CN108282069A - The modular splicing disc type magnetic suspension force torque motor of Ultra-Low Speed - Google Patents

Abstract

The ultra-low-speed unit type splicing disc type magnetic levitation torque motor includes a base and a pair of unit type splicing disc type direct drive motors. It is characterized in that the device has a rotationally symmetrical central rotating body and constrains the rotating body axially, A pair of tapered active offset magnetic suspension bearings for radial movement realizes the magnetic suspension support of the rotating shaft. At the same time, it is equipped with a corresponding pair of radial protection bearings, a pair of axial protection bearings and a position feedback system. On this basis , the central rotating body is driven redundantly or synchronously by a pair of unitary spliced disc direct drive motors. The invention integrates a direct drive motor, a magnetic suspension bearing, an axial and radial protection bearing, a feedback and a braking system, has a simple and compact structure, has a high degree of integration, improves space utilization, and can effectively reduce machining costs and power Reduce the cost of electronic devices and improve the competitiveness of products.

Description

Ultra-low speed unit type splicing disc type magnetic levitation torque motor

technical field

The invention relates to a magnetic levitation rotating device driven by a unit type spliced disc torque motor, in particular to an ultra-low speed unit spliced disc type magnetic levitation torque motor, which integrates conical active bias magnetic levitation bearings and is designed for high precision magnetic levitation rotation axis. It can be used in the tracking spindle of astronomical instruments, and can also be used in radar tracking, aerospace measurement and control simulation platforms and other fields. The present invention is the research achievement of the following projects: National Natural Science Foundation General Project (Project No.: 11573046, 11273039), Chinese Academy of Sciences Astronomy Special Project (C-113).

Background technique

Large-scale astronomical instruments and spacecraft measurement and control simulation platforms are all high-precision equipment, requiring small frictional torque, high rigidity of the transmission mechanism, fast dynamic response, and high rotation accuracy. Traditional rotating shafts are generally supported by hydrostatic bearings and mechanical bearings. The structural design of hydrostatic bearings is very complicated, and the requirements for manufacturing precision are very high. The precision of mechanical bearings is difficult to meet the precision requirements of large astronomical instruments. The rotating shaft supported by mechanical bearings still has disadvantages such as large frictional torque, serious nonlinearity, high power consumption, and low-speed crawling. For large astronomical instruments, the problem is more obvious. The magnetic levitation support has the advantages of non-contact, no friction, high precision, low power consumption, and low mechanical assembly requirements, and can be integrated with the motor to simplify the structure and reduce the cost. The conventional magnetic suspension bearing system generally uses two radial electromagnetic bearings and one axial electromagnetic bearing to control the five degrees of freedom of the rotating shaft, which occupies a considerable space and has a complex structure. The invention proposes a unit type, spliced disc type direct drive motor, which integrates a conical active bias magnetic suspension bearing, and realizes the magnetic suspension support and direct drive of the rotating shaft at the same time. It meets the technical requirements of small friction torque, high transmission stiffness, fast dynamic response, low power consumption, and high rotation precision of the rotating device. The design is compact, high reliability, maintenance-free, excellent acceleration performance, and no vibration. It is suitable for large-scale astronomical instruments. , radar, and spacecraft measurement and control platforms have broad application prospects in applications that require extremely high reliability, precision, and load capacity.

Contents of the invention

The purpose of the present invention is to propose a unitary spliced disc motor with a wider range of applications than the prior art. At the same time, it integrates a conical active offset magnetic suspension bearing to realize a magnetic suspension that directly drives the rotating shaft. The device of the invention is mainly composed of an angular displacement feedback system, a tapered active offset magnetic suspension bearing, a unit spliced disc motor, an axial protection bearing, a radial protection bearing, a rotating shaft, a base and the like. And meet the following technical requirements: easy processing, assembly, transportation, low maintenance cost, strong bearing capacity, no friction, low power consumption, high transmission efficiency, high rotary positioning accuracy, and no crawling during ultra-low speed operation.

The technical solution for accomplishing the task of the above invention is: an ultra-low-speed unitary spliced disc magnetic suspension torque motor, which mainly includes a base, a pair of unitary spliced disc direct drive motors, a pair of conical active biased magnetic suspension bearings and a shaft To, radial protection bearing. It is characterized in that the device has a rotationally symmetrical central rotating body and a pair of conical active offset magnetic suspension bearings that constrain the axial and radial movement of the rotating body to realize the magnetic suspension support of the rotating shaft. At the same time, it is designed with corresponding Based on a pair of radial protection bearings, a pair of axial protection bearings and a position feedback system, the central rotating body is driven redundantly or synchronously by a pair of unitary spliced disc direct drive motors.

The pair of unit type spliced disk direct drive motors, the pair of conical active magnetic suspension bearings, the pair of radial protection bearings, and the pair of axial protection bearings are arranged symmetrically with respect to the axial center of the rotating shaft. Initialize the tapered active magnetic suspension bearing before work. According to the calibrated position of the axial and radial conical active magnetic suspension bearing sensors, initialize the control current or voltage to control the position of the rotating shaft. When working, the rotating shaft needs to rotate or rotate At a certain angle, the controller controls the unit type splicing disc type direct drive motor to execute the system command.

The unit spliced disc direct drive motor is a three-phase permanent magnet torque motor, which is designed as 2L (L=1, 2, 3, 4...) minimum unit motors, and the 2L minimum units can be flexibly and freely combined into P A unit motor, according to the size of the model, the optimal structure combination P=1, 2, 3, 4, .... In a specific implementation example, P=4, and each independent unit motor can operate as a single motor, or can cooperate and operate synchronously. According to a preferred design scheme, the left and right sets of unit spliced disc permanent magnet synchronous torque motors each have 4 stator units, each sharing a rotor, and can independently or cooperatively drive the rotating shaft 4 to rotate. Each of said direct drive (unit) motors consists of an appendage (rotor) and an energizable base (stator unit) which are rigidly connected to said central rotating cylinder (rotation shaft 5 ) in a torsionally fixed manner. Accessories (rotor) refer to 2-8, 2-9, 2-10, 2-11 in Figure 7; base parts (stator units) that can be powered refer to 2-1, 2-2, 2-3 in Figure 7 , 2-4, 2-5, 2-6, 2-7.

In the unit type spliced disc type direct drive motor, the rotor consists of p N poles and p S poles (p=1, 2, 3, ...) alternately and evenly distributed on the rotor shaft; the permanent The magnet adopts a unit structure; each magnetic pole is composed of m (m=1, 2, 3, ...) permanent magnets of equal length and same polarity, and adopts a design to reduce cogging effect; the m equal length and same polarity The permanent magnet is evenly assembled on the rotor shaft of the motor by the automatic glue-coating assembly mechanism in the way of alternating N and S poles; a protection device is designed outside the permanent magnet to protect the permanent magnet.

The unit type splicing disc type direct drive motor is implemented as an example, the motor rotor is distributed on the rotor shaft by 128 N poles and 128 S poles alternately and uniformly; the permanent magnet of each magnetic pole adopts a unit structure ; The whole rotor is made up of 16 rotor units, and each rotor unit is alternately distributed with 8 N poles and 8 S poles permanent magnets 2-10, and each magnetic pole is made up of 2 permanent magnets of equal length and same polarity, and The design of reducing the cogging effect is adopted; the two permanent magnets of the same length and the same polarity are uniformly bonded on the rotor magnetic conducting ring (plate) in the way of alternating N and S poles; the permanent magnets 2-10 are installed outside The stainless steel protective cover is fixed on the rotor magnetic conducting ring (plate) by screws.

The unit spliced disc direct drive motor has a stator with a unit spliced structure design, and each independent and complete stator unit is composed of several minimum stator winding units; there can be 2M (M=1, 2, 3, 4 ,…) independent stator units are evenly distributed on the same circle, and each independent stator unit can operate as a single motor, or can cooperate and operate synchronously. The unit splicing structure design means that each independent stator unit (motor) (refer to Figure 10-Figure 13, Figure 14) is passed through the positioning structure by the smallest stator winding unit, more specifically, a convex groove positioning structure , Assembled; the stator core 3-2 of each winding unit is made of silicon steel sheets through a progressive die stamping at one time, and the cogging of each internal unit adopts a structure for reducing the cogging effect; and each The outermost winding unit of the complete stator unit is designed to reduce the end effect. The stator core and the stator winding are insulated by an insulating isolation cover.

The present invention adopts the design of reducing the end face effect, specifically refers to the design of the closed loop structure of the magnetic force lines as shown in Figure 14-1 and Figure 14-2 on the silicon steel sheets of the two outermost stator windings of the stator unit.

The driving part of the central rotating part is realized by electric direct drive, especially by directly driving the permanent magnet synchronous torque motor, preferably the unitary disc spliced permanent magnet synchronous torque motor directly drives the central rotating part (rotary shaft). Wherein, the energizable base member (stator unit) of each disc-type direct drive device is rigidly connected to the base through a connecting member. The rotor part of the motor is constructed as an attachment containing permanent magnet excitation, rigidly connected to the central rotating part (rotary shaft) by means of joints, and the (sensing) device for detecting the angle and/or phase position is advantageously axially Set between attachments.

The motor rotor is composed of n N poles and n S poles (n=1, 2, 3,...) alternately and evenly distributed on the rotor shaft; the permanent magnet of each pole adopts a unit structure; each pole It is composed of m (m=1,2,3,...) permanent magnets of equal length and polarity, and adopts a design to reduce the cogging effect; the m permanent magnets of equal length and polarity are assembled by automatic glue coating The mechanism is evenly assembled on the rotor shaft of the motor in the way of alternating N and S poles; a stainless steel protection device is designed outside the permanent magnet.

In order to improve the reliability of the system. The spliced disc-type direct drive motor adopts a symmetrical double-redundant structure, which not only realizes the symmetry of the axial force, but also realizes that when one set of control systems fails, the other set of systems can still operate through the dual-redundant control system. normal work. During normal operation, the two redundancy systems work at the same time. When a failure occurs in a certain redundancy system, the system removes the faulty redundancy and activates the single redundancy mode.

To repeat: This motor adopts a dual redundancy system, and as an optimal method, it adopts a hot backup control method. That is to say, under normal circumstances, the two redundancy levels work at the same time. When a certain redundancy level fails, the system removes the faulty level and activates the single redundancy mode.

In order to realize the rotation of the central rotating part (rotating shaft) around the center, the designed conical active offset magnetic bearing replaces the radial magnetic bearing and the axial magnetic bearing. The tapered active offset magnetic suspension bearing is a non-mechanical contact bearing. It can be a permanent magnetic bias, electromagnetically controlled active magnetic bearing or a hybrid bearing combining the two. According to the design plan, the tapered active bias magnetic bearing adopts a unitized design and is designed as 2R (R=1, 2, 3, 4, ...) minimum units, 2R minimum units can be flexibly and freely combined into T units, which are evenly distributed in pairs on the circumference of the central cylinder. The preferred structure T=1, 2, 3, 4, ....

In order to effectively control the tapered active offset magnetic suspension bearing, it also includes a sensor detection system, which includes an axial displacement sensor for the magnetic suspension bearing and a radial displacement sensor for the magnetic suspension bearing. The radial displacement sensor of the magnetic suspension bearing is located on the right side of one of the disc motors and is installed on the bracket located on the end cover of the stator housing, and the axial displacement sensor of the magnetic suspension bearing is installed on the axial bracket located on the end cover of the magnetic suspension bearing. The magnetic suspension bearing axial displacement sensor is used to detect the axial displacement of the conical active bias magnetic suspension bearing, and the magnetic bearing radial displacement sensor is used to detect the radial displacement of the conical active bias magnetic suspension bearing. According to the detected deviation, the radial active magnetic suspension bearing is controlled in real time to ensure that the central axis of rotation of the central cylinder is within the specified precision space.

The taper angle α of the tapered active offset magnetic suspension bearing is similar to the contact angle of the angular contact bearing, and its size can be designed according to the axial and radial bearing capacity.

In order to realize the rotation of the central rotating part (rotating shaft) around the center, the protection bearing is designed to protect the whole device from damage when it is subjected to a large external load impact or the tapered active bias magnetic suspension bearing fails. Among them, radial protection bearings are especially rolling bearings. Ball bearings as well as roller bearings can be considered as rolling protection bearings. In all cases, in order to achieve a frictionless suspension of the rotating shaft, the balls or rollers of the protective rolling bearing are kept at the same distance from a cylindrical surface on the only central rotating part (rotating shaft) and smaller than the air gap of the radial magnetic bearing .

Angular displacement sensors are used to achieve precise position control and speed control of rotating axes. It can be installed on the inner cylindrical surface of the central rotating part (axis of rotation) or on the outer cylindrical surface. The angular displacement sensor can choose an incremental sensor or an absolute sensor. According to a preferred embodiment, the angular displacement sensor is an incremental sensor, and the angular displacement sensor is fixed in a designed groove of the central rotating part (rotating shaft) through a viscous connection medium. Optionally, in order to construct a redundant system and improve the accuracy of the system, the angular displacement sensor is equipped with p (p=2, 4, 8) signal reading devices. After the angular displacement signal is processed by the controller, it is used for the position and speed control of the rotating shaft.

The advantage of the present invention is that it adopts a symmetrical unit type spliced disc type direct drive motor, integrates a tapered active offset magnetic suspension bearing, and the designed magnetic suspension directly drives the rotating shaft, which not only eliminates the friction torque of the mechanical bearing, but also improves the control accuracy , reducing the power consumption of the turntable system, no crawling phenomenon during ultra-low speed operation, high reliability of the overall device, and low failure rate. In addition, the structure designed by the invention is easy to process, assemble, and transport, has low maintenance cost, strong bearing capacity, high rotary positioning accuracy, good anti-vibration performance and the function of braking control error compensation.

Description of drawings

Figure 1. The overall cross-sectional view of the magnetic levitation rotating shaft driven by the unitary splicing disc motor when used alone;

Figure 2. Cross-sectional view of the axial tapered active magnetic bearing sensor;

Figure 3. Cross-sectional view of the axial angular position sensor;

Figure 4. Schematic diagram of the structure of the electromagnetic brake;

Figure 5. The overall structure of the axial protection bearing;

Figure 6. Schematic diagram of axial sensor installation;

Figure 7. Structural schematic diagram of radial protection bearing and disc direct drive motor;

Figure 8. Schematic diagram of the tapered active magnetic suspension bearing mechanism;

Figure 9. Schematic diagram of the installation mechanism of the angular position sensor;

Figure 10-1 and Figure 10-2 are the structural schematic diagrams of the stator spliced disc type direct drive motor respectively;

Figure 11-1 and Figure 11-2 are the schematic diagrams of the structure of the stator-spliced disc-type direct drive motor;

Figure 12-1 and Figure 12-2 are the structural schematic diagrams of the stator spliced disc type direct drive motor respectively;

Figure 13-1 and Figure 13-2 are the structural schematic diagrams of the stator spliced disc type direct drive motor respectively;

Figure 14-1 and Figure 14-2 are the schematic diagrams of the minimum stator unit structure respectively.

Detailed ways

Components that correspond to each other or have the same function are identified with the same symbols in all figures.

As shown in Fig. 1-Fig. 5, the unit type spliced disc type direct drive motor and its magnetic levitation rotating shaft of the present invention are mainly composed of base 1, unit type spliced disc type direct drive motor 5, 8, conical active magnetic suspension bearing 2, 6. Radial protective bearings 9, 10, axial protective bearings 3, 7, rotating shaft 5, axial tapered active magnetic suspension bearing sensor 11, axial tapered active magnetic suspension bearing sensor 12, and angular displacement sensor 13. The load is installed on the rotating shaft 4 and initialized before work. The tapered active magnetic suspension bearings 2 and 6 are initialized, and the control current is initialized according to the positions calibrated by the axial and radial tapered active magnetic suspension bearing sensors 11 and 12. The position of the rotating shaft, when working, when the rotating shaft needs to rotate or rotate at a certain angle, the controller controls the unit-type splicing disc-type direct drive motors 5 and 8 to execute system instructions.

The unit type splicing disc permanent magnet synchronous torque motor, according to the design plan, the unit type splicing permanent magnet synchronous torque motor is designed to be 2L (L=1, 2, 3, 4...) minimum Unit motors, 2L smallest units can be flexibly and freely combined into P unit motors. According to the size of the model, the optimal structure combination is P=1, 2, 3, 4. , each independent stator unit can operate independently as a motor, and can also operate synchronously. According to a preferred design scheme, in this device, the left and right two sets of unit type splicing permanent magnet synchronous torque motors 5, 8 each have four stator units, and each shares a rotor, which can independently or cooperatively drive the rotating shaft 4 to rotate.

The spliced unit structure design specifically means that each independent winding is passed through the positioning structure by the smallest stator winding unit. More specifically, the smallest stator unit (motor) is mainly composed of the stator shell 2-1, the stator core fixing plate 2-2, stator core 2-3, fixing bolt 2-4, stator winding 2-5, epoxy resin 2-6, magnetic air gap 2-7, permanent magnet protective cover 2-8, rotor magnetic ring ( Plate) 2-9, permanent magnet 2-10, set screw 2-11. 256 pieces of permanent magnets 2-10 are uniformly pasted on the rotor magnetic conducting ring (plate) 2-9 through epoxy resin. In order to prevent the permanent magnets 2-10 from falling off, a stainless steel protective cover is installed on the outer surface of the permanent magnets 2-10 2-8, the protective cover is fastened to the rotor magnetic conduction ring (plate) 2-9 through a connecting part, and the motor rotor is rigidly connected to the rotating shaft 4 through a connecting part 2-11.

The stator core 2-3 of the smallest stator unit (motor) is designed with a convex groove structure. According to the design requirements of the specific model, several smallest units are assembled into a complete stator unit (motor) 5, 8 through the convex groove positioning structure; each The stator core of each winding unit is formed by stamping silicon steel sheets through a progressive die at one time. As an example of this patent, but not limited to this, each winding stator core unit 2-3 is made of 400 pieces of 0.3mm silicon steel sheets It is formed by one-time stamping through a progressive die, and the stator core 2-3 and the stator winding 2-5 are insulated through an insulating isolation cover.

The cogging of each inner unit is designed to reduce the cogging effect; while the outermost winding unit of each complete stator unit is designed to reduce the end effect, specifically referring to the outermost winding unit of the stator unit. A favorable magnetic force loop structure is designed on the silicon steel sheets of the two stator windings, as shown in Figure 14-1 and Figure 14-2.

The motor rotor consists of n N poles and n S poles (n=1, 2, 3, ...) alternately and evenly distributed on the rotor shaft; the permanent magnet of each pole adopts a unit structure; each pole consists of m ( m=1, 2, 3,...) permanent magnets of the same length and the same polarity, and adopt the design to reduce the cogging effect; the m permanent magnets of the same length and the same polarity are assembled by the automatic glue assembly mechanism , S poles are evenly assembled on the rotor shaft of the motor in an alternate manner; a protection device is designed outside the permanent magnet to protect the permanent magnet.

As a specific implementation example, the motor rotor consists of 128 N poles and 128 S poles distributed on the rotor shaft alternately and evenly; the permanent magnet of each magnetic pole adopts a unit structure; the entire rotor is composed of 16 rotor units, each The rotor unit is alternately and evenly distributed with 8 N poles and 8 S poles permanent magnets 2-10, each pole is composed of 2 permanent magnets of equal length and same polarity, and adopts a design to reduce cogging; the 2 The permanent magnets of the same length and the same polarity are evenly bonded on the rotor magnetic conducting ring (plate) 2-9 in the way of alternating N and S poles; the permanent magnet 2-10 is equipped with a stainless steel protective cover 2-8, and the screw 2-11 is fixed on the rotor magnetic conducting ring (plate) 2-9.

In order to realize the rotation of the central rotating part (rotating shaft) around the center, the designed conical active offset magnetic bearing replaces the radial magnetic bearing and the axial magnetic bearing. The tapered active offset magnetic suspension bearing is a non-mechanical contact bearing. It can be a permanent magnetic bias, electromagnetically controlled active magnetic bearing or a hybrid bearing combining the two. According to the design plan, the tapered active bias magnetic bearing adopts a unitized design and is designed as 2R (R=1, 2, 3, 4...) minimum units, 2R minimum units can be flexibly and freely combined into T units, which are evenly distributed in pairs on the circumference of the central cylinder. The preferred structure is T=2,4.

According to a specific implementation, this example uses 4 conical permanent magnet bias magnetic suspension bearing units, and 4 conical active magnetic suspension bearing units 3 or 7 share one motor rotor. Four conical permanent magnetic bias magnetic suspension bearing units and four conical active magnetic suspension bearing units 3 or 7 are installed alternately and evenly on the same circumference. The conical active magnetic suspension bearing unit 3 or 7 and the rotor 3-6 form the main controllable magnetic suspension bearing. According to the feedback information of the axial and radial magnetic suspension bearing position sensors 11 and 12, the control system controls the axial position of the rotating shaft in real time. and radial position.

In the tapered active bias magnetic bearing described in Figure 8, its tapered active magnetic suspension bearing unit 3 mainly consists of a stator core 3-2, an inner magnetic guide ring 3-6, an outer magnetic guide ring (the motor stator shell ) 3-2, excitation coil 3-4, insulating cover 3-3, magnetic air gap 3-7, stator core pressure plate 3-7, axial magnetic suspension bearing position sensor 11, and radial magnetic suspension bearing position sensor 12. Four conical active magnetic suspension bearing units 3 are evenly distributed on the same circumference, and are fixed on the base 1 by 12 M20 bolts. Four orthogonally distributed axial magnetic suspension bearing position sensors 11 measure the axial displacement signal in the z direction of the rotation axis, and four orthogonally distributed radial magnetic suspension bearing position sensors 12 measure the rotation axis x, y2 orthogonal The axial displacement signal in the direction is sent to the axial permanent magnet bias active magnetic bearing. After being converted into a control value, the central rotating part of the shaft (rotary axis 4) is controlled in real time. The sensor is an eddy current displacement sensor, the probe model of which is RS-900500, and other types of sensors can also be used as required.

As shown in FIG. 7 , the axial auxiliary bearings 3 and 7 are mainly used to protect the entire device from damage when the rotating shaft 4 is impacted by a large external load or the tapered active bias magnetic suspension bearing fails. The designed axial auxiliary bearings 3 and 7 are mainly composed of bearing installation base 3-1, large ball 3-3, small ball 3-2, bearing end cover 3-4, fastening screw 3-5 and installation base 2-1 , The rotating shaft consists of 4 bearing support raceways and gaps. Axial auxiliary bearings should be used in pairs. According to the embodiment, 16 sets of auxiliary protective bearing units 3 are evenly distributed on the same circumference. The number of this design is not limited to 16, and can be combined freely according to the size and carrying capacity of the device. A spherical raceway matching the large ball 3-3 is designed on the rotating shaft 4, and the distance between each axial auxiliary bearing unit and the spherical raceway on the rotating shaft 4 is consistent by adjusting the bearing mounting base 3-1. According to the size of the magnetic air gap of the disc-type direct drive motor, the distance is preferably between 0.5-1mm. The adjusted axial auxiliary bearing unit is fixed on the installation plane designed by the base 3-1 through lock nuts.

As shown in FIG. 9 , the radial auxiliary bearings 9 and 10 are mainly used to protect the entire device from damage when the rotating shaft 4 is impacted by a large external load or the tapered active bias magnetic suspension bearing fails. The designed radial auxiliary bearings 9 and 10 are mainly composed of bearing mounting base 10-1, large ball 10-3, small ball 10-4, bearing end cover 10-5, fastening screw 10-2, contact angle α, bearing clearance It is composed of the installation base part 1 and the bearing support raceway of the rotating shaft 4. Radial auxiliary bearings should be used in pairs. There is a contact angle α between the large ball 10-3 and the bearing support raceway of the rotating shaft 4, which can realize axial and radial bidirectional constraints at the same time. For the specific implementation, α = 40,8 Sets of radial auxiliary bearings 9 and 10 are evenly distributed on the same circumference, and the number in this design is not limited to 8, and can be combined freely according to the size and bearing capacity of the device. A spherical raceway matching the large ball 3-3 is designed on the rotating shaft 4, and the distance between each axial auxiliary bearing unit and the spherical raceway on the rotating shaft 4 is consistent by adjusting the bearing mounting base 10-1. According to the size of the magnetic air gap of the disc-type direct drive motor, the axial distance component is preferably between 0.5-1 mm. The adjusted axial auxiliary bearing unit is fixed on the designed mounting plane of the base 1 through lock nuts.

Claims (10)

1. An ultra-low-speed unit type splicing disc type magnetic levitation torque motor, comprising a base, a pair of unit type splicing disc type direct drive motors, characterized in that the device has a rotationally symmetrical central rotating body and constrains the rotating A pair of tapered active offset magnetic suspension bearings for axial and radial movement of the body realizes the magnetic suspension support of the rotating shaft. At the same time, it is equipped with a corresponding pair of radial protection bearings, a pair of axial protection bearings and a position feedback system. On this basis, the central rotating body is driven redundantly or synchronously by a pair of unitary spliced disc direct drive motors. 2. The ultra-low-speed unit type splicing disc type magnetic suspension torque motor according to claim 1, characterized in that, the pair of unit type splicing disc type direct drive motors, a pair of conical active magnetic suspension bearings, a pair of radial A pair of axial protection bearings and a pair of axial protection bearings are symmetrically arranged relative to the axial center of the rotating shaft; initialization is performed before work, and the tapered active magnetic suspension bearing is initialized, according to the position calibrated by the axial and radial tapered active magnetic suspension bearing sensors , initialize the control current, control the position of the rotating shaft, and when working, when the rotating shaft needs to rotate or rotate at a certain angle, the controller controls the unit-type splicing disc-type direct drive motor to execute system instructions. 3. The ultra-low speed unit type splicing disc type magnetic levitation torque motor according to claim 1, characterized in that, the ultra low speed unit type splicing disc type magnetic levitation torque motor is a three-phase permanent magnet torque motor, which is designed as 2L minimum Unit motor, L=1, 2, 3, 4...; 2L smallest units can be flexibly and freely combined into P unit motors; each independent unit motor operates as a single motor, or operates synchronously. 4. The ultra-low-speed unit type splicing disc-type magnetic suspension torque motor according to claim 3, characterized in that, two sets of ultra-low-speed unit type splicing disc type magnetic suspension torque motors each have 4 stator units, each sharing a rotor, independent Or cooperating to drive the rotation shaft 4 in rotation; each of said direct drive unit motors comprises a rotor and energizable stator unit rigidly connected to said central rotating cylinder in a torsion-proof manner. 5. The ultra-low-speed unit type splicing disk type magnetic levitation torque motor according to claim 3, characterized in that, 2M independent stator units are evenly distributed on the same circumference, M=1, 2, 3, 4..., Each independent stator unit operates independently as a motor, or operates synchronously; the unit splicing structure design means that each independent stator unit motor is assembled by the smallest stator winding unit through a positioning structure; each winding unit The stator core is made of silicon steel sheets through a progressive die, and the cogging of each internal unit adopts a structure to reduce the cogging effect; while the outermost winding unit of each complete stator unit adopts a Design to reduce end face effect: On the silicon steel sheets of the two outermost stator windings of the stator unit, there is a closed loop structure for the magnetic force lines; the stator core and the stator winding are insulated by an insulating isolation cover. 6. The ultra-low-speed unit type splicing disc-type magnetic levitation torque motor according to claim 3, characterized in that, the motor rotor consists of p N poles and p S poles, p=1, 2, 3..., alternately The distribution is grouped on the rotor shaft; the permanent magnets of each magnetic pole adopt a unitary structure; each magnetic pole is composed of m permanent magnets of the same length and the same polarity, m=1,2,3...; and reduce cogging Effect design; the m permanent magnets of equal length and polarity are evenly assembled on the rotor shaft of the motor by the automatic gluing assembly mechanism in the manner of alternating N and S poles; a protection device is designed outside the permanent magnet to protect the permanent magnet . 7. The ultra-low-speed unit type splicing disc-type magnetic levitation torque motor according to claim 6, characterized in that, the motor rotor is distributed on the rotor shaft by 128 N poles and 128 S poles alternately and uniformly; each The permanent magnets of the magnetic poles adopt a unit structure; the whole rotor is composed of 16 rotor units, and each rotor unit is alternately distributed with 8 N poles and 8 S poles permanent magnets 2-10, and each pole is composed of 2 equal lengths and the same It is composed of permanent magnets with different polarity, and adopts the design to reduce the cogging effect; the two permanent magnets of the same length and the same polarity are uniformly bonded to the rotor magnetic ring or magnetic plate in the way of alternating N and S poles ; A stainless steel protective cover is installed outside the permanent magnet, which is fixed on the rotor magnetic ring or magnetic plate by screws. 8. The ultra-low-speed unit-type splicing disc-type magnetic suspension torque motor according to claim 1, wherein the radial auxiliary bearing is composed of a bearing mounting base, a large ball, a small ball, a bearing end cover, a fastening screw, a contact horn , bearing clearance, mounting base, and central slewing body bearing support raceway; radial auxiliary bearings should be used in pairs, and there is a contact angle between the large ball and the central slewing body bearing support raceway , realize axial and radial two-way constraints at the same time; there is a gap between the large ball and the supporting raceway of the rotating shaft bearing of the central gyratory body, and the axial distance component is between 0.5-1mm. 9. The ultra-low-speed unit type splicing disc-type magnetic suspension torque motor according to claim 1, characterized in that, the axial auxiliary bearing is mainly composed of a bearing mounting base, a large ball, a small ball, a bearing end cover, a fastening screw, It is composed of the installation base, the supporting raceway of the central slewing body bearing and the gap; the axial auxiliary bearing is used in pairs, and there is a gap between the large ball and the supporting raceway of the central slewing body bearing, and the distance is between 0.5-1mm. 10. The ultra-low-speed unitary splicing disc-type magnetic suspension torque motor according to any one of claims 1-9, characterized in that, the conical active bias magnetic suspension bearing is not a mechanical contact bearing; it is a permanent magnetic bias , Electromagnetically controlled active magnetic suspension bearings or hybrid bearings combining the two, the tapered active bias magnetic suspension bearings adopt a unitized design, which is designed as 2R minimum units, R=1, 2, 3, 4...; The 2R smallest units are flexibly and freely combined into T units, which are evenly distributed in pairs on the circumference of the central cylinder.