Electric machine

Abstract

The invention relates to an electric machine having a stator (2) and a rotor (3), wherein the stator (2) has a stator core (4), which has slots (8) that are distributed along the circumferential direction (5) of the stator and run in the axial direction (6) and radial direction (7), and a winding assembly (9) running through the slots (8), and the winding assembly (9) has a plurality of electrically connected coils (14), the coils (14) comprising a first group of coils (15) which are provided in the slots (8) and are nested so as to form a first ring (16), some of the coils (14) of the first group (15) resting against one another. It is proposed that the coils (14) comprise a second group of coils (19) which are provided in the slots (8) and are nested so as to form a second ring (20) in such a way that some of the coils (14) of the second group (19) rest against one another, at least some of the coils (14) of the first group (15) resting against one another are insulated from one another by an insulation material (21) which is separate from the coils (14), and at least some of the coils (14) of the second group (19) resting against one another rest directly against one another.

Description

[0001] Electric machine

[0002] The present invention relates to an electric machine according to the preamble of claim 1, a use of an electric machine according to claim 12 and a method for manufacturing an electric machine according to the preamble of claim 13.

[0003] Electrical machines, especially motors and generators, typically consist of a rotor and a stator. This discussion focuses on electrical machines where the stator has a winding arrangement. Such winding arrangements have several coils arranged in slots of a stator core. It is common practice in such winding arrangements to insulate the coil wires with a material that may be applied directly to the wires. Over time, this insulating material can be damaged by vibrations. If two coils with a high potential difference (voltage difference) are then located close to each other, a short circuit can occur. Therefore, above a certain potential difference, additional, separate insulating materials are placed between the coils. Applying these separate insulating materials is a complex and often manual process.

[0004] The known prior art (EP 4 304 058 A1), from which the invention is based, relates to an electric machine according to the preamble of claim 1. In this prior art, an electric machine with a stator and a rotor is disclosed, wherein the stator has a stator core with slots distributed along its circumferential direction and extending in the axial and radial directions, and a winding arrangement extending through the slots.

[0005] The winding arrangement comprises several electrically connected coils, which, for clarity, will be referred to as the first group of coils in the following text. The coils are arranged in two layers within the slots and nested to form a first ring. Some of the coils in the first group are in contact with each other. Particularly in the area of ​​a winding head, the sections of the coils that connect two slots are, as is typical, positioned against each other.

[0006] In the known winding arrangement, a complex geometry was developed, in which the coils are nested into a ring, depending on the desired connection of the coils, specifically a two-strand star connection, in which no or almost no additional insulating materials are necessary.

[0007] One challenge is that not every circuit is suitable for such a geometry. For example, the familiar circuit cannot be used with circuits that have more than two external coils per phase directly connected to the phases. In other cases, greater flexibility is also desirable to optimize the magnetic field and torque ripple.

[0008] The invention is based on the problem of designing and further developing the known electrical machine in such a way that further optimization is achieved with regard to the aforementioned challenges.

[0009] The above problem is solved by the features of the characterizing part of claim 1.

[0010] The essential consideration is that a second group of coils can be nested to form a second ring, resulting in two at least partially separate coil groups that can be provided with different insulation measures.

[0011] Specifically, it is proposed that the coils have a second group of coils arranged in the slots and nested to form a second ring, that some of the coils of the second group are in contact with each other, that at least some of the in contact coils of the first group are insulated from each other by an insulating material separate from the coils, and that at least some of the in contact coils of the second group are in direct contact with each other. Claim 2 specifies possibilities whereby the coils of the first group, insofar as they are in contact with each other, are all insulated from each other, and / or whereby the coils of the second group are not insulated from each other, i.e., insofar as they are in contact with each other, are in direct contact with each other. At least for the phase-different coils of the first group, separate insulation is preferably provided when they are in contact with each other. The wire insulation that is nevertheless present is considered part of the coil.This variant is particularly easy to implement from a production standpoint. If the first group is insulated and the second is not, insulation material and work steps can be saved, while the probability of errors is low. This advantage also exists in some variants where only part of the first group is provided with separate insulation material, especially if this part is visually identifiable. However, if only specific coils are insulated from each other, and these can only be identified with expert knowledge, the susceptibility to errors increases.

[0012] In a preferred embodiment according to claim 3, the first group is arranged radially outside in the grooves and the second group radially inside. Such an arrangement allows for easy insertion of the coils.

[0013] The groups can be arranged in different grooves, particularly alternating (claim 4). This reduces the space requirement in the radial direction.

[0014] Claim 5 relates to preferred embodiments of the electric machine, in particular as a three-phase electric machine and / or with at least four, preferably at least eight, outer coils. The outer coils of different phases exhibit the greatest potential differences, so that separate insulation of these coils, when they are in contact with each other, may be necessary to increase the service life of the electric machine.

[0015] In an embodiment according to claim 6, the electrical coils can be connected in two stages, resulting in different potentials being present at the coils of the different stages. It should be noted that the maximum potential differences between adjacent coils are relevant; the voltage drop across a coil is not the primary concern here. The stages can be assigned to groups such that, in particular, the inner or outer ring has the coils directly connected to the phase terminals and is provided with separate insulating materials, while the other ring does not need to be insulated separately, or at least not completely. Preferably, the two-stage circuit is a star-delta connection (claim 7).

[0016] An embodiment according to claim 8 relates to the possibility of designing the coils of a slot to be at the same potential, thus eliminating the need for separate insulation in the slot. For this purpose, identical coils of parallel two-stage circuits can be arranged in a single slot. The term "equal potential" is to be interpreted broadly. On the one hand, a voltage drop naturally occurs across a coil, and on the other hand, fluctuations can occur between two "equal" potentials of a parallel circuit, for example, the star points of two parallel star connections, and even between conductors of a coil. This is generally irrelevant here.

[0017] In an embodiment according to claim 9, it is provided that the coils are wound over several stator teeth and thus skip slots.

[0018] Also of interest are embodiments according to claim 10, wherein the coils of the groups can have different wire diameters. This allows the fill factor to be optimized.

[0019] A preferred possible use is the subject of claim 11. Separate insulating material is generally only used above a certain voltage class.

[0020] According to a further teaching as per claim 12, which has independent significance, the use of a proposed electric machine is claimed to be on a voltage source with a voltage of at least 400 V AC as RMS, preferably at least 800 V AC as RMS, and / or as a drive motor of an electric vehicle and / or as an auxiliary unit of a working machine. Reference may be made to all embodiments of the proposed electric machine.

[0021] According to a further teaching as claimed in claim 13, which also has independent significance, a method for manufacturing a proposed electrical machine is claimed.

[0022] It is essential that a portion, in particular at least 50%, of the coils from the first group is placed on an insertion tool and drawn into the stator, and that subsequently a portion, in particular at least 50%, of the coils from the second group is placed on the insertion tool, specifically using the same slots as before, and drawn into the stator. The percentage refers to the number of coils per group. It is conceivable that some of the coils are inserted manually into the stator and / or the insertion tool to close the respective ring. This results in an efficient and feasible insertion process for the coils. Inserting all coils simultaneously would involve excessively high insertion forces for many groove geometries, coils, etc., but is otherwise not ruled out.

[0023] Reference may be made to all statements concerning the proposed electrical machine and its proposed use.

[0024] Claim 14 further describes the insertion of the coils.

[0025] The invention will now be explained in more detail with reference to a drawing that merely illustrates exemplary embodiments. The drawing shows

[0026] Fig. 1 a) a longitudinal section through a proposed electrical machine and b) a schematic top view of a winding head of the electrical machine,

[0027] Fig. 2 a) four parallel star-delta circuits and b) alternatively a star-star circuit,

[0028] Fig. 3 shows another view of the arrangement of the coils in the slots, Fig. 4 shows an insertion process with an insertion tool for inserting the coils into the stator and

[0029] Fig. 5 schematically shows the two-stage process of the insertion process.

[0030] The embodiments shown in the figures, which are preferred in this respect, relate to an electric machine 1 with a stator 2 and a rotor 3. The electric machine 1 can be used in construction machinery, agricultural machinery, and electric vehicles, in particular as a drive motor or auxiliary unit. Auxiliary units include, for example, hydraulic drives or fan drives.

[0031] Fig. 1 a) shows a longitudinal section through the electric machine 1. Essentially, the electric machine 1 is constructed in a conventional manner. The rotor 3 may drive a shaft (motor operation) or be driven by a shaft (generator operation). The electric machine 1 is, and preferably, a brushless electric machine 1. Accordingly, the stator 2 has a stator core 4 with slots 8 distributed along its circumferential direction 5, extending in the axial direction 6 and radial direction 7, and a winding arrangement 9 extending through the slots 8. The rotor 3 may have a permanent magnet arrangement 10. Alternatively, the electric machine 1 can also be designed as an asynchronous machine or a reluctance machine.

[0032] As can be seen from Fig. 1 a), the axial direction 6 runs along the axis of rotation 11 of the rotor 3. The radial direction 7 is arranged perpendicular to this. The circumferential direction 5, in turn, runs along the circumference of a circle or cylinder with an imaginary radius around the axis of rotation 11.

[0033] The stator arrangement primarily considered here, specifically the stator core 4, typically has a yoke 12 from which stator teeth 13 project inwards in a radial direction 7, which in turn have slots 8 between them along the circumferential direction 5. The winding arrangement 9 has several electrically connected coils 14. The coils 14 are generally arranged in the slots 8. There are numerous possible geometries for such coils 14, determining how the coils 14 can be distributed across the slots 8 and which coils 14 are intended to be connected in which configuration. This allows for the control of various parameters of the electric machine 1. In this case, in addition to high efficiency, a lower torque ripple is also a priority. The arrangement of the coils 14 is therefore correspondingly important.

[0034] In detail, the coils 14 have a first group of coils 15 arranged in the slots 8 and nested to form a first ring 16. The coils 14 are nested here, preferably at least in the region of two winding heads 17. The extent to which the coils 14 are nested can be seen from the view of one of the winding heads 17 in Fig. 1b). The first group 15 is shown hatched in Fig. 1b). The other coils 14 shown are explained below. In a preferred embodiment, as shown in Fig. 1b), a coil 14 of the first group 15 emerges from every second slot 8. Another coil 14 of the first group 15 enters the same slot 8. The terms "enter" and "exit" here refer to the (not shown) current direction, but are otherwise of little significance, since the coils 14 generally do not have a preferred direction.The coil 14 exiting slot 8 is guided in the winding head 17 along the circumferential direction 5 until it enters another slot 8. On its path, the coil 14 runs radially inwards (clockwise) along the 7 direction, and further coils 14 emerge from the skipped slots 8, which then follow the same path. Thus, the coils 14 of the first group 15 are individually arranged parallel to each other and obliquely to the circumferential direction 5, and after a complete revolution, they are nested within each other as a group. The geometry shown and described is only an example. Such nested rings of coils 14 can be obtained in various ways. The term "ring" here refers to the cross-section; viewed as a whole, the coils 14 are also nested to form a cylinder. A ring in this context is therefore a layer of a distributed winding arrangement 9.

[0035] It is therefore also the case that some of the coils 14 of the first group 15 are in contact with each other. This contact occurs here, and preferably at least in the area of ​​the winding head 17. With reference to Fig. 1 b), it can be said of an exemplary coil 18 that it exits radially outwards from a slot 8, skips five slots 8 in a clockwise direction, and enters a slot 8 further radially inwards. In the meantime, the exemplary coil 18 is in contact with other coils 14 of the first group 15, first only on the inside, later on both the inside and outside, and finally only on the outside (in each case radially).

[0036] It is essential that the coils 14 have a second group of coils 19, which are arranged in the grooves 8 and nested to form a second ring 20, and that some of the coils 14 of the second group 19 are in contact with each other. This second group 19 is not shown hatched in Fig. 1 b). It is interesting to note that this second group 19 is itself nested. However, the second group 19 is clearly separated from the first group 15 and preferably not nested with the first group 15.

[0037] The separation into groups now allows the groups to be treated differently when insulating the coils 14. It is proposed that at least some of the adjacent coils 14 of the first group 15, in particular all adjacent coils 14 of the first group 15 that are out of phase, be insulated from each other by an insulating material 21 separate from the coils 14, and that at least some of the adjacent coils 14 of the second group 19, in particular all adjacent coils 14 of the second group 19 that are out of phase, be in direct contact with each other. The separation into groups and the different insulation of the groups significantly reduces the probability of human error when applying the separate insulating material 21. In Fig. 1 b), the separate insulating material 21 is shown in the area of ​​the winding head 17 between the coils 14 of the first group 15.The separate insulating material 21 can be insulating paper and / or self-adhesive.

[0038] Consequently, it is preferably provided here that all adjacent coils 14 of the first group 15 are insulated from each other by an insulating material 21 separate from the coils 14, and / or that all adjacent coils 14 of the second group 19 are in direct contact with each other. The coils 14 of the second group 19 may be partially in contact with the coils 14 of the first group 15. Depending on the potential difference, separate insulating material 21 may also be introduced between the first group 15 and the second group 19.

[0039] As can also be seen from Fig. 1 b), and preferably provided here, the first group of coils 15 is arranged in multiple layers, in particular two layers, in the slots 8, and the second group of coils 19 is arranged in multiple layers, in particular two layers, in the slots 8. Preferably, exactly two coils 14 are arranged in each slot 8.

[0040] Here, and preferably, the first group 15 is arranged radially outside in the slots 8, and the second group 19 is arranged radially inside the slots 8. It should be noted that the coils 14 in the winding head 17 are represented as two almost completely separate rings. The inner coils 14 are also pressed outwards to a certain extent in the slots 8.

[0041] As can also be seen from Fig. 1 b), the first group 15 and the second group 19 can be arranged in different grooves 8. Preferably, the first group 15 and the second group 19 are arranged alternately in the grooves 8 along the circumferential direction 5.

[0042] Fig. 2 shows in a) and b) two preferred configurations of the coils 14 of both groups. Firstly, it can be provided that the electrical machine 1, in particular, has at least or exactly three or at least or exactly six phase connections U, V, W.

[0043] Preferably, at least one, preferably at least four, and more preferably at least eight, coil(s) 14, in particular of the first group 15, is or are connected to each phase terminal U, V, W. For clarity, a variant with eight coils 14 has not been shown.

[0044] Furthermore, it is preferably provided here that the first group 15 is connected to the phase terminals U, V, W and the second group 19, and that the second group 19 is only connected to the first group 15.

[0045] In principle, it can be provided that the first group 15 and the second group 19 each form one stage of a two-stage circuit. Preferably, as shown, the first group 15 and the second group 19 form at least two, preferably at least four, and further preferably at least eight, parallel two-stage circuits. The variant with eight circuits is not shown.

[0046] The two-stage circuit can be a star-delta connection, as shown in Fig. 2 a), wherein the first group 15 forms the star connection and the second group 19 forms the delta connection. Alternatively, as shown in Fig. 2 b), the two-stage circuit can be a star-star connection, wherein the first group 15 forms an outer star connection and the second group 19 forms an inner star connection. Fig. 3 shows the connection again at the winding head. Figures 2 a) and 2 b) show four parallel circuits, which are preferably wound over 24 slots 8.

[0047] The term "parallel" also encompasses cascaded circuits with, for example, measures to suppress circulating currents. These circuits are cascaded at the level of electrical connections and therefore not parallel in the circuit-technical sense, but magnetically equivalent to the circuit shown. As an alternative to cascading, it is also conceivable, for example, to connect the outer star points of the triangles to each other.

[0048] It is therefore the case that in the area of ​​the first group 15, a need for separate insulating material 21 between many or all of the coils 14 is hardly avoidable by dividing the coils 14 onto the slots 8, since simply all of the coils 14 of the first group 15 are connected to one phase and the coils 14 of one phase are to be distributed around the circumference.

[0049] In general, and in particular to save on separate insulating material 21, it can be provided that the coils 14 of a group, which are arranged in multiple layers in a slot 8, are at the same potential, in particular that they are identical coils 14 of the parallel two-stage circuits. For example, two coils 14, each forming the upper arm of a star, can be arranged in a slot 8. Preferably, no separate insulating material 21 is arranged between two coils 14 of a group, which are arranged in multiple layers in a slot 8. It should also be mentioned that it can be provided that the coils 14 of the first group 15 and / or the second group 19 are each wound over at least four, preferably at least five, and more preferably at least six, stator teeth 13 forming the slots 8.

[0050] The slots 8 narrow radially inwards, and even though the coils 14 of the second group 19 can be partially pressed radially outwards within the slots 8, the available space is somewhat reduced. Therefore, it is preferably provided that the coils 14 of the first group 15 each have a larger wire diameter than the coils 14 of the second group 19. Even though this results in more wires per coil 14 to achieve the same overall cross-section, it increases the flexibility of the arrangement in the slots 8.

[0051] It may be provided that the coils 14 of the first group 15 have different geometric parameters, in particular a larger circumference, than the coils 14 of the second group 19.

[0052] Preferably the stator core 4 has at least 24, preferably at least 48, slots 8.

[0053] Furthermore, and preferably, it is provided here that the electric machine 1 is suitable for connection via the coils 14, in particular the phase terminals U, V, W, to a voltage source with an AC voltage of at least 400 V RMS, preferably at least 800 V RMS. The voltage source can be a battery, in particular that of an electric vehicle, wherein the battery voltage is converted into three-phase current by means of an inverter. Alternatively, a diesel vehicle can also use an electric motor if an internal combustion engine and a generator are connected upstream of it.

[0054] According to a further teaching, it is proposed to use an electrical machine 1 according to the proposed method on a voltage source of at least 400 V AC voltage as RMS value, preferably at least 800 V AC voltage as RMS value, and / or as a drive motor of an electric vehicle and / or as an auxiliary unit of a working machine.

[0055] According to a further teaching, a method for manufacturing a proposed electrical machine 1 is proposed. This method can be explained with reference to Figures 4 and 5. Figure 4 shows a setup with a stator core 4 and an insertion tool 22 with coils 14 inserted into the insertion tool 22.

[0056] Essential to this further teaching is that a portion, in particular at least 50%, of the coils 14 of the first group 15 is placed on a drawing-in tool 22 and drawn into the stator 2, and subsequently a portion, in particular at least 50%, of the coils 14 of the second group 19 is placed on the drawing-in tool 22, in particular with the same slots 23 of the drawing-in tool 22 as before, and drawn into the stator 2. Fig. 5 shows two drawing-in processes successively, the first group 15 above and then the second group 19 below. A portion of the coils 14, for example the last three, can be drawn in by hand and / or inserted into the drawing-in tool 22.

[0057] In either case, it is preferably provided here that all coils 14 of the first group 15 are drawn into the stator 2 before the coils 14 of the second group 19 are drawn into the stator 2. Preferably, separate insulating material 21 is provided between the groups. This is preferably drawn in after the coils 14 of the first group 15 and before the coils 14 of the second group 19.

Claims

Patent claims 1. Electric machine with a stator (2) and a rotor (3), wherein the stator (2) has a stator core (4) with slots (8) distributed along its circumferential direction (5) and extending in the axial direction (6) and radial direction (7), and a winding arrangement (9) extending through the slots (8), wherein the winding arrangement (9) has several electrically connected coils (14), wherein the coils (14) have a first group of coils (15) arranged in the slots (8) and nested to form a first ring (16), wherein a portion of the coils (14) of the first group (15) are in contact with each other, characterized in that that the coils (14) have a second group of coils (19) arranged in the slots (8) and nested to form a second ring (20), that some of the coils (14) of the second group (19) are in contact with each other, that at least some of the adjacent coils (14) of the first group (15) are insulated from each other by an insulating material (21) separate from the coils (14), and that at least some of the adjacent coils (14) of the second group (19) are in direct contact with each other.

2. Electrical machine according to claim 1, characterized in that all adjacent coils (14) of the first group (15) are insulated from each other by an insulating material (21) separate from the coils (14), and / or that all adjacent coils (14) of the second group (19) are directly adjacent to each other.

3. Electric machine according to claim 1, characterized in that the first group of coils (15) is arranged in the slots (8) in multiple layers, in particular in two layers, and that the second group of coils (19) is arranged in the slots (8) in multiple layers, in particular in two layers, and / or, that the first group (15) is arranged radially outside in the slots (8), and that the second group (19) is arranged radially inside in the slots (8).

4. Electric machine according to claim 1 or 2, characterized in that the first group (15) and the second group (19) are arranged in different grooves (8), preferably that the first group (15) and the second group (19) are arranged alternately in the grooves (8) along the circumferential direction (5).

5. Electrical machine according to one of the preceding claims, characterized in that the electrical machine (1), in particular having at least or exactly three or at least or exactly six, phase connections (U, V, W), preferably that at least four, preferably at least eight, coils (14), in particular of the first group (15), are connected to each phase connection (U, V, W).

6. Electrical machine according to claim 5, characterized in that the first group (15) is connected to the phase terminals (U, V, W) and the second group (19), and that the second group (19) is connected only to the first group (15), and / or that the first group (15) and the second group (19) each form a stage of a two-stage circuit, preferably that the first group (15) and the second group (19) form at least two, preferably at least four, further preferably at least eight, parallel two-stage circuits.

7. Electrical machine according to claim 6, characterized in that the two-stage circuit is a star-delta circuit, that the first group (15) forms the star circuit, and that the second group (19) forms the delta circuit.

8. Electrical machine according to one of the preceding claims, characterized in that the coils (14) of a group, which are arranged in multiple layers in a slot (8), are at the same potential, in particular are identical coils (14) of the parallel two-stage circuits, preferably that no separate insulating material (21) is arranged in the slot (8) between two coils (14) of a group, which are arranged in multiple layers in a slot (8).

9. Electrical machine according to one of the preceding claims, characterized in that the coils (14) of the first group (15) and / or the second group (19) are each wound over at least four, preferably at least five, further preferably at least six, stator teeth (13) forming the slots (8).

10. Electrical machine according to one of the preceding claims, characterized in that the coils (14) of the first group (15) each have a larger wire diameter than the coils (14) of the second group (19), and / or that the coils (14) of the first group (15) have different geometric parameters, in particular a larger circumference, than the coils (14) of the second group (19).

11. Electrical machine according to one of the preceding claims, characterized in that the electrical machine (1) is suitable for being connected with the coils (14), in particular the phase connections (U, V, W), to a voltage source of at least 400 V AC voltage as RMS value, preferably at least 800 V AC voltage as RMS value.

12. Use of an electric machine (1) according to one of the preceding claims on a voltage source with at least 400 V AC voltage as RMS value, preferably at least 800 V AC voltage as RMS value, and / or as a drive motor of an electric vehicle and / or as an auxiliary unit of a working machine.

13. Method for manufacturing an electric machine (1) according to any one of claims 1 to 11 , characterized by that a part, in particular at least 50%, of the coils (14) of the first group (15) is placed on a drawing-in tool (22) and drawn into the stator (2), and that subsequently a part, in particular at least 50%, of the coils (14) of the second group (19) is placed on the drawing-in tool (22), in particular the same slots (23) of the drawing-in tool (22) as before, and drawn into the stator (2).

14. Method according to claim 13, characterized in that all coils (14) of the first group (15) are drawn into the stator (2) before the coils (14) of the second group (19) are drawn into the stator (2).

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