RU2161361C1 - Induction machine - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: differentially compounded shunt circuit or differentially compounded series circuit is proposed for connecting two three-phase stator windings to squirrel- cage induction machine with variable turn number of three-phase windings in reverse sequence. Such electrical machine can be used for converting mechanical energy into three-phase electrical energy synchronized with that of external power supply and also for converting electrical to mechanical energy. It can run as motor and as generator in step with external three-phase power supply incorporating provision for desired power factor correction at permanently varying rotor speed. EFFECT: reduced nonlinear distortions of machine when running as generator, enhanced power factor and efficiency. 3 cl, 4 dwg

Description

 The invention relates to electrical engineering and can be used in other industries, for example, in wind energy and transport, both for converting mechanical energy into three-phase current electric energy strictly synchronized by an external source, and electric energy into mechanical.

Known asynchronous motor with a squirrel-cage rotor, the stator winding of which is connected by a triangle, and one of the three phases is connected rotated by 180 ^o and is equipped with additional adjustment [2].

 Known induction motor with squirrel-cage rotor, with an asymmetric connection of two three-phase stator windings [3].

 Known asynchronous motor with two multiphase windings of a two-section stator with the arrangement of sections of the magnetic circuits along a common rotor [1].

 The disadvantage of these devices is large nonlinear distortion in the generator mode, low cosφ and efficiency, poor synchronization with an external three-phase current source, there are no structural elements of the settings and tasks of the operating modes when changing the rotor speed [4].

 The purpose of the invention is the reduction of nonlinear distortion in the generator mode, increasing cosφ and efficiency, improving synchronization with an external three-phase current source, providing the necessary regulation of cosφ at constantly changing rotor speeds.

 This goal is achieved by the fact that in an asynchronous machine with a squirrel-cage rotor and two three-phase stator windings, a counter-parallel or counter-series connection of the phase stator windings is applied with a variable number of turns of the phase windings in the reverse sequence, and two particular cases of application in an asynchronous machine with squirrel-cage rotor and two windings of a single-section stator magnetic circuit and in an asynchronous machine with a squirrel-cage rotor and two-section magnetic circuit a stator, sections of which are arranged sequentially along a common rotor, and one of the sections of the stator magnetic circuit has the ability to rotate relative to the fixed section of the stator magnetic circuit. In both special cases, it is additionally envisaged to rotate one three-phase stator winding relative to the second three-phase stator winding for the necessary correction of cosφ.

Figure 1 shows a diagram of the anti-parallel connection of two three-phase stator windings of an asynchronous squirrel-cage machine, where the phases A ₂ , B ₂ and C _{2 of the} second are connected in parallel to the phases A ₁ , B ₁ and C _{1 of the} first three-phase stator winding three-phase stator winding, and a change in the number of turns of phases A ₁ , B ₁ and C _{1 of the} first three-phase stator winding leads to a change in the number of turns of phases A ₂ , B ₂ and C _{2 of the} second three-phase stator winding by the same number of turns, but in reverse sequence with subsequent fixation their desired ratio.

Figure 2 shows the scheme of the in-series connection of two three-phase stator windings of an asynchronous squirrel-cage machine, where the phases A ₂ , B ₂ and C _{2 of the} second are connected in series to the phases A ₁ , B ₁ and C _{1 of the} first three-phase stator winding three-phase stator winding, and a change in the number of turns of phases A ₁ , B ₁ and C _{1 of the} first three-phase stator winding leads to a change in the number of turns of phases A ₂ , B ₂ and C _{2 of the} second three-phase stator winding by the same number of turns, but in reverse sequence with subsequent iksatsiey their desired ratio.

 Figure 3 shows a special case of applying the circuit of figure 1 or figure 2 in an asynchronous machine with a squirrel-cage rotor and two three-phase windings of a single-section stator. On the shaft 1 there is a magnetic circuit 2 of a squirrel-cage rotor, and a stator 5 with a single-section magnetic circuit 4 and two three-phase windings 3 and 6, made so that the component parts of the windings are connected at their ends to the contact pads of the fixed circuit boards 7, and all the necessary connection of the components of the stator windings is the scheme of figure 1 or figure 2 is made by a certain position of the movable circuit boards 8 with their subsequent fixation. Moving boards 8 in addition to the circuit of figure 1 or figure 2 is installed and the necessary angular shift between the three-phase windings 3 and 6 of the stator.

 FIG. 4 shows a second particular case of applying the circuit of FIG. 1 or FIG. 2 in an asynchronous machine with a squirrel-cage rotor and two three-phase windings of a two-section stator magnetic circuit, the magnetic circuit sections of which are arranged sequentially along a common rotor, and one of the stator magnetic circuit sections has a device for turning relative to a fixed section of the stator magnetic circuit. On the shaft 1 there is a magnetic circuit 2 of a squirrel-cage rotor, and the stator 5 with a two-section magnetic circuit 4 and 9 has two three-phase windings 3 and 6, made so that the component parts of the windings are connected at their ends to the contact pads of the fixed circuit boards 7, and all the necessary connection of the components of two three-phase windings of the stator sections according to the scheme of figure 1 or figure 2 is made by a certain position of the movable circuit boards 8 with their subsequent fixation. The possibility of an angular shift between the three-phase windings 3 and 6 is provided using a device for continuous automatic control of the angle of rotation of the movable section 9 of the stator magnetic circuit relative to the fixed section 4 of the stator magnetic circuit 5.

The asynchronous machine with a squirrel-cage rotor and two three-phase connected counter-parallel stator windings works as follows in FIG. 1 as follows. It is included in the generator modes under load in a three-phase network, and phases A ₁ , B ₁ and C _{1 of the} first three-phase winding give a lagging generator current, and phases A ₂ , B ₂ and C ₂ give an additional compensating current. Higher harmonics are damped by countercurrents. The total current is strictly synchronized by an external three-phase current source.

The asynchronous machine with a squirrel-cage rotor and two three-phase connected counter-series stator windings works as follows in FIG. 2 as follows. It turns on in the generator mode under load in a three-phase network, and phases A ₁ , B ₁ and C _{1 of the} first three-phase stator winding give E.D. C. with a lag, and phases A ₂ , B ₂ and C ₂ give E.D.S. ahead of schedule. Higher harmonics are quenched, falling into opposite phases to each other. Total E.D.S. strictly synchronized with an external three-phase current source.

 The asynchronous machine of FIG. 3 operates in generator mode with a squirrel-cage rotor and two three-phase windings of a single-section stator, assembled according to the circuit in FIG. 1 or in FIG. 2 as follows. The shaft 1 of the rotor 2 is untwisted, and the desired ratio of the number of turns of the three-phase stator windings 3 and 6 is set using the movable boards 8. By the number of revolutions of the rotor 2, the necessary rotation angle between the three-phase is established by the movable circuit boards 8 or Fig. 2 windings 3 and 6 of the stator 5 through cosφ of an external three-phase network, where a strictly synchronized current is supplied, as in the scheme of FIG. 1 or FIG. 2. Turning a three-phase winding changes the cosφ of the generator current of this three-phase winding and adjusts the cosφ of the total generator current.

 The asynchronous machine of Fig. 4 operates with a squirrel-cage rotor and two three-phase windings of a two-section stator, the sections of the magnetic circuit of which are arranged sequentially along the common rotor, and one of the sections of the stator magnetic circuit has a device for turning relative to the fixed section of the stator magnetic circuit, assembled according to the diagram in FIG. . 1 or in FIG. 2 as follows. The shaft 1 of the rotor 2 is untwisted, and according to the number of revolutions of the rotor 2, the desired ratio of the number of turns of the three-phase stator windings 3 and 6 of the stator is set by the movable boards 8 and is included in the external three-phase network under load. In this case, the asynchronous machine in figure 4 gives a synchronized current to an external three-phase network, as in the circuit of figure 1 or in figure 2, by which it is assembled. The required angle of shift between the three-phase windings 3 and 6 of the stator sections 5 is set using a device for continuous automatic control of the displacement of the movable section 9 of the stator magnetic circuit relative to the fixed section 4 of the stator magnetic circuit 5, which in turn leads to a change in the cosφ of the generator current of the three-phase winding 6 and the cosφ of the total generator current.

Sources:
1. K. I. Schoenfer "Asynchronous machines", SEI, ML, 1938, p. 228, 229, Fig. 226, pp. 185-187, Fig. 177, Fig. 178, Fig. 179 and Fig. 180.

 2. "Asynchronous motor". THEM. Stone, A.S. N 92177 USSR 1950 M.C. H 02 B 17/12.

 3. "The method of asymmetric inclusion of the windings of a two-winding induction motor", and.with. N 76597 USSR for 1948

 4. A.I. Voldek "Electric machines" publishing house "Energy" Leningrad branch, 1974, p. 507-509 and p.590-592.

Claims (3)

1. An asynchronous machine with a squirrel-cage rotor and two three-phase stator windings, characterized in that the stator windings are connected so that the phases A ₁ , B ₁ , C _{1 of the} first three-phase winding are connected opposite-parallel or opposite-sequential phases A ₂ , B _2, C ₂ of the second three-phase windings, while the option of changing the number of windings of three-phase stator windings so that the change in the number of phases of the first three-phase windings causes a change in the number of phase windings of the second three-phase stator windings on the same chi layer of turns, but in reverse sequence with subsequent fixation of their desired ratio.  2. The asynchronous machine according to claim 1, characterized in that it is made with a single-section stator magnetic circuit, the stator windings are assembled from components connected at their ends to the contact pads of the fixed circuit boards, and all the necessary connections of the stator winding component parts are made by moving circuit boards with subsequent fixing at the same time, the possibility of the necessary angular shift of one three-phase winding relative to the other three-phase stator winding by the corresponding position of the movable boards is provided.  3. The asynchronous machine according to claim 1, characterized in that it is made with a two-section stator magnetic circuit, the sections of which are arranged sequentially along a common rotor, and one of the stator magnetic circuits has a device for turning relative to the fixed stator section, while the windings of two magnetic circuits stators are assembled from components connected at their ends to the contact pads of the fixed boards, and all necessary connections of the component parts of the windings are made by moving boards with their subsequent fi * FIG, and wherein is further provided with a device for continuous automatic control of the angle of rotation movable section relative to the fixed stator yoke section of the stator magnetic circuit.

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