CN117546396A

CN117546396A - Permanent magnet synchronous motor and rotor thereof

Info

Publication number: CN117546396A
Application number: CN202280005600.XA
Authority: CN
Inventors: 冯奕冠; 彭城坚; 欧耀辉; 邹志
Original assignee: Hanyu Group JSCL
Current assignee: Hanyu Group JSCL
Priority date: 2022-06-07
Filing date: 2022-06-07
Publication date: 2024-02-09
Also published as: WO2023236032A1

Abstract

The invention provides a permanent magnet synchronous motor and a rotor thereof, wherein the rotor comprises a rotor core (10) and a plurality of permanent magnets (20), grooves (11) and protrusions (12) are alternately formed on the peripheral surface of the rotor core (10), and the grooves (11) are arranged at equal angular intervals and penetrate through the rotor core (10) along the direction parallel to the axis of the rotor core (10); permanent magnets (20) are fixedly arranged in the grooves (11), first magnetic poles and second magnetic poles which are circumferentially and alternately distributed and have opposite polarities are formed on the outer peripheral surface of the rotor core (10) by the permanent magnets (20) and the protrusions (12), and the polar arc coefficient of the permanent magnets (20) is set to be larger than 1. The rotor core (10) is utilized to form a magnetic pole with the polarity opposite to that of the permanent magnet (20), so that the pole arc coefficient of the permanent magnet (20) can be set beyond the conventional range, the output torque of the motor is increased, and the motor performance is improved. In addition, the proportion relation of the pole arc angles occupied by the two magnetic poles is reasonably adjusted, the consumption of the permanent magnet (20) is reduced under the condition that the output torque of the motor can meet the preset requirement, and the balance between the reduction of the manufacturing cost and the guarantee of the motor performance is realized.

Description

Permanent magnet synchronous motor and rotor thereof

Technical Field

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

Background

For a permanent magnet synchronous motor, the design of a rotor structure directly determines the performances of no-load electromotive force, electromagnetic torque and the like of the motor, wherein the selection of the pole arc coefficient of a permanent magnet is important. The polar arc parameter is the ratio of the polar arc angle of the permanent magnet to the polar distance under one polar distance. In conventional designs, the polar arc coefficient is generally less than 1, and in the field, there have been many researches on the influence of the polar arc coefficient on the motor, and specific related knowledge can be seen in textbooks or monographs such as "permanent magnet motor" published in 2011 of the electric publishing company of China, and "modern permanent magnet synchronous motor theory and design" published in 2015 of the mechanical industry publishing company, etc., in the article "permanent magnet synchronous motor polar arc coefficient selection" recorded in the period of 2020 of journal "electric technology".

Disclosure of Invention

The invention aims to provide a permanent magnet synchronous motor and a rotor thereof, wherein the pole arc coefficient is selected beyond the conventional range by changing the structure of a permanent magnet, so that the consumption of the permanent magnet is reduced as much as possible while the output torque of the motor meets the requirement, and the manufacturing cost of the motor is reduced.

The invention provides a permanent magnet synchronous motor rotor, which comprises a rotor core and a plurality of permanent magnets, wherein grooves and protrusions are alternately formed on the peripheral surface of the rotor core, the grooves are arranged at equal angular intervals and penetrate through the rotor core along the direction parallel to the axis of the rotor core; the permanent magnets are fixedly arranged in the grooves, the permanent magnets and the protrusions form first magnetic poles and second magnetic poles which are circumferentially and alternately distributed and have opposite polarities on the outer peripheral surface of the rotor core, and the polar arc coefficient of the permanent magnets is set to be larger than 1.

Preferably, the pole 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 disposed in the groove, and a gap is formed between the permanent magnet and each of the two sides of the groove. The gap is preferably set to an arc length angle of 2 °.

Preferably, the permanent magnet includes radially opposed inner and outer peripheral side surfaces 1, 1 which are arcuate, which conform to the radial surfaces of the grooves, and which are on the same cylindrical surface as the raised radial surfaces.

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

In a second aspect, the invention also provides a permanent magnet synchronous motor, which comprises a stator and the motor rotor.

The invention has the following beneficial effects:

firstly, the rotor core itself is utilized to form a second magnetic pole with the polarity opposite to that of the permanent magnet, so that the pole arc coefficient of the permanent magnet can be set beyond the conventional range, the output torque of the motor is increased, and the motor performance is improved.

And secondly, the proportion relation of the pole arc angles occupied by the first magnetic pole and the second magnetic pole is reasonably adjusted, the permanent magnet consumption is reduced under the condition that the motor output torque can reach the preset requirement, and the balance between the manufacturing cost reduction and the motor performance guarantee is realized.

Third, the first magnetic pole and the second magnetic pole are separated in the circumferential direction by a groove between the permanent magnet and the protrusion to reduce magnetic leakage.

Additional features and advantages of the invention will be set forth in the description which follows, or in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

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

FIG. 2 is a schematic diagram of the magnetic lines of force of a rotor of a permanent magnet synchronous motor according to the present invention;

FIG. 3 is a data diagram of Table 1 of the present specification;

fig. 4 is a schematic diagram of magnetic lines of force of a rotor of a permanent magnet synchronous motor according to the prior art;

FIG. 5 is a data diagram of Table 2 of the present specification;

fig. 6 is a data line diagram of table 2 of the present invention.

Detailed Description

In order to make the present invention better understood by those skilled in the art, the following description of the present invention will be made in detail, but not necessarily with reference to the accompanying drawings.

The permanent magnet synchronous motor and the rotor thereof provided by the invention can be applied to various motors which need to drive a water pump, in particular to the application scene of a Permanent Magnet Synchronous Motor (PMSM). For the convenience of understanding the present invention, a rotor disclosed in an embodiment of the present invention will be described in detail.

As shown in fig. 1, a permanent magnet synchronous motor rotor provided by an embodiment of the present invention includes a rotor core 10 and a plurality of permanent magnets 20, wherein:

the rotor core 10 is an integral piece formed by laminating a plurality of annular silicon steel stamping sheets, and for simplicity of description, the rotor core 10 is used as a reference in the description of the radial direction, the axial direction and the circumferential direction. The rotor core 10 has grooves 11 and protrusions 12 alternately formed on the outer circumferential surface thereof. The grooves 11 are provided at equal angular intervals, penetrate the rotor core 10 in a direction parallel to the axis of the rotor core 10, for disposing the permanent magnets 20.

The permanent magnet 20 is made of rare earth magnetic steel such as neodymium iron boron, is tile-shaped, and is fixedly arranged in the groove 11 through adhesive or screws. The permanent magnet 20 includes an inner peripheral side surface 21 and an outer peripheral side surface 22 that are opposed in the radial direction, and two peripheral side surfaces 23, 24 that are opposed in the circumferential direction. The inner peripheral side surface 21 and the outer peripheral side surface 22 are arc surfaces, the inner peripheral side surface 21 is attached to the radial surface 111 of the groove 11, and the outer peripheral side surface 22 is on the same cylindrical surface as the radial surface 121 of the projection 12.

The permanent magnet 20 is magnetized in the radial direction, and has different polarities at the inner peripheral side portion and the outer peripheral side portion. In the present embodiment, as shown in fig. 2, all the permanent magnets 20 are arranged in the grooves 11 with the outer peripheral side portions thereof being S-poles and the inner peripheral side portions being N-poles, forming first magnetic poles in the polarity of S-poles. The external magnetic force line of the permanent magnet 20 starts from the N pole of the permanent magnet, passes through the bulge 12 to the outside of the rotor core 10, and finally returns to the S pole of the permanent magnet 20. In this case, the protrusions 12 converge magnetic lines of force of the adjacent two permanent magnets 20, and thus a second magnetic pole having an N-pole polarity is formed at the protrusions 12 of the rotor core 10. Similarly, the permanent magnets 20 may be arranged such that the outer circumferential side thereof is N-pole and the inner circumferential side is S-pole, depending on the magnetization directions, and in this case, the protrusions 12 of the rotor core 10 form second magnetic poles having S-pole polarity.

Let the number of permanent magnets 20, i.e. the first magnetic poles, be p and the pole arc angle be φ 1, the rotor of this embodiment has 2p magnetic poles, the pole pair number be p, the pole pitch be 180 °/p, the pole arc coefficient α=φ1/(180 °/p).

Taking a permanent magnet synchronous motor with 12 slots and 8 poles, 12V rated voltage and 400W rated output power as an example, the inventor only changes the polar arc coefficient alpha, and determines the motor output torque under the condition of not changing other parameters, and the motor output torque is set to 690+/-6% mNm to be qualified, and the experimental results are shown in the following table 1:

polar arc coefficient	Motor output torque (mNm)	Assessment results
0.78	492.7	Failure to pass
0.80	506.7	Failure to pass
0.82	520.5	Failure to pass
0.84	534.7	Failure to pass
0.87	547.9	Failure to pass
0.89	560.5	Failure to pass

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

1.87	188.5	Failure to pass
1.89	149.9	Failure to pass

The inventor experiment researches show that as shown in fig. 3, the polar arc coefficient is adjusted within the range that the existing polar arc coefficient alpha is smaller than 1, and the larger the polar arc coefficient alpha is, the larger the motor output torque is. The polar arc coefficient alpha is continuously increased within the range that the polar arc coefficient alpha is larger than 1, the output torque of the motor is increased firstly, and the output torque is reduced along with the increase of the polar arc coefficient alpha after the output torque reaches a certain value. According to the experimental result, the invention can increase the polar arc coefficient alpha by arranging the larger groove and correspondingly placing the permanent magnet with larger arc length angle, so that the polar arc coefficient is larger than 1, and the output torque of the motor is increased. On this basis, the preferred range of the polar arc coefficient alpha of the rotor of the invention is also obtained: when the value of the polar arc coefficient alpha is within the range of alpha epsilon 1.07,1.46, the output torque of the motor can reach more than 690+/-6% mNm, thereby meeting the use requirement of the motor. Wherein, when the polar arc coefficient alpha takes the value of alpha=1.24, the motor output torque reaches the maximum value 689.8mNm.

Compared with the conventional scheme (as shown in fig. 4) that both poles are formed by the permanent magnets 20, the second pole is formed by the structure of the rotor core 10 itself instead of the permanent magnets 20, and the amount of the permanent magnets 20 is reduced, which reduces the manufacturing cost on the one hand and the performance of the motor on the other hand. According to the preferred embodiment of the invention, the reduction rate obtained by adjusting the ratio of the pole arc angles phi 1 and phi 2 of the first magnetic pole and the second magnetic pole relative to the consumption of the permanent magnet 20 and the motor output torque of the traditional scheme under the same condition is measured, the motor output torque reduction rate is set to be within 23 percent, and the experimental result is shown in the following table 2:

φ2/φ1	rate of permanent magnet usage reduction	Torque reduction rate	Assessment results
1.52	57％	41％	Failure to pass
1.44	56％	40％	Failure to pass
1.36	55％	38％	Failure to pass
1.29	54％	36％	Failure to pass
1.23	52％	35％	Failure to pass
1.17	51％	33％	Failure to pass
1.11	50％	32％	Failure to pass
1.05	49％	30％	Failure to pass
1.00	48％	29％	Failure to pass
0.95	46％	27％	Failure to pass
0.90	45％	26％	Failure to pass
0.86	44％	25％	Failure to pass
0.81	43％	24％	Failure to pass
0.77	41％	23％	Qualified product
0.73	40％	22％	Qualified product
0.70	39％	21％	Qualified product
0.66	38％	20％	Qualified product
0.63	37％	20％	Qualified product
0.59	35％	19％	Qualified product
0.56	34％	19％	Qualified product
0.53	33％	18％	Qualified product
0.50	32％	18％	Qualified product
0.47	30％	18％	Qualified product
0.44	29％	18％	Qualified product
0.42	28％	18％	Qualified product

0.39	27％	18％	Qualified product
0.37	26％	19％	Qualified product
0.34	24％	19％	Qualified product
0.32	23％	20％	Qualified product
0.30	22％	21％	Qualified product
0.28	21％	22％	Qualified product
0.26	20％	23％	Qualified product
0.24	18％	24％	Failure to pass
0.22	17％	25％	Failure to pass
0.20	16％	27％	Failure to pass
0.18	15％	29％	Failure to pass
0.16	13％	31％	Failure to pass
0.15	12％	33％	Failure to pass
0.13	11％	36％	Failure to pass
0.11	10％	39％	Failure to pass
0.10	9％	42％	Failure to pass
0.08	7％	46％	Failure to pass
0.07	6％	49％	Failure to pass
0.05	5％	53％	Failure to pass
0.04	4％	57％	Failure to pass
0.03	2％	61％	Failure to pass
0.01	1％	65％	Failure to pass

The inventor experiment researches show that the pole arc angles phi 1 and phi 2 of the first magnetic pole and the second magnetic pole have the following preferable relation, as shown in figure 1, the pole arc angle phi 1 of the first magnetic pole formed by the permanent magnet 20 is larger than the pole arc angle phi 2 of the second magnetic pole formed by the bulge 12, wherein the pole arc angle phi 2 of the second magnetic pole is preferably 0.26-0.77 times of the pole arc angle phi 1 of the first magnetic pole as shown in figures 5 and 6, the dosage of the permanent magnet 20 is reduced by 20-41%, the output torque of the motor can reach the preset requirement, and the balance between the reduction of the manufacturing cost and the guarantee of the motor performance is realized.

The structural relationship between the permanent magnet 20 and the groove 11 according to the present invention is preferably designed such that, as shown in fig. 1, the permanent magnet 20 is disposed in the groove 11 at a periphery Xiang Juzhong, and a gap ΔΦ is provided between the circumferential sides 23, 24 of the permanent magnet 20 and the circumferential sides 112, 113 of the groove 11, wherein the gap ΔΦ is configured such that adjacent first and second magnetic poles are circumferentially spaced apart to reduce magnetic leakage, and the gap ΔΦ is preferably set to an arc length angle of 2 ° in this embodiment.

The invention also provides a permanent magnet synchronous motor which comprises a stator and the rotor.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

The permanent magnet synchronous motor rotor comprises a rotor core (10) and a plurality of permanent magnets (20), wherein grooves (11) and protrusions (12) are alternately formed on the outer peripheral surface of the rotor core (10), and the grooves (11) are arranged at equal angular intervals and penetrate through the rotor core (10) along the direction parallel to the axis of the rotor core (10); the permanent magnets (20) are fixedly arranged in the grooves (11), first magnetic poles and second magnetic poles which are circumferentially and alternately distributed and have opposite polarities are formed on the outer peripheral surface of the rotor core (10) by the permanent magnets (20) and the protrusions (12), and the pole arc coefficient of the permanent magnets (20) is set to be larger than 1.
The permanent magnet synchronous motor rotor according to claim 1, characterized in that the pole arc coefficient of the permanent magnets (20) is set to 1.07 to 1.46.
The permanent magnet synchronous motor rotor according to claim 2, characterized in that the pole arc coefficient of the permanent magnets (20) is set to 1.24.
The rotor of a permanent magnet synchronous motor according to claim 1, wherein the permanent magnet (20) is centrally arranged in the groove (11) in the circumferential direction, and a gap is provided between the permanent magnet (20) and both sides of the groove (11).
The permanent magnet synchronous motor rotor according to claim 4, wherein the gap is set at an arc length angle of 2 °;
permanent magnet synchronous motor rotor according to claim 1, characterized in that the permanent magnet (20) comprises an inner peripheral side surface (21) and an outer peripheral side surface (22) which are opposite in radial direction, the inner peripheral side surface (21) and the outer peripheral side surface (22) being arc-shaped, the inner peripheral side surface (21) being in abutment with a radial surface (111) of the groove (11), the outer peripheral side surface (22) being on the same cylindrical surface as a radial surface (121) of the protrusion (12).
Permanent magnet synchronous motor rotor according to claim 1, characterized in that the permanent magnets (20) form a first pole with a pole arc angle that is larger than the pole arc angle of the second pole formed by the projections (12).
The permanent magnet synchronous motor rotor according to claim 7, wherein the second pole arc angle is 0.26 to 0.77 times the first pole arc angle.
A permanent magnet synchronous motor comprising a stator and a permanent magnet synchronous motor rotor according to any one of claims 1 to 8.