Coil for magnetic system of stator of salient-pole electric machine

FIELD: electric engineering and electro-mechanical industry, in particular, features of design of coils with salient poles for rectangular stators of salient-pole electric machine.

SUBSTANCE: in the coil for magnetic system of stator of salient-pole electric machine with rectangular poles, made by winding of flat rectangular cross-section bus onto narrow rib and containing elements of body and coil isolation with monolithic realization of working part of coil, in accordance to invention, on frontal parts of coil air gaps are provided between coils, expanding in wedge-like fashion in axial direction from the end of magnetic-duct of pole, in gaps between coils in longitudinal symmetry plane of coil distant inserts are installed made of solid isolating material with shape and dimensions, corresponding to gaps between coils in this plane, and with width substantially lesser than width of pole, connected by gluing to surfaces of adjacent coils, a packet of structural elements, consisting of frontal parts of coil rings and distant inserts between them, is fastened in longitudinal symmetry plane of the coil by bandage of non electro-conductive material, resistant to stretching, aforementioned inserts being of orthogonally symmetric H-like form with height of bar, equal to width of bus, and with common height, exceeding it by double bandage thickness, aforementioned bandage being positioned between shelves formed by aforementioned method. Due to such characteristic feature, all four sides of rectangular cross-section of each conductor within limits of frontal part of coil form surfaces, directly cooled by blowing air or liquid, correspondingly to scheme of theoretically full usage of external surface of conductors for their cooling.

EFFECT: increased efficiency of electric machine, increased density of current in windings, resulting in improved mass-dimensional characteristics of electric machine, decreased temperature of windings, and, thus, increased lifetime of isolation, allowing to use isolation of lesser heat resistance which is therefore cheaper or more technologically accessible.

8 cl, 10 dwg

 

The invention relates to electrical engineering and for the design of the coils of the poles of the rectangular stator salient-pole electrical machines.

This development refers to the construction of pole coils made by winding a flat tire rectangular cross section on a narrow edge.

Known coil magnetic system of the stator salient pole electric machine with poles of rectangular shape, made gapless winding flat tires rectangular cross section on a narrow edge. They are applied widely. In particular, a vast area of application, the coils of the magnetic poles of the stator systems traction commutator DC motors. For additional poles such design of the coils for many decades is almost always (Alekseev AE Traction motors. M, Transgenderist, 1951. Pp.232, Fig, b).

The main advantage of the coils from the winding of the flat tires on the narrow edge - thermal: almost the same conditions for all cooling coils, regardless of their number, the ratio of the cross section of the pole and the cooling scheme. Only in extreme turns the heat sink slightly increased.

The design of such coils is simple. For long narrow poles it has a clear and large layout and energy (in particular, the losses of bullets the purpose stray fields) advantages in comparison with coils, made by winding a flat tire on the wide edge. This is determined by the mass application of additional poles of traction motors: currently, the direct current motors of the traction electric drive systems for electric locomotives and diesel locomotives are hundreds of thousands of such coils.

However, coil, perform gapless winding flat tires rectangular cross section on a narrow edge, have important structural and technological disadvantage. When unhampered the bend bus as its thickness increases from the inner side of the coil throughout the length of the curve and decreases from the outside. Because of this, to ensure the compactness of the coil is necessary to take special measures (see, for example, in the above book Aeaiaciia, pp.232)that formed by bending trapezitinae the cross section of the tire turns the frontal part of the coil to convert at least a thickened part of the section to the size of a thickness equal to that of negoti tires the working side of the coils. This increases the cost of the product. Not provided the exact restoration of the geometry of the cross section of the tire along the planes of contact of the coils, resulting in poor working conditions turn-to-turn insulation. But on a tight bend to keep the cross-section curved round the same as the direct bus, yet.

Known monolithic coil of the type in question, in which some the e increase of the total heat removal from the coil is achieved through the development of its surface windshields parts by performing them in the form of polution rectangular radial cross-section (see, for example: Alekseev AE Design of electrical machines. M.-L., Gosenergoizdat, 1953. Str, Fig.10-10). However, this increase in heat is not proportional to a corresponding increase in the amount of copper in the coil, as in a monolithic frontal part of the ratio of fuel volume and directly cooled surface of its elements are changed only at the expense of appearing at this, open the inner surface of the half.

At the same time polutropos embodiment windshields parts monolithic coils wound flat tire with a bend on a narrow edge, has only two valuable features:

a) the largest possible for a given tangential dimension of the coil radius flexible bus and respectively the lowest distortion profile tires curved part;

b) due to the absence of the frontal part of the straight section of the circuit of the coils is greatly simplified technology of flexible (see, for example, with the design of the pole on is in this book Aeaiaciia "Design ...", str).

This stimulates the search for ways to improve thermal qualities of this form windshields parts.

In particular, it is the proposal to increase directly cooled surface of polutropos the frontal part of the coil of the type in question performing the alternating number of coils acting on the evom the machine direction (Alekseev AE Design ... (see above). Str, Fig.5-36). The complexity of the technology of such coils cannot be justified structurally limited by the condition of conservation of solidity) and therefore a slight increase in surface cooling. Because of this, the specified variant of development of the surface to be cooled windshields parts polutropos type of wide application not found. Coils politologie nose parts are still being used primarily in the simplest scenario, with smooth monolithic rectangular torus.

The latest example of the coils with nose pieces simple polutropos type (with all the inherent disadvantages - see above) - in the engine STI-350 system REED (Shcherbakov VG, Pavlyukov V.M., Zakharov V.I. Induction traction motor for electric trains. Options, design features. WPI. higher education institutions. Electrician, 2000, No. 3. P. 58). The design of the electromagnetic system of this engine is thoroughly tested and can be recognized as the best known. This, along with the high score of the engine, this in this work, allows you to accept its coil of stator poles as a structural prototype of the claimed device.

The objective of the invention is the provision of a sharp increase in heat removal from the frontal parts polutropos type coil pole rectangular shape is the commutator magnet electric machine, made by winding tires rectangular cross section on a narrow edge, through the development of simple design and technological measures the surface to be cooled. At the same time due to the high thermal conductivity of copper is provided by the increase of heat from the conductors not only the frontal part of the coil, but its working part, i.e. in the car as a whole.

This allows (together or alternative):

a) to increase the current density in the windings and thereby improve the overall dimensions of the machine;

b) reduce the temperature of the windings and thereby

to increase the service life of isolation

- apply insulation less heat resistant and therefore cheaper or technologically available,

- to increase the efficiency of the machine.

The solution of the invention is achieved by performing the frontal part of polutropos type coil with gaps between all the turns, wedge-shaped radiating in the axial direction from the end pole of the magnetic circuit, providing the necessary stable form of the frontal part of the remote coil spacers between the coils installed in the longitudinal plane of symmetry of the coil.

Thanks to such General distinguishing features of all four sides of the rectangular cross section of each conductor within the frontal part of the coil form directly cooled purge air or what incostly surface, which corresponds to the diagram theoretically limit the use of the outer surface of the conductors to cool.

In accordance with this development and above the General principle of increasing the cooling surface of the frontal part of polutropos coil type magnetic system of the stator salient pole electric machine with poles rectangular shape made by winding a flat tire rectangular cross section on a narrow edge, containing the elements of the Cabinet and winding insulation with a monolithic implementation of the working part of the coil, the problem is practically solved by the fact that:

a) on the end parts of the coil is provided by air gaps between the coils, a wedge extending in the axial direction from the end face of the magnetic pole;

b) in the gaps between the coils in the longitudinal plane of symmetry of the coil installed the spacer of solid insulating material with a shape and size corresponding to the gaps between the coils in this plane, and a width substantially less than the width of the pole connected by bonding with the surfaces of adjacent coils;

in the package of structural elements, consisting of the frontal parts of the turns of the coil and remote gaskets between them, sealed in the longitudinal plane of symmetry of the coil supporter of strong stretching of electrop the aqueous material;

g) these gaskets are made orthogonal symmetrical H-shaped with the height of the crossbar, the width of the tire, and with a total height of more of it to double the size of the thickness of the brace placed between educated in this way the tabs.

Given the General definition of the inventive device allows a number of useful private options. The main of them can be combined in the following groups:

a) in the form of coils windshields parts and fastening the coils remote gaskets:

- turns head-frequently made flat, and the spacer between them are wedge-shaped;

- lots of flat coils windshields parts most remote from the magnetic circuit made with the limb relative to the lines of bending perpendicular to the longitudinal plane of symmetry of the coil and intersecting at a distance from the most remote from the magnetic point turns, not smaller width tires, and bend, providing mutual parallelism of all educated in this way the surfaces of these sections of adjacent coils, between which there is a flat spacer;

b) for use in tire cover different types:

the coil is made of uninsulated (bare or with reisolation protective coating) tires with winding insulation plates of insulating mA is Arial, placed between the coils on the length of their contact and connected with them by gluing;

- open surfaces glabrous bus after complete Assembly of a coil covered with the insulation or reisolation protective coating (for example, by dipping method);

a coil made of insulated bus isolation which side in connection with such adjacent coils for electric strength in the equivalent winding, with the connection of the coils with each other in the length of their contact bonding;

C) using vnutrimashinnogo space for use according to this development of the proposed stratification windshields parts of the coil in two basic layout options:

- with the same performance of both end parts of the coil: with the limitation of the volume of the annular space with the outer diameter surface of the back yoke of the magnetic circuit of the stator and the inner diameter surface of the bore;

- when different execution windshields parts coil: with the limitation of the volume of the annular space, having both end parts of the same outer diameter surface of the back yoke of the magnetic circuit of the stator, and the inner diameter of these circular spaces in front of different parts: one windshields parts it is equal to the bore diameter of the magnetic circuit of the stator, the second less on the ports of the outdoor diameter of the magnetic rotor.

Figure 1 shows a General view of the frontal part of the proposed coil in the plan - option of individual structural elements of the winding insulation and bonding of flat coils windshields parts of the reel band with a wedge-shaped spacer bars between the coils;

figure 2 is the same as in figure 1, a longitudinal section (conditionally only on tires);

in figure 3, the spacer between adjacent coils in the end parts of the coil (view in plan);

figure 4 - same as figure 3, the spacer wedge, type in the profile.

figure 5 is a longitudinal section of a (conditionally only on tires) the frontal part of the coil, the option of individual structural elements of the winding insulation and bond with the limb turns windshields parts of the coil brace flat spacer bars between the coils;

figure 6 is a view in plan of the frontal part of the coil made according to figure 5 in the variant using the internal space of polution windshields parts for an additional increase in the cross-section of the pole speed narusheniami;

7 - geometric conditions of placement of the coil in the car with the execution of one of the windshields parts for internal overall limitation on the diameter of the bore of the magnetic circuit of the stator, and a second diameter less than the outer diameter of the magnetic rotor and radially symmetric stratified and; arrow V indicates the direction of movement of the cooling air in the interpolar slots reactive rotor;

on Fig geometrical conditions of placement of the frontal part of the coil with internal dimensions of the limit diameter less than the outer diameter of the magnetic rotor and radially asymmetric segregation (design flat outer coil);

figure 9 plots the loss of surface direct expansion coils of the frontal part of the coil in the area of the main bending;

figure 10 - the geometrical characteristics of the approximate losses of the direct cooling of the surface.

The offered coil is made in the form of a helical spiral formed by the continuous winding of the tire 1 of rectangular cross-section on the narrow edge (figure 1) with the gaps between the coils on the rectilinear working section 2 of the coil integral-filled winding insulation 3, with wedge-shaped widening gaps in the frontal portion forming an axial-tangential channels 4 for the passage of cooling air, and Cabinet insulation 5 of the working part 2 coils (figure 2). Shows a layout option, the most efficient in a large (more than 2) the ratio of the axial and tangential dimensions of the cross section of the pole 6 of the magnetic circuit of the stator, characteristic of the poles of the magnet electrical machines with poles rectangular is the first form of the mass application - traction motors (see above): with the design of the frontal part of polutropos type and location of the centers Of curvature of bending of the coils in the vicinity of the end face 7 of the pole 6.

To ensure the stability of the shape of the frontal part of the coil as a spatial mechanical systems,

a) in the gaps between the coils in the longitudinal plane of symmetry of the coil installed the spacer 8 (3 and 4) of the solid insulating material (e.g. fiberglass) with the shape and size of the profile corresponding to the gaps between the coils in this plane, and a width of Sdsignificantly less than the width Smpole 6 of the magnetic circuit of the stator (1), and listed the spacer 8 are connected by bonding with the surfaces of adjacent coils;

b) package of structural elements, consisting of the frontal parts of the turns of the coil to the remote gasket 8 between them, optionally bonded in the longitudinal plane of symmetry of the coil brace 9 of durable tensile electroconductive material, for example, of the type SAM (fiberglass anisotropic material);

C) these spacers 8 are orthogonal symmetrical H-shaped in plan form with a height of hdthe crossbar 10, equal to the width of a tire 1, and the total height H greater than the width and tires 1 to double the size of thickness hBbandage placed between educated specified by the protrusions 11; in coils, flat coils stratified frontal part (Fig 1 and 2) gaskets 8 are wedge-shaped (figure 4) with the angle of the clinoid shape ϕequal to the angle stratification ϕp1(figure 2); when the limb end parts of the coils (figure 5) the spacer 8 flat (ϕ=0).

In the latter case, the most remote from the end face 7 of the pole 6 of the magnetic circuit of the stator sections of flat coils windshields parts made with the limb relative to the lines of bending perpendicular to the longitudinal plane of symmetry of the coil and intersecting at a distance from the most remote from the magnetic point turns, not smaller width and bus 1, and bend, providing mutual parallelism of all educated in this way the surfaces of these sections of adjacent coils, which creates the possibility of using this site flat remote gaskets 8.

Large and indisputable advantage of this design solution (in comparison with the variation in the flat coils windshields parts of the coil - figures 1 and 2) in the extreme simplicity of obtain here monolith, due to the orthogonal pair included in the node details, especially when the mating surfaces of the coils parallel to the plane of the coil (figure 5). This ensures high quality of the otopleniya node and its reliability.

In addition, under comparable conditions (in particular, at the same radial dimensions of the thickness of the node), the angle of separation is higher than the similar angle ϕp1in the variant with flat turns and angle strips 8. Accordingly increases the cross-section of inter-turn channels 4 for the passage of cooling air and the heat in them from the copper to the air, which is especially valuable when multiturn coils.

Finally, if necessary, the maximum filling iron pole, 6 inner loop coils this is usually achieved by addition of rectangular cross-section pole 6 as step narushenii 12 placed in the inner space of polution windshields parts (6). In this case, the execution of end parts of the coil in figure 5 provides the best use of the total building solution frontal part of the pole 6 as a whole.

These features can be more important complication in this case, technology wiring of the coil: winding progressive unequal departure identical end parts of the coils and also different additional bending. However, spec. the equipment for these operations is known and easily. The increase in the consumption of copper (in comparison with the minimal structurally required when flat coils) and slightly teplotechna the Eski useful as it increases in the same measure surface direct cooling of the conductors of the frontal part of the coil.

Possible, of course, and structural inversion variants 2 and 5 longitudinal profile of the frontal part of the coils of the proposed type, namely:

a) constant - winding - flying turns the frontal part (as in scheme 2), but with a contour similar to version 5 and block Assembly remote pads 8 on the flat strips;

b) variable - winding - with the departure of flat coils of the frontal part (as in the scheme of figure 5), providing a constant distance from the inner surface of the coils to the end of the pole of the magnetic circuit, but without a subsequent lamina of coils and block Assembly remote strips 3 wedge-shaped gaskets (as in scheme 2).

Therefore, a reasonable choice of the form of delamination fronts of coils of this type can be made only comparative analysis of these options in the detailed design of the machine.

Stratification windshields parts polutropos types of coils made by winding pole bus on the narrow edge, can be implemented in vnutrimashinnogo space when used with the axial dimension l1(Fig.7 and 8) mechanical components - annular spaces of two types:

a) with an outer diameter of D1surface Spink the yoke of the magnetic circuit of the stator and an inner diameter of D 2its surface bore (space Ω1);

b) with an outer diameter of D1and an inner diameter of D3less of the outer diameter D4of the magnetic rotor (space Ω2, 7 and Ω3, Fig).

It is obvious that the installation of the rotor in the machine space of the second type (D3<D4) may be the limit for placements in him stratified frontal part of the coil on only one side of the machine and the length of the active part (magnet) rotor l3no more than the axial length (l2the magnetic circuit of the stator. Typically, this jet machine.

In the annular spaces of the specified second type delamination fronts of coils can have two basic forms:

a) a radially-symmetric space Ω2, Fig.7);

b) radially symmetrical (space Ω3, Fig).

In the first case, the restriction to symmetric development of stratification is the thickness of the back yoke of the magnetic circuit of the stator (the surface with diameter D1and the corresponding inner diameter D3). In the second case, technically the most appropriate execution with flat, parallel to the plane of the coil that is at least on the outer side of the magnetic coil in the frontal part and the development of stratification only in the direction of the rotor, which is ogranichivaetsya overall surface of the structure of this part of the rotor over a length l 1(for example, the diameter of the inner surface of the magnetic rotor 13, as shown in Fig).

The most common system of air cooling of electric machines of conventional type one-way purge has, as is well known, a major drawback: it is a significant temperature difference between the end parts of the coils opposite sides of the stator. On the output side of the air from the active part of the machine it is in some cases may be higher by tens of degrees.

To resolve this difference when only the total axial movement of cooling air through the machine cannot. Limit the service life of the winding insulation in the whole thermal aging of its most heated area (in this case, the frontal part of the stator winding on the output side of the cooling air from the machine or the adjacent area with the groove part)that causes a large underutilization of health isolate all of the rest of the winding (including grooved area) from the entrance of cooling air into the car.

When using the annular spaces of the second type in both considered forms - Ω2and Ω3the air flowing in the gap in the bore 14 and, more importantly, in the interpolar slots 15 jet rotor (Fig) intensively blows on the windshield side of the coils on the output. This creates a practical possibility to decrease the value of their temperature up to align with temperature in a similar point turns windshields parts from the entrance of the cooling air. In short machinesdue to the high thermal conductivity of copper, the temperature of the coils in their working parts are also significantly reduced.

The usefulness of the design of the coil according to the invention is ensured by its thermal efficiency and reliability as a mechanical system.

The coil of the proposed design as thermal system is determined by the mode of the current load and the cooling conditions. The analysis shows that in the coils of this type of replacement monolithic windshields parts stratified reduces the temperature of the winding at any load and any cooling conditions. The use of such coils is particularly useful when the topology of the aerodynamic system of the machine is provided as elements of a rational blow-off end parts of the coils. An example is the jet machine with salient-pole winding rotor. But in machines of other types of materials useful effect of the invention can and should be used.

Define criteria for the evaluation of thermal efficiency of the proposed device and give it a score.

In the calculations of the heating coils of electric machines have been widely used assessment for specific surface cooling

where A is the total estimated surface cooling coils, cm2;

Po- power losses in the winding from the operating current, W;

Pd- additional losses in the conductors of the coil, W,

ie α - the cooling surface in cm21 watt losses (Kurbatov SR Electric DC machine. M.-L., Stud. ed., 1928. Str).

However, criterion (1) contains not only one of the parameters of the design of the coil as thermal object, but also the energy parameters of its current load. Therefore, to evaluate thermal properties of the actual coil device as it appears imperfect.

More than seems reasonable, the total approximate estimation of thermal properties of the coils of electrical machines to perform using a geometric criterion value

where W is the total volume of fuel elements coil, cm3.

At constant along the contour of the pole cross-sectional area of the wire of the coil group (or its part) evaluation, similar to the criterion (2) (and numerically identical with it - see below), can be done by value

where S is the total perimeter of the cross section directly cooled conductors or monolithic group;

F their total area of the cross the wow section.

Compare on these criteria thermal properties of the proposed coil and prototype.

Suppose monolithic coil prototype made of tires rectangular cross section of width a and thickness b, is wound with a radius R on the narrow edge (see figure 1 and 2) and contains n turns.

The surface half of the frontal part of the coil

Ap=π(a+2R)(a+h)

where h=bn - height cross-section wire of the coil group;

(index "p" will celebrate the prototype, the index and the proposed coil);

the volume of the frontal part of

criterion (2)

criterion (3)

εpp.

We proposed according to the invention coil

Aand=π(a+2R)(a+b)n,

criterion (2)

criterion (3) (as prototype)

εandand.

This is an absolute assessment. As it follows from expressions (4) and (6), they physically represent the relationship of the perimeters of the sections to their areas:

for the prototype is the ratio of the total perimeter of the solid section and wiring group of the spool to its area (f-La (4));

for the proposed design solution is the ratio of the perimeter of the cross section of the individual conductor (bus) to its area (f-La (6)).

The same formula for the of asceta by the total cross-sectional area of the wiring group of the frontal part of the coil (f-La (2)) and its fuel volume (f-La (3)) indicate the possibility conventionally considered rusks area of the conductive coil section evaluation equivalent to its fuel volume.

To map thermal efficiency of the proposed coil and the prototype will introduce a comparative assessment

and pre-examine its information content as a function of the form E(n). Note: in both of the compared variants of the coils of the prototype and offer ("stratified" prototype) - the amount of heat emitting elements have the same (Vand=Vp- see above). Therefore, this comparison can be conducted directly on the ratio of surface cooling Aandand Apthat defines the same criterion (7).

Note, first, that the elements of the fraction (7) is the sum of the perimeters of the tires and wiring group and pauperised monolithic section. When the same total cross section of conductors comparison groups the relation (7) has a clear physical meaning: with increasing number of turns in the coil n thermal efficiency of the considered frontal part of the coil made according to the invention increases:

when n=1 compare technical solutions are equivalent,

when n>1 evaluation of E(n)>1.

This same conclusion and gives a formal analysis of the dependence (7):

since all values included in the formula, not negative. However, the intensity of this is th dependencies

with the growth of n dies, and the function (7) asymptotically approaches the limiting value

In a known construction of electric machines 5≤n≤25. Calculations show that for these values of n the proposed solution is always useful.

We will give numerical examples.

1. a=3.0 cm; b=0.5 cm; n=9 (real-coil design with "thick" - a/b=6<10 - bus). According to the formula (7)

the asymptotic value of the function F(n) for the specified section dimensions tyres (f-La (8))

i.e. in the coil opportunities to increase heat transfer by increasing the number of turns used a little more than half: utilization asymptotic limit

2. a=2.2 cm; b=0.2 cm; (rail thin: a/b=11>10); n=23 (stator coil traction engine-prototype).

the asymptote of the function (6)

utilization asymptotic limit

It is noteworthy that all received the final results of this part of the analysis do not depend on the radius of the flexible tire on the edge of R. This unexpected, at first sight, the fact contains ample opportunities DL the constructive-technological improvement proposed by coils of electrical machines of this type.

But the estimate is imprecise. They are obtained without loss of direct surface cooling in the proposed design of the coil, due to the use of remote pads and the contact turns in the bending area at the base is the main structural measures obtain stratified frontal part of the coil.

Consider the impact of these factors.

A. loss of remote gaskets consists of losses on each of the end coils

Bto=a(SB+Sd)+2bSB,

and each medium

Bwith=2aSd+bSB;

this determines the total losses in block

Ind=2Vto+(n-2)with

or in expanded form

Ind=2[(a+nb)SB+a(n-1)Sd].

For large n calculation Indcan be greatly simplified by the use of the formula

Ind=2n(aSd+bSB)

with absolute error

Δd=2a(Sd+SB),

ie, as the calculations show, very accurately.

Consider the function Ind(n) in a convenient format for analysis

where β - the relative size of the channel width in the remote laying under the bandage (figure 3):

Ratio

indicates a linear dependence of losses Indfrom Koli is estva of turns in the coil determines the physical meaning of the boundary of special cases:

β=0; this - bezandry remote strips in coil, performed only by gluing,

β=1; constructive variant with a bandage placed on the outer surface of the gasket, not having a channel for lateral fixation bandage (hB=0, figure 3):

Both of these options β practicable in the same manner as in the General case of 0<β<1. Their choice depends on the level of excellence available in the production technology of the monolith, metal-polymer structures.

Rate if lossdin the coil of the proposed type-based parameters coil-prototype (see above numerical example 2) and take βor=0.6; Sd=2.0 cm; R=4.0 cm (it is "cool" coil: ρ=R/a<2; large ρ relative losses directly cooled surface in the area of remote strips are much smaller).

By the formula (9)

Ind=2·2,0[2,2(23-1)+0,6(2,2+23·0,2)]=210 cm2.

The surface of the layered half of the frontal part of the coil (formula (5))

Andand=π(2,2+2·4,0)(2,2+0,2)23=1770 cm2.

The loss coefficient in the block remote pads

B. loss of direct cooling of the surface in the bending area of the coils of the frontal part of the coil at the second and consider n the basis of the example - diagram Fig.9.

This use case vnutrimashinnogo space on circuits Ω1(7) and Ω3(Fig). Here it is assumed: n=6; total angle stratification ϕ=π/4; bending radius of the reference bus at separation minimum: r=bgas usual for ductile metals; from the same bus will lead and coordinate the account i in the package, so that imax=n. Accept that here bgis the estimated overall tyre width that corresponds to the thickness of the isolated bus or naked, but with the output VideU insulation in the space of the frontal part. Stratification will be considered uniform: turn-to-turn angles bundle

Identified on the basis of schematic figures 9 General distribution pattern on one loss area directly cooled surface is determined for each coil Boisum of squares |Boi| zone of its contact with the adjacent coils:

where |Inoi|i-1- the area of contact between the i-loop (i-1)-round:

|Inoi|i+1- the same, (i+1)-round:

This determines deployed

or compact, convenient for analysis and calculations form according to (10)

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where b1and b2beyond the revolution number of the first constant of the coil:

The total losses of the square directly to the surface to be cooled in a pending application

ie, in particular, proportional to the angle stratification ϕ. However, despite the decrease in total surface direct cooling of the frontal part of the coil - increase ϕ, calculations show that increasing the heat it in a much greater extent than the reduction of heat sink indicated by the increasing loss of the cooled surface in the zone of the main bending coils. Therefore, the choice of angle ϕ loss of Boto serve as a limitation it is not practically possible.

When r=bg(see above assumptions) formula (14) finally becomes simpler:

where. In this most common case

so the total loss is proportional to not only the corner ϕbut the effective thickness of the bus bgthat, combined with the trivial proportion to the width of the tire defines a specified dependence on the square of the calculated cross-section of the bus (a·bgin General.

A specific feature of the recurrence relation (10) is bukowsical fictitious existence of zero (i=0) with a coil parameters similar to real (i≥1) turns: bth=r and ro=0. This stage defines the first term of the formula (10) for the first round in the form of a zero component (formula (11))

This is correct, but artificially obtained result.

In the General structure of the algorithm (10)-(12) the zero turn is symmetric logical analogue of (n-1)-round: it is the boundary elements of the i-sequence, beyond which the studied phenomenon disappears. As a consequence, their computing definition. So, the first round

the penultimate (front straight), i=n-1,

i.e. when r=bgthese results are identical:

In fact, such losses on the first turn no. However, as calculations, made this error when calculating the total loss here by the formulas (15)-(17) is small, and for multiturn coils is negligible (see below) and it can be ignored.

Will give a quantitative assessment of the considered losses in the sealing tires half the frontal part of the example coil prototype. As before, we assume a uniform stratification. Will take to calculate the overall thickness of the bus bg=0.25 cm > b=0.2 cm (i.e. including the winding insulation - see above) and ϕ=π/4 as in the diagram Fig.9.

The calculation by the formula (17) defines

Total surface area of the direct cooling of the layered coil of the prototype without losses Andand=1770 cm2(formula (5) and the above calculation of losses Ind).

The loss factor in the bending area of one and a half turns of the frontal part of the coil located at the

Fictitious losses on the first turn from zero (formula (11) amendment to General condition calculation r=bg)

in comparisons withdefines the relative error in the calculation of losses in this area according to the established procedure

ie is really negligible (see above).

Check for the considered numerical example of the relation (18)

confirms its correctness.

Round imthe greatest loss of the surface to be cooled B'omis determined by the solution of the equation

where im=11, and formula (16), which in this case

received:

The average loss for coils

<> C. the Total loss of the space directly cooled surface of the frontal part of the coil

their relative

ie 20%. Taking into account these losses, thermal efficiency of the stratification of the frontal part of the coil of the prototype being evaluated by the criterion (7) and pre-9 in numerical example 2, is determined by the ratio

This result is obtained by a detailed analysis of the geometric characteristics of the cooled surfaces of windshields parts polutropos type coil made by winding tires rectangular cross section on a narrow edge, shows: the objective of the invention is the provision of a sharp increase in the heat here in the coil solved, and the solution achieved by the development of simple design and technological measures directly cooled surface: angular separation windshields parts.

In approximate practical calculations the results of losses In close and accurate, can be obtained by calculating the ratio of total losses μ, (formula (20)) its approximate formula (numerical examples later on the same data)

where L is the estimated full arc length flat surface coils (figure 10):

p> Lin- estimated arc length total losses:

Lin=Sd+2Sabout=2,0+2·0,69=3,38,

So- arc length equivalent to the volume of half of the frontal part of the coil off of the direct cooling at the base of coils:

Without calculatingsize Soyou can determine the approximate electric formula

where large values of ksshould be taken for milovanovich (n<10) coils. So for the previously discussed numerical example with layered coil prototype

(cf.: So=0,69 cm);

for a geometric diagram Fig.9 (where bg=1.0 cm)

(the exact value 0,86).

Examples of other calculations show errors

computing the arc length Solosses by the formula (23) is immaterial.

Noteworthy: all types of losses (formulas (11)-(17)) is proportional to the width of the tire and, however, Soone of the most important characteristics of the losses from not depends. Let us show it.

In the accepted definition of Sabout(22) the average value of losses in coils (formula (19))

where

(see formula (17). But there

therefore, according to the formula (22)

and the function ƒin(i;n) value and does not contain. Therefore, Sofrom and not affected.

The high thermal efficiency of the proposed coil shown above theoretical analysis, it may be practically useful if it is guaranteed high reliability, as hard and durable mechanical system. Taken by itself stratification windshields parts polutropos type coil wound on a narrow edge, that as compared with the prototype worsens. Therefore, we consider the operation of this system in more detail.

A specific feature of the frontal part of the coil as the mechanical system is determined by two basic modes of loading:

a) the inertial forces generated by the vibration of the machine as a whole;

b) the internal electrodynamic forces of interaction of orbits arising from the action in the coil steady-state and in particular shock currents transient short circuit in the coil circuit.

The frontal part of the proposed coil, as the object of structural mechanics is a regular series of free flat arched elements made from the same rod of rectangular cross-section, along the axis of the bend has a width of up to 10 times smaller is its thickness. Geometric characteristics of the resistance to deformation of the bend on the main orthogonal axes of such section is dramatically different: the resistance difference is proportional to the ratio of sides, the moments of inertia - its square. So, for a typical bus 50×50 these ratios of 10 and 100.

The minimum stiffness of the elements of the frontal part winding coil deformation in the plane of symmetry determines the lowest frequency of free Flexural vibrations it produces are easily excited by resonance phenomena under the action of the respective components of the inertial forces. It is a known source of fatigue failure of cantilever elements of the windings in the frontal parts of electrical machines.

Electrodynamic interturn forces are here also in the plane of symmetry of the coil. They can be very large (see, for example, Rudenberg R. Transients in power systems, M., "Foreign literature", 1955, str-159, 167-177) and cause permanent deformation of the winding elements (usually made from plastic materials) to their contact, i.e. with education (at the bare bus) secondary foci KS - already in the car.

Finally, the coil with nose pieces polutropos type wound on the narrow edge of the tire rectangular (particularly "thin" - see above), released what assainies extreme package coils can be deformed due to the negligent attitude to the coil in the production, during storage and repair.

The remote gaskets installed in the meridional plane of symmetry of the proposed coil performs the essential function of ensuring the rigidity and strength of the frontal part of the coil, stratified according to the invention on a separate bus-conductors.

Link remote pad and bandage all bus-conductors of the frontal part of the coil in a monolithic rigid Central node radically changes its power circuit, which dramatically improves the frequency response of the system by mechanical vibrations and increases its load-carrying capacity. This identifies the site as an integral element of the claimed device, ensuring its practical performance and reliability.

1. The coil of the magnetic system of the stator salient pole electric machine with poles rectangular shape made by winding a flat tire rectangular cross section on a narrow edge with the design of windshields parts polutropos type, containing the elements of the Cabinet and winding insulation with a monolithic implementation of the working part of the coil, characterized in that the end parts has air gaps between the coils, a wedge extending in the axial direction from the end face of the magnetic pole, in the gaps between the coils in the longitudinal plane of symmetry of the coil installed the spacer and the solid insulating material with the shape and size of the profile, corresponding to the gaps between the coils in this plane, and a width substantially less than the width of the pole connected by bonding with the surfaces of adjacent coils, package of structural elements, consisting of the frontal parts of the turns of the coil and remote gaskets between them, sealed in the longitudinal plane of symmetry of the coil brace from high-tensile-electroconductive material, these gaskets are made orthogonal symmetrical H-shaped in plan form with the height of the crossbar, the width of the tire, and with a total height of more of it to double the size of the thickness of the brace placed between educated in this way the tabs.

2. Coil according to claim 1, characterized in that the coils windshields parts are made flat, and the spacer between them are wedge-shaped.

3. Coil according to claim 1, characterized in that the most remote from the end pole of the magnetic sections of flat coils windshields parts made with the limb relative to the lines of bending perpendicular to the longitudinal plane of symmetry of the coil and intersecting at a distance from the most remote from the magnetic point turns, not smaller width tires, and bend, providing mutual parallelism of all educated in this way the surfaces of these sections of adjacent coils, between which the flat spacer.

4. Coil according to claim 1, characterized in that it is made of uninsulated (bare or with reisolation protective coating) tires with winding insulation plates of an insulating material placed between the coils on the length of their contact and connected with them by gluing.

5. Coil according to claim 4, characterized in that the open surfaces of bare bus after complete Assembly of a coil covered with the insulation or reisolation protective coating.

6. Coil according to claim 1, characterized in that it is made of insulated bus isolation which side in connection with such adjacent coils for electric strength in the equivalent winding, with the connection of the coils with each other in the length of their contact pasting.

7. Coil according to claim 1, characterized in that the stratification its windshields parts made with restriction the volume of the annular space with the outer diameter surface of the back yoke of the magnetic circuit of the stator and the inner diameter surface of the bore.

8. Coil according to claim 1, characterized in that the stratification its windshields parts made with restriction the volume of the annular space, having both end parts of the outer diameter surface of the back yoke of the magnetic circuit of the stator, and the inner diameter of these circular spaces at one of the end parts is equal to the bore diameter magneto is the wires of the stator, the second is less than the outer diameter of the magnetic rotor.



 

Same patents:

FIELD: electrical and electromechanical engineering; large electrical machines, such as turbogenerators.

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21 cl, 20 dwg

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10 cl, 16 dwg

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17 cl, 7 dwg

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