A hybrid-excitation axial brushless motor and its power generation method

Abstract

The present invention provides a hybrid-excitation axial brushless motor and its power generation method, which includes a casing and a rotating shaft rotatably fixed within the casing. Seven components, namely a first excitation stator, a first magnetic flux regulating ring rotor, a first permanent magnet rotor, an armature stator, a second permanent magnet rotor, a second magnetic flux regulating ring rotor, and a second excitation stator, are sequentially installed axially within the casing. An air gap is provided between adjacent components. The first permanent magnet rotor and the second permanent magnet rotor are symmetrically arranged and both are rotatably fixed on the rotating shaft. The first magnetic flux regulating ring rotor and the second magnetic flux regulating ring rotor are symmetrically arranged and both are fixedly connected to the rotating shaft. The first excitation stator and the second excitation stator are symmetrically arranged and both are fixedly connected to the casing. The armature stator is fixedly connected to the casing through an armature stator bracket. By adopting hybrid excitation, the present invention realizes brushless operation while improving the power density and power generation capacity of the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of axial motors, and in particular to a hybrid-excitation axial brushless motor and a power generation method thereof. Background Art

[0002] With the continuous enhancement of energy crisis and environmental awareness, the scale of hybrid electric vehicles, hybrid unmanned aerial vehicles and wind power generation has gradually increased. Due to its own advantages, the hybrid-excitation axial flux motor is increasingly widely used in the fields of hybrid drive and wind power generation, but the problems of its low power factor and efficiency have also become prominent.

[0003] First of all, at present, the rotor in the hybrid-excitation axial flux motor usually adopts a single rotor structure, such as one of a wound rotor, a squirrel-cage rotor or a permanent magnet rotor. For the axial induction motor formed by a single wound rotor or squirrel-cage rotor, the efficiency and power factor of the motor are not high, and the wound rotor also requires a brush and slip ring structure, which reduces the operating reliability. For the permanent magnet synchronous motor formed by a single permanent magnet rotor, the magnetic field is not adjustable and cannot meet the requirement of flexible magnetic field adjustment under variable speed conditions.

[0004] Secondly, most of the structures of the hybrid-excitation axial flux motors in the prior art are flux-switching motors and brushless induction motors. Since the flux-switching motor generally adopts a salient pole structure, and both the permanent magnet and the armature winding in the motor are located on the stator side, there is a competitive relationship between the permanent magnet and the armature winding in space, which limits the space utilization rate and torque density of the hybrid-excitation axial flux-switching motor. For the hybrid-excitation axial brushless induction motor, whether it uses permanent magnet excitation or DC for hybrid excitation, although the efficiency of the motor is improved, the structure of the motor is too complex.

[0005] In addition, the existing hybrid-excitation axial flux motors usually have axial unbalanced magnetic pull, resulting in large vibrations during the operation of the motor.

[0006] In summary, the power density and torque density of the hybrid-excitation axial flux motor still need to be further improved; the problem of how to achieve brushless AC excitation remains to be solved; in addition, there are also problems in terms of magnetic field regulation performance and power generation efficiency of the existing permanent magnet brushless structure. These problems all affect the power factor and efficiency of the motor. Summary of the Invention

[0007] To solve the problems existing in the background art, the present invention proposes a hybrid-excitation axial brushless motor, which includes a casing and a rotating shaft rotatably fixed in the casing. Seven components, namely a first excitation stator, a first magnetic modulation ring rotor, a first permanent magnet rotor, an armature stator, a second permanent magnet rotor, a second magnetic modulation ring rotor, and a second excitation stator, are sequentially installed along the axis in the casing. Air gaps are provided between adjacent two components. The first permanent magnet rotor and the second permanent magnet rotor are symmetrically arranged and both are rotatably fixed on the rotating shaft. The first magnetic modulation ring rotor and the second magnetic modulation ring rotor are symmetrically arranged and both are fixedly connected to the rotating shaft. The first excitation stator and the second excitation stator are symmetrically arranged and both are fixedly connected to the casing. The armature stator is fixedly connected to the casing through an armature stator bracket.

[0008] The number of magnetic poles of both the first excitation stator and the second excitation stator is p, and the number of magnetic poles of the armature stator is q. Both the first magnetic modulation ring rotor and the second magnetic modulation ring rotor include reluctance units, and the number of reluctance units is p + q for both. Both p and q are integers and p and q are not equal.

[0009] Preferably, both the first excitation stator and the second excitation stator are circular rings and are provided with slots. A first excitation stator winding and a second excitation stator winding are respectively embedded in the slots of the first excitation stator and the second excitation stator. After the first excitation stator winding and the second excitation stator winding are energized, a magnetic field with the number of poles p is formed.

[0010] Preferably, both the first permanent magnet rotor and the second permanent magnet rotor include a permanent magnet rotor disk and a plurality of permanent magnets. The permanent magnets are evenly distributed on the circumference on one side of the permanent magnet rotor disk. The permanent magnets are all neodymium iron boron with axial magnetization and are arranged at intervals of magnetic charging polarities N and S. The number of magnetic poles of the permanent magnets is q.

[0011] Preferably, both the first magnetic modulation ring rotor and the second magnetic modulation ring rotor further include a magnetic modulation ring rotor disk. The reluctance unit includes a plurality of magnetic conduction blocks and a plurality of non-magnetic conduction blocks. The magnetic conduction blocks and the non-magnetic conduction blocks are installed on the magnetic modulation ring rotor disk, and the magnetic conduction blocks and the non-magnetic conduction blocks are alternately arranged along the magnetic modulation ring rotor disk.

[0012] Preferably, the armature stator includes a stator core, a separator disk, a first armature stator winding, and a second armature stator winding. Slots are provided on both sides of the stator core. The first armature stator winding and the second armature stator winding are respectively installed in the slots on both sides of the stator core. After the first armature stator winding and the second armature stator winding are energized, a magnetic field with the number of poles p is formed. The separator disk is arranged on the stator core between the first armature stator winding and the second armature stator winding.

[0013] Preferably, both the first armature stator winding and the second armature stator winding located in the stator core slots are AC windings, and the magnetic fields generated by the first armature stator winding and the second armature stator winding are not coupled. The spacer disk is made of non-magnetic material.

[0014] Preferably, the first permanent magnet rotor and the second permanent magnet rotor are respectively rotatably fixed on the rotating shaft through permanent magnet rotor bearings.

[0015] A power generation method for a hybrid-excitation axial brushless motor:

[0016] The first excitation stator, the first magnetic field regulating ring rotor, the first permanent magnet rotor and the first armature stator winding form a first working unit, and the second excitation stator, the second magnetic field regulating ring rotor, the second permanent magnet rotor and the second armature stator winding form a second working unit. The first working unit and the second working unit work simultaneously and have the same operating principle;

[0017] Taking the first working unit as an example, an external power component drives the rotating shaft to rotate, and the rotating shaft drives the first magnetic field regulating ring rotor to rotate. At this time, an alternating current magnetic field with a pole pair number of p is generated by passing an alternating current excitation current through the first excitation stator winding. The magnetic field is modulated by the first magnetic field regulating ring rotor to modulate a p-pole and a q-pole magnetic field. The modulated q-pole magnetic field interacts with the first armature stator winding to induce a q-pole alternating current electromotive force in the first armature stator winding. At the same time, the first permanent magnet rotor rotates under the action of the changing magnetic field, and the rotating first permanent magnet rotor cuts the modulated alternating current magnetic field, and a q-pole alternating current electromotive force will also be induced in the first armature stator winding.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The structure of the first excitation stator, the second excitation stator, the first magnetic field regulating ring rotor and the second magnetic field regulating ring rotor adopted in the present invention realizes the brushless of a hybrid-excitation axial motor of the present invention, solves the technical problems that electric sparks will be generated by the carbon brushes and slip rings of an AC brushed motor, and the electric sparks cause poor reliability and high failure rate of the motor, and improves the stable operation ability of the motor.

[0020] 2. The present invention is symmetric about the armature stator in the overall structure, balancing the axial magnetic pull of the stator and the rotor, thereby achieving the purpose of weakening vibration and noise.

[0021] 3. The present invention adopts a hybrid-excitation structure of the same axial AC and permanent magnet excitation. The first excitation stator and the second excitation stator perform AC excitation, and the first permanent magnet rotor and the second permanent magnet rotor perform permanent magnet excitation. The armature stator includes two independent armature stator windings, which is equivalent to the performance synthesized by two brushless axial motors, significantly improving the motor power density and power generation amount.

[0022] 4. The AC and permanent magnet hybrid excitation of the present invention improves the operating efficiency of the motor and also enhances the flexibility of magnetic field regulation. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 It is a schematic diagram of the armature stator structure of the present invention;

[0025] Figure 3 It is a schematic diagram of the excitation stator structure of the present invention;

[0026] Figure 4 It is a schematic diagram of the permanent magnet rotor structure of the present invention;

[0027] Figure 5 It is a schematic diagram of the magnetic field regulating ring rotor structure of the present invention;

[0028] Figure 6 It is a schematic diagram of the overall structure of Embodiment 2 of the present invention;

[0029] Figure 7 It is a schematic diagram of the overall structure of Embodiment 3 of the present invention.

[0030] Reference numerals in the drawings: 1. Machine housing; 2. First end cover; 3. First excitation stator; 4. First excitation stator winding; 5. First magnetic field regulating ring rotor; 6. First permanent magnet rotor; 7. Second end cover; 8. Second excitation stator; 9. Second excitation stator winding; 10. Permanent magnet rotor bearing; 11. Second magnetic field regulating ring rotor; 12. Second permanent magnet rotor; 13. Permanent magnet; 14. Armature stator; 15. Separation disk; 16. Armature stator bracket; 17. Rotating shaft bearing; 18. Rotating shaft; 19. First armature stator winding; 20. Second armature stator winding; 21. Permanent magnet rotor disk; 22. Magnetic field regulating ring rotor disk; 23. Reluctance unit; 24. Magnetic conduction block; 25. Non-magnetic conduction block; 26. Armature stator rectifier-inverter device; 27. Excitation stator rectifier-inverter device; 28. Storage battery; 29. Dual PWM converter; 30. Power grid. Detailed Embodiments

[0031] In order to make the present invention clearer and more understandable, the following further elaborates on the technical solutions of the present invention in conjunction with the description of the drawings and embodiments. It should be understood that the given embodiments are only two implementation manners and do not represent all embodiments.

[0032] Embodiment 1:

[0033] Combined with the attached Figure 1-6, the present invention provides a hybrid-excitation axial brushless motor, which includes a housing 1 and a rotating shaft 18 rotatably fixed within the housing 1. Specifically, a first end cover 2 and a second end cover 7 are provided at both ends of the housing 1. One end of the rotating shaft 18 is rotatably connected to the first end cover 2 through a rotating shaft bearing 17, and the other end of the rotating shaft 18 is rotatably connected to the second end cover 7 through another rotating shaft bearing 17. Seven components, namely a first excitation stator 3, a first magnetic flux regulating ring rotor 5, a first permanent magnet rotor 6, an armature stator 14, a second permanent magnet rotor 12, a second magnetic flux regulating ring rotor 11, and a second excitation stator 8, are axially installed in sequence within the housing 1. An air gap is provided between adjacent two components. The first permanent magnet rotor 6 and the second permanent magnet rotor 12 are symmetrically arranged and both are rotatably fixed on the rotating shaft 18. The first magnetic flux regulating ring rotor 5 and the second magnetic flux regulating ring rotor 11 are symmetrically arranged and both are fixedly connected to the rotating shaft 18. The first excitation stator 3 and the second excitation stator 8 are symmetrically arranged and both are fixedly connected to the housing 1. The armature stator 14 is fixedly connected to the housing 1 through an armature stator bracket 16.

[0034] The number of magnetic poles of both the first excitation stator 3 and the second excitation stator 8 is p, and the number of magnetic poles of the armature stator 14 is q. Both the first magnetic flux regulating ring rotor 5 and the second magnetic flux regulating ring rotor 11 include reluctance units 23, and the number of the reluctance units 23 is p + q for both. Both p and q are integers and p and q are not equal.

[0035] The center lines of the eight components, namely the rotating shaft 18, the first excitation stator 3, the first magnetic flux regulating ring rotor 5, the first permanent magnet rotor 6, the armature stator 14, the second permanent magnet rotor 12, the second magnetic flux regulating ring rotor 11, and the second excitation stator, are on the same straight line.

[0036] Specifically, both the first excitation stator 3 and the second excitation stator 8 are circular rings and are provided with slots. A first excitation stator winding 4 and a second excitation stator winding 9 are respectively embedded in the slots of the first excitation stator 3 and the second excitation stator 8. After the first excitation stator winding 4 and the second excitation stator winding 9 are energized, a magnetic field with the number of poles p is formed.

[0037] Specifically, both the first permanent magnet rotor 6 and the second permanent magnet rotor 12 include a permanent magnet rotor disk 21 and a plurality of permanent magnets 13. The permanent magnets 13 are evenly distributed on the circumference of one side of the permanent magnet rotor disk 21. The permanent magnets 13 are all axially magnetized neodymium iron boron and are arranged at intervals of magnetic charging polarities N and S. The number of magnetic poles of the permanent magnets 13 is q.

[0038] Specifically, both the first magnetic flux regulating ring rotor 5 and the second magnetic flux regulating ring rotor 11 further include a magnetic flux regulating ring rotor disk 22. The reluctance unit 23 includes a plurality of magnetic conduction blocks 24 and a plurality of non-magnetic conduction blocks 25. The magnetic conduction blocks 24 and the non-magnetic conduction blocks 25 are installed on the magnetic flux regulating ring rotor disk 22, and the magnetic conduction blocks 24 and the non-magnetic conduction blocks 24 are alternately arranged along the magnetic flux regulating ring rotor disk 22.

[0039] Specifically, the armature stator 14 includes a stator core, a spacer disk 15, a first armature stator winding 19, and a second armature stator winding 20. Slots are formed on both sides of the stator core. The first armature stator winding 19 and the second armature stator winding 20 are respectively installed in the slots on both sides of the stator core. After the first armature stator winding 19 and the second armature stator winding 20 are energized, a magnetic field with a pole number of p is formed. The spacer disk 15 is arranged on the stator core between the first armature stator winding 19 and the second armature stator winding 20.

[0040] Specifically, both the first armature stator winding 19 and the second armature stator winding 20 located in the stator core slots are AC windings, and the magnetic fields generated by the first armature stator winding 19 and the second armature stator winding 20 are not coupled. The spacer disk 15 is made of a non-magnetic material.

[0041] Specifically, the first permanent magnet rotor 6 and the second permanent magnet rotor 12 are respectively rotationally fixed on the rotating shaft 18 through permanent magnet rotor bearings 10 and can freely rotate around the rotating shaft 18 through the permanent magnet rotor bearings 10.

[0042] A power generation method for a hybrid excitation axial brushless motor: The first excitation stator 4, the first magnetic field regulating ring rotor 5, the first permanent magnet rotor 6, and the first armature stator winding 19 form a first working unit, and the second excitation stator 8, the second magnetic field regulating ring rotor 11, the second permanent magnet rotor 12, and the second armature stator winding 20 form a second working unit. The first working unit and the second working unit work simultaneously and have the same operating principle.

[0043] Taking the first working unit as an example, an external power component drives the rotating shaft 18 to rotate. The external power component is a driving device such as an internal combustion engine or a wind turbine. The rotating shaft 18 drives the first magnetic field regulating ring rotor 5 to rotate. At this time, an alternating magnetic field with a pole number of p is generated by passing an alternating excitation current through the first excitation stator winding 4. Through the first magnetic field regulating ring rotor 5, magnetic field modulation is performed to modulate a p-pole and a q-pole magnetic field. The modulated q-pole magnetic field interacts with the first armature stator winding 19, and a q-pole alternating electromotive force is induced in the first armature stator winding 19. At the same time, the first permanent magnet rotor 6 rotates under the action of the changing magnetic field. The rotating first permanent magnet rotor 6 cuts the modulated alternating magnetic field, and a q-pole alternating electromotive force is also induced in the first armature stator winding 19.

[0044] Embodiment 2:

[0045] Combined with Figure 6, taking the first working unit as an example, when the hybrid-excitation axial brushless motor operates as a power generation unit in the hybrid drive system, the first armature stator winding 19 is connected to the storage battery 28 through the armature stator rectifier-inverter device 26, and the first excitation stator winding 4 is connected to the storage battery 28 through the excitation stator rectifier-inverter device 27. When the driving torque of the external power component of the prime mover acting on the motor shaft 18 changes, the current in the excitation stator rectifier-inverter device 27 can be adjusted to ensure that the first armature stator winding 19 outputs AC electric energy.

[0046] By coordinating the external prime mover driving torque and the current in the first excitation stator 3, it can be ensured that the first armature stator winding 19 can output a stable electromotive force.

[0047] Embodiment 3:

[0048] Combined with Figure 7 , taking the first working unit as an example, when the hybrid-excitation axial brushless motor operates as a variable-speed constant-frequency wind power generation unit, the first armature stator winding 19 is directly connected to the power grid 30, and the first excitation stator winding 4 is connected to the power grid 30 through the dual PWM converter 29. To ensure variable-speed constant-frequency operation, when the wind speed changes and the generator speed changes, the frequency of the current in the first excitation stator winding 4 can be controlled to keep the frequency of the first armature stator winding 19 constant. Specifically, when the generator speed is less than the synchronous speed, that is, in the sub-synchronous state, the direction of the rotating magnetic field generated by the first excitation stator 3 is the same as the direction of rotation speed. At this time, the first excitation stator 3 absorbs the slip power from the power grid 30 through the dual PWM frequency converter 29; when the generator speed is greater than the synchronous speed, that is, in the super-synchronous state, the direction of the rotating magnetic field generated by the first excitation stator 3 is opposite to the direction of rotation speed. At this time, the first excitation stator winding 4 feeds the slip power to the power grid 30 through the dual PWM frequency converter 29; when the generator speed is equal to the synchronous speed, that is, in the synchronous state, at this time the dual PWM frequency converter 29 provides DC excitation to the first excitation stator 3, equivalent to the operation of a synchronous generator. In the above three operating states, the excitation method of the first excitation stator 3 is realized by the first magnetic modulation ring rotor 5 for brushless double-fed excitation after magnetic modulation.

[0049] It can be seen that when operating as a wind turbine connected to the grid, the present invention can achieve brushless double-fed variable-speed constant-frequency power generation.

[0050] The above embodiments only illustrate the basic principles and characteristics of the present invention, but are not limited by the above embodiments. It should be understood that for those of ordinary skill in the art, various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention, and these changes and modifications all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A hybrid-excitation axial brushless motor, comprising a housing (1) and a rotating shaft (18) rotatably fixed within the housing (1), characterized in that: Inside the housing (1), seven components are successively installed along the axis, namely a first exciting stator (3), a first magnetic regulating ring rotor (5), a first permanent magnet rotor (6), an armature stator (14), a second permanent magnet rotor (12), a second magnetic regulating ring rotor (11), and a second exciting stator (8). An air gap is provided between adjacent two components. The first permanent magnet rotor (6) and the second permanent magnet rotor (12) are symmetrically arranged and both are rotatably fixed on the rotating shaft (18). The first magnetic regulating ring rotor (5) and the second magnetic regulating ring rotor (11) are symmetrically arranged and both are fixedly connected to the rotating shaft (18). The first exciting stator (3) and the second exciting stator (8) are symmetrically arranged and both are fixedly connected to the housing (1). The armature stator (14) is fixedly connected to the housing (1) through the armature stator bracket (16). The number of magnetic poles of both the first exciting stator (3) and the second exciting stator (8) is p, and the number of magnetic poles of the armature stator (14) is q. Both the first magnetic regulating ring rotor (5) and the second magnetic regulating ring rotor (11) include reluctance units (23), and the number of reluctance units (23) is p + q for both. Both p and q are integers and p and q are not equal.

2. The hybrid-excitation axial brushless motor according to claim 1, wherein: Both the first exciting stator (3) and the second exciting stator (8) are circular rings and are provided with slots. The first exciting stator (3) and the second exciting stator (8) respectively embed a first exciting stator winding (4) and a second exciting stator winding (9) in the slots. After the first exciting stator winding (4) and the second exciting stator winding (9) are energized, a magnetic field with the number of poles p is formed.

3. The hybrid-excitation axial brushless motor according to claim 1, characterized in that: Both the first permanent magnet rotor (6) and the second permanent magnet rotor (12) include a permanent magnet rotor disk (21) and a plurality of permanent magnets (13). The permanent magnets (13) are evenly distributed on the circumference on one side of the permanent magnet rotor disk (21). The permanent magnets (13) are all neodymium iron boron magnetized axially and are arranged at intervals of the magnetization polarities N and S. The number of magnetic poles of the permanent magnets (13) is q.

4. A hybrid-excitation axial brushless motor according to claim 1, characterized in that: Both the first magnetic regulating ring rotor (5) and the second magnetic regulating ring rotor (11) further include a magnetic regulating ring rotor disk (22). The reluctance unit (23) includes a plurality of magnetic conduction blocks (24) and a plurality of non-magnetic conduction blocks (25). The magnetic conduction blocks (24) and the non-magnetic conduction blocks (25) are installed on the magnetic regulating ring rotor disk (22), and the magnetic conduction blocks (24) and the non-magnetic conduction blocks (25) are arranged alternately along the magnetic regulating ring rotor disk (22).

5. A hybrid-excitation axial brushless motor according to claim 1, wherein: The armature stator (14) includes a stator core, a separator disk (15), a first armature stator winding (19), and a second armature stator winding (20). Slots are opened on both sides of the stator core. The first armature stator winding (19) and the second armature stator winding (20) are respectively installed in the slots on both sides of the stator core. After the first armature stator winding (19) and the second armature stator winding (20) are energized, a magnetic field with the number of poles q is formed. The separator disk (15) is arranged on the stator core between the first armature stator winding (19) and the second armature stator winding (20).

6. The hybrid excitation axial brushless motor according to claim 5, wherein: Both the first armature stator winding (19) and the second armature stator winding (20) located in the stator core slots are AC windings, and the magnetic fields generated by the first armature stator winding (19) and the second armature stator winding (20) are not coupled. The spacer disk (15) is made of non-magnetic material.

7. A hybrid-excitation axial brushless motor according to claim 1, characterized in that: The first permanent magnet rotor (6) and the second permanent magnet rotor (12) are respectively rotatably fixed on the rotating shaft (18) through permanent magnet rotor bearings (10).

8. A power generation method for a hybrid-excitation axial brushless motor, implemented based on the hybrid-excitation axial brushless motor described in claim 1, characterized in that: The first exciting stator winding (4), the first magnetic modulation ring rotor (5), the first permanent magnet rotor (6) and the first armature stator winding (19) form a first working unit, and the second exciting stator (8), the second magnetic modulation ring rotor (11), the second permanent magnet rotor (12) and the second armature stator winding (20) form a second working unit. The first working unit and the second working unit work simultaneously and have the same operating principle. Taking the first working unit as an example, an external power component drives the rotating shaft to rotate, and the first magnetic modulation ring rotor (5) is driven to rotate by the rotating shaft (8). At this time, an alternating magnetic field with a pole pair number of p is generated by passing an alternating excitation current through the first exciting stator winding (4). Through the first magnetic modulation ring rotor (5), the magnetic field is modulated to generate a p-pole and a q-pole magnetic field. The modulated q-pole magnetic field interacts with the first armature stator winding (19), and a q-pole alternating electromotive force is induced in the first armature stator winding (19). At the same time, the first permanent magnet rotor (6) is forced to rotate in the changing magnetic field, and the rotating first permanent magnet rotor (6) cuts the modulated alternating magnetic field, and a q-pole alternating electromotive force is also induced in the first armature stator winding (19).

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