Summary of research and developments
INTRODUCTION
The modern stage of development of industrial electrical drives and systems of automatic control is characterized the wide spectrum of various innovative suggestions which give birth due to the leadthrough of research and experimental works. Leading producers at the market of technique for an electromechanic and automation of technological complexes offer many interesting devices and technical decisions on their basis. Due to it today the decision of practically any requirement specification and realization of the systems of automatic control an object becomes possible with the ever-higher level of complication (be that separate mechanism or factory with the difficult structure of technological complexes).
However, what ideal alternative modern electrical machines and their control system were not, by an absolute leader in application on industrial enterprises and not only, there is the system of automatic control, built on the base of induction motor with the use frequency converter. This system allows to get the quite good technical and economic indexes of the use of application of the managed drive in static and dynamic office hours. In addition, for the construction of such system there is not a necessity for replacement of electrical machine and mechanical knots. Modern frequency converters of foreign producers not bad work with the old machines of domestic production. Certainly, many nuances on which it is necessary to pay attention during work frequency converters with electrical machine of mass production take place (which generally is not intended for work in composition the system of adjusting). It worsening of cooling during work on an underspeed at a quiescent load; some losses, related to work at the values of currents and tensions which differ from nominal, and, as a result of it, decline of output-input and power-factor ratio [1].
In general, electrical drive of alternating current on a base induction motor with a shortcircuited rotor and frequency converters is the basic type of electromechanics transformation of energy, which is successfully used on enterprises. Newest technologies and developments, in particular those which require the deep or complete re-erecting of production remain an unattainable purpose for enterprises and factories, and the old systems of non-adjustment drive already so became obsolete itself, that are unprofitable in any case and modernizations are not added in any way.
In this situation mechanisms which are equipped an induction non-adjustment drive and need improvement, coming from the necessities of technological process or economy of electrical power, are a wonderful object for automation. Management an induction machine with a help frequency converter is the simple, effective and economical method, therefore the system of frequency converter– induction motor is the most widespread system of automated electrical drive.
Modern frequency converters are the converters with double-conversion of energy, that have a link of direct current in the composition that a bit reduces him output-input ratio, however much other substantial advantages of converters of this type provide by him dominant position in modern automated electrical drive. Vast and ramified system of tuning of parameters frequency converter allows very exactly to influence a drive in accordance with the requirements of concrete mechanism or technological process.
CURRENT STAGE OF WORK
Use of electrical drive of alternating current in the system «frequency converter – an induction motor» to date is the most widespread system of the automated electrical drive, because a management an induction machine by the frequency converter is the simple, effective and economical method of realization of the managed electrical drive. Deep study of theoretical material on the induction frequency-managed electrical drive, mastering of software for work with the frequency converters, acquisition of practical experience and leadthrough of practical researches with an electromechanics equipment in the real terms is the actual aspects of this work.
REVIEW OF EXISTENT RESEARCHES
In connection with very wide distribution of the systems of frequency management in all spheres of industry and not only, plenty of theoretical and practical researches on this topic in the conditions of different research centers and higher educational establishments is conducted.
TASKS, DECIDED IN THIS WORK
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development and construction of experimental stand for the leadthrough of researches with the use of industrial equipment;
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research of static and dynamic descriptions of electrical drive during the imitation of moment of the static loading on the billow of induction motor in accordance with some diagram;
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a leadthrough of comparative analysis of regulation properties of electrical drive is in different office hours.
BASIC PART
Construction of experimental stand for research of the induction frequency-managed electrical drive executed in the laboratory of control system by the electrical drives of department of EAPU. In basis of stand is used the frequency converter Micromaster 440 productions of firm Siemens. Micromaster 440 is a serial converter, intended for adjusting of three-phase electrical motors of alternating current. He is equipped the microsystem of management, which provides optimum work of electrical drive in a technological process, and uses modern technologies with IGBT by modules-transistors (Insulated Gate Bipolar Transistor is transistor with the isolated breech-block). The original method of latitudinal-impulsive modulation with the choice of frequency of commutation enables noiseless work of electrical motor. The vast functions of defence provide effective defence of converter and motor. Connection of frequency converter with the personal computer gives many possibilities in research and evident presentation of principles of the systems of automatic control of one or another coordinate of drive. Realization of the known laws (principles, algorithms) of management with different user facilities and wide possibilities of retuning and adaptation of parameters gives space for researches of conduct of drive under various conditions and analysis of experimental data, got, for example, at the different laws of management in the conditions of the unchanging loading, or to see the reaction of the adjusting system on influence of indignation of different character.
The generalized scheme of an experimental stand is shown on picture 1.
Picture 1 – Generalized scheme of an experimental stand
(GIF-animation, 3 frames, 189Kb, infinite repetition)
The construction of equipment of stand is executed with the observance of principles of block-module structure and sectionalizing of areas of chart of stand. All necessary organs of management and mean of visualization are shown out on a front panel for providing of comfortable and safe access to them. A stand is foreseen by possibility of two variants of creation of loading on the billow of induction motor M1. As a loading machine the generator of direct-current of M2 is applied. It is a machine with the mixed excitation, which works as a machine of independent excitation, because a shunt puttee is connected to the independent source, and the successive is not involved quite. A generator is connected with an induction motor a muff, and can come forward as an imitator of working organ which creates the moment of the static loading on the billow of induction motor. The puttee of excitation LM2 of generator gets a feed from the source of direct current which the monophase out of control rectifier UZ plays role of. Possibility of forming of linear dependence of moment of loading depending on speed is realized most simply – through connecting of armature to the bit rheostat Rp and organizations thus of work M2 in the mode of the dynamic braking. Resistance of bit rheostat is neat so that at nominal speed of rotation and presence of current of excitation on the terminals of armature puttee electro-motive force, which stipulates flowing in it of current a size of which is near to the basic value, is generated. The chart of stand foresees also possibility of feed of armature of loading machine from the drive of direct current БТУ-3601, that enables to create a permanent (independent of speed of rotation) static moment, and also variable moment forming of which can be carried out in accordance with some diagram by reshaper of moment ЗМ.
The photo-impulsive sensor of speed BV is intended for the removal of information about actual speed of rotation of billow of electrical machines and conclusion of it in an evident form for visual control and comparing to the calculation size. Development and constructing of sensor is also executed in laboratory terms [3].
Management of frequency converter, control and diagnosticating of work of drive, visualization and registration the results of experiment (static and dynamic descriptions), the record of values of all necessary variables is carried out by the personal computer, with which the frequency converter is united through the special module which uses the general-purpose interface of connection of RS232. Drivemonitor or Starter, set on a computer, software gives comfortable access to all parameters of the system, allows to change them, manage work of occasion in the online mode and to control the state of the system with evident presentation of current variables of information of process [4].
CONCLUSION
The experimental stand adjusted and geared-up to work is intended for the leadthrough of researches of regulation properties of the induction frequency-managed drive, and also leadthrough of laboratory works for students and master's degrees.
LITERATURE
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Комплектні електроприводи: Навч. посібник / М.М. Казачковський – Дніпропетровськ: Національний гірничий університет, 2003. – 226 с.
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Соколовский Г.Г. Электроприводы переменного тока с частотным регулированием: Учебник – М.: Академия, 2006 – 265 с.
- Виглеб Г. Датчики. Устройство и применение: Пер. с нем. – М.: Мир, 1989. – 196 с.
- Micromaster 440. Руководство по эксплуатации. Документация пользователя. Издание А1. – Siemens AG 2007. – 140 с.
- Булгаков А.А. Частотное управление асинхронными электроприводами. - М.: Энергоиздат . 1982. - 216 с.
- Ссылка – Усольцев А.А. Частотное управление асинхронными двигателя-
ми/Учебное пособие. СПб: СПбГУ ИТМО, 2006, – 94 с.
- Ссылка – Автоматизация нагрузочных испытаний асинхронного электропривода. Е.В. Шульгин.
- Ссылка – Энергетические показатели асинхронного двигателя в частотном электроприводе при различных законах управления. В.С. Петрушин, канд. техн. наук, А.А. Танько
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