EP3698454A1

EP3698454A1 - Toroidal polyphase electric machine

Info

Publication number: EP3698454A1
Application number: EP18803743.6A
Authority: EP
Inventors: Gaël ANDRIEUX; Arnaud HYPPIAS; Laurent HERBEIN
Original assignee: Moving Magnet Technologie SA
Current assignee: Moving Magnet Technologie SA
Priority date: 2017-10-17
Filing date: 2018-10-16
Publication date: 2020-08-26
Also published as: KR20200073262A; US20200295641A1; FR3072517B1; JP2020537864A; US11967870B2; WO2019077261A1; FR3072517A1; CN111316536A

Abstract

The invention relates to an electric machine having a rotor (11a, 11b, 11c) comprising a set of permanent magnets (13a, 13b, 13c, 13d, 13e, 13f, 13g) and a stator comprising a stator strip (1) made of a soft ferromagnetic material, said strip (1) supporting a coil body (4) having a single discontinuity, said coil body (4) supporting a plurality of wire coils (8) so as to form a polyphase coil stator assembly (10) of the toroidal type, characterised in that said strip (1) has a single discontinuity and has at least one partial cut (2) at regular intervals between two consecutive wire coils (8).

Description

POLYPHASE ELECTRO TOROIDAL ELECTRIC MACHINE

TECHNICAL FIELD OF THE INVENTION

The invention relates to the field of polyphase electrical machines and more particularly to an advantageous embodiment of machines called toroidal winding, or circumferential winding, that is to say machines in which the winding axes follow the direction circumferential stators of said machines.

The invention also relates to a method of producing a toroidal type electrical machine, allowing significant gains in terms of number of parts and performance.

STATE OF THE PRIOR ART

Already known in the state of the art electrical machines toroidal type as for example described in US9470238 and EP1324472.

These devices, however, have segmented stators, that is to say made in several distinct parts on which are positioned, unitarily, wound assemblies, said assemblies are subsequently assembled together. This construction, although allowing a technically viable embodiment, however, involves a large number of manufacturing steps and manipulations that makes industrial and economic viability very difficult.

Also known is the document JP1980173254, older, which describes the embodiment of a toroidal winding motor. In the illustrated embodiments, discrete windings are inserted one by one on a strip wound of material, forming the ferromagnetic stator of the machine.

This achievement also proves industrially unattractive by the large number of parts, in this case wound assembly to achieve and position precisely on the stator. The rolled form of the stator does not help, moreover, to the implementation. More recently known document US7145280 which shows an improved embodiment of a toroidal machine from a ferromagnetic core in the form of a strip on which are positioned in a discrete manner the coils.

This achievement improves the previous achievements but still poses a problem in terms of the number of discrete parts to handle and does not explain how the core must be wound once the assembly of the coils realized. It seems difficult to conceive of winding a thick solid material, so that only small sections of cores are realistic, which implies a realization of low performance machines.

SUMMARY OF THE INVENTION

The present invention aims to overcome the disadvantages of the state of the art by proposing a simplified embodiment and more economically viable. In particular, the invention aims to reduce the number of parts used to produce a toroidal electric machine.

It is also for the purpose of the invention to allow a simplified winding of the stator of the machine by the play of a particular geometry.

It is also for the purpose of the invention to provide a method of realization simplifying the techniques implemented in the state of the art.

More particularly, the invention provides an electric machine having a rotor comprising a set of permanent magnets and a stator comprising a stator strip of a soft ferromagnetic material, said strip carrying a coil body carrying a plurality of coils of wires so as to form a toroidal polyphase coiled stator assembly. The strip advantageously has a single discontinuity and periodically exhibits at least one partial cut between two consecutive wire coils in order to obtain a polygonal shape of said strip within said plurality of wire coils.

In different embodiments, the machine has: a rotor with two radial rows of permanent magnets located on either side, radially, of the coiled stator assembly,

a rotor with a third row of magnets situated radially at the same level of the coiled stator assembly and above axially of said coiled stator assembly,

a crown with a welded seam ensuring the circumferential closure of said ring.

Alternatively, are inserted into the coil body, between the consecutive son coils, polar parts and the number of partial cuts of the strip is two.

In particular embodiments, the invention relates to a three-phase machine. The set of wire coils is wound with a continuous wire to make a connection between said three phases, and the electrical assembly of the three phases is achieved by local cuts of the son. The polyphase coiled stator assembly is in a star or parallel arrangement with, for each phase, assemblies in series or parallel of several coils of wires.

The invention also proposes a method of winding a stator assembly for an electric toroidal winding machine, comprising a sequence of steps that consist of:

forming a linear continuous strip into a ferromagnetic material having periodically partial cuts forming, for each cut, two disjointed flanks,

forming a linear continuous coil body presenting a set of reception zones,

forming a set of coils arranged in a linear arrangement of adjacent coils housed in said receiving areas, said linearly arranged coils being wound with a continuous wire or a continuous set of parallel wires for each phase, -pliering the linear arrangement of the stator assembly formed by said linear continuous band into a ferromagnetic material, by said linear continuous coil body and said coil assembly to form a torus, wherein the coils aligned along a circumference forms a toroidal winding of an electric machine and for which said disjoint flanks are contacted, and wherein said strip has a polygonal shape within the set of yarn packages.

Preferably, for this method, said machine is a three-phase machine and said linearly arranged coils are wound with a continuous wire and said continuous wire also carries the connection between said phases, and said continuous wire is then cut locally to achieve the electrical assembly of the three phases.

The polyphase coiled stator assembly may be in a star or parallel arrangement with, for each phase, assemblies in series or parallel of several coils.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will emerge from the following reading of detailed embodiments, with reference to the appended figures which respectively represent:

FIGS. 1a, 1b and 1c, respectively, an isolated view of a stator unwound from a machine according to the invention before insertion of the coil body, an isolated view of a linear matrix of strips and an isolated view a matrix of superimposed bands,

FIGS. 2a, 2b and 2c, isolated views of a cut of a stator strip unrolled from a machine according to the invention before insertion of the bobbin body,

FIGS. 3a and 3b are isolated views of an unwound coil body intended for a machine according to the invention and according to two different embodiments, - Figure 4 an isolated view of a coil body according to Figure 3a on which are wound electrical son,

FIGS. 5a and 5b are isolated views of a coil body intended for a machine according to the invention, showing respectively an example of coil wire passage and flexible bridges of the coil body,

FIG. 6, a view of a coil body according to the invention illustrating the winding of a particular machine,

FIGS. 7a and 7b, insulated views of the respectively wound and unwinded coil body of FIG. 4, in which is inserted the unwrapped stator of FIG. 1 respectively after or before the winding of the body,

FIGS. 8a to 8d, isolated views of examples of closure of the stator assembly,

FIGS. 9a and 9b, axial views of a machine according to the invention in two different embodiments,

FIGS. 10a, 10b and 10c are isolated sectional views of examples of machines according to the invention with different use of magnets,

FIGS. 11a, 11b, 11c, 11d and 1b are sectional views of examples of machines according to the invention with different use of magnets,

FIGS. 12a, 12b and 12c, views of a particular embodiment of the magnets of a machine according to the invention,

FIG. 13, an isolated view of a magnetized ring of a machine according to the invention according to a particular embodiment,

FIGS. 14a, 14b and 14c, various views of an embodiment of an axial flow machine according to the invention,

FIG. 15, an exploded isolated view of an embodiment of a machine with two independent electrical networks,

FIG. 16, an alternative embodiment of a coil body according to the invention,

FIGS. 17a, 17b and 17c, views of a first embodiment integrating ferromagnetic poles,

- Figures 18a and 18b, views of a second embodiment incorporating ferromagnetic poles. DETAILED DESCRIPTION OF AN EMBODIMENT

A first part of the object of the invention is appraised in Figure 1a, which shows a strip (1) stator unwound from an electric machine according to the invention. This stator band (1) is generally in the form of a plate of soft ferromagnetic material, several of these strips being superposable in order to obtain a strip which forms the core of the stator. This stator band (1) comprises regularly spaced cuts (2) whose shape can be variable but allow the contact of the lateral flanks (3a, 3b), better visible in FIGS. 2a to 2c, during the winding of the stator band (1), while these flanks (3a, 3b) are disjoint in this unwound form. The shape of the cutoff (2) and the flanks (3a, 3b) is not limiting and FIGS. 2a to 2c show only a few exemplary embodiments. In the example of FIGS. 2a and 2b, for a stator intended to present 12 coils, the angle formed by the cutoff (12) will preferably be close to 30 ° in order to allow contact of the flanks (3a, 3b). In the example of Figure 2c, for a stator for presenting 9 coils, the angle formed by the cutoff (12) will preferably be close to 40 °. In order to facilitate the elastic deformation it may be envisaged to perform a local material removal (22) above the cut (12) as shown, for example, in Figure 2b.

The stator strip (1) can be made from a linear continuous strip matrix (15) as shown in FIG. 1c, or from an array of superposed stripes (16) as shown in FIG. 1 b, without these examples being limiting in their possible achievements.

A second part of the object of the invention is appreciated in Figures 3a and 3b, showing a coil body (4) of an electric machine according to the invention and according to two different embodiments. This coil body (4) is in the form of a linear strip before mounting the stator and made of an electrically insulating material, preferably of the plastic type. The bobbin body (4) can optionally be loaded with ferromagnetic particles to improve the magnetic performance of the machine. The coil body (4) has a a multitude of reception zones (5), the number of which is preferably equal to the number of cuts (2) of the stator band (1) minus one unit. In the first mode in FIG. 3a, the coil body (4) also has a succession of pins

(6) intended to allow the guiding of a winding wire, not shown here, and cavities called IDC (7) - for insulation displacement contact in English - for receiving displacement blades (not shown) of displacement type insulation. The placement and the number of these pins (6) and cavities (7) can vary depending on the type of connection - series, parallel, star, triangle - and are given here as an example for a machine with 12 coils connected in a triangle series. The coil body (4) further has a longitudinal opening (9) therethrough.

A second example of a coil body (4) is given in FIG. 3b. This coil body (4) does not have a pin (6) but only IDC cavities

(7) which also allow the guiding of the wires.

A third example of a coil body (4) is given in FIG. 16. This coil body (4) has forks (20) for welding the wires when this solution is preferred.

Figure 4 shows the coil body (4) after winding a wire (8) conductor (typically copper, silver or aluminum). The winding method and the advantages of the coil body (4) are explained in FIGS. 5 and 6.

FIG. 5a shows, for example, in an isolated view of a few reception zones (5) of the coil body (4), the theoretical path of a wire (8) around the pins (6) in the where the coil body (4) comprises such pins (6) in a clockwise (CW) or counterclockwise (CCW) direction relative to the longitudinal opening (9). The pins (6) serve to guide the wire (8) during the winding and ensure that it remains on the average fiber, that is to say in the plane cutting longitudinally the coil body (4) and passing through the IDC cavities (7) during winding.

Figure 5b illustrates the bridges (21) flexible between the receiving areas (5) of the coil body (4) and which ensure the continuous connection of the latter. These bridges (21) also give the degree of freedom to the body of coils (4) allowing it to deform during the shaping of the stator assembly (10). In the example illustrated here, these bridges (21) are two in number between each receiving zone (5), and are situated on the lower part and the upper part of the body (5) on either side of the stator band (1) (not shown here) and symmetrically on the depth of the body (4). This embodiment of the bridges (21) is non-limiting and the shape, position and number of bridges (21) can be modified without departing from the scope of the invention.

Figure 6 shows that it is possible with the concept of the present invention to wind the entire coil body (4) with a single wire (8) in a single continuous operation. The three reel body strings (4) of this figure 6 represent one and the same reel body (4), but shown in three wire winding steps (8) for better understanding. Thus for the winding of a stator carrying 12 coils in an operation whose wiring is called "triangle-series-parallel", that is to say having 4 coils per phase and whose coils of a phase are in series one by one and in parallel two by two, it is possible to circulate a single wire (8) as shown and cut said wire (8) in two places, the scissors schematically showing the necessary cutting locations. This winding "triangle-series-parallel" is given as an example and is in no way limiting. It is thus possible to achieve different wiring in accordance with the invention, although this wiring is preferably considered for its simplicity of implementation.

Once wound, the coil body (4) receives in its longitudinal opening (9) the superimposed unrolled stator strips (1) which are thus inserted into the coil body (4) in the direction given by the arrow thick in Figure 7a. It is also notable that it is possible, again according to the invention, to provide for the mounting of the stator strip (1) in the coil body (4) before the winding thereof, as illustrated in FIG. 7b.

Once the coil body (4) wound and the strip (1) inserted stator - before or after winding - the stator assembly (10) thus formed is shaped circular by folding the latter at the cuts (2). The closure of the stator assembly (10) is then made according to different modes as illustrated in FIGS. 8a to 8d. In FIG. 8a, the joint is made by a weld (17), in FIG. 8b the joint is made by the coil body (4), in FIG. 8c, the joint is made by an insert (18) at the body of coil (4) and in Figure 8d, the joint is formed by against-forms (19) at the level of the strip (1) of the stator. A dovetail principle can also be envisaged (not shown) at the stator strip (1). Similarly, the joining and closing of the stator assembly can be achieved by overmoulding into an injectable material.

Figures 9a and 9b show an electric machine according to the invention in two different embodiments, for example, once The stator strip (1) inserted into the coil body (4) and the stator assembly (10) wound so that the flanks (3a, 3b) are joined. The stator strip (1) has a polygonal shape within said plurality of wire coils. The machine according to the example of Figure 9a is a three-phase machine having 9 coils and two rotors (1 1a, 1 1b) formed by multipole magnet rings (13a, 13b) alternating polarities North and South - here 5 pairs of poles for each rotor- and ferromagnetic yokes (12a, 12b). The rotors (1 1 a, 1 1 b) are located respectively radially outside and inside, of the stator assembly (10), and are advantageously integral with each other.

In the second embodiment of Figure 9b, the machine comprises 12 coils and 4 pairs of poles per rotor (1 1 a, 1 1 b).

It should be noted that the shape of the multipole magnet rings (13a, 13b) may be variable and in particular have radial extensions (14), as shown in FIGS. 10a to 10c, in order to increase the active surface area of the magnets (13a, 13b) opposite the wound wire (8). In these illustrations 10a to 10c, showing isolated sectional views of a machine according to the invention, the bobbin body (4) is not illustrated to simplify understanding. The invention allows to use an inner magnet (13b) and outer (13a), as shown in Figure 1 1a, but also to use in addition an axial magnet (13c) located axially relative to the assembly stator (10), as shown in Figures 1 1 b, or to use a radial magnet and an axial magnet, as shown in Figure 1 1 c. Advantageously, the magnets (13a, 13b and 13c) are integral with each other. According to the invention, it is possible to use only one inner magnet (13b) as shown in FIG. 11d or a single external magnet (13a) as shown in FIG.

The various magnetic rings used for a machine according to the invention can be rigid rings or be made in the form of a flexible strip (19), illustrated in FIG. 12a, cut to form a magnet (13d), and magnetized to make a magnetic strand illustrated in Figure 12b, then shaped and positioned inside the ferromagnetic yoke (12a) as shown in Figure 12c.

The magnetization of the magnets of a machine according to the invention can be carried out radially unidirectionally as shown in Figures 9a, 9b and 9c or be performed in a sinusoidal evolution of the magnetization angle as presented in Figure 13 - Thick arrows showing the local magnetization direction in the magnet. In this embodiment, it is possible to eliminate the use of the yoke, the magnetic field being looped mainly inside the magnet (13e), which notably makes it possible to improve the dynamic performance of the machine by decreasing rotor inertia and phase inductance.

Figures 14a to 14c are illustrations of an embodiment of the invention of an axial flow machine. The stator strip (1) consists of a plurality of ferromagnetic sheets stacked according to the width of the strip (1) and the magnets (13f, 13g) are located, after assembly of the stator assembly (10), of part and of other of the latter, axially.

The invention also makes it possible to produce a machine having two independent coil networks in order to ensure the operation of the machine. even when one or the other of the wound networks is defective (short circuit for example). FIG. 15 illustrates the concept of this particular embodiment with two different stator sets (10a, 10b) which are made separately in the same way as previously presented and then assembled together, for example, the techniques presented in FIGS. 8a to 8d.

The embodiments described above all relate to topologies of electrical machines called "without notch" (slotless English), but this feature is in no way limiting. Indeed, as can be seen in the embodiments of FIGS. 17a, 17b, 17c, 18a and 18b, it is possible to envisage the production of a machine with notches by integrating pole pieces (23), that is to say to say ferromagnetic poles, while respecting the spirit of the invention.

Figures 17a and 17b show the body of coils (4) respectively with and without the conductive son wound (8) for a machine stator having 6 pole pieces and 6 son coils (8). These bodies (4) have inserted pole pieces (23) whose geometry is given as an example in FIG. 17c. In this non-limiting example, each pole piece is in the form of portions of stacked sheets. It can also be envisaged that these polar pieces are massive. In the spirit of the invention, these pole pieces (23) are inserted mechanically before or after the winding of son (8) in the coil body (4).

Figure 18a shows a second example where pole pieces (23) are reported in the coil body (4) for a machine having here 12 pole pieces (23) and 12 son coils (8). FIG. 18b is a longitudinal sectional view of FIG. 18a, in which the two breaks (2), in particular, are separated between the coils of wires (8) in order to allow the winding of the stator assembly to realize a rotating machine.

Claims

1. An electric machine having a rotor (11a, 11b, 11c) comprising a set of permanent magnets (13a, 13b, 13c, 13d, 13e, 13f, 13g) and at least one stator assembly (10) comprising a stator strip (1) of a soft ferromagnetic material, said strip (1) carrying a coil body (4) carrying a plurality of wire coils (8) so as to form the polyphase coiled stator assembly (10) of toroidal type characterized in that said strip (1) has periodically at least one cut (2) partial between two son coils (8) consecutive to obtain a polygonal shape of said strip within said plurality of coils of son (8).

2. Electrical machine according to claim 1 characterized in that said rotor (1 1 a, 1 1 b, 1 1 c) has two radial rows of permanent magnets (13a, 13b) located on either side, radially, the stator assembly (10) wound.

3. Electrical machine according to claim 2 characterized in that said rotor (1 1 a, 1 1 b, 1 1 c) has a third row of magnets (13c) located radially at the same level of the stator assembly (10) wound and above, axially, said coiled stator assembly (10).

4. Electrical machine according to any one of the preceding claims characterized in that said strip (1) has a welded seam ensuring the circumferential closure of said strip (1).

Electric machine according to one of the preceding claims, characterized in that pole pieces (23) are inserted into the coil body (4) between two consecutive wire coils (8) and in that the number of partial cuts (2) of the band (1) is two.

Electric machine according to any one of the preceding claims characterized in that said machine is a three-phase machine, in that the set of wire coils (8) is wound with a continuous wire (18) in order to make a connection between said three phases, and in that the electrical assembly of the three phases is achieved by local cuts of the wire (18)

7. Electrical machine according to the preceding claim characterized in that the stator assembly (10) polyphase coil is in a star or parallel arrangement with for each phase, assemblies in series or parallel of several son coils (8).

A method of winding a stator assembly (10) for a toroidal electric winding machine, comprising a sequence of steps which comprises:

forming a linear continuous strip (1) of a ferromagnetic material having periodically partial cuts (2) forming, for each cut (2), two disjointed flanks (3a, 3b),

forming a linear continuous coil body (4) presenting a set of reception zones (5),

forming a set of wire coils (8) arranged in a linear arrangement of adjacent coils housed in said receiving areas (5), said wire coils (8) being linearly wound with a continuous wire (8) or a continuous set of parallel wires for each phase, -folding the stator assembly (10) formed by said linear continuous strip (1) into a ferromagnetic material, by said linear continuous coil body (4) and said coil assembly of wires (8) to form a toroid, in which the coils form along the circumference a toroidal winding of an electric machine, for which said disjointed flanks (3a, 3b) are brought into contact, and wherein said strip has a polygonal shape within the set of wire coils (8).

9. A method of winding a stator assembly (10) for an electric machine according to the preceding claim characterized in that said machine is a three-phase machine and in that said wire coils (8) linearly arranged are wound with a wire (8) continuous and in that said continuous wire (8) also carries out the connection between said phases, and in that said continuous wire (8) is then cut locally to perform the electrical assembly of the three phases.

10. A method of winding a stator assembly for an electric machine according to the preceding claim characterized in that the stator assembly (10) polyphase coil is in a star or parallel arrangement with for each phase, assemblies in series or parallel several coils of threads (8).