12: 4 slot-pole matching inter-pole bearingless brushless direct current motor and manufacturing method thereof

Abstract

The invention discloses a 12: 4 slot pole matching inter-pole bearingless brushless direct current motor and a manufacturing method thereof, and belongs to the technical field of novel special alternating current motors and driving control thereof. The motor comprises a stator structure and a permanent magnet rotor topological structure. The stator adopts a 12: 4 slot pole matching duplex winding structure, and a torque winding and a suspension winding are respectively wound on the inner layer and the outer layer of a stator slot; the rotor inter-pole permanent magnet structure is magnetized to form four main magnetic poles and four auxiliary magnetic poles, and a shoulder-type trapezoidal wave-like air-gap magnetic field is obtained through different magnetizing directions of the main magnetic poles and the auxiliary magnetic poles. By adopting the permanent magnet rotor with the radial magnetizing main magnetic pole and the tangential parallel magnetizing auxiliary magnetic pole and winding the double-winding structure on the stator slot, the motor power density can be effectively improved, the torque ripple can be reduced and the good magnetic suspension operation control performance can be obtained while the good radial suspension control characteristic is maintained.

Description

Technical Field

[0001] The present invention relates to the field of novel special AC motors and drive control technology thereof, and in particular to a bearingless brushless DC motor with a 12:4 slot-pole ratio and inter-pole ratio and a manufacturing method thereof. Background Art

[0002] Research has been conducted at home and abroad on the dual-winding bearingless brushless DC motor (BL-BLDC motor for short) and its control technology. In terms of torque control, the "three-phase two-pass" working mode of the traditional brushless DC motor has been basically adopted; in terms of rotor magnetic suspension control, research has been conducted on accurate modeling of magnetic suspension force, stator / rotor structure, magnetic suspension performance analysis and control strategy. At present, the rotor permanent magnet of the BL-BLDC motor usually adopts a single radial magnetized N and S pole alternating structure. The magnetic field weakening phenomenon at both ends of the flat-top part of the trapezoidal wave air gap magnetic field is an important reason for the increase of torque pulsation and the decrease of torque mean value in the commutation stage. Therefore, exploring new rotor permanent magnet topology and combined magnetization methods to ensure the radial magnetic suspension force control characteristics and obtain excellent torque control characteristics is the key to solving the problem.

[0003] The results of literature and patent search show that: Internationally, permanent magnet Halbach array structure is applied to ordinary brushless DC motors, but this magnetization method is relatively complex, and modeling and implementation are relatively difficult. There are literatures at home and abroad that apply radial and circumferential combined magnetization permanent magnet structure to ordinary permanent magnet brushless motors, but the three-phase current passed is not DC, and it is not a brushless DC motor in the strict sense, let alone the BL-BLDC motor of this patent application. Domestic and foreign research on "BL-BLDC motors" mainly focuses on the conduction law of suspension windings, mathematical modeling of magnetic suspension force, control systems, etc., and there are few literature reports on the optimization and improvement of the permanent magnet rotor structure of BL-BLDC motors. Summary of the invention

[0004] The purpose of the present invention is to improve the flat-top area magnetic field of the trapezoidal wave air gap magnetic field, ensure the radial magnetic suspension force control characteristics, obtain excellent torque control characteristics, reduce torque pulsation, and ensure control characteristics that are beneficial to or do not reduce the radial suspension force through a new rotor permanent magnet topology structure and a combined magnetization method.

[0005] To achieve the above-mentioned purpose, the present invention provides a 12:4 slot-pole ratio interpole bearingless brushless DC motor, comprising a stator structure, a torque winding, a suspension winding and a permanent magnet rotor topology structure, wherein a plurality of stator slots are evenly arranged on the inner surface of the stator structure, the torque winding and the suspension winding are respectively wound in the stator slots, and the permanent magnet rotor topology structure is arranged in the stator structure.

[0006] Preferably, the bottom of the stator slot adopts a rounded flat-bottom slot structure, and the upper and lower widths of the slot body between two adjacent stator slots are equal.

[0007] Preferably, the coil cross-sectional area of ​​the torque winding accounts for 60% to 70% of the stator slot cross-sectional area, and the stator slot cross-sectional area is equal to the sum of the coil cross-sectional area of ​​the torque winding and the coil cross-sectional area of ​​the suspension winding.

[0008] Preferably, the permanent magnet rotor topology structure includes main magnetic poles and inter-pole auxiliary magnetic poles, and four of the main magnetic poles and four of the inter-pole auxiliary magnetic poles are provided. The pole arc coefficient α of the main magnetic poles ranges from 0.75 to 0.9, and the pole arc coefficient of the inter-pole auxiliary magnetic poles is 1-α.

[0009] Preferably, the thickness of the main magnetic pole and the interpolar auxiliary magnetic pole is 2.5 to 3 times the air gap length, and the material of the main magnetic pole and the interpolar auxiliary magnetic pole is a permanent magnet steel selected from the group consisting of aluminum-nickel-cobalt permanent magnet alloy, iron-chromium-cobalt permanent magnet alloy, permanent magnet ferrite, rare earth permanent magnet material and the like.

[0010] A method for manufacturing a bearingless brushless DC motor with a 12:4 slot-pole ratio and inter-pole ratio, comprising the following steps:

[0011] S1: Construct the stator structure of the bearingless brushless DC motor with 12:4 slot-pole ratio and inter-pole ratio;

[0012] S11: construct a stator slot structure of a bearingless brushless DC motor with a 12:4 slot-pole ratio and an inter-pole ratio, evenly arrange 12 stator slots on the inner surface of the outer stator structure, and set the distance between adjacent stator slots (i.e., the slot pitch angle width) to 30 degrees; select the stator tooth corresponding to the positive direction of the X-axis as the stator slot No. 1, and number the stator teeth No. 2, No. 3, No. 4, No. 5, No. 6, No. 7, No. 8, No. 9, No. 10, No. 11, and No. 12 in the counterclockwise direction;

[0013] S12: construct the torque winding and suspension winding of the bearingless brushless DC motor with 12:4 slot-pole ratio and inter-pole ratio;

[0014] First, a four-pole torque winding is constructed. A certain number of turns of tooth coils are wound around each stator tooth in the inner layer of the stator slot. The numbers of the tooth coils are consistent with the corresponding stator tooth numbers to form 12 sets of inner tooth coils, namely, No. 1 (C3), No. 2 (B4), No. 3 (A1), No. 4 (C4), No. 5 (B1), No. 6 (A2), No. 7 (C1), No. 8 (B2), No. 9 (A3), No. 10 (C2), No. 11 (B3), and No. 12 (A4). At the same time, the inner tooth coils No. 3 (A1), No. 6 (A2), No. 9 (A3), and No. 10 (C2) are wound around each stator tooth. The No. 1 inner tooth coil (A3) and the No. 12 inner tooth coil (A4) are connected in reverse series in sequence to form the A phase (four-pole) torque winding; the No. 2 inner tooth coil (B4), the No. 5 inner tooth coil (B1), the No. 8 inner tooth coil (B2), and the No. 11 inner tooth coil (B3) are connected in reverse series in sequence to form the B phase (four-pole) torque winding; the No. 7 inner tooth coil (C1), the No. 10 inner tooth coil (C4), the No. 1 inner tooth coil (C3), and the No. 4 inner tooth coil (C4) are connected in reverse series in sequence to form the C phase (four-pole) torque winding;

[0015] Then, a two-pole suspension winding is constructed, and a certain number of turns of tooth coils are wound around each stator tooth on the outer layer of the stator slot. The tooth coils are numbered in accordance with the corresponding stator tooth numbers to form 12 sets of outer tooth coils, namely, No. 1 (w3), No. 2 (v4), No. 3 (u1), No. 4 (w4), No. 5 (v1), No. 6 (u2), No. 7 (w1), No. 8 (v2), No. 9 (u3), No. 10 (w2), No. 11 (v3), and No. 12 (u4). At the same time, the No. 3 outer tooth coil (u1) and the No. 9 outer tooth coil (u3) are connected in reverse series to form the U1 suspension winding, and the No. 6 outer tooth coil (u2) and the No. 12 outer tooth coil (u4) are connected in reverse series to form the U2 suspension winding. The U1 suspension winding The U-phase (two-pole) suspension winding is formed by the U1 suspension winding and the U2 suspension winding; the V1 suspension winding is formed by the No. 5 outer tooth coil (v1) and the No. 11 outer tooth coil (v3) being connected in reverse series, and the V2 suspension winding is formed by the No. 2 outer tooth coil (v4) and the No. 8 outer tooth coil (v2) being connected in reverse series, and the V1 suspension winding and the V2 suspension winding are formed together as the V-phase (two-pole) suspension winding; the W1 suspension winding is formed by the No. 7 outer tooth coil (w1) and the No. 1 outer tooth coil (w3) being connected in reverse series, and the W2 suspension winding is formed by the No. 10 outer tooth coil (w2) and the No. 4 outer tooth coil (w4) being connected in reverse series, and the W1 suspension winding and the W2 suspension winding are formed together as the W-phase (two-pole) suspension winding;

[0016] S2: Construct the permanent magnet rotor topology of the bearingless brushless DC motor with a 12:4 slot-pole ratio and inter-pole-pole ratio;

[0017] S21: Selecting permanent magnet materials for the main magnetic pole and the inter-pole auxiliary magnetic pole to ensure that the performance of the magnetic material of the main permanent magnetic pole is not lower than that of the inter-pole auxiliary magnetic pole;

[0018] S22: manufacture the main magnetic pole permanent magnets and inter-pole auxiliary magnetic pole permanent magnets of the rotor, and combine the inner diameter of the stator structure, the air gap length and other parameters, according to the permanent magnet steel thickness of 2.5 to 3 times the air gap length, and the pole arc coefficient α of each magnet steel within the range of 0.75 to 0.9, manufacture four tile-shaped permanent magnet steels as the main magnetic poles; according to the pole arc coefficient of each magnet steel of "1-α", manufacture four tile-shaped permanent magnet steels as inter-pole auxiliary magnetic poles; take the thickness of the inter-pole auxiliary magnetic poles to be the same as that of the main magnetic poles; if the suspension control performance is mainly based on the preferred α value of about 0.8, if the torque control performance is mainly based on the preferred α value, the specific magnetic steel thickness and the main magnetic pole pole arc coefficient are based on the values ​​calculated after the motor optimization;

[0019] S23: magnetizing the permanent magnets of the main magnetic poles and the inter-pole auxiliary magnetic poles, and radially magnetizing the permanent magnets of the four tile-shaped main magnetic poles to obtain two N-shaped permanent magnets (with magnetic lines pointing to the air gap) and two S-shaped permanent magnets (with magnetic lines pointing to the rotor core);

[0020] Then, taking the geometric center line of the interpolar auxiliary magnetic pole as a reference, determine the quasi-tangential parallel magnetization direction of the interpolar auxiliary permanent magnet along its vertical direction; magnetize the two auxiliary permanent magnets in parallel in the counterclockwise direction, and magnetize the other two permanent magnets in parallel in the clockwise direction, to form two counterclockwise "quasi-tangential parallel magnetization" interpolar auxiliary magnetic poles and two clockwise "quasi-tangential parallel magnetization" interpolar auxiliary magnetic poles;

[0021] S24: The main magnetic poles and the inter-pole auxiliary magnetic poles are arranged in a fixed order. The order of arranging the permanent magnet magnetic poles in a counterclockwise manner along the surface of the permanent magnet rotor topology structure is: N-pole main magnetic pole (magnetic force lines pointing to the air gap), clockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole, S-pole main magnetic pole (magnetic force lines pointing to the rotor core), counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole, N-pole main magnetic pole (magnetic force lines pointing to the air gap), clockwise "quasi-tangential parallel magnetization" "Magnetic" inter-pole auxiliary magnetic poles, (magnetic lines pointing to the rotor core) S-pole main magnetic poles, counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic poles; if the permanent magnet poles are assembled clockwise along the outer surface of the rotor core, the assembly order is opposite to the above order. On the basis of the main magnetic poles, the magnetic field intensity distribution at both ends of the flat top part of the trapezoidal wave air gap magnetic field is improved by the "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic poles, and a "shoulder-shoulder-type trapezoidal wave air gap magnetic field" is obtained;

[0022] S3: Construct the operation control method of the bearingless brushless DC motor with 12:4 slot-pole ratio and inter-pole ratio;

[0023] S31: Set the selection principle of the current working torque winding and the suspension force control winding. The electromagnetic torque of the 12:4 slot-pole ratio inter-pole bearingless brushless DC motor adopts the "three-phase two-through six-state" control method. According to the position range of the rotor, two phases of the three-phase torque winding are respectively connected to the corresponding torque current to generate electromagnetic torque, which is called the "current torque winding"; the other phase torque winding is in an idle state without power, called the "current idle torque winding", and a phase suspension winding with the same teeth as the "current idle torque winding" (and containing two suspension windings with orthogonal axes) in the three-phase suspension winding is taken as the "current suspension winding"; the installation of the rotor angular position sensor and the angular position measurement method are the same as those of ordinary brushless DC motors. Set Figure 1 The position of the rotor in is the initial (zero degree) angular position;

[0024] S32: Setting the radial magnetic suspension force control coordinate system and coordinate transformation relationship, setting the radial magnetic suspension force control coordinate system, wherein: XY is a universal stationary coordinate system, and the rotor radial displacement sensor is installed in the positive direction of its X-axis and Y-axis; U1-U2 is the suspension force control coordinate system when the U-phase suspension winding is working, and its axis is set on the axis of the U1 suspension winding and the U2 suspension winding; V1-V2 is the suspension force control coordinate system when the V-phase suspension winding is working, and W1-W2 is the suspension force control coordinate system when the W-phase suspension winding is working, and its axis setting is similar to U1-U2;

[0025] According to the radial magnetic levitation force control coordinate system setting, the coordinate transformation relationship between each radial magnetic levitation force control coordinate system and the universal coordinate system is obtained as follows:

[0026]

[0027] Among them They are radial magnetic suspension force given signals along the X-axis and Y-axis directions, and their values ​​are output by the closed-loop control system regulator; They are the radial magnetic suspension force given signals along the U1 axis and the U2 axis respectively; They are the radial magnetic suspension force given signals along the V1 axis and V2 axis respectively; They are the radial magnetic suspension force given signals along the W1 axis and the W2 axis respectively; and and and The value of is obtained in real time according to the coordinate transformation relationship (1) between the radial magnetic suspension force control coordinate system corresponding to the "current suspension winding" and the XY universal stationary coordinate system;

[0028] S33: Select the "current torque winding" and the "current suspension winding" according to the angular position range in which the rotor is currently located; according to the torque given signal output by the external speed control system, a torque current of corresponding magnitude and polarity is supplied to the "current torque winding" through the corresponding torque inverter; according to the radial magnetic suspension force given signal output by the external radial displacement control system, a suspension current of corresponding magnitude and polarity is supplied to the "current suspension winding" through the corresponding suspension inverter.

[0029] Therefore, compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The bearingless brushless DC motor of the present invention adopts a permanent magnet rotor topology structure of "radially magnetized main magnetic poles + quasi-tangentially parallel magnetized auxiliary magnetic poles", which has a simpler manufacturing process than the Halbach permanent magnet structure and radial plus circumferential combined magnetization permanent magnet structure of ordinary brushless DC motors.

[0031] (2) The design and manufacture of the electromagnetic torque and radial magnetic suspension force closed-loop control system using a 12:4 slot-pole ratio and a dual-winding type in the present invention can refer to the common structure BL-BLDC motor, and the difficulty and complexity of the system implementation are not high.

[0032] (3) The present invention provides a 12:4 slot-pole ratio inter-pole bearingless brushless DC motor structure solution, which can effectively improve the power density of the motor and reduce torque pulsation while maintaining good radial magnetic suspension control characteristics, thereby obtaining good magnetic suspension operation control performance.

[0033] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the overall structure of an embodiment of a bearingless brushless DC motor in the present invention;

[0035] Figure 2 A schematic diagram of the stator tooth slot structure of a bearingless brushless DC motor embodiment of the present invention;

[0036] Figure 3 The permanent magnet rotor topology structure and magnetization method of the bearingless brushless DC motor embodiment of the present invention;

[0037] Figure 4 A schematic diagram of a universal coordinate system of a radial magnetic suspension force control coordinate system of an embodiment of a bearingless brushless DC motor in the present invention;

[0038] Figure 5 A schematic diagram of the U1-U2 coordinate system of the radial magnetic suspension force control coordinate system of the bearingless brushless DC motor embodiment of the present invention;

[0039] Figure 6 A schematic diagram of a V1-V2 coordinate system of a radial magnetic suspension force control coordinate system of an embodiment of a bearingless brushless DC motor in the present invention;

[0040] Figure 7 A schematic diagram of the W1-W2 coordinate system of the radial magnetic suspension force control coordinate system of the bearingless brushless DC motor embodiment of the present invention;

[0041] Reference numerals:

[0042] 11. Stator structure; 12. Stator slot; 121. Fillet; 13. Torque winding; 14. Suspension winding; 15. Permanent magnet rotor topology; 16. Interpolar auxiliary magnetic poles; 17. Main magnetic poles; 18. Pole magnetization direction. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0044] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0045] Example

[0046] See also Figure 1-Figure 7 The present invention provides a 12:4 slot-pole ratio inter-pole bearingless brushless DC motor and a manufacturing method thereof, wherein the device comprises a stator structure 11, a torque winding 13, a suspension winding 14 and a permanent magnet rotor topology structure 15, wherein a plurality of stator slots 12 are evenly arranged on the inner surface of the stator structure 11, the torque winding 13 and the suspension winding 14 are respectively wound on the stator slots 12, and the permanent magnet rotor topology structure 15 is arranged in the stator structure 11.

[0047] Figure 1The overall structure diagram of the embodiment of the bearingless brushless DC motor is shown in FIG. The inner layer of the stator slot 12 is a three-phase torque winding 13 (A, B, C), each phase is composed of windings on four stator slots 12 separated by 3 tooth pitches connected in series, and the three-phase torque windings 13 are 120 degrees electrical angle (60 degrees mechanical angle) apart in sequence; the outer layer of the stator slot 12 is a three-phase suspension winding 14 (U, V, W); each phase suspension winding 14 is composed of two suspension windings 14 with mutually perpendicular axes (such as the U-phase suspension winding is composed of the U1 suspension winding and the U2 suspension winding), and the three-phase suspension windings 14 are 120 degrees electrical angle (120 degrees mechanical angle) apart in sequence; each suspension winding 14 is composed of two spatially symmetrical suspension coils connected in reverse series. Its permanent magnet rotor topology structure 15 is an inter-pole permanent magnet inner rotor structure; the inter-pole is in the transition area between the N pole and the S pole.

[0048] Figure 2 The figure is a schematic diagram of the stator slot structure of the embodiment of the bearingless brushless DC motor in the present invention. In order to improve the fullness of the stator slot 12 and minimize the damage to the insulation in the slot, the stator slot 12 adopts a rounded flat bottom slot structure. Among them, Bs0 is the slot width, Hs0 is the slot width, Hs1 is the slot shoulder width, Hs2 is the stator slot depth, Bs1 is the width of the stator slot body close to the stator slot shoulder, Bs2 is the width of the stator slot bottom, and Rs is the radius of the fillet 121 of the stator slot bottom corner.

[0049] Figure 3 The permanent magnet rotor topology structure and magnetization method of the bearingless brushless DC motor embodiment of the present invention, wherein the permanent magnet rotor topology structure 15 includes a main magnetic pole 17 and an interpolar auxiliary magnetic pole 16, and four main magnetic poles 17 and four interpolar auxiliary magnetic poles 16 are provided respectively, and the pole arc coefficient α of the main magnetic pole 17 ranges from 0.75 to 0.9, and the pole arc coefficient of the interpolar auxiliary magnetic pole 16 is 1-α. The thickness of the main magnetic pole 7 and the interpolar auxiliary magnetic pole 16 is 2.5 to 3 times the air gap length, and the material of the main magnetic pole 17 and the interpolar auxiliary magnetic pole 16 is a permanent magnetic steel selected from materials such as aluminum nickel cobalt permanent magnetic alloy, iron chromium cobalt permanent magnetic alloy, permanent magnetic ferrite, and rare earth permanent magnetic material. The arrow direction in the figure is the magnetization direction 18 of the main magnetic pole 17 and the interpolar auxiliary magnetic pole 16. First, the four tile-shaped main magnetic pole 17 permanent magnets are radially magnetized to obtain two N-shaped permanent magnets (magnetic lines pointing to the air gap) and two S-shaped permanent magnets (magnetic lines pointing to the rotor core);

[0050] Then, taking the geometric center line of the interpolar auxiliary magnetic pole 16 as a reference, determine the quasi-tangential parallel magnetization direction of the interpolar auxiliary permanent magnet along its vertical direction; magnetize the two auxiliary permanent magnets in parallel in the counterclockwise direction, and magnetize the other two permanent magnets in parallel in the clockwise direction, to form two counterclockwise "quasi-tangential parallel magnetization" interpolar auxiliary permanent magnetic poles and two clockwise "quasi-tangential parallel magnetization" interpolar auxiliary permanent magnetic poles;

[0051] Finally, the main magnetic poles 17 and the inter-pole auxiliary magnetic poles 16 are arranged in a fixed order. The order of arranging the permanent magnet poles in a counterclockwise manner along the outer surface of the rotor core is: N-pole main magnetic pole (magnetic force lines pointing to the air gap), clockwise "quasi-tangential parallel magnetization" inter-pole auxiliary permanent magnetic pole, S-pole main magnetic pole (magnetic force lines pointing to the rotor core), counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary permanent magnetic pole, N-pole main magnetic pole (magnetic force lines pointing to the air gap), clockwise "quasi-tangential parallel magnetization" inter-pole auxiliary permanent magnetic pole, S-pole main magnetic pole (magnetic force lines pointing to the rotor core), counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary permanent magnetic pole; if the permanent magnet poles are assembled in a clockwise manner along the outer surface of the rotor core, the assembly order is opposite to the above order. On the basis of the main magnetic pole 17, the magnetic field intensity distribution at both end areas of the flat top part of the trapezoidal wave air gap magnetic field is improved through the "quasi-tangential parallel magnetization" interpolar auxiliary magnetic pole 16 to obtain a "shoulder-type trapezoidal wave air gap magnetic field".

[0052] like Figure 4-Figure 7 The radial magnetic suspension force control coordinate system of the bearingless brushless DC motor embodiment of the present invention is shown. Figure 4 is a universal coordinate system, Figure 5 is the U1-U2 coordinate system, Figure 6 is the V1-V2 coordinate system, Figure 7 It is the W1-W2 coordinate system. Among them: XY is the universal stationary coordinate system, and the rotor radial displacement sensor is installed in the positive direction of its X-axis and Y-axis; U1-U2 is the suspension force control coordinate system when the U-phase suspension winding is working, and its axis is set on the axis of the U1 suspension winding and the U2 suspension winding; V1-V2 is the suspension force control coordinate system when the V-phase suspension winding is working, and W1-W2 is the suspension force control coordinate system when the W-phase suspension winding is working, and its axis setting is similar to U1-U2. According to the radial magnetic suspension force control coordinate system setting in the figure, the coordinate transformation relationship between each radial magnetic suspension force control coordinate system and the universal coordinate system is obtained as follows:

[0053]

[0054] Among them They are radial magnetic suspension force given signals along the X-axis and Y-axis directions, and their values ​​are output by the closed-loop control system regulator; They are the radial magnetic suspension force given signals along the U1 axis and the U2 axis respectively; They are the radial magnetic suspension force given signals along the V1 axis and V2 axis respectively; They are the radial magnetic suspension force given signals along the W1 axis and the W2 axis respectively; and and and The value of is obtained in real time according to the coordinate transformation relationship (1) between the radial magnetic suspension force control coordinate system corresponding to the "current suspension winding" and the XY universal stationary coordinate system.

[0055] According to the technical solution of the present invention, the relationship between the rotor position when generating counterclockwise driving torque and radial magnetic suspension force along the positive direction of the X-axis and the current working winding and its current polarity is as follows:

[0056]

[0057] A method for manufacturing a bearingless brushless DC motor with a 12:4 slot-pole ratio and inter-pole ratio, comprising the following steps:

[0058] S1: Construct the stator structure of the bearingless brushless DC motor with 12:4 slot-pole ratio and inter-pole ratio;

[0059] S11: construct a stator slot structure of a bearingless brushless DC motor with a 12:4 slot-pole ratio and an inter-pole ratio, evenly arrange 12 stator slots on the inner surface of the outer stator structure, and set the distance between adjacent stator slots (i.e., the slot pitch angle width) to 30 degrees; select the stator tooth corresponding to the positive direction of the X-axis as the stator slot No. 1, and number the stator teeth No. 2, No. 3, No. 4, No. 5, No. 6, No. 7, No. 8, No. 9, No. 10, No. 11, and No. 12 in the counterclockwise direction;

[0060] S12: Construct the torque winding and suspension winding of the 12:4 slot-pole ratio inter-pole bearingless brushless DC motor.

[0061] First, a four-pole torque winding is constructed. A certain number of turns of tooth coils are wound around each stator tooth in the inner layer of the stator slot. The numbers of the tooth coils are consistent with the corresponding stator tooth numbers to form 12 sets of inner tooth coils, namely, No. 1 (C3), No. 2 (B4), No. 3 (A1), No. 4 (C4), No. 5 (B1), No. 6 (A2), No. 7 (C1), No. 8 (B2), No. 9 (A3), No. 10 (C2), No. 11 (B3), and No. 12 (A4). At the same time, the inner tooth coils No. 3 (A1), No. 6 (A2), No. 9 (A3), and No. 10 (C2) are wound around each stator tooth. The No. 1 inner tooth coil (A3) and the No. 12 inner tooth coil (A4) are connected in reverse series in sequence to form the A phase (four-pole) torque winding; the No. 2 inner tooth coil (B4), the No. 5 inner tooth coil (B1), the No. 8 inner tooth coil (B2), and the No. 11 inner tooth coil (B3) are connected in reverse series in sequence to form the B phase (four-pole) torque winding; the No. 7 inner tooth coil (C1), the No. 10 inner tooth coil (C4), the No. 1 inner tooth coil (C3), and the No. 4 inner tooth coil (C4) are connected in reverse series in sequence to form the C phase (four-pole) torque winding;

[0062] Then, a two-pole suspension winding is constructed, and a certain number of turns of tooth coils are wound around each stator tooth on the outer layer of the stator slot. The tooth coils are numbered in accordance with the corresponding stator tooth numbers to form 12 sets of outer tooth coils, namely, No. 1 (w3), No. 2 (v4), No. 3 (u1), No. 4 (w4), No. 5 (v1), No. 6 (u2), No. 7 (w1), No. 8 (v2), No. 9 (u3), No. 10 (w2), No. 11 (v3), and No. 12 (u4). At the same time, the No. 3 outer tooth coil (u1) and the No. 9 outer tooth coil (u3) are connected in reverse series to form the U1 suspension winding, and the No. 6 outer tooth coil (u2) and the No. 12 outer tooth coil (u4) are connected in reverse series to form the U2 suspension winding. The U1 suspension winding The U-phase (two-pole) suspension winding is formed by the U1 suspension winding and the U2 suspension winding; the V1 suspension winding is formed by the No. 5 outer tooth coil (v1) and the No. 11 outer tooth coil (v3) being connected in reverse series, and the V2 suspension winding is formed by the No. 2 outer tooth coil (v4) and the No. 8 outer tooth coil (v2) being connected in reverse series, and the V1 suspension winding and the V2 suspension winding are formed together as the V-phase (two-pole) suspension winding; the W1 suspension winding is formed by the No. 7 outer tooth coil (w1) and the No. 1 outer tooth coil (w3) being connected in reverse series, and the W2 suspension winding is formed by the No. 10 outer tooth coil (w2) and the No. 4 outer tooth coil (w4) being connected in reverse series, and the W1 suspension winding and the W2 suspension winding are formed together as the W-phase (two-pole) suspension winding;

[0063] S2: Construct the permanent magnet rotor topology of the bearingless brushless DC motor with a 12:4 slot-pole ratio and inter-pole-pole ratio;

[0064] S21: Selecting permanent magnet materials for the main magnetic pole and the inter-pole auxiliary magnetic pole to ensure that the performance of the magnetic material of the main permanent magnetic pole is not lower than that of the inter-pole auxiliary magnetic pole;

[0065] S22: manufacture the main magnetic pole permanent magnets and inter-pole auxiliary magnetic pole permanent magnets of the rotor, and combine the inner diameter of the stator structure, the air gap length and other parameters, according to the permanent magnet steel thickness of 2.5 to 3 times the air gap length, and the pole arc coefficient α of each magnet steel within the range of 0.75 to 0.9, manufacture four tile-shaped permanent magnet steels as the main magnetic poles; according to the pole arc coefficient of each magnet steel of "1-α", manufacture four tile-shaped permanent magnet steels as inter-pole auxiliary magnetic poles; take the thickness of the inter-pole auxiliary magnetic poles to be the same as that of the main magnetic poles; if the suspension control performance is mainly based on the preferred α value of about 0.8, if the torque control performance is mainly based on the preferred α value, the specific magnetic steel thickness and the main magnetic pole pole arc coefficient are based on the values ​​calculated after the motor optimization;

[0066] S23: magnetizing the permanent magnets of the main magnetic poles and the inter-pole auxiliary magnetic poles, and radially magnetizing the permanent magnets of the four tile-shaped main magnetic poles to obtain two N-shaped permanent magnets (with magnetic lines pointing to the air gap) and two S-shaped permanent magnets (with magnetic lines pointing to the rotor core);

[0067] Then, taking the geometric center line of the interpolar auxiliary magnetic pole as a reference, determine the quasi-tangential parallel magnetization direction of the interpolar auxiliary permanent magnet along its vertical direction; magnetize the two auxiliary permanent magnets in parallel in the counterclockwise direction, and magnetize the other two permanent magnets in parallel in the clockwise direction, to form two counterclockwise "quasi-tangential parallel magnetization" interpolar auxiliary magnetic poles and two clockwise "quasi-tangential parallel magnetization" interpolar auxiliary magnetic poles;

[0068] S24: The main magnetic poles and the inter-pole auxiliary magnetic poles are arranged in a fixed order. The order of arranging the permanent magnet magnetic poles in a counterclockwise manner along the surface of the permanent magnet rotor topology structure is: N-pole main magnetic pole (magnetic force lines pointing to the air gap), clockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole, S-pole main magnetic pole (magnetic force lines pointing to the rotor core), counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole, N-pole main magnetic pole (magnetic force lines pointing to the air gap), clockwise "quasi-tangential parallel magnetization" "Magnetic" inter-pole auxiliary magnetic poles, (magnetic lines pointing to the rotor core) S-pole main magnetic poles, counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic poles; if the permanent magnet poles are assembled clockwise along the outer surface of the rotor core, the assembly order is opposite to the above order. On the basis of the main magnetic poles, the magnetic field intensity distribution at both ends of the flat top part of the trapezoidal wave air gap magnetic field is improved by the "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic poles, and a "shoulder-shoulder-type trapezoidal wave air gap magnetic field" is obtained;

[0069] S3: Construct an operation control method for a 12:4 slot-pole ratio inter-pole bearingless brushless DC motor;

[0070] S31: Set the selection principle of the current working torque winding and the suspension force control winding. The electromagnetic torque of the 12:4 slot-pole ratio inter-pole bearingless brushless DC motor adopts the "three-phase two-through six-state" control method. According to the position range of the rotor, two phases of the three-phase torque winding are respectively connected to the corresponding torque current to generate electromagnetic torque, which is called the "current torque winding"; the other phase torque winding is in an idle state without power, called the "current idle torque winding", and a phase suspension winding with the same teeth as the "current idle torque winding" (and containing two suspension windings with orthogonal axes) in the three-phase suspension winding is taken as the "current suspension winding"; the installation of the rotor angular position sensor and the angular position measurement method are the same as those of ordinary brushless DC motors. Set Figure 1 The position of the rotor in is the initial (zero degree) angular position;

[0071] S32: Setting the radial magnetic suspension force control coordinate system and coordinate transformation relationship, setting the radial magnetic suspension force control coordinate system, wherein: XY is a universal stationary coordinate system, and the rotor radial displacement sensor is installed in the positive direction of its X-axis and Y-axis; U1-U2 is the suspension force control coordinate system when the U-phase suspension winding is working, and its axis is set on the axis of the U1 suspension winding and the U2 suspension winding; V1-V2 is the suspension force control coordinate system when the V-phase suspension winding is working, and W1-W2 is the suspension force control coordinate system when the W-phase suspension winding is working, and its axis setting is similar to U1-U2;

[0072] According to the radial magnetic levitation force control coordinate system setting, the coordinate transformation relationship between each radial magnetic levitation force control coordinate system and the universal coordinate system is obtained as follows:

[0073]

[0074] Among them They are radial magnetic suspension force given signals along the X-axis and Y-axis directions, and their values ​​are output by the closed-loop control system regulator; They are the radial magnetic suspension force given signals along the U1 axis and the U2 axis respectively; They are the radial magnetic suspension force given signals along the V1 axis and V2 axis respectively; They are the radial magnetic suspension force given signals along the W1 axis and the W2 axis respectively; and and and The value of is obtained in real time according to the coordinate transformation relationship (1) between the radial magnetic suspension force control coordinate system corresponding to the "current suspension winding" and the XY universal stationary coordinate system;

[0075] S33: Select the "current torque winding" and the "current suspension winding" according to the angular position range in which the rotor is currently located; according to the torque given signal output by the external speed control system, a torque current of corresponding magnitude and polarity is supplied to the "current torque winding" through the corresponding torque inverter; according to the radial magnetic suspension force given signal output by the external radial displacement control system, a suspension current of corresponding magnitude and polarity is supplied to the "current suspension winding" through the corresponding suspension inverter.

[0076] Therefore, the present invention adopts a 12:4 slot-pole ratio inter-pole bearingless brushless DC motor and a manufacturing method of the above structure, and utilizes the high precision and fast response characteristics of piezoelectric drive to perform underwater vector commutation, thereby improving the accuracy of vector commutation and shortening the response time. At the same time, the thruster adopts a combination of a jet unit and a piezoelectric vector commutation mechanism, so that the overall structure has a low production cost, is easy to miniaturize, modularize, and is easy to integrate into other navigation equipment.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A 12:4 slot-pole ratio inter-pole bearingless brushless DC motor, characterized in that: It comprises a stator structure, a torque winding, a suspension winding and a permanent magnet rotor topology structure. The inner surface of the stator structure is evenly provided with a plurality of stator slots. The torque winding and the suspension winding are respectively wound in the stator slots. The permanent magnet rotor topology structure is arranged in the stator structure.

2. A 12:4 slot-pole ratio interpole-pole bearingless brushless DC motor according to claim 1, characterized in that: The bottom of the stator slot adopts a rounded flat-bottom slot structure, and the upper and lower parts of the slot body between two adjacent stator slots are equal in width.

3. A 12:4 slot-pole ratio interpole-pole bearingless brushless DC motor according to claim 2, characterized in that: The coil cross-sectional area of ​​the torque winding accounts for 60% to 70% of the stator slot cross-sectional area, and the stator slot cross-sectional area is equal to the sum of the coil cross-sectional area of ​​the torque winding and the coil cross-sectional area of ​​the suspension winding.

4. A 12:4 slot-pole ratio interpole-pole bearingless brushless DC motor according to claim 1, characterized in that: The permanent magnet rotor topology structure includes main magnetic poles and inter-pole auxiliary magnetic poles. Four of the main magnetic poles and four of the inter-pole auxiliary magnetic poles are provided. The pole arc coefficient α of the main magnetic poles ranges from 0.75 to 0.9, and the pole arc coefficient of the inter-pole auxiliary magnetic poles is 1-α.

5. A 12:4 slot-pole ratio interpole-pole bearingless brushless DC motor according to claim 4, characterized in that: The thickness of the main magnetic pole and the inter-pole auxiliary magnetic pole is 2.5 to 3 times the air gap length, and the material of the main magnetic pole and the inter-pole auxiliary magnetic pole is a permanent magnetic steel selected from the group consisting of aluminum-nickel-cobalt permanent magnetic alloy, iron-chromium-cobalt permanent magnetic alloy, permanent magnetic ferrite, rare earth permanent magnetic material and the like.

6. A method for manufacturing a 12:4 slot-pole ratio interpole-pole bearingless brushless DC motor, applied to a 12:4 slot-pole ratio interpole-pole bearingless brushless DC motor according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Construct the stator structure of the bearingless brushless DC motor with 12:4 slot-pole ratio and inter-pole ratio; S11: construct a stator slot structure of a bearingless brushless DC motor with a 12:4 slot-pole ratio and inter-pole ratio, evenly arrange 12 stator slots on the inner surface of the outer stator structure, and set the distance between adjacent stator slots to 30 degrees; select the stator tooth corresponding to the positive direction of the X-axis as the first stator tooth, and number them as No. 2, No. 3, No. 4, No. 5, No. 6, No. 7, No. 8, No. 9, No. 10, No. 11, and No. 12 stator teeth in a counterclockwise direction; S12: Construct the torque winding and suspension winding of the 12:4 slot-pole ratio inter-pole bearingless brushless DC motor. First, construct a four-pole torque winding, wind a certain number of turns of tooth coils around each stator tooth in the inner layer of the stator slot, and make the number of the tooth coils consistent with the corresponding stator tooth number, forming 12 sets of inner layer tooth coils, No. 1 C3, No. 2 B4, No. 3 A1, No. 4 C4, No. 5 B1, No. 6 A2, No. 7 C1, No. 8 B2, No. 9 A3, No. 10 C2, No. 11 B3, No. 12 A4, and at the same time, No. 3 inner layer tooth coil A1, No. 6 inner layer tooth coil A2, No. 9 inner layer tooth coil A3, No. 10 C2, No. 11 B3, No. 12 A4. The inner tooth coil A3 and the 12th inner tooth coil A4 are connected in reverse series in sequence to form the A-phase four-pole torque winding; the 2nd inner tooth coil B4, the 5th inner tooth coil B1, the 8th inner tooth coil B2, and the 11th inner tooth coil B3 are connected in reverse series in sequence to form the B-phase four-pole torque winding; the 7th inner tooth coil C1, the 10th inner tooth coil C4, the 1st inner tooth coil C3, and the 4th inner tooth coil C4 are connected in reverse series in sequence to form the C-phase four-pole torque winding; Then, a two-pole suspension winding is constructed, and a tooth coil with a certain number of turns is wound around each stator tooth in the outer layer of the stator slot. The number of the tooth coil is consistent with the number of the corresponding stator tooth, forming 12 sets of outer tooth coils No. 1 w3, No. 2 v4, No. 3 u1, No. 4 w4, No. 5 v1, No. 6 u2, No. 7 w1, No. 8 v2, No. 9 u3, No. 10 w2, No. 11 v3, and No. 12 u4. At the same time, the No. 3 outer tooth coil u1 and the No. 9 outer tooth coil u3 are connected in reverse series to form the U1 suspension winding, and the No. 6 outer tooth coil u2 and the No. 12 outer tooth coil u4 are connected in reverse series to form the U2 suspension winding. The U1 suspension winding and the U2 suspension winding are connected in reverse series. The floating windings together constitute the U-phase two-pole suspension winding; the No. 5 outer tooth coil v1 and the No. 11 outer tooth coil v3 are connected in reverse series to form the V1 suspension winding, the No. 2 outer tooth coil v4 and the No. 8 outer tooth coil v2 are connected in reverse series to form the V2 suspension winding, and the V1 suspension winding and the V2 suspension winding together constitute the V-phase two-pole suspension winding; the No. 7 outer tooth coil w1 and the No. 1 outer tooth coil w3 are connected in reverse series to form the W1 suspension winding, the No. 10 outer tooth coil w2 and the No. 4 outer tooth coil w4 are connected in reverse series to form the W2 suspension winding, and the W1 suspension winding and the W2 suspension winding together constitute the W-phase two-pole suspension winding; S2: Construct the permanent magnet rotor topology of the bearingless brushless DC motor with a 12:4 slot-pole ratio and inter-pole-pole ratio; S21: Selecting permanent magnet materials for the main magnetic pole and the inter-pole auxiliary magnetic pole to ensure that the performance of the magnetic material of the main permanent magnetic pole is not lower than that of the inter-pole auxiliary magnetic pole; S22: manufacturing the main magnetic pole permanent magnets and inter-pole auxiliary magnetic pole permanent magnets of the rotor, and combining the inner diameter of the stator structure, the air gap length and other parameters, with the thickness of the permanent magnetic steel being 2.5 to 3 times the air gap length, and the pole arc coefficient α of each magnetic steel being within the range of 0.75 to 0.9, manufacturing four tile-shaped permanent magnetic steels as the main magnetic poles; Four tile-shaped permanent magnets are made as inter-pole auxiliary magnetic poles according to the pole arc coefficient of each magnetic steel being "1-α". The thickness of the inter-pole auxiliary magnetic poles is the same as that of the main magnetic poles. If the suspension control performance is the main consideration, the α value is preferably around 0.8, and if the torque control performance is the main consideration, a larger α value is preferred. The specific magnetic steel thickness and the pole arc coefficient of the main magnetic pole are calculated according to the values ​​after the motor optimization. S23: magnetizing the permanent magnets of the main magnetic poles and the inter-pole auxiliary magnetic poles, and radially magnetizing the permanent magnets of the four tile-shaped main magnetic poles to obtain two N-shaped permanent magnets with magnetic force lines pointing to the air gap and two S-shaped permanent magnets with magnetic force lines pointing to the rotor core; Then, taking the geometric center line of the interpolar auxiliary magnetic pole as a reference, determine the quasi-tangential parallel magnetization direction of the interpolar auxiliary permanent magnet along its vertical direction; magnetize the two auxiliary permanent magnets in parallel in the counterclockwise direction, and magnetize the other two permanent magnets in parallel in the clockwise direction, so as to form two counterclockwise "quasi-tangential parallel magnetization" interpolar auxiliary magnetic poles and two clockwise "quasi-tangential parallel magnetization" interpolar auxiliary magnetic poles; S24: the main magnetic poles and the inter-pole auxiliary magnetic poles are arranged in a fixed order, and the order of arranging the permanent magnet magnetic poles in a counterclockwise manner along the surface of the permanent magnet rotor topological structure is: the magnetic force line points to the N-pole main magnetic pole of the air gap, the clockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole, the magnetic force line points to the S-pole main magnetic pole of the rotor core, the counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole, the magnetic force line points to the N-pole main magnetic pole of the air gap, the clockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole, the magnetic force line points to the S-pole main magnetic pole of the rotor core, and the counterclockwise "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic pole; if the permanent magnet magnetic poles are assembled in a clockwise manner along the outer surface of the rotor core, the assembly order is opposite to the above order. On the basis of the main magnetic poles, the magnetic field intensity distribution of the two end areas of the flat top part of the trapezoidal wave air gap magnetic field is improved by the "quasi-tangential parallel magnetization" inter-pole auxiliary magnetic poles to obtain the "shoulder-shoulder-type trapezoidal wave air gap magnetic field"; S3: Construct an operation control method for a 12:4 slot-pole ratio inter-pole bearingless brushless DC motor; S31: setting the selection principle of the current working torque winding and the suspension force control winding. The electromagnetic torque of the 12:4 slot-pole ratio inter-pole bearingless brushless DC motor adopts the "three-phase two-through six-state" control mode. According to the position interval of the rotor, two phases of the three-phase torque winding are respectively connected with the corresponding torque current to generate electromagnetic torque, which is called the "current torque winding"; another phase torque winding is in an idle state without power, which is called the "current idle torque winding". A phase suspension winding with the same teeth as the "current idle torque winding" and containing two suspension windings with orthogonal axes in the three-phase suspension winding is taken as the "current suspension winding"; the installation of the rotor angular position sensor and the angular position measurement method are the same as those of the ordinary brushless DC motor. The rotor position in Figure 1 is set as the initial zero-degree angular position; S32: Setting the radial magnetic suspension force control coordinate system and coordinate transformation relationship, setting the radial magnetic suspension force control coordinate system, wherein: XY is a universal stationary coordinate system, and the rotor radial displacement sensor is installed in the positive direction of its X-axis and Y-axis; U1-U2 is the suspension force control coordinate system when the U-phase suspension winding is working, and its axis is set on the axis of the U1 suspension winding and the U2 suspension winding; V1-V2 is the suspension force control coordinate system when the V-phase suspension winding is working, and W1-W2 is the suspension force control coordinate system when the W-phase suspension winding is working, and its axis setting is similar to U1-U2; According to the radial magnetic levitation force control coordinate system setting, the coordinate transformation relationship between each radial magnetic levitation force control coordinate system and the universal coordinate system is obtained as follows: Among them They are radial magnetic suspension force given signals along the X-axis and Y-axis directions, and their values ​​are output by the closed-loop control system regulator; They are the radial magnetic suspension force given signals along the U1 axis and the U2 axis respectively; They are the radial magnetic suspension force given signals along the V1 axis and V2 axis respectively; They are the radial magnetic suspension force given signals along the W1 axis and the W2 axis respectively; and and and The value of is obtained in real time according to the coordinate transformation relationship (1) between the radial magnetic suspension force control coordinate system corresponding to the "current suspension winding" and the XY universal stationary coordinate system; S33: selecting the "current torque winding" and the "current suspension winding" according to the angular position interval in which the rotor is currently located; supplying a torque current of corresponding magnitude and polarity to the "current torque winding" through the corresponding torque inverter according to the torque given signal output by the external speed control system; supplying a suspension current of corresponding magnitude and polarity to the "current suspension winding" through the corresponding suspension inverter according to the radial magnetic suspension force given signal output by the external radial displacement control system.

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