Segmented combined rotor slots for cast copper rotor induction motors for new energy vehicles
The segmented combined rotor slot design for cast copper rotor induction motors addresses torque and power issues by combining specific slot types to enhance starting torque, peak power, and efficiency, reducing harmonic flux density and critical slip rates.
Patent Information
- Application Number
- CN202410871014.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-01
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2044-07-01
AI Technical Summary
Existing cast copper rotor induction motors for new energy vehicles face issues with torque-speed offset curves, low starting torque, large torque fluctuations, high critical slip rates, and insufficient peak power due to traditional rotor slot structures that fail to balance motor efficiency and starting performance while maintaining low harmonic flux density.
A segmented combined rotor slot design for cast copper rotor induction motors, comprising four different slot types - rectangular, inverted isosceles trapezoidal, isosceles trapezoidal, and sinusoidal structures - arranged radially and circumferentially, with specific geometric configurations to reduce harmonic flux density and maintain fundamental air gap flux density, enhancing starting torque and peak power.
The design achieves improved motor efficiency, reduced losses, and higher starting torque with smaller critical slip rates and peak power by effectively combining slot structures, while maintaining fundamental air gap flux density, thus optimizing torque and power performance.
Smart Images
Figure CN118646181B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of motor production related equipment, and in particular to a segmented combined rotor slot suitable for a cast copper rotor induction motor of a new energy vehicle. Background Art
[0002] The cast copper rotor induction motor of new energy vehicles adopts the traditional simpler rotor slot structure, and the motor cannot obtain a good torque-speed offset curve. When the motor runs at low speed, the starting torque of the two-stage trapezoidal slot structure combination is small and the torque fluctuation is large. Although the single-stage sinusoidal structure can reduce the harmonic content of the air gap, the critical slip rate is large and the peak power cannot reach a high level. The two-stage and three-stage combined rotor slots in the prior art generally only have the function of balancing the motor efficiency and starting performance, and cannot take into account both high peak power and high starting torque. And these combined slot types cannot reduce the harmonic flux density, because other combined slot types make the rotor teeth no longer resemble parallel tooth structures, which will cause the air gap flux density waveform to be distorted. Summary of the invention
[0003] In order to solve the above technical problems, improve the peak power and starting torque of the motor, reduce losses and improve efficiency, the present invention provides a segmented combined rotor slot suitable for the cast copper rotor induction motor of new energy vehicles, using four different slot types as rotor slots, and the double trapezoidal structure composed of inverted isosceles trapezoidal segments and isosceles trapezoidal segments has a smaller critical slip rate and higher peak power when the maximum torque is higher. When the fundamental air gap flux density of the sinusoidal structure remains unchanged, the third, fifth and other homogeneous air gap flux densities are reduced to improve the efficiency of the motor. The combination of rectangular slots, two-stage trapezoidal structures and one-stage sinusoidal structure can simultaneously obtain good performance of each. The present invention has a simple structure, effectively improves the starting torque and maximum peak power, and reduces losses.
[0004] In order to achieve the above object, the present invention adopts the following technical scheme:
[0005] A segmented combined rotor slot suitable for a cast copper rotor induction motor of a new energy vehicle comprises a rotor core, a plurality of segmented combined rotor slots are opened on the rotor core, and the segmented combined rotor slots are sequentially provided with four different slot types, namely a rectangular notch section, an inverted isosceles trapezoid section, an isosceles trapezoid section and a sinusoidal structure section, along the radial direction of the rotor from a side close to an air gap to a side close to a rotating shaft; rotor teeth are formed between any two adjacent slot types, and the spacing between the rotor teeth is a fixed value.
[0006] Furthermore, the rotor slot is a semi-open axial oblique slot.
[0007] Furthermore, the groove depth of the inverted isosceles trapezoidal segment is greater than the groove depth of the isosceles trapezoidal segment.
[0008] Furthermore, the slope of the hypotenuse of the isosceles trapezoidal segment is greater than the slope of the hypotenuse of the inverted isosceles trapezoidal segment.
[0009] Furthermore, the sinusoidal structure segment opens upward and is wider at the top and narrower at the bottom.
[0010] Furthermore, the plurality of segmented combined rotor slots are evenly distributed along the circumferential direction of the rotor.
[0011] Furthermore, the slot pitch of the segmented combined rotor slots along the rotor circumferential direction is a constant value, which is 360° divided by the number of rotor slots, and the number of rotor slots is selected according to the matching of the slots; the slot pitch is equal to the spacing of the rotor teeth.
[0012] In order to reduce the noise and vibration of the cast copper induction motor, the rotor adopts an axial skewed slot structure. The slot depths of the two trapezoidal slot structures of the segmented combined rotor slot are different, and the slot depth of the first trapezoidal slot structure close to the air gap is larger; the slopes of the two trapezoidal slot structures of the combined rotor slot are different, and the slope of the second trapezoidal slot structure close to the shaft is larger.
[0013] Beneficial effects:
[0014] The segmented combined rotor slots in the prior art can effectively reduce the third, fifth and other homogeneous air gap magnetic density while failing to ensure that the fundamental air gap magnetic density remains basically unchanged. Reducing the harmonic magnetic density can effectively improve the motor efficiency and reduce losses. At the same time, a larger starting torque can be obtained when the motor is running at a low speed, the critical slip rate can be reduced, and a higher peak power can be obtained. Only by using the four specific segmented combined rotor slots of the present invention can the excellent performance of each segment slot type be obtained while eliminating some of the shortcomings of each segment rotor slot being used alone. While ensuring that the fundamental air gap magnetic density remains basically unchanged, the third, fifth and other homogeneous air gap magnetic density can be effectively reduced. Reducing the harmonic magnetic density can effectively improve the motor efficiency and reduce losses. At the same time, a larger starting torque can be obtained when the motor is running at a low speed, and a higher peak power can be obtained when the motor is running at a high speed.
[0015] The present invention reduces the critical slip, increases the maximum peak power, increases the starting torque, reduces the loss and improves the efficiency by combining slot structures of various shapes while facilitating the processing of the rotor slot, and has wide versatility. The segmented combined rotor slot of the present invention is divided into four different slot types along the radial direction of the rotor, from the side close to the air gap to the side close to the rotating shaft, including rectangular slots, inverted isosceles trapezoids, isosceles trapezoids and sinusoidal structures. The combination of two-stage trapezoidal slot structures can reduce the critical slip and have a higher peak power, but when the motor runs at a low speed, the starting torque is small and the torque fluctuation is large. One section of the sinusoidal structure of the segmented combined rotor slot opens upward, is wide at the top and narrow at the bottom. Although this section of the sinusoidal structure can reduce the harmonic content of the air gap, the critical slip is large and the peak power cannot reach a high level. Therefore, the use of segmented combined rotor slots can simultaneously obtain the excellent performance of each segment slot type when used alone. At the same time, the combination of each segment slot type can eliminate some of the shortcomings of using each segment rotor slot alone. While ensuring that the fundamental air gap flux density remains basically unchanged, the third, fifth and other homogeneous air gap flux densities can be effectively reduced. Reducing the harmonic flux density can effectively improve the motor efficiency and reduce losses. At the same time, a larger starting torque can be obtained when the motor runs at low speed. At the same time, the distribution of stress on the rotor core is less affected, which can ensure that the rotor has a higher mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a diagram of the structure of the segmented combined rotor slot;
[0017] Figure 2 This is a structural diagram of the segmented combined rotor slots of the cast copper rotor induction motor for new energy vehicles of the present invention;
[0018] Figure 3 This is a speed-torque curve analysis diagram of the segmented combined rotor slots of the cast copper rotor induction motor suitable for new energy vehicles of the present invention.
[0019] Figure 4 This is an analysis diagram of the air gap flux waveform of the segmented combined rotor slots of the cast copper rotor induction motor suitable for new energy vehicles of the present invention.
[0020] In the figure: 1. Segmented combined rotor slot; 10. Rectangular slot section; 11. Inverted isosceles trapezoid section; 12. Isosceles trapezoid section; 13. Sinusoidal structure section; 2. Rotor core; 3. Rotor shaft. DETAILED DESCRIPTION
[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.
[0022] like Figure 2 As shown, the segmented combined rotor slots suitable for the cast copper rotor induction motor of the new energy vehicle of the present invention include a rotor core 2, and a plurality of segmented combined rotor slots 1 are opened on the rotor core 2. The segmented combined rotor slots 1 are arranged along the radial direction of the rotor, from the side close to the air gap to the side close to the rotating shaft, with four different slot types, namely, a rectangular notch section, an inverted isosceles trapezoid section, an isosceles trapezoid section, and a sinusoidal structure section. Rotor teeth are formed between any two adjacent slot types, and the spacing between the rotor teeth is a fixed value. Therefore, the multi-slot combined rotor of the cast copper rotor induction motor of the new energy vehicle is still evenly distributed along the circumferential direction of the rotor, so no special slot matching is required.
[0023] like Figure 1 As shown, the segmented combined rotor slot is respectively provided with a rectangular slot section, an inverted isosceles trapezoid section, an isosceles trapezoid section and a sinusoidal structure section along the radial direction of the rotor from the side close to the air gap to the side close to the rotating shaft.
[0024] Preferably, the segmented combined rotor slots are evenly and symmetrically distributed along the circumferential direction of the rotor, and the slot pitch is a constant. When selecting the stator and rotor slot matching of the induction motor, the traditional slot matching that does not generate asynchronous additional torque and synchronous additional torque should be selected as much as possible to better suppress electromagnetic noise.
[0025] Take the Y2-160L-2 small induction motor as an example. The motor has a rated output power of 18.5kW, a rated voltage of 380V, 2 poles, a stator outer diameter of 260mm, a stator inner diameter of 170mm, a rotor inner diameter of 60mm, an air gap of 0.65mm, 30 straight slots in the stator core, and a single-layer winding. The number of rotor slots is 37. The stator structure is not changed, and only the rotor slot structure is combined in sections.
[0026] like Figure 1As shown, the upper half of the segmented combined rotor slot 1 is opened to form a rectangular slot section 10, and four different slot types, namely, a rectangular slot section 10, an inverted isosceles trapezoidal section 11, an isosceles trapezoidal section 12 and a sinusoidal structure section 13, are sequentially arranged along the radial direction of the rotor from the side close to the air gap to the side close to the rotating shaft. The rectangular slot section 10 is a narrow and shallow rectangular slot, the inverted isosceles trapezoidal section 11 is an inverted isosceles trapezoidal section that is wide at the top and narrow at the bottom, the isosceles trapezoidal section 12 is an isosceles trapezoidal section that is narrow at the top and wide at the bottom, the isosceles trapezoidal slot structure depth of the inverted isosceles trapezoidal section 11 is greater than or equal to the isosceles trapezoidal depth of the isosceles trapezoidal section 12, and the fourth part structure is a sinusoidal structure section 13 that opens upward. The double trapezoidal structure composed of the inverted isosceles trapezoidal section 11 and the isosceles trapezoidal section 12 can obtain a smaller critical slip and a higher peak power while ensuring a higher maximum torque. The sinusoidal structure segment 13 of the fourth part can effectively reduce the third, fifth and other homogeneous air gap magnetic fluxes while ensuring that the fundamental air gap magnetic flux remains basically unchanged. Reducing the harmonic magnetic flux can effectively improve the motor efficiency and reduce losses. At the same time, a larger starting torque can be obtained when the motor runs at a low speed, but the critical slip rate is large and the peak power cannot reach a high level.
[0027] like Figure 2 As shown, the segmented combined rotor slots 1 are composed of four segments of slots. The segmented combined rotor slots 1 are evenly and symmetrically distributed along the circumferential direction of the rotor. The slot pitch is a constant value, which is 360° divided by the number of rotor slots. The number of rotor slots is selected according to the slot matching.
[0028] like Figure 3 As shown, within the low-speed variation range of the motor, the starting torque value is larger and the variation range is smaller, that is, the torque pulsation is smaller. When the motor runs at high speed, the critical slip rate is smaller, the maximum torque is larger, and the peak power is larger. Because power is the product of torque and speed, when the maximum torque is almost the same, the larger the critical speed, the greater the peak power.
[0029] like Figure 4 As shown, the sinusoidal structure slot 13 can effectively reduce the third-order, fifth-order and other homogeneous air gap flux densities while ensuring that the fundamental air gap flux density remains basically unchanged. Reducing the harmonic flux density can effectively improve the motor efficiency and reduce losses.
[0030] It should be understood that the orientation or positional relationship indicated in the terms is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0031] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A segmented combined rotor slot suitable for a cast copper rotor induction motor for a new energy vehicle, characterized in that: The invention comprises a rotor core, on which a plurality of segmented combined rotor slots are provided, wherein the segmented combined rotor slots are sequentially provided with four different slot types, namely, a rectangular slot section, an inverted isosceles trapezoid section, an isosceles trapezoid section and a sinusoidal structure section, along the radial direction of the rotor from the side close to the air gap to the side close to the rotating shaft; rotor teeth are formed between any two adjacent slot types, and the spacing between the rotor teeth is a fixed value; The groove depth of the inverted isosceles trapezoidal segment is greater than the groove depth of the isosceles trapezoidal segment; The slope of the hypotenuse of the isosceles trapezoidal segment is greater than the slope of the hypotenuse of the inverted isosceles trapezoidal segment; The sinusoidal structure section opens upward and is wider at the top and narrower at the bottom.
2. The segmented combined rotor slot suitable for the cast copper rotor induction motor of new energy vehicles according to claim 1 is characterized in that: The rotor slots are semi-open axial skew slots.
3. The segmented combined rotor slot suitable for the cast copper rotor induction motor of new energy vehicles according to claim 1 is characterized in that: The plurality of segmented combined rotor slots are evenly distributed along the circumferential direction of the rotor.
4. The segmented combined rotor slot suitable for the cast copper rotor induction motor of new energy vehicles according to claim 1 is characterized in that: The slot pitch of the segmented combined rotor slots along the rotor circumferential direction is a constant value, which is 360° divided by the number of rotor slots, and the number of rotor slots is selected according to the matching of the slots; the slot pitch is equal to the spacing of the rotor teeth.