A low-noise permanent magnet synchronous motor rotor

Abstract

The present invention relates to a low-noise permanent magnet synchronous motor rotor. At least two unit motors are arranged on the rotor lamination body. Each unit motor has a different magnetic pole structure. The magnetic poles in each unit motor are symmetrically and evenly distributed, and the magnetic pole structures of the unit motors adopt a U-shaped or V-shaped structure. The different magnetic pole structures generate different phases of the 0th-order force waves, which can effectively weaken the motor's 24th-order, 48th-order, and other 0th-order force waves, reducing electromagnetic vibration noise.

Description

Technical Field

[0001] The present invention relates to the technical field of synchronous motors, in particular to a low-noise permanent magnet synchronous motor rotor, and more particularly to a built-in low-noise permanent magnet synchronous motor rotor. Background Art

[0002] Permanent magnet synchronous motors have been widely used in automotive drives. There are many factors that affect the performance of permanent magnet synchronous motors, but what gives designers a headache is the impact of motor vibration and noise on motor performance.

[0003] The non-sinusoidal magnetic field generated by permanent magnets, unbalanced armature currents, rotor eccentricity, core saturation, and stator slots all contribute to the generation of harmonic magnetic fields in the motor's air gap. The interaction of these harmonic magnetic fields generates electromagnetic force waves, which act on the stator core, causing vibrations in the stator and its connected mechanical structures. Therefore, electromagnetic force waves excite electromagnetic vibration and noise. The interaction of multiple harmonic magnetic fields complicates the force wave components. Low-order force waves have large amplitudes, and when their frequencies are close to the motor's natural mode frequencies, they can easily cause motor resonance, exacerbating electromagnetic vibration and noise. Therefore, the magnitude, order, and frequency of electromagnetic force waves are directly related to the motor's electromagnetic vibration and noise.

[0004] Existing motor noise reduction methods mainly focus on weakening electromagnetic noise, improving structural strength, and isolating transmission paths. However, the latter two methods are relatively expensive. Weakening the motor's electromagnetic vibration noise from the perspective of electromagnetic design has become a more economical and reliable method.

[0005] For example, in the electromagnetic vibration noise of a 48-slot, 8-pole internal permanent magnet synchronous motor, the 24th and 48th orders are the main noise sources, which are not easy to weaken in the traditional symmetrical structure.

[0006] Therefore, the market is in urgent need of a synchronous motor rotor that can reduce motor vibration noise. Summary of the Invention

[0007] The object of the present invention is to provide an improved low-noise permanent magnet synchronous motor rotor, which can overcome the shortcomings of the prior art such as poor electromagnetic noise reduction and excessive vibration.

[0008] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: a low-noise permanent magnet synchronous motor rotor, including a rotor punching body, characterized in that: at least two unit motors are arranged on the rotor punching body, the magnetic pole structure of each unit motor is different, the magnetic poles in each unit motor are symmetrically and evenly distributed, and the magnetic pole structure of the unit motor adopts a U-shaped structure, a V-shaped structure, an inverted triangle structure or a type structure.

[0009] Preferably, two or three unit motors are provided on the rotor punching body, the two or three unit motors are arranged at intervals from each other, and the unit motors of the same type are symmetrically distributed along the axis of the rotor body.

[0010] Furthermore, the rotor punching body is provided with a rotor slot, and a magnet is provided in the rotor slot. The U-shaped unit motor is provided with a double-layer U-shaped rotor slot, and the double-layer U-shaped rotor slot includes a U-shaped inner rotor slot and a U-shaped outer rotor slot. The inner and outer U-shaped rotor slots are respectively provided with an inner layer of magnet and an outer layer of magnet; the V-shaped unit motor is provided with a V-shaped rotor slot, and the V-shaped rotor slot is provided with a first and a second V-shaped magnet.

[0011] Furthermore, the rotor lamination body is divided into four equal parts. Two symmetrical parts along the central axis of the rotor lamination body are equipped with identical unit motors. Each unit motor is equipped with two sets of V-shaped magnets or two sets of double-layer U-shaped magnets. The magnets in the rotor slots are composed of one or more permanent magnets.

[0012] Compared with the prior art, the technical solution of the present invention not only improves the overall technical solution, but also includes many improvements in details. Specifically, it has the following beneficial effects:

[0013] 1. In the improved solution described in the present invention, at least two unit motors are arranged on the rotor sheet body, and the magnetic pole structure of each unit motor is different. The magnetic poles in each unit motor are symmetrically and evenly distributed. The 0th-order force waves generated by different structures have different phases, which can effectively weaken the 24th-order, 48th-order and other 0th-order force waves of the motor and reduce electromagnetic vibration noise;

[0014] 2. In the technical solution of the present invention, two types of unit motors are provided on the rotor sheet body, namely a U-shaped unit motor and a V-shaped unit motor. The magnetic flux density widths generated by the two layers of magnetic steel are different, which can better reduce harmonics.

[0015] 3. The present invention can change the output torque of the unit motor by adjusting the magnetic pole structure of different unit motors. The different output torques of different unit motors produce phase differences, thereby reducing the torque pulsation of the motor;

[0016] 4. The present invention has a simple structure, is easy to manufacture, and is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the electromagnetic force on the rotor of a permanent magnet synchronous motor in the prior art.

[0018] Figure 2 Schematic diagram of electromagnetic force of the present invention.

[0019] Figure 3 This is a schematic diagram of the cross-sectional structure of the motor rotor of the present invention.

[0020] Figure 4 This is another structural schematic diagram of the motor rotor section of the present invention.

[0021] Figure 5 This is a schematic diagram of the motor rotor structure of the present invention.

[0022] Figure 6 This is a structural diagram of another embodiment of the present invention.

[0023] Figure 7 for Figure 6 Schematic diagram of electromagnetic force in the embodiment.

[0024] Reference numerals:

[0025] AU type structure motor unit, BV type structure motor unit, C inverted triangle structure motor unit;

[0026] 1 outer magnetic steel, 2 inner magnetic steel;

[0027] 3. First V-shaped magnetic steel, 4. Second V-shaped magnetic steel;

[0028] 5. Rotor surface grooves, 6. Rotor punching body. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] The present invention provides a low-noise permanent magnet synchronous motor rotor, see Figure 1 , including a rotor punching body, which differs from the prior art in that: at least two unit motors are arranged on the rotor punching body, the magnetic pole structure of each unit motor is different, and the magnetic poles in each unit motor are symmetrically and evenly distributed, that is, the rotor slots of each unit motor are symmetrically distributed, and the magnetic pole structure of the unit motor adopts a U-shaped structure, a V-shaped structure, an inverted triangle structure or a type I structure.

[0031] Specifically, two types of unit motors are provided on the rotor punching body, and the two unit motors are arranged at intervals from each other. The same type of unit motors are symmetrically distributed along the axis of the rotor body, that is, in the diagonal direction. Unit motor A corresponds to unit motor A, and unit motor B corresponds to unit motor B. Unit motor A adopts a double U-shaped magnetic pole structure, and unit motor B adopts a V-shaped magnetic pole structure, so that the entire motor has a certain topological structure.

[0032] Furthermore, according to the 0th-order force wave expression Where n represents the spatial force wave order, m represents the time particle vibration frequency, Initial angle. Guaranteed In this case, the motor's 0th-order force wave can be weakened better, The closer the absolute value is to 180°, the better the weakening effect.

[0033] According to the 8th order force wave expression The formula generates an 8th order electric force wave, even if Even in this case, second-order electromagnetic force waves are not generated. Therefore, this model does not generate lower-order force waves due to the eighth-order electromagnetic force waves generated by the fundamental magnetic flux density. Due to the different phase differences in the radial force waves output by different unit motors, the vibration distribution of major noise sources such as the 48th and 24th orders is disrupted, thereby reducing vibration noise. This achieves the goal of reducing motor vibration noise during the electromagnetic design stage.

[0034] In one embodiment, the synchronous motor rotor is provided with two unit motors spaced apart from each other, wherein the unit motor A adopts a double-layer U-shaped structure, and the unit motor B adopts a V-shaped structure, and the V-shaped structure is a single-layer structure.

[0035] The rotor lamination body is provided with rotor slots, which are filled with magnets. The U-shaped unit motor has double-layer U-shaped rotor slots, which include an inner U-shaped rotor slot and an outer U-shaped rotor slot. The inner and outer U-shaped rotor slots contain inner and outer magnetic steels, respectively. The V-shaped unit motor has V-shaped rotor slots, which contain first and second V-shaped magnets. The magnets in the rotor slots are composed of one or more permanent magnets.

[0036] In another embodiment (see Figure 6 、 Figure 7 ), three types of unit motors are provided on the rotor punching body, and the three unit motors are arranged at intervals from each other. The same type of unit motors are symmetrically distributed along the axis of the rotor body. This structure is a 12-pole rotor, and the three unit single machines are respectively a double-layer U-shaped structure, a V-shaped structure and an inverted triangle structure. When set, two double-layer U-shaped structures are used as unit motor A, and the double-layer U-shaped structure includes an outer layer of magnetic steel, an inner layer of magnetic steel and an auxiliary magnetic steel arranged between the inner and outer layers of magnetic steel. Two V-shaped structures are used as unit motor B, and two inverted triangle structures are used as unit motor C, and the magnetic poles are symmetrically distributed.

[0037] Here, a three-unit motor model is used, and the number of pole pairs must be a multiple of 3. The advantages are as follows:

[0038] 1. The use of three unit motors can effectively weaken the motor's 0th-order electromagnetic force wave and reduce motor vibration noise;

[0039] 2. Due to the asymmetry of the structure on the circumference, the torque ripple of the motor can be weakened and the back EMF harmonics can be reduced;

[0040] 3. In the 3-pole and 9-pole models, two unit motor models cannot be used, only 3 unit motor models can be used.

[0041] In another embodiment, the rotor punching body is divided into four equal parts, and two symmetrical parts along the central axis of the rotor punching body are provided with identical unit motors, each unit motor is provided with two groups of V-shaped magnets or two groups of double-layer U-shaped magnets, wherein unit motor B is provided with two groups of symmetrically arranged V-shaped rotor slots, and V-shaped slot reinforcement ribs are provided between the left and right side slots of each V-shaped rotor slot, and separate or assembled magnets are provided in the V-shaped rotor slot, and gaps are left between the two ends of the magnet and the end of the V-shaped rotor slot.

[0042] The V-shaped angle range of the V-shaped rotor slot is 120°-145°; a U-shaped inner rotor magnet is provided in the middle of the U-shaped inner rotor slot, and the U-shaped outer rotor slot is composed of a middle slot and two symmetrically arranged side slots. A reinforcing rib is provided between the middle slot and the side slots, and the width range of the reinforcing rib is 0.8-2.0 mm, preferably 1.2 mm.

[0043] The main rotor harmonics that affect the electromagnetic vibration and noise performance of motors are the 5th, 7th, 11th, and 13th harmonics. A single motor unit model can only specifically attenuate the 5th, 7th, or 11th, 13th harmonics, but cannot attenuate the 0th-order force wave generated by interaction with the stator harmonics. Unit A motors use a double-layer magnet arrangement with a spacing of 6-10mm between the two layers. Unit B motors use a single-layer magnet arrangement with flux density widths of l2 and l2', respectively. To achieve optimal harmonic attenuation, the flux density lengths l2 and l2' should satisfy the following relationship as closely as possible.

[0044] To weaken the 0th to 24th order harmonics, the following relationship must be satisfied:

[0045]

[0046] To weaken the 0th to 48th order harmonics, the following relationship must be satisfied:

[0047]

[0048]

[0049] Considering the influence of magnetic steel leakage, core saturation and reinforcement ribs, the actual width of each section of magnetic steel needs to be slightly compensated. The magnetic steel width correction is as follows:

[0050]

[0051] Calculation of magnetic steel width after double-layer structure correction:

[0052]

[0053] Calculation of magnetic steel width after correction of single-layer structure:

[0054]

[0055] Where h rib2 The width of the second layer of reinforcement ribs ranges from 0.8 to 2.0 mm. bride1 、h bride2 The width of the first and second magnetic isolation bridges is selected from a range of 0.8-1.2mm, r is the rotor radius; Δx1 and Δx2 are the distances from the magnetic edge closest to the q-axis to the magnetic isolation bridge, which vary with the motor structure; h1 is the thickness of the first magnetic layer (3-4mm), h2 is the thickness of the second magnetic layer (5-6mm), and Δl1 and Δl2 are the correction widths to make the air gap flux density waveform closer to a sine wave. The reinforcement value here ensures mold life and the structural strength of the rotor lamination at high speeds. The smaller the magnetic isolation bridge width, the more sinusoidal the air gap flux density waveform, ensuring the air gap sinusoidality.

[0056] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to the above description. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A low-noise permanent magnet synchronous motor rotor, comprising a rotor sheet body, characterized in that: At least two unit motors are arranged on the rotor sheet body, each unit motor has a different magnetic pole structure, and the magnetic poles in each unit motor are symmetrically and evenly distributed. Two types of unit motors are installed on the rotor punching body. The two unit motors are arranged at intervals from each other, and the same unit motors are symmetrically distributed along the axis of the rotor body. The magnetic pole structure in each unit motor generates 0-order force waves of different phases, thereby generating a phase difference, which is used to weaken the 24th and 48th order 0-order force waves of the motor and reduce motor vibration noise. Two types of unit motors are used. Unit motor A adopts a double-layer U-shaped magnetic pole structure, and the spacing between the double-layer magnetic steel is 6-10mm; unit motor B adopts a single-layer V-shaped magnetic pole structure, and the V-shaped angle range of the V-shaped rotor slot is 120°-145°; the rotor punching body is provided with a rotor slot, and the rotor slot is provided with a magnetic steel. The U-shaped unit motor is provided with a double-layer U-shaped rotor slot, and the double-layer U-shaped rotor slot includes a U-shaped inner rotor slot and a U-shaped outer rotor slot, and the U-shaped inner and outer rotor slots are respectively provided with an inner layer of magnetic steel and an outer layer of magnetic steel; the V-shaped unit motor is provided with a V-shaped rotor slot, and the V-shaped rotor slot is provided with a first and a second V-shaped magnetic steel; the rotor punching body is divided into four equal parts, and two symmetrical parts along the central axis of the rotor punching body are provided with identical unit motors, and each unit motor is provided with two groups of V-shaped magnetic steel or two groups of double-layer U-shaped magnetic steel.

2. The low-noise permanent magnet synchronous motor rotor according to claim 1, characterized in that: The U-shaped outer rotor slot consists of a middle slot and two symmetrically arranged side slots. A reinforcing rib is provided between the middle slot and the side slots, and the width of the reinforcing rib is 0.8-2.0 mm.

3. The low-noise permanent magnet synchronous motor rotor according to claim 2, characterized in that: The magnetic steel in the rotor slot is composed of one or more permanent magnets.

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