CN114825725A - Low-cost axial permanent magnet motor and control system thereof - Google Patents

Abstract

The application provides a low-cost axial permanent-magnet machine and control system thereof relates to motor technical field, and this permanent-magnet machine includes: the rotor comprises a rotating shaft, two rotors arranged on the rotating shaft and a stator positioned between the two rotors; the rotor comprises an end disc, a permanent magnet and a magnetic resistance, wherein the permanent magnet and the magnetic resistance have the same structure and size and are symmetrically arranged on the surface of the end disc to form a surface-mounted rotor; the magnetic poles of two adjacent permanent magnets are opposite and are symmetrical about the center of the rotating shaft. The structure replaces the traditional N-S symmetrical arrangement mode of magnetic poles, the permanent magnets are replaced by magnetic resistances, the cost is reduced, the magnetic circuits are similar and symmetrical, the magnetic resistance torque generated by the magnetic resistances is fully utilized, the torque density is obviously improved under the unit permanent magnet consumption, the magnetic resistances and the permanent magnet mirror images correspond to enable the permanent magnet torque of the motor and the maximum value of a magnetic resistance rotor to be superposed at the same current phase angle, the superposition utilization of the permanent magnet torque and the magnetic resistance torque is realized, and the torque density of the motor is improved.

Description

A low-cost axial permanent magnet motor and its control system

technical field

The application belongs to the technical field of motors, and in particular relates to a low-cost axial permanent magnet motor and a control system thereof.

Background technique

The statements in this section merely provide background information related to the present application and do not necessarily constitute prior art.

In recent years, with the wide application of rare earth permanent magnet materials in motors, the electromagnets in electrically excited synchronous motors have been gradually replaced by permanent magnet materials. Compared with traditional induction motors, permanent magnet synchronous motors have the advantages of small size, light weight, high power density, high torque density, high power factor and high efficiency.

As a type of permanent magnet motor, axial permanent magnet motor, also known as disc permanent magnet motor, has attracted more and more attention due to its compact structure, high efficiency, and high power density. In recent years, the topology of axial permanent magnet motors has been extensively studied to improve torque density, and most of the research has focused on five parts: stator/rotor combination, rotor core, PM arrangement, stator core, and coil layout. Compared with radial-flux motors, axial-flux motors have higher diameter-to-length ratios (compactness) and torque-to-weight ratios (torque density), so they have broad application prospects. However, due to the limitations of motor manufacturing process, permanent magnet material performance, winding configuration technology, drive capacity, etc., the axial magnetic field permanent magnet synchronous motor has not been effectively developed.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present application provides a low-cost axial permanent magnet motor and a control system thereof, which not only have low cost, but also have high torque density and operating efficiency, so that they are suitable for operating conditions.

In order to achieve the above purpose, the technical scheme adopted in the application is as follows:

In a first aspect, an embodiment of the present application provides a low-cost axial permanent magnet motor, including: a rotating shaft, two rotors disposed on the rotating shaft, and a stator located between the two rotors; the rotor includes an end disk, a permanent magnet Magnets and reluctances, the permanent magnets and reluctance have the same structure and size, and are symmetrically arranged on the surface of the end disc to form a surface-mounted rotor; the magnetic poles of two adjacent permanent magnets are opposite and symmetrical about the center of the rotating shaft.

As an optional embodiment, the permanent magnet is a double-sine structure, which is cut from double-sine unequal amplitudes, and the magnetic resistance corresponds to the permanent magnet in structure;

Alternatively, the magnetoresistance can be of the same or nearly the same density as the permanent magnets.

As an optional implementation manner, the stator includes a stator core and a stator winding, and the stator winding is a two-phase winding, which is uniformly wound along the vertical direction of the circumference of the stator core.

As an optional implementation manner, the stator iron core is a hollow iron core in the shape of an annular sleeve, and does not contain stator teeth or their corresponding slots.

As an optional implementation manner, the stator core is formed by axially laminating soft magnetic composite materials.

As an alternative embodiment, a plurality of flat coils are spatially oriented around the stator, and four concentrated windings correspond to the two-phase windings and surround the stator core.

As an optional embodiment, the two-phase windings are arranged in a 180-degree symmetrical arrangement in space, and one phase of the electromagnetic phase leads the other by 90 degrees, which constitutes the electromagnetic phase relationship of the motor.

As an optional embodiment, the rotor further includes a rotor sheath, the rotor sheath is closely attached to the surface of the end disc and is in close contact with the permanent magnet and the magnetic resistance, and its outer diameter is the same as that of the end disc.

As an optional implementation manner, the rotor includes an N-pole permanent magnet reluctance auxiliary rotor and an S-pole permanent magnet reluctance auxiliary rotor; the length of the air gap between the N-pole permanent magnet reluctance auxiliary rotor and the stator is equal to the length of the air gap between the N-pole permanent magnet reluctance auxiliary rotor and the stator. The S-pole permanent magnet reluctance assists the length of the air gap between the rotor and the stator.

In a second aspect, embodiments of the present application further provide a control system for a low-cost axial permanent magnet motor, including the low-cost axial permanent magnet motor according to the first aspect and any optional implementation manner of the first aspect, and A two-phase connection controller, which is used to realize AC/DC conversion of electromechanical energy and control the stator winding of the low-cost axial permanent magnet motor, and the two-phase connection controller is a two-phase six-switch bridge circuit .

The beneficial effects of this application are:

(1) The low-cost axial permanent magnet motor provided by this application has a structure that replaces the traditional N-S symmetrical arrangement of magnetic poles, and replaces the permanent magnets with reluctance to reduce costs. Reluctance torque, the torque density is significantly improved under the unit amount of permanent magnets, and the mirror image of the reluctance and permanent magnets echoes so that the permanent magnet torque of the motor and the maximum value of the reluctance rotor can be superimposed at the same current phase angle, realizing permanent magnetism. The superposition of torque and reluctance torque is utilized to increase the torque density of the motor.

由双正弦不等幅值切割而成，导线切割磁极磁力线的有效面积始终正弦变化，实现磁链和反电动势的正弦化，正弦的气隙场分布以减少涡流损耗，降低气隙磁场谐波，降低转矩脉动和振动噪声，提高运行效率。相应的，磁阻在结构上与永磁体对应，可以降低轴向磁拉力和净轴向力，磁阻使用与永磁体密度相似的材料，能够平衡转子运行转动惯量，降低径向力。(2) The permanent magnet and reluctance of the axial permanent magnet motor are optimized based on the sinusoidal curve. The permanent magnet adopts a double sinusoidal structure. The outer sinusoidal curve is defined as Asinθ, the inner sinusoidal curve is defined as Bsinθ, and the magnetic pole area is:

It is cut from double sine with unequal amplitude. The effective area of the magnetic field lines of the wire cutting magnetic poles always changes sinusoidally, realizing the sinusoidal flux linkage and back electromotive force. The sinusoidal air gap field distribution can reduce the eddy current loss and reduce the harmonics of the air gap magnetic field. Reduce torque ripple and vibration noise and improve operating efficiency. Correspondingly, the reluctance corresponds to the permanent magnet in structure, which can reduce the axial magnetic pulling force and the net axial force. The reluctance uses a material with a density similar to that of the permanent magnet, which can balance the rotational inertia of the rotor and reduce the radial force.

The double-sine structure permanent magnet-reluctance structure is designed for ease of processing and cost reduction. The permanent magnet corresponds to the reluctance, and the formed rotor magnetic circuit is similar and symmetrical. The introduction of the reluctance rotor relatively reduces the motor torque ripple and improves the permanent The torque that the magnet can output.

(3) The stator winding of the axial flux permanent magnet motor adopts two-phase windings, the two-phase windings are concentrated, and the rectangular cross-section flat copper wire is used to increase the effective area of the wire and the air gap. The end windings are short and copper The loss is low and the structure is simple, and the air-gap magnetic field modulation is more concise and ideal.

而两相六开关电桥的开关管功率要求：

两相控制器在功率器件上要求更低。(4) The stator winding of the axial flux permanent magnet motor is controlled by a two-phase connection controller. The switches controlled by the three-phase winding connection need to be controlled at the same time. The third-phase independent switch shared by the controller windings of the two-phase connection can be independently controlled. Control, not disturbed by the first two-phase switch. Under the condition that the wire resistance of the overall winding remains unchanged, each phase of the three-phase winding is assigned a rated current I, and each phase of the two-phase winding is assigned a rated current of 1.5I, and the three-phase and two-phase concentrated windings generate the same average torque. In addition, the operating power requirements of the switching tube of the three-phase six-switch bridge are:

The power requirements of the switch tube of the two-phase six-switch bridge are:

The two-phase controller has lower requirements on the power device.

(5) The stator of the axial permanent magnet motor adopts a hollow stator, which reduces the use of stator materials, and at the same time can eliminate the cogging torque, reduce the axial magnetic force, and reduce the loss of the stator core.

Description of drawings

The accompanying drawings forming a part of the present application are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

1 is a schematic diagram of a structural explosion of a low-cost axial permanent magnet motor provided by an embodiment of the present invention;

2 is a schematic diagram of a stator structure and a phase distribution of windings provided by an embodiment of the present application;

3 is a schematic cross-sectional view of a stator 1/2 provided by an embodiment of the present application;

4 is a schematic topology diagram of a stator control circuit provided by an embodiment of the present application;

5 is a schematic structural diagram of an N-pole permanent magnet reluctance auxiliary rotor provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram of an S-pole permanent magnet reluctance auxiliary rotor provided by an embodiment of the present application.

Reference signs: 1. S-pole permanent magnet reluctance auxiliary rotor; 1-1, S-pole double-sine structure permanent magnet; 1-2, S-pole double-sine structure reluctance; 1-3, S-pole permanent magnet reluctance auxiliary Rotor end disc; 1-4, S pole permanent magnet reluctance auxiliary rotor sheath; 2, N pole permanent magnet reluctance auxiliary rotor; 2-1, N pole double sine structure permanent magnet; 2-2, N pole double sine Structural reluctance; 2-3, N pole permanent magnet reluctance auxiliary rotor end plate; 2-4, N pole permanent magnet reluctance auxiliary rotor sheath; 3, stator; 3-1, stator core; 3-2, stator Winding; 4, shaft.

Detailed ways

The present application will be further described below with reference to the accompanying drawings and embodiments.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

Based on this, the present application provides a low-cost axial permanent magnet motor, which not only has low cost but also has high operating efficiency and torque density, and is suitable for various operating conditions.

Please refer to FIG. 1. FIG. 1 is a schematic exploded view of the structure of a low-cost axial permanent magnet motor provided by an embodiment of the present invention. As shown in FIG. 1, the low-cost axial permanent magnet motor includes: a rotating shaft 4, and a set of The two rotors on the rotating shaft 4 and the stator 3 between the two rotors; the rotors include end discs, permanent magnets and reluctance, the permanent magnets and reluctance have the same structure and size, and are symmetrically arranged in A surface-mounted rotor is formed on the surface of the end disc; the magnetic poles of the two adjacent permanent magnets are opposite and symmetrical about the center of the rotating shaft.

In the specific implementation, the two rotors are the S pole permanent magnet reluctance auxiliary rotor 1 and the N pole permanent magnet reluctance auxiliary rotor 2 respectively, and the stator 3 is located in the S pole permanent magnet reluctance auxiliary rotor 1 and the N pole permanent magnet reluctance auxiliary rotor 1. between rotors 2. The rotor is an axial double-layer structure, including a rotating shaft 4, rotor end disks 1-3, 2-3 fixed on the rotating shaft, permanent magnets and reluctance have the same structure and size, and are symmetrically arranged on the surface of the end disk. Surface-mounted rotor; the poles of two adjacent permanent magnets are opposite and symmetrical about the center of the rotating shaft.

This application reduces the cost by replacing the permanent magnets with reluctance, and at the same time, the magnetic circuit is similar and symmetrical, making full use of the reluctance torque generated by the reluctance, and significantly improving the torque density per unit of permanent magnet consumption, and the reluctance and permanent magnet mirror image The mutual response enables the permanent magnet torque of the motor and the maximum value of the reluctance rotor to be superimposed at the same current phase angle, realizing the superposition and utilization of the permanent magnet torque and the reluctance torque, thereby improving the torque density of the motor.

In the embodiment of the present application, as an optional embodiment, the permanent magnet is a double sinusoidal structure, and the magnetic resistance corresponds to the permanent magnet in structure;

Alternatively, the magnetoresistance can be of the same or nearly the same density as the permanent magnets.

磁阻在结构上与永磁体对应，由双正弦不等幅值切割而成，导线切割磁极磁力线的有效面积始终正弦变化，实现磁链和反电动势的正弦化，正弦的气隙场分布以减少涡流损耗，降低气隙磁场谐波，降低转矩脉动和振动噪声，提高运行效率。如图2和图3中所示，S极双正弦结构永磁体1-1、S极双正弦结构磁阻1-2、N极双正弦结构永磁体2-1、N极双正弦结构磁阻2-2采用基于双正弦结构的正弦化设计，紧贴在相应S极永磁磁阻辅助转子端盘1-3、N极永磁磁阻辅助转子端盘2-3的表面上，S极双正弦结构永磁体1-1关于N极双正弦结构磁阻2-2镜像对称，N极双正弦结构永磁体2-1关于S极双正弦结构磁阻1-2镜像对称。In the specific implementation, the permanent magnet adopts a double sine structure, and the outer sine curve is defined as Asinθ, the inner sine curve is Bsinθ, and the magnetic pole area is:

The magnetoresistance corresponds to the permanent magnet in structure, and is cut by double sine with unequal amplitude. The effective area of the magnetic field line of the wire cutting magnetic pole always changes sinusoidally, realizing the sinusoidal flux linkage and back electromotive force, and the sinusoidal air gap field distribution to reduce Eddy current loss, reduce air gap magnetic field harmonics, reduce torque ripple and vibration noise, and improve operating efficiency. As shown in FIG. 2 and FIG. 3 , S-pole double-sine structure permanent magnet 1-1, S-pole double-sine structure magnetoresistance 1-2, N-pole double-sine structure permanent magnet 2-1, N-pole double-sine structure magnetoresistance 2-2 adopts the sinusoidal design based on the double sine structure, and is closely attached to the surface of the corresponding S-pole permanent magnet reluctance auxiliary rotor end plate 1-3 and N-pole permanent magnet reluctance auxiliary rotor end plate 2-3. The double-sine structure permanent magnet 1-1 is mirror-symmetrical about the N-pole double-sine structure reluctance 2-2, and the N-pole double-sine structure permanent magnet 2-1 is mirror-symmetric about the S-pole double-sine structure magnetoresistance 1-2.

In the embodiment of the present application, as an optional embodiment, the stator includes a stator core and a stator winding, and the stator winding is a two-phase winding, which is evenly wound along the vertical direction of the circumference of the stator core; The stator core is a hollow core in the shape of a ring sleeve, and does not contain stator teeth or their corresponding slots. Optionally, the stator core is formed by axially laminating soft magnetic composite materials; optionally, as an optional embodiment, a plurality of flat coils are spatially oriented around the stator, and the four concentrated windings correspond to the two-phase windings. around the stator core.

In a specific implementation, as shown in FIG. 4 and FIG. 5 , the stator 3 includes a hollow stator core 3-1 and a stator two-phase winding 3-2. The stator core 3-1 adopts a slotless stator structure and is composed of a soft magnetic composite The material is axially laminated. The stator winding 3-2 is a two-phase winding, and is uniformly wound on the stator core 3-1 along the vertical direction of the circumference of the stator core 3-1 by using flat windings. In the figure, "+" represents the incoming direction of each phase winding, "-" represents the outgoing direction of each phase winding, A and B respectively represent the two phases of stator winding 3-2, and each phase is separated by a 90° mechanical angle. The distribution form in each phase of the stator winding 3-2 can be changed, and the distribution of each phase winding here is only used for illustration.

Here, the stator iron core is a circular sleeve-shaped hollow iron core, which does not contain stator teeth or their corresponding slots, that is, a slotless stator structure, which can eliminate cogging torque and effectively reduce vibration noise; the stator winding adopts two-phase winding, two The phase winding is centrally wound, and the flat copper wire with rectangular cross-section is used, which can increase the effective area of the wire and the air gap, and the air gap magnetic field modulation is more ideal. The stator winding adopts flat winding to make the end smaller, easy to manufacture and winding, and has good heat dissipation performance. In addition, it also has high stiffness, which reduces the vibration and noise of the motor winding, thereby improving the overall performance of the motor. Optionally, the two-phase windings are spatially arranged symmetrically at 180 degrees to constitute the electromagnetic phase relationship of the motor.

In the embodiment of the present application, as an optional embodiment, the rotor further includes a rotor sheath, the rotor sheath is closely attached to the surface of the end disk and is in close contact with the permanent magnet and the magnetic resistance, and the outer diameter of the rotor sheath is the same as that of the end plate. disc is the same.

In a specific implementation, the permanent magnet 1-1 of the S-pole dual-sine structure, the magnetic resistance 1-2 of the S-pole dual-sine structure, the permanent magnet 2-1 of the N-pole dual-sine structure, and the magnetic resistance 2-2 of the N-pole dual-sine structure are respectively fixed On the corresponding S pole permanent magnet reluctance auxiliary rotor sheath 1-4 and N pole permanent magnet reluctance auxiliary rotor sheath 2-4, and close to the corresponding S pole permanent magnet reluctance auxiliary rotor end disk 1-3, On the surface of the N-pole permanent magnet reluctance auxiliary rotor end disk 2-3, the S-pole double-sine structure permanent magnet 1-1 is mirror-symmetrical with respect to the N-pole double-sine structure reluctance 2-2, and the N-pole double-sine structure permanent magnet 2- 1 Mirror symmetry about S-pole double-sine structure magnetoresistance 1-2.

Here, the rotor sheath is installed on the remaining space on the surface of the rotor except the permanent magnet after the shape optimization design, and the structure is compact and does not affect the effective air gap length of the motor.

In the embodiment of the present application, as an optional embodiment, the rotor includes an N-pole permanent magnet reluctance auxiliary rotor and an S-pole permanent magnet reluctance auxiliary rotor; The air gap length is equal to the air gap length between the S-pole permanent magnet reluctance auxiliary rotor and the stator.

The advantages of the above technical solutions are that the permanent magnets are cut from double sinusoidal unequal amplitudes, the effective area of the magnetic field lines of the wire cutting magnetic poles always changes sinusoidally, and the double sinusoidal structure realizes the sinusoidal flux linkage and back electromotive force, reducing the harmonics of the air gap magnetic field. , reduce torque ripple and vibration noise, improve operating efficiency. The reluctance double sine structure design corresponds to the double sine structure permanent magnet in structure, which reduces the axial magnetic pull and net axial force. The reluctance uses materials with a density similar to that of the permanent magnet to balance the rotational inertia of the rotor and reduce the radial force. The permanent magnets are replaced with reluctance to reduce the cost, and the magnetic circuit is similar and symmetrical, making full use of the reluctance torque generated by the reluctance, and the torque density is significantly improved under the unit amount of permanent magnets. The maximum value of the magnetic torque and the reluctance rotor can be superimposed at the same current phase angle, realizing the superposition utilization of the permanent magnet torque and the reluctance torque.

In the embodiment of the present application, the axial magnetic flux structure is adopted, so that the axial effective air gap length is adjustable without being affected by the permanent magnet sheath, the volume is compact, and the heat dissipation performance is superior; the stator adopts a slotless hollow stator structure to eliminate cogging torque and reduce Reduce vibration noise and increase power density; stator winding improves heat dissipation performance and efficiency by using flat wire winding technology; rotor permanent magnet and reluctance are designed to achieve sinusoidal flux linkage and back EMF through shape optimization, so that the motor has low harmonic distortion , low vibration noise, high efficiency and so on.

Embodiments of the present application further provide a control system for a low-cost axial permanent magnet motor, including the above-mentioned low-cost axial permanent magnet motor and a two-phase connection controller, where the two-phase connection controller is used to realize AC/DC conversion of electromechanical energy , control the stator winding of the low-cost axial permanent magnet motor, and the two-phase connection controller is a two-phase six-switch bridge circuit.

而两相六开关电桥的开关管功率要求：

两相控制器在功率器件上要求更低。这里，定子控制电路拓扑示意图如图6中所示，两相连接控制器为两相六开关电桥电路，该电路用于实现机电能量交直流变换，控制低成本轴向永磁电机的定子绕组。In a specific implementation, an important advantage of the two-phase connection controller is that the requirements for the drive circuit are lower. The switches controlled by the three-phase winding connection need to be controlled at the same time, and the third-phase independent switch shared by the two-phase connected controller windings can be independently controlled without interference from the first two-phase switches. Under the condition that the overall wire resistance remains unchanged, the rated current I is allocated to each phase in the three-phase winding, and the two-phase winding is allocated a rated current of 1.5I to each phase, and the three-phase and two-phase concentrated windings generate the same average torque. In addition, the operating power requirements of the switching tube of the three-phase six-switch bridge are:

The power requirements of the switch tube of the two-phase six-switch bridge are:

The two-phase controller has lower requirements on the power device. Here, the topology diagram of the stator control circuit is shown in Figure 6. The two-phase connection controller is a two-phase six-switch bridge circuit, which is used to realize the AC-DC conversion of electromechanical energy and control the stator winding of the low-cost axial permanent magnet motor. .

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. During execution, the processes of the embodiments of the above-mentioned methods may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM), or a random access memory (Random Access Memory, RAM) or the like.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (10)

1. A low cost axial permanent magnet machine, comprising: the rotor comprises a rotating shaft, two rotors arranged on the rotating shaft and a stator positioned between the two rotors; the rotor comprises an end disc, a permanent magnet and a magnetic resistance, wherein the permanent magnet and the magnetic resistance have the same structure and size and are symmetrically arranged on the surface of the end disc to form a surface-mounted rotor; the magnetic poles of two adjacent permanent magnets are opposite and are symmetrical about the center of the rotating shaft.

2. The low cost axial permanent magnet machine of claim 1, wherein said permanent magnets are of a double sinusoidal configuration with magnetic reluctance structurally corresponding to said permanent magnets;

alternatively, the magnetic resistance is made of a material with the same or almost the same density as the permanent magnet.

3. The low cost axial permanent magnet machine of claim 1, wherein said stator comprises a stator core and a stator winding, said stator winding being a two phase winding wound uniformly in a direction perpendicular to the circumference of said stator core.

4. A low cost axial permanent magnet machine according to claim 3, characterized in that said stator core is a toroidal sleeve shaped hollow core without stator teeth or their corresponding slots.

5. The low cost axial permanent magnet machine of claim 4, wherein said stator core is axially laminated from a soft magnetic composite material.

6. The low cost axial permanent magnet machine of claim 3, wherein the plurality of pancake coils are spatially oriented around the stator with four concentrated windings corresponding to two phase windings and surrounding the stator core.

7. The low-cost axial permanent magnet machine of claim 3, wherein the two phase windings are spatially arranged 180 degrees symmetrically, with one phase leading the other by 90 degrees, to form the electromagnetic phase relationship of the machine.

8. The low cost axial permanent magnet machine of claim 1, wherein said rotor further comprises a rotor sheath abutting the surface of the end disk and in intimate contact with the permanent magnets and the reluctance and having an outer diameter the same as the end disk.

9. The low cost axial permanent magnet machine of claim 1, wherein said rotor comprises an N pole permanent magnet reluctance auxiliary rotor and an S pole permanent magnet reluctance auxiliary rotor; and the length of an air gap between the N-pole permanent magnet reluctance auxiliary rotor and the stator is equal to that of an air gap between the S-pole permanent magnet reluctance auxiliary rotor and the stator.

10. A control system for a low cost axial permanent magnet machine, comprising a low cost axial permanent magnet machine according to any of claims 1-9 and a two-phase connection controller for performing electromechanical energy ac/dc conversion to control the stator windings of the low cost axial permanent magnet machine, the two-phase connection controller being a two-phase six-switch bridge circuit.

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