Design method of bearingless permanent magnet synchronous motor with parallel magnetized combined poles and inclined connection

Abstract

The present invention discloses a design method for a bearingless permanent magnet synchronous motor with parallel magnetization and combined magnetic poles connected by an inclined plane, which belongs to the technical field of novel special AC motor optimization design. The stator teeth / slots of the BL-PMSM are evenly arranged along the circumference of the stator, and the stator teeth / slots are designed with pear-shaped slots and parallel teeth; then a four-pole torque winding and a two-pole suspension winding are constructed; finally, a symmetrical arc-bottom trapezoidal main magnetic pole and an asymmetrical trapezoidal auxiliary magnetic pole are constructed using high remanence material and low remanence material respectively, the main and auxiliary magnetic poles are seamlessly connected by an inclined plane, and the pole arc coefficient occupied by the width of the inclined plane connection area is used as one of the structural parameter variables to construct an integrated parallel magnetization integral sector ring magnetic pole structure, and then the four-pole permanent magnet inner rotor structure of the BL-PMSM is constructed in an alternating order of N and S polarity. The inclined plane connection combined magnetic pole structure of the present invention can effectively avoid local fusion of the air gap magnetic density waveform, reduce the pulsation rate of torque and suspension force, and is suitable for the field of magnetic suspension rotation drive technology of high-speed permanent magnet synchronous motors.

Description

Technical Field

[0001] The present invention relates to the technical field of AC motor optimization design, in particular to a design method for a bearingless permanent magnet synchronous motor with parallel magnetized combined magnetic poles and inclined surfaces. Background Art

[0002] The bearingless permanent magnet synchronous motor (BL-PMSM) is a novel magnetic levitation motor constructed by nesting an additional suspension winding within the stator core of a conventional permanent magnet synchronous motor. This suspension winding, with a pole pair offset from the torque winding (motor winding), is located one pole apart. By applying the same-frequency excitation current to both windings, a stable electromagnetic torque is generated while also generating a stable and controllable radial magnetic levitation force, enabling bearingless magnetic levitation rotation. This motor has broad application prospects in high-tech fields such as flywheel energy storage, sealed pumps, life sciences, and aerospace.

[0003] Literature and search results show that the electromagnetic performance of BL-PMSM driven by sinusoidal current is closely related to the sinusoidality of the air gap flux density; the development of BL-PMSM started late, and its current optimized pole optimization structure mainly includes Halbach permanent magnet array, unequal amplitude modulated pole structure and combined pole; Chinese scholars applied the combined poles in traditional permanent magnet synchronous motors to BL-PMSM and conducted a series of studies, which can reduce torque pulsation and suspension force pulsation while ensuring the output performance of the motor, but the integrated radial magnetization method of the combined poles adopted is not conducive to significantly improving the sinusoidality of the BL-PMSM air gap flux density.

[0004] In order to improve the electromagnetic torque and radial magnetic levitation force characteristics of BL-PMSM, the present invention will address the defects existing in the domestic existing technical research and propose a new structure of "bearingless permanent magnet synchronous motor with inclined plane connection, parallel magnetization and combined magnetic poles" which can effectively improve the sinusoidality of air gap magnetic density and reduce torque pulsation and levitation force pulsation. Summary of the Invention

[0005] The purpose of the present invention is to provide a design method for a bearingless permanent magnet synchronous motor with parallel magnetized combined poles connected by an inclined surface, and proposes a new structure of parallel magnetized combined poles connected by an inclined surface. In order to improve the sinusoidality of its air gap magnetic field, an integrated parallel magnetization method is adopted; the middle main pole of the combined pole adopts a symmetrical arc bottom trapezoidal structure, and the auxiliary poles symmetrically distributed on both sides adopt an asymmetrical trapezoidal structure, and after seamlessly connecting with the middle main pole by an inclined surface, they together form a fan-ring permanent magnet structure. The junction area between the main pole and the auxiliary pole of the same combined pole occupies a certain width (which can be represented by the pole arc coefficient of the inclined surface connection area), which will make the synthetic residual magnetic flux density change continuously in the junction area, thereby effectively avoiding the step-like mutation of the air gap magnetic field, thereby further improving the degree of consistency between the rising / falling area in the air gap magnetic field waveform and the sine waveform.

[0006] To achieve the above object, the present invention provides a design method for a bearingless permanent magnet synchronous motor with parallel magnetized combined poles and an inclined connection, comprising the following steps:

[0007] S1. Construct stator teeth / slots of the BL-PMSM with parallel magnetized combined poles and connected by inclined planes. Evenly arrange the stator teeth / slots of the BL-PMSM along the stator circumference, and arrange 24 stator teeth / slots in a pear-shaped stator slot structure and a parallel stator tooth structure.

[0008] S2. Construct the stator winding of the BL-PMSM with parallel magnetized combined poles and inclined planes. Place two sets of conductors in each stator slot designed in step S1 to form a torque winding conductor and a suspension winding conductor. After numbering each torque winding conductor and suspension winding conductor, construct a four-pole stator torque winding in the inner layer of the slot and a two-pole stator suspension winding in the outer layer of the slot.

[0009] S3. Construct the overall structure of the inclined-surface connection combined magnetic poles of the BL-PMSM inner rotor, use high remanence material and low remanence material to construct symmetrical arc-bottom trapezoidal main magnetic poles and asymmetrical trapezoidal auxiliary magnetic poles respectively, connect the main and auxiliary magnetic poles seamlessly with an inclined surface, and use the pole arc coefficient occupied by the width of the connecting inclined surface area as one of the structural parameter variables to construct an integrated parallel magnetized inclined-surface connection combined magnetic pole overall fan ring structure, and then construct the permanent magnet four-pole inner rotor structure of the BL-PMSM in an alternating order of N and S polarity.

[0010] Preferably, in step S1, the steps of constructing the stator teeth / slots of the BL-PMSM with parallel magnetized combined magnetic poles connected by inclined planes are specifically as follows:

[0011] S11, adopting an outer stator and inner rotor structure, 24 stator teeth / slots are evenly arranged along the inner surface of the stator core;

[0012] S12. Number the stator slots with a slot pitch of 15° from 1 to 24 in a counterclockwise direction.

[0013] Preferably, in step S12, the stator slot width is b s0 The width of the stator slot body close to the stator slot shoulder is b s1 , the width of the stator slot bottom is b s2 , the stator slot height is h s0 , the height of the groove shoulder is h s1 , stator slot depth is h s2 The bottom of the pear-shaped groove is a semicircular arc structure, and the radius of the arc at the bottom of the groove is b s2 / 2 , and the center of the circle is located at the intersection of the middle axis of the stator slot and the boundary lines of the stator slot body and the stator slot bottom.

[0014] Preferably, in step S2, constructing the stator winding of the BL-PMSM with inclined-connected parallel magnetized poles specifically includes the following steps:

[0015] S21. Place two sets of conductors in the 24 stator slots, with the torque winding conductors embedded in the inner slots and the suspension winding conductors embedded in the outer slots. Number the 24 conductors of the torque winding and suspension winding in counterclockwise order as 1, 2, 3, 4, ..., 23, and 24, respectively. The numbers of the torque winding conductors and the suspension winding conductors are consistent with the corresponding stator slot numbers.

[0016] S22. Construct a four-pole torque winding in the inner layer of the slot, connect the torque winding conductor No. 1 and the torque winding conductor No. 7 end-to-end to obtain torque coil No. 1, and connect the torque winding conductor No. 2 and the torque winding conductor No. 8 end-to-end to obtain torque coil No. 2;

[0017] Then connect the No. 1 torque coil and the No. 2 torque coil in series to obtain the No. 1 "torque coil group";

[0018] Connect the No. 13 torque winding conductor and the No. 19 torque winding conductor end to end to obtain the No. 3 torque coil, connect the No. 14 torque winding conductor and the No. 20 torque winding conductor end to end to obtain the No. 4 torque coil, and then connect the No. 3 torque coil and the No. 4 torque coil in series to obtain the No. 2 "torque coil group";

[0019] Connect the No. 1 "torque coil group" and the No. 2 "torque coil group" in series to obtain the "A-phase four-pole torque winding";

[0020] S23. Construct a two-pole suspension winding in the outer layer of the slot. Connect the No. 1 suspension winding conductor and the No. 13 suspension winding conductor end to end to obtain suspension coil No. 1. Connect the No. 2 suspension winding conductor and the No. 14 suspension winding conductor end to end to obtain suspension coil No. 2. Connect the No. 3 suspension winding conductor and the No. 15 suspension winding conductor end to end to obtain suspension coil No. 3. Connect the No. 4 suspension winding conductor and the No. 16 suspension winding conductor end to end to obtain suspension coil No. 4.

[0021] Then, the No. 1 suspension coil, the No. 2 suspension coil, the No. 3 suspension coil, and the No. 4 suspension coil are connected in series in sequence to obtain the "U-phase two-pole suspension winding".

[0022] Preferably, in step S22, according to the construction steps of "A-phase four-pole torque winding", B-phase and C-phase torque windings are constructed, and the A-phase, B-phase and C-phase torque windings of the stator are staggered by 120 electrical degrees in the electrical space.

[0023] Preferably, in step S23, according to the construction step of "U-phase two-pole suspension winding", V-phase and W-phase suspension windings are constructed, and the U-phase, V-phase and W-phase suspension windings of the stator are staggered by 120 electrical degrees in electrical space.

[0024] Preferably, in step S3, the inclined-plane-connected parallel-magnetized combined magnetic pole structure of the BL-PMSM inner rotor is constructed, which specifically includes the following steps:

[0025] S31. Construct a surface-mounted, bevel-connected, parallel-magnetized combined magnetic pole topology. Each combined magnetic pole is composed of three permanent magnets of equal thickness, and the middle main magnetic pole is made of high-remanence permanent magnetic material to form an "arc-bottom trapezoidal" symmetrical structure.

[0026] Two asymmetric trapezoidal auxiliary magnetic poles are symmetrically arranged on both sides of the main magnetic pole using permanent magnetic materials with relatively low remanence. The two auxiliary magnetic poles are seamlessly connected with the main magnetic pole at an angle to form an overall fan-ring structure of "bevel-connected combined magnetic poles".

[0027] S32. Set the parameter variables of the combined magnetic pole, and set the overall pole arc coefficient α1 of the combined magnetic pole, the pole arc coefficient α2 of the main magnetic pole, the pole arc coefficient α3 corresponding to the width of the junction area between the main and auxiliary magnetic poles, and the permanent magnet thickness hm as "structural parameter variables";

[0028] Under the premise that all parameter variables satisfy the relationship of "α1>α2+α3", the overall structure of the combined magnetic pole can be changed by changing the size of the four permanent magnet structural parameter variables α1, α2, α3 and hm;

[0029] The permanent magnet thickness hm parameter is generally selected within the range of 2.5 to 3.5 times the air gap length. At the same time, the main pole residual flux density Brm and the auxiliary pole residual flux density Brs on both sides of the combined magnetic pole are set as "magnetization parameter variables", satisfying the relationship "Brm>Brs".

[0030] S33, determining the limiting condition of the pole arc coefficient α3 corresponding to the width of the interface region where the main and auxiliary magnetic poles meet, such that the pole arc coefficient α3 reaches its maximum value when the interface between the main and auxiliary magnetic poles is tangent to the outer diameter of the rotor;

[0031] S34, performing integrated parallel magnetization on the entire magnetic combination pole after the inclined surfaces are connected, and performing integrated parallel magnetization on the four combined magnetic pole permanent magnet structures after the inclined surfaces are connected along the center lines of each main magnetic pole in an alternating order of N and S polarity, to obtain two inclined surface connected parallel magnetized combined magnetic pole permanent magnet N poles and two inclined surface connected parallel magnetized combined magnetic pole permanent magnet S poles;

[0032] S35. In the order of alternating N and S polarities, the combined magnetic poles are evenly pasted on the outer surface of the rotor core to form a permanent magnet four-pole inner rotor with inclined surfaces connecting parallel magnetized combined magnetic poles.

[0033] Preferably, in step S33, the constraint relationship of α3 is as follows:

[0034]

[0035] According to formula (1), the maximum value of the pole arc coefficient α3 occupied by the inclined surface connection area between the main magnetic pole and the auxiliary magnetic pole can be obtained:

[0036]

[0037] Where Rm in (1) and (2) is the outer diameter of the rotor permanent magnet, and Rr is the outer diameter of the rotor core;

[0038] By changing the six parameter variables and combining them with the magnetization method of the rotor permanent magnet, the air gap magnetic field distribution characteristics and radial magnetic flux density amplitude generated by the inclined plane connecting parallel magnetization combined magnetic poles can be determined.

[0039] Therefore, the design method of the bearingless permanent magnet synchronous motor with parallel magnetized combined poles and inclined plane connection of the present invention has the following beneficial effects:

[0040] (1) Compared with the traditional tile-type combined magnetic pole structure, the inclined-plane-connected parallel-magnetized combined magnetic pole topology structure of the present invention can effectively avoid the local drastic change of the air gap magnetic flux distribution waveform. In addition, the integrated parallel magnetization method can further improve the torque and suspension force control characteristics of the bearingless permanent magnet synchronous motor, and effectively reduce the torque pulsation rate and suspension force pulsation rate.

[0041] (2) The present invention provides specific parameters for the structure of the parallel magnetized combined magnetic poles with inclined connection, especially setting the pole arc coefficient of the inclined connection area between the main magnetic pole and the auxiliary magnetic poles on both sides as a parameter variable, which provides great convenience for the optimization of the combined magnetic pole structure and also provides convenient conditions for the motor structure optimization analysis based on the intelligent optimization algorithm; by changing the combined magnetic pole structure parameters provided in the present invention, the structure of the combined magnetic pole and the air gap magnetic field distribution characteristics and magnetic flux density amplitude generated by it can be changed quickly and accurately.

[0042] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The overall topology diagram of the BL-PMSM with parallel magnetized combined magnetic poles and inclined plane connection according to the design method of the bearingless permanent magnet synchronous motor of the present invention is as follows;

[0044] Figure 2 Schematic diagram of the stator tooth / slot topology structure of the trapezoidal combined magnetic pole type BL-PMSM of the design method of the bearingless permanent magnet synchronous motor with parallel magnetized combined magnetic poles and bevel connection according to the present invention;

[0045] Figure 3Schematic diagram of the A-phase four-pole torque winding of the combined-pole BL-PMSM of the present invention in accordance with the design method of the bearingless permanent magnet synchronous motor with parallel magnetization and combined-pole configuration;

[0046] Figure 4 Schematic diagram of the U-phase two-pole suspension winding of the combined-pole BL-PMSM according to the design method of the bearingless permanent magnet synchronous motor with parallel magnetized combined poles connected by an inclined plane of the present invention;

[0047] Figure 5 A schematic diagram of the topology of the surface-mounted inclined-plane-jointed parallel-magnetized trapezoidal combined magnetic poles of the design method of the bearingless permanent magnet synchronous motor of the present invention;

[0048] Figure 6 This is a schematic diagram of the magnetic pole structure when α3 takes the maximum value in the design method of the bearingless permanent magnet synchronous motor with parallel magnetized combined magnetic poles and inclined surfaces of the present invention. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0050] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" 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 object being described changes, the relative positional relationship may also change accordingly.

[0051] Example

[0052] The present invention provides a design method for a bearingless permanent magnet synchronous motor with parallel magnetized combined magnetic poles and an inclined surface connection, comprising the following steps:

[0053] S1. Construct stator teeth / slots of the BL-PMSM with parallel magnetized combined poles and connected by inclined planes. Evenly arrange the stator teeth / slots of the BL-PMSM along the stator circumference, and arrange 24 stator teeth / slots in a pear-shaped stator slot structure and a parallel stator tooth structure.

[0054] S2. Construct the stator winding of the BL-PMSM with parallel magnetized combined poles and inclined planes. Place two sets of conductors in each stator slot designed in step S1 to form a torque winding conductor and a suspension winding conductor. After numbering each torque winding conductor and suspension winding conductor, construct a four-pole stator torque winding in the inner layer of the slot and a two-pole stator suspension winding in the outer layer of the slot.

[0055] S3. Construct the BL-PMSM inner rotor's inclined-plane connection parallel magnetization combined magnetic pole structure, use high remanence material and low remanence material to construct symmetrical arc-bottom trapezoidal main magnetic poles and asymmetrical trapezoidal auxiliary magnetic poles respectively, connect the main and auxiliary magnetic poles seamlessly at an inclined plane, and use the pole arc coefficient occupied by the width of the connecting inclined plane area as one of the structural parameter variables to construct an integrated parallel magnetization inclined-plane connection combined magnetic pole overall fan ring structure, and then construct the BL-PMSM's permanent magnet four-pole inner rotor structure in an alternating order of N and S polarity.

[0056] In step S1, the specific steps of constructing the stator teeth / slots of the BL-PMSM with parallel magnetized combined poles and inclined surfaces are as follows:

[0057] Figure 1 The overall topological structure diagram of the BL-PMSM with parallel magnetized combined poles connected by inclined planes (see the stator winding connection diagram for details) Figures 3 and 4 ) uses an outer stator and inner rotor structure. Stator teeth / slots are evenly arranged along the inner surface of the stator core. For a stator core with 24 slots / tooth, the slots with a 15° pitch are numbered 1 to 24 in a counterclockwise direction.

[0058] In order to avoid damaging the insulation layer in the slot, a pear-shaped stator slot structure is adopted. Figure 2 is the pear-shaped trough topology diagram adopted, where b s0 is the stator slot width, b s1 b is the width of the stator slot body close to the stator slot shoulder side, s2 is the width of the stator slot bottom, h s0 is the stator slot height, h s1 is the height of the groove shoulder, h s2 is the stator slot depth; the bottom of the pear-shaped slot is a semicircular arc structure, and the radius of the arc at the bottom of the slot is b s2 / 2, with the center of the circle located at the intersection of the stator slot's mid-axis and the stator slot body and bottom boundary. To increase the slot cross-sectional area and motor power density, the stator teeth adopt a parallel tooth structure. This means that adjacent stator slots are parallel to the boundary of the stator tooth between them. In other words, except for the tooth crown, the width of the stator tooth body between two adjacent stator slots is equal.

[0059] In step S2, the specific steps of constructing the stator winding of the BL-PMSM with inclined-connected parallel magnetized poles are as follows:

[0060] First, two sets of conductors are placed in the 24 stator slots, with the torque winding conductors embedded in the inner layer of the slots and the suspension winding conductors embedded in the outer layer of the slots. The 24 conductors of the torque winding and the suspension winding are numbered 1, 2, 3, 4, ..., 23, and 24 in counterclockwise order. The numbers of the torque winding conductors and the suspension winding conductors are consistent with the corresponding stator slot numbers.

[0061] Next, the four-pole torque winding in the inner slot layer is constructed. Torque winding conductors 1 and 7 are connected end-to-end to form torque coil 1. Torque winding conductors 2 and 8 are connected end-to-end to form torque coil 2. Torque coils 1 and 2 are then connected in series to form "torque coil group 1." Torque winding conductors 13 and 19 are connected end-to-end to form torque coil 3. Torque winding conductors 14 and 20 are connected end-to-end to form torque coil 4. Torque coils 3 and 4 are then connected in series to form "torque coil group 2." Torque coil group 1 is then connected in series to form "Phase A (four-pole) torque winding." The torque windings for phases B and C can be constructed similarly. The stator's A, B, and C torque windings are staggered by 120 degrees in electrical space (corresponding to 60 degrees in mechanical angle).

[0062] Next, construct the two-pole suspension winding in the outer slot layer. Connect the No. 1 suspension winding conductor and the No. 13 suspension winding conductor end-to-end to form suspension coil No. 1. Connect the No. 2 suspension winding conductor and the No. 14 suspension winding conductor end-to-end to form suspension coil No. 2. Connect the No. 3 suspension winding conductor and the No. 15 suspension winding conductor end-to-end to form suspension coil No. 3. Connect the No. 4 suspension winding conductor and the No. 16 suspension winding conductor end-to-end to form suspension coil No. 4. Finally, connect the No. 1 suspension coil, the No. 2 suspension coil, the No. 3 suspension coil, and the No. 4 suspension coil in series to form the "U-phase (two-pole) suspension winding." Similarly, the V-phase and W-phase suspension windings can be constructed; the U-phase, V-phase, and W-phase suspension windings of the stator are staggered by 120 degrees in electrical space (corresponding to a 120-degree mechanical angle).

[0063] Through the above steps or methods, a four-pole torque winding and a two-pole suspension winding of the BL-PMSM with parallel magnetized combined magnetic poles connected by an inclined plane can be constructed; Figure 3 and Figure 4 The stator winding connection diagrams are constructed using the A-phase four-pole torque winding and the U-phase two-pole suspension winding as examples.

[0064] In step S3, the specific steps of constructing the inclined-plane-connected parallel-magnetized combined magnetic pole structure of the BL-PMSM inner rotor are as follows:

[0065] First, a surface-mounted inclined-plane parallel magnetization combined magnetic pole topology structure is constructed. Figure 5 As shown, each combined magnetic pole is composed of three permanent magnets of equal thickness; the middle main magnetic pole adopts high remanence permanent magnetic material to form an "arc-bottom trapezoidal" symmetrical structure; two auxiliary magnetic poles with asymmetric trapezoidal structure are symmetrically arranged on both sides of the main magnetic pole using permanent magnetic material with relatively low remanence. The two auxiliary magnetic poles are seamlessly connected with the main magnetic pole at an angle to form an overall fan-ring structure of "bevel-connected combined magnetic pole".

[0066] Then, set the parameter variables of the bevel connection combined magnetic pole. The overall pole arc coefficient α1 of the bevel connection combined magnetic pole (generally 0.7 to 0.95), the pole arc coefficient α2 of the main magnetic pole, the pole arc coefficient α3 of the main and auxiliary magnetic pole bevel connection junction area, the permanent magnet thickness h m Set as "structural parameter variable"; under the premise that each parameter variable satisfies the relationship of "α1>α2+α3", by changing α1, α2, α3 and h m The size of these four permanent magnet structural parameter variables can change the overall structure of the inclined surface connection combined magnetic pole; in order to obtain better torque and suspension force control characteristics, the permanent magnet thickness h m The parameter is generally selected within the range of 2.5 to 3.5 times the air gap length; at the same time, the residual magnetic flux density B of the main magnetic pole of the combined magnetic pole is rm and the residual magnetic flux density B of the auxiliary poles on both sides rs Set as "magnetization parameter variable", which satisfies "B rm >B rs "Relationship.

[0067] Secondly, determine the limiting conditions of the pole arc coefficient α3 corresponding to the width of the junction area between the main and auxiliary magnetic poles. The combined magnetic pole structure when the pole arc coefficient α3 in the junction area between the main magnetic pole and the auxiliary magnetic pole takes the maximum value is as follows: Figure 6 As shown in the figure, when the interface between the main magnetic pole and the auxiliary magnetic pole is tangent to the outer diameter of the rotor, the pole arc coefficient α3 reaches its maximum value. At this time, α3 must satisfy the following constraint relationship:

[0068]

[0069] According to formula (1), the maximum value of the pole arc coefficient α3 occupied by the inclined surface connection area between the main magnetic pole and the auxiliary magnetic pole can be obtained:

[0070]

[0071] In formulas (1) and (2), Rm is the outer diameter of the rotor permanent magnet, and Rr is the outer diameter of the rotor core.

[0072] By changing the six parameter variables and combining them with the magnetization method of the rotor permanent magnet, the air gap magnetic field distribution characteristics and radial magnetic flux density amplitude generated by the inclined plane connecting parallel magnetization combined magnetic poles can be determined.

[0073] Secondly, the entire magnetic combination pole after the bevel connection is integrated and parallel magnetized. In the order of alternating N and S polarity, the four bevel connection combination pole permanent magnet structures are integrated and parallel magnetized along the center line of each main magnetic pole, thereby obtaining two bevel connection parallel magnetization combination pole permanent magnet N poles and two bevel connection parallel magnetization combination pole permanent magnet S poles.

[0074] Finally, the combined magnetic poles are evenly pasted on the outer surface of the rotor core in the order of alternating N and S polarities to form a permanent magnet four-pole inner rotor with inclined connection and parallel magnetization of combined magnetic poles.

[0075] After the above steps, the overall topology of the bearingless permanent magnet synchronous motor with parallel magnetized combined poles connected by inclined planes can be obtained. Figure 1 shown

[0076] The working principle involved in the present invention is as follows:

[0077] (1) Based on the working principle of the bearingless motor, the present invention feeds the torque winding and the suspension winding with a difference of one pole pair into the same frequency current, which can generate stable and controllable electromagnetic torque and radial magnetic suspension force. By reasonably controlling the torque current and suspension current, the stable suspension operation control of the BL-PMSM can be achieved.

[0078] (2) The waveform of the air gap magnetic field of the motor will directly affect its working characteristics. The traditional combined magnetic poles mainly adopt a tile-type structure with equal or unequal thickness, and adopt vertical surface connection (the pole arc coefficient of the junction area of ​​the main and auxiliary magnetic poles of the same combined magnetic pole is 0), which makes the synthetic residual magnetic flux density have a drastic mutation in the junction area of ​​the main and auxiliary magnetic poles; the trapezoidal combined magnetic poles studied at home and abroad mostly adopt the Halbach array, which is different from the single parallel magnetization method, and the application object is ordinary permanent magnet synchronous motor.

[0079] (3) The present invention proposes a new structure of combined magnetic poles with inclined surface connection for BL-PMSM, and adopts an integrated parallel magnetization method to improve the sinusoidality of its air gap magnetic field; the middle main magnetic pole of the combined magnetic pole adopts a symmetrical arc bottom trapezoidal structure, and the auxiliary magnetic poles symmetrically distributed on both sides adopt an asymmetrical trapezoidal structure, and together with the middle main magnetic pole, they form a fan-ring permanent magnet structure after seamless inclined surface connection. The boundary area between the main magnetic pole and the auxiliary magnetic pole of the same combined magnetic pole occupies a certain width (which can be represented by the pole arc coefficient of the inclined surface connection area), which will make the synthetic residual magnetic flux density change continuously in the boundary area, thereby effectively avoiding the step-like mutation of the air gap magnetic field, thereby further improving the degree of consistency between the rising / falling area in the air gap magnetic field waveform and the sine waveform.

[0080] Therefore, the present invention adopts the above-mentioned design method for a bearingless permanent magnet synchronous motor with a beveled connection and combined magnetic poles, which can effectively avoid the phenomenon of local drastic changes in the air gap magnetic flux distribution waveform. In addition, the integrated parallel magnetization method can further improve the torque and suspension force control characteristics of the bearingless permanent magnet synchronous motor, effectively reducing the torque pulsation rate and suspension force pulsation rate. The pole arc coefficient of the beveled connection area between the main magnetic pole and the auxiliary magnetic poles on both sides is set as a parameter variable, which greatly facilitates the optimization of the combined magnetic pole structure and also facilitates the optimization analysis of the motor structure based on the intelligent optimization algorithm. By changing the combined magnetic pole structure parameters given in the present invention, the structure of the combined magnetic pole and the resulting air gap magnetic field distribution characteristics and magnetic flux amplitude can be quickly and accurately changed.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. 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 solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A design method for a bearingless permanent magnet synchronous motor with parallel magnetized combined poles and inclined surfaces, characterized in that: The following steps are involved: S1. Construct stator teeth / slots of the BL-PMSM with parallel magnetized combined poles and connected by inclined planes. Evenly arrange the stator teeth / slots of the BL-PMSM along the stator circumference, and arrange 24 stator teeth / slots in a pear-shaped stator slot structure and a parallel stator tooth structure. S2. Construct the stator winding of the BL-PMSM with parallel magnetized combined poles and inclined planes. Place two sets of conductors in each stator slot designed in step S1 to form a torque winding conductor and a suspension winding conductor. After numbering each torque winding conductor and suspension winding conductor, construct a four-pole stator torque winding in the inner layer of the slot and a two-pole stator suspension winding in the outer layer of the slot. S3. Construct the BL-PMSM inner rotor's inclined-surface connection parallel magnetization combined magnetic pole structure, respectively using high remanence material and low remanence material to construct symmetrical arc-bottom trapezoidal main magnetic poles and asymmetrical trapezoidal auxiliary magnetic poles, seamlessly connect the main and auxiliary magnetic poles at an inclined surface, and use the pole arc coefficient occupied by the width of the connecting inclined surface area as one of the structural parameter variables to construct an integrated parallel magnetization inclined-surface connection combined magnetic pole overall sector ring structure, and then construct the BL-PMSM permanent magnet four-pole inner rotor structure in an alternating order of N and S polarity; In step S3, a parallel magnetized trapezoidal combined magnetic pole structure with inclined plane connection of the BL-PMSM inner rotor is constructed, which specifically includes the following steps: S31. Construct a surface-mounted, bevel-connected, parallel-magnetized combined magnetic pole topology. Each combined magnetic pole is composed of three permanent magnets of equal thickness, and the middle main magnetic pole is made of high-remanence permanent magnet material to form an "arc-bottom trapezoidal" symmetrical structure. Two asymmetric trapezoidal auxiliary magnetic poles are symmetrically arranged on both sides of the main magnetic pole using permanent magnetic materials with relatively low remanence. The two auxiliary magnetic poles are seamlessly connected with the main magnetic pole at an angle to form an overall fan-ring structure of "bevel-connected combined magnetic poles". S32. Set parameter variables of the inclined-surface connection magnetic combination poles, and set the overall pole arc coefficient α1 of the inclined-surface connection magnetic combination poles, the pole arc coefficient α2 of the main magnetic poles, the pole arc coefficient α3 corresponding to the width of the main and auxiliary magnetic pole inclined-surface connection interface area, and the permanent magnet thickness hm as "structural parameter variables." Under the premise that all parameter variables satisfy the relationship of "α1>α2+α3", the overall structure of the inclined-plane joint magnetic pole can be changed by changing the values ​​of the four permanent magnet structural parameter variables α1, α2, α3 and hm. The permanent magnet thickness parameter hm is set within the range of 2.5 to 3.5 times the air gap length. At the same time, the main pole remanent flux density Brm and the auxiliary pole remanent flux density Brs on both sides of the combined magnetic pole are set as "magnetization parameter variables" and satisfy the relationship "Brm>Brs". S33, determining the limiting condition of the pole arc coefficient α3 corresponding to the width of the interface region where the main and auxiliary magnetic poles meet, such that the pole arc coefficient α3 reaches its maximum value when the interface between the main and auxiliary magnetic poles is tangent to the outer diameter of the rotor; S34, performing integrated parallel magnetization on the entire magnetic combination pole after the bevel connection, and sequentially performing integrated parallel magnetization on the four bevel connection magnetic combination pole permanent magnet structures along the center line of each main magnetic pole in the order of alternating N and S polarities, to obtain two bevel connection parallel magnetization magnetic combination pole permanent magnet N poles and two bevel connection parallel magnetization magnetic combination pole permanent magnet S poles; S35. In the order of alternating N and S polarities, the combined magnetic poles are evenly pasted on the outer surface of the rotor core to form a permanent magnet four-pole inner rotor with inclined surfaces connecting parallel magnetized combined magnetic poles.

2. The design method of a bearingless permanent magnet synchronous motor with parallel magnetization and combined magnetic poles connected by inclined surfaces according to claim 1 is characterized in that: In step S1, the steps for constructing the stator teeth / slots of the BL-PMSM with parallel magnetized combined poles and inclined surfaces are as follows: S11, adopting an outer stator and inner rotor structure, 24 stator teeth / slots are evenly arranged along the inner surface of the stator core; S12. Number the stator slots with a slot pitch of 15° from 1 to 24 in a counterclockwise direction.

3. The design method of a bearingless permanent magnet synchronous motor with parallel magnetization and combined magnetic poles connected by inclined surfaces according to claim 2 is characterized in that: In step S12, the stator slot width is b s0 The width of the stator slot body close to the stator slot shoulder is b s1 , the width of the stator slot bottom is b s2 , the stator slot height is h s0 , the height of the groove shoulder is h s1 , stator slot depth is h s2 The bottom of the pear-shaped groove is a semicircular arc structure, and the radius of the arc at the bottom of the groove is b s2 / 2 , and the center of the circle is located at the intersection of the middle axis of the stator slot and the boundary lines of the stator slot body and the stator slot bottom.

4. The design method of a bearingless permanent magnet synchronous motor with parallel magnetization and combined magnetic poles connected by inclined surfaces according to claim 1 is characterized in that: In step S2, the stator winding of the BL-PMSM with parallel magnetized combined poles connected by an inclined plane is constructed, which specifically includes the following steps: S21. Place two sets of conductors in the 24 stator slots, with the torque winding conductors embedded in the inner slots and the suspension winding conductors embedded in the outer slots. Number the 24 conductors of the torque winding and suspension winding in counterclockwise order as 1, 2, 3, 4, ..., 23, and 24, respectively. The numbers of the torque winding conductors and the suspension winding conductors are consistent with the corresponding stator slot numbers. S22. Construct a four-pole torque winding in the inner layer of the slot. Connect the No. 1 torque winding conductor and the No. 7 torque winding conductor end to end to obtain the No. 1 torque coil. Connect the No. 2 torque winding conductor and the No. 8 torque winding conductor end to end to obtain the No. 2 torque coil. Finally, connect the No. 1 torque coil and the No. 2 torque coil in series to obtain the No. 1 "torque coil group." Connect the No. 13 torque winding conductor and the No. 19 torque winding conductor end to end to obtain the No. 3 torque coil. Connect the No. 14 torque winding conductor and the No. 20 torque winding conductor end to end to obtain the No. 4 torque coil. Then connect the No. 3 torque coil and the No. 4 torque coil in series to obtain the No. 2 "torque coil group". Connect the No. 1 "torque coil group" and the No. 2 "torque coil group" in series to obtain the "A-phase four-pole torque winding"; S23. Construct a two-pole suspension winding in the outer layer of the slot. Connect the No. 1 suspension winding conductor and the No. 13 suspension winding conductor end to end to obtain suspension coil No.

1. Connect the No. 2 suspension winding conductor and the No. 14 suspension winding conductor end to end to obtain suspension coil No.

2. Connect the No. 3 suspension winding conductor and the No. 15 suspension winding conductor end to end to obtain suspension coil No.

3. Connect the No. 4 suspension winding conductor and the No. 16 suspension winding conductor end to end to obtain suspension coil No.

4. Then, No. 1 suspension coil, No. 2 suspension coil, No. 3 suspension coil, and No. 4 suspension coil are connected in series in sequence to obtain a "U-phase two-pole suspension winding".

5. The design method of a bearingless permanent magnet synchronous motor with parallel magnetization and combined magnetic poles connected by inclined surfaces according to claim 4 is characterized in that: In step S22, according to the construction steps of "A-phase four-pole torque winding", B-phase and C-phase torque windings are constructed, and the A-phase, B-phase and C-phase torque windings of the stator are staggered by 120 electrical degrees in the electrical space.

6. The design method of a bearingless permanent magnet synchronous motor with parallel magnetization and combined magnetic poles connected by inclined surfaces according to claim 4 is characterized in that: In step S23, according to the construction steps of "U-phase two-pole suspension winding", V-phase and W-phase suspension windings are constructed, and the U-phase, V-phase, and W-phase suspension windings of the stator are staggered by 120 electrical degrees in electrical space.

7. The design method of a bearingless permanent magnet synchronous motor with parallel magnetization and combined magnetic poles connected by inclined surfaces according to claim 1, characterized in that: In step S33, the constraint relationship of α3 is as follows: （1） According to formula (1), the maximum value of the pole arc coefficient α3 occupied by the inclined surface connection area between the main magnetic pole and the auxiliary magnetic pole can be obtained: （2） In (1) and (2), Rm is the outer diameter of the rotor permanent magnet, and Rr is the outer diameter of the rotor core.

Images