Axial magnetic modulation permanent magnet synchronous motor and driving method thereof

Abstract

The present invention discloses an axially magnetically modulated permanent magnet synchronous motor and a driving method thereof, comprising: a stator, a first rotor and a second rotor; the first rotor and the second rotor are coaxially connected and built into the stator; the first rotor is provided with a first rib structure, the second rotor is provided with a second rib structure, the first rib structure and the second rib structure are staggered at an angle in the axial direction; the end of the first rotor is provided with an inner ring magnetic conductive shaft connected to the first rib structure, the end of the second rotor is provided with an outer ring magnetic conductive shaft connected to the second rib structure and having a radius different from that of the inner ring magnetic conductive shaft, the rib structure of each rotor section and the magnetic conductive shaft connected thereto are of the same polarity, and the polarities between the two rotor sections are opposite, so that the magnetic flux on each rotor section enters the other rotor section along the rib structure and the magnetic conductive shaft connected to the rib structure to form a closed magnetic circuit; the extended ends of the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft are provided with excitation windings to adjust the magnetic flux of the closed magnetic circuit by adjusting the current of the excitation windings.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet synchronous motors, and in particular to an axial magnetization-modulated permanent magnet synchronous motor and a driving method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Permanent magnet motors have significant advantages such as high efficiency, high power density, and high response speed, which have led to their rapid development and widespread application.

[0004] According to the inventors' understanding, existing permanent magnet synchronous motors have the following technical disadvantages:

[0005] While permanent magnet motors offer a range of advantages, the inherent properties of permanent magnet materials also make the motor's air gap magnetic field difficult to adjust. When used in electric equipment such as electric vehicles and high-speed cutting systems, their speed is affected by the air gap magnetic field regulation capability and bus voltage, preventing them from maintaining a wide speed regulation range and constant power operation. When used in renewable energy generation systems such as wind and wave power, fluctuations in the load and renewable energy sources can make it difficult for the generator to maintain constant voltage operation. When used in systems requiring high reliability, the limited fault demagnetization capability of permanent magnet motors cannot meet practical requirements. Traditional permanent magnet motors often employ a control strategy that applies a demagnetization current to the motor's direct axis to achieve air gap magnetic field regulation. While this method can compensate for the shortcomings of permanent magnet motors to a certain extent, it does not fundamentally resolve the problem. Furthermore, incorrect or excessive direct axis demagnetization control in permanent magnet motors can lead to even more serious problems.

[0006] Hybrid excitation is an application form that effectively combines the advantages of permanent magnet motors and electromagnetic excitation motors and makes up for their disadvantages as much as possible. Its advantages are as follows:

[0007] 1. It can effectively improve the operating speed range of the permanent magnet motor electric drive system and broaden the constant power operating range of the motor;

[0008] 2. Improve the operating efficiency of the electric drive system and reduce the system's magnetic adjustment operation loss;

[0009] 3. Improve the anti-disturbance capability of power generation systems and promote the development of the new energy industry;

[0010] 4. Add motor excitation port to help improve the power of the drive system;

[0011] 5. Enhance the system's multi-redundancy operation capability and provide fault-tolerant operation guarantee

[0012] Despite the aforementioned advantages, hybrid-excitation permanent magnet synchronous motors require adding electric excitation windings to the already high-precision, highly integrated permanent magnet motor and constructing a suitable magnetic field circuit. This requires significant structural changes to the permanent magnet motor and the use of more excitation windings. This adjustment can degrade the motor's electromagnetic performance, affect its ability to regulate magnetic flux, and significantly increase motor manufacturing costs and the difficulty of mass production. Summary of the Invention

[0013] In order to solve the above problems, the present invention proposes an axially magnetically modulated permanent magnet synchronous motor and a driving method thereof. The magnetic flux on each rotor section enters the other rotor section along the rib structure and the magnetic conductive shaft connected to the rib structure, forming a closed magnetic circuit. The magnetic flux of the closed magnetic circuit is adjusted by adjusting the current of the excitation winding, thereby flexibly realizing magnetic flux regulation.

[0014] In order to achieve the above object, the present invention adopts the following technical solutions:

[0015] In a first aspect, the present invention provides an axially-magnetically-adjustable permanent magnet synchronous motor, comprising: a stator, a first rotor, and a second rotor;

[0016] The first rotor and the second rotor are coaxially connected and built into the stator;

[0017] The yoke of the first rotor is provided with a first rib structure, and the yoke of the second rotor is provided with a second rib structure, the first rib structure and the second rib structure are staggered in the axial direction and form a staggered angle;

[0018] An inner ring magnetic conductive shaft connected to the first rib structure is provided at the end of the first rotor, and an outer ring magnetic conductive shaft connected to the second rib structure and having a different radius from the inner ring magnetic conductive shaft is provided at the end of the second rotor. The rib structure of each rotor section and the magnetic conductive shaft connected thereto have the same polarity, while the polarity between the two rotor sections is opposite, so that the magnetic flux on each rotor section enters the other rotor section along the rib structure and the magnetic conductive shaft connected to the rib structure, forming a closed magnetic circuit.

[0019] The extended ends of the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft are provided with excitation windings so as to adjust the magnetic flux of the closed magnetic circuit by adjusting the current of the excitation windings.

[0020] As an optional implementation, the number of the first rib structures and the second rib structures are consistent with the number of motor pole pairs.

[0021] As an optional implementation, the staggered angle is 360 / 2p degrees, where p is the number of motor pole pairs.

[0022] As an optional embodiment, the rib structure of each rotor segment is connected to the N pole or S pole of the corresponding rotor segment.

[0023] As an optional embodiment, the first rotor and the second rotor are both provided with rotor slots, and permanent magnets are provided in the rotor slots. The magnetic flux generated by the permanent magnets forms the main magnetic circuit of the motor and the motor magnetic adjustment circuit, and the main magnetic circuit of the motor and the motor magnetic adjustment circuit are connected in parallel.

[0024] As an optional embodiment, the stator is coaxially arranged with the first rotor and the second rotor, and an air gap is provided between the stator and the rotor. The magnetic flux generated by the permanent magnet enters the air gap to form the main magnetic circuit of the motor.

[0025] As an optional embodiment, the inner ring magnetic shaft and the outer ring magnetic shaft extend to one side of the rotor end, and the magnetic shaft is closed on the side of the extended rotor end, so that magnetic flux passes between the rib structure of the two sections of the rotor and the magnetic shaft, forming a motor magnetic regulation magnetic circuit.

[0026] As an optional implementation, when the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft extend to one side of the rotor end, an excitation winding is provided in the air gap between the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft.

[0027] As an optional implementation method, when a weak magnetic current is applied to the excitation winding, the magnetic flux of the closed magnetic circuit is increased, and the main magnetic flux of the motor flowing through the air gap between the stator and rotor is reduced, thereby realizing weak magnetic operation; when a magnetizing current is applied to the excitation winding, the main magnetic flux per pole of the motor is increased, thereby realizing magnetizing operation.

[0028] In a second aspect, the present invention provides a driving method for an axially-magnetically-adjustable permanent-magnet synchronous motor, which is applied to the axially-magnetically-adjustable permanent-magnet synchronous motor described in the first aspect, comprising:

[0029] The motor main magnetic circuit and the motor magnetic adjustment magnetic circuit are operated in parallel. The motor main magnetic circuit is formed by the magnetic flux generated by the permanent magnets entering the air gap between the stator and the rotor to form the motor main magnetic circuit. The motor magnetic adjustment magnetic circuit is a closed magnetic circuit formed after the magnetic flux on each rotor section enters the other rotor section along the rib structure and the magnetic conductive shaft connected to the rib structure;

[0030] When the motor starts or operates normally, the magnetizing current is applied through the excitation winding according to the torque requirement, which reduces the magnetic flux generated by the permanent magnet in the closed magnetic circuit and increases the magnetic flux in the main magnetic circuit of the motor;

[0031] When the motor is running in weak magnetic field, the current of the excitation winding is reduced, the magnetic flux of the closed magnetic circuit is increased, and the magnetic flux of the main magnetic circuit of the motor is reduced.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention proposes an axially magnetically modulated permanent magnet synchronous motor and a driving method thereof. The rotor consists of two rotor sections, each of which is provided with an interlaced rib structure and connected to the magnetic shaft of the rotor end shaft. The ribs of the two rotor sections are staggered by 360 / 2p degrees, so that the polarity of the ribs of each rotor section and the magnetic shaft is opposite to the polarity of the ribs of the other rotor section and the magnetic shaft. The magnetic shafts of the two rotor sections extend beyond the motor end and are closed externally. The magnetic flux of one rotor section can enter the other rotor section along the "rotor rib-magnetic shaft" and form a closed loop. An excitation winding is placed in the air gap between the closed ends of the inner and outer ring magnetic shafts of the motor. The excitation winding can apply current to control the amount of magnetic flux passing through the "rotor rib-magnetic shaft", thereby controlling the magnetic flux of each pole of the rotor and achieving flux regulation.

[0034] The rotor end shaft of the motor of the present invention uses magnetic guide shafts of varying radii to direct the leakage magnetic flux out of the motor end. This minimizes the space occupied by the hybrid magnetic circuit branch, making the magnetic modulation structure design easy to implement. The rotor is a conventional spoke-type permanent magnet rotor, employing only a segmented structure. This motor's manufacturing process is simple and easy to manufacture, resulting in lower structural complexity and manufacturing costs than existing hybrid excitation permanent magnet motors. Furthermore, the motor of the present invention mechanically positions the hybrid excitation winding outside the motor end, resulting in a well-integrated mechanical structure suitable for operation under various complex operating conditions, including high loads and high speeds.

[0035] The air gap between the inner and outer magnetic shafts at the rotor end of the motor of the present invention can be provided with an excitation winding capable of applying current. By controlling the magnitude and direction of the current applied to the excitation winding, the magnitude of the motor's main magnetic flux can be controlled. Through reasonable design, the excitation winding can be de-energized when the motor is operating under rated conditions, significantly reducing excitation losses at the motor's rated operating point and helping to improve the motor's operating efficiency. Furthermore, the closed portion of the inner and outer magnetic shafts at the motor end and their excitation windings can be designed as mechanically movable elements. When the motor is in normal operation and does not require field weakening or magnetizing adjustment, the closed magnetic circuit is cut off by the mechanically movable device, further increasing the motor's main magnetic flux and improving the motor's energy density and power output.

[0036] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0038] Figure 1 A schematic diagram of the stator structure provided in Example 1 of the present invention;

[0039] Figure 2 A schematic diagram of the rotor magnetic adjustment end surface structure provided in Example 1 of the present invention;

[0040] Figure 3 A schematic diagram of the non-magnetic end face structure of the rotor provided in Example 1 of the present invention;

[0041] Among them, 1. first rotor, 2. permanent magnet, 3. first rib structure, 4. inner ring magnetic shaft, 5. second rotor, 6. outer ring magnetic shaft, 7. second rib structure, 8. excitation winding, 9. connecting end face of inner and outer ring magnetic shafts, 10. stator, 11. armature winding, 12. stator teeth, 13. stator slots. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0045] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0046] Example 1

[0047] This embodiment provides an axially-magnetically-adjustable permanent magnet synchronous motor, comprising: a stator 10, a first rotor 1 and a second rotor 5;

[0048] The first rotor 1 and the second rotor 5 are coaxially connected and built into the stator 10;

[0049] The yoke of the first rotor 1 is provided with a first rib structure 3, and the yoke of the second rotor 5 is provided with a second rib structure 7. The first rib structure 3 and the second rib structure 7 are staggered in the axial direction and form a staggered angle.

[0050] The end of the first rotor 1 is provided with an inner ring magnetic conductive shaft 4 connected to the first rib structure 3, and the end of the second rotor 5 is provided with an outer ring magnetic conductive shaft 6 connected to the second rib structure 7 and having a different radius from the inner ring magnetic conductive shaft 4. The rib structure of each rotor section and the magnetic conductive shaft connected thereto have the same polarity, while the polarity between the two rotor sections is opposite, so that the magnetic flux on each rotor section enters the other rotor section along the rib structure and the magnetic conductive shaft connected to the rib structure, forming a closed magnetic circuit;

[0051] The extended ends of the inner ring magnetic conductive shaft 4 and the outer ring magnetic conductive shaft 6 are provided with excitation windings 8 so as to adjust the magnetic flux of the closed magnetic circuit by adjusting the current of the excitation windings 8 .

[0052] In this embodiment, the first rotor 1 and the second rotor 5 are built into the stator 10 and are coaxially placed with the stator 10;

[0053] As an optional embodiment, Figure 1 As shown, the stator 10 is formed by laminating silicon steel sheets. The stator 10 includes stator slots 13 , stator teeth 12 and a stator yoke. The armature winding 11 is placed in the stator slots 13 .

[0054] As an optional implementation, the armature winding 11 may be a single-layer winding or a double-layer winding.

[0055] As an optional implementation, the armature winding 11 can be divided into a distributed winding, a concentrated winding or a lapped winding.

[0056] As an optional implementation, the number of poles of the armature winding 11 is consistent with the number of rotor poles.

[0057] As an optional embodiment, the stator and the rotor are coaxial, and there is an air gap between the stator and the rotor. A portion of the magnetic flux generated by the rotor passes through the outer diameter of the rotor into the air gap to form the main pole magnetic flux of the rotor.

[0058] As an optional implementation manner, the number of phases m of the motor is ≥3, and the number of pole pairs p of the motor is ≥1.

[0059] In this embodiment, the first rotor 1 and the second rotor 5 have the same structure and are coaxially connected. Each rotor yoke is provided with p rib structures, where p is the number of motor pole pairs; and the staggered angle of the rib structures between the two rotor sections is related to the number of pole pairs, which is 360 / 2p degrees. The rib structure of each rotor section is respectively connected to the N pole or S pole of the corresponding rotor section, so that the rib structure of the rotor section and the magnetic conductive axis connected thereto have the same polarity, and the rib structures and the magnetic conductive axes of the two rotor sections have opposite polarities.

[0060] As an optional embodiment, the first rotor and the second rotor are both built-in spoke-type permanent magnet rotors.

[0061] As an optional embodiment, both the first rotor 1 and the second rotor 5 have rotor slots, and permanent magnets 2 are placed in the rotor slots. The permanent magnets 2 are arranged in series and parallel combination to achieve a "magnetic focusing effect" to form radial magnetic poles in the radial direction of the rotor. The magnetic flux generated by the permanent magnets can enter the air gap radially, and the rotor can generate eddy currents when the motor starts, thereby achieving self-starting.

[0062] As an optional embodiment, the first rotor 1 and the second rotor 5 can be made of laminated silicon steel sheets, or made of soft magnetic composite materials with high magnetic permeability, or made of a mixture of silicon steel sheets and soft magnetic composite materials.

[0063] As an optional embodiment, both the first rotor 1 and the second rotor 5 are solid rotors, and the solid rotor has high magnetic permeability.

[0064] As an optional embodiment, the permanent magnet 2 can be made of high-performance permanent magnet materials, such as neodymium iron boron, rare earth cobalt, etc., or low-coercivity permanent magnet materials, such as aluminum nickel cobalt or ferrite.

[0065] In this embodiment, the inner ring magnetic axis 4 and the outer ring magnetic axis 6 have different radii and extend to one side of the rotor end. The magnetic axis is closed on the side of the extended end, so that magnetic flux passes between the rib structure and the magnetic axis of the two rotor sections. Since the polarity between the two rotor sections is opposite, the magnetic flux of the two rotor sections with different polarities is drawn to the rotor end and closed at the end, so that the magnetic flux generated by the permanent magnet on each rotor section enters the other rotor section along the "rib structure-magnetic axis", forming a closed magnetic circuit.

[0066] In this embodiment, when the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft extend to one side of the rotor end, an annular inner and outer ring magnetic conductive shafts with an air gap space are formed, and an excitation winding is provided in the air gap between the annular inner and outer ring magnetic conductive shafts. By adjusting the current of the excitation winding, the magnetic flux of the closed magnetic circuit can be adjusted, thereby controlling the magnetic flux flowing through the "rib structure-magnetic conductive shaft", thereby controlling the magnetic flux of each pole and realizing the purpose of mixed excitation of the motor.

[0067] In this embodiment, the magnetic flux generated by the rotor permanent magnet is divided into two parts. One part passes through the outer diameter of the rotor and enters the air gap to form the main pole magnetic flux of the rotor. The other part forms a closed magnetic circuit through the staggered rib structure and the inner and outer ring magnetic shafts. The inner and outer ring magnetic shafts have different polarities, and an excitation winding is arranged between the air gaps. By changing the current size and direction of the excitation winding, the size of the magnetic flux generated by the permanent magnet passing through the rib structure can be controlled, thereby controlling the magnetic flux of each pole of the motor and realizing mixed excitation of the motor.

[0068] As an optional embodiment, the excitation winding is placed in a closed structure at the end of the magnetically conductive shaft and is a stationary winding. During normal motor operation, the excitation winding can be energized with no current or with a magnetizing current. When the magnetizing current is energized, the motor's main magnetic flux increases, achieving magnetizing operation. When the field-weakening current is energized, the motor's main magnetic flux decreases, achieving field-weakening operation.

[0069] In this embodiment, the magnetic flux generated by the permanent magnet forms two magnetic circuits on the rotor through the "magnetic focusing effect". The first magnetic circuit includes the stator-rotor air gap and the stator, which is the main magnetic circuit of the motor; the other magnetic circuit includes the rotor ribs, the rotor magnetic shaft and the connecting end face of the magnetic shaft, which is the motor magnetic adjustment magnetic circuit. The two magnetic circuit branches are in parallel.

[0070] like Figure 2-Figure 3 As shown, this embodiment takes a motor with 3 phases, 48 ​​stator teeth, 8 rotor slots, 8 ribs in two rotor sections, 16 permanent magnet blocks, and 8 rotor poles as an example. The rotor includes two sections of the same structure, a first rotor 1 and a second rotor 5, which are coaxially connected.

[0071] The first rotor 1 is provided with a first rib structure 3, and the first rib structure 3 is connected to the inner ring magnetic shaft 4;

[0072] The second rotor 5 is provided with a second rib structure 7, and the second rib structure 7 is connected to the outer ring magnetic shaft 6;

[0073] The staggered angle between the second rib structure 7 and the first rib structure 3 is 360 / 2p degrees. In this embodiment, taking an 8-pole motor as an example, the staggered angle is 45 degrees, thereby forming a staggered rib structure on the rotor end shaft.

[0074] Each rotor section has 8 rotor slots for placing permanent magnets 2. The magnetization directions of two adjacent permanent magnets 2 are opposite. The two adjacent permanent magnets 2 and the rotor core between them generate radial magnetic poles in the radial direction. The magnetic flux generated by the permanent magnets 2 passes through the radial magnetic poles and the air gap into the stator core and interlinks with the armature winding to form the main magnetic flux.

[0075] The inner ring magnetic shaft 4 and the outer ring magnetic shaft 6 extend beyond the end face of the motor to form an inner and outer ring magnetic shaft connecting end face 9, and an excitation winding 8 is provided in the air gap between the inner ring magnetic shaft 4 and the outer ring magnetic shaft 6; since the rib structures of the two rotor sections and their corresponding magnetic shafts have opposite magnetic polarities, a portion of the magnetic flux of each rotor section passes through the rib structure, the magnetic shaft and the magnetic shaft connecting end face into the other rotor section, forming a closed magnetic circuit.

[0076] When the motor is running, current is applied to the excitation winding 8 to reduce the magnetic flux in the "rib structure-magnetic axis" magnetic circuit branch. At this time, most of the magnetic flux generated by the permanent magnet enters the stator 10 to form the main magnetic flux of the motor, so that the magnetic flux per pole of the motor is maintained at a high level.

[0077] Alternatively, a weak magnetic current can be applied to the excitation winding 8. At this time, more magnetic flux passes through the staggered rib structure, the magnetic shaft and the magnetic shaft connecting end face 9 to form a closed magnetic circuit. The magnetic flux passing through the stator and rotor air gap is reduced, thereby reducing the main magnetic flux of the motor, thereby realizing weak magnetic control and widening the constant power operation area of ​​the motor. It can be seen that hybrid excitation of the motor can be achieved through the excitation winding.

[0078] In this embodiment, the motor's main magnetic flux is dynamically adjusted during operation by applying a magnetizing current to the excitation winding, thereby achieving magnetic flux control. When energized, the excitation winding controls the amount of magnetic flux generated by the permanent magnets flowing through the rotor ribs, thereby indirectly controlling the main magnetic flux per rotor pole and achieving hybrid excitation.

[0079] When the permanent magnet synchronous motor is working, when the motor is no-load and no current is flowing, part of the magnetic flux generated by the permanent magnet passes through the radial magnetic poles and the air gap into the stator core and interlinks with the armature winding to form the main magnetic flux. The other part forms a closed magnetic circuit through the rib structure, magnetic axis, etc. The magnetic flux passing through the "rib structure-magnetic axis" can be controlled by the current size and direction of the excitation winding.

[0080] When the motor is running under load, after current is applied to the stator winding, the main magnetic flux generated by the permanent magnets on the motor's rotor and the armature winding generate a driving torque, and the motor rotor begins to rotate. At the same time, current can be applied to the current winding in the middle of the magnetic shaft at the end of the motor rotor, which can achieve two effects: magnetization operation or weak magnetic speed expansion operation, effectively widening the operating range of the motor and realizing hybrid excitation of the motor.

[0081] When the motor starts running, a magnetizing current is applied through the excitation winding to "magnetize" each magnetic pole of the motor, increasing the main magnetic flux of each pole of the motor during the starting process and improving the starting ability of the motor;

[0082] When the motor runs at high speed, the current of the excitation winding is reduced, and the flow of permanent magnet flux in the motor's "rib-magnetic shaft" structure is increased, thereby reducing the motor's main magnetic flux flowing through the stator and rotor air gap, achieving weak magnetic speed expansion, and effectively expanding the motor's constant power operating range.

[0083] In actual application of the motor, various performances can be achieved by rationally designing various parameters of the motor, such as the air gap length, the number of turns of the stator armature winding, and the number of turns of the rotor built-in current winding, according to the rated speed, rated torque and specific performance requirements of the motor.

[0084] Example 2

[0085] This embodiment provides a driving method for the axially-magnetically modulated permanent magnet synchronous motor described in Example 1. Current applied to the stator armature winding interacts with the rotor's main magnetic field to generate driving torque. The excitation winding between the inner and outer ring magnetic shafts at the end achieves hybrid excitation by regulating the magnetic flux of the "rib structure-magnetic shaft" branch. Specifically, the method includes:

[0086] When the motor is starting or operating normally, the excitation winding between the inner and outer ring magnetic shafts at the rotor end can apply magnetizing currents of different amplitudes according to the torque requirements, reducing the flow of magnetic flux generated by the permanent magnets in the staggered rib structure of the rotor yoke, so that the main magnetic flux per pole in the radial direction of the motor reaches a higher value;

[0087] When the motor needs to operate in field weakening mode, the current in the excitation winding between the inner and outer ring magnetic shafts at the rotor end is reduced, so that more of the magnetic flux generated by the permanent magnet passes through the "rib structure-magnetic shaft" structure, thereby reducing the radial main magnetic flux of the motor and achieving the effect of field weakening and speed expansion;

[0088] At the same time, the motor can operate without applying excitation winding current between the inner and outer ring magnetic shafts at the rotor end. At this time, part of the magnetic flux generated by the permanent magnet passes through the "rib structure-magnetic shaft" to form a closed magnetic circuit, and part constitutes the main magnetic flux of the motor. The operation mode at this time is the same as that of an ordinary motor.

[0089] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. An axially-magnetic permanent magnet synchronous motor, characterized in that: include: a stator, a first rotor, and a second rotor; The first rotor and the second rotor are coaxially connected and built into the stator; The yoke of the first rotor is provided with a first rib structure, and the yoke of the second rotor is provided with a second rib structure, the first rib structure and the second rib structure are staggered in the axial direction and form a staggered angle; An inner ring magnetic conductive shaft connected to the first rib structure is provided at the end of the first rotor, and an outer ring magnetic conductive shaft connected to the second rib structure and having a different radius from the inner ring magnetic conductive shaft is provided at the end of the second rotor. The rib structure of each rotor section and the magnetic conductive shaft connected thereto have the same polarity, while the polarity between the two rotor sections is opposite, so that the magnetic flux on each rotor section enters the other rotor section along the rib structure and the magnetic conductive shaft connected to the rib structure, forming a closed magnetic circuit. The extended ends of the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft are provided with excitation windings, so as to adjust the magnetic flux of the closed magnetic circuit by adjusting the current of the excitation windings; The number of the first rib structure and the second rib structure is consistent with the number of motor pole pairs; The first rotor and the second rotor are both provided with rotor slots, and permanent magnets are provided in the rotor slots. The magnetic flux generated by the permanent magnets forms a main magnetic circuit of the motor and a magnetic circuit of the motor, and the main magnetic circuit of the motor and the magnetic circuit of the motor are connected in parallel; The inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft extend to one side of the rotor end, and the magnetic conductive shaft is closed on the side of the extended rotor end, so that magnetic flux passes between the rib structure of the two sections of the rotor and the magnetic conductive shaft, forming a magnetic circuit for motor magnetic regulation; When the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft extend to one side of the rotor end, an excitation winding is provided in the air gap between the inner ring magnetic conductive shaft and the outer ring magnetic conductive shaft.

2. The axially-magnetic permanent magnet synchronous motor according to claim 1, characterized in that: The staggered angle is 360 / 2p degrees, where p is the number of motor pole pairs.

3. The axially-magnetic permanent magnet synchronous motor according to claim 1, characterized in that: The rib structure of each rotor segment is connected to the N pole or S pole of the corresponding rotor segment.

4. The axially-magnetic permanent magnet synchronous motor according to claim 1, characterized in that: The stator is coaxially arranged with the first rotor and the second rotor, and an air gap is provided between the stator and the rotor. The magnetic flux generated by the permanent magnet enters the air gap to form the main magnetic circuit of the motor.

5. The axially-magnetic permanent magnet synchronous motor according to claim 1, characterized in that: When a weakening magnetic current is applied to the field winding, the magnetic flux of the closed magnetic circuit is increased, and the main magnetic flux of the motor flowing through the air gap between the stator and rotor is reduced, thus achieving weakening magnetic operation. When the magnetizing current is applied to the excitation winding, the main magnetic flux per pole of the motor is increased, realizing magnetizing operation.

6. A driving method for an axially-magnetically-adjustable permanent magnet synchronous motor, characterized in that: The axially-magnetically-adjustable permanent magnet synchronous motor according to any one of claims 1 to 5 comprises: The motor main magnetic circuit and the motor magnetic adjustment magnetic circuit are operated in parallel. The motor main magnetic circuit is formed by the magnetic flux generated by the permanent magnets entering the air gap between the stator and the rotor to form the motor main magnetic circuit. The motor magnetic adjustment magnetic circuit is a closed magnetic circuit formed after the magnetic flux on each rotor section enters the other rotor section along the rib structure and the magnetic conductive shaft connected to the rib structure; When the motor starts or operates normally, the magnetizing current is applied through the excitation winding according to the torque requirement, which reduces the magnetic flux generated by the permanent magnet in the closed magnetic circuit and increases the magnetic flux in the main magnetic circuit of the motor; When the motor is running in weak magnetic field, the current of the excitation winding is reduced, the magnetic flux of the closed magnetic circuit is increased, and the magnetic flux of the main magnetic circuit of the motor is reduced.

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