Built-in multi-layer arc-shaped mixed magnetic steel magnetism gathering type permanent magnet rotor
By using a multi-layer arc-type hybrid magnetic steel polymagnetic permanent magnet rotor in the built-in permanent magnet synchronous motor, and using a multi-layer permanent magnet structure and air permanent magnet slot, the problem of difficult to balance the air gap magnetic density and power density in the prior art is solved, and a higher torque density and power density are achieved, and noise and fluctuations are reduced.
Patent Information
- Application Number
- CN202510024491.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-12-30
- Filing Date
- 2025-01-07
- Publication Date
- 2025-03-04
AI Technical Summary
When the existing built-in permanent magnet synchronous motor improves the magnetic density of the air gap, it is difficult to take into account the power density, torque density and high-speed operation safety.
The built-in multi-layer arc-type hybrid magnet steel polymagnetic permanent magnet rotor is adopted. By setting up multiple permanent magnet units and arc-type magnet groups, the air permanent magnet slot and multi-layer permanent magnet structure are used to improve the air gap magnetic density and magnetoresistance torque ratio.
It significantly improves torque density and power density, reduces motor noise and torque fluctuations, and expands the constant power speed range, improving the reliability and safety of the motor.
Smart Images
Figure CN119561286A_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 multi-layer arc-shaped hybrid magnetic steel magnetic concentrating 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 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 multi-layer arc-shaped 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 multi-layer arc-shaped hybrid magnetic steel magnetic concentrating permanent magnet rotor, including a rotor core, on which a plurality of permanent magnet units are arranged symmetrically around the axis of the rotor core, characterized in that: The permanent magnet unit includes three arc-shaped magnetic steel groups, and the three arc-shaped magnetic steel groups are arranged in sequence from the inside to the outside along the radial direction of the rotor, the two ends of the three arc-shaped magnetic steel groups face outward, and the two ends of the arc-shaped magnetic steel groups are each provided with a first air permanent magnet slot, the arc-shaped magnetic steel group is divided from left to right into a left magnetic steel, a middle magnetic steel and a right magnetic steel, and a second air permanent magnet slot is each provided between the middle magnetic steel and the left magnetic steel and the right magnetic steel; The coercive force of the left magnetic steel and the right magnetic steel is greater than the coercive force of the middle magnetic steel.
[0007] The built-in multi-layer arc-shaped hybrid magnetic steel magnetic concentrating permanent magnet rotor provided by the present invention adopts a structure in which three layers of magnetic steel are arranged in a segmented arc shape, and multiple groups of magnetic steel are used for multi-directional magnetization, so that the magnetic concentrating effect is strong, and the air permanent magnet slots (non-magnetic flux barriers) form multiple air magnetic barriers in different positions and structures, which effectively improve the salient pole ratio and the magnetic resistance torque ratio. At the same time, low magnetic energy product ferrite magnetic steel is used to make the weak magnetic speed expansion ability of the armature magnetic field stronger, which can significantly reduce the centrifugal force of the rotor during high-speed operation, which is conducive to the frequent starting of the motor and plays the role of magnetic isolation and suppression of leakage flux; the magnetic steel group and the outer edge of the rotor form a magnetic bridge, and the saturation degree of the magnetic circuit is changed by adjusting the width of the magnetic bridge, so as to achieve the effect of weak magnetic constant power speed expansion in the high-speed section, and obtain a wider constant power speed range than the existing built-in permanent magnet motor; the multi-layer permanent magnet structure and the high-low energy magnetic steel mixed multi-path magnetic concentrating make the d-axis radial center line of the magnetic pole and the q-axis radial force of the center line between the poles tend to be balanced, which can improve 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
[0008] Figure 1 It is a schematic radial cross-sectional view of a built-in multi-layer arc-shaped hybrid magnetic steel magnetic concentrating permanent magnet rotor according to an embodiment of the present invention. DETAILED DESCRIPTION
[0009] 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.
[0010] like Figure 1 As shown, an embodiment of the present invention provides a built-in multi-layer arc-shaped hybrid magnetic steel magnetic concentrating permanent magnet rotor, comprising a rotor core 1, on which a plurality of permanent magnet units are arranged symmetrically around the axis of the rotor core 1, characterized in that: The permanent magnet unit includes three arc-shaped magnetic steel groups, and the three arc-shaped magnetic steel groups are arranged in sequence from the inside to the outside along the radial direction of the rotor, with both ends of the three arc-shaped magnetic steel groups facing outward, and both ends of the arc-shaped magnetic steel groups are provided with first air permanent magnet slots 31, and the arc-shaped magnetic steel groups are divided into left magnetic steel 21, middle magnetic steel 22 and right magnetic steel 23 from left to right, and second air permanent magnet slots 32 are provided between the middle magnetic steel 22 and the left magnetic steel 21 and the right magnetic steel 23; The coercive force of the left magnetic steel 21 and the right magnetic steel 23 is greater than the coercive force of the middle magnetic steel 22 .
[0011] 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 embodiment of the present invention has a rated current reduced from 109A to 102A, an efficiency increased from 94.2% to 96.3%, 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; It can be seen that the embodiments of the present invention 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 multi-layer arc-shaped hybrid magnetic steel magnetic concentrating permanent magnet rotor, comprising a rotor core, on which a plurality of permanent magnet units are arranged symmetrically around the axis of the rotor core, characterized in that: The permanent magnet unit includes three arc-shaped magnetic steel groups, and the three arc-shaped magnetic steel groups are arranged in sequence from the inside to the outside along the radial direction of the rotor, the two ends of the three arc-shaped magnetic steel groups face outward, and the two ends of the arc-shaped magnetic steel groups are each provided with a first air permanent magnet slot, the arc-shaped magnetic steel group is divided from left to right into a left magnetic steel, a middle magnetic steel and a right magnetic steel, and a second air permanent magnet slot is each provided between the middle magnetic steel and the left magnetic steel and the right magnetic steel; The coercive force of the left magnetic steel and the right magnetic steel is greater than the coercive force of the middle magnetic steel.