Method for determining magnetic orientation of injection molded permanent magnets

Abstract

To provide a method for monitoring the magnetic orientation of a composite magnetic material injected into a rotor pole of a rotor core.SOLUTION: A rotor pole is defined by at least one rotor cavity. A method includes injecting a magnetic composite material into the at least one rotor cavity defining the rotor poles and applying an external magnetic field to the rotor pole to magnetically orient the magnetic composite material during injection into the at least one rotor cavity.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] The field of this disclosure relates generally to measuring characteristics of permanent magnet (PM) synchronous reluctance machine (PMSynRM) rotors, and more particularly to systems and methods for determining the magnetic orientation of permanent magnets installed in a PMSynRM rotor.

[0002]

[0002] Permanent magnet (PM) synchronous reluctance machines (PMSynRM) can utilize polymer-bonded magnets (PBM) in their construction. When sintered magnets are utilized in PMSynRM, the individual components are pre-oriented during manufacturing and shipped to the customer (e.g., motor manufacturer) for final assembly and magnetization.

[0003]

[0003] In a molded PMSynRM rotor, the filling of the PBM into the rotor cavity is completed using a suitable molding process. During the manufacture of a PMSynRM rotor, a laminated rotor having a cavity is placed into a mold cavity. Material containing the PBM is injected into the cavity through a runner and gating system. The magnetic field generated by the PBM depends on the magnetic orientation of the permanent magnets. As a result, the manufactured rotor may exhibit magnetic fields with inconsistent magnitudes that are formed during the injection process and after the rotor cools.

[0004]

[0004] Therefore, there is a need to monitor the magnetic field generated by the PBM during and after the injection process so that manufacturing yields can be improved. Summary of the Invention

[0005] In one aspect of the present disclosure, a method for monitoring the magnetic orientation of rotor poles of a rotor core disposed within an injection mold, the rotor poles being defined by at least one rotor cavity, includes injecting a magnetic composite material into the at least one rotor cavity defining the rotor poles, and applying an external magnetic field to the rotor poles to magnetically orient the magnetic composite material injected into the at least one rotor cavity.

[0006] In another aspect of the present disclosure, a method for determining a magnetic field orientation of a rotor pole of a rotor core is disclosed. The rotor pole is defined by at least one rotor cavity filled with a magnetic composite material. The method includes measuring a magnetic field magnitude of the rotor pole generated by the magnetic composite material and evaluating the magnetic field magnitude of the rotor pole relative to at least one of a first magnetic field magnitude threshold and a second magnetic field magnitude threshold, the first magnetic field magnitude threshold corresponding to a first known magnetic field orientation and the second magnetic field magnitude threshold corresponding to the second magnetic field orientation. [Brief explanation of the drawings]

[0007]

[0007] The subject matter of the present disclosure will be described in more detail in the following text with reference to exemplary embodiments illustrated in the accompanying drawings. [Figure 1]

[0008] Figure 1 is a top view of the PMSynRM. [Figure 2]

[0009] FIG. 2 shows a cross-sectional side view of the rotor core taken along line AA shown in FIG. [Figure 3A]

[0010] FIG. 3A shows a detailed view of Detail A shown in FIG. 1 of an isotropic magnet with substantially randomized easy axes. [Figure 3B]

[0011] FIG. 3B shows a detailed view of Detail A shown in FIG. 1 of an anisotropic magnet with substantially parallel easy axes of magnetization. [Figure 4]

[0012] FIG. 4 illustrates a top view of a system for monitoring the magnetic orientation of at least one rotor pole of a rotor core disposed within an injection mold. [Figure 5]

[0013] FIG. 5 illustrates a side view of the system shown in FIG. 4 for monitoring the magnetic orientation of at least one rotor pole of a rotor core disposed within an injection mold. [Figure 6]

[0014] FIG. 6 illustrates a method for monitoring the magnetic orientation of at least one rotor pole of a rotor core disposed within an injection mold. [Figure 7]

[0015] FIG. 7 illustrates a side view of a system for determining the magnetic field orientation of at least one rotor pole of a rotor core. [Figure 8]

[0016] FIG. 8 illustrates a method for determining the magnetic field orientation of at least one rotor pole of a rotor core. [Figure 9]

[0017] FIG. 9 illustrates a system for determining the degree of magnetic orientation of a magnetic composite material injected into a rotor core of a motor assembly. [Figure 10]

[0018] FIG. 10 illustrates a method for determining the degree of magnetic orientation of a magnetic composite material injected into a rotor core of a motor assembly.

[0008]

[0019] The reference signs used in the drawings and their meanings are listed in summary form in the list of reference signs. As a rule, identical parts in the figures are given the same reference signs. DETAILED DESCRIPTION OF THE INVENTION

[0009]

[0020] In the following specification and claims, reference will be made to a number of terms, which shall be defined to have the following meanings.

[0010]

[0021] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs or does not occur.

[0011]

[0022] Unless otherwise indicated, approximating language such as "generally," "substantially," and "about" used herein indicates that the modified term may apply only to an approximate degree, as recognized by one of ordinary skill in the art, rather than to an absolute or complete degree. Thus, a value modified by one or more terms, such as "about," "approximately," and "substantially," should not be limited to the exact value specified. In at least some cases, approximating language may correspond to the precision of an instrument for measuring the value. Range limitations may be specified here and throughout this specification and claims. Such ranges may be combined and / or interchangeable, and include all subranges contained therein, unless the context or language indicates otherwise.

[0012]

[0023] Furthermore, unless otherwise indicated, the terms "first," "second," etc. are used herein merely as labels, and are not intended to impose any order, position, or hierarchical requirements on the items to which these terms refer. Furthermore, a reference to, for example, a "second" item does not require or exclude the presence of, for example, a "first" or lower-numbered item, or a "third" or higher-numbered item.

[0013]

[0024] In summary, embodiments of the present disclosure relate to a method for monitoring the magnetic orientation of a composite magnetic material injected into rotor poles of a rotor core, the rotor poles being defined by at least one rotor cavity, the method including injecting a magnetic composite material into the at least one rotor cavity defining the rotor poles, and applying an external magnetic field to the rotor poles to magnetically orient the magnetic composite material injected into the at least one rotor cavity.

[0014]

[0025] In some embodiments, a method is for determining a magnetic field orientation of a rotor pole of a rotor core, the rotor pole being defined by at least one rotor cavity filled with a magnetic composite material. The method includes measuring a magnetic field magnitude of the rotor pole generated by the magnetic composite material and evaluating the magnetic field magnitude of the rotor pole relative to at least one of a first magnetic field magnitude threshold and a second magnetic field magnitude threshold, the first magnetic field magnitude threshold corresponding to a first known magnetic field orientation and the second magnetic field magnitude threshold corresponding to the second magnetic field orientation.

[0015]

[0026] FIG. 1 shows a top view of rotor core 100, and FIG. 2 shows a cross-sectional side view of rotor core 100 taken along line AA shown in FIG. 1. Rotor core 100 is a component of a motor assembly that includes a rotor shaft, a rotor, and a stator (not shown). In the exemplary embodiment, rotor core 100 is a permanent magnet synchronous reluctance machine (PMSynRM) rotor core. In the embodiment shown in FIG. 1, rotor core 100 includes a cylindrical body 102, hereafter referred to as rotor stack 102. In some embodiments, rotor stack 102 is made up of two or more cylindrical bodies.

[0016]

[0027] As used herein, the term "electric motor" refers to an electric machine that converts electrical energy into mechanical energy. Electric motors operate through the interaction of magnetic fields formed in the wire windings of a stator and integrated magnets in a rotor, generating a force in the form of torque that is applied to the rotor shaft. Generators convert mechanical energy into electrical energy. Components that generally include a stator, rotor, conductors, and housing may be found in both generators and motors. Thus, because generators and motors are similar in their operation and mechanical aspects, it should be understood that the mechanical aspects of electric motors described herein also describe generators, and the term "electric motor" also includes generators.

[0017]

[0028] As shown in FIGS. 1 and 2 , the rotor stack 102 includes a top surface 104 and a bottom surface 106. The rotor stack 102 has a central longitudinal axis A extending along the length of the rotor stack 102 defined between the top surface 104 and the bottom surface 106. A centrally located shaft bore 108 extends longitudinally along the central longitudinal axis A of the rotor stack 102. The shaft bore 108 of the rotor stack 102 is adapted to receive a rotor shaft therethrough. The rotor shaft may be secured to the rotor stack 102 by a friction fit, welding, or adhesive, or by the use of a key that may be inserted into one or more keyways located on the inner surface of the shaft bore 108. In some embodiments, the rotor shaft may be secured to the rotor stack 102 by a c-clip.

[0018]

[0029] The rotor stack 102 includes at least two rotor poles 110. This embodiment of the disclosure includes four rotor poles 110a, 110b, 110c, and 110d. Each of the rotor poles 110a-d includes at least one rotor stack cavity 112. In this disclosure, each rotor pole 110a-d includes three rotor stack cavities 112. Each rotor stack cavity 112 extends longitudinally through the rotor stack 102 (e.g., extends parallel to the central longitudinal axis A). As shown in FIG. 1 for illustrative purposes, the top surface 104 of the rotor stack 102 is illustratively divided into four sections (P1, P2, P3, P4) that comprise approximately 90 degrees of the circular rotor stack 102. Each rotor pole 110a, 110b, 110c, and 110d is located in a respective section P1, P2, P3, and P4. The rotor core 100 described herein, including four rotor poles 110, is an exemplary configuration, and the number of rotor poles 110 shown is not intended to be limiting. The rotor core 100 may have any number of rotor poles 110, and the rotor top surface 104 may illustratively be divided such that each of the rotor poles 110 (and multiple rotor stack cavities 112) is symmetrically oriented about the central longitudinal axis A. Similarly, the number of rotor stack cavities 112 shown is an example configuration (eg, the number of rotor stack cavities 112 for each rotor pole 110) and is not intended to be limiting.

[0019]

[0030] The plurality of rotor stack cavities 112 may be filled with a magnetic composite material 120 . In some embodiments, the magnetic composite material 120 is in a molten state. In other embodiments, the magnetic composite material 120 is in a solidified state (at room temperature). The magnetic composite material 120 may be magnetizable. In some embodiments, the magnetic composite material 120 is magnetizable during an injection process in which a magnetic field is applied to the magnetic composite material 120 as it is injected into the plurality of rotor stack cavities 112. As shown in FIGS. 1 and 2 , a magnetic field 122 is generated by the magnetic composite material 120, and the orientation of the magnetic field 122 is indicated by dashed lines and / or arrows. The orientation of the magnetic field 122 as illustrated is merely exemplary and not intended to be limiting.

[0020]

[0031] The performance of a rotor and / or motor is generally proportional to the orientation and magnitude of the magnetic field 122 generated by the magnetic composite material 120. The orientation of the magnetic field 122 is characterized by the magnetic anisotropy of the solid-state magnetic composite material 120. The orientation of the magnetic composite material 120 and the magnetic field 122 can be defined by the distribution of magnetic easy axes. An isotropic magnetic material is defined by substantially randomized magnetic easy axes, while an anisotropic magnetic material is defined by substantially parallel magnetic easy axes. As an example, FIG. 3A shows a detailed view of Detail A as shown in FIG. 1 of an isotropic magnet with substantially randomized magnetic easy axes. FIG. 3B shows a detailed view of Detail A as shown in FIG. 1 of an anisotropic magnet with substantially parallel magnetic easy axes. The θ (degree of crystallographic orientation) value of an isotropic magnetic material is approximately 0.50, while the θ value of an anisotropic magnetic material is approximately 1.00. Anisotropic magnetic materials generate stronger magnetic fields relative to partially isotropic magnetic materials and relative to fully isotropic magnetic materials.

[0021]

[0032] FIG. 4 shows a top view of a system 200 for monitoring the magnetic orientation of at least one rotor pole 110 of a rotor core 100 disposed within an injection mold 210. FIG. 5 shows a side view of the system 200. As shown in FIGS. 4 and 5, the injection mold 210 includes a mold body 212 having a cavity 214 in which the rotor core 100 is disposed. A distribution plate 220 (shown in FIG. 5) includes an injection channel 222 to facilitate filling the rotor stack cavity 112 with the molten composite material 120. The system 200 includes a plurality of sensors 230 disposed within the injection mold 210 to measure the magnitude of the magnetic field of the rotor pole 110 generated by the magnetic composite material 120. Each sensor 230 is positioned proximate the mold body 212 for the respective rotor pole 110 at a location corresponding to the rotor pole 110. In some embodiments, the sensors 230 are Hall effect sensors and / or current sensors. System 200 also includes conductive coils 240 external to mold body 212 to facilitate straightening magnetic composite material 120 as it is injected into rotor stack cavity 112. The external magnetic field generated by each conductive coil 240 is oriented perpendicular to the respective rotor pole 110.

[0022]

[0033] In operation, as the magnetic composite material 120 is injected through the injection channel 222 of the distribution plate 220, a current is passed through the conductive coil 240 to straighten and align the magnetic orientation of the magnetic composite material 120. Simultaneously, the sensor 230 measures the magnetic flux of the magnetic composite material 120 while it is melting and as it solidifies. Thus, measurements are taken during the injection process.

[0023]

[0034] The magnetic flux measurements are evaluated against known magnetic flux measurements from a control rotor core (not shown). The control rotor core has the same geometry, mechanical properties, and material properties as rotor core 100. The control rotor core also has the same magnetic composite material injected into the cavities of the control rotor core by the same process. Because the magnetic flux measurements are temperature dependent, the known magnetic flux measurements also have a corresponding known rotor core temperature.

[0024]

[0035] 6 illustrates a method 300 for monitoring the magnetic orientation of at least one rotor pole of a rotor core disposed within an injection mold, such as rotor pole 110 of rotor core 100 disposed within injection mold 210. Method 300 includes positioning a sensor on the injection mold for each of the at least one rotor pole at a location corresponding to the at least one rotor pole 302 and injecting a magnetic material into at least one rotor cavity defining the at least one rotor pole 304. Method 300 also includes applying an external magnetic field to each of the at least one rotor pole 306 to magnetically orient the magnetic material injected into the at least one rotor cavity defining the at least one rotor pole 306 and measuring a magnitude of the rotor pole's magnetic field generated by the magnetic material 308. Method 300 further includes measuring a magnitude of the rotor pole's magnetic field 310 and comparing a magnitude of the rotor pole's magnetic field to a magnetic field magnitude threshold 312.

[0025]

[0036] FIG. 7 shows a side view of a system 400 for determining the magnetic field orientation of at least one rotor pole 110 of a rotor core 100. Unlike the systems and methods described in FIGS. 4-6, in FIG. 7, the injection process has been completed and the magnetic composite material 120 has solidified. Similar to the system 200 shown in FIGS. 4 and 5, multiple sensors 430 are disposed on the rotor core 100 to measure the magnitude of the magnetic field of the rotor pole 110 generated by the magnetic composite material 120. A sensor 430 is positioned on the mold body 212 for each of the rotor poles 110 at a location corresponding to the rotor pole 110. In some embodiments, the sensor 430 is a Hall effect sensor, a current sensor, and / or a Gaussian sensor.

[0026]

[0037] The magnetic flux measurements are evaluated against known magnetic flux measurements from a control rotor core (not shown). The control rotor core has the same geometry, mechanical properties, and material properties as rotor core 100. The control rotor core also has the same magnetic composite material injected into the cavity of the control rotor core by the same process. Because the magnetic flux measurements are temperature dependent, the known magnetic flux measurements also have a corresponding known temperature. In some embodiments, the range of known magnetic flux measurements of the control rotor core corresponds to a range of temperatures.

[0027]

[0038] The measured magnetic field magnitude is evaluated against an upper and lower threshold, the upper threshold corresponding to an anisotropic magnetic material defined by substantially parallel easy axes, and the lower threshold corresponding to an isotropic magnetic material defined by substantially randomized easy axes. As previously mentioned, the crystalline orientation value θ for an isotropic magnetic material is approximately 0.50, and the crystalline orientation value θ for an anisotropic magnetic material is approximately 1.00.

[0028]

[0039] 8 illustrates a method 500 for determining a magnetic field orientation of at least one rotor pole of a rotor core, such as rotor pole 110 of rotor core 100. Method 500 includes measuring 502 a magnitude of a magnetic field of the rotor pole generated by a magnetic material. Method 500 further includes evaluating 504 a magnitude of the magnetic field of the rotor pole relative to at least one of a first control magnetic field magnitude value and a second control magnetic field magnitude value. The first control magnetic field magnitude value and the second control magnetic field magnitude value each correspond to a first magnetic field orientation and a second magnetic field orientation, respectively.

[0029]

[0040] As described above, the magnetic material has at least one of a material composition and a temperature. The first and second control magnetic field magnitude values ​​are generated by a control magnetic material having the same material composition and temperature as the magnetic material. The magnitude of the magnetic field of the rotor pole generated by the magnetic material is proportional to half the θ value. The first magnetic field orientation is a substantially isotropic magnetic material orientation having a θ value of approximately 0.5, and the second magnetic field orientation is a substantially anisotropic magnetic material orientation having a θ value of approximately 1.

[0030]

[0041] The method 500 further includes, for each of the at least one rotor pole, positioning 506 a sensor on the outer surface of the rotor core at a location corresponding to the respective rotor pole.

[0031]

[0042] FIG. 9 shows a system 600 for determining the degree of magnetic orientation of a magnetic composite material injected into a rotor core 100 assembled into a motor assembly 610. A rotor shaft 620 is fixed to the rotor core 100, which is disposed within a stator 630. A back EMF voltage sensor 640 is connected to the motor assembly 610, and the stator is energized to rotate the rotor 100 around the rotor shaft 620. The rotor shaft 620 is rotated at a known minimum speed so that the back EMF voltage can be measured. The measured back EMF voltage can be evaluated against a back EMF voltage threshold of a control motor assembly (not shown) having the same specifications as the motor assembly 610 and rotor core 100. The magnitude of the back EMF voltage of the motor assembly 610 is proportional to the degree of magnetic orientation of the magnetic composite material injected into the rotor core 100.

[0032]

[0043] FIG. 10 illustrates a method 700 for determining the degree of magnetic orientation of a magnetic composite material injected into a rotor core of a motor assembly, such as rotor core 100 of motor assembly 610. The method includes rotating 702 the rotor core at a minimum rotational speed and measuring 704 a magnitude of a back EMF voltage of the motor assembly. Method 700 further includes evaluating 706 the magnitude of the back EMF voltage against a back EMF voltage threshold. The back EMF voltage threshold is a back EMF voltage threshold of a control motor assembly having a control rotor core, rotor shaft, and control stator assembly that is the same as motor assembly 610. The magnitude of the back EMF voltage of the motor assembly is proportional to the degree of magnetic orientation of the magnetic composite material injected into the rotor core.

[0033]

[0044] Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Moreover, references to "one embodiment" in the above description are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. In accordance with the principles of the present disclosure, any feature of a drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0034]

[0045] This specification uses examples, including the best mode, to enable any person skilled in the art to practice the present disclosure, including making and using any device or system, and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to 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 have insubstantial differences from the literal language of the claims. The inventions described in the original claims of this application are set forth below. [1] A method for monitoring magnetic orientation of a composite magnetic material injected into a rotor pole of a rotor core, the rotor pole being defined by at least one rotor cavity, the method comprising: injecting a magnetic composite material into the at least one rotor cavity defining the rotor pole; and applying an external magnetic field to the rotor poles to magnetically orient the magnetic composite material during injection into the at least one rotor cavity. [2] The method of [1], further comprising measuring the magnitude of the magnetic field of the rotor pole generated by the magnetic composite material. [3] The method of [2], further comprising evaluating the magnetic field magnitude of the rotor poles against a magnetic field magnitude threshold. [4] The method according to [3], wherein the magnetic composite material has at least one of a material composition and a temperature, and the magnitude of the magnetic field depends on at least one of the material composition and the temperature. [5] The method of [4], wherein the threshold magnitude of the magnetic field is generated by a control material, the control material and the magnetic composite material having a common material composition and temperature, and wherein the control material is injected into at least one control rotor cavity that defines a control rotor pole of a control rotor core. [6] The method described in [5], wherein each of the at least one rotor cavity and the at least one control rotor has at least one of a common volume, surface shape, and orientation, and the orientation of the at least one rotor cavity is defined on the top surface of the control rotor core. [7] The method according to [3], wherein the control rotor core comprises a plurality of rotor poles, and the magnitude of the magnetic field of each of the plurality of rotor poles is evaluated. [8] The method according to [3], wherein the magnitude of the magnetic field in the rotor pole is proportional to the magnetic orientation of the magnetic composite material within the rotor pole. [9] The method of [8], wherein the ratio of the magnitude of the magnetic field in the rotor pole to the magnetic orientation of the magnetic composite material within the rotor pole is about 0.5 for a substantially isotropic composite material.

[10] The method of [8], wherein the ratio of the magnitude of the magnetic field in the rotor pole to the magnetic orientation of the magnetic composite material within the rotor pole is about 1 for a substantially anisotropic composite material.

[11] The method according to [2], wherein the magnitude of the magnetic field of the rotor pole generated by the magnetic composite material is measured by a sensor, the sensor being positioned near the rotor pole.

[12] The method according to

[11] , wherein the sensor is a Hall effect sensor.

[13] The method of [3], further comprising measuring at least one of the amplitude and polarity of the magnetic field generated by the magnetic composite.

[14] A method for determining a magnetic field orientation of a rotor pole of a rotor core, the rotor pole being defined by at least one rotor cavity filled with a magnetic composite material, the method comprising: measuring the magnitude of the rotor pole magnetic field generated by the magnetic composite; evaluating a rotor pole magnetic field magnitude against at least one of a first magnetic field magnitude threshold and a second magnetic field magnitude threshold, the first magnetic field magnitude threshold corresponding to a first known magnetic field orientation and the second magnetic field magnitude threshold corresponding to a second magnetic field orientation.

[15] The method of

[14] , wherein each of the first magnetic field magnitude threshold and the second magnetic field magnitude threshold is generated by a control material, the control material and the magnetic composite material having a common material composition and temperature, and the control material is injected into at least one control rotor cavity defining a control rotor pole of a control rotor core.

[16] The method according to

[15] , wherein each of the at least one rotor cavity and the at least one control rotor has at least one of a common volume, a common surface shape, and a common orientation, the common orientation being defined along a top surface of the control rotor core.

[17] The method of

[16] , wherein the magnitude of the magnetic field in the rotor pole is proportional to the magnetic orientation of the magnetic composite material within the rotor pole.

[18] The method of

[17] , wherein the ratio of the magnitude of the magnetic field in the rotor pole to the magnetic orientation of the magnetic composite material within the rotor pole is about 0.5 for a substantially isotropic composite material.

[19] The method of

[17] , wherein the ratio of the magnitude of the magnetic field in the rotor pole to the magnetic orientation of the magnetic composite material within the rotor pole is about 1 for a substantially anisotropic composite material.

[20] The method further comprises determining a degree of magnetic orientation of a magnetic composite material injected into a rotor core as part of a motor assembly, the motor assembly including at least a rotor shaft and a stator assembly, and determining a degree of magnetic orientation of the magnetic composite material injected into the rotor core includes: rotating the rotor core at a minimum rotational speed; measuring a magnitude of a back-EMF voltage of the motor assembly; evaluating the magnitude of the back EMF voltage against a back EMF voltage threshold, the back EMF voltage threshold being a back EMF voltage threshold for a control motor assembly having a control rotor core, a rotor shaft, and a control stator assembly;

[14] The method according to

[14] , wherein the magnitude of the back electromotive force voltage of the motor assembly is proportional to the degree of magnetic orientation of the magnetic composite material injected into the rotor core.

Claims

1. 1. A method for monitoring magnetic orientation of a composite magnetic material injected into a rotor pole of a rotor core, the rotor pole being defined by at least one rotor cavity, the method comprising: injecting a magnetic composite material into the at least one rotor cavity defining the rotor pole; applying an external magnetic field to the rotor poles to magnetically orient the magnetic composite material during injection into the at least one rotor cavity; The method further comprises monitoring the magnetic orientation of the injected composite magnetic material by measuring the magnitude of the magnetic field of the rotor pole generated by the magnetic composite material with a sensor positioned near the rotor pole.

2. The method of claim 1 , further comprising evaluating the rotor pole magnetic field magnitude relative to a threshold magnetic field magnitude.

3. The method of claim 2 , wherein a magnitude of the rotor pole magnetic field generated by the magnetic composite material depends on at least one of a material composition and a temperature of the magnetic composite material.

4. 4. The method of claim 3, wherein the threshold magnitude of the magnetic field is generated by a control material comprising a control rotor core, the control material and the magnetic composite material having the same temperature and material composition, the control rotor core having the same shape, mechanical properties, and material properties as the rotor core, and the control material being injected into at least one control rotor cavity that defines a control rotor pole of the control rotor core.

5. 5. The method of claim 4, wherein the at least one rotor cavity and the at least one control rotor cavity have the same volume, surface shape, and orientation in common, and the orientation of the at least one rotor cavity is defined on a top surface of the rotor core.

6. A method described in any one of claims 2 to 5, wherein the rotor core has a plurality of rotor poles and the magnitude of the magnetic field of each of the plurality of rotor poles is evaluated.

7. The method of claim 2 , wherein the magnitude of the magnetic field in the rotor pole is proportional to the magnetic orientation of the magnetic composite material within the rotor pole.

8. 8. The method of claim 7, wherein the ratio of the magnitude of the rotor pole magnetic field to the magnetic orientation of the magnetic composite material within the rotor pole is about 0.5 for a substantially isotropic composite material.

9. 8. The method of claim 7, wherein the ratio of the magnitude of the rotor pole magnetic field to the magnetic orientation of the magnetic composite material within the rotor pole is about 1 for a substantially anisotropic composite material.

10. The method of claim 1 , wherein the sensor is a Hall Effect sensor.

11. The method of claim 2 , further comprising measuring at least one of an amplitude and a polarity of the magnetic field generated by the magnetic composite material.

12. 1. A method for determining a magnetic field orientation of a rotor pole of a rotor core, the rotor pole being defined by at least one rotor cavity filled with a magnetic composite material, the method comprising: measuring the magnitude of the magnetic field of the rotor pole generated by the magnetic composite with a sensor positioned near the rotor pole; evaluating a rotor pole magnetic field magnitude against at least one of a first magnetic field magnitude threshold and a second magnetic field magnitude threshold, wherein the first magnetic field magnitude threshold corresponds to a magnetic field orientation of an isotropic magnetic material and the second magnetic field magnitude threshold corresponds to a magnetic field orientation of an anisotropic magnetic material.

13. 13. The method of claim 12, wherein each of the first magnetic field magnitude threshold and the second magnetic field magnitude threshold is generated by a control material comprising a control rotor core, the control material and the magnetic composite material having a common material composition and temperature, wherein the control rotor core has the same shape, mechanical properties, and material properties as the rotor core, and the control material is injected into at least one control rotor cavity defining a control rotor pole of the control rotor core.

14. 14. The method of claim 13, wherein the at least one rotor cavity and the at least one control rotor cavity have the same volume, surface shape, and orientation, the orientation being defined along a top surface of the rotor core.

15. The method of claim 14 , wherein the magnitude of the magnetic field in the rotor pole is proportional to the magnetic orientation of the magnetic composite material within the rotor pole.

16. 16. The method of claim 15, wherein the ratio of the magnitude of the rotor pole magnetic field to the magnetic orientation of the magnetic composite material within the rotor pole is about 0.5 for a substantially isotropic composite material.

17. 16. The method of claim 15, wherein the ratio of the magnitude of the rotor pole magnetic field to the magnetic orientation of the magnetic composite material within the rotor pole is about 1 for a substantially anisotropic composite material.

18. determining a degree of magnetic orientation of a magnetic composite material injected into the rotor core as part of a motor assembly, the motor assembly including at least a rotor shaft and a stator assembly, and determining a degree of magnetic orientation of the magnetic composite material injected into the rotor core includes: rotating the rotor core at a minimum rotational speed; measuring a magnitude of a back-EMF voltage of the motor assembly; evaluating the magnitude of the back EMF voltage against a back EMF voltage threshold, the back EMF voltage threshold being a back EMF voltage threshold for a control motor assembly having a control rotor core, a rotor shaft, and a control stator assembly; 18. The method of claim 12, wherein the magnitude of the back EMF voltage of the motor assembly is proportional to the degree of magnetic orientation of the magnetic composite material injected into the rotor core.

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