METHOD OF MANUFACTURING A STATOR ASSEMBLY

Abstract

A method of manufacturing a stator assembly for an electric machine includes providing multiple stator windings. Each stator winding is connected to a conductive terminal. The method includes assembling multiple busbars into a busbar assembly. The busbars are arranged flexibly relative to each other in the busbar assembly. The method also includes connecting the busbar assembly to some of the conductive terminals.

Claims

1. A method of manufacturing a stator assembly for an electric machine, the method comprising: providing a plurality of stator windings, each stator winding being connected to a conductive terminal; assembling a plurality of busbars into a busbar assembly, wherein the plurality of busbars are arranged flexibly relative to each other in the busbar assembly; and connecting the busbar assembly to a plurality of the conductive terminals.

2. The method as claimed in claim 1, wherein each of the plurality of busbars is rigid.

3. The method as claimed in claim 1, wherein the step of assembling the plurality of busbars into the busbar assembly comprises winding lacing tape around the plurality of busbars.

4. The method as claimed in claim 1, wherein the step of assembling the plurality of busbars into the busbar assembly comprises arranging the plurality of busbars into two or more layers to form the busbar assembly.

5. The method as claimed in claim 4, wherein the step of assembling the plurality of busbars into the busbar assembly comprises arranging a layer of insulation between the two or more layers of the busbar assembly.

6. The method as claimed in claim 5, wherein the layer of insulation comprises a low-friction material.

7. The method as claimed in claim 4, wherein the step of assembling the plurality of busbars into the busbar assembly comprises applying an adhesive or an epoxy between the two or more layers of the busbar assembly.

8. The method as claimed in claim 7, wherein the method comprises curing the adhesive or the epoxy after the busbar assembly has been connected to the plurality of the conductive terminals.

9. The method as claimed in claim 1, wherein the method comprises connecting the busbar assembly to a plurality of the conductive terminals so to connect at least four of the stator windings together for supplying a same phase of an AC voltage supply to these at least four stator windings.

10. The method as claimed in claim 9, wherein the busbar assembly comprises at least 6 busbars.

11. The method as claimed in claim 1, wherein the step of assembling the plurality of busbars into the busbar assembly comprises arranging the plurality of busbars in a flexible jig.

12. The method as claimed in claim 11, wherein the method comprises connecting the busbar assembly to the plurality of the conductive terminals while the plurality of busbars are in the flexible jig.

13. The method as claimed in claim 12, wherein the method comprises curing the flexible jig.

14. The method as claimed in claim 1, wherein the method comprises: applying a coating to the busbar assembly; and curing the coating.

15. The method as claimed in claim 1, wherein the busbar assembly comprises an arc that subtends an angle 50 degrees and 360 degrees.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0047] One or more non-limiting examples will now be described, by way of example only, and with reference to the accompanying figures in which:

[0048] FIG. 1 shows a stator assembly;

[0049] FIG. 2 shows a closer view of part of the stator assembly shown in FIG. 1;

[0050] FIG. 3 shows a busbar assembly including multiple busbars;

[0051] FIG. 4 shows a closer view of the busbar assembly shown in FIG. 3; and

[0052] FIGS. 5, 6 and 7 show examples of how busbars may be arranged flexibly relative to each other in a busbar assembly.

DETAILED DESCRIPTION

[0053] FIG. 1 shows a stator assembly 1 including multiple windings 2. Each winding 2 is depicted as a block in FIG. 1, not showing the wires in the winding 2. Each winding may be formed from a solid wire or layers of flat wire. Alternatively, each winding may be formed from a multi-strand cable, such as a Litz wire, that contains multiple wires (i.e. strands) that are insulated from one another along at least part of their length (e.g. along the whole length except for at the ends). The (e.g. strands of the) cable may be in electrical communication with one another at the end portions of the (e.g. strands of the) cable, to electrically connect the ends of (e.g. each of the strands of) the cable to a conductive terminal 4.

[0054] Each winding may be wound around an electromagnetic core 6 (e.g. an iron core). The ends of each winding 2 (shown here as an individual coil) are electrically connected to a pair of conductive terminals 4. In some embodiments, more than one coil may be wound together.

[0055] The conductive terminals 4 may be externally threaded and the busbars may be connected to the conductive terminals 4 using nuts 14. The conductive terminals 4 are arranged on an inner circumference and an outer circumference of the stator assembly 1.

[0056] FIG. 2 shows a closer view of part of the stator assembly 1 shown in FIG. 1. In this example, it can be seen that busbars 8 are bolted onto pairs of conductive terminals 4 from different windings 2 to electrically connect the windings 2.

[0057] FIG. 3 shows two busbar assemblies 10, one stacked on top of the other, and each including multiple busbars 8. Each busbar 8 has a main longitudinal portion that extends around an arc, and two end portions 12 that project radially outwards or inwards. The end portions 12 define an aperture that allows the busbar 8 to fit over the conductive terminals 4 to which the busbar 8 is to be connected. A potting material (not shown) may be used to encapsulate the edges of the busbars.

[0058] The busbars 8 are arranged to form an arc-shaped busbar assembly 10, such that the busbar assembly 10 fits into the gap between the inner circumference and the outer circumference of the stator assembly 1 between the conductive terminals 4, and such that the end portions 12 of the busbars 8 substantially align with the conductive terminals 4. Four busbar assemblies 10, for example, are used to connect all of the conductive terminals 4 of the stator assembly 1. In other examples, only two or three busbar assemblies may be used.

[0059] FIG. 4 shows a closer view of the busbar assembly 10 shown in FIG. 3. FIG. 4 shows a plan view, in a direction parallel to the plane of the busbar assembly 10. The busbars 8 are arranged in six layers that allow the necessary connections to be made between the busbars 8 and the conductive terminals 4. Each busbar 8 has a low-friction dielectric coating, such that an electrical connection is not made between the busbars 8 of the busbar assembly 10.

[0060] (It should be noted that the number of layers of busbars 8 in the busbar assembly 10 may depend on the number of phases of the AC voltage supply that is being supplied to the stator assembly 1. The busbar assembly 10 may have a number of layers of busbars 8 that is equal to the number of phases, e.g. three layers for three phases, six layers for six phases.)

[0061] The busbars 8 are assembled into the busbar assembly 10 before the busbar assembly 10 is fitted into the stator assembly 1 and the end portions 12 of the busbars 8 are connected to the conductive terminals 4. Pre-assembling the busbar assembly 10 makes the process of manufacturing the stator assembly 1 more efficient and less prone to damaging the stator windings 2 and the conductive terminals 4 when fitting the busbar assembly 10.

[0062] In order to assist with the fitting of the busbar assembly 10 into the stator assembly 1 and the connection of the end portions 12 of the busbars 8 to the conductive terminals 4, the busbars 8 are assembled into the busbar assembly 10 in a way in which the busbars 8 are arranged flexibly relative to each other in the busbar assembly 10. The flexibility of the busbar assembly 10 helps to make it easier, quicker and less error prone to align and fit the busbar assembly 10 in the stator assembly 1, when mechanically mating the busbar assembly 10 to the conductive terminals 4 of the stator windings 2. The flexibility of the busbar assembly 10 also helps to reduce the force that has to be exerted on the busbar assembly 10 when fitting it into place for connecting to the conductive terminals 4 of the stator windings 2.

[0063] Three examples of how busbars may be arranged flexibly relative to each other in a busbar assembly will now be described, with reference to FIGS. 5, 6 and 7.

[0064] FIG. 5 shows a busbar assembly 110 in which the busbars 108 are connected together by lacing tape 112 that is wrapped around the busbars 108 of the busbar assembly 110. The tension of the lacing tape 112 is chosen to determine the amount of movement between the busbars 108 of the busbar assembly 110.

[0065] FIG. 6 shows a busbar assembly 210 in which the busbars 208 are connected together by an adhesive, a bond coating or an epoxy 212 between the layers of busbars 208 of the busbar assembly 210. The adhesive, bond coating or epoxy 212 is applied in a flexible state to connect the layers of busbars 208 of the busbar assembly 210 but allows the busbars 208 of the busbar assembly 210 to move relative to each other. The adhesive, bond coating or epoxy 212 is then cured to rigidly secure the busbars 208 of the busbar assembly 210 together, after the busbars 208 have been connected to the conductive terminals of the stator assembly.

[0066] FIG. 7 shows a busbar assembly 310 in which the busbars 308 are assembled together in a flexible jig 312. This allows the busbars 308 to move relative to each other in the busbar assembly 310. The flexible jig 312 is then cured to rigidly secure the busbars 308 of the busbar assembly 310 together, after the busbars 308 have been connected to the conductive terminals of the stator assembly.

[0067] Once the busbars have been connected to the conductive terminals of the stator assembly and, e.g., the flexible adhesive, bond coating, epoxy or jig has been cured, the stator assembly is impregnated by dipping the stator assembly in a varnish. The stator assembly is then baked in an oven to cure the varnish. This helps to form a rigid stator assembly.

[0068] While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.