Magnetic alignment system and method for permanent magnet motor

Abstract

Embodiments of the present disclosure relate to magnetic alignment systems and methods for permanent magnet motors. A system for manufacturing a rotor for a permanent magnet (PM) motor is provided. The system includes a mold configured to receive a rotor body, the rotor body including a plurality of rotor teeth and defining one or more rotor cavities, and a plurality of electromagnetic coils including a plurality of magnetic cores and a plurality of electromagnetic windings, each magnetic core of the plurality of magnetic cores configured to align with a respective rotor tooth of the plurality of rotor teeth. The system also includes a controller configured to close the mold after the rotor body is positioned within the mold, energize the plurality of electromagnetic coils after closing the mold, inject magnetic material into the one or more rotor cavities, where the plurality of electromagnetic coils are electrically coupled to the mold before curing of the magnetic material. The energized electromagnetic coils align the magnetic material to a desired magnetic orientation, powering off the plurality of electromagnetic coils.

Description

Background Art

[0001] The field of the present disclosure relates generally to permanent magnet (PM) electric machines, and more particularly to PM electric machine manufacturing using injection molding.

[0002] A PM motor is an electric motor that uses permanent magnets to provide a magnetic field that can interact with one or more windings to produce motion. With respect to manufacturing PM motors, known systems and methods are deficient in some respects in meeting the needs of PM motor manufacturers and improvements are needed. Summary of the invention

[0003] In one aspect, a system for manufacturing a rotor for a permanent magnet (PM) motor is provided. The system includes a mold configured to receive a rotor body, the rotor body including a plurality of rotor teeth and defining one or more rotor cavities. The system also includes a plurality of electromagnetic coils, the plurality of electromagnetic coils including a plurality of magnetic cores and a plurality of electromagnetic windings, each of the plurality of magnetic cores being configured to align with a corresponding rotor tooth in the plurality of rotor teeth, wherein each of the electromagnetic windings is wound around at least one magnetic core in the plurality of magnetic cores. The system also includes a controller configured to: close the mold after the rotor body is positioned in the mold; after closing the mold, energize the plurality of electromagnetic coils; after energizing the plurality of electromagnetic coils, inject magnetic material into the one or more rotor cavities, wherein the energized electromagnetic coils align the magnetic material into a desired magnetic orientation before solidification of the magnetic material; and after injecting the magnetic material, de-energize the plurality of electromagnetic coils.

[0004] On the other hand, a method for manufacturing a rotor for a PM motor is provided. The method is performed using a system including a mold and a plurality of electromagnetic coils, the mold being configured to receive a rotor body, the rotor body including a plurality of rotor teeth and defining one or more rotor cavities, the plurality of electromagnetic coils including a plurality of magnetic cores and a plurality of electromagnetic windings, each of the plurality of magnetic cores being configured to align with a corresponding rotor tooth in the plurality of rotor teeth, wherein each of the electromagnetic windings is wound around at least one of the plurality of magnetic cores. The method includes: closing the mold after the rotor body is positioned in the mold; after closing the mold, energizing the plurality of electromagnetic coils; after energizing the plurality of electromagnetic coils, injecting magnetic material into the one or more rotor cavities, wherein the energized electromagnetic coils align the magnetic material into a desired magnetic orientation before solidification of the magnetic material; and de-energizing the plurality of electromagnetic coils after injecting the magnetic material.

[0005] On the other hand, a controller for manufacturing a rotor for a PM motor is provided. The controller communicates with a mold and a plurality of electromagnetic coils, the mold being configured to receive a rotor body, the rotor body comprising a plurality of rotor teeth and defining one or more rotor cavities, the plurality of electromagnetic coils comprising a plurality of magnetic cores and a plurality of electromagnetic windings, each of the plurality of magnetic cores being configured to align with a corresponding rotor tooth of the plurality of rotor teeth, wherein each of the electromagnetic windings is wound around at least one of the plurality of magnetic cores. The controller is configured to: close the mold after the rotor body is positioned in the mold; after closing the mold, energize the plurality of electromagnetic coils; after energizing the plurality of electromagnetic coils, inject magnetic material into the one or more rotor cavities, wherein the energized electromagnetic coils align the magnetic material into a desired magnetic orientation before solidification of the magnetic material; and after injecting the magnetic material, de-energize the plurality of electromagnetic coils. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a perspective view of an example system for manufacturing a PM motor;

[0007] Figure 2 is used for Figure 1 a perspective view of an example electromagnetic coil of the system shown;

[0008] Figure 3 It is along Figure 2 The section line 3-3 shown is taken Figure 2 A cross-sectional view of an example electromagnetic coil is shown;

[0009] Figure 4 is used for Figure 1 a perspective view of another example electromagnetic coil of the illustrated system; and

[0010] Figure 5 is a flow chart illustrating an example method for manufacturing a PM electric machine. DETAILED DESCRIPTION

[0011] Example embodiments of the present disclosure include a system and corresponding method for manufacturing a permanent magnet (PM) motor. The manufacture of PM motors traditionally utilizes discrete magnets. Challenges involved in the manufacturing chain include the need for inventory control of parts of different sizes, and the need to bond the magnets in the rotor, resulting in a curing step for the parts. Therefore, a process that can manufacture PM in situ directly in the rotor cavity of a PM motor provides technical and economic advantages.

[0012] In an example embodiment, the system includes a mold configured to receive a rotor body including a plurality of rotor teeth and defining one or more rotor cavities that can be filled with a magnetic material, such as a polymer with embedded magnetic particles. The system also includes a plurality of electromagnetic coils including a plurality of magnetic cores aligned with corresponding rotor teeth of the plurality of rotor teeth, and a plurality of electromagnetic windings, each electromagnetic winding being wound around at least one magnetic core of the plurality of magnetic cores so that a desired magnetic field pattern can be generated when current is supplied to the electromagnetic windings.

[0013] After the rotor body is positioned in the mold, the mold is closed, the electromagnetic coil is energized, and the magnetic material is then injected into the rotor cavity. The energized electromagnetic coil aligns the magnetic material into the desired magnetic orientation before the magnetic material solidifies. Then, after the magnetic material is sufficiently solidified, the electromagnetic coil is de-energized to produce a PM rotor structure with the desired magnetic orientation for use in a PM motor.

[0014] Thus, the systems and methods described herein provide many advantages over known systems and methods for manufacturing PM motors. One benefit is that the automatic simultaneous insertion of magnets into the cavity shortens manufacturing time, reduces the chance of human error (e.g., magnetic orientation), and eliminates the need for adhesives and associated curing time. Another benefit is a simplified supply chain because pellets (raw materials for injection molding of multiple frame sizes) can be used instead of discrete magnets of different sizes. Another benefit is flexibility in material selection because the change from one magnetic compound to a different magnetic compound does not require any physical modification to the mold. Another benefit is the ability to fully automate the process without the need for post-processing (such as magnetization). Another benefit is modularity because the mold can be configured to accommodate rotors with different numbers of poles or different sizes by adjusting the mold and / or the number of electromagnetic coils mounted around the mold accordingly. In addition, in some embodiments, the rotor can be assembled onto the shaft to (completely / partially) inject the magnetic material, which reduces the need for post-processing.

[0015] Figure 1 is a perspective view of an example system 100. In an example embodiment, the system 100 includes a mold 102 configured to receive a rotor body 104 including a plurality of rotor teeth 106. The rotor body 104 defines one or more rotor cavities 108 extending axially through the rotor body 104. The rotor cavities 108 may be filled with a magnetic material, as described in further detail below. Figure 1 As shown, in some embodiments, the rotor teeth 106 are curvilinear and arranged in concentric groups corresponding to the poles of the rotor body 104. For example, Figure 1The rotor body 104 is depicted as having four rotor poles, each having a set of concentric rotor teeth 106 and a rotor cavity 108. In such an embodiment, the rotor cavity 108 is defined between pairs of concentric rotor teeth 106. In some embodiments, the rotor body 104 is formed by a plurality of rotor laminations that may be layered in an axial direction to form the rotor body 104. In some such embodiments, each rotor lamination has substantially the same shape, and each rotor lamination is rotationally skewed relative to adjacent rotor laminations. In such an embodiment, when the rotor cavity 108 passes through the rotor body 104, the rotor cavity 108 is curved relative to the axis of the rotor body 104.

[0016] In an exemplary embodiment, the system 100 also includes a plurality of electromagnetic coils 110. Each electromagnetic coil 110 includes a plurality of magnetic cores 112. Each magnetic core 112 is configured to align with a corresponding rotor tooth in the rotor teeth 106. Each electromagnetic coil 110 also includes a plurality of electromagnetic windings 114. Each electromagnetic winding 114 is wound around a corresponding magnetic core 112 so that when the electromagnetic winding 114 is provided with current and energized, the corresponding magnetic core 112 is magnetized. In an embodiment where the rotor body 104 defines a plurality of rotor poles, there is one electromagnetic coil 110 for each rotor pole, and each electromagnetic coil 110 is configured to align with a corresponding rotor pole when the rotor body 104 is placed in the mold 102. The shape of the magnetic core 112 is complementary to the shape of the rotor teeth 106 to provide efficient magnetic flux transfer to the rotor cavity 108. For example, the magnetic core 112 can be shaped so that, as Figure 1 As shown, when the magnetic core 112 and the rotor teeth 106 are aligned, any gaps between the respective ends of the magnetic core 112 and the rotor teeth 106 are minimized. In some embodiments, the electromagnetic coil 110 also includes a mounting plate 116 to which the magnetic core 112 is attached.

[0017] The electromagnetic winding 114 is formed of a conductive material, such as, for example, aluminum or copper, and may be formed of wire or foil. In some embodiments, the electromagnetic winding 114 may include an electrical insulator on its surface. In embodiments where there is more than one winding layer, insulation may be applied between the layers. The insulation may include a film (e.g., polyethylene terephthalate (PET), paper-based (Nomex)) and / or a liquid (heat / UV) curable resin (e.g., epoxy and acrylate). The electromagnetic winding 114 is thick enough to reduce losses and temperature rise, and to limit leakage flux passing between the magnetic cores 112. Due to the high current (and current density), there is a significant magnetic potential between the magnetic cores 112.

[0018] In the example embodiment, the system 100 also includes a controller 118. The controller 118 communicates with components of the system 100 and is configured to control these components, such as the mold 102, the electromagnetic coil 110, or other components described herein. It should be understood that in some embodiments, one or more of the functions of the controller 118 described below may be performed by components other than the single controller 118 (e.g., Figure 1 For example, in some embodiments, different controllers can control different parts of the system 100, and / or certain functions can be performed manually and / or based on manual input by an operator. In some embodiments, the electromagnetic coils 110 are electrically connected in series and use a single power source that can be controlled by a controller 118 (e.g., integrated into hardware for controlling injection molding).

[0019] In an example embodiment, the controller 118 is configured to close the mold 102 after the rotor body 104 is positioned within the mold 102. For example, the controller 118 can control an actuator that causes the mold 102 to close. By closing the mold 102, a closed space is created that can be injected with molten hot magnetic material. In some embodiments, the rotor body 104 is divided into axial segments, each of which can be inserted into the mold 102 at a separate time. The rotor body 104 is positioned within the mold 102 so that each rotor pole of the rotor body 104 is aligned with the corresponding electromagnetic coil 110, and each rotor tooth 106 is aligned with the corresponding magnetic core 112.

[0020] In an exemplary embodiment, the controller 118 is configured to inject the magnetic material into the rotor cavity 108 after closing the mold. For example, the controller 118 can control the injector to move the magnetic material as a fluid or liquid (e.g., a molten polymer including embedded magnetic particles) into the mold 102 to fill the rotor cavity 108. During injection, the magnetic material (e.g., polymer and magnetic particles) fills the rotor cavity 108 under a certain pressure. The temperature of the magnetic material during the injection process depends on the plastic matrix. In some embodiments, the injection period lasts from about 0.5 to about 10 seconds. After being injected into the rotor cavity 108, the magnetic material can begin to cool and eventually solidify.

[0021] In an example embodiment, after closing the mold 102, the controller 118 is configured to energize the electromagnetic coil 110 to align the magnetic material into a desired magnetic orientation prior to solidification of the magnetic material. For example, the controller 118 may cause current to be supplied to the electromagnetic winding 114, thereby magnetizing the magnetic core 112, which in turn generates a magnetic field that causes the fluid magnetic material to align into the desired magnetic orientation. The electromagnetic coil 110 may be energized before and / or during injection of the magnetic material.

[0022] The magnetic flux density applied to all rotor cavities 108 must be higher than the magnetic field required to fully orient the magnetic particles embedded in the magnetic material. In some embodiments, for example, the magnetic field density can be about 1.8 Tesla for the magnetic core 112 of the iron-based structure or about 2.2 Tesla for the magnetic core 112 of the iron-cobalt-based structure. When the magnetic field is applied, the magnetic particles of the magnetic material rotate so that their magnetization axis is aligned with the magnetic field. This happens when the viscosity of the polymer containing the magnetic particles (which is a function of temperature) is low enough (that is, the temperature is still high enough). Due to the dependence of the magnetocrystalline anisotropy constant and the saturation polarization (which controls the intrinsic coercive force), the magnetic field required for orientation is a function of temperature. The magnetic field generated by the electromagnetic coil 110 is determined by the direct current applied during excitation. Applying a higher current will produce a stronger magnetic field. In some embodiments, the electromagnetic winding 114 is configured to carry a current density of about 15 amperes per square millimeter to about 25 amperes per square millimeter. The level of directional magnetic field strength required depends on the specific magnetic material used. Examples of materials, ranked from lowest to highest magnetic field requirements, include: polymer bonded ferrite, polymer bonded Sm-Fe-N, polymer bonded Neo, polymer bonded Mn-Bi, and polymer bonded Sm-Co. For the magnetic materials listed (but not limited to them), if a relatively small number of foil turns are used for the electromagnetic winding 114, the current applied during the process should be on the order of tens to hundreds of amperes. This approach also allows for relatively low coil excitation voltage requirements (e.g., less than 48 volts), providing greater safety compared to more traditional wire implementations.

[0023] In an example embodiment, after energizing the electromagnetic coil 110, the controller 118 is configured to de-energize the electromagnetic coil 110. In some embodiments, the controller 118 de-energizes the electromagnetic coil 110 after the magnetic material solidifies. Because the magnetic material is solidified while being held in the desired magnetic orientation by the electromagnetic coil 110, the magnetic material retains the desired magnetic orientation after solidification even when the electromagnetic coil 110 is de-energized and the oriented magnetic field generated thereby is removed.

[0024] In some embodiments, after the curing of the magnetic material, the controller 118 is further configured to open the mold 102. For example, the controller 118 can control an actuator that causes the mold 102 to close. In some embodiments, the controller 118 is further configured to cause the mold to eject the rotor body 104 and the cured magnetic material contained within the rotor body 104. For example, the controller 118 can control an actuator that pushes or otherwise moves the rotor body 104 outside the mold 102. Because the cured magnetic material is contained within the rotor body 104, the mechanism for ejecting the rotor body 104 should be strong enough to overcome any magnetic force that prevents the rotor body 104 from being removed from the mold 102.

[0025] Figure 2 is a perspective view of an example electromagnetic coil 110 including a magnetic core 112 and an electromagnetic winding 114, which is generally as described with respect to Figure 1 It works as described. Figure 3 It is along Figure 2 The cross-sectional view of the electromagnetic coil 110 is shown along the cross-sectional line 3-3. Figure 2 and Figure 3 In the example embodiment shown, the electromagnetic coil 110 is configured to align with the rotor body 104 having a rotational skew. Therefore, in the example embodiment, the shape of the magnetic core 112 is designed to have a curvature relative to the axis of the rotor body 104 so that the end of each magnetic core can be aligned with the corresponding rotor tooth 106 of the rotor body 104. Figure 2 and Figure 3 As shown, a single electromagnetic winding 114 can be used to magnetize multiple cores 112. In particular, the electromagnetic winding 114 can be wound around two cores 112, each core 112 being aligned with a corresponding end of the same rotor tooth 106 (e.g., Figure 1 shown).

[0026] Figure 4 is a perspective view of another example electromagnetic coil 110 including a magnetic core 112 and an electromagnetic winding 114, which is generally as described with respect to Figure 1 It works as described. Figure 4 In the illustrated example embodiment, the electromagnetic coils 110 are configured to be aligned with the rotor body 104 without rotational skew. Therefore, in the illustrated example embodiment, the magnetic cores 112 are shaped to extend substantially parallel to the axis of the rotor body 104 so that the ends of each magnetic core can be aligned with the corresponding rotor teeth 106 of the rotor body 104.

[0027] Figure 5is a flow chart illustrating an example method 500 for manufacturing a PM motor. In an example embodiment, method 500 is performed using a system (such as system 100) that includes a mold (such as mold 102) and a plurality of electromagnetic coils (such as electromagnetic coil 110), the mold being configured to receive a rotor body (such as rotor body 104), the rotor body including a plurality of rotor teeth (such as rotor teeth (106)) and defining one or more rotor cavities (such as rotor cavity 108), the plurality of electromagnetic coils including a plurality of magnetic cores (such as magnetic core 112) and a plurality of electromagnetic windings (such as electromagnetic winding 114), each magnetic core in the plurality of magnetic cores being configured to align with a corresponding rotor tooth in the plurality of rotor teeth, wherein each electromagnetic winding in the electromagnetic windings is wound around at least one magnetic core in the plurality of magnetic cores. In some embodiments, each step of method 500 is performed by and / or under the direction of a single controller (such as controller 118). Alternatively, in some embodiments, one or more steps of method 500 may be performed by a separate controller and / or manually. For example, the mold 102 and its associated injection device may be controlled by one controller, while the solenoid 110 may be controlled by another controller, with each controller executing corresponding program instructions.

[0028] In the example embodiment, method 500 includes closing 502 the mold after the rotor body is positioned within the mold.

[0029] In the example embodiment, method 500 further includes energizing 504 the plurality of electromagnetic coils after closing the mold.

[0030] In an example embodiment, method 500 further includes injecting 506 magnetic material into the one or more rotor cavities after energizing the plurality of electromagnetic coils, wherein the energized electromagnetic coils align the magnetic material into a desired magnetic orientation prior to solidification of the magnetic material.

[0031] In an example embodiment, method 500 also includes de-energizing 508 the plurality of electromagnetic coils after injecting the magnetic material.

[0032] In some embodiments, method 500 further includes opening 510 the mold after curing of the magnetic material.

[0033] In some embodiments, method 500 further includes causing the mold to eject 512 the rotor body after opening the mold.

[0034] In some embodiments, the electromagnetic coil is de-energized after curing of the magnetic material.

[0035] In some embodiments, the plurality of rotor teeth are curvilinear, and at least one of the one or more rotor cavities is defined between a pair of concentric rotor teeth of the plurality of rotor teeth.

[0036] In some embodiments, the rotor body is formed from a plurality of rotor laminations. In some such embodiments, at least one rotor lamination of the plurality of rotor laminations is rotationally skewed relative to another lamination of the plurality of rotor laminations.

[0037] In some embodiments, the rotor body defines a plurality of rotor poles, and each electromagnetic coil of the plurality of electromagnetic coils is configured to align with a corresponding rotor pole of the plurality of rotor poles.

[0038] Example embodiments of systems and methods for manufacturing PM motors are described in detail above. The systems and methods are not limited to the specific embodiments described herein, but rather, the components of the systems and / or operations of the methods may be used independently and separately from other components and / or operations described herein. In addition, the components and / or operations described may also be defined in or used in conjunction with other systems, methods, and / or devices, and are not limited to practice using only the systems described herein.

[0039] At least one technical effect of the systems and methods described herein includes (a) enabling automatic insertion of permanent magnets into a rotor by utilizing a system comprising a mold and a plurality of electromagnetic coils that can be aligned with magnetic material injected into the mold; (b) simplifying the material required to insert the permanent magnets into the rotor by using molten magnetic material; and (c) improving the modularity of a system for manufacturing PM motors by utilizing an automated system comprising a mold and a plurality of electromagnetic coils that can be aligned with magnetic material injected into the mold, wherein the number of electromagnetic coils and the properties of the injected material can be controlled to achieve the desired specifications of the rotor.

[0040] Although specific features of various embodiments of the present invention may be shown in some drawings but not in other drawings, this is only for convenience. According to the principles of the present invention, any feature in a drawing may be referenced and / or claimed in combination with any feature in any other drawing.

[0041] This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any device or system and performing any combined method. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples should be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims.

Claims

1. A system for manufacturing a rotor for a permanent magnet PM motor, the system comprising: a mold configured to receive a rotor body including a plurality of rotor teeth and defining one or more rotor cavities; Multiple electromagnetic coils, including: a plurality of magnetic cores, each magnetic core of the plurality of magnetic cores being configured to align with a corresponding rotor tooth of the plurality of rotor teeth; and a plurality of electromagnetic windings, wherein each of the electromagnetic windings is wound around at least one magnetic core of the plurality of magnetic cores; and The controller is configured as: After the rotor body is positioned within the mold, closing the mold; after closing the mold, energizing the plurality of electromagnetic coils; injecting a magnetic material into the one or more rotor cavities after energizing the plurality of electromagnetic coils, wherein the energized electromagnetic coils align the magnetic material into a desired magnetic orientation prior to solidification of the magnetic material; and After injecting the magnetic material, the plurality of electromagnetic coils are de-energized. 2 . The system of claim 1 , wherein the controller is further configured to open the mold after curing of the magnetic material. 3 . The system of claim 2 , wherein the controller is further configured to cause the mold to be ejected from the rotor body after opening the mold.

4. The system of claim 1, wherein the electromagnetic coil is de-energized after solidification of the magnetic material.

5. The system of any one of claims 1 to 4, wherein the plurality of rotor teeth are curvilinear, and wherein at least one of the one or more rotor cavities is defined between a pair of concentric rotor teeth of the plurality of rotor teeth.

6. The system of any one of claims 1 to 4, wherein the rotor body is formed from a plurality of rotor laminations. 7 . The system of claim 6 , wherein at least one rotor lamination of the plurality of rotor laminations is rotationally skewed relative to another lamination of the plurality of rotor laminations.

8. The system of any one of claims 1 to 4, wherein the rotor body defines a plurality of rotor poles, and wherein each electromagnetic coil of the plurality of electromagnetic coils is configured to align with a corresponding rotor pole of the plurality of rotor poles.

9. A method for manufacturing a rotor for a permanent magnet PM motor using a system, the system comprising a mold and a plurality of electromagnetic coils, the mold being configured to receive a rotor body, the rotor body comprising a plurality of rotor teeth and defining one or more rotor cavities, the plurality of electromagnetic coils comprising a plurality of magnetic cores and a plurality of electromagnetic windings, each of the plurality of magnetic cores being configured to align with a corresponding rotor tooth of the plurality of rotor teeth, wherein each of the electromagnetic windings is wound around at least one magnetic core of the plurality of magnetic cores, the method comprising: After the rotor body is positioned within the mold, closing the mold; after closing the mold, energizing the plurality of electromagnetic coils; injecting a magnetic material into the one or more rotor cavities after energizing the plurality of electromagnetic coils, wherein the energized electromagnetic coils align the magnetic material into a desired magnetic orientation prior to solidification of the magnetic material; and After injecting the magnetic material, the plurality of electromagnetic coils are de-energized.

10. The method of claim 9, further comprising opening the mold after curing of the magnetic material.

11. The method of claim 10, further comprising causing the mold to eject the rotor body after opening the mold.

12. The method of claim 9, wherein the electromagnetic coil is de-energized after solidification of the magnetic material.

13. The method of any one of claims 9 to 12, wherein the plurality of rotor teeth are curvilinear, and wherein at least one of the one or more rotor cavities is defined between a pair of concentric rotor teeth of the plurality of rotor teeth.

14. A method according to any one of claims 9 to 12, wherein the rotor body is formed from a plurality of rotor laminations.

15. The method of claim 14, wherein at least one rotor lamination of the plurality of rotor laminations is rotationally skewed relative to another lamination of the plurality of rotor laminations.

16. The method of any one of claims 9 to 12, wherein the rotor body defines a plurality of rotor poles, and wherein each electromagnetic coil of the plurality of electromagnetic coils is configured to align with a respective rotor pole of the plurality of rotor poles.

17. A controller for manufacturing a rotor for a permanent magnet PM motor, the controller in communication with a mold configured to receive a rotor body, the rotor body including a plurality of rotor teeth and defining one or more rotor cavities, the plurality of electromagnetic coils including a plurality of magnetic cores and a plurality of electromagnetic windings, each magnetic core of the plurality of magnetic cores being configured to align with a corresponding rotor tooth of the plurality of rotor teeth, wherein each electromagnetic winding of the electromagnetic windings is wound around at least one magnetic core of the plurality of magnetic cores, the controller being configured to: After the rotor body is positioned within the mold, closing the mold; after closing the mold, energizing the plurality of electromagnetic coils; injecting a magnetic material into the one or more rotor cavities after energizing the plurality of electromagnetic coils, wherein the energized electromagnetic coils align the magnetic material into a desired magnetic orientation prior to solidification of the magnetic material; and After injecting the magnetic material, the plurality of electromagnetic coils are de-energized.

18. The controller of claim 17, wherein the controller is further configured to open the mold after the curing of the magnetic material.

19. The controller of claim 18, wherein the controller is further configured to cause the mold to be ejected from the rotor body after opening the mold.

20. A controller according to any one of claims 17 to 19, wherein the electromagnetic coil is de-energised after solidification of the magnetic material.

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