Built-in tangential mixed magnetic steel magnetism gathering type permanent magnet rotor
By setting multiple permanent magnet units on the rotor core of the built-in permanent magnet synchronous motor, using the combined structure of magnetic steel and air permanent magnet slots of different coercive forces, the problem of difficulty in improving the air gap magnetic density in the prior art is solved, and higher torque density, power density and motor safety are achieved.
Patent Information
- Application Number
- CN202510024494.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-12-30
- Filing Date
- 2025-01-07
- Publication Date
- 2025-02-28
Smart Images
Figure CN119543504A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of motor technology, and in particular to a technology of a built-in tangential hybrid magnetic steel magnetic concentrating type permanent magnet rotor. Background Art
[0002] Currently, permanent magnet synchronous motors suitable for electric vehicles and industrial automation have defects such as large torque fluctuations, low power and torque density, low overload capacity and poor reliability, which make it difficult to meet the requirements. The drive motors restrict the research and development and industrialization process of China's electric vehicles and industrial automation.
[0003] For a long time, improving power and torque density and reducing motor torque fluctuation have been one of the focuses of motor research at home and abroad. One way to improve power density is to increase the speed, but it is necessary to increase the input power supply voltage frequency, which leads to an increase in high-order harmonics, permanent magnet rotor losses and motor temperature rise; an effective way to improve power density and torque density is to increase the air gap flux and air gap flux density, thereby increasing the no-load back EMF and reducing leakage flux. For this reason, the existing internal permanent magnet synchronous motor (IPMSM) takes two measures to jointly resist leakage flux and improve air gap flux density: 1) Air permanent magnet slots are set at both ends of the internal magnetic steel, that is, non-magnetic flux barriers (Non-magnetic flux barriers), which play a magnetic isolation role and improve air gap flux density; 2) Magnetic isolation bridges are set between the two ends of the permanent magnet poles (q axis) and the outer edge of the rotor to improve the air gap flux density.
[0004] The narrower the magnetic bridge thickness is designed, the deeper the magnetic circuit is saturated, and the smaller the magnetic permeability coefficient is, which can limit the leakage flux, increase the effective magnetic flux, and improve the air gap magnetic density; however, the magnetic bridge is located at the outer edge of the rotor, and the thickness of the magnetic bridge is too narrow, the mechanical strength is poor, the motor manufacturing process and manufacturing cost are increased, and the service life of the rotor silicon steel sheet die is reduced; the maximum stress of the rotor is inversely proportional to the thickness of the magnetic bridge and proportional to the square of the speed. At high speed, there is a hidden danger of plastic deformation of the rotor, and the high-speed operation of the motor is unsafe. Therefore, the existing IPMSM, the magnetic bridge is difficult to isolate leakage flux, and it is difficult to balance the power density of the motor by increasing the air gap magnetic density and the safety of the motor's high-speed operation. Summary of the invention
[0005] In view of the defects existing in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor which can increase the air gap magnetic density, thereby increasing the torque density and power density, and reducing the motor noise and torque fluctuation.
[0006] In order to solve the above technical problems, the present invention provides a built-in tangential hybrid magnetic steel magnetic concentrating type permanent magnet rotor, comprising a rotor core and a rotating shaft, wherein the rotor core is provided with a plurality of permanent magnet units symmetrically arranged around the axis of the rotor core, characterized in that: The permanent magnet unit includes a central magnetic steel, and a central air permanent magnet slot and radial magnetic steels are provided between adjacent permanent magnet units. The central air permanent magnet slot and radial magnetic steels are both arranged on the q-axis, and the central air permanent magnet slot is arranged on the inner side of the radial magnetic steel. The central magnetic steel and the radial magnetic steels adjacent to the central magnetic steel on both sides are arranged in a U shape.
[0007] Furthermore, the coercive force of the radial magnetic steel is lower than the coercive force of the central magnetic steel.
[0008] Furthermore, the permanent magnet unit also includes a V-shaped magnet, which is located on the outside of the middle magnet. The V-shaped magnet is composed of two I-shaped magnets, which are respectively arranged on both sides of the d-axis and are arranged in an eight-shaped shape with a narrow mouth facing inward, and an inner end air permanent magnet groove is provided in the narrow mouth of the eight-shaped shape, and an outer end air permanent magnet groove is provided at each outer end of the two I-shaped magnets.
[0009] Furthermore, the coercive force of the two straight-line magnetic steels constituting the V-shaped magnetic steel is higher than the coercive force of the radial magnetic steel.
[0010] The built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor provided by the present invention adopts a structure of U-shaped arrangement of magnetic steels, utilizes multiple groups of magnetic steels for multi-directional magnetization, has a strong magnetic concentrating effect, and utilizes magnetic steels with different coercive forces to effectively suppress the armature reaction at both ends of the magnetic steels, thereby improving the overload capacity and overload multiple of the motor. The air permanent magnet slots (non-magnetic flux barriers) play the role of isolating magnetic flux and suppressing leakage magnetic flux. The multi-layer permanent magnet structure and the radial, tangential and high- and low-energy magnetic steel mixed multi-path magnetic concentrating make the d-axis of the radial center line of the magnetic pole and the q-axis radial force of the inter-pole center line tend to be balanced, thereby improving the air gap magnetic density, thereby improving the torque density and power density, and reducing the motor noise and torque fluctuation. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 1 is a schematic radial cross-sectional view of a built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor according to a first embodiment of the present invention; Figure 2 It is a radial cross-sectional schematic diagram of a built-in tangential hybrid magnetic steel magnetic concentrating type permanent magnet rotor according to the second embodiment of the present invention. DETAILED DESCRIPTION
[0012] The following is a further detailed description of an embodiment of the present invention in conjunction with the accompanying drawings, but this embodiment is not intended to limit the present invention. All similar structures and similar variations of the present invention should be included in the protection scope of the present invention. The commas in the present invention all represent the relationship of and.
[0013] like Figure 1As shown, a first embodiment of the present invention provides a built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor, comprising a rotor core 11 and a rotating shaft 12, wherein the rotor core 11 is provided with a plurality of permanent magnet units symmetrically arranged around the axis of the rotor core, and is characterized in that: The permanent magnet unit includes a middle magnetic steel 143, and a middle air permanent magnet slot 142 and a radial magnetic steel 141 are provided between adjacent permanent magnet units. The middle air permanent magnet slot 142 and the radial magnetic steel 141 are both arranged on the q-axis, and the middle air permanent magnet slot 142 is arranged on the inner side of the radial magnetic steel 141 (the side facing the rotor core axis is the inner side), and the middle magnetic steel 143 and the radial magnetic steels 141 adjacent to the middle magnetic steel 143 on both sides are arranged in a U shape, and the portion of the rotor core 11 enclosed by the middle magnetic steel 143 and the radial magnetic steel 141 constitutes a pole shoe 13; The coercive force of the radial magnetic steel 141 is lower than the coercive force of the central magnetic steel 143 . The radial magnetic steel 141 is made of a ferrite material with a low coercive force, and the central magnetic steel 143 is made of a neodymium iron boron material with a high coercive force.
[0014] like Figure 2 As shown, the second embodiment of the present invention is similar to the first embodiment, and the second embodiment also includes a rotor core 21 and a rotating shaft 22. The rotor core 21 is also provided with a plurality of permanent magnet units symmetrically arranged around the axis of the rotor core, and the permanent magnet unit includes a middle magnetic steel 243, and a middle air permanent magnet slot 242 and a radial magnetic steel 241 are provided between adjacent permanent magnet units. The middle air permanent magnet slot 242 and the radial magnetic steel 241 are both arranged on the q-axis, and the middle air permanent magnet slot 242 is arranged on the inner side of the radial magnetic steel 241. The middle magnetic steel 243 and the radial magnetic steels 241 adjacent to the middle magnetic steel 243 on both sides are arranged in a U shape. The coercive force of the radial magnetic steel 241 is lower than the coercive force of the central magnetic steel 243 . The radial magnetic steel 241 is made of a ferrite material with a low coercive force, and the central magnetic steel 243 is made of a neodymium iron boron material with a high coercive force.
[0015] The difference between the second embodiment of the present invention and the first embodiment is that the permanent magnet unit also includes a V-shaped magnet, which is located on the outside of the middle magnet 243. The V-shaped magnet is composed of two I-shaped magnets 251. The two I-shaped magnets 251 are respectively arranged on both sides of the d-axis and are arranged in an eight-shaped shape with a narrow mouth facing inward, and an inner end air permanent magnet groove 252 is provided at the narrow mouth of the eight-shaped shape. An outer end air permanent magnet groove 253 is provided at each outer end of the two I-shaped magnets 251, and the coercive force of the two I-shaped magnets 251 is higher than the coercive force of the radial magnet 241. The two I-shaped magnets 251 are both made of high coercive force neodymium iron boron material, and the part of the rotor core 21 enclosed by the two I-shaped magnets 251 constitutes the pole shoe 23.
[0016] The motor using the permanent magnet rotor of this embodiment is compared with a motor of the same specification using an existing built-in double-layer U-shaped permanent magnet rotor. The parameters of the motor of the existing built-in double-layer U-shaped permanent magnet rotor are: rated power of 36KW, rated current of 109A, efficiency of 94.2%, rated speed of 3000r / min, maximum speed of 9000r / min, rated torque of 115Nm, and maximum torque of 253Nm; Compared with the existing built-in double-layer U-shaped permanent magnet rotor motor of the same specification, the motor using the permanent magnet rotor of the first embodiment of the present invention has a rated current reduced from 109A to 102A, an efficiency increased from 94.2% to 96.5%, a rated power increased from 36KW to 38KW, a rated torque increased from 115Nm to 121Nm, and a maximum torque increased from 253Nm to 268Nm, that is, the power density and torque density are significantly improved; Compared with the existing motor with built-in double-layer U-shaped permanent magnet rotor of the same specification, the motor using the permanent magnet rotor of the second embodiment of the present invention has an efficiency increased from 94.2% to 97.2%, and when the rated current is reduced from 109A to 121A, the rated power is increased from 36KW to 38KW, and the rated torque is increased from 115Nm to 121Nm, that is, the power density and torque density are significantly improved; It can be seen that the first embodiment and the second embodiment of the present invention both improve the air gap magnetic flux density waveform, and reduce motor noise and torque fluctuation by increasing power density and torque density.
Claims
1. A built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor, comprising a rotor core and a rotating shaft, wherein the rotor core is provided with a plurality of permanent magnet units symmetrically arranged around the axis of the rotor core, characterized in that: The permanent magnet unit includes a central magnetic steel, and a central air permanent magnet slot and radial magnetic steels are provided between adjacent permanent magnet units. The central air permanent magnet slot and radial magnetic steels are both arranged on the q-axis, and the central air permanent magnet slot is arranged on the inner side of the radial magnetic steel. The central magnetic steel and the radial magnetic steels adjacent to the central magnetic steel on both sides are arranged in a U shape.
2. The built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor according to claim 1 is characterized in that: The coercive force of the radial magnetic steel is lower than the coercive force of the central magnetic steel.
3. The built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor according to claim 1 or 2, characterized in that: The permanent magnet unit also includes a V-shaped magnet, which is located on the outside of the middle magnet. The V-shaped magnet is composed of two I-shaped magnets, which are respectively arranged on both sides of the d-axis and are arranged in an eight-shaped shape with a narrow mouth facing inward, and an inner end air permanent magnet groove is provided in the narrow mouth of the eight-shaped shape, and an outer end air permanent magnet groove is provided at the outer ends of the two I-shaped magnets.
4. The built-in tangential hybrid magnetic steel magnetic concentrating permanent magnet rotor according to claim 3 is characterized in that: The coercive force of the two straight-shaped magnets constituting the V-shaped magnet is higher than the coercive force of the radial magnet.