A self-starting permanent magnet motor rotor and a self-starting permanent magnet motor

Abstract

This invention discloses a self-starting permanent magnet motor rotor and a self-starting permanent magnet motor, relating to the field of motor technology. The invention includes guide bar slots arranged in a circular array on the edge of the rotor laminations; and guide bars uniformly distributed in space within the guide bar slots. The relationship between the number of guide bars and the number of guide bar slots is: number of guide bars / number of guide bar slots = (t-1) / t, where t is only 2, 3, or 4. By employing the optimized structure proposed in this invention, the number of rotor guide bars is reduced to 3 / 4 of the number of guide bar slots, successfully reducing the starting current multiple to 7 times, enabling successful load starting of the self-starting motor. The proposed structure / method can significantly reduce the starting current of the self-starting permanent magnet synchronous motor, reduce the impact on the power grid during motor starting, and reduce the impact on other electrical equipment in the same power grid.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, and in particular relates to a self-starting permanent magnet motor rotor and a self-starting permanent magnet motor. Background Technology

[0002] A self-starting permanent magnet synchronous motor is a specially designed synchronous motor that combines the high efficiency of a permanent magnet synchronous motor with the self-starting capability of an asynchronous motor. It is typically used in applications requiring high starting torque and efficient operation.

[0003] While self-starting permanent magnet synchronous motors (PMSMs) offer advantages in starting and operating efficiency, they may generate a larger starting current compared to ordinary induction motors. This is primarily due to the motor's need to overcome the rotor's static inertia and load resistance during startup to generate sufficient starting torque. However, this larger starting current can lead to several drawbacks and application limitations: it can impact the power grid, causing voltage fluctuations and affecting the normal operation of other equipment on the same grid; it increases energy loss during startup, reducing system efficiency; it causes overheating in the motor windings and power supply lines, which, if not properly cooled, can affect the lifespan of the motor's insulation materials and even damage the motor; and the larger starting current and torque can exert significant mechanical stress on the motor and the driven machinery, impacting equipment lifespan. Furthermore, in high-power industrial motors, ordinary induction motors typically use reduced-voltage soft starting, while self-starting PMSMs cannot.

[0004] For example, Chinese patent CN203883721U discloses a compensating voltage regulator for a self-starting permanent magnet synchronous motor for an oil pumping unit, which allows the voltage regulator controller to be connected in series with the motor circuit and operate at a set voltage. Another example is Chinese patent CN104578612A, which discloses a method for solving the heat dissipation of the starting cage bars of a large self-starting rare earth permanent magnet synchronous motor. Chinese patent CN111162649A discloses a high-efficiency cast copper self-starting permanent magnet motor, which reduces the impact of motor starting on the power grid or transformer by improving the motor rotor. Chinese patent CN109149815B discloses a hybrid solid and laminated permanent magnet rotor structure, which divides the rotor core into two parts: a solid body and a laminated body, so that the self-starting permanent magnet synchronous motor can ensure a sufficiently large starting torque while reducing the starting current.

[0005] Furthermore, self-starting permanent magnet motors require sufficient embedding capability. Because the rotor of a self-starting motor contains permanent magnets, its starting process is more complex than that of an induction motor. During starting, both average torque and pulsating torque are present, and the amplitude of these torques varies with the motor's speed and position. Additionally, the motor startup involves ultra-transient current, and currently, few testing stations in China are capable of full-voltage, full-current testing; generally, derating and current-reducing tests are performed according to standards. Therefore, high-power self-starting permanent magnet synchronous motors suffer from a series of problems, including inaccurate calculation and measurement of the starting current.

[0006] Furthermore, due to a series of issues such as inaccurate calculation of the starting current and insufficient testing capabilities of high-power self-starting permanent magnet synchronous motors, if the motor exhibits problems such as high starting current and tripping of the integrated protection system in the application field, the only solution is generally to attempt to reduce the starting current ratio by changing the conductor bars and end ring material. However, this method will increase the starting torque ratio of the self-starting permanent magnet motor and reduce its engagement capability. An increased starting torque ratio will cause significant impact on the motor coupling and shaft, potentially leading to shaft breakage and engine failure. Conversely, a reduced engagement capability will make it difficult for the motor to engage synchronously, reducing its starting capacity under load, and in severe cases, causing loss of synchronization and demagnetization.

[0007] Therefore, the present invention provides a self-starting permanent magnet motor rotor and a self-starting permanent magnet motor, which can effectively reduce these defects and application limitations, and enable the motor to perform at its best in various applications. Utility Model Content

[0008] The purpose of this invention is to provide a self-starting permanent magnet motor rotor and a self-starting permanent magnet motor. Based on the proposed self-starting permanent magnet motor rotor structure, the existing problems are solved, effectively reducing the motor starting current while minimizing the impact on the motor's starting torque multiple and embedding capability.

[0009] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0010] As the first aspect provided by the present invention, the present invention is a self-starting permanent magnet motor rotor, comprising: guide bar grooves, the guide bar grooves being formed in a circumferential array at the edge of the rotor laminations; guide bars, the guide bars being uniformly distributed in space and installed in the guide bar grooves; the relationship between the number of guide bars and the number of guide bar grooves is: number of guide bars / number of guide bar grooves = (t-1) / t, and t is only 2, 3, or 4.

[0011] Furthermore, the guide bars are connected to each other via end rings.

[0012] Furthermore, the end ring is made of brass T2Y or copper Grass.

[0013] Furthermore, the guide bar is made of brass T2Y.

[0014] Furthermore, it also includes several magnet units arranged in a circumferential array along the central shaft hole of the rotor lamination, each of the magnet units comprising several magnets in an "I" or "V" shaped structure.

[0015] Furthermore, the rotor lamination is provided with magnet slots that cooperate with magnets, and two adjacent magnet slots are not connected to each other.

[0016] Furthermore, there are 4 magnets on 1 / 4 of the rotor lamination, the magnets are in the form of an "I" shape, and the 4 magnets are on the same straight line;

[0017] On the complete rotor lamination, the four sets of magnet units are arranged in a square.

[0018] Furthermore, when t=2, there is an empty guide bar groove between two adjacent guide bars, and on 1 / 4 of the rotor lamination, one guide bar groove on each side is empty and the other is equipped with a guide bar.

[0019] Furthermore, when t=4, the three adjacent guide bars form a group, and there is an empty guide bar slot between each pair of adjacent groups; and on 1 / 4 of the rotor lamination, one of the guide bar slots on both sides is empty and the other is equipped with a guide bar.

[0020] As a second aspect of the present invention, the present invention is a self-starting permanent magnet motor, the motor comprising a stator and a self-starting permanent magnet motor rotor as described in the first aspect.

[0021] The present invention has the following beneficial effects:

[0022] The relationship between the number of conductor bars and the number of conductor bar slots in this invention is: number of conductor bars / number of conductor bar slots = (t-1) / t, where t is only 2, 3, or 4. The structure / method proposed in this invention can significantly reduce the starting current of the self-starting permanent magnet synchronous motor, reduce the impact on the power grid during motor startup, and reduce the impact on other electrical equipment in the same power grid.

[0023] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1This is a schematic diagram of the structure of the present invention where the number of rotor bars is 1 / 2 of the number of bar slots;

[0026] Figure 2 This is a schematic diagram of the structure of the present invention where the number of rotor bars is 3 / 4 of the number of bar slots;

[0027] Figure 3 The stall current curve is for a conventional structure.

[0028] Figure 4 The stall current curve is for a rotor with 3 / 4 the number of bar slots as described in this invention.

[0029] The attached diagram lists the components represented by each number as follows:

[0030] 1-Rotor lamination, 2-Magnet slot, 3-Magnet, 4-Guide bar, 5-Guide bar slot. Detailed Implementation

[0031] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0032] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0033] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0034] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0035] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0037] Example 1:

[0038] As an embodiment of the present invention, the present invention is a self-starting permanent magnet motor rotor, comprising: rotor laminations 1, magnet slots 2, magnets 3, guide bars 4, and guide bar slots 5; the high-power self-starting permanent magnet synchronous motor has a pole pair number 2p = 4, 6, 8, 10, as shown below. Figure 1 It has 4 poles. Figure 1 It has a 1 / 4 rotor structure. The conductor bars 4 are made of brass T2Y, and the magnets 3 adopt an "I" type structure or a "V" type structure. All conductor bars are short-circuited through end rings, and the end rings are preferably made of brass T2Y or copper Grass.

[0039] As an embodiment of the present invention, preferably, the guide bar grooves 5 are arranged in a circular array at the edge of the rotor lamination 1; the guide bars 4 are evenly distributed in space and installed in the guide bar grooves 5; the relationship between the number of guide bars 4 and the number of guide bar grooves 5 is: number of guide bars 4 / number of guide bar grooves 5 = (t-1) / t, and t is only 2, 3, or 4.

[0040] As an embodiment of the present invention, preferably, the number of rotor bars is (t-1) / t of the number of bar slots, where t can only be 2, 3, or 4. The rotor bars are connected by end rings, and the end rings are preferably made of brass T2Y or copper Grass. This structure can significantly reduce the starting current of the self-starting permanent magnet synchronous motor.

[0041] As an embodiment of the present invention, preferably, the guide strips 4 are connected by end rings.

[0042] As an embodiment of the present invention, preferably, the end ring is made of brass T2Y or copper Grass.

[0043] As an embodiment of the present invention, preferably, the guide bar 4 is made of brass T2Y.

[0044] As an embodiment of the present invention, preferably, it further includes a plurality of magnet units arranged in a circumferential array along the central shaft hole of the rotor lamination 1, each of the magnet units including a plurality of magnets 3 in an "I" or "V" shaped structure.

[0045] This invention can effectively reduce the motor starting current while having minimal impact on the motor's starting torque multiple and embedding capability.

[0046] Example 2:

[0047] like Figure 1-2 As shown, as the second embodiment provided by the present invention, the present invention is a self-starting permanent magnet motor, wherein the rotor lamination 1 is provided with a magnet slot 2 that cooperates with the magnet 3, and two adjacent magnet slots 2 are not connected to each other.

[0048] As an embodiment of the present invention, preferably, four magnets 3 are provided on 1 / 4 of the rotor lamination 1, the magnets 3 are in the form of an "I" shape, and the four magnets 3 are on the same straight line;

[0049] On the complete rotor lamination 1, the four sets of magnet units are arranged in a square.

[0050] As an embodiment of the present invention, preferably, the proposed structure / method can significantly reduce the starting current of the self-starting permanent magnet synchronous motor, reduce the impact on the power grid during the motor starting process, and reduce the impact on other electrical equipment in the same power grid.

[0051] Example 3:

[0052] like Figure 1 As shown, as the third embodiment provided by the present invention, the present invention is a self-starting permanent magnet motor. When t=2, there is an empty guide bar groove 5 between two adjacent guide bars 4, and on 1 / 4 of the rotor lamination 1, one of the guide bar grooves 5 on both sides is empty and the other is equipped with a guide bar 4.

[0053] As an embodiment of the present invention, preferably, the rotor guide bars 4 are spatially uniformly distributed, such as... Figure 1 As shown, t=2, retaining the guide bar groove helps reduce magnetic leakage and ensures the uniformity of the air gap magnetic field and harmonic content.

[0054] As an embodiment of the present invention, a preferred method for reducing the high starting current of a factory-made self-starting permanent magnet synchronous motor is provided. As shown in Table 1, the following simulation data illustrates that the starting current of the motor, whether the transient peak value or the effective value, is significantly reduced, while the starting torque multiple and embedded inertia multiple of the self-starting motor are not significantly reduced.

[0055] Table 1

[0056]

[0057] Example 4:

[0058] like Figure 2 As shown in the fourth embodiment of the present invention, the present invention is a self-starting permanent magnet motor. When t=4, three adjacent guide bars 4 form a group, and there is an empty guide bar slot 5 between each pair of adjacent groups; and on 1 / 4 of the rotor lamination 1, one of the guide bar slots 5 on both sides is empty, and the other is equipped with a guide bar 4. By adopting the optimized structure proposed in this invention, the number of rotor guide bars is reduced to 3 / 4 of the guide bar slots, and the starting current multiple is successfully reduced to 7 times, and the self-starting motor starts successfully under load.

[0059] As an embodiment of the present invention, preferably, the rotor guide bars 4 are spatially uniformly distributed, such as... Figure 2 As shown, t=4, retaining the guide bar groove helps reduce magnetic leakage and ensures the uniformity of the air gap magnetic field and harmonic content.

[0060] like Figure 3 The figure shows the stall current curve for a conventional structure (equal number of rotor bars and bar slots). Figure 4 The figure shows the stall current curve of the structure of the present invention (the number of rotor bars is 3 / 4 of the number of bar slots).

[0061] Example 5:

[0062] As a fifth embodiment of the present invention, the present invention provides a self-starting permanent magnet motor, the motor comprising a stator and a self-starting permanent magnet motor rotor as described in the first embodiment. The structure / method proposed in this invention can significantly reduce the starting current of the self-starting permanent magnet synchronous motor, reduce the impact on the power grid during motor startup, and reduce the impact on other electrical equipment in the same power grid.

[0063] As an embodiment of the present invention, preferably, the parameters of the self-starting permanent magnet synchronous motor of the present invention are as follows:

[0064] Motor center height: 560, number of poles: 4, power: 630kW, voltage: 10kv, number of slots: 72, number of rotor bars: 64;

[0065] Rated current: 39A. The motor's factory test starting current is 9 times the rated current. On-site testing showed a large starting current, causing the comprehensive protection to overcurrent. By adopting the optimized structure proposed in this invention, the number of rotor bars was reduced to 3 / 4 of the bar slots, successfully reducing the starting current multiple to 7 times, and the self-starting motor successfully started under load.

[0066] Similarly, for motors that have already left the factory but have a large starting current during field testing, the corresponding rotor bars can be damaged to reduce the starting current, which is within the scope of protection of this invention.

[0067] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," 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 the invention. In this specification, 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.

[0068] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A self-starting permanent magnet electric machine rotor, characterized by, include: Guide grooves (5) are arranged in a circular array at the edge of rotor laminations (1); Guide bars (4) are installed in guide bar grooves (5) in a spatially uniform manner; The relationship between the number of guide bars (4) and the number of guide bar grooves (5) is: number of guide bars (4) / number of guide bar grooves (5) = (t-1) / t, and t is only 2, 3, or 4.

2. A self-starting permanent magnet motor rotor according to claim 1, wherein, The guide bars (4) are connected by end rings.

3. A self-starting permanent magnet motor rotor according to claim 2, wherein, The end ring is made of brass T2Y or copper Grass.

4. A self-starting permanent magnet motor rotor according to claim 1, wherein The guide bar (4) is made of brass T2Y.

5. A self-starting permanent magnet motor rotor according to claim 1, wherein It also includes several magnet units arranged in a circular array along the central shaft hole of the rotor lamination (1), each of the magnet units including several magnets (3) in an "I" or "V" shaped structure.

6. A self-starting permanent magnet motor rotor according to claim 5, wherein, The rotor lamination (1) is provided with a magnet slot (2) that cooperates with the magnet (3), and two adjacent magnet slots (2) are not connected to each other.

7. A self-starting permanent magnet motor rotor according to claim 5, characterized in that: Four magnets (3) are present on one-quarter of the rotor lamination (1). The magnets (3) are in the form of an "I" shape and the four magnets (3) are on the same straight line. On the complete rotor lamination (1), the four sets of magnet units are arranged in a square.

8. A self-starting permanent magnet motor rotor according to claim 1, wherein, When t=2, there is an empty guide bar groove (5) between two adjacent guide bars (4), and on 1 / 4 of the rotor lamination (1), one of the guide bar grooves (5) on both sides is empty and the other is equipped with a guide bar (4).

9. A self-starting permanent magnet motor rotor according to claim 1, wherein When t=4, the three adjacent guide bars (4) are grouped together, and there is an empty guide bar groove (5) between each pair of adjacent groups; and on 1 / 4 of the rotor lamination (1), one of the guide bar grooves (5) on both sides is empty and the other is equipped with a guide bar (4).

10. A self-starting permanent magnet electric machine characterized by, The motor includes a stator and a self-starting permanent magnet motor rotor as described in any one of claims 1-9.

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