High-voltage motor stator

Abstract

The invention refers to a high-voltage motor stator (10) comprising a back iron arrangement (20) with several radial stator tooth bodies (22) defining radial stator slots (24) between the stator tooth bodies (22), and with a back iron ring (29) connecting all stator tooth bodies (22) with each other, plastic tooth isolating sleeves (30) electrically isolating each stator tooth body (22), electromagnetic pole coils (40) each surrounding one of the tooth isolating sleeves (30), two separate plastic end caps (50, 50') being fixed to both axial ends (21, 21') of the back iron arrangement (20) and axially covering the pole coils (40), a slot isolation sheet (60) provided in every stator slot (24) at the slot bottom surface (25) of the stator slot (24), respectively, wherein the plastic end caps (50, 50') are provided with sheet holding 20 structures (52), respectively, for holding the slot isolation sheets (60) in position.

Description

[0001] High-voltage motor stator

[0002] The invention refers to a high-voltage motor stator of a high-voltage electric motor, in particular of a high-voltage electric motor in automotive applications for driving secondary devices, such as a hydrogen blower, an air-conditioning compressor, a coolant pump etc.

[0003] Automobiles with electric traction engines and traction batteries typically have system voltages of 400 V, 800 V or even more. Some typical secondary devices in an automobile have a performance in the range of some kWh so that the high-voltage circuit is preferred to drive the electric motor. However, a high system voltage requires different isolation measures to avoid electric short circuits and electric leakage currents in the motor stator.

[0004] Typically, an external motor stator is provided with a back iron arrangement with several radial stator tooth bodies defining radial stator slots between the stator tooth bodies. The back iron arrangement is also provided with an outside back iron ring connecting all stator tooth bodies with each other. Every stator tooth body is surrounded by an electromagnetic pole coil.

[0005] DE 10 2009 024 991 B4, DE 10 2020 131 413 Al, DE 11 2013 005 061 T5 and US 2020 0 052 556 Al disclose electric motors including high-voltage motor stators with different electric isolation means and measures, and in particular disclose plastic end caps at the axial ends of the motor stator.

[0006] It is an object of the invention to provide a high-voltage motor stator with good electric isolation against unintentional human contact and against electric leakage currents.

[0007] This object is solved, according to the invention, with a high-voltage motor stator with the features of claim 1. The high-voltage motor stator according to the invention comprises a back iron arrangement with several radial stator tooth bodies defining the electric poles of the motor stator and defining radial stator slots between the stator tooth bodies, seen in circumferential direction. The back iron arrangement also is provided with a circular back iron ring connecting all stator tooth bodies with each other. The radially outside ends of the stator tooth bodies are directly connected to the circular back iron ring. The back iron arrangement is preferably made of laminated sheet packages of ferromagnetic metal sheets. Preferably the back iron ring and the stator tooth bodies are separate parts which are connected to each other by a, for example, form-fit connection.

[0008] Every stator tooth body is provided with a tooth isolation sleeve constituting an electric isolation. The plastic tooth isolation sleeves can be provided as several separate plastic parts or can be connected to each other so that all plastic tooth isolation sleeves together define a single integral plastic part.

[0009] Every stator tooth body is provided with an electromagnetic ring-like pole coil which surrounds the corresponding tooth isolation sleeve, respectively. The plastic tooth isolation sleeve guarantees that the coil wire of the pole coil cannot get into direct electrical contact with the stator tooth body.

[0010] The motor stator also comprises two separate plastic end caps being fixed to both axial ends of the back iron arrangement and thereby axially covering the pole coils. The plastic end caps have as a primary function the mechanical shielding of the pole coils but can have additional functions, such as guidance and leading of the coil wire ends.

[0011] A separate slot isolation sheet is provided in every stator slot at the slot bottom surface of the stator slots. The slot isolation sheet covers and electrically isolates the radially inside surface of the back iron ring so that the coil wire of the pole coil cannot get into direct electric contact with the back iron ring of the back iron arrangement. The plastic end caps are provided with sheet holding structures, respectively, for holding the slot isolation sheets in position. The sheet holding structures guarantee a defined position of the slot isolation sheet in axial, radial and tangential direction so that the slot isolation sheet cannot shift during the lifetime of the motor stator. Additionally, the sheet holding structures of the plastic end caps facilitate the assembly of the high-voltage motor stator.

[0012] Generally, the sheet holding structures can be of any suitable kind. Preferably, the sheet holding structures are provided as axial holding slits to which axial end portions of the slot insulation sheets are inserted. The axial holding slits define the spatial position of the slot insulation sheets in axial and radial direction. The axial end portions of the slot insulation sheets are not necessarily additionally fixed at or within the holding slits by clamping, by screws and / or by gluing, but can additionally be fixed within the holding slits.

[0013] Preferably, the tooth isolation sleeves each define a ring-like sleeve collar at their radially distal sleeve end, respectively, so that a tangential isolation slit is defined between the sleeve collar and the back iron ring. The plastic sleeve collar is not directly in contact with the back iron ring but defines a small tangential isolation slit together with the radially inside surface of the back iron ring. The slot isolation sheet tangentially extends into both tangential isolation slits of each stator slot, respectively. This measure substantially increases the creepage distance for electric leakage currents between the coil wire at the outside of the pole coil and the back iron ring.

[0014] Preferably, the tangential depth of the isolation slit is at least 1.0 mm, and preferably is more than 2.0 mm, so that the resulting creepage distance is sufficient for a typical system voltage of 400 V or, with more than 4.0 mm depth, for 800 V.

[0015] Preferably, the axial holding slits are, seen in axial direction, parallel to the inner slot bottom surface of the back iron ring, so that also the slot isolation sheet is, seen in axial direction, more or less parallel to the preferably cylindrical radially inside surface defining the slot bottom surface of the back iron ring.

[0016] Preferably, the plastic end caps both are located axially outside of the stator slots and do not axially extend into the stator slots. More preferably, the plastic end caps can be in axial contact with the axial surface of the back iron arrangement to perfectly define the axial position of the plastic end caps.

[0017] Preferably, the end caps are directly fixed to the tooth isolating sleeves, wherein the fixation can be provided by an axial snap-fit connection, by gluing and / or by other suitable fixation means, techniques and methods.

[0018] Preferably, the end caps are provided with cooling fluid openings which are axially in-line with the stator slots. More preferably, the cooling fluid openings substantially have the contour of the free space of the corresponding stator slot. The free space in this context is the free axial space in a stator slot which is not filled with the stator tooth bodies, the tooth isolating sleeves and the electromagnetic pole coils. The free axial space and the corresponding cooling fluid openings allow an axial cooling fluid flow through the motor stator, wherein the cooling fluid preferably is cooling air.

[0019] Preferably, the axial length of the slot isolation sheet is at least equal to the axial extend of the corresponding electromagnetic pole coil.

[0020] A high voltage in the present context is generally a voltage above 60 V which requires structural protection means and measures to avoid unintentional contact of a person with the high voltage. Preferably, a high voltage in the present context is at least 200 V which requires substantial structural means and measures to avoid electric leakage currents.

[0021] One embodiment of the invention is shown with reference to the enclosed drawings, wherein figure 1 shows a longitudinal sectional view I-I of a high-voltage motor stator with plastic end caps having sheet holding structures for holding slot isolation sheets in position, figure 2 shows a transversal sectional view II-II of the motor stator of figure 1, figure 3 shows another transversal sectional view III-III of a part of the motor stator of figures 1 and 2, and figure 4 shows a plastic end cap and a perspective view.

[0022] The figures show a high voltage motor stator 10 for a system voltage of, for example 400 V for an electric high voltage motor with a typical electric performance of 2 kWh.

[0023] The high-voltage motor stator 10 comprises a back iron arrangement 20 with six radial stator tooth bodies 22 which define, seen in circumferential direction, six radial stator slots 24 between the stator tooth bodies 22. The back iron arrangement 20 comprises a separate back iron ring 29 connecting the outside end portions of the six stator tooth bodies 22 with each other. The substantially cylindrical inside surface of the back iron ring 29 defines the slot bottom surfaces 25 of the six stator slots 24. The motor stator 10 has a substantially cylindrical configuration with respect to a longitudinal stator axis A.

[0024] The inside end portions of the six stator teeth bodies 22 are provided with pole shoes 23 which are connected to each other in circumferential direction by material bridges having a very small cross-section. The stator tooth bodies 22 and the back iron ring 29 each are defined by packages of many metal sheets.

[0025] Every stator tooth body 22 is electrically isolated by a plastic tooth isolating sleeve 30 completely surrounding the stator tooth body 22 and covering the pole shoe 23 with a pole shoe cover 23'. Every tooth isolating sleeve 30 also defines a ring-like sleeve collar 34 at the radially distal sleeve end 26, as shown in figure 1. The lateral extension of the sleeve collar 34 referring to the isolating sleeve 30 is 5 mm. The radially distal side of the sleeve collar 34 is not in direct contact with the proximal surface of the slit bottom surface 25 but has a radial distance rlOO of, for example, 0.5 to 3 mm. The sleeve collar 34 and the slot bottom surface 25 of the back iron ring 29 together define twelve tangential isolation slits 100 which have a tangential depth tlOO of 5 mm.

[0026] The tooth isolating sleeves 30 each are surrounded by an electromagnetic pole coil 40 being arranged radially between the sleeve collar 34 and the pole shoe cover 23'. Each pole coil 40 is defined by a coil wire. The six pole coils 40 are electrically connected with each other in three phases and in a triangular structure or in a star structure.

[0027] The motor stator 10 comprises two separate plastic end caps 50, 50' arranged at both axial ends 21, 21' of the back iron arrangement 20 and axially substantially covering the pole coils 40. The plastic end caps 50, 50' both are provided with six sheet holding structures 52 holding six slot isolation sheets 60 axially and radially in position. The slot isolation sheet 60 is defined by an electrically isolating sheet body material.

[0028] Each holding structure 52 is provided with three small axial holding slits 54 to which axial end portions 61, 61' of the slot insulation sheets 60 are inserted, as in particular shown in figures 2 and 3. The three axial holding slits 54 of each holding structure 52 are defined by three axial holding noses 53, which holding noses 53 restrict the inward movement of the axial end portions 61, 61' of the slot insulation sheets 60. Each holding structure 52 is provided with tangential slit walls 51 extending radially inwardly from the cylindrical cap body and which define the tangential extend in circumferential direction of each holding structure 52. As a result, each holding structure 52 defines the spatial position of every and portion 61, 60 one' of every slot insulation sheet 60 in both tangential (circumferential), in both radial and in one axial direction. As shown in figure 1, the axial length x60 of the slot isolation sheet 60 is 30% greater than the axial extend x40 of the corresponding electromagnetic pole coil 40. As shown in figure 2, the axial holding slits 54 have, seen in axial direction, are parallel to the cylindrical slot bottom surfaces 25 of the back iron ring 29. The sheet holding structures 52 of the end caps 50, 50' are located axially outside of the stator slots 24 and do not project into the stator slots 24. The end caps 50, 50' are directly fixed at the tooth isolating sleeves 30 by a snap-on connection, or by any other suitable connection. The end caps 50, 50' both are provided with six axial cooling fluid openings 55, each of them being axially in-line with the stator slots 24.

[0029] A separate cylindrical slit tube 110 is provided at the radial inside of the pole shoes 23.

Claims

CLAIMS1. A high-voltage motor stator (10) comprising a back iron arrangement (20) with several radial stator tooth bodies (22) defining radial stator slots (24) between the stator tooth bodies (22), and with a back iron ring (29) connecting all stator tooth bodies (22) with each other, plastic tooth isolating sleeves (30) electrically isolating each stator tooth body (22), electromagnetic pole coils (40) each surrounding one of the tooth isolating sleeves (30), two separate plastic end caps (50, 50') being fixed to both axial ends (21, 21') of the back iron arrangement (20) and axially covering the pole coils (40), a slot isolation sheet (60) provided in every stator slot (24) at the slot bottom surface (25) of the stator slot (24), respectively, wherein the plastic end caps (50, 50') are provided with sheet holding structures (52), respectively, for axially holding the slot isolation sheets (60) in position.

2. The high-voltage motor stator (10) of claim 1, wherein the tooth isolating sleeves (30) each define a ring-like sleeve collar (34) at every radially distal sleeve end (26), so that a tangential isolation slit (100) is defined between the sleeve collar (34) and the back iron ring (29), wherein the slot isolation sheet (60) tangentially extends into both tangential isolation slits (100) of one stator slot (24), respectively.

3. The high-voltage motor stator (10) of claim 2, wherein the tangential depth (tlOO) of the isolation slit (100) is at least 1.0 mm, and is preferably more than 2.0 mm.

4. The high-voltage motor stator (10) of one of the preceding claims, wherein the sheet holding structures (52) are provided with axial holding slits (54) to which axial end portions (61, 61') of the slot insulation sheets (60) are inserted.

5. The high-voltage motor stator (10) of claim 4, wherein the axial holding slits (54) are parallel to the slot bottom surface (25) of the back iron ring (29).

6. The high-voltage motor stator (10) of one of the preceding claims, wherein the sheet holding structures (52) of the end caps (50, 50') are located axially outside of the stator slots (24).

7. The high-voltage motor stator (10) of one of the preceding claims, wherein the end caps (50, 50') are directly fixed to the tooth isolating sleeves (30).

8. The high-voltage motor stator (10) of one of the preceding claims, wherein the end caps (50, 50') are provided with cooling fluid openings (55), which are axially in-line with the stator slots (24).

9. The high-voltage motor stator (10) of one of the preceding claims, wherein the axial length (x60) of the slot isolation sheet (60) is atleast equal to the axial extend (x40) of the corresponding electromagnetic pole coil (40).

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