Axial magnetic flux type hybrid excitation switched reluctance motor

Abstract

The invention provides an axial magnetic flux type hybrid excitation switched reluctance motor which comprises two stator ring assemblies and a rotor ring assembly arranged between the two stator ring assemblies, and an air gap is formed between the stator ring assemblies and the rotor ring assembly. The stator ring assembly comprises a stator iron core, auxiliary excitation permanent magnets and armature windings, the stator iron core is provided with a plurality of stator main poles and auxiliary poles which are distributed in a staggered mode, each stator main pole is wound with one armature winding, the auxiliary excitation permanent magnets are arranged on the stator grooves close to the air gap side, and the auxiliary excitation permanent magnets are arranged on the stator grooves close to the air gap side. And the armature winding is sealed in the stator slot. The auxiliary excitation permanent magnets are added between the stator main poles and the auxiliary poles, so that the air gap flux density during conduction and the magnetic field of the switched reluctance motor are improved, the torque density and the power density of the switched reluctance motor are improved, and meanwhile, the excitation current of the armature winding is reduced; and the average torque of the switched reluctance motor is increased, a main magnetic circuit is shortened, and the operation efficiency of the switched reluctance motor is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flux switched reluctance motors, and in particular relates to an axial flux hybrid excitation switched reluctance motor. Background Art

[0002] Switched reluctance motor (SRM) has the advantages of simple structure, high efficiency, low cost of consumables, etc., and has broad application prospects. Although SRM has a wide speed range and advantages, compared with permanent magnet motors, they also have disadvantages such as large torque pulsation and low torque / power density, which limits their application.

[0003] At present, in order to improve the operating performance of the switched reluctance motor and expand the application field of the switched reluctance motor, the topology of the switched reluctance motor needs to be improved. Studies have found that the modular motor structure with auxiliary poles can effectively improve the power density of the motor and reduce the processing cost. For example, a journal paper published in IEEE Transactions on Industry Applications (Characteristics Analysis and Comparison of Conventional and Segmental Rotor Type 12 / 8 Switched Reluctance Motors, Z. Xu, J. Liu, MJ Kim, DH Lee and JW Ahn, IEEE Trans. Ind. Appl, vol. 55, no. 3, pp. 3129-3137, May-June 2019) proposed a new type of 12 / 8-pole radial switched reluctance motor, which has a segmented rotor and 6 main poles and 6 auxiliary poles on the stator. This structure shortens the magnetic circuit and increases the output torque. Compared with traditional SRM, this topology with auxiliary poles in the stator can generally increase the torque density and power density of the motor. However, although merely replacing part of the stator poles in the switched reluctance motor with auxiliary poles can shorten the magnetic circuit to achieve the purpose of increasing the torque, it wastes the soft magnetic material performance of the motor in disguised form. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of material waste in the prior art in order to improve the switched reluctance motor, and to provide an axial flux type hybrid excitation switched reluctance motor.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] An axial flux type hybrid excitation switched reluctance motor comprises two groups of stator ring assemblies and a rotor ring assembly arranged between the two stator ring assemblies, wherein an air gap is provided between the stator ring assembly and the rotor ring assembly, the rotor ring assembly is fixedly connected to the motor shaft, and a bearing is provided between each stator ring assembly and the motor shaft; the stator ring assembly comprises a stator core, an auxiliary excitation permanent magnet and an armature winding, the stator core is provided with a plurality of stator main poles and auxiliary poles arranged in an alternating distribution, and the gap between the stator main pole and the auxiliary pole is a stator slot of the stator core; an armature winding is wound around each stator main pole for generating a main magnetic flux, and the auxiliary pole is used to provide a return path for the magnetic flux; a plurality of auxiliary excitation permanent magnets are provided and are respectively installed on the stator slots close to the air gap side so as to enclose the armature winding in the stator slot; the rotor ring assembly comprises a plurality of rotor cores evenly distributed in the circumferential direction and a non-magnetic material fixing member for connecting the plurality of rotor cores.

[0007] Furthermore, both the stator main pole and the auxiliary pole are fan-shaped structures, and the pole arc width of the stator main pole is twice the pole arc width of the auxiliary pole.

[0008] Furthermore, the auxiliary excitation permanent magnets have a fan-shaped structure, and the magnetization direction is the circumferential direction of the stator core. The auxiliary excitation permanent magnets on both sides of each stator main pole form a group, and the magnetization directions are opposite.

[0009] Furthermore, the inner diameter of the auxiliary excitation permanent magnet is the same as the inner diameter of the stator main pole, and the outer diameter is the same as the outer diameter of the stator main pole.

[0010] Furthermore, the pole arc width of the rotor core is the same as the pole arc width of the stator main pole, and the core stack length is the same as the width of the auxiliary pole.

[0011] Furthermore, a plurality of auxiliary excitation permanent magnets are evenly distributed on the stator core and are not in contact with the rotor core.

[0012] Furthermore, the side of the stator ring assembly away from the rotor ring assembly is the stator yoke; when the armature winding of a phase of the switched reluctance motor is not energized, the magnetic flux path near the stator main pole of this phase is: auxiliary excitation permanent magnet-stator main pole-stator yoke-auxiliary pole-auxiliary excitation permanent magnet; when the armature winding of this phase is energized, the magnetic field of the switched reluctance motor is composed of the armature winding and the auxiliary excitation permanent magnet.

[0013] Furthermore, the non-magnetic material fixing piece is austenitic stainless steel filled between the multiple rotor cores.

[0014] The advantages of the present invention are:

[0015] 1. The present invention increases the air gap flux density and the magnetic field of the switched reluctance motor during conduction by adding auxiliary excitation permanent magnets between the stator main pole and the auxiliary pole, thereby increasing the motor torque density and power density, while reducing the excitation current of the armature winding and reducing copper loss. Since the addition of auxiliary excitation permanent magnets has no effect on the peak torque of the switched reluctance motor, but increases the average torque, the torque ripple can also be slightly reduced.

[0016] 2. The stator ring assembly adopts a mixed structure of stator main poles and auxiliary poles, which shortens the main magnetic circuit, that is, more magnetic flux will pass through the air gap to reach the rotor core, thereby increasing the air gap magnetic density in disguise; at the same time, it eliminates the magnetic flux reversal in the stator ring assembly, thereby reducing iron loss and magnetomotive force requirements, and improving the operating efficiency of the switched reluctance motor.

[0017] 3. The rotor ring assembly adopts a modular rotor structure to achieve lightweight design of the switched reluctance motor, reduce rotational inertia, reduce starting difficulty, and reduce wind resistance.

[0018] 4. Applying auxiliary pole structure and auxiliary excitation permanent magnet to axial flux motor structure makes it easier to improve output torque and wheel hub integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The features and advantages of the present invention will become more readily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and in which some features are exaggerated or minimized to show details of particular components:

[0020] Figure 1 is a schematic structural diagram of an axial flux type hybrid excitation switched reluctance motor according to an embodiment of the present invention;

[0021] Figure 2 is an exploded view of an axial flux type hybrid excitation switched reluctance motor according to an embodiment of the present invention;

[0022] Figure 3 1 is a schematic structural diagram of a stator core in an embodiment of the present invention;

[0023] Figure 4 It is a structural schematic diagram of auxiliary excitation permanent magnets and armature windings installed on the stator main poles in an embodiment of the present invention;

[0024] Figure 5 is a schematic diagram of the position distribution of multiple rotor cores in an embodiment of the present invention;

[0025] Figure 6 is a schematic structural diagram of an auxiliary excitation permanent magnet in an embodiment of the present invention;

[0026] Figure 7 is a schematic structural diagram of a rotor core in an embodiment of the present invention;

[0027] In the figure: 1- stator core; 2- auxiliary excitation permanent magnet; 3- rotor core; 4- armature winding; 5- stator main pole; 6- auxiliary pole. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings by means of exemplary embodiments of the present invention. It should be noted that the following detailed description of the present invention is only for the purpose of illustration, and is not intended to limit the present invention.

[0029] An axial flux type hybrid excitation switched reluctance motor, such as Figure 1 As shown, it includes two groups of stator ring assemblies and a rotor ring assembly arranged between the two stator ring assemblies, the rotor ring assembly is fixed on the motor shaft through non-magnetic conductive materials, each stator ring assembly is fixed on the motor shaft through a motor bearing, and an air gap is separated from the two groups of stator ring assemblies and the rotor ring assembly. The side of the stator ring assembly away from the rotor ring assembly is the stator yoke, and the side close to the rotor ring assembly is the air gap side.

[0030] like Figure 2 , 4 As shown, the stator ring assembly includes a stator core 1, an auxiliary excitation permanent magnet 2 and an armature winding 4. Figure 3 As shown, the stator core 1 has 12 stator main poles 5 and auxiliary poles 6 arranged in a staggered manner, and the gaps between the stator main poles 5 and the auxiliary poles 6 are stator slots of the stator core 1, with a total of 12 stator slots. The number and slot type of the stator slots in the two sets of stator and rotor components are consistent. The armature winding 4 adopts flat wire direct forming technology to improve the slot fill rate of the stator slot.

[0031] like Figure 4 As shown, each stator main pole 5 is wound with an armature winding 4, the armature winding 4 is a ring structure, and is used to generate a main magnetic flux, and the auxiliary pole 6 is used to provide a return path for the magnetic flux.

[0032] like Figure 1 , 5 As shown, the rotor ring assembly includes a plurality of rotor cores 3 evenly distributed in the circumferential direction and a non-magnetic material fixing member for connecting the plurality of rotor cores 3 .

[0033] In this embodiment, the main magnetic circuit of the switched reluctance motor is: stator main pole 5-air gap-rotor core 3-air gap-stator main pole 5-stator yoke and auxiliary pole 6-air gap-rotor core 3-air gap-auxiliary pole 6-stator yoke. The magnetic flux of each stator main pole 5 passes along the adjacent left and right auxiliary poles 6; the magnetic flux of each auxiliary pole 6 is about 1 / 2 of the stator main pole 5, and the direction of the magnetic flux is opposite to that of the adjacent stator main pole 5, so that the magnetic flux path is shortened without changing the number and volume of the stator and rotor of the switched reluctance motor, and the stator slot area is increased. In addition, when the phase current transitions from phase A to phase B, or from phase B to phase C, or from phase C to phase A, there is no magnetic flux reversal in the stator main pole 5 of the motor, and vice versa, which significantly reduces the iron loss and magnetomotive force requirements.

[0034] In one embodiment, a plurality of auxiliary excitation permanent magnets 2 are provided and respectively installed on the stator slots close to the air gap side. The auxiliary excitation permanent magnets 2, the stator yoke, the stator main poles 5 and the auxiliary poles 6 surround the armature winding 4 and enclose the armature winding 4 in the stator slots.

[0035] like Figure 4 , 6 As shown, the auxiliary excitation permanent magnet 2 has a fan-shaped structure, and the material is high-performance sintered NdFeB, and the magnetization direction is the circumferential direction of the stator core 1. The auxiliary excitation permanent magnets 2 on both sides of each stator main pole 5 are a group, and the magnetization directions are opposite, so that the excitation flux passes through the stator main pole 5 to increase the air gap magnetic density.

[0036] In this embodiment, the above scheme is used to further strengthen the motor magnetic field and increase the air gap magnetic flux density. When the armature winding 4 of a certain phase of the switched reluctance motor is not energized, the magnetic flux path near the stator main pole 5 of the phase is: auxiliary excitation permanent magnet 2-stator main pole 5-stator yoke-auxiliary pole 6-auxiliary excitation permanent magnet 2. At this time, the auxiliary excitation permanent magnet 2 has no effect on the torque output of the switched reluctance motor; when the armature winding 4 of the phase is energized, the magnetic field provided by the two adjacent auxiliary excitation permanent magnets 2 of the stator main pole 5 of the phase is added to the main magnetic flux due to the action of direct current, that is, the magnetic field of the switched reluctance motor is composed of the armature winding 4 and the auxiliary excitation permanent magnet 2. At this time, the electromagnetic torque of the switched reluctance motor is composed of the reluctance torque and the permanent magnet torque, thereby achieving the effect of enhancing the torque in the early stage without increasing the volume of the switched reluctance motor.

[0037] In one embodiment, Figure 3 As shown, the stator main pole 5 and the auxiliary pole 6 are both fan-shaped structures, and the pole arc width of the stator main pole 5 is twice the pole arc width of the auxiliary pole 6. The stator core 1, the electronic main pole and the auxiliary pole 6 are all made of soft magnetic composite materials and are die-cast in one piece.

[0038] In one embodiment, 12 auxiliary excitation permanent magnets 2 are evenly distributed on the stator core 1 and do not contact the rotor core 3 , and other parts are filled with non-magnetic material fixing members. The non-magnetic material fixing members are austenitic stainless steel filled between multiple rotor cores 3 .

[0039] In this embodiment, the number of rotor core 3 stages is 8, which matches the number of stator slots 12 to form a concentrated winding motor structure; by using non-magnetic conductive materials as fixing parts, the electromagnetic mass of the switched reluctance motor is reduced, and the wind resistance during the operation of the switched reluctance motor is reduced, thereby reducing the difficulty of starting the switched reluctance motor.

[0040] In one embodiment, the inner diameter of the auxiliary excitation permanent magnet 2 is the same as the inner diameter of the stator main pole 5 , and the outer diameter is the same as the outer diameter of the stator main pole 5 .

[0041] In one embodiment, Figure 6 , 7 As shown, the pole arc width of the rotor core 3 is the same as that of the stator main pole 5, and the core stack length is the same as the width of the auxiliary pole 6, that is, 1 / 2 of the width of the stator main pole 5. The core stack length refers to the axial length of the magnetic circuit part of the rotor core 3, which can be simply understood as the thickness of the rotor core 3. To prevent the magnetic density saturation of the rotor ring assembly material, the material of the rotor core 3 is selected to be the same as that of the stator core 1.

[0042] The present invention increases the air gap flux density and the motor magnetic field during conduction by adding an auxiliary excitation permanent magnet 2 between the teeth of the stator main pole 5 and the auxiliary pole 6, thereby making it easier to increase the torque density and power density of the switched reluctance motor, while reducing the excitation current of the armature winding 4 and the copper loss; the average torque is increased; this structure also increases the air gap flux density in disguised form, while eliminating the flux reversal in the stator switching component stage, thereby reducing the iron loss and magnetomotive force requirements and improving the motor operation efficiency.

[0043] Finally, it should be noted that the features mentioned and / or shown in the above description of the exemplary embodiments of the present invention may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other implementations. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope of the present invention.

Claims

1. An axial flux type hybrid excitation switched reluctance motor, characterized in that: It comprises two groups of stator ring assemblies and a rotor ring assembly arranged between the two stator ring assemblies, wherein an air gap is provided between the stator ring assembly and the rotor ring assembly, the rotor ring assembly is fixedly connected to the motor shaft, and a bearing is provided between each stator ring assembly and the motor shaft; The stator ring assembly comprises a stator core, auxiliary excitation permanent magnets and an armature winding. The stator core is provided with a plurality of stator main poles and auxiliary poles which are arranged in a staggered distribution. The gap between the stator main poles and the auxiliary poles is the stator slot of the stator core. The armature winding is wound around each of the stator main poles to generate a main magnetic flux, and the auxiliary pole is used to provide a return path for the magnetic flux. The auxiliary excitation permanent magnets are provided in plurality and are respectively installed on the stator slots close to the air gap side to enclose the armature winding in the stator slots. The rotor ring assembly comprises a plurality of rotor cores evenly distributed in the circumferential direction and a non-magnetic material fixing member for connecting the plurality of rotor cores.

2. The axial flux hybrid excitation switched reluctance motor according to claim 1, characterized in that: The stator main pole and the auxiliary pole are both fan-shaped structures, and the pole arc width of the stator main pole is twice the pole arc width of the auxiliary pole.

3. The axial flux hybrid excitation switched reluctance motor according to claim 1, characterized in that: The auxiliary excitation permanent magnets are in a fan-shaped structure, and the magnetization direction is the circumferential direction of the stator core. The auxiliary excitation permanent magnets on both sides of each stator main pole form a group, and the magnetization directions are opposite.

4. The axial flux hybrid excitation switched reluctance motor according to claim 1, characterized in that: The inner diameter of the auxiliary excitation permanent magnet is the same as the inner diameter of the stator main pole, and the outer diameter is the same as the outer diameter of the stator main pole.

5. The axial flux hybrid excitation switched reluctance motor according to claim 1, characterized in that: The pole arc width of the rotor core is the same as the pole arc width of the stator main pole, and the core stack length is the same as the width of the auxiliary pole.

6. The axial flux hybrid excitation switched reluctance motor according to claim 1, characterized in that: The plurality of auxiliary excitation permanent magnets are evenly distributed on the stator core and are not in contact with the rotor core.

7. The axial flux hybrid excitation switched reluctance motor according to claim 1, characterized in that: The side of the stator ring assembly away from the rotor ring assembly is the stator yoke; when the armature winding of a certain phase of the switched reluctance motor is not energized, the magnetic flux path near the stator main pole is: auxiliary excitation permanent magnet-stator main pole-stator yoke-auxiliary pole-auxiliary excitation permanent magnet; when the armature winding of this phase is energized, the magnetic field of the switched reluctance motor is composed of the armature winding and the auxiliary excitation permanent magnet.

8. The axial flux hybrid excitation switched reluctance motor according to claim 1, characterized in that: The non-magnetic conductive material fixing piece is austenitic stainless steel filled between the plurality of rotor cores.

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