Asynchronous motor with combined windings. Energy efficient electric motors Energy efficient electric motors

An economic crisis is sweeping across the world today. One of its causes is the energy crisis. Therefore, today the issue of energy saving is very acute. This topic is especially relevant for Russia and Ukraine, where the cost of electricity per unit of production is 5 times higher than in developed European countries. Reducing the consumption of electricity by enterprises of the fuel and energy complex of Ukraine and Russia is the main task of science, the electrical and electronic industries of these countries. More than 60% of the electricity used in enterprises is accounted for by the electric drive. If we take into account that its efficiency is no more than 69%, then only using energy-saving motors can save more than 120 GW / h of electricity per year, which will amount to more than 240 million rubles from 100 thousand electric motors. If we add here the savings of reducing the installed capacity, we will get more than 10 billion rubles.

If these figures are converted into fuel savings, then the savings are 360-430 million tons of standard fuel per year. This figure corresponds to 30% of all domestic energy consumption in the country. If we add here the energy savings due to the use of a frequency-controlled drive, then this number rises to 40%. Russia has already signed an order to reduce energy intensity by 40% by 2020.

Since September 2008, the IEC 60034-30 standard has been adopted in Europe, where all motors are divided into 4 energy efficiency classes:

• standard (ie1);
• high (ie2);
• highest, PREMIUM (ie3);
• ultra-high, Supper-Premium (ie4).

Today, all major European manufacturers have started producing energy-efficient motors. Moreover, all American manufacturers are replacing "high" energy efficiency motors with "higher", PREMIUM energy efficiency motors.

• The development of an energy-efficient series of general-purpose motors is also carried out in our countries. There are three challenges for manufacturers to improve energy efficiency;
• Development and development of new energy-efficient models of low-voltage asynchronous motors that correspond to the world level of development of the electrical and engineering industries for use in the domestic and international markets;
• Increasing the efficiency values ​​of newly created energy efficient motors according to the IEC 60034-30 energy efficiency standard, while increasing the consumption of material used in class ie2 motors by no more than 10 percent;
• A saving of active materials should be achieved, corresponding to a saving of 10 kW of power per 1 kg of winding copper. As a result of the use of energy-efficient models of electric motors, the number of die equipment is reduced by 10-15%;

The development and implementation of high efficiency electric motors eliminates the problem of the need to increase the installed capacity of electrical equipment and reduce emissions of harmful substances into the atmosphere. In addition, reducing the amount of noise and vibration, increasing the reliability of the entire electric drive is an indisputable argument in favor of using energy-efficient asynchronous electric motors;

Description of 7A Series Energy Efficient Induction Motors

Asynchronous squirrel-cage motors of the 7A series (7AVE) belong to three-phase asynchronous electric motors, a general industrial series with a squirrel-cage rotor. These motors have already been adapted for use in variable frequency drive circuits. They have an efficiency of 2-4% higher than that of analogues made in Russia (EFFI). They are produced with a standard range of rotation axis: from 80 to 355 mm, designed for power from 1 to 500 kW. The industry has mastered engines with standard speeds: 1000, 1500, 3000 rpm and voltages: 220/380, 380/660. The motors are designed with a degree of protection corresponding to IP54 and insulation class F. Permissible overheating corresponds to class B.

Benefits of using 7A series asynchronous motors

The advantages of using asynchronous motors of the 7A series include their high efficiency. Energy savings with installed power P set = 10,000 kW Energy savings can save up to 700 thousand dollars / year. Another advantage of such motors is their high reliability and service life, in addition, they have a lower noise level by about 2-3 times in relation to the motors of the previous series. They allow you to produce a larger number of on-off and more maintainable. The motors can operate with mains fluctuations up to 10% in voltage.

Design features

The 7A series motors use a new type of winding that can be wound on old generation winding equipment. In the manufacture of engines of this series, new impregnating varnishes are used, which provide higher carburization and high thermal conductivity. Significantly increased the efficiency of the use of magnetic materials. During 2009, dimensions 160 and 180 were mastered, and during 2010-2011. dimensions of 280, 132, 200, 225, 250, 112, 315, 355 mm were mastered.

An excursion into history. The origin of the problem of energy saving

The problem of saving the energy resources of the planet was identified in the second half of the 20th century. So in the 70s of the last century, an energy crisis broke out all over the world. Oil prices increased 14.5 times from 1972 to 1981. And although most of the difficult moments of that time were overcome, the problem of saving the global fuel and energy complex received the status of a global especially significant problem, and every year more and more attention is paid to this issue.

Energy saving today

Due to technological development, there is a rapid increase in energy consumption around the world. In order for the planet's resources to be enough for humanity in the future, people are looking for various ways and solutions: alternative natural energy sources (wind, water, solar panels) are used, environmentally friendly technologies for generating energy by processing garbage and various household wastes have been invented, technological equipment is being modernized from year to year in order to reduce the power consumption of this equipment.

The energy efficiency of equipment is a private concern for each of us. After all, the amount in the monthly electricity bill directly depends on it. In Europe, electricity is much more expensive than in Russia, so every European tries to select high-tech equipment that consumes as little energy as possible. In our country, a much smaller number of people think about this, but in our country, the use of energy-saving technologies can also have a beneficial effect on the “thickness of your wallet”. Paying monthly electricity bills, we do not think that the annual operating costs are an impressive amount that could be spent on other purposes.

Energy efficiency in ventilation

The main source of electricity consumption in ventilation installations, as you might guess, is the fan, and more specifically the electric motor (or motor), due to which the fan impeller rotates.

Energy efficiency class IE

The European DIN motor standards are based on the IEC (International Electrotechnical Commission) equipment energy efficiency classification standard.

According to international standards, four energy efficiency classes of motors IE1, IE2, IE3 and IE4 have been developed to date. IE means "International Energy Efficiency Class" - an international energy efficiency class

• IE1 standard energy efficiency class.
• IE2 high energy efficiency class.
• IE3 ultra-high energy efficiency class.
• IE4 is the highest energy efficiency class.

Below are the efficiency curves of the motor corresponding to the energy efficiency class versus the rated power.

Starting January 1, 2017, all European motor manufacturers, in accordance with the adopted directive, will produce electric motors with an energy efficiency class of at least IE3

Selecting the energy efficiency of motors when selecting installations in the QC Ventilazione program

TM QuattroClima offers ventilation units with asynchronous motors of IE2 and IE3 classes, as well as premium EC motors IE4.

The fan type is selected by pressing the left mouse button on the "Fan" tab.

Direct drive centrifugal fan - asynchronous motor (IE2 standard).

Direct drive centrifugal fan with EC motor complies with IE4 class.

You can choose the desired energy efficiency class of an asynchronous motor here, just below.

From theory to practice

For clarity, let's look at an example. We calculate a standard air handling unit with a flow rate of 20,000 m3/h and a free pressure of 500 Pa in three options:

1) With asynchronous motor class IE2

2) With IE3 asynchronous motor

3) With EC motor class IE4

And then we compare the results.

Installation with IE2 asynchronous motor

Installation with IE3 asynchronous motor

Installation with EC motor class IE4

In this case, the program selected a section of two EC fans.

Now let's compare the results.

The power consumption of an IE3 motor is 0.18 kW less than that of an IE2 motor. And the power difference between two EC motors and an IE2 motor is already 1.16 kW.

In the case of similar calculations for supply and exhaust ventilation high-flow ventilation units, the difference in the power consumption of IE2 and IE3 motors can reach 25-30%. And if dozens of installations are used at the facility, then the energy consumption of ventilation can be reduced by an order of magnitude and, thanks to this, save hundreds of thousands, or even millions of rubles.

In the following articles, we will talk about other ways to reduce the power consumption of electric motors when selecting ventilation units in the QC Ventilazione program. Earlier, we talked about improving the energy efficiency of low-flow ventilation units with rotary heat exchangers. You can read the article.

The question of creating energy-saving electric motors arose simultaneously with the invention of the electric machines themselves. At the 1891 International Electrical Exhibition in Frankfurt am Main, Charles Brown (later to found ABB) showed a synchronous three-phase generator of his own production, whose efficiency exceeded 95%. An asynchronous three-phase motor presented by Mikhail Dolivo-Dobrovolsky showed an efficiency of 95%. Since then, the efficiency of a three-phase asynchronous motor has been improved by only one to two percent.

The most acute interest in energy-efficient engines arose in the late 1970s during the world's oil energy crisis. It turned out that saving one ton of standard fuel is many times cheaper than producing it. During the crisis, investments in energy conservation increased many times over. Many countries began to allocate special grants for energy saving programs.

After analyzing the problem of energy saving, it turned out that more than half of the electricity generated in the world is consumed by electric motors. Therefore, all the leading electrical companies in the world are working on their improvement.

What are energy saving motors?

These are electric motors whose efficiency is 1-10% higher than that of standard motors. In large energy-saving motors, the difference in efficiency values ​​is 1–2%, and in motors of small and medium power, this difference is already 7–10%.

Efficiency of Siemens electric motors

The increase in efficiency in energy-saving engines is achieved due to:

• increasing the share of active materials - copper and steel;
• the use of thinner and higher quality electrical steel;
• the use of copper instead of aluminum in rotor windings;
• reducing the air gap in the stator using precision process equipment;
• optimization of the shape of the tooth zone of the magnetic circuit and the design of the windings;
• use of bearings of a higher class;
• special design of the fan;

According to statistics, the price of the entire engine is less than 2% of the total life cycle costs. For example, if an engine runs 4,000 hours a year for 10 years, then electricity accounts for approximately 97% of all life cycle costs. Another one percent is for installation and maintenance. Therefore, an increase in the efficiency of an average power engine by 2% will make it possible to recoup the increase in the cost of an energy-saving engine in 3 years, depending on the operating mode. Practical experience and calculations show that the increase in the cost of an energy-saving motor pays off due to the saved electricity when operating in S1 mode for a year and a half (with an annual operating time of 7000 hours).

In the general case, the transition to the use of an energy-saving engine allows:

• increase engine efficiency by 1–10%;
• improve the reliability of its work;
• reduce downtime;
• reduce maintenance costs;
• increase the resistance of the engine to thermal overloads;
• increase the overload capacity;
• increase the engine's resistance to deterioration in operating conditions;
• reduced and overvoltage, distortion of the shape of the voltage curve, phase imbalance, etc.;
• improve power factor;
• reduce the noise level;
• increase engine speed by reducing slip;

The negative property of electric motors with increased efficiency compared to conventional ones are:

• 10 - 30% higher cost;
• slightly more mass;
• higher starting current.

In some cases, the use of an energy efficient motor is inappropriate:

• when the engine is operated for a short time (less than 1-2 thousand hours / year), the introduction of an energy-efficient engine may not make a significant contribution to energy saving;
• when the engine is running in modes with frequent starts, since the saved electricity will be spent on a higher value of the starting current;
• when the engine is running, it works with underload, due to a decrease in efficiency when operating at a load below the nominal one.

The amount of energy savings resulting from the introduction of an energy efficient motor may be negligible compared to the potential of a variable speed drive. Each additional percentage of efficiency requires an increase in the mass of active materials by 3-6%. In this case, the moment of inertia of the rotor increases by 20–50%. Therefore, high-performance engines are inferior to conventional ones in terms of dynamic performance, if this requirement is not specifically taken into account during their development.

When choosing in favor of an energy efficient motor, it is necessary to carefully approach the issue of price. According to analysts' forecasts, copper will rise in price much faster than steel. Therefore, where it is possible to use the so-called steel engines (with a smaller groove area), it is better to use them. Such motors have a lower cost due to copper savings. For the same reasons, it is necessary to treat energy-saving permanent magnet motors. If you have to look for a replacement for such an engine in the future. it may turn out that its price will be too high, and its replacement with an energy-saving engine of a general industrial design will be difficult due to a mismatch in dimensions. According to experts, permanent magnets made of rare earth materials will rise in price more and faster than copper, which will lead to a significant rise in the cost of such motors. Although such motors with the highest energy efficiency class are quite compact, their introduction into industry is limited by the fact that permanent magnets are now in demand in other industries than the general industry, and, according to experts, they will be used in the production of special equipment for which they spare no money.

For about five years, the NPO St. Petersburg Electrotechnical Company (SPBEK) has been persistently collecting implemented rationalization proposals, innovations, and developments from enterprises, institutes, research centers of the former Soviet Union.

Another innovation applicable in Russian realities is associated with the name of Dmitry Alexandrovich Duyunov, who is engaged in the problem of increasing energy efficiency of asynchronous motors:

"In Russia, according to various estimates, asynchronous motors account for from 47 to 53% of the consumption of all generated electricity. In industry, on average, 60%, in cold water systems up to 80%. They carry out almost all technological processes associated with movement and cover all spheres of human life.In each apartment there are more asynchronous motors than residents.Earlier, since there was no task of saving energy resources, when designing equipment, they tried to "keep it safe" and used motors with a power exceeding the calculated one.Energy saving in the design faded into the background , and such a concept as energy efficiency was not so relevant. The industry of Russia did not design and produce energy-efficient engines. The transition to a market economy has dramatically changed the situation. Today, saving a unit of energy resources, for example, 1 ton of fuel in conventional terms, is half the price of extracting it.

Energy-efficient motors (EMs) are asynchronous EMs with a squirrel-cage rotor, in which, due to an increase in the mass of active materials, their quality, as well as due to special design techniques, it was possible to increase by 1-2% (powerful motors) or by 4-5% ( small engines) nominal efficiency with some increase in the price of the engine. This approach can be useful if the load changes little, speed control is not required, and the motor is properly selected. With the advent of motors with combined windings "Slavyanka" it is possible to significantly improve their parameters without increasing their price. Due to the improved mechanical characteristics and higher energy performance, it became possible not only to save from 30 to 50% of energy consumption for the same useful work, but also to create an adjustable drive with unique characteristics that has no analogues in the world.

Unlike standard motors with combined windings, they have a higher torque ratio, have an efficiency and power factor close to the nominal value in a wide range of loads. This allows you to increase the average load on the engine up to 0.8 and improve the performance of the equipment serviced by the drive.

Compared to the known methods for improving the energy efficiency of an asynchronous drive, the novelty of our approach lies in changing the fundamental design principle of classical motor windings. The scientific novelty lies in the fact that new principles have been formulated for designing motor windings, as well as for choosing the optimal ratios of the numbers of rotor and stator slots. Based on them, industrial designs and schemes of single-layer and double-layer combined windings have been developed, both for manual and automatic laying of windings on standard equipment. A number of RF patents have been obtained for technical solutions.

The essence of the development follows from the fact that, depending on the scheme for connecting a three-phase load to a three-phase network (star or triangle), two systems of currents can be obtained, forming an angle of 30 electrical degrees between the vectors. Accordingly, it is possible to connect an electric motor to a three-phase network that does not have a three-phase winding, but a six-phase one. In this case, part of the winding must be included in the star, and part in the triangle and the resulting vectors of the poles of the same phases of the star and the triangle must form an angle of 30 electrical degrees with each other. The combination of two circuits in one winding makes it possible to improve the shape of the field in the working gap of the engine and, as a result, significantly improve the main characteristics of the engine.

Compared to the known ones, a frequency-controlled drive can be made on the basis of new motors with combined windings with an increased frequency of the supply voltage. This is achieved due to lower losses in the steel of the motor magnetic circuit. As a result, the cost of such a drive is significantly lower than when using standard motors, in particular, noise and vibration are significantly reduced.”

UDK 621.313.333:658.562

ENERGY EFFICIENT ASYNCHRONOUS MOTORS FOR A REGULATED ELECTRIC DRIVE

O.O. Muravleva

Tomsk Polytechnic University E-mail: [email protected]

The possibility of creating energy-efficient asynchronous motors without changing the cross-section for adjustable electric drives is considered, which makes it possible to ensure real energy saving. The ways of ensuring energy saving through the use of high-power asynchronous motors in pumping units in the sphere of housing and communal services are shown. The economic calculations carried out and the analysis of the results show the economic efficiency of using increased power engines, despite the increase in the cost of the engine itself.

Introduction

In accordance with the Energy Strategy for the period up to 2020, the highest priority of the state energy policy is to increase the energy efficiency of industry. The efficiency of the Russian economy is significantly reduced due to its high energy intensity. According to this indicator, Russia is 2.6 times ahead of the United States, 3.9 times ahead of Western Europe, and 4.5 times ahead of Japan. Only partly, these differences can be justified by the harsh climatic conditions of Russia and the vastness of its territory. One of the main ways to prevent an energy crisis in our country is to pursue a policy that provides for the large-scale introduction of energy and resource-saving technologies at enterprises. Energy saving has become a priority area of ​​technical policy in all developed countries of the world.

In the near future, the problem of energy saving will increase its rating with the accelerated development of the economy, when there is a shortage of electric energy and it can be compensated in two ways - by introducing new energy generating systems and energy saving. The first way is more expensive and time-consuming, and the second one is much faster and more cost-effective because 1 kW of power with energy saving costs 4...5 times less than in the first case. The high cost of electrical energy per unit of the gross national product creates a huge potential for energy saving in the national economy. Basically, the high energy intensity of the economy is caused by the use of energy-wasting technologies and equipment, large losses of energy resources (during their extraction, processing, transformation, transport and consumption), and the irrational structure of the economy (a high share of energy-intensive industrial production). As a result, a vast energy saving potential has accumulated, estimated at 360.430 Mtce. tons, or 38.46% of modern energy consumption. The realization of this potential can allow, with the growth of the economy by 2.3 ... 3.3 times over 20 years, to limit the growth of energy consumption by only 1.25.

ny goods and services in the domestic and foreign markets. Thus, energy saving is an important factor in economic growth and increasing the efficiency of the national economy.

The purpose of this work is to consider the possibilities of creating energy-efficient asynchronous motors (AM) for controlled electric drives to ensure real energy saving.

Possibilities for creating energy efficient

induction motors

In this paper, on the basis of a systematic approach, effective ways to ensure real energy savings are determined. A systematic approach to energy saving combines two areas - the improvement of converters and asynchronous motors. Taking into account the possibilities of modern computer technology, improvement of optimization methods, we come to the need to create a software-computer complex for designing energy-efficient induction motors operating in controlled electric drives. Taking into account the great potential for energy saving in housing and communal services (housing and communal services), we will consider the possibility of using an adjustable electric drive based on asynchronous motors in this area.

The solution to the problem of energy saving is possible with the improvement of an adjustable electric drive based on asynchronous motors, which must be designed and manufactured specifically for energy-saving technologies. Currently, the energy saving potential for the most popular electric drives - pumping units - is more than 30% of the power consumption. Based on monitoring in the Altai Territory, the following indicators can be obtained using a controlled electric drive based on asynchronous motors: energy savings - 20.60%; saving water - up to 20%; exclusion of hydraulic shocks in the system; reduction of starting currents of motors; minimization of maintenance costs; reducing the likelihood of emergencies. This requires the improvement of all parts of the electric drive, and, above all, the main element that performs electromechanical energy conversion - an asynchronous motor.

Now, in most cases, in a controlled electric drive, serial asynchronous general-purpose motors are used. The level of consumption of active materials per unit of IM power has practically stabilized. According to some estimates, the use of serial IM in controlled electric drives leads to a decrease in their efficiency and an increase in installed power by 15.20%. Among Russian and foreign experts, there is an opinion that special engines are needed for such systems. A new approach to design is currently required due to the energy crisis. The mass of blood pressure has ceased to be a determining factor. An increase in energy performance comes to the fore, including by increasing their cost and the consumption of active materials.

One of the promising ways to improve the electric drive is the design and manufacture of induction motors specifically for specific operating conditions, which is favorable for energy saving. At the same time, the problem of adapting the AM to a specific electric drive is solved, which gives the greatest economic effect under operating conditions.

It should be noted that the production of IM specifically for a controlled electric drive is produced by Simens (Germany), Atlans-Ge Motors (USA), Lenze Bachofen (Germany), Leroy Somer (France), Maiden (Japan). There is a steady trend in the global electrical engineering industry to expand the production of such motors. In Ukraine, a software package for designing IM modifications for a controlled electric drive has been developed. In our country, GOST R 51677-2000 has been approved for IM with high energy performance, and their release will probably be organized in the near future. The use of AM modifications specially designed to provide effective energy saving is a promising direction for improving asynchronous motors.

At the same time, the question arises of a reasonable choice of a suitable motor from a variety of designs, modifications of the range of manufactured motors, because the use of general industrial asynchronous motors for an electric drive with an adjustable speed turns out to be suboptimal in terms of weight, size, cost and energy indicators. In this regard, the design of energy-efficient asynchronous motors is required.

An asynchronous motor is energy efficient, in which, using a systematic approach in design, manufacture and operation, efficiency, power factor and reliability are increased. Typical requirements for general industrial drives are the minimization of capital and operating costs,

including maintenance. In this regard, and also due to the reliability and simplicity of the mechanical part of the electric drive, the vast majority of general industrial electric drives are built on the basis of an asynchronous motor - the most economical motor that is structurally simple, unpretentious and has a low cost. An analysis of the problems of controlled induction motors showed that their development should be carried out on the basis of a systematic approach, taking into account the peculiarities of work in controlled electric drives.

At present, in connection with the increased requirements for efficiency by solving issues of energy saving and improving the reliability of the operation of electrical systems, the tasks of modernizing asynchronous motors to improve their energy characteristics (efficiency and power factor), obtaining new consumer qualities (improving environmental protection) are becoming particularly relevant. , including sealing), ensuring reliability in the design, manufacture and operation of asynchronous motors. Therefore, when performing research and development in the field of modernization and optimization of asynchronous motors, it is necessary to create appropriate methods to determine their optimal parameters, from the condition of obtaining maximum energy characteristics, and to calculate dynamic characteristics (start-up time, winding heating, etc.). As a result of theoretical and experimental studies, it is important to determine the best absolute and specific energy characteristics of asynchronous motors, based on the requirements for an adjustable AC drive.

The cost of a converter is usually several times higher than the cost of an induction motor of the same power. Asynchronous motors are the main converters of electrical energy into mechanical energy, and to a large extent they determine the efficiency of energy saving.

There are three ways to ensure effective energy saving when using a controlled electric drive based on asynchronous motors:

Improving blood pressure without changing the cross section;

Improving IM with a change in the geometry of the stator and rotor;

Choice of IM of general industrial design

more power.

Each of these methods has its advantages, disadvantages and limitations in application, and the choice of one of them is possible only through an economic assessment of the relevant options.

Improvement and optimization of asynchronous motors with a change in the geometry of the stator and rotor will give a greater effect, the designed motor will have better energy and dynamic characteristics. However, at the same time, the financial costs for the modernization and re-equipment of production for its production will amount to significant amounts. Therefore, at the first stage, we will consider measures that do not require large financial costs, but at the same time allow for real energy saving.

Research results

Currently, IM for a controlled electric drive is practically not being developed. It is advisable to use special modifications of asynchronous motors, in which the stamps on the stator and rotor sheets and the main structural elements are preserved. This article discusses the possibility of creating energy-efficient IM by changing the length of the stator core (/), the number of turns in the phase of the stator winding (#) and the wire diameter using the factory cross-sectional geometry. At the initial stage, modernization of asynchronous motors with a squirrel-cage rotor was carried out by changing only the active length. The AIR112M2 asynchronous motor with a power of 7.5 kW, produced by OAO Sibelektromotor (Tomsk), was taken as the base motor. The values ​​of the length of the stator core for calculations were taken in the range /=100.170%. The results of calculations in the form of dependences of the maximum (Psh) and nominal (tsn) efficiency on the length for the selected motor size are shown in fig. one.

Rice. 1. Dependences of the maximum and nominal efficiency for different lengths of the stator core

From fig. 1 shows how the efficiency value changes quantitatively with increasing length. The upgraded IM has a nominal efficiency higher than that of the base motor when the length of the stator core changes up to 160%, while the highest values ​​of the nominal efficiency are observed at 110.125%.

Changing only the length of the core and, as a result, reducing losses in steel, despite a slight increase in efficiency, is not the most effective way to improve an induction motor. It would be more rational to change the length and winding data of the motor (the number of turns of the winding and the cross section of the stator winding wire). When considering this option, the values ​​of the length of the stator core for calculations were taken in the range /=100.130% . The range of changes in the turns of the stator winding was assumed to be N = 60.110%. The base engine has the value No = 108 turns and n = 0.875. On fig. 2 shows a graph of the change in the efficiency value when changing the winding data and the active length of the motor. When the number of turns of the stator winding changes in the direction of decrease, there is a sharp drop in the efficiency values ​​to 0.805 and 0.819 for motors with a length of 100 and 105%, respectively.

Engines in the range of length variation /=110.130% have efficiency values ​​higher than those of the base engine, for example, No=96 ^»=0.876.0.885 and No=84 with 1=125.130% have n»=0.879.0.885. It is advisable to consider motors with a length in the range of 110.130%, and with a decrease in the number of turns of the stator winding by 10%, which corresponds to N = 96 turns. The extremum of the function (Fig. 2), highlighted in dark color, corresponds to the given values ​​of the length and turns. In this case, the efficiency value increases by 0.7-1.7% and is

We see the third way to ensure energy saving in the fact that it is possible to use an asynchronous motor of general industrial performance of higher power. The values ​​of the length of the stator core for calculations were taken in the range /=100.170%. The analysis of the data obtained shows that for the investigated engine AIR112M2 with a power of 7.5 kW, with an increase in its length to 115%, the maximum efficiency value n,wx=0.885 corresponds to the power Р2wn=5.5 kW. This fact indicates that it is possible to use motors of the AIR112M2 series with an increased length with a power of 7.5 kW, instead of the basic 5.5 kW motor of the AIR90M2 series, in an adjustable electric drive. For a 5.5 kW engine,

The power consumption per year is 71,950 r. One of the reasons for this fact is the reduction in the share of electricity to cover losses in the IM due to the operation of the engine in the region of increased efficiency values.

An increase in engine power must be justified by both technical and economic necessity. In the study of high-power engines, a number of IMs of general industrial use of the AIR series were taken in the power range of 3.75 kW. As an example, let's consider IM with a rotation speed of 3000 rpm, which are most often used in pumping units of housing and communal services, which is associated with the specifics of the regulation of the pumping unit.

Rice. Fig. 3. Dependence of savings over the average service life on the useful power of the engine: the wavy line is built according to the results of the calculation, the solid line is approximated

To justify the economic benefits of using increased power engines, calculations were made and a comparison was made of engines with the power required for a given task and engines with a power one step higher. On fig. 3 shows graphs of savings for the average service life (E10) from the useful power on the motor shaft. Analysis of the obtained dependence shows

economic efficiency of using high power engines, despite the increase in the cost of the engine itself. Energy savings over the average service life for engines with a rotation speed of 3000 rpm is 33.235 thousand rubles.

Conclusion

The huge potential for energy saving in Russia is determined by the high costs of electrical energy in the national economy. A systematic approach to the development of asynchronous controlled electric drives and the organization of their mass production can provide effective energy saving, in particular, in housing and communal services. When solving the problem of energy saving, an asynchronous controlled electric drive should be used, which currently has no alternative.

1. The task of creating energy-efficient asynchronous motors that meet specific operating conditions and energy saving must be solved for a specific controlled electric drive using a systematic approach. A new approach to the design of asynchronous motors is currently being applied. The determining factor is the increase in energy performance.

2. The possibility of creating energy-efficient asynchronous motors without changing the cross-sectional geometry with an increase in the length of the stator core up to 130% and a decrease in the number of turns of the stator winding up to 90% for controlled electric drives is considered, which allows real energy saving.

3. Ways to ensure energy saving through the use of high-power asynchronous motors in pumping units in the housing and utilities sector are shown. For example, when replacing the AIR90M2 engine with a power of 5.5 kW with the AIR112M2 engine, the energy saving is up to 15%.

4. The economic calculations carried out and the analysis of the results show the economic efficiency of using increased power engines, despite the increase in the cost of the engine itself. Energy savings over the average service life is expressed in tens and hundreds of thousands of rubles. depending on the engine power and is 33.325 thousand rubles. for asynchronous motors with a speed of 3000 rpm.

BIBLIOGRAPHY

1. Energy strategy of Russia for the period up to 2020 // TEK.

2003. - No. 2. - S. 5-37.

2. Andronov A.L. Energy saving in water supply systems by means of frequency regulation of the electric drive // ​​Electricity and the future of civilization: Mater. scientific-technical conf. - Tomsk, 2004. - S. 251-253.

3. Sidelnikov B.V. Prospects for the development and application of non-contact adjustable electric motors // Energy saving. - 2005. - No. 2. - S. 14-20.

4. Petrushin V.S. System approach in designing adjustable asynchronous motors. conf. IEEE-2003. - Crimea, Alushta, 2003. - Part 1. -S. 357-360.

5. GOST R 51677-2000 Electric asynchronous machines with power from 1 to 400 kW inclusive. Engines. Performance indicators. - M.: Publishing house of standards, 2001. - 4 p.

6. Muraviev O.P., Muravieva O.O. Induction variable speed drive as the basis of efficient energy saving // The 8th Russian-Korean Intern. Symp. Science and Technology KORUS 2004. - Tomsk: TPU, 2004.

V. 1. - P. 264-267.

7. Muraviev O.P., Muravieva O.O., Vekhter E.V. Energetic Parameters of Induction Motors as the Basis of Energy Saving in a Variable Speed ​​Drive // ​​The 4th Intern. Workshop Compatibility in Power Electronics Cp 2005. - June 1-3, 2005, Gdynia, Poland, 2005. -P. 61-63.

8. Muravlev O.P., Muravleva O.O. Power Effective Induction Motors for Energy Saving // The 9th Russian-Korean Intern. Symp. Science and Technology KORUS 2005. - Novosibirsk: Novosibirsk State Technical University, 2005. - V. 2. - P. 56-60.

9. Vekhter E.V. The choice of high-power asynchronous motors to ensure energy saving of pumping units in housing and communal services // Modern equipment and technologies: Proceedings of the 11th Intern. scientific-practical conf. youth and students. -Tomsk: Publishing House of TPU, 2005. - T. 1. - S. 239-241.

UDC 621.313.333:536.24

SIMULATION OF THE OPERATION OF MULTIPHALE ASYNCHRONOUS MOTORS IN EMERGENCY OPERATION MODES

D.M. Glukhov, O.O. Muravleva

Tomsk Polytechnic University E-mail: [email protected]

A mathematical model of thermal processes in a multiphase asynchronous motor is proposed, which makes it possible to calculate the temperature rise of the winding in emergency conditions. The adequacy of the model was verified experimentally.

Introduction

The intensive development of electronics and microprocessor technology leads to the creation of high-quality adjustable AC drives to replace DC drives and unregulated AC drives due to the greater reliability of AC motors compared to DC machines.

Regulated electric drives are gaining the field of application of unregulated ones both to ensure technological characteristics and to save energy. Moreover, preference is given to AC machines, asynchronous (AD) and synchronous (SD), as they have better weight and size indicators, higher reliability and service life, are easier to maintain and repair compared to DC collector machines. Even in such a traditionally "collector" area as electric vehicles, DC machines are giving way to frequency-controlled AC motors. An increasing place in the production of electrical engineering plants is occupied by modifications and specialized designs of electric motors.

It is impossible to create a universal frequency-controlled motor suitable for all occasions. It can only be optimal for each specific combination of the law and control method, the frequency control range and the nature of the load. A multi-phase asynchronous motor (MAD) can be an alternative to three-phase machines when powered by a frequency converter.

The purpose of this work is to develop a mathematical model for studying the thermal fields of multi-phase asynchronous motors both in steady state and in emergency operating modes, which are accompanied by a shutdown (break) of phases (or one phase) in order to show the possibility of operating asynchronous machines as part of a controlled electric drive. without the use of additional cooling means.

Thermal field modeling

Features of the operation of electrical machines in an adjustable electric drive, as well as high vibrations and noise, imposing certain requirements on the design, require other approaches in the design. At the same time, the features of polyphase motors make such machines suitable for use in controlled applications.

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