Demagnetization of magnet element of wind turbine generator

Abstract

A demagnetization system for demagnetizing a magnet element (10) of a wind turbine generator component is provided. The magnet element (10) comprises at least one permanent magnet block (15). The demagnetization system (100) comprises a magnetoresistive modulation component (20) and a movement arrangement (70) configured to provide relative movement between the magnetoresistive modulation component (20) and the magnet element (10). The reluctance modulation member (20) is configured to vary the reluctance experienced by the magnetic flux of the one or more permanent magnet blocks (15) as the reluctance modulation member (20) moves past the magnet element (10). The system is configured to generate an eddy current in the at least one permanent magnet block (15) by providing said relative movement between the reluctance modulation component (20) and the magnet element (10), where the eddy current heats the at least one permanent magnet block (15) to be demagnetized.

Description

Technical Field

[0001] The present invention relates to a demagnetization system for demagnetizing a magnetic element of a wind turbine generator component and to a corresponding method for demagnetizing such a magnetic element. Background Art

[0002] Over the past few years, the size of wind turbines and their power output have increased significantly. Modern high-power wind turbines include direct-drive wind turbines, in which the generator rotor is directly coupled to the wind turbine rotor without an intermediate gearbox. Such direct-drive generators typically employ permanent magnets, often on the generator rotor. For an exemplary wind turbine, six tons of NdFeB (neodymium iron boron) permanent magnets may be used on the generator rotor. It is desirable to reuse the permanent magnet material and, in particular, to recycle such permanent magnet material at the end of the life of the corresponding wind turbine generator.

[0003] However, this recycling faces several difficulties. In order to reuse the material of the permanent magnet, it is usually necessary to demagnetize the permanent magnet. Demagnetization can be carried out by heating the permanent magnet up to the Curie temperature. For example, NdFeB permanent magnets can be heated to up to 350°C for demagnetization. The magnet elements used in wind turbine generators are usually of considerable size, such as approximately 100x20x70 mm. The inventors have found that in order to demagnetize the corresponding magnet element, the element can be placed in an oven and heated for approximately 40 minutes, which is required to achieve a stable temperature throughout the magnet element.

[0004] Therefore, this way of demagnetizing the magnetic elements is time-consuming. In addition, heating may require a relatively large amount of energy. Furthermore, it may not be possible to place several modules into the oven because large forces are established between the magnetic elements, which may damage the equipment and may pose a risk to the operator operating the equipment. Therefore, demagnetization may be inefficient and time-consuming. It is generally difficult to provide demagnetization using equipment similar to a magnetizer because this requires disassembling the magnetic elements, which is difficult to achieve as long as the permanent magnet blocks inside the magnetic elements are still magnetized. In addition, demagnetization using induction heating faces the following difficulties: the heating frequency may depend on the structure of the magnetic elements (which may include magnet covers, steel plates, etc.) and may need to be adjusted for different types of elements. Therefore, it is desirable to facilitate the demagnetization of such magnetic elements. Summary of the Invention

[0005] Therefore, there is a need to alleviate at least some of the above mentioned disadvantages and improve the demagnetization of magnet elements. It is particularly desirable to increase the efficiency of the demagnetization, to make the demagnetization more flexible and / or to improve the safety of service personnel performing the demagnetization.

[0006] This need is met by the features of the independent claim.The dependent claims describe embodiments of the invention.

[0007] According to one embodiment of the present invention, a demagnetization system for demagnetizing a magnetic element of a wind turbine generator component is provided. The magnetic element includes at least one permanent magnet block. The demagnetization system includes a reluctance modulation component and a movement arrangement configured to provide relative movement between the reluctance modulation component and the magnetic element. The reluctance modulation component is configured to change the reluctance experienced by a magnetic flux of one or more permanent magnet blocks when the reluctance modulation component moves past the magnetic element. The system is configured to generate eddy currents in the at least one permanent magnet block by providing relative movement between the reluctance modulation component and the magnetic element, wherein the eddy currents heat the at least one permanent magnet block.

[0008] By this heating of the permanent magnet blocks, the magnet elements can be demagnetized in an efficient manner. In particular, the eddy currents can be the result of the magnetic flux density of the permanent magnet blocks themselves, so that the heating process can be concentrated within the permanent magnet material. Therefore, efficient heating of the permanent magnet blocks can be achieved. In particular, the relative movement between the reluctance modulation component and the magnet element can cause the reluctance of the magnetic circuit through at least one permanent magnet block to change, thereby causing the magnetic flux through the permanent magnet block to change. This change in flux may induce eddy currents in the permanent magnet blocks, which heat the permanent magnet blocks. The change in reluctance due to the relative movement can in particular change the magnetic flux density (i.e. the B field), the flux through the surface being the surface integral of the B field over the corresponding surface.

[0009] Reluctance can also be described as a type of magnetic resistance. Specifically, it is the resistance experienced by magnetic flux in a magnetic circuit. Magnetic flux corresponds to magnetomotive force divided by reluctance. When reluctance changes, permeance changes inversely; permeance corresponds to magnetic conductance and is the inverse of reluctance. Reluctance can be understood as the property of a material that hinders the flow of magnetic flux in a magnetic circuit (similar to resistance, which hinders the flow of current in an electrical circuit).

[0010] Because with this system, heating occurs via eddy currents generated in the permanent magnet mass, heating may not rely on any other components that may form part of the magnet element, such as a housing, enclosure or encapsulation, base plate, cover, etc. Furthermore, with this direct heating, the energy required for heating may be reduced, and heating may occur faster and more efficiently.

[0011] In one embodiment, a reluctance modulation component (which may be abbreviated herein as a modulation component or simply a component) may have a spatial extension in the direction of relative movement. The reluctance of the reluctance modulation component may vary along the spatial extension. When the modulation component moves relative to the magnet element, the magnetic flux generated by at least one permanent magnet segment may therefore experience a difference in magnetic permeability (due to the movement and because the component has a varying reluctance along its extension), thereby resulting in flux modulation and corresponding eddy current generation. Such an extension of the modulation component may be a linear extension or a circumferential extension, such as a circular extension.

[0012] The magnetic permeability of the reluctance modulation component can vary along the spatial extension of the reluctance modulation component, for example, repeatedly or periodically. This variation in magnetic permeability can occur gradually, continuously, or the like. This variation in magnetic permeability can be achieved, for example, by disposing different types of materials with different magnetic permeabilities along the spatial extension of the component. Generally speaking, reluctance is inversely proportional to magnetic permeability.

[0013] The reluctance modulation component may, for example, comprise different segments in the direction of relative movement. These segments may face the magnetic element. Adjacent segments may have different reluctances, and in particular different permeabilities, to provide a variation in reluctance. As an example, the component may have alternating segments of ferromagnetic material and paramagnetic material (such as air) or diamagnetic material. Thus, when the modulation component moves relative to the magnetic element, an efficient variation in reluctance may be achieved. Consequently, different segments of the component may present different reluctances to the flux generated by the at least one permanent magnet block.

[0014] The width of each segment in the direction of relative movement can be less than half the extension of the magnet element in the direction of relative movement. With this geometry, a higher frequency change in magnetic resistance can be achieved, thus leading to higher eddy currents and higher heat losses.

[0015] In one embodiment, the reluctance modulation component can be a circular component having an (inner or outer) circumferential surface facing the magnetic element. The relative movement can include relative rotational movement between the circular component and the magnetic element. The magnetic element can be arranged outside the circular component in a radial direction, for example, or inside the circular component in a radial direction. With this arrangement, a continuous and repeated change of the reluctance can be achieved, thereby providing a fast and efficient induction of eddy currents and heating. For example, the circumferential surface can have a (periodically) changing reluctance. It can include different segments, which can alternate in the circumferential direction, and adjacent segments have different magnetic permeabilities.

[0016] The circular component may be a rotor, and the movement arrangement may be configured to rotate the rotor relative to the magnet element. Thus, the movement arrangement may be implemented with reduced technical complexity and may provide relative movement in an efficient manner. In particular, such an arrangement may allow the flux of the magnet element to experience high-frequency reluctance variations.

[0017] The moving arrangement may for example comprise a motor to rotate the rotor. The motor may be an electric motor, such as an induction motor, but may alternatively be a hydraulic or pneumatic motor.

[0018] The rotor may have a plurality of magnetic poles, and when the magnetic poles rotate through the magnetic element, the magnetic poles may cause a change in magnetic resistance. Such magnetic poles may, for example, be projections protruding from a ring or disk of the rotor. Such magnetic poles may be made of ferromagnetic material, such as iron or an iron-based material. In particular, the magnetic poles may have a first, higher magnetic permeability, and the magnetic poles may be separated by regions (such as slots) having a second, lower magnetic permeability (e.g., air). Therefore, when the magnetic poles rotate through the magnetic element, the magnetic flux provided by the permanent magnet block experiences a changing magnetic resistance, thereby modulating the magnetic flux and providing efficient generation of eddy currents.

[0019] The rotor may be a salient-pole rotor. Thus, the rotor may have high salient properties. Optionally, the magnetic poles of the rotor may have pole shoes. Preferably, the rotor does not have a rotor winding.

[0020] In an exemplary embodiment, the mobile arrangement can be configured to rotate the rotor at at least 3000 rpm. This may result in high-frequency changes in the reluctance experienced by the permanent magnet segments and, therefore, in high-frequency changes in the magnetic flux, thereby leading to the generation of an increase in eddy currents. In an example, the diameter of the rotor may be at least 0.5 or 1 m. The rotor may have at least 20, 30 or 40 poles. By increasing the number of poles, the frequency of the changes in reluctance experienced by the flux of at least one permanent magnet segment can be further increased. It will be clear that parameters such as the diameter of the rotor, the air gap towards the magnet elements and the number of poles can be adjusted according to the size of the magnet elements, in particular the size of one or more permanent magnet segments.

[0021] In one example, the frequency at which the magnetic poles of the rotor pass the magnet elements may be at least 300, 500 or 1,000 Hz. The frequency may be in the range of 1,000 to 10,000 Hz.

[0022] The rotor may be a laminated rotor. For example, the poles may be composed of laminated sheets, which may be arranged to reduce eddy currents induced in the rotor. This may prevent excessive heating of the rotor due to eddy currents induced in the rotor.

[0023] In one embodiment, the demagnetization system further comprises at least one second reluctance modulation component, wherein the magnetic element is arranged between the reluctance modulation component and the second reluctance modulation component. The mobile arrangement can also be configured to provide relative movement between the second reluctance modulation component and the magnetic element. The second reluctance modulation component can be configured to change the reluctance experienced by the magnetic flux of one or more permanent magnet blocks when the second reluctance modulation component moves past the magnetic element. Therefore, the second reluctance modulation component can provide a similar function to the previously mentioned (first) reluctance modulation component, and it can have a similar structure. It can in particular include corresponding sections with different reluctances, in particular different magnetic permeabilities. By providing such a second reluctance modulation component, demagnetization can be further accelerated.

[0024] The second reluctance modulation component can, for example, be implemented as a second rotor, complementary to the above-mentioned (first) rotor. For example, one or more magnetic elements can be arranged (in the radial direction) between the first rotor and the second rotor, the reluctance modulation part of each rotor facing the one or more magnetic elements. The first rotor can be an inner rotor and the second rotor can be an outer rotor, or vice versa. Other configurations can also use the second reluctance modulation component. For example, one or more magnetic elements can be arranged between a (first) linearly extending reluctance modulation component and a second reluctance modulation component, which can also extend linearly, for example, parallel to the first reluctance modulation component. One or more magnetic elements can move relative to the two components, the two components can be stationary, or the two components can move simultaneously relative to the stationary magnetic element; combinations of such configurations are also conceivable.

[0025] In one embodiment, the demagnetization system further comprises a flux enhancement component configured to increase the magnetic flux of the magnet element. The system can be configured to arrange the magnet element on the flux enhancement component (in particular during demagnetization). The flux enhancement component can in particular be configured to reduce the magnetic resistance of the magnetic circuit of the at least one permanent magnet block. Thus, a high magnetic flux density can be provided in the flux enhancement component, which further increases the flux in the at least one permanent magnet block. By increasing this flux, the losses generated by the induced eddy currents in the at least one permanent magnet block can be further increased, thus leading to faster and more efficient heating. In other words, the flux enhancement component can increase the magnetic permeability of the magnetic circuit formed by the at least one permanent magnet block. For example, the flux enhancement component can be configured to have a relatively high magnetic permeability (higher than air). It can have, for example, a magnetic flux density greater than 10 -5 H / m, preferably greater than 10 -4 The relative magnetic permeability may be, for example, at least 10, preferably at least 100. It may in particular be made of a ferromagnetic material.

[0026] For example, the flux enhancement component may include a plate disposed on a side of the magnetic element opposite to the side facing the reluctance modulation component. Thus, the magnetic element may be positioned between the flux enhancement component and the reluctance modulation component. This allows for efficient modulation of the magnetic flux passing through the magnetic element, and thus for efficient induction of eddy currents. The plate may be a ferromagnetic plate, such as a metal plate; it may be made of iron or an iron alloy.

[0027] The magnet element may be composed of a single or multiple permanent magnet blocks; or may include one or more permanent magnet blocks and additional components, such as a housing, an enclosure, an encapsulation, and the like.

[0028] The demagnetization system may further comprise a support configured to support the magnet element at a (predefined) distance relative to the reluctance modulation component during demagnetization. Such a support may, for example, comprise a form-fitting connection (e.g., a T-slot), a clamp, etc., to hold the magnet element in place. Additionally or alternatively, the support may hold the magnet element in place by a magnetic force generated by the magnet element. However, such a magnetic force alone may not be sufficient, as the magnetic force will typically weaken during demagnetization.

[0029] The magnetic element can be supported, in particular, adjacent to the modulation component. The magnetic element can be supported relative to the reluctance modulation component so as to provide a gap (preferably of a predefined size) between the magnetic element and the reluctance modulation component. This gap is preferably small enough to allow eddy currents induced by the reluctance modulation component to heat the magnetic element during relative movement.

[0030] The support element may, for example, include a slot into which the magnet element is slit or pushed; the base plate of the magnet element may, for example, be retained in such a slot in a form-fitting manner. Other possibilities include a fixture, a support plate, or a carriage on a conveyor that transports the magnet element past the modulation component to achieve relative movement. Other configurations are of course conceivable.

[0031] It will be clear that the demagnetization system can be configured to demagnetize one, two, three or more magnetic elements at the same time. The mobile arrangement can provide relative movement between the reluctance modulation component and the plurality of magnetic elements. The support can be configured to support the one, two, three or more magnetic elements relative to the reluctance modulation component. Thus, demagnetization can be made more efficient because it can allow the simultaneous demagnetization of multiple magnetic elements. For example, the component can be moved past a plurality of magnetic elements, which can be distributed circumferentially around the rotor or within the rotor, for example; or the plurality of magnetic elements can be moved past the reluctance modulation component, for example, by a conveyor, by gravity, or the like.

[0032] In one embodiment, the system can be configured to demagnetize the at least one permanent magnet block by heating it to a temperature equal to or greater than the Curie temperature of the at least one permanent magnet block via eddy currents. Demagnetization can typically be performed by heating the at least one permanent magnet block to a temperature greater than the Curie temperature at which demagnetization occurs. This heating can achieve efficient demagnetization.

[0033] In one embodiment, the demagnetization system further comprises a transport system configured to receive the magnet element and automatically transport the magnet element to a mobile arrangement and / or transport the demagnetized magnet element (from the mobile arrangement) to a collection stage or another processing stage. The transport system may, for example, comprise a conveyor, such as a belt, chain or slat conveyor. The other processing stage may, for example, be a separation stage, at which the magnet element is separated into two or more components. For example, the magnet element may be a magnet module, which comprises at least one permanent magnet block and further comprises a cover, a shroud, an encapsulation or the like. Preferably, it comprises a base plate and a cover attached to the base plate, with the at least one permanent magnet block being arranged between the cover and the base plate.

[0034] The transport system can also be configured to automatically position the magnet element on a support that supports the magnet element relative to the reluctance modulation component. The transport system itself can include the support, or it can, for example, include an actuator that moves the magnet element onto the support. Such an actuator can, for example, be a hydraulic or pneumatic cylinder that pushes or pulls the magnet element onto the support, for example, pushing the magnet element into a slot in which the magnet element is held in a form-fitting manner. In other embodiments, such an actuator can, for example, include a clamp, a gripper, or the like that holds the magnet element in place during demagnetization.

[0035] According to another embodiment, the demagnetization system includes a controller configured to control the relative movement. The controller can be configured to control the generation of eddy currents by the relative movement so as to heat at least one permanent magnet block until the Curie temperature is reached. The controller can, for example, adjust the duration and / or speed of the relative movement, the frequency of the change in magnetic resistance, etc. It can, for example, control the duration and rotation speed of the operation of the motor driving the above-mentioned rotor. The controller can also be configured to control the transport system. Such a controller can be a separate controller or can form part of a larger controller that can, for example, control a recycling system for recycling the magnet elements.

[0036] According to another embodiment of the present invention, a method for demagnetizing a magnetic element of a wind turbine generator component is provided. The magnetic element includes at least one permanent magnet segment. The method includes generating eddy currents in the at least one permanent magnet segment by providing relative movement between a reluctance modulation component and the magnetic element, wherein the reluctance modulation component changes the reluctance experienced by a magnetic flux of one or more permanent magnet segments as the reluctance modulation component moves past the magnetic element. The method also includes heating the at least one permanent magnet segment via the eddy currents to demagnetize the magnetic element. Advantages similar to those outlined further above can be achieved by this method.

[0037] The method may further comprise any of the steps described herein with respect to the demagnetization system.Furthermore, the demagnetization system, in particular its controller, may be configured to implement any of the methods described herein.

[0038] It will be appreciated that the features mentioned above and those to be explained below may be used not only in the respective combinations indicated, but also in other combinations or alone, without departing from the scope of the present invention. In particular, unless otherwise indicated to the contrary, the features of the different aspects and embodiments of the present invention may be combined with one another. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The foregoing and other features and advantages of the present invention will become more apparent from the following detailed description read in conjunction with the accompanying drawings, in which like reference numerals refer to like elements.

[0040] Figure 1 is a schematic diagram illustrating a demagnetization system according to an embodiment.

[0041] Figure 2 is a schematic diagram illustrating a demagnetization system according to another embodiment.

[0042] Figure 3 is a schematic diagram illustrating a demagnetization system according to an embodiment. Figure 1 system modification.

[0043] Figure 4 is a schematic diagram illustrating a demagnetization system according to another embodiment.

[0044] Figure 5 is a schematic diagram illustrating a magnetic element according to an embodiment.

[0045] Figure 6 It is an icon Figure 1 Schematic diagram of the losses caused by induced eddy currents in the magnetic components of the demagnetization system.

[0046] Figure 7 The demagnetization period is shown in the figure Figure 1 Schematic diagram of the torque on the rotor of the demagnetization system.

[0047] Figure 8 is a flow chart illustrating a method of demagnetizing a magnet element according to an embodiment. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the embodiments is provided for illustrative purposes only and should not be considered as having a limiting meaning. It should be noted that the accompanying drawings are only to be considered as schematic representations, and the elements in the accompanying drawings are not necessarily drawn to scale with each other. On the contrary, the representations of the various elements are selected so that their functions and general use become apparent to those skilled in the art. As used herein, the singular forms "a", "an" and "the" are also intended to include plural forms, unless the context clearly indicates otherwise. The terms "include", "have", "include" and "comprising" will be interpreted as open terms (i.e., meaning "including, but not limited to"), unless otherwise noted.

[0049] Figure 1 The demagnetization system 100 is schematically illustrated and includes a magnetoresistive modulation component 20 and a movement arrangement that provides relative movement between the magnet element 10 and the magnetoresistive modulation component 20. Figure 1 In the example of FIG. 1 , the component 20 is formed as a rotor 25 and the moving arrangement comprises an actuator ( Figure 1 ). The rotor 25 has an outer circumferential surface facing the magnet element 10. Along the direction of relative movement as indicated by the arrow, the component 20 has an extension along which the magnetic resistance changes, in particular changes periodically. This is achieved by providing segments 21 with high magnetic permeability and segments 22 with low magnetic permeability, wherein the segments 21 and 22 are arranged alternately. As a result, the magnetic resistance changes significantly between adjacent segments. When the rotor 25 rotates, these segments that delay the magnetic resistance move past the magnet element 10. As a result, the magnetic flux of one or more permanent magnet blocks of the magnet element 10 experiences a changing magnetic resistance (or, correspondingly, a changing magnetic permeance). Eddy currents are induced in the permanent magnet blocks by the changing magnetic permeance or magnetic resistance to which the magnetic flux of the magnet element 10 is subjected. As a result, eddy currents are induced in the permanent magnet material itself, thereby generating heat. By providing a relative movement at a corresponding speed and for a corresponding duration, the magnet element 10 , in particular one or more permanent magnet blocks thereof, can be heated up to the Curie temperature to thereby demagnetize the one or more permanent magnet blocks.

[0050] exist Figure 1In the example of FIG, the segments 21 with high magnetic permeability are provided by the poles of the rotor 25, while the segments 22 with low magnetic permeability are provided by the slots or spaces between the poles. The segments 21, 22 are each spaced sufficiently wide so as to cause the flux of the magnet element 10 to experience a significant change in magnetic resistance when the segments 21, 22 move past the magnet element 10. The width of the segment 22 (e.g., the slot) in the circumferential direction can be at least half the width of the segment 21 (e.g., the pole). The width of the segment 22 (at the outer circumferential surface) in the circumferential direction can be, for example, between 50% and 150% of the width of the segment 21 in the circumferential direction. It should be clear that the frequency with which the segments 21, 22 pass through the magnet element 10 can be adjusted by adjusting the number of segments 21, 22 present on the outer circumferential surface, by adjusting the diameter of the rotor 25, and by adjusting the rotational speed of the rotor 25. A relatively high frequency can be selected to achieve efficient heating. For example, the rotor may be caused to rotate at more than 3,000 rpm, for example at about 6,000 rpm, and may include a large number of poles, such as 20 poles, 30 poles, 40 poles or more.

[0051] It should be clear that Figure 1 Only an exemplary geometric configuration of the component 20 is shown, and a variety of different configurations are conceivable. For example, the segments 21, 22 can be arranged on the inner circumferential surface of the rotor 25, and the magnet elements 10 can be arranged inside the rotor 25. In addition, instead of a rotor, the component 20 can extend linearly, as described below with reference to Figure 4 Furthermore, the magnet element 10 can be moved instead of the component 20. Furthermore, a plurality of magnet elements 10 can be provided and distributed around the rotor 25, for example.

[0052] Thus, the demagnetization system 100, and in particular the component 20, can be similar to a rotating electrical machine, such as a reluctance motor. In a reluctance motor, a magnetic field is generated by windings around the stator poles, and the rotor is aligned with the magnetic field to reduce magnetic resistance. Figure 1 The demagnetization system of the invention rotates the rotor instead and thereby induces currents in the "stator", i.e. in one or more magnet elements 10. As a result, efficient generation of eddy currents in the magnet elements 10 can be achieved, making rapid heating of the permanent magnet material possible, regardless of the configuration of the magnet elements 10.

[0053] In order to increase the flux through the magnet element 10, a flux enhancing component 30 is provided. It is arranged on the side of the magnet element 10 opposite to the side on which the component 20 is arranged, as shown in FIG. Figure 1As shown in . The flux enhancement component 30 can have a high magnetic permeability and can be provided in the form of a backing plate on which the magnet elements 10 are arranged. The flux enhancement component 30 can be made, for example, of a ferromagnetic material; it can be made of iron, an iron alloy, or another iron-based composition. This can in particular allow one or more permanent magnet blocks to have a higher permeability coefficient (PC) point. By increasing the flux, the losses induced in the one or more permanent magnet blocks are also increased. As a result, heating can be accelerated.

[0054] In the finite element simulation, the Figure 1 The heating of the magnet element 10 is determined by the configuration of the demagnetization system illustrated in FIG. Figure 6 The figure shows the loss P in the magnetic element 10 when the speed of the rotor 25 is 6000 rpm. L . Figure 7 The torque τ experienced by the rotor 25 over time t is shown. As can be seen in the figure, significant losses are induced in the magnet element 10, which remain relatively constant over time in the simulation (the loss power is greater than 500 watts on average). Since this power is deposited directly in the magnet element 10 as heat, the magnet element 10 heats up quickly and reaches the Curie temperature for demagnetization in a relatively short amount of time. The actuator driving the rotor 25 should be able to provide sufficient torque to account for both the losses and the braking torque generated by the entire system. The simulation takes into account the conductivity in the rotor and therefore takes into account the eddy currents (specifically the reaction field of the eddy currents) generated in the rotor 25. In order to reduce the amount of heat generated in the rotor 25, the rotor 25 can be provided as a laminated rotor that reduces such circulating currents. The simulation does not take into account the demagnetization of the magnet element 10 as the temperature increases. Therefore, to provide uniform heating, the rotational speed of the rotor 25 can be increased during the demagnetization process to compensate for the reduction in magnetic flux density.

[0055] In addition, the demagnetization system 100 may include an additional heater to heat the magnet element 10, such as an induction heater, a thermal heater, etc. Therefore, the heating of the magnet element 10 can be further accelerated, and this configuration can allow fine-tuning of different heating methods to provide efficient demagnetization, especially demagnetization that reduces energy consumption and time and provides high demagnetization quality.

[0056] Figure 2 Graphic Figure 1 The above explanations are also applicable to the specific implementation of the demagnetization system 100. Figure 2The moving arrangement 70 of the system 100 includes a motor 26 and corresponding components (such as a shaft between the motor 26 and the rotor 25), which provide relative movement between the component 20 and the magnet element 10. The reluctance modulation component 20 is driven by the motor 26, such as an electric motor. This can occur under the control of a controller 50. The controller 50 can control the speed and time of rotation of the rotor 25 so as to achieve a desired demagnetization temperature, in particular the Curie temperature, of the magnet element 10. The system 100 can also include a support 40 that supports the magnet element 10 during demagnetization. The support 40 can be pre-configured or can be adjustable so as to provide a gap between the magnet element 10 and the outer circumferential surface of the rotor 25, the gap being sized to ensure efficient generation of eddy currents within the magnet element 10.

[0057] Figure 5 A specific example of a magnet element 10 is shown. It includes one or more permanent magnet blocks 15, such as one, two, three, or more, for example, one to ten. The magnet element 10 also includes a housing, a casing, or an enclosure that encloses the one or more permanent magnet blocks 15. In this example, the one or more permanent magnet blocks 15 are mounted on a base plate 11 (e.g., steel) by means of an adhesive 12 and are covered by a cover 17 (e.g., sheet metal). Thus, the permanent magnet blocks 15 can be protected from environmental influences, which is particularly advantageous in an offshore environment.

[0058] The support 40 can be configured to hold the magnet element 10 in place. For this purpose, it can, for example, include a T-slot into which the magnet element 10 can be inserted in a form-fitting manner. The base plate 11 can, for example, be held in place within such a T-slot. In other configurations, other types of form-fitting mountings, clamps, grippers, etc. can be used to hold the magnet element 10 in place. The support 40 can include one or a combination of such configurations.

[0059] The demagnetization system 100 also includes a transport system 60 that transports the magnet elements 10 to the support 40 and, after demagnetization, transports the magnet elements 10 away from the support 40 to different processing stages or collection systems. The transport system 60 may include a first conveyor 61 that may, for example, receive the magnet elements 10 from an extraction system that extracts the magnet elements 10 from a component of a wind turbine rotor, such as from a generator rotor. The transport system 60 may also include an actuator that places the magnet elements 10 on or in the support 40. This may occur via the conveyor 61 itself, or may include additional active devices, such as hydraulic, pneumatic, or electrically driven cylinders, that may push the magnet elements 10 onto or into the support 40. The same or different actuators may further push the magnet elements out of the support 40 after demagnetization. The transport system 60 may include a second conveyor 62 onto which the magnet element is pushed, and the second conveyor 62 transports the magnet element to the next processing stage, such as a separation stage, where one or more permanent magnet blocks 15 are separated from the housing. It should be clear that other types of actuators or active devices may be provided to position the magnet element 10 on the support 40, such as a robotic arm, etc.

[0060] The controller 50 may include a processing unit 51 and a memory 52, wherein the memory 52 stores control instructions executed by the processing unit 51. The controller 50 may also control the transport system 60 and the corresponding conveyors and / or actuators included therein. Thus, the controller 50 can provide an automatic demagnetization operation by controlling the demagnetization system 100. In particular, demagnetization of the magnetic element 10 may be performed without operator intervention. The processing unit 51 may include a microprocessor, a digital signal processor, an application-specific integrated circuit, etc. The memory 52 may include RAM, ROM, or other types of volatile and non-volatile memory.

[0061] Figure 3 Graphic Figure 1 or Figure 2 The rotor 25 still includes magnetic poles and slots therebetween to provide modulation of the magnetic resistance when rotating relative to the magnetic elements. Figure 3 In the example of , a plurality of magnet elements 10 are distributed circumferentially around the rotor 25. A flux enhancing component 30 is provided for each magnet element 10. The flux enhancing component 30 may be mounted to a support 40 or may be integrated with the support 40. It may, for example, provide a T-slot into which the magnet element 10 is inserted. Preferably, the portion of the support 40 connecting the different flux enhancing components 30 is made of a material having a relatively low thermal conductivity. In this way, it is ensured that the heat capacity of the support 40 remains low and that the heat generated in the magnet element 10 is not conducted away. More efficient heating can thereby be achieved. A plurality of conveyors 61, 62 may be provided to Figure 3 . Alternatively, the support 40 can be rotated to a position where the magnet elements can be loaded by the conveyor 61 and can remain stationary during the demagnetization process. It should be clear that this is merely an exemplary embodiment and that a different number of magnet elements can be distributed around the circumferential direction. Similarly, different types of mounting members 40 can be provided, and no flux enhancement member 30 or a flux enhancement member 30 of a different shape can be provided.

[0062] It becomes obvious that by Figure 3 With the arrangement shown in , multiple magnet elements 10 can be demagnetized simultaneously by the rotation of the rotor 25. Thus, fast and energy-efficient demagnetization of multiple magnet elements becomes possible. It should be clear that the torque required to rotate the rotor 25 will generally increase with the number of magnet elements 10 distributed around the rotor 25.

[0063] In other embodiments, a second reluctance modulation component (not shown) may be arranged on the other side of the magnet element 10. For example, the outer rotor may additionally be provided with a reluctance modulation component facing the magnet element, for example in the form of a corresponding magnetic pole of the rotor corresponding to the magnetic pole of the section 21 of the rotor 25. The rotor can then likewise rotate to generate additional eddy currents inside the magnet element 10. In this configuration, the flux enhancement component 30 may not be provided. The direction of rotation is preferably such that the eddy currents induced by the two reluctance modulation components add to maximize the losses.

[0064] Figure 4 Another possible implementation is shown. Figures 1 to 3 The demagnetization system is different. Figure 4 In the example of , the reluctance modulation component 20 is stationary. Instead, the magnet element 10 is arranged on a transport system 60, in particular a conveyor 61, which transports the magnet element 10 through the component 20 to provide relative movement. Therefore, the moving arrangement may include a conveyor 61. Similarly, the component 20 includes a section 21 with high magnetic permeability and a section 22 with low magnetic permeability. When the magnet element 10 moves along the sections 21, 22, the reluctance of the magnetic circuit changes, thereby changing the flux in the magnet element 10, resulting in eddy currents being induced in the same manner as further described above. The component 20 can have a sufficient length and a sufficient number of poles or teeth 21 so that when moving along the component 20, the magnet element 10 is heated to the Curie temperature for demagnetization. For this purpose, the component 20 can also provide a closed path (e.g., an oval or a circle) along which the magnet element 10 moves continuously until the desired demagnetization temperature is reached. Likewise, the flux enhancement member 30 may be provided, for example, on a conveyor 61 to which the magnet elements 10 are mounted. Figures 1 to 3 The explanations provided apply accordingly to Figure 4 Example of .

[0065] Likewise, in Figure 4 In the embodiment of the present invention, a second magnetoresistive modulation component may be added. Such a second magnetoresistive modulation component may have Figure 4 The structure of the magnetic reluctance modulation component 20 is similar to or identical to that of the magnetic element 10. It can be arranged on the other side of the magnetic element 10, so that the magnetic element 10 is arranged between the magnetic reluctance modulation component 20 and a second magnetic reluctance modulation component (not shown). Therefore, when the magnetic element 10 moves, it moves relative to the two magnetic reluctance modulation components, so that high eddy currents and therefore higher losses can be generated in the magnetic element. Similarly, in this configuration, the flux enhancement component 30 may not be present.

[0066] Figure 8 FIG. 1 is a flow chart schematically illustrating a method for demagnetizing a magnetic element according to an embodiment. In step S1 , a magnetic element is received at a demagnetization system, for example, Figure 2 At the conveyor 61 of the magnet element 10, or directly at the support 40. In optional step S2, the magnet element is positioned on the support 40 relative to the reluctance modulation component 20. As described above, this relative positioning can ensure the desired distance between the magnet element 10 and the component 20, which leads to efficient induction of eddy currents. In step S3, relative movement is provided between the magnet element 10 and the reluctance modulation component 20. This can be achieved by rotating Figures 1 to 3 The rotor 25 in the embodiment of the present invention is operated by Figure 4 or by any other conceivable means. In step S4, by the relative movement, the magnetic resistance experienced by the magnet element 10 is continuously changed, thereby changing the flux through the magnet element 10 and inducing eddy currents. With the help of these eddy currents, the magnet element is heated in step S5. The heating continues until the magnet element reaches the desired degree of demagnetization, in particular until the temperature of at least one permanent magnet block 15 reaches or exceeds the Curie temperature. This can take place under the control of the controller 50. After demagnetization, in an optional step S6, the demagnetized element can be transferred to a collection system or a separation system. This can be done, for example, by Figure 2 Conveyor 62 or directly through Figure 4 It will be clear that the method may include the methods disclosed herein, in particular with reference to Figures 1 to 7 Any other steps disclosed.

[0067] Although specific embodiments are disclosed herein, various changes and modifications may be made without departing from the scope of the invention. The present embodiments are to be considered in all respects as illustrative and non-restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims

1. A demagnetization system for demagnetizing a magnetic element (10) of a wind turbine generator component, wherein: The magnetic element (10) comprises at least one permanent magnet block (15), wherein the demagnetization system (100) comprises: - a magnetoresistive modulation component (20); and a movement arrangement (70) configured to provide relative movement between the reluctance modulation component (20) and the magnet element (10), wherein the reluctance modulation component (20) is configured to vary the reluctance experienced by the magnetic flux of the one or more permanent magnet segments (15) when the reluctance modulation component (20) moves past the magnet element (10), The system is configured to generate eddy currents in the at least one permanent magnet block (15) by providing the relative movement between the reluctance modulation component (20) and the magnet element (10), wherein the eddy currents heat the at least one permanent magnet block (15).

2. The demagnetization system according to claim 1, wherein: The magnetoresistive modulation element (20) has a spatial extension in the direction of relative movement, and wherein the magnetoresistive modulation element (20) changes its magnetic resistance along the spatial extension.

3. The demagnetization system according to claim 2, wherein: The magnetic permeability of the magnetoresistive modulation component (20) varies, preferably periodically, along the spatial extension of the magnetoresistive modulation component (20).

4. A demagnetization system according to any one of the preceding claims, wherein: The magnetic resistance modulation component (20) includes different sections (21, 22) in the direction of relative movement, the sections (21, 22) facing the magnetic element (10), wherein adjacent sections (21, 22) have different magnetic resistances to provide the change in magnetic resistance.

5. A demagnetization system according to any one of the preceding claims, wherein: The magnetic resistance modulation component (20) is a circular component having a circumferential surface facing the magnetic element (10), wherein the relative movement includes relative rotational movement between the circular component and the magnetic element (10).

6. The demagnetization system according to claim 5, wherein: The circular component is a rotor (25), wherein the moving arrangement (70) is configured to rotate the rotor (25) relative to the magnet element (10).

7. The demagnetization system according to claim 6, wherein: The rotor (25) has a plurality of magnetic poles, wherein the magnetic poles cause the change in magnetic resistance when the magnetic poles rotate past the magnetic element (10).

8. The demagnetization system according to any one of the preceding claims, further comprising at least one second reluctance modulation component, wherein The magnetic element (10) is arranged between the reluctance modulation component (20) and the second reluctance modulation component, and wherein the movement arrangement is configured to provide relative movement between the second reluctance modulation component (20) and the magnetic element (10), wherein the second reluctance modulation component (20) is configured to change the reluctance experienced by the magnetic flux of the one or more permanent magnet blocks (15) when the second reluctance modulation component (20) moves past the magnetic element (10).

9. The demagnetization system according to any one of the preceding claims, further comprising a flux enhancement component (30) configured to increase the magnetic flux of the magnet element (10), wherein The system is configured to arrange the magnet element (10) on the flux enhancing component (30).

10. The demagnetization system according to claim 9, wherein: The demagnetization system is configured to support the magnet element (10) between the flux enhancing component (30) and the magnetoresistive modulation component (20), wherein the flux enhancing component (30) preferably comprises a plate.

11. The demagnetization system according to any of the preceding claims, further comprising a support (40) configured to support the magnetic element (10) at a distance relative to the reluctance modulation component (20) during demagnetization.

12. A demagnetization system according to any one of the preceding claims, wherein: The demagnetization system (100) is configured to heat the at least one permanent magnet block (15) to a temperature equal to or higher than the Curie temperature of the at least one permanent magnet block (15) by the eddy current to demagnetize the at least one permanent magnet block (15).

13. A demagnetization system according to any of the preceding claims, further comprising a transport system (60) configured to receive the magnet element (10) and automatically transport the magnet element (10) to the mobile arrangement (70) and / or transport the demagnetized magnet element (10) to a collection stage or another processing stage.

14. The demagnetization system according to any of the preceding claims, further comprising a transport system (60) configured to automatically position the magnetic element (10) on a support (40) supporting the magnetic element (10) relative to the magnetoresistive modulation component (20).

15. A method of demagnetizing a magnetic element of a wind turbine generator component, wherein: The magnet element (10) comprises at least one permanent magnet block (15), wherein the method comprises: - generating eddy currents in the at least one permanent magnet segment (15) by providing relative movement between a reluctance modulation component (20) and the magnet element (10), wherein the reluctance modulation component (20) changes the reluctance experienced by the magnetic flux of the one or more permanent magnet segments (15) as the reluctance modulation component (20) moves past the magnet element (10); and - heating the at least one permanent magnet segment (15) by means of the eddy currents in order to demagnetize the magnet element (10).

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