CN210225085U - Permanent magnet motor rotor structure for enhancing shielding effect of harmonic magnetic field - Google Patents
Permanent magnet motor rotor structure for enhancing shielding effect of harmonic magnetic field Download PDFInfo
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- CN210225085U CN210225085U CN201921130304.4U CN201921130304U CN210225085U CN 210225085 U CN210225085 U CN 210225085U CN 201921130304 U CN201921130304 U CN 201921130304U CN 210225085 U CN210225085 U CN 210225085U
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- 230000000694 effects Effects 0.000 title claims abstract description 13
- 230000002708 enhancing effect Effects 0.000 title claims abstract description 5
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 13
- 239000010949 copper Substances 0.000 claims description 13
- 229910052802 copper Inorganic materials 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 2
- 229910001069 Ti alloy Inorganic materials 0.000 claims description 2
- 239000004917 carbon fiber Substances 0.000 claims description 2
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 2
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- 230000005347 demagnetization Effects 0.000 description 4
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- 238000003466 welding Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
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- Permanent Field Magnets Of Synchronous Machinery (AREA)
Abstract
The utility model discloses a permanent magnet motor rotor structure for enhancing the shielding effect of a harmonic magnetic field, which comprises a rotating shaft and is characterized in that the surface of the rotating shaft is wrapped with a rotor core, a permanent magnet, a shielding layer and a rotor sheath from inside to outside in sequence; and the two axial ends of the permanent magnet are provided with conductive end covers, and the conductive end covers are fixedly connected with the shielding layer and are tightly attached to the permanent magnet. The structure can effectively reduce the eddy current loss in the permanent magnet and the eddy current loss in the shielding layer, reduce the total eddy current loss of the rotor and improve the operation reliability of the permanent magnet motor.
Description
Technical Field
The utility model belongs to the technical field of the motor, especially, relate to a permanent-magnet machine rotor structure of reinforcing harmonic magnetic field shielding effect.
Background
The motor is an important component in an industrial system, and the motor with excellent performance is important for the industrial system. With the development of power electronics technology, more and more motors are powered by inverters. Since the switching frequency of the inverter is limited by the power electronics, the stator current time harmonics will increase significantly as the motor speed increases and the current fundamental frequency increases. The asynchronous rotation of the magnetic field generated by the stator current time harmonic relative to the rotor can cause the fluctuation of the magnetic field in the rotor, which causes the eddy current and the loss heating of the rotor, and the phenomenon is particularly serious when the motor runs at high speed. In addition, the permanent magnet motor rotor is almost in a closed space, the size is small, the heat dissipation condition is poor, and the eddy current loss of the rotor can cause obvious rotor temperature rise. Rotor overheating easily causes permanent magnet demagnetization and even irreversible demagnetization, so rotor eddy current loss needs to be effectively suppressed.
Research shows that a thin copper layer is wrapped on the outer cylindrical surface of the permanent magnet to shield the harmonic magnetic field of the stator current from penetrating into the inner permanent magnet, so that the structure is called a copper shielding layer. Although a certain eddy current can be induced in the copper shielding layer, the conductivity of copper is very high, so that excessive loss cannot be caused; the induced magnetic field of the copper shielding layer can counteract the fluctuating magnetic field in the rotor, so that the eddy current of the permanent magnet is inhibited, and the total eddy current loss of the rotor is reduced. The surface-mounted permanent magnet motor rotor with the copper shielding layer generally comprises a rotor shaft, an iron core, a permanent magnet, the copper shielding layer and a rotor sheath from inside to outside, and is shown in fig. 1.
Finite element analysis finds that the eddy current in the copper shielding layer is relatively uniform in the axially central part and low in eddy current density, but the eddy current rotating positions at two axial ends are very concentrated, and the eddy current density is very high. The eddy current at the end part of the rotor not only flows through two end surfaces of the copper shielding layer, but also passes through the permanent magnet nearby, and the eddy current loss of the permanent magnet is increased. Therefore, the traditional rotor structure with the shielding layer cannot effectively inhibit the eddy current at the end part of the rotor, and local overheating and demagnetization at the end part of the rotor are easily caused.
SUMMERY OF THE UTILITY MODEL
Based on the above-mentioned problem that prior art exists, the utility model provides a permanent-magnet machine rotor structure of reinforcing harmonic magnetic field shielding effect can effectively reduce the eddy current loss in the permanent magnet and shield the intraformational eddy current loss to reduce the total eddy current loss of rotor, improve permanent-magnet machine's operational reliability.
The technical scheme of the utility model as follows:
a permanent magnet motor rotor structure for enhancing the shielding effect of a harmonic magnetic field comprises a rotating shaft and is characterized in that the surface of the rotating shaft is sequentially wrapped with a rotor core, a permanent magnet, a shielding layer and a rotor sheath from inside to outside; and the two axial ends of the permanent magnet are provided with conductive end covers, the conductive end covers are fixedly connected with the shielding layer, and the conductive end covers are tightly attached to the permanent magnet.
Interference fit is adopted between the rotor iron core and the permanent magnet, between the permanent magnet and the shielding layer and between the shielding layer and the rotor sheath.
The utility model discloses increase two electrically conductive end covers at permanent magnet axial both ends to guide the vortex of rotor tip to the electrically conductive end cover of high conductivity, restrain it and cause permanent magnet eddy current loss to diffusion in the permanent magnet.
The effect of this electrically conductive end cover is different from traditional rotor end clamp plate, and the effect of rotor end clamp plate prevents that the permanent magnet from taking place the displacement along the axial, plays the effect of consolidating the rotor structure. In addition, in order to avoid magnetic field leakage at the end part of the magnetic field generated by the permanent magnet and the stator and additional eddy current loss, the rotor end pressing plate needs to be made of non-magnetic materials, such as aluminum, non-magnetic stainless steel and the like. In addition, for the motor with the permanent magnet having insignificant axial movement, a rotor end pressure plate does not need to be installed.
In the utility model, for the motor with a rotor end pressing plate, the conductive end cover is arranged between the end pressing plate and the permanent magnet; for a motor without a rotor end pressing plate, the conductive end covers are arranged at two ends of the permanent magnet.
The shielding layer is used for shielding the harmonic magnetic field to inhibit eddy current loss and collect heat in the rotor to make the temperature of the rotor uniform, and can be made of copper and other high-conductivity, high-heat-conductivity and non-magnetic materials. The thickness of the shielding layer is not less than the skin depth of the main harmonic magnetic field in the shielding layer.
The conductive end cap requires the use of a material having a high conductivity, typically the same material as the shield layer, such as copper. The thickness of the conductive end cover is not less than that of the shielding layer.
The rotor sheath is used for protecting the permanent magnet, the shielding layer and the conductive end cover in the rotor sheath against centrifugal force, and can be made of carbon fiber, glass fiber, stainless steel, titanium alloy and other high-mechanical-strength and non-magnetic materials.
In the utility model, the inner diameter of the shielding layer is equal to the outer diameter of the permanent magnet, and the shielding layer is tightly attached to the surface of the permanent magnet of the motor rotor during installation; the rotor sheath is in interference fit with the shielding layer, and the shielding layer and the permanent magnet are protected by pretightening force; the conductive end covers are tightly attached to the two end faces of the permanent magnet and fixedly connected with the shielding layers to form good conductive contact.
The conductive end cover can adopt two processing technologies aiming at different rotor structures.
When the motor rotor does not have an end pressing plate, the lengthened shielding layer is turned inwards at the end part by using a flanging process to form a conductive end cover integrated with the shielding layer.
When the motor rotor is provided with the end pressing plate, the conductive end cover is arranged between the rotor end pressing plate and the permanent magnet, and the rotor end pressing plate is used for axial fixation to enable the conductive end cover to be in close contact with the shielding layer. The conductive end cover is manufactured by the following process: the shielding layer is lengthened properly and turned inwards, conductive end covers with steps are added at two ends of the shielding layer, and then the conductive end covers are connected with the shielding layer through laser welding. The shielding layer and the conductive end cover are connected in a melting mode through small-range high temperature in laser welding, so that good conduction of the shielding layer and the conductive end cover can be guaranteed, and overheating and demagnetization of the permanent magnet cannot be caused. When the thickness of the conductive end cover exceeds the thickness of the rotor end pressing plate, the rotor end pressing plate can be cancelled, and the conductive end cover replaces the rotor end pressing plate, so that function reuse is realized.
Compared with the prior art, the utility model discloses following beneficial effect has:
1. the utility model discloses a hug closely at the permanent magnet both ends and set up electrically conductive end cover, provide extra gyration route at the rotor tip for the vortex, and this route conductivity is high, can reduce the eddy current loss of permanent magnet tip and the eddy current loss of shielding layer at both ends to the total eddy current loss of rotor has been reduced.
2. The utility model discloses can further reduce the loss and the temperature rise of rotor on traditional rotor structure basis of only taking the shielding layer, improve permanent-magnet machine's operational reliability.
Drawings
Fig. 1 is a schematic structural diagram of a conventional surface-mounted permanent magnet motor rotor;
fig. 2 is a cross-sectional view of a surface-mounted permanent magnet motor rotor with a conductive end cover according to an embodiment of the present invention;
fig. 3 is a schematic structural view of a surface-mounted permanent magnet motor rotor with a conductive end cover according to an embodiment of the present invention;
FIG. 4 is a schematic structural view of an endless press plate rotor using a flanging process according to an embodiment of the present invention;
FIG. 5 is a schematic view of a shield layer structure before the flanging process is employed;
FIG. 6 is a schematic view of a shielding layer structure after a flanging process is employed;
fig. 7 is a schematic structural view of the end-pressing plate rotor adopting the flanging and laser welding process in the embodiment of the present invention.
In the figure: 1-rotating shaft, 2-rotor core, 3-permanent magnet, 4-shielding layer, 5-rotor sheath, 6-conductive end cover and 7-rotor end pressing plate.
Detailed Description
The invention will be described in further detail with reference to the following figures and examples, which are intended to facilitate the understanding of the invention without limiting it.
As shown in fig. 1, a conventional surface-mounted permanent magnet motor rotor structure includes a rotating shaft 1, a rotor core 2, a permanent magnet 3, a shielding layer 4, and a rotor sheath 5 from inside to outside.
The surface-mounted permanent magnet motor rotor structure with the conductive end cover in the embodiment of the utility model is as shown in fig. 2 and fig. 3, and comprises a rotating shaft 1, wherein the surface of the rotating shaft 1 is sequentially wrapped with a rotor core 2, a permanent magnet 3, a shielding layer 4 and a rotor sheath 5 from inside to outside; and conductive end covers 6 are arranged at two axial ends of the permanent magnet 3, and the conductive end covers 6 are fixedly connected with the shielding layer 4 and tightly attached to the permanent magnet 3.
The permanent magnet 3 is tightly attached to the surface of the rotating shaft 1; the shielding layer 4 is tightly attached to the surface of the permanent magnet 3; the two conductive end covers 6 are tightly attached to the end faces of the permanent magnets 3 and are in full contact with the shielding layers 4; the rotor sheath 5 is wrapped around the shield 4 and the conductive end cap 6.
The principle of the utility model is that:
the shielding layer 4 with high conductivity can provide a passage for eddy current on the cylindrical surface of the rotor, and reduce eddy current loss and heating of the cylindrical surface of the internal permanent magnet 3; the conductive end cover 6 can provide an extra rotary passage for the eddy current at the end part of the rotor, so that the eddy current loss and the heat generation at the end part of the permanent magnet 3 are reduced, and the eddy current density, the eddy current loss and the heat generation at the two ends of the shielding layer 4 are also reduced; good contact between the shield layer 4 and the conductive end cap 6 may enable eddy currents to form a good flow path in the shield layer 4 and the conductive end cap 6. Because the resistivity of the shielding layer 4 and the conductive end cover 6 is very small, the eddy current loss is small, and the eddy current loss and the heating of the whole rotor can be effectively inhibited. In addition, the shielding layer 4 and the conductive end cover 6 with high heat conductivity can also collect heat generated by the permanent magnet 3 and homogenize the temperature of each part of the permanent magnet 3, so that local overheating of the rotor is avoided. The rotor sheath 5 can enhance the mechanical strength of the rotor and tightly bind the permanent magnet 3 and the shielding structure on the rotor shaft and the iron core during high-speed operation.
The utility model discloses well electrically conductive end cover's effect is different from traditional rotor end clamp plate, consequently does not influence the use of former rotor end clamp plate whether. For a motor with a rotor end pressure plate, the conductive end cover is arranged between the end pressure plate and the permanent magnet; for a motor without a rotor end pressing plate, the conductive end covers are arranged at two ends of the permanent magnet.
The following further describes the processing technique of the conductive end cap 6 of the present invention by taking a motor without a rotor end pressing plate as an example and combining with fig. 4-6.
When the rotor is not end-laminated, as shown in fig. 4, the conductive end cover 6 and the shielding layer 4 may be integrally formed by flanging. Firstly, before processing, the shielding layer 4 is mounted outside the permanent magnet 3 with a suitable length reserved at each end (the thickness of the reserved portion should be greater than or equal to that of the permanent magnet 3), as shown in fig. 5. Then, the part of the shielding layer 4 beyond the permanent magnet 3 is folded inwards by 90 degrees by using a flanging process to form a conductive end cover structure, as shown in fig. 6. The integral processing of the shielding layer 4 and the conductive end cap 6 can naturally ensure that the shielding layer and the conductive end cap have good contact.
As shown in fig. 7, when the rotor has an end pressing plate, the conductive end cover 6 covered with a step may be added after the flanging, and the contact edges of the two are fused by laser welding, so as to ensure that the eddy current can flow between the shielding layer 4 and the conductive end cover 6. The rotor end pressure plate 7 still serves as an axial fixation ensuring that the conductive end cover 6 is in close contact with the shielding layer 4.
As an implementation case, to a high-speed permanent-magnet machine of sixty thousand revolutions per minute, six kilowatts, adopt the copper conductive end cover after, its permanent magnet eddy current loss can reduce 83.1%, the total eddy current loss of rotor can reduce 20.3%, the highest temperature rise of rotor can reduce 25.4%.
The above-mentioned embodiment is to the technical solution and the beneficial effects of the present invention have been described in detail, it should be understood that the above is only the specific embodiment of the present invention, not used for limiting the present invention, any modification, supplement and equivalent replacement made within the principle scope of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A permanent magnet motor rotor structure for enhancing the shielding effect of a harmonic magnetic field comprises a rotating shaft and is characterized in that the surface of the rotating shaft is sequentially wrapped with a rotor core, a permanent magnet, a shielding layer and a rotor sheath from inside to outside; and the two axial ends of the permanent magnet are provided with conductive end covers, and the conductive end covers are fixedly connected with the shielding layer and are tightly attached to the permanent magnet.
2. The permanent magnet motor rotor structure with the enhanced harmonic magnetic field shielding effect according to claim 1, wherein interference fit is adopted between the rotor core and the permanent magnet, between the permanent magnet and the shielding layer, and between the shielding layer and the rotor sheath.
3. The structure of claim 1, wherein the conductive end caps and shield layer are made of copper.
4. The structure of claim 1, wherein the thickness of the shielding layer is not less than the skin depth of the major harmonic magnetic field in the shielding layer.
5. The structure of claim 1, wherein the material of the rotor sheath is carbon fiber, glass fiber, non-magnetic stainless steel or titanium alloy.
6. The structure of claim 1, wherein the thickness of the conductive end cover is not less than the thickness of the shielding layer.
7. The permanent magnet motor rotor structure with the enhanced harmonic magnetic field shielding effect according to claim 1, further comprising a rotor end pressing plate, wherein the conductive end cover is arranged between the rotor end pressing plate and the permanent magnet, and the rotor end pressing plate is used for axial fixation so that the conductive end cover is in close contact with the shielding layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921130304.4U CN210225085U (en) | 2019-07-18 | 2019-07-18 | Permanent magnet motor rotor structure for enhancing shielding effect of harmonic magnetic field |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921130304.4U CN210225085U (en) | 2019-07-18 | 2019-07-18 | Permanent magnet motor rotor structure for enhancing shielding effect of harmonic magnetic field |
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| CN210225085U true CN210225085U (en) | 2020-03-31 |
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| CN201921130304.4U Active CN210225085U (en) | 2019-07-18 | 2019-07-18 | Permanent magnet motor rotor structure for enhancing shielding effect of harmonic magnetic field |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110380536A (en) * | 2019-07-18 | 2019-10-25 | 浙江大学 | A kind of rotor structure for permanent magnet motor enhancing harmonic field shielding action |
| CN111725922A (en) * | 2020-06-30 | 2020-09-29 | 稳力(广东)科技有限公司 | Motor sheath device |
-
2019
- 2019-07-18 CN CN201921130304.4U patent/CN210225085U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110380536A (en) * | 2019-07-18 | 2019-10-25 | 浙江大学 | A kind of rotor structure for permanent magnet motor enhancing harmonic field shielding action |
| CN110380536B (en) * | 2019-07-18 | 2024-04-16 | 浙江大学 | Permanent magnet motor rotor structure for enhancing harmonic magnetic field shielding effect |
| CN111725922A (en) * | 2020-06-30 | 2020-09-29 | 稳力(广东)科技有限公司 | Motor sheath device |
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