REGULATION OF UNBALANCED ELECTROMAGNETIC MOMENT IN MUTUAL LOADING SYSTEMS OF ELECTRIC MACHINES OF TRACTION ROLLING STOCK AND MULTIPLE UNIT OF MAINLINE AND INDUSTRIAL TRANSPORT

Purpose. The research data are aimed to identify the regulatory principles of unbalanced electromagnetic moment of mutually loaded electric machines of traction rolling stock and multiple unit of main and industrial transport. The purpose of this study is energy efficiency increase of the testing of traction electric machines of direct and pulse current using the improvement methods of their mutual loading, including the principles of automatic regulation of mutual loading system. Methodology. The general theoretical provisions and principles of system approach to the theoretical electric engineering, the theory of electric machines and theoretical mechanics are the methodological basis of this research. The known methods of analysis of electromagnetic and electromechanical processes in electrical machines of direct and pulse current are used in the study. Methods analysis of loading modes regulation of traction electric machines was conducted using the generalized scheme of mutual loading. It is universal for all known methods to cover the losses of idling using the electric power. Findings. The general management principles of mutual loading modes of the traction electric machines of direct and pulse current by regulating their unbalanced electric magnetic moment were developed. Regulatory options of unbalanced electromagnetic moment are examined by changing the difference of the magnetic fluxes of mutually loaded electric machines, the current difference of electric machines anchors, the difference of the angular velocities of electric machines shafts. Originality. It was obtained the scientific basis development to improve the energy efficiency test methods of traction electric machines of direct and pulse current. The management principles of mutual loading modes of traction electric machines were formulated. For the first time it is introduced the concept and developed the principles of regulation of unbalanced electromagnetic moment in the mutual loading systems of electric machines of direct and pulse current. Analytical expressions for the unbalanced moment of mutually loaded electromagnetic electric machines were obtained. The requirements for automatic regulation systems of the mutual loading stands of the traction electric machines of direct and pulse current are formulated. Practical value. Using the results of the theoretical research will significantly simplify the development algorithms of the test stands management of the traction electric machines of rolling stock for mainline and industrial transport. Introduction of the proposed principles of mutual loading for traction electric machines will significantly reduce the costs for creating new stations and modernization of the existing ones for testing of traction electric machines. Automating the process of refit and acceptance tests of traction electric machines will significantly improve the test quality and reliability of the traction rolling stock and multiple unit with electric traction drive.


Introduction
Requirements of the relevant standards and repair regulations of traction rolling stock and multiple units of the main and industrial vehicles provide acceptance tests for each newly produced traction electric machine or after repair [3,10].These tests are an important and integral part of the technological processes of manufacturing or repair of electric cars, material costs for which are included in the cost of the final product.Heating tests, check of rotation and reverse frequency, as well as commutation test require inevitable loading of the traction electric machines.
High energy efficiency at a relatively low total power of the supply sources is provided by the systems of mutual loading, in which there is energy exchange between the electric machines under study [11][12][13].External supply sources in such loading systems are only required to cover the power losses in the electric machines under study [6][7][8].
Cover of certain types of power losses in the mutual loading systems can be carried out by both direct and indirect methods.The use of indirect methods the loss covering is realized by using unbalanced electromagnetic power of the studied electric machines.This power can be created due to the difference of both electromotive forces of electric machines or the difference of their electromagnetic moments [4].

Purpose
The paper is aimed to determine the regulatory principles of unbalanced electromagnetic torque of mutually loaded electric machines of traction rolling stock and multiple units of the mainline and industrial transport.

Methodology
Unbalanced electromagnetic power of mutually loaded electric machines of direct and pulse current can be represented as the difference [1,2]  In the mutual loading systems with electric method to cover the idling losses the regulation of angular speed of the tested electric machines is carried out by changing эм P ∆ .
Generalized universal scheme of mutual loading system of electric cars, which makes it possible to realize all the possible variants of electric method to cover the idling losses, is shown in the Fig. 1.
In this scheme: M -are the windings of electric machine tested in the mode of motor; G -are the windings of electric machine tested in the mode of generator; И1 -is a consistent source of electric power; И2 -is a parallel source of electric power; P -is a gear (converter of angular velocity).where эмд M , эмг M ′ -are the electromagnetic tor- que of the motor and electromagnetic torque of the generator, respectively.
The reduced electromagnetic torque of the generator can be represented as  After expressing the electromagnetic torques of the motor and the generator through the magnetic fluxes and currents, after transformations we obtain Let us consider the possible ways of regulating the values эм M ∆ by changing the parameters of regulators and converters of the mutual loading system.
The difference between magnetic fluxes Ф ∆ , the armature current difference I ∆ and the transfer coefficient of the angular velocity k ω [1, 2] will be considered as the factors determining the value The equation of the torques balance in the static mode for all the schemes of mutual loading with the electric method to compensate the idling losses will have the form [1] эм  The Fig. 3 shows that at the higher load current I of the tested electric machines to compensate the given amount of the losses of torques M ∆ ∑ it is required a lesser value of the difference of magnetic fluxes Ф ∆ .
Let us consider the variant of regulation эм M ∆ by changing the armature currents difference, wherein: 1; In this variant of the regulation the condition Ф 0 ∆ ≠ is taken from considerations that the mag- netic characteristics of a pair of the tested electric machines may not be the same [5,9].That is, the case of the magnetic characteristics divergence of the tested engine and generator is considered.
In this case the expression (1) can be written as After transformations the same expression can be written in two ways: For the case of correspondence of the magnetic characteristics   k var The condition Ф 0 ∆ ≠ is accepted in this variant of regulation from the same considerations as in the previous one.
The equation ( 1) for the given condition will have the form ( ) After transformations we obtain the same expression in the form ( ) At the coincidence of the magnetic characteristics of the tested electric machines In these variants of the mutual loading systems the transfer coefficient of the angular velocity k ω is always lesser than unity [2].
In the Fig. 7 it is qualitatively presented the dependence nature for the case of divergence of the magnetic characteristics of the tested electric machines ( Ф 0 ∆ ≠ ).

Originality and practical value
For the first time the concept was introduced and the principles of regulation of unbalanced electromagnetic torque in the systems of mutual loading for electric machines of direct and pulse current were considered.Analytical expressions for the unbalanced electromagnetic torque for mutually loaded electric machines, the use of which will facilitate the development of control algorithms for testing stands of the traction electric cars of rolling stock of mainline and industrial transport were obtained.

Conclusions
Unbalanced electromagnetic torque of mutually loaded traction electric machines provides an unbalanced electromagnetic power needed for the implementation of electric method to cover the idling losses in the electric machines under study.
Regulation of unbalanced electromagnetic torque of mutually loaded traction electric machines can be realized by changing the difference of armature current, the difference of magnetic fluxes and the difference of the rotation angular velocities of electric machines armatures.
At the mutual loading of electric traction machines with divergent magnetic characteristics a broader range of regulating the magnetic fluxes of the machines under study is required.
Ключевые слова: тяговые электрические машины; испытание; взаимное нагружение; электромагнитный момент; регулирование P -are electromagnetic powers of the tested generator and engine accordingly[5,9].c -is a constructive constant of the tested electric machines of the single type; г Ф , д Ф -are the magnetic flows of the generator and engine accordingly; г ω , д ω -are the angular rotation velocities of the generator and motor armature respectively; г I , д I -are the armature currents of the generator and motor respectively.

Fig. 1 .J
Fig. 1.Generalized universal scheme of mutual loading system At the electric method to cover the idling losses the regulation of unbalanced electromagnetic power эм P ∆ is reduced to the regulation of the unbalanced electromagnetic torque эм M ∆ and, as a result of the angular velocityи д ω .These parameters are interconnected by the equation [1]

Fig. 2 .
Fig. 2. The structural scheme of the angular rate regulationUnbalanced electromagnetic torque of the tested generator and motor, reduced to the motor shaft can be expressed as torque of the tested engine; k ω -is the coefficient of the angular velocity transfer of the gear P.

Findings
of the constant armature current I is graphically shown in the Fig.3.

Fig. 4 .
Fig. 4. The nature of the dependence of

Fig. 5 .
Fig. 5.The nature of the dependence of

Fig. 6 .
Fig. 6.The nature of the dependence of