A multi-axis motor and a topological structure design method thereof

Abstract

The present invention discloses a novel coaxial single motor with multiple degrees of freedom and a method for designing its topological structure. The stator part of the motor adopts a centralized winding structure, and the number of degrees of freedom and the variable slot angle method are used to set the parameters of the centralized winding structure of the stator part; then, the rotor part of the motor is designed with a mixed embedded and coaxial sleeve shaft according to the structural parameters of the stator part, so as to form a coaxial single motor with multiple degrees of freedom; the method is designed to generate rotating magnetic fields with different numbers of magnetic pole pairs through a set of stator windings, realize decoupling control of multiple rotors and multi-degree-of-freedom operation, and use a split tooth structure to modulate the rotating magnetic field generated by the stator winding, obtain a newly added air gap magnetic field with an increased number of magnetic pole pairs, increase the pole ratio to increase the electromagnetic torque, and realize open-loop control under light load conditions. The present invention realizes the multi-degree-of-freedom control effect of a single motor, and has the advantages of high multi-axis synchronization and compact overall structure.

Description

Technical Field

[0001] The invention relates to the field of permanent magnet motor design, and in particular to a topological structure design method for a multi-axis motor. Background Art

[0002] In recent years, advanced equipment combined with artificial intelligence, such as industrial robotic arms, bionic robots, precision CNC machine tools, and intelligent medical devices, has developed rapidly and has become the primary research and development direction in the high-tech field. Most of the driving force for the automated operation of these highly intelligent devices comes from motors, and the realization of complex spatial motion or precise point positioning requires multi-dimensional coordinated operation of motors. The traditional multi-axis system composed of multiple single-degree-of-freedom motors and complex transmission mechanisms is prone to reduced control accuracy and weakened operating stability of the entire system due to error accumulation and inaccurate system models. Multi-degree-of-freedom single motors with multiple degrees of freedom can replace traditional multi-motor systems, effectively reduce the complexity of the system structure, improve the compactness of the actuator, and enhance the dynamic stability of the system, which has essential optimization significance for multi-degree-of-freedom systems.

[0003] Traditional multi-degree-of-freedom motors refer to motors with 2 or 3 degrees of rotational freedom that can rotate around any axis in a fixed space, including spherical motors and yaw motors used in omnidirectional devices such as robot joints and electric gyroscopes, dual mechanical port motors used in hybrid electric vehicles, reverse dual-rotor switched reluctance motors used in propulsion systems, dual-rotor radial flux motors used in air conditioners to simultaneously drive condensers and evaporators, dual three-phase dual-stator axial flux permanent magnet motors used in quadruped robot knee and hip joints, and coaxial multi-axis stepper motors used in multiple joints of robotic arms. At the same time, multi-degree-of-freedom motors also include rotary-linear motors that have both linear and rotary motions, which are used in robot joint drives, micro medical flaw detection devices, etc.

[0004] However, most multi-DOF motors have multiple sets of stator windings and multiple rotor structures, which are essentially just a combination of multiple single motors. They still require multiple sets of drivers and controllers, and the manufacturing process is complex. Compared with traditional multi-motor control systems, they have no obvious advantages. The structural design, dynamic analysis methods and control strategies of spherical motors and deflection motors with multiple stators and single rotor structures are complex, which limits their application. Summary of the invention

[0005] In view of the problems in the above background technology, the present invention proposes a multi-axis motor which is easy to install and can control multiple rotors with a single stator, and a topology design method thereof.

[0006] The coaxial multi-degree-of-freedom single motor designed by the method of the present invention is a multi-degree-of-freedom single motor that can control multiple rotors through a set of stator windings to achieve a multi-degree-of-freedom control effect of a single motor, and has the advantages of high multi-axis synchronization and compact overall structure.

[0007] The technical solution adopted by the present invention is:

[0008] S1. The stator part of the motor adopts a concentrated winding structure, and the parameters of the concentrated winding structure of the stator part are set by using the number of degrees of freedom and the variable slot angle method;

[0009] S2. Then, according to the structural parameters of the stator part, the rotor part of the motor is designed with a mixed embedded and coaxial sleeve shaft topology structure to form a coaxial multi-degree-of-freedom single motor.

[0010] Finally, a coaxial multi-degree-of-freedom single motor is manufactured according to the topological structure designed by the method of the present invention.

[0011] The stator part has a plurality of teeth arranged at intervals along the circumferential direction on the inner circumferential surface, the number of teeth is n times the number of phases, n is a natural number, and a coil is wound on each tooth as a coil winding.

[0012] The step S1 comprises:

[0013] S11, according to the number of degrees of freedom of the motor, using a variable slot angle method to set the number of phases and the number of rotors of the motor;

[0014] S12. Based on the magnetic field modulation principle, a split tooth structure is added to the stator teeth to increase the number of magnetic pole pairs of the armature magnetic field of the motor, and the number of teeth in the split tooth structure is set.

[0015] In the step S11, the number of phases of the motor and the rotor shaft in the rotor part are set according to the number of degrees of freedom of the coaxial multi-degree-of-freedom single motor:

[0016] In the coaxial multi-degree-of-freedom single motor, firstly, the number of degrees of freedom is n DOF Set the minimum number of phases constraint:

[0017] m ≥2 n DOF

[0018] in, n DOF Indicates the number of degrees of freedom of a coaxial multi-degree-of-freedom single motor.

[0019] Then, according to the minimum phase number constraint combined with Kirchhoff's law, an additional phase is added, and then the most appropriate phase number is set according to the following formula:

[0020] m =2 n DOF +1

[0021] And the number of rotor shafts in the rotor part of the coaxial multi-degree-of-freedom single motor is set to be consistent with the number of degrees of freedom.

[0022] The step S12 is specifically as follows:

[0023] A split tooth is arranged in the annular air gap as a modulation unit. The split tooth is formed by arranging a plurality of magnetic conductive blocks at intervals on the end surface of each tooth of the stator part. Each magnetic conductive block serves as a tooth of the split tooth, and a tooth groove of the split tooth is formed between two adjacent magnetic conductive blocks.

[0024] The number of magnetic pole pairs of the newly added air gap magnetic field introduced after setting the modulation unit p ad :

[0025] p ad= p a

[0026] in, p a express m The number of pole pairs of the armature magnetic field of the coaxial multi-degree-of-freedom single motor with the same phase;

[0027] After using split teeth, the number of magnetic pole pairs of the coaxial multi-degree-of-freedom single motor excitation magnetic field is obtained according to the following formula: p e , which is equivalent to obtaining the number of teeth on the rotor shaft:

[0028] p ad =| p e - p f |

[0029] p f = n f Z s

[0030] in, p e is the number of magnetic pole pairs of the excitation magnetic field, that is, the sum of the number of teeth of individual gears on all rotor shafts; p f is the number of pole pairs of the modulation unit, that is, the number of magnetic blocks. In the structure using split teeth, it is the total number of split teeth. Z sThe number of main teeth is the number of teeth in the stator part; n f Indicates the number of teeth on the split tooth.

[0031] The step S2 comprises:

[0032] S21. Designing a hybrid embedded structure in the rotor part of the motor;

[0033] S22, arranging a plurality of hybrid embedded structures having the same number of degrees of freedom as the motor in the axial direction and on the same axis, and the polarities of adjacent hybrid embedded structures are opposite;

[0034] S23. A sleeve shaft structure is used to connect different rotor shaft components, and adjacent rotor shaft components are connected by ball bearings to form an integral rotor part.

[0035] In the step S21, an axially magnetized permanent magnet is embedded and fixed between two gears to form a hybrid embedded structure. Each gear is composed of multiple silicon steel sheets stacked along the axial direction. The number of teeth of the two gears is the same and equal to the number of magnetic pole pairs passing through the armature magnetic field. p a and the number of pole pairs of the modulation unit p f Calculated p e = p a + p f , and the two gears are staggered by a tooth pitch in the circumferential direction. The permanent magnet is axially magnetized so that the two gears are magnetized to N pole and S pole respectively.

[0036] In the step S22, a plurality of hybrid embedded structures having the same number of degrees of freedom as the motor are arranged axially and coaxially with equal spacing, and the axial magnetic poles of each adjacent hybrid embedded structure are arranged oppositely.

[0037] In the step S23, each hybrid embedded structure is fixedly mounted on a corresponding rotating shaft to form a rotor shaft, and the rotating shafts corresponding to each hybrid embedded structure are connected from the inside to the outside in sequence through a ball bearing movable set, and each rotating shaft is connected to its own power source and driven to rotate by the power source, so that each hybrid embedded structure is combined in a sleeve shaft manner to form independent rotations corresponding to different degrees of freedom.

[0038] Finally, the above-mentioned topological structure design method can be used to design and manufacture the specific coaxial multi-degree-of-freedom single motor of the present invention.

[0039] The innovation of the present invention lies in the structural design of axially stacking multiple rotors in a single set of windings and the processing of coaxial sleeve installation of multiple rotating shafts, which brings the advantage of further improving the structural compactness of the multi-degree-of-freedom motor and realizes the effect of a single motor outputting multiple controllable degrees of freedom. Compared with the traditional system of multiple motors outputting multiple controllable degrees of freedom, it has the advantages of high integration and high synchronization.

[0040] The coaxial multi-degree-of-freedom single motor of the present invention refers to a motor having multiple coaxial, independently rotatable and controllable rotor shafts, each of which is connected to a respective power source and driven to rotate by the respective power source.

[0041] The coaxial multi-degree-of-freedom single motor is a multi-phase concentrated winding motor with a phase number greater than or equal to 3, and is also an end star-connected motor.

[0042] The motor designed in the present invention is based on the principle of variable slot angle. A set of stator windings are used to generate rotating magnetic fields with different numbers of magnetic pole pairs, so as to realize decoupling control of the three rotors and further realize three-degree-of-freedom operation. At the same time, based on the principle of magnetic field modulation, the rotating magnetic field generated by the stator winding is modulated by a split tooth structure to obtain a newly added air gap magnetic field with an increased number of magnetic pole pairs, and to increase the pole ratio to increase the electromagnetic torque, so that open-loop control can be achieved under light load conditions. In addition, the above principles and decoupled operation performance are verified by finite element simulation methods. Finally, experiments are carried out on the manufactured prototype to verify the feasibility of the proposed multi-degree-of-freedom motor to achieve three-degree-of-freedom operation.

[0043] The beneficial effects of the present invention are:

[0044] 1) The method of the present invention can be used to design a novel coaxial multi-degree-of-freedom single motor. Based on the variable slot angle method, the number of phases of the motor can be accurately designed according to the required number of controllable degrees of freedom, and the number of pole pairs of the armature magnetic field of the motor can be increased through the split tooth structure. Based on the magnetic field modulation principle, the pole ratio is expanded and the output torque of the motor is increased, so that it can achieve open-loop operation under light load.

[0045] 2) The method of the present invention designs a hybrid embedded rotor to convert the surface-mounted permanent magnet into a simplified structure of a gear plus a single piece of unidirectionally magnetized permanent magnet, eliminating the permanent magnet processing and mounting procedures, especially in smaller-sized multi-pole-pole-pair motors, eliminating the high-difficulty and low-precision permanent magnet mounting process, which can greatly reduce the production cost and manufacturing difficulty of the motor.

[0046] 3) The coaxial multi-degree-of-freedom single motor designed by the method of the present invention can achieve the effect of a single motor outputting multiple controllable degrees of freedom. Compared with the traditional method of realizing multi-degree-of-freedom control by combining multiple motors, it has the advantages of simple installation, high multi-axis synchronization and compact overall structure.

[0047] In summary, the method of the present invention proposes for the first time a motor topology design method that uses a single rotating magnetic field to simultaneously control multiple rotors, expanding the principles and topology types of multi-degree-of-freedom motors. The designed motor topology has the advantages of compact structure, easy installation, and light-load open-loop operation. It can replace the traditional multi-motor combination in application scenarios that require multiple control degrees of freedom, and has great application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a logical relationship diagram of the method of the present invention;

[0049] Figure 2 A schematic diagram of phase band division of a 7-phase 3-DOF motor using a variable slot angle method in an embodiment;

[0050] Figure 3 A schematic diagram of a 7-phase concentrated and common-pole winding with a driving circuit in an embodiment;

[0051] Figure 4 A schematic diagram of a hybrid embedded rotor structure of a three-degree-of-freedom motor of an embodiment;

[0052] Figure 5 A schematic diagram of a multi-axis sleeve shaft of a three-degree-of-freedom motor of an embodiment;

[0053] Figure 6 This is a physical picture of the three-degree-of-freedom motor of the embodiment. DETAILED DESCRIPTION

[0054] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] The coaxial multi-degree-of-freedom single motor designed by the present invention comprises a stator part and a rotor part;

[0056] The stator part is sleeved on the outer periphery of the rotor part, and an annular air gap is provided between the stator part and the rotor part;

[0057] The stator part has a plurality of teeth arranged at intervals along the circumferential direction on the inner circumferential surface, the number of teeth is n times the number of phases, n is a natural number, slots are formed between adjacent teeth, a coil is wound on each tooth as a coil winding, a magnetic conductive block can be arranged on the inner end surface of each tooth to form a split tooth, all teeth have the same radial length, and there is an air gap between the inner end surfaces of all teeth and the rotor part;

[0058] In a specific implementation, the number of teeth of the stator part is n times the number of phases, where n is a natural number. One tooth and the coil wound thereon, i.e., the coil winding, is one phase, and each phase is evenly spaced along the circumferential direction.

[0059] If there are at least two coil windings in the same phase, the coil windings of the same phase are arranged symmetrically along the circumferential direction. All coil windings of the same phase are connected in series, and coil windings of different phases are connected in parallel. The coil windings of each phase are led out and connected to an external pulse controller through a half-bridge drive circuit.

[0060] The rotor part includes a plurality of coaxially arranged, independently rotatable and controllable rotor shafts, each of which is coaxially movable and relatively independently rotated. Each rotor shaft is mainly composed of a rotating shaft and two gears and permanent magnets coaxially fixedly mounted on the rotating shaft. The two gears have the same number of teeth, and a permanent magnet is arranged between the two gears, that is, the permanent magnet is located on both sides of the two gears. Each rotor shaft is connected to its own power source and is driven to rotate by its own power source.

[0061] The two gears in each rotor shaft have the same number of teeth, and the gears of different rotor shafts may have different numbers of teeth.

[0062] The number of rotor shafts corresponds to the number of degrees of freedom of the motor.

[0063] In a specific implementation, the overall hybrid embedded structure consisting of two gears and permanent magnets in each rotor shaft is fixedly mounted on the bottom of the rotating shaft, and the rotating shafts of each rotor shaft are sequentially passed through the ball bearing set from the inside to the outside, so that the overall hybrid embedded structure consisting of two gears and permanent magnets is arranged along the coaxial axial spacing.

[0064] Different rotor shafts are coaxially connected from the inside to the outside by a sleeve structure, and adjacent rotor shafts are connected by ball bearings, so that multiple rotor shafts of the motor can operate independently of each other.

[0065] In each rotor shaft, each gear is composed of a plurality of silicon steel sheets stacked axially, and the two gears in each rotor shaft are staggered by a tooth pitch in the circumferential direction, that is, the tooth axis of the upper gear is aligned with the tooth groove of the upper gear in the upward direction.

[0066] The permanent magnet is axially magnetized so that the two gears are magnetized to the N pole and the S pole respectively.

[0067] The specific embodiments of the present invention and the design process thereof are as follows:

[0068] Taking the design of a coaxial three-degree-of-freedom single motor by the method of the present invention as an example, the topology design method of the multi-degree-of-freedom single motor of the present invention is as follows:

[0069] The stator part of the motor adopts a centralized winding structure. A plurality of teeth are arranged on the inner circumferential surface of the stator part at intervals in the circumferential direction. The number of teeth is n times the number of phases, where n is a natural number. A coil is wound on each tooth as a coil winding.

[0070] like Figure 2As shown, this is a schematic diagram of phase band division when a 7-phase three-degree-of-freedom motor adopts the variable slot angle method. When the slot angles are π / 2, π / 4, and π / 6, the phase bands are divided into 4, 8, and 12 respectively, and the armature magnetic field presents 2, 4, and 6 pairs of poles.

[0071] The logical steps involved in the embodiment are as follows: Figure 1 shown.

[0072] 1) According to the number of degrees of freedom required by the motor, the number of phases in the stator part of the motor and the number of rotor shafts are set using the variable slot angle method designed by the present invention.

[0073] The number of phases of the motor and the rotor shaft in the rotor part are both set according to the number of degrees of freedom of the coaxial multi-degree-of-freedom single motor.

[0074] In general, the phase sequence of each phase current is determined, that is, it follows ABC-…, and the number of pole pairs of the armature magnetic field formed by the power-on of all stator coils depends on the arrangement of the coil windings. For a certain set of motor windings, the number of pole pairs of the armature magnetic field is fixed. However, in the coaxial multi-degree-of-freedom single motor described in the present invention, the multi-phase winding has control redundancy, and the number of pole pairs of the armature magnetic field is changed by changing the phase difference of each phase excitation.

[0075] The number of slots for a stator section is Q s , the number of magnetic pole pairs is p of m The coaxial multi-degree-of-freedom single motor with two phases is set to have a slot angle of a =(2 p p) / Q s The slot pitch angle is used to characterize the phase difference between the current vectors in adjacent slots.

[0076] Number of slots in the stator section Q s When the number of magnetic pole pairs of a coaxial multi-DOF single motor is determined, p and slot angle a Related to, with the slot angle a Change and change.

[0077] Based on the definition of the slot angle, the following method is used to change the number of pole pairs of the armature magnetic field: keep the original winding arrangement, change the phase sequence of power supply to change the slot angle.

[0078] For the single-stator, multi-rotor, multi-degree-of-freedom motor of the present invention, which requires the simultaneous existence of multiple armature magnetic field pole pairs, the winding arrangement has only one fixed form, and the above method needs to be used to achieve the change of the armature magnetic field pole pair number to generate different rotating magnetic fields, thereby controlling different rotors.

[0079] The concentrated winding motor with the same number of slots / teeth and phases is defined as the minimum unit motor, that is, m The minimum unit motor of the phase motor is m Slot concentrated winding motor.

[0080] The number of slots / teeth is km of m In a motor with two phases, the number of pole pairs of the armature magnetic field is equal to the number of pole pairs of the smallest unit motor. k By analyzing the number of pole pairs of the armature magnetic field of the smallest unit motor, we can explore all possible situations of the number of pole pairs of the armature magnetic field generated by the motor when using the variable slot angle method.

[0081] Establish the constraint that the number of pole pairs of the armature magnetic field of the minimum unit motor is not greater than the number of phases, satisfying 2 p ≤ m ,therefore m The minimum unit motor of a phase can only produce at most [m / 2] pole pairs through the variable slot angle method, and [] indicates rounding down.

[0082] Therefore, in the common three-phase minimum unit motor, at most only one pair of poles can be generated, and the number of pole pairs of the armature magnetic field can only be increased by increasing the number of slots and changing the winding arrangement; m >3) In the motor, the increase in the number of phases allows the phase sequence of each current to change. This control redundancy increases the number of armature magnetic field pole pairs that can be generated by the smallest unit motor.

[0083] Based on this, in the coaxial multi-degree-of-freedom single motor, the number of degrees of freedom is first n DOF Set the minimum number of phases constraint:

[0084] m ≥2 n DOF

[0085] in, n DOF Indicates the number of degrees of freedom of a coaxial multi-degree-of-freedom single motor.

[0086] Then, considering the end star connection structure of the coaxial multi-DOF single motor, an additional phase is added according to the minimum phase number constraint combined with Kirchhoff's law of the circuit, and then the most appropriate stator phase number is set according to the required number of degrees of freedom according to the following formula:

[0087] m =2 n DOF +1

[0088] And the number of rotor shafts in the rotor part of the coaxial multi-degree-of-freedom single motor is set to be consistent with the number of degrees of freedom.

[0089] In the embodiment, the number of phases required for the three-degree-of-freedom motor is:

[0090] m =2×3+1=7

[0091] like Figure 3 The figure shows a schematic diagram of a 7-phase concentrated and shun-pole winding with a drive circuit. The winding is arranged counterclockwise in the order of 1-2-3-4-5-6-7 phases, and the ends are connected in star shape. The 7-phase winding can generate three armature magnetic fields with pole pairs of 2, 4, and 6. There are three control degrees of freedom, and the number of rotor shafts is 3.

[0092] 2) Based on the principle of magnetic field modulation, a split tooth structure is added to the stator teeth to increase the number of magnetic pole pairs of the armature magnetic field of the motor, which is used to improve the pole ratio of the motor and increase the electromagnetic torque, so that it can operate in open loop under light load conditions.

[0093] Specifically, a split tooth is arranged in the annular air gap as a modulation unit, and the split tooth is formed by arranging a plurality of magnetic conductive blocks at intervals on the inner end surface of each tooth of the stator part, each magnetic conductive block serves as a tooth of the split tooth, and a tooth groove of the split tooth is formed between two adjacent magnetic conductive blocks;

[0094] After adding a modulation unit in the annular air gap according to the magnetic field modulation principle, the magnetic permeability of the modulation unit is greater than the magnetic permeability of the air, and the magnetic flux tends to pass through the modulation unit, thereby introducing new magnetic field harmonics and changing the air gap magnetic field.

[0095] The number of magnetic pole pairs of the newly added air gap magnetic field introduced after setting the modulation unit p ad for:

[0096] p ad= p a

[0097] in p a express m The number of pole pairs of the armature magnetic field of the phase motor.

[0098] After using split teeth, the number of magnetic pole pairs of the coaxial multi-degree-of-freedom single motor excitation magnetic field is obtained according to the following formula: p e :

[0099] p ad =| p e -p f |

[0100] p f = n f Z s

[0101] in, p e is the number of magnetic pole pairs of the excitation magnetic field, which is the sum of the number of teeth of the individual gears on all rotor shafts, and is also the number of magnetic pole pairs of the permanent magnet. In the hybrid embedded rotor, it is the number of teeth of each rotor. p g ; p f is the number of magnetic conductive blocks on all modulation units, which is 3*14 in the specific implementation; Z s The number of main teeth is the number of teeth in the stator part; n f Indicates the number of teeth on the split tooth, which is a preset parameter.

[0102] Because the split-tooth structure expands the number of pole pairs of the motor's armature magnetic field, the multi-degree-of-freedom motor can have a higher number of pole pairs, and thus a high pole ratio and high output torque, making it similar to a stepper motor and able to achieve open-loop operation under lighter loads.

[0103] like Figure 2 As shown in the figure, the stator of the designed three-degree-of-freedom motor adopts a 14-slot structure, and each stator tooth has 3 split auxiliary teeth, a total of 14 main teeth and 42 small teeth. The topological structure using split teeth is: p f = n f Z s =3×14=42.

[0104] From the above, it can be seen that the 7-phase 14-slot concentrated and common-pole windings can generate armature magnetic fields with pole pairs of 2, 4, and 6, so the corresponding excitation magnetic field pole pairs are p er Should be:

[0105] p e1 =42+2=44

[0106] p e2 =42+4=46

[0107] p e3=42+6=48

[0108] 3) Designing a hybrid embedded structure in the rotor part of the motor so as to realize the permanent magnet rotor part with a higher number of magnetic pole pairs of the excitation magnetic field as mentioned above;

[0109] In order to make the number of pole pairs of the excitation magnetic field p e To match the high pole-pole-pair armature magnetic field obtained by magnetic field modulation in step 2), the present invention transforms the traditional surface-mounted permanent magnet rotor and adopts a hybrid embedded structure to construct the required high pole-pole-pair permanent magnet rotor.

[0110] This step is to embed and fix an axially magnetized permanent magnet between the two gears to form a hybrid embedded structure. Each gear is composed of multiple silicon steel sheets stacked along the axial direction. The number of teeth of the two gears is the same and is equal to the number of pole pairs of the excitation magnetic field and the number of pole pairs of the modulation unit calculated above. p e = p a + p f , and the two gears are staggered by a tooth pitch in the circumferential direction. The permanent magnet is axially magnetized so that the two gears are magnetized to N pole and S pole respectively.

[0111] When axial magnetic flux is ignored, the number of teeth on the gear p g The hybrid embedded rotor is equivalent to a magnetic pole pair p e The surface mounted permanent magnet rotor, p e = p g .

[0112] The above-mentioned hybrid embedded structure of the present invention eliminates the permanent magnet processing and mounting procedures by converting the surface-mounted permanent magnets into gears. In particular, it eliminates the difficult and low-precision permanent magnet mounting process in smaller-sized multi-pole-pole-pair motors, which can greatly reduce the production cost and manufacturing difficulty of the motor.

[0113] like Figure 4 As shown, three rotors ( r ∈[1,3]) the number of teeth of the gear p gr They are 44, 46, and 48 respectively, which are equivalent to the number of magnetic pole pairs. p er = p gr Permanent magnet rotor.

[0114] 4) The hybrid embedded structures of multiple rotor shaft components with the same number of degrees of freedom as the motor are arranged in the axial direction and on the same axis, and the polarities of the hybrid embedded structures of adjacent rotor shaft components are opposite, which can weaken the coupling of the axial magnetic fields between different rotors.

[0115] This step is to arrange multiple hybrid embedded structures with the same number of degrees of freedom as the motor axially and coaxially with equal spacing, and the axial magnetic poles between each adjacent hybrid embedded structure are arranged oppositely.

[0116] In specific implementation, Figure 3 As shown, the three hybrid embedded structures are arranged coaxially in the axial direction. The three hybrid embedded structures are arranged at equal intervals along the axial direction of the motor, the axis of each rotor is collinear, and each adjacent hybrid embedded structure is arranged in a manner with opposite axial magnetic poles, that is, the magnetic pole direction in the axial direction from the output shaft side to the bottom of the motor is "rotor shaft 1 (NS) → rotor shaft 2 (SN) → rotor shaft 3 (NS) →...", so as to minimize the spatial coupling of the magnetic fields of different rotors.

[0117] 5) A sleeve shaft structure is used to connect different rotor shaft components, and adjacent rotor shaft components are connected by ball bearings to form an integral rotor part, so that multiple rotor shaft components of the motor can operate and output independently of each other.

[0118] In step 5), each hybrid embedded structure is fixedly mounted on the bottom of a corresponding rotating shaft to form a rotor shaft. The rotating shafts corresponding to different hybrid embedded structures have different diameters. The rotating shafts corresponding to the hybrid embedded structures are connected from the inside to the outside in sequence through ball bearing movable sets, and each rotating shaft is connected to its own power source and driven to rotate by the power source, so that the hybrid embedded structures are combined in a sleeve shaft manner to form independent rotations corresponding to different degrees of freedom.

[0119] like Figure 5 As shown, the three rotating shafts of the three-degree-of-freedom motor are combined in the form of sleeve shafts, that is, shaft 3 is inserted into shaft 2, and then the two are inserted into shaft 1 together to complete the sleeve shaft. The rotating shafts are in contact with each other through ball bearings and are ideally independent of each other.

[0120] Specifically, the design principle of the sleeve shaft is that the rotor farthest from the output side and close to the bottom of the motor has the smallest shaft diameter and the longest length, and the shaft diameter of the rotors closer to the output shaft side gradually increases and the length decreases, so that the shaft of the rotor from the output shaft side to the bottom of the motor can be continuously inserted into the shaft of the previous rotor along the axial direction to realize the sleeve shaft structure.

[0121] Finally, a coaxial multi-degree-of-freedom single motor is manufactured according to the topological structure designed by the method of the present invention.

[0122] In the present invention, the designed coaxial 7-phase 3-DOF motor is used to carry out multi-DOF control test experiment. Figure 6 As shown. The control signal generated by the RT-LAB device drives the 7-phase half-bridge circuit, the control frequency is 20kHz, the bus voltage is 5 V, the control method is basic SPWM, the whole experiment adopts open-loop control, and the load condition is no-load. In order to verify the decoupling operation characteristics of the three-degree-of-freedom motor, the operation performance of axis 1, axis 2 and axis 3 in the same direction, reverse direction, same speed and non-same speed is tested under no-load conditions, as shown in Table 1.

[0123] Table 1 Three-degree-of-freedom motor decoupling operation experiment

[0124]

[0125] Experimental results show that the proposed three-degree-of-freedom motor can achieve decoupled operation under different working conditions.

[0126] It can be seen from the implementation that the coaxial multi-degree-of-freedom motor designed by the method of the present invention can realize multi-degree-of-freedom decoupling operation, the control of each axis is independent, and the multi-degree-of-freedom operation can be completed. It can also run in an open loop under no-load conditions, and has strong multi-axis decoupling performance and stability. Compared with the traditional multi-motor combination to achieve multi-degree-of-freedom control, it has the advantages of simple installation, high multi-axis synchronization, and compact overall structure.

[0127] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for designing a topological structure of a multi-axis motor, characterized in that: Methods include: S1. The stator part of the motor adopts a concentrated winding structure, and the parameters of the concentrated winding structure of the stator part are set by using the number of degrees of freedom and the variable slot angle method; The step S1 comprises: S11, according to the number of degrees of freedom of the motor, using a variable slot angle method to set the number of phases and the number of rotors of the motor; S12. Based on the magnetic field modulation principle, a split tooth structure is added to the stator teeth, thereby increasing the number of magnetic pole pairs of the armature magnetic field of the motor, and setting the number of teeth in the split tooth structure; In the step S11, the number of phases of the motor and the rotor shaft in the rotor part are set according to the number of degrees of freedom of the same multi-axis motor: In the multi-axis motor, firstly, the number of degrees of freedom n DOF Set the minimum number of phases constraint: m≥2n DOF Among them, n DOF Indicates the number of degrees of freedom of the multi-axis motor; Then, according to the minimum phase number constraint combined with Kirchhoff's law, an additional phase is added, and then the most appropriate phase number is set according to the following formula: <h2 style=";text-align:left;direction:ltr">m = 2n<h2 style=";text-align:left;direction:ltr"> DOF <h2 style=";text-align:left;direction:ltr"> +1 and setting the number of rotor shafts in the rotor part of the multi-axis motor to be consistent with the number of degrees of freedom; S2. Then, according to the structural parameters of the stator part, the rotor part of the motor is designed with a mixed embedded and coaxial sleeve shaft topology to form a multi-axis motor.

2. The method for designing a topological structure of a multi-axis motor according to claim 1, characterized in that: The stator part has a plurality of teeth arranged at intervals along the circumferential direction on the inner circumferential surface, the number of teeth is n times the number of phases, n is a natural number, and a coil is wound on each tooth as a coil winding.

3. The method for designing a topological structure of a multi-axis motor according to claim 1, characterized in that: The step S12 is specifically as follows: A split tooth is arranged in the annular air gap as a modulation unit. The split tooth is formed by arranging a plurality of magnetic conductive blocks at intervals on the end surface of each tooth of the stator part. Each magnetic conductive block serves as a tooth of the split tooth, and a tooth groove of the split tooth is formed between two adjacent magnetic conductive blocks. The number of magnetic pole pairs p of the newly added air gap magnetic field introduced after setting the modulation unit ad : p ad＝ p a Among them, p a Represents the number of pole pairs of the armature magnetic field of the m-phase motor; After adopting the split teeth, the number of magnetic pole pairs p of the excitation magnetic field of the multi-axis motor is obtained according to the following formula: e , and then obtain the number of teeth on the rotor shaft: p ad =|p e -p f | p f =n f Z s Among them, p e is the number of pole pairs of the excitation magnetic field, that is, the sum of the number of teeth of the individual gears on all rotor shafts; p f is the number of pole pairs of the modulation unit, that is, the number of magnetic blocks. In the structure using split teeth, it is the total number of split teeth. s The number of main teeth, that is, the number of teeth in the stator part; n f Indicates the number of teeth on the split tooth.

4. The method for designing a topological structure of a multi-axis motor according to claim 3, characterized in that: The step S2 comprises: S21. Designing a hybrid embedded structure in the rotor part of the motor; S22, arranging a plurality of hybrid embedded structures having the same number of degrees of freedom as the motor in the axial direction and on the same axis, and the polarities of adjacent hybrid embedded structures are opposite; S23. A sleeve shaft structure is used to connect different rotor shaft components, and adjacent rotor shaft components are connected by ball bearings to form an integral rotor part.

5. The method for designing a topological structure of a multi-axis motor according to claim 4, characterized in that: In the step S21, an axially magnetized permanent magnet is embedded and fixed between two gears to form a hybrid embedded structure. Each gear is composed of multiple silicon steel sheets stacked along the axial direction. The number of teeth of the two gears is the same and equal to the number of magnetic pole pairs passing through the armature magnetic field p. a and the number of pole pairs of the modulation unit p f The calculated p e =p a +p f , and the two gears are staggered by one tooth pitch along the circumferential direction.

6. The method for designing a topological structure of a multi-axis motor according to claim 4, characterized in that: In the step S22, a plurality of hybrid embedded structures having the same number of degrees of freedom as the motor are arranged axially and coaxially with equal spacing, and the axial magnetic poles of each adjacent hybrid embedded structure are arranged oppositely.

7. The method for designing a topological structure of a multi-axis motor according to claim 4, characterized in that: In the step S23, each hybrid embedded structure is fixedly mounted on a corresponding rotating shaft to form a rotor shaft, and the rotating shafts corresponding to each hybrid embedded structure are connected from the inside to the outside in sequence through a ball bearing movable set, and each rotating shaft is connected to its own power source and driven to rotate by the power source, so that each hybrid embedded structure is combined in a sleeve shaft manner to form independent rotations corresponding to different degrees of freedom.

8. A multi-axis motor, characterized in that: The topological structure is designed and obtained by adopting any one of the topological structure design methods described in claims 1-7.

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