Built-in V-shaped asymmetric permanent magnet rotor
By designing a built-in V-shaped asymmetric permanent magnet rotor and using alternating A and B groups of permanent magnet units, the problems of large torque fluctuation and high processing difficulty in permanent magnet synchronous motors for electric vehicles have been solved, achieving low noise, high power density and wide speed regulation performance of the motor.
Patent Information
- Application Number
- CN202323319099.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-06
- Publication Date
- 2026-01-13
- Estimated Expiration
- 2033-12-06
AI Technical Summary
Existing permanent magnet synchronous motors have problems such as large torque fluctuations, low power density, narrow high-speed constant power range, low overload capacity and poor reliability in electric vehicle applications. Moreover, existing solutions increase the difficulty and cost of rotor processing.
A built-in V-shaped asymmetric permanent magnet rotor is designed, which adopts alternating A and B groups of permanent magnet units with asymmetric magnet thickness and width, and different magnetic isolation slot structures at the inner and outer ends, forming an asymmetric structure. This reduces the need for stator skew slots, rotor skew poles and uneven air gaps, and reduces torque fluctuation.
It effectively reduces torque ripple, improves the overall performance of the motor, reduces mechanical vibration and noise, improves the air gap magnetic field waveform, increases overload capacity and power density, and meets the driving requirements of electric vehicles.
Smart Images
Figure CN223797990U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to motor technology, and in particular to a technology for a built-in V-shaped asymmetric permanent magnet rotor. Background Technology
[0002] Currently, permanent magnet synchronous motors suitable for electric vehicles suffer from drawbacks such as large torque fluctuations, low power density, narrow high-speed constant power range, low overload capacity, and poor reliability, making it difficult to meet the requirements.
[0003] Reducing motor torque ripple is a key focus of motor research. The interaction between the stator core and permanent magnets generates positioning torque, and the non-sinusoidal waveforms of current and back EMF cause harmonic torque during motor operation. Furthermore, deviations in manufacturing processes exacerbate torque ripple. Cogging torque, also known as magnetic reluctance torque, is a fatal flaw in speed control systems used in automation and mechatronics applications. When the frequency of the torque coincides with the mechanical resonant frequency of the stator or rotor during motor operation, the vibration and noise generated by the cogging torque are significantly amplified, also affecting low-speed performance and positioning accuracy.
[0004] To overcome the above-mentioned defects, most existing permanent magnet synchronous motors adopt measures such as setting skewed slots in the stator, setting skewed poles in the rotor, setting uneven air gaps between the stator and rotor, and increasing the number of motor slots to reduce torque fluctuations. These measures increase the difficulty of rotor processing and increase rotor processing costs. Utility Model Content
[0005] In view of the defects existing in the prior art, the technical problem to be solved by this utility model is to provide a built-in V-shaped asymmetric permanent magnet rotor that can reduce motor torque fluctuation and has low processing difficulty.
[0006] To solve the above-mentioned technical problems, this utility model provides a built-in V-shaped asymmetric permanent magnet rotor, including a rotor core on which multiple permanent magnet units are provided; each permanent magnet unit consists of two magnets, one of which is arranged on the counterclockwise side of the d-axis and the other on the clockwise side of the d-axis, and the arrangement of the two magnets is a narrow-mouthed inward V-shape, with magnetic isolation grooves provided at both the inner and outer ends of the two magnets; characterized in that:
[0007] The permanent magnet unit is divided into group A and group B. The two groups of permanent magnet units are arranged alternately around the axis of the rotor core. The magnet of the permanent magnet unit in group A is the first magnet, and the magnet of the permanent magnet unit in group B is the second magnet. The thickness of the first magnet is h1 and the width is b1, and the thickness of the second magnet is h2 and the width is b2, where h1 < h2 and b1 > b2.
[0008] Furthermore, the magnetic isolation grooves at both the inner and outer ends of the first magnet have different structures from those at both the inner and outer ends of the second magnet, forming an asymmetrical structure.
[0009] Furthermore, the thickness h1 of the first magnet is 0.67 to 0.85 times the thickness h2 of the second magnet.
[0010] Furthermore, the width b1 of the first magnet is 1.1 to 1.2 times the width b2 of the second magnet.
[0011] The built-in V-shaped asymmetric permanent magnet rotor provided by this utility model adopts an asymmetric structure of adjacent permanent magnet unit magnets, making the center lines of adjacent magnetic poles asymmetric. This effectively improves the overall performance. The motor stator does not need skewed slots, the rotor does not need skewed poles, and there is no need to set uneven air gaps between the stator and rotor. This effectively reduces torque fluctuations, improves the air gap magnetic field waveform, and has lower processing difficulty. Without increasing the number of motor slots, it can increase the fundamental frequency of cogging torque fluctuations, reduce the amplitude of cogging fundamental and higher harmonic torques, reduce torque fluctuations caused by cogging, and make the radial force of the d-axis of the magnetic pole radial center line and the q-axis of the inter-pole center line tend to be balanced, improving the air gap magnetic flux density waveform, reducing mechanical vibration, noise, and back EMF harmonics, reducing core losses, and effectively reducing torque fluctuations. Attached Figure Description
[0012] Figure 1 This is a radial cross-sectional schematic diagram of the built-in V-shaped asymmetric permanent magnet rotor according to an embodiment of the present invention;
[0013] Figure 2 This is a torque fluctuation histogram of the built-in V-shaped asymmetric permanent magnet rotor of this utility model embodiment and the existing built-in V-shaped permanent magnet rotor. Detailed Implementation
[0014] The embodiments of this utility model are described in further detail below with reference to the accompanying drawings. However, these embodiments are not intended to limit this utility model. Any similar structures or variations thereof that adopt this utility model should be included in the protection scope of this utility model. The commas in this utility model all indicate the relationship between and.
[0015] like Figure 1 As shown, the present invention provides a built-in V-shaped asymmetric permanent magnet rotor, which includes a rotor core 1, and the rotor core 1 is provided with a plurality of permanent magnet units.
[0016] The permanent magnet unit consists of two magnets, one of which is arranged on the counterclockwise side of the d-axis and the other is arranged on the clockwise side of the d-axis. The arrangement of the two magnets is a figure-eight shape with the narrow opening facing inward. Both the inner and outer ends of the two magnets are provided with magnetic isolation grooves 3.
[0017] The permanent magnet units are divided into group A and group B. The two groups of permanent magnet units are arranged alternately around the axis of the rotor core. The magnet of the permanent magnet unit in group A is the first magnet 21, and the magnet of the permanent magnet unit in group B is the second magnet 22. The thickness of the first magnet 21 is h1 and the width is b1, and the thickness of the second magnet 22 is h2 and the width is b2. h1 < h2 and b1 > b2. Adjacent permanent magnet units use magnets with different thicknesses and widths to form an asymmetrical structure.
[0018] The magnetic isolation grooves 3 at both the inner and outer ends of the first magnet 21 have different structures from those at both the inner and outer ends of the second magnet 22, forming an asymmetrical structure.
[0019] In this embodiment of the present invention, the preferred ratio of the thickness of the first magnet to the thickness of the second magnet is: the thickness h1 of the first magnet is 0.67 to 0.85 times the thickness h2 of the second magnet.
[0020] In this embodiment of the present invention, the preferred aspect ratio of the width of the first magnet 21 to the width of the second magnet 22 is that the width b1 of the first magnet is 1.1 to 1.2 times the width b2 of the second magnet.
[0021] Figure 2 This is a torque fluctuation histogram of the embodiment of this utility model and an existing built-in V-type permanent magnet rotor. Figure 2 In the figure, the vertical axis Tr represents torque fluctuation, the square column A represents the torque fluctuation of the existing built-in V-type permanent magnet rotor, and the square column C represents the torque fluctuation of this embodiment.
[0022] Torque fluctuations caused by electromagnetic factors generate mechanical and electromagnetic noise, affecting the smooth operation and reliability of the motor. These fluctuations are of two types: cogging torque, which is the torque generated by the interaction between the stator slots and the rotor permanent magnets. This torque fluctuates periodically with spatial position and is independent of the stator current; and ripple torque, which is the harmonic torque caused by the difference between the current and back EMF waveforms. The torque fluctuations in automotive permanent magnet synchronous motors are the superposition of cogging torque and ripple torque.
[0023] from Figure 2 It can be seen that the torque fluctuation of the existing built-in V-type permanent magnet rotor is 73%, while the torque fluctuation of this embodiment is 49%, showing a significant reduction in torque fluctuation. This demonstrates that the rotor of this embodiment can effectively reduce cogging torque fluctuation and ripple torque fluctuation.
[0024] The motor using the permanent magnet rotor of this embodiment was compared with a motor of the same specification using an existing built-in V-type permanent magnet rotor. The motor parameters are: rated power of 18KW, rated speed of 3000r / min, maximum speed of 9000r / min, rated torque of 57.3Nm, and maximum torque of 126Nm.
[0025] The cogging torque of the motor using the existing built-in V-type permanent magnet rotor is 2.63 Nm, the cogging torque fluctuation is 4.58%, and the efficiency is 94%.
[0026] The motor using the permanent magnet rotor in this embodiment has a cogging torque of 1.32 Nm, a cogging torque fluctuation of 2.3%, and an efficiency of 95.6%.
[0027] It is evident that the cogging torque fluctuation of the motor of the same specifications used in this embodiment is significantly reduced, and the efficiency is significantly improved.
[0028] This utility model embodiment constructs an asymmetrical structure of adjacent magnetic pole centerlines, which can effectively improve overall performance. The motor stator does not require skewed slots, the rotor does not require skewed poles, and there is no need for measures such as uneven air gaps between the stator and rotor. This effectively reduces torque ripple, improves the air gap magnetic field waveform, and increases the fundamental frequency of cogging torque ripple without increasing the number of motor slots. It also reduces the amplitude of cogging fundamental and higher harmonic torques, lowers torque ripple caused by cogging, and brings the radial forces along the d-axis of the magnetic pole radial centerline and the q-axis of the inter-pole centerline into balance. This improves the air gap magnetic flux density waveform, reduces mechanical vibration, noise, and back EMF harmonics, reduces core losses, effectively reduces torque ripple, improves overload capacity, meets the drive requirements of electric vehicles, and achieves the characteristics of high power density, low noise, low torque ripple, wide speed range, small size, lightweight, and stable operation of the motor.
Claims
1. A built-in V-shaped asymmetric permanent magnet rotor, comprising a rotor core, a plurality of permanent magnet units are arranged on the rotor core; the permanent magnet unit is composed of two magnetic steels, one of which is arranged on the counterclockwise side of the d-axis, and the other is arranged on the clockwise side of the d-axis, and the arrangement shape of the two magnetic steels is a narrow opening inward splayed shape, and the inner and outer ends of the two magnetic steels are provided with magnetic isolation grooves; characterized in that: the permanent magnet unit is divided into group A and group B, the two groups of permanent magnet units are alternately arranged around the axis of the rotor core, the magnetic steel of the group A permanent magnet unit is a first magnetic steel, the magnetic steel of the group B permanent magnet unit is a second magnetic steel, the thickness of the first magnetic steel is h1 and the width is b1, the thickness of the second magnetic steel is h2 and the width is b2, h1 < h2 and b1 > b2.
2. The interior V-type asymmetric permanent magnet rotor according to claim 1, characterized in that: The magnetic isolation grooves at the inner and outer ends of the first magnetic steel are different in structure from the magnetic isolation grooves at the inner and outer ends of the second magnetic steel, forming an asymmetric structure.
3. The interior V-type asymmetric permanent magnet rotor according to claim 1, characterized in that: The thickness h1 of the first magnetic steel is 0.67-0.85 times the thickness h2 of the second magnetic steel.
4. The interior V-type asymmetric permanent magnet rotor according to claim 1, characterized by: The width b1 of the first magnetic steel is 1.1-1.2 times the width b2 of the second magnetic steel.