Fractional slot permanent magnet synchronous motor and method for suppressing vibration of fractional slot permanent magnet synchronous motor

Abstract

The invention discloses a fractional-slot permanent magnet synchronous motor and a method for suppressing vibration of the fractional-slot permanent magnet synchronous motor, a magnetic conductive slot wedge is arranged at a stator slot corresponding to each basic unit of the fractional-slot permanent magnet synchronous motor, and the top of the magnetic conductive slot wedge is an arc. The side, close to the air gap, of the permanent magnet synchronous motor stator is connected with the top of the magnetic conductive slot wedge to form a complete inner circle. Orientation type electrical steel is rolled into a magnetic conductive slot wedge with the radial direction of the motor as the rolling direction, and the magnetic conductive slot wedge is arranged at a stator notch of the fractional-slot permanent magnet synchronous motor; the permanent magnet synchronous motor provided by the invention can restrain vibration of other orders, except for 0-order vibration and integral multiple-pole-number vibration, generated by the motor, the stability of motor operation is improved, meanwhile, the inductance of the motor can be increased, the short-circuit current of a stator winding can be restrained, and the fault-tolerant capability of the motor is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and particularly relates to a fractional-slot permanent magnet synchronous motor and a method for suppressing its vibration. Background Art

[0002] Compared with traditional integer-slot permanent magnet synchronous motors, fractional-slot permanent magnet synchronous motors have many advantages such as large torque density, small volume, and high power density. The winding forms configured are also more conducive to realizing fault-tolerant control, so they are widely used in fields such as aviation, space shuttles, unmanned aerial vehicles, and electric vehicles. Due to the influence of stator slotting effects on the air-gap magnetic density, in addition to the 0th-order vibration, the motor will generate vibrations at integer multiples of the greatest common divisor <GCD(N,2p)> of the number of slots and the number of poles, where N is the number of slots of the motor and 2p is the number of poles of the motor. Therefore, compared with integer-slot permanent magnet synchronous motors, fractional-slot permanent magnet synchronous motors will have a large number of low-order vibrations, which have a great impact on the safe and stable operation of the motor. Summary of the Invention

[0003] The purpose of the present invention is to provide a fractional-slot permanent magnet synchronous motor and a method for suppressing its vibration, which can greatly reduce the motor vibration while ensuring the original output capacity of the motor.

[0004] To achieve the above object, the solution of the present invention is:

[0005] A method for suppressing the vibration of a fractional-slot permanent magnet synchronous motor, in which a magnetic conductive slot wedge is installed at the stator slot opening corresponding to each basic unit of the fractional-slot permanent magnet synchronous motor, and the top of the magnetic conductive slot wedge is an arc, so that a complete inner circle is formed by connecting the side of the permanent magnet synchronous motor stator close to the air gap with the top of the magnetic conductive slot wedge.

[0006] The above magnetic conductive slot wedge is rolled from grain-oriented electrical steel.

[0007] The direction of rolling the above magnetic conductive slot wedge made of grain-oriented electrical steel is the radial direction of the motor, so that the radial magnetic conduction ability during the motor load operation is much stronger than the tangential magnetic conduction ability.

[0008] The radial thickness of the above magnetic conductive slot wedge is greater than the stator slot shoulder height of the permanent magnet synchronous motor and less than the stator tooth pole shoe height of the permanent magnet synchronous motor; based on the comprehensive consideration of the manufacturing cost of the magnetic conductive slot wedge and the ability of the magnetic conductive slot wedge to suppress motor vibration, the user can reasonably select the thickness of the magnetic conductive slot wedge within the above range, and it is recommended that the thickness is slightly less than the stator tooth pole shoe height of the permanent magnet synchronous motor, and the axial length of the magnetic conductive slot wedge is the same as the axial length of the motor stator.

[0009] The above magnetic conductive slot wedge is fixed with each side parallel to the stator tooth or fixed to the stator tooth by a dovetail groove.

[0010] When the above magnetic conductive slot wedge is installed at the stator slot opening, there is a gap between it and the stator tooth, avoiding intense friction between the stator tooth and the slot wedge during installation, which may affect the magnetic conductivity of the stator tooth and the slot wedge. The width of the air gap should ensure that the air gap has little impact on the motor magnetic field.

[0011] The above fractional-slot permanent magnet synchronous motor is a traditional common fractional-slot permanent magnet synchronous motor with normal stator slotting, covering all fractional-slot permanent magnet synchronous motors where the number of poles 2p is greater than the greatest common divisor <GCD(N, 2p)> of the number of poles and the number of slots (such as a 12-slot 10-pole motor, a 24-slot 22-pole motor).

[0012] A fractional-slot permanent magnet synchronous motor, the fractional-slot permanent magnet synchronous motor includes several basic units, and magnetic conductive slot wedges are installed at the stator slot openings corresponding to each basic unit. The top of the magnetic conductive slot wedge is an arc, so that a complete inner circle is formed by connecting the side of the permanent magnet synchronous motor stator close to the air gap and the top of the magnetic conductive slot wedge.

[0013] The above magnetic conductive slot wedge is rolled from grain-oriented electrical steel.

[0014] The rolling direction of the above grain-oriented electrical steel rolled magnetic conductive slot wedge is the radial direction of the motor.

[0015] After adopting the above scheme, the present invention uses grain-oriented electrical steel to roll and manufacture a magnetic conductive slot wedge with the radial direction of the motor as the rolling direction, and installs the magnetic conductive slot wedge at the stator slot opening of the fractional-slot permanent magnet synchronous motor; the permanent magnet synchronous motor provided by the present invention can suppress other-order vibrations of the motor except for the 0-order vibration and the vibration of integer multiples of the number of poles, increase the stability of the motor operation, and at the same time can increase the motor inductance, which is beneficial to suppressing the short-circuit current of the stator winding and enhancing the fault tolerance of the motor. Description of the Drawings

[0016] Figure 1 is the structural model of a classical open-slot 12-slot 10-pole permanent magnet synchronous motor, and the method of the present invention has not been used in this motor structure;

[0017] Figure 2 is Figure 1 the partial enlarged view of I in, and the method provided by the present invention has been used in the motor structure;

[0018] Figure 3 is Figure 2 the partial enlarged view of II in;

[0019] Figure 4 is Figure 2 the partial enlarged view of III in;

[0020] Figure 5The simulation data of the radial electromagnetic force density wave of a permanent magnet synchronous motor with an open slot of 12 slots and 10 poles and a permanent magnet synchronous motor of 12 slots and 10 poles with the orientation-type magnetic conductive slot wedge added according to the present invention under the same stator and rotor dimensions when powered by a 12A sinusoidal current;

[0021] Among them, (a) is the FFT three-dimensional analysis result of the radial electromagnetic force density wave of the permanent magnet synchronous motor with an open slot of 12 slots and 10 poles, (b) is the FFT two-dimensional analysis result of the radial electromagnetic force density wave of the permanent magnet synchronous motor with an open slot of 12 slots and 10 poles at time t = 0, (c) is the FFT three-dimensional analysis result of the radial electromagnetic force density wave of the permanent magnet synchronous motor with a closed slot of 12 slots and 10 poles, and (d) is the FFT two-dimensional analysis result of the radial electromagnetic force density wave of the permanent magnet synchronous motor with a closed slot of 12 slots and 10 poles at time t = 0.

[0022] Reference numerals:

[0023] 101 - permanent magnet, 102 - stator, 103 - magnetic conductive slot wedge, 104 - rotor. Detailed implementation manners

[0024] The technical solutions and beneficial effects of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] The present invention provides a fractional-slot permanent magnet synchronous motor capable of suppressing motor vibration. Among the existing relatively mature fractional-slot permanent magnet synchronous motors with the number of poles 2p greater than the greatest common divisor <GCD(N, 2p)> of the number of poles and the number of slots that have been put into operation, according to the stator slot opening dimensions of the motor, an arc is formed at the top of the rolled magnetic conductive slot wedge, so that a complete inner circle is formed by connecting the side of the stator of the permanent magnet synchronous motor close to the air gap with the top of the magnetic conductive slot wedge after the magnetic conductive slot wedge is installed; according to the actual situation, when the fractional-slot permanent magnet synchronous motor includes m basic units (m is the greatest common divisor of N and 2p), magnetic conductive slot wedges are arranged at the corresponding slot openings of each basic unit, and in a preferred embodiment, magnetic conductive slot wedges are arranged at each stator slot opening; the radial thickness of the magnetic conductive slot wedge is higher than the height of the stator slot shoulder of the permanent magnet synchronous motor and less than the height of the stator tooth pole shoe of the permanent magnet synchronous motor; based on a comprehensive consideration of the manufacturing cost of the magnetic conductive slot wedge and the ability of the magnetic conductive slot wedge to suppress the vibration of the electrode, the user can reasonably select the thickness of the magnetic conductive slot wedge within the above range, and in a preferred embodiment, the thickness is slightly less than the height of the stator tooth pole shoe of the permanent magnet synchronous motor; the axial length of the magnetic conductive slot wedge is the same as the axial length of the motor stator, and a very small air gap is ensured between the magnetic conductive slot wedge and the stator tooth, and the width of the air gap needs to ensure that the air gap hardly affects the magnetic field of the motor. The purpose is to avoid severe friction during the installation of the magnetic conductive slot wedge, which causes the deterioration of the magnetic conductivity of the stator tooth and the magnetic conductive slot wedge. The magnetic conductive slot wedge is rolled from oriented electrical steel with the radial direction of the motor as the rolling direction.

[0026] In an alternative embodiment, the structure is not limited to being added to a mature motor that is already in operation, and the structure can also be directly designed during the production and processing of a new motor.

[0027] In an alternative embodiment, the specific shape of the slot wedge can be changed, and slot wedge structures such as dovetail grooves and circular splicing grooves can be used to fix the slot wedge on the stator teeth.

[0028] Example:

[0029] Figure 1 Shown is a model of a classic open-slot 12-slot 10-pole fractional-slot concentrated-winding permanent magnet synchronous motor. The motor consists of a stator 102, a rotor 104, permanent magnets 101, and armature windings. This motor topology has currently been widely used in various fields. The number of slots N of the shown motor is 12, and the number of pole pairs p is 5. The number of pole pairs and the number of slots of the shown motor meet the requirement of the present invention that the number of poles 2p of the motor must be greater than the greatest common divisor <GCD(N,2p)> of the number of poles and the number of slots.

[0030] Figure 2 For Figure 1 a partial enlarged view of I, and the motor structure has used the structure provided by the present invention. The magnetic conductive slot wedge 103 is rolled from the B30P105 grain-oriented electrical steel of Baoshan Iron & Steel Co., Ltd. Figure 2 The dotted line at the center of each magnetic conductive slot wedge in I represents the rolling direction of the electrical steel (i.e., the radial direction of the motor).

[0031] Figure 3 For Figure 2 a partial enlarged view of II, where l1 represents the gap between the magnetic conductive slot wedge and the stator tooth, which is 0.05 mm in this embodiment. The current industrial techniques can meet this requirement and can avoid severe friction between the slot wedge and the stator tooth. l2 represents the minimum gap between the inner circle of the stator and the permanent magnet, that is, the "air gap" value in the motor industry, which is 1.2 mm in this embodiment. Since l2 >> l1, l1 in this embodiment hardly affects the air gap magnetic field.

[0032] Figure 4 For Figure 2 a partial enlarged view of III, h w represents the thickness of the slot wedge, which is 2.2 mm in this embodiment, h s represents the height of the stator tooth pole shoe of the permanent magnet synchronous motor, which is 2.5 mm in this embodiment, h t represents the height of the stator slot shoulder of the permanent magnet synchronous motor, which is 1.2 mm in this embodiment. Therefore, in this embodiment, h t <h w <h s The thickness of the slot wedge h w and is only slightly less than the height h s, it is ensured that the motor using the method of the invention in this embodiment will not generate a large production cost while suppressing vibration. The top of the slot wedge is an arc, so that after installing the magnetic conductive slot wedge, the side of the permanent magnet synchronous motor stator close to the air gap is connected with the top of the magnetic conductive slot wedge to form a complete inner circle.

[0033] Figure 5 For a permanent magnet synchronous motor with 12 slots and 10 poles in open slots under the same stator and rotor dimensions (i.e., Figure 1 ) and the 12-slot 10-pole permanent magnet synchronous motor with an oriented magnetic conductive slot wedge added in the embodiment of the present invention (i.e., Figure 2 ) are the simulation data of the radial electromagnetic force density wave.

[0034] From Figure 4 it can be seen that for the 12-slot 10-pole permanent magnet synchronous motor with an oriented magnetic conductive slot wedge added in the embodiment of the present invention, compared with the 12-slot 10-pole permanent magnet synchronous motor in open slots, the radial electromagnetic force except for the 0th-order force and the force of an integer multiple of the number of poles can be greatly weakened.

[0035] The amplitude of the vibration deformation response caused by the radial electromagnetic force of the permanent magnet synchronous motor can be expressed as:

[0036]

[0037] In formula (1), F o represents the amplitude of the 0th-order radial electromagnetic force, V o represents the amplitude of the vibration deformation response caused by the 0th-order radial electromagnetic force, R y is the average radius of the stator yoke, T y is the thickness of the stator yoke, R is the inner diameter of the stator, and E is the value of the Young's modulus of the stator material.

[0038] Formula (1) shows that for a permanent magnet synchronous motor with the same stator and rotor size results, the amplitude of the vibration deformation response caused by the radial electromagnetic force is only affected by the order of the radial electromagnetic force and the amplitude of the radial electromagnetic force, and the amplitude of the 0th-order vibration response is only proportional to the amplitude of the 0th-order radial electromagnetic force and inversely proportional to the 4th power of the order 0, indicating that the low-order radial force is far more harmful to the vibration of the motor than the high-order radial force. That is, in this embodiment, for Figure 1 and Figure 2 in the two motors, their stator and rotor size structures are the same, that is, the values of R y , T y , R, and E of the two motors are all the same. Combining Figure 5As shown, although the low-order radial electromagnetic forces such as the 2nd, 4th, 6th order, etc. generated by the original open-slot 12-slot 10-pole permanent magnet synchronous motor have smaller amplitudes compared to the high-order radial electromagnetic forces such as the 10th and 20th order, due to their lower orders, the vibration deformation responses generated are much greater than those generated by the high-order radial electromagnetic forces. Under the embodiments of the method of the present invention, the 12-slot 10-pole permanent magnet synchronous motor with the addition of the oriented magnetic conductive slot wedge greatly weakens the radial electromagnetic forces except for the 0th order force and the forces of integer multiples of the number of poles, that is, greatly weakens the vibration responses caused by these low-order motor radial electromagnetic forces.

[0039] The simulation results show that the output torque of the open-slot 12-slot 10-pole permanent magnet synchronous motor is 8.07 N·m, and the output torque of the 12-slot 10-pole permanent magnet synchronous motor with the addition of the oriented magnetic conductive slot wedge under the embodiments of the present invention is 7.82 N·m. The output capacity of the 12-slot 10-pole permanent magnet synchronous motor with the addition of the oriented magnetic conductive slot wedge under the embodiments of the present invention only decreases by about 3%, indicating that the 12-slot 10-pole permanent magnet synchronous motor with the addition of the oriented magnetic conductive slot wedge under the embodiments of the present invention can greatly weaken the vibration deformation response caused by the radial electromagnetic force while ensuring the output capacity of the motor.

[0040] The tangential magnetic conductivity of the magnetic conductive slot wedge is stronger than that of air. Therefore, compared with the open-slot 12-slot 10-pole permanent magnet synchronous motor, the 12-slot 10-pole permanent magnet synchronous motor with the addition of the oriented magnetic conductive slot wedge under the embodiments of the present invention has a larger inductance, which is beneficial to suppressing the short-circuit current.

[0041] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can be in the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented in various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0042] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, and the combination of processes and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, so that the instructions executed by the processors of the computer or other programmable data processing devices generate for implementation in the process Figure 1one or more processes and / or blocks Figure 1 means for the functions specified in one or more blocks

[0043] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means that implement the functions in the process Figure 1 one or more processes and / or blocks Figure 1 means for the functions specified in one or more blocks

[0044] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions in the process Figure 1 one or more processes and / or blocks Figure 1 means for the functions specified in one or more blocks

[0045] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn the basic inventive concept. Therefore, the appended claims are intended to be construed to cover the preferred embodiments as well as all changes and modifications falling within the scope of the present invention

[0046] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations

Claims

1. A method for suppressing vibration of a fractional-slot permanent magnet synchronous motor, characterized in that: A magnetic slot wedge is installed in the stator slot corresponding to each basic unit of the fractional-slot permanent magnet synchronous motor. The top of the magnetic slot wedge is an arc, so that the side of the permanent magnet synchronous motor stator close to the air gap is connected with the top of the magnetic slot wedge to form a complete inner circle.

2. The method for suppressing vibration of a fractional-slot permanent magnet synchronous motor according to claim 1, characterized in that: The magnetically conductive slot wedge is made by rolling oriented electrical steel.

3. The method for suppressing vibration of a fractional-slot permanent magnet synchronous motor according to claim 2, characterized in that: The direction of rolling the magnetic groove wedges with the oriented electrical steel is the radial direction of the motor.

4. The method for suppressing vibration of a fractional-slot permanent magnet synchronous motor according to claim 1, characterized in that: The radial thickness of the magnetic conductive slot wedge is greater than the stator slot shoulder height of the permanent magnet synchronous motor and less than the stator tooth pole shoe height of the permanent magnet synchronous motor.

5. The method for suppressing vibration of a fractional-slot permanent magnet synchronous motor according to claim 1, characterized in that: Each side of the magnetic conductive slot wedge is fixed parallel to the stator teeth or fixed by using a dovetail slot to engage the stator teeth.

6. The method for suppressing vibration of a fractional-slot permanent magnet synchronous motor according to claim 1, characterized in that: When the magnetically conductive slot wedge is installed in the stator slot, a gap is left between it and the stator teeth.

7. The method for suppressing vibration of a fractional-slot permanent magnet synchronous motor according to claim 1, characterized in that: The number of all poles 2p of the fractional slot permanent magnet synchronous motor is greater than the greatest common divisor of the number of poles and the number of slots<GCD(N,2p)> .

8. A fractional-slot permanent magnet synchronous motor, characterized in that: The fractional-slot permanent magnet synchronous motor comprises several basic units, and the stator slot corresponding to each basic unit is equipped with a magnetic slot wedge, and the top of the magnetic slot wedge is an arc, so that the side of the permanent magnet synchronous motor stator close to the air gap is connected with the top of the magnetic slot wedge to form a complete inner circle.

9. The fractional-slot permanent magnet synchronous motor according to claim 8, characterized in that: The magnetically conductive slot wedge is made by rolling oriented electrical steel.

10. The fractional-slot permanent magnet synchronous motor according to claim 9, characterized in that: The direction of rolling the magnetic groove wedges with the oriented electrical steel is the radial direction of the motor.

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