得较高效率的平滑调速特性。本方法适用于不需要无级调速的生产机械，如金属切削机床、升降机、起重设备、风机、水泵等。二、变频调速方法变频调速是改变电动机定子电源的频率，从而改变其同步转速的调速方法。变频调速系统主要设备是提供变频电源的变频器，变频器可分成交流直流交流变频器和交流交流变频器两大类，目前国内大都使用交直交变频器。其特点：1、效率高，调速过程中没有附加损耗2、应用范围广，可用于笼型异步电动机3、调速范围大，特性硬，精度高4、技术复杂，造价高，维护检修困难。本方法适用于要求精度高、调速性能较好场合。三、串级调速方法串级调速是指绕线式电动机转子回路中串入可调节的附加电势来改变电动机的转差，达到调速的目的。大部分转差功率被串入的附加电势所吸收，再利用产生附加的装置，把吸收的转差功率返回电网或转换能量加以利用。根据转差功率吸收利用方式，串级调速可分为电机串级调速、机械串级调速及晶闸管串级调速形式，多采用晶闸管串级调速，其特点为：1、可将调速过程中的转差损耗