Permanent magnet biased magnetic suspension bearing and magnetic flux reverse motor

Abstract

The permanent magnet biased magnetic suspension bearing comprises a magnetic bearing rotor iron core, a magnetic bearing stator iron core assembly and an iron core coil, the magnetic bearing stator iron core assembly is arranged on the periphery of the magnetic bearing rotor iron core, and the magnetic bearing rotor iron core rotates relative to the magnetic bearing stator iron core assembly; the magnetic bearing stator iron core assembly comprises magnetic bearing magnetic poles and a circular ring connecting fastener, the magnetic bearing magnetic poles are arranged along the circumferential direction of the circular ring connecting fastener, and the iron core coil is wound on the magnetic bearing magnetic poles; the invention further discloses a magnetic flux reversing motor. The advantages of compactness and simplicity of a permanent magnet type magnetic flux reverse motor are reserved structurally, the space on the inner side of the end of the motor winding is fully utilized, the axial length of a permanent magnet high-speed motor system combined with the magnetic suspension bearing can be reduced without additionally increasing the size of the motor, the dynamic performance of a motor shaft system is improved, and the service life of the motor is prolonged. The purposes of simple structure, high compactness and high integration degree are achieved.

Description

Technical Field

[0001] The present invention relates to the field of motors, and in particular to a permanent magnet biased magnetic suspension bearing and a flux reversal motor. Background Art

[0002] With the rapid development of modern industry, high-speed rotating machinery such as high-speed motors / generators, compressors, and gas turbines with permanent magnet synchronous motors as the core power are key equipment to ensure the operation of the system. The motor structures used in different application fields and operating conditions are also very rich. Compared with the commonly used rotor permanent magnet brushless motor, the permanent magnet of the stator permanent magnet brushless motor is located on one side of the motor stator. 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. It overcomes the shortcomings of traditional rotor permanent magnet brushless motors, such as complex structure, high manufacturing cost, complex processing technology, large equivalent air gap, difficult rotor cooling, and irreversible demagnetization risk.

[0003] Stator permanent magnet brushless motors can usually be divided into four categories: double salient pole type, flux switching type, stator slot permanent magnet type and flux reversal type. They each have their own characteristics: the permanent magnets of the double salient pole permanent magnet motor are usually located in the stator yoke, the space for placing permanent magnets is small, and the armature winding is often unipolar flux, resulting in low torque density; the permanent magnets of the flux switching permanent magnet motor are embedded in the middle of the stator teeth, and the permanent magnets and the stator core teeth on both sides present a "sandwich" structure. The back electromotive force waveform of this structure is very sinusoidal and the torque capacity is outstanding, but the amount of permanent magnets is relatively large and the structure is relatively complex; the permanent magnets of the stator slot permanent magnet motor are usually installed in the stator slot. Although this structure can adjust the main magnetic field through the electric excitation current, the overall torque capacity is general, and the structure and installation are relatively complex; the flux reversal permanent magnet motor usually attaches the permanent magnets to the stator teeth. Its structure is the simplest, robust, the amount of permanent magnets is moderate, and it has a large torque output capacity.

[0004] However, as a key component of high-speed motors, the performance of bearings is closely related to the safe and reliable operation of motors. Traditional mechanical bearings will produce serious problems such as heating, electrical corrosion, vibration, noise, etc. due to friction and shaft current at high speeds, reducing the efficiency of the system and the life of the bearings themselves, resulting in a decrease in system reliability. This has become one of the technical bottlenecks restricting the development of the system towards high speed, high efficiency and long life. Therefore, a high-speed bearing system must be adopted. In response to the problems caused by traditional mechanical bearings, the industry has proposed the idea of ​​using magnetic 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 mainstream high-speed magnetic bearing motor system generally consists of a pair of two radial magnetic bearings and an axial thrust magnetic bearing installed at both ends of the high-speed motor, and then the impeller, fan, pump and other structures are installed on the outside of the magnetic bearing. In addition, the existing systems all regard the three magnetic bearings and the motor as independent components, which need to be designed separately and then assembled. The compactness between the components is not high, and the space at the end of the permanent magnet motor winding is not fully utilized, resulting in low axial space utilization of the shaft system. Compared with the permanent magnet motor system using mechanical bearings, the proportion of the axial effective length of the assembled high-speed magnetic bearing motor system to the total axial length of the entire system is relatively low, resulting in low power density of the motor system and magnetic bearing suspension force density. Compared with the motor system supported by conventional mechanical shaft systems, there is no obvious advantage, which has become one of the bottleneck problems of the current magnetic bearing motor system. Summary of the invention

[0006] Purpose of the invention: In view of the above problems, the purpose of the present invention is to provide a permanent magnet biased magnetic levitation bearing and a flux reversal motor. By designing the key components of the magnetic levitation bearing stator, the permanent magnets of the permanent magnet flux reversal motor can realize other uses of the magnetic field energy through the magnetic bearing pole structure, thereby improving the integration of the magnetic levitation motor system. At the same time, since the integrated magnetic bearing is located on the inner side of the motor winding end, the power density of the magnetic levitation motor system can be further improved without increasing the volume, thereby shortening its overall axial length.

[0007] Technical solution: On the one hand, the present invention provides a permanent magnet biased magnetic suspension bearing, comprising a magnetic bearing rotor core, a magnetic bearing stator core assembly and a core coil, wherein the magnetic bearing rotor core is an axial ring structure, the magnetic bearing stator core assembly is arranged on the periphery of the magnetic bearing rotor core, and the magnetic bearing rotor core rotates relative to the magnetic bearing stator core assembly;

[0008] The magnetic bearing stator core assembly comprises a magnetic bearing pole and an annular connecting fastener. The magnetic bearing pole is arranged along the circumferential direction of the annular connecting fastener, and the core coil is wound around the magnetic bearing pole.

[0009] Furthermore, the annular connecting fastener has protrusions along the axial direction, and the protrusions are evenly arranged along the circumferential direction. The outer end surface of the magnetic bearing pole yoke is embedded between two adjacent protrusions, and the axial thickness of the protrusion is the same as the axial thickness of the magnetic bearing pole.

[0010] Furthermore, the number of magnetic poles of the magnetic bearing is 6N, where N is a positive integer.

[0011] Furthermore, the magnetic pole of the magnetic bearing is a T-shaped structure.

[0012] Another aspect of the present invention provides a flux reversal motor, comprising a permanent magnet biased magnetic suspension bearing, a motor stator core, a motor rotor core, a permanent magnet, a three-phase armature winding and a rotating shaft;

[0013] The magnetic bearing rotor core is arranged on the rotating shaft;

[0014] The stator core of the motor includes a plurality of stator teeth evenly arranged in the circumferential direction, each stator tooth is mounted with two permanent magnets with opposite magnetization directions facing the air gap surface, the axial thickness of the permanent magnet is greater than the thickness of the stator tooth, and the outer end surface of the magnetic pole yoke of the magnetic bearing is tightly fitted with the permanent magnet beyond the stator tooth;

[0015] Each coil of the three-phase armature winding is wound on the stator teeth in sequence;

[0016] The motor rotor core rotates relative to the motor stator core.

[0017] Furthermore, the polarities of the four permanent magnets under two adjacent stator teeth are alternately distributed.

[0018] Furthermore, the three-phase armature winding is a concentrated winding or a distributed winding.

[0019] Furthermore, the three-phase armature winding is a single-layer winding or a multi-layer winding.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0021] 1. The present invention makes full use of the inner space of the motor winding end, and introduces the energy of the motor permanent magnet into the integrated magnetic suspension bearing by reasonably designing the shape and size of the magnetic bearing pole without increasing the motor volume or reducing the motor performance, thereby providing a bias magnetic field for the magnetic suspension bearing, realizing the component reuse of the permanent magnet in the permanent magnet flux reversal motor, and further realizing the multi-purpose reuse of the magnetic field energy, shortening 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 high-speed motor and magnetic suspension bearing.

[0022] 2. The present invention can obtain bias magnetic fields of different sizes by extending the permanent magnets in contact with different poles to different lengths, and then can combine constant magnetic pulling forces of different sizes and directions to bear constant loads such as the gravity of the rotating shaft itself when installed horizontally, thereby reducing the control current and driver capacity to a certain extent to reduce losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a permanent magnet biased magnetic bearing;

[0024] Figure 2 It is the assembly drawing of the permanent magnet biased magnetic bearing;

[0025] Figure 3 It is a structural schematic diagram of a flux reversal motor;

[0026] Figure 4 It is a structural schematic diagram of a 6-slot 4-pole flux reversal motor;

[0027] Figure 5 It is a 1 / 2 cross-sectional view of a 6-slot 4-pole flux reversal motor;

[0028] Figure 6 It is a three-dimensional schematic diagram of the 1 / 3 bias magnetic circuit of a 6-slot 4-pole flux reversal motor;

[0029] Figure 7 This is the front view of the 1 / 3 bias magnetic circuit of the 6-slot 4-pole flux reversal motor. DETAILED DESCRIPTION

[0030] 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.

[0031] Embodiment 1

[0032] The structure diagram of a permanent magnet biased magnetic suspension bearing described in this embodiment is as shown in FIG. Figure 1 to Figure 2 As shown, the bearing comprises a magnetic bearing rotor core 8, a magnetic bearing stator core assembly and a core coil 6, the magnetic bearing rotor core 8 is an axial ring structure, the magnetic bearing stator core assembly is arranged on the magnetic bearing rotor core 8, and the magnetic bearing rotor core 8 rotates relative to the magnetic bearing stator core assembly;

[0033] The magnetic bearing stator core assembly includes a magnetic bearing pole 5 and an annular connecting fastener 7. The magnetic bearing pole 5 is arranged along the circumferential direction of the annular connecting fastener 7. The core coil 6 is wound around the magnetic bearing pole 5, and the core coil 6 maintains an electrically insulating distance from the magnetic bearing pole 5.

[0034] To facilitate the detailed description of this embodiment, a spatial xyz reference coordinate system is established without loss of generality, such as Figure 2 As shown, the xy plane is parallel to the end face of the permanent magnet biased magnetic levitation bearing with a circular cross-section, r is the radial direction of each end face of the permanent magnet biased magnetic levitation bearing (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 permanent magnet biased magnetic levitation bearing (hereinafter referred to as axial).

[0035] The annular connecting fastener 7 has protrusions along the axial direction, and the protrusions are evenly arranged along the circumferential direction. The outer end surface of the yoke of the magnetic bearing pole 5 is embedded between two adjacent protrusions, and the thickness of the protrusion along the axial direction is the same as the thickness of the magnetic bearing pole 5 along the axial direction.

[0036] The annular connecting fastener 7 is annular as a whole and can be divided into a base section and an interpolar section. The interpolar section is a convex structure. The annular connecting fastener 7 can be made of non-magnetic, low-conductivity materials with certain mechanical strength and hardness, such as ceramics, stainless steel, and high-temperature resistant plastics. Several circumferential grooves are formed between the interpolar sections to embed each magnetic bearing pole 5 and closely contact it. The base section is in close contact with the outer surface of the end of all magnetic bearing poles to connect the components, fasten the components and make them a whole.

[0037] The number of magnetic bearing poles 5 is 6N, where N is a positive integer, and the number of magnetic bearing poles 5 is less than or equal to the number of motor stator teeth. The thickness and width are calculated by the magnetic circuit method based on the target magnetic field strength and the structural magnetic circuit.

[0038] In this example, the number of magnetic bearing poles 5 is 6 for illustration.

[0039] The magnetic bearing pole 5 is a T-shaped structure. The outer diameter of the annular fastener 7 is not larger than the outer diameter of the magnetic bearing pole 5, and the inner diameter is not smaller than the inner diameter of the contact section between the magnetic bearing pole 5 and the permanent magnet. The axial thickness of the interpolar section extending between the two magnetic bearing poles 5 is equal to the thickness of the magnetic bearing pole 5.

[0040] The permanent magnet biased magnetic bearing described in this embodiment makes full use of the space inside the motor winding end. By reasonably designing the shape and size of the magnetic bearing poles without increasing the motor volume or reducing the motor performance, the energy of the motor permanent magnet can be introduced into the integrated magnetic bearing, providing a bias magnetic field for the magnetic bearing, realizing the component reuse of the permanent magnet in the permanent magnet flux reversal motor, and further realizing the multi-purpose reuse of the magnetic field energy, shortening the axial length of the magnetic bearing 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 bearing.

[0041] Embodiment 2

[0042] like Figure 3 As shown, a flux reversal motor described in this embodiment includes the permanent magnet biased magnetic suspension bearing described in the above embodiment 1, and also includes a motor stator core 1, a motor rotor core, a permanent magnet 4, a three-phase armature winding 3 and a rotating shaft;

[0043] The magnetic bearing rotor core is arranged on the rotating shaft;

[0044] The motor stator core 1 includes a plurality of stator teeth uniformly arranged along the circumferential direction, and each stator tooth is mounted with two permanent magnets 4 with opposite magnetization directions facing the air gap surface, and the axial thickness of the permanent magnet 4 is greater than the thickness of the stator tooth, and the outer end surface of the yoke of the magnetic bearing pole 5 is closely fitted with the permanent magnet 4 beyond the stator tooth;

[0045] The coils of the three-phase armature winding 3 are wound on the stator teeth in sequence;

[0046] The motor rotor core rotates relative to the motor stator core 1 .

[0047] In this example, the motor stator core 1 and the motor rotor core 2 are both formed by laminating non-oriented multi-layer silicon steel sheets. The motor rotor core 2 is located in the middle of the motor stator and has an air gap with the motor stator core 1. The motor rotor core 2 can rotate relative to the motor stator.

[0048] The four permanent magnets 4 under two adjacent stator teeth are distributed with alternating polarities, such as NSSN distribution or SNNS distribution.

[0049] The surface of the stator tooth facing the air gap is taken as its lower surface. Two permanent magnets 4 with opposite magnetization directions are mounted on the lower surface of each stator tooth. The magnetism of the permanent magnets 4 under adjacent stator teeth is alternating. That is, if the magnetism of the permanent magnet 4 under the first stator tooth is NS, the magnetism of the permanent magnets 4 under the two adjacent stator teeth is SN, and they are alternately distributed on the lower surface of the stator teeth. Therefore, if the number of stator teeth is Ps, there are 2Ps permanent magnets 4 mounted on the surface of the stator teeth.

[0050] The permanent magnet 4 is slightly longer in axial length than the motor stator core 1. Figure 6 The h1 shown in the figure indicates that the permanent magnet 4 is longer than the length of the motor stator core 1, and is used to cooperate with the magnetic bearing pole 5 to introduce the permanent 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. Figure 3 As shown, the yoke edge of the magnetic bearing pole 5 is tightly fitted with the inner side of the permanent magnet 4 extending out of the motor, and a core coil 6 is wound around each magnetic bearing pole 5 of the magnetic suspension bearing. The magnetic bearing rotor core 8 is located in the annular space formed by the magnetic bearing poles 5 evenly distributed along the circumference and can rotate relative to the magnetic bearing stator core. The yoke edges of all magnetic bearing poles 5 are embedded in the circumferential grooves of the annular connection fasteners 7 to form a solid whole. Figure 6 As shown, the required permanent magnet length h1 extending out of the motor stator teeth and the axial thickness h2 of the magnetic bearing pole 5 can be determined by the magnetic circuit method according to the required magnetic field strength and the structural magnetic circuit. The bias magnetic field size under each magnetic bearing pole 5 can be changed by the length h1 and the magnetic bearing pole thickness h2, and bias forces of different sizes and directions can be combined by changing the bias magnetic field size under different poles. Based on the designed bias magnetic circuit lead-out structure and the operating principle in the embodiment, active magnetic suspension bearings with different numbers of poles, magnetic field strengths and magnetic pulls can be designed.

[0051] The magnetic bearing rotor core 8 is an axially hollow structure, 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 in reliable contact with each other through interference fit, keyway and other connection methods.

[0052] The three-phase armature winding 3 is wound on each stator tooth, and the three-phase armature winding 3 can be a concentrated winding or a distributed winding. The three-phase armature winding is a single-layer winding or a multi-layer winding.

[0053] In a preferred embodiment of the present invention, the motor is a 6-slot 4-pole concentrated winding flux reversal structure, and the motor stator core has six teeth, such as Figure 4 As shown. Each coil of the three-phase concentrated armature winding is wound on a stator tooth and is alternately distributed in the order of ABC three phases. The two armature coils of each phase are 180° apart in space and radially opposite to each other. As shown in the figure, 301 and 304 are sequentially connected in series or in parallel to form the A-phase armature winding, 302 and 305 are sequentially connected in series or in parallel to form the B-phase armature winding, and 303 and 306 are sequentially connected in series or in parallel to form the C-phase armature winding. The magnetization direction of the permanent magnet is as described above, 402 and 403 are radially outward, and 401 and 404 are radially inward. In this embodiment, the stator and rotor cores of the motor are formed by stacking multiple layers of non-oriented silicon steel sheets, and the thickness of the silicon steel sheets can be 0.2mm, 0.35mm or 0.5mm.

[0054] like Figure 5 As shown, the outer diameter of the magnetic bearing pole 5 is equal to the inner diameter of the tile-shaped permanent magnet 4 mounted on the surface of the motor stator tooth to ensure good contact between the magnetic bearing pole 5 and the permanent magnet 4. The outer diameter of the circular connecting fastener 7 is not greater than the outer diameter of the magnetic bearing pole 5, and the inner diameter is not less than the inner diameter of the yoke of the magnetic bearing pole 5. The length of the interpolar section extending between the two magnetic bearing poles 5 can be equal to the thickness of the magnetic bearing pole 5. Each magnetic bearing pole 5 is embedded in the groove of the circular connecting fastener 7 to ensure that it is fixed as a whole. The number of magnetic bearing poles 5 is equal to the number of stator teeth, which is 6 in this example. The magnetic bearing pole 5 and the magnetic bearing rotor core 8 can be formed by stacking multiple layers of non-oriented rolled silicon steel sheets of corresponding shapes, or by integral fine processing of electrical pure iron. The circular connecting fastener 7 is a non-magnetic, low-conductivity material with a certain mechanical strength and hardness, which can be ceramic, stainless steel, high-temperature resistant plastic, etc.

[0055] Figure 6 to Figure 7 FIG. 1 is a schematic diagram of the magnetic circuit of the magnetic bearing part of this embodiment, wherein: Figure 6 This is a schematic diagram of 1 / 3 magnetic circuit. Figure 7 for Figure 6 The operating principle of the permanent magnet biased magnetic bearing of the present invention is as follows:

[0056] Since the permanent magnets extending out of the motor are in close contact with the magnetic pole yoke of the magnetic bearing, and two permanent magnets of the same polarity are attached to the same magnetic pole of the magnetic bearing, a radially inward or outward bias magnetic field will be generated therein. Figure 6As shown, the bias flux generated by this part of permanent magnets 401-404 flows through the magnetic poles 501-503 and the radial permanent magnetic bias magnetic circuit formed by the magnetic bearing rotor 8 as follows: permanent magnet N pole → magnetic bearing pole 502 → air gap → magnetic bearing rotor core → air gap → adjacent magnetic bearing pole 501 or 503 → permanent magnet S pole. The iron core coil wound on the magnetic bearing pole teeth 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 two control coils radially opposite 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.

[0057] The permanent magnet biased magnetic bearing of the present invention is based on the flux reversal motor. By extending the permanent magnets mounted on the surface of the stator teeth axially, a typical magnetic bearing closed magnetic circuit is formed by using T-type magnetic poles, working air gaps and magnetic bearing rotors, so as to achieve the goal of multi-purpose reuse of permanent magnets in the flux reversal motor. At the same time, when the extension lengths of the permanent magnets mounted on different stator teeth are different, different strengths of air gap magnetic density can be generated in the magnetic bearing, and then different bias forces are generated to bear constant loads, so as to achieve the goal of reducing load current and drive capacity. In terms of structure, the advantages of the compactness and simplicity of the permanent magnet flux reversal motor are retained, and the space inside the motor winding end is fully utilized. The axial length of the "permanent magnet high-speed motor system + magnetic bearing" can be reduced without increasing the motor volume, and the dynamic performance of the motor shaft system is improved, so as to achieve the goal of simple structure and high integration.

Claims

1. A permanent magnet biased magnetic bearing, characterized in that: It includes a magnetic bearing rotor core, a magnetic bearing stator core assembly and a core coil, wherein the magnetic bearing rotor core is an axial ring structure, the magnetic bearing stator core assembly is arranged on the periphery of the magnetic bearing rotor core, and the magnetic bearing rotor core rotates relative to the magnetic bearing stator core assembly; The magnetic bearing stator core assembly comprises a magnetic bearing pole and an annular connecting fastener. The magnetic bearing pole is arranged along the circumferential direction of the annular connecting fastener, and the core coil is wound around the magnetic bearing pole.

2. The permanent magnet biased magnetic bearing according to claim 1, characterized in that: The annular connecting fastener has protrusions along the axial direction, and the protrusions are evenly arranged along the circumferential direction. The outer end surface of the magnetic bearing pole yoke is embedded between two adjacent protrusions, and the axial thickness of the protrusion is the same as the axial thickness of the magnetic bearing pole.

3. The permanent magnet biased magnetic bearing according to claim 2, characterized in that: The number of magnetic poles of the magnetic bearing is 6N, where N is a positive integer.

4. The permanent magnet biased magnetic bearing according to claim 1, characterized in that: The magnetic poles of the magnetic bearing are of T-shaped structure.

5. A flux reversal motor, characterized in that: The permanent magnet biased magnetic bearing according to any one of claims 1 to 4 further comprises a motor stator core, a motor rotor core, a permanent magnet, a three-phase armature winding and a rotating shaft; The magnetic bearing rotor core is arranged on the rotating shaft; The stator core of the motor includes a plurality of stator teeth evenly arranged in the circumferential direction, each stator tooth is mounted with two permanent magnets with opposite magnetization directions facing the air gap surface, the axial thickness of the permanent magnet is greater than the thickness of the stator tooth, and the outer end surface of the magnetic pole yoke of the magnetic bearing is tightly fitted with the permanent magnet beyond the stator tooth; Each coil of the three-phase armature winding is wound on the stator teeth in sequence; The motor rotor core rotates relative to the motor stator core.

6. The flux reversal motor according to claim 5, characterized in that The polarities of the four permanent magnets under two adjacent stator teeth are alternately distributed.

7. The flux reversal motor according to claim 5, characterized in that The three-phase armature winding is either a concentrated winding or a distributed winding.

8. The flux reversal motor according to claim 5, characterized in that The three-phase armature winding is a single-layer winding or a multi-layer winding.

Images