Rotor, motor, electric drive assembly, vehicle, and coercivity determination method

Abstract

This application discloses a rotor, a motor, an electric drive assembly, a vehicle, and a method for determining coercivity, belonging to the field of motors. The rotor includes a shaft and a plurality of magnet assemblies spaced apart along the axial direction of the shaft, wherein at least two magnet assemblies have different coercivities along the axial direction of the shaft. In this application, by setting at least two magnet assemblies to have different coercivities along the axial direction of the shaft, magnet assemblies can be formed using magnet materials with different coercivities in the rotor. This allows magnet materials with lower coercivity to be used, thereby reducing the waste of magnet materials with lower coercivity and improving their utilization rate.

Description

Technical Field

[0001] This application belongs to the field of electric motors, specifically relating to a rotor, an electric motor, an electric drive assembly, a vehicle, and a method for determining coercivity. Background Technology

[0002] With the development of technology, vehicles have become an indispensable means of transportation for people's daily travel. Typically, vehicles are equipped with synchronous motors, which provide power for the vehicle to move. A synchronous motor consists of a rotor module and a stator module, with the stator module mounted on top of the rotor module, allowing the rotor module to rotate relative to the stator module. The rotor module usually contains magnet assemblies. The performance of the synchronous motor is determined by demagnetizing it. In related technologies, to improve the demagnetizing ability of the synchronous motor, the coercivity of the magnet assembly is usually increased. However, this method leads to a waste of magnet material. Summary of the Invention

[0003] The purpose of this application is to provide a rotor, motor, electric drive assembly, vehicle, and coercivity determination method, at least to solve the problem of waste of magnet materials.

[0004] In a first aspect, embodiments of this application provide a rotor, the rotor comprising: a rotating shaft and a plurality of magnet assemblies spaced apart along the axial direction of the rotating shaft, wherein at least two of the magnet assemblies have different coercivity along the axial direction of the rotating shaft.

[0005] Optionally, along the axial direction of the rotating shaft, the plurality of magnet assemblies include a first magnet assembly, a second magnet assembly, and a third magnet assembly, wherein the second magnet assembly is located between the first magnet assembly and the third magnet assembly, and the coercivity of the first magnet assembly, the second magnet assembly, and the third magnet assembly are all different.

[0006] Optionally, the second magnet assembly is located in the middle section of the axial direction of the rotating shaft, and the first magnet assembly and the third magnet assembly are located at both ends of the axial direction of the rotating shaft.

[0007] Optionally, the coercivity of the second magnet assembly is greater than that of the first magnet assembly, and the coercivity of the second magnet assembly is greater than that of the third magnet assembly.

[0008] Optionally, along the axial direction of the rotating shaft, from the second magnet assembly to the first magnet assembly, the coercivity of the magnet assembly gradually decreases, and along the direction from the second magnet assembly to the third magnet assembly, the coercivity of the magnet assembly gradually decreases.

[0009] Optionally, the coercivity of the first magnet assembly is 753 Ka / m, the coercivity of the second magnet assembly is 767 Ka / m, and the coercivity of the third magnet assembly is 739 Ka / m.

[0010] Optionally, each of the magnet assemblies includes multiple magnet groups, and each magnet group includes at least two magnet sheets;

[0011] Along the circumferential direction of the rotating shaft, a plurality of magnet groups of each magnet assembly are distributed at intervals around the rotating shaft, and the magnet groups of two adjacent magnet assemblies are staggered along the circumferential direction of the rotating shaft.

[0012] Secondly, embodiments of this application provide an electric motor, which includes the rotor described in any one of the first aspects above.

[0013] Thirdly, embodiments of this application provide an electric drive assembly, which includes the motor described in the second aspect above.

[0014] Fourthly, embodiments of this application provide a vehicle that includes the electric drive assembly described in the third aspect above.

[0015] Fifthly, embodiments of this application provide a method for determining coercivity, used to determine the distribution of coercivity in the magnet assembly of the rotor described in any of the first aspects above, the method comprising:

[0016] Control the motor to switch to active short-circuit protection mode to demagnetize the motor, and determine the transient torque waveform of the motor when it switches to active protection mode;

[0017] Based on the transient waveform diagram, the distribution of coercivity of the magnet assembly is determined.

[0018] Optionally, before controlling the motor to switch to active short-circuit protection mode, the determination method further includes:

[0019] When the motor runs for a duration greater than or equal to a preset duration and the temperature of the internal components of the motor is at its highest temperature, the motor is controlled to switch to the mode corresponding to the peak external characteristic inflection point. The peak external characteristic inflection point is the highest speed operating point at which the motor outputs peak torque. The motor includes a rotor assembly, and the rotor includes multiple magnet assemblies, which are distributed sequentially along the axial direction of the motor shaft.

[0020] Optionally, determining the distribution of coercivity of the magnet assembly based on the transient waveform includes:

[0021] The magnitude of the demagnetizing magnetic field at different positions of the rotor is determined from the transient waveform diagram;

[0022] The distribution of the magnet components is determined according to the magnitude of the demagnetizing magnetic field.

[0023] Optionally, determining the distribution of the magnet assembly according to the magnitude of the demagnetizing magnetic field includes:

[0024] Sort the demagnetized magnets by size;

[0025] According to the order of demagnetizing magnetic field from large to small, the magnet components with different coercivity are sorted to determine the distribution of the magnet components. Among them, the magnet components with small coercivity correspond to small demagnetizing magnetic fields, and the magnet components with large coercivity correspond to large demagnetizing magnetic fields.

[0026] In this embodiment, since multiple magnet assemblies are distributed along the axial direction of the shaft, and at least two magnet assemblies have different coercivities along the axial direction of the shaft, magnet assemblies with different coercivities can be used along the axial direction of the shaft. This allows magnet materials with different coercivities to be used, avoiding waste of magnet materials with lower coercivity. In other words, by setting at least two magnet assemblies with different coercivities along the axial direction of the shaft, magnet assemblies can be formed using magnet materials with different coercivities in the rotor. This allows magnet materials with lower coercivity to be used, thereby reducing the waste of magnet materials with lower coercivity and improving their utilization rate. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of a rotor provided in an embodiment of this application;

[0028] Figure 2 This diagram illustrates a rotor provided in an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of a rotor module provided in an embodiment of this application;

[0030] Figure 4 This is a schematic diagram showing the distribution of magnet components in a rotor module of a rotor according to an embodiment of this application;

[0031] Figure 5 This diagram illustrates the transient waveform of a rotor peak external feature inflection point hard-cut ASC torque according to an embodiment of this application.

[0032] Figure 6 This diagram illustrates the transient waveforms of three-phase current and back EMF of a rotor peak external novel inflection point hard-cut ASC provided in an embodiment of this application;

[0033] Figure 7This is a schematic diagram illustrating the relative position of the winding and the middle of the rotor module at the moment when the V back electromotive force crosses zero when three-phase current flows through the rotor, according to an embodiment of this application.

[0034] Figure 8 This is a schematic diagram showing the relative position of the winding and the end of the rotor module at the moment when the V back electromotive force crosses zero when three-phase current flows through the rotor, according to an embodiment of this application.

[0035] Figure 9 This is a flowchart illustrating a method for determining coercivity provided in an embodiment of this application.

[0036] Figure label:

[0037] 10: Rotor; 11: Shaft; 13: Rotating shell assembly; 121: Magnet assembly; 122: Magnet group; 123: Magnet sheet; 1201: First part; 1202: Second part; 1203: Third part; 20: Stator module. Detailed Implementation

[0038] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0039] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] like Figures 1 to 8 As shown, the rotor includes a shaft 10 and a plurality of magnet assemblies 121 distributed along the axial direction of the shaft 11. At least two magnet assemblies 121 have different coercive forces along the axial direction of the shaft 11.

[0042] In this embodiment, since multiple magnet assemblies 121 are distributed along the axial direction of the rotating shaft 11, and at least two magnet assemblies 121 have different coercivity along the axial direction of the rotating shaft 11, magnet assemblies 121 with different coercivity can be used along the axial direction of the rotating shaft 11. This allows magnet materials with different coercivity to be used, avoiding waste of magnet materials with lower coercivity. In other words, by setting at least two magnet assemblies 121 with different coercivity along the axial direction of the rotating shaft 11, magnet assemblies 121 with different coercivity can be formed in the rotor using magnet materials with different coercivity. This allows magnet materials with lower coercivity to be used, thereby reducing the degree of waste of magnet materials with lower coercivity and improving the utilization rate of magnet materials with lower coercivity.

[0043] For vehicle rotors, the most demanding demagnetization condition that the rotor needs to withstand is: prolonged high-load continuous operation, bringing all internal components of the rotor to their highest operating temperature. Immediately afterwards, the rotor switches to its peak external characteristic inflection point (the highest speed at which the rotor can output peak torque), and then immediately hard-switches into ASC mode. ASC mode is the rotor's active short-circuit protection mode, where the controller short-circuits the rotor's three-phase windings, generating a peak high current that demagnetizes the motor magnets. Currently, to improve the rotor's demagnetization capability, the coercivity of the rotor magnets can be increased. In related technologies, the rotor includes multiple magnet assemblies 121, which are arranged along the axial direction of the shaft 11. The coercivity of each magnet assembly 121 is equal to that of the other magnet assemblies 121. That is, the coercivity of all magnet assemblies 121 in the entire rotor is increased to meet the anti-demagnetization requirements of the most severe demagnetization position of the magnet. This will result in the overcapacity of the magnet material and waste of magnet materials with lower coercivity. In this embodiment, the strength of the demagnetizing magnetic field varies along the axial direction of the rotor shaft 11 during demagnetization. Therefore, different coercive magnet components 121 are selected for different intensities of demagnetizing magnetic fields. This ensures that, while maintaining the rotor's resistance to demagnetization, weaker demagnetizing magnetic fields correspond to magnet components 121 with lower coercivity, and stronger demagnetizing magnetic fields correspond to magnet components 121 with higher coercivity. In other words, for weaker demagnetizing magnetic fields, magnet components 121 with lower coercivity can be used, and for stronger demagnetizing magnetic fields, magnet components 121 with higher coercivity can be used. This allows magnet materials with lower coercivity to be used, thereby improving the utilization rate of magnet materials with lower coercivity and reducing waste.

[0044] Coercivity refers to the magnetic induction intensity B of a magnetic material after saturation magnetization, which does not return to zero when the external magnetic field returns to zero. Only when a magnetic field of a certain magnitude is applied in the opposite direction of the original magnetization field can the magnetic induction intensity return to zero. This magnetic field is called the coercive magnetic field, also known as coercivity.

[0045] In addition, in some embodiments, the coercivity of the magnet assembly 121 located in the middle of the rotating shaft 11 is greater than that of the magnet assembly 121 located in other parts of the rotating shaft 11 along the axial direction of the rotating shaft 11.

[0046] Simulation and analysis of synchronous motors are performed, specifically as follows: Figures 5 to 8 As shown, the analysis conditions can be as follows: Figure 5As shown, the synchronous motor operates at the inflection point of its external characteristics before 0.009525s. At 0.009525s, the ASC active short-circuit protection is activated, and the torque of the synchronous motor enters a jittering state. At this time, the transient waveforms of the three-phase current and back EMF of the synchronous motor are as follows: Figure 6 As shown, the three-phase windings of the synchronous motor generate peak currents. Taking phase V as an example, the peak currents are 838A, 693A, and 591A, respectively, all exceeding the peak current of 580A at the stable operation of the external characteristic inflection point. These peak currents generate a reverse magnetic field acting on the rotor 10, causing irreversible demagnetization of the magnet assembly 121. (Comparison) Figure 6 From the V-phase current and V-phase back electromotive force, it can be observed that when a synchronous motor experiences a hard cut-off ASC (Automatic Switching Controller), the maximum current in each single-phase winding occurs at the zero-crossing point of this back electromotive force. Figure 6 The three back EMF zero-crossing points of the V-phase are all peak points of the high current in the V-phase winding. Analyzing the relative positions of the stator module 20 and rotor 10 of the synchronous motor, the back EMF zero-crossing point of any phase is precisely the position where the center line of the stator winding of that phase is aligned with the axis of rotor 10. For example... Figure 7 As shown, at the moment the V-phase back potential crosses zero, the neutral line of the 20V phase winding of the stator module and the N / S pole neutral line of the axial middle section topology of the rotor 10 are aligned. At this time, the transient current of the V-phase is at its maximum, resulting in the most severe demagnetization. That is, the most severe demagnetization occurs in the middle of the rotor 10, while the demagnetization at the ends of the rotor 10 is not as severe as that in the middle. Figure 8 As shown, at the moment when the V-phase back potential crosses zero, the center line of the 20V phase winding of the stator module is offset from the center line of the magnet assembly 121 by a skew angle. The magnet assembly 121 located at the end of the rotor 10 is not directly facing the maximum reverse demagnetizing magnetic field, so its demagnetization is not as severe as that of the magnet assembly 121 located in the middle. Based on the above analysis, it can be determined that the magnet assembly 121 in the middle of the rotating shaft 11 is subjected to the most severe demagnetization during rotor demagnetization, while the magnet assemblies 121 outside the middle of the rotating shaft 11 are not subjected to the same severe demagnetization as the magnet assembly 121 in the middle. Therefore, in this embodiment, along the axial direction of the rotating shaft 11, the coercivity of the magnet assembly 121 in the middle of the rotating shaft 11 is greater than that of the magnet assemblies 121 in the parts of the rotating shaft 11 other than the middle. This allows the magnet assembly 121 in the middle of the rotating shaft 11 to be formed of a magnet material with higher coercivity, while the magnet assemblies 121 in the parts outside the middle of the rotating shaft 11 can be formed of a magnet material with lower coercivity, thereby improving the utilization rate of magnet materials with lower coercivity.

[0047] In some embodiments, along the axial direction of the rotor shaft 11, a plurality of magnet assemblies 121 have a first portion 1201, a second portion 1202, and a third portion 1203, which are arranged sequentially. The coercivity of the magnet assembly 121 in the second portion 1202 is greater than that in the first portion 1201, and the coercivity of the magnet assembly 121 in the second portion 1202 is greater than that in the third portion 1203.

[0048] Since the first part 1201, the second part 1202, and the third part 1203 are arranged sequentially, the second part 1202 is effectively located between the first part 1201 and the third part 1203. Therefore, the magnet assembly 121 of the second part 1202 undergoes the most severe demagnetization during rotor demagnetization. The first part 1201 and the third part 1203 do not experience the same level of demagnetization as the magnet assembly 121 of the second part 1202. This allows the second part 1201 to... The coercivity of the magnet assembly 121 in the second part 1202 is greater than that of the magnet assembly 121 in the first part 1201, and the coercivity of the magnet assembly 121 in the second part 1202 is greater than that of the magnet assembly 121 in the third part 1203. This means that the magnet assembly 121 in the first part 1201 is formed of a magnet material with lower coercivity, and the magnet assembly 121 in the third part 1203 is formed of a magnet material with lower coercivity, which can improve the utilization rate of magnet materials with lower coercivity.

[0049] In addition, in this embodiment, along the axial direction of the rotor shaft 11, a plurality of magnet assemblies 121 have a first part 1201, a second part 1202 and a third part 1203. The first part 1201, the second part 1202 and the third part 1203 are arranged sequentially. Along the direction from the second part 1202 to the first part 1201, the coercivity of the magnet assembly 121 gradually decreases. Along the direction from the second part 1202 to the third part 1203, the coercivity of the magnet assembly 121 gradually decreases.

[0050] Since the first part 1201, the second part 1202, and the third part 1203 are arranged in sequence, the second part 1202 is located between the first part 1201 and the third part 1203. Therefore, the magnet assembly 121 of the second part 1202 is subjected to the most severe demagnetization when the rotor is demagnetized. The first part 1201 and the third part 1203 are not as subjected to severe demagnetization as the magnet assembly 121 of the second part 1202. This allows the coercivity of the magnet assembly 121 to gradually decrease along the direction from the second part 1202 to the first part 1201. In other words, the coercivity of the magnet assembly 121 gradually decreases along the axial direction of the rotating shaft 11 and along the direction from the second part 1202 to both sides of the second part 1202. The magnet assembly 121 can be formed by a magnet material with low coercivity, thereby improving the utilization rate of the magnet material with low coercivity.

[0051] In some embodiments, the plurality of magnet assemblies 121 include a first magnet assembly, a second magnet assembly, and a third magnet assembly, with the second magnet assembly located between the first and third magnet assemblies. The coercivity of the first, second, and third magnet assemblies is different. This arrangement means that adjacent magnet assemblies 121 have different coercivities along the axial direction of the shaft 11. Therefore, magnet assemblies 121 can be formed using magnet materials with different coercivities in the rotor, allowing the use of magnet materials with lower coercivities. This reduces the waste of lower coercive magnet materials, thereby improving their utilization rate.

[0052] In addition, in the embodiments of this application, the number of magnet assemblies 121 in the first part 1201 is at least one, the number of magnet assemblies 121 in the second part 1202 is one, and the number of magnet assemblies 121 in the third part 1203 is at least one.

[0053] When there are multiple magnet assemblies 121 in the first part 1201, if the coercivity of the magnet assembly 121 in the second part 1202 is greater than that of the magnet assembly 121 in the first part 1201, then the coercivity of the multiple magnet assemblies 121 in the first part 1201 can be equal; if the coercivity of the magnet assembly 121 gradually decreases along the direction from the second part 1202 to the first part 1201, then the coercivity of the magnet assembly 121 in the first part 1201 can gradually decrease along the direction from the second part 1202 to the first part 1201.

[0054] When there are multiple magnet assemblies 121 in the third part 1203, if the coercivity of the magnet assembly 121 in the second part 1202 is greater than that of the magnet assembly 121 in the third part 1203, then the coercivity of the multiple magnet assemblies 121 in the third part 1203 can be equal; if the coercivity of the magnet assembly 121 gradually decreases along the direction from the second part 1202 to the third part 1203, then the coercivity of the magnet assembly 121 in the third part 1203 can gradually decrease along the direction from the second part 1202 to the third part 1203.

[0055] Furthermore, by setting the number of magnet assemblies 121 in the second part 1202 to one, the most stringent demagnetization position of the rotor during demagnetization is determined, which is equivalent to determining the maximum coercivity required for the magnet assembly 121. Based on the maximum coercivity, the coercivity of magnet assemblies 121 in other parts can be determined, that is, the coercivity of magnet assemblies 121 in other parts is less than the coercivity of magnet assemblies 121 in the second part 1202.

[0056] In addition, in some embodiments, the coercivity of the magnet assembly 121 in the first part 1201 is different from that of the magnet assembly 121 in the third part 1203.

[0057] During rotor demagnetization, the magnetic field strength corresponding to the first part 1201 may differ from that corresponding to the third part 1203. Therefore, in this embodiment, setting the coercivity of the magnet assembly 121 in the first part 1201 to be different from that in the third part 1203 allows the coercivity of the magnet assembly 121 in the first part 1201 to match the magnetic field strength corresponding to the first part 1201, and the coercivity of the magnet assembly 121 in the third part 1203 to match the magnetic field strength corresponding to the third part 1203. This allows the magnet assembly 121 in the first part 1201 to be configured according to requirements. The coercivity of the magnet assembly 121 in the third part 1203 and the coercivity of the magnet assembly 121 can further improve the utilization rate of magnet materials with low coercivity. This avoids situations where the coercivity of the magnet assembly 121 required for the third part 1203 is less than that required for the first part 1201, or vice versa, the coercivity of the magnet assembly 121 required for the first part 1201 is less than that required for the third part 1203. In such cases, setting the coercivity of the magnet assembly 121 in the first part 1201 to be equal to that in the third part 1203 would lead to waste of magnet materials with low coercivity. In other words, by setting the coercivity of the magnet assembly 121 in the first part 1201 to be different from that in the third part 1203, the utilization rate of magnet materials with low coercivity can be improved.

[0058] In some embodiments, the second magnet assembly is located in the axial middle section of the shaft, while the first and third magnet assemblies are located at the axial ends of the shaft. This arrangement facilitates the arrangement of the magnet assemblies 121 on the shaft.

[0059] Furthermore, in some embodiments, the coercivity of the second magnet assembly is greater than that of the first magnet assembly, and the coercivity of the second magnet assembly is greater than that of the third magnet assembly. With this configuration, during rotor demagnetization, neither the first nor the third magnet assembly experiences the most severe demagnetization, thus ensuring that the coercivity of both the second and third magnet assemblies is greater than that of the first and third magnet assemblies. This allows for the first and third magnet assemblies to be formed from magnet materials with lower coercivity, improving the utilization rate of these lower-coercivity magnet materials.

[0060] It should be noted that the coercivity of the first magnet assembly and the coercivity of the third magnet assembly can be the same or different. This application does not limit this aspect in the embodiments.

[0061] In some embodiments, the coercivity of the magnet assembly gradually decreases along the axial direction of the rotating shaft, from the second magnet assembly to the first magnet assembly, and also gradually decreases along the direction from the second magnet assembly to the third magnet assembly. This arrangement effectively reduces the coercivity of the magnet assembly 121 along the axial direction of the rotating shaft 11, towards both sides of the second magnet assembly. This allows the magnet assembly 121 to be formed using a magnet material with lower coercivity, thereby improving the utilization rate of such magnet materials.

[0062] In addition, in the embodiments of this application, the coercivity of the first magnet assembly is 753 Ka / m, the coercivity of the second magnet assembly is 767 Ka / m, and the coercivity of the third magnet assembly is 739 Ka / m.

[0063] In some embodiments, each magnet assembly 121 includes multiple magnet groups 122, and each magnet group 122 includes at least two magnet sheets 123. Along the circumferential direction of the shaft 11, the multiple magnet groups 122 of each magnet assembly 121 are spaced apart around the shaft 11, and the magnet groups 122 in adjacent magnet assemblies 121 are staggered along the circumferential direction of the shaft 11. This arrangement optimizes the rotor's torque pulsation and improves the rotor's performance.

[0064] It should be noted that, in the embodiments of this application, the number of magnet pieces 123 included in each magnet group 122 can be set according to actual needs, so that the magnet pieces 123 can be arranged in different forms. For example, if each magnet group 122 includes two magnet pieces 123, the two magnet pieces 123 can be arranged in a V shape. Or, if each magnet group 122 includes three magnet pieces 123, the three magnet pieces 123 can be arranged in a U shape. The embodiments of this application do not limit this arrangement.

[0065] In addition, the misalignment of the magnet group 122 in two adjacent magnet assemblies 121 along the circumferential direction of the rotating shaft 11 means that the magnet sheet 123 in one magnet group 122 is misaligned with the magnet sheet 123 in the other magnet group 122 in the two corresponding positions of the two adjacent magnet assemblies 121.

[0066] In some embodiments, the rotor 10 further includes a rotating housing assembly 13, which is sleeved on the rotating shaft 11, and the magnet assembly 121 is embedded in the rotating housing assembly 13. By providing the rotating housing assembly 13, it is easier to install the magnet assembly 121.

[0067] In some embodiments, the rotor also includes a stator module 20, which is fitted onto the rotor 10 and is rotatable relative to the stator module 20. This arrangement facilitates the generation of driving force by the rotation of the rotor 10 relative to the stator module 20.

[0068] Furthermore, a comparison is made between the rotor provided in this application embodiment and rotors in related technologies, as shown in Table 1:

[0069] Table 1

[0070]

[0071] As shown in Table 1, the rotor in the related technology uses magnets with a coercivity of 767 Ka / m in the magnet assembly 121 of the first part 1201, the second part 1202, and the third part 1203. Under the most severe demagnetization conditions, the demagnetization areas of the first part 1201, the second part 1202, and the third part 1203 are 8.71%, 10.00%, and 7.12%, respectively. The second part 1202 is the most severely demagnetized, while the demagnetization of the first part 1201 and the third part 1203 is lower than that of the second part 1202. In this embodiment, the coercivity of the magnet assembly 121 in the first part 1201 and the third part 1203 is adjusted respectively. According to the demagnetization standard of ≤10% demagnetization of a single magnet, the coercivity of the magnet assembly 121 in the first part 1201 is determined to be 753 Ka / m, and the coercivity of the magnet assembly 121 in the third part 1203 is 739 Ka / m. Therefore, compared with the magnet assembly 121 in the related art, the coercivity of the magnet assembly 121 in the first part 1201 in this embodiment is reduced by 14 Ka / m, and the coercivity of the magnet assembly 121 in the third part 1203 is reduced by 28 Ka / m. At the same time, the rotor provided by this embodiment still meets the demagnetization requirements, that is, the back EMF decay is ≤3%, and the demagnetization of a single magnet is ≤10%. Moreover, the torque after hard cutting ASC demagnetization in the two schemes is basically the same, which shows that the coercivity of the magnet assembly 121 in the rotor can be adjusted, indicating the feasibility of the rotor provided by this embodiment.

[0072] In this embodiment, since multiple magnet assemblies 121 are distributed along the axial direction of the rotating shaft 11, and at least two magnet assemblies 121 have different coercivity along the axial direction of the rotating shaft 11, magnet assemblies 121 with different coercivity can be used along the axial direction of the rotating shaft 11. This allows magnet materials with different coercivity to be used, avoiding waste of magnet materials with lower coercivity. In other words, by setting at least two magnet assemblies 121 with different coercivity along the axial direction of the rotating shaft 11, magnet assemblies 121 with different coercivity can be formed in the rotor using magnet materials with different coercivity. This allows magnet materials with lower coercivity to be used, thereby reducing the degree of waste of magnet materials with lower coercivity and improving the utilization rate of magnet materials with lower coercivity.

[0073] This application provides an electric motor, which includes the rotor of any of the above embodiments.

[0074] This application provides an electric drive assembly that includes the motor described in the above embodiments.

[0075] This application provides a vehicle that includes the electric drive assembly described in the above embodiments.

[0076] It should be noted that, in the embodiments of this application, the types of vehicles include, but are not limited to, electric vehicles and hybrid vehicles.

[0077] This application provides a method for determining coercivity, used to determine the distribution of coercivity in the magnet assembly of the rotor in any of the above embodiments, such as... Figure 9 As shown, the determination method includes:

[0078] Step 901: Control the motor to switch to active short-circuit protection mode to demagnetize the motor and determine the transient torque waveform of the motor when it switches to active protection mode.

[0079] During motor operation, the system can control the motor to switch to active short-circuit protection mode, i.e., ASC mode, to demagnetize the motor. During this demagnetization process, the transient torque waveform of the motor can be determined. Specifically, the motor torque can be monitored in real time, allowing for the determination of the transient torque waveform during demagnetization.

[0080] In addition, in some implementations, before controlling the motor to switch to the active short-circuit protection mode, the determination method further includes: when the motor running time is greater than or equal to a preset time and the temperature of the internal components of the motor is at its highest temperature, controlling the motor to switch to the mode corresponding to the peak external characteristic inflection point, where the peak external characteristic inflection point is the highest speed operating point at which the motor outputs peak torque, wherein the motor includes a rotor assembly, the rotor includes multiple magnet assemblies, and the multiple magnet assemblies are distributed sequentially along the axial direction of the motor shaft.

[0081] Step 902: Determine the distribution of coercivity of the magnet assembly based on the transient waveform diagram.

[0082] In some implementations, step 902 can be implemented by: determining the magnitude of the demagnetizing magnetic field at different positions of the rotor on the transient waveform diagram; and determining the distribution of the magnet assembly according to the magnitude of the demagnetizing magnetic field.

[0083] In some implementations, determining the distribution of magnet components based on the magnitude of the demagnetizing magnetic field can be achieved by: sorting the demagnetizing magnets by size; and then sorting the magnet components with different coercivities according to the demagnetizing magnetic field from largest to smallest, thus determining the distribution of the magnet components. Magnet components with lower coercivity correspond to smaller demagnetizing magnetic fields, and magnet components with higher coercivity correspond to larger demagnetizing magnetic fields. By setting it up in this way, after determining the magnitude of the demagnetizing magnetic field, magnet components with different coercivities can be set according to the order of the demagnetizing magnetic field magnitude. Specifically, smaller coercive magnet components are set for smaller demagnetizing magnetic fields, and larger coercive magnet components are set for larger demagnetizing magnetic fields. This allows magnet materials with lower coercivities to be used, thereby reducing the waste of lower coercive magnet materials and improving their utilization rate.

[0084] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A rotor, characterized in that, The rotor includes: a rotating shaft and a plurality of magnet assemblies spaced apart along the axial direction of the rotating shaft, wherein at least two of the magnet assemblies have different coercivity along the axial direction of the rotating shaft.

2. The rotor according to claim 1, characterized in that, Along the axial direction of the rotating shaft, the plurality of magnet assemblies include a first magnet assembly, a second magnet assembly, and a third magnet assembly. The second magnet assembly is located between the first magnet assembly and the third magnet assembly, and the coercivity of the first magnet assembly, the second magnet assembly, and the third magnet assembly are all different.

3. The rotor module according to claim 2, characterized in that, The second magnet assembly is located in the middle section of the axial direction of the rotating shaft, while the first magnet assembly and the third magnet assembly are located at both ends of the axial direction of the rotating shaft.

4. The rotor according to claim 3, characterized in that, The coercivity of the second magnet assembly is greater than that of the first magnet assembly, and the coercivity of the second magnet assembly is greater than that of the third magnet assembly.

5. The rotor according to claim 3, characterized in that, Along the axial direction of the rotating shaft, from the second magnet assembly to the first magnet assembly, the coercivity of the magnet assembly gradually decreases, and along the direction from the second magnet assembly to the third magnet assembly, the coercivity of the magnet assembly gradually decreases.

6. The rotor according to any one of claims 1-5, characterized in that, The coercivity of the first magnet assembly is 753 Ka / m, the coercivity of the second magnet assembly is 767 Ka / m, and the coercivity of the third magnet assembly is 739 Ka / m.

7. The rotor according to claim 6, characterized in that, Each of the magnet assemblies includes multiple magnet groups, and each magnet group includes at least two magnet sheets; Along the circumferential direction of the rotating shaft, a plurality of magnet groups of each magnet assembly are distributed at intervals around the rotating shaft, and the magnet groups of two adjacent magnet assemblies are staggered along the circumferential direction of the rotating shaft.

8. An electric motor, characterized in that, The motor includes the rotor according to any one of claims 1-7.

9. An electric drive assembly, characterized in that, The electric drive assembly includes the motor as described in claim 8.

10. A vehicle, characterized in that, The vehicle includes the electric drive assembly as described in claim 9.

11. A method for determining coercivity, characterized in that, The method for determining the distribution of coercivity in the magnet assembly of any one of claims 1-7 includes: Control the motor to switch to active short-circuit protection mode to demagnetize the motor, and determine the transient torque waveform of the motor when it switches to active protection mode; Based on the transient waveform diagram, the distribution of coercivity of the magnet assembly is determined.

12. The method for determining coercivity according to claim 11, characterized in that, Before controlling the motor to switch to active short-circuit protection mode, the determination method further includes: When the motor runs for a duration greater than or equal to a preset duration and the temperature of the internal components of the motor is at its highest temperature, the motor is controlled to switch to the mode corresponding to the peak external characteristic inflection point. The peak external characteristic inflection point is the highest speed operating point at which the motor outputs peak torque. The motor includes a rotor assembly, and the rotor includes multiple magnet assemblies, which are distributed sequentially along the axial direction of the motor shaft.

13. The method for determining coercivity according to claim 11, characterized in that, Determining the distribution of coercivity of the magnet assembly based on the transient waveform includes: The magnitude of the demagnetizing magnetic field at different positions of the rotor is determined from the transient waveform diagram; The distribution of the magnet components is determined according to the magnitude of the demagnetizing magnetic field.

14. The method for determining coercivity according to claim 13, characterized in that, The step of determining the distribution of the magnet components according to the magnitude of the demagnetizing magnetic field includes: Sort the demagnetized magnets by size; According to the order of demagnetizing magnetic field from large to small, the magnet components with different coercivity are sorted to determine the distribution of the magnet components. Among them, the magnet components with small coercivity correspond to small demagnetizing magnetic fields, and the magnet components with large coercivity correspond to large demagnetizing magnetic fields.

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