NO347240B1

NO347240B1 - Method for production of a double-layer multiphase ironless winding and winding resulting therefrom

Info

Publication number: NO347240B1
Application number: NO20211544A
Authority: NO
Inventors: Zhaoqiang Zhang; Oddvin Agnalt Østmo
Original assignee: Alva Ind As
Priority date: 2021-12-20
Filing date: 2021-12-20
Publication date: 2023-07-24
Also published as: NO20211544A1; EP4454111A1; WO2023121476A1

Description

Method for production of a double-layer multiphase ironless winding and winding resulting therefrom

The present invention is related to a method for production of a double-layer multiphase ironless winding, according to the preamble of claim 1.

The present invention is also related to a double-layer multiphase ironless winding, according to the preamble of claim 5.

Background

Ironless and slotless permanent magnet electric machines gain an increasing attention of both the research and the industrial communities. Having certain advantages over the conventional technologies ironless and slotless machines are attractive for use in automation, robotics, medical devices, drones, etc.

The main enabling component of an ironless/slotless machine is the part creating alternating/rotating magnetic field, containing just conductors and not containing any iron/ferromagnetic parts, such as teeth. This component is commonly known as an ironless winding. One of the ways to create an ironless winding is to first make a so-called multiphase electromagnetic mat (consisting of conductors and some support elements), then bend it into a circular element, connect the ends, and finally consolidate it by, e.g., moulding it in some sort of epoxy.

Ironless windings often have end-windings of the neighbouring phases crossing each other in the end-region. For example, US2020244149A1 (“Electromagnetic mat for a stator or rotor component of an electric machine”), in the name of the applicant, discloses a winding in the form of a multiphase electromagnetic mat made by a method resembling weaving. It is visible that the end-windings of the neighbouring phases cross each other. A winding with crossing end-windings is also disclosed in JPS6343542A (“Void winding structure of motor armature”).

Crossing of the neighbouring phases in the end-region results in thicker end-windings compared to the thickness of the winding in the active area.

The ironless windings can have one or more layers. In some cases, double-layer windings are preferable. However, if the end-windings of different phases are crossing, the end-windings of the double-layer windings become even bigger than in the case with single-layer windings. This is well illustrated in GB1526614A (“Dynamoelectric machine two-layer stator windings”) where a slotless electric machine has a two-layer (double-layer) stator winding.

Massive end windings result in higher ohmic resistance of the phases of the winding and some challenges with mechanical integration of the ironless winding with the other components of the electric machine.

In double-layer winding it is possible to avoid the crossing of the end-windings by choosing a topology where each phase wire from the first layer crosses into the second layer two phase positions away. Such a solution is described in, for example, US2010117481A1 (“Winding arrangement for an electrical machine”) disclosing a design for and method of winding an electric machine using multiple strands of wire preformed into a wave shape with a plurality of wires (“legs”) connected by shaped end windings (“end turns”). This solution results in efficient packing of the winding end-parts and improved machine performance. This kind of winding can be realized both for axial-flux and radial-flux machines.

However, this solution is not free from drawbacks. It requires termination of twelve wires for a three-phase winding. The area with wire ends designated “15a-f” in Fig. 4 of US2010117481A1 shows the twelve wire ends. Thus, the double-layer winding in US2010117481A1 requires four wire ends per phase, while conventional winding would have two wire ends per phase, e.g. six wire ends for three phases.

Having double amount of wire ends makes production of the electric machine more complex since each wire end must be terminated (by either soldering some kind of terminals on the wire, soldering the wires together or soldering the wire ends to some kind of printed circuit board). This work is not easy to automate, so it is most often manual and very time consuming. In addition, the numerous terminals require a lot of space and can make moulding of the winding an extra challenge.

US2010117481A1 is considered to be the closest prior art to the present invention.

The prior art solutions fail to disclose design of double-layer ironless windings with compact endwindings wherein the number of terminals would not exceed two terminals per phase.

Further, a disadvantage of prior art solutions is, among others, that they fail to disclose methods for production of such windings.

Ironless/coreless machines are an attractive alternative to the conventional technologies even with the present level of their performances. Further improvement of the performances of ironless/coreless machines would provide the end-users with a superior electric machine technology enabling higher degree of electrification of the world.

Higher performances, such as higher efficiency and compactness, can be reached by reducing the size of the end-windings and by having fewer wire ends.

Reducing the size of the end-windings can have two positive effects: lower phase resistance and the possibility of making a substantially flat winding where the winding thickness will be approximately the same in the active area and in the end-winding area. The flat winding is easier to integrate with the rest of stator and rotor parts of the machine.

Winding having many wire ends that need termination is not easy to handle during production of the machine. Termination of the wire ends may require soldering, welding of other complex processes which are not easy to automate. In case of moulding of the ironless winding, the numerous wire ends will make the process of placing the electromagnetic mat into the mould complex and time consuming.

Wire ends coming from the winding need to be insulated from each other and when the limited space is already tightly packed with wire ends, adding insulation to each wire end is challenging.

There is accordingly a need for a method for production of a double-layer multiphase ironless winding and winding resulting therefrom with compact end-windings and as few terminals as possible.

There is further a need for a method for production of a double-layer multiphase ironless winding enabling production of ironless or slotless electric machines, wherein the method preferably is possible to automate.

There is further a need for method for production of a double-layer multiphase ironless winding and a winding resulting therefrom that will cut production steps and costs.

Object

The main object of the present invention is to provide a method for production of a double-layer multiphase ironless winding for electric machines and a winding resulting therefrom partly or entirely solving the above-mentioned drawbacks of prior art.

It is further an object of the present invention to provide a method for production of a double-layer multiphase ironless winding for electric machines and a winding resulting therefrom enabled by an electromagnetic mat that can be moulded with a curable liquid potting material, as epoxy/resin, to ensure higher mechanical strength, improved heat transfer, etc. for a stator or rotor component.

An object of the present invention is to provide a method for production of a double-layer multiphase ironless winding for electric machine and winding resulting therefrom enabling smaller end-windings compared to prior art solutions.

It is an object of the present invention to provide a method for production of a double-layer multiphase ironless winding for electric machine and a winding resulting therefrom enabling reduced number of terminals compared to prior art solutions.

An object of the present invention is to provide a method for production of a double-layer multiphase ironless winding for electric machine and winding resulting therefrom enabling a substantially flat double-layer ironless winding.

It is an object of the present invention to provide a method for production of a double-layer multiphase ironless winding for electric machine and a winding resulting therefrom enabling tailoring for different design specifications of an electric machine in a simple manner.

An object of the present invention to provide a method for production of a double-layer multiphase ironless winding for electric machine and a winding resulting therefrom resulting in lower production costs, both for mass production and low volume products.

Further objects of the present invention will appear from the following description, claims, and attached drawings.

The invention

A method for production of a double-layer multiphase ironless winding according to the present invention is defined by the technical features of claim 1. Preferable features of the method are described in the dependent method claims.

A double-layer multiphase ironless winding according to the present invention is defined by the technical features of claim 5. Preferable features of the winding are described in the dependent winding claims.

A winding according to the present invention has two ends in the longitudinal or circumferential (tangential) direction. The winding according to the present invention comprises multiple phase wires having respective first and second ends.

According to the present invention, all the phase wire ends are positioned on the one and same end of the winding. Accordingly, in the present invention all the phase wires have both their ends on the same end of the winding. On the other end of the winding, the phase wires are continuous and have no interruptions or connections.

In accordance with the present invention, the mentioned two wire ends of the same phase wire, when going in longitudinal or circumferential direction from the one end of the winding (where all the phase wire ends are positioned) to the other end, change transversal direction and cross each other in end-winding region of the winding arranging intermediate parts of the respective phase wires in alternating positions in the top or in the bottom layer in the active area. Intermediate parts of the phase wire will be the parts between the ends thereof.

In accordance with one embodiment of the present invention, the phase wires are arranged in determined positions in the winding by the use of a support structure holding the phase wires in place.

According to one embodiment of the present invention, the support structure comprises warps into which the phase wires woven providing a winding in the form of an electromagnetic mat.

In accordance with one embodiment of the present invention, the winding has a circular shape and wherein the two ends thereof are connected. A circular shape will be applicable in rotary machines.

According to a further embodiment of the winding according to the present invention, it is directly formed with a circular shape. According to one embodiment of present invention, the winding is directly formed within the circumference of an electric machine by being connected to the stator or rotor back iron.

In an alternative embodiment of the winding according to the present invention, the winding is first made with a flat shape, e.g. as a flat electromagnetic mat, which is then bent to a circular shape and next connection the ends of the winding/electromagnetic mat.

In accordance with a further embodiment suitable for linear or planar machine applications, the winding/electromagnetic mat can be made and left flat.

According to a further embodiment of the present invention, the winding is consolidated/structurally enforced by moulding it in a curable liquid potting material, such as epoxy or resin. By consolidating the winding will constitute an object with e.g. a circular shape. The consolidation also ensures higher mechanical strength, improved heat transfer, etc. for a stator or rotor component.

According to the present invention, the phase wires may be of any conductive type, such as, but not limited to, Litz-wires, solid wires, etc.

In accordance with the present invention, the winding comprises two or more phases. The most common number of phases being three.

In a case where the winding comprises three phases, the present invention reduces the number of wire ends from twelve to six (compared to the closest prior art).

A method of production of a double-layer ironless winding of an electric machine according to the present invention comprises continuously extending the phase wires at one end. The method further comprises, when going in longitudinal or circumferential direction from the one end to the other end of the winding, changing transversal direction of and crossing the respective phase wire ends in end-winding region of the winding and arranging intermediate parts of the respective phase wires in alternating positions in top or bottom layer in active area of the winding, and positioning all phase wire ends at the one and same end of the winding.

According to one embodiment of the method according to the present invention, it comprises holding the phase wires in place by fixing or integrating the phase wires in a support structure.

In accordance with a further embodiment of the method according to the present invention, it comprises fixing or integrating the phases wires to or in the support structure by weaving. The support structure is according to one embodiment comprising warps that is used to weave the phase wires into the support structure.

According to one embodiment of the method according to the present invention, it comprises coiling the phase wire length of each phase on two respective storages so that there is approximately the same length of phase wire coiled on each of the respective storages.

In accordance with a further embodiment of the method according to the present invention, it comprises starting winding creation process from approximately the middle of the phase wires and the winding creation process is performed by moving the respective storages across the winding in transversal direction.

According to a further embodiment of the method according to the present invention, it comprises bending the winding to a circular shape and connecting the ends.

In a further embodiment of the method according to the present invention, it comprises consolidating the winding by moulding it in a curable liquid potting material, such as epoxy or resin.

Further preferable features and advantageous details of the present invention will appear from the following example description, claims, and attached drawings.

Example

The present invention will below be described in detail with reference to non-limiting embodiments in the attached drawings, where:

Fig.1 is a principle drawing of an electromagnetic mat according to prior art,

Fig.2a-b are cross-sectional drawings of a double-layer coreless winding according to prior art,

Fig.3a-b are principle drawings of a coreless stator of axial-flux electric machine and its winding diagram according to prior art,

Fig.4 is a reconstruction of the design according to prior art,

Fig.5 is a principle drawing of a structure of a winding according to the present invention, showing end-windings for one phase only,

Fig.6 is a principle drawing of the structure of a winding according to the present invention, showing end-windings of all phases,

Fig.7a-d are principle drawings of the production method of a winding according to the present invention, and

Fig.8 is a principle drawing of an alternative design and alternative way to produce the winding according to the present invention.

Reference is now made to Figure 1, which is a principle drawing of an electromagnetic mat according to prior art US2020244149A1. As can be seen in Fig.1 the end-windings of the neighbouring phases cross each other resulting in thicker end-windings compared to the thickness of the electromagnetic mat in the active area.

Reference is now made to Figures 2a-b, which are cross-sectional drawings of a double-layer coreless winding of a slotless electric machine according to prior art GB1526614A. As can be seen from Fig.2a-b the end-windings are quite long and thicker than the winding part in the active area.

Reference is now made to Figures 3a-b, which are principle drawings of a coreless stator of an axialflux electric machine and its winding diagram according to prior art US2010117481A1. The ironless winding comprises multiple strands of wire preformed into a wave shape with a plurality of legs connected by shaped end turns. As can be seen from Fig. 3a-b the total number of wire ends is twelve. From the winding diagram one can further see that six wire ends belong to the left-hand side of the winding and six wire ends belong to the right-hand side of the winding.

Reference is now made to Figure 4 showing a representation of a flat winding 10 structure (like an electromagnetic mat) of the same design and structure as the winding presented in Figure 3b. In Figure 4, the phase wires 21-26 of different phases A, B, C, respectively, are represented by lines of different thickness. The phase wires 21-26 in the first (top) layer are represented by solid lines and the phase wires 21-26 of the second (bottom) layer are represented by dashed lines.

As Fig.4 shows, the phase wire 21-26 ends will be on both sides of the winding 10, grouped into a first group 41 at the left-hand side of the winding 10 and a second group 42 at the right-hand side of the winding 10. It is apparent that the winding 10 is made of six phase wires 21-26 belonging to the three phases, where:

• Phase A – phase wires 21 and 24

• Phase B – phase wires 22 and 25

• Phase C – phase wires 23 and 26

It is apparent that this winding 10 is a so-called “wave winding”.

Reference is now made to Figure 5, which is a principle drawing of the structure of a double-layer multiphase ironless winding 10 according to one embodiment of the present invention. Note that end-windings 70 are only shown for the first phase (phase wire 21). In the shown example embodiment, the winding comprises three phases. In the shown embodiment, the three phases take positions one after another in a sequence A-B-C-A-B-C-… (phase wire 21-22-23-21-22-23-…).

In contrast to the prior art solutions, as e.g. shown in Fig.4, the present invention does not start the forming of the winding 10 from the ends of the phase wires 21-23, but from the middle of the phase wires 21-23. The straight part of the phase wire 21 (on the left-hand side) comprises the starting part (intermediate part) of the winding 10. Forming direction for the phase wire 21 is according to the present invention shown by arrows 30. As Fig.5 show, the present invention enables that parts of the same phase wire 21-23 (of the same phase) can be arranged in either a top or bottom layer in active part 80 (shown in Fig.6) of the winding 10.

The first three straight parts of the phase wires 21-23 belong to the bottom layer and the last three straight parts of the phase wires 21-23 (right-hand side of the winding) belong to the top layer. According to one embodiment of the present invention, the winding 10 is bent to exhibit a circular shape, wherein the two single-layer parts is arranged on top of each other forming the double-layer structure.

As can be seen from Fig.5, for example, the phase wire 21 of the first phase has both ends 21a-b at a second end 102 of the winding 10, wherein the phase wire 21 is continuously extending at a first end 101 of the winding. As Fig.5 shows, the two phase wire ends 21a-b, when going in longitudinal or circumferential direction from the one end 102 to the other end 101 of the winding 10, i.e. from right to the left in Fig.5, change transversal direction and are crossing each other in end winding 70 region (shown in Fig.6) of the winding 10. In this manner, the intermediate parts of the phase wire 21 are arranged in alternative positions in the top or the bottom layer and the phase wire 21 ends 21a-b “meet” each other in the first end 101 of the winding 10.

Reference is now made to Figure 6 which is a principle drawing of a structure of a winding 10 according to the present invention, showing end-windings 70 of all phases, phase wire ends 21a-b, 22a-b, 23a-b of all phases, as well as defining what is the active area 80 of the winding 10.

Reference is now made to Figures 7a-c showing the principle of the method of production of a double-layer ironless winding 10 according to the present invention.

In the shown example embodiment, a three phase winding 10 according to the present invention is formed, since three is the most common number of phases. There is used one phase wire 21, 22, 23 per phase as shown in Figure 7a. Phase wire 21, 22, 23 length of each phase is coiled on two respective storages, e.g. storages 51A and 51B for phase wire 21, storages 52A and 52B for phase wire 22, storages 53A and 53B for phase wire 23. The amount of phase wire 21, 22, 23 on the two respective storages 51A-B, 52A-B, 53A-B, should be approximately equal, so that the part of the phase wire 21, 22, 23, respectively, between the two respective storages 51A-B, 52A-B, 53A-B is approximately the middle part of the total wire length. Thus, the winding creation process starts from the middle of the respective phase wires 21-23, and not from one of the ends as in the prior art solutions.

Fig. 7a-c further show the use of an embodiment of a support structure 60 used for holding the phase wires 21-23 in place in the winding 10. In the shown example the support structure 60 comprises warps 61 into which the wires 21-23 are woven, but any other suitable support structure can be used in the production method according to the present invention.

In accordance with the present invention the respective storages 51A-B, 52A-B, 53A-B are repeatedly transferred from one side of the support structure 60 to the other side (swapping) to form loops like the ones shown in Figure 7b. By taking this step two layers of the winding 10 can be formed, wherein phase wire ends 21a-b, 22a-b, 23a-b from the same wire 21-23 can be laid on top of each other thus making the two levels/layers.

The process sequence would be first to integrate the first three phase wire 21-23 of the three phases into the support structure 60 next to each other, then make the first loop with the phase wire 21 of the first phase by moving/swapping the storages 51A and 51B, then make the second loop with the phase wire 22 of the second phase by moving/swapping the storages 52A and 52B, then make the third loop with the phase wire 23 of the third phase by moving/swapping the storages 53A and 53B. The result of this sequence of steps is shown in Figure 7c.

The schematic representation of the cross-section of the part of the winding 10 shown in Figure 7c is given in Figure 7d. The first three phase wires 21-23 of the three phases are in the same single layer and the next three phase wires 21-23 are in two layers where the phase wires 21-23 of the same phase are located on top of each other.

The process continues until the required length of the winding 10 is reached. In the end of the production (e.g. weaving) process the last three conductors 21-23 will also be in a single layer. When the winding 10 is bent to a circular shape, the two single-layer parts will be put on top of each other forming the double-layer structure, so that the whole ironless winding 10 has two layers everywhere along the circumference.

The production process (method) as described above can be manual or automated. The support structure 60 can be of any kind, not only warps 61 like in the presented example.

Reference is now made to Figure 8 showing a schematic representation of the cross-section of the ironless winding 10 according to the present invention, where, if seen along the length of the winding 10, the phases A, B, C repeat more than one time, namely two times: for a three-phase system the sequence of phases can be A-A-B-B-C-C-A-A-...

The above-described embodiments can be combined and modified to form other embodiments within the scope of the attached claims.

The present invention is applicable for electric machines with any direction of the magnetic flux, e.g. for axial-flux or radial-flux machines, linear or planar electric machines.

The present invention is applicable for windings with number of phases.

List of designations

10 – ironless winding

21, 24 – phase wires of phase A (wire lengths of phase A)

22, 25 – phase wires of phase B

23, 26 – phase wires of phase C

21a-b – phase wire ends of phase wire 21

22a-b – phase wire ends of phase wire 22

23a-b – phase wire ends of phase wire 23

30 – weaving direction for phase wire of phase A

41 – first group of ends of phase wires

42 – second group of ends of phase wires

51A –storage containing the first part of the phase wire of phase A 52A –storage containing the first part of the phase wire of phase B 53A –storage containing the first part of the phase wire of phase C 51B –storage containing the second part of the phase wire of phase A 52B –storage containing the second part of the phase wire of phase B 53B –storage containing the second part of the phase wire of phase C 60 – support structure

61 – warps

70 – end-windings

80 – active area of the winding

101 – first end of the winding

102 – second end of the winding

Claims

1. Method of production of a double-layer multiphase ironless winding (10) of an electric machine, wherein the winding (10) comprises multiple phase wires (21, 22, 23) having respective first and second phase wire ends (21a-b, 22a-b, 23a-b) and wherein the winding (10) has two ends (101, 102) in longitudinal or circumferential direction thereof, wherein the method comprises forming the winding (10) in longitudinal or circumferential direction from one end to the other end, wherein

coiling the phase wire (21, 22, 23) length of each phase on two respective storages (51A, 51B, 52A, 52B, 53A, 53B) so that there is approximately the same length of phase wire (21, 22, 23) coiled on each of the respective storages (51A, 51B, 52A, 52B, 53A, 53B),

continuously extending the phase wires (21, 22, 23) at one end (101), wherein, when going in longitudinal or circumferential direction from the one end (101) to the other end (102) of the winding (10), changing transversal direction of and crossing the respective phase wire ends (21a-b, 22a-b, 23a-b) in end-winding (70) region of the winding (10) and arranging intermediate parts of the respective phase wires (21, 22, 23) in alternating positions in top or bottom layer in active area (80) of the winding (10),

ending up positioning all phase wire ends (21a-b, 22a-b, 23a-b) at the one and same end (102) of the winding (10), and

wherein starting winding creation process from approximately the middle of the phase wires (21, 22, 23) and the winding creation process is performed by moving the respective storages (51A, 51B, 52A, 52B, 53A, 53B) across the winding (10) in transversal direction.

2. Method according to claim 1, wherein holding the phase wires (21, 22, 23) in place by fixing or integrating the phase wires (21, 22, 23) in a support structure (60).

3. Method according to claim 2, wherein fixing or integrating the phases wires (21-23) to or in the support structure (60) by weaving.

4. Method according to claim 1, wherein bending the winding (10) to a circular shape and connecting the ends (101, 102).

5. Double-layer multiphase ironless winding (10) of an electric machine produced by the method according to any one of the claims 1-4.

6. Winding (10) according to claim 5, wherein the winding (10) comprising multiple phase wires (21, 22, 23) having respective first (21a, 22a, 23a) and second (21b, 22b, 23b) phase wire ends, wherein the winding (10) has two ends (101, 102) in longitudinal or circumferential direction thereof, and wherein all phase wire ends (21a-b, 22a-b, 23a-b) are positioned on the one and the same end (102) of the winding (10) and wherein the phase wires (21, 22, 23) are continuously extending at the other end (101) of the winding (10),

wherein the respective phase wire ends (21a-b, 22a-b, 23a-b), when going in longitudinal or circumferential direction from the one end (101) to the other end (102) of the winding (10), change transversal direction and are crossing each other in end-winding (70) region of the winding (10) arranging intermediate parts of the respective phase wire (21, 22, 23) in alternating positions in top or bottom layer in active area (80) of the winding (10).

7. Winding (10) according to claim 6, wherein the winding (10) having a support structure (60) holding the phase wires (21, 22, 23) in place.

8. Winding (10) according to claim 7, wherein the support structure (60) comprises warps (61) in which the phase wires (21, 22, 23) are weaved into.

9. Winding (10) according to claim 5, wherein the winding (10) is bent into a circular shape and the ends (101, 102) connected.

10. Winding (10) according to claim 5, wherein the winding (10) exhibits a flat shape.

11. Winding (10) according to claim 5, wherein the winding (10) is structurally enforced by being moulded in a curable liquid potting material.

12. Winding (10) according to claim 5, wherein the phase wires (21, 22, 23) are Litz-wires.

13. Winding (10) according to claim 5, wherein the number of phases (A, B, C) in the winding (10) is three.