CN113178968A - Skewed pole permanent magnet motor rotor and design method thereof - Google Patents

Abstract

The invention discloses a skewed pole permanent magnet motor rotor and a design method thereof. Firstly, determining the total oblique pole angle of an oblique pole permanent magnet motor rotor provided with N sections of rotor cores with equal length in the original scheme; determining the motor torque and torque ripple values of the original scheme by using finite element simulation software; the total oblique pole angle of the new oblique pole permanent magnet motor rotor is kept unchanged, and the optimization of the angle separation of the magnetic pole center lines of the adjacent rotor core sections is carried out by combining the bisection method with finite element simulation software.

Description

Skewed pole permanent magnet motor rotor and design method thereof

Technical Field

The invention relates to the field of permanent magnet motors, in particular to a skewed pole permanent magnet motor rotor and a design method thereof.

Background

The torque fluctuation is an important index influencing the performance of the permanent magnet motor, the torque fluctuation can cause motor shake, electromagnetic vibration and noise are generated, the control precision is influenced, and the performance is reduced and even the control is invalid when the fluctuation is serious.

In the existing new energy permanent magnet motor, a rotor skewed pole mode is mostly adopted for reducing torque fluctuation, a motor rotor is axially divided into a plurality of sections, the center line of each section of magnetic pole has a certain angle difference in the circumferential direction, and the total skewed pole angle = tooth pitch angle x (number of sections-1)/number of sections.

However, the permanent magnet materials of the segmented skewed pole rotor adopted by the existing permanent magnet motor need to be uniform in size and specification, a single product uses a permanent magnet with a single specification, and the permanent magnet materials of different motors with the same punching sheet structure cannot be universal.

Disclosure of Invention

The invention aims to: the utility model provides a rotor of oblique utmost point permanent-magnet machine can use different length rotor cores to make up to utilize the algorithm to optimize the motor oblique utmost point angle, promote motor stability and vibration noise through reducing motor torque ripple.

The technical scheme of the invention is as follows:

a rotor of an oblique pole permanent magnet motor comprises a motor rotating shaft and a plurality of sections of rotor cores which are sleeved on the motor rotating shaft and arranged in an oblique pole mode, the lengths of the rotor cores in adjacent sections are different, and permanent magnets which are as long as the rotor core in the adjacent section are assembled on each section of the rotor core.

Preferably, the lengths of the rotor core sections are gradually lengthened from two ends to the middle of the motor rotating shaft.

Preferably, in each section of the rotor core, the left and right sections of the rotor core, which are the same in position from the center of the motor rotating shaft, are equal in length.

Preferably, the lengths of the rotor core segments are lengthened in equal proportion or equal difference from two ends to the middle of the motor rotating shaft.

Preferably, each section of the rotor core is composed of a plurality of rotor punching sheets with 8 poles and 48 slots and the same size.

A method for designing a rotor of a skewed pole permanent magnet motor comprises the following steps:

s1, firstly, determining the rotor of the skewed pole permanent magnet motor in the original scheme:

n sections of rotor cores with equal length are configured on a rotor of a skewed pole permanent magnet motor in the original scheme, the number of winding slots on the rotor cores is M, the total skewed pole angle alpha of the original rotor is = (360 degrees/M) × (N-1)/N, and the center line of the magnetic pole of two adjacent sections of rotor cores is separated by an angle beta = (360 degrees/M)/N;

s2, performing motor parameter simulation on the skewed pole permanent magnet motor rotor in the original scheme by using finite element simulation software, and determining a motor torque T and a torque ripple value S in the original scheme;

s3, designing a new skewed pole permanent magnet motor rotor:

the new skewed pole permanent magnet motor rotor is provided with N ' sections of rotor cores as claimed in any one of claims 1 to 5, the number of winding slots on the rotor cores is still M, and the new rotor total skewed pole angle α ' is the same as the original rotor total skewed pole angle α, namely α ' = α;

s4, optimizing the magnetic pole center line separation angle beta ' of each adjacent section of the rotor core by combining bisection method with finite element simulation software for the new skewed pole permanent magnet motor rotor, and monitoring new motor torque T ' and a torque ripple value S ' until the difference between the new motor torque T ' and the motor torque T in the original scheme is within +/-2%, wherein the new torque ripple value S ' is lower than the torque ripple value S in the original scheme.

The invention has the advantages that:

the rotor of the oblique pole permanent magnet motor can adopt permanent magnets with different specifications to design the motor, and the torque output capacity of the rotor is consistent with that of the permanent magnets with the same specification, and the torque pulsation of the motor is reduced by utilizing an algorithm, so that the stability of the motor is improved, and the vibration noise is reduced.

Drawings

The invention is further described with reference to the following figures and examples:

FIG. 1 is a schematic structural diagram of a rotor A of an oblique-pole permanent magnet motor in an embodiment;

FIG. 2 is a schematic diagram of a permanent magnet motor rotor sheet used in the embodiment;

FIG. 3 is a comparison of a skewed pole permanent magnet motor rotor A, B according to an embodiment;

FIG. 4 is a diagram illustrating a comparison of permanent magnet configurations respectively used for the skewed pole PMSM rotor A, B in an embodiment;

FIG. 5 is a schematic sectional view of a skewed pole of a rotor A of a skewed pole permanent magnet motor in an embodiment;

FIG. 6 is a simulation parameter diagram of a rotor A of an oblique-pole permanent magnet motor in an embodiment;

FIG. 7 is a schematic sectional view of a skewed pole of a rotor C of a skewed pole permanent magnet motor according to an embodiment;

fig. 8 is a simulation parameter diagram of the rotor C of the skewed pole permanent magnet motor in the embodiment.

Detailed Description

The structure of the rotor of the permanent magnet motor of the new energy automobile generally comprises a motor rotating shaft, a rotor iron core and a permanent magnet.

As shown in fig. 1 and 3, two types of skewed-pole permanent magnet motor rotors A, B with different lengths in the prior art are provided, each of the two types of skewed-pole permanent magnet motor rotors A, B includes a motor rotating shaft 1 and four sections of skewed-pole arranged rotor cores 2 sleeved on the motor rotating shaft 1, and the lengths of the rotor cores 2 in adjacent sections are the same. The length of the rotor A, B of the oblique-pole permanent magnet motor is 80mm and 160mm respectively, and the length of the single-section rotor core 2 on the rotor A, B of the oblique-pole permanent magnet motor is 20mm and 40mm respectively.

As shown in fig. 2, each segment of the rotor core 2 of the skewed-pole permanent magnet motor rotor A, B is formed by a plurality of rotor sheets 2-1 with 8 poles and 48 slots and the same size.

As shown in fig. 4, each section of the rotor core 2 of the skewed-pole permanent magnet motor rotor A, B is equipped with a first permanent magnet 3 and a second permanent magnet 3' that are as long as the rotor core 2, that is, the lengths of the two types of permanent magnets are 20mm and 40mm, respectively.

The embodiment provides a new skewed pole permanent magnet motor rotor C on the basis of the two kinds of skewed pole permanent magnet motor rotors, and the specific design steps are as follows:

s1, as shown in fig. 5, since the number of segments N =4 of the permanent magnet motor rotor a, the total rotor pole pitch angle α = (360 °/48) × (N-1)/N =5.625 °, and the center line of two adjacent magnetic poles is separated by an angle β = (360 °/48)/N =1.875 ° with the motor rotation shaft as the center.

S2, as shown in fig. 6, using common finite element simulation software, firstly performing motor parameter simulation on the permanent magnet motor rotor a, and determining the motor torque T and the torque ripple value S in the original scheme.

S3, as shown in fig. 7, a new skewed pole permanent magnet motor rotor C is constructed by selecting a rotor core and a permanent magnet of the skewed pole permanent magnet motor rotor A, B. The number of the segments of the rotor core of the rotor C of the oblique-pole permanent magnet motor is N =3, and the lengths of the three segments of the rotor core are 20mm, 40mm and 20mm respectively.

S4, as shown in fig. 8, keeping the new total oblique angle α 'of the rotor still at 5.625 °, optimizing the magnetic pole center line separation angle β' of each adjacent segment of the rotor core by a bisection method in combination with finite element simulation software, and monitoring the new motor torque T 'and the torque ripple value S' until the new motor torque T 'is within ± 2% of the motor torque T of the original scheme, and the new torque ripple value S' is lower than the torque ripple value S of the original scheme.

The magnetic pole center lines of the adjacent rotor core segments of the embodiment are separated by an angle beta' of-2.8125 degrees, 1 degree and 2.8125 degrees. As can be seen from the front and back simulation data, under the condition that the torque is reduced by 0.6%, the torque ripple is reduced by 7.8%, and the purpose of reducing the torque ripple and improving the motor performance is achieved by adopting the permanent magnet motor rotor C.

In addition to the above embodiments, motors with different specifications can be designed with oblique poles by referring to the same method, for example, the number of oblique pole segments can be increased. But is preferably designed according to the following principle to reduce the optimization difficulty.

(1) The length of each segment of the rotor core 2 is gradually increased from the two ends of the motor rotating shaft 1 to the middle.

(2) In each section of the rotor iron core 2, the left and right sections of the rotor iron core 2 which are the same as the center of the motor rotating shaft 1 are equal in length.

(3) The lengths of the rotor iron core 2 are lengthened in equal ratio or equal difference from the two ends of the motor rotating shaft 1 to the middle.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All modifications made according to the spirit of the main technical scheme of the invention are covered in the protection scope of the invention.

Claims (6)

1. The utility model provides a rotor of oblique utmost point permanent-magnet machine, its characterized in that includes motor shaft (1) and a plurality of sections cover rotor core (2) that the oblique utmost point arranged on motor shaft (1), and rotor core (2) length of adjacent section is different, is equipped with permanent magnet (3) isometric with rotor core (2) of place on every section rotor core (2).

2. The skewed pole permanent magnet machine rotor according to claim 1, wherein the length of each segment of the rotor core (2) is gradually longer from the two ends to the middle of the machine shaft (1).

3. The skewed pole permanent magnet motor rotor according to claim 2, wherein the lengths of the left and right rotor cores (2) at the same distance from the center of the motor shaft (1) in each section of the rotor cores (2) are equal.

4. A skewed pole permanent magnet machine rotor according to claim 3, wherein the length of each segment of the rotor core (2) is equal or different from the two ends to the middle of the machine shaft (1).

5. The skewed pole permanent magnet motor rotor according to claim 4, wherein each segment of the rotor core (2) is composed of a plurality of rotor sheets (2-1) with 8 poles and 48 slots and the same size.

6. A method for designing a rotor of a skewed pole permanent magnet motor is characterized by comprising the following steps:

s1, firstly, determining the rotor of the skewed pole permanent magnet motor in the original scheme:

n sections of rotor cores with equal length are configured on a rotor of a skewed pole permanent magnet motor in the original scheme, the number of winding slots on the rotor cores is M, the total skewed pole angle alpha of the original rotor is = (360 degrees/M) × (N-1)/N, and the center line of the magnetic pole of two adjacent sections of rotor cores is separated by an angle beta = (360 degrees/M)/N;

s2, performing motor parameter simulation on the skewed pole permanent magnet motor rotor in the original scheme by using finite element simulation software, and determining a motor torque T and a torque ripple value S in the original scheme;

s3, designing a new skewed pole permanent magnet motor rotor:

the new skewed pole permanent magnet motor rotor is provided with N ' sections of rotor cores as claimed in any one of claims 1 to 5, the number of winding slots on the rotor cores is still M, and the new rotor total skewed pole angle α ' is the same as the original rotor total skewed pole angle α, namely α ' = α;

s4, optimizing the magnetic pole center line separation angle beta ' of each adjacent section of the rotor core by combining bisection method with finite element simulation software for the new skewed pole permanent magnet motor rotor, and monitoring new motor torque T ' and a torque ripple value S ' until the difference between the new motor torque T ' and the motor torque T in the original scheme is within +/-2%, wherein the new torque ripple value S ' is lower than the torque ripple value S in the original scheme.

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