Rotor slot design method based on motor stall characteristics

Abstract

The present invention relates to a rotor slot design method based on motor stall characteristics, belongs to the field of motor technology, and solves the technical problems that the existing single rotor slot cannot achieve the matching of motor starting performance and working conditions, and has poor economic benefits. The solution is: a rotor slot design method based on motor stall characteristics, comprising the following steps: 1) designing a first rotor slot and a second rotor slot, the first rotor slot and the second rotor slot have the same shape, the br1 of the first rotor slot is greater than the br1' of the second rotor slot, and the br2 of the first rotor slot is greater than the br2' of the second rotor slot; 2) when the motor is in the first gear power, the situation of the stall current closest to the standard is selected as the most preferred rotor punching slot; 3) when the motor is in the second, third, fourth and fifth gear power, the rotor punching adopts a combination of different numbers of first rotor slots and second rotor slots in different arrangements and combinations, and the most preferred is selected with the optimal stall current as the target.

Description

Technical Field

[0001] The invention belongs to the technical field of motors, and in particular relates to a rotor slot design method based on motor stall characteristics. Background Art

[0002] The rotor slot type has an important influence on the performance of the motor. Changing the cage rotor slot type and related dimensions can change the motor starting performance within a large range. Under the condition that the stator design remains unchanged, the appropriate change of the rotor slot type can obtain better starting performance. The quality factor Kst is generally used to measure the starting performance of the motor. The quality factor Kst is calculated as the ratio of the stall torque Tst to the stall current Ist, that is, Kst=Tst / Ist. Ist is controlled within a reasonable range. The larger the quality factor, the more the motor can adapt to the stringent starting requirements. It is known from motor science that the stall torque Tst∝r2s / Zst 2 , the locked-rotor current Ist∝1 / Zst, where Zst is the total impedance during starting and r2s is the rotor starting resistance.

[0003] At present, low-voltage high-power cage rotor motors with the same frame number, the same number of poles and different powers all use the same rotor slot type to ensure the universality of the mold. However, the power range of low-voltage high-power motors with the same center height and the same number of poles is relatively large, generally exceeding 5 power levels. The electromagnetic design is carried out under the boundary conditions of equal proportional iron length and equal temperature rise. As the power and iron length increase, the rotor starting resistance r2s remains basically unchanged, the stator resistance r1, the stator end leakage reactance Xe1 at start-up, and the rotor end leakage reactance Xe2 at start-up gradually decrease, and the total impedance Zst at start-up decreases, which leads to a significant increase in the stall torque Tst and the stall current Ist. This leads to the problem that the stall torque Tst and the stall current Ist of small power specifications are too small, and the stall torque Tst and the stall current Ist of large power specifications are too large. As the market demand for high-efficiency, low-voltage, high-power motors continues to increase, customers have different requirements for the stall current and stall torque of motors of the same specification in different application conditions. A single rotor slot shape cannot match the motor starting performance with all operating conditions. Motors under different working conditions need to be customized according to load and application scenarios, which results in an increase in molds and poor economic benefits. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art and solve the technical problems that the existing single rotor slot type cannot match the motor starting performance with the working conditions and has poor economic benefits, the present invention provides a rotor slot design method based on the motor stall characteristics.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a rotor slot design method based on the stall characteristics of a motor, wherein the motors have the same center height and the same number of poles, and the motors include a first gear power, a second gear power, a third gear power, a fourth gear power and a fifth gear power from small to large, and include the following steps: 1) Designing a first rotor slot type and a second rotor slot type, wherein the first rotor slot type and the second rotor slot type have the same shape, br1 of the first rotor slot type is greater than br1' of the second rotor slot type, and br2 of the first rotor slot type is greater than br2' of the second rotor slot type; 2) When the motor is in the first power gear, the rotor punchings are evenly distributed with a number of first rotor slot types and a number of second rotor slot types. The quality factor and the stall current of the motor are calculated in the two cases. The stall current closest to the standard is selected as the most preferred rotor punching slot type, and the stall current is the optimal stall current; 3) When the motor is in the second power gear, the third power gear, the fourth power gear and the fifth power gear, the rotor punching is arranged by combining different numbers and different combinations of the first rotor slot type and the second rotor slot type, and the quality factor and the stall current of the motor when running in different numbers and different combinations are calculated, and the optimal stall current obtained in step 2) is used as the target to select the most preferred rotor punching slot type.

[0007] Further, the first rotor slot type and the second rotor slot type both include an arc edge, two upper opposite side edges, two upper parallel straight edges, two lower opposite side edges and lower parallel straight edges, the arc edge is connected to the two upper opposite side edges, the two upper opposite side edges are inclined outwardly relative to the arc edge, the two upper opposite side edges are connected to the two upper parallel straight edges, the two upper parallel straight edges are connected to the two lower opposite side edges, the two lower opposite side edges are inclined inwardly relative to the upper parallel straight edges, and the two lower opposite side edges are respectively connected to the lower parallel straight edges.

[0008] Furthermore, the motor is a center height 315 two-pole motor, the first gear power is 110kW, the second gear power is 132kW, the third gear power is 160kW, the fourth gear power is 185kW, and the fifth gear power is 200kW.

[0009] Furthermore, the size of br1 of the first rotor slot type is 1.5 mm, and the size of br2 of the first rotor slot type is 3.0 mm; the size of br1' of the second rotor slot type is 1.0 mm, and the size of br2' of the second rotor slot type is 2.7 mm.

[0010] Furthermore, when the motor is in the first gear with a power of 110 kW, the most preferred rotor slot type is that the rotor slots are evenly distributed with 40 first rotor slots, and the optimal locked-rotor current is 7.0.

[0011] Furthermore, when the motor is in the second gear with a power of 132 kW, the most preferred configuration of the rotor punching slots is a combination of 24 first rotor slots and 16 second rotor slots.

[0012] Furthermore, when the motor is in the third gear with a power of 160 kW, the most preferred configuration of the rotor punching slots is a combination of 16 first rotor slots and 24 second rotor slots.

[0013] Furthermore, when the motor is in the fourth gear with a power of 185 kW, the most preferred configuration of the rotor punching slots is a combination of 8 first rotor slots and 32 second rotor slots.

[0014] Furthermore, when the motor is in the fifth gear with a power of 200 kW, the most preferred rotor punching slot type is that 40 second rotor slot types are evenly distributed on the rotor punchings.

[0015] The beneficial effects achieved by the present invention are as follows: the present invention proposes a rotor slot design method for improving the stall characteristics of motors with the same center height and the same number of poles and different powers, designs a first rotor slot and a second rotor slot, the first rotor slot and the second rotor slot have the same shape, br1 of the first rotor slot is greater than br1' of the second rotor slot, br2 of the first rotor slot is greater than br2' of the second rotor slot, the size of br1 and br2 mainly affects the rotor slot leakage reactance Xs2s and the rotor starting resistance r2s when the motor starts, the smaller br1 and br2 are, the larger the rotor slot leakage reactance Xs2s and the rotor starting resistance r2s are when starting, the total impedance Zst is improved when starting, and the increase of the total impedance Zst when starting is much greater than the rotor starting resistance r2s, so the stall torque Tst and the stall current Ist are reduced, so that the stall torque T of the first rotor slot is reduced. st and the stall current Ist are both larger than those of the second rotor slot type; the first rotor slot type and the second rotor slot type are arranged in different numbers and different combinations on the rotor punching sheet, the more the first rotor slot types are, the larger the stall torque Tst and the stall current Ist are, and the more the second rotor slot types are, the smaller the stall torque Tst and the stall current Ist are. The double-slot design of the rotor with the first rotor slot type and the second rotor slot type can avoid the unreasonable stall characteristics of the motor caused by a single rotor slot type, and solves the problem of increased molds and poor economic benefits caused by customized processing of different customer motors for different loads and application scenarios; in addition, the present invention, through the design of the double-slot rotor, also triggers the idea of ​​designing a rotor with multiple slots. According to the method of the present invention, a number of rotor slots are designed. By setting a number of rotor slots in different numbers and different combinations, the optimal rotor punching slot type is achieved under different powers.

[0016] Compared with the prior art, the present invention has the advantages of designing a double-slot rotor to match the motor starting performance with the working conditions and improve the economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the first rotor slot type in the present invention; Figure 2 is a schematic structural diagram of the second rotor slot type in the present invention; Figure 3 This is a schematic diagram of the most preferred structure of the rotor punching slot type when the motor is in the first gear with a power of 110 kW in the present invention; Figure 4 This is a schematic diagram of the most preferred structure of the rotor punching slot type when the motor is in the second gear with a power of 132kW in the present invention; Figure 5 This is a schematic diagram of the most preferred structure of the rotor punching slot type when the motor is in the third gear with a power of 160kW in the present invention; Figure 6 This is a schematic diagram of the most preferred structure of the rotor punching slot type when the motor is in the fourth gear with a power of 185kW in the present invention; Figure 7 It is a schematic structural diagram of the most preferred rotor punching slot type when the motor is in the fifth gear with a power of 200 kW in the present invention.

[0018] In the figure: 1. first rotor slot type; 2. second rotor slot type; 3. arc edge; 4. upper opposite side edge; 5. upper parallel straight edge; 6. lower opposite side edge; 7. lower parallel straight edge. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0020] like Figures 1 to 7 As shown, the rotor slot design method based on the stall characteristics of the motor, the motors have the same center height and the same number of poles, the motors include a first gear power, a second gear power, a third gear power, a fourth gear power and a fifth gear power from small to large, the motor in this embodiment is a two-pole motor with a center height of 315, the first gear power is 110kW, the second gear power is 132kW, the third gear power is 160kW, the fourth gear power is 185kW, and the fifth gear power is 200kW, comprising the following steps: 1) Design a first rotor slot type 1 and a second rotor slot type 2. The first rotor slot type 1 and the second rotor slot type 2 have the same shape. The br1 of the first rotor slot type 1 is larger than the br1' of the second rotor slot type 2. The br2 of the first rotor slot type 1 is larger than the br2' of the second rotor slot type 2. The other dimensions are the same. The size of br1 and br2 mainly affects the rotor slot leakage reactance Xs2s and the rotor starting resistance r2s when the motor starts. The smaller br1 and br2 are, the larger the rotor slot leakage reactance Xs2s and the rotor starting resistance r2s are when the motor starts. The total impedance Zst is increased when starting, and the increase in the total impedance Zst when starting is much larger than the rotor starting resistance r2s. Therefore, the stall torque Tst and the stall current Ist are reduced. In this way, the stall torque Tst and the stall current Ist of the first rotor slot type 1 are larger than those of the second rotor slot type 2. The first rotor slot type 1 and the second rotor slot type 2 both include an arc edge 3, two upper opposite side edges 4, two upper parallel straight edges 5, two lower opposite side edges 6 and a lower parallel straight edge 7, the arc edge 3 is connected to the two upper opposite side edges 4, the two upper opposite side edges 4 are inclined outwardly relative to the arc edge 3, the two upper opposite side edges 4 are connected to the two upper parallel straight edges 5, the two upper parallel straight edges 5 are connected to the two lower opposite side edges 6, the two lower opposite side edges 6 are inclined inwardly relative to the upper parallel straight edges 5, and the two lower opposite side edges 6 are respectively connected to the lower parallel straight edges 7.

[0021] In this embodiment, the size of br1 of the first rotor slot type 1 is 1.5 mm, and the size of br2 of the first rotor slot type 1 is 3.0 mm; the size of br1' of the second rotor slot type 2 is 1.0 mm, and the size of br2' of the second rotor slot type 2 is 2.7 mm, so that the area of ​​the first rotor slot type 1 can completely cover the area of ​​the second rotor slot type 2, and the locked-rotor torque Tst and the locked-rotor current Ist of the first rotor slot type 1 are both larger than those of the second rotor slot type 2; 2) When the motor is in the first power gear, the rotor punchings are evenly distributed with a number of first rotor slot types 1 and a number of second rotor slot types 2. The quality factor and the stall current of the motor when running in the two cases are calculated. The stall current closest to the standard is selected as the most preferred rotor punching slot type, and the stall current is the optimal stall current; In this embodiment, when the motor is in the first gear power of 110kW, the rotor punchings are evenly distributed with 40 first rotor slots 1 and 40 second rotor slots 2. When the rotor punchings are evenly distributed with 40 first rotor slots 1, the quality factor Kst of the motor is 2.12 / 7.04=0.30, and the locked-rotor current Ist is 7.04. When the rotor punchings are evenly distributed with 40 second rotor slots 2, the quality factor Kst of the motor is 1.97 / 6.16=0.32, and the locked-rotor current is 6.16. Generally speaking, the standard locked-rotor current is generally around 7, so the situation closest to the standard locked-rotor current is that the rotor punchings are evenly distributed with 40 first rotor slots 1, and the optimal locked-rotor current is 7.0. 3) When the motor is in the second power gear, the third power gear, the fourth power gear and the fifth power gear, the rotor punching is arranged by combining different numbers and different arrangements and combinations of the first rotor slot type 1 and the second rotor slot type 2, and the quality factor and the stall current of the motor when running in different numbers and different arrangements and combinations are calculated, and the optimal rotor punching slot type is selected with the optimal stall current obtained in step 2) as the target.

[0022] When the motor is in the second gear with a power of 132 kW, different numbers and combinations of the first rotor slot types 1 and the second rotor slot types 2 are arranged on the rotor punchings. Through the goal of an optimal stall current of 7.0, the most preferred rotor punching slot type is a combination of 24 first rotor slot types 1 and 16 second rotor slot types 2. The quality factor Kst of the motor is 2.28 / 7.06=0.32, and the stall current Ist is 7.06.

[0023] When the motor is in the third gear with a power of 160kW, different numbers and combinations of the first rotor slot types 1 and the second rotor slot types 2 are arranged on the rotor punchings. Through the goal of an optimal stall current of 7.0, the most preferred rotor punching slot type is finally obtained as a combination of 16 first rotor slot types 1 and 24 second rotor slot types 2. The quality factor Kst of the motor is 2.42 / 7.12=0.34, and the stall current Ist is 7.12.

[0024] When the motor is in the fourth gear with a power of 185kW, different numbers and combinations of the first rotor slot types 1 and the second rotor slot types 2 are arranged on the rotor punchings. Through the goal of an optimal stall current of 7.0, the most preferred rotor punching slot type is a combination of 8 first rotor slot types 1 and 32 second rotor slot types 2. The quality factor Kst of the motor is 2.44 / 6.99=0.35, and the stall current Ist is 6.99.

[0025] When the motor is in the fifth gear with a power of 200kW, different numbers and combinations of the first rotor slot type 1 and the second rotor slot type 2 are arranged on the rotor punchings. Through the goal of the optimal stall current of 7.0, the most preferred rotor punching slot type is that 40 second rotor slot types 2 are evenly distributed on the rotor punchings. The quality factor Kst of the motor is 2.52 / 7.03=0.36, and the stall current Ist is 7.03.

[0026] In the present invention, the first rotor slot type 1 and the second rotor slot type 2 are arranged in different numbers and in different combinations on the rotor punching sheet. The more first rotor slot types 1, the greater the stall torque Tst and the stall current Ist, and the more second rotor slot types 2, the smaller the stall torque Tst and the stall current Ist. The double-slot design of the first rotor slot type 1 and the second rotor slot type 2 can avoid the unreasonable stall characteristics of the motor caused by a single rotor slot type, and solve the problem of increased molds and poor economic benefits caused by customized processing of different customer motors for different loads and application scenarios. In addition, the present invention, through the design of the double-slot rotor, also triggers the idea of ​​designing a rotor with multiple slots. According to the method of the present invention, a plurality of rotor slots are designed. By setting a plurality of rotor slots in different numbers and in different combinations, the optimal rotor punching slot type is achieved under different powers.

[0027] The above describes in detail the implementation modes of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes. The implementation modes can still be changed within the knowledge scope of ordinary technicians in the field. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A rotor slot design method based on the stall characteristics of a motor, wherein the motors have the same center height and the same number of poles, and the motors include a first gear power, a second gear power, a third gear power, a fourth gear power and a fifth gear power from small to large, characterized in that: The steps include: 1) designing a first rotor slot type (1) and a second rotor slot type (2), wherein the first rotor slot type (1) and the second rotor slot type (2) have the same shape, br1 of the first rotor slot type (1) is greater than br1' of the second rotor slot type (2), and br2 of the first rotor slot type (1) is greater than br2' of the second rotor slot type (2); 2) When the motor is in the first power level, the rotor laminations are evenly distributed with a plurality of first rotor slot types (1) and a plurality of second rotor slot types (2), and the quality factor and the stall current of the motor when running in the two situations are calculated. The stall current closest to the standard is selected as the most preferred rotor lamination slot type, and the stall current is the optimal stall current; 3) When the motor is in the second power gear, the third power gear, the fourth power gear and the fifth power gear, the rotor punching is arranged by combining different numbers and different arrangements and combinations of the first rotor slot type (1) and the second rotor slot type (2), and the quality factor and the stall current of the motor when running in different numbers and different arrangements and combinations are calculated, and the optimal rotor punching slot type is selected with the optimal stall current obtained in step 2) as the target.

2. The rotor slot design method based on motor stall characteristics according to claim 1 is characterized in that: The first rotor slot type (1) and the second rotor slot type (2) both comprise an arc edge (3), two upper opposite side edges (4), two upper parallel straight edges (5), two lower opposite side edges (6) and a lower parallel straight edge (7); the arc edge (3) is connected to the two upper opposite side edges (4); the two upper opposite side edges (4) are inclined outwardly relative to the arc edge (3); the two upper opposite side edges (4) are connected to the two upper parallel straight edges (5); the two upper parallel straight edges (5) are connected to the two lower opposite side edges (6); the two lower opposite side edges (6) are inclined inwardly relative to the upper parallel straight edges (5); and the two lower opposite side edges (6) are respectively connected to the lower parallel straight edges (7).

3. The rotor slot design method based on motor stall characteristics according to claim 1 is characterized in that: The motor is a center height 315 two-pole motor, the first gear power is 110kW, the second gear power is 132kW, the third gear power is 160kW, the fourth gear power is 185kW, and the fifth gear power is 200kW.

4. The rotor slot design method based on motor stall characteristics according to claim 3 is characterized in that: The size of br1 of the first rotor slot type (1) is 1.5 mm, and the size of br2 of the first rotor slot type (1) is 3.0 mm; the size of br1' of the second rotor slot type (2) is 1.0 mm, and the size of br2' of the second rotor slot type (2) is 2.7 mm.

5. The rotor slot design method based on motor stall characteristics according to claim 4 is characterized in that: When the motor is in the first gear with a power of 110 kW, the most preferred rotor slot type is 40 evenly distributed rotor slots (1), and the optimal locked-rotor current is 7.

0.

6. The rotor slot design method based on motor stall characteristics according to claim 5 is characterized in that: When the motor is in the second gear with a power of 132 kW, the most preferred rotor sheet slot type is a combination of 24 first rotor slot types (1) and 16 second rotor slot types (2).

7. The rotor slot design method based on motor stall characteristics according to claim 6 is characterized in that: When the motor is in the third gear with a power of 160 kW, the most preferred rotor slot type is a combination of 16 first rotor slot types (1) and 24 second rotor slot types (2).

8. The rotor slot design method based on motor stall characteristics according to claim 7 is characterized in that: When the motor is in the fourth gear with a power of 185 kW, the most preferred rotor slot type is a combination of 8 first rotor slot types (1) and 32 second rotor slot types (2).

9. The rotor slot design method based on motor stall characteristics according to claim 8, characterized in that: When the motor is in the fifth gear with a power of 200 kW, the most preferred rotor slot type is 40 second rotor slot types (2) evenly distributed on the rotor slots.

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