Magnetic steel thermal demagnetization system for outer rotor of permanent magnet direct drive wind power motor

Abstract

The invention discloses a magnetic steel thermal demagnetization system for an outer rotor of a permanent magnet direct drive wind power motor, and belongs to the technical field of wind power generator assembly. Comprising a control device, a surface magnetic detection device, a demagnetization coil device, a temperature measuring device, a demagnetization current generating device and an execution device. The demagnetizing coil device is used for heating and demagnetizing the rotor magnetic pole; the execution equipment is used for driving the demagnetizing coil device to complete the demagnetizing operation of the whole rotor; the demagnetization current generating device is used for generating magnetic current according to a control instruction of the control equipment; the surface magnetic detection device and the temperature measurement device are respectively used for detecting the magnetic field intensity and temperature data of the rotor magnetic pole surface in the demagnetization process; the control equipment receives the feedback signal, processes the feedback signal and then sends out a corresponding control instruction, and demagnetization parameters in the demagnetization process are regulated and controlled in real time. According to the invention, automatic demagnetization of the outer rotor of the permanent magnet direct-driven wind power motor can be realized, parameter adjustment and demagnetization detection are carried out in the demagnetization process, and the demagnetization efficiency and safety are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine assembly, and in particular to a permanent magnet direct-drive wind turbine outer rotor magnetic steel thermal demagnetization system. Background Art

[0002] Existing permanent magnet direct-drive wind turbines mostly use an outer rotor and inner stator structure. The rotor is assembled by fixing permanent magnets to the inner wall of the outer rotor frame to form rows of magnetic poles. When this structure requires rotor repair or recycling, the strong magnetism of the permanent magnets makes removal extremely difficult and cumbersome without demagnetization. This requires the design and use of specialized tooling, and there are safety risks associated with handling the magnets.

[0003] Existing methods for demagnetizing the outer rotor magnets of permanent magnet wind turbine motors typically exploit their temperature sensitivity by heating the magnets to above 310°C using an oxyacetylene flame or oven, causing them to lose their magnetism or even completely lose it, allowing them to be removed without losing their magnetism. However, due to the large number of poles and size of the outer rotor of a permanent magnet direct-drive motor, heating all the magnets on the rotor takes a long time, consumes a lot of energy, and causes significant environmental pollution.

[0004] In the prior art, a foreign patent with publication number JP2023084977A and publication date June 20, 2023, discloses a permanent magnet demagnetization method for a rotating motor, a permanent magnet demagnetization system for a rotating motor, and a rotor extraction method. The demagnetization method demagnetizes the motor rotor by induction heating by passing a high-frequency alternating current through the winding of the original motor. At the same time, the demagnetization can be further supplemented by using the winding to generate a reverse magnetic field of the rotor poles. That is, the rotor can be demagnetized without using professional equipment or removing the stator, and the rotor can be disassembled after demagnetization. This method has a good application effect on small motors with inner rotors, but it is not applicable to direct-drive wind turbines for the following reasons: 1) When high-frequency AC is applied to the original motor windings, the coils generate a lot of heat. Direct-drive air-cooled motors have difficulty dissipating heat when not in normal operation. The coils may heat up before demagnetization requirements are met, damaging the insulation material and even causing the coils to burn out. 2) If AC is passed through the original windings of the motor, induced eddy currents will also be generated in the rotor frame. These eddy currents will generate additional electromagnetic forces on the rotor frame structure, which may cause the frame to deform. In the worst case, eddy currents will be generated in the shaft system, burning key parts such as bearings. 3) When alternating current is passed through the generator winding, the rotor poles may tend to move relative to each other due to the magnetic field generated by the alternating current in the winding, and additional braking devices are required to limit it.

[0005] It can be seen from this that for direct-drive wind turbines, if the outer rotor is to be demagnetized by induction heating, it is not appropriate to directly use the method of passing high-frequency alternating current through the original stator winding of the motor for demagnetization. It is necessary to improve the demagnetization system based on the induction heating technology route. Summary of the Invention

[0006] The present invention aims to solve the shortcomings of the existing methods for demagnetizing the outer rotor magnets of permanent magnet wind turbines, and proposes a thermal demagnetization system for the outer rotor magnets of permanent magnet direct-drive wind turbines. The demagnetization system uses an independent induction heating coil close to the magnetic poles to generate an alternating magnetic field, which induces eddy currents in the permanent magnets to heat up to above the Curie point to achieve demagnetization, and can realize automatic parameter adjustment and demagnetization detection during the demagnetization process.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows: A permanent magnet direct drive wind turbine motor outer rotor magnetic steel thermal demagnetization system, comprising: A demagnetization coil device, which is opposite to the surface of the rotor pole to be demagnetized and is used to generate a uniform alternating magnetic field to induce eddy currents in the permanent magnets to heat up to above the Curie point for demagnetization; a demagnetization current generating device, connected to the demagnetization coil device, for generating a demagnetization current matching the thickness of the magnetic steel according to a control instruction of the control device and inputting the demagnetization current into the demagnetization coil device; An execution device, connected to the demagnetization coil device, used to adjust the position of the demagnetization coil device and drive the demagnetization operation of the entire rotor; The surface magnetic detection device is arranged at the front end of the demagnetization coil device, and is used to synchronously collect the surface magnetic data of the magnetic pole surface during the demagnetization process and feed it back to the control device; The temperature measuring device is arranged on the front face of the demagnetization coil device, and is used to synchronously collect temperature data of the magnetic pole surface during the demagnetization process and feed it back to the control device; The control device is connected to the signals of various devices and equipment, receives real-time detection data from the surface magnetic detection device and the temperature measuring device, and outputs control instructions to the demagnetization current generating device and the execution device to regulate the heating temperature and heating time during the demagnetization process.

[0008] Preferably, in a certain embodiment, the demagnetization coil device comprises a plurality of induction coils, which are arranged in an array to form an array coil whose overall length covers the length of a single magnetic pole and whose overall width at least covers the width of a single magnetic pole.

[0009] Preferably, in a certain embodiment, the structures of the induction coils are the same, and the distances between adjacent induction coils are the same.

[0010] Preferably, in a certain embodiment, the shape of each induction coil is square, and the single side size of the induction coil is 20-30 cm.

[0011] Preferably, in a certain embodiment, the demagnetization coil device further includes an insulating fixing plate and a cover plate covering the surface of the insulating fixing plate, the insulating fixing plate is provided with a cavity matching the coil shape, the coil is embedded in the corresponding cavity and fixed by the cover plate.

[0012] Preferably, in a certain embodiment, a small hole is reserved on the surface of the cover plate corresponding to the center position of each induction coil, and an infrared temperature measuring probe is arranged in the hole to form an infrared temperature measuring probe array.

[0013] Preferably, in a certain embodiment, the execution device includes a main body and a moving device connected thereto for driving the demagnetization coil device as a whole to move along the circumference of the direct-drive rotor base, and a telescopic device for adjusting the distance between the demagnetization coil device and the magnetic pole.

[0014] Preferably, in a certain embodiment, the moving device includes a servo motor and a walking assembly driven by the servo motor, the walking assembly includes a support wheel and a guide wheel, the support wheel rolls along the end face of the direct-drive rotor base under the drive of the servo motor, and the guide wheels are provided with two and are respectively close to the two side faces of the end face of the direct-drive rotor base.

[0015] Preferably, in a certain embodiment, the telescopic front end of the telescopic device is connected to a coil fixing cantilever, and a slide motor is provided on the coil fixing cantilever; the demagnetization coil device is installed on a slider of the slide motor, and the slide motor automatically adjusts the position of the demagnetization coil device to align with the upper and lower positions of the magnetic pole according to the detection data of the surface magnetism detection device.

[0016] In summary, the present invention has the following advantages: 1. The thermal demagnetization system proposed in this invention uses an independent induction heating demagnetization coil device close to the magnetic pole to generate an alternating magnetic field, which triggers eddy currents in the permanent magnets to heat up to above the Curie point to achieve demagnetization. It can also detect the surface magnetism and temperature data of the magnetic steel in real time during the demagnetization process, match and control the heating depth, temperature and heating time of different rotors, realize automatic parameter adjustment and demagnetization detection, and reduce human intervention. 2. The thermal demagnetization system proposed in this invention is a highly automated system that takes into account the regulation of heating depth, temperature control, heating duration, heating uniformity, etc. Through precise measurement and control, it can achieve efficient demagnetization of the outer rotor structure of permanent magnet direct-drive wind turbines, while ensuring the efficiency and safety of the demagnetization process. 3. In the thermal demagnetization system proposed by the present invention, the independent induction heating coil is an array coil covering one or more magnetic poles. By adjusting and designing the structural parameters of the array coil, the problem of magnetic field interference between adjacent coils is solved, and the surface-mounted magnetic poles of the outer rotor of the direct-drive wind turbine can be uniformly heated. 4. The thermal demagnetization system proposed in the present invention uses a temperature measuring device to monitor the surface temperature of the magnetic steel in real time and feeds the data back to the control device. The heating process can be precisely controlled through PID technology to prevent local overheating that may cause damage to the magnetic steel surface or local damage to the rotor structure. 5. The thermal demagnetization system proposed by the present invention uses a surface magnetic detection device to monitor the surface magnetic data of the magnetic steel in real time, which can reflect the current demagnetization state of the magnetic pole in real time and assist the automatic operation of the demagnetization work; 6. In the thermal demagnetization system proposed by the present invention, the relative position of the demagnetization coil device and the rotor can be adjusted by the execution device to achieve the best demagnetization effect, which facilitates the completion of the automatic demagnetization operation of the entire rotor; 7. In the thermal demagnetization system proposed in the present invention, the execution equipment has good versatility for different types of rotors. The moving device adopts guide wheels with adjustable spacing, which can adapt to rotor bases with different wall thicknesses; the sliding rail motor is connected to the telescopic device to adjust the position of the demagnetization coil device along the axial direction of the rotor, which can adapt to different magnetic pole positions of different rotors. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the composition and signal flow of the thermal demagnetization system of the present invention; Figure 2 Schematic diagram of the structure of the coil array of the present invention; Figure 3 Schematic diagram of the first arrangement of the array coils in Example 1; Figure 4 Schematic diagram of the second arrangement of the array coils in Example 1; Figure 5 is a structural diagram of the fixed plate; Figure 6 This is a schematic diagram of the installation of the induction coil; Figure 7 A structural diagram of an execution device; Figure 8 Another structural diagram of the execution device; In the picture: 1. Control device, 2. Demagnetization current generating device, 3. Demagnetization coil device, 4. Execution device, 5. Surface magnetic detection device, 6. Temperature measuring device, 401. Main body, 402. Telescopic device, 403. Support wheel, 404. Hub motor, 405. Guide wheel, 406. Coil fixing cantilever, 407. Slide motor, 7. Rotor, 8. Main body, 9. Rotating shaft, 10. Cantilever, 11. Array coil, 12. Fixing plate, 13. Cover plate, 14. Cavity. DETAILED DESCRIPTION

[0018] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and drawings. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0019] Example 1 The present invention provides a permanent magnet direct drive wind turbine motor outer rotor 7 magnetic steel thermal demagnetization system, such as Figure 1 As shown, it includes a control device 1 and a demagnetization coil device 3, a surface magnetic detection device 5, a temperature measuring device 6, a demagnetization current generating device 2 and an execution device 4 connected thereto. The control device 1 serves as the control center of the entire system, receives signals from the execution device 4, the surface magnetic detection device 5, the temperature measuring device 6, and the demagnetization current generating device 2, processes the signals, and issues corresponding control instructions.

[0020] In this solution, the demagnetization coil device 3 is an independent induction heating coil, which is used to generate a uniform alternating magnetic field near the magnetic poles, causing the eddy current of the permanent magnet to heat up to above the Curie point to achieve demagnetization. The execution device 4 is connected to the demagnetization coil device 3 and is used to drive the demagnetization coil device 3 to complete the demagnetization operation of the entire rotor 7 according to the control instructions of the control device 1. The demagnetization current generating device 2 is connected to the demagnetization coil device 3 and is used to generate the corresponding demagnetization current according to the control instructions of the control device 1. The surface magnetic detection device 5 and the temperature measuring device 6 are respectively used to detect the magnetic field strength and temperature data of the rotor 7 magnetic pole surface in real time during the demagnetization process, and feed them back to the control device 1.

[0021] In this solution, the control device 1 automatically selects the appropriate heating frequency based on the thickness of the magnet to improve demagnetization efficiency. In induction heating, the frequency of the AC current is correlated with the depth of heating. Lower frequencies result in deeper heating depths, making it suitable for thorough heating of large workpieces. Higher frequencies result in shallower heating depths, making it suitable for surface heating of smaller workpieces. Surface-mount magnets of varying thicknesses require different frequencies to achieve the optimal heating depth.

[0022] Preferably, in this solution, the demagnetization coil device 3 is arranged at the front end of the execution device 4, opposite to the magnetic pole surface of the rotor 7 to be demagnetized. The demagnetization coil device 3 is controlled by the execution device 4 to move along the circumferential direction of the rotor 7, so as to realize demagnetization of each part of the magnetic pole one by one. The surface magnetic detection device 5 and the temperature measuring device 6 are arranged on the front end surface of the demagnetization coil device 3, and the surface magnetic data and temperature data of the magnetic pole surface are synchronously collected during the demagnetization process, and fed back to the control device 1. The control device 1 adjusts the heating temperature, heating time and other parameters in the demagnetization process in real time according to the fed-back surface magnetic data and temperature data, such as controlling the heating temperature by controlling the current amplitude of the demagnetization current generating device 2, and controlling the heating time by controlling the action of the execution device 4.

[0023] The present invention generates an alternating magnetic field by placing an independent induction-heated demagnetization coil device 3 close to the magnetic pole, thereby inducing eddy currents in the permanent magnet to heat up to above the Curie point to achieve demagnetization. The present invention also detects the surface magnetism and temperature data of the magnet during demagnetization in real time, matches and controls parameters such as the heating depth, heating temperature, and heating time, and can achieve automated parameter adjustment and demagnetization detection, reducing human intervention. While improving the demagnetization efficiency, it achieves precise control of the heating process, preventing damage to the magnet surface or local structural damage to the rotor 7 caused by excessive local temperature.

[0024] The working principle of the above demagnetization system is as follows: Before demagnetization, the rotor 7 is first positioned. Information about the magnetic pole shape, including magnet thickness, magnet placement, and number of poles, is input into the thermal demagnetization system and fed back to the control device 1. The control device 1 automatically matches the appropriate heating frequency based on the magnet thickness and inputs it into the demagnetization current generator 2, causing the demagnetization coil device 3 to generate an alternating magnetic field, inducing eddy currents in the permanent magnets to heat up to above the Curie point for demagnetization. During demagnetization, the actuator 4 drives the demagnetization coil device 3 close to the magnetic poles of the rotor 7. The demagnetization current generating device 2 converts the current input from the power grid into a demagnetization current and inputs it into the demagnetization coil device 3 to increase the temperature of the magnetic poles of the rotor 7. During the demagnetization process, the surface magnetism detection device 5 and the temperature measuring device 6 are used to detect the surface magnetism and temperature data in real time and feed them back to the control device 1. When it is recognized that the surface magnetism has changed and does not change subsequently, it is considered that the magnetic pole has been demagnetized, heating is stopped and the heating temperature is recorded. The control device 1 then uses high-power induction heating to quickly heat the remaining magnetic poles according to the temperature, and PID control is used to accurately control the temperature during the process. After the demagnetization of a certain magnetic pole is completed, the relative position of the demagnetization coil device 3 and the rotor 7 is adjusted by the execution device 4, and the demagnetization process is repeated to heat the remaining magnetic poles, and the surface magnetic data during the process is collected until the demagnetization of the entire rotor 7 is completed.

[0025] To improve demagnetization efficiency, the control actuator 4 drives the demagnetization coil assembly 3 along the circumference of the magnetic poles, demagnetizing each pole individually. After demagnetization is complete, the surface magnetism of the entire rotor 7 can be tested again to identify any remaining areas for additional demagnetization. All surface magnetism data is then recorded and collected for subsequent research.

[0026] Furthermore, since nearby undemagnetized magnetic poles may affect the results of surface magnetic detection during the surface magnetic detection process when the rotor 7 is not fully demagnetized, before demagnetization, a magnetic field simulation model of the rotor 7 poles can be established based on the external shape information of the rotor 7 and the magnetic poles, and a surface magnetic detection correction algorithm can be calibrated to process the data obtained from subsequent surface magnetic detection, thereby obtaining more accurate surface magnetic measurement results. In specific operations, ANSYS MAXWELL or other electromagnetic simulation software is used to establish a complete rotor 7 model containing all magnetic poles. By setting the demagnetization state of different magnetic poles and solving them separately, the surface magnetic data of each magnetic pole after sequential demagnetization is collected and processed. In this way, a surface magnetic measurement model is established that eliminates interference from adjacent magnetic poles (when the surface magnetic field reaches a certain value in a certain state, it can be considered to be completely demagnetized). The model data can be corrected through sample experiments.

[0027] Furthermore, for magnets with protective shells, the outer surface temperature is not accurately measured due to the slow heating of the stainless steel shell. Therefore, before demagnetization, the structure and material information of the magnet and the shell can be simulated and modeled, and a temperature-heating time compensation correction algorithm can be established between the shell and the magnet to process the surface temperature data collected by the infrared thermometer, thereby obtaining more accurate temperature measurement results. In specific operations, ANSYS WORKBENCH can be used to geometrically model a single magnet module, add eddy current excitation inside the magnetic pole as a heat load, and apply the natural heat dissipation coefficient and ambient temperature to the surface of the shell. The change of the shell and internal temperature over time under different temperature rise conditions is solved, and the collected data is fitted into the internal and external temperature relationship curve model at different times and different parameters. The model is then calibrated through the actual measured data of the sample experiment with the same parameters. Relying on this calibration model, more accurate temperature measurement results can be obtained.

[0028] Example 2 Based on the first embodiment, this embodiment further illustrates the structure of the demagnetization coil device 3 .

[0029] In this embodiment, the structure of the demagnetization coil device 3 can be referred to in the appendix of the specification. Figure 2 As shown, the demagnetization coil device 3 includes multiple induction coils arranged in an array, forming a rectangular array coil 11 whose overall length covers the length of a single magnetic pole and whose overall width covers at least the width of a single magnetic pole. In this embodiment, the width of the array coil 11 should cover an integer number of magnetic poles as much as possible.

[0030] In order to ensure uniform heating, the structures of the induction coils should be the same, and the spacing between adjacent coils should be the same. Preferably, in this embodiment, the shape of each induction coil is a square with equal sides in all directions. The array coil 11 can be designed as a curved surface that matches the shape of the rotor 7. Preferably, in order to control the magnetic field strength inside the coil to be as consistent as possible, the single-sided size of the induction coil is preferably 20~30cm. By controlling the size of a single coil, increasing the number of small eddy currents and heating points, when the same demagnetization induction current is passed into each coil, an alternating magnetic field can be uniformly generated on the demagnetization surface, forming multi-point simultaneous heating, and achieving an overall uniform heating effect.

[0031] Considering the problem that when the same current flows through each coil, the reverse magnetic field generated by the current in the coil on the outside of the coil may cause the magnetic fields between adjacent coils to cancel each other out, resulting in a weakened heating effect, the present invention proposes the following two solutions: The first method is to pass the same current through each coil and increase the gap between the coils. The gap is preferably half or more of the side length of a single coil. This arrangement prevents the magnetic fields in the center of the coil from canceling each other out. The magnetic fields between the coils are superimposed and reinforced. At a certain moment, the magnetic fields in the coils face inwards and are independent of each other, while the magnetic fields between the coils face outwards. Figure 3 This solution is relatively simple to implement and leaves more space for arranging water cooling pipelines.

[0032] The second type: The coils are arranged close to each other (almost edge to edge, the distance is set according to the actual situation), and the currents flowing through adjacent coils are set with a phase difference according to the coil arrangement. Figure 4 As shown, under this arrangement, the current phases in adjacent coils differ by 180 degrees. At a certain moment, the magnetic fields of adjacent coils are of the same magnitude but in opposite directions. The magnetic field within a coil is superimposed on the magnetic field in the adjacent coil, which in turn enhances the magnetic field. This method transforms the magnetic field cancellation between adjacent coils into mutual enhancement in terms of periodicity, while ensuring the uniformity of the magnetic field and thus achieving uniform heating. The key to this method lies in the setting of the coil current phase difference. The optimal setting varies for coils of different arrangements and shapes, and can be adjusted according to actual conditions.

[0033] The demagnetization coil device 3 in this embodiment utilizes the eddy current effect to generate an alternating magnetic field near the magnetic poles. The specially designed demagnetization coil can generate a uniform demagnetization magnetic field around the magnetic poles, ensuring that all parts of the magnetic steel are evenly heated to above the Curie point. This solves the problem of uneven heating caused by uneven magnetic field distribution in conventional coils and improves the stability of the demagnetization effect.

[0034] Example 3 When an alternating current flows through the induction coil near the magnetic pole of the rotor 7, the coil may deform or vibrate. Therefore, based on the second embodiment, the demagnetization coil device 3 of this embodiment is further designed with a fixing plate 12 and a cover plate 13 for reinforcing and supporting the coil to resist coil deformation, as shown in FIG. Figure 5 As shown. The fixing plate 12 is made of insulating material, such as epoxy laminated glass cloth board, which has flame retardant and insulating properties. A cavity 14 is dug on the fixing plate 12 corresponding to each coil with a shape matching that of the coil. The array coil 11 is embedded in the cavity 14 and fixed by a cover plate 13 covering the fixing plate 12. Figure 6 shown.

[0035] Based on the design of the demagnetization coil device 3 described above, the surface magnetic detection device 5 can utilize a surface magnetic detection sensor array to detect surface magnetic data. In this embodiment, the surface magnetic sensor can be a gallium arsenide Hall element. The temperature measurement device 6 can also utilize an array of infrared temperature probes to detect the surface temperature of the magnetic steel. In a specific implementation, small holes are reserved on the cover plate 13 at the exact center of each induction coil, and infrared temperature probes are arranged in these holes to form an array. The surface magnetic detection sensor array and the infrared temperature probe array can be staggered.

[0036] Example 4 Based on the content of any of the above embodiments, this embodiment further illustrates the specific structure of the execution device 4 in a magnetic steel thermal demagnetization system of an outer rotor 7 of a permanent magnet direct-drive wind turbine.

[0037] like Figure 7 The figure shows a feasible structural solution for an actuator device according to the present invention. The actuator device 4 comprises a main body 401, a movable device and a telescopic device 402 connected to the main body 401. The movable device is used to achieve displacement of the entire device along the circumference of the base of the direct-drive rotor 7. The telescopic device 402 is connected to the demagnetization coil device 3 and is used to adjust the distance between the demagnetization coil device 3 and the magnetic pole.

[0038] The moving device includes a servo motor and a traveling assembly driven by the servo motor. In this embodiment, the servo motor can be a hub motor 404. The traveling assembly includes a support wheel 403 and a guide wheel 405. Driven by the hub motor 404, the support wheel 403 can roll along the end face of the direct-drive rotor 7 base, thereby driving the demagnetization coil device 3 to move along the circumference of the rotor 7 base, gradually completing the demagnetization. There are two guide wheels 405, each of which is tightly attached to the two side faces of the end face of the direct-drive rotor 7 base. The spacing between the two guide wheels 405 can be controlled and adjusted to accommodate rotor 7 bases of different wall thicknesses. During the demagnetization process, the two guide wheels 405 play a guiding role in assisting the support wheel 403 in its movement.

[0039] In this embodiment, the telescopic device 402 can be implemented by a hydraulic telescopic rod or other telescopic devices 402. The telescopic front end of the telescopic device 402 is connected to a coil fixing cantilever 406, and the demagnetization coil device 3 is connected to the coil fixing cantilever 406, facing the magnetic pole surface of the rotor 7 to be demagnetized.

[0040] Furthermore, to automatically adjust the position of the demagnetization coil assembly 3, a slide motor 407 is mounted on the coil-mounting cantilever 406. The slide motor 407 slides parallel to the axis of the rotor 7. The demagnetization coil assembly 3 is mounted on a slider of the slide motor 407. Based on the detection data from the surface magnetic field detection device 5, the slide motor 407 automatically adjusts the position of the demagnetization coil assembly 3 to align with the upper and lower positions of the magnetic poles. When the surface magnetic field detection device 5 detects a gradual decrease in the magnetism at the upper and lower ends of the magnetic poles, the demagnetization coil assembly 3 is considered aligned.

[0041] Through the design of the execution device 4, the demagnetization coil device 3 can be automatically controlled to move along the circumferential direction of the rotor 7, demagnetizing each part of the magnetic pole one by one, thereby improving the demagnetization efficiency. At the same time, the demagnetization process is more automated and the labor intensity is reduced.

[0042] In this embodiment, the demagnetization process of the execution device 4 is as follows: 1) Put the rotor 7 in place, clean the magnetic pole surface of the rotor 7, and lift the device to the end face of the rotor 7.

[0043] 2) The control device 1 controls the guide wheel 405 to clamp the machine base cylinder, and at the same time controls the telescopic device 402 to move the demagnetization coil device 3 close to the magnetic pole. At the same time, the surface magnetic detection sensor array is close to the surface of the magnetic pole to detect the surface magnetic and position data of the magnetic pole and feed it back to the control device 1.

[0044] 3) Based on the matrix surface magnetic and position data, the control device 1 controls the coil fixing slide to adjust the coil up and down position until the surface magnetic detection data is fed back to the control device 1 to determine that the magnetic poles are completely covered.

[0045] 4) Magnetic pole shape information, including magnet thickness, magnet position and number of poles, is input into control device 1. Control device 1 selects appropriate demagnetization parameters based on the matched magnet thickness information and inputs them into demagnetization current generator 2. Simultaneously, control device 1 performs parameter modeling based on the input magnetic pole shape information, calibrates the surface magnetic detection correction algorithm and temperature, and processes subsequent surface magnetic detection and infrared temperature measurement data as the basis for system control.

[0046] 5) Demagnetization current generator 2 uses input parameters to convert grid input into a demagnetization current, which is fed into demagnetization coil device 3 to generate an alternating magnetic field, inducing eddy currents in the magnet and causing a rapid temperature increase. Simultaneously, the surface magnetic field sensor array monitors the magnet's surface magnetic field in real time, while infrared temperature probes placed on the coil surface collect real-time surface temperature data from the magnet and feed it back to control device 1. 6) When it is recognized that the surface magnetism has changed and does not change subsequently, it is considered that the magnetic pole has been demagnetized, heating is stopped and the heating temperature at that moment is recorded.

[0047] 7) The control device 1 subsequently uses high-power induction heating according to the heating temperature data, and uses PID control to accurately control the temperature during the process to quickly heat up the remaining magnetic poles.

[0048] 8) After the demagnetization of the first part of the magnetic poles is completed, the servo motor is driven by the control device 1 to control the movement of the support wheel 403, and the positioning movement position is based on the surface magnetic detection, so as to heat the remaining magnetic poles and collect the surface magnetic data in the process to complete the demagnetization of the entire rotor 7.

[0049] After completion, the surface magnetism of the entire rotor 7 is tested again to identify the parts that have not been demagnetized completely and perform additional demagnetization. All surface magnetism data are recorded and collected for subsequent research.

[0050] Example 5 This embodiment has the following differences compared to embodiment 4: The mobile device in the execution device 4 can also be used as follows Figure 8 The illustrated arrangement comprises a rotating shaft 9 and a cantilever 10 connected to the rotating shaft 9 disposed at the center of the rotor 7. The telescopic device 402 is secured to the cantilever 10, positioning the demagnetization coil device 3 opposite the inner surface of the magnetic poles of the rotor 7. The remaining configuration remains consistent with the execution device of Example 5. A servo motor and gears cooperate to drive the rotating shaft 9 to rotate, thereby driving the demagnetization coil device 3 to move along the circumference of the base of the direct-drive rotor 7, gradually achieving demagnetization.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A permanent magnet direct drive wind turbine motor outer rotor magnetic steel thermal demagnetization system, characterized in that: include: A demagnetization coil device (3), the demagnetization coil device (3) being opposite to the magnetic pole surface of the rotor (7) to be demagnetized, and being used to generate a uniform alternating magnetic field, inducing eddy currents in the permanent magnet to heat up to above the Curie point for demagnetization; A demagnetization current generating device (2) is connected to the demagnetization coil device (3) and is used to generate a demagnetization current matching the thickness of the magnetic steel according to a control instruction of the control device (1) and input the demagnetization current into the demagnetization coil device (3); An execution device (4) is connected to the demagnetization coil device (3) and is used to adjust the position of the demagnetization coil device (3) to drive the demagnetization operation of the entire rotor (7); A surface magnetic detection device (5) is arranged on the front end surface of the demagnetization coil device (3) and is used to synchronously collect surface magnetic data of the magnetic pole surface during the demagnetization process and feed it back to the control device (1); A temperature measuring device (6) is arranged on the front end surface of the demagnetization coil device (3) and is used to synchronously collect temperature data of the magnetic pole surface during the demagnetization process and feed it back to the control device (1); The control device (1) is connected to various devices and equipment signals, receives real-time detection data from the surface magnetic detection device (5) and the temperature measurement device (6), and outputs control instructions to the demagnetization current generating device (2) and the execution device (4) to regulate the heating temperature and heating time during the demagnetization process.

2. A permanent magnet direct drive wind turbine outer rotor magnetic steel thermal demagnetization system according to claim 1, characterized in that: The demagnetization coil device (3) comprises a plurality of induction coils, which are arranged in an array form to form an array coil (11) whose overall length covers the length of a single magnetic pole and whose overall width at least covers the width of a single magnetic pole.

3. A permanent magnet direct drive wind turbine outer rotor magnetic steel thermal demagnetization system according to claim 2, characterized in that: In the array coil (11), the structures of the induction coils are the same, and the spacing between adjacent induction coils is the same.

4. A permanent magnet direct drive wind turbine outer rotor magnetic steel thermal demagnetization system according to claim 3, characterized in that: The shape of each induction coil is square, and the single side size of the induction coil is 20~30cm.

5. A permanent magnet direct drive wind turbine outer rotor magnetic steel thermal demagnetization system according to any one of claims 2 to 4, characterized in that: The demagnetization coil device (3) further comprises an insulating fixing plate (12) and a cover plate (13) covering the surface of the insulating fixing plate (12); a cavity (14) matching the coil shape is excavated on the insulating fixing plate (12); the coil is embedded in the corresponding cavity (14) and fixed by the cover plate (13).

6. A permanent magnet direct drive wind turbine outer rotor magnetic steel thermal demagnetization system according to claim 5, characterized in that: A small hole is provided on the surface of the cover plate (13) at the exact center position corresponding to each induction coil, and an infrared temperature measuring probe is arranged in each hole to form an infrared temperature measuring probe array.

7. The permanent magnet direct drive wind turbine motor outer rotor magnetic steel thermal demagnetization system according to claim 1, characterized in that: The execution device (4) includes a main body (401), a moving device connected thereto for driving the demagnetization coil device (3) as a whole to move along the circumference of the base of the direct-drive rotor (7), and a telescopic device (402) for adjusting the distance between the demagnetization coil device (3) and the magnetic pole.

8. The permanent magnet direct drive wind turbine motor outer rotor magnetic steel thermal demagnetization system according to claim 7, characterized in that: The moving device includes a servo motor and a walking assembly driven by the servo motor. The walking assembly includes a support wheel (403) and a guide wheel (405). The support wheel (403) rolls along the end face of the base of the direct-drive rotor (7) under the drive of the servo motor. The guide wheel (405) is provided with two wheels and is respectively in close contact with two side faces of the end face of the base of the direct-drive rotor (7).

9. The permanent magnet direct drive wind turbine motor outer rotor magnetic steel thermal demagnetization system according to claim 8, characterized in that: The telescopic front end of the telescopic device (402) is connected to a coil fixing cantilever (406), and a slide motor (407) is provided on the coil fixing cantilever (406); the demagnetization coil device (3) is installed on a slider of the slide motor (407), and the slide motor (407) automatically adjusts the position of the demagnetization coil device (3) to align with the upper and lower positions of the magnetic poles according to the detection data of the surface magnetism detection device (5).

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