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Vladimir, Russia

This article focuses on the use of speed characteristics in issues of the development of variable-speed induction motors. An algorithm for constructing a test electromagnetic calculation, which takes into account the influence of the main regulators of the control system and uses the basic design formulas and procedures of the known methods, is proposed. The algorithm solves the inverse problem concerning test electromagnetic calculation. Ways of using the proposed technique for the solution of practical tasks, which include the creation of speed characteristics, as well as finding the optimum power supply regime, are shown. Results of comparison of the design and experimental data are given. © 2015, Allerton Press, Inc.

Kruglikov O.V.,JSC NIPTIEM
Russian Electrical Engineering | Year: 2015

The main results of development of directly driven elevator machines carried out in 2008–2014 at JSC NIPTIEM are reported. Reasons are given for preferring to use a squirrel-cage induction motor in the low-speed variable-frequency drive of a gearless elevator machine. Algorithms for designing the active part of the motor and the elevator machine are presented. The importance of using experimental data to improve the calculation techniques and the parameters of the motors, as well as the necessity of mathematical simulation for designing variable-frequency motors, is shown. The basic technical and economic characteristics and the product range of directly driven elevator machines made by the Karacharovskii Mechanical Plant are reported. © 2015, Allerton Press, Inc.

Russian Electrical Engineering | Year: 2015

A new edition of IEC 34-2 part 1 laying out methods for determination of losses and electric engine efficiency, as well as demands placed on gauges, was introduced in September 2007. The method for determination of additional losses was published in the last edition of IEC, but missing in GOST (State Standard) 7217. The method is for carrying out tests for asymmetric power supply of asynchronous motors. The essence of the method lies in producing a reversely rotating field, which allows one to avoid experiments with reverse rotation. Supply voltage asymmetry is produced using an additional resistor connected with one of the phase. It is recommended to carry out the experiments with a cold engine to avoid overheating the winding due to asymmetry of phase currents. Linear voltages and currents, as well as power and skidding, are measured during the experiments. Data processing is reduced to determination of current and voltages of the direct and reverse sequence. A functional dependence of additional losses on the reverse sequence current is obtained, and the additional losses under the nominal regime are determined. Application of new test methods and determination of power efficiency will allow one to create prerequisites for increasing the technological level of modern low-voltage asynchronous motors. © 2015, Allerton Press, Inc.

Russian Electrical Engineering | Year: 2015

Features of control by electromechanical energy transformers with “hard” and “hauling” mechanical characteristics are considered. It is shown that the mechanical characteristics of direct-current motors with permanent magnets are “hard” and the speed is determined by not only the input voltage, but also the load moment. The mechanical characteristics of a direct-current commutator motor with series excitation are hauling in nature, and the moment is proportional to the square of current. Noncontact electromechanical energy transformers can have both hard and hauling mechanical characteristics, depending on the control methods. Electromechanical energy transformers in which there are no permanent magnets or exciting windings can operate with a constant flux of excitation with a hard mechanical characteristic or with a hauling mechanical characteristic under a change in excitation flux. In the last case, an energy-saving regime is implemented in the electromechanical energy transformers. It is shown that, to increase the accuracy of control systems with different electromechanical energy transformers, certain methods and control units need to be used. A functional diagram of control by electromechanical energy transformers with hauling electromechanical characteristics and compensation of load moment at a constant equivalent inertia moment is given. © 2015, Allerton Press, Inc.

Some properties of fractional single-toothed concentrated windings that contribute to their effective application in electrical machines have been considered. Small end windings allow making an electrical machine more compact in the axial direction, which makes it possible to use it in several applications: in motor-wheel drives, in a wind wheel power generator, in an elevator drive without room for a machine, etc. Fractional windings can significantly reduce the cogging torque of an electrical machine. This reduces the cogging torque, which is very important in wind energy, but at the same time it increases the smoothness and accuracy of positioning, which allows it to be used in special electrical machines. One of the drawbacks of the fractional single-toothed concentrated windings is a worse MMF harmonic content. With this in mind, application of a two-layer winding is to be preferred to that of a single-layer one. An example shows application of a fractional tooth concentrated winding in a synchronous engine with permanent magnets to drive the plunger pump used for oil production. The use of a two-layer winding instead of a single-layer one allowed reducing the eddy-current losses in the rotor by 3.7 times and avoiding unacceptable overheating of magnets. © 2015, Allerton Press, Inc.

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