ACTIVE ASSEMBLY OF A WIND TURBINE ROTATING ELECTRIC MACHINE

An active assembly of a wind turbine rotating electric machine has a magnetic guide having at least two slots separated by a tooth with a plane of symmetry; and a coil formed by a plurality of electric conductors, each with a substantially rectangular cross section and wound repeatedly about the tooth to fill the slots and form two heads close to the opposite ends of the tooth; the width of each electric conductor being less than a third of the distance between the electric conductor and the plane of symmetry.

BACKGROUND

Certain known wind turbines employ rotating electric machines of the type in which a rotor rotates about an axis of rotation with respect to a stator. The rotor and the stator comprise respective, supporting structures; such as tubular supporting structures and respective tubular active parts concentric with and facing one another, and fitted to the respective supporting structures. The active parts are separated by an air gap, which should be constant and relatively very small to optimize the efficiency of the rotating electric machine.

In this field, segmented active parts, (i.e., active parts divided into a plurality of axial active segments) are employed to enable relatively easy assembly, removal, and maintenance of the active parts of the rotating electric machine, which is mounted tens of metres off the ground. Each active segment can be removed and, if necessary, replaced with a new one relatively easily. The tubular active parts are secured to the respective supporting structures, which have respective mating faces for the active segments, and axial grooves configured to guide and possibly fix the respective active segments in position. The active segments of the stator normally have one or more active assemblies, by which is meant an assembly comprising a magnetic guide with at least two slots separated by a tooth; and a coil made of electric conductors and wound to fill the slots and form two heads close to the opposite ends of the tooth.

The efficiency of the electric machine depends on the extent to which the slots on each active assembly are filled. Some examples are given in U.S. Published Patent Application No. 2011/00210558 and U.S. Pat. No. 4,617,725.

Moreover, to reduce magnetic flux losses, and to reduce the size of the ends of the segments and so make the segments easier to handle, the heads of the coils must project as little as possible from the magnetic guide.

SUMMARY

The present disclosure relates to an active assembly of a wind turbine rotating electric machine.

It is an advantage of the present disclosure to provide an active assembly configured to optimize electric efficiency and easy handling.

According to the present disclosure, there is provided an active assembly of a wind turbine rotating electric machine, the active assembly comprising a magnetic guide having two slots separated by a tooth with a plane of symmetry; and a plurality of electric conductors, each with a substantially rectangular cross section and wound edgewise about the tooth to fill the slots and form two heads close to the opposite ends of the tooth, each head comprising a plurality of adjacent U-shaped turns of the electric conductors; and wherein the width of each electric conductor is less than a third of the distance between the electric conductor and the plane of symmetry of the tooth.

Because of the rectangular cross section of the electric conductors, the slots can be filled relatively evenly, and the electric conductors can all be folded into a U to form compact, relatively closely-packed heads. Accordingly, by providing the geometric as described herein, the electric conductor may be folded edgewise without damaging the electric conductor.

In certain embodiments of the present disclosure, all the electric conductors inside the slots are the same width. This solution has the advantage of, in certain embodiments, employing only one type of electric conductor.

In certain embodiments, the width of each slot substantially equals a whole multiple of the width of the electric conductors. The size of the slot is based on the size of the electric conductors.

In an alternative embodiment of the present disclosure, some of said electric conductors are of different widths; the electric conductors of larger width being located further from the plane of symmetry of the tooth than the electric conductors of smaller width. This technical solution reduces the number or quantity of electric conductors needed to fill the slot. Reducing the number or quantity of conductors improves the efficiency of the rotating electric machine by reducing the space occupied by the electric conductor insulation, and the voids formed by the rounded corners of the rectangular cross section of the electric conductor.

In certain embodiments, the respective widths of the electric conductors increase as a function of the distance between the electric conductors and the plane of symmetry of the tooth.

The conductor furthest from the plane of symmetry may be much wider than the one closest to the plane of symmetry. In certain embodiments, the width increases linearly with the distance from the plane of symmetry of the tooth. In this configuration, the width of the slot substantially equals the sum of the widths of all the electric conductors.

The present disclosure also relates to an active segment.

According to the present disclosure, there is provided a wind turbine rotating electric machine active segment comprising at least one active assembly as defined above.

The present disclosure also relates to a wind turbine rotating electric machine.

According to the present disclosure, there is provided a wind turbine rotating electric machine; the rotating electric machine being a synchronous, permanent-magnet type, and comprising a stator, and a rotor which rotates about an axis of rotation about the stator; the stator comprising a tubular supporting structure, a tubular active part fitted to the supporting structure, and a plurality of active assemblies arranged uniformly about the axis of rotation to form said active part, and as defined above; and the rotor comprising a further tubular supporting structure, and a further tubular active part fitted to the further supporting structure.

The rotating electric machine is thus relatively highly efficient and relatively easy to maintain.

The present disclosure also relates to a wind turbine configured to produce electric energy.

According to the present disclosure, there is provided a wind turbine configured to produce electric energy; the wind turbine comprising a vertical structure and a main frame configured to support in an elevated position a rotating electric machine as defined above.

DETAILED DESCRIPTION

Referring now to the example embodiments of the present disclosure illustrated inFIGS. 1 to 7, number1inFIG. 1indicates as a whole a wind turbine configured to produce electric energy. Wind turbine1is a direct-drive type. In the example shown, wind turbine1comprises a vertical structure2; a main frame3fitted in rotary manner to the top of vertical structure2; a rotating electric machine4; and a blade assembly5which rotates about an axis of rotation A. Rotating electric machine4is located between main frame3and blade assembly5, and, in addition to producing electric energy, also serves to support blade assembly5and to transmit forces and moments induced by blade assembly5and rotating electric machine4to main frame3.

In the example shown, main frame3is defined by a curved, tubular nacelle.

Blade assembly5comprises a hollow hub6connected to rotating electric machine4; and a plurality of blades7.

Rotating electric machine4extends about axis of rotation A, and is substantially tubular to form a passage between the hollow main frame3and hollow hub6. Rotating electric machine4comprises a stator8; and a rotor9located inside stator8, and which rotates with respect to stator8about axis of rotation A.

With reference toFIG. 2, stator8comprises a tubular supporting structure10; and a tubular active part11comprising a plurality of axial active segments12. Similarly, rotor9comprises a tubular supporting structure13; and a tubular active part14comprising a plurality of axial active segments15. As shown inFIG. 1, supporting structure10is connected to main frame3, and supporting structure13is connected to blade assembly5.

Supporting structure10has a mating face16—in the example shown, a cylindrical mating face—along which active segments12rest. In the example shown, each active segment12comprises a lamination pack17, which is substantially prismatic in shape, extends mainly axially, and has a mating face18configured to rest on mating face16, and a plurality of teeth19projecting on the opposite side to mating face18; and a plurality of coils20wound about teeth19to define field poles.

More specifically, each segment15comprises an assembly21of magnetic guides and permanent magnets; and a gripper22configured to grip assembly21. Gripper22is positioned resting on and fixed to tubular structure13.

The system configured to lock segments12is configured to fix each segment12to tubular structure10independently of the other segments12. Accordingly, supporting structure10has a plurality of grooves23, which extend inside the body of supporting structure10, along mating face16. Grooves23themselves define locks configured to lock active segments12, and cooperate with further locks (not shown) configured to cooperate with grooves23.

In the example shown, supporting structure10has a number or quantity of grooves23equal to the number or quantity of segments12. And each segment12has a groove24configured to face and communicate with a respective groove23.

Each coil20is defined by a plurality of electric conductors25, each wound about a tooth19. In theFIG. 3example, five conductors25are wound about tooth19.

Active segments12and15are removable selectively from rotating electric machine4in a direction D1, and are insertable selectively onto rotating electric machine4in the opposite direction to direction D1.

With reference toFIG. 3, each conductor25has a substantially rectangular cross section, a width L1(long side), and a height H1(short side). It should be appreciated that the cross section of electric conductor25differs slightly from a rectangle by having rounded corners. Each conductor25comprises a metal core26, and an insulating sheath27covering metal core26. Electric conductor25is particularly rigid, and can be deformed permanently lengthwise into various shapes. Electric conductor25, with the technical characteristics described, are normally referred to as a ‘flat’ because of its flat shape.

With reference toFIG. 4, the assembly defined by the portion of lamination pack17with a tooth19and two slots28on opposite sides of tooth19, and by a coil20wound about tooth19, is referred to as active assembly29. In addition to two parallel portions housed inside slots28, coil20also comprises two heads30at opposite ends of tooth19, and two connecting ends31.

Electric conductors25are folded edgewise about tooth19at heads30. More specifically, electric conductors25are wound about tooth19in a pattern of concentric spirals or similar spirals. In other words, a first electric conductor25is wound directly about a tooth19along a first spiral path; and a second electric conductor25is wound directly about the first electric conductor25along a second spiral path. The other electric conductors25are wound in further patterns similar to those of the first and second electric conductor25. And, depending on the location of electric conductors25inside slots28, electric conductors25define turns C1, C2, C3, C4, C5, which increase in radius of curvature from tooth19.

With reference toFIG. 5, each tooth19has a plane of symmetry S, which substantially also defines the plane of symmetry of coil20. In the example shown, the width L2of slots28substantially equals a whole multiple of the width L1of electric conductors25; or conversely, the width L1of electric conductors25substantially equals a submultiple of the width L2of slots28. The width L1of the electric conductor is selected so that it is less than a third of the distance D between electric conductor25and the plane of symmetry S of tooth19.

With reference toFIG. 4, conformance with the above condition enables electric conductor25to be folded edgewise to form turn C1and, consequently, also turns C2, C3, C4C5at heads30without damaging metal core26or insulating sheath27of electric conductor25(FIG. 3).

In the example shown, for the sake of simplicity and component part standardization, electric conductors25are all of the same width L1and the same size in general. This way, turns C1, C2, C3C4, C5are all U-shaped, and the resulting heads30are closely-packed and compact with very little jut-out.

With reference toFIGS. 6 and 7, an embodiment of the present disclosure employs electric conductors25of the same height H1, but different widths L1and L3, where L3is greater than L1.

Basically, the principle employed is to use electric conductors25increasing in width with the distance D from the plane of symmetry S of tooth19. This way, slot28is filled with fewer electric conductors25—in the example shown, four as opposed to the five conductors inFIGS. 4 and 5.

With reference toFIG. 6, the four electric conductors25form, at heads30and working outwards of tooth19, four turns C1, C2, C6, C7of increasing radius of curvature. It should be appreciated that the increasing width of electric conductor25as a function of the distance from tooth19is not essential to the present disclosure.

Clearly, changes may be made to the active assembly according to the present disclosure without, however, departing from the protective scope of the accompanying Claims. That is, various changes and modifications to the presently disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.