RU2277282C1 - Electrical machine armature winding - Google Patents

Abstract

FIELD: electrical engineering; low-power electrical machines running under severe switching conditions.

SUBSTANCE: electrical machine armature winding is wound of multiturn sections incorporating series-connected coils placed under all poles so that closest sides of adjacent coils are spaced one tooth pitch apart and any two adjacent coils are wound in opposite directions; coil number in section is greater than pole number; coils disposed under any pole are shifted along armature slots through one tooth pitch and are equally spaced apart on armature. Armature coil pitches under adjacent poles differ by one tooth pitch with odd number of slots and even number of coils per pole pair or with even number of slots and odd number of coils per pole pair. In case of even number of armature slots and odd number of coils per pole pair armature coil pitch is greater under pole wherein coil number is greater. The result is that coils of each section are distributed both under different poles and under separate pole thereby providing for greater number of section coils than pole number of electrical machine and, hence, section inductance is reduced. Essential part of active coil sides of each preceding section is disposed in this case in same slots as active coil sides of next sections thereby enhancing mutual magnetic coupling between adjacent sections.

EFFECT: facilitated switching of armature winding sections and enhanced damping properties of winding.

1 cl, 6 dwg

Description

The invention relates to electrical engineering, namely to the field of designing electric machines, and can be used in low-power electric machines with severe switching conditions.

Known is the anchor of a collector electric machine, containing a winding laid in grooves, including sections divided into separate coils with the same pitch, and at least part of the coils of each previous section is placed in the same grooves with the coils of subsequent sections (A.S. USSR No. 1489536, MKI 4 H 02 K 3/12).

The disadvantage of these windings is the relatively high inductance of their sections, since its decrease is limited by the maximum number of coils in the section, which can be placed in the grooves of the armature with a shift of the active sides of the same name relative to each other within the interpolar arc. Since the interpole arc decreases with an increase in the number of poles, the number of coils in the section also decreases, and the inductance of the sections increases.

The winding of the armature of an electric machine is also known, containing multi-turn sections, which consist of series-connected coils with an equal number of turns, with the number of coils in a section equal to the number of poles, the adjacent sides of adjacent coils are separated by one tooth division, the coils are symmetrically laid under all poles and the direction of winding of any two adjacent coils is opposite (A. s. USSR No. 1356131, MKI 4 H 02 K 23/26, publ. 30.11.87. Bull. No. 44).

This armature winding serves as a prototype of the invention.

The disadvantage of the considered winding is also the relatively high inductance of the sections, determined, ceteris paribus, by the number of coils in the section, which is limited here by the number of poles of the electric machine.

In addition, this winding has low damping properties, which depend on the number of active sides of the coils of the previous section, placed in the same grooves with the active sides of the coils of the subsequent section.

In the considered winding, only half of the active sides of the coils of each previous section can be placed in the same grooves with the active sides of the subsequent section.

The objective of the invention is to improve the switching sections of the armature winding by reducing the inductances of the sections, increasing the mutual magnetic bonds between adjacent sections and increasing the damping properties of the winding.

The problem is achieved in that in the winding of the armature of an electric machine from multi-turn sections, as well as in the prototype consisting of series-connected coils laid under all poles in such a way that the adjacent sides of adjacent coils are separated by one tooth division, and the direction of winding is any two adjacent coils is counter, according to the invention, the number of coils per pair of poles satisfies the condition

where N is the number of section coils per pair of poles;

Z is the number of grooves of the anchor;

ξ = α · p / π is the relative angular size of the pole piece;

α is the angular size of the pole piece along the bore of the inductor, rad;

p is the number of pairs of poles, while the coils located under a pole are shifted along the grooves of the armature by one tooth division and are made with the same step along the armature, and the steps of the coils along the armature under adjacent poles with an odd number of grooves and an even number of coils for a pair of poles and for an even number of grooves and an odd number of coils for a pair of poles differ by one tooth division, and for an even number of grooves of an anchor and an odd number of coils for a pair of poles, the coils below the pole under which the bol neck number of coils.

A distinctive feature of the proposed design of the armature winding is the increased (in comparison with the prototype) number of coils in the section per couple of poles, i.e. N> 2 (in the prototype N = 2).

The maximum number of active sides of the coils, which can be located in the interpolar space with a shift of one tooth division, is

Accordingly, the maximum number of coils in a section per pair of poles must satisfy the condition

Therefore, the number of coils in the section per pair of poles is selected within

2 <N≤1 + Z · (1-ξ) / (2-p).

Moreover, the placement of the active sides of the section coils located under any of the poles in different grooves of the armature reduces the inductance of the section.

In addition, the number of active sides of the turns of each previous section increases, placed in the same grooves with the active sides of the turns of the subsequent section, which leads to an increase in mutual magnetic bonds and an increase in the damping properties of the winding.

Thus, in the proposed winding, the anchors of the section contain a number of coils that are distributed both under different poles and under a single pole, so that their active sides are located within the interpolar arc during the switching process. Moreover, the number of coils in the section can be several times larger than the number of poles of the electric machine, and the active sides of the coils of the section are located in different grooves of the armature. This leads to a significant reduction in the inductance of the sections of the proposed winding compared with the prototype, since the inductance of the section decreases in proportion to the number of individual coils in the section, which can be increased several times here.

The proposed winding can, for example, be obtained by dividing the turns of the section into the number of coils, a multiple of the number of poles of an electric machine. Moreover, the coils located under the same pole can be made of the same width. After that, the first group of coils is placed in the grooves of the anchor, then the second group of coils is shifted relative to the first one tooth division in a given direction and also fits in the grooves of the anchor. The third group of coils is laid in a similar manner relative to the second group of coils, etc.

The next section of the proposed winding is performed in a similar way and fits with an offset of one tooth division relative to the first section (with one elementary groove in real).

The increase in the number of coils in the sections of the proposed winding compared with the prototype and their placement in various grooves of the armature not only reduce the inductance of the section, but also increase the damping properties of the winding, since this increases the proportion of active sides of the coils of any previous section lying in the same grooves with the active sides of the coils of the subsequent section.

Figure 1 presents the sections of the proposed winding with an even number of grooves of the armature and an even number of coils of equal width per pair of poles, in which the active sides are located within the interpolar arc during the switching process.

Figure 2 presents the sections of the proposed winding with an even number of grooves of the armature and an even number of coils of equal width per pair of poles, in which some of the active sides are located outside the interpolar arc during the switching process.

Figure 3 shows sections of the proposed winding with an odd number of grooves of the armature and an even number of coils of different widths per pair of poles.

Figure 4 presents the implementation of the sections of the proposed winding with an odd number of grooves of the armature and an odd number of coils of equal width per pair of poles.

Figure 5 shows sections of the proposed winding, in which an odd number of coils with different spacing per pair of poles with an even number of armature slots, with coils under the pole, under which more coils are placed, have a larger step along the armature.

Figure 6 shows sections of the proposed winding, in which an odd number of coils with different spacing per pair of poles with an even number of armature slots, with the coils under the pole with the smaller number of coils being placed at the greater step along the armature.

The proposed simple loop winding of the anchor in figure 1 is made in a bipolar electric machine with an even number of grooves at the anchor (Z = 14) in a two-layer design and with one elementary groove in the real groove of the anchor.

The first section of this winding consists of coils 1, 2, 3, 4, having the same pitch along the armature U ₁ .

The coil 1 lying in the grooves 9 and 14, and the coil 2 lying in the grooves 10 and 15, are located under the north pole (N) and are offset relative to each other by one tooth division. The coil 3 lying in the grooves 16 and 21, and the coil 4 lying in the grooves 17 and 22, are placed under the south pole (S) and are also offset relative to each other by one tooth division. The coils 1, 2, 3, 4 of the first section are connected in series and connected to the collector plates 23, 24. Moreover, the coils 1, 2 located under the north pole are connected counter to the coils 3, 4 located under the south pole.

The second section of this winding, consisting of coils 5, 6 and 7, 8, located respectively in the grooves 10, 15 and 11, 16, as well as in the grooves 17, 22 and 18, 9, is similar in design to the first section, offset from the last by one tooth division and is connected to the collector plates 24, 25. Thus, the number of coils in the section of the presented winding is twice as much as in the prototype winding, all other things being equal. Moreover, all the coils here also lie in different grooves. Therefore, the inductance of the section of the proposed winding is almost halved.

In addition, the active sides of the first section of the proposed winding, lying in the grooves 9, 10, 15 and 16, 17, 22, are placed together with the active sides of the second section. Therefore, the six active sides of the coils of the first section of eight lie with the active sides of the second section. Accordingly, the damping coefficient (Tolkunov V.P. Theory and practice of switching DC machines. - M .: Energy, 1979, p.108) of the proposed winding is approximately 0.44, whereas in the prototype winding it is 0, 75. Therefore, the damping properties of the proposed winding also surpasses the prototype winding.

For this winding, condition (1) is satisfied:

2 <N≤1 + Z · (1-ξ) / (2-p),

Indeed, here N = 4, Z = 14, p = 1, ξ = α · p / π = 0.424 (with α = 1.33). Then inequality (1) can be written as

2 <4≤1 + 14 · (1-0.424) / (2 · 1),

or

2 <4≤5.03.

Thus, condition (1) is satisfied, which ensures (when placing the brushes on the line of geometric neutral) the location of the active sides of the switched sections within the interpolar arc. At the same time, the effect of the field of the main poles on switching is significantly reduced, which can lead to a violation of the optimal nature of the flow of switching processes, especially in reversing machines.

So, for example, condition (1) is not satisfied in the armature winding in Fig. 2 (here N = 4, and (1 + Z · (1-ξ) / (2-p)) = 2.98), which differs from windings of the armature in figure 1 with a larger width of the pole piece (α = 2.25 rad). At the same time, the active sides of the first section, lying in the grooves 10, 14, 17, 21, are located in the field of the main poles, which is accompanied by the induction of rotation EMF from the main poles, and this, as mentioned above, can significantly impair the switching quality of the electric machine. In addition, with this ratio of the winding data of the armature and the geometric parameters of the inductor, the full use of the magnetic flux of the main poles is not achieved, which reduces the energy characteristics of the electric machine.

With a larger number of pole pairs in an electric machine, the number of coils in a section of the proposed winding increases in proportion to the number of pole pairs, and the section design remains similar to that discussed above.

If the number of grooves at the anchor is odd, the section coils lying under different poles can be made of different widths, as shown in Fig.3. Here, the coil 1, lying in the grooves 9, 14 under the north pole, and the coil 2, laid in the grooves 10, 15 also under the north pole, have an anchor pitch U ₁ , which is less than one tooth division of the pitch U _{2 of the} coils 3, 4. Coils 3 and 4, in turn, are located under the south pole and lie respectively in the grooves 16, 22 and 17, 23. The coils 1, 2, 3, 4 of the first section are connected in series and connected to the collector plates 24, 25.

The second section of the anchor consists of coils 5, 6, 7, 8, is made similar to the first section, laid in the grooves of the armature with a shift of one tooth division relative to the first section and connected to the collector plates 25, 26.

Thus, this armature winding with an odd number of grooves and an even number of coils per pair of poles under one of the poles has a coil pitch of section U ₁ smaller than the pitch of coils of section U ₂ under the other pole. Due to this, the winding in figure 3, made at anchor with an odd number of grooves, has technical properties similar to the properties of the winding in figure 1, made at anchor with an even number of grooves.

Condition (1) for the winding in FIG. 3 is also satisfied (2 <4≤5.43).

When the proposed winding (4) in a two-pole electrical machine with an odd number of grooves on the anchor at an odd number of coils of equal width on a pair of poles at the north pole are arranged with a pitch Y _1, the coil 1, laid in the grooves 7, 13, and the coil 2, located in the grooves 8, 14. The coil 3, laid in the grooves 15, 21 under the south pole, has a step U ₂ equal to the step U ₁ . The coils 1, 2, 3 of the first section are connected in series and connected to the collector plates 22, 23.

The second section, consisting of coils 4, 5, 6, is made similar to the first section and laid in the grooves of the armature with a shift of one tooth division and connected to the collector plates 23, 24.

Therefore, sections of this winding under one of the poles have a larger number of coils than under the other pole. According to its technical properties, the considered winding also surpasses the prototype winding with the same initial data, however, its switching properties are slightly lower than that of the winding in Fig. 3.

Condition (1) for the winding in FIG. 4 is satisfied (2 <3≤3.925). Moreover, in comparison with the winding in Fig. 3, the width of the pole piece is increased to 1.93 rad (1.3 rad in Fig. 3), which makes it possible to increase the energy characteristics of the electric machine.

When performing the proposed winding in a bipolar electric machine with an even number of grooves at the anchor and with an odd number of coils with different spacing for a pair of poles (Fig. 5), coil 1 lying in grooves 7, 13 under the north pole and coil 2 laid in grooves 8, 14 also under the north pole, have a step along the anchor U ₁ , greater by one tooth division than the step U _{2 of} coil 3. Coil 3, in turn, is located under the south pole and lies, respectively, in the grooves 15, 20. The coils 1, 2, 3 of the first section are connected in series and connected to the collector plates 21, 2 2.

The second section consists of coils 4, 5, 6, is made similar to the first section, laid in the grooves of the armature with a shift by one tooth division relative to the first section and connected to the collector plates 22, 23.

Condition (1) for the winding in FIG. 5 is satisfied (2 <3≤3.1). Moreover, in comparison with the winding in Fig. 1, the width of the pole piece is increased to 2.2 rad (1.33 rad in Fig. 1), which makes it possible to increase the energy characteristics of the electric machine. This was a consequence of the fact that, in comparison with the winding in Fig. 1, the number of coils per pair of poles decreased and coils were made with a large step along the armature under that pole, under which more coils are placed.

Figure 6 presents a similar winding of the armature, in which the last of the above conditions is not satisfied, i.e. coils under the pole, under which a smaller number of coils are placed, have a greater step along the anchor. Here, the coils 1, 2 of the first section have a step Y ₁ , which is less than the step Y _{2 of the} coil 3 by one tooth division. In this case, condition (1) is fulfilled, Fig. 5, however, the width of the pole piece is reduced to 1.34 rad, which affects the energy performance of the electric machine in comparison with the previous version of the winding.

Thus, the values of the steps of the coils along the anchor under adjacent poles with an odd number of grooves and an even number of coils per pair of poles (Fig. 3), or with an even number of grooves and an odd number of coils per pair of poles (Fig. 5, 6) should differ by one tooth division. Moreover, according to the invention, with an even number of grooves of the armature and an odd number of coils per pair of poles, the coils under the pole under which the larger number of coils are placed should have a larger step along the armature (Fig. 5).

The work of the proposed winding.

In the process of moving the collector relative to the brush, the latter first runs onto the collector plates 23, 24 (Fig. 1) and shorts the first section of the coils 1, 2, 3, 4. Then the collector plates 24, 25 are closed with a brush (more than one with a brush overlap) and the second section from the coils 5, 6, 7, 8 is shorted. After that, the collector plate 23 comes out from under the brushes and the process of switching the first section from the coils 1, 2, 3, 4 is completed. In this case, one part of the electromagnetic energy of the first section is transmitted by mutual magnetic communication second sections of coils 5, 6, 7, 8, and the other part is allocated in the air gap under the brush in the form of a spark discharge.

The low value of the inductance of the sections of the proposed winding reduces the amount of energy stored by them at the time of their opening by the brush, and the increased magnetic coupling of adjacent sections reduces the share of the stored energy of the sections released under the brush in the form of sparking. Therefore, the resulting amount of energy realized in the air gap under the brush in the proposed winding is significantly lower than in the prototype winding.

Calculations show that the amount of specified energy in the proposed winding in figure 1 or figure 3 is almost 3.4 times less than in the prototype with similar winding data.

Thus, the proposed winding can significantly reduce the switching voltage of the electric machine, increase the resource and reliability of its operation.

It is most preferable to use the proposed winding in low-power electric machines with severe switching conditions.

Claims (1)

The winding of the anchor of an electric machine from multi-turn sections consisting of series-connected coils laid under all poles so that the adjacent sides of adjacent coils are separated by one tooth division, and the direction of winding of any two adjacent coils is opposite, characterized in that the number coils for a pair of poles satisfies the condition: 2 <N≤1 + Z · (1-ξ) / (2 · p), where N is the number of section coils per pair of poles; Z is the number of grooves of the anchor; ξ = α · p / π is the relative angular size of the pole piece; α is the angular size of the pole piece along the bore of the inductor, rad; p is the number of pairs of poles, while the coils located under a pole are displaced along the grooves of the anchor by one tooth division and are made with the same step along the anchor, and the steps of the steps of the coils along the anchor under adjacent poles with an odd number of grooves and an even number of coils per pair of poles and with even the number of grooves and the odd number of coils per pair of poles differ by one tooth division, and with an even number of grooves of the anchor and the odd number of coils per pair of poles, the coils below the pole under which the larger number of coils are located have a greater step along the anchor.

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