Natural gas pressure differential generator with bilateral biaxial magnetic bearings and parameter determination method

Abstract

The present invention provides a bilateral dual-axial magnetic levitation bearing natural gas pressure differential generator and a parameter determination method, relating to the technical field of natural gas pressure differential power generation equipment. The present invention designs a bilateral dual-axial magnetic levitation bearing natural gas pressure differential generator, including an axial air inlet, an axial air outlet, a flow channel, a fairing, a turbine impeller, a stator, a magnetic levitation bearing mechanism and a body casing. This structure can effectively solve the stability problem of natural gas pressure differential power generation equipment under high axial thrust, and improve the system's load-bearing capacity and operating efficiency. At the same time, the present invention provides a bilateral dual-axial magnetic levitation bearing natural gas pressure differential generator parameter determination method, using a stator material of amorphous alloy and silicon steel laminated, and using a fruit fly algorithm and a genetic algorithm to respectively optimize the radial and axial magnetic bearing structural parameters. The optimized radial and axial magnetic levitation bearing structural parameters further improve the performance of the magnetic bearings, reduce the volume and weight of the equipment, and reduce the manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas pressure differential power generation equipment, in particular to a natural gas pressure differential generator with bilateral dual-axial magnetic suspension bearings and a parameter determination method. Background Art

[0002] The application of magnetic bearing technology is crucial in natural gas differential pressure power generation equipment. Traditional mechanical bearings, due to friction loss, limited mechanical lifespan, and incompatibility with high-speed operation, are no longer able to meet the demands of modern, high-efficiency power generation equipment. Magnetic bearings utilize electromagnetic force to achieve contactless levitation of the rotor. They offer advantages such as frictionlessness, cleanliness, long life, and ultra-high speed, making them widely used in high-speed, high-precision, and high-reliability scenarios.

[0003] However, magnetic bearings face numerous challenges in natural gas differential pressure power generation equipment. Rapid changes in high-pressure differential airflow significantly increase the impeller's axial force. Impeller design parameters (such as blade shape and mounting angle) significantly influence the axial component of the airflow, generating significant axial thrust. Furthermore, the rapid decompression and cooling of the gas inside the turbine, which causes changes in density and velocity, is also a key factor in the generation of axial thrust. Uneven airflow distribution, mechanical imbalances in rotating components, and high-performance sealing systems can further increase axial thrust. This increased thrust not only increases the load on the magnetic bearing and reduces its stability, but can also lead to magnetic circuit saturation. Over time, this can exacerbate vibration, reduce power generation efficiency, and increase maintenance costs.

[0004] In practical applications, magnetic bearings have obvious limitations in handling high axial thrust. On the one hand, material strength limits the thrust level they can withstand; on the other hand, motor size limitations also affect performance improvements. Axial thrust is closely related to generator size, but due to space and weight constraints, the generator size cannot be expanded indefinitely, which in turn limits the load-bearing capacity of magnetic bearings. In addition, the magnetic saturation effect must be considered in the design. Excessive magnetic field strength will lead to magnetic saturation, thereby limiting the increase in axial thrust. The design of axial magnetic bearings is also difficult, requiring a special magnetic pole structure and electromagnetic design to meet high thrust requirements.

[0005] The application of existing magnetic bearing technology in natural gas differential pressure power generation equipment is subject to multiple limitations, particularly under high axial thrust conditions, where its stability and load-bearing capacity cannot meet practical requirements. Therefore, developing a magnetic bearing structure that can effectively handle high axial thrust, improve system stability, and enhance power generation efficiency is of great practical significance in the field of natural gas differential pressure power generation. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a natural gas pressure differential generator with bilateral dual-axial magnetic bearings, which includes an axial air inlet, an axial air outlet, a flow channel, a fairing, a turbine impeller, a stator, a magnetic bearing mechanism, and a body casing;

[0007] The bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator is provided with an axial air inlet at the input end and an axial air outlet at the output end;

[0008] The magnetic suspension bearing mechanism includes a rotor and two bearing sub-mechanisms, each of which includes an axial magnetic bearing, a radial magnetic bearing, a protective bearing, and a thrust plate. The two bearing sub-mechanisms are installed at both ends of the rotor, and the thrust plate is fixed to the rotor by welding. The protective bearing, axial magnetic bearing, and radial magnetic bearing are sleeved on the rotor. From the center of the rotor to the two ends, the radial magnetic bearing, axial magnetic bearing, and protective bearing are respectively included, and the thrust plate is located on the inner side of the axial magnetic bearing; a stator is provided between the two bearing sub-mechanisms, and the stator is fixed to the body shell;

[0009] A fairing is provided on both ends of the magnetic bearing mechanism. The axial magnetic bearing, radial magnetic bearing, protective bearing and thrust plate are located inside the fairing. The fairing is provided with 8 flow holes and is fixed to the body shell. The turbine impeller is fixed to the rotor by interlocking.

[0010] The flow channel includes a first flow channel and a second flow channel. The first flow channel is a flow channel passing through the flow hole of the fairing and passing through the inside of the fairing. The second flow channel is a flow channel between the outside of the fairing and the inside of the body shell.

[0011] A method for determining parameters of a natural gas pressure differential generator with bilateral dual-axial magnetic bearings is implemented based on a natural gas pressure differential generator with bilateral dual-axial magnetic bearings, including:

[0012] Step 1: Calculate the air gap flux density of the magnetic circuit nodes of the radial magnetic bearing, and then obtain the expression of the bearing capacity of the radial magnetic bearing based on the air gap flux density;

[0013] Step 2: Calculate the total magnetic resistance of the magnetic circuit considering the edge effect, and then determine the final expression of the load-bearing capacity of the axial magnetic bearing;

[0014] Step 3: Load-carrying capacity of radial magnetic bearings based on fruit fly algorithm and genetic algorithm The expression and final bearing capacity of the axial magnetic bearing The expression of is used to determine the parameters of the natural gas pressure differential generator with bilateral dual axial magnetic bearings;

[0015] Step 4: Based on the parameters of the bilateral dual-axial magnetic bearing natural gas pressure differential generator, adjust the structure of the bilateral dual-axial magnetic bearing natural gas pressure differential generator to obtain the final bilateral dual-axial magnetic bearing natural gas pressure differential generator.

[0016] Optionally, step 1 specifically includes:

[0017] Step 1.1: Calculate the magnetic circuit nodes of the radial magnetic bearing without considering magnetic circuit saturation i Air gap flux density at , which is specifically achieved through the following formula:

[0018] ;

[0019] in, represents the vacuum permeability, For nodes The magnetomotive force at The magnetic pole center node i The circumferential position of the air gap, Circumferential position The air gap length at

[0020] Among them, when the rotor is eccentric, Calculated by the following formula:

[0021] ;

[0022] in, is the eccentricity, is the eccentric angle, is the air gap length between the rotor and the stator when the rotor is in equilibrium position;

[0023] Among them, the node Magnetomotive force Calculated by the following formula:

[0024] ;

[0025] Where N represents the number of winding turns, Node The control current at represents the bias current;

[0026] Step 1.2: Set the initial iteration number to 0, and initialize the air gap magnetic flux of each node at the initial iteration number. Add 1 to the initial iteration number as the current iteration number j, and use the air gap magnetic flux calculated in step 1.1 as the air gap magnetic flux at the current iteration number.

[0027] Step 1.3: According to the air gap magnetic flux density at the current iteration number Compute nodes The stator pole flux density at , which is specifically achieved through the following formula:

[0028] ;

[0029] in, is the magnetic flux leakage compensation coefficient;

[0030] Compute nodes The magnetic flux density of the rotor yoke , which is specifically achieved through the following formula:

[0031] ;

[0032] in, For nodes The air gap magnetic density at is the effective air gap width, For nodes The magnetic flux density of the rotor yoke at is the rotor yoke width, is the air gap flux density at node 1, The magnetic flux density of the rotor yoke at node 1;

[0033] Step 1.4: Compute Node The magnetic flux density of the stator yoke , which is specifically achieved through the following formula:

[0034] ;

[0035] in, For nodes The stator pole flux density at , For nodes The magnetic flux density of the stator yoke at is the stator pole width, is the stator yoke width, is the stator pole flux density at node 1, is the magnetic flux density of the stator yoke at node 1;

[0036] Step 1.5: Iteratively calculate the total magnetomotive force based on the magnetic field strength and effective length of each loop segment , which is specifically achieved through the following formula:

[0037] ;

[0038] in, The magnetic pole center node The air gap length at the circumferential position of the air gap, For nodes The magnetic field strength at the stator pole is For nodes i The magnetic field strength of the rotor yoke at For nodes i The magnetic field strength of the stator yoke at is the effective length of each stator pole, is the effective length of each rotor yoke, is the effective length of each stator yoke;

[0039] Computation loop at node i Magnetomotive force , which is specifically achieved through the following formula:

[0040] ;

[0041] in, For nodes The magnetomotive force at is the magnetomotive force at node 1, is the magnetomotive force at node 8;

[0042] Step 1.6: Calculate the loop at the node i Magnetomotive force error at , which is specifically achieved through the following formula:

[0043] ;

[0044] The total magnetomotive force error of all circuits is then calculated as shown in the following formula:

[0045] ;

[0046] Step 1.7: Determine whether the total magnetomotive force error is greater than the preset accuracy requirement value. If the total magnetomotive force error is not greater than the preset accuracy requirement value, the air gap magnetic flux density at the current iteration number is used as the final air gap magnetic flux density. , execute step 1.9. If the total magnetomotive force error is greater than the preset accuracy requirement value, execute step 1.8;

[0047] Step 1.8: Correct the air gap flux density using the following formula:

[0048] ;

[0049] in, is the empirical coefficient, Indicates the node under the current iteration number j after correction i The air gap flux density at represents the air gap flux density at node 8 in the j-1th iteration, represents the magnetomotive force error of the loop at node 8;

[0050] The current iteration number is increased by one, As the new air gap flux density at the current iteration number , return to step 1.3;

[0051] Step 1.9: Calculate the circumferential position using the one-dimensional relative permeability function Air gap flux density , which is specifically achieved through the following formula:

[0052] ;

[0053] in, for The first derivative of ;

[0054] Step 1.10: Based on the linearized single-degree-of-freedom electromagnetic force formula, obtain the bearing capacity of the radial magnetic bearing The expression is realized by the following formula:

[0055] ;

[0056] ;

[0057] ;

[0058] in, is the horizontal component of force, is the vertical component of force, is the effective area of ​​the magnetic pole.

[0059] Optionally, the linearized single-degree-of-freedom electromagnetic force formula described in step 1.10 is expressed as:

[0060] ;

[0061] in, is a single degree of freedom electromagnetic force , is the vacuum permeability, is the number of winding turns, is the cross-sectional area of ​​the air gap, is the rotor displacement, is the bias current, To control the current, is the rated operating point position, α is the force and angle of the magnetic pole acting on the rotor.

[0062] Optionally, step 2 specifically includes:

[0063] Step 2.1: Ignore the vibration of the thrust plate. The magnetic field of the axial electromagnetic bearing is a static field, and there is no eddy current in the rotor core. Ignore the magnetic resistance of the stator and rotor cores. Only consider the air gap magnetic resistance. Calculate the total magnetic resistance of the magnetic circuit taking into account the edge effect. This is achieved using the following formula:

[0064] ;

[0065] in, represents the total magnetic resistance of the magnetic circuit, R i and R o is the reluctance at the main air gap, R 2 is the leakage magnetic resistance between the outer magnetic pole and the thrust plate, R 1 is the magnetic resistance at the air gap between the rotor and the stator, R ii is the magnetic flux leakage inside the inner pole, R io The magnetic flux leakage outside the inner magnetic pole is R oi is the magnetic flux leakage inside the outer magnetic pole, R oo It is the magnetic flux leakage outside the outer magnetic pole;

[0066] Step 2.2: Calculate the bearing capacity of the axial magnetic bearing based on the linearized single-degree-of-freedom electromagnetic force formula The formula is implemented by the following formula:

[0067] ;

[0068] ;

[0069] Where S represents the area of ​​the magnetic pole end including the edge flux range, is the total magnetic flux of the magnetic circuit, It is the main magnetic flux through the stator inner and outer poles in series with the thrust plate and the main air gap on the inner end face. It is the main magnetic flux through the stator inner and outer poles in series with the thrust plate and the main air gap on the outer end face. 、 、 、 is the fringe flux flowing through the stator poles and in parallel with the main air gaps between the two magnetic pole end faces, The magnetic flux passes through the inner magnetic pole of the stator and is connected in series with the adjacent rotating shaft, in parallel with the inner end surface working air gap and in series with the outer end surface working air gap. is the magnetic flux passing through the thrust plate and connected in parallel with the main air gap of the outer magnetic pole;

[0070] Step 2.3: Load-bearing capacity of axial magnetic bearings The formula is simplified to obtain the final bearing capacity of the axial magnetic bearing The expression of is specifically expressed by the following formula:

[0071] ;

[0072] in, is the extreme magnetic pole area including the edge flux range at the inner magnetic pole, They are the extreme pole areas at the outer pole including the edge flux range.

[0073] Optionally, step 3 specifically includes:

[0074] Step 3.1: Load-carrying capacity based on radial magnetic bearings , setting a first objective function and a first constraint condition, optimizing the radial magnetic bearing structural parameters based on the fruit fly algorithm and the first objective function and the first constraint condition, and obtaining optimized radial magnetic bearing structural parameters;

[0075] Step 3.2: Based on the final axial magnetic bearing capacity , set the second objective function and the second constraint condition, optimize the axial magnetic bearing structural parameters based on the genetic algorithm, the second objective function and the second constraint condition, and obtain the optimized axial magnetic bearing structural parameters.

[0076] Optionally, the radial magnetic bearing structural parameters described in step 3.1 E 1 is represented by:

[0077] ;

[0078] in, is the stator pole width, is the stator slot width, is the rotor yoke width, is the stator yoke width, is the rotor outer diameter, is the stator pole height, is the axial width of the radial magnetic bearing, Indicates the radian of the stator magnetic extreme end face;

[0079] Wherein, the first objective function is expressed as:

[0080] ;

[0081] in, is the pole width, is the air gap circumferential position of the magnetic pole center, i max is the maximum current, s represents the area of ​​the magnetic pole end face including the edge flux range, represents the axial volume;

[0082] The first constraint condition is expressed as:

[0083] ;

[0084] in, B Indicates the maximum magnetic flux density.

[0085] Optionally, the axial magnetic bearing structural parameters described in step 3.2 E 2 is expressed as:

[0086] E 2={ r 0, r 1, r 2, r 3, r 4, r 5, r 6, h 1, h 2, h 3, h 4};

[0087] in, r 0 is the rotor radius, r 1 is the inner radius of the stator, r 2 is the outer radius of the stator inner magnetic pole, r 3 is the inner radius of the stator outer magnetic pole, r 4 is the radius of the stator outer magnetic pole, r 5 is the outer radius of the stator slot, r 6 is the outer radius of the stator, h 1 is the axial length of the stator, h 2 is the axial length of the wire slot, h 3 is the axial thickness of the stator yoke, h 4 is the axial length of the stator outer magnetic pole;

[0088] Wherein, the second objective function is expressed as:

[0089] ;

[0090] in, Indicates the dimensions of the axial magnetic bearing, and Expressed as:

[0091] ;

[0092] The second constraint is expressed as:

[0093] ;

[0094] in, is the maximum linear flux density of the soft magnetic material, is the coil wire diameter, is a coefficient determined based on experience;

[0095] The optimized radial magnetic bearing structural parameters and the optimized axial magnetic bearing structural parameters constitute the parameters of the bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator.

[0096] The beneficial effects of adopting the above technical solution are:

[0097] The present invention designs a bilateral dual-axial magnetic levitation bearing natural gas pressure differential generator. The structure of the bilateral dual-axial magnetic levitation bearing natural gas pressure differential generator can effectively solve the stability problem of natural gas pressure differential power generation equipment under high axial thrust, and improve the system's load-bearing capacity and operating efficiency. At the same time, the present invention provides a method for determining the parameters of the bilateral dual-axial magnetic levitation bearing natural gas pressure differential generator. The stator material is a laminated amorphous alloy and silicon steel, and the fruit fly algorithm and genetic algorithm are used to optimize the radial and axial magnetic bearing structural parameters respectively. The optimized radial and axial magnetic levitation bearing structural parameters further improve the performance of the magnetic bearings, reduce the volume and weight of the equipment, and reduce the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 Schematic diagram of the structure of a natural gas pressure differential generator with bilateral dual-axial magnetic bearings in an embodiment of the present invention;

[0099] Figure 2 Schematic diagram of a magnetic bearing mechanism in an embodiment of the present invention

[0100] Figure 3 is a schematic diagram of a bearing sub-mechanism in an embodiment of the present invention;

[0101] Figure 4 Schematic diagram of the magnetic pole arrangement of an octupole radial magnetic bearing in an embodiment of the present invention, wherein (a) is a schematic diagram of the NSNS arrangement, and (b) is a schematic diagram of the NSSN arrangement;

[0102] Figure 5 Schematic diagram of the magnetic circuit of an octapole radial magnetic bearing in an embodiment of the present invention;

[0103] Figure 6 Schematic diagram of the magnetic circuit model of an octapole radial magnetic bearing in an embodiment of the present invention;

[0104] Figure 7 Schematic diagram of the flow of a method for determining parameters of a natural gas pressure differential generator with bilateral dual-axial magnetic bearings in an embodiment of the present invention;

[0105] Figure 8Schematic diagram of the magnetic circuit of an axial magnetic bearing in an embodiment of the present invention;

[0106] Figure 9 Schematic diagram of an equivalent magnetic circuit model of an axial electromagnetic bearing in an embodiment of the present invention;

[0107] In the figure, 1-axial air inlet, 2-axial air outlet, 3-flow channel, 4-fairing, 5-turbine impeller, 6-stator, 7-magnetic bearing mechanism, 8-body casing, 301-first flow channel, 302-second flow channel, 701-rotor, 702-bearing sub-mechanism, 7021-axial magnetic bearing, 7022-radial magnetic bearing, 7023-protective bearing, 7024-thrust plate, A-stator yoke, B-magnetic pole, C-rotor yoke, E-stator reluctance, F-magnetic pole reluctance, G-air gap reluctance, H-rotor reluctance, I-magnetomotive force, J-coil, K-main circuit inner and outer magnetic ring end face air gap reluctance, L-rotor and stator inner magnetic pole air gap leakage reluctance, M-outer magnetic pole main air gap parallel circuit air gap reluctance, N-edge circuit air gap reluctance. DETAILED DESCRIPTION

[0108] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0109] In response to the problems existing in the prior art, the present invention solves the technical difficulties of natural gas pressure difference power generation equipment under high axial thrust by optimizing the structural design and electromagnetic parameters of magnetic levitation bearings, thereby improving the operating efficiency and reliability of the equipment. The present invention provides a bilateral dual-axial magnetic levitation bearing natural gas pressure difference generator. Compared with the traditional unilateral single-degree-of-freedom magnetic bearing structure, the bilateral dual-axial magnetic bearing has high load-bearing capacity, high-precision control, and strong impact resistance. However, the bilateral dual-axial magnetic bearing structure is complex and large in size, which limits space. Therefore, based on this structure, the magnetic bearing structure is re-optimized and designed to achieve the dual goals of compact structure and improved efficiency while maintaining high performance. Figure 1 The structural diagram of the bilateral dual-axial magnetic bearing natural gas pressure difference generator, and Figure 2 Schematic diagram of the magnetic bearing mechanism, and Figure 3 Schematic diagram of the bearing sub-mechanism, the bilateral dual-axial magnetic bearing natural gas pressure difference generator includes an axial air inlet 1, an axial air outlet 2, a flow channel 3, a fairing 4, a turbine impeller 5, a stator 6, a magnetic bearing mechanism 7 and a body casing 8;

[0110] The bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator is provided with an axial air inlet 1 at the input end and an axial air outlet 2 at the output end;

[0111] The magnetic levitation bearing mechanism 7 includes a rotor 701 and two bearing sub-mechanisms 702. The bearing sub-mechanisms 702 include an axial magnetic bearing 7021, a radial magnetic bearing 7022, a protective bearing 7023 and a thrust plate 7024. The two bearing sub-mechanisms 702 are installed at both ends of the rotor. The thrust plate 7024 is fixed to the rotor 701 by welding. The protective bearing 7023, the axial magnetic bearing 7021 and the radial magnetic bearing 7022 are sleeved on the rotor 701. From the center of the rotor 701 to the two ends, there are the radial magnetic bearing 7022, the axial magnetic bearing 7021 and the protective bearing 7023 respectively, and the thrust plate 7024 is located on the inner side of the axial magnetic bearing 7021; a stator 6 is arranged between the two bearing sub-mechanisms 702, and the stator 6 is fixed to the body shell 8.

[0112] The stator 6 is the stationary portion of the motor, assembled from multiple layers of thin silicon steel sheets coated with insulating varnish. These sheets are slotted with windings, which consist of multiple insulated copper wires wound in a specific pattern within the slots. When energized, the stator windings generate a rotating magnetic field, driving the rotor. The rotor 701 is the rotating portion of the motor, constructed from multiple thin sheets of electrical steel stacked in a specific pattern. Rotor 701 is mounted on the drive shaft via bearings. When energized, the induced current interacts with the magnetic field on the rotor to generate torque, driving the shaft to rotate. The housing 8 is a closed annular casing that secures and protects the internal components. Both ends of the housing 8 are sealed with end caps. To meet explosion-proof requirements, the housing 8 must be constructed with a high-pressure-resistant, pressure-bearing structure and equipped with strict protection levels and a ventilation system. Booster devices are also required in locations such as the terminal box.

[0113] A fairing 4 is provided on both ends of the magnetic bearing mechanism. An axial magnetic bearing 7021, a radial magnetic bearing 7022, a protective bearing 7023, and a thrust plate 7024 are located inside the fairing 4. The fairing 4 is provided with eight flow holes and is fixed to the body casing 8. The turbine impeller 5 is fixed to the rotor 701 by interlocking.

[0114] The flow channel 3 includes a first flow channel 301 and a second flow channel 302. The first flow channel 301 is a flow channel passing through the flow hole of the fairing 4 and the inside of the fairing 4. The second flow channel 302 is a flow channel between the outside of the fairing 4 and the inside of the body shell.

[0115] The first and second flow channels are used to recover heat energy generated by the high-speed operation of the motor, improving aerodynamic efficiency. The motor adopts a deep-grooved stator structure and uses natural gas as the cooling medium. The dual-flow channel natural gas converges on the stator teeth to enhance the heat dissipation of the rotor shaft.

[0116] The rotor in the electromagnetic structure of the radial magnetic bearing adopts a laminated structure, and the radial magnetic suspension bearing adopts a heteropolar structure with 8 magnetic poles arranged in NSSN. The load-bearing capacity of the radial magnetic bearing is analytically calculated using the distributed magnetic circuit method, the magnetic pole structure and parameters are optimized, the load-bearing capacity and control accuracy of the radial magnetic bearing are improved, and the structural parameters of the radial magnetic bearing are optimized to increase the load-bearing capacity and reduce the axial length and volume. Figure 4 As shown in the figure, (a) is a schematic diagram of the NSNS arrangement, and (b) is a schematic diagram of the NSSN arrangement. A complete magnetic circuit of the radial magnetic bearing is divided into four sections: the stator yoke section, the stator pole section, the air gap section, and the rotor yoke section. In the circumferential direction, the magnetic bearing is evenly divided into 8 sections with the center position of each magnetic pole as a node, resulting in 8 magnetic rings. The magnetic circuit diagram is shown in the figure. Figure 5 As shown, A is the stator yoke, B is the magnetic pole, and C is the rotor yoke. The magnetic circuit model diagram is shown in Figure 6 As shown, where E is the stator reluctance, F is the pole reluctance, G is the air gap reluctance, H is the rotor reluctance, and I is the magnetomotive force. Since the magnetic circuit is a closed loop, Figure 6 Node 1(8) and Node 8(1) indicate that Node 1 and Node 8 are the same node.

[0117] Based on this, the present invention also provides a method for determining parameters of a natural gas pressure difference generator with bilateral dual-axial magnetic suspension bearings, which is realized based on a natural gas pressure difference generator with bilateral dual-axial magnetic suspension bearings, combined with Figure 7 , specifically including the following steps:

[0118] Step 1: Calculate the air gap flux density of the magnetic circuit nodes of the radial magnetic bearing, and then obtain the expression of the bearing capacity of the radial magnetic bearing based on the air gap flux density;

[0119] Step 1.1: Calculate the magnetic circuit nodes of the radial magnetic bearing without considering magnetic circuit saturation i Air gap flux density at , which is specifically achieved through the following formula:

[0120] ;

[0121] in, represents the vacuum permeability, For nodes The magnetomotive force at The magnetic pole center node i The circumferential position of the air gap, Circumferential position The air gap length at

[0122] Among them, according to the geometric relationship, when the rotor is eccentric, Calculated by the following formula:

[0123] ;

[0124] in, is the eccentricity, is the eccentric angle, is the air gap length between the rotor and the stator when the rotor is in equilibrium position;

[0125] Among them, the node Magnetomotive force Calculated by the following formula:

[0126] ;

[0127] Where N represents the number of winding turns, Node The control current at represents the bias current;

[0128] Step 1.2: Set the initial iteration number to 0, and initialize the air gap magnetic flux of each node at the initial iteration number. Add 1 to the initial iteration number as the current iteration number j, and use the air gap magnetic flux calculated in step 1.1 as the air gap magnetic flux at the current iteration number.

[0129] Step 1.3: According to the air gap magnetic flux density at the current iteration number Compute nodes The stator pole flux density at , which is specifically achieved through the following formula:

[0130] ;

[0131] in, is the magnetic flux leakage compensation coefficient;

[0132] Compute nodes The magnetic flux density of the rotor yoke , which is specifically achieved through the following formula:

[0133] ;

[0134] in, For nodes The air gap magnetic density at is the effective air gap width, For nodes The magnetic flux density of the rotor yoke at is the rotor yoke width, is the air gap flux density at node 1, The magnetic flux density of the rotor yoke at node 1;

[0135] Step 1.4: Compute Node The magnetic flux density of the stator yoke , which is specifically achieved through the following formula:

[0136] ;

[0137] in, For nodes The stator pole flux density at , For nodes The magnetic flux density of the stator yoke at is the stator pole width, is the stator yoke width, is the stator pole flux density at node 1, is the magnetic flux density of the stator yoke at node 1;

[0138] Step 1.5: Iteratively calculate the total magnetomotive force based on the magnetic field strength and effective length of each loop segment , which is specifically achieved through the following formula:

[0139] ;

[0140] in, The magnetic pole center node The air gap length at the circumferential position of the air gap, For nodes The magnetic field strength at the stator pole is For nodes i The magnetic field strength of the rotor yoke at For nodes i The magnetic field strength of the stator yoke at is the effective length of each stator pole, is the effective length of each rotor yoke, is the effective length of each stator yoke;

[0141] Computation loop at node i Magnetomotive force , which is specifically achieved through the following formula:

[0142] ;

[0143] in, For nodes The magnetomotive force at is the magnetomotive force at node 1, is the magnetomotive force at node 8;

[0144] Step 1.6: Calculate the loop at the node i Magnetomotive force error at , which is specifically achieved through the following formula:

[0145] ;

[0146] The total magnetomotive force error of all circuits is then calculated as shown in the following formula:

[0147] ;

[0148] Step 1.7: Determine whether the total magnetomotive force error is greater than the preset accuracy requirement value. If the total magnetomotive force error is not greater than the preset accuracy requirement value, the air gap magnetic flux density at the current iteration number is used as the final air gap magnetic flux density. , execute step 1.9. If the total magnetomotive force error is greater than the preset accuracy requirement value, execute step 1.8;

[0149] Step 1.8: Consider the saturation of the magnetic bearing material and correct the air gap flux density. This is achieved using the following formula:

[0150] ;

[0151] in, is the empirical coefficient, Indicates the node under the current iteration number j after correction i The air gap flux density at represents the air gap flux density at node 8 in the j-1th iteration, represents the magnetomotive force error of the loop at node 8;

[0152] The current iteration number is increased by one, As the new air gap flux density at the current iteration number , return to step 1.3;

[0153] Step 1.9: Calculate the circumferential position using the one-dimensional relative permeability function Air gap flux density , which is specifically achieved through the following formula:

[0154] ;

[0155] in, for The first derivative of ;

[0156] Step 1.10: Based on the linearized single-degree-of-freedom electromagnetic force formula, obtain the bearing capacity of the radial magnetic bearing The expression is realized by the following formula:

[0157] ;

[0158] ;

[0159] ;

[0160] in, is the horizontal component of force, is the vertical component of force, is the effective area of ​​the magnetic pole.

[0161] The linearized single-degree-of-freedom electromagnetic force formula is obtained as follows:

[0162] Assuming that the magnetic flux mainly passes through the rotor core and is evenly distributed, and neglecting magnetic leakage, the electromagnetic force is calculated using the virtual displacement principle. Combined with the magnetic flux density results, the electromagnetic force expression is obtained, and a linearization process is performed for a single-degree-of-freedom differential magnetic bearing.

[0163] The electromagnetic force is calculated using the virtual displacement principle. When the air gap changes slightly, the gravitational force does work and the field energy changes. At this time, the force exerted by the magnetic pole on the rotor has an angle , the electromagnetic force on a single degree of freedom is expressed as follows:

[0164] ;

[0165] in, , is the vacuum permeability, for Number of winding turns, is the cross-sectional area of ​​the air gap, is the rotor displacement, is the bias current, To control the current, is the rated operating point position.

[0166] When the core is in equilibrium (no eccentricity) and When , the single-degree-of-freedom electromagnetic force formula is simplified and linearized to obtain the linearized single-degree-of-freedom electromagnetic force formula, which is expressed as:

[0167] ;

[0168] in, is a single degree of freedom electromagnetic force , is the vacuum permeability, is the number of winding turns, is the cross-sectional area of ​​the air gap, is the rotor displacement, is the bias current, To control the current, is the rated operating point position, α is the force and angle of the magnetic pole acting on the rotor.

[0169] Step 2: Calculate the total magnetic resistance of the magnetic circuit considering the edge effect, and then determine the final expression of the load-bearing capacity of the axial magnetic bearing;

[0170] Step 2.1: Ignore the vibration of the thrust plate. The magnetic field of the axial electromagnetic bearing is a static field. There is no eddy current in the rotor core. Ignore the magnetic resistance of the stator and rotor core. Only consider the air gap magnetic resistance. The magnetic circuit diagram is as follows: Figure 8 As shown, where J is the coil and its equivalent magnetic circuit model is as follows Figure 9 As shown, K is the air gap reluctance of the inner and outer magnetic ring end faces of the main circuit, L is the air gap leakage reluctance of the rotor and stator inner magnetic poles, M is the air gap reluctance of the outer magnetic pole main air gap parallel circuit, and N is the air gap reluctance of the edge circuit. Based on this, the total reluctance of the magnetic circuit considering the edge effect is calculated, which is specifically achieved through the following formula:

[0171] ;

[0172] in, represents the total magnetic resistance of the magnetic circuit, R i and R o is the reluctance at the main air gap, R 2 is the leakage magnetic resistance between the outer magnetic pole and the thrust plate, R 1 is the magnetic resistance at the air gap between the rotor and the stator, R ii is the magnetic flux leakage inside the inner pole, R io The magnetic flux leakage outside the inner magnetic pole is R oi is the magnetic flux leakage inside the outer magnetic pole, R oo It is the magnetic flux leakage outside the outer magnetic pole;

[0173] Step 2.2: Calculate the bearing capacity of the axial magnetic bearing based on the linearized single-degree-of-freedom electromagnetic force formula The formula is implemented by the following formula:

[0174] ;

[0175] ;

[0176] Where S represents the area of ​​the magnetic pole end including the edge flux range, is the total magnetic flux of the magnetic circuit, It is the main magnetic flux through the stator inner and outer poles in series with the thrust plate and the main air gap on the inner end face. It is the main magnetic flux through the stator inner and outer poles in series with the thrust plate and the main air gap on the outer end face. 、 、 、 is the fringe flux flowing through the stator poles and in parallel with the main air gaps between the two magnetic pole end faces, The magnetic flux passes through the inner magnetic pole of the stator and is connected in series with the adjacent rotating shaft, in parallel with the inner end surface working air gap and in series with the outer end surface working air gap. is the magnetic flux passing through the thrust plate and connected in parallel with the main air gap of the outer magnetic pole;

[0177] Step 2.3: Load-bearing capacity of axial magnetic bearings The formula is simplified to obtain the final bearing capacity of the axial magnetic bearing The expression of is specifically expressed by the following formula:

[0178] ;

[0179] in, is the extreme magnetic pole area including the edge flux range at the inner magnetic pole, They are the extreme pole areas at the outer pole including the edge flux range.

[0180] Step 3: Load-carrying capacity of radial magnetic bearings based on fruit fly algorithm and genetic algorithm The expression and final bearing capacity of the axial magnetic bearing The expression of is used to determine the parameters of the natural gas pressure differential generator with bilateral dual axial magnetic bearings;

[0181] The radial magnetic bearing stator is constructed by stacking amorphous alloy and silicon steel stator sheets in a 1:1 ratio, with axial spacing, and placing silicon steel at both ends of the stator. The axial magnetic bearing stator is made of conventional electrical pure iron.

[0182] Step 3.1: Load-carrying capacity based on radial magnetic bearings , setting a first objective function and a first constraint condition, optimizing the radial magnetic bearing structural parameters based on the fruit fly algorithm and the first objective function and the first constraint condition, and obtaining optimized radial magnetic bearing structural parameters;

[0183] Among them, the optimization goal is to increase the bearing capacity of the radial magnetic bearing and reduce the axial length and volume of the radial magnetic bearing.

[0184] Among them, the radial magnetic bearing structural parameters E 1 is represented by:

[0185] ;

[0186] in, is the stator pole width, is the stator slot width, is the rotor yoke width, is the stator yoke width, is the rotor outer diameter, is the stator pole height, is the axial width of the radial magnetic bearing, Indicates the radian of the stator magnetic extreme end face;

[0187] Wherein, the first objective function is expressed as:

[0188] ;

[0189] in, is the pole width, is the air gap circumferential position of the magnetic pole center, i max is the maximum current, s represents the area of ​​the magnetic pole end face including the edge flux range, represents the axial volume;

[0190] In order to make the magnetic bearing work in the linear region, the maximum magnetic flux density in the magnetic bearing stator and rotor magnetic circuits It should be less than the middle value of the linear section of the magnetization curve of the soft magnetic material used. Therefore, the maximum permissible magnetic flux density is limited to 1.4T.

[0191] In addition, the structural dimensions of the optimized radial magnetic bearing should comply with geometric rules and design experience. Therefore, the first constraint condition is expressed as:

[0192] ;

[0193] in, B Indicates the maximum magnetic flux density.

[0194] In the specific implementation process, based on the above optimization scheme, the optimized radial magnetic bearing structural parameters are obtained, as shown in Table 1.

[0195] Table 1 Optimized radial magnetic bearing structural parameters

[0196] name Numerical <![CDATA[Stator pole width w c / mm]]> 24.5 <![CDATA[Stator slot width w d / mm]]> 46 <![CDATA[Width of rotor yoke w r / mm]]> 33 <![CDATA[Stator yoke width w e / mm]]> 22 <![CDATA[Maximum current i max / A]]> 5 <![CDATA[Outer diameter of rotor R r1 / mm]]> 48 Stator pole height / mm 17.5 Axial width of radial magnetic bearing / mm 50.5 Stator magnetic pole end face radian / deg 40 Air gap length / mm 0.5

[0197] Step 3.2: Based on the final axial magnetic bearing capacity , set the second objective function and the second constraint condition, optimize the axial magnetic bearing structural parameters based on the genetic algorithm, the second objective function and the second constraint condition, and obtain the optimized axial magnetic bearing structural parameters.

[0198] Among them, the axial magnetic bearing structural parameters E 2 is expressed as:

[0199] E 2={r 0, r 1, r 2, r 3, r 4, r 5, r 6, h 1, h 2, h 3, h 4};

[0200] in, r 0 is the rotor radius, r 1 is the inner radius of the stator, r 2 is the outer radius of the stator inner magnetic pole, r 3 is the inner radius of the stator outer magnetic pole, r 4 is the radius of the stator outer magnetic pole, r 5 is the outer radius of the stator slot, r 6 is the outer radius of the stator, h 1 is the axial length of the stator, h 2 is the axial length of the wire slot, h 3 is the axial thickness of the stator yoke, h 4 is the axial length of the stator outer magnetic pole;

[0201] Wherein, the second objective function is expressed as:

[0202] ;

[0203] in, Indicates the dimensions of the axial magnetic bearing, and Expressed as:

[0204] ;

[0205] According to the functional relationship between the structural parameters of the axial electromagnetic bearing, the second constraint used in the optimization process is expressed as:

[0206] ;

[0207] in, is the maximum linear flux density of the soft magnetic material, is the coil wire diameter, is a coefficient determined based on experience;

[0208] The active magnetic bearing-rotor system utilizes a bilateral, dual-axial magnetic bearing structure. The natural gas differential pressure power generation equipment requires approximately 7.5 kN of axial thrust, so the design load capacity of the axial magnetic bearing is set at 4 kN. The design requirements for the axial magnetic bearing's axial load capacity, air gap length, and other parameters are shown in Table 2.

[0209] Table 2 Design requirements for axial load capacity, air gap length and other parameters of axial electromagnetic bearings

[0210] name Numerical <![CDATA[Axial bearing capacity F a / N]]> 4000 <![CDATA[Axial air gap length g z / mm]]> 0.5 <![CDATA[Coil wire diameter d m / mm]]> 1.1 Maximum linear speed of thrust plate m / s 350 Maximum linear flux density of soft magnetic materials / T 1.4

[0211] In the specific implementation process, based on the above optimization scheme, the optimized axial magnetic bearing structural parameters are obtained, as shown in Table 3.

[0212] Table 3 Optimized axial magnetic bearing structural parameters

[0213] name Numerical <![CDATA[Rotor radius r 0 / mm]]> 40 <![CDATA[Inner radius of stator r 1 / mm]]> 46 <![CDATA[Outer radius of inner magnetic pole of stator r 2 / mm]]> 60.6 <![CDATA[Inner radius of the stator outer magnetic pole r 3 / mm]]> 71.5 <![CDATA[Radius of the outer stator magnetic pole r 4 / mm]]> 80 <![CDATA[Stator outer radius r 6 / mm]]> 99.3 <![CDATA[Axial length of stator h 1 / mm]]> 88.8 <![CDATA[Outer radius of stator slot r 5 / mm]]> 28.9 <![CDATA[Axial length of wire duct h 2 / mm]]> 50.5 <![CDATA[Axial thickness of stator yoke h 3 / mm]]> 6.9 <![CDATA[Axial length of the outer stator magnetic pole h 4 / mm]]> 27.9 Coil turns 350

[0214] The optimized radial magnetic bearing structural parameters and the optimized axial magnetic bearing structural parameters constitute the parameters of the bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator.

[0215] Step 4: Based on the parameters of the bilateral dual-axial magnetic bearing natural gas pressure differential generator, adjust the structure of the bilateral dual-axial magnetic bearing natural gas pressure differential generator to obtain the final bilateral dual-axial magnetic bearing natural gas pressure differential generator.

[0216] The present invention designs an active magnetic bearing-rotor system with an axially symmetrical layout and configures multiple bearings to ensure operation.

[0217] The radial magnetic bearing adopts an 8-pole NSSN structure with different polarity. The load-bearing capacity is calculated and the parameters are optimized by using the distributed magnetic circuit method. The axial magnetic bearing design considers the edge effect to calculate the relevant parameters.

[0218] In terms of electromagnetic parameter optimization, a stator material composed of laminated amorphous alloy and silicon steel is used, and the fruit fly algorithm and genetic algorithm are used to optimize the radial and axial magnetic bearing structural parameters respectively.

[0219] This equipment effectively solves the problem of high axial thrust, improves system performance, reduces equipment size and weight, and lowers costs. It performs well under high speed and high axial load conditions and has good application prospects.

[0220] The present invention effectively solves the stability problem of natural gas pressure differential power generation equipment under high axial thrust through the design structure of the bilateral dual-axial magnetic suspension bearing natural gas pressure differential generator, and improves the system's load-bearing capacity and operating efficiency.

[0221] The optimized radial and axial magnetic bearing structural parameters further improve the performance of the magnetic bearing, reduce the size and weight of the equipment, and lower the manufacturing cost.

[0222] The use of hybrid stator materials and optimized electromagnetic parameter design improves the operating efficiency and reliability of the magnetic bearing and extends its service life.

[0223] The bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator of the present invention exhibits excellent performance under high-speed and high-axial load conditions and has broad application prospects.

[0224] The above description is merely an illustration of the preferred embodiments of the present disclosure and the technical principles employed. Those skilled in the art should understand that the scope of the invention encompassed by the embodiments of the present disclosure is not limited to technical solutions formed by specific combinations of the aforementioned technical features. It also encompasses other technical solutions formed by any combination of the aforementioned technical features or their equivalents, without departing from the aforementioned inventive concept. For example, a technical solution formed by replacing the aforementioned features with (but not limited to) technical features with similar functions disclosed in the embodiments of the present disclosure.

Claims

1. Double-sided dual-axial magnetic bearing natural gas pressure difference generator, characterized in that: The bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator includes an axial air inlet, an axial air outlet, a flow channel, a fairing, a turbine impeller, a stator, a magnetic suspension bearing mechanism and a body shell; The bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator is provided with an axial air inlet at the input end and an axial air outlet at the output end; The magnetic suspension bearing mechanism includes a rotor and two bearing sub-mechanisms, each of which includes an axial magnetic bearing, a radial magnetic bearing, a protective bearing, and a thrust plate. The two bearing sub-mechanisms are installed at both ends of the rotor, and the thrust plate is fixed to the rotor by welding. The protective bearing, axial magnetic bearing, and radial magnetic bearing are sleeved on the rotor. From the center of the rotor to the two ends, the radial magnetic bearing, axial magnetic bearing, and protective bearing are respectively included, and the thrust plate is located on the inner side of the axial magnetic bearing; a stator is provided between the two bearing sub-mechanisms, and the stator is fixed to the body shell; A fairing is provided on both ends of the magnetic bearing mechanism. The axial magnetic bearing, radial magnetic bearing, protective bearing and thrust plate are located inside the fairing. The fairing is provided with 8 flow holes and is fixed to the body shell. The turbine impeller is fixed to the rotor by interlocking. The flow channel includes a first flow channel and a second flow channel. The first flow channel is a flow channel passing through the flow hole of the fairing and passing through the inside of the fairing. The second flow channel is a flow channel between the outside of the fairing and the inside of the body shell.

2. A method for determining parameters of a double-sided dual-axial magnetic bearing natural gas pressure differential generator, based on the double-sided dual-axial magnetic bearing natural gas pressure differential generator according to claim 1, characterized in that: include: Step 1: Calculate the air gap flux density of the magnetic circuit nodes of the radial magnetic bearing, and then obtain the expression of the bearing capacity of the radial magnetic bearing based on the air gap flux density; Step 2: Calculate the total magnetic resistance of the magnetic circuit considering the edge effect, and then determine the final expression of the load-bearing capacity of the axial magnetic bearing; Step 3: Load-carrying capacity of radial magnetic bearings based on fruit fly algorithm and genetic algorithm The expression and final bearing capacity of the axial magnetic bearing The expression of is used to determine the parameters of the natural gas pressure differential generator with bilateral dual axial magnetic bearings; Step 4: Based on the parameters of the bilateral dual-axial magnetic bearing natural gas pressure differential generator, adjust the structure of the bilateral dual-axial magnetic bearing natural gas pressure differential generator to obtain the final bilateral dual-axial magnetic bearing natural gas pressure differential generator.

3. The method for determining parameters of a bilateral dual-axial magnetic bearing natural gas pressure differential generator according to claim 2 is characterized in that: Step 1 specifically includes: Step 1.1: Calculate the magnetic circuit nodes of the radial magnetic bearing without considering magnetic circuit saturation i Air gap flux density at , which is specifically achieved through the following formula: ； in, represents the vacuum permeability, For nodes The magnetomotive force at The magnetic pole center node i The circumferential position of the air gap, Circumferential position The air gap length at Among them, when the rotor is eccentric, Calculated by the following formula: ； in, is the eccentricity, is the eccentric angle, is the air gap length between the rotor and the stator when the rotor is in equilibrium position; Among them, the node Magnetomotive force Calculated by the following formula: ； Where N represents the number of winding turns, Node The control current at represents the bias current; Step 1.2: Set the initial iteration number to 0, and initialize the air gap magnetic flux of each node at the initial iteration number. Add 1 to the initial iteration number as the current iteration number j, and use the air gap magnetic flux calculated in step 1.1 as the air gap magnetic flux at the current iteration number. Step 1.3: According to the air gap magnetic flux density at the current iteration number Compute nodes The stator pole flux density at , which is specifically achieved through the following formula: ； in, is the magnetic flux leakage compensation coefficient; Compute nodes The magnetic flux density of the rotor yoke , which is specifically achieved through the following formula: ； in, For nodes The air gap magnetic density at is the effective air gap width, For nodes The magnetic flux density of the rotor yoke at is the rotor yoke width, is the air gap flux density at node 1, The magnetic flux density of the rotor yoke at node 1; Step 1.4: Compute Node The magnetic flux density of the stator yoke , which is specifically achieved through the following formula: ； in, For nodes The stator pole flux density at , For nodes The magnetic flux density of the stator yoke at is the stator pole width, is the stator yoke width, is the stator pole flux density at node 1, is the magnetic flux density of the stator yoke at node 1; Step 1.5: Iteratively calculate the total magnetomotive force based on the magnetic field strength and effective length of each loop segment , which is specifically achieved through the following formula: ； in, The magnetic pole center node The air gap length at the circumferential position of the air gap, For nodes The magnetic field strength at the stator pole is For nodes i The magnetic field strength of the rotor yoke at For nodes i The magnetic field strength of the stator yoke at is the effective length of each stator pole, is the effective length of each rotor yoke, is the effective length of each stator yoke; Computation loop at node i Magnetomotive force , which is specifically achieved through the following formula: ； in, For nodes The magnetomotive force at is the magnetomotive force at node 1, is the magnetomotive force at node 8; Step 1.6: Calculate the loop at the node i Magnetomotive force error at , which is specifically achieved through the following formula: ； The total magnetomotive force error of all circuits is then calculated as shown in the following formula: ； Step 1.7: Determine whether the total magnetomotive force error is greater than the preset accuracy requirement value. If the total magnetomotive force error is not greater than the preset accuracy requirement value, the air gap magnetic flux density at the current iteration number is used as the final air gap magnetic flux density. , execute step 1.

9. If the total magnetomotive force error is greater than the preset accuracy requirement value, execute step 1.8; Step 1.8: Correct the air gap flux density using the following formula: ； in, is the empirical coefficient, Indicates the node under the current iteration number j after correction i The air gap flux density at represents the air gap flux density at node 8 in the j-1th iteration, represents the magnetomotive force error of the loop at node 8; The current iteration number is increased by one, As the new air gap flux density at the current iteration number , return to step 1.3; Step 1.9: Calculate the circumferential position using the one-dimensional relative permeability function Air gap flux density , which is specifically achieved through the following formula: ； in, for The first derivative of ; Step 1.10: Based on the linearized single-degree-of-freedom electromagnetic force formula, obtain the bearing capacity of the radial magnetic bearing The expression is realized by the following formula: ； ； ； in, is the horizontal component of force, is the vertical component of force, is the effective area of ​​the magnetic pole.

4. The method for determining parameters of a bilateral dual-axial magnetic bearing natural gas pressure differential generator according to claim 3 is characterized in that: The linearized single-degree-of-freedom electromagnetic force formula described in step 1.10 is expressed as: ； in, is a single degree of freedom electromagnetic force , is the vacuum permeability, is the number of winding turns, is the cross-sectional area of ​​the air gap, is the rotor displacement, is the bias current, To control the current, is the rated operating point position, α is the force and angle of the magnetic pole acting on the rotor.

5. The method for determining parameters of a bilateral dual-axial magnetic bearing natural gas pressure differential generator according to claim 2 is characterized in that: Step 2 specifically includes: Step 2.1: Ignore the vibration of the thrust plate. The magnetic field of the axial electromagnetic bearing is a static field, and there is no eddy current in the rotor core. Ignore the magnetic resistance of the stator and rotor cores. Only consider the air gap magnetic resistance. Calculate the total magnetic resistance of the magnetic circuit taking into account the edge effect. This is achieved using the following formula: ； in, represents the total magnetic resistance of the magnetic circuit, R i and R o is the reluctance at the main air gap, R 2 is the leakage magnetic resistance between the outer magnetic pole and the thrust plate, R 1 is the magnetic resistance at the air gap between the rotor and the stator, R ii is the magnetic flux leakage inside the inner pole, R io The magnetic flux leakage outside the inner magnetic pole is R oi is the magnetic flux leakage inside the outer magnetic pole, R oo It is the magnetic flux leakage outside the outer magnetic pole; Step 2.2: Calculate the bearing capacity of the axial magnetic bearing based on the linearized single-degree-of-freedom electromagnetic force formula The formula is implemented by the following formula: ； ； Where S represents the area of ​​the magnetic pole end including the edge flux range, is the total magnetic flux of the magnetic circuit, It is the main magnetic flux through the stator inner and outer poles in series with the thrust plate and the main air gap on the inner end face. It is the main magnetic flux through the stator inner and outer poles in series with the thrust plate and the main air gap on the outer end face. 、 、 、 is the fringe flux flowing through the stator poles and in parallel with the main air gaps between the two magnetic pole end faces, The magnetic flux passes through the inner magnetic pole of the stator and is connected in series with the adjacent rotating shaft, in parallel with the inner end surface working air gap and in series with the outer end surface working air gap. is the magnetic flux passing through the thrust plate and connected in parallel with the main air gap of the outer magnetic pole; Step 2.3: Load-bearing capacity of axial magnetic bearings The formula is simplified to obtain the final bearing capacity of the axial magnetic bearing The expression of is specifically expressed by the following formula: ； in, is the extreme magnetic pole area including the edge flux range at the inner magnetic pole, They are the extreme pole areas at the outer pole including the edge flux range.

6. The method for determining parameters of a bilateral dual-axial magnetic bearing natural gas pressure differential generator according to claim 2 is characterized in that: Step 3 specifically includes: Step 3.1: Load-carrying capacity based on radial magnetic bearings , setting a first objective function and a first constraint condition, optimizing the radial magnetic bearing structural parameters based on the fruit fly algorithm and the first objective function and the first constraint condition, and obtaining optimized radial magnetic bearing structural parameters; Step 3.2: Based on the final axial magnetic bearing capacity , set the second objective function and the second constraint condition, optimize the axial magnetic bearing structural parameters based on the genetic algorithm, the second objective function and the second constraint condition, and obtain the optimized axial magnetic bearing structural parameters.

7. The method for determining parameters of a bilateral dual-axial magnetic bearing natural gas pressure differential generator according to claim 6 is characterized in that: Structural parameters of the radial magnetic bearing described in step 3.1 E 1 is represented by: ； in, is the stator pole width, is the stator slot width, is the rotor yoke width, is the stator yoke width, is the rotor outer diameter, is the stator pole height, is the axial width of the radial magnetic bearing, Indicates the radian of the stator magnetic extreme end face; Wherein, the first objective function is expressed as: ； in, is the pole width, is the air gap circumferential position of the magnetic pole center, i max is the maximum current, s represents the area of ​​the magnetic pole end face including the edge flux range, represents the axial volume; The first constraint condition is expressed as: ； in, B Indicates the maximum magnetic flux density.

8. The method for determining parameters of a natural gas pressure differential generator with bilateral dual-axial magnetic bearings according to claim 6 is characterized in that: Axial magnetic bearing structural parameters described in step 3.2 E 2 is expressed as: E 2={ r 0, r 1, r 2, r 3, r 4, r 5, r 6, h 1, h 2, h 3, h 4}； in, r 0 is the rotor radius, r 1 is the inner radius of the stator, r 2 is the outer radius of the stator inner magnetic pole, r 3 is the inner radius of the stator outer magnetic pole, r 4 is the radius of the stator outer magnetic pole, r 5 is the outer radius of the stator slot, r 6 is the outer radius of the stator, h 1 is the axial length of the stator, h 2 is the axial length of the wire slot, h 3 is the axial thickness of the stator yoke, h 4 is the axial length of the stator outer magnetic pole; Wherein, the second objective function is expressed as: ； in, Indicates the dimensions of the axial magnetic bearing, and Expressed as: ； The second constraint condition is expressed as: ； in, is the maximum linear flux density of the soft magnetic material, is the coil wire diameter, is a coefficient determined based on experience; The optimized radial magnetic bearing structural parameters and the optimized axial magnetic bearing structural parameters constitute the parameters of the bilateral dual-axial magnetic suspension bearing natural gas pressure difference generator.

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