An axial flux hybrid excitation switched reluctance motor

Abstract

The present invention provides an axial flux hybrid excitation switched reluctance motor, comprising two stator ring assemblies and a rotor ring assembly disposed between the two stator ring assemblies, with an air gap separating the stator ring assemblies. The stator ring assembly comprises a stator core, auxiliary excitation permanent magnets, and an armature winding. The stator core has a plurality of stator main poles and auxiliary poles arranged in an alternating pattern, each of which is wound with an armature winding. Multiple auxiliary excitation permanent magnets are provided and mounted on stator slots proximal to the air gap to enclose the armature winding within the stator slots. By adding auxiliary excitation permanent magnets between the stator main poles and the auxiliary poles, the present invention increases the air gap flux density and the magnetic field of the switched reluctance motor during conduction, thereby improving the torque density and power density of the switched reluctance motor while reducing the excitation current of the armature winding. Furthermore, the average torque of the switched reluctance motor is increased, the main magnetic circuit is shortened, and the operating efficiency of the switched reluctance motor is further improved.

Description

Technical Field

[0001] The present 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 motors (SRMs) have broad application prospects due to their simple structure, high efficiency, and low material costs. While SRMs offer advantages such as a wide speed range, they also suffer from disadvantages such as high torque ripple and lower torque / power density compared to permanent magnet motors, which limit their application.

[0003] To improve the operating performance and expand the application areas of switched reluctance motors (SRMs), improvements to their topology are needed. Research has found that modular motor structures with auxiliary poles can effectively increase the motor's power density and reduce manufacturing costs. For example, a journal article 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) proposes a novel 12 / 8-pole radial switched reluctance motor with a segmented rotor and six main poles and six auxiliary poles on the stator. This structure shortens the magnetic circuit and increases output torque. Compared to traditional SRMs, this topology with auxiliary poles in the stator generally increases the motor's torque and power density. However, although simply replacing some of the stator poles in the switched reluctance motor with auxiliary poles can shorten the magnetic circuit to achieve the purpose of increasing torque, it in disguised form wastes the soft magnetic material performance of the motor. 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 hybrid excitation switched reluctance motor.

[0005] To achieve the above objectives, the technical solutions provided by the present invention are:

[0006] An axial flux hybrid excitation switched reluctance motor comprises two groups of stator ring assemblies and a rotor ring assembly arranged between the two stator ring assemblies, with an air gap between the stator ring assemblies 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 having a plurality of stator main poles and auxiliary poles arranged in an alternating distribution, and the gaps between the stator main poles and the auxiliary poles are stator slots of the stator core; each stator main pole is wound with an armature winding for generating a main magnetic flux, and the auxiliary poles are used to provide a return path for the magnetic flux; a plurality of auxiliary excitation permanent magnets are provided and are respectively mounted on the stator slots close to the air gap side to enclose the armature winding in the stator slot; the rotor ring assembly comprises a plurality of rotor cores evenly distributed circumferentially 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, the plurality of auxiliary excitation permanent magnets are evenly distributed on the stator core and do not contact 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 adds auxiliary excitation permanent magnets between the stator main poles and the auxiliary poles to increase the air gap flux density and the magnetic field of the switched reluctance motor during conduction, thereby improving the motor's torque density and power density, while reducing the excitation current of the armature winding and 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, it can also slightly reduce torque ripple.

[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 the auxiliary pole structure and auxiliary excitation permanent magnet to the axial flux motor structure makes it easier to improve the output torque and integrate with the hub. 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 2 is a schematic structural diagram of an axial flux hybrid excitation switched reluctance motor according to an embodiment of the present invention;

[0021] Figure 2 1 is an exploded view of an axial flux 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 according to an embodiment of the present invention;

[0023] Figure 4 Schematic diagram of the structure 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 Schematic diagram of the structure of the auxiliary excitation permanent magnet in an embodiment of the present invention;

[0026] Figure 7 1 is a schematic structural diagram of a rotor core according to 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 hybrid excitation switched reluctance motor, such as Figure 1 As shown, the motor comprises two sets of stator ring assemblies and a rotor ring assembly disposed between the two stator ring assemblies. The rotor ring assemblies are secured to the motor shaft via non-magnetic material. Each stator ring assembly is secured to the motor shaft via a motor bearing. An air gap separates the two sets 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.

[0030] like Figure 2 、 4 As shown, the stator ring assembly includes a stator core 1, auxiliary excitation permanent magnets 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 an alternating pattern. The spaces between the stator main poles 5 and auxiliary poles 6 represent the stator slots of the stator core 1, totaling 12 stator slots. The number and slot type of the stator slots in both stator and rotor assemblies are identical. The armature winding 4 utilizes flat wire direct forming technology to increase the stator slot fill rate.

[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-shaped structure and is used to generate a main magnetic flux. 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 two adjacent left and right auxiliary poles 6; the magnetic flux of each auxiliary pole 6 is approximately 1 / 2 of the stator main pole 5, and the magnetic flux direction is opposite to that of the adjacent stator main pole 5. This shortens the magnetic flux path while increasing the stator slot area without changing the number of stages and volume of the stator and rotor of the switched reluctance motor. 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 motor stator main pole 5, and vice versa, which significantly reduces iron loss and magnetomotive force requirements.

[0034] In one embodiment, a plurality of auxiliary excitation permanent magnets 2 are provided and are respectively installed on the stator slots close to the air gap side. The auxiliary excitation permanent magnets 2, the stator yoke, the stator main pole 5 and the auxiliary pole 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 magnets 2 have a fan-shaped structure and are made of high-performance sintered NdFeB. 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 grouped together, 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-described solution further strengthens the motor's magnetic field and increases the air gap flux density. When the armature winding 4 of a phase of the switched reluctance motor is de-energized, the magnetic flux path near the stator main pole 5 of that 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 that phase is energized, the magnetic field provided by the two adjacent auxiliary excitation permanent magnets 2 of the stator main pole 5 of that phase is added to the main magnetic flux due to the action of direct current. In other words, 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 increasing torque in the early stage without increasing the size 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 stator main pole 5 and the auxiliary pole 6 are all made of soft magnetic composite materials and are die-cast as a whole.

[0038] In one embodiment, the twelve auxiliary excitation permanent magnets 2 are evenly distributed on the stator core 1 and do not contact the rotor core 3 , while the remaining portion is filled with a non-magnetic material fixture. The non-magnetic material fixture is austenitic stainless steel filled between the multiple rotor cores 3 .

[0039] In this embodiment, the number of rotor core stages is 8, which matches the number of stator slots 12 to form a concentrated winding motor structure. By using non-magnetic materials as fixing parts, the electromagnetic mass of the switched reluctance motor is reduced, and the wind resistance during 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 of the auxiliary excitation permanent magnet 2 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 rotor core 3 is the same as that of stator main pole 5, and the core stack length is the same as the width of auxiliary pole 6, that is, 1 / 2 the width of stator main pole 5. The core stack length refers to the axial length of the magnetic path portion of rotor core 3 and can be simply understood as the thickness of rotor core 3. To prevent magnetic flux saturation of the rotor ring assembly material, the rotor core 3 is made of the same material as the stator core 1.

[0042] The present invention increases the air gap flux density and the motor magnetic field during conduction by adding auxiliary excitation permanent magnets 2 between the teeth of the stator main pole 5 and the auxiliary pole 6, thereby making it easier to improve the torque density and power density of the switched reluctance motor, while reducing the excitation current of the armature winding 4 and reducing copper loss; and increasing the average torque; 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 iron loss and magnetomotive force requirements and improving the motor operating efficiency.

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

Claims

1. An axial flux hybrid excitation switched reluctance motor, characterized in that: The invention comprises two sets of stator ring assemblies and a rotor ring assembly arranged between the two stator ring assemblies, wherein an air gap is separated between the stator ring assemblies and the rotor ring assemblies, and the rotor ring assemblies are fixedly connected to the motor shaft, and a bearing is provided between each stator ring assembly and the motor shaft; The stator ring assembly includes a stator core, auxiliary excitation permanent magnets and an armature winding. The stator core has a plurality of stator main poles and auxiliary poles arranged in a staggered manner. The gaps between the stator main poles and the auxiliary poles are stator slots of the stator core. The stator main pole and the auxiliary pole are both fan-shaped, and the pole arc width of the stator main pole is twice the pole arc width of the auxiliary pole; the armature winding is wound on each stator main pole to generate the 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 to enclose the armature winding in the stator slots; the auxiliary excitation permanent magnets are fan-shaped, 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; 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; The rotor ring assembly includes a plurality of rotor cores evenly distributed circumferentially and a non-magnetic material fixing member for connecting the plurality of rotor cores; 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.

2. 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.

3. 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.

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

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