Active magnetic suspension bearing and electro-magnetic flux switching motor

Abstract

The invention discloses an active magnetic suspension bearing which comprises a magnetic bearing rotor core, a control coil, a magnetic bridge and a plurality of magnetic poles, the magnetic poles are mounted on one side of the magnetic bridge, the control coil is wound on the magnetic poles, and the magnetic bearing rotor core is embedded into an annular space formed after the magnetic poles are arranged in the circumferential direction. The magnetic poles and the magnetic bridges form a magnetic bearing stator iron core, and the magnetic bearing rotor iron core rotates relative to the magnetic bearing stator iron core. The invention further discloses an electro-magnetic flux switching motor. According to the invention, a closed radial bias magnetic field main loop is formed, so that the purposes of multi-purpose reuse of the excitation magnetic field of the electro-magnetic flux switching motor and adjustable bias magnetic field of the magnetic suspension bearing are realized; the motor winding end space is fully utilized to reduce the axial length of the magnetic suspension motor system, the dynamic performance of the motor shaft system is improved, and the purposes of high compactness, high integration and component reuse are achieved.

Description

Technical Field

[0001] The present invention relates to the field of motors, and in particular to an active magnetic suspension bearing and an electrically excited magnetic flux switching motor. Background Art

[0002] With the rapid development of modern industry, high-speed and ultra-high-speed motors have been widely used in machine tool processing, impeller machinery, flywheel energy storage, fuel vehicles and other fields. In terms of motor structure, unlike rotor-excited motors, the excitation part of stator-excited motors is located on the stator side of the motor, and there are neither permanent magnets nor windings on the rotor. Therefore, there is no risk of permanent magnets being crushed by centrifugal force and demagnetized by high temperature faced by traditional rotor permanent magnet motors, and there is no disadvantage of low reliability caused by brushes and slip rings required for rotor electromagnetic motors. It overcomes the shortcomings of traditional rotor-excited motors, such as complex structure, high manufacturing cost, complex processing technology, large equivalent air gap, difficult rotor cooling and irreversible demagnetization risk.

[0003] However, the speed regulation range of permanent magnet motors is limited during operation, and is greatly restricted in some application fields that require a wide speed regulation range. The reason is that the inherent characteristics of permanent magnet materials themselves make it impossible to flexibly adjust the air gap magnetic field of permanent magnet motors. The flux switching of the electric excitation structure can achieve the adjustment of the main magnetic field, overcome the disadvantage of the difficulty in adjusting the magnetic field of permanent magnets, and reasonably adjust the DC excitation current, so that the motor can operate in a wide speed range.

[0004] However, the existing stator permanent magnet motor system generally uses mechanical bearings. During use, the mechanical bearings are prone to failure due to long-term mechanical friction, long-term wear, fatigue failure, and lubricant corrosion, which greatly shortens their service life and faces the risk of failure. They cannot operate reliably at high speeds, which limits the reliability of stator permanent magnet motors to a certain extent. Therefore, a high-speed bearing system must be used. In response to the problems caused by traditional mechanical bearings, the industry has proposed the idea of ​​using magnetic suspension bearings to replace traditional bearings such as ball bearings, oil-filled bearings, and air bearings to achieve suspension support for high-speed rotors.

[0005] The existing magnetic bearing and high-speed motor system generally consists of a pair of radial magnetic bearings at both ends of the motor and an axial magnetic bearing at one end of the motor, and then the impeller and other structures are installed on the outside of the magnetic bearing. In addition, the existing systems all treat the magnetic bearing and the motor as independent components without integrated design and control, resulting in the "magnetic bearing + high-speed motor" system being more complex and bulky than the "mechanical bearing + motor" system. The former's excessive shaft length brings about complex rotor dynamics problems, limiting the system's speed increase and wider application. Summary of the invention

[0006] Purpose of the invention: In view of the above problems, the purpose of the present invention is to provide an active magnetic bearing and an electrically excited flux switching motor. By designing the magnetic bearing structure, the integration of the magnetic levitation motor system is improved. At the same time, a certain magnetic pull can be obtained with only a small control current, thereby improving the performance of the magnetic levitation motor system and shortening its overall axial length.

[0007] Technical solution: On the one hand, the present invention provides an active magnetic levitation bearing, including a magnetic bearing rotor core, a control coil, a magnetic bridge and a plurality of magnetic poles, the magnetic poles are installed on one side of the magnetic bridge, the control coil is wound around the magnetic poles, the magnetic bearing rotor core is embedded in the annular space formed by the circumferential arrangement of the magnetic poles, the magnetic poles and the magnetic bridge constitute the magnetic bearing stator core, and the magnetic bearing rotor core rotates relative to the magnetic bearing stator core.

[0008] Furthermore, the magnetic bridge is composed of multiple magnetic units, each magnetic unit includes a circumferential magnetic segment, a yoke connecting segment and two radial magnetic segments, one end of the circumferential magnetic segment is connected to one end of the first radial magnetic segment, the other end of the first radial magnetic segment is connected to one end of the yoke connecting segment, the other end of the yoke connecting segment is connected to one end of the second radial magnetic segment, and the other end of the second radial magnetic segment is connected to the other end of the circumferential magnetic segment in the adjacent magnetic unit, so that the magnetic bridge forms a closed loop.

[0009] Furthermore, the number of magnetic poles is the same as the number of magnetic conductive units, which is 6N, where N is a positive integer.

[0010] Furthermore, the magnetic pole is of T-shaped structure, and the radial outer end of the magnetic pole of the T-shaped structure is in contact with the circumferential magnetic conductive section of the magnetic conductive bridge.

[0011] On the other hand, the present invention provides an electrically excited flux switching motor, including an active magnetic bearing, and also including a motor stator core, a motor rotor core, an excitation winding coil and an armature winding coil. The motor rotor core is arranged inside the motor stator core, and the motor rotor core rotates relative to the motor stator core. The active magnetic bearing is arranged at the ends of the motor stator core and the motor rotor core, and the magnetic bridge is arranged between the magnetic pole and the motor stator core. The teeth of each motor stator core are wound with the excitation winding coil, and the teeth of adjacent motor stator cores are wound with the armature winding coil.

[0012] Furthermore, the motor stator core is a multi-tooth salient pole structure, each tooth has a slot in the center, the armature winding coil is wound on each tooth of the motor stator core, and the excitation winding coil is wound in the slots between two adjacent motor stator core teeth.

[0013] Furthermore, all radial magnetic conductive sections and yoke connecting sections are attached to the stator core of the motor, and each armature winding coil and excitation winding coil bypasses the radial magnetic conductive section and maintains an electrical insulation distance from the magnetic conductive bridge.

[0014] Furthermore, the width of the radial magnetic conductive section is less than or equal to the width of the teeth of the motor stator core, the outer diameter of the circumferential magnetic conductive section is not greater than the inner diameter of the motor stator core, and the inner and outer diameters of the yoke connecting section are respectively equal to the inner and outer diameters of the motor yoke.

[0015] Furthermore, the number of magnetic conductive units is not greater than the number of teeth of the motor stator core.

[0016] Furthermore, the interiors of the magnetic bearing rotor core and the motor rotor core are both hollow structures for mounting the rotating shaft.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0018] 1. The active magnetic bearing proposed in the present invention makes full use of the space at the end of the motor. By reasonably designing the shape and size of the magnetic bearing's magnetic bridge and magnetic poles, the magnetic bearing's stator core can be in good contact with the motor's stator core, thereby introducing the energy of the excitation magnetic field in the electric excitation flux switching motor into the integrated magnetic bearing, providing a bias magnetic field for the magnetic bearing, and realizing the reuse of components of the excitation winding in the electric excitation flux switching motor, thereby realizing the multi-purpose reuse of the excitation magnetic field energy in the stator electric excitation motor, reducing the axial length of the magnetic suspension motor system, improving the dynamic performance of the motor rotor, and achieving the purpose of compact structure of the integrated design of high-speed motor and magnetic suspension bearing.

[0019] 2. The present invention utilizes an energized coil to provide a bias magnetic field for the magnetic bearing. The magnitude of the bias magnetic field of the magnetic bearing can be changed by adjusting the current in the excitation winding coil, thereby adjusting the bias force of the magnetic pole on the magnetic bearing rotor. By adjusting the bias force under different magnetic poles, magnetic pulling forces of different magnitudes and directions are combined, thereby achieving a reduction in control current and driver capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of an active magnetic bearing;

[0021] Figure 2 It is the assembly drawing of each component of active magnetic bearing;

[0022] Figure 3 It is the structural schematic diagram of the magnetic bridge;

[0023] Figure 4 It is a structural schematic diagram of an electrically excited flux switching motor;

[0024] Figure 5 It is a front view of the overall structure of the 6-slot 4-pole electric excitation flux switching motor in the embodiment;

[0025] Figure 6 Schematic diagram of 1 / 3 bias magnetic circuit of 6-slot 4-pole electric excitation flux switching motor in the embodiment;

[0026] Figure 7 A radial view of a 1 / 3 bias magnetic circuit of a 6-slot 4-pole electrically excited flux switching motor in an embodiment;

[0027] Figure 8 It is a half cross-sectional view of the 6-slot 4-pole electromagnetic flux switching motor in the embodiment. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] Embodiment 1

[0030] The active magnetic bearing described in this embodiment has a structural schematic diagram as shown in FIG. Figure 1 to Figure 2 As shown, the magnetic bearing includes a magnetic bearing rotor core 8, a control coil 7, a magnetic bridge 5 and a plurality of magnetic poles 6. The magnetic pole 6 is installed on one side of the magnetic bridge 5. The control coil 7 is wound around the magnetic pole 6. The magnetic bearing rotor core 8 is embedded in an annular space formed by circumferential arrangement of the magnetic poles 6. The magnetic poles 6 and the magnetic bridge 5 constitute a magnetic bearing stator core. The magnetic bearing rotor core rotates relative to the magnetic bearing stator core 8. The interior of the magnetic bearing rotor core 8 is a hollow structure for mounting a rotating shaft.

[0031] To facilitate detailed description of the present invention, a spatial xyz reference coordinate system is established without loss of generality, wherein the xy plane is parallel to the motor end face with a circular cross-section, r is the radial direction of each end face of the motor (hereinafter referred to as radial), each end face circle is the circumferential direction (hereinafter referred to as circumferential), and z is the axial direction of the motor (hereinafter referred to as axial).

[0032] like Figure 3 As shown, the magnetic bridge 5 is composed of a plurality of magnetic conductive units, each of which includes a circumferential magnetic conductive segment 501, a yoke connecting segment 503 and two radial magnetic conductive segments, the two radial magnetic conductive segments being respectively a first radial magnetic conductive segment 502 and a second radial magnetic conductive segment 504. One end of the circumferential magnetic conductive segment 501 is connected to one end of the first radial magnetic conductive segment 502, the other end of the first radial magnetic conductive segment 502 is connected to one end of the yoke connecting segment 503, the other end of the yoke connecting segment 503 is connected to one end of the second radial magnetic conductive segment 504, and the other end of the second radial magnetic conductive segment 504 is connected to the other end of the circumferential magnetic conductive segment in the adjacent magnetic conductive unit, so that the magnetic bridge 5 forms a closed loop.

[0033] The ferromagnetic part of the magnetic bearing is made of silicon steel sheets or materials with good magnetic conductivity.

[0034] When the magnetic poles 6 and the magnetic bridge 5 are used together, the number of the magnetic poles 6 needs to be the same as the number of the magnetic conductive units, which is 6N, where N is a positive integer. In this example, the number of the magnetic poles 6 is 6. The magnetic poles 6 are T-shaped, and the radial outer end of the T-shaped magnetic pole fits the circumferential magnetic conductive section 501 of the magnetic bridge 5.

[0035] Embodiment 2

[0036] like Figure 4 As shown, an electrically excited flux switching motor described in this embodiment includes the active magnetic bearing described in the first embodiment, and also includes a motor stator core 1, a motor rotor core 2, an excitation winding coil 4 and an armature winding coil 3. The motor rotor core 1 is arranged inside the motor stator core 2, and the motor rotor core 1 rotates relative to the motor stator core 2. The active magnetic bearing is arranged at the ends of the motor stator core 1 and the motor rotor core 2, and the magnetic bridge 5 is arranged between the magnetic pole 6 and the motor stator core 1. The teeth of each motor stator core 1 are wound with the excitation winding coil 4, and the teeth of adjacent motor stator cores 1 are wound with the armature winding coil 3. The inside of the magnetic bearing rotor core 8 and the motor rotor core 2 are both hollow structures for mounting the rotating shaft.

[0037] The motor stator core 1 is a multi-tooth salient pole structure, each tooth has a slot in the center, an armature winding coil 3 is wound on each tooth of the motor stator core 1, and an excitation winding coil 4 is wound in the slots between two adjacent motor stator core teeth.

[0038] All radial magnetic conductive sections and the yoke connecting section 503 are attached to the stator core of the motor, and each armature winding coil 3 and excitation winding coil 4 bypasses the radial magnetic conductive section and maintains an electrical insulation distance from the magnetic conductive bridge 5 .

[0039] The width of the radial magnetic conductive section is less than or equal to the width of the motor stator core tooth, the outer diameter of the circumferential magnetic conductive section is not greater than the inner diameter of the motor stator core, and the inner and outer diameters of the yoke connecting section are respectively equal to the inner and outer diameters of the motor yoke. The number of magnetic conductive units is not greater than the number of teeth of the motor stator core.

[0040] In this example, the motor stator core 1 and the motor rotor core 2 are both formed by stacking non-oriented multi-layer silicon steel sheets. The motor stator core 1 is a multi-tooth salient pole structure with a slot in the center of each tooth. The armature winding coil 3 is wound on the tooth of each motor stator core 1, and the excitation winding coil 4 is wound in the slots opened by two adjacent motor stator core teeth. The motor rotor core 2 is located in the middle of the motor stator and has an air gap between it and the motor stator core 1. The motor rotor core 2 can rotate relative to the motor stator.

[0041] The armature winding coil 3 and the excitation winding coil 4 are axially bypassed around the motor stator core 1 and the radial magnetic conductive section, and are used to cooperate with the magnetic pole 6 to introduce the excitation magnetic field into the magnetic suspension bearing, so as to achieve the purpose of switching the motor excitation magnetic field by reusing the electric excitation magnetic flux of the magnetic suspension bearing. The outer radial edge of the magnetic pole 6 is tightly fitted with the circumferential magnetic conductive section 501. A control coil 7 is wound around each magnetic pole 6 of the magnetic suspension bearing. The magnetic bearing rotor core 8 is located in the annular space formed by the uniform distribution of the magnetic poles 6 of the magnetic suspension bearing along the circumferential direction, and can rotate relative to the magnetic bearing stator core 8. The axial thickness of the magnetic conductive bridge 5 and the magnetic pole 6 can be calculated according to the required magnetic field strength and the structural magnetic circuit. The motor and the magnetic bearing rotor core 8 are both axially hollow structures, and the motor shaft can be inserted into the inner ring of the magnetic bearing rotor core 8. The magnetic bearing rotor core 8 and the shaft are fastened and reliably contacted by connection methods such as interference fit and keyway.

[0042] In a preferred embodiment of the present invention, the motor is a 6-slot 4-pole electric excitation flux switching structure, and the motor stator core is a six-tooth Figure 5 As shown, a slot is opened in the middle of each tooth, each armature winding coil 301-306 is wound on a stator tooth, and six armature winding coils form a three-phase winding. The excitation winding coils 401-403 are wound in the slots opened by two adjacent stator teeth. If a double-layer excitation winding is used, six excitation coils are wound in sequence. If a single-layer excitation winding is used, three excitation coils are distributed between phases. Figure 5 In this embodiment, the stator and rotor cores of the motor are formed by laminating multiple layers of non-oriented silicon steel sheets, and the thickness of the silicon steel sheets can be 0.2 mm, 0.35 mm or 0.5 mm.

[0043] Figure 6 This is a schematic diagram of 1 / 3 magnetic circuit of the motor in this embodiment. Figure 7 for Figure 6 The radial view of the magnetic bearing of the present invention is as follows:

[0044] Since the excitation winding coil of the motor bypasses the radial magnetic conductive section of the magnetic bearing, a bias magnetic field is generated in it. Figure 6 The radial permanent magnetic bias magnetic circuit formed by the bias magnetic flux generated by the excitation winding coil is: the connecting section of the yoke of the magnetic bridge → the radial magnetic section of the magnetic bridge → the circumferential magnetic section of the magnetic bridge → the magnetic pole 602 → the air gap → the magnetic bearing rotor core → the air gap → the adjacent magnetic poles 601 and 603 → the circumferential magnetic sections of the adjacent magnetic bridges → the radial magnetic sections of the adjacent magnetic bridges. The control coil generates a radial control magnetic field to adjust the air gap synthetic magnetic field. Specifically, the power amplifier drives the current of equal magnitude to pass through the two control coils opposite to each other in one direction, and the magnetic field is enhanced in the air gap on one side and weakened in the air gap on the other side, thereby adjusting the magnetic force of the magnetic bearing acting on the magnetic bearing rotor core.

[0045] Figure 8It is a half cross-sectional view of the electromagnetic flux switching motor and the bearing after being assembled in this embodiment.

[0046] The outer diameter of the magnetic bridge is equal to the outer diameter of the motor stator, the width of the radial magnetic section is not greater than the width of a single arm of the stator tooth, and the number of magnetic poles is equal to the number of stator teeth, which is 6. The magnetic bridge and the magnetic poles can be made of multi-layer non-oriented silicon steel sheets of different shapes, or can be made of electrical pure iron through integral precision machining.

[0047] The electrically excited flux switching motor described in the present invention is integrated with an active magnetic bearing. By adjusting the bias force generated on different magnetic poles of the magnetic bearing, a magnetic pull with adjustable size and direction can be combined. Based on the designed bias magnetic circuit lead-out structure and the operating principle in the embodiment, active magnetic bearings with different numbers of magnetic poles, magnetic field strengths and magnetic pulls can be designed. The thickness of the magnetic bridge and magnetic pole of the magnetic bearing is calculated based on the target magnetic field strength and the structural magnetic circuit. The size of the bias magnetic field can be adjusted by the current in the excitation winding, and the suspension force control of the magnetic bearing rotor can be achieved by adjusting the current in the control coil.

[0048] The integrated active magnetic bearing in the present invention has the characteristics of intuitive principle and compact structure, and effectively utilizes the space at the end of the motor stator. The main difference from the existing magnetic levitation motor system is that the excitation winding of the motor is used to provide a bias magnetic field for the active magnetic bearing, which shortens the axial length of the system and makes the bias magnetic field adjustable. The magnetic bearing stator draws out the excitation magnetic field through a magnetic bridge structure to form a bias magnetic field closed main loop.

Claims

1. An active magnetic bearing, characterized in that: It includes a magnetic bearing rotor core, a control coil, a magnetic bridge and multiple magnetic poles. The magnetic pole is installed on one side of the magnetic bridge. The control coil is wound around the magnetic pole. The magnetic bearing rotor core is embedded in the annular space formed by the circumferential arrangement of the magnetic poles. The magnetic poles and the magnetic bridge constitute the magnetic bearing stator core. The magnetic bearing rotor core rotates relative to the magnetic bearing stator core.

2. An active magnetic bearing according to claim 1, characterized in that: The magnetic bridge is composed of multiple magnetic units, each magnetic unit includes a circumferential magnetic section, a yoke connecting section and two radial magnetic sections, one end of the circumferential magnetic section is connected to one end of the first radial magnetic section, the other end of the first radial magnetic section is connected to one end of the yoke connecting section, the other end of the yoke connecting section is connected to one end of the second radial magnetic section, and the other end of the second radial magnetic section is connected to the other end of the circumferential magnetic section in the adjacent magnetic unit, so that the magnetic bridge forms a closed loop.

3. An active magnetic bearing according to claim 2, characterized in that: The number of magnetic poles is the same as the number of magnetic conductive units, which is 6N, where N is a positive integer.

4. The active magnetic bearing according to claim 3, characterized in that: The magnetic pole is of T-shaped structure, and the radial outer end of the magnetic pole of the T-shaped structure is in contact with the circumferential magnetic conductive section of the magnetic conductive bridge.

5. An electrically excited flux switching motor, characterized in that: An active magnetic bearing comprising any one of claims 2-4, further comprising a motor stator core, a motor rotor core, an excitation winding coil and an armature winding coil, wherein the motor rotor core is arranged inside the motor stator core, and the motor rotor core rotates relative to the motor stator core, the active magnetic bearing is arranged at the ends of the motor stator core and the motor rotor core, and the magnetic bridge is arranged between the magnetic pole and the motor stator core, and the teeth of each motor stator core are wound with the excitation winding coil and the armature winding coil.

6. The electrically excited flux switching motor according to claim 5, characterized in that: The motor stator core is a multi-tooth salient pole structure, with a slot in the center of each tooth. The armature winding coil is wound on each tooth of the motor stator core, and the excitation winding coil is wound in the slots between two adjacent motor stator core teeth.

7. The electrically excited flux switching motor according to claim 6, characterized in that: All radial magnetic conductive sections and yoke connecting sections are attached to the stator core of the motor, and each armature winding coil and excitation winding coil bypasses the radial magnetic conductive section and maintains an electrical insulation distance from the magnetic conductive bridge.

8. The electrically excited flux switching motor according to claim 5, characterized in that: The width of the radial magnetic conductive section is less than or equal to the width of the teeth of the motor stator core, the outer diameter of the circumferential magnetic conductive section is not greater than the inner diameter of the motor stator core, and the inner and outer diameters of the yoke connecting section are respectively equal to the inner and outer diameters of the motor yoke.

9. The electrically excited flux switching motor according to claim 5, characterized in that: The number of magnetic conductive units is not greater than the number of teeth of the motor stator core.

10. The electrically excited flux switching motor according to claim 5, characterized in that: The interior of the magnetic bearing rotor core and the motor rotor core are both hollow structures for mounting the rotating shaft.

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