Multi-slot combined rotor suitable for cast copper rotor induction motors for new energy vehicles

Abstract

The present invention discloses a multi-slot type combined rotor suitable for a cast copper rotor induction motor of a new energy vehicle, and relates to the technical field of motor production related equipment, including a rotor core, wherein the rotor core is provided with rectangular slots and trimmed circular slots, and the number ratio of the two slot types is 1:1, so that they appear alternately along the circumferential direction of the rotor. The rectangular slot has a larger slot width and a lower slot depth, has good rated operating performance and a higher peak power, and reduces the critical slip rate, but when the motor speed is low, the surge current is large at startup, the torque is low and varies greatly within a certain range; when the tooth width is appropriate, the size of the trimmed circular slot is close to the size of the rectangular slot, when the motor speed is low, the torque is high within a certain speed range, the distribution of stress on the rotor core is less affected, the rotor has high mechanical strength, reduces the rotor tooth magnetic flux density and the current density of the conductor bar, and increases the conductor bar area. The present invention has a simple structure and good speed regulation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of motor production related equipment, and in particular to a multi-slot combined rotor suitable for a cast copper rotor induction motor for a new energy vehicle. Background Art

[0002] The cast copper rotor induction motor of new energy vehicles adopts a single rotor slot structure, which generally cannot take into account both the high constant torque at low speed and the high constant power at high speed, nor can it take into account both the high peak power and the high load conversion performance. Among them, the rectangular slot has a larger slot width and a lower slot depth, has good rated operating performance and high peak power, and reduces the critical slip rate, but when the motor speed is low, the surge current is large at startup, the torque is low and varies greatly within a certain range; the cut-edge circular rotor slot has a large critical slip rate and a small peak power when the motor speed is high. Other existing multi-slot rotor slots cannot achieve both high peak power at high speed and stable starting torque at low speed. Only when the combined structure of rectangular rotor slots and cut-edge circular rotor slots is adopted, can high peak power at high speed and stable starting torque at low speed be achieved, so that the motor can retain the excellent performance of using two rotor slots alone, and can also eliminate some shortcomings when using two rotor slots alone, reduce the critical slip rate of the motor, increase the peak power of the motor, improve the load conversion performance, and enable the motor to obtain a large and stable starting torque when running at low speed, with wide versatility. The peak power of other simple slot types is not as large as that of the rectangular slot. The torque pulsation of other simple slot types at low speed is not as small as that of the cut-edge circular slot. It is impossible to achieve both high peak power at high speed and stable starting torque at low speed by using other simple slot types. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a multi-slot combined rotor suitable for a cast copper rotor induction motor of a new energy vehicle, which improves the peak power and load conversion performance of the motor and obtains good operating performance under low and high speed conditions.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] A multi-slot combined rotor suitable for a cast copper rotor induction motor of a new energy vehicle comprises a rotor core, wherein a plurality of rotor slots are formed on the rotor core, wherein the rotor slots are rectangular slots and trimmed circular slots; the number ratio of the rectangular slots to the trimmed circular slots is 1:1, and the rectangular slots and the trimmed circular slots are arranged alternately along the circumferential direction of the rotor, and rotor teeth are formed between any two adjacent rotor slots of different types, and the spacing between the rotor teeth is a fixed value.

[0006] Furthermore, the rotor slots are closed axial inclined slots.

[0007] Furthermore, the ratio of the slot width to the slot depth of the rotor rectangular slot is less than 1:1.2 and greater than 1:2.

[0008] Furthermore, the trimmed circular groove is a groove type obtained by trimming both sides of the groove type main body according to the requirement of equal tooth width in order to improve the magnetic flux density of the rotor teeth on the basis of the groove type main body being a circular groove.

[0009] Furthermore, the top of the trimmed circular groove is a large arc, the bottom of the groove is a small arc, the trimmed circular groove is wide at the top and narrow at the bottom, and the width of the trimmed circular groove excluding the arc part gradually becomes wider at the top and narrower at the bottom from the side close to the rotor shaft to the side close to the air gap.

[0010] Furthermore, the rotor slots are evenly distributed along the circumferential direction of the rotor, and the slot pitch is equal to the spacing between the rotor teeth, both of which are constant values, which are 360° divided by the number of rotor slots, and the number of rotor slots is selected according to the slot fit.

[0011] When rectangular slots are used alone, the rotor structure of the induction motor is a parallel slot. The use of rectangular slots has good rated operating performance and normal starting performance, while reducing the critical slip rate and having a higher peak power. Because power is the product of torque and speed, when the maximum torque is almost the same, the greater the critical speed, the greater the peak power. However, when the motor speed is low, the surge current at starting is large, the torque is low and varies greatly within a certain range. When the cut-edge circular slots are used alone, the load conversion performance is improved, that is, the motor has a better performance in changing the speed under large load, the motor has better rigidity, and when the motor speed is low, the torque can be maintained at a high level within a certain speed range.

[0012] In order to reduce the noise and vibration of the cast copper induction motor, the rotor adopts an axial skewed slot structure. Since the cast copper rotor induction motor of new energy vehicles is powered by variable frequency, it can obtain higher starting performance through frequency and voltage regulation, and the type of rotor slot does not need to be designed to be very narrow or deep. The rectangular slot is designed to be a shape with a larger slot width and a lower slot depth (the slot width of the 18.5kW small induction motor is 10mm and the slot depth is 20mm), which can obtain good rated operating performance and normal starting performance, while reducing the critical slip rate and having a higher peak power. However, when the motor speed is low, the surge current at start-up is large, the torque is low and varies greatly within a certain range; while ensuring that the tooth width is appropriate, the size of the cut-edge circular slot is as close as possible to the size of the rectangular slot, and the slot width and slot depth are close to make the slot area close. When the motor speed is low, the torque can be maintained at a high level within a certain speed range, and the distribution of stress on the rotor core is less affected, which can ensure that the rotor has a higher mechanical strength, effectively reduce the rotor tooth flux density, increase the conductor bar area, and reduce the current density on the conductor bar.

[0013] Beneficial effects:

[0014] The existing combined rotor slots cannot achieve both high peak power at high speed and stable starting torque at low speed. When a combined structure of rectangular rotor slots and cut-edge circular rotor slots is adopted, the excellent performance of the two rotor slots used alone can be retained, and some disadvantages of using the two rotor slots alone can be eliminated, thereby reducing the critical slip rate of the motor and increasing the peak power of the motor; improving the load conversion performance, so that the motor can obtain a larger and more stable starting torque when running at a low speed, and has wide versatility.

[0015] Because when the tooth width is appropriate, the area of ​​the trimmed circular slot is close to the area of ​​the rectangular slot, but when the motor speed is low, the torque is high within a certain speed range, the influence on the distribution of stress on the rotor core is small, the rotor has high mechanical strength, the rotor tooth magnetic flux density and the current density of the conductor bar are reduced, and the conductor bar area is increased. For this reason, the present invention must adopt a combination structure of a rectangular rotor slot and a trimmed circular rotor slot. Only when the combination of these two slot shapes is adopted, and when the cast copper rotor induction motor of a new energy vehicle is combined and alternated according to the ratio of the number of rectangular rotor slots and trimmed circular rotor slots of 1:1, can the critical slip rate of the motor be reduced and the peak power of the motor be increased, because power is the product of torque and speed. When the maximum torque is almost the same, the greater the critical speed, the greater the peak power; at the same time, the load conversion performance can be improved, that is, the motor has better performance in changing the speed under large load, and the rigidity of the motor is better; it can also obtain good operating performance under low and high speed conditions, and has wide versatility.

[0016] Therefore, the present invention has a simple structure, changes the arrangement of the rotor slots, increases the maximum torque, reduces rotor losses, and has good speed regulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1a It is a rectangular slot structure diagram;

[0018] Figure 1b This is the structural diagram of the cut edge circular groove;

[0019] Figure 2 A rotor structure diagram showing a combination of two types of rotor slots, rectangular slots and trimmed circular slots, in a 1:1 ratio;

[0020] Figure 3 The figure is a comparative analysis of the speed-torque curves of the three rotor structures.

[0021] Among them, the figures are marked as: 1, rectangular slot; 2, cut-edge circular slot; 3, rotor core; 4, rotor shaft. DETAILED DESCRIPTION

[0022] 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.

[0023] like Figure 1a , Figure 1b , Figure 2 As shown, a multi-slot combined rotor suitable for a cast copper rotor induction motor for a new energy vehicle of the present invention comprises a rotor core 3, on which a plurality of rotor slots are opened, and the rotor slots are of two types, namely, rectangular slots 1 and trimmed circular slots 2, and the number ratio of the two types of rotor slots is 1:1, and they are arranged alternately along the circumferential direction of the rotor, and rotor teeth are formed between any two adjacent rotor slots of different types, and the spacing of the rotor teeth is a fixed value, so the multi-slot combined rotor of the cast copper rotor induction motor for a new energy vehicle is still uniformly distributed along the circumferential direction of the rotor, so no special slot matching is required. The width of the rotor teeth is appropriate, the magnetic flux density is not easy to saturate, the temperature rise is within an acceptable range, and the loss increase is not large.

[0024] The rectangular slot 1 is designed to have a larger slot width and a lower slot depth (the ratio of the slot width to the slot depth is less than 1:1.2 and greater than 1:2), which can obtain good rated operating performance and normal starting performance; the trimmed circular slot 2 is based on the slot body being a circular slot. In order to improve the rotor tooth magnetic flux density, appropriate trimming is performed on both sides of the slot according to the equal tooth width requirements. Under the condition of ensuring that the tooth width is appropriate, the area of ​​the trimmed circular slot 2 is as close as possible to the area of ​​the rectangular slot 1, and the slot width and slot depth are close to make the slot area close. The slot top of the trimmed circular slot 2 is a small arc, and the slot bottom is a large arc. The trimmed circular slot 2 is narrow at the top and wide at the bottom. The trimmed circular slot 2 has little effect on the distribution of stress on the rotor core, which can ensure that the rotor has a higher mechanical strength, effectively reduce the rotor tooth magnetic flux density, and at the same time increase the conductor bar area, reduce the current density on the conductor bar, and reduce the heating and copper loss of the copper bar.

[0025] Preferably, since the spacing of the rotor teeth is a fixed value, 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. Therefore, 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.

[0026] Take the Y2-160L-2 small induction motor as an example. The rated output power of the motor is 18.5kW, the rated voltage is 380V, 2 poles, the stator outer diameter is 260mm, the stator inner diameter is 170mm, the rotor inner diameter is 60mm, the air gap is 0.65mm, the stator core has 30 straight slots, and the single-layer winding. The number of rotor slots is 26, and the stator structure is not changed. Only the rotor slot distribution is double-slot modulated, so that the two types of rotor slots of the rotor, rectangular slots and trimmed circular slots, are combined in a 1:1 ratio and appear alternately along the circumferential direction of the rotor.

[0027] like Figure 1a , Figure 1b As shown, Figure 1a It is a rectangular slot structure. Figure 1b It is a structure of cut-edge circular grooves, and both types of rotor slots are closed slots.

[0028] like Figure 3 The figure shows the comparative analysis of the motor speed-torque curves using three rotor structures. The first curve is the speed-torque relationship of the cast copper induction motor using rectangular slots alone, the second curve is the speed-torque relationship of the cast copper induction motor using trimmed circular slots alone, and the third curve is the speed-torque relationship of the cast copper induction motor with two types of rotor slots, rectangular slots and trimmed circular slots, in a 1:1 combination. Within the low-speed range of the motor, the torque value of the first curve is the smallest and the maximum variation, the torque value of the second curve is the largest and the variation is the second largest, and the torque value of the third curve is relatively large. Within a certain speed range, the torque is almost maintained at a certain value. Within the high-speed range of the motor, the torque value of the first curve is the largest and the variation is the smallest, the torque value of the second curve is the smallest and the variation is the largest, and the torque value of the third curve is relatively large. Within a certain speed range, the variation is relatively small. Comparing the critical slip rates of the three curves, it is found that the critical slip rate of the first curve is the smallest, the critical slip rate of the second curve is the largest, and the process slip rate of the third curve is in the middle. The peak power of the motor using only rectangular slots is the largest, and the peak power of the motor using a combination of rectangular slots and cut-edge circular slots is slightly smaller within the allowable range. The peak power of the motor using only cut-edge circular slots is the smallest. The motor of the third curve has better performance in changing speed under large loads, the torque is almost unchanged, and the load conversion performance is improved.

[0029] 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.

[0030] 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 multi-slot combined rotor suitable for cast copper rotor induction motors of new energy vehicles, characterized in that: The invention comprises a rotor core, wherein a plurality of rotor slots are formed on the rotor core, wherein the rotor slots are rectangular slots and trimmed circular slots; the number ratio of the rectangular slots to the trimmed circular slots is 1:1, and the rectangular slots and the trimmed circular slots are alternately arranged along the circumferential direction of the rotor, and rotor teeth are formed between any two adjacent rotor slots of different types, and the spacing between the rotor teeth is a fixed value; The ratio of the width to the depth of the rotor rectangular slot is less than 1:1.2 and greater than 1:2; The top of the trimmed circular groove is a large arc, the bottom of the groove is a small arc, and the width of the trimmed circular groove excluding the arc portion gradually becomes wider inside and narrower outside from the side close to the rotor shaft to the side close to the air gap; The rotor slots are evenly distributed along the circumferential direction of the rotor, and the slot pitch is equal to the spacing between the rotor teeth, which 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 fit.

2. A multi-slot combined rotor suitable for a cast copper rotor induction motor for new energy vehicles according to claim 1, characterized in that: The rotor slots are closed axial skew slots.

3. The multi-slot combined rotor suitable for the cast copper rotor induction motor of new energy vehicles according to claim 1, characterized in that: The trimmed circular groove is a groove type obtained by trimming both sides of the groove type main body according to the requirement of equal tooth width in order to improve the magnetic flux density of the rotor teeth on the basis of the groove type main body being a circular groove.

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