System and method for demagnetizing permanent magnet rotor

Abstract

The invention provides a system and a method for demagnetizing a permanent magnet rotor. Methods and systems for demagnetizing a rotor. In one example, the method includes: adjusting a position of a magnetic pole mounted on a frame in a demagnetization system relative to a first motor rotor; and reducing the magnetization of the first motor rotor by operating the demagnetizing system to generate an electromagnetic field.

Description

Technical Field

[0001] The present description generally relates to methods and systems for demagnetizing a permanent magnet rotor using an electromagnetic field. Background Art

[0002] Electric machines including rare earth permanent magnets are used in many applications due to their high performance. Mining, separating and manufacturing rare earth elements involves many steps and is a complex process overall. Therefore, from an efficiency and environmental perspective, it may be desirable to recycle rare earth permanent magnets.

[0003] Some recycling methods crush or melt the motor before separating the rare earth elements from the mixture. However, these recycling methods are energy intensive and complex. Separating the rare earth permanent magnets from the motor rotor core during the recycling process may be more efficient than crushing or melting the entire motor. However, due to the strong magnetic field generated by the rare earth permanent magnets, it may be difficult to remove the magnets without demagnetization.

[0004] Attempts have been made to demagnetize the rotor during motor recycling. An exemplary method is shown by Araki et al. in JP2012-147602A, which describes a device for demagnetizing and removing permanent magnets from the rotor. In Araki's system, the permanent magnets are held in a demagnetizing retainer and heated to melt the joints and demagnetize the magnets for recycling. In Araki's device, the induction heating coils of the demagnetizing device heat the rotor magnets, and the coils are designed to make axial adjustments. Summary of the invention

[0005] However, the inventors herein have recognized potential problems with Araki's system and other demagnetization systems. The coils in Araki's device have fixed radial positions, which limits the applicability of the device. Therefore, multiple demagnetization devices may be used to demagnetize rotors of different shapes or sizes. Demagnetization is complicated and inefficient when a facility has multiple rotors of various designs and sizes. In addition, melting the rotor may cause difficulties in downstream processing of the rotor components.

[0006] In one example, the above problems can be solved at least in part by a method for operating a demagnetization system. In one example, the method includes adjusting (e.g., radially adjusting) the position of the magnetic pole relative to the motor rotor. In addition, the method includes reducing the magnetization intensity of the motor rotor via an electromagnetic field generated by the demagnetization system. In this way, rotors of different sizes and designs can be effectively demagnetized by the demagnetization system.

[0007] Furthermore, in one example, the position of the magnetic poles and / or the current, frequency, or duration of the electromagnetic field can be adjusted during demagnetization of the motor rotor to improve the efficiency of the demagnetization process. For example, the magnetic flux of the rotor can be monitored during demagnetization, and when the magnetic flux exceeds a threshold, the current, frequency, or duration of the electromagnetic field can be increased. In this way, the efficiency of the demagnetization process is further improved.

[0008] It should be understood that the above summary is provided to introduce a series of concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 An exemplary demagnetization system positioned to demagnetize a first rotor is shown.

[0010] Figure 2 Shows Figure 1 A demagnetization system is configured to demagnetize the second rotor.

[0011] Figure 3 Shows Figure 1 Detailed view of the magnetic poles of the demagnetization system.

[0012] Figure 4 A second example of a demagnetization system for demagnetizing a rotor is shown.

[0013] Figure 5 Shows Figure 4 The magnetic poles of the demagnetization system.

[0014] Figure 6 A method for demagnetizing a rotating rotor is shown.

[0015] Figure 7 A method for demagnetizing a stationary rotor is shown. DETAILED DESCRIPTION

[0016] The following description relates to systems and methods for demagnetizing a permanent magnet rotor of an electric motor. Electric motors, such as traction motors in vehicles, typically include permanent magnets (e.g., rare earth magnets). Once a rotor is no longer in use, it may be desirable to recycle the permanent magnets. In order to effectively recycle the permanent magnets, a demagnetization system can be used to implement a demagnetization process of the magnets. During the demagnetization process, the rotor is positioned within the demagnetization system. The demagnetization system includes poles, each of which can be adjusted radially and / or axially to accommodate the rotor. Thus, the demagnetization system is able to accommodate rotors of various designs and / or sizes.

[0017] A demagnetization system may be used to reduce the magnetic flux of the permanent magnets within the rotor via an electromagnetic field. The demagnetization system may generate an electromagnetic field via magnetic poles. In some examples, each magnetic pole may include a permanent magnet and one or more insulating layers, such as Figure 1 , Figure 2 and Figure 3 As shown. Thus, the magnetic poles can generate a direct current (DC) electromagnetic field. In other examples, the magnetic poles can each include a coil and a steel lamination, such as Figure 4 and Figure 5 As shown. Therefore, the magnetic poles can generate a DC electromagnetic field or an alternating current (AC) electromagnetic field, depending on the power supplied to the coil. In order to demagnetize the rotor in a DC electromagnetic field, the rotor can be rotated relative to the demagnetization system, as shown in reference Figure 6 Furthermore, in order to demagnetize the rotor in an AC electromagnetic field, the rotor can be kept stationary relative to the demagnetization system, as described in reference Figure 7 During demagnetization via a DC electromagnetic field or an AC electromagnetic field, the magnetic poles of the demagnetization system can be adjusted radially and / or axially. Such adjustments can allow the demagnetization system to accommodate structural components of the rotor and / or modify the electromagnetic field to more effectively demagnetize the rotor.

[0018] Figures 1 to 5 A coordinate system is included for orienting the view. In one example, the z-axis can be a vertical axis (e.g., parallel to the gravity axis), the y-axis can be a longitudinal axis (e.g., a horizontal axis), and / or the x-axis can be a transverse axis. However, in other examples, the axes can have other orientations.

[0019] Figure 1 An example of a demagnetization system 100 and a rotor 102 for an electric machine is shown. The electric machine may be an electric motor used in a vehicle, such as a traction motor. However, the demagnetization system may be used to demagnetize the rotor of a wide variety of electric motors that may be used in a variety of environments, including but not limited to factories, machinery, appliances, etc.

[0020] The rotor 102 includes a rotor body 104 and permanent magnets 106. Thus, the magnets can have a high coercivity and resist changes in magnetization. In some examples, the magnets can be rare earth magnets. For example, the magnets can include neodymium or samarium cobalt. In other examples, the magnets can include alnico or ferrite. From an environmental perspective, it may be desirable to recycle the magnets. However, the magnets can generate strong magnetic fields, which increases the difficulty of removing the magnets from the rotor body 104 without demagnetization. In addition, the permanent magnets can be adhesively bonded to the rotor body using epoxy and / or other suitable adhesives, which can cause further difficulties when deconstructing the rotor.

[0021] In the example shown, the permanent magnets 106 include six magnets. In other examples, the permanent magnets 106 may include more or less than six magnets, depending on the design of the rotor 102. The magnets may be arranged circumferentially and positioned proximate to the circumferential surface 110 of the rotor body 104. In some examples, consecutive magnets may be evenly spaced.

[0022] During the demagnetization process, the rotor 102 is positioned in the demagnetization system 100. In detail, the rotor 102 can be mounted on a shaft 124, which is positioned at the center of the demagnetization system 100. In one example, the shaft 124 can be configured to rotate. A motor or other suitable device can be used to rotate the shaft 124. The demagnetization system 100 may include a magnetic pole 108. The magnetic pole can be arranged circumferentially and positioned close to the outside of the circumferential surface 110 of the rotor body 104. Therefore, the magnetic pole can at least partially surround the rotor body 104. In addition, one surface of each magnetic pole can be aligned tangentially with the circumferential surface 110. Each magnetic pole can be positioned opposite to another magnetic pole. In addition, in some examples, continuous magnetic poles can be evenly spaced (for example, the distance between the magnetic pole 109 and two adjacent magnetic poles can be the same). In other examples, the magnetic pole 108 can be arranged in another suitable orientation so that the demagnetization system 100 can at least partially surround the rotor 102. The magnetic poles 108 may be mounted on a frame 122, which may be included in a fixture 123, and the position of each magnetic pole may be adjusted relative to the frame. For example, the frame 122 may have a circular or polyhedral shape.

[0023] The magnetic poles 109 can be adjusted axially and / or radially along the axis 126 along the axis 128 (e.g., along the length of the rotor 102). Similarly, each of the magnetic poles 108 can be adjusted along the axial and / or radial axis. Such adjustment of the magnetic poles allows the demagnetization system 100 to accommodate and demagnetize many different rotors with various designs and / or sizes. In this way, the demagnetization system 100 can be used for a wide range of rotor types, thereby expanding the applicability of the system. The position of the magnetic poles can be adjusted before the rotor 102 is attached to the shaft 124.

[0024] Each of the magnetic poles 108 may include a permanent magnet 112. The permanent magnet 112 may be oriented so that its poles (e.g., north pole and south pole) face the same direction. Thus, the permanent magnets may constructively generate a DC magnetic field. Adjacent poles may be oriented in opposite directions. The magnet may be segmented. In detail, the magnet may be divided into smaller components along a radial or axial direction.

[0025] An insulating layer 116 may be used to join / separate segmented components. The insulating layer 116 may be positioned between the permanent magnets 112. The insulating layer may be adhesively bonded or otherwise suitably attached to the magnets. The insulating layer serves to reduce eddy currents in the permanent magnets. However, other suitable pole configurations have been contemplated.

[0026] The magnetic poles 108 generate a collective DC electromagnetic field for demagnetizing the rotor 102 (and more specifically, the permanent magnets 106). In detail, the rotor 102 can rotate around the axis 130 on the shaft 124 within the demagnetization system 100 to cause demagnetization of the rotor, and more specifically, demagnetization of the permanent magnets 106. When the rotor 102 and the shaft 124 rotate around the axis 130 within the demagnetization system, the orientation of the DC electromagnetic field relative to each magnet changes over time. The multiple magnetic dipoles of each magnet can be reoriented at different points in time by the DC electromagnetic field, thereby randomizing the magnetic dipoles within each magnet and thus causing a loss of magnetization. In addition, in another example, the magnetic poles 108 may include two or more layers of magnetic poles along the axial direction.

[0027] During the demagnetization process (which may include the rotation of the rotor 102 within the demagnetization system 100), one or more of the magnetic poles 108 may be adjusted axially and / or radially. In some examples, the position of the magnetic poles may be adjusted based on the magnetic flux density of the rotor 102. For example, the magnetic poles may be adjusted radially to adjust the strength of the magnetic field experienced by the permanent magnets 106. In addition, the magnetic poles may be adjusted axially so that all portions of the rotor 102 may be accommodated within the demagnetization system at a certain point in time. Therefore, the demagnetization system 100 may effectively demagnetize rotors having various designs.

[0028] The controller 113 may form part of a control system 117. The control system 117 is shown as receiving information from the sensor 115 and sending control signals to the actuator 181. As an example, the sensor 115 may include sensors such as a rotational speed sensor, a magnetic flux density sensor, etc. The actuator 181 may include an actuator 182 for adjusting the radial position of the magnetic pole 108, and an actuator 183 for adjusting the axial position of the shaft 124 and thus the rotor 102. The controller 113 may receive input data from the sensor, process the input data via a processor, and trigger the actuator in response to the processed input data based on instructions or coding corresponding to one or more programs programmed in the input data. In some examples, the controller 113 may include instructions to send command signals to the actuators of the demagnetization system 100 to adjust the radial position of the magnetic poles based on the measured magnetic flux density of the rotor 102.

[0029] The magnetic flux density of rotor 102 may be measured by sensor 118, which may be included in sensor 115. Figure 1 As shown, the sensor 118 can be positioned near the outside of the circumferential surface 110 of the rotor body 104. In addition, the sensor 118 can be a flux meter or another suitable device for measuring magnetic flux density. The controller 113 can receive signals from the sensor 118 and can use the actuators 182, 183 to adjust the position of the magnetic pole 108 based on the received signals and the instructions stored in the memory of the controller 113.

[0030] The axial and / or radial position of the poles can be adjusted before the rotor is attached to the shaft 124, which allows the system to be configured for rotors of different shapes, as discussed above. In addition, in some examples, the axial and / or radial position of the poles can be dynamically adjusted during demagnetization. In detail, as the magnetic flux density of the rotor 102 decreases, the actuator 182 can radially adjust the position of the poles 108 to move it further away from the rotor 102 to gradually reduce the demagnetization magnetic field on the magnet. In a use case example, the movement can be continuous and the demagnetization process can be completed in a few seconds. In addition, the shaft 124 can also be dynamically adjusted as it moves the rotor in and out of the demagnetization system. As the rotor gradually moves out, the magnetic field from the demagnetization system may also gradually decay, which has the same effect as moving the poles in the radial direction.

[0031] Adjusting the radial and / or axial position of the magnetic poles may include adjusting an actuator coupled to the magnetic poles. In some examples, a mechanical piston, a hydraulic device, a combination thereof, etc. may automatically actuate the adjustment of the magnetic poles. In other examples, an operator may manually adjust the position of the magnetic poles by adjusting screws, etc. The control system 117 may also be configured to: Figure 4 is shown in and can be used in conjunction with the demagnetization system shown therein and described in more detail herein.

[0032] like Figure 1 As shown, the rotational speed of the rotor 102 can be measured by a sensor 120 that can be included in the sensor 115. The sensor 120 can be positioned close to the outside of the circumferential surface 110 of the rotor body 104. The rotational speed can be adjusted based on the magnetic flux density measured by the sensor 118 during the demagnetization process. For example, the rotational speed of the rotor 102 can decrease as the magnetic flux density of the rotor decreases. The controller 113 can receive a signal from the sensor 118 and the sensor 120 can use an actuator 181 to adjust the rotational speed of the shaft 124 and thus the rotor based on the received signal and the instructions stored on the memory of the controller 113. For example, adjusting the rotational speed of the shaft 124 may include adjusting the actuator of the motor responsible for the rotation of the shaft. In addition, the rotation of the shaft and the rotor can be stopped in response to the magnetic flux density of the rotor dropping below a threshold.

[0033] Figure 2A second rotor 202 is shown including a rotor body 204 and magnets 206. In the example shown, the diameter of the second rotor 202 is greater than Figure 1 The second rotor 104 is a rotor having a diameter greater than that of the rotor 102, and thus the rotor body 204 is larger than the rotor body 104 of the rotor 102. In addition, the second rotor includes a greater number of magnets 206. The magnets 206 may be oriented circumferentially and positioned proximate to a circumferential edge 210 of the rotor body 204. As described above, the demagnetization system 100 can be effectively reconfigured to accommodate rotors of a variety of sizes, profiles, etc.

[0034] As shown, the second rotor 202 is positioned within the demagnetization system 100. In addition, the second rotor 202 is mounted on the shaft 124, which is positioned at the center of the demagnetization system 100. The demagnetization system 100 includes poles 108, a frame 122, a control system 117, a sensor 118, a sensor 120, and an actuator 182. In order to accommodate the second rotor 202, which is larger than the rotor 102, the poles 108 are radially adjusted away from the shaft 124, which provides more space for the second rotor 202 within the demagnetization system 100. In some examples, the poles can be adjusted axially to accommodate one or more structural features of the second rotor. For example, the poles 109 can be adjusted along the axis 128 to a position to accommodate the second rotor. In this way, the poles 108 can still be positioned close to the outside of the circumferential edge 210 of the rotor body 204. The poles 108 may have been radially adjusted by the actuator 182 to accommodate the second rotor 202, as shown in reference Figure 1 described.

[0035] Figure 3 Shows Figure 1 and Figure 2 The magnetic pole 109 of the demagnetization system 100. As shown in reference Figure 1 As described, the pole 109 may include a permanent magnet 112, and an insulating layer 116 may be positioned in the middle of the permanent magnet 112. The use of permanent magnets and one or more insulating layers in the pole may allow the pole to be heated more slowly, and therefore retain more power and durability. More specialized magnet arrangements (e.g., Halbach arrays) may also concentrate the magnetic field and increase the magnetic field strength at the same magnet volume, or make the magnet assembly more compact than a single-piece pole and a pole including a coil.

[0036] Figure 4 An example of a degaussing system 400 is shown that is similar to the degaussing system 100. Therefore, overlapping components of the degaussing system 400 and the degaussing system 100 may be similarly numbered. Figure 4Also shown is the rotor 102. The rotor 102 can be positioned on the shaft 124 of the demagnetization system 400. The demagnetization system 400 includes magnetic poles 408. In the example shown, each of the magnetic poles 408 includes a coil 402 and a metal lamination 404 (e.g., steel laminations), rather than the permanent magnets and insulating layers described with respect to the magnetic poles 108.

[0037] Figure 4 The illustrated magnetic poles 408 can each generate a DC electromagnetic field or an AC electromagnetic field when supplied with DC or AC, respectively. Thus, the magnetic poles 408 can generate a collective DC electromagnetic field or a collective AC electromagnetic field for demagnetizing the rotor 102 (and more specifically, the permanent magnets 106).

[0038] The demagnetization system 400 can generate a DC electromagnetic field when supplied with direct current. In some examples, the rotor 102 can be rotated around the axis 130 (e.g., the longitudinal axis of the rotor) within the demagnetization system 400 via the shaft 124 to cause demagnetization of the rotor (e.g., the permanent magnets 106). As the shaft and the rotor rotate around the axis 130 within the demagnetization system, the orientation of the DC electromagnetic field relative to each of the magnets changes over time. The multiple magnetic dipoles of each magnet can be reoriented at different points in time by the DC electromagnetic field, thereby randomizing the magnetic dipoles within each magnet and thus reducing the magnetization intensity. During demagnetization of the rotor 102 by the DC electromagnetic field, the position of the magnetic poles 408 can be adjusted radially and / or axially, and the rotational speed of the rotor can be adjusted, as shown in reference to FIG. Figure 1 For example, the magnetic poles 409 can be adjusted axially along the axis 412 and / or radially along the axis 410. In addition, the rotational speed of the shaft 124 and, therefore, the rotor 102 can be adjusted by one or more actuators of the control system 117 based at least in part on the magnetic flux density of the rotor. Thus, the demagnetization system 400 can be adjusted to accommodate various sizes and design features of the rotor.

[0039] Additionally or alternatively, Figure 4 The demagnetization system 400 can generate an AC electromagnetic field when supplied with AC. The AC electromagnetic field causes demagnetization of static objects. Therefore, when the poles 408 generate AC, the shaft 124 and the rotor 102 can remain stationary within the demagnetization system 100 during the demagnetization of the permanent magnet rotor. When the rotor is stationary within the demagnetization system, the AC electromagnetic field continuously changes direction and magnitude over time. The changing nature of the AC electromagnetic field can randomly reorient the magnetic dipole of each magnet, resulting in a loss of magnetization. In some examples, discrete current pulses can be supplied to the poles 408 instead of continuously supplying alternating current.

[0040] Similar to demagnetization using a DC electromagnetic field, one or more of the magnetic poles 408 can be adjusted axially and / or radially during demagnetization using an AC electromagnetic field. Therefore, the controller 113 can include sending a command signal to the actuator 182 of the demagnetization system 400 to adjust the radial position of one or more of the magnetic poles 408 based on measurements made by the sensor 115 (e.g., sensor 118 and / or sensor 120). For example, as the magnetic flux density of the rotor 102 decreases, the actuator 182 can radially adjust the position of the magnetic pole 408 to move it further away from the rotor. In addition, the actuator can axially adjust the magnetic poles as the rotor rotates so as to effectively demagnetize all portions of the rotor.

[0041] In addition, the AC and pulse current can be adjusted during the demagnetization of the rotor 102, and in some examples, the pulse current can be adjusted. The supplied AC can be adjusted based on the magnetic flux density measured by the sensor 118 during the demagnetization process. For example, the magnitude of the AC can decrease as the magnetic flux density of the rotor decreases. For example, adjusting the AC can include adjusting the circuit that controls the power supply responsible for supplying current to the demagnetization system 400. In addition, in response to the magnetic flux density of the rotor dropping below a threshold, the current passing through the coil of each pole can be interrupted. It should be understood that, as described herein, when the magnetic flux density of the magnet drops below a threshold, the magnet can be demagnetized, and the threshold may be non-zero in some examples, and may not be zero for recycling purposes. Therefore, even if the magnetic flux density of the magnet may be greater than zero, the magnet can be indicated as demagnetized. However, it should be understood that in some cases, the demagnetization system can demagnetize the magnet so that the magnetic flux density is zero or close to zero.

[0042] Figure 5 Shows Figure 4 The magnetic pole 409 of the demagnetization system 400 includes a coil 402 and a steel lamination 404. The coil 402 can be a spiral coil of a metal wire whose length is greater than its diameter (e.g., a solenoid). In some examples, the coil 402 can be made of copper and / or other suitable materials. In addition, the coil can have an axis 406, which can be oriented tangentially to the closest point of the circumferential surface 110 of the rotor body 104 (e.g., parallel to the x-axis). The coil can generate an electromagnetic field when an electric current is provided. Similarly, each of the magnetic poles 408 can generate an electromagnetic field via the coil when an electric current is provided.

[0043] Each of the magnetic poles 408 may include a steel lamination 404. In one example, the steel lamination 404 includes a plurality of layers that may be formed of electrical steel. In one specific example, the steel lamination may be comprised of high silicon steel. The coil 402 may be positioned around at least a portion of the steel lamination 404. In addition, the steel lamination includes a plurality of steel sheets, such as Figure 5 The steel laminations are configured to reduce eddy current losses.

[0044] Figure 6 A method 600 for demagnetizing a rotating rotor using a demagnetization system is shown. The method 600 and other methods described herein may be performed by Figure 1 The demagnetization system 100 shown, Figure 4 The method 600 and / or other methods described herein may be implemented by other suitable demagnetization systems. In alternative examples, however, the method 600 and / or other methods described herein may be implemented by other suitable demagnetization systems. Instructions for implementing the method 600 and the remaining methods included herein may be executed by a controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the demagnetization system. According to the method described below, the controller may use an actuator of the demagnetization system to adjust the operation of the demagnetization system.

[0045] At 602, method 600 includes adjusting the magnetic poles of the demagnetization system according to the size of the rotor being demagnetized. The magnetic poles of the demagnetization system can be adjusted radially with respect to the rotor. In detail, the magnetic poles can be adjusted radially so that each magnetic pole is positioned close to the outer surface of the rotor. The ability to radially adjust the magnetic poles allows the demagnetization system to be used with many different rotors, each having a variety of sizes and designs, thereby expanding the applicability and attractiveness of the system.

[0046] At 604, method 600 includes positioning the rotor in the demagnetization system. For example, the rotor can be coupled to the shaft of the system. Once the rotor is coupled to the shaft, the rotor can be axially translated to a desired position. In this way, the axial position of the rotor can be adjusted to accommodate rotors of different shapes. However, in other examples, the axial position of the shaft (which determines the axial position of the rotor) can be adjusted at step 602. The rotor can be positioned so that the poles are circumferentially positioned and positioned close to the outer surface of the rotor.

[0047] At 606, method 600 includes setting the operating parameters of the demagnetization system. Setting the operating parameters includes: at 608, setting the magnetic field of the magnetic poles of the demagnetization system. As described above, the DC electromagnetic field generated by the demagnetization system can be adjusted by adjusting the magnitude of the DC current supplied to the coils of the magnetic poles. Therefore, the strength of the DC electromagnetic field can be set by supplying a specific magnitude of direct current to each coil of the demagnetization system based on the current magnetic flux density of the rotor. In detail, the operating parameters may include the amount of current delivered to the magnetic poles, the rotational speed of the rotor and the shaft, the duration and frequency of the electromagnetic field, and / or the radial position of the magnetic poles. In the case of magnetic poles, the magnetic poles can be set to be in a position closest to the rotor surface, and the rotational speed of the shaft will gradually increase until the rotor magnetic flux surface magnitude begins to decrease, and then the magnetic poles can be gradually adjusted to reduce the magnetic field on the magnets. Alternatively, the shaft can move in the axial direction, and the magnetic field on the magnets can also be gradually reduced when the rotor moves out of the fixture.

[0048] Setting the operating parameters of the demagnetization system includes setting the rotational speed of the rotor, as indicated at 610. As discussed above, the rotor can be rotated on the shaft within a DC electromagnetic field so that the rotor is demagnetized. Therefore, the rotational speed of the shaft and the rotor can be set by a mechanical power source (e.g., a motor) based on the current magnetic flux density of the rotor. For example, as the magnetic flux density of the rotor decreases, the shaft can rotate slower.

[0049] At 614, method 600 includes monitoring the magnetic flux density of the rotor magnetic field. Specifically, in one example, the magnetic flux density can be monitored after each rotation of the rotor. However, in other examples, the magnetic flux density can be monitored after multiple cycles. When the rotor is demagnetized, the strength of the magnetic field generated by the magnet decreases. The strength of the rotor magnetic flux density can be monitored by one or more sensors of the demagnetization system. In some examples, the sensors can be positioned close to the outer surface of the rotor. In addition, in some examples, the sensors can each be a flux meter or another suitable hardware component for measuring magnetic flux density.

[0050] At 616, method 600 includes determining whether the magnetic flux density of the rotor is less than a threshold value. The control system determines whether the measured magnetic flux density is below a predetermined threshold value. The threshold value may be determined based on the rotor design, the type of magnets within the rotor, the requirements of downstream magnet processing, etc. In some examples, the threshold value may be in the range of 0 to 0.1 T, or may be expressed as a relative value (e.g., in one use case example, expressed as 10% of the original strength).

[0051] If the rotor flux is not lower than the threshold value ( Figure 6 If the answer is no), the method 600 returns to 606. After the method returns to 606, the amount of current provided to the magnetic poles, the rotational speed of the rotor, and / or the duration of the current are increased.

[0052] If the rotor flux is below the threshold after rotation ( Figure 6 If the demagnetization system utilizes coils and metal laminations, such as Figure 4 As shown, DC current can no longer be supplied to the coils of the magnetic poles. If the demagnetization system utilizes permanent magnets, the magnetic poles can be translated radially and / or axially away from the rotor. In addition, the rotor can be axially translated out of the demagnetization system (e.g., unloaded from the system). Once removed from the demagnetization system, the rotor can be disassembled and recycled.

[0053] Figure 7A method 700 for demagnetizing a static (non-rotating) rotor using a demagnetization system is shown. At 702, the method 700 includes adjusting the magnetic poles of the demagnetization system according to the size of the rotor being demagnetized. At 704, the method 700 includes positioning the rotor in the demagnetization system. 702 and 704 can be respectively Figure 6 602 and 604 are the same.

[0054] At 706, method 700 includes setting demagnetization operating parameters. Setting operating parameters may include, at 707, setting estimated AC and pulse currents. Figure 4 As explained, the AC electromagnetic field generated by the demagnetization system can be adjusted by adjusting the magnitude and / or direction of the alternating current supplied to the coils of each magnetic pole. Thus, the strength of the AC electromagnetic field can be set by supplying a specific magnitude of alternating current to each coil of the demagnetization system based on the current magnetic flux density of the rotor. For example, less alternating current can be supplied to the coils, and thus the AC electromagnetic field can become weaker as the magnetic flux density of the motor decreases. In some examples, pulsed current (discrete current pulses) can be supplied to the coils instead of continuous alternating current. The magnitude and / or frequency of the pulsed current can be set at 706.

[0055] At 708, method 700 includes monitoring the magnetic flux density of the rotor magnetic field. When magnetized, the magnets within the rotor generate a magnetic field. When the rotor is demagnetized, the magnetic field generated by the magnets decreases. The strength of the magnetic field generated by the rotor can be measured as magnetic flux density by one or more sensors of the demagnetization system. In some examples, the sensors can be positioned close to the outer surface of the rotor. In addition, in some examples, the sensors can each include a flux meter or another suitable hardware component for measuring magnetic flux density.

[0056] At 710, method 700 includes determining whether the magnetic flux density of the rotor or an equivalent is less than a threshold value. The threshold value may be determined based on the rotor design, the type of magnets within the rotor, etc. If the magnetic flux density of the rotor is not less than the threshold value ( Figure 7 If the answer is no), the method 700 returns to 706. After the method returns to 706, the amount of current provided to the magnetic pole, the frequency of the current, and / or the duration of the current are increased.

[0057] If the rotor flux is below the threshold ( Figure 7 ), the method 700 proceeds to 712. At 712, the method 700 includes stopping the demagnetization and unloading the rotor. In detail, the current supplied to the coils of each pole is interrupted. In addition, the rotor can be axially translated out of the demagnetization system (e.g., unloaded from the system). Once removed from the demagnetization system, the rotor can then be disassembled and recycled.

[0058] In this way, a system and method for demagnetizing permanent magnets in a rotor without pre-disassembling the rotor is proposed. The demagnetization system can be used to demagnetize different permanent magnet rotors of various designs and sizes. The demagnetization system can be configured to generate an electromagnetic field around the rotor, wherein the electromagnetic field can be an AC or DC electromagnetic field. The AC electromagnetic field can be generated by the demagnetization system when the rotor is stationary, or the DC electromagnetic field can be generated by the demagnetization system when the rotor is rotating. Eddy currents induced in the permanent magnets of the rotor due to the electromagnetic field can heat (e.g., inductively heat) the magnets and reduce the coercive force, thereby allowing each magnet to be demagnetized via a weaker electromagnetic field / current. In addition, the heat generated by the eddy currents induced via the demagnetization system can soften any epoxy resin around the permanent magnets of the rotor, which can further facilitate the removal of magnets from the rotor core. Compared with other methods, the system and method described herein produce higher demagnetization efficiency and increased system applicability due to the system's ability to accommodate different rotors (e.g., motors) of various designs and demagnetize them.

[0059] A technical effect of the method described herein is to effectively demagnetize rotors of various shapes and sizes.

[0060] Figures 1 to 5 An exemplary configuration with relative positioning of various components is shown. If shown as directly contacting or directly connected to each other, such elements can be referred to as directly contacting or directly connected, respectively, in at least one example. Similarly, in at least one example, elements shown as being adjacent or adjacent to each other can be adjacent or adjacent to each other, respectively. As an example, components that are coplanarly contacted with each other can be referred to as coplanar contact. As another example, in at least one example, elements that are positioned apart from each other with only space between them and no other components can be referred to as such. As another example, elements shown as being above / below each other, on opposite sides or on the left / right side of each other can be referred to as such relative to each other. In addition, as shown in the accompanying drawings, in at least one example, the topmost element or the vertex of an element can be referred to as the "top" of a component, and the bottommost element or the bottommost point of an element can be referred to as the "bottom" of a component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the accompanying drawings, and are used to describe the positioning of the elements of the accompanying drawings relative to each other. Therefore, in one example, an element shown as being above other elements is located vertically above other elements. As yet another example, shapes of elements depicted within the drawings may be referred to as having these shapes (e.g., such as being rounded, straight, planar, curved, rounded, chamfered, angled, etc.). Additionally, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Further, in one example, elements shown as being within another element or shown as being outside another element may be referred to as such.

[0061] In one example, a method is provided, the method comprising: adjusting the position of a plurality of magnetic poles in a demagnetization system relative to a first motor rotor; and reducing the magnetic flux of the first motor rotor via operating the demagnetization system to generate an electromagnetic field, wherein the plurality of magnetic poles are positioned on a frame. In a first example of the method, operating the demagnetization system to generate an electromagnetic field comprises rotating the first motor rotor in a static electromagnetic field. In a second example of the method (optionally including the first example), the method further comprises: monitoring the magnetic flux density of the first motor rotor; and adjusting the current, frequency, or duration of the electromagnetic field generated by the demagnetization system based on the magnetic flux density. In a third example of the method (optionally including one or both of the first and second examples), adjusting the current, frequency, or duration of the electromagnetic field comprises increasing the current, frequency, or duration of the magnetic field in response to the magnetic flux density exceeding a threshold, and interrupting the generation of the electromagnetic field in response to the magnetic flux density decreasing below a threshold. In a fourth example of the method (optionally including one or more or each of the first to third examples), the position of the plurality of magnetic poles may be adjusted before generating the electromagnetic field, and the position may be a radial position. In a fifth example of the method (optionally including one or more or each of the first to fourth examples), the positions of the plurality of magnetic poles can be dynamically adjusted during the generation of the electromagnetic field. In a sixth example of the method (optionally including one or more or each of the first to fifth examples), the electromagnetic field is an alternating current (AC) field, and the method further includes maintaining the first motor rotor stationary. In a seventh example of the method (optionally including one or more or each of the first to sixth examples), the electromagnetic field is a direct current (DC) field, and the method further includes rotating the first motor rotor while the demagnetization system generates the DC field. In an eighth example of the method (optionally including one or more or each of the first to seventh examples), the method further includes: monitoring the magnetic flux density of the first motor rotor; and adjusting the rotor speed, the electromagnetic field current, or the electromagnetic field frequency based on the magnetic flux density. In a ninth example of the method (optionally including one or more or each of the first to eighth examples), the method also includes adjusting a position of a plurality of magnetic poles relative to a second motor rotor, and reducing a magnetic flux of the second motor rotor by operating a demagnetization system to generate an electromagnetic field, wherein the first motor rotor and the second motor rotor have different sizes and / or permanent magnet configurations.

[0062] In another example, a demagnetization system is provided, the demagnetization system comprising: a frame; a plurality of magnetic poles, the plurality of magnetic poles being adjustably attached to the frame; and a controller, the controller comprising instructions stored on a non-transitory memory, the instructions causing the controller to reduce the magnetic flux of the first motor rotor by operating the demagnetization system to generate an electromagnetic field when executed. In the first example of the demagnetization system, the plurality of magnetic poles each comprise a permanent magnet. In the second example of the demagnetization system (optionally including the first example), the controller further comprises instructions stored on the non-transitory memory, the instructions causing the controller to dynamically adjust the position of the plurality of magnetic poles relative to the first motor rotor when executed. In the third example of the demagnetization system (optionally including one or both of the first and second examples), the dynamic adjustment is an axial adjustment. In the fourth example of the demagnetization system (optionally including one or more or each of the first to third examples), the dynamic adjustment is a radial adjustment. In the fifth example of the demagnetization system (optionally including one or more or each of the first to fourth examples), the plurality of magnetic poles each comprise a stack of steel laminations and coils. In a sixth example of the demagnetization system (optionally including one or more or each of the first to fifth examples), the steel laminations are silicon steel laminations. In a seventh example of the demagnetization system (optionally including one or more or each of the first to sixth examples), the plurality of magnetic poles each include a plurality of permanent magnets and at least one insulating layer positioned between the plurality of permanent magnets.

[0063] In yet another example, a method is provided, the method comprising: adjusting an axial or radial position of a plurality of magnetic poles in a demagnetization system relative to a first motor rotor; and reducing magnetic flux of the first motor rotor by operating the demagnetization system to generate an electromagnetic field, wherein the plurality of magnetic poles are positioned on a frame. In a first example of the method, the electromagnetic field is an alternating current (AC) field, and the method further comprises maintaining the first motor rotor stationary, or the electromagnetic field is a direct current (DC) field, and the method further comprises rotating the first motor rotor while the demagnetization system generates the DC field.

[0064] It should be noted that the exemplary control and estimation procedures included herein can be used with various demagnetization system configurations. The control methods and procedures disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in combination with various sensors, actuators and other hardware. The specific procedures described herein can represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Therefore, the various actions, operations and / or functions shown can be performed in the sequence shown, performed in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations and / or functions shown can be repeatedly performed according to the specific strategy used. In addition, the described actions, operations and / or functions can be graphically represented as codes in a non-transitory memory of a computer-readable storage medium that will be programmed into a control system, wherein the described actions are implemented by executing instructions in a system including various hardware components in conjunction with an electronic controller.

[0065] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be considered to have a limiting meaning, as many variations are possible. In addition, unless explicitly stated to the contrary, the terms "first," "second," "third," etc. are not intended to represent any order, position, quantity, or importance, but are merely used as markers to distinguish one element from another. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0066] The appended claims particularly point out certain combinations and subcombinations deemed novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presenting new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included in the subject matter of the present disclosure.

Claims

1. A method comprising: adjusting the positions of a plurality of magnetic poles in the demagnetization system relative to the rotor of the first motor; as well as reducing magnetic flux of the first electric machine rotor by operating the demagnetization system to generate an electromagnetic field; Wherein the plurality of magnetic poles are positioned on a frame. 2 . The method of claim 1 , wherein operating the demagnetization system to generate the electromagnetic field comprises rotating the first motor rotor in a static electromagnetic field.

3. The method of claim 1, further comprising: monitoring the magnetic flux density of the rotor of the first motor; as well as A current, frequency, or duration of the electromagnetic field generated by the demagnetization system is adjusted based on the magnetic flux density.

4. The method of claim 3, wherein adjusting the current, the frequency, or the duration of the electromagnetic field comprises: increasing the current, the frequency, or the duration of the electromagnetic field in response to the magnetic flux density exceeding a threshold; as well as The generation of the electromagnetic field is discontinued in response to the magnetic flux density decreasing below the threshold.

5. The method of claim 1, wherein the positions of the plurality of magnetic poles are adjusted before generating the electromagnetic field, and the positions are radial positions.

6. The method of claim 1, wherein the positions of the plurality of magnetic poles are dynamically adjusted during generation of the electromagnetic field.

7. The method of claim 1, wherein the electromagnetic field is an alternating current (AC) field, and the method further comprises maintaining the first motor rotor stationary.

8. The method of claim 1, wherein the electromagnetic field is a direct current (DC) field, and the method further comprises rotating the first motor rotor while the demagnetization system generates the DC field.

9. The method of claim 8, further comprising: monitoring the magnetic flux density of the rotor of the first motor; as well as The rotor speed, the electromagnetic field current or the electromagnetic field frequency is adjusted based on the magnetic flux density.

10. The method of claim 1, further comprising: adjusting the positions of the plurality of magnetic poles relative to the second motor rotor; as well as reducing the magnetic flux of the second electric machine rotor by operating the demagnetization system to generate the electromagnetic field; The first motor rotor and the second motor rotor have different sizes and / or permanent magnet configurations.

11. A demagnetization system, comprising: frame; a plurality of magnetic poles adjustably attached to the frame; as well as A controller comprising instructions stored on a non-transitory memory, the instructions when executed causing the controller to: The magnetic flux of the first electric machine rotor is reduced by operating the demagnetization system to generate an electromagnetic field.

12. The demagnetization system of claim 11, wherein each of the plurality of magnetic poles comprises a permanent magnet.

13. The demagnetization system of claim 11, wherein the controller further comprises instructions stored on the non-transitory memory, the instructions when executed causing the controller to: The positions of the plurality of magnetic poles relative to the first motor rotor are dynamically adjusted.

14. The demagnetization system of claim 13, wherein the dynamic adjustment is an axial adjustment.

15. The demagnetization system of claim 13, wherein: The dynamic adjustment is radial adjustment; The plurality of magnetic poles each include a stack of steel laminations and a coil; The steel laminations are high silicon steel laminations; and / or The plurality of magnetic poles each include a plurality of permanent magnets and at least one insulating layer positioned between the plurality of permanent magnets.

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