Rotor of a transverse flux permanent magnet synchronous motor

Abstract

This application relates to the field of motor rotor structure, specifically an anti-salient pole permanent magnet synchronous motor rotor. The purpose of this application is to address the problems of large permanent magnet leakage, small speed regulation range due to field weakening, and irreversible demagnetization of permanent magnets in existing rare-earth permanent magnet synchronous motors with built-in magnetic steel structures and magnetic bridges. The rotor core of this application has a main permanent magnet uniformly embedded circumferentially on its outer surface. Each main permanent magnet is divided into 2m-1 segments circumferentially. Two auxiliary permanent magnets are embedded between adjacent main permanent magnets. The rotor core between adjacent main permanent magnet segments serves as a rotor tooth. The rotor core between adjacent main and auxiliary permanent magnets serves as a rotor side tooth. An axially penetrating magnetic isolation slot is formed on the rotor core, with each slot uniformly arranged circumferentially and corresponding to one of the main permanent magnets. The cross-section of each magnetic isolation slot is a radially elongated strip, with one end connected to the corresponding main permanent magnet.

Description

Technical Field

[0001] This application belongs to the field of electric motors, and in particular relates to the rotor structure of electric motors. Background Technology

[0002] Traditional rare-earth permanent magnet synchronous motors with built-in magnet bridges possess advantages such as high torque density, high power factor, and high efficiency, leading to their widespread research and application across various industries. However, the built-in magnet bridge structure results in increased permanent magnet leakage due to the magnetic flux emitted by the permanent magnets flowing through the internal magnet bridge of the rotor, thus reducing the utilization rate of the permanent magnets. Figure 8 As shown. When the speed of a permanent magnet synchronous motor exceeds its rated speed, field weakening control must be performed. Because the excitation of rare-earth permanent magnets cannot be adjusted, and because the permanent magnets are always connected in series in the direct-axis magnetic circuit, such as... Figure 8 As shown, the inability to obtain a large direct-axis inductance results in a small field-weakening speed range for permanent magnet synchronous motors, limiting their application in fields with wide field-weakening speed ranges. Furthermore, applying a direct-axis demagnetizing current to the permanent magnet synchronous motor for field weakening can easily lead to irreversible demagnetization of the permanent magnets. Additionally, the high cost of rare-earth permanent magnet materials increases the material cost of rare-earth permanent magnet synchronous motors. Summary of the Invention

[0003] This application aims to address the problems of large permanent magnet leakage, small speed regulation range due to field weakening, and irreversible demagnetization of permanent magnets in existing rare-earth permanent magnet synchronous motors with built-in magnetic steel structures and magnetic bridges. The application provides a low-cost permanent magnet synchronous motor rotor with anti-salient poles and surface-embedded magnetic steel structure.

[0004] The first aspect of this application provides a rotor for an anti-salient pole permanent magnet synchronous motor, comprising a coaxially nested rotor core and a shaft, wherein the outer surface of the rotor core is uniformly embedded with [missing information - likely referring to a specific type of material] circumferentially. One main permanent magnet The number of pole pairs is 2m-1, and each main permanent magnet is divided into 2m-1 segments along the circumference, where m is an integer greater than or equal to 2.

[0005] Two auxiliary permanent magnets are embedded between adjacent main permanent magnets and arranged in contact with each other;

[0006] The rotor core between two adjacent main permanent magnet sections serves as the rotor teeth.

[0007] The rotor core between adjacent main permanent magnets and auxiliary permanent magnets serves as the rotor side teeth;

[0008] The rotor core has A magnetic flux-blocking slot that runs through the axis. The magnetically shielding slots are evenly arranged along the circumference of the rotor core, and are respectively connected to the magnetically shielding slots. Each main permanent magnet corresponds to a specific magnet, and the cross-section of the magnetic isolation groove is a long strip arranged radially, with one end connected to the corresponding main permanent magnet.

[0009] In one possible design, a magnetic bridge connected in series in the quadrature magnetic circuit is left between the other end of the magnetic isolation slot and the inner circle of the rotor core.

[0010] In one possible design, the main permanent magnet is a rare-earth permanent magnet material, and the auxiliary permanent magnet is a non-rare-earth permanent magnet material.

[0011] In one possible design, both the main permanent magnet and the auxiliary permanent magnet are made of rare-earth permanent magnet materials.

[0012] In one possible design, both the main permanent magnet and the auxiliary permanent magnet are made of non-rare earth permanent magnet materials.

[0013] In one possible design, the permanent magnet material is magnetized either parallel or radially.

[0014] In one possible design, the rotor teeth in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet as the axis of symmetry.

[0015] In one possible design, the circumferential widths of the rotor teeth located on the same side of the axis of symmetry are different.

[0016] In one possible design, the rotor side teeth in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet as the axis of symmetry.

[0017] In one possible design, the magnetic flux barrier is filled with a non-magnetic solid.

[0018] A second aspect of this application provides an anti-salient pole permanent magnet synchronous motor, comprising: a stator and a rotor nested coaxially, with an air gap between the stator and the rotor; the rotor is the aforementioned anti-salient pole permanent magnet synchronous motor rotor.

[0019] The beneficial effects of this application are:

[0020] 1. One side of the permanent magnet is an air gap with a large magnetic resistance. Therefore, the leakage of magnetic flux in the rotor teeth is very small, and the utilization rate of the permanent magnet is high.

[0021] 2. The convex teeth formed by the rotor core provide a path for the direct-axis magnetic flux, which can obtain a large direct-axis inductance, thus improving the speed regulation range of the motor by field weakening.

[0022] 3. The excitation is achieved by using a mixture of rare earth permanent magnet materials and non-rare earth permanent magnet materials. The amount of rare earth permanent magnet materials used is small, resulting in low motor material costs.

[0023] 4. Due to its anti-salient pole characteristics, the magnetic weakening current required to reach the same speed when operating above the rated speed is smaller, reducing the risk of irreversible demagnetization of the permanent magnet.

[0024] This application can be used for both permanent magnet motors and permanent magnet generators. Attached Figure Description

[0025] Figure 1 A schematic diagram of the overall structure of a low-cost permanent magnet synchronous motor with surface-embedded magnets and anti-convex poles;

[0026] Figure 2 A schematic diagram of the rotor structure in a low-cost permanent magnet synchronous motor with surface-embedded magnets and anti-convex poles;

[0027] Figure 3 A schematic diagram of the magnetic flux path of a motor winding that only carries direct-axis current;

[0028] Figure 4 A schematic diagram of the magnetic flux path of a motor winding that carries only cross-axis current;

[0029] Figure 5 A schematic diagram of the rotor of a surface-embedded magnet structure with anti-convex pole rare-earth permanent magnet synchronous motor.

[0030] Figure 6 A schematic diagram of the rotor of a surface-embedded magnet structure anti-convex pole non-rare earth permanent magnet synchronous motor.

[0031] Figure 7 This is a schematic diagram of the orthogonal axis magnetic flux path of a surface-mounted magnet rotor.

[0032] Figure 8 A schematic diagram of the orthogonal axis magnetic flux path of a permanent magnet synchronous motor with an embedded magnetic steel structure and a magnetic bridge;

[0033] In the figure, the main permanent magnet is 1, the auxiliary permanent magnet is 2, the rotor core is 3, the rotor tooth is 3-1, the rotor side tooth is 3-2, the magnetic isolation slot is 4, the shaft is 5, the stator is 6, and the rotor is 7. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0035] Specific Implementation Method 1: The anti-salient pole permanent magnet synchronous motor rotor described in this implementation method includes a coaxially nested rotor core and a shaft. The outer surface of the rotor core is uniformly embedded with [missing information - likely referring to a specific type of material]. One main permanent magnet The number of pole pairs is 2m-1, and each main permanent magnet is divided into 2m-1 segments along the circumference, where m is an integer greater than or equal to 2.

[0036] Two auxiliary permanent magnets are embedded between adjacent main permanent magnets and arranged in contact with each other;

[0037] The rotor core between two adjacent main permanent magnet sections serves as the rotor teeth.

[0038] The rotor core between adjacent main permanent magnets and auxiliary permanent magnets serves as the rotor side teeth;

[0039] The rotor core has A magnetic flux-blocking slot that runs through the axis. The magnetically shielding slots are evenly arranged along the circumference of the rotor core, and are respectively connected to the magnetically shielding slots. Each main permanent magnet corresponds to a specific magnet, and the cross-section of the magnetic isolation groove is a long strip arranged radially, with one end connected to the corresponding main permanent magnet.

[0040] In one embodiment, a magnetic bridge connected in series in the quadrature magnetic circuit is left between the other end of the magnetic isolation slot and the inner circle of the rotor core.

[0041] In one embodiment, the main permanent magnet is a rare-earth permanent magnet material, and the auxiliary permanent magnet is a non-rare-earth permanent magnet material.

[0042] In one implementation, such as Figure 5 As shown, both the main permanent magnet and the auxiliary permanent magnet are made of rare-earth permanent magnet materials. The amount of rare-earth permanent magnet material used is the same as that in traditional rare-earth permanent magnet synchronous motors. Compared with the case where the two permanent magnets are made of different materials, the fact that both the main permanent magnet and the auxiliary permanent magnet are made of rare-earth permanent magnet materials can further improve the power density ratio of the motor.

[0043] In one implementation, such as Figure 6 As shown, both the main permanent magnet and the auxiliary permanent magnet are made of non-rare-earth permanent magnet materials. Compared with cases where the two permanent magnets are made of different materials, the fact that both the main and auxiliary permanent magnets are made of non-rare-earth permanent magnet materials can eliminate the dependence on rare-earth permanent magnet materials and further reduce the cost of motor materials.

[0044] In one embodiment, the permanent magnet material is magnetized in a parallel or radial manner.

[0045] In one embodiment, the rotor teeth in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet as the axis of symmetry.

[0046] In one embodiment, the rotor teeth located on the same side of the axis of symmetry have different circumferential widths.

[0047] In one embodiment, the rotor side teeth 3-2 in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet 1 as the axis of symmetry.

[0048] In one embodiment, the magnetically shielded channel is filled with a non-magnetic solid.

[0049] In traditional permanent magnet synchronous motors with built-in magnetic bridges, the direct-axis inductance is smaller than the quadrature-axis inductance. Because of the smaller direct-axis inductance, the field weakening range is limited. Simultaneously, the magnetic bridge leads to significant leakage flux in the permanent magnets, reducing their utilization rate.

[0050] In this embodiment, segmented permanent magnets are embedded in the outer surface of the rotor core 3, thereby forming protruding teeth on the surface of the rotor core 3. These protruding teeth provide a path for direct-axis magnetic flux, thus obtaining a larger direct-axis inductance and improving the motor's field-weakening speed regulation range. At the same time, the structure of the permanent magnets embedded in the outer surface of the rotor can effectively reduce the leakage flux of the permanent magnets and improve the utilization rate of the permanent magnets.

[0051] The rotor tooth 3-1 provides a path for the direct-axis magnetic flux, resulting in a large direct-axis inductance. However, due to the presence of the rotor tooth 3-1, the quadrature-axis magnetic flux can also be closed through the rotor tooth 3-1. Since the magnetic reluctance of the rotor tooth 3-1 is very small, the quadrature-axis inductance will also be large. To reduce the quadrature-axis inductance, a flux-blocking slot 4 is provided in the quadrature-axis magnetic circuit. The flux-blocking slot has a very large magnetic reluctance and is connected in series in the quadrature-axis magnetic circuit, which can effectively reduce the quadrature-axis inductance, thereby realizing an anti-salient pole structure. The presence of the flux-blocking slot 4 increases the difference between the direct-axis inductance and the quadrature-axis inductance, that is, increases the reluctance torque of the motor, which is beneficial to further improve the electromagnetic torque of the motor.

[0052] Specific implementation method two: The anti-salient pole permanent magnet synchronous motor described in this implementation method includes a stator 6 and a rotor 7 nested coaxially, with an air gap between the stator 6 and the rotor 7.

[0053] Stator 6 consists of a stator core and stator windings.

[0054] The rotor is the anti-salient pole permanent magnet synchronous motor rotor described in Specific Embodiment 1. The rotor 7 consists of a rotor core 3, permanent magnets, magnetically insulating slots 4, and a rotating shaft 5. The permanent magnets include... One main permanent magnet 1 and Two auxiliary permanent magnets. In this embodiment, the extreme logarithm is used. .

[0055] To further illustrate the implementation scheme of this application, Figure 2 A low-cost permanent magnet synchronous motor rotor with anti-salient poles and a surface-embedded magnet structure is provided, which is described in detail below:

[0056] like Figure 1As shown. A low-cost permanent magnet synchronous motor with a surface-embedded magnet structure and anti-convex poles includes a coaxially nested stator 6 and rotor 7, with an air gap between the stator 6 and rotor 7.

[0057] Stator 6 consists of a stator core and stator windings.

[0058] Rotor 7 consists of rotor core 3, permanent magnet, magnetically insulating slots 4, and rotating shaft 5. The permanent magnet includes... One main permanent magnet 1 and Two auxiliary permanent magnets. In this embodiment, the extreme logarithm is used. .

[0059] like Figure 2 As shown. The outer surface of rotor core 3 has circumferentially shaped openings. One main permanent magnet slot and One auxiliary permanent magnet slot. One main permanent magnet slot and The auxiliary permanent magnet slots are arranged alternately. The main permanent magnet 1 is located at respectively Each main permanent magnet slot contains two auxiliary permanent magnets 2; each auxiliary permanent magnet slot contains two auxiliary permanent magnets 2, so that Each auxiliary permanent magnet 2 is located at... Inside the auxiliary permanent magnet slot.

[0060] Each main permanent magnet 1 is uniformly divided into 2m-1 segments along the circumference, where m is an integer greater than or equal to 2, and in this embodiment, m=2. The rotor core 3 between two adjacent main permanent magnet segments 1 serves as rotor teeth 3-1; the rotor core 3 between adjacent main permanent magnet 1 and auxiliary permanent magnet 2 serves as rotor side teeth 3-2.

[0061] The rotor teeth 3-1 in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet 1 as the axis of symmetry; the circumferential width of the rotor teeth 3-1 located on the same side of the axis of symmetry can be different.

[0062] The rotor side teeth 3-2 in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet 1 as the axis of symmetry.

[0063] The rotor core 3 has an opening A magnetic flux-blocking groove 4 that runs through the axis. The magnetically shielding slots 4 are evenly arranged around the rotor core 3, and are respectively connected to the magnetically shielding slots 4. Each main permanent magnet slot corresponds one-to-one. The cross-section of the magnetic flux isolation slot 4 is a long strip arranged radially. This strip coincides with the radial centerline of the corresponding main permanent magnet slot, and one end is connected to the corresponding main permanent magnet slot. The other end has a magnetic bridge connected in series in the quadrature axis magnetic circuit between it and the inner circle of the rotor. Its function is to connect the rotor laminations into a whole with sufficient mechanical strength. The magnetic flux generated by the direct-axis component of the permanent magnet or winding current does not pass through this magnetic bridge; only the quadrature axis magnetic flux generated by the quadrature axis component of the winding current passes through this magnetic bridge.

[0064] The rotating shaft 5 is made of non-magnetic material, the main permanent magnet 1 is made of rare earth permanent magnet material, and the auxiliary permanent magnet 2 is made of non-rare earth permanent magnet material. The polarity of the main and auxiliary permanent magnet materials in each pole is the same.

[0065] Figure 3 A schematic diagram of the orthogonal axis magnetic flux path of a motor winding that carries only direct-axis current; Figure 4 This is a schematic diagram of the direct-axis magnetic flux path of a motor winding carrying only quadrature-axis current. As shown in the diagram, in this embodiment, the number of direct-axis magnetic lines is greater than the number of quadrature-axis magnetic lines, and the direct-axis inductance of the motor... Greater than quadrature axis inductance The motor has anti-salient pole characteristics.

[0066] like Figure 7 The surface-mounted magnet structure rotor's right-angle magnetic flux path is shown, where the right-angle inductances are equal. According to the electromagnetic torque formula of a permanent magnet synchronous motor: It is evident that reluctance torque cannot be utilized; the motor employs direct-axis current. Because field weakening control is not possible, the speed regulation range for field weakening of the motor is very narrow. In the formula, For the electromagnetic torque of a permanent magnet synchronous motor, For extreme logarithms, It is a permanent magnet flux linkage. and These are the direct-axis and quadrature-axis currents, respectively.

[0067] In traditional permanent magnet synchronous motors with embedded magnets, the permanent magnet is a single piece, and the direct-axis inductor... Approximately equal to quadrature axis inductance Furthermore, it is very small, essentially a salient-pole structure. Although this embodiment also uses a surface-embedded magnet structure, the permanent magnets are segmented to form convex teeth. When the magnetic flux isolation slot 4 is absent, the right-angle axis inductance in this embodiment is similar, but due to the presence of the convex teeth, the right-angle axis inductance is numerically larger, still remaining a salient-pole structure. Adding the magnetic flux isolation slot 4 changes the motor's magnetic circuit structure, making the right-angle inductance significantly larger than the quadrature axis inductance, forming an anti-salient-pole structure. Therefore, although the motor in this embodiment has a surface-embedded magnet structure, it is indeed an anti-salient-pole structure, i.e. The main advantages of this embodiment of the motor compared to surface-mounted permanent magnet synchronous motors are:

[0068] First, it is not necessary to use direct-axis current. Control allows for adjustment of the direct-axis current. With field weakening speed regulation, the motor has a wide speed range.

[0069] Second, the inductances of the right and quadrature axes are not equal ( Magnetic reluctance torque can be utilized, which is beneficial for improving electromagnetic torque. Since the rotor convex teeth 3-1 of the iron core in the direct axis direction provide a path for the direct axis magnetic flux and are in an unsaturated state, while magnetic barriers in the quadrature axis direction reduce the quadrature axis inductance, the difference between the direct axis inductance and the quadrature axis inductance is relatively large. According to the current flow law of anti-salient pole motors: when the motor is running at rated speed, a very small positive direct axis current flows through it. When the motor is running at speeds above its rated speed, the positive direct-axis current... The current gradually decreases to 0, then to less than 0, until it reaches the rated current. Therefore, when operating below the rated speed, a very small positive direct-axis current is required to obtain a large reluctance torque.

[0070] like Figure 8 The diagram shows the direct-axis and quadrature-axis flux paths of a permanent magnet synchronous motor with an integrated magnet structure featuring a magnetic bridge. The direct-axis inductance is smaller than the quadrature-axis inductance. A permanent magnet is connected in series in a direct-axis magnetic circuit, and a direct-axis inductor... Smaller permanent magnet flux linkage, larger motor speed formula. It can be seen that the speed regulation range of the motor by field weakening is small. In the formula, This is the motor's maximum speed. These are voltage extreme values. This represents the current extreme value. The magnetic bridge causes high leakage flux in the permanent magnet, resulting in low utilization. The magnetic bridge state is saturated. When weakening the motor's field, a negative direct-axis demagnetizing current needs to be applied, which can easily cause irreversible demagnetization of the permanent magnet. Rare-earth permanent magnet materials are used in large quantities, leading to high costs.

[0071] The motor described in this embodiment adopts a surface-embedded magnet structure, with each permanent magnet inserted into a slot on the outer surface of the rotor. The motor described in this embodiment and... Figure 8 Compared to the motor with the structure shown, it has the following advantages:

[0072] 1. One side of the permanent magnet is the gap between the stator and rotor (where the air magnetic resistance is very large), so the leakage magnetic flux of the permanent magnet in the rotor teeth is small and the utilization rate of the permanent magnet is high.

[0073] 2. The rotor teeth 3-1 formed by the rotor core (the core material has very low magnetic resistance) provide a path for the direct-axis magnetic flux, and the rotor teeth 3-1 are in an unsaturated state (the magnetic bridge in the built-in magnet structure is in a severely saturated state). The direct-axis inductance of the motor... It is very large, and at the same time, magnetic barriers are set on the quadrature axis magnetic circuit to reduce it. The motor has anti-salient pole characteristics, that is Therefore, the speed regulation range of the motor can be improved by field weakening.

[0074] 3. Rare earth permanent magnet materials are used in small quantities, resulting in low motor costs.

[0075] 4. When performing field weakening control above the rated speed, the direct-axis demagnetizing current required for the same speed is small, and the permanent magnet is less likely to undergo irreversible demagnetization.

[0076] In practical applications, the rotor described in this embodiment can be used as an inner rotor structure or an outer rotor structure. The outer surface of the rotor core can be circular or composed of... A non-circular curve composed of segments of circular arcs. Permanent magnets can be rectangular or tile-shaped. The permanent magnet material is magnetized parallel or radially, with the polarity of the main and auxiliary permanent magnet materials at each pole being the same. Each segment of the main permanent magnet 1 can be equal or unequal. The magnetically shielding slot 4 can be empty or filled with a non-magnetic solid. The shape of the magnetically shielding slot can be rectangular, trapezoidal, or irregular.

[0077] While specific embodiments of this application have been described herein with reference to them, it should be understood that these embodiments are merely examples of the principles and applications of this application. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of this application as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A rotor for an anti-salient pole permanent magnet synchronous motor, comprising a coaxially nested rotor core and a shaft, characterized in that, The outer surface of the rotor core is uniformly embedded with 2p main permanent magnets along the circumference, where p is the number of pole pairs, and each main permanent magnet is divided into 2m-1 segments along the circumference, where m is an integer greater than or equal to 2. Two auxiliary permanent magnets are embedded between adjacent main permanent magnets and arranged in circumferential contact with each other. The rotor core between two adjacent main permanent magnet sections serves as the rotor teeth. The rotor core between adjacent main permanent magnets and auxiliary permanent magnets serves as the rotor side teeth; The rotor core has 2p axially penetrating magnetic flux isolation slots. The 2p magnetic flux isolation slots are evenly arranged along the circumference of the rotor core and correspond one-to-one with the 2p main permanent magnets. The cross-section of the magnetic flux isolation slot is a long strip arranged radially, and one end is connected to the corresponding main permanent magnet.

2. The anti-salient pole permanent magnet synchronous motor rotor according to claim 1, characterized in that, The other end of the magnetic flux isolation slot has a magnetic bridge connected in series in the quadrature magnetic circuit between it and the inner circle of the rotor core.

3. The anti-salient pole permanent magnet synchronous motor rotor according to claim 1, characterized in that, The main permanent magnet is made of rare earth permanent magnet material, and the auxiliary permanent magnet is made of non-rare earth permanent magnet material.

4. The anti-salient pole permanent magnet synchronous motor rotor according to claim 1, characterized in that, Both the main permanent magnet and the auxiliary permanent magnet are rare earth permanent magnet materials.

5. The anti-salient pole permanent magnet synchronous motor rotor according to claim 1, characterized in that, Both the main permanent magnet and the auxiliary permanent magnet are non-rare earth permanent magnet materials.

6. The anti-salient pole permanent magnet synchronous motor rotor according to claim 3, 4 or 5, characterized in that, The permanent magnet material is magnetized in the parallel or radial direction.

7. The anti-salient pole permanent magnet synchronous motor rotor according to claim 1, characterized in that, The rotor teeth in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet as the axis of symmetry.

8. The anti-salient pole permanent magnet synchronous motor rotor according to claim 7, characterized in that, The circumferential widths of the rotor teeth located on the same side of the axis of symmetry are different.

9. The anti-salient pole permanent magnet synchronous motor rotor according to claim 1, characterized in that, The rotor side teeth in the same pole are arranged radially symmetrically with the radial centerline of the main permanent magnet as the axis of symmetry.

10. The anti-salient pole permanent magnet synchronous motor rotor according to claim 1, characterized in that, The magnetically shielded slot is filled with a non-magnetic solid.

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