A permanent magnet synchronous motor

Abstract

A permanent magnet synchronous motor comprises a stator, a rotor and a rotating shaft, wherein the stator comprises a stator winding, a stator end face magnetic pole ring group k0, k1, k2...k n The rotor includes a rotor main permanent magnet, a rotor end face magnetic pole ring group k0, k1, k2...k n And rotor iron yoke, stator end face magnetic pole ring group k0, k1, k2...k n With the rotor end face magnetic pole ring group k0, k1, k2...k n The same group consists of k0, k1, k2...k n Group; thus, smooth torque output can be achieved, torque pulsation suppression effect is good, the structure is simple and easy to process, and high-precision control can be better achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet synchronous motors, and in particular to a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors have the advantages of compact structure, high power density, high air gap flux and high torque inertia ratio. They are widely used in high-precision AC servo, electric vehicle drive, wind power generation and other systems. Torque pulsation is an important indicator to measure motor performance. The smaller the torque pulsation of a motor, the smoother and more reliable it will run, thus greatly reducing the operating cost of the motor control system.

[0003] 1. Stator skew slot and rotor skew pole method

[0004] The use of skewed slots is one of the most widely used methods for suppressing torque pulsation. The stator slots are tilted by a stator tooth pitch relative to the rotor poles, so that the air gap flux density is a constant, eliminating the slot torque pulsation. Due to the existence of the end effect, the skewed slots cannot completely eliminate the slot torque generated by the magnetic field between the ends of the core. At the same time, it is difficult to ensure that the air gap flux density is a constant, so it is impossible to completely eliminate the slot torque pulsation. Due to the end effect, the skewed slots cannot actually completely eliminate the torque pulsation. The cost of using skewed slots or skewed poles is that the motor structure tends to be complex, the processing difficulty increases, and the output torque of the motor is reduced to a certain extent, especially for motors with fewer teeth per pole.

[0005] 2. Fractional slot method

[0006] The cogging torque is only related to the Yth harmonic component of B. When it is equal to 1, it is called the fundamental cogging torque. The number of cogging torque pulsation cycles corresponding to one rotation of the rotor is Y. The nth cogging torque pulsation is generated by the Yth harmonic, and the number of cogging torque pulsation cycles is Y. Compared with the permanent magnet synchronous motor with integer slot winding, the motor with fractional slot winding can choose more slot number combinations. Selecting the optimal combination of slot number z with a larger least common multiple and pole number 2 can reduce the cogging torque pulsation caused by the motor body. However, after using the fractional slot combination, the winding distribution under each pole number will be asymmetric, which will partially reduce the effective torque component of the motor, and the average torque output of the motor will also be reduced accordingly.

[0007] 3. Magnetic slot wedge method

[0008] The magnetic slot wedge method is to apply a layer of magnetic slot mud on the stator slot of the motor, and after solidification, a slot wedge with certain magnetic conductivity is formed. The magnetic slot wedge reduces the influence of the stator slot opening, making the air gap magnetic permeability distribution between the stator and the rotor more uniform, thereby reducing the torque pulsation caused by the cogging effect. Since the magnetic conductivity of the magnetic slot wedge material is not very good, the degree of reduction of torque pulsation is limited.

[0009] Many measures reduce the cogging torque, while the electromagnetic torque also decreases, but the electromagnetic torque pulsation increases accordingly. Therefore, the torque pulsation should be considered comprehensively, taking into account both the cogging torque pulsation and the electromagnetic torque pulsation. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a permanent magnet synchronous motor.

[0011] The technical solution adopted by the present invention to solve the technical problem is:

[0012] A permanent magnet synchronous motor comprises a stator, a rotor and a rotating shaft, wherein the stator comprises a stator winding, a stator end face magnetic pole ring group k0, k1, k2...k n The rotor includes a rotor main permanent magnet, a rotor end face magnetic pole ring group k0, k1, k2...k n And rotor iron yoke, stator end face magnetic pole ring group k0, k1, k2...k n With the rotor end face magnetic pole ring group k0, k1, k2...k n The same group consists of k0, k1, k2...k n Group; where the following relations are satisfied:

[0013] The functional relationship between the output torque of the permanent magnet synchronous motor and the rotor angle θ is as follows:

[0014]

[0015] Where, T PMSM Permanent magnet synchronous motor torque, T DC is the DC component of the torque, k is the harmonic order, A PMSMk is the kth harmonic amplitude of the permanent magnet synchronous motor torque, P PMSM Number of pole pairs of permanent magnet synchronous motor, φ PMSMk is the initial phase of the kth harmonic of the permanent magnet synchronous motor, θ is the rotor angle; ∞ is infinity;

[0016] The output torque of group i is offset from the center line of the magnetic pole of group i by an angle θ si The functional relationship is as follows:

[0017] T Wi =A Wi cos(P Wi θ si +φ Wi ) (2)

[0018] Where, T Wi is the output torque of group i, A Wi is the amplitude of group i, P Wiis the number of pole pairs of group i, φ Wi is the phase of group i, θ si is the offset angle of the magnetic pole center line of group i, group i is k0, k1, k2...k n One of the groups;

[0019] The pole-pair relationship is as follows:

[0020] P PMSM i=P Wi (3)

[0021] Where P PMSM Number of pole pairs of permanent magnet synchronous motor, P Wi is the number of pole pairs of group i, group i is k0, k1, k2…k n One of the groups.

[0022] In one embodiment, the stator end face magnetic pole ring groups k0, k1, k2...k n With the rotor end face magnetic pole ring group k0, k1, k2...k n As a group.

[0023] In one embodiment, the permanent magnet synchronous motor torque kth harmonic amplitude A PMSMk The relationship is as follows:

[0024] A PMSMk -A Wi →0 (4)

[0025] In the formula, A PMSMk is the kth harmonic amplitude of the permanent magnet synchronous motor torque, A Wi is the amplitude of group i.

[0026] In one embodiment, the initial phase φ of the kth harmonic of the permanent magnet synchronous motor is PMSMk The relationship is as follows:

[0027] φ PMSMk -π=φ Wi =θ si ·P Wi (5)

[0028] In the formula, φ PMSMk is the initial phase of the kth harmonic of the permanent magnet synchronous motor, θ si is the initial angle of group i, φ Wi is the phase of group i, P Wi is the number of pole pairs of group i.

[0029] In one embodiment, the stator end face magnetic pole ring groups k0, k1, k2...k n Both include a stator end face magnetic pole ring 1 and a stator end face magnetic pole ring 2.

[0030] In one embodiment, the rotor end face magnetic pole ring groups k0, k1, k2...k n Both include a rotor end surface magnetic pole ring 1 and a rotor end surface magnetic pole ring 2.

[0031] In one embodiment, the stator end face magnetic pole ring groups k0, k1, k2...k n With the rotor end face magnetic pole ring group k0, k1, k2...k n The inner diameters are equal.

[0032] In one embodiment, the stator end face magnetic pole ring groups k0, k1, k2...k n With the rotor end face magnetic pole ring group k0, k1, k2...k n The outer diameters are equal.

[0033] In one embodiment, the stator end face magnetic pole ring groups k0, k1, k2...k n With the rotor end face magnetic pole ring group k0, k1, k2...k n The number of pole pairs is the same.

[0034] In one embodiment, the rotor yoke, the rotor end face magnetic pole ring groups k0, k1, k2...k n , the rotor main permanent magnet and the rotating shaft are fixed as a whole.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention can achieve smooth output of torque, has good torque pulsation suppression effect, has a simple structure and is easy to process, and can better achieve high-precision control. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0038] Figure 2 It is a schematic diagram of the structure of the stator and rotor end face magnetic pole rings of the present invention;

[0039] Figure 3 This is a torque per unit value diagram after suppressing the fundamental wave of the present invention;

[0040] Figure 4 This is a per-unit torque diagram after the second and sixth harmonics of the fundamental wave are suppressed by the present invention.

[0041] In the figure: 10, rotating shaft, 20, stator winding, 21, stator end surface magnetic pole ring 1, 22, stator end surface magnetic pole ring 2, 25, stator end surface magnetic pole ring group, 30, rotor main permanent magnet, 31, rotor iron yoke, 32, rotor end surface magnetic pole ring 1, 33, rotor end surface magnetic pole ring 2, 35, rotor end surface magnetic pole ring group. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0043] Example 1

[0044] like Figure 1-4 As shown, this embodiment includes a stator, a rotor, and a rotating shaft 10. The stator includes a stator winding 20, a stator end face magnetic pole ring group 25k0, k1, k2...k n The rotor includes a rotor main permanent magnet 30, a rotor end face magnetic pole ring group 35k0, k1, k2...k n and rotor iron yoke 31, stator end face magnetic pole ring group 25k0, k1, k2...k n With the rotor end face magnetic pole ring group 35k0, k1, k2...k n The same group consists of k0, k1, k2...k n Group;

[0045] In this embodiment, the stator end face magnetic pole ring group 25k0, k1, k2...k n They all include a stator end face magnetic pole ring 1 21, a stator end face magnetic pole ring 22; a rotor end face magnetic pole ring group 35k0, k1, k2...k n Both include a rotor end surface magnetic pole ring 1 32 and a rotor end surface magnetic pole ring 2 33;

[0046] And satisfy the following relationship:

[0047] The functional relationship between the output torque of the permanent magnet synchronous motor and the rotor angle θ is as follows:

[0048]

[0049] Where, T PMSM Permanent magnet synchronous motor torque, T DC is the DC component of the torque, k is the harmonic order, A PMSMk is the kth harmonic amplitude of the permanent magnet synchronous motor torque, P PMSM Number of pole pairs of permanent magnet synchronous motor, φ PMSMk is the initial phase of the kth harmonic of the permanent magnet synchronous motor, θ is the rotor angle; ∞ is infinity;

[0050] The output torque of group i is offset from the center line of the magnetic pole of group i by an angle θ si The functional relationship is as follows:

[0051] T Wi =A Wi cos(P Wi θ si +φ Wi ) (2)

[0052] Where, T Wi is the output torque of group i, A Wi is the amplitude of group i, P Wi is the number of pole pairs of group i, φ Wi is the phase of group i, θ si is the offset angle of the magnetic pole center line of group i, group i is k0, k1, k2...k n One of the groups;

[0053] The pole-pair relationship is as follows:

[0054] P PMSM i=P Wi (3)

[0055] Where P PMSM Number of pole pairs of permanent magnet synchronous motor, P Wi is the number of pole pairs of group i, group i is k0, k1, k2…k n One of the groups;

[0056] The amplitude relationship is as follows:

[0057] A PMSMk -A Wi →0 (4)

[0058] In the formula, A PMSMk is the kth harmonic amplitude of the permanent magnet synchronous motor torque, A Wi is the amplitude of group i;

[0059] The phase relationship is as follows:

[0060] φ PMSMk -π=φ Wi =θ si , P Wi (5)

[0061] In the formula, φ PMSMk is the initial phase of the kth harmonic of the permanent magnet synchronous motor, θ si is the initial angle of group i, φ Wi is the phase of group i, P Wi is the number of pole pairs of group i;

[0062] In one embodiment, the stator end face magnetic pole ring group 25k0, k1, k2...k n With the rotor end face magnetic pole ring group 35k0, k1, k2...kn The inner diameters of the stator end face magnetic pole ring groups are all equal; 25k0, k1, k2…k n With the rotor end face magnetic pole ring group 35k0, k1, k2...k n The outer diameters of the stator end face magnetic pole ring groups are all equal; 25k0, k1, k2…k n With the rotor end face magnetic pole ring group 35k0, k1, k2...k n The number of pole pairs is the same; the rotor iron yoke 31, the rotor end face magnetic pole ring group 35k0, k1, k2...k n , the rotor main permanent magnet 30 and the rotating shaft 10 are fixed as a whole;

[0063] In this embodiment, the inner diameter and outer diameter of each set of stator end face magnetic pole rings 25 and the corresponding rotor end face magnetic pole rings 35 (such as stator end face magnetic pole ring 1 and rotor end face magnetic pole ring 1) are respectively equal, the number of pole pairs is the same, and the corresponding magnetic pole center line stagger angle is the starting angle. The rotor iron yoke 31, the rotor end face magnetic pole ring group 35, the rotor main permanent magnet 30 and the rotating shaft 10 are fixed as a whole, and the number of end face magnetic pole ring groups is set according to the main harmonic conditions of the torque;

[0064] Taking a permanent magnet synchronous motor with 9 pole pairs, 216 slots and a speed of 640 rpm as an example, a comparative analysis is performed with a permanent magnet synchronous motor with the same parameters.

[0065] The results of the FFT analysis of the torque of the traditional permanent magnet synchronous motor are shown in the table below;

[0066]

[0067]

[0068] The per-unit value of the suppressed fundamental torque of the permanent magnet synchronous motor of the present application is as follows: Figure 3 As shown, the torque pulsation is obviously suppressed, and the FFT analysis is performed on it, as shown in the following table;

[0069]

[0070] Compared with traditional permanent magnet synchronous motors, the amplitude of the fundamental wave is reduced from 1.95% to 0.12%, which greatly reduces the impact of the fundamental wave on the torque, and the amplitudes of other harmonics have no obvious changes.

[0071] The number of end magnetic pole ring pairs for suppressing the fundamental wave group is 9 (9p), the number of end magnetic pole ring pairs for suppressing the second harmonic group is 18 (18p), and the number of end magnetic pole ring pairs for suppressing the sixth harmonic group is 54 (54p). Fnd is the fundamental wave, h2 is the second harmonic, and h6 is the sixth harmonic.

[0072] The results of the harmonic amplitudes and total harmonic distortion (THD) of the conventional permanent magnet synchronous motor, the motor with each harmonic suppressed individually, and the motor with each harmonic suppressed superimposed are shown in the following table;

[0073]

[0074] like Figure 4 As shown in the figure, compared with the traditional permanent magnet synchronous motor, the harmonic amplitude is greatly reduced, the peak-to-peak value of torque pulsation is reduced from 6.2% to 1.7%, and the THD is reduced from 2.16% to 0.65%. The results prove that the new permanent magnet synchronous motor has good torque pulsation suppression effect and can achieve smooth torque output.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the technical solutions of the present invention have been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A permanent magnet synchronous motor, characterized in that: The invention comprises a stator, a rotor and a rotating shaft (10), wherein the stator comprises a stator winding (20), a stator end face magnetic pole ring group (25) k0, k1, k2, ... n The rotor comprises a rotor main permanent magnet (30), a rotor end face magnetic pole ring group (35) k0, k1, k2...k n and a rotor iron yoke (31), a stator end face magnetic pole ring group (25) k0, k1, k2 ... k n and the rotor end face magnetic pole ring group (35) k0, k1, k2...k n The same group consists of k0, k1, k2...k n Group; where the following relations are satisfied: The functional relationship between the output torque of the permanent magnet synchronous motor and the rotor angle θ is as follows: Where, T PMSM Permanent magnet synchronous motor torque, T DC is the DC component of the torque, k is the harmonic order, A PMSMk is the kth harmonic amplitude of the permanent magnet synchronous motor torque, P PMSM Number of pole pairs of permanent magnet synchronous motor, φ PMSMk is the initial phase of the kth harmonic of the permanent magnet synchronous motor, θ is the rotor angle; ∞ is infinity; The output torque of group i is offset from the center line of the magnetic pole of group i by an angle θ si The functional relationship is as follows: T Wi =A Wi cos(P Wi i si +φ Wi ) (2) Where, T Wi is the output torque of group i, A Wi is the amplitude of group i, P Wi is the number of pole pairs of group i, φ Wi is the phase of group i, θ si is the offset angle of the magnetic pole center line of group i, group i is k0, k1, k2...k n One of the groups; The pole-pair relationship is as follows: P PMSM i=P Wi (3) Where P PMSM Number of pole pairs of permanent magnet synchronous motor, P Wi is the number of pole pairs of group i, group i is k0, k1, k2…k n One of the groups.

2. The permanent magnet synchronous motor according to claim 1, characterized in that: The stator end face magnetic pole ring group (25) k0, k1, k2...k n The rotor end face magnetic pole ring group (35) k0, k1, k2...k n As a group.

3. The permanent magnet synchronous motor according to claim 1 or 2, characterized in that: The permanent magnet synchronous motor torque kth harmonic amplitude A PMSMk The relationship is as follows: A PMSMk -A Wi →0 (4) In the formula, A PMSMk is the kth harmonic amplitude of the permanent magnet synchronous motor torque, A Wi is the amplitude of group i.

4. The permanent magnet synchronous motor according to claim 3, characterized in that: The initial phase φ of the kth harmonic of the permanent magnet synchronous motor PMSMk The relationship is as follows: f PMSMk -π=φ Wi =θ si ·P Wi (5) In the formula, φ PMSMk is the initial phase of the kth harmonic of the permanent magnet synchronous motor, θ si is the initial angle of group i, φ Wi is the phase of group i, P Wi is the number of pole pairs of group i.

5. The permanent magnet synchronous motor according to claim 4, characterized in that: The stator end face magnetic pole ring group (25) k0, k1, k2...k n Both include a stator end surface magnetic pole ring 1 (21) and a stator end surface magnetic pole ring 2 (22).

6. The permanent magnet synchronous motor according to claim 5, characterized in that: The rotor end face magnetic pole ring group (35) k0, k1, k2...k n Both include a rotor end surface magnetic pole ring 1 (32) and a rotor end surface magnetic pole ring 2 (33).

7. The permanent magnet synchronous motor according to claim 6, characterized in that: The stator end face magnetic pole ring group (25) k0, k1, k2...k n The rotor end face magnetic pole ring group (35) k0, k1, k2...k n The inner diameters are equal.

8. The permanent magnet synchronous motor according to claim 7, characterized in that: The stator end face magnetic pole ring group (25) k0, k1, k2...k n The rotor end face magnetic pole ring group (35) k0, k1, k2...k n The outer diameters are equal.

9. The permanent magnet synchronous motor according to claim 8, characterized in that: The stator end face magnetic pole ring group (25) k0, k1, k2...k n The rotor end face magnetic pole ring group (35) k0, k1, k2...k n The number of pole pairs is the same.

10. The permanent magnet synchronous motor according to claim 9, characterized in that: The rotor iron yoke (31), the rotor end face magnetic pole ring group (35) k0, k1, k2...k n The rotor main permanent magnet (30) and the rotating shaft (10) are fixed as a whole.

Images