RU2683596C9 - Inductor of linear induction machine - Google Patents

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to induction machines with open magnetic conductor and can be used for pumping, dosing and mixing of liquid metals and alloys in metallurgical smelting-casting production. Disclosed is open magnetic core with winding, phases of which are formed by coils arranged in different parallel planes, wherein slots, in which conductors of coil of one phase are placed, alternate with slots, in which conductors of coil of other phase are arranged, and sections of windings of different phases alternate in height, open magnetic core has 2pm of slots in the inductor active zone and two slots located outside the active zone at the edges of the inductor, and each section of the winding has two layers of coils.EFFECT: technical result consists in creation of inductor of linear induction machine for transportation, dosing and mixing of liquid metals with improved energy indicators due to reduction of harmful effect of pulsating flow, as well as with smaller weight and size.4 cl, 8 dwg

Description

The invention relates to induction machines with an open magnetic circuit and can be used for pumping, dosing and mixing liquid metals and alloys in the metallurgical smelting and foundry industry. For this purpose, flat linear induction machines with multiphase windings are usually used [1]. In practice, three-phase (m = 3) and two-phase (m = 2) windings are mainly used. To strengthen the magnetic field of an electric machine, the active sides of the winding coils are laid in the grooves of the ferromagnetic magnetic circuit (core).

The use of linear induction machines in the smelting and foundry industry has features. Due to the large gaps between the inductors of the machines and the molten metal, due to the presence of heat-insulating materials, it is necessary to allow a large linear current load of the windings. However, the current densities in the windings are limited due to difficult cooling conditions. Therefore, it is necessary to use multi-turn windings and lay their active sides in deep and wide grooves. Under these conditions, the implementation of the usual types of windings with numerous bends of the frontal parts in various planes becomes difficult. It is especially difficult to produce such windings for low-frequency installations (for example, MHD-mixers of aluminum melts have a current frequency in the winding of 0.3≤f <l, 2 Hz). Such a winding “breathes” under the influence of electromagnetic forces, and during operation, its insulation is frayed, which leads to the winding coming out of working condition.

These difficulties stimulated the development of windings, the coils of which have the simplest manufacturing technology and increased reliability in operation. The windings themselves are made of concentric coils, the conductors of which are bent to the wide side of the coil cross section.

Known three-phase and two-phase windings of inductors of a linear induction machine made of concentric coils of a flat rectangular shape.

So in [2], a linear induction machine was proposed, containing an open magnetic circuit with a three-phase winding, the phases of which are formed by identical concentric coils of a flat shape, which are divided in height into several sections and located on the rods of the magnetic circuit. The sectional design of the winding coils contributes to the creation of channels for free cooling (or forced air cooling), which allows the device to operate for pumping or mixing high-temperature liquid metals. This design of the linear induction machine also allows to reduce the width of the inductor by reducing the frontal parts of the coils and, if necessary, install it under the bottom of the bath of the furnace or mixer, without violating their strength characteristics.

Also known is an induction machine containing an open magnetic circuit and a two-phase winding of identical concentric coils located on the terminals of the magnetic circuit, with sections of the coils of one phase located on the first and third terminals of the magnetic circuit, and sections of the coil of the other phase located on the second and fourth terminals of the magnetic circuit [3].

The three-phase and two-phase windings of flat concentric coils located on the rods of the magnetic cores have relatively low winding coefficients [1, 4]. Therefore, inductors of linear induction machines with such windings have low energy and electromagnetic properties.

It should be noted that inductors with an open magnetic circuit create in the active zone, in addition to the traveling one, pulsating magnetic fields. These pulsating fields induce currents in the secondary medium (liquid metal), which lead to additional power losses, increase the asymmetric phase load. To suppress or compensate for the indicated pulsating magnetic field, it is proposed to coil the linear induction machine with the presence of compensating elements at the ends of the inductor that create the magnetizing force necessary to compensate for the pulsating magnetic field [1].

, (p - число пар полюсов, τ - полюсное деление). В [1] представлена трехфазная обмотка линейной индукционной машины с фазной зоной 60° (электрических) и расположением катушечных групп в двух плоскостях. Особенностью обмотки является наличие за пределами активной зоны компенсирующих элементов, электрические токи которых способны компенсировать вредное влияние пульсирующего магнитного потока. Роль компенсирующих элементов играют свободные стороны катушек, находящиеся за пределами активной зоны.Compensating winding elements must have currents equal at any time to half the sums of currents of the coil sides at the extreme pole divisions of the magnetic circuit, but with opposite signs. The action of the compensating elements is ideal if they are located at the boundaries of the active zone and have an infinitely small width. The length of the core in linear induction machines is

, (p is the number of pole pairs, τ is pole division). In [1], a three-phase winding of a linear induction machine with a phase zone of 60 ° (electric) and the arrangement of coil groups in two planes is presented. A feature of the winding is the presence outside the active zone of compensating elements, the electric currents of which are able to compensate for the harmful effect of a pulsating magnetic flux. The role of the compensating elements is played by the free sides of the coils located outside the core.

In [1], an induction machine with a two-phase two-plane winding is also presented, a feature of which is its winding into a “break-up”, that is, the coil sides are divided in half and the frontal parts of these halves are bent in different directions. Such a winding has a good winding coefficient, as well as a smaller transverse size of the inductor due to the smaller overhang of the frontal parts. In terms of operating efficiency and electromagnetic properties, three- and two-phase windings differ little from each other [5].

The disadvantage of the three-phase and two-phase two-layer windings of linear induction machines is the difference in the inductive resistances of the coils located in the lower and upper layers, which leads to asymmetry of the currents in the phases and poor cooling conditions.

Closest to the claimed is an inductor of a linear induction machine [6], containing an open magnetic circuit with a winding, the phases of which are formed by identical coils placed in different parallel planes. The grooves in which the conductors of the coil of one phase are placed alternate with the grooves in which the conductors of the coil of the other phase are placed, with each coil divided in height into several sections, and sections of the coils of different phases also alternate in height.

The disadvantages of the known inductor should include its large transverse dimensions due to the departure of the frontal parts and the absence of compensating elements that can reduce the harmful effects of the pulsating magnetic flux caused by the open magnetic circuit.

The basis of the invention is the creation of an inductor of a linear induction machine for transporting, dispensing and mixing liquid metals with lower mass and improved energy performance by reducing the harmful effects of the pulsating flow.

The problem is solved in that in the inductor of a linear induction machine containing an open magnetic circuit with a winding, the phases of which are formed by coils placed in different parallel planes, and the grooves in which the conductors of the coil of one phase are placed alternate with the grooves in which the conductors of the coil of the other phases, the winding is divided in height into sections, and sections of different phases are also alternated in height, according to the invention, an open magnetic circuit has 2pm grooves in the inductor core and two grooves, dyaschihsya outside the core on edges of the inductor, and each section has a two layer winding coils.

Preferably, in the inductor of the linear induction machine with m = 3, each section of the winding contains 3p-1 coils, covering three teeth of the magnetic circuit and placed in 6p grooves of the active zone of the inductor, and two extreme coils, covering two teeth of the magnetic circuit, if, in one in the layer of the section, one side of one extreme coil is located in one groove of the magnetic circuit outside the core, then in the other layer of the section one side of the second extreme coil is located in the other groove of the magnetic circuit outside of the core of the inductor.

Preferably, in the inductor of the linear induction machine with m = 2, each section of the winding contains 4p coils in contact with each other, covering two teeth of the magnetic circuit, while the contacting sides of the coils are located in the grooves located in the active zone of the inductor, and the non-contacting sides of the coils are located in the grooves located outside the active zone of the inductor, and if one coil covering the extreme tooth of the magnetic circuit is located in one layer of the section, then the second coil covering the extreme tooth of the magnetic circuit It located in another layer section.

For an inductor of a linear induction machine installed near a bath with liquid metal, the winding of each phase is made in accordance with the condition

L / R≤0.2 * 10 ^-7 γτ ² , where

L is the inductance, GN,

R is the active resistance, Ohm,

γ is the conductivity of the melt, 1 / Ohm,

τ - pole division of the inductor, m,

m is the number of phases

p is the number of pole pairs.

The implementation of the invention we consider the example of an inductor of a linear induction machine with a three-phase winding and with a two-phase winding.

The invention is illustrated by drawings, where in FIG. 1 schematically shows the inductor of a linear induction machine with a three-phase winding (m = 3, p = 1, the number of grooves per pole and phase q = 1); in FIG. 2 is a section AA of FIG. one; in FIG. 3 is a section BB of FIG. one; in FIG. 4 is a vector diagram of currents in a three-phase winding of an inductor. In FIG. 5 schematically shows the inductor of a linear induction machine with a two-phase winding (m = 2, p = 1, the number of grooves per pole and phase q = 1); in FIG. 6 is a section AA of FIG. five; in FIG. 7 is a section BB of FIG. five; in FIG. 8 is a vector diagram of currents in a two-phase winding of an inductor.

The inductor of the linear induction machine (Fig. 1) has an open magnetic circuit containing seven teeth 1 ₁ , 1 ₂ , ..., 1 ₇ and yoke 2. Between the teeth there are 2 pm=6 (p = 1) grooves 3 ₁ , 3 ₂ , ..., 3 ₆ in the core of the inductor and two grooves 4 ₁ and 4 ₂ located outside the core (open). In the grooves are sections of a three-phase winding, each section consists of two layers (section AA in FIG. 2 and section BB in FIG. 3). In one layer there is a coil 5 ₁ , covering 2 teeth 1 ₁ and 1 ₂ , a magnetic circuit and a coil 6 ₁ , covering three teeth 1 ₄ , 1 ₅ and 1 _{6 of the} magnetic circuit. In another layer there is also another coil 5 ₂ covering two teeth 1 ₆ and 1 ₇ , and a coil 6 ₂ covering three teeth 1 ₂ , 1 ₃ and 1 ₄ . One side of one coil 5 ₁ , covering 2 teeth of the magnetic circuit, is located in the left open groove 4 _{1 of the} lower layer, and one side of the other coil 5 ₂ , covering 2 teeth, is located in the right open groove 4 _{2 of the} upper layer, located outside the core of the inductor . The coils of each layer are wedged by wedges 7, and insulating inserts with holes that form the air channels 8 are usually installed between the winding layers. Smaller coils 5 ₁ and 5 ₂ connected in series (or in parallel) are connected to the same phase (for example, C ) three-phase voltage, the other two coils 6 ₁ and 6 _{2 are} connected to other phases (for example, B and A), respectively.

When connecting the inductor winding (coil 5_one, five₂, 6_one and 6₂) to the source of an alternating three-phase voltage (with a phase shift of 120 °) in the conductors of the inductor winding (Fig.2, 3) there are alternating electric currents, a vector diagram of which is presented in Fig.4. In conductors in active slots 3_one÷ 3₆ electric currents are phase shifted relative to each other by 60 ° and change in time with an angular frequency ω,with^-one. In the region of the inductor core (l = 2рτ = 2τ), a traveling magnetic induction wave (traveling magnetic field) is formed. In conductors located in open grooves 4_one and 4₂ (outside the active zone of the inductor), the electric currents are shifted relative to each other in phase by 180 ° (figure 4). These currents create a pulsating magnetic field, the direction of which is opposite to the pulsating magnetic field caused by the open magnetic circuit of the inductor [1]. As a result of superposition of all fields near the inductor, a magnetic field appears that is close to the traveling one, that is, the amplitude of the normal component to the surface of the inductor of magnetic induction (Bz) will move in the x-axis direction with a speed V_one= 2τf,m / s,Where f = ω / 2π - current frequency, s^-one.

Sectional winding with air channels and the alternation of layers along the height of the groove allows you to cool it well and align the inductive phase resistance. The symmetry of the currents in the phases is also facilitated by the presence on the edges of the inductor of compensating elements that suppress a pulsating magnetic field in the active zone.

The inductor of the linear induction machine (Fig. 5) has an open magnetic circuit, consisting of five teeth of the magnetic circuit 1 ₁ ÷ 1 ₅ and yoke 2. Between the teeth are formed grooves 3 ₁ ÷ 3 ₄ located in the active zone of the inductor, and two extreme grooves 4 ₁ and 4 ₂ located outside the core. In the grooves 3 ₁ , 3 ₃ , 4 ₁ and 4 _{2 there} are three coils of each layer of the phase A winding, while the contacting sides of the coils are located in the grooves 3 ₁ and 3 ₃ located in the active zone of the inductor, and the free sides of the coils are located in the grooves 4 ₁ and 4 ₂ located outside the core of the inductor. In the grooves 3 ₂ , 3 ₄ , 4 ₁ and 4 _{2 there} are three coils of each layer of the phase B winding, while the contacting sides of the coils are located in the grooves 3 ₂ and 3 ₄ located in the active zone of the inductor, and the free sides of the coils are located in the grooves 4 ₁ and 4 ₂ located outside the core of the inductor. The winding of each phase has n layers, while the layers of different phases alternate at a height, the coils of each layer are wedged by wedges 7, inserts are installed between the layers of the winding of one phase, which form air channels 8 for cooling.

When connecting the winding (coils 5 ₁ , 5 ₂ , 6 ₁ ÷ 6 ₄ ) of the inductor (Fig.6, 7) to a two-phase voltage with a phase shift of 90 °, alternating electric currents will appear in the conductors of the inductor winding, the vector diagram of which is presented in Fig. 8 . In the conductors located in the grooves 3 ₁ ÷ 3 ₄ (active zone) of the inductor, the electric currents are shifted by 90 ° relative to each other and change in time with an angular frequency ω, s ^-1 . In conductors located in the open grooves 4 ₁ and 4 ₂ (outside the active zone), the electric currents are phase-shifted relative to each other by 180 ° (Fig. 8). All currents of the windings create a magnetic field close to the traveling one, the amplitude of the magnetic induction of which moves along the x axis with a speed of Vl = 2τf m / s.

When designing three-phase or two-phase inductors so that the condition L / R≤0.2 * 10-7γτ ^{2 is} satisfied, and connecting these inductors to a multiphase voltage of a rectangular shape, it is possible to increase the efficiency of a linear induction machine [7]. Here L is the inductance of the phase of the winding, GN; R is the active phase resistance of the winding, Ohm; γ is the conductivity of the melt 1 / Ohm⋅m; τ - pole division, m.

If three-phase or two-phase inductors are located near a bath with liquid metal and their windings are connected to the corresponding voltage system, then the traveling magnetic fields of the inductors will help bring the liquid metal into motion. A linear induction machine with one inductor can be used as an MHD-mixer of molten metal in melting furnaces and mixers, in this case, as a rule, the number of pole pairs is p = 1. A linear induction machine with two inductors can be used to transport liquid metals in flat channels, in this case, as a rule, the number of pole pairs is p> 1.

Thus, by reducing the outflow of the frontal parts, the transverse size of the inductor is reduced, and this, in turn, will increase the reliability of metallurgical equipment (for example, a melting furnace, mixer).

Information sources

1. Voldek A.I. Magnetohydrodynamic induction machines with a liquid metal working fluid. L .: "Energy", 1970. - 272 p.

2. RF patent No. 118485, cl. H02K41 / 025. Inductor of a linear induction machine. Application No. 2012107917/07, publ. 07/20/2012, BI No. 20.

3. RF patent No. 109615, cl. H02K41 / 025. Inductor of a linear induction machine. Application No. 20111214781/07, publ. October 20, 2011, BI No. 29.

4. Voldek A.I. Electric cars. Textbook for students of higher technical institutions. Ed. 2nd rev. and add. L .: "Energy", 1974, 840 p.

5. Timofeev V.N., Khatsyuk M.Yu. Analysis of electromagnetic processes of magnetohydrodynamic mixing of liquid metals. Electricity, 2017, No. 1, p. 35-44.

6. RF patent No. 1899507, cl. Н02К41 / 025. Inductor of a linear induction machine. Application No. 4765258/07, publ. 04/15/1993, BI No. 14.

7. RF patent No. 2524463, cl. F27D 27/00, B01F 13/08. Induction installation for mixing liquid metals. Application No. 2012116779/02, publ. 07.27.2014, BI No. 21.

Claims (11)

1. The inductor of a linear induction machine, containing an open magnetic circuit with a winding, the phases of which are formed by coils placed in different parallel planes, and the grooves in which the conductors of the coil of one phase are placed alternate with the grooves in which the conductors of the coil of the other phase are placed, the winding is divided into sections and sections of different phases alternate in height, characterized in that the open magnetic circuit has 2pm grooves in the core of the inductor and two grooves located outside the core at the edges of the inductor, and each with The winding section has two layers of coils. 2. The inductor of a linear induction machine according to claim 1, characterized in that for m = 3 each section of the winding contains 3p-1 coils, covering three teeth of the magnetic circuit and placed in 6p grooves of the inductor core, and two extreme coils, covering two the magnetic core, and if in one layer of the section one side of one extreme coil is located in one groove of the magnetic circuit outside the active zone, then in the other layer of the section one side of the second extreme coil is located in the other groove of the magnetic circuit outside the active zone of the inductor. 3. The inductor of the linear induction machine according to claim 1, characterized in that, for m = 2, each section of the winding contains 4p coils in contact with each other, covering two teeth, while the contacting sides of the coils are located in grooves located in the active zone of the inductor, and the non-touching sides of the coils are located in grooves located outside the active zone of the inductor, and if one coil covering the extreme tooth of the magnetic circuit is located in one layer of the section, then the second coil covering the extreme tooth of the magnetic circuit is laid in another layer of the section. 4. The inductor of a linear induction machine according to paragraphs. 2 and 3, installed near the bath with liquid metal, characterized in that the winding of each phase is made in accordance with the condition L / R≤0.2⋅10 ^-7 γτ ² _, where L is the inductance, GN, R is the active resistance, Ohm, γ is the specific electrical conductivity of the melt, 1 / (Ohm⋅m), τ - pole division of the inductor, m, m is the number of phases p is the number of pole pairs.

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