A five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor

Abstract

The present invention relates to a five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor. Both ends of a cylindrical solid permanent magnet are respectively connected to a rotating shaft. A casing is installed outside the cylindrical solid permanent magnet. A stator core is fixedly installed on the casing. A set of torque windings is embedded in the bottom layer of the stator core, and two sets of suspension windings are embedded in the upper layer of the stator core. End covers are fixedly installed on both sides of the casing. Auxiliary bearings are installed between the end covers and the rotating shaft. Passive permanent magnet bearings are nested on both the end covers and the rotating shaft. The present invention is reasonably designed, integrating a magnetic suspension bearing and a permanent magnet motor into one. While the motor generates an electromagnetic torque capable of driving the rotor to rotate, it can also generate a radial suspension force to overcome the rotor gravity and unilateral magnetic pull force, simplifying the motor structure and shortening the axial length of the motor. The double suspension windings and the axial passive permanent magnet magnetic bearing achieve five-degree-of-freedom control, increasing the rotor stiffness and critical speed of the ultra-high-speed motor, and improving the operation stability and anti-disturbance ability.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor equipment, relates to permanent magnet motors, and particularly relates to a five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor. Background Art

[0002] Due to high efficiency, high power density, and small volume, ultra-high-speed motors are directly connected to loads, eliminating mechanical speed-changing devices, thus reducing noise and improving the efficiency of the transmission system. Ultra-high-speed motors are widely used in fields such as hydrogen fuel cell air compressors, flywheel energy storage, and aerospace. The research on ultra-high-speed motors has become a research hotspot in the field of motors. Permanent magnet motors, due to their large power density and high efficiency, have become the preferred structure for ultra-high-speed motors.

[0003] However, the rotational speed of ultra-high-speed motors can reach tens of thousands or even more than one hundred thousand revolutions per minute, and the circumferential speed can reach more than 200 m / s. Traditional mechanical bearings used in ultra-high-speed motors will be quickly worn out and it is difficult to achieve ultra-high-speed operation. Non-mechanical contact bearings need to be used. Non-mechanical contact bearings include air bearings and magnetic levitation bearings, among which:

[0004] Air bearings can achieve ultra-high-speed stable operation, with the advantages of low friction loss and long service life, but they have poor anti-interference ability and it is difficult to operate in a vacuum environment;

[0005] Magnetic levitation bearings have good stability, strong load-bearing capacity, and are easy to achieve ultra-high speed. However, their axial length is relatively long, which limits the development of motors in terms of volume and critical speed, and also increases the complexity and cost of the system. Summary of the Invention

[0006] The object of the present invention is to overcome the deficiencies of the prior art and provide a five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor. This motor combines a magnetic levitation bearing and an ultra-high-speed motor, and can achieve ultra-high-speed stable operation of the motor without the need for bearings.

[0007] The present invention solves its technical problems through the following technical solutions:

[0008] A five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor, characterized in that: it includes a housing, a left rotating shaft, a right rotating shaft and a cylindrical solid permanent magnet. The two ends of the cylindrical solid permanent magnet are respectively connected to the left rotating shaft and the right rotating shaft. The housing is installed outside the cylindrical solid permanent magnet. A stator core is fixedly installed on the housing. The stator core is divided into two sections. A set of torque windings are embedded in the bottom layer of the two sections of the stator core, and two sets of suspension windings are embedded in the upper layer of the two sections of the stator core. Left end covers and right end covers are respectively fixedly installed on both sides of the housing. A left auxiliary bearing is installed between the left end cover and the left rotating shaft, and a right auxiliary bearing is installed between the right end cover and the right rotating shaft. Left passive permanent magnet bearings are nested on both the left end cover and the left rotating shaft, and right passive permanent magnet bearings are nested on both the right end cover and the right rotating shaft. The left passive permanent magnet bearings and right passive permanent magnet bearings nested on the left end cover, right end cover, left rotating shaft and right rotating shaft are used to control the axial degree of freedom when the rotor is subjected to axial force or axial impact, and jointly with the two sets of suspension windings to achieve the control of five degrees of freedom.

[0009] Moreover, the left passive permanent magnet bearing and the right passive permanent magnet bearing are two permanent magnet rings with mutually repulsive magnetic properties. An annular protective sleeve is arranged outside the left passive permanent magnet bearing on the left rotating shaft, the right passive permanent magnet bearing on the right rotating shaft and the cylindrical solid permanent magnet. The cylindrical solid permanent magnet and the annular protective sleeve are in interference fit and combined to form a permanent magnet rotor.

[0010] Moreover, the torque winding is a two-stage torque winding and is used to generate electromagnetic torque. The suspension winding is a four-stage suspension winding and is used to generate radial suspension force. Both the torque winding and the suspension winding adopt a single-layer full-pitch winding method.

[0011] Moreover, the stator core is laminated by electrical steel sheets.

[0012] Moreover, there is a clearance fit between the left auxiliary bearing and the left rotating shaft, and between the right auxiliary bearing and the right rotating shaft. When the permanent magnet motor is not powered on, the left and right auxiliary bearings are in contact with the left and right rotating shafts to support the permanent magnet rotor and prevent the permanent magnet rotor from directly contacting the stator. When the permanent magnet motor is powered on, the left and right auxiliary bearings do not rotate with the permanent magnet rotor. The suspension windings replace the left and right auxiliary bearings to support the permanent magnet rotor, and at the same time overcome the gravity and unilateral magnetic pull of the permanent magnet rotor.

[0013] The advantages and beneficial effects of the present invention are:

[0014] 1. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor of the present invention integrates a magnetic levitation bearing and a permanent magnet motor into one body, enabling the stator and rotor of the motor to generate both the electromagnetic torque for driving the motor to rotate and the radial levitation force for supporting the weight of the rotor and overcoming the unilateral magnetic pull force. This not only simplifies the structure of the high-speed motor but also greatly shortens the axial dimension of the motor, thereby increasing the stiffness and critical speed of the ultra-high-speed motor rotor system and improving its operating stability.

[0015] 2. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor of the present invention has a stator core divided into two sections. Two levitation force windings are used to control the levitation force at the left and right ends of the motor rotor respectively, while a set of torque windings is used for unified control of the motor torque, and two passive permanent magnet magnetic bearings are used to control the axial degree of freedom.

[0016] 3. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor of the present invention uses a 2p-pole torque winding and a (2p + 2)-pole levitation force winding. On the one hand, it reduces the motor loss and increases the inductance of the torque winding. On the other hand, the permanent magnet rotor can adopt a cylindrical solid permanent magnet structure, simplifying the manufacturing process of the permanent magnet rotor and improving the operating reliability of the motor.

[0017] 4. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor of the present invention uses a single-layer full-pitch winding method for both the torque winding and the levitation winding, which can obtain a larger torque and levitation force with less ripple. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic axial sectional view of the present invention;

[0019] Figure 2 It is a schematic connection diagram of the torque winding and the levitation winding of the present invention;

[0020] Figure 3 It is a schematic principle diagram of generating the levitation force in the y direction through the levitation winding current of the present invention.

[0021] DESCRIPTION OF THE REFERENCE NUMERALS

[0022] 1 - housing; 2 - stator core; 3 - left end cover; 4 - right end cover; 5 - torque winding; 6 - levitation winding; 7 - cylindrical solid permanent magnet; 8 - annular protective sleeve; 9 - left shaft; 10 - right shaft; 11 - left auxiliary bearing; 12 - right auxiliary bearing; 13 - left passive permanent magnet magnetic bearing; 14 - right passive permanent magnet magnetic bearing. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be further described in detail below through specific embodiments. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0024] As Figure 1As shown in the figure, a five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor is innovative in that it includes a housing 1, a left rotating shaft 9, a right rotating shaft 10, and a cylindrical solid permanent magnet 7. Both ends of the cylindrical solid permanent magnet 7 are connected to the left rotating shaft 9 and the right rotating shaft 10 respectively. The housing 1 is installed outside the cylindrical solid permanent magnet 7. A stator core 2 is fixedly installed on the housing 1. The stator core 2 is laminated by electrical steel sheets. The stator core 2 is divided into two sections. A set of torque windings 5 are embedded in the bottom layer of the two sections of the stator core 2, and two sets of suspension windings 6 are embedded in the upper layer of the two sections of the stator core 2. Left end covers 3 and right end covers 4 are fixedly installed on both sides of the housing 1 respectively. A left auxiliary bearing 11 is installed between the left end cover 3 and the left rotating shaft 9, and a right auxiliary bearing 12 is installed between the right end cover 4 and the right rotating shaft 10. Left passive permanent magnet bearings 13 are nested on both the left end cover 3 and the left rotating shaft 9, and right passive permanent magnet bearings 14 are nested on both the right end cover 4 and the right rotating shaft 10. The left passive permanent magnet bearings 13 and the right passive permanent magnet bearings 14 nested on the left end cover 3, the right end cover 4, the left rotating shaft 9, and the right rotating shaft 10 are used to control the axial degree of freedom when the rotor is subjected to axial force or axial impact, and jointly with the two sets of suspension windings 6 to achieve the control of five degrees of freedom.

[0025] The left passive permanent magnet bearing 13 and the right passive permanent magnet bearing 14 are two permanent magnet rings with magnetic repulsion. And an annular protective sleeve 8 is arranged outside the left passive permanent magnet bearing 13 on the left rotating shaft 9, the right passive permanent magnet bearing 14 on the right rotating shaft 10, and the cylindrical solid permanent magnet 7. The cylindrical solid permanent magnet 7 and the annular protective sleeve 8 are in interference fit and combined to form a permanent magnet rotor.

[0026] The torque winding 5 is a two-stage torque winding and is used to generate electromagnetic torque. The suspension winding 6 is a four-stage suspension winding and is used to generate radial suspension force. Both the torque winding 5 and the suspension winding 6 adopt a single-layer full-pitch winding method.

[0027] P B =P M ±1 The number of pole pairs P of the suspension winding 6 B And the number of pole pairs P of the torque winding M Always satisfy the relationship between them. The schematic diagram of their spatial distribution structure in the stator core is as Figure 2 Shown. (a) is the suspension winding, and (b) is the torque winding. Considering the ultra-high-speed characteristics and torque requirements of the motor, the torque winding is 2 poles and the suspension winding is 4 poles. In order to obtain larger torque and suspension force, both windings adopt a single-layer full-pitch distribution. Since the air gap of the ultra-high-speed motor is large, this winding structure will not increase the torque ripple and suspension force ripple.

[0028] The suspension force winding is used to generate the radial suspension force to support the motor rotor. As Figure 3As shown, when a current is applied to the suspension winding as shown in the figure, the magnetic field generated by the suspension winding current is superimposed on the magnetic field generated by the rotor permanent magnet. The magnetic field on the upper side of the motor weakens while the magnetic field on the lower side strengthens. 15 represents the strengthening of the magnetic field, and 16 represents the weakening of the magnetic field. The electromagnetic suction force between the stator and the rotor is proportional to the square of the air-gap magnetic flux density. Therefore, the motor rotor will receive a suspension force in the vertical direction from bottom to top in the figure. Similarly, a suspension force in the horizontal direction can be generated. By detecting the radial position of the motor rotor in real time, the magnitude and direction of the suspension winding current can be controlled, so that the rotor can always be in a stable central suspension state.

[0029] There is a clearance fit between the left auxiliary bearing 11 and the left rotating shaft 9, and between the right auxiliary bearing 12 and the right rotating shaft 10. When the permanent magnet motor is not powered on, the left and right auxiliary bearings are in contact with the left and right rotating shafts to support the permanent magnet rotor and prevent the permanent magnet rotor from directly contacting the stator. When the permanent magnet motor is powered on, the left and right auxiliary bearings do not rotate with the permanent magnet rotor. The suspension winding 6 replaces the left and right auxiliary bearings to support the permanent magnet rotor, and at the same time overcomes the gravity of the permanent magnet rotor and the unilateral magnetic pull force.

[0030] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that various substitutions, changes, and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments and drawings.

Claims

1. A five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor, characterized in that: It includes a housing (1), a left rotating shaft (9), a right rotating shaft (10) and a cylindrical solid permanent magnet (7). Both ends of the cylindrical solid permanent magnet (7) are respectively connected to the left rotating shaft (9) and the right rotating shaft (10). The housing (1) is installed outside the cylindrical solid permanent magnet (7). A stator core (2) is fixedly installed on the housing (1). The stator core (2) is divided into two sections. A set of torque windings (5) is embedded in the bottom layer of the two sections of the stator core (2), and two sets of suspension windings (6) are embedded in the upper layer of the two sections of the stator core (2). Left end covers (3) and right end covers (4) are respectively and fixedly installed on both sides of the housing (1). A left auxiliary bearing (11) is installed between the left end cover (3) and the left rotating shaft (9), and a right auxiliary bearing (12) is installed between the right end cover (4) and the right rotating shaft (10). Left passive permanent magnet bearings (13) are nested on both the left end cover (3) and the left rotating shaft (9), and right passive permanent magnet bearings (14) are nested on both the right end cover (4) and the right rotating shaft (10). The left passive permanent magnet bearings (13) and the right passive permanent magnet bearings (14) nested on the left end cover (3), the right end cover (4), the left rotating shaft (9) and the right rotating shaft (10) are used to control the axial degree of freedom when the rotor is subjected to axial force or axial impact, and jointly with the two sets of suspension windings (6) to achieve the control of five degrees of freedom.

2. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor according to claim 1, wherein: The left passive permanent magnet bearing (13) and the right passive permanent magnet bearing (14) are two permanent magnet rings with magnetic repulsion. And an annular protective sleeve (8) is arranged outside the left passive permanent magnet bearing (13) on the left rotating shaft (9), the right passive permanent magnet bearing (14) on the right rotating shaft (10) and the cylindrical solid permanent magnet (7). The cylindrical solid permanent magnet (7) and the annular protective sleeve (8) are in interference fit and combined to form a permanent magnet rotor.

3. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor according to claim 1, characterized in that: The torque winding (5) is a two-stage torque winding and is used to generate electromagnetic torque. The suspension winding (6) is a four-stage suspension winding and is used to generate radial suspension force. Both the torque winding (5) and the suspension winding (6) adopt a single-layer full-pitch winding method.

4. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor according to claim 1, characterized in that: The stator core (2) is laminated by electrical steel sheets.

5. The five-degree-of-freedom ultra-high-speed bearingless permanent magnet motor according to claim 2, wherein: There is a clearance fit between the left auxiliary bearing (11) and the left rotating shaft (9), and between the right auxiliary bearing (12) and the right rotating shaft (10). When the permanent magnet motor is not powered on, the left and right auxiliary bearings are in contact with the left and right rotating shafts to support the permanent magnet rotor and prevent the permanent magnet rotor from directly contacting the stator. When the permanent magnet motor is powered on, the left and right auxiliary bearings do not rotate with the permanent magnet rotor. The suspension windings (6) replace the left and right auxiliary bearings to support the permanent magnet rotor, and at the same time overcome the gravity of the permanent magnet rotor and the unilateral magnetic pull force.

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