RU2794201C1 - Magnetic system of an electric machine with a multilayer ultra-compact winding - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: devices for electromechanical power conversion. The device is a magnetic system of a three-phase synchronous electric machine with permanent magnets (2), a rotor (1), which can be located both outside the stator (3) and inside it. The stator (3) contains a distributed three-phase winding, the coils of which can be placed in slots 2, 4, 8, etc. of layers. The groove (4) of the stator (2) is open. The stator winding coils are made in such a way that the frontal parts have a rigid shape, and the working sections remain flexible and capable of deformation sufficient to ensure that the coil is immersed in the stator grooves without damaging the wire insulation layer.

EFFECT: increase in power efficiency, specific characteristics, as well as a simplification of production process and an increase in the reliability and durability of electrical machines.

5 cl, 21 dwg

Description

The proposed technical solutions and a group of inventions relate to electromechanical energy conversion devices.

There are many variants of magnetic systems of electrical machines with a lumped winding. This type of winding is described, for example, in the following patents: US6870292B2, US20170324307A1, US20160226346A1, US20160344246A1, US8664818B2, JP3603784B2, JP6079012B2, KR20170094261A, WO2241117, WO2241112 2, EP1727261B1, EP2306622B1, etc. A key feature of lumped-wound magnetic systems is that each coil winding is wound on a separate tooth in such a way that both sections of the coil are located in adjacent grooves.

Based on many scientific studies, it has been proven that the magnetic field created in the gap of electrical machines with a lumped stator winding has asynchronous spatial harmonics, which cause induction of eddy currents in the permanent magnets of the rotor, as well as pulsations of the electromagnetic torque, which leads to a decrease in the energy efficiency of such electrical machines . Also a big role in the design of magnetic systems with a concentrated winding is played by the shape of the tooth, which, as a rule, implies the presence of a characteristic pole piece. In accordance with this, the groove in the magnetic systems of electrical machines with concentrated winding is, as a rule, semi-closed, which greatly complicates and increases the cost of the winding procedure. In this case, the coils are wound directly on the tooth. In order to ensure low winding resistance, winding is most often carried out with a stranded wire (or several parallel conductors), which significantly reduces the packing density of the wire in the groove and, as a result, reduces the specific characteristics of the machine. In addition, this method of winding is quite difficult to automate and requires either the use of monofunctional expensive winding equipment, or the use of manual labor by a qualified specialist winder.

In connection with the foregoing, this application proposes the design of the magnetic system of electric machines with a distributed winding and an open slot. The three-phase distributed winding can be laid into the grooves of the stator of the magnetic system in 2, 4, 8, etc. layers. The coil winding pitch can be 2 or more teeth.

Known patents: US20140015348A1, WO2005050816A2 and US20140145540A1. In WO2005050816A2 and US20140145540A1, cases of magnetic systems with an external rotor are given, which is closer to the variant proposed in this application. In these prototypes, implementation options for a two-layer winding in magnetic systems with an open stator slot are presented. Such a groove geometry makes it possible to significantly simplify and reduce the cost of the winding manufacturing procedure. Prefabricated coils are immersed in the slots of the stator of the magnetic system. This method ensures the most dense filling of the groove with a winding wire. Due to the open shape of the groove, the procedure for covering the walls of the groove with an insulating layer is simplified, as well as laying insulation between coils belonging to different phases and located in the same groove, which increases the reliability and durability of the stator winding. Each coil has two sections: one section is located in the upper layer of the two-layer winding, the second - in the lower one. This method of laying is provided by giving the coils a special spatial geometry.

The disadvantage of the technical solutions proposed in the prototypes is that the coils of the two-layer winding are given such a geometry in which two sections of the same coil are located at different levels (in different layers). This leads, firstly, to the fact that the frontal part of such coils has a rather complex shape, which can be made only on special equipment, and secondly, the procedure for filling the groove with coils of this shape becomes more complicated. Patent WO2005050816A2 proposes the use of so-called shaped (formed) coils, which have a rather rigid shape. On the one hand, the rigidity of the form ensures the high quality of the coils: all conductors are laid in a strict sequence and the coil occupies the smallest possible volume. However, on the other hand, with this design of the coils, it becomes difficult to immerse them in the stator slots, since in radial flow machines the distance between any two slots inevitably decreases when moving from the edge of the stator to its axis. In this regard, in WO2005050816A2, a special shape of the groove is proposed, which assumes the presence of steps in the groove, due to which it becomes possible to immerse a preformed rigid coil into the grooves without its deformation. In order to immerse such a coil into the grooves, eight step-by-step actions are required. The technical solution proposed in WO2005050816A2 leads, firstly, to the fact that the procedure for manufacturing the stator winding becomes complicated and cannot be automated, and secondly, to the fact that the fill factor of the slot is reduced.

In this application, it is proposed to use a winding, each coil of which is made in a frameless way (preformed coils) in such a way that its end parts have a rigid shape, and the working areas remain flexible and capable of slight deformation, sufficient to ensure that the coil is immersed in the stator slots without damage. wire insulating layer. In this case, the coil has such a shape that both of its sections are located at the same distance from the axis of the engine. The proposed technical solution allows, while maintaining the most simple geometry of the stator groove of the magnetic system, to achieve the maximum possible filling of the groove with the minimum possible frontal part of the winding, without creating a risk of damage to the insulating layer of the winding wire of the coils when they are immersed in the grooves.

An essential feature of the group of inventions is the magnetic system of an electric machine, the stator of which has an open deep groove, and the stator winding coil is such that its frontal parts have a rigid shape, and the working sections remain flexible and capable of slight deformation, sufficient to ensure that the coil is immersed in the grooves of the stator without damaging the insulating layer of the wire, while the cross section of the coil in the working section located inside the stator groove has the shape of a rectangle and is equal to the section of the coil in the frontal part located outside the stator package, so that the height of the rectangular section in the working section of the coil is equal to the width rectangular section in the frontal part of the coil, and the width of the rectangular section in the working section of the coil is equal to the height of the rectangular section in the frontal part of the coil.

List of figures (drawings):

In FIG. 1 is an isometric sectional view of the device.

In FIG. 2 shows the appearance of the coil of the proposed geometry.

In FIG. 3 shows a top view of the coil.

In FIG. 4 shows a side view of the coil.

In FIG. 5 shows the first step of laying part of the coils in the stator slots in the first layer of the four-layer winding.

In FIG. 6 shows the orientation of coils C1Z1, A1X1, A2X2, B3Y3, C3Y3.

In FIG. 7 shows the second step of laying part of the coils into the stator slots in the first layer of the four-layer winding.

In FIG. 8 shows the orientation of coils B1Y1, B2Y2, C2Z2, A3X3, A4X4.

In FIG. 9 shows the final arrangement of a part of the coils laid in the first layer of a four-layer winding.

In FIG. 10 shows the result of laying a part of the coils in the second layer of a four-layer winding.

In FIG. 11 shows the orientation of coils C'1Z'1, A'1X'1, A'2X'2, B'3Y'3.

In FIG. 12 shows the orientation of coils B'1Y'1, B'2Y'2, C'2Z'2, A'3X'3, A'4X'4.

In FIG. 13 shows the first step of laying part of the coils in the stator slots in the third layer of the four-layer winding.

In FIG. 15 shows the second step of laying part of the coils in the stator slots in the third layer of the four-layer winding.

In FIG. 14 shows the orientation of coils C3Z3, C4Z4, A5X5, B5Y5, B6Y6.

In FIG. 16 shows the orientation of the coils B4Y4, C5Z5, C6Z6, A6X6.

In FIG. 17 shows the final arrangement of a part of the coils laid in the stator slots in the third layer of the four-layer winding.

In FIG. 18 shows the location of a part of the coils laid in the stator slots in the fourth layer of the four-layer winding.

In FIG. 19 shows the orientation of coils C'3Z'3, C'4Z'4, A'5X'5, B'5Y'5, B'6Y'6.

In FIG. 20 shows the orientation of coils B'4Y'4, C'5Z'5, C'6Z'6, A'6X'6.

In FIG. 21 shows a sketch of the magnetic system of an unwinding electric machine whose stator has 72 teeth and the number of poles is 32.

Figures 1 and 21 show a device that is a magnetic system of a three-phase synchronous electric machine with permanent magnets (2), a rotor (1), which can be located both outside the stator (3) and inside the stator. The stator (3) contains a distributed three-phase winding, the coils of which can be laid in slots in 2, 4, 8, etc. layers. The groove (4) at the stator (2) is open. The invention is applicable in traction electric motors, for example, those built into a vehicle wheel, in torque motors for driving various actuators, as alternators in power supply systems, including in the field of distributed and renewable energy, in linear motors and linear generators and other applications. The proposed design of the magnetic system and its electrical circuit make it possible to increase energy efficiency, specific characteristics, as well as simplify the manufacturing technology and increase the reliability and durability of electrical machines.

Figure 2 shows the appearance of a preformed coil of the proposed geometry, from which it is clearly seen that the section of the coil in the working area located inside the stator groove has the shape of a rectangle

Figures 3 and 4 show top and side views of the coil. The key feature of this coil is that the width of the frontal part is equal to the height of the working area of the coil b, and the height of the frontal part is equal to the width of the working area a. This geometry allows coils to be laid in one layer in such a way that the thickness of this layer does not exceed b. As can be seen from FIG. 3 at the coil, one base is flat, and the second is curly.

Consider an example of laying coils in the stator slots.

Before laying the coils, the stator slots are covered with a layer of insulation made of electrical cardboard, synthoflex or other suitable insulating material. The thickness of the insulation layer is determined by the operating voltage for which the electrical machine is designed.

In FIG. 5 shows the first step of laying part of the coils in the stator slots in the first layer of the four-layer winding.

In FIG. 7 shows the second step of laying part of the coils into the stator slots in the first layer of the four-layer winding.

In FIG. 9 shows the final arrangement of a part of the coils laid in the stator slots in the first layer of the four-layer winding.

Figures 6 and 8 show that the coils C1Z1, A1X1, A2X2, B3Y3 face the motor axis with a flat base, the coils B1Y1, B2Y2, C2Z2, A3X3, A4X4 face the motor axis with a figured base.

In FIG. 10 shows the location of part of the coils laid in the stator slots in the second layer of the four-layer winding. Note that the second layer of coils completely repeats the first layer, i.e., above the coil of phase A, which lies in the first layer, there is a coil of the same phase A, which lies in the second layer. Moreover, these coils are oriented in space in the same way. A similar condition is observed when installing coils in the stator slots in the second layer of the other two phases.

In FIG. 11 shows the orientation of coils C'1Z'1, A'1X'1, A'2X'2, B'3Y'3.

In FIG. 12 shows the orientation of coils B'1Y'1, B'2Y'2, C'2Z'2, A'3X'3, A'4X'4.

In FIG. 13 shows the first step of laying part of the coils in the stator slots in the third layer of the four-layer winding.

In FIG. 15 shows the second step of laying part of the coils in the stator slots in the third layer of the four-layer winding.

Figures 14 and 16 show the orientations of coils C3Z3, C4Z4, A5X5, B5Y5, B6Y6 and coils B4Y4, C5Z5, C6Z6, A6X6, respectively.

In FIG. 17 shows the final arrangement of a part of the coils laid in the stator slots in the third layer of the four-layer winding.

In FIG. 18 shows the location of a part of the coils laid in the stator slots in the fourth layer of the four-layer winding. Note that the fourth layer of coils completely repeats the third layer, that is, above the coil of phase A, which lies in the third layer, there is a coil of the same phase A, which lies in the fourth layer. Moreover, these coils are oriented in space in the same way. A similar condition is observed when installing coils in the stator slots in the fourth layer of two other phases.

Figures 19 and 20 show the orientations of coils C'3Z'3, C'4Z'4, A'5X'5, B'5Y'5, B'6Y'6 and coils B'4Y'4, C'5Z '5, C'6Z'6, A'6X'6 respectively.

In figures 5, 7, 9, 10, 13, 15, 17, 18 numbers of teeth are indicated. We assume that the groove to the left of the tooth has the same number as the tooth.

From figures 9, 10, 17, 18 it can be seen that in some grooves there are coils in four layers belonging to different phases, and in some grooves there are coils in four layers belonging to one phase. So, in the grooves numbered 1, 4, 7, 10, 13, 16 in the first and second layers and in the third and fourth layers there are coils belonging to different phases. Therefore, for these grooves, it is recommended to lay an insulation layer of electrical cardboard, synthoflex or other suitable insulating material between the second and third layers. In grooves 2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18 in the first and second layers and in the third and fourth layers there are coils belonging to the same phase. Therefore, in these grooves between the second and third layers, there is no need to lay a layer of insulation. In some cases, for example, when the operating voltage for which the electrical machine is designed is low, the insulation between the layers may not be laid in any of the grooves.

All coils belonging to the same phase can be connected in series. However, not all coils belonging to the same phase can be connected in parallel. Consider, using the example of phase C, possible ways to connect coils. Coils C1Z1 and C'1Z'1 can be connected either in series or in parallel. Similarly, coils C3Z3 and C'3Z'3 can be connected to each other in series or in parallel, and C4Z4 and C'4Z'4 can be connected to each other in series or in parallel. However, the common coil for C1Z1 and C'1Z'1 and the common coil for C3Z3 and C'3Z'3 and the common coil for C4Z4 and C'4Z'4 can only be connected in series. Also, coils C2Z2 and C'2Z'2 can be connected to each other both in series and in parallel, coils C5Z5 and C'5Z'5 can be connected to each other both in series and in parallel, and coils C6Z6 and C'6Z'6 can be connected to each other both in series and in parallel. However, the common coil for C2Z2 and C'2Z'2 and the common coil for C5Z5 and C'5Z'5 and the common coil for C6Z6 and C'6Z'6 can only be connected in series. Thus, we get two groups of coils: 1) C1Z1, C'1Z'1, C3Z3, C'3Z'3, C4Z4, C'4Z'4, and 2) C2Z2, C'2Z'2, C5Z5, C'5Z '5, C6Z6, C'6Z'6. These groups of coils can be connected to each other both in series and in parallel.

A similar rule for connecting coils applies to phases A and B.

Figures 9, 10, 17, 18 show the location of the stator coils, consisting of eighteen slots and teeth. Such an electric machine will have eight poles. If we continue to stack the coils in a symmetrical manner, we can get a stator consisting of 36 slots (this is a 16-pole machine), 54 slots (this is a 24-pole machine), 72 slots (this is a 32-pole machine), etc.

In FIG. 21 shows a sketch of the magnetic system of an unwinding electric machine whose stator has 72 teeth and the number of poles is 32.

The use of the proposed winding allows:

1. To increase the energy efficiency of electric machines with permanent magnets in comparison with the case of using lumped winding in such machines; the result is achieved by reducing the parasitic effect of some field harmonics, which leads to a decrease in eddy current losses in the permanent magnets of the rotor, as well as to a decrease in the ripple of the electromagnetic torque and, as a result, to a decrease in noise and vibration during the operation of the electric machine.

2. To increase the energy efficiency of electric machines with permanent magnets in comparison with the case of using lumped winding in such machines; The result is achieved by reducing the number of pole pairs in the electric machine and, as a result, the operating frequency of the current in the stator winding decreases when a given rotor speed is reached, which leads to a decrease in losses in the stator steel of the electric machine.

3. To increase the specific characteristics of electric machines with permanent magnets in comparison with the case of using lumped winding in such machines; the result is achieved by increasing the filling factor of the stator slot and, as a result, increasing the number of ampere-turns in each coil, the torque and the useful power of the electric machine without increasing its dimensions.

4. To simplify the technology of manufacturing stator windings of electric machines with permanent magnets in comparison with the case of using a lumped winding in such machines; the result is achieved by using an open stator groove, into which a coil pre-made on mandrels is immersed (in electric machine machines with a concentrated winding, the groove is half-closed, therefore it is not possible to immerse the entire coil in such a groove, it is necessary to stretch the coil turns along one conductor).

5. Increase the reliability and durability of electric machines with permanent magnets; The result is achieved by the fact that when prefabricated coils are immersed, in which the frontal parts have a rigid shape, and the working sections remain flexible and capable of slight deformation, no damage occurs to the insulating layer of the winding wire from which the coil is made (this avoids an early aging of the wire, increase its resource, as well as avoid insulation breakdowns and short circuits).

The advantages listed above apply equally to 2-, 4- and 8-layer windings.

In the case of organizing 2 layers in the stator winding, the size of the frontal part of the winding will be 27% larger than the size of the frontal part of the 4-layer winding and 47% larger than the size of the frontal part of the 8-layer winding, therefore, its resistance (compared to the case of 4- x or 8 layers) will be higher, which will lead to an increase in losses in the winding, however, in the case of a 2-layer winding, the complexity of manufacturing the winding is the smallest (since the number of coils is the smallest). That is, the fewer layers, the easier it is to manufacture, but the higher the Joule losses in the winding. 4 layers can be considered a compromise option (this option is presented in detail in the figures).

Claims (5)

1. A stator coil having frontal parts and working sections, characterized in that its frontal parts have a rigid shape, and the working sections remain flexible and capable of deformation sufficient to ensure that the coil is immersed in the stator grooves without damaging the insulating layer of the wire, while the cross section coil in the working section located inside the stator groove has the shape of a rectangle and is equal to the section of the coil in the frontal part located outside the stator package, so that the height of the rectangular section in the working section of the coil is equal to the width of the rectangular section in the frontal part of the coil, and the width of the rectangular section in the working section of the coil is equal to the height of the rectangular section in the frontal part of the coil. 2. The magnetic system of an electric machine, including a rotor with permanent magnets and a stator with an open slot and a three-phase winding, the coils of which are laid in the slots in an even number of layers, characterized in that both sections of each coil of the multi-phase multilayer stator winding are located in the slots of the stator pack with a pitch of at least two teeth in such a way that they are at the same distance from the axis of rotation of the rotor and are connected to the electrical circuit so that there are at least 9 stator teeth per 4 poles of the rotor, while each stator coil is made according to claim 1. 3. The magnetic system according to claim 2, characterized in that the coils are laid in grooves in 2 layers, 4 layers or 8 layers. 4. A method for increasing the reliability and durability of electric machines with permanent magnets, consisting in the fact that coils according to claim 1 are used, in which the frontal parts are rigid, and the working areas remain flexible and capable of deformation sufficient to ensure that the coil is immersed in the grooves stator without damaging the insulation layer of the wire. 5. A method for manufacturing stator windings of electric machines with permanent magnets, consisting in the fact that an open stator slot is used, into which coils pre-made on mandrels are immersed, each stator coil being made according to claim 1.

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