A rotor assembly, electric machine and compressor

Abstract

The application provides a rotor assembly, a motor and a compressor, comprising a rotor core, the rotor core is provided with a plurality of magnetic poles, each magnetic pole has a d-axis, each magnetic pole is provided with a first magnetic group, the first magnetic group comprises two first moving permanent magnets, and the two first moving permanent magnets are arranged on two sides of the d-axis; when the rotor speed is greater than a first preset speed, the two first moving permanent magnets move towards the d-axis; when the rotor core speed is less than a second preset speed, the two first moving permanent magnets move away from the d-axis, and the second preset speed is less than the first preset speed, so that the demagnetization risk can be reduced while improving the stability of high-speed operation of the permanent magnet synchronous motor.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, specifically relating to a rotor assembly, a motor, and a compressor. Background Technology

[0002] Permanent magnet synchronous motors have advantages such as high efficiency, high power factor and high reliability. However, when running at high speed, the high magnetic flux can cause the speed to be unstable. Weakening control is required to maintain a steady speed, but this control method will increase the operating current, reduce efficiency and increase the risk of demagnetization.

[0003] How to improve the stability of permanent magnet synchronous motors at high speeds while reducing the risk of demagnetization is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] Therefore, the present invention provides a rotor assembly, a motor, and a compressor that can improve the stability of high-speed operation of a permanent magnet synchronous motor while reducing the risk of demagnetization.

[0005] In a first aspect, the present invention provides a rotor assembly including a rotor core, wherein the rotor core is provided with a plurality of magnetic poles, each magnetic pole having a d-axis, and each magnetic pole being provided with a first magnetic group, the first magnetic group including two first movable permanent magnets disposed on both sides of the d-axis; when the rotor speed is greater than a first preset speed, the two first movable permanent magnets move toward the d-axis, and when the rotor core speed is less than a second preset speed, the two first movable permanent magnets move away from the d-axis, wherein the second preset speed is less than the first preset speed.

[0006] In some embodiments, each magnetic pole is further provided with two sliders that are movable in the radial direction, the sliders being arranged corresponding to the first movable permanent magnet; when the rotor core rotation speed is greater than a first preset rotation speed, the sliders can be moved toward the outer edge of the rotor core, and the movement of the sliders toward the outer edge of the rotor core can drive the first movable permanent magnet adjacent to the sliders to move toward the d-axis.

[0007] In some embodiments, a first compression spring is provided between two first movable permanent magnets, which can compress the first compression spring when the first movable permanent magnet moves toward the d-axis.

[0008] In some embodiments, the midpoint of the first compression spring is aligned with the d-axis and fixed to the rotor core, and the two ends of the first compression spring are respectively connected to two first movable permanent magnets.

[0009] In some embodiments, the rotor core is provided with a slide rail that extends along the radial direction of the rotor core, and the slider is slidably disposed within the slide rail. The slide rail has an inner opening at one end facing the center of the rotor core.

[0010] In some embodiments, the slide rail has an outer opening at one end facing the outer edge of the rotor core, and an elastic element is provided between the outer opening and the slider.

[0011] or,

[0012] The slide is closed at one end facing the outer edge of the rotor core.

[0013] In some embodiments, each magnetic pole is further provided with a second magnetic group, the second magnetic group including two second movable permanent magnets, the two second movable permanent magnets being disposed on both sides of the d-axis; in the radial direction of the rotor core, the second magnetic group is disposed outside the first magnetic reluctance; when the rotational speed of the rotor core is greater than a third preset speed, the two second movable permanent magnets move toward the d-axis; when the rotor rotational speed is less than a fourth preset speed, the two second movable permanent magnets move away from the d-axis; the third preset speed is greater than the first preset speed; the fourth preset speed is less than the third preset speed and greater than the first preset speed.

[0014] In some embodiments, each magnetic pole is further provided with a fixed permanent magnet, which is disposed inside the first magnetic group in the radial direction of the rotor core.

[0015] In a second aspect, the present invention also provides an electric motor, including the rotor assembly described above.

[0016] Thirdly, the present invention also provides a compressor, including a motor.

[0017] This invention enables two first movable permanent magnets of each magnetic pole of the rotor core to move closer to the d-axis at high rotor core speeds and further away from the d-axis at low rotor core speeds. Furthermore, as the rotor core speed increases from low to high, the first movable permanent magnets gradually move closer to the d-axis. This results in a lower magnetic field at higher rotor core speeds, significantly reducing or even eliminating the need for field weakening control. This effectively lowers the risk of demagnetization of the permanent magnets in the rotor core and reduces power consumption at high rotor core speeds. Motors using this rotor assembly belong to the strategic emerging industries sector and possess energy-saving and environmentally friendly technical benefits. Attached Figure Description

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the rotor core according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the first and second magnetic groups of this invention being inserted into the slide rails in an embodiment of the invention.

[0021] Figure 3 This is an embodiment of the present invention. Figure 2 A schematic diagram of the magnetic field distribution generated by the magnetic poles of the rotor core under the specified conditions;

[0022] Figure 4 This is a schematic diagram of the first magnetic assembly being pushed out of the slide by the slider in an embodiment of the present invention;

[0023] Figure 5 This is an embodiment of the present invention. Figure 4 A schematic diagram of the magnetic field distribution generated by the magnetic poles of the rotor core under the specified conditions;

[0024] Figure 6 This is a schematic diagram of the first and second magnetic groups being squeezed out of the slide in an embodiment of the present invention.

[0025] Figure 7 This is an embodiment of the present invention. Figure 6 A schematic diagram of the magnetic field distribution generated by the magnetic poles of the rotor core under the specified conditions;

[0026] The attached figures are labeled as follows:

[0027] 1. First magnetic group; 2. Second magnetic group; 101. First movable permanent magnet; 201. Second movable permanent magnet; 1011. First compression spring; 2011. Second compression spring; 3. Rotor core; 4. Slider; 5. Slide rail; 501. Inner opening; 502. Outer opening; 503. Insertion hole; 6. Elastic element; 7. Carrier block; 8. Fixed permanent magnet. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms 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 on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0030] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0031] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0032] Permanent magnet synchronous motors have advantages such as high efficiency, high power factor and high reliability. However, when running at high speed, the high magnetic flux can cause the speed to be unstable. Weakening control is required to maintain a steady speed, but this control method will increase the operating current, reduce efficiency and increase the risk of demagnetization.

[0033] To improve the stability of permanent magnet synchronous motors during high-speed operation while reducing the risk of demagnetization, this application provides a rotor assembly, such as... Figure 1-7 As shown, the rotor core 3 includes a rotor core 3 with multiple magnetic poles, each magnetic pole having a d-axis and a first magnetic group 1. The first magnetic group 1 includes two first movable permanent magnets 101, which are disposed on both sides of the d-axis. When the rotor speed is greater than a first preset speed, the two first movable permanent magnets 101 move toward the d-axis. When the rotor core 3 speed is less than a second preset speed, the two first movable permanent magnets 101 move away from the d-axis. The second preset speed is less than the first preset speed.

[0034] The rotor assembly of this application can dynamically adjust the position of the first moving permanent magnet 101 according to the rotor speed, so as to realize the real-time adjustable permanent magnet flux of the rotor. Under low speed conditions, the permanent magnet is far away from the d-axis to maintain a large excitation magnetic field to ensure low-speed torque output. Under high speed conditions, the permanent magnet moves closer to the d-axis to automatically weaken the excitation magnetic field. It can adapt to the wide speed operation requirements without relying on high-intensity field weakening control, avoid the problem of current surge and efficiency decay in the high-speed section, and reduce the risk of permanent magnet demagnetization.

[0035] Specifically, by setting a first movable permanent magnet 101 on each side of the d-axis of the rotor core 3, when the rotor core 3 rotates at a speed greater than a first preset speed, the two first movable permanent magnets 101 move towards the d-axis; when the rotor core 3 rotates at a speed less than a second preset speed, the two first movable permanent magnets 101 move away from the d-axis, and the second preset speed is less than the first preset speed. In this way, the magnetic field range of the magnetic poles on the rotor core 3 can be adjusted.

[0036] When the rotational speed of the rotor core 3 increases (greater than the first preset speed), the two first moving permanent magnets 101 move closer to the d-axis, reducing the magnetic field range. Consequently, the excitation magnetic field provided by the rotor core 3 also decreases, thereby significantly reducing field weakening control or even eliminating it entirely. This eliminates the current surge and efficiency decay caused by field weakening control, ultimately reducing the difficulty of motor control, lowering the risk of permanent magnet demagnetization, and improving the rotational stability of the rotor core 3. Consequently, it also improves the operational stability of the motor using the rotor core 3. Because the risk of permanent magnet demagnetization is reduced, the service life of the rotor core 3 is also increased, which is beneficial for energy saving. The motor using the rotor core 3 of this application has low energy consumption and belongs to the energy-saving equipment category, which is in the strategic emerging industry field and has energy-saving and environmentally friendly technical effects.

[0037] Furthermore, the two first moving permanent magnets 101 are always symmetrical about the d-axis.

[0038] The rotor core 3 is made of stacked silicon steel sheets.

[0039] Preferred, such as Figure 1 , Figure 2 , Figure 4 and Figure 7 As shown, each magnetic pole is also provided with two sliders 4 that can move in the radial direction. The sliders 4 are correspondingly arranged with the first movable permanent magnet 101. When the rotational speed of the rotor core 3 is greater than the first preset rotational speed, the sliders 4 can move toward the outer edge of the rotor core 3. The movement of the sliders 4 toward the outer edge of the rotor core 3 can drive the first movable permanent magnet 101, which is close to the sliders 4, to move toward the d-axis.

[0040] The first moving permanent magnet 101 is directly driven to move toward the d-axis by the squeezing action of the slider 4. The transmission path is short and the response speed is fast. The excitation magnetic field can be dynamically adjusted synchronously with the speed change. It is suitable for the speed fluctuation scenario of the compressor with the change of operating conditions. The adjustment process is precise and does not require additional control of energy consumption.

[0041] Preferred, such as Figure 1 , Figure 2 , Figure 4 and Figure 7 As shown, a first compression spring 1011 is provided between the two first movable permanent magnets 101, and the first compression spring 1011 can be compressed when the first movable permanent magnet 101 moves toward the d-axis.

[0042] The first compression spring 1011 can provide a reverse buffer force and store elastic potential energy when the two first moving permanent magnets 101 move towards the d-axis. On the one hand, it can prevent the permanent magnets from moving too much and colliding. On the other hand, it can provide a stabilizing force for the subsequent reset of the permanent magnets, ensuring that the two permanent magnets can move smoothly away from the d-axis in sync when the speed decreases. This allows the excitation magnetic field to quickly recover to the large magnetic flux state as the speed drops, ensuring efficient and stable operation in the low-speed range.

[0043] Preferred, such as Figure 1 , Figure 2 , Figure 4 and Figure 7 As shown, the midpoint of the first compression spring is aligned with the d-axis and fixed to the rotor core 3, and the two ends of the first compression spring are respectively connected to two first movable permanent magnets 101.

[0044] The symmetrical fixing structure of the compression spring can ensure that the forces on the two first moving permanent magnets 101 are completely balanced. During the movement process, the two magnets are always symmetrically arranged around the d-axis, avoiding magnetic field distortion caused by displacement deviation of the permanent magnets on both sides, ensuring the sinusoidal nature of the air gap magnetic field, reducing motor vibration and noise, extending the service life of the compression spring, and improving the reliability of the rotor in long-term operation.

[0045] Preferred, such as Figure 1 , Figure 2 , Figure 4 and Figure 7 As shown, the rotor core 3 is provided with a slide rail 5, which extends along the radial direction of the rotor core 3. The slider 4 is slidably disposed in the slide rail 5, and the end of the slide rail 5 facing the center of the rotor core 3 is provided with an inner opening 501.

[0046] By setting the slide rail 5, the slider 4 can move stably along the radial direction. This improves the stability of the permanent magnet's movement, thereby enabling the magnetic assembly to provide a stable and changing magnetic field.

[0047] The slider 4 is sealed and slidably disposed within the slide rail 5, with an opening at one end of the slide rail 5 facing the center of the rotor core 3. When the rotor assembly is applied to the compressor, the higher the rotor speed and the higher the compressor's operating frequency, the greater the gas pressure generated. High-pressure gas enters through the inner opening 501 and pushes the slider 4 towards the outer edge of the rotor core 3, thereby causing the slider 4 to push the permanent magnet towards the d-axis. Thus, the movement of the slider 4 is directly related to the operating frequency of the compressor in which the rotor assembly is applied, improving the slider 4's response rate to changes in the rotor core 3's speed, and correspondingly, enhancing the correlation between the slider 4 and the compressor's operating frequency. This effectively improves the timeliness of changes in the magnetic field generated by the two first moving permanent magnets 101 (synchronous changes in magnetic field area and magnetic field strength), improves the stability of compressor operation, and contributes to improving the stability and reliability of the high-pressure gas output by the compressor.

[0048] Preferred, such as Figure 1 , Figure 2 , Figure 4 and Figure 7 As shown, the slide rail 5 has an outer opening 502 at one end facing the outer edge of the rotor core 3, and an elastic element 6 is provided between the outer opening 502 and the slider 4.

[0049] or,

[0050] The slide 5 is closed at one end facing the outer edge of the rotor core 3.

[0051] Example 1: The slide rail 5 has an outer opening 502 at one end facing the outer edge of the rotor core 3, and an elastic element 6 is provided between the outer opening 502 and the slider 4. The movement of the slider 4 towards the outer edge of the rotor core 3 allows the elastic element 6 to store elastic potential energy. When the rotational speed of the rotor core 3 decreases, the elastic element 6 can push the slider 4 towards the center of the rotor core 3, thereby improving the timeliness and stability of the slider 4's movement. This elastic element 6 can counteract the centrifugal force on the slider 4 under low-speed operating conditions, driving the slider 4 to automatically reset towards the rotor center, releasing the squeezing driving effect on the first moving permanent magnet 101, allowing the permanent magnet to synchronously return to its initial position away from the d-axis, quickly restoring the high-excitation magnetic field state, and achieving fully autonomous switching between "high-speed automatic demagnetization and low-speed automatic magnetization" without additional manual intervention, adapting to usage scenarios where the compressor frequently starts and stops and operates under varying conditions.

[0052] Example 2: By "closing one end of the slide rail 5 toward the outer edge of the rotor core 3", when the slider 4 moves toward the outer edge of the rotor core 3, the gas between the slider 4 and the closed end is compressed because the slide rail 5 is closed at the outer edge. When the rotational speed of the rotor core 3 decreases, the compressed gas can act on the slider 4 to push the slider 4 toward the center of the rotor core 3, realizing the fully autonomous switching of "high-speed automatic demagnetization and low-speed automatic magnetization".

[0053] Furthermore, the slider 4 is provided with a pressing surface, and the first movable permanent magnet 101 is provided on the carrier block 7. When the slider 4 slides toward the outer edge of the rotor core 3, the pressing surface can press the carrier block 7 to move toward the d-axis.

[0054] Preferred, such as Figure 1 , Figure 2 , Figure 4 and Figure 7 As shown, each magnetic pole is also provided with a second magnetic group 2, which includes two second movable permanent magnets 201, which are arranged on both sides of the d-axis. In the radial direction of the rotor core 3, the second magnetic group 2 is arranged outside the first magnetic reluctance. When the rotational speed of the rotor core 3 is greater than the third preset speed, the two second movable permanent magnets 201 move toward the d-axis. When the rotor rotational speed is less than the fourth preset speed, the two second movable permanent magnets 201 move away from the d-axis. The third preset speed is greater than the first preset speed, and the fourth preset speed is less than the third preset speed and greater than the first preset speed.

[0055] The graded adjustment structure of the double-layer movable magnetic group can weaken the excitation magnetic field step by step in different speed ranges. In the medium and high speed range, the first magnetic group 1 completes the first stage of demagnetization, and in the ultra-high speed range, the second magnetic group 2 completes the second stage of deep demagnetization, further suppressing the magnetic flux density to below 1.2T, greatly expanding the upper limit of the motor's operating frequency, achieving stable operation in ultra-high speed scenarios, and effectively solving the problems of high difficulty in field weakening control and high demagnetization risk when the permanent magnet motor is running at ultra-high speed.

[0056] A second compression spring 2011 is provided between the two second movable permanent magnets 201.

[0057] Furthermore, a third and fourth magnetic group can be set as needed, with the arrangement of different magnetic groups being the same as that of the first magnetic group 1. Different rotational speeds of the rotor core 3 can cause different numbers of permanent magnets to move toward the d-axis, and can also change the distance between at least one magnetic group and the d-axis in real time.

[0058] Preferred, such as Figure 1 , Figure 2 , Figure 4 and Figure 7 As shown, each magnetic pole is also provided with a fixed permanent magnet 8, which is located inside the first magnetic group 1 in the radial direction of the rotor core 3.

[0059] The fixed permanent magnet 8 on the inner side can provide basic excitation flux. When both sets of moving permanent magnets move to the vicinity of the d-axis and the excitation magnetic field drops to its minimum, a stable basic magnetic field can still be maintained, avoiding the "demagnetization" problem of the motor and ensuring that the motor can maintain stable torque output when running at ultra-high speed. At the same time, it can optimize the magnetic circuit distribution, reduce the risk of local magnetic saturation of the rotor core 3, and further improve the operating efficiency of the motor across the entire speed range.

[0060] This application provides an electric motor, including the aforementioned rotor assembly.

[0061] The permanent magnet synchronous motor equipped with this adjustable magnetic field rotor assembly breaks through the performance limitations of the fixed magnetic flux of traditional permanent magnet motors. It can maintain high efficiency across the entire speed range. The large magnetic flux at low speed ensures high torque and high energy efficiency, while the automatic demagnetization at high speed eliminates the need for strong and weak magnetic field control. The operating current is significantly reduced, and the risk of demagnetization is greatly reduced. It effectively avoids the risks of operating current surge, efficiency decay, and permanent magnet demagnetization. At the same time, it can achieve a speed range far exceeding that of conventional permanent magnet motors, making it suitable for various wide-speed operation application scenarios.

[0062] The centrifugal force generated by the rotation of the rotor core 3 can be used as the driving force for the slider 4. The radial automatic displacement of the slider 4 can be achieved without the need for additional electromagnetic drive components. The structure is simple and highly reliable.

[0063] This application also provides a compressor, including the aforementioned motor.

[0064] This compressor can rely on the dynamic magnetic field adjustment characteristics of the motor, combined with the strong correlation between its internal air pressure, speed and operating conditions, to achieve real-time and precise control of the excitation magnetic field. Under all operating conditions, the motor is always in the high-efficiency operating range, which greatly reduces the compressor's operating energy consumption. At the same time, the ultra-high speed and stable operation capability can further improve the compressor's volumetric efficiency, broaden the compressor's operating condition adaptability range, and significantly improve the overall operational reliability and service life.

[0065] The motor also includes a stator, with the rotor core 3 housed within the stator, forming an annular air gap between the rotor core 3 and the stator. When the motor is used in a compressor, the entire motor is located within the compressor housing. During compressor operation, the housing is under high pressure, and the air pressure in the central region of the rotor core 3 is greater than the air pressure near the air gap. Thus, as the compressor's operating frequency increases (the rotor core 3's rotational speed increases), the pressure difference between the central region of the rotor core 3 and the air gap increases (the pressure difference between the inner opening 501 and the outer opening 502 of the slide rail 5 mentioned above increases). The pressure on the side of the slider 4 facing the rotor core 3 can push the slider 4 towards the outer edge of the rotor core 3, thereby moving the permanent magnet towards the d-axis. Therefore, the movement of the slider 4 in this application not only utilizes the centrifugal force of the rotor core 3's rotation but also utilizes the pressure difference at both ends of the slide rail 5 to drive the slider 4's movement, ensuring the stability of the slider 4's operation. Regulation is achieved through internal compressor air pressure adjustment, a simple adjustment method, and the air pressure is strongly correlated with the rotational speed at different frequencies and different operating conditions, enabling real-time, precise, and efficient control. This directly links the movement of slider 4 to the operating frequency of the compressor without requiring additional control. This improves the closeness between the compressor's operation and the changes in the magnetic field formed by the permanent magnet, thereby enhancing the reliability and stability of the compressor's operation. It can also effectively reduce the risk of motor demagnetization and reduce energy consumption.

[0066] When the rotor core 3 rotates at a low speed, the magnetic field shape of the magnetic poles is roughly "V" shaped, with the largest lateral coverage area and the largest excitation magnetic field provided by the rotor core 3. When the internal air pressure of the compressor increases, the air pressure and centrifugal force drive the sliding block in the slide rail 5 to move. As the air pressure changes, the displacement of the slider 4 in the slide rail 5 also changes. When the track sliding block pushes open the permanent magnet sliding block, the central magnetic field of the permanent magnet in the movable permanent magnet layer is covered, that is, it changes to a "V" shaped arrangement with different angles. The angle between the magnetic field center line of the permanent magnet and the D-axis also continuously decreases, and the excitation magnetic field provided by the rotor also continuously decreases synchronously. The magnetic field range begins to shrink. When the magnetic field center lines of the two permanent magnets in the movable permanent magnet layer are parallel to the D-axis, the magnetic field shape is defined as "I-shaped". At this time, the excitation magnetic field provided by the rotor is the smallest, and the magnetic field range is the smallest, finally reaching the set minimum value.

[0067] Specifically, during the low-frequency operation phase of the compressor: the permanent magnets are arranged in a "V-shape" to maximize the excitation magnetic field strength, ensuring the motor's magnetic flux density remains stable above 1.8 T. This guarantees the motor operates in its high-efficiency range, significantly improving low-speed torque output and energy efficiency. During the high-frequency operation phase: the permanent magnets are switched to a "straight line" arrangement, effectively reducing the excitation magnetic field and suppressing the magnetic flux density to below 1.2 T, greatly reducing the difficulty of speed regulation. This design allows the motor to completely avoid reliance on field weakening control in the high-frequency range, directly maintaining stable speed. It eliminates current surges and efficiency degradation caused by field weakening control, while effectively reducing the risk of permanent magnet demagnetization.

[0068] When the compressor motor operates, the gas pressure gradually decreases from the center of the motor outwards. A socket 503 is provided on the side of the slide rail facing the moving permanent magnet, into which the carrier block 7 can be inserted.

[0069] like Figure 3 , Figure 5 and Figure 7 As shown, when the compressor is operating at low frequency, i.e., in the initial state of minimum air pressure, the slider 4 is located near the center of the rotor core 3. At this time, one end of the carrier block 7 is inserted into the insertion hole 503, and the limiting block assembly set in the slide rail 5 limits the slider 4. The compression spring between the two moving permanent magnets is in a relaxed state. The magnetic field shape at this time is defined as "V-shaped". At this time, the lateral coverage area is the largest, and the excitation magnetic field provided by the rotor is the largest. Figure 2 and Figure 3 As shown, the carrier blocks of the first permanent magnet 101 and the second permanent magnet 201 are both inserted into the socket 503, and the coverage area of ​​the magnetic field path formed by the fixed permanent magnet 8, the first permanent magnet 101 and the second permanent magnet 201 is S1.

[0070] As the compressor's operating frequency increases, meaning the rotor core 3's rotational speed gradually increases, the internal air pressure of the compressor increases. Consequently, the pressure difference between the inner opening 501 and outer opening 502 of the slide rail 5 also gradually increases. This air pressure (along with centrifugal force) pushes the slider 4 in the slide rail 5 towards the outer edge of the rotor core 3. During this movement, as the slider 4 pushes open the carrier block 7 containing the first moving permanent magnet 101, the limiting block assembly is also pushed open. As the first moving permanent magnet 101 gradually moves towards the d-axis, the compression spring is continuously compressed, and the magnetic field range begins to shrink, changing into a "V-shaped" arrangement with different angles. The excitation magnetic field (magnetic field area and magnetic field strength) provided by the rotor also decreases accordingly. Figure 4 and Figure 5 As shown, the coverage area of ​​the magnetic field path formed by the fixed permanent magnet 8, the first permanent magnet 101, and the second permanent magnet 201 is S2.

[0071] The internal air pressure and centrifugal force of the compressor gradually increase until the carrier block 7 containing the first moving permanent magnet 101 is completely pushed out of the slide rail 5. The rotational speed of the compressor rotor core 3 continues to increase, and the slider 4 continues to slide along the slide rail 5. Eventually, the slider 4 will also completely push the carrier block 7 containing the second moving permanent magnet 201 out of the slide rail 5. When the center lines of the permanent magnet magnetic fields of the first moving permanent magnet 101 and the second moving permanent magnet 201 are both parallel to the D-axis, the magnetic field shape is defined as "I-shaped". At this time, the excitation magnetic field provided by the rotor is the minimum, and the magnetic field range is the minimum, finally reaching the set minimum value. The slider 4 is restricted by the elastic element 6. The force acting on the slider 4 by the elastic element 6 is balanced with the internal air pressure and centrifugal force of the compressor, and the slider 4 no longer moves; Figure 6 and Figure 7 As shown, the coverage area of ​​the magnetic field path formed by the fixed permanent magnet 8, the first permanent magnet 101, and the second permanent magnet 201 is S3. S1>S2>S3.

[0072] When the air pressure decreases, the centrifugal force decreases as the elastic element 6 and the compression spring release their elastic potential energy, causing the slider 4 and the carrier block 7 of the permanent magnet to reset, thus achieving dynamic adjustment. By adjusting the position of the permanent magnet, the excitation magnetic field of the motor can be adjusted, and the magnitude of the excitation magnetic field can be controlled as needed.

[0073] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A rotor assembly comprising a rotor core (3), the rotor core (3) having a plurality of magnetic poles, each magnetic pole having a d-axis, characterized in that, Each magnetic pole is provided with a first magnetic group (1), the first magnetic group (1) includes two first movable permanent magnets (101), the two first movable permanent magnets (101) are arranged on both sides of the d-axis; when the rotor speed is greater than the first preset speed, the two first movable permanent magnets (101) move toward the d-axis; when the rotor core (3) speed is less than the second preset speed, the two first movable permanent magnets (101) move away from the d-axis, the second preset speed is less than the first preset speed.

2. The rotor assembly according to claim 1, characterized in that, Each magnetic pole is also provided with two sliders (4) that can move in the radial direction. The sliders (4) are corresponding to the first movable permanent magnet (101). When the rotation speed of the rotor core (3) is greater than the first preset rotation speed, the sliders (4) can move towards the outer edge of the rotor core (3). The movement of the sliders (4) towards the outer edge of the rotor core (3) can drive the first movable permanent magnet (101) that is close to the sliders (4) to move towards the d-axis.

3. The rotor assembly according to claim 2, characterized in that, A first compression spring (1011) is provided between the two first movable permanent magnets (101), which can compress the first compression spring (1011) when the first movable permanent magnet (101) moves toward the d-axis.

4. The rotor assembly according to claim 3, characterized in that, The midpoint of the first compression spring (1011) is combined with the d-axis and fixed on the rotor core (3). The two ends of the first compression spring (1011) are respectively connected to two first movable permanent magnets (101).

5. The rotor assembly according to claim 2, characterized in that, The rotor core (3) is provided with a slide (5), the slide (5) extends along the radial direction of the rotor core (3), the slider (4) is provided in the slide (5) in a sealable and slidable manner, and the slide (5) is provided with an inner opening (501) at one end facing the center of the rotor core (3).

6. The rotor assembly according to claim 5, characterized in that, The slide (5) has an outer opening (502) at one end facing the outer edge of the rotor core (3), and an elastic element (6) is provided between the outer opening (502) and the slider (4). or, The slide (5) is closed at one end toward the outer edge of the rotor core (3).

7. The rotor assembly according to any one of claims 1-6, characterized in that, Each magnetic pole is also provided with a second magnetic group (2), the second magnetic group (2) includes two second movable permanent magnets (201), the two second movable permanent magnets (201) are arranged on both sides of the d-axis; in the radial direction of the rotor core (3), the second magnetic group (2) is arranged outside the first magnetic reluctance. When the rotational speed of the rotor core (3) is greater than the third preset speed, the two second movable permanent magnets (201) move toward the d-axis. When the rotational speed of the rotor is less than the fourth preset speed, the two second movable permanent magnets (201) move away from the d-axis. The third preset speed is greater than the first preset speed, and the fourth preset speed is less than the third preset speed and greater than the first preset speed.

8. The rotor assembly according to claim 7, characterized in that, Each magnetic pole is also provided with a fixed permanent magnet (8), which is located inside the first magnetic group (1) in the radial direction of the rotor core (3).

9. An electric motor, characterized in that, Includes the rotor assembly as described in any one of claims 1-8.

10. A compressor, characterized in that, Includes the motor as described in claim 9.

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