Permanent magnet motor stator punching sheet with low cogging torque polygonal inner hole

Abstract

The invention discloses a permanent magnet motor stator punching sheet with a low cogging torque polygonal inner bore, the permanent magnet motor stator punching sheet comprises an annular stator yoke part and a plurality of stator teeth extending inwards from the stator yoke part in the radial direction, winding grooves are formed among the stator teeth, the tooth crests of the stator teeth are provided with tooth crest planes, and the tooth crest planes are arranged on the stator yoke part. An inner hole formed by the tooth top planes of the plurality of stator teeth is a regular polygon; the inner hole formed by the tooth crest plane of the permanent magnet motor stator punching sheet is in the shape of the regular polygon, the cogging torque can be well restrained, the sine property of the counter electromotive force of the motor is improved, the air gap harmonic magnetic field is reduced, the performance of the motor can be improved by adopting a smaller air gap, the structure is simple, the cost is low, torque fluctuation is reduced, and the service life of the motor is prolonged. And high-precision servo control is realized.

Description

Technical Field

[0001] The invention relates to the field of permanent magnet motors, and in particular to a permanent magnet motor stator punching sheet with a low cogging moment polygonal inner hole. Background Art

[0002] The stator core of the permanent magnet motor is made of stator stampings stacked by different process methods. The permanent magnet motor is small in size and high in efficiency, but the cogging torque of the motor may be very large and difficult to suppress; the cogging torque (cogging torque) is one of the problems unique to permanent magnet motors and is a key problem that must be considered and solved in the design and manufacture of high-performance permanent magnet motors. Cogging torque is the torque generated by the interaction between the permanent magnet and the stator core when the permanent magnet motor winding is not energized. It is caused by the pulsation of the tangential component of the interaction force between the permanent magnet and the stator teeth. When the motor rotor rotates, the magnetic permeance in a small range of the stator slots on both sides of the permanent magnet changes significantly, causing the magnetic field energy storage to change, thereby generating cogging torque. Cogging torque can cause torque pulsation of the permanent magnet motor, which in turn causes speed fluctuations. Torque pulsation can also cause vibration and noise in the motor. When the frequency of the pulsating torque is consistent with the resonant frequency of the armature current, resonance will occur, which will inevitably amplify the vibration and noise of the cogging torque. It seriously affects the positioning accuracy and servo performance of the motor, especially at low speeds.

[0003] For rare earth permanent magnet motors with concentrated windings, if the motor is a fractional slot concentrated winding motor with the number of slots per pole per phase q = Z / (2Pm) ≤ 1 / 2, where Z is the number of slots, 2P is the number of poles, and m is the number of phases; in the extreme case, the cogging torque reaches a maximum value when the number of poles is equal to the number of slots; therefore, overcoming the cogging torque becomes a difficulty in the design and manufacture of permanent magnet motors.

[0004] The traditional methods to overcome the cogging torque are: selecting reasonable cogging matches, using closed slots or small slots, appropriately increasing the air gap, using rotor skew slots, using rotor eccentricity, and other commonly used methods to suppress the positioning torque. However, all methods will increase the motor leakage, reduce the air gap flux density, and reduce the motor material utilization rate, which is at the expense of the motor's power energy index and performance. In engineering applications, in order to obtain the ideal cogging positioning torque, a combination of multiple methods will be used, which is complex in process, high in cost and affects the output performance of the motor. Therefore, suppressing the positioning torque is still a major problem in the current design and manufacture of permanent magnet motors. In particular, large-diameter torque motors in direct drive systems still use traditional distributed winding structures to obtain good cogging torque. The motor structure and manufacturing process are complex, and the production cost is very high. Summary of the invention

[0005] The purpose of the present invention is to provide a permanent magnet motor stator punching sheet with a low cogging torque polygonal inner hole. The permanent magnet motor made of such a permanent magnet motor stator punching sheet reduces the disadvantage of traditional methods of overcoming the cogging torque but reduces the power index of the permanent magnet motor.

[0006] Based on this, the present invention provides a permanent magnet motor stator punching sheet with a low tooth slot moment polygonal inner hole, the permanent magnet motor stator punching sheet comprising: an annular stator yoke portion and a plurality of stator teeth extending radially inward from the stator yoke portion, winding slots are formed between the stator teeth, the tooth tops of the stator teeth are provided with tooth top planes, and the inner hole formed by the tooth top planes of the plurality of stator teeth is a regular polygon.

[0007] In the low-cogging-torque polygonal inner-hole permanent magnet motor stator punching sheet as described above, the stator yoke comprises a plurality of stator yoke units that can be connected end to end to form a ring, and each stator yoke unit is provided with a stator tooth.

[0008] In the permanent magnet motor stator punching sheet with low cogging moment polygonal inner hole as described above, one end of the stator yoke unit is provided with a connecting groove, and the other end of the stator yoke unit is provided with a connecting portion that can be inserted into the connecting groove.

[0009] As described above, the stator punching sheet of a permanent magnet motor with a low cogging moment polygonal inner hole, the stator yoke comprises: N pieces of stator yoke units that can be connected end to end to form a ring, wherein N is a positive integer.

[0010] The present invention also provides a permanent magnet motor stator punching sheet with a low tooth slot moment polygonal inner hole. The permanent magnet motor stator punching sheet comprises: an annular sleeve, an annular stator yoke portion and a plurality of stator teeth extending radially outward from the stator yoke portion, the tooth tops of the plurality of stator teeth are embedded in the inner side of the annular sleeve, winding slots are formed between the stator teeth, the inner side of the stator yoke portion is provided with tooth root planes corresponding one to one to the stator teeth, and the inner hole formed by the tooth root planes of the plurality of stator teeth is a regular polygon.

[0011] The implementation of the embodiments of the present invention has the following beneficial effects:

[0012] The inner hole formed by the tooth top plane of the permanent magnet motor stator punching sheet of the present invention is a regular polygon, which can very well suppress the tooth slot torque, improve the sinusoidality of the motor back electromotive force, reduce the air gap harmonic magnetic field, and use a smaller air gap to improve the motor performance. It has a simple structure and low cost, which is conducive to reducing torque fluctuations and achieving high-precision servo control. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 It is a schematic diagram of the structure in which the inner hole of the stator punching sheet of a traditional permanent magnet motor is circular.

[0015] Figure 2 It is a front view schematic diagram of a permanent magnet motor stator punching sheet according to Embodiment 1 of the present invention.

[0016] Figure 3 It is an experimental data curve diagram of the cogging torque and rotation angle of the permanent magnet motor stator punching with a circular inner hole in the present invention and the permanent magnet motor stator punching in Example 1.

[0017] Figure 4 It is an experimental data curve diagram of the back electromotive force and rotation angle of the permanent magnet motor stator punching sheet with a circular inner hole in the present invention and the permanent magnet motor stator punching sheet in Example 1.

[0018] Figure 5 It is a front view schematic diagram of the stator yoke unit in Example 2 of the present invention.

[0019] Figure 6 It is a front view schematic diagram of the stator punching sheet of the permanent magnet motor in Example 2 of the present invention.

[0020] Figure 7 It is a front view schematic diagram of the stator yoke in Example 3 of the present invention.

[0021] Figure 8 It is a front view schematic diagram of the annular sleeve in Example 3 of the present invention.

[0022] Fig. 9 It is a front view schematic diagram of the stator punching sheet of the permanent magnet motor in Example 3 of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figures 1 to 9 As shown, the present invention has three specific embodiments. The details are as follows.

[0025] Embodiment 1:

[0026] like Figure 2 As shown, a permanent magnet motor stator punching with a low cogging torque polygonal inner hole of this embodiment, the permanent magnet motor stator punching comprises: a ring-shaped stator yoke 11 and a plurality of stator teeth 12 extending radially inward from the stator yoke 11, winding slots 101 are formed between the stator teeth 12, and the tops of the stator teeth 12 are provided with tooth top planes 1201, and the inner hole 102 formed by the tooth top planes 1201 of the plurality of stator teeth 12 is a regular polygon. The inner hole formed by the tooth top plane of the permanent magnet motor stator punching of the present invention is a regular polygon, which can suppress the cogging torque very well, improve the sinusoidality of the motor back electromotive force, reduce the air gap harmonic magnetic field, and can use a smaller air gap to improve the motor performance, with a simple structure and low cost, which is conducive to reducing torque fluctuations and realizing high-precision servo control.

[0027] like Figure 2 As shown, in this embodiment, the permanent magnet motor stator punching sheets of the experimental group are selected as follows Figure 2 As shown: the number of slots Z = 12, the number of poles 2P = 10; the inner hole of the stator is a regular dodecagon, the air gap is 0.25mm, and the winding coefficient is 0.933. The permanent magnet motor stator punching sheet of the control group is selected as follows Figure 1 As shown in the figure, the inner hole of the stator is circular, and the other data are the same as those of the experimental group. The experimental data curves of the experimental group and the control group are shown in the figure. Figure 3 and Figure 4 As shown in the figure, without detailed optimization, the sinusoidality of the cogging torque and the back EMF are greatly improved, the cogging torque is reduced by nearly 100 times, and the back EMF is of comparable size. The motor force index is maintained while reducing the cogging torque, which is beneficial to reduce torque fluctuations and achieve high-precision servo control.

[0028] Embodiment 2:

[0029] like Figure 2 As shown, the stator punching sheets of the permanent magnet motor of Example 1 are made in one piece; Figure 5 and Figure 6 As shown, in this embodiment: the stator yoke 11 includes a plurality of stator yoke units 111 that can be connected end to end to form a ring, and each stator yoke unit 111 is provided with a stator tooth 12 .

[0030] A connecting groove 1111 is provided at one end of the stator yoke unit 111 , and a connecting portion 1112 which can be inserted into the connecting groove 1111 is provided at the other end of the stator yoke unit 111 .

[0031] In this embodiment, the stator yoke 11 includes: 3N pieces of stator yoke units 111 that can be connected end to end to form a ring, where N is a positive integer.

[0032] Embodiment 3:

[0033] like Figure 2 As shown, the stator punching sheets of the permanent magnet motor of Example 1 are made in one piece; Figure 7 , 8 As shown in Figure 9, in this embodiment, a permanent magnet motor stator punching sheet with a low tooth slot moment polygonal inner hole is provided, and the permanent magnet motor stator punching sheet comprises: an annular sleeve 13, an annular stator yoke 11 and a plurality of stator teeth 12 extending radially outward from the stator yoke 11, the tooth tops of the plurality of stator teeth 12 are embedded in the inner side of the annular sleeve 13, winding slots 101 are formed between the stator teeth 12, and the inner side of the stator yoke 11 is provided with tooth root planes 1202 corresponding to the stator teeth 12 one by one, and the inner hole 102 formed by the tooth root planes 1202 of the plurality of stator teeth 12 is a regular polygon.

[0034] The permanent magnet motor stator punching sheet of Example 1 is not very convenient when winding the enameled wire. In this embodiment, the enameled wire is first wound in the winding groove formed between the stator teeth, and then is put into the annular sleeve. This can achieve the same performance as the permanent magnet motor stator punching sheet of Example 1 and facilitate winding.

[0035] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A permanent magnet motor stator punching sheet with low cogging moment and polygonal inner hole, It is characterized in that The permanent magnet motor stator punching sheet comprises: an annular stator yoke (11) and a plurality of stator teeth (12) extending radially inward from the stator yoke (11), winding slots (101) are formed between the stator teeth (12), and is characterized in that a tooth top plane (1201) is provided at the tooth top of the stator tooth (12), and the inner hole (102) formed by the tooth top planes (1201) of the plurality of stator teeth (12) is a regular polygon.

2. A permanent magnet motor stator punching sheet with a low cogging moment polygonal inner hole according to claim 1, It is characterized in that The stator yoke (11) comprises a plurality of stator yoke units (111) which can be connected end to end to form a ring, and each stator yoke unit (111) is provided with a stator tooth (12).

3. A permanent magnet motor stator punching sheet with a low cogging moment polygonal inner hole according to claim 2, It is characterized in that One end of the stator yoke unit (111) is provided with a connecting groove (1111), and the other end of the stator yoke unit (111) is provided with a connecting portion (1112) capable of being inserted into the connecting groove (1111).

4. A permanent magnet motor stator punching sheet with a low cogging moment polygonal inner hole according to claim 1, It is characterized in that The stator yoke (11) comprises: 3N pieces of stator yoke units (111) which can be connected end to end to form a ring, wherein N is a positive integer.

5. A permanent magnet motor stator punching sheet with low cogging moment and polygonal inner hole, It is characterized in that The permanent magnet motor stator punching sheet comprises: an annular sleeve (13), an annular stator yoke (11) and a plurality of stator teeth (12) extending radially outward from the stator yoke (11), the tooth tops of the plurality of stator teeth (12) are embedded in the inner side of the annular sleeve (13), and winding slots (101) are formed between the stator teeth (12). The invention is characterized in that the inner side of the stator yoke (11) is provided with tooth root planes (1202) corresponding one by one to the stator teeth (12), and the inner hole (102) formed by the tooth root planes (1202) of the plurality of stator teeth (12) is a regular polygon.

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