Rotor punching sheet with asymmetric auxiliary groove structure, rotor core and permanent magnet motor

Abstract

The invention discloses a rotor punching sheet with an asymmetric auxiliary groove structure, a rotor core and a permanent magnet motor, and the rotor punching sheet comprises a plurality of unit parts, each unit part comprises a first pair of asymmetric auxiliary grooves and a second pair of asymmetric auxiliary grooves, and the first pair of asymmetric auxiliary grooves comprises a first left auxiliary groove and a first right auxiliary groove; the first left auxiliary groove and the first right auxiliary groove are located on the two sides of the magnetic pole d-axis. The second pair of asymmetric auxiliary grooves comprises a left auxiliary groove II and a right auxiliary groove II; the second left auxiliary groove and the second right auxiliary groove are located on the two sides of the magnetic pole d-axis. At least one of three parameters of the notch width, the notch depth and the offset from the notch bottom to the notch center between the first left auxiliary groove and the first right auxiliary groove is different; and at least one of three parameters of the notch width, the notch depth and the offset from the notch bottom to the notch center between the second left auxiliary groove and the second right auxiliary groove is different. The non-sinusoidal distribution of the air-gap magnetic field of the permanent magnet motor can be improved, and the harmonic content of the air-gap flux density is reduced, so that the vibration noise of the motor is reduced, and the operation stability of the motor is improved.

Description

Technical Field

[0001] The invention relates to the technical field of permanent magnet motors, and in particular to a rotor punching sheet with an asymmetric auxiliary slot structure, a rotor core and a permanent magnet motor. Background Art

[0002] Built-in permanent magnet motors have the characteristics of high power density, high efficiency, wide speed range, stable operation, etc., and are widely used in the automotive field. With the continuous expansion of the new energy vehicle market, in addition to the requirements for the power, economy and safety of electric vehicles, the comfort of the driving environment, low vibration and low noise are gradually becoming important criteria for choosing a car.

[0003] The high speed of permanent magnet motors widens the vibration frequency range of the system, which can easily cause system resonance. In addition, due to the lightweight of the motor system, the stiffness decreases, and the electromagnetic excitation of the motor will cause greater high-frequency electromagnetic vibration noise, which will undoubtedly significantly reduce the ride comfort and operating reliability of electric vehicles, and reduce the driving comfort and reliability of new energy vehicles.

[0004] There are two main methods for reducing motor vibration at present: one is to suppress it through control algorithms, and the other is to suppress it from the motor design. Due to hardware and computing power limitations, there are great limitations in using algorithms for suppression. Therefore, suppressing motor vibration noise through design is the current mainstream method. Currently, there are mainly stator and rotor topology optimization, stator and rotor auxiliary slots, stator and rotor skewed poles, skewed slots and other means. In the actual production process, a specific method can be selected for suppression based on the actual situation.

[0005] Among them, the optimization of the rotor auxiliary slot structure is one of the common methods to reduce the motor cogging torque and reduce vibration and noise. At present, the research of domestic and foreign scholars is mainly based on the auxiliary slot structure with symmetrical arrangement. For example, the existing patents with announcement numbers CN215498476U and CN211606216U disclose that by opening symmetrical auxiliary slot groups in the rotor punching sheets, the sinusoidal nature of the air gap magnetic flux density is improved, and the cogging torque fluctuation and motor torque fluctuation are reduced. The research on the asymmetry of the rotor is also mostly limited to the asymmetry between the magnetic poles and the magnetic barriers. However, the existing symmetrical rotor auxiliary slot structure optimization has its limitations, and it is difficult to meet the application requirements of low vibration and noise under high frequency and high fluctuation conditions. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a rotor punching, a rotor core and a permanent magnet motor with an asymmetric auxiliary slot structure. The asymmetric rotor auxiliary slot structure is used to improve the non-sinusoidal distribution of the air gap magnetic field of the permanent magnet motor, reduce the harmonic content of the air gap magnetic density, thereby reducing the vibration noise of the motor and improving the operating stability of the motor. Compared with the motor with a symmetrical auxiliary slot structure, it can be better suitable for high-frequency and high-fluctuation applications.

[0007] In order to achieve the above object, the present invention discloses a rotor punching sheet with an asymmetric auxiliary slot structure, comprising a plurality of unit parts, wherein the unit parts include a first pair of asymmetric auxiliary slots and a second pair of asymmetric auxiliary slots:

[0008] The first pair of asymmetric auxiliary slots includes a left auxiliary slot and a right auxiliary slot; the left auxiliary slot and the right auxiliary slot are respectively located on both sides of the magnetic pole d axis; the second pair of asymmetric auxiliary slots includes a left second auxiliary slot and a right second auxiliary slot; the left second auxiliary slot and the right second auxiliary slot are respectively located on both sides of the magnetic pole d axis;

[0009] The positioning point angles of the left auxiliary slot and the right auxiliary slot are the same; the positioning point angles of the left second auxiliary slot and the right second auxiliary slot are the same; wherein the positioning point angle is the angle between the line connecting the midpoint of the auxiliary slot opening and the center of the rotor punching and the d-axis of the magnetic pole;

[0010] At least one of the three parameters of the slot width, slot depth, and offset from the slot bottom to the slot center between the left auxiliary slot and the right auxiliary slot is different; at least one of the three parameters of the slot width, slot depth, and offset from the slot bottom to the slot center between the left second auxiliary slot and the right second auxiliary slot is different.

[0011] Furthermore, it also includes a first layer of magnetic steel units and a second layer of magnetic steel units, the first layer of magnetic steel units are symmetrically arranged on both sides of the magnetic pole d axis, the second layer of magnetic steel units are symmetrically arranged on both sides of the magnetic pole d axis, and the first layer of magnetic steel units are located on the outside of the second layer of magnetic steel units.

[0012] Furthermore, the first pair of asymmetric auxiliary slots are located between the magnetic isolation bridge of the first layer of magnetic steel units and the magnetic isolation bridge of the second layer of magnetic steel units, and the positioning point angle of the second pair of asymmetric rotor auxiliary slots is smaller than the magnetic pole arc angle of the second layer of magnetic steel units.

[0013] On the other hand, the present invention further discloses a rotor core formed by stacking a plurality of rotor punching sheets with the asymmetric auxiliary slot structure.

[0014] On the other hand, the present invention also discloses a permanent magnet motor, comprising the rotor core.

[0015] Beneficial effects of the present invention:

[0016] The present invention provides asymmetric auxiliary slots on the surface of the rotor core magnetic poles, which can effectively improve the non-sinusoidal distribution of the air gap magnetic field of the permanent magnet motor, reduce the harmonic content of the air gap magnetic density, thereby reducing the cogging torque, torque pulsation and radial electromagnetic force, reduce the electromagnetic vibration and noise of the motor, meet the driving requirements of electric vehicles, and achieve the characteristics of high power density, low noise, low torque fluctuation, wide speed regulation, small size, light weight and smooth operation of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the rotor punching unit of the present invention.

[0018] Figure 2 It is a schematic diagram of the present invention for reflecting various parameters on the rotor punching sheet.

[0019] Figure 3 It is a comparison diagram of the cogging torque waveforms of two motors with asymmetric auxiliary slots and symmetric auxiliary slots.

[0020] Figure 4 It is a comparison diagram of the output torque waveforms of two motors with asymmetric auxiliary slots and symmetric auxiliary slots.

[0021] In the figure: 1. Left first auxiliary slot; 2. Left second auxiliary slot; 3. Right second auxiliary slot; 4. Right first auxiliary slot; 5. Magnetic steel slot; 6. Rotor punching sheet; 7. Second layer magnetic steel unit; 8. First layer magnetic steel unit. DETAILED DESCRIPTION

[0022] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0023] In a first aspect, the present invention discloses a rotor punching having an asymmetric auxiliary slot structure.

[0024] Reference Figure 1 A rotor punching sheet with an asymmetric auxiliary slot structure includes a plurality of unit parts, wherein the unit parts include a first pair of asymmetric auxiliary slots, a second pair of asymmetric auxiliary slots, a first layer of magnetic steel units 8 and a second layer of magnetic steel units 7.

[0025] The first pair of asymmetric auxiliary slots includes a left auxiliary slot 1 and a right auxiliary slot 4, and the left auxiliary slot 1 and the right auxiliary slot 4 are respectively located on both sides of the magnetic pole d axis; the second pair of asymmetric auxiliary slots includes a left second auxiliary slot 2 and a right second auxiliary slot 3, and the left second auxiliary slot 2 and the right second auxiliary slot 3 are respectively located on both sides of the magnetic pole d axis. The first pair of asymmetric auxiliary slots and the second pair of asymmetric auxiliary slots are both triangular auxiliary slots, and the first pair of asymmetric auxiliary slots are located outside the second pair of asymmetric auxiliary slots.

[0026] The positioning point angles of the left auxiliary slot 1 and the right auxiliary slot 4 are the same; the positioning point angles of the left second auxiliary slot 2 and the right second auxiliary slot 3 are the same; the above-mentioned positioning point angles are the angles between the line connecting the midpoint of the auxiliary slot opening and the center of the rotor punching 6 and the magnetic pole d axis; in this embodiment, the positioning point angle of the first asymmetric auxiliary slot is set to α, and the positioning point angle of the second asymmetric auxiliary slot is set to β.

[0027] Reference Figure 2In this embodiment, the slot width, slot depth and the offset from the slot bottom to the slot center of the left auxiliary slot 1 are represented by parameters A, E and I respectively; the slot width, slot depth and the offset from the slot bottom to the slot center of the right auxiliary slot 4 are represented by parameters B, F and L respectively; the slot width, slot depth and the offset from the slot bottom to the slot center of the left second auxiliary slot 2 are represented by parameters C, G and J respectively; the slot width, slot depth and the offset from the slot bottom to the slot center of the right second auxiliary slot 3 are represented by parameters D, H and K respectively. At least one item of the parameter set [A, E, I] of the left auxiliary groove 1 is different from the parameter set [B, F, L] of the right auxiliary groove 4, and at least one item of the parameter set [C, G, J] of the left second auxiliary groove 2 is different from the parameter set [D, H, K] of the right second auxiliary groove 3; the groove width range of the first pair of asymmetric auxiliary grooves and the second pair of asymmetric auxiliary grooves is 2-5mm, and the groove depth of the first pair of asymmetric auxiliary grooves and the second pair of asymmetric auxiliary grooves does not exceed 0.5mm.

[0028] The first layer of magnetic steel units 8 are symmetrically arranged on both sides of the magnetic pole d axis, and the second layer of magnetic steel units 7 are symmetrically arranged on both sides of the magnetic pole d axis. The first layer of magnetic steel units 8 and the second layer of magnetic steel units 7 are both composed of two magnetic steel slots 5 symmetrically distributed on both sides of the magnetic pole d axis in a "V" shape and magnetic steel embedded in the magnetic steel slots 5. The first layer of magnetic steel units 8 are located outside the second layer of magnetic steel units 7. When magnetic steel is embedded in the magnetic steel units, a q-axis magnetic circuit channel is formed between adjacent magnetic steel units, and a magnetic isolation bridge is formed between each magnetic steel unit and the outer peripheral wall of the rotor punching 6.

[0029] The first pair of asymmetric auxiliary slots are located between the magnetic isolation bridge of the first layer of magnetic steel unit 8 and the magnetic isolation bridge of the second layer of magnetic steel unit 7. The positioning point angle of the second pair of asymmetric rotor auxiliary slots is smaller than the magnetic pole arc angle of the second layer of magnetic steel unit 7, thereby preventing the auxiliary slots from being arranged on the magnetic isolation bridge, which may lead to a reduction in the rotor structure strength.

[0030] In a second aspect, the present invention further discloses a rotor core, which is formed by stacking the above-mentioned multiple rotor punchings with an asymmetric auxiliary slot structure.

[0031] In a third aspect, the present invention further discloses a permanent magnet motor, which includes the above-mentioned rotor core. This embodiment uses an existing 8-pole 48-slot built-in permanent magnet motor with a symmetrical auxiliary slot structure as a comparative example, and conducts an experimental comparison with the built-in permanent magnet motor of the present application with an asymmetrical auxiliary slot structure. The comparison motor has the same number of auxiliary slots, slot width and slot depth as the motor of the present application, and the other motor parameters and operating environment parameters are also the same. Then, the output parameters of the two motors are compared and analyzed, and the comparison structure is shown in the following table:

[0032] Table 1:

[0033] parameter Comparison motor This application motor unit Output torque 304.38 304.11 Nm Torque ripple peak-to-peak 19.50 16.65 Nm Torque ripple 6.41 5.47 ％ Cogging torque 1.53 0.99 Nm 0th order in space and 24th order in time 2.43 2.29 Nm Space 0th order Time 48th order Electromagnetic force 1.75 1.62 Nm

[0034] Combined with Figure 3 The cogging torque waveform comparison of the two motors with asymmetric auxiliary slots and symmetric auxiliary slots, and Figure 4 From the output torque waveform comparison diagram of the two motors with asymmetric auxiliary slots and symmetric auxiliary slots, it can be seen that the cogging torque and torque pulsation of the rotor core with an asymmetric rotor auxiliary slot structure of this embodiment are lower than those of the existing built-in V-type permanent magnet rotor. It can be seen that the rotor of this embodiment can effectively reduce the cogging torque and torque fluctuation.

[0035] The present application provides asymmetric auxiliary slots on the surface of the rotor core poles, which can effectively improve the non-sinusoidal distribution of the air gap magnetic field of the permanent magnet motor, reduce the harmonic content of the air gap magnetic density, thereby reducing the cogging torque, torque pulsation and radial electromagnetic force, reduce the electromagnetic vibration and noise of the motor, meet the driving requirements of electric vehicles, and achieve the characteristics of high power density, low noise, low torque fluctuation, wide speed regulation, small size, light weight and smooth operation of the motor.

[0036] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A rotor punching with an asymmetric auxiliary slot structure, characterized in that: The invention comprises a plurality of unit parts, wherein the unit parts comprise a first pair of asymmetric auxiliary grooves and a second pair of asymmetric auxiliary grooves: The first pair of asymmetric auxiliary slots comprises a left auxiliary slot (1) and a right auxiliary slot (4); the left auxiliary slot (1) and the right auxiliary slot (4) are respectively located on both sides of the magnetic pole d axis; the second pair of asymmetric auxiliary slots comprises a left second auxiliary slot (2) and a right second auxiliary slot (3); the left second auxiliary slot (2) and the right second auxiliary slot (3) are respectively located on both sides of the magnetic pole d axis; The positioning point angles of the left auxiliary groove (1) and the right auxiliary groove (4) are the same; the positioning point angles of the left second auxiliary groove (2) and the right second auxiliary groove (3) are the same; wherein the positioning point angle is the angle between the line connecting the midpoint of the auxiliary groove opening and the center of the rotor punching (6) and the magnetic pole d axis; At least one of the three parameters of the slot width, slot depth and the offset from the slot bottom to the slot center between the left auxiliary slot (1) and the right auxiliary slot (4) is different; at least one of the three parameters of the slot width, slot depth and the offset from the slot bottom to the slot center between the left second auxiliary slot (2) and the right second auxiliary slot (3) is different.

2. The rotor punching sheet with an asymmetric auxiliary slot structure according to claim 1, characterized in that: It also comprises a first layer of magnetic steel units (8) and a second layer of magnetic steel units (7), wherein the first layer of magnetic steel units (8) are symmetrically arranged on both sides of the magnetic pole d axis, and the second layer of magnetic steel units (7) are symmetrically arranged on both sides of the magnetic pole d axis, and the first layer of magnetic steel units (8) are located outside the second layer of magnetic steel units (7).

3. The rotor punching sheet with an asymmetric auxiliary slot structure according to claim 2, characterized in that: The first pair of asymmetric auxiliary slots are located between the magnetic isolation bridge of the first layer of magnetic steel units (8) and the magnetic isolation bridge of the second layer of magnetic steel units (7), and the positioning point angle of the second pair of asymmetric rotor auxiliary slots is smaller than the magnetic pole arc angle of the second layer of magnetic steel units (7).

4. A rotor core, characterized in that: The invention is formed by stacking a plurality of rotor punching sheets (6) with an asymmetric auxiliary slot structure as described in any one of claims 1 to 3.

5. A permanent magnet motor, characterized in that: Comprising the rotor core as claimed in claim 4.

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