An asymmetric rotor new energy vehicle motor based on double magnetic axis offset

Abstract

An asymmetric rotor new energy vehicle motor based on double offset of magnetic axis belongs to the field of new energy vehicle motors. It solves the problem of low motor torque density in existing new energy vehicle motors. The motor described in the present invention is provided with M groups of asymmetric double V-shaped magnetic barrier through holes along the axial direction at equal intervals along the circumference of the rotor core, and each group of asymmetric double V-shaped air magnetic barrier through holes includes two asymmetric V-shaped through holes, and the two asymmetric V-shaped through holes are stacked and arranged along the radial direction of the rotor core, and the opening directions of the two asymmetric V-shaped through holes are both toward the outside of the rotor core; the two strip holes of each asymmetric V-shaped through hole have different lengths, and a permanent magnet is arranged in each strip hole, and the permanent magnet in the shorter strip hole in each asymmetric V-shaped through hole is longer, and the permanent magnet in the longer strip hole is shorter, and each permanent magnet runs through the corresponding strip hole. The present invention is suitable for improving the torque density of the motor.

Description

Technical Field

[0001] The invention belongs to the field of motors for new energy vehicles. Background Art

[0002] In traditional round wire motors and flat wire motors, the cost of permanent magnets is the main part of the motor cost. As a non-renewable resource, the price of rare earth permanent magnet materials has been rising as they are continuously mined, which has led to a continuous increase in the production cost of motors. In order to meet the practical significance and the needs of sustainable development of new energy vehicle drive motors, in order to resolve the contradiction between high performance and high cost, it is necessary to make better use of magnetic resistance and electromagnetic torque to improve the torque density of the motor.

[0003] At present, the traditional symmetrical built-in "single V", "double V", "straight", "V+1" permanent magnet synchronous motors have the following two disadvantages. On the one hand, due to the symmetry of the motor structure, the magnitude of the reluctance torque is fixed, and the reluctance torque is not fully utilized; on the other hand, due to the fixed amount of permanent magnets, the permanent magnet flux will not change, so the magnitude of the permanent magnet torque is also fixed. These two factors lead to a low torque density of the motor. Summary of the invention

[0004] The present invention aims to solve the problem of low motor torque density in existing new energy vehicle motors, and now provides an asymmetric rotor new energy vehicle motor based on double offset of magnetic axis.

[0005] The asymmetric rotor new energy vehicle motor based on double magnetic axis offset of the present invention comprises: a stator core, a rotor core and a rotating shaft, wherein the stator core, the rotor core and the rotating shaft are coaxially connected in sequence from outside to inside; n stator teeth are evenly spaced on the end surface of the stator core, and 8 layers of hairpin windings are arranged in the stator slots between every two adjacent stator teeth; wherein n is a positive integer;

[0006] M groups of asymmetric double V-shaped magnetic barrier through holes along the axial direction are evenly spaced along the circumference of the rotor core, wherein M is a positive integer;

[0007] Each group of asymmetric double V-shaped air magnetic barrier through holes includes two asymmetric V-shaped through holes, and the two asymmetric V-shaped through holes are stacked and arranged along the radial direction of the rotor core, and the opening directions of the two asymmetric V-shaped through holes are both toward the outside of the rotor core; the two strip holes of each asymmetric V-shaped through hole have different lengths, and a permanent magnet is arranged in each strip hole, the permanent magnet in the shorter strip hole in each asymmetric V-shaped through hole is longer, and the permanent magnet in the longer strip hole is shorter, and a gap is left between each permanent magnet and the two ends of the corresponding strip hole; and each permanent magnet passes through the corresponding strip hole.

[0008] Furthermore, in the present invention, the two strip-shaped holes of each asymmetric V-shaped through hole are not connected.

[0009] Furthermore, in the present invention, the widths of the two strip-shaped holes of each asymmetric V-shaped through hole are the same.

[0010] Furthermore, in the present invention, the longer strip holes in the two asymmetric V-shaped through holes are stacked accordingly, and the shorter strip holes are stacked accordingly, and in the two strip holes stacked on one side, the length of the strip hole located on the inner side is greater than the length of the strip hole located on the outer side.

[0011] Furthermore, in the present invention, two shorter bar-shaped holes stacked on one side are respectively provided with a permanent magnet 1 and a permanent magnet 3; the centers of the permanent magnet 1 and the permanent magnet 3 coincide with the centers of the magnetic barrier holes in which they are located;

[0012] Permanent magnet 2 and permanent magnet 4 are respectively arranged in the two longer bar holes; the distance from the center of permanent magnet 2 and permanent magnet 4 to the outer end of the bar hole is greater than the distance to the inner end.

[0013] Furthermore, in the present invention, the longer strip hole of the asymmetric V-shaped through hole located on the outside is 14.5 mm long and 3.1 mm wide, and the permanent magnet four inside it is 4 mm long and 3 mm wide, and the shorter strip hole is 13 mm long and 3.1 mm wide, and the permanent magnet three inside it is 10 mm long and 3 mm wide.

[0014] Furthermore, in the present invention, the longer strip hole of the asymmetric V-shaped through hole located on the inner side is 27 mm long and 4.1 mm wide, and the permanent magnet 2 inside it is 8 mm long and 4 mm wide; the shorter strip hole is 24 mm long and 4.1 mm wide, and the permanent magnet 1 inside it is 20 mm long and 4 mm wide.

[0015] The present invention discloses an asymmetric rotor new energy vehicle motor based on a double offset of the magnetic axis. It is known that the synthetic torque of the motor is formed by adding the electromagnetic torque and the reluctance torque. The first increase of the synthetic torque in the present invention is to increase it by using the reluctance torque. The original symmetrical model is asymmetrically designed with a magnetic barrier hole (strip hole). The purpose is to make the elongated magnetic barrier hole block more magnetic lines of force than the original symmetrical magnetic barrier hole, increase the difference between the d and q axis inductances, and improve the reluctance torque. At the same time, due to the asymmetry of the magnetic barrier, the reluctance magnetic axis will be offset, so that the reluctance torque increases again at the set current angle. The second increase of the synthetic torque is to increase it by using the electromagnetic torque. Since the amount of permanent magnets remains unchanged, the permanent magnetic flux remains constant, which makes the electromagnetic torque size unchanged. Only by designing the asymmetric permanent magnets can the electromagnetic torque axis be offset, so that the electromagnetic torque becomes larger at the set current angle. Through the above two steps, the disadvantages of the electromagnetic torque and reluctance torque of traditional symmetrical motors that are not fully utilized can be solved, thereby improving the torque output capacity of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of an asymmetric rotor new energy vehicle motor based on double offset of magnetic axis according to the present invention.

[0017] Figure 2 It is a schematic diagram of the asymmetric double V-shaped magnetic barrier hole and permanent magnet structure under a single pole;

[0018] Figure 3 It is a dimension marking diagram of the asymmetric double V-shaped magnetic barrier hole and permanent magnet structure under a single pole;

[0019] Figure 4 It is a structural schematic diagram of an existing symmetrical rotor new energy vehicle motor;

[0020] Figure 5 It is a schematic diagram of the existing double V-shaped magnetic barrier hole and permanent magnet structure that is symmetrical under a single pole;

[0021] Figure 6 It is a schematic diagram of the structure of an asymmetric motor with only magnetic barrier holes;

[0022] Figure 7 It is a schematic diagram of the double V-shaped magnetic barrier holes and permanent magnet structure of an asymmetric motor with only magnetic barrier holes under a single pole;

[0023] Figure 8 Schematic diagram of the comparison between the motor reluctance torque of the original symmetric model and when only the magnetic barrier hole is asymmetric;

[0024] Fig. 9 It is a schematic diagram comparing the electromagnetic torque of the motor when only the magnetic barrier hole is asymmetric and when the magnetic barrier hole and the permanent magnet are asymmetric;

[0025] Fig.10 It is the schematic diagram of the d and q axis inductance of the original symmetric model;

[0026] Fig.11 Schematic diagram of d-axis and q-axis inductance when only the magnetic barrier hole is asymmetric;

[0027] Fig.12 It is a schematic diagram of the magnetic flux of the asymmetric permanent magnet with only the magnetic barrier hole;

[0028] Fig.13 It is a schematic diagram of the permanent magnet flux linkage when the magnetic barrier hole is asymmetric and the permanent magnet is asymmetric;

[0029] Fig.14 A comparison curve of the output torque of the asymmetric rotor new energy vehicle motor based on double magnetic axis offset according to the present invention and the output torque of the existing motor;

[0030] Fig.15This is a rotor stress cloud diagram of the asymmetric rotor new energy vehicle motor based on double magnetic axis offset described in the present invention at 1.2 times the maximum speed. DETAILED DESCRIPTION

[0031] The following will be combined with the accompanying 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, rather than 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 belong to the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0032] Specific implementation method 1: refer to Figures 1 to 15 Specifically describing this embodiment, the asymmetric rotor new energy vehicle motor based on double magnetic axis offset described in this embodiment comprises: a stator core 1, a rotor core 3 and a rotating shaft 5, wherein the stator core 1, the rotor core 3 and the rotating shaft 5 are coaxially connected in sequence from the outside to the inside; n stator teeth 6 are evenly spaced on the end surface of the stator core 1, and 8 layers of hairpin windings 2 are arranged in the stator slots between every two adjacent stator teeth 6; wherein n is a positive integer;

[0033] M groups of asymmetric double V-shaped air magnetic barrier holes (4) along the axial direction are evenly spaced along the circumference of the rotor core 3, wherein M is a positive integer; each group of asymmetric double V-shaped air magnetic barrier holes 4 includes two asymmetric V-shaped holes, the two asymmetric V-shaped holes are stacked and arranged along the radial direction of the rotor core 3, and the opening directions of the two asymmetric V-shaped holes are both toward the outside of the rotor core 3; the two bar holes of each asymmetric V-shaped hole have different lengths, and a permanent magnet is arranged in each bar hole, the permanent magnet in the shorter bar hole in each asymmetric V-shaped hole is longer, and the permanent magnet in the longer bar hole is shorter, and a gap is left between each permanent magnet and the two ends of the corresponding bar hole; and each permanent magnet passes through the corresponding bar hole.

[0034] Furthermore, in this embodiment, the two strip-shaped holes of each asymmetric V-shaped through hole are not connected.

[0035] Furthermore, in this embodiment, the widths of the two strip-shaped holes of each asymmetric V-shaped through hole are the same.

[0036] Furthermore, in this embodiment, the longer strip holes in the two asymmetric V-shaped through holes are stacked accordingly, and the shorter strip holes are stacked accordingly, and in the two strip holes stacked on one side, the length of the strip hole on the inner side is greater than the length of the strip hole on the outer side.

[0037] Furthermore, in this embodiment, two shorter bar-shaped holes stacked on one side are respectively provided with a permanent magnet 1 41 and a permanent magnet 3 43; the centers of the permanent magnet 1 41 and the permanent magnet 3 43 coincide with the centers of the magnetic barrier holes in which they are located;

[0038] A second permanent magnet 42 and a fourth permanent magnet 44 are respectively disposed in the two longer bar-shaped holes; the distance from the center of the second permanent magnet 42 and the fourth permanent magnet 44 to the outer end of the bar-shaped hole is greater than the distance to the inner end.

[0039] In this embodiment, the centers of permanent magnet 2 42 and permanent magnet 44 correspond to the centers of permanent magnet 1 41 and permanent magnet 3 43. Therefore, the centers of permanent magnet 2 42 and permanent magnet 44 correspond to the center of the magnetic barrier hole on the shorter side, and do not overlap with the center of the magnetic barrier hole on the longer side.

[0040] Furthermore, in the present embodiment, the longer strip hole of the asymmetric V-shaped through hole located on the outside is 14.5 mm long and 3.1 mm wide, and the permanent magnet four 44 inside it is 4 mm long and 3 mm wide, and the shorter strip hole is 13 mm long and 3.1 mm wide, and the permanent magnet three 43 inside it is 10 mm long and 3 mm wide.

[0041] Furthermore, in the present embodiment, the longer strip hole of the asymmetric V-shaped through hole located on the inner side is 27 mm long and 4.1 mm wide, and the permanent magnet 42 inside it is 8 mm long and 4 mm wide; the shorter strip hole is 24 mm long and 4.1 mm wide, and the permanent magnet 1 41 inside it is 20 mm long and 4 mm wide.

[0042] In this embodiment, refer to Figures 1 to 15 Specifically describing this embodiment, the asymmetric rotor new energy vehicle motor based on double magnetic axis offset described in this embodiment includes: Figure 1 The stator core, rotor core and coaxial nested shaft are arranged on the stator core, and there are 48 stator teeth. The hairpin winding has a higher slot fill rate than the traditional round wire winding. The flat wire motor can take a relatively small slot size, which can effectively reduce the tooth torque. Therefore, 8 layers of hairpin windings are placed inside each stator tooth, and three-phase alternating current is passed through the winding to generate the armature magnetic field.

[0043] There are four air magnetic barrier holes under each pole of the rotor core. The air magnetic barrier holes are axial through holes with a "double V-shaped" radial cross section. Figure 2 From the inner circle of the rotor to the outer circle of the rotor, there are two longer strip holes of the asymmetric double V-shaped air magnetic barrier through hole 4, and then from the outside to the inside through two shorter strip holes. The magnet is a rare earth permanent magnet, and each permanent magnet has a magnetic steel groove at the corner to facilitate the placement of the permanent magnet.

[0044] The air magnetic barrier hole under each pole is a non-axisymmetric structure. The asymmetry of the air magnetic barrier hole makes the four ends of the "double V-shaped" structure have different distances from the outer circle of the rotor. The purpose of this design is to increase the size of the reluctance torque and to move the reluctance torque axis through the asymmetric distribution of the magnetic barrier holes so that the reluctance torque can be increased again at a set angle. The rare earth permanent magnets embedded in the air magnetic barrier hole under each pole are also asymmetric structures. The design purpose is to move the electromagnetic torque axis through the asymmetric distribution of permanent magnets so that the electromagnetic torque can be increased at a set angle.

[0045] The magnetization directions of the permanent magnets 41, 42, 43 and 44 are respectively perpendicular to the length direction of the corresponding strip holes, and the sum of the magnetization angles of the permanent magnets 41 and 42 and the angle between the two strip holes of the inner V-shaped hole is maintained at 180 degrees, and the sum of the magnetization angles of the permanent magnets 43 and 44 and the angle between the two strip holes of the outer V-shaped hole is maintained at 180 degrees. Figure 4 , Figure 5 Because of the traditional symmetrical structure, both the permanent magnet torque and the reluctance torque are not fully utilized. Figure 6 , Figure 7 It is an asymmetric model with only magnetic barrier holes. It is a torque model that uses magnetic resistance torque to increase torque for the first time. The d and q axis inductance values ​​of this model and the original symmetric model are Fig.10 and Fig.11 As shown, the change in the magnitude of the reluctance torque and the magnetic axis offset are determined by Figure 8 shown. Figure 1 , Figure 2 The present invention is a model of magnetic barrier hole asymmetry and permanent magnet asymmetry, which is a model that uses electromagnetic torque to increase torque for the second time. The size of the permanent magnet flux linkage of this model and the model of magnetic barrier hole asymmetry only is determined by Fig.12 and Fig.13 As shown, the change in the magnitude of the electromagnetic torque and the magnetic axis offset are given by Fig. 9 shown.

[0046] The original model is a conventional left-right symmetrical model ( Figure 4 and Figure 5 ), the original model average torque ( Fig.14 ) is 150.35Nm, and the first step of optimization is to stretch the magnetic barrier ( Figure 6 and Figure 7 ) makes the magnetic resistance axis shift to increase the synthetic torque. The relationship between the length of the outer magnetic barrier and the inner magnetic barrier on the right and the synthetic torque is shown in Table 1. It can be seen from Table 1 that the torque increases slowly after group D, so the best elongation length interval is in the (DF) interval, but the rotor stress of group E and group F exceeds the yield strength of the material 410Mpa, so group D is the best choice. The average torque of group D model ( Fig.14 ) is 158.79Nm. The second step of optimization is carried out based on group D. By changing the amount of permanent magnets on the left and right parts ( Figure 1 and2 ) makes the electromagnetic axis shift to increase the synthetic torque for the second time. Due to the limitation of the magnetic barrier length, the longest permanent magnet is 20mm (as shown in Table 2). It can be seen that the optimal structure is the D+f combination. The average torque of the D+f group model ( Fig.14 ) is 166.64Nm. According to the rotor dynamics simulation of the Workbench software in ANSYS, at room temperature, when the maximum speed is 1.2 times (14400rpm), the maximum rotor stress is 400.52Mpa ( Fig.15 ), which is less than the maximum yield strength of silicon steel sheet 410Mpa, the rotor will not break and the structure meets the stress requirements.

[0047] Table 1 Relationship between the length of the outer and inner magnetic barriers and the synthetic torque

[0048]

[0049] Table 2 Relationship between the reduced length of the outer permanent magnet and the inner permanent magnet and the synthetic torque

[0050]

[0051]

[0052] The present embodiment proposes an asymmetric rotor new energy vehicle motor based on double magnetic axis offset. Since the synthetic torque of the motor is formed by the addition of electromagnetic torque and magnetic resistance torque, the first increase of synthetic torque in the present invention is to increase it by using magnetic resistance torque. The original symmetrical model is designed with asymmetric magnetic barrier holes. The purpose is to make the elongated magnetic barrier holes block more magnetic lines of force than the original symmetrical magnetic barrier holes, thereby increasing the d- and q-axis inductance difference ( Fig.10 and Fig.11 ), which can improve the reluctance torque. At the same time, the asymmetry of the magnetic barrier causes the reluctance magnetic axis to shift ( Figure 8 ), so that the reluctance torque increases again at the set current angle. The second increase in the synthetic torque is achieved by using the electromagnetic torque. Since the amount of permanent magnets remains unchanged, the permanent magnet flux remains constant ( Fig.12 and Fig.13 ), which makes the electromagnetic torque size unchanged. The only way to change the electromagnetic torque axis is to design an asymmetric permanent magnet ( Fig. 9 ), so that the electromagnetic torque becomes larger at the set angle. Through the above two steps, the torque output capacity of the motor can be improved, so that the current provided by the motor at the same torque level becomes smaller, the current density is reduced, and then the copper loss of the winding is reduced, and the motor efficiency is improved.

[0053] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. An asymmetric rotor new energy vehicle motor based on double magnetic axis offset, characterized in that: include: A stator core (1), a rotor core (3) and a rotating shaft (5), wherein the stator core (1), the rotor core (3) and the rotating shaft (5) are coaxially connected in sequence from the outside to the inside; n stator teeth (6) are arranged at equal intervals on the end surface of the stator core (1), and eight layers of hairpin windings (2) are arranged in the stator slots between every two adjacent stator teeth (6); wherein n is a positive integer; M groups of asymmetric double V-shaped air magnetic barrier through holes (4) are arranged at equal intervals along the circumference of the rotor core (3), wherein M is a positive integer; each group of asymmetric double V-shaped air magnetic barrier through holes (4) comprises two asymmetric V-shaped through holes, the two asymmetric V-shaped through holes are stacked and arranged along the radial direction of the rotor core (3), and the opening directions of the two asymmetric V-shaped through holes are both toward the outside of the rotor core (3); the two strip holes of each asymmetric V-shaped through hole have different lengths, and a permanent magnet is arranged in each strip hole, the permanent magnet in the shorter strip hole in each asymmetric V-shaped through hole is longer, and the permanent magnet in the longer strip hole is shorter, and a gap is left between each permanent magnet and the two ends of the corresponding strip hole; and each permanent magnet passes through the corresponding strip hole; A permanent magnet 1 (41) and a permanent magnet 3 (43) are respectively arranged in two shorter bar holes stacked on one side; the centers of the permanent magnet 1 (41) and the permanent magnet 3 (43) coincide with the centers of the magnetic barrier holes where they are located; a permanent magnet 2 (42) and a permanent magnet 4 (44) are respectively arranged in two longer bar holes; the distance from the centers of the permanent magnet 2 (42) and the permanent magnet 4 (44) to the outer ends of the bar holes where they are located is greater than the distance from the centers of the permanent magnet 2 (42) and the permanent magnet 4 (44) to the inner ends; the permanent magnets The magnetization directions of permanent magnet one (41), permanent magnet two (42), permanent magnet three (43) and permanent magnet four (44) are respectively perpendicular to the length direction of the corresponding strip hole, and the sum of the magnetization angles of permanent magnet one (41) and permanent magnet two (42) and the angle between the two strip holes located on the inner side of the V-shaped hole is maintained at 180 degrees, and the sum of the magnetization angles of permanent magnet three (43) and permanent magnet four (44) and the angle between the two strip holes located on the outer side of the V-shaped hole is maintained at 180 degrees; The air magnetic barrier hole under each pole is a non-axisymmetric structure. The asymmetry of the air magnetic barrier hole makes the four ends of the opening of the "double V-shaped" structure have different distances from the outer circle of the rotor.

2. The asymmetric rotor new energy vehicle motor based on double magnetic axis offset according to claim 1 is characterized in that: The two strip holes of each asymmetric V-shaped through hole are not connected.

3. The asymmetric rotor new energy vehicle motor based on double magnetic axis offset according to claim 1 is characterized in that: The two strip holes of each asymmetric V-shaped through hole have the same width.

4. The asymmetric rotor new energy vehicle motor based on double magnetic axis offset according to claim 1 or 2, characterized in that: The longer strip holes in the two asymmetric V-shaped through holes are stacked accordingly, and the shorter strip holes are stacked accordingly, and in the two strip holes stacked on one side, the length of the strip hole located on the inner side is greater than the length of the strip hole located on the outer side.

5. The asymmetric rotor new energy vehicle motor based on double magnetic axis offset according to claim 3 is characterized in that: The longer strip hole of the asymmetric V-shaped through hole located on the outside is 14.5 mm long and 3.1 mm wide, and the permanent magnet four (44) inside it is 4 mm long and 3 mm wide. The shorter strip hole is 13 mm long and 3.1 mm wide, and the permanent magnet three (43) inside it is 10 mm long and 3 mm wide.

6. The asymmetric rotor new energy vehicle motor based on double magnetic axis offset according to claim 5 is characterized in that: The longer strip hole of the asymmetric V-shaped through hole located on the inner side is 27 mm long and 4.1 mm wide, and the second permanent magnet (42) inside it is 8 mm long and 4 mm wide; the shorter strip hole is 24 mm long and 4.1 mm wide, and the first permanent magnet (41) inside it is 20 mm long and 4 mm wide.

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