Motor rotor and hybrid excitation motor with same

Abstract

The invention relates to the technical field of excitation motors, and discloses a motor rotor and a hybrid excitation motor with the same. The motor rotor comprises a rotor iron core, a plurality of wire embedding grooves and a plurality of magnetic steel notches are formed in the rotor iron core, the wire embedding grooves are arranged at intervals in the circumferential direction of the rotor iron core, the magnetic steel notches are arranged between every two adjacent wire embedding grooves, the magnetic steel notches are arranged close to the circumferential edge of the rotor iron core, and the magnetic steel notches are arranged in a closed mode in the circumferential direction; the permanent magnets are installed in the magnetic steel grooves in an embedded mode so that the rotor iron core can completely surround the peripheries of the permanent magnets in the circumferential direction; and the excitation winding is wound and installed in the two adjacent wire embedding grooves. The permanent magnets are completely embedded in the circumferentially closed magnetic steel notches, so that the rotor core can form all-around protection and constraint on the permanent magnets, and the mechanical reliability of the motor rotor structure is improved. The built-in permanent magnet can reduce the equivalent air gap and reduce the magnetic resistance of the magnetic circuit in the excitation motor, thereby improving the torque and power density of the excitation motor.

Description

Technical Field

[0001] This invention relates to the field of excitation motor technology, specifically to a motor rotor and a hybrid excitation motor having the same rotor. Background Technology

[0002] Hybrid excitation motors, as a technical solution that combines the high efficiency of permanent magnet motors with the wide speed range of electrically excited motors, have shown broad application prospects in the field of new energy vehicle drives. By simultaneously introducing permanent magnets and excitation windings into the motor's magnetic circuit, the air gap magnetic field can be controlled by adjusting the excitation current, thereby effectively widening the constant power speed range of the motor and improving the vehicle's adaptability to different operating conditions.

[0003] In hybrid excitation motors, the rotor structure is a key core component, directly affecting the motor's torque density, efficiency, reliability, and vibration and noise performance. Existing hybrid excitation motor rotor pole structures mostly employ surface-mount or surface-embedded magnet solutions. The permanent magnets are typically fixed to the rotor core surface or shallow slots using adhesive bonding, such as... Figure 1 As shown. However, since the magnets are fixed by adhesives, the huge centrifugal force during high-speed motor operation can easily cause the magnets to fall off or be damaged, resulting in insufficient mechanical strength of the rotor structure, which makes it difficult to meet the reliability requirements of high-speed operation for new energy vehicle motors. Moreover, because the magnets are attached to the rotor surface, the equivalent air gap is large, leading to an increase in air gap magnetic reluctance. Under the same material usage, the motor's torque, power output capacity, and density are all lower. Summary of the Invention

[0004] In view of this, the present invention provides a motor rotor and a hybrid excitation motor having the same, to solve the problems of easy detachment of internal magnets and excessively large equivalent air gap in the rotor of the hybrid excitation motor in the prior art.

[0005] In a first aspect, the present invention provides an electric motor rotor, comprising: The rotor core has multiple winding slots and multiple magnet slots formed inside. The multiple winding slots are arranged at intervals along the circumference of the rotor core. The magnet slots are located between two adjacent winding slots. The magnet slots are arranged close to the circumferential edge of the rotor core and are closed along the circumference. A permanent magnet is embedded in the magnetic steel slot so that the rotor core completely surrounds the permanent magnet circumferentially. The excitation winding is wound and installed in two adjacent slots.

[0006] When the motor rotor is operating, its rotor core serves as the magnetic circuit carrier and structural main body. Permanent magnets embedded in circumferentially closed magnetic slots generate a constant permanent magnetic field; simultaneously, the current-driven excitation winding generates a controllable electrical excitation magnetic field. The permanent magnetic field and the electrical excitation magnetic field superimpose and couple within the rotor core, jointly forming the main air gap magnetic field. By adjusting the current in the excitation winding, the strength and direction of the electrical excitation magnetic field can be changed, thereby regulating the coupled air gap magnetic field. By completely embedding the permanent magnets within the circumferentially closed magnetic slots, the rotor core provides comprehensive protection and constraint for the permanent magnets, improving the mechanical reliability of the motor rotor structure, especially suitable for high-speed applications. Furthermore, the built-in permanent magnets reduce the overall equivalent air gap of the motor, lowering the magnetic reluctance of the magnetic circuit in the exciter motor, thus generating a stronger air gap magnetic field with the same volume and material usage, increasing the torque and power density of the exciter motor. Meanwhile, the built-in permanent magnet can provide a constant excitation magnetic field, and it does not require current or increase excitation copper losses, similar to the operation mode of a permanent magnet motor. In the low-to-medium speed, low-torque operating range, the magnetic field generated by the permanent magnet can be used mainly for operation, while the excitation winding does not work or only operates under a small load, which can significantly reduce excitation copper losses and improve the average efficiency of the excitation motor.

[0007] In one alternative embodiment, the winding slot is closed on one side facing the circumferential edge of the rotor core, thereby forming a radial constraint on the excitation winding. This prevents the excitation winding from dislodging from the winding slot under centrifugal force during high-speed operation, enhancing the mechanical reliability of the motor rotor. Simultaneously, the closed structure helps reduce cogging harmonics of the air gap flux and improves the air gap magnetic flux density waveform, thereby reducing torque ripple and electromagnetic noise, and improving the overall noise, vibration, and harshness (NVH) performance of the excitation motor.

[0008] In one optional embodiment, a connecting bridge is provided on the side of the winding slot facing the circumferential edge of the rotor core, and the connecting bridge is integrally formed with the rotor core. The side of the winding slot facing the outer circle of the rotor is formed by the connecting bridge closed structure of the lamination material of the rotor core itself. The connecting bridge, as part of the rotor core lamination, is punched and stacked together with the silicon steel sheet of the rotor core during manufacturing.

[0009] In one optional embodiment, a slot wedge is installed on the side of the winding slot facing the circumferential edge of the rotor core, and the slot wedge is detachably installed on the rotor core. After the excitation winding is installed into the winding slot, an independent slot wedge is installed at the slot opening position, and the slot wedge is locked and fixed to the rotor core by mechanical fixing methods such as snap-fit ​​and abutment to prevent the slot wedge from loosening, thereby ensuring the stability of the excitation winding under high-speed motor operation.

[0010] In one optional embodiment, the rotor core includes a plurality of segmented cores, which are spliced ​​together circumferentially to form the rotor core, and the inlay groove is formed between two adjacent segmented cores.

[0011] When assembling the motor rotor, the excitation winding can be wound separately on individual segmented cores. Then, the segmented cores are spliced ​​together circumferentially. At this time, the gap between adjacent segmented cores naturally forms a complete winding slot to accommodate the excitation winding, which facilitates the assembly of the excitation winding.

[0012] In one optional embodiment, a rotor end plate is mounted on at least one end of the rotor core along the axial direction, and a shoulder is provided at the position of the rotor end plate corresponding to the magnet slot, the shoulder extending away from the rotor core.

[0013] The rotor end plate axially presses the ends of the rotor core together with shoulders. The shoulders extend and cover the axial openings of the magnet slots. The shoulder structure prevents the rotor core laminations from warping axially and provides axial constraint on the built-in permanent magnets. This prevents the permanent magnets from shifting axially or being thrown out during motor rotor operation, thus improving the mechanical reliability and safety of the motor rotor at high speeds.

[0014] In one alternative embodiment, the magnet slots are provided in one or more layers at intervals along the radial direction of the rotor core.

[0015] Permanent magnets are arranged in one or more magnetic slots at different radial depths within the rotor core. Arranging multiple magnetic slots to install multiple layers of permanent magnets can improve the air gap magnetic flux density and the motor's torque output capability. The combination of different layers of permanent magnets can reduce rotor leakage flux and adjust the direct-axis and quadrature-axis inductances, thereby more effectively utilizing reluctance torque and improving the power density and speed range of the excitation motor.

[0016] In one alternative embodiment, a plurality of magnet slots are spaced apart between two adjacent winding slots. Segmenting the permanent magnets can reduce eddy current losses caused by continuous distribution of the permanent magnets, thus reducing magnet heating. Simultaneously, the segmented layout of the permanent magnets helps optimize the sinusoidal waveform of the air gap magnetic field, reducing torque pulsation.

[0017] In one optional embodiment, the cross-section of the magnet slots is arranged in a straight line, a V-shape, or a U-shape. Different magnet slot arrangement shapes can change the direction of the magnetic field generated after the permanent magnets are installed in the magnet slots, thereby forming different magnetic circuit structures. Among them, the V-shaped or U-shaped layout can generate a magnetic focusing effect and improve the air gap magnetic density; at the same time, the permanent magnets arranged in a V-shaped or U-shaped manner can form wider magnetic bridges, which can improve the mechanical strength of the motor rotor and is more suitable for ultra-high speed operation. The straight line permanent magnet layout has a high magnet utilization rate.

[0018] In one optional embodiment, the excitation winding is made of round copper wire or flat copper wire. Using round copper wire for the excitation winding simplifies the winding process, improves tooling compatibility, and reduces manufacturing costs. Using flat copper wire for the excitation winding increases the slot fill factor, allowing for more conductive material to be accommodated in the same slot shape, thereby reducing winding resistance, decreasing excitation copper losses, and improving motor efficiency.

[0019] Secondly, the present invention also provides a hybrid excitation motor having the motor rotor described in the present invention.

[0020] Since the hybrid excitation motor includes a motor rotor and has the same effect as the motor rotor, it will not be elaborated further here. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the magnetic pole structure of a hybrid excitation motor rotor in the prior art.

[0023] Figure 2 This is a side view of the motor rotor provided in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the permanent magnet layout structure of the motor rotor provided in an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the excitation winding structure of another motor rotor provided in an embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of another motor rotor connecting bridge provided in an embodiment of the present invention.

[0027] Figure 6 This is a schematic diagram of the segmented core structure provided in an embodiment of the present invention.

[0028] Figure 7 A perspective view of a motor rotor provided in an embodiment of the present invention.

[0029] Figure 8 This is a schematic diagram of the rotor end plate provided in an embodiment of the present invention.

[0030] Figure 9This is a schematic diagram of another permanent magnet layout structure for a motor rotor provided in an embodiment of the present invention.

[0031] Figure 10 This is a schematic diagram of another permanent magnet layout structure for a motor rotor provided in an embodiment of the present invention.

[0032] Figure 11 This is a schematic diagram of another permanent magnet layout structure for a motor rotor provided in an embodiment of the present invention.

[0033] Figure 12 This is a schematic diagram of another permanent magnet layout structure for a motor rotor provided in an embodiment of the present invention.

[0034] Figure 13 This is a schematic diagram of another permanent magnet layout structure for a motor rotor provided in an embodiment of the present invention.

[0035] Figure 14 This is a schematic diagram of another permanent magnet layout structure for a motor rotor provided in an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures: 1. Rotor core; 2. Permanent magnet; 3. Excitation winding; 4. Insertion slot; 5. Magnet slot opening; 6. Slot wedge; 7. Connecting bridge; 8. Rotor end plate; 9. Shoulder. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all embodiments. 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.

[0038] In related technologies, the magnets in surface-mount and surface-embedded magnet structures of excitation motors are fixed with adhesive, which is not secure enough. The rotor provides poor protection for the magnets, and at high speeds, the centrifugal force can easily cause the magnets to fly off, thus failing to meet the high-speed requirements of new energy vehicle motors. Furthermore, the relative permeability of these magnets is approximately 1, close to that of air, and far lower than the 2000-8000 of silicon steel sheets. The equivalent air gap of surface-mount and surface-embedded structures, when combined with the thickness of a magnet, is much larger than the air gap in conventional structures. With the same amount of material, the output torque and power are significantly lower, and the torque and power density are far lower than those of smaller air gap solutions. To improve the excitation magnetic field, higher-performance magnets, increased excitation coil turns, or increased excitation current are required, which increases costs and rotor copper losses. Furthermore, in surface-mount and surface-embedded motors, the quadrature-axis and direct-axis inductances are nearly equal, and the reluctance torque is close to zero. This makes it impossible to utilize the reluctance torque, and the controller software finds it more difficult to adjust the air gap magnetic field waveform. The air gap magnetic flux density also has a relatively high harmonic content, increasing harmonic losses and causing NVH (noise, vibration, and harshness) issues. Moreover, common hybrid-excitation and electrically excited motors do not use rotor end plates, or the end plates are surrounded and obscured by coils. Therefore, when performing rotor dynamic balancing, holes cannot be drilled on the end plates; holes must be drilled in the rotor core, which affects the motor's magnetic circuit and electromagnetic performance.

[0039] To overcome the above-mentioned shortcomings, the following will be combined with Figures 2 to 14 The following describes embodiments of the present invention.

[0040] According to an embodiment of the present invention, in one aspect, an electric motor rotor is provided, including a rotor core 1, a permanent magnet 2, and an excitation winding 3.

[0041] like Figure 2 As shown, the rotor core 1 has multiple winding slots 4 and multiple magnet slots 5 formed inside. The winding slots 4 are arranged at intervals along the circumference of the rotor core 1, and the magnet slots 5 are located between two adjacent winding slots 4, close to the circumferential edge of the rotor core 1, and are circumferentially closed. Permanent magnets 2 are embedded in the magnet slots, so that the rotor core 1 completely surrounds the permanent magnets 2 circumferentially. The excitation winding 3 is wound and installed on the rotor core 1 between two adjacent winding slots 4, thus forming an excitation circuit on the rotor core 1. The rotor core 1 is composed of layers of high-permeability silicon steel sheets, and the permanent magnets 2 are made of magnets or other materials.

[0042] When the motor rotor is working, its rotor core 1 serves as the magnetic circuit carrier and structural main body. Permanent magnets 2, embedded in circumferentially closed magnetic slots 5, generate a constant permanent magnetic field; simultaneously, the current-driven excitation winding 3 generates a controllable electrical excitation magnetic field. The permanent magnetic field and the electrical excitation magnetic field are superimposed and coupled within the rotor core 1, jointly forming the main air gap magnetic field. By adjusting the current in the excitation winding 3, the strength and direction of the electrical excitation magnetic field can be changed, thereby achieving adjustment of the coupled air gap magnetic field.

[0043] In the built-in magnet rotor structure, the permanent magnet 2 is placed inside the rotor core 1, which is made of silicon steel sheets. The permanent magnet 2 is axially inserted into the rotor core 1 through the magnet slots. By completely embedding the permanent magnet 2 within the circumferentially closed magnet slots 5, the rotor core can provide all-round protection and constraint for the permanent magnet 2, improving the mechanical reliability of the motor rotor structure, especially suitable for high-speed conditions. Moreover, compared with surface-mounted permanent magnets, built-in permanent magnets 2 can reduce the overall equivalent air gap of the motor and reduce the magnetic reluctance of the magnetic circuit in the exciter motor. This allows for the generation of a stronger air gap magnetic field with the same volume and material usage, improving the torque and power density of the exciter motor. At the same time, the built-in permanent magnet 2 can provide a constant excitation magnetic field without requiring current or increasing excitation copper losses, similar to the operation mode of a permanent magnet motor. In the low-speed, low-torque operating range, the magnetic field generated by the permanent magnet 2 can be used mainly for operation, while the excitation winding 3 is not working or only operates under a small load, which can significantly reduce excitation copper losses and improve the average efficiency of the exciter motor.

[0044] It should be noted that the specific parameters such as the shape of the magnet slot 5, the type of permanent magnet 2, and the material of the excitation winding 3 involved in the above embodiments can be flexibly adjusted and optimized according to the actual application scenario and design requirements. Moreover, the permanent magnet 2 is located inside the rotor core 1, and the outer circle of the rotor core 1 can be a regular arc or designed as a sinusoidal non-uniform air gap structure, which can improve the sinusoidality of the air gap magnetic flux density waveform, reduce the harmonic content, reduce the iron loss and magnet eddy current loss caused by harmonics, and optimize the noise, vibration, and acoustic roughness performance of the excitation motor.

[0045] In one embodiment, such as Figure 3 and Figure 4As shown, the excitation winding 3 can be made of round copper wire with a circular cross-section or flat copper wire with a rectangular cross-section. Round copper wire windings typically use a traditional loose winding method, with the wires distributed relatively randomly within the slots; while flat copper wire windings use a shaped, rigid winding, with the wires insulated and neatly embedded into the slots in a specific order. Using round copper wire for the excitation winding 3 simplifies the winding process, facilitates wire arrangement, allows for easy adjustment of the number of coil turns, provides good compatibility with different wire diameter winding fixtures, and reduces manufacturing costs. Using flat copper wire for the excitation winding 3 increases the slot fill factor, allowing more conductive material to be accommodated within the same cross-sectional area of ​​the slot 4, thereby reducing winding resistance, directly reducing copper losses caused by the excitation current, and improving motor efficiency, making it particularly suitable for applications with extremely high efficiency requirements.

[0046] In one embodiment, the winding slot 4 of the rotor core 1 is designed to be closed on one side facing the circumferential edge of the rotor core 1, providing radial constraint force for the excitation winding 3. This effectively prevents the excitation winding 3 from potentially dislodging from the winding slot 4 due to the large centrifugal force during high-speed operation of the exciter motor, thereby enhancing the overall mechanical reliability of the motor rotor. Simultaneously, the closed winding slot 4 structure helps optimize the distribution of air gap magnetic flux, reduces the generation of cogging harmonics, and makes the air gap magnetic flux waveform smoother. This reduces torque pulsation and electromagnetic noise during motor operation, improving the overall performance of the exciter motor in terms of noise, vibration, and acoustic roughness.

[0047] In one embodiment, such as Figure 3 and Figure 4 As shown, a slot wedge 6 is fitted onto the winding slot 4 of the rotor core 1 facing its circumferential edge, and the slot wedge 6 is fixed to the rotor core 1 in a detachable manner. In actual operation, the excitation winding 3 is first accurately placed inside the winding slot 4, and then the independent slot wedge 6 is installed at the opening position of the winding slot 4. The slot wedge 6 is assembled and fixed to the rotor core 1 by mechanical fixing methods such as snap-fit, abutment, or bolt tightening. In this embodiment, mounting slots are correspondingly provided on the rotor core 1 on both sides of the winding slot 4 near the opening area, and the slot wedge 6 is snap-fitted into the mounting slot to limit the radial displacement of the slot wedge 6 in the rotor core 1. This prevents the slot wedge 6 from loosening during high-speed motor operation, ensuring that the excitation winding 3 is always in a stable and reliable working environment.

[0048] In this embodiment, as Figure 5As shown, a connecting bridge 7 is provided on the outer circumferential edge of the winding slot 4 facing the rotor core 1, and the connecting bridge 7 and the rotor core 1 are integrally formed. Specifically, the connecting bridge 7 is directly punched from the lamination material of the rotor core 1, and then laminated together with the silicon steel sheet of the rotor core 1 in the subsequent lamination process to form an integral component. The presence of the connecting bridge 7 not only enhances the structural strength of the rotor core 1 in this area, but also helps to ensure the positional accuracy of the excitation winding 3 in the winding slot 4. Moreover, eliminating the slot wedge 6 structure increases the effective area of ​​the winding slot 4, increases the number of coil turns, reduces excitation copper loss, and improves motor efficiency.

[0049] In one embodiment, such as Figure 6 As shown, to facilitate the winding and installation of the excitation winding 3, the rotor core 1 includes multiple segmented cores, which are spliced ​​together circumferentially to form the rotor core 1. The winding slot 4 is formed between adjacent segmented cores. The rotor core 1 is composed of multiple independent fan-shaped segmented cores spliced ​​together circumferentially. Each segmented core is an independent module made of stacked silicon steel sheets. The number of segmented cores can vary according to actual needs, and the segmented cores can be fan-shaped, trapezoidal, or other structures that can be spliced ​​together to form a columnar rotor.

[0050] When assembling the motor rotor, the excitation winding 3 can be wound separately on individual segmented cores, and then the segmented cores are spliced ​​together along the circumference. At this time, the gap between adjacent segmented cores naturally forms a complete winding groove 4 to accommodate the excitation winding 3, which facilitates the assembly of the excitation winding 3.

[0051] In one embodiment, such as Figure 7 and Figure 8 As shown, a rotor end plate 8 is installed at at least one end of the rotor core 1 along the axial direction. A shoulder 9 is provided at the position of the rotor end plate 8 corresponding to the position of the magnet slot 5, and the shoulder 9 extends away from the rotor core 1. In this embodiment, rotor end plates 8 are installed at both ends of the rotor core 1. The rotor end plates 8 are made of non-magnetic materials such as aluminum alloy to reduce end magnetic leakage. When the rotor end plates 8 are installed in place, the shoulder 9 precisely covers and presses the end of the magnet slot 5 and the rotor core laminations around it in the axial direction.

[0052] The rotor end plate 8 axially presses the end of the rotor core 1 with a shoulder 9. The shoulder 9 extends and covers the axial opening end of the magnet slot 5. The shoulder 9 structure prevents the rotor core laminations from warping axially and provides axial constraint on the built-in permanent magnet 2. During motor rotor operation, it prevents the permanent magnet 2 from axially shifting or being thrown out, improving the mechanical reliability and safety of the motor rotor during high-speed operation. Using a rotor end plate 8 with a shoulder 9 can press the rotor core to prevent lamination warping, protect the permanent magnet 2, and prevent the permanent magnet 2 or excitation winding 3 from being thrown out at high speeds. At the same time, the rotor dynamic balance problem can be solved by drilling holes in the rotor end plate 8, without needing to drill holes in the core, and without affecting the rotor magnetic circuit and electromagnetic performance.

[0053] In one embodiment, one or more magnet slots 5 are arranged at intervals along the radial direction of the rotor core 1. Permanent magnets 2 are arranged in one or more magnet slots 5 at different radial depths within the rotor core 1. Arranging multiple magnet slots 5 to install multiple layers of permanent magnets 2 can improve the air gap magnetic flux density and the torque output capability of the motor. The cooperation of different layers of permanent magnets 2 can reduce rotor leakage flux and adjust the direct-axis and quadrature-axis inductance, thereby more effectively utilizing reluctance torque and improving the power density and speed range of the excitation motor.

[0054] Furthermore, multiple magnet slots 5 are arranged at intervals between two adjacent inset slots 4. Segmenting the permanent magnets 2 can reduce eddy current losses caused by the continuous distribution of the permanent magnets 2 and reduce the heat generated by the permanent magnets 2. At the same time, the segmented layout of the permanent magnets 2 helps to optimize the sinusoidal waveform of the air gap magnetic field and reduce torque pulsation.

[0055] Specifically, the cross-section of the magnet slot 5 is arranged in a straight line, a V-shape, or a U-shape. For example... Figures 9 to 14 As shown, different shapes of the magnet slots 5 can change the direction of the magnetic field generated after the permanent magnets 2 are installed in the magnet slots 5, thus forming different magnetic circuit structures. In the V-shaped or U-shaped layout, the permanent magnets 2 are further away from the air gap, and the number of permanent magnets 2 is less than in the segmented straight-line layout. Furthermore, by increasing the rib width and magnetic bridge width, the strength of the rotor laminations can be improved to meet the high-speed requirements of over 20,000 rpm. In the segmented straight-line layout, the permanent magnets 2 installed in the magnet slots 5 are closer to the air gap, with a compact arrangement, small rib width, and a narrow magnetic bridge between the permanent magnets and the outer edge of the rotor core 1. This results in a narrow magnetic leakage path and less magnetic leakage, allowing for a larger torque output with the same number of magnets, thus saving costs.

[0056] Typically, the magnetic field slots are arranged in one or two layers. When the magnetic steel slots 5 are arranged in a single layer, they can be in any shape, such as a straight line, a V-shape, or a U-shape. When the magnetic steel slots 5 are arranged in two layers, the outer layer can be arranged in a straight line or a V-shape, and the inner layer can be arranged in a V-shape or a U-shape. The performance of the permanent magnets 2 installed in the double-layered magnetic steel slots 5 is similar to that of the single-layered V-shape or U-shape. The double-layered permanent magnets 2 are equivalent to increasing the thickness of the permanent magnets 2, reducing the direct-axis inductance, and increasing the motor output power. In some other embodiments, the magnetic field slots can also be arranged in three, four, or more layers as needed.

[0057] According to an embodiment of the present invention, a hybrid excitation motor is also provided, having the motor rotor described in this application. During motor operation, the excitation winding 3 is connected to an external excitation power supply via a brush slip ring structure or a rotary transformer to regulate the excitation current. The constant magnetic field generated by the permanent magnet 2 and the controllable magnetic field generated by the excitation winding 3 are coupled inside the rotor and interact with the stator winding through the air gap to generate electromagnetic torque. By adjusting the magnitude and direction of the excitation current, the strength of the air gap magnetic field can be changed, thereby achieving efficient operation of the motor under different operating conditions. In the motor rotor, the permanent magnet 2 is placed inside the rotor core 1 made of silicon steel sheets, and the permanent magnet 2 is axially inserted into the rotor core 1 through the magnetic slots. By completely embedding the permanent magnet 2 within the circumferentially closed magnetic slots 5, the rotor core can provide all-round protection and constraint for the permanent magnet 2, improving the mechanical reliability of the motor rotor structure, especially suitable for high-speed operating conditions. Moreover, the built-in permanent magnet 2 can reduce the overall equivalent air gap of the motor compared to the surface-mounted type, and reduce the magnetic resistance of the magnetic circuit in the exciter motor. As a result, it can generate a stronger air gap magnetic field with the same volume and material usage, thereby improving the torque and power density of the exciter motor.

[0058] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electric machine rotor, characterized in that, The motor rotor comprises a rotor core (1) having a plurality of embedded wire grooves (4) and a plurality of magnetic steel slots (5) formed inside, the plurality of embedded wire grooves (4) are arranged at intervals along the circumference of the rotor core (1), the magnetic steel slots (5) are arranged between two adjacent embedded wire grooves (4), the magnetic steel slots (5) are arranged close to the circumferential edge of the rotor core (1), and the magnetic steel slots (5) are arranged in a closed manner along the circumference. A permanent magnet (2) is embeddedly installed in the magnetic steel slot, so that the rotor core (1) completely surrounds the permanent magnet (2) in the circumference. An excitation winding (3) is installed in two adjacent embedded wire grooves (4). The embedded wire groove (4) is arranged in a closed manner towards one side of the circumferential edge of the rotor core (1).

2. The electric machine rotor of claim 1, wherein, The embedded wire groove (4) is provided with a connecting bridge (7) towards one side of the circumferential edge of the rotor core (1), and the connecting bridge (7) is an integral molding structure with the rotor core (1).

3. The motor rotor of claim 2, wherein, Alternatively, the embedded wire groove (4) is provided with a slot wedge (6) towards one side of the circumferential edge of the rotor core (1), and the slot wedge (6) is detachably installed on the rotor core (1). The rotor core (1) comprises a plurality of block cores, and the plurality of block cores are spliced in a circumferential direction to form the rotor core (1), and the embedded wire groove (4) is formed between two adjacent block cores.

4. The electrical machine rotor according to any one of claims 1 to 3, characterized in that The rotor core (1) is provided with a rotor end plate (8) at least at one end in the axial direction, the rotor end plate (8) is provided with a stop shoulder (9) at a position corresponding to the magnetic steel slot (5), and the stop shoulder (9) extends away from the rotor core (1).

5. The motor rotor of any one of claims 1 to 3, wherein The magnetic steel slots (5) are arranged at intervals in one or more layers along the radial direction of the rotor core (1).

6. The motor rotor of any one of claims 1 to 3, wherein A plurality of magnetic steel slots (5) are arranged at intervals between two adjacent embedded wire grooves (4).

7. The motor rotor of any one of claims 1 to 3, wherein The cross section of the magnetic steel slot (5) is arranged in a straight line, V shape or U shape.

8. The motor rotor of claim 7, wherein, The excitation winding (3) is a round copper wire or a flat copper wire.

9. The motor rotor of any one of claims 1 to 3, wherein, The motor rotor has any one of claims 1-9.

10. A hybrid excitation electric machine, characterized by ​

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