Outer rotor switch reluctance motor

Abstract

The invention relates to the technical field of motors, in particular to an outer rotor switched reluctance motor which comprises a rotor, a stator, a three-phase winding and a permanent magnet, the rotor is coaxially nested on the outer side of the stator, the rotor is of a salient pole structure and comprises rotor poles and a magnetic shield, and the magnetic shield is in a cylindrical shape formed by enclosing a plurality of modules. A plurality of rotor poles are uniformly connected to the inner surface of the magnetic shield in the circumferential direction of the cylinder, the stator is of a salient pole structure and comprises stator poles and a stator yoke, a plurality of stator poles are uniformly arranged on the outer side of the stator yoke, a winding groove is formed between every two adjacent stator poles, and the three-phase winding is embedded in the winding groove. And the permanent magnet is arranged at the notch of the winding groove and is positioned on the outer side of the three-phase winding. According to the invention, the structure of the block outer rotor, the trapezoidal air gap and the integral pitch winding is adopted, and the permanent magnets are installed at the winding notches for auxiliary excitation, so that the output torque density and efficiency of the switched reluctance motor are greatly improved, and the problem that the output torque density and efficiency of a traditional switched reluctance motor are low is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to an outer rotor switched reluctance motor. Background Art

[0002] The switched reluctance motor usually adopts a double-salient pole structure, and its winding is only placed on the stator. There is no winding or permanent magnet on the rotor. These structural features make it simple, low cost, high reliability, strong fault tolerance, and wide speed regulation range. Based on the above advantages, the switched reluctance motor has broad application prospects in high-end equipment such as electric vehicles and aerospace, but the torque density and efficiency of traditional switched reluctance motors are slightly lower than those of other types of motors, which limits its further application in high-end equipment.

[0003] In order to improve the output torque density and efficiency of the switched reluctance motor, domestic and foreign scholars have carried out a lot of research work on the switched reluctance motor body. Among them, some scholars have optimized the size based on the traditional switched reluctance motor structure, and some scholars have proposed a new switched reluctance motor structure, including block stator type, block rotor type, axial flux, etc. Although these solutions can improve the performance of the switched reluctance motor, compared with other types of motors, their performance advantages are not obvious. In addition, the existing switched reluctance motor structure mostly adopts an inner rotor structure, and only adopts a single air gap structure or a single excitation method, which makes it difficult to further improve its performance. Summary of the invention

[0004] The purpose of the present invention is to provide an outer rotor switched reluctance motor, which greatly improves the output torque density and efficiency of the switched reluctance motor by adopting a segmented outer rotor, a trapezoidal air gap and a full-pitch winding structure, and installing permanent magnets in the winding slots for auxiliary excitation, thereby effectively solving the problem of low output torque density and efficiency of traditional switched reluctance motors.

[0005] To achieve the above-mentioned purpose, the present invention provides an outer rotor switched reluctance motor, which is a three-phase motor, including a rotor, a stator, a three-phase winding and a permanent magnet. The rotor is coaxially nested on the outside of the stator. The rotor is a salient pole structure including a rotor pole and a magnetic isolation sleeve. The magnetic isolation sleeve is surrounded by a plurality of modules to form a cylindrical shape. A plurality of rotor poles are evenly connected to the inner surface of the magnetic isolation sleeve along the circumference of the cylinder. The stator is a salient pole structure including a stator pole and a stator yoke. A plurality of stator poles are evenly arranged on the outside of the stator yoke. A winding slot is formed between two adjacent stator poles. The three-phase winding is embedded in the winding slot. The permanent magnet is arranged at the notch of the winding slot and is located on the outside of the three-phase winding.

[0006] Preferably, the number of stator poles of the three-phase motor is 6m, and the number of rotor poles is 4m, where m is an integer greater than or equal to 1.

[0007] Preferably, the module is an arc-shaped structure, one side of the module is provided with an arc-shaped protrusion, the other side of the module is provided with an arc-shaped groove, and the arc-shaped protrusions and arc-shaped grooves of two adjacent modules are plug-connected.

[0008] Preferably, a mounting groove is provided on the inner surface of the magnetic isolation sleeve, and a mounting protrusion is provided on the rotor pole, and the mounting protrusion is plug-connected with the mounting groove.

[0009] Preferably, the inner surface of the rotor pole and the outer surface of the stator pole are both provided with a trapezoidal concave-convex structure, and the concave-convex structure of the rotor pole and the concave-convex structure of the stator pole are gap-matched to form a trapezoidal air gap.

[0010] Preferably, the three-phase winding is pulse powered, the three-phase winding is a full-pitch winding, and each phase winding is composed of m winding coils.

[0011] More preferably, when m is equal to 1, each phase winding is composed of one winding coil, and when m is greater than or equal to 2, the connection method of the m winding coils of each phase winding needs to be completely the same.

[0012] Preferably, three stator poles are inserted in each winding coil, the coil edges on both sides of the winding coil are embedded in the winding slots, and the currents of the coil edges in two adjacent winding slots flow in opposite directions.

[0013] Preferably, two ends of the permanent magnet are respectively against the stator poles, and the axial length of the permanent magnet is the same as the stack length of the stator.

[0014] Preferably, the permanent magnet is tangentially magnetized, and the direction of the magnetic field generated by the permanent magnet in the stator is opposite to the direction of the magnetic field generated by the coil side arranged in the same slot in the stator.

[0015] Beneficial effects of the present invention:

[0016] (1) The present invention adopts an outer rotor switched reluctance motor of the above structure. By adopting a block rotor structure, the magnetic flux generated by the winding coil can only pass through two adjacent stator poles and rotor blocks to form a closed magnetic circuit, which greatly shortens the length of the magnetic circuit, not only increases the magnetic flux utilization rate, but also reduces the core loss, thereby improving the output torque and efficiency of the motor.

[0017] (2) The present invention adopts an outer rotor switched reluctance motor of the above structure, and by placing permanent magnets in the stator slots for auxiliary excitation, the air gap flux density of the motor when loaded is greatly increased, thereby improving the output torque and overload capacity of the motor.

[0018] (3) The present invention adopts an outer rotor switched reluctance motor with the above structure, which increases the alignment area of ​​the stator and rotor poles in the alignment position by adopting a trapezoidal air gap, reduces the air gap magnetic resistance, increases the air gap magnetic flux density and magnetic flux utilization, and thus increases the output torque of the motor.

[0019] (4) The present invention adopts an outer rotor switched reluctance motor of the above structure. By adopting an outer rotor structure, the stator is placed on the inside, the outer diameter of the rotor is increased, and the end length of the full-pitch winding is reduced, which not only improves the output torque density, but also reduces the copper consumption and winding resistance of the motor, thereby reducing the copper loss of the motor and improving the operating efficiency of the motor.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the overall structure of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention;

[0022] Figure 2 is a cross-sectional schematic diagram of an outer rotor switched reluctance motor according to embodiment 1 of the present invention;

[0023] Figure 3 is a schematic diagram of a rotor structure of an outer rotor switched reluctance motor according to embodiment 1 of the present invention;

[0024] Figure 4 is a schematic diagram of a stator structure of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention;

[0025] Figure 5 is a schematic diagram of a stator structure of an outer rotor switched reluctance motor without showing a permanent magnet in Embodiment 1 of the present invention;

[0026] Figure 6 is a schematic diagram of a winding coil of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention;

[0027] Figure 7 Schematic diagram of an air gap structure of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention;

[0028] Figure 8 Schematic diagram of the winding and permanent magnet polarity distribution of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention;

[0029] Fig. 9 is a schematic diagram of a no-load magnetic flux path of an outer rotor switched reluctance motor according to embodiment 1 of the present invention;

[0030] Fig.10 Schematic diagram of a load magnetic flux path of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention (Phase A is turned on);

[0031] Fig.11 This is a schematic diagram of the overall structure of an outer rotor switched reluctance motor according to Embodiment 2 of the present invention;

[0032] Fig.12Schematic diagram of the winding and permanent magnet polarity distribution of an outer rotor switched reluctance motor according to Embodiment 2 of the present invention;

[0033] Fig.13 is a schematic diagram of a no-load magnetic flux path of an outer rotor switched reluctance motor according to embodiment 2 of the present invention;

[0034] Fig.14 It is a schematic diagram of a load magnetic flux path of an outer rotor switched reluctance motor according to embodiment 2 of the present invention.

[0035] Reference numerals:

[0036] 1. Rotor; 11. Rotor pole; 12. Magnetic isolation sleeve; 121. Module; 122. Arc-shaped protrusion; 123. Arc-shaped groove; 13. Mounting slot; 14. Mounting protrusion; 2. Stator; 21. Stator pole; 22. Stator yoke; 3. Winding coil; 31. Coil edge; 4. Permanent magnet; 5. Concave-convex structure; 6. Trapezoidal air gap. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with the accompanying drawings and embodiments. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs. The above-mentioned features or features mentioned in the specific examples mentioned in the present invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0038] An outer rotor switched reluctance motor provided by the present invention is a three-phase motor, wherein the number of stator poles 21 and the number of rotor poles 11 are matched according to the relationship of 6m / 4m, the number of stator poles 21 is 6m, the number of rotor poles 11 is 4m, and m is an integer greater than or equal to 1. When m=1, the number of stator poles 21 is 6, and the number of rotor poles 11 is 4; when m=2, the number of stator poles 21 is 12, and the number of rotor poles 11 is 8, and so on.

[0039] Example 1

[0040] The value of m is equal to 1, so the number of stator poles is 21, which is 6, the number of rotor poles is 11, which is 4, and the number of permanent magnets is 4, which is 6.

[0041] Figure 1 Schematic diagram of the overall structure of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention. Figure 1As shown, the present invention provides an outer rotor switched reluctance motor, which is a three-phase motor, including a rotor 1, a stator 2, a three-phase winding and a permanent magnet 4. The rotor 1 is coaxially nested on the outside of the stator 2. This structure can increase the outer diameter of the rotor 1, so that the motor can output a larger torque under the same volume, thereby improving the output torque density of the motor and meeting more high-load demand scenarios. In addition, the rotor 1 can be directly connected to the driven element to achieve direct drive, reduce intermediate transmission components, reduce the useless space between the motor and the equipment, and avoid the energy loss caused by friction and vibration of the transmission components in indirect drive, thereby improving the driving efficiency of the entire motor system.

[0042] Figure 2 is a cross-sectional schematic diagram of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention, Figure 3 Schematic diagram of a rotor structure of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention. Figure 2 and Figure 3 As shown, the rotor 1 is a salient pole structure including a rotor pole 11 and a magnetic isolation sleeve 12. The magnetic isolation sleeve 12 is surrounded by a plurality of modules 121 to form a cylindrical shape. The module 121 is an arc-shaped structure. An arc-shaped protrusion 122 is provided on one side of the module 121, and an arc-shaped groove 123 is provided on the other side of the module 121. The arc-shaped protrusions 122 of two adjacent modules 121 are plug-connected with the arc-shaped grooves 123. By modularizing the magnetic isolation sleeve 12, the problem that the stator 2 and the rotor 1 cannot be assembled according to the traditional assembly method due to the introduction of the trapezoidal air gap 6 is solved. Four rotor poles 11 of the same size and shape are evenly connected to the inner surface of the magnetic isolation sleeve 12 along the cylindrical circumference. The inner surface of the magnetic isolation sleeve 12 is provided with a mounting groove 13. The rotor pole 11 is provided with a mounting protrusion 14. The mounting protrusion 14 is plug-connected with the mounting groove 13, which improves the accuracy of the installation position of the rotor pole 11 and facilitates the installation and disassembly of the rotor pole 11, bringing great convenience to the production and maintenance of the motor.

[0043] Figure 4 is a schematic diagram of a stator structure of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention, Figure 7 Schematic diagram of an air gap structure of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention. Figure 4 , Figure 7As shown, the stator 2 is a salient pole structure including a stator pole 21 and a stator yoke 22, and six stator poles 21 of the same size and shape are evenly arranged on the outside of the stator yoke 22. The inner surface of the rotor pole 11 and the outer surface of the stator pole 21 are both provided with a trapezoidal concave-convex structure 5, and the concave-convex structure 5 can be obtained by machining methods such as laser cutting or wire cutting. The concave-convex structure 5 of the rotor pole 11 and the concave-convex structure 5 of the stator pole 21 are gap-matched to form a trapezoidal air gap 6. The motor adopts a trapezoidal air gap 6, which increases the overlapping area of ​​the stator pole 21 and the rotor pole 11 in the aligned position. Without changing the outer diameter, stack length, and air gap length of the motor, the magnetic resistance of the air gap can be reduced, the magnetic flux density and magnetic flux utilization of the air gap can be increased, and the output torque density and efficiency of the motor can be effectively improved.

[0044] Figure 5 is a schematic diagram of a stator structure of an outer rotor switched reluctance motor without showing a permanent magnet in Embodiment 1 of the present invention, Figure 6 is a schematic diagram of a winding coil of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention, Figure 8 Schematic diagram of the winding and permanent magnet polarity distribution of an outer rotor switched reluctance motor according to Embodiment 1 of the present invention, Figure 1 , Figure 5 , Figure 6 and Figure 8 As shown, a winding slot is formed between two adjacent stator poles 21, and the three-phase winding is embedded in the winding slot. The three-phase winding adopts pulse power supply, and each phase winding is composed of a winding coil 3. The coil edges 31 on both sides of the winding coil 3 are embedded in the winding slot, and the current flow direction of the coil edges 31 in two adjacent winding slots is opposite. The three-phase winding is a full-pitch winding, and the pitch of each phase winding is three, that is, each winding coil 3 is interspersed with three stator poles 21. For example, one coil edge 31 of the winding coil 3 is at S 1 Winding slot, the other coil side 31 is at S 4 Winding slots. This combination of winding coils 3 can maximize the number of turns per phase, thereby ensuring that the motor has a large induced electromotive force and output power, and can also optimize the motor's magnetic circuit in conjunction with the motor structure, reduce magnetic resistance and energy loss, and improve the motor's efficiency.

[0045] like Figure 4 As shown, six permanent magnets 4 of the same size and shape are respectively arranged at the slot openings of the winding slots and are located outside the three-phase winding. The two ends of the permanent magnet 4 are respectively against the stator poles 21, and the axial length of the permanent magnet 4 is the same as the stack length of the stator 2. The permanent magnet 4 is tangentially magnetized, and the direction of the magnetic field generated by the permanent magnet 4 in the stator 2 is opposite to the direction of the magnetic field generated by the coil side 31 arranged in the same slot as the permanent magnet 4 in the stator 2.

[0046] Fig. 9This is a schematic diagram of the no-load magnetic flux path of an outer rotor switched reluctance motor according to embodiment 1 of the present invention. As shown in the figure, when no current passes through the winding coil 3, only the magnetic flux generated by the permanent magnet 4 exists in the motor. The magnetic flux generated by the permanent magnet 4 starts from the N pole, first flows into the stator yoke 22 through the stator pole 21 in contact with it, and then returns to the S pole through another stator pole 21 in contact with it, forming a closed magnetic circuit. No matter how the position of the rotor 1 changes, the magnetic flux generated by the permanent magnet 4 hardly passes through the air gap, so the cogging torque of the motor is close to zero when it is no-load.

[0047] Fig.10 It is a schematic diagram of the load magnetic flux path of an outer rotor switched reluctance motor according to embodiment 1 of the present invention (phase A is turned on). As shown in the figure, when current is passed through phase A, the magnetic flux generated by the permanent magnet 4 and the magnetic flux generated by the A-phase winding coil 3 exist in the motor at the same time. Since the direction of the magnetic flux generated by the A-phase winding coil 3 is completely opposite to the direction of the magnetic flux generated by the permanent magnet 4 in the same slot in the stator pole 21 and the stator yoke 22, they cancel each other out. Therefore, the magnetic flux generated by the permanent magnet 4 in the same slot as the A-phase winding coil 3 can only start from the N pole, pass through the stator pole 21 in contact with it, enter the trapezoidal air gap 6, pass through the rotor pole 11, and then return to the S pole from the trapezoidal air gap 6 and the other stator pole 21 in contact with it, forming a closed loop. In addition, since the direction of the magnetic flux generated by the A-phase winding coil 3 is completely opposite to the direction of the magnetic flux generated by the permanent magnet 4 in the adjacent slot in the stator pole 21, the magnetic flux generated by the permanent magnet 4 in the slot adjacent to the A-phase winding coil 3 also forms a closed loop through the trapezoidal air gap 6 and the rotor pole 11. At this time, the magnetic flux generated by the permanent magnet 4 and the magnetic flux generated by the A-phase winding coil 3 are superimposed on each other at the air gap, increasing the air gap magnetic density, greatly increasing the output torque of the motor, and thereby improving the overload capacity and operating efficiency of the motor.

[0048] Example 2

[0049] Fig.11 This is a schematic diagram of the overall structure of an outer rotor switched reluctance motor according to embodiment 2 of the present invention. As shown in the figure, the difference between this embodiment and embodiment 1 is that the value of m is equal to 2, the number of stator poles 21 of the motor is 12, the number of rotor poles 11 is 8, and the number of permanent magnets 4 is 12.

[0050] Fig.12 This is a schematic diagram of the winding and permanent magnet polarity distribution of an outer rotor switched reluctance motor according to embodiment 2 of the present invention. As shown in the figure, each phase winding is composed of two winding coils 3, and the connection method (series or parallel) of the two winding coils 3 constituting each phase winding is exactly the same to ensure the symmetry of the three-phase circuit and magnetic circuit of the motor.

[0051] Fig.13 is a schematic diagram of a no-load magnetic flux path of an outer rotor switched reluctance motor according to embodiment 2 of the present invention; Fig.14This is a schematic diagram of a load magnetic flux path of an outer rotor switched reluctance motor according to embodiment 2 of the present invention. As shown in the figure, since the number of stator poles 21 is doubled, the number of paths forming a closed magnetic circuit around each stator pole 21 is also doubled accordingly.

[0052] Therefore, the present invention adopts an outer rotor switched reluctance motor with the above structure, which can greatly improve the output torque density and efficiency of the switched reluctance motor, and solves the problem of low output torque density and efficiency of traditional switched reluctance motors.

[0053] 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 they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. An outer rotor switched reluctance motor, the motor is a three-phase motor, characterized in that: It includes a rotor, a stator, a three-phase winding and a permanent magnet. The rotor is coaxially nested on the outside of the stator. The rotor is a salient pole structure including a rotor pole and a magnetic isolation sleeve. The magnetic isolation sleeve is surrounded by a plurality of modules to form a cylindrical shape. A plurality of rotor poles are evenly connected to the inner surface of the magnetic isolation sleeve along the circumference of the cylinder. The stator is a salient pole structure including a stator pole and a stator yoke. A plurality of stator poles are evenly arranged on the outside of the stator yoke. A winding slot is formed between two adjacent stator poles. The three-phase winding is embedded in the winding slot. The permanent magnet is arranged at the notch of the winding slot and is located on the outside of the three-phase winding.

2. The outer rotor switched reluctance motor according to claim 1, characterized in that: The number of stator poles of the three-phase motor is 6m, and the number of rotor poles is 4m, where m is an integer greater than or equal to 1.

3. The outer rotor switched reluctance motor according to claim 1, characterized in that: The module is an arc-shaped structure, one side of the module is provided with an arc-shaped protrusion, the other side of the module is provided with an arc-shaped groove, and the arc-shaped protrusions and arc-shaped grooves of two adjacent modules are plug-connected.

4. The outer rotor switched reluctance motor according to claim 1, characterized in that: The inner surface of the magnetic isolation sleeve is provided with a mounting groove, and the rotor pole is provided with a mounting protrusion, which is plug-connected with the mounting groove.

5. The outer rotor switched reluctance motor according to claim 1, characterized in that: The inner surface of the rotor pole and the outer surface of the stator pole are both provided with a trapezoidal concave-convex structure, and the concave-convex structure of the rotor pole and the concave-convex structure of the stator pole are gap-matched to form a trapezoidal air gap.

6. The outer rotor switched reluctance motor according to claim 2, characterized in that: The three-phase winding is pulse-powered, the three-phase winding is a full-pitch winding, each phase winding is composed of m winding coils, and the connection method of the m winding coils of each phase winding is exactly the same.

7. The outer rotor switched reluctance motor according to claim 6, characterized in that: Three stator poles are interspersed in each winding coil. The coil edges on both sides of the winding coil are embedded in the winding slots. The currents of the coil edges in two adjacent winding slots flow in opposite directions.

8. The outer rotor switched reluctance motor according to claim 1, characterized in that: Two ends of the permanent magnet are respectively against the stator poles, and the axial length of the permanent magnet is the same as the stack length of the stator.

9. The outer rotor switched reluctance motor according to claim 8, characterized in that: The permanent magnet is tangentially magnetized, and the direction of the magnetic field generated by the permanent magnet in the stator is opposite to the direction of the magnetic field generated by the coil side arranged in the same slot in the stator.

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