2024年2月16日发(作者：)

外文文献及翻译--三相异步电动机的几种调速方式

三相异步电动机的几种调速方式

三相异步电动机的转速公式为：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

串级调速方法是将多个电动机串联起来，通过改变每个电动机的转速来达到调速目的。其特点如下：

1、调速范围大，可实现无级调速；

2、效率高，能量损耗小；

3、调速平稳，可用于精密机械；

4、成本高，安装维护较为复杂。

本方法适用于大功率、高精度的调速场合，如钢铁、水泥、矿山等行业。

串级调速是一种调节电动机转速的方法，它通过在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率，从而达到调速的目的。在这种方法中，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，其中晶闸管串级调速是最常用的一种。它的特点是：可以将调速过程中的转差损耗回馈到电网或生产机械上，效率较高；装置容量与调速范围成正比，投资省，适用于调速范围在额定转速７０％－９０％的生产机械上；调速装置故障时可以切换至全速运行，避免停产；但功率因数偏低，谐波影响较大。晶闸管串级调速适合于风机、水泵、轧钢机、矿井提升机、挤压机等生产机械的调速。

绕线式电动机转子串电阻调速方法是另一种调节电动机转速的方法。它通过在绕线式异步电动机转子回路中串入附加电阻，使电动机的转差率加大，从而使电动机在较低的转速下运行。串入的电阻越大，电动机的转速越低。这种方法设备简单，控制方便，但转差功率以发热的形式消耗在电阻上，属有级调速，机械特性较软。

定子调压调速方法是一种通过改变电动机的定子电压来调节电动机转速的方法。当改变电动机的定子电压时，可以得到一组不同的机械特性曲线，从而获得不同转速。由于电动机的转矩与电压平方成正比，因此最大转矩下降很多，其调速范围较小，使一般笼型电动机难以应用。为了扩大调速范围，调压调速应采用转子电阻值大的笼型电动机，如专供调压调速用的力矩电动机，或者在绕线式电动机上串联频敏电阻。为了扩大稳定运行范围，当调速在2：1以上的场合应采用反馈控制以达到自动调节转速目的。调压调速的主要装置是一个能提供电压变化的电源，目前常用的调压方式有串联饱和电抗器、自耦变压器以及晶闸管调压等几种。晶闸管调压方式为最佳。调压调速的特点是：线路简单，易实现自动控制；调压过程中转差

功率以发热形式消耗在转子电阻中，效率较低。调压调速一般适用于100KW以下的生产机械。

电磁调速电动机调速方法是一种通过控制电磁转差离合器来调节电动机转速的方法。它由笼型电动机、电磁转差离合器和直流励磁电源（控制器）三部分组成。直流励磁电源功率较小，通常由单相半波或全波晶闸管整流器组成，改变晶闸管的导通角，可以改变励磁电流的大小。电磁调速电动机调速方法的特点是：控制方便，调速范围广，但设备复杂，成本较高。

XXX: armature。ic pole。XXX with the motor rotor and is

driven by the motor。The ic pole is connected to the load shaft

with a coupling and is called the driven part。When both the

armature and the ic pole are XXX direct current。multiple pairs of

XXX along the surface of the air gap。and the ic flux will pass

through the armature。When the armature rotates with the motor。the relative movement een the armature and the ic pole induces

XXX the eddy currents and the ic flux produces torque。which

drives the rotor with the ic pole to rotate in the same n。but its

speed is always lower than the armature speed is a slip

speed control method。Changing the DC n current of the slip

clutch can change the output torque and speed of the clutch。The

speed control XXX:

device structure and control circuit。reliable n。and

easy maintenance;

speed n and stepless speed n;

harmonic impact on the power grid;

speed loss and low efficiency.

This method is XXX with medium and low power。requiring

XXX and short-term low-speed n.

The speed control method of hydraulic coupling

XXX XXX。XXX。XXX。the fluid in it is driven by the

blade to rotate。Under the n of centrifugal force。it enters the

XXX along the outer ring of the pump XXX。XXX is consistent

with the relative filling amount of the working fluid in the housing。During the working process。changing the filling rate can change

the speed of the turbine wheel of the coupling。achieving XXX

characteristics are:

power n range is large and can meet the needs of

different powers XXX;

structure。reliable n。convenient use and

maintenance。and low cost;

size and large capacity;

ient control and n。easy to achieve automatic

control.

This method is suitable for speed n of fans and water pumps.

Three-XXX:

The formula for the speed of a three-phase asynchronous

motor is N = 60f / p (1-s).

From the above formula。it can be observed that the

frequency of the power supply。motor pole number。and slip can

all be adjusted to change the speed of the motor。However。when

considering the essence of speed。changing the XXX.

In n machines。us methods are used to control the speed of

motors XXX resistance speed control。chopper speed control。cascade control。and the use of ic slip clutches。fluid couplings。clutches。and other speed control devices。Another way to

change the speed of a multi-speed motor is by XXX。XXX.

From a speed perspective。there are two types of methods:

high speed and inefficient methods。High speed methods refer to

those that have no slip losses。such as multi-speed motors。slip

frequency control。and speed recovery methods like cascade

control。On the other hand。XXX speed method result in energy

loss in the rotor circuit and clutch coils。XXX speed method also

leads to energy loss in the oil of the fluid coupling。Generally。the loss increases with the n of the speed range。However。if the

speed range is small。the energy loss is minimal.

le Speed Control Method of Pole Pairs

XXX to control the speed of the red XXX。with no slip loss

and high efficiency。nally。the wiring is simple。easy to control。and affordable.

A level speed is not ideal as it has a large XXX。with the use

of pressure and speed adjustment。along with an ic slip clutch。access to high speed characteristics XXX that does not require

variable speed n。such as metal cutting machine beds。lifting

equipment。fans。water pumps。and more.

The frequency control method XXX power supply frequency。which in turn changes the speed of its synchronous speed。The

main equipment for this method is an XXX variable frequency

power supply。The inverter can be categorized into AC-DC-AC

inverter and AC-AC converter。with the majority of domestic use

being AC-DC-AC inverters。This method boasts high efficiency

and speed without nal loss。a wide range of ns。and a hard。high

accuracy speed range。making it ideal for use with cage XXX.

Technical complexity。high cost。and difficult XXX

methods of speed n。However。there are still effective methods

that can be used in high accuracy and good speed performance

XXX.

One such method is the XXX's slip。thereby achieving speed

control。The added potential is absorbed in series with the n in

power。and can be XXX。

Cascade control can be divided into different types。including Motor Cascade control。mechanical and thyristor

cascade control。and multi-XXX to speed up the process of n in

loss of feedback to the ork or n machinery。making them more

efficient.

The investment required for this method is XXX installed

capacity and speed range。and it is applicable for a speed range of

70% to 90% of the rated speed of n machinery。By using the

Cascade Speed n Method。businesses XXX.

XXX failure caused by high speed。it is mended to switch to

full speed to prevent cut-offs。On the other hand。thyristor

cascade speed control can lead to low power factor and greater

harmonics impact。making it unsuitable for XXX。pumps。rolling mills。mine hoists。XXX.

One effective speed control method for wound rotor motors is

to add resistance in series。XXX。the greater the resistance。the

lower the motor speed。and this method can cause power n in the

form of heat in the resistor。DespiteXXX.

XXX precise control of motor speed and can be used in a

XXXXXX.

When changing the motor。XXX to the square。a significant

decrease in torque occurs。making it challenging to apply small

cage motors in general。To expand the speed range。a larger

rotor resistance value should be used in cage motors。XXX-XXX。feedback control should be adopted when the speed is 2:1 or XXX.

Adjusting pressure and speed is a XXX providing power

supply voltage。One common method is the XXX。which utilizes

devices such as reactors。auto transformers。and XXX。Thyristor Surge is the most effective。The pressure and speed

adjustment circuit is simple and allows for easy automatic control.

However。poor power XXX。XXX。As a result。pressure

and speed XXX 100KW.

XXX speed n is another method for controlling motor speed。XXX。squirrel cage motor。electric slip clutch。and DC n power

supply (Controller)。The DC n power supply is typically small

and composed of single-phase half-wave or full-wave XXX。XXX.

XXX field。The speed control method of this motor is XXX:

voltage n and frequency n.

XXX to the motor。The higher the voltage。the higher the

speed of the motor。This method is simple and easy to implement。but it has a limited speed range and poor speed XXX.

XXX the frequency of the power supply。The higher the

frequency。the higher the speed of the motor。This method has a

wider speed range and better speed XXX.

In n to these two methods。there is also a combined voltage

and frequency n method。which combines the advantages of both

methods to achieve better speed control performance.

Compared with other types of motors。XXX high efficiency。low noise。and good speed control performance。They are XXX

industries。XXX。metallurgy。and chemical industry.

In recent years。with the development of power XXX。the

speed control XXX。The n of new power devices and control

algorithms has XXX。making them XXX.

XXX three parts: the armature。poles。XXX to the active

part of the motor and is driven by it。The armature docks with the

load axis ic XXX.

When the armature poles are at rest and the n windings are for

DC。a number of air gaps on the n。s。of alternating polarity

poles will form along the circumferential surface。and the ic flux

will pass through the armature。When the electric armature rotates

with the drag motor。the XXX。leading the rotor pole to rotate in

the same n but at a speed lower than the electric armature's speed

is a good adjustable speed way。and changing the ic

current of the DCLa clutch device can change the clutch device's

output torque and speed.

XXX speed are that it can adjust the speed through the ic

current of the XXX the ic current。the output torque and speed of

the clutch device can be adjusted。This makes it a good way to

regulate the speed of the motor.

Appliances with a simple structure and control circuit are

XXX。the power ork can cause harmonic effects。leading to lost

speed and low efficiency。This method is suitable for medium and

small power machinery that requires smooth and short n runs.

XXX XXX Method is another n for XXX the speed of the

machinery。It is particularly useful for heavy machinery that

requires a constant speed and torque。The XXX a constant speed

while cing the load on the motor.

To use this method。the XXX een the motor and the load。The coupler consists of two XXX。it drives the impeller。which

in turn drives the fluid。The fluid then drives the other impeller。which is connected to the load。By adjusting the amount of fluid

in the coupler。the speed of the load can be regulated.

Overall。XXX the load on the motor。This method is

particularly XXX that require a constant speed and torque。such

as in the XXX industries.

XXX drive and consists of a pump and XXX case that is filled

with a specific amount of working fluid。When the pump is

rotated。the XXX under the n of centrifugal force。The thrust

from the turbine blades drives the n machinery。and the power

transfer capacity of the hydraulic coupler and the volume of fluid

in the shell are consistent。The filling rate can be changed during

n to adjust the turbine speed。allowing for stepless speed n。This

feature makes the hydraulic coupler suitable for a wide range of

power needs。from 10-XXX.

The hydraulic coupler has a simple structure。reliable

performance。and is easy to XXX at a low cost。It is also small in

size and has a high capacity。nally。it is easy to adjust and can

fulfill automatic control.

Overall。the XXX speed n and its simple structure make it an

excellent choice for a wide range of power needs.

This method XXX the speed of both the fan and water pump。

By adjusting the speed of the fan and water pump。the

temperature of the system can be regulated。

This temperature n can be XXX decreasing the speed of the

fan and water pump。which will in turn affect the flow of air and

water。

XXX temperature n。it is important to monitor the

temperature of the system and adjust the speed of the fan and water

pump accordingly。

nally。it is XXX that the fan and water pump are XXX。

Overall。controlling the speed of the fan and water pump is a

XXX.