High-speed axial air gap motor
By employing a combination of non-conductive materials and thermally conductive encapsulants in the axial air gap motor, the problem of high eddy current losses was solved, achieving low-loss high-speed operation and effective heat dissipation.
Patent Information
- Application Number
- CN202480039240.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-16
- Filing Date
- 2024-06-14
- Publication Date
- 2026-01-09
AI Technical Summary
Existing axial air gap motors suffer from high eddy current losses under high-frequency magnetic fields, resulting in high power consumption and difficulty in effectively dissipating heat at high speeds.
By employing non-conductive materials or non-conductive structural designs, combined with a combination of thermally conductive encapsulants and conductive materials, eddy current losses are reduced while maintaining thermal conductivity. This includes the optimized arrangement of laminated conductive elements, non-conductive housings, and conductive mounting parts.
An axial air gap motor with low loss and high speed operation has been achieved, which effectively dissipates heat and reduces power consumption, while maintaining mechanical strength and thermal conductivity.
Smart Images
Figure CN121312043A_ABST
Abstract
Description
Background Technology
[0001] This invention relates to the field of axial air gap motors (both linear and rotary). Summary of the Invention
[0002] One embodiment relates to an axial air gap motor comprising a rotor and a stator, the rotor having a plurality of permanent magnet portions of a pattern, the stator being disposed near the rotor, and an axial air gap being formed between the stator and the rotor. The stator has a stator housing housing (or including) a set of force generator coils operable to induce motion of the rotor through their magnetic interaction with the rotor. The stator housing has a segmented backplate formed of a plurality of metal segments thermally contacting each other in a non-conductive (or non-electrically conductive) manner to provide heat transfer from the force generator coils to the discrete stator mounting structure, while minimizing eddy currents and associated effects within the stator housing.
[0003] Another embodiment relates to an axial air gap motor comprising a rotor and a stator, the rotor having a plurality of permanent magnet portions of a pattern, the stator being disposed near the rotor, and an axial air gap being formed between the stator and the rotor. The stator has a stator housing housing a set of force generator coils operable to induce motion in the rotor through magnetic interaction with the rotor. The stator housing has a coil housing portion for holding the coils and a separate mounting portion for attaching the stator to a discrete support structure. The coil housing portion is made of a non-conductive (or non-electrically conductive) material that effectively provides heat transfer from the force generator coils to the mounting portion while avoiding eddy currents and associated effects in at least the coil housing portion of the stator housing.
[0004] In some arrangements, the coil housing and mounting portions are separate parts of a monolithic assembly made of non-conductive material.
[0005] In some arrangements, the mounting portion is made of metal to facilitate heat transfer from the stator housing to the discrete support structure.
[0006] In some arrangements, the mounting portion includes an outer wall member made of metallic material that surrounds both the mounting portion and the coil housing portion to provide mechanical strength and thermal conductivity within the stator housing.
[0007] Other embodiments relate to systems, subsystems, devices, components, etc. Some embodiments relate to various methods, components, devices, platforms, etc., that include a high-speed axial air gap motor. Attached Figure Description
[0008] As shown in the accompanying drawings, the following description, foregoing, and other objects, features, and advantages of the present invention, based on specific embodiments, will become apparent, in which the same reference numerals refer to the same parts in different views.
[0009] Figure 1 (Category 1) A three-dimensional view of the laminated back plate force generator adjacent to the permanent magnet track.
[0010] Figure 2 (Category 1) Cross-sectional view of the laminated backing force generator, showing the interface between the laminate, the laminated backing force generator and the non-conductive housing, and the intermediate insulating material.
[0011] Figure 3 (Category 2) A three-dimensional view of a non-electrical conductivity force generator adjacent to the permanent magnet track.
[0012] Figure 4 (Category 2) Cross-sectional view of a non-conductive force generator, showing the single-unit structure.
[0013] Figure 5 (Category 3) Cross-sectional view of the hybrid force generator adjacent to the permanent magnet track (non-conductive housing with conductive mounting blocks).
[0014] Figure 6 (Category 3) Cross-sectional view of a hybrid force generator, showing the interface between a conductive housing and a non-conductive housing.
[0015] Figure 7 (Category 4) A perspective view of a hybrid force generator (conductive body with a non-conductive backplate), showing the interface between the conductive shell and the non-conductive shell.
[0016] Figure 8 (Category 4) Cross-sectional view of a hybrid force generator, showing the interface between a conductive housing and a non-conductive housing. Detailed Implementation
[0017] Overview
[0018] Typically, high-pole, slotless, and iron-free axial air-gap motors operate at currents high enough to require a heat sink to conduct heat away from the motor windings and limit winding temperature. The frame for the coils serves as the housing and also conducts heat from the coils to discrete heat sinks. In the presence of a high-frequency magnetic field, the conductive housing acts as a generator of eddy current losses. It is necessary to achieve a desired balance between eddy current reduction and sufficient heat conduction to allow copper losses to reach the heat sink, while ensuring a mechanically robust stator housing that meets thermal requirements.
[0019] Some embodiments relate to an axial air gap motor in which a high-speed, high-pole-number solution includes features that provide operation with lower power consumption due to reduced losses. This device differs from known motors, which are characterized by relatively high power consumption under similar operating conditions. The disclosed method enables the operation of a high-speed (high surface feet per minute) axial air gap motor with lower losses, while also providing heat removal (by conduction or radiation) from the coil assembly (also known as the force generator or stator). The method focuses on the use of coil assembly-specific materials and techniques, including non-conductive structures, thermally conductive encapsulants, and / or potentially laminated or non-laminated conductive materials.
[0020] The specific arrangements, configurations, or constructions disclosed herein, as well as the various individual features of the embodiments, can be combined in any desired manner to create technical significance. Furthermore, unless such combinations, variations, and / or arrangements have been explicitly excluded or impractical, such features are thus combined in this way to form all possible combinations, variations, and arrangements. Support for such combinations, variations, and arrangements is assumed to exist in this document.
[0021] An embodiment is described in which aspects of the coil assembly of an axial motor (also referred to herein as a "force generator") are manufactured and / or arranged in a manner that provides the desired reduction of eddy currents while maintaining thermal conductivity for heat removal. The coils may be complete complements to engage the rotor with 360 degrees of mechanical engagement, or they may be a set or more of reduced numbers of coils that engage only one or more finite angular segments of the rotor.
[0022] The following describes four different types or categories of embodiments. Category 1 employs a conductive force generator with a segmented arrangement to reduce eddy current losses, while Categories 2 to 4 have at least partially non-conductive structures:
[0023] Category 1 - Segmented (e.g., laminated) conductive elements in the structural composition of the force generator to reduce eddy currents while maintaining thermal conductivity (to minimize eddy current losses).
[0024] Category 2 - Remove all conductive components (to minimize eddy current losses);
[0025] Category 3 - Remove conductive elements near the permanent magnet (to minimize eddy current losses) and keep conductive elements away from the permanent magnet for structural and heat transfer purposes;
[0026] Category 4- Remove conductive elements outside the main wall of the force generator housing near the permanent magnet (to minimize eddy current losses) for structural and heat transfer purposes.
[0027] Example
[0028] Category 1 - Modified conductive elements
[0029] Category 1 includes conductive elements (with a laminated backing plate of intermediate dielectric material) modified inside the electromagnetic path from the electromagnet to the permanent magnet (immediately adjacent to the permanent magnet). The force generator housing material is constructed of non-conductive material, conductive plate, insulating plate, or any combination of these three.
[0030] Figure 1 and Figure 2 An exemplary embodiment of a specific form of a linear arcuate (LARC) motor is shown, having a stator 10 and a circular rotor 12 that rotates about a central axis 14 in response to forces generated by interaction with the stator 10. The stator 10 is arranged in a close axially spaced relationship with the rotor 12. The stator 10 includes a housing 16 that includes one or more coils 18 connected to an external circuit (not shown) that provides current to the coils to generate a magnetic field that interacts with the permanent magnets of the rotor 12 to generate a force that causes its rotational motion. Examples of the arrangement of the rotor's permanent magnets are shown in other examples below. In the illustrated embodiment, the housing 16 has a generally solid cuboid shape, although it has arcuate inner surfaces to accommodate the shape of a rotating member (not shown), to which the rotor 12 is attached in use.
[0031] The stator housing 16 includes a segmented planar metal backplate 20. Each segment (or plate) 22 is conductive due to its metallic material but has little flux-carrying capacity. The plates 22 are preferably in good thermal contact with each other, but not in electrical contact. Thermally, the backplate 20 thus conducts heat from the internal coils 18 to a discrete heat dissipation structure to which the stator 10 is mounted during use. Electrically, the segmentation of the backplate 20 reduces its ability to carry eddy currents generated by a strong magnetic field during use, thereby minimizing associated eddy current losses (which manifest as additional heating). The plates 22 can be arranged with non-conductive gaps between them (e.g., using discrete insulating materials), or the plates 22 themselves can be coated with a slightly insulating surface or otherwise treated to have an electrically insulating surface (e.g., anodizing of an aluminum plate) and placed in close contact with each other for optimal conductive heat dissipation. The plates 22 can be electrically interconnected with a low-frequency conductor for safety grounding.
[0032] The plates 22 are preferably positioned directly above the magnet channel or rotor magnetic field, and they may overlap with the magnetic field source in any direction. In an alternative arrangement, both the housing 10 and the plates 22 are rounded (i.e., arcuate) to conform to the rotor profile, rather than being substantially rectangular as shown. While in the illustrated embodiment, the back plate 20 has four tangentially extending and radially discrete plates 22, alternative embodiments may employ more or fewer plates and / or different segmentation patterns, including, for example, one where the plates extend radially and are tangentially discrete.
[0033] Category 2 - No conductive elements inside or outside the electromagnetic path
[0034] Category 2 does not include conductive elements (immediately adjacent to the permanent magnet) on the inside or outside of the electromagnetic path from the electromagnet to the permanent magnet (non-conductive, non-magnetic coil holders in both the coil holder and the mounting area).
[0035] Figure 3 and Figure 4 An example embodiment is shown, which has the same characteristics as... Figure 1 and Figure 2 The stator 20 and rotor 22 are arranged similarly. In this case, the stator 20 has a housing made of non-conductive material, formed by an integral component 26. Figure 3 The alternating magnetic regions 28 and 30 of the rotor 22 are shown, which establish a magnetic mode that interacts with the magnetic field of the stator 20.
[0036] The stator housing has a coil housing portion 32 for holding the coil (not shown) and a discrete mounting portion 34 for attaching the stator 20 to a discrete support structure (not shown). Component 26 is preferably made of a non-conductive material that effectively provides heat transfer from the force generator coil to the discrete support structure while avoiding eddy currents and associated effects due to its non-conductive material construction.
[0037] Category 3 - No conductive elements inside the electromagnetic path
[0038] Category 3 does not include conductive elements inside the electromagnetic path from the electromagnet to the permanent magnet (immediately adjacent to the permanent magnet), but does include conductive elements outside the electromagnetic path (e.g., the area of a fully plastic coil holder fixed to an aluminum mounting block).
[0039] Figure 5 and Figure 6 An exemplary embodiment is shown, which has the same characteristics as... Figures 1 to 2 and Figures 3 to 4A similar arrangement exists for the stator 40 and rotor 42. In this case, the stator 40 has a housing 46 formed of two different materials. The coil housing portion 48 is preferably made of a non-conductive material (similar to the non-conductive material of the integral component 26), which effectively provides heat transfer from the force generator coil to the mounting portion 50 while avoiding eddy currents and associated effects due to its non-conductive material construction. Meanwhile, the mounting portion 50 is preferably made of a metallic material to improve heat conduction to the discrete support structure. Although this arrangement may have non-zero eddy currents due to the metallic construction of the mounting portion 50, these eddy currents are minimized by both the narrow shape of the mounting portion and its location away from the coil and high field strength regions.
[0040] Category 4 - Selected conductive elements inside the electromagnetic path
[0041] Category 4 includes conductive elements located inside the electromagnetic path from the electromagnet to the permanent magnet (immediately adjacent to the permanent magnet). The main body wall of the force generator housing can be made of thermally and electrically conductive materials without segmented plates (e.g., aluminum or other non-flux-bearing materials). The force generator coil is mechanically secured with a non-conductive encapsulant, or equivalently, secured to a non-conductive plate.
[0042] Figure 7 and Figure 8 An example embodiment is shown, which has the same characteristics as... Figures 1 to 2 , Figures 3 to 4 ,as well as Figures 5 to 6 A similar arrangement exists for the stator 60 and rotor 62. In this case, the stator 60 has a housing 66 formed of two different materials. A portion of the coil housing portion 68 and / or the mounting portion 70 is preferably made of a non-conductive material (e.g., similar to the integral member 26), effectively providing heat transfer from the force generator coil to the discrete support structure while avoiding eddy currents and associated effects due to its non-conductive material construction. Additionally, at least one main wall of the housing 66 is preferably made of a metallic material to improve mechanical strength and heat conduction to the discrete support structure. While this arrangement may have non-zero eddy currents due to one or more body walls being constructed of metal, these eddy currents are minimized by their location away from the coil and in high-field regions and / or other geometric features, as explained above in conjunction with other embodiments.
[0043] In some arrangements, the coil housing portion 68 is non-metallic, except for one or more main walls in the housing 66. Here, the mounting portion 70 may include a conductive material extending into the coil housing portion 68 (e.g., an extension of the main wall). Accordingly, the mounting portion 70 may be made of a metallic material to facilitate heat transfer from the stator housing to the discrete support structure. In particular, the mounting portion 70 may include an outer wall member made of a metallic material that extends across (or even around) both the mounting portion 70 and the coil housing portion 68 to provide mechanical strength and thermal conductivity within the stator housing 66.
[0044] It should be understood that the terms "electrically non-conductive" and "non-electrically conductive" can refer to materials that restrict the flow of electric current. However, it should be understood that such materials can still conduct electricity in other ways. Accordingly, various electrically insulating materials still offer high thermal conductivity (e.g., the ability to move heat quickly and efficiently). Furthermore, such materials can offer other advantages such as reasonable structural / mechanical strength, high durability, and low thermal expansion.
[0045] While various embodiments of the invention have been specifically shown and described, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims. Such modifications and enhancements are intended to be part of the various embodiments of this disclosure.
Claims
1. An axial air gap motor, comprising: A rotor having multiple permanent magnet sections in one pattern; as well as A stator is disposed near the rotor, with an axial air gap between the rotor and the stator. The stator has a stator housing that houses a set of force generator coils capable of operating to induce rotor motion through magnetic interaction with the rotor. The stator housing has a segmented backplate formed of multiple metal segments that are thermally contacted in a non-conductive manner to provide heat transfer from the force generator coils to the discrete stator mounting structure, while minimizing eddy currents and associated effects in the stator housing.
2. An axial air gap motor, comprising: A rotor having multiple permanent magnet sections in one pattern; as well as A stator is disposed near the rotor, with an axial air gap between the stator and the rotor. The stator has a stator housing that houses a set of force generator coils capable of operating to induce rotor motion through magnetic interaction with the rotor. The stator housing has coil housing portions for holding the coils and different mounting portions for attaching the stator to discrete support structures. The coil housing portions are made of a non-conductive material that effectively provides heat transfer from the force generator coils to the mounting portions while avoiding eddy currents and associated effects in at least the coil housing portions of the stator housing.
3. The axial air gap motor of claim 2, wherein the coil housing portion and the mounting portion are separate parts of an integral component made of the non-conductive material.
4. The axial air gap motor of claim 2, wherein the mounting portion is made of a metallic material to facilitate heat transfer from the stator housing to the discrete support structure.
5. The axial air gap motor of claim 4, wherein the mounting portion includes an outer wall member made of a metallic material surrounding both the mounting portion and the coil housing portion to provide mechanical strength and thermal conductivity within the stator housing.