Saving materials in the production of asynchronous motors. International standards for energy efficiency of electric motors. Essence of the proposed development

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YES. Duyunov , project manager, AS and PP LLC, Moscow, Zelenograd

In Russia for a share asynchronous motors, according to various estimates, accounts for from 47 to 53% of the consumption of all generated electricity. In industry - on average 60%, in cold water supply systems - up to 90%. They do almost everything technological processes associated with movement and cover all spheres of human activity. With the advent of new, so-called motors with combined windings (MWM), it is possible to significantly improve their parameters without increasing the price.

For each apartment in a modern residential building there are more asynchronous motors than there are residents in it. Previously, since there was no goal of saving energy resources, when designing equipment they tried to “play it safe” and used engines with power exceeding the calculated one. Energy saving in design faded into the background, and such a concept as energy efficiency was not so relevant. Energy efficient engines- This is rather a purely Western phenomenon. Russian industry did not design or produce such engines. Go to market economy changed the situation dramatically. Today, saving a unit of energy resources, for example 1 ton of fuel in conventional terms, is half as expensive as extracting it.

Energy-efficient motors (EMs) presented on the foreign market are asynchronous motors with a squirrel-cage rotor, in which, by increasing the mass of active materials, their quality, as well as due to special design techniques, it is possible to increase ( powerful engines) or by 4-5% ( small engines) nominal efficiency with a slight increase in engine price. This approach can be beneficial if the load changes little, speed control is not required and the motor parameters are correctly selected.

Using motors with combined windings (WWM), due to improved mechanical characteristics and higher energy performance, it became possible not only to save from 30 to 50% of energy consumption with the same useful work, but also to create an adjustable energy-saving drive with unique characteristics that has no analogues in the world. The greatest effect is achieved when using DSO in installations with a variable load. Based on the fact that currently the global production volume of asynchronous motors of various capacities has reached seven billion units per year, the effect of the introduction of new motors can hardly be overestimated.

It is known that the average load of an electric motor (the ratio of the power consumed by the working part of the machine to the rated power of the electric motor) in domestic industry is 0.3-0.4 (in European practice this value is 0.6). This means that regular engine operates with efficiency significantly lower than rated. Excessive engine power often leads to imperceptible at first glance, but very significant negative consequences in equipment served by an electric drive, for example, to excessive pressure in hydraulic networks associated with increased losses, decreased reliability, etc. Unlike standard ones, DSOs have low level noise and vibration, higher torque multiplicity, have efficiency and power factor close to the nominal wide range loads This allows you to increase the average load on the engine to 0.8 and improve the characteristics of the drive served technological equipment, in particular, to significantly reduce its energy consumption.

Savings, payback, profit

The above concerns energy saving in the drive and is intended to reduce losses on the conversion of electrical energy into mechanical energy and increase the energy performance of the drive. When implemented on a large scale, DSO gives ample opportunities on energy saving up to the creation of new energy-saving technologies.

According to the website of the Federal State Statistics Service (http://www.gks.ru/
wps/wcm/connect/rosstat/rosstatsite/main/) electricity consumption in 2011 in Russia as a whole amounted to 1,021.1 billion kWh.

According to the order Federal service according to tariffs dated October 6, 2011 No. 239-e/4, the minimum level of tariff for electrical energy (power) supplied to customers on retail markets in 2012, will be 164.23 kopecks/kWh (excluding VAT).

Replacing standard induction motors will save 30 to 50% energy for the same useful work. The economic effect of widespread replacement will be minimal:

1021.1·0.47·0.3·1.6423 = 236.4503 billion rubles. per year.

In the Moscow region the effect will be minimal:

47100.4·0.47·0.3·1.6423 = 10906.771 million rubles. per year.

Taking into account the maximum tariff levels for electrical energy in peripheral and other problem areas, the maximum effect and minimum payback period are achieved in regions with maximum tariffs - Irkutsk region, Khanty-Mansi Autonomous Okrug, Chukotka Autonomous Okrug, Yamalo-Nenets Autonomous Okrug, etc.

Maximum effect and a minimum payback period can be achieved when replacing engines with continuous operation, for example, water supply pumping units, fan units, rolling mills, as well as highly loaded engines, for example, elevators, escalators, conveyors.

To calculate the payback period, the prices of OJSC UralElectro were taken as the basis. We believe that an energy service contract has been concluded with the company to replace the ADM 132 M4 engine of the pumping unit on a leasing basis. Engine price 11,641 rubles. The cost of work to replace it (30% of the cost) is RUB 3,492.3. Additional costs(10% of cost) RUB 1,164.1

Total costs:

11,641 + 3,492.3 + 1,164.1 = 16,297.4 rubles.

The economic effect will be:

11 kW 0.3 1.6423 rub./kWh 1.18 24 = = 153.48278 rub. per day (including VAT).

Payback period:

16,297.4 / 153.48278 = 106.18 days or 0.291 years.

For other capacities, the calculation gives similar results. Considering that the operating time of engines in industrial enterprises may not exceed 12 hours, the payback period may be no more than 0.7-0.8 years.

It is assumed that under the terms of the leasing contract, an enterprise that has replaced engines with new ones, after paying leasing payments, pays 30% of the energy savings for three years. In this case, the income will be: 153.48278·365·3 = 168,063.64 rubles. Consequently, replacing one low-power engine allows you to receive income from 84 to 168 thousand rubles. On average, from replacing engines one small utility company can generate an income of at least 4.8 million rubles. The introduction of new engines while upgrading standard ones will allow utilities and transport in many cases to abandon subsidies for electricity without increasing tariffs.

The project acquires particular social significance in connection with Russia's accession to the WTO. Domestic manufacturers of asynchronous motors are not able to compete with the world's leading manufacturers. This could lead to bankruptcy of many city-forming enterprises. Mastering the production of motors with combined windings will not only remove this threat, but also create serious competition in foreign markets. Therefore, the implementation of the project also has political significance for the country.

Novelty of the proposed approach

In recent years, due to the advent of reliable and affordable frequency converters, adjustable asynchronous drives have become widespread. Although the price of converters remains quite high (two to three times more expensive than the engine), they make it possible in some cases to reduce electricity consumption and improve engine performance, bringing them closer to the characteristics of less reliable engines DC. The reliability of frequency regulators is also several times lower than that of electric motors. Not every consumer has the opportunity to invest such huge amounts of money on the installation of frequency regulators. In Europe, by 2012, only 15% of adjustable electric drives are equipped with DC motors. Therefore, it is important to consider the problem of energy saving mainly in relation to asynchronous electric drives, including variable-frequency drives, equipped with specialized motors with lower material consumption and cost.

In world practice, there are two main directions for solving this problem.

The first is energy saving by means of electric drives by supplying the required power to the end consumer at every moment of time. The second is the production of energy-efficient motors that meet the IE-3 standard. In the first case, efforts are aimed at reducing the cost of frequency converters. In the second case - to develop new electrical materials and optimize the main dimensions of electrical machines.

Compared to known methods increasing the energy efficiency of an asynchronous drive, the novelty of our proposed approach lies in changing the fundamental design principle of classic motor windings. The scientific novelty lies in the fact that new principles have been formulated for the design of motor windings, as well as the selection of optimal ratios of the numbers of rotor and stator slots. On their basis, industrial designs and schemes of single-layer and double-layer combined windings have been developed, both for manual and automatic laying. Since 2011, 7 Russian patents have been received for technical solutions. Several applications are under consideration by Rospatent. Applications for patenting abroad are being prepared.

Compared to the known ones, a variable-frequency drive can be made on the basis of a DSO with an increased frequency of the supply voltage. This is achieved due to lower losses in the steel of the magnetic core. The cost of such a drive is significantly lower than when using standard motors, in particular, noise and vibration are significantly reduced.

During tests carried out at the stands of the Kataysky Pumping Plant, the standard 5.5 kW motor was replaced with a 4.0 kW motor of our design. The pump provided all the parameters in accordance with the requirements of the specifications, while the engine practically did not heat up.

Currently, work is underway to introduce technology in the oil and gas complex (Lukoil, TNK-BP, Rosneft, Bugulma Electric Pump Plant), and in metro enterprises ( International Association subways), in the mining industry (Lebedinsky GOK) and a number of other industries.

Essence of the proposed development

The essence of the development follows from the fact that, depending on the connection diagram of a three-phase load to a three-phase network (star or triangle), it is possible to obtain two current systems that form an angle of 30 electrical degrees between the magnetic flux induction vectors. Accordingly, an electric motor that has not a three-phase winding, but a six-phase one, can be connected to a three-phase network. In this case, part of the winding must be connected to a star, and part to a triangle, and the resulting induction vectors of the poles of the same phases of the star and triangle must form an angle of 30 electrical degrees with each other.

Combining two circuits in one winding makes it possible to improve the shape of the field in the operating gap of the engine and, as a result, significantly improve the main characteristics of the engine. The field in the working gap of a standard engine can only conditionally be called sinusoidal. In fact, it is stepped. As a result, harmonics, vibrations and braking torques are generated in the engine, which have a negative impact on the engine and degrade its performance. Therefore, a standard asynchronous motor has acceptable performance only at rated load. When the load differs from the rated load, the performance of a standard motor decreases sharply, reducing power factor and efficiency.

Combined windings also make it possible to reduce the level of magnetic induction of fields from odd harmonics, which leads to a significant reduction in the overall losses in the elements of the motor magnetic circuit and an increase in its overload capacity and power density. This also allows motors to be designed to operate at higher supply voltage frequencies when using steels designed to operate at a frequency of 50 Hz. Motors with combined windings have a lower frequency of starting currents at higher starting torques. This is essential for equipment operating with frequent and prolonged starts, as well as for equipment connected to long and heavily loaded networks with a high voltage drop. They generate less interference into the network and distort less the shape of the supply voltage, which is essential for a number of objects equipped with complex electronics and computing systems.

In Fig. Figure 1 shows the field shape in a standard 3000 rpm motor with a 24 slot stator.

The field shape of a similar motor with combined windings is shown in Fig. 2.

From the graphs above it can be seen that the field shape of a motor with combined windings is closer to sinusoidal than that of a standard motor. As a result, as existing experience shows, without increasing labor intensity, with lower material consumption, without changing existing technologies, all other conditions being equal, we obtain engines whose characteristics are significantly superior to standard ones. Unlike previously known methods for increasing energy efficiency, the proposed solution is the least expensive and can be implemented not only in the production of new engines, but also in major renovation and modernization of the existing fleet. In Fig. Figure 3 shows how the mechanical characteristics changed from replacing the standard winding with a combined winding during a major overhaul of the engine.

No other known method can so radically and effectively improve the mechanical characteristics of the existing engine fleet. The results of bench tests conducted by the Central Factory Laboratory of UralElectro-K CJSC, Mednogorsk, confirm the declared parameters. The data obtained are confirmed by the results obtained during testing at NIPTIEM in Vladimir.

Competitive advantages

The uniqueness of the proposed solution lies in the fact that competitors that are obvious at first glance are, in fact, potential strategic partners. This is explained by the fact that it is possible to master the production and modernization of motors with combined windings in the shortest possible time at almost any specialized enterprise engaged in the production or repair of standard motors. This does not require changes to existing technologies. To do this, it is enough to modify the existing design documentation at enterprises. No competing product offers these benefits. In this case, there is no need to obtain special permits, licenses and certificates. An illustrative example is the experience of cooperation with OJSC UralElectro-K. This is the first enterprise with which a license agreement has been concluded for the right to produce energy-efficient asynchronous motors with combined windings. Compared to frequency drives, the proposed technology allows for greater energy savings with significantly lower capital investments. During operation, maintenance costs are also significantly lower. Compared to other energy-efficient engines, the proposed product has a lower price for the same performance.

Conclusion

The scope of application of asynchronous motors with combined windings covers almost all spheres of human activity. About seven billion engines of various capacities and designs are produced annually in the world. Today, almost no technological process can be organized without the use of electric motors. The consequences of large-scale use of this development are difficult to overestimate. In the social sphere, they make it possible to significantly reduce tariffs for basic types of services. In the field of ecology, they allow us to achieve unprecedented results. For example, with the same useful work, they make it possible to reduce the specific electricity generation by three times and, as a result, sharply reduce the specific consumption of hydrocarbons.

Three-phase asynchronous electric motors of the main version are energy efficient (class IE2) of the AIR, 7AVER series

Motors for general industrial use are designed to operate in S1 mode from the mains AC 50Hz, voltage 380V (220, 660V). Standard degree of protection - IP54, IP55, climatic version and placement category - U3, U2.
Energy efficiency class - IE2 (in accordance with GOST R51677-2000 and international standard IEC 60034-30).

The use of energy efficient engines allows:

• increase Engine efficiency by 2-5%;
• reduce energy consumption;
• increase the life of the engine and related equipment;
• improve power factor;
• improve overload capacity;
• increase the engine’s resistance to thermal loads and changes in operating conditions.

The overall, installation and connection dimensions of energy-efficient motors correspond to the overall, installation and connection dimensions of the basic design motors.

Energy efficient electric motors EFF1/IE2 produced by ENERAL

Energy efficient electric motors EFF1 are three-phase asynchronous single-speed electric motors with a squirrel-cage rotor.
Energy-efficient electric motors are electric motors for general industrial use, whose total power losses are at least 20% less than the total power losses of engines with normal efficiency of the same power and rotation speed.

Key Features:

Energy efficiency class Eff 1 meets IE2 standard
Technical characteristics of energy-efficient engines produced by ENERAL are presented in the table:

Comparison of characteristics:

Asynchronous electric motors with a squirrel-cage rotor currently make up a significant part of all electrical machines; more than 50% of the electricity consumed comes from them. It is almost impossible to find an area where they are used: electric drives of industrial equipment, pumps, ventilation equipment and much more. Moreover, both the volume of the technological park and engine power are constantly growing.

Energy efficient ENERAL motors of the AIR...E series are structurally designed as three-phase asynchronous single-speed motors with a squirrel-cage rotor and comply with GOST R51689-2000.

The energy-efficient engine of the AIR…E series has increased efficiency due to the following system improvements:

1. The mass of active materials has been increased (copper stator winding and cold-rolled steel in the stator and rotor packages);
2. Electrical steels with improved magnetic properties and reduced magnetic losses are used;
3. The tooth-slot zone of the magnetic core and the design of the windings have been optimized;
4. Insulation with increased thermal conductivity and electrical strength is used;
5. The air gap between the rotor and stator has been reduced using high-tech equipment;
6. A special fan design is used to reduce ventilation losses;
7. Bearings and lubricants of higher quality are used.

New consumer properties of the energy-efficient engine of the AIR...E series are based on design improvements, where special attention is paid to protection from adverse conditions and increased sealing.

So, design features AIR…E series allow minimizing losses in the stator windings. Due to the low temperature of the motor winding, the service life of the insulation is also extended.

An additional effect is achieved by reducing friction and vibration, and therefore overheating, due to the use of high-quality lubricant and bearings, including a tighter bearing lock.

Another aspect related to the lower operating temperature of the engine is the ability to operate at higher temperatures. high temperature environment or the possibility of reducing costs associated with external cooling of a running engine. This also leads to lower energy costs.

One of important advantages new energy-efficient engine - reduced noise level. IE2 class electric motors use less powerful and quieter fans, which also plays a role in improving aerodynamic properties and reducing ventilation losses.

Minimizing capital and operating costs are key requirements for industrial energy-efficient electric motors. As practice shows, the period of compensation due to the difference in prices when purchasing more advanced asynchronous electric motors class IE2 is up to 6 months only due to lower operating costs and consumption of less electricity.

Reduced costs when replacing the engine with an energy-efficient one:

AIR 132M6E (IE2) P2=7.5 kW; Efficiency=88.5%; In=16.3A; cosφ=0.78
AIR132M6 (IE1) P2=7.5 kW; Efficiency=86.1%; In=17.0A; cosφ=0.77

Power consumption: P1=P2/efficiency
Load characteristic: 16 hours per day = 5840 hours per year
Annual energy cost savings: 1400 kW/hour

When switching to new energy-efficient engines, the following are taken into account:

• increased requirements for environmental aspects;
• requirements for the level of energy efficiency and performance characteristics of products;
• energy efficiency class IE2, along with savings opportunities, acts as a unified “quality mark” for the consumer;
• financial incentive: opportunity to reduce energy consumption and operating costs integrated solutions: energy efficient motor + efficient control system (variable drive) + effective protection system = best result.
  

Advantages:

Provide a reduction in total power losses by at least 20% in relation to engines with normal efficiency of the same power and rotation speed;
- Increased efficiency in partial load mode (by 1.8 - 2.4%);
- Have improved performance characteristics:

• more resistant to network fluctuations;
• less overheating, less energy loss;
• operate with reduced noise levels;
• Increased reliability and extended service life;
• At a higher purchase price (15-20% compared to the standard), EEDs recoup additional costs by reducing energy consumption within 500-600 hours of operation;
• Reduced overall operating costs.

Thus, energy-efficient motors are motors of increased reliability for enterprises focused on energy-saving technologies.

The energy efficiency indicators of AIR...E electric motors produced by ENERAL comply with GOST R51677-2000 and the international standard IEC 60034-30 for energy efficiency class IE2.

UDC 621.313.333:658.562

ENERGY-EFFICIENT INDUCTION MOTORS FOR CONTROLLED ELECTRIC DRIVES

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 allows for real energy savings. Ways to ensure energy saving through the use of high-power asynchronous motors in pumping units in the housing and communal services sector are shown. The economic calculations and analysis of the results show the economic efficiency of using high-power engines, despite the increase in the cost of the engine itself.

Introduction

In accordance with the Energy Strategy for the period until 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, Western Europe 3.9 times, Japan - 4.5 times. 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 implement a policy providing 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 a shortage of electrical energy appears and it can be compensated for in two ways - the introduction of new energy generating systems and energy saving. The first way is more expensive and takes a long time, and the second is much faster and more economically profitable because 1 kW of power with energy saving costs 4...5 times less than in the first case. Large expenditures of electrical energy per unit of gross domestic product create enormous potential for energy saving in the national economy. Basically, the high energy intensity of the economy is caused by the use of energy-waste technologies and equipment, large losses of energy resources (during their extraction, processing, transformation, transport and consumption), and the irrational structure of the economy (high share of energy-intensive industrial production). As a result, extensive energy saving potential has accumulated, estimated at 360.430 million tce. t., or 38.46% of modern energy consumption. The realization of this potential may allow, with economic growth over 20 years by 2.3...3.3 times, limiting the growth of energy consumption to only 1.25...1.4 times, significantly improving the quality of life of citizens and the competitiveness of domestic

new 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 adjustable electric drives to ensure real energy savings.

Opportunities for creating energy efficient

asynchronous motors

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

The solution to the problem of energy saving is possible by improving the adjustable electric drive based on asynchronous motors, which should 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 power consumption. Based on monitoring in the Altai Territory, the following indicators can be obtained when using an adjustable electric drive based on asynchronous motors: energy savings - 20.60%; water savings - up to 20%; elimination of hydraulic shocks in the system; reduction of motor starting currents; minimizing maintenance costs; reducing the likelihood of emergency situations. This requires improvement of all parts of the electric drive, and, above all, the main element that performs electromechanical energy conversion - the asynchronous motor.

Now in most cases adjustable electric drive Serial general-purpose asynchronous 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 motors in adjustable 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 such systems require special engines. Currently, a new approach to design is required due to the energy crisis. Blood pressure mass has ceased to be a determining factor. Increasing energy performance comes to the fore, including through an increase in their cost and consumption of active materials.

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

It should be noted that the production of motors specifically for adjustable electric drives is produced by Siemens (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. Developed in Ukraine software package designing IM modifications for adjustable electric drives. In our country, GOST R 51677-2000 has been approved for IM with high energy performance and possibly in soon their release will be organized. The use of IM modifications specially designed to ensure effective energy saving - promising direction to improve asynchronous motors.

This raises the question of making a reasonable choice. suitable engine from the range of manufactured motors, varied in design and modifications, because the use of general industrial asynchronous motors for electric drives with adjustable frequency rotation 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 efficiency, power factor and reliability are increased using a systematic approach in design, manufacturing and operation. The characteristic requirements for general industrial drives are minimization of capital and operating costs,

including on 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, which is structurally simple, unpretentious and has a low cost. An analysis of the problems of adjustable asynchronous motors showed that their development should be carried out on the basis of a systematic approach, taking into account the peculiarities of operation in adjustable electric drives.

Currently, due to increased requirements for efficiency by addressing issues of energy saving and increasing the reliability of electrical systems, the task of modernizing asynchronous motors to improve their energy characteristics (efficiency and power factor), obtaining new consumer qualities (improving environmental protection , including sealing), ensuring reliability in the design, manufacture and operation of asynchronous motors. Therefore, when carrying out research and development in the field of modernization and optimization of asynchronous motors, it is necessary to create appropriate methods for determining their optimal parameters, from the condition of obtaining maximum energy characteristics, and calculating dynamic characteristics (starting time, heating of windings, 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 a controlled AC electric drive.

The cost of a converter is usually several times higher than the cost of an asynchronous 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 an adjustable electric drive based on asynchronous motors:

Improving blood pressure without changing the cross section;

Improving IM by changing the geometry of the stator and rotor;

Selection of general industrial IM

more power.

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

Improving and optimizing asynchronous motors with changing the geometry of the stator and rotor will give a greater effect; the designed motor will have better energy and dynamic characteristics. However, the financial costs for 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 savings.

Research results

At present, IMs for adjustable electric drives are practically not being developed. It is advisable to use special modifications of asynchronous motors, which retain the stamps on the stator and rotor sheets and the main structural elements. This article discusses the possibility of creating energy-efficient IM by changing the length of the stator core (/), the number of turns in the stator winding phase (No) and the diameter of the wire when using the factory cross-section geometry. At the initial stage, asynchronous motors with a squirrel-cage rotor were modernized by changing only the active length. The base motor was an AIR112M2 asynchronous motor with a power of 7.5 kW, produced by Sibelektromotor OJSC (Tomsk). The stator core length values ​​for calculations were taken in the range /=100.170%. The calculation results in the form of dependences of the maximum (Ppsh) and nominal (tsn) efficiency on the length for a given motor size are presented in Fig. 1.

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

From Fig. 1 shows how the efficiency value changes quantitatively with increasing length. The upgraded IM has a rated efficiency higher than that of the base engine when the length of the stator core changes to 160%, while the most high values nominal efficiency is observed at 110.125%.

Changing only the length of the core and, as a consequence, reducing losses in steel, despite a slight increase in efficiency, is not the most effective way to improve an asynchronous 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 stator core length values ​​for calculations were taken in the range /=100.130%. The range of changes in the turns of the stator winding was taken equal to No = 60.110%. The base engine has a value of No = 108 turns and n = 0.875. In Fig. Figure 2 shows a graph of changes in efficiency values ​​with changes in winding data and active length of the motor. When the number of turns of the stator winding decreases, there is a sharp drop in efficiency values ​​to 0.805 and 0.819 for motors with a length of 100 and 105%, respectively.

Motors in the range of length changes /=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 reduction in the number of turns of the stator winding by 10%, which corresponds to No. = 96 turns. The extremum of the function (Fig. 2), highlighted in dark color, corresponds to these values ​​of length and turns. In this case, the efficiency value increases by 0.7.1.7% and amounts to

We see the third way to ensure energy saving in the fact that it is possible to use a general-industrial asynchronous motor of higher power. The stator core length values ​​for calculations were taken in the range /=100.170%. Analysis of the data obtained shows that for the studied engine AIR112M2 with a power of 7.5 kW, with an increase in its length to 115%, the maximum efficiency value p,shx = 0.885 corresponds to the power P2sh„=5.5 kW. This fact indicates that it is possible to use motors of the AIR112M2 series with an increased length of 7.5 kW in an adjustable electric drive, instead of the base 5.5 kW motor of the AIR90M2 series. A 5.5 kW engine costs

The capacity of electricity consumed per year is 71,950 rubles, which is significantly higher than the same indicator for an engine of increased length (115% of the base) with a power of 7.5 kW at C = 62,570 rubles. One of the reasons for this fact is the reduction in the share of electricity to cover losses in the motor due to engine operation in the region of increased efficiency values.

Increasing engine power must be justified by both technical and economic necessity. When studying high-power motors, a number of IMs of general industrial use of the AIR series in the power range of 3.75 kW were taken. As an example, let us consider motors with a rotation speed of 3000 rpm, which are most often used in pumping units in the housing and communal services sector, which is due to the specific regulation of the pumping unit.

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

To justify the economic benefits of using high-power engines, calculations and comparisons were made of engines with the power required for a given task and engines with a power level one step higher. In Fig. 3 shows graphs of savings over the average service life (E10) from the useful power on the engine shaft. Analysis of the obtained dependence shows

economic efficiency of using engines of increased power, despite the increase in the cost of the engine itself. Electricity savings over an average service life amount to 33,235 thousand rubles for engines with a rotation speed of 3000 rpm.

Conclusion

The huge potential for energy saving in Russia is determined at great expense electrical energy in the national economy. A systematic approach to the development of asynchronous adjustable electric drives and the organization of their mass production can ensure effective energy saving, in particular, in the housing and communal services sector. When solving the problem of energy saving, an asynchronous adjustable electric drive should be used, for which there is currently no alternative.

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

2. The possibility of creating energy-efficient asynchronous motors without changing the cross-section geometry by increasing the length of the stator core to 130% and reducing the number of turns of the stator winding to 90% for adjustable electric drives is considered, which allows for real energy savings.

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

4. The economic calculations and analysis of the results show the economic efficiency of using high-power engines, despite the increase in the cost of the engine itself. Electricity savings over the average service life are expressed in tens and hundreds of thousands of rubles. depending on engine power and amounts to 33.325 thousand rubles. for asynchronous motors with a rotation speed of 3000 rpm.

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UDC 621.313.333:536.24

SIMULATION OF OPERATION OF MULTIPHASE INDUCTION MOTORS IN EMERGENCY OPERATING 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 at emergency modes. The adequacy of the model was verified experimentally.

Introduction

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

Adjustable electric drives are conquering the application areas of non-adjustable drives both to ensure technological performance and for the purpose of energy saving. Moreover, preference is given to AC machines, asynchronous (AM) and synchronous (SD), since they have better weight and size indicators, higher reliability and service life, and are easier to maintain and repair compared to collector machines DC. Even in such a traditionally "collector" field as electric vehicles, DC machines are giving way to variable-frequency AC motors. Modifications and specialized versions of electric motors occupy an increasingly important place in the products of electrical machine-building plants.

It is impossible to create a universal frequency-controlled motor suitable for all occasions. It can only be optimal for each specific combination of law and control method, frequency control range and load nature. A multiphase asynchronous motor (MAM) 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 multiphase asynchronous motors in both steady-state and emergency operating modes, which are accompanied by shutdown (break) of phases (or one phase) in order to show the possibility of operation asynchronous machines as part of an adjustable electric drive without the use additional funds cooling.

Thermal field modeling

Features of the operation of electrical machines in a controlled electric drive, as well as high vibrations and noise, imposing certain design requirements, require different approaches to design. At the same time, the features of multiphase motors make such machines suitable for use in controlled applications.

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A unique modernization technology using combined windings of the “Slavyanka” type makes it possible to increase power and significantly reduce energy consumption of burnt-out and new asynchronous motors. Today it is successfully implemented at several large industrial enterprises. This modernization makes it possible to increase the starting and minimum torques by 10-20%, and reduce them by 10-20%. starting current or increase the power of the electric motor by 10-15%, stabilize the efficiency close to the rated one in a wide range of loads, reduce the current idle speed, reduce steel losses by 2.7-3 times, the level of electromagnetic noise and vibrations, increase reliability and increase the service life between repairs by 1.5 - 2 times.

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

Energy-efficient motors (EM) are asynchronous motors with a squirrel-cage rotor, in which, due to an increase in the mass of active materials, their quality, as well as through special design techniques, it was possible to increase by 1-2% (powerful motors) or by 4-5% ( small engines) rated efficiency with some increase in engine price.

With the advent of motors with combined Slavyanka windings using a patented design, it became possible to significantly improve motor parameters without increasing the price. Due to improved mechanical characteristics and higher energy performance, it has become possible to save up to 15% of energy consumption with the same useful work and create an adjustable drive with unique characteristics that has no analogues in the world.

Unlike standard ones, electric motors with combined windings have a high torque ratio, have efficiency and a power factor close to the rated one in a wide range of loads. This allows you to increase the average load on the engine to 0.8 and improve the performance characteristics of the equipment served by the drive.

Compared to known methods for increasing the energy efficiency of an asynchronous drive, the novelty of the technology used by the St. Petersburgers lies in changing the fundamental design principle of classic motor windings. The scientific novelty lies in the fact that completely new principles have been formulated for the design of motor windings and the selection of optimal ratios of the numbers of rotor and starter slots. On their basis, 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 Russian patents have been received for technical solutions.

The essence of the development is that, depending on the connection diagram of a three-phase load to a three-phase network (star or triangle), two current systems can be obtained, forming an angle of 30 electrical degrees between the vectors. Accordingly, an electric motor that has not a three-phase winding, but a six-phase one, can be connected to a three-phase network. In this case, part of the winding must be connected to a star, and part to a triangle, and the resulting vectors of the poles of the same phases of the star and triangle must form an angle of 30 electrical degrees with each other. Combining two circuits in one winding makes it possible to improve the shape of the field in the operating gap of the engine and, as a result, significantly improve the main characteristics of the engine.

Compared to the known ones, a variable-frequency 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.

The use of this technology when repairing asynchronous motors allows, due to energy savings, to recoup costs within 6-8 months. Over the past year, the Research and Production Association “St. Petersburg Electrical Engineering Company” alone has modernized several dozen burnt out and new asynchronous motors by rewinding stator windings at a number of large enterprises in St. Petersburg in the bakery, tobacco industries, building materials factories and many others. And this direction is developing successfully. Today, the Research and Production Association “St. Petersburg Electrical Engineering Company” is looking for potential partners in the regions who can organize a business together with St. Petersburg residents to modernize asynchronous electric motors in their area.

Prepared by Maria Alisova.

Reference

Nikolay Yalovega- founder of technology - professor, Doctor of Technical Sciences. Patent issued in the USA in 1996. As of today, the validity period has expired.

Dmitry Duyunov— developer of a method for calculating layout schemes for combined motor windings. A number of patents have been issued.