WO2023236032A1 - Permanent magnet synchronous motor and rotor thereof - Google Patents

Abstract

Provided are a permanent magnet synchronous motor and a rotor thereof. The rotor comprises a rotor iron core (10) and a plurality of permanent magnets (20); grooves (11) and protrusions (12) are alternately distributed and formed on the outer peripheral surface of the rotor iron core (10); the grooves (11) are arranged at equal angular intervals and pass through the rotor iron core (10) in a direction parallel to the axis of the rotor iron core (10); the permanent magnets (20) are fixedly mounted in the grooves (11); and the permanent magnets (20) and the protrusions (12) form, on the outer peripheral surface of the rotor iron core (10), first magnetic poles and second magnetic poles that are alternately distributed in a circumferential direction and have opposite polarities; and the pole arc coefficient of the permanent magnets (20) is set to be greater than 1. The rotor iron core (10) is used to constitute a magnetic pole having a polarity opposite to the polarities of the permanent magnets (20), so that the pole arc coefficient of the permanent magnets (20) can be set to exceed a conventional range, thereby increasing the output torque of the motor, and improving the performance of the motor. In addition, the proportional relationship of the pole arc angles occupied by two magnetic poles is reasonably adjusted, and when the output torque of the motor can reach a predetermined requirement, the use amount of the permanent magnets (20) is reduced, thereby reducing the manufacturing cost, and ensuring the balance between the motor performance.

Description

A permanent magnet synchronous motor and its rotor Technical field

The present invention relates to the field of motor technology, and in particular to a permanent magnet synchronous motor and its rotor. The IPC classification belongs to H02K1/27.

Background technique

For permanent magnet synchronous motors, the design of the rotor structure directly determines the motor's no-load electromotive force, electromagnetic torque and other properties. Among them, the selection of the polar arc coefficient of the permanent magnet is crucial. The polar arc parameter is the ratio of the permanent magnet's polar arc angle to the pole pitch at one pole pitch. In conventional design, the polar arc coefficient is generally less than 1. There have been many studies in this field on the impact of the polar arc coefficient on motors within this range. For specific relevant knowledge, please refer to the article "Electrical Technology" included in the 11th issue of 2020. "Permanent Magnet Synchronous Motor Pole Arc Coefficient Selection", as well as textbooks or monographs such as "Permanent Magnet Motor" published by China Electric Power Press in 2011, and "Modern Permanent Magnet Synchronous Motor Theory and Design" published by Mechanical Industry Press in 2015.

Contents of the invention

The purpose of the present invention is to provide a permanent magnet synchronous motor and its rotor. By changing the structure of the permanent magnet, the polar arc coefficient can be selected beyond the conventional range. While ensuring that the output torque of the motor meets the demand, the damage of the permanent magnet can be reduced as much as possible. dosage, reducing the manufacturing cost of the motor.

In a first aspect, the present invention provides a permanent magnet synchronous motor rotor, which includes a rotor core and a plurality of permanent magnets. The outer circumferential surface of the rotor core is alternately formed with grooves and protrusions, and the grooves are arranged at equal angles. They are arranged at intervals and penetrate the rotor core in a direction parallel to the axis of the rotor core; the permanent magnets are fixedly installed in the grooves, and the permanent magnets and protrusions form a circumference on the outer circumferential surface of the rotor core. Towards the alternately distributed first magnetic poles and second magnetic poles with opposite polarities, the polar arc coefficient of the permanent magnet is set to be greater than 1.

Preferably, the polar arc coefficient of the permanent magnet is set to 1.07 to 1.46. More preferably, the polar arc coefficient of the permanent magnet is set to 1.24.

Preferably, the permanent magnet is circumferentially centrally arranged in the groove, and there is a gap on both sides of the permanent magnet and the groove. The gap is preferably set to an arc length angle of 2°.

Preferably, the permanent magnet includes an inner peripheral side surface 1 and an outer peripheral side surface that are opposite in the radial direction. The inner peripheral side surface and the outer peripheral side surface are arcuate surfaces. The inner peripheral side surface is in contact with the radial surface of the groove. Together, the outer peripheral side surface and the radial surface of the protrusion are on the same cylindrical surface.

Preferably, the polar arc angle of the first magnetic pole formed by the permanent magnet is greater than the polar arc angle of the second magnetic pole formed by the protrusion. Wherein, the arc angle of the second magnetic pole is preferably 0.26 to 0.77 times the arc angle of the first magnetic pole.

In a second aspect, the present invention also provides a permanent magnet synchronous motor, including a stator and the above-mentioned motor rotor.

The invention has the following beneficial effects:

First, the rotor core itself is used to form a second magnetic pole with the opposite polarity to the permanent magnet, so that the polar arc coefficient of the permanent magnet can be set beyond the conventional range, increasing the motor output torque and improving motor performance.

Second, rationally adjust the proportional relationship between the polar arc angles occupied by the first magnetic pole and the second magnetic pole, reduce the amount of permanent magnets when the motor output torque can meet the predetermined requirements, and achieve a balance between reducing manufacturing costs and ensuring motor performance. balance.

Third, the first magnetic pole and the second magnetic pole are circumferentially separated by the groove between the permanent magnet and the protrusion to reduce magnetic flux leakage.

Other features and advantages of the present invention will be described in the subsequent description, or some of the features and advantages can be inferred or determined without doubt from the description, or can be learned by implementing the technical contents of the present invention.

Description of the drawings

Figure 1 is a cross-sectional view of the rotor of the permanent magnet synchronous motor of the present invention;

Figure 2 is a schematic diagram of the magnetic lines of force of the permanent magnet synchronous motor rotor of the present invention;

Figure 3 is a data line diagram shown in Table 1 of the specification of the present invention;

Figure 4 is a schematic diagram of the magnetic lines of force of the permanent magnet synchronous motor rotor in the prior art;

Figure 5 is a data line diagram shown in Table 2 of the specification of the present invention;

Figure 6 is a data line diagram shown in Table 2 of the specification of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments. Obviously, the described embodiments are examples of the present invention. Some examples, not all examples.

The permanent magnet synchronous motor and its rotor provided by the present invention can be applied to various types of motors that need to drive water pumps, especially the application scenarios of permanent magnet synchronous motors (PMSM). In order to facilitate understanding of the present invention, a rotor disclosed in the embodiment of the present invention is first introduced in detail.

As shown in Figure 1, an embodiment of the present invention provides a permanent magnet synchronous motor rotor, including a rotor core 10 and several permanent magnets 20, wherein:

The rotor core 10 is an integrated piece formed by stacking a plurality of annular silicon steel stamping sheets. To simplify the description, the “radial direction”, “axial direction” and “circumferential direction” in this specification are all represented by the rotor iron core. Core 10 is the reference. Grooves 11 and protrusions 12 are formed alternately on the outer circumferential surface of the rotor core 10 . Each groove 11 is arranged at equal angular intervals and penetrates the rotor core 10 in a direction parallel to the axis of the rotor core 10 for placing the permanent magnet 20 .

The permanent magnet 20 is made of rare earth magnetic steel such as neodymium iron boron, has a tile shape, and is fixedly installed in the groove 11 by glue or screws. The permanent magnet 20 includes an inner peripheral side surface 21 and an outer peripheral side surface 22 that are opposite in the radial direction, and two circumferential side surfaces 23 and 24 that are opposite in the circumferential direction. The inner peripheral surface 21 and the outer peripheral surface 22 are arc-shaped. The inner peripheral surface 21 is in contact with the radial surface 111 of the groove 11 . The outer peripheral surface 22 is in contact with the radial surface of the protrusion 12 . The facing surface 121 is on the same cylindrical surface.

The permanent magnet 20 is magnetized in the radial direction, and its inner peripheral side portion and outer peripheral side portion have different polarities. In this embodiment, as shown in FIG. 2 , all permanent magnets 20 are arranged in the groove 11 in such a manner that their outer circumferential side portions are S poles and their inner circumferential side portions are N poles, forming a first magnetic pole with S pole polarity. The external magnetic field lines of the permanent magnet 20 start from its N pole, pass through the protrusion 12 to the outside of the rotor core 10 , and finally return to the S pole of the permanent magnet 20 . In this case, the protrusions 12 converge the magnetic lines of force of two adjacent permanent magnets 20 , thus forming a second magnetic pole with N pole polarity on the protrusions 12 of the rotor core 10 . In the same way, the permanent magnet 20 can also be arranged in such a manner that its outer circumferential side is an N pole and its inner circumferential side is an S pole according to different magnetization directions. In this case, the protrusions 12 of the rotor core 10 form an S pole. The second magnetic pole of polarity.

Let the number of permanent magnets 20, that is, the first magnetic poles be p, and the pole arc angle be φ1, then the rotor in this embodiment has 2p magnetic poles, the number of pole pairs is p, the pole pitch is 180°/p, and the pole arc coefficient α=φ1/ (180°/p).

Taking the inventor's permanent magnet synchronous motor with 12 slots and 8 poles, rated voltage 12V, and rated output power 400W as an example, only the pole arc coefficient α is changed, and the motor output torque is measured without changing other parameters. Set The motor output torque reaches 690±6%mNm to be qualified. The experimental results are shown in Table 1 below:

Polar arc coefficient	Motor output torque (mNm)	Evaluation Results
0.78	492.7	Unqualified
0.80	506.7	Unqualified
0.82	520.5	Unqualified
0.84	534.7	Unqualified
0.87	547.9	Unqualified
0.89	560.5	Unqualified

0.91	574.2	Unqualified
0.93	585.6	Unqualified
0.96	596.6	Unqualified
0.98	609.0	Unqualified
1.00	618.9	Unqualified
1.02	628.4	Unqualified
1.04	638.4	Unqualified
1.07	647.5	qualified
1.09	654.5	qualified
1.11	663.8	qualified
1.13	669.3	qualified
1.16	674.0	qualified
1.18	679.8	qualified
1.20	683.5	qualified
1.22	685.5	qualified
1.24	689.8	qualified
1.27	689.5	qualified
1.29	688.1	qualified
1.31	688.7	qualified
1.33	685.5	qualified
1.36	681.2	qualified
1.38	677.5	qualified
1.40	672.8	qualified
1.42	664.3	qualified
1.44	658.6	qualified
1.47	648.7	qualified
1.49	637.4	Unqualified
1.51	626.6	Unqualified
1.53	612.9	Unqualified
1.56	597.5	Unqualified
1.58	582.6	Unqualified
1.60	562.1	Unqualified
1.62	538.3	Unqualified
1.64	513.7	Unqualified
1.67	485.4	Unqualified
1.69	455.9	Unqualified
1.71	426.8	Unqualified
1.73	395.6	Unqualified
1.76	363.8	Unqualified
1.78	331.2	Unqualified
1.80	295.8	Unqualified
1.82	260.4	Unqualified
1.84	225.2	Unqualified

1.87	188.5	Unqualified
1.89	149.9	Unqualified

The inventor found through experimental research, as shown in Figure 3, that if the polar arc coefficient is adjusted within the range of the existing polar arc coefficient α being less than 1, the larger the polar arc coefficient α is, the greater the motor output torque will be. As the polar arc coefficient α continues to increase within the range where the polar arc coefficient α is greater than 1, the motor output torque first increases, and after reaching a certain value, it decreases as the polar arc coefficient α increases. According to the above experimental results, the present invention can increase the polar arc coefficient α by setting larger grooves and correspondingly placing permanent magnets with larger arc length angles, so that the polar arc coefficient is greater than 1 and increases the motor output torque. On this basis, the preferred range of the polar arc coefficient α of the rotor of the present invention is also obtained: when the value of the polar arc coefficient α is within the range of α∈[1.07,1.46], the motor output torque can reach more than 690±6% mNm. , to meet the needs of the motor. Among them, when the polar arc coefficient α takes the value α=1.24, the motor output torque reaches the maximum value of 689.8mNm.

Compared with the traditional solution in which both magnetic poles are formed by permanent magnets 20 (as shown in Figure 4), in the present invention, the second magnetic pole is formed by the structure of the rotor core 10 itself instead of the permanent magnets 20. The amount of permanent magnets 20 is reduced, and a On the one hand, it reduces the manufacturing cost, but on the other hand, it also reduces the performance of the motor. In the preferred embodiment of the present invention, the ratio of the polar arc angles φ1 and φ2 of the first magnetic pole and the second magnetic pole is adjusted to determine the reduction rate obtained by the amount of permanent magnet 20 and the output torque of the motor compared to the traditional solution under the same conditions. , set the motor output torque reduction rate within 23% to be qualified. The experimental results are shown in Table 2 below:

φ2/φ1	Permanent magnet dosage reduction rate	Torque reduction rate	Evaluation Results
1.52	57%	41%	Unqualified
1.44	56%	40%	Unqualified
1.36	55%	38%	Unqualified
1.29	54%	36%	Unqualified
1.23	52%	35%	Unqualified
1.17	51%	33%	Unqualified
1.11	50%	32%	Unqualified
1.05	49%	30%	Unqualified
1.00	48%	29%	Unqualified
0.95	46%	27%	Unqualified
0.90	45%	26%	Unqualified
0.86	44%	25%	Unqualified
0.81	43%	twenty four%	Unqualified
0.77	41%	twenty three%	qualified
0.73	40%	twenty two%	qualified
0.70	39%	twenty one%	qualified
0.66	38%	20%	qualified
0.63	37%	20%	qualified
0.59	35%	19%	qualified
0.56	34%	19%	qualified
0.53	33%	18%	qualified
0.50	32%	18%	qualified
0.47	30%	18%	qualified
0.44	29%	18%	qualified
0.42	28%	18%	qualified

0.39	27%	18%	qualified
0.37	26%	19%	qualified
0.34	twenty four%	19%	qualified
0.32	twenty three%	20%	qualified
0.30	twenty two%	twenty one%	qualified
0.28	twenty one%	twenty two%	qualified
0.26	20%	twenty three%	qualified
0.24	18%	twenty four%	Unqualified
0.22	17%	25%	Unqualified
0.20	16%	27%	Unqualified
0.18	15%	29%	Unqualified
0.16	13%	31%	Unqualified
0.15	12%	33%	Unqualified
0.13	11%	36%	Unqualified
0.11	10%	39%	Unqualified
0.10	9%	42%	Unqualified
0.08	7%	46%	Unqualified
0.07	6%	49%	Unqualified
0.05	5%	53%	Unqualified
0.04	4%	57%	Unqualified
0.03	2%	61%	Unqualified
0.01	1%	65%	Unqualified

The inventor found through experimental research that the polar arc angles φ1 and φ2 of the first magnetic pole and the second magnetic pole have the following preferred relationship, as shown in Figure 1. The polar arc angle φ1 of the first magnetic pole formed by the permanent magnet 20 is greater than the convex angle. The polar arc angle φ2 of the second magnetic pole formed from 12, where the second magnetic pole arc angle φ2 is preferably 0.26 to 0.77 times the first magnetic pole arc angle φ1 as shown in Figure 5 and Figure 6, which is reduced by 20% to 41%. The amount of permanent magnets is 20, and the motor output torque can meet the predetermined requirements, achieving a balance between reducing manufacturing costs and ensuring motor performance.

The present invention has a preferred design for the structural relationship between the permanent magnet 20 and the groove 11 as shown in Figure 1. The permanent magnet 20 is circumferentially centered in the groove 11, and the circumferential side surfaces 23, 24 of the permanent magnet 20 are in contact with the groove 11. There is a gap Δφ between the circumferential side surfaces 112 and 113 of the groove 11. The gap Δφ separates the adjacent first magnetic pole and the second magnetic pole in the circumferential direction to reduce magnetic flux leakage. In this embodiment, the gap Δφ is preferably Set to an arc length angle of 2°.

The invention also provides a permanent magnet synchronous motor, which includes a stator and the above-mentioned rotor.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above-mentioned embodiments are illustrative and should not be construed as limitations of the present invention. Those of ordinary skill in the art can make various modifications within the scope of the present invention. The above-described embodiments are subject to changes, modifications, substitutions and variations.

Claims (9)

1. A permanent magnet synchronous motor rotor includes a rotor core (10) and several permanent magnets (20). The outer circumferential surface of the rotor core (10) is alternately formed with grooves (11) and protrusions (12). The grooves (11) are arranged at equal angular intervals and penetrate the rotor core (10) in a direction parallel to the axis of the rotor core (10); the permanent magnets are fixedly installed in the grooves (11). (20), the permanent magnet (20) and the protrusion (12) form first magnetic poles and second magnetic poles of opposite polarity distributed alternately in the circumferential direction on the outer peripheral surface of the rotor core (10). The polar arc coefficient of the magnet (20) is set to be greater than 1.
2. The permanent magnet synchronous motor rotor according to claim 1, characterized in that the polar arc coefficient of the permanent magnet (20) is set to 1.07 to 1.46.
3. The permanent magnet synchronous motor rotor according to claim 2, characterized in that the polar arc coefficient of the permanent magnet (20) is set to 1.24.
4. The permanent magnet synchronous motor rotor according to claim 1, characterized in that the permanent magnet (20) is circumferentially centrally arranged in the groove (11), and the permanent magnet (20) and the groove (11) ) has a gap on each side.
5. The permanent magnet synchronous motor rotor according to claim 4, wherein the gap is set to an arc length angle of 2°;
6. The permanent magnet synchronous motor rotor according to claim 1, characterized in that the permanent magnet (20) includes an inner peripheral side surface (21) and an outer peripheral side surface (22) that are opposite in the radial direction, and the inner peripheral side surface The surface (21) and the outer peripheral side surface (22) are arc-shaped, the inner peripheral side surface (21) is in contact with the radial surface (111) of the groove (11), and the outer peripheral side surface (22) is in contact with the radial surface (111) of the groove (11). The radial surface (121) of the protrusion (12) is on the same cylindrical surface.
7. The permanent magnet synchronous motor rotor according to claim 1, characterized in that the polar arc angle of the first magnetic pole formed by the permanent magnet (20) is greater than the polar arc angle of the second magnetic pole formed by the protrusion (12). .
8. The permanent magnet synchronous motor rotor according to claim 7, wherein the second magnetic pole arc angle is 0.26 to 0.77 times the first magnetic pole arc angle.
9. A permanent magnet synchronous motor includes a stator and the permanent magnet synchronous motor rotor according to any one of claims 1 to 8.

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