A permanent magnet alternator rotor

Abstract

The present invention provides a permanent magnet alternator rotor, comprising a rotor body formed by stacking a plurality of punching sheets, wherein the shape formed by the projection of the outer edge of the punching sheet comprises: an even-numbered base curved edge, an even-numbered convex curved edge, and a connecting curved edge, wherein the convex curved edge is connected to the base curved edge by the connecting curved edge; wherein, in a rectangular coordinate system with the projection point of the central axis as the origin, the convex curved edge is arranged between two base curved edges, and the even-numbered base curved edges and the convex curved edges are symmetrical about the X-axis and the Y-axis; the connecting curved edge comprises two connecting arcs with different curvatures, and the centers of the two connecting arcs deviate from the projection point of the central axis and are respectively located on both sides of the central axis. The present invention proposes a permanent magnet alternator rotor, which overcomes the defects of reduced and unstable motor output power while reducing the total voltage harmonic distortion rate, thereby not only reducing the total voltage harmonic distortion rate, but also ensuring stable power output of the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of generators, and in particular to a permanent magnet alternating current generator rotor. Background Art

[0002] The advantages of high efficiency and small size of permanent magnet motors have attracted widespread attention from various industries. The size and waveform of the no-load induced voltage of the permanent magnet motor have an important impact on the motor's operating efficiency, vibration noise, torque fluctuation, etc. When used as a generator connected to the grid or operating independently, the induced voltage waveform is required to be higher. Table 1 shows the upper limits of the total harmonic voltage distortion rate and each harmonic voltage content rate of the public power grid at different voltage levels specified in the national standard GB / T14549--93 "Power Quality-Public Power Grid Harmonics", and the total harmonic distortion rate of the no-load induced voltage of the permanent magnet motor is generally greater than the regulation. In order to reduce the total voltage harmonic distortion rate, the main methods currently used mainly include:

[0003] (1) A fractional slot winding structure with similar number of poles and slots is used. This structure is often used in large hydroelectric generators and low-speed permanent magnet motors, but is rarely used in situations where the speed is 3000 rpm and 1500 rpm.

[0004] (2) Use skewed slots or skewed poles. This method can effectively reduce the total harmonic distortion rate of the no-load induced voltage of the permanent magnet motor and improve the sinusoidal nature of the voltage waveform. However, the motor manufacturing process is relatively complex, and while reducing the harmonic voltage, the fundamental voltage is also reduced. In addition, for large motors, skewed slots and skewed poles will bring about a large axial force, which is not conducive to motor operation.

[0005] (3) Optimize the rotor structure. At present, conventional built-in permanent magnet motors usually use additional Figure 1 to Figure 4 structure. Figures 1 to 3 The sinusoidality of the no-load induced voltage is improved mainly by optimizing the angle, adding auxiliary slots on the outer circle of the rotor core, and optimizing the circumferential opening angle of the auxiliary slots. However, the corresponding measures have limited effect on reducing the total harmonic distortion rate of the no-load induced voltage waveform, and it is difficult to meet the requirements of the national standard GB / T14549-93. Figure 1 to Figure 3 Based on the patent CN 110048530 B, Figure 4 The structure shown optimizes the no-load induced voltage, thereby reducing torque fluctuations. However, after adopting this structure, the motor torque is reduced, affecting the motor power output. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a permanent magnet AC generator rotor, which solves the problem in the prior art that the motor output power is reduced and unstable after the total voltage harmonic distortion rate is reduced and the rotor structure is optimized.

[0007] According to an embodiment of the present invention, a permanent magnet alternating current generator rotor comprises a rotor body, wherein the rotor body is formed by stacking a plurality of punching sheets, a center hole is provided inside the rotor body and a center axis passing through the center hole is defined, and a rectangular coordinate system with a projection point of the center axis as the origin is defined in a plane perpendicular to the center axis; in the plane perpendicular to the center axis, the shape formed by the projection of the outer edge of the punching sheet comprises: an even number of base curved edges, an even number of convex curved edges, and a connecting curved edge, wherein the convex curved edge is connected to the base curved edge by the connecting curved edge; wherein,

[0008] In a rectangular coordinate system with the projection point of the central axis as the origin, the convex curved edge is arranged between the two base curved edges, and the even-numbered base curved edges and the convex curved edges are symmetrical about the X-axis and the Y-axis;

[0009] The connecting curved edge includes two connecting arcs with different curvatures, and the centers of the two connecting arcs deviate from the projection point of the central axis and are respectively located on both sides of the central axis.

[0010] Preferably, in a rectangular coordinate system with the projection point of the central axis as the origin, the center of the base curved edge coincides with the origin; in the two connecting arcs in the nth quadrant, the center of the connecting arc connected to the base curved edge is located in the quadrant diagonal to the nth quadrant, and the center of the connecting arc connected to the convex curved edge is located in the nth quadrant.

[0011] Preferably, the punching sheet further has an even number of mounting holes, which are arranged between the edge of the center hole and the outer edge of the punching sheet.

[0012] Preferably, the radius ratio of the two connecting arcs is between 1:1.05 and 1:1.85.

[0013] Preferably, among the even number of the mounting holes, a reinforcing rib is reserved between two adjacent mounting holes.

[0014] Preferably, the curved edge of the convex portion comprises an arc, the center of the arc is the projection point of the central axis, and a notch is constructed on the arc.

[0015] Preferably, a plurality of through holes are provided on the punching sheet.

[0016] Preferably, the through hole is a circular hole, and a plurality of the through holes are located between two of the mounting holes.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention proposes a permanent magnet AC generator rotor, which reduces the voltage harmonic total distortion rate while overcoming the defects of reduced and unstable motor output power, thereby not only reducing the voltage harmonic total distortion rate but also ensuring stable power output of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The invention discloses an existing rotor structure.

[0020] Figure 2 This is another existing rotor structure.

[0021] Figure 3 This is another existing rotor structure.

[0022] Figure 4 This is another existing rotor structure.

[0023] Figure 5 for Figure 1-Figure 4 Distribution functions of permanent magnet remanence and air gap length for four rotor structures.

[0024] Figure 6 for Figure 1-Figure 3 The induced voltage waveforms corresponding to the three rotor structures.

[0025] Figure 7 for Figure 4 The induced voltage waveform of the rotor structure.

[0026] Figure 8 This is a schematic diagram of the motor structure.

[0027] Fig. 9 The figure is a schematic structural diagram of a punching sheet according to an embodiment of the present invention.

[0028] Fig.10 It is a schematic structural diagram of a punching sheet according to another embodiment of the present invention.

[0029] Fig.11 The induced voltage waveform diagram after the punching sheets of the two embodiments of the present invention are assembled into a motor.

[0030] In the above drawings: 101, center axis; 301, center hole; 100, motor; 10, stator; 20, rotor; 30, rotor body; 31, punching sheet; 32, base curved edge; 33, convex curved edge; 34, connecting curved edge; 35, connecting arc; 35a, first connecting arc; 35b, second connecting arc 36, mounting hole; 37, through hole; 38, reinforcing rib; 40, arc; 41, notch; c1, auxiliary groove 1; c2, auxiliary groove 2. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] Table 1 shows the upper limits of the total harmonic voltage distortion rate and each harmonic voltage content rate of the public power grid at different voltage levels as specified in the national standard GB / T14549--93 "Power Quality - Public Power Grid Harmonics".

[0033]

[0034] Table 1

[0035] According to Faraday's law of electromagnetic induction, when the number of poles, slots and winding form of the permanent magnet motor are constant, the waveform of the no-load air gap flux density plays a decisive role in the no-load induced electromotive force of the permanent magnet motor. The more sinusoidal the air gap flux density is, the more sinusoidal the no-load induced electromotive force is. According to the basic law of magnetic circuit, under the condition of given permanent magnet thickness and material properties, the distribution function of the air gap flux density along the circumference can be expressed as:

[0036]

[0037] Where, μ0=4π×10 -7 H / m is the magnetic permeability in vacuum; θ is the circumferential angle; l pm (θ) is the distribution function of the permanent magnet thickness along the circumference; l g (θ) is the distribution function of the air gap length along the circumference; H pm (θ) is the distribution function of the remanent magnetism of the permanent magnet along the circumferential direction.

[0038] For a conventional permanent magnet motor, the distribution function of the residual magnetism of the magnet along the circumferential direction is pm (θ) is a rectangular wave or a step wave. pm (θ) is the permanent magnet thickness distribution function along the circumference, which is a rectangular wave or a step wave. Its waveform is similar to H pm (θ) is the same; when the slotting effect is not considered, l g (θ) is a constant along the circumferential direction.

[0039] Figure 1-Figure 3 Adding auxiliary slots 1 and 2 to the outer circumference of the rotor can only make a small adjustment to the circumferential distribution of the air gap length, and it is difficult to achieve a high degree of sinusoidal back electromotive force.

[0040] Figure 4 The sinusoidal design of the no-load induced voltage is carried out by offsetting the rotor outer circle by a certain distance H0 from the center of the shaft. Figure 1-Figure 4 The distribution function of the permanent magnet remanence and air gap length is as follows Figure 5 As shown, Figure 5 Figure (a) shows the use of the attached Figure 1 The permanent magnet remanence distribution function corresponding to the structure shown in the figure, (b) is the use of the attached Figure 2 -Attached Figure 4The permanent magnet remanence distribution function corresponding to the structure shown in the figure, (c) is the use of the attached Figure 1 Attached Figure 3 The air gap length distribution function corresponding to the structure shown in Figure (d) is the air gap length distribution function corresponding to the structure shown in Figure (d). Figure 4 The air gap length distribution function corresponding to the structure shown in FIG. (e) represents the air gap length distribution function corresponding to the structure shown in FIG. Fig. 9 and attached Figure 1 The air gap length function corresponding to the structure shown. It can be seen that the use of Figures 1 to 4 The induced emf of the structure shown has a low sinusoidality.

[0041] Figure 6 for Figures 1 to 3 The total harmonic distortion rate of the induced electromotive force waveform corresponding to the structure is 9.5%.

[0042] Figure 7 for Figure 4 The induced electromotive force waveform of the structure. Figure 7 It can be seen that due to Figure 4 The corresponding air gap length function can better adjust the permanent magnet remanence distribution function, so the waveform sinusoidality is improved, and its total harmonic distortion rate is 7.8%. Figure 4 The air gap length at the q-axis position of the structure shown is very large, which reduces the space for placing permanent magnets in the rotor, resulting in Figure 4 The fundamental wave of the induced electromotive force of the structure shown is relative to Figure 1-Figure 3 The structure shown is reduced by about 9%.

[0043] In view of this, the present invention proposes to simulate the outer circle of the rotor between the d-axis and the q-axis through multiple arcs, thereby achieving Figure 5 The air gap length distribution function shown in (e) does not reduce the space for placing the permanent magnet, but also improves the sinusoidality of the induced electromotive force.

[0044] Motor structure reference Figure 8 As shown, the motor 100 includes a stator 10 and a rotor 20. The rotor 20 can be driven by a magnetic field to rotate around a central axis 101. The stator 10 is used to generate a magnetic field to drive the rotor 20 to rotate. The stator 10 is sleeved on the outer circumference of the rotor 20, and the stator 10 and the rotor 20 have a certain air gap in the radial direction of the central axis 101.

[0045] refer to Figure 9-10As shown, an embodiment of the present invention proposes a permanent magnet AC generator rotor, including a rotor body 30, wherein the rotor body 30 is formed by stacking a plurality of punching sheets 31, wherein a center hole 301 is provided inside the rotor body 30, and an XY rectangular coordinate system with the projection point of the center axis 101 as the origin is defined in a plane perpendicular to the center axis 101; in the plane perpendicular to the center axis 101, the shape formed by the projection of the outer edge of the punching sheet 31 includes: an even-numbered base curved edge 32, an even-numbered convex curved edge 33, and a connecting curved edge 34, wherein the convex curved edge 33 is connected to the base curved edge 32 by the connecting curved edge 34; wherein,

[0046] In a rectangular coordinate system with the projection point of the central axis 101 as the origin, the convex curved edge 33 is arranged between the two base curved edges 32, and even-numbered segments of the base curved edges 32 and the convex curved edges 33 are symmetrical about the X-axis and the Y-axis;

[0047] The connecting curved edge 34 includes two connecting arcs 35 with different curvatures, namely a first connecting arc 35a and a second connecting arc 35b, and the centers of the first connecting arc 35a and the second connecting arc 35b deviate from the projection point of the central axis 101 and are respectively located on both sides of the central axis 101.

[0048] As a specific embodiment, in a rectangular coordinate system with the projection point of the central axis as the origin, the center of the base curved edge 32 coincides with the origin; in the two connecting arcs 35 in the nth quadrant, the center of the first connecting arc 35a connected to the base curved edge 32 is located in the quadrant diagonal to the nth quadrant, and the center of the second connecting arc 35b connected to the convex curved edge 33 is located in the nth quadrant. For example, in a rectangular coordinate system with the projection point of the central axis 101 as the origin, the center of the base curved edge 32 in the second quadrant coincides with the origin. The points coincide with each other; in the two connecting arcs 35 in the second quadrant, the center of the first connecting arc 35a connected to the base curved edge 32 is located in the fourth quadrant, and the center of the second connecting arc 35b connected to the convex curved edge 33 is located in the second quadrant, and the radius ratio of the first connecting arc 35a to the second connecting arc 35b is between 1:1.05 and 1:1.85; the convex curved edge 33 includes an arc 40, the center of the arc 40 is the projection point of the central axis 101, and a notch 41 is constructed on the arc 40, and the notch is V-shaped.

[0049] As a specific embodiment, see the attached Fig. 9Between the edge of the center hole 301 and the outer edge of the punching sheet 31, two groups of mounting holes 36 are opened on the punching sheet 31, each group of mounting holes 36 has two, and are distributed in two layers in the radial direction of the center axis 101, and a reinforcing rib 38 is reserved between two adjacent mounting holes 36 in each group, and a through hole 37 is also opened between the two layers of mounting holes 36, the radius of the base curved edge 32 is 75.5mm, and the radii of the first connecting arc 35a and the second connecting arc 35b are 47.7mm and 79.5mm respectively.

[0050] As a specific embodiment, see the attached Fig.10 , between the edge of the center hole 301 and the outer edge of the punching piece 31, different from the first embodiment, four groups of mounting holes 36 are opened on the punching piece 31, each group of mounting holes 36 has two, and are distributed in two layers in the radial direction of the center axis 101. In order to ensure the strength of the punching piece 31, a reinforcing rib 38 is reserved between two adjacent mounting holes 36 in each group, and a through hole 37 is also opened between the two layers of mounting holes 36. The radius of the base curved edge is 75.5 mm, and the radii of the first connecting arc 35a and the second connecting arc 35b are 49.4 mm and 72.5 mm, respectively.

[0051] In the present invention, the connecting curved edge 34 is composed of arcs with different centers and different radii. By optimizing the design of different arc segment angles and center positions, the air gap magnetic resistance is optimized, and the total harmonic distortion rate of the no-load induced voltage is reduced while ensuring that the output voltage of the motor changes very little, and the sinusoidality of the no-load induced voltage is improved. Compared with the existing induced voltage optimization technology, the total harmonic distortion rate of the no-load induced voltage under the structure of the present invention not only meets the requirements of the national standard GB / T14549-93, but also the no-load induced voltage fundamental wave value will not be reduced relative to the conventional structure with concentric outer circle. In addition, relative to the rotor outer circle concentric structure, the direct axis inductance of this structure is reduced, which increases the active power output capacity of the generator; because the rotor outer circle is a non-concentric structure, the distance from the rotor outer circle to the inner circle of the motor stator core is different on the circumference, which increases the flow rate of the air gap, which is beneficial to the heat dissipation of the motor.

[0052] The motor induced voltage waveforms of the above two specific embodiments are shown in Fig.11 , which is different from the common Figure 1-Figure 4 Compared with the motor rotor structure in Figure 6 Indicated in Figure 1-Figure 3 Inductive voltage waveforms of three rotor structures and Figure 7 Indicated Figure 4 The inductive voltage waveform of the rotor structure, the rotor inductive voltage in the present invention has better sinusoidality and more stable power output.

[0053] As a specific embodiment, the radii of the first connecting arc 35a and the second connecting arc 35b are 46.9 mm and 73.4 mm, 42.3 mm and 71.8 mm respectively.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A permanent magnet alternator rotor, comprising a rotor body, the rotor body being formed by stacking a plurality of punching sheets, the rotor body being provided with a central hole and defining a central axis passing through the central hole, a rectangular coordinate system with a projection point of the central axis as an origin being defined in a plane perpendicular to the central axis; in the plane perpendicular to the central axis, the shape formed by the projection of the outer edge of the punching sheet comprises: an even number of base curved edges, an even number of convex curved edges, and a connecting curved edge, wherein the convex curved edge and the base curved edge are connected by the connecting curved edge; wherein, In a rectangular coordinate system with the projection point of the central axis as the origin, the convex curved edge is arranged between the two base curved edges, and the even-numbered base curved edges and the convex curved edges are symmetrical about the X-axis and the Y-axis; characterized in that: The connecting curved edge includes two connected arcs with different curvatures, and the centers of the two connecting arcs deviate from the projection point of the central axis and are respectively located on both sides of the central axis; In a rectangular coordinate system with the projection point of the central axis as the origin, the center of the base curved edge coincides with the origin; in the two connecting arcs in the nth quadrant, the center of the connecting arc connected to the base curved edge is located in the quadrant diagonal to the nth quadrant, and the center of the connecting arc connected to the convex curved edge is located in the nth quadrant; The curved edge of the convex portion includes an arc, and the center of the arc is the projection point of the central axis.

2. A permanent magnet alternator rotor according to claim 1, characterized in that: The punching sheet is also provided with an even number of mounting holes, which are arranged between the edge of the center hole and the outer edge of the punching sheet.

3. A permanent magnet alternator rotor according to claim 1 or 2, characterized in that: The radius ratio of the two connecting arcs is between 1:1.05 and 1:1.

85.

4. A permanent magnet alternator rotor according to claim 1 or 2, characterized in that: The radius ratio of the two connecting arcs is between 1:1.45 and 1:1.

75.

5. A permanent magnet alternator rotor according to claim 2, characterized in that: Among the even-numbered mounting holes, a reinforcing rib is reserved between two adjacent mounting holes.

6. A permanent magnet alternator rotor according to claim 1, characterized in that: A notch is configured on the circular arc.

7. A permanent magnet alternator rotor according to claim 5, characterized in that: A plurality of through holes are provided on the punching sheet.

8. A permanent magnet alternator rotor according to claim 7, characterized in that: The through holes are circular holes, and a plurality of the through holes are located between two of the mounting holes.

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