Displacement control method and system for magnetic fluid double-suspension bearing with constant-flow oil supply

Abstract

The invention provides a method and a system for controlling the displacement of a magnetic-liquid double-suspension bearing with constant-flow oil supply, and relates to the technical field of magnetic-liquid double-suspension bearings, the method provided by the invention comprises the following steps: determining a magnetic-liquid proportionality coefficient, an initial flow and a current, acquiring a rotor state signal by a PID controller, controlling an output flow and changing the static pressure of a second support cavity; the electromagnetic force is changed, so that the rotor rotates back to the central position. The system provided by the invention comprises a static pressure control subsystem and an electromagnetic closed-loop control subsystem which are matched with each other so as to determine a magnetic liquid proportionality coefficient, form a control system taking static pressure support as a main part and electromagnetic suspension as an auxiliary part, and form adjustment of an initial balance state and rapid adjustment of external load interference. The system can adaptively adjust the flow and the current, thereby adjusting the static pressure and the electromagnetic force, ensuring the balance of the rotor under the action of an external load, omitting high-precision and easily-damaged parts of the displacement sensor, and being suitable for high-speed and high-precision equipment.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic fluid double magnetic bearings, and particularly relates to a displacement control method and system for a magnetic fluid double magnetic bearing with constant flow oil supply. Background Art

[0002] The magnetic fluid double magnetic bearing is a new type of magnetic bearing that mainly relies on electromagnetic suspension and supplemented by hydrostatic support. It can additionally increase the hydrostatic support force without affecting the electromagnetic suspension force, effectively improving the bearing operation stability and its service life. When the magnetic fluid double magnetic bearing system starts, eight hydraulic pipelines evenly distributed circumferentially on the radial stator of the bearing need to provide oil to provide hydrostatic support for the rotating shaft, and at the same time, two pipelines located on the front and rear axial stators provide oil to control the axial thrust work of the bearing.

[0003] In the existing magnetic fluid double magnetic bearing system, a displacement sensor is installed outside the rotating shaft to monitor the axis trajectory in real time. When the rotating shaft deviates, the data measured by the displacement sensor is returned to the host computer and after calculation, new electromagnetic force and static pressure are given again to make the rotating shaft return to the equilibrium position. This also results in a long initial debugging and response time during the operation of the bearing system. At the same time, since the magnetic fluid double magnetic system needs to debug eight hydraulic pipelines evenly distributed circumferentially on the radial stator respectively when starting, the process is complex and the price of the displacement sensor is expensive compared with other sensors. Various factors lead to a long response time and high installation cost of the magnetic fluid double magnetic bearing system, affecting the work efficiency. Summary of the Invention

[0004] In order to solve the above deficiencies of the prior art, the purpose of the present invention is to provide a displacement control method and system for a magnetic fluid double magnetic bearing with constant flow oil supply. By introducing a hydrostatic pressure control subsystem and an electromagnetic closed-loop control subsystem, precise control of the constant flow oil supply for the displacement of the bearing rotor is achieved. The method provided by the present invention adjusts the flow rate and current in real time during the movement of the rotor, effectively coping with the dynamic changes of the external load, greatly improving the suspension stability of the bearing and the reliability of the system operation. In addition, by optimizing the sensor layout and pole arrangement, the response speed and robustness of the system are enhanced, providing key technical support for the application of magnetic fluid double magnetic bearings in high-speed and high-precision occasions.

[0005] Specifically, on the one hand, the present invention provides a displacement control method for a magnetic fluid double magnetic bearing with constant flow oil supply, which includes the following steps:

[0006] S1: When in the initial no-load state, calculate the mechanical equilibrium equation of the single-degree-of-freedom magnetic fluid double magnetic bearing rotor to determine the magnetic fluid proportional coefficient, initial flow rate, and initial current;

[0007] S2: During the movement, the first PID controller and the second PID controller respectively collect the rotor state signals of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing and form real-time calculation results;

[0008] S3: Transmit the real-time calculation results to the hydrostatic pressure control subsystem and the electromagnetic closed-loop control subsystem;

[0009] S4: The hydrostatic pressure control subsystem controls the flow parameters of the hydrostatic pressure support subsystem of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing, and changes the static pressures of the first support chamber and the second support chamber;

[0010] S5: When there is no external load, the electromagnetic closed-loop control subsystem controls the current parameters of the electromagnetic support subsystem of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing to change the electromagnetic force;

[0011] S6: When under the action of an external load, the state of the rotor of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing deviates. The hydrostatic pressure control subsystem collects signals, and the first PID controller calculates and outputs a current signal to control the magnitude of the electromagnetic force, and the second PID controller calculates and outputs a current signal to control the magnitude of the static pressure, so that the rotor of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing rotates back to the central position. At the same time, the system steady-state output parameters of the external load F and the flow rate q0 - Δq2 of the first support chamber, the flow rate q0 + Δq2 of the second support chamber, the current i0 - Δi2 of the first support chamber unit, and the current i0 + Δi2 of the second support chamber unit are obtained.

[0012] Preferably, in step S6, the relational expressions for constructing the first PID controller and the second PID controller are as follows:

[0013]

[0014] In the formula, F DS2 is the electromagnetic force of the first support chamber unit, F DX2 is the electromagnetic force of the second support chamber unit, and θ is the included angle between the center line of the first support chamber and the center line of the rotor of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing.

[0015] Preferably, in step S1, when the rotor of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing is in the initial unloaded state, it is jointly supported by the hydrostatic pressure support subsystem and the electromagnetic support subsystem. At this time, the magneto-hydrodynamic ratio coefficient is determined to be 1, the initial flow rates are determined to be q0 - Δq1 and q0 + Δq1, and the initial currents are determined to be i0 - Δi1 and i0 + Δi1, where q0 is the system flow rate, Δq1 is the initial adjustment flow rate, i0 is the bias current, and Δi1 is the initial adjustment current.

[0016] Preferably, in step S1, the calculation method of the mechanical balance equation of the rotor of the single-degree-of-freedom magneto-hydrodynamic double magnetic suspension bearing includes the following steps:

[0017] S11: In the initial equilibrium state, the static pressure support forces of the first support cavity and the second support cavity are calculated to be F YS1 and F YX1 , and their relationship is as follows:

[0018]

[0019] S12: Calculate the electromagnetic force according to the magneto - liquid proportionality coefficient, and obtain the electromagnetic force F DS1 of the first support cavity unit and the electromagnetic force F DX1 of the second support cavity unit. The relationships they satisfy are as follows:

[0020]

[0021] In the formula, F DS1 is the electromagnetic force of the first support cavity unit, and F DX1 is the electromagnetic force of the second support cavity unit.

[0022] Preferably, in step S6, the calculation method of the system steady - state output parameters includes the following steps:

[0023] S61: When there is an external disturbance F 外 acting, the pressures of the first support cavity and the second support cavity change. Calculate the liquid resistance R1 of the first support cavity, the liquid resistance R2 of the second support cavity, and the external load F;

[0024] S62: Calculate the electromagnetic force according to the magneto - liquid proportionality coefficient, and obtain the electromagnetic force F DS2 of the first support cavity unit and the electromagnetic force F DX2 of the second support cavity unit under the steady state of the system.

[0025] On the other hand, the present invention provides a displacement control system for a magneto - liquid double - magnetic - suspension bearing with constant - flow oil supply, which includes a static pressure control subsystem, an electromagnetic closed - loop control subsystem, and a single - degree - of - freedom magneto - liquid double - magnetic - suspension bearing.

[0026] The static pressure control subsystem includes an oil tank, a filter, a servo hydraulic pump, an overflow valve, a check valve, a first mass flow controller, a first pressure sensor, a second mass flow controller, and a second pressure sensor. The filter is connected to the oil tank and the servo hydraulic pump. The overflow valve is connected to the oil tank and the servo hydraulic pump. The check valve is connected to the overflow valve, the first mass flow controller, and the second mass flow controller. The first mass flow controller is connected to the first pressure sensor and the single - degree - of - freedom magneto - liquid double - magnetic - suspension bearing. The second mass flow controller is connected to the second pressure sensor and the single - degree - of - freedom magneto - liquid double - magnetic - suspension bearing.

[0027] The electromagnetic closed-loop control subsystem includes a first PID controller, a second PID controller, a first power amplifier, a second power amplifier, a first current sensor, a second current sensor, a first D / A converter, a first A / D converter, a second D / A converter, a second A / D converter, a first electromagnetic coil, and a second electromagnetic coil. The first D / A converter is connected to a first mass flow controller and a second mass flow controller, and is connected to the first PID controller. The first A / D converter is connected to the first PID controller and the second PID controller, and is connected to a first pressure sensor, a first mass flow controller, a second pressure sensor, and a second mass flow controller. The second D / A converter is connected to the second PID controller, the first power amplifier, and the second power amplifier. The second A / D converter is connected to the second PID controller, the first current sensor, and the second current sensor. The first power amplifier is respectively connected to the first current sensor and the first electromagnetic coil, and the second power amplifier is respectively connected to the second current sensor and the second electromagnetic coil.

[0028] Preferably, a single-degree-of-freedom magneto-hydrodynamic bearing is provided with a single-degree-of-freedom magneto-hydrodynamic bearing rotor. A first support cavity unit is provided at the first end of the single-degree-of-freedom magneto-hydrodynamic bearing rotor, and a second support cavity unit is provided at the second end of the single-degree-of-freedom magneto-hydrodynamic bearing rotor.

[0029] Furthermore, preferably, radial magnetic poles are uniformly arranged in the first support cavity unit and the second support cavity unit. Every two adjacent radial magnetic poles form a support unit. Each pair of radial magnetic poles is arranged on the same installation plane and the interval angle is 90°.

[0030] Preferably, a first electromagnetic coil is installed on the radial magnetic pole of the first support cavity unit, and a second electromagnetic coil is installed on the radial magnetic pole of the second support cavity unit.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. Compared with the original magneto-hydrodynamic bearing system, the present invention adopts a new detection and control method to make the response of the system faster.

[0033] 2. The new magneto-hydrodynamic bearing system of the present invention replaces the original displacement sensor and adds a mass flow controller, saving costs on the original basis.

[0034] 3. Compared with the original magneto-hydrodynamic bearing system, the present invention reduces the displacement sensor, so there is no need to worry about the damage of the externally installed displacement sensor in subsequent tests, reducing the subsequent maintenance cost. Description of the Drawings

[0035] Figure 1Flow chart of the displacement control method for the single-degree-of-freedom magnetic fluid double-suspension bearing of the present invention;

[0036] Figure 2 Flow chart of the displacement control system for the single-degree-of-freedom magnetic fluid double-suspension bearing without external disturbance of the present invention;

[0037] Figure 3 Flow chart of the displacement control system for the single-degree-of-freedom magnetic fluid double-suspension bearing under external disturbance of the present invention;

[0038] Figure 4 Schematic diagram of the magnetic fluid double-closed-loop composite regulation system for the single-degree-of-freedom magnetic fluid double-suspension bearing of the present invention;

[0039] Figure 5 Schematic diagram of the structure of the single-degree-of-freedom magnetic fluid double-suspension bearing of the present invention. Detailed implementation manners

[0040] Hereinafter, the implementation manners of the present invention will be described with reference to the accompanying drawings.

[0041] The technical solution adopted by the present invention is to provide a displacement control method for a magnetic fluid double-suspension bearing with constant flow oil supply, as Figure 1 and Figures 4 - 5 shown, including the following steps:

[0042] S1: When the rotor 3 of the single-degree-of-freedom magnetic fluid double-suspension bearing is in the initial unloaded state, calculate the mechanical equilibrium equation of the rotor 3 of the single-degree-of-freedom magnetic fluid double-suspension bearing to determine the magnetic fluid proportional coefficient, the initial flow rate, and the initial current.

[0043] S2: During the movement process, the first PID controller 19 and the second PID controller 20 respectively collect the state signals of the rotor 3 of the single-degree-of-freedom magnetic fluid double-suspension bearing and form real-time calculation results.

[0044] S3: The first PID controller 19 and the second PID controller 20 transmit the real-time calculation results to the hydrostatic pressure control subsystem 1 and the electromagnetic closed-loop control subsystem 2.

[0045] S4: The hydrostatic pressure control subsystem 1 controls the flow rate parameters of the hydrostatic pressure support subsystem 33 of the single-degree-of-freedom magnetic fluid double-suspension bearing 32 to change the static pressures of the first support chamber 4 and the second support chamber 5.

[0046] S5: When not affected by an external load, the electromagnetic closed-loop control subsystem 2 controls the current parameters of the electromagnetic support subsystem 34 of the single-degree-of-freedom magnetic fluid double-suspension bearing 32 to change the electromagnetic force.

[0047] S6: When subjected to an external load, the state of the single-degree-of-freedom magnetic fluid dual-suspension bearing rotor 3 shifts. The static pressure control subsystem 1 collects signals, and the first PID controller 19 calculates the output current signal to control the magnitude of the electromagnetic force. The second PID controller 20 calculates the output current signal to control the magnitude of the static pressure, thereby causing the single-degree-of-freedom magnetic fluid dual-suspension bearing rotor 3 to return to the center position. At the same time, the relationship between the external load F and the flow rate q0-Δq2 of the first support cavity 4, the flow rate q0+Δq2 of the second support cavity 5, the current i0-Δi2 of the first support cavity unit 29, and the current i0+Δi2 of the second support cavity unit 30 is obtained as follows:

[0048]

[0049] Where R is the initial fluid resistance, A is the bearing area of the support cavity, and F DS2 is the electromagnetic force of the first supporting cavity unit 29, F DX2 is the electromagnetic force of the second support cavity unit 30, i0-Δi2 is the current current of the first support cavity unit 29, i0+Δi2 is the current current of the second support cavity unit 30, q0-Δq2 is the current flow of the first support cavity 4, q0+Δq2 is the current flow of the second support cavity 5, θ is the angle between the centerline of the first support cavity 4 and the centerline of the single-degree-of-freedom magnetic fluid dual-suspension bearing rotor 3. Further, the first PID controller 19 and the second PID controller 20 are constructed according to the relationship obtained in step S6.

[0050] In step S1, when the single-degree-of-freedom magnetic fluid dual-suspension bearing rotor 3 is in an initial no-load state, it is jointly supported by the static pressure support subsystem 33 and the electromagnetic support subsystem 34. At this time, the magnetic fluid proportional coefficient is determined to be 1, the initial flow rate is determined to be q0-Δq1 and q0+Δq1, and the initial current is determined to be i0-Δi1 and i0+Δi1, where q0 is the system flow rate, Δq1 is the initial adjustment flow rate, i0 is the bias current, and Δi1 is the initial adjustment current.

[0051] In step S1, when the single-degree-of-freedom magnetic fluid dual-suspension bearing rotor 3 is in a balanced position, the gap between the first support cavity 4 and the single-degree-of-freedom magnetic fluid dual-suspension bearing rotor 3 is h0, and the relationship R=μ / Bh exists. 3 =p / q, where R is the system fluid resistance, B is the support coefficient of the support cavity, h is the gap between the first support cavity 4 and the single-degree-of-freedom magnetic fluid dual-suspension bearing rotor 3, μ is the oil viscosity, p is the support cavity pressure, and q is the support cavity flow rate.

[0052] When the static pressure control loop is determined, the electromagnetic regulation is determined accordingly. The flow rate output by the static pressure control subsystem 1 corresponds to the current change i output in the electromagnetic regulation. The hydraulic pressure F 液 The output flow rate q of the first mass flow controller 13 and the second mass flow controller 15 corresponds to the output flow rate q of the first mass flow controller 13 and the second mass flow controller 15.电 and F 液 Under the combined action of and F, the rotor turns back to the central position again.

[0053] In step S1, under no external load, the process of calibrating the equilibrium position of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3 is as follows: the self-weight is G, the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3 has no offset, the liquid film has an initial thickness h0, the system liquid resistances of the first support chamber 4 and the second support chamber 5 are equal, the static pressure and the electromagnetic force respectively bear half of the self-weight of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3. The calculation method of the mechanical equilibrium equation of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3 is as Figure 2 and Figures 4 - 5 shown, and it includes the following steps:

[0054] S11: In the equilibrium state, the magneto-hydrodynamic double-suspension bearing 32 uses the first mass flow sensor 13 and the second mass flow sensor 15 to regulate the flow parameters of the hydrostatic bearing system. At the initial moment, the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3 is in equilibrium. The flow rate of the first support chamber 4 is q0 - Δq1, and the flow rate of the second support chamber 5 is q0 + Δq1. According to the Navier-Stokes equation, the hydrostatic bearing forces of the first support chamber 4 and the second support chamber 5 are respectively F YS1 and F YX1 , and their relationship is:

[0055]

[0056] In the formula, θ is the included angle between the center line of the first support chamber 4 and the center line of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3, R is the initial liquid resistance, q0 - Δq1 is the flow rate of the first support chamber 4, q0 + Δq1 is the flow rate of the second support chamber 5, q0 is the system flow rate, Δq1 is the initial adjustment flow rate, and A is the bearing area of the support chamber.

[0057] S12: Calculate the electromagnetic force according to the magneto-hydrodynamic proportional coefficient, and obtain the electromagnetic force F DS1 of the first support chamber unit 29 and the electromagnetic force F DX1 of the second support chamber unit 30. The relationships they satisfy are as follows:

[0058]

[0059] In the formula, i0 - Δi1 is the current of the first support chamber unit 29, i0 + Δi1 is the current of the second support chamber unit 30, i0 is the bias current, Δi1 is the initial adjustment current, q0 is the system flow rate, Δq1 is the initial adjustment flow rate, R is the initial liquid resistance, and A is the bearing area of the support chamber.

[0060] At this time, the flow rate of the first support chamber 4 is q0 - Δq1, the flow rate of the second support chamber 5 is q0 + Δq1, the output current of the second PID controller 20 is 0, the driving current output by the first power amplifier 21 and the second power amplifier 22 is the reference current i0, the current of the first electromagnetic coil 6 is i0 + Δi1, the current of the second electromagnetic coil 7 is i0 - Δi1, the total electromagnetic support force is equal to the total static pressure support force, and is half of the initial weight of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3.

[0061] In step S6, when affected by an external load, the output parameters of the hydrostatic pressure control subsystem 1 and the electromagnetic closed-loop control subsystem 2 change, the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3 deviates from the central position, the liquid resistance of the first support chamber 4 becomes R1, the liquid resistance of the second support chamber 5 becomes R2, the pressures of the first support chamber 4 and the second support chamber 5 change, and the calculation method of the system steady-state output parameters is as Figure 3 and Figures 4 - 5 shown, and includes the following steps:

[0062] S61: When there is an external disturbance F 外 acting on the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3, the displacement of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3 changes, and at the same time, the pressures of the first support chamber 4 and the second support chamber 5 change.

[0063] The liquid resistances R1 of the first support chamber 4 and R2 of the second support chamber 5 are:

[0064]

[0065] In the formula, P1 is the pressure of the first support chamber 4, P2 is the pressure of the second support chamber 5, q0 is the system flow rate, Δq1 is the initial adjustment flow rate, q0 - Δq1 is the flow rate of the first support chamber 4, q0 + Δq1 is the flow rate of the second support chamber 5, R1 is the liquid resistance of the first support chamber 4, and R2 is the liquid resistance of the second support chamber 5.

[0066] At the same time, calculate the magnitude of the external load F:

[0067]

[0068] F = (P2 - P1)A - (F YX1 - F YS1 )

[0069] F = cosθ(R1 - R)A(q0 + Δq1) + cosθ(R - R2)A(q0 - Δq1)

[0070] In the formula, F YF is the current static pressure support force, G is the self-weight, F is the external load, P1 is the pressure of the first support chamber 4, P2 is the pressure of the second support chamber 5, A is the bearing area of the support chamber, F YS1 is the static pressure support force of the first support chamber 4, F YX1 is the static pressure support force of the second support chamber 5, θ is the included angle between the center line of the first support chamber 4 and the center line of the single-degree-of-freedom magneto-fluid double-suspension bearing rotor 3, R1 is the liquid resistance of the first support chamber 4, R2 is the liquid resistance of the second support chamber 5, q0 is the system flow rate, Δq1 is the initial adjustment flow rate, q0 - Δq1 is the flow rate of the first support chamber 4, and q0 + Δq1 is the flow rate of the second support chamber 5.

[0071] S62: Calculate the electromagnetic force according to the magneto-fluid proportionality coefficient to obtain the electromagnetic force F of the first support chamber unit 29 DS2 and the electromagnetic force F of the second support chamber unit 30 DX2 That is

[0072]

[0073] In the formula, R is the initial liquid resistance, A is the bearing area of the support chamber, F DS2 is the electromagnetic force of the first support chamber unit 29, F DX2 is the electromagnetic force of the second support chamber unit 30, i0 - Δi2 is the current of the first support chamber unit 29, i0 + Δi2 is the current of the second support chamber unit 30, q0 - Δq2 is the current flow rate of the first support chamber 4, q0 + Δq2 is the current flow rate of the second support chamber 5, and θ is the included angle between the center line of the first support chamber 4 and the center line of the single-degree-of-freedom magneto-fluid double-suspension bearing rotor 3.

[0074] When the single-degree-of-freedom magneto-fluid double-suspension bearing rotor 3 is under the action of an external load, the first PID controller 19 adjusts the flow rate of the first support chamber 4 to q0 - Δq2, the flow rate of the second support chamber 5 to q0 + Δq2, the current of the first electromagnetic coil 6 to i0 + Δi2, and the current of the second electromagnetic coil 7 to i0 - Δi2. At this time, the total electromagnetic support force is equal to the total static pressure support force and is half of the weight of the initial single-degree-of-freedom magneto-fluid double-suspension bearing rotor 3 and the external load F. Under the combined action of the static pressure and the electromagnetic force, the rotor returns to the central position again.

[0075] In the second aspect of the present invention, a magneto-fluid double-suspension bearing displacement control system with a constant flow rate oil supply is provided, as shown in Figure 4 and Figure 5As shown, it includes a static pressure control subsystem 1, an electromagnetic closed-loop control subsystem 2, a single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3, a first support cavity 4, a second support cavity 5, a first electromagnetic coil 6 and a second electromagnetic coil 7. The static pressure control subsystem 1 includes an oil tank 8, a filter 9, a servo hydraulic pump 10, a relief valve 11, a check valve 12, a first mass flow controller 13, a first pressure sensor 14, a second mass flow controller 15, a second pressure sensor 16 and the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3. The second end of the filter 9 is connected to the oil tank 8, the first end of the filter 9 is connected to the inlet of the servo hydraulic pump 10, the outlet of the servo hydraulic pump 10 is connected in parallel with the inlet of the relief valve 11, the outlet of the relief valve 11 is connected to the oil tank 8, the inlet of the relief valve 11 and the outlet of the servo hydraulic pump 10 are both connected to the second end of the check valve 12, the first end of the check valve 12 is respectively connected to the second port of the first mass flow controller 13 and the second port of the second mass flow controller 15, the first port of the first mass flow controller 13 is connected to the second interface of the first pressure sensor 14, and at the same time, the first port of the first mass flow controller 13 is connected to the first oil inlet 17 of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing 3. The first port of the second mass flow controller 15 is connected to the second interface of the second pressure sensor 16, and at the same time, the first port of the second mass flow controller 15 is connected to the second oil inlet 18 of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing 3.

[0076] The electromagnetic closed-loop control subsystem 2 includes a first PID controller 19, a second PID controller 20, a first power amplifier 21, a second power amplifier 22, a first current sensor 23, a second current sensor 24, a first D / A converter 25, a first A / D converter 26, a second D / A converter 27, and a second A / D converter 28. The second signal interface of the first D / A converter 25 is connected to the first signal interfaces of the first mass flow controller 13 and the second mass flow controller 15 through signal lines. The first signal interface of the first D / A converter 25 is connected to the second signal interface of the first PID controller 19. The first signal interface of the first A / D converter 25 is connected to the first signal interface of the first PID controller 19. At the same time, the first signal interface of the first A / D converter 26 is connected to the first signal interface of the second PID controller 20. The second signal interface of the first A / D converter 26 is respectively connected to the first signal interface of the first pressure sensor 14, the second signal interface of the first mass flow controller 13, the first signal interface of the second pressure sensor 16, and the second signal interface of the second mass flow controller 15. The first signal interface of the second D / A converter 27 is connected to the second signal interface of the second PID controller 20. The second signal interface of the second D / A converter 25 is respectively connected to the first signal interfaces of the first power amplifier 21 and the second power amplifier 22. The first signal interface of the second A / D converter 28 is connected to the first signal interface of the second PID controller 20. The second signal interface of the second A / D converter 28 is respectively connected to the first signal interfaces of the first current sensor 23 and the second current sensor 24. The second signal interface of the first power amplifier 21 is respectively connected to the second signal interface of the first current sensor 23 and the first electromagnetic coil 6. The second signal interface of the second power amplifier 22 is respectively connected to the second signal interface of the second current sensor 24 and the second electromagnetic coil 7.

[0077] A first support cavity unit 29 is installed at the first end of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3, and a second support cavity unit 30 is installed at the second end of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor 3. Radial magnetic poles 31 are uniformly arranged in the first support cavity unit 29 and the second support cavity unit 30. A first electromagnetic coil 6 is installed on the radial magnetic pole 31 of the first support cavity unit 29, and a second electromagnetic coil 7 is installed on the radial magnetic pole 31 of the second support cavity unit 30. Every two adjacent radial magnetic poles 31 form a support unit. Each pair of radial magnetic poles 31 is arranged on the same installation plane and the interval angle is 90°.

[0078] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A displacement control method for a magnetic fluid double-suspension bearing with constant flow rate oil supply, characterized in that: It includes the following steps: S1: When in the initial unloaded state, calculate the mechanical equilibrium equation of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor to determine the magneto-hydrodynamic proportionality coefficient, initial flow rate, and initial current; S2: During the movement process, the first PID controller and the second PID controller respectively collect the state signals of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor and form real-time calculation results; S3: Transmit the real-time calculation results to the hydrostatic pressure control subsystem and the electromagnetic closed-loop control subsystem; S4: The hydrostatic pressure control subsystem controls the flow rate parameters of the hydrostatic support subsystem of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing, changing the static pressures of the first support chamber and the second support chamber; S5: When not under external load, the electromagnetic closed-loop control subsystem controls the current parameters of the electromagnetic support subsystem of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing, changing the electromagnetic force; S6: When under external load, the state of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor shifts. The hydrostatic pressure control subsystem collects signals, and the first PID controller calculates and outputs a current signal to control the magnitude of the electromagnetic force, and the second PID controller calculates and outputs a current signal to control the magnitude of the static pressure, so that the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor returns to the central position. At the same time, the system steady-state output parameters of the external load F and the flow rate q0 - Δq2 of the first support chamber, the flow rate q0 + Δq2 of the second support chamber, the current i0 - Δi2 of the first support chamber unit, and the current i0 + Δi2 of the second support chamber unit are obtained.

2. The displacement control method of the magnetic fluid double-suspension bearing with constant flow rate oil supply according to claim 1, wherein: In step S6, the relational expressions for constructing the first PID controller and the second PID controller are: Where, F DS2 is the electromagnetic force of the first support cavity unit, F DX2 is the electromagnetic force of the second support cavity unit, and θ is the included angle between the center line of the first support cavity and the center line of the rotor of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing.

3. The displacement control method of the magnetic fluid double-suspension bearing with constant flow rate oil supply according to claim 1, characterized in that: In step S1, when the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor is in the initial unloaded state, it is jointly supported by the hydrostatic support subsystem and the electromagnetic support subsystem. The magneto-hydrodynamic proportionality coefficient is determined to be 1, the initial flow rates are determined to be q0 - Δq1 and q0 + Δq1, and the initial currents are determined to be i0 - Δi1 and i0 + Δi1, where q0 is the system flow rate, Δq1 is the initial adjustment flow rate, i0 is the bias current, and Δi1 is the initial adjustment current.

4. The displacement control method of the magnetic fluid double-suspension bearing with constant flow rate oil supply according to claim 1 or 3, characterized in that: In step S1, the calculation method of the mechanical equilibrium equation of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor includes the following steps: S11: In the initial equilibrium state, the static pressure support forces of the first support cavity and the second support cavity are calculated to be F YS1 and F YX1 , and their relationship is as follows: S12: Calculate the electromagnetic force according to the magneto-hydrodynamic proportionality coefficient to obtain the electromagnetic forces of the first support chamber unit and the second support chamber unit, and the relational expressions satisfied by each are as follows: Wherein, F DS1 is the electromagnetic force of the first support cavity unit, and F DX1 is the electromagnetic force of the second support cavity unit.

5. The displacement control method of the magnetic fluid double-suspension bearing with constant flow rate oil supply according to claim 2, characterized in that: In step S6, the calculation method of the system steady-state output parameters includes the following steps: S61: When there is an external disturbance F 外 acting, the pressures in the first support chamber and the second support chamber change, and the liquid resistance R1 of the first support chamber, the liquid resistance R2 of the second support chamber, and the external load F are calculated; S62: Calculate the electromagnetic force according to the magnetorheological fluid proportionality coefficient to obtain the electromagnetic force F of the first support cavity unit under the steady state of the system DS2 and the electromagnetic force F of the second support cavity unit DX2 .

6. A displacement control system for a magnetic fluid double-suspension bearing with constant flow oil supply for the constant flow oil supply magnetic fluid double-suspension bearing displacement control method according to any one of claims 1-5, characterized in that: It includes a hydrostatic pressure control subsystem, an electromagnetic closed-loop control subsystem, and a single-degree-of-freedom magneto-hydrodynamic double-suspension bearing. The hydrostatic pressure control subsystem includes an oil tank, a filter, a servo hydraulic pump, a relief valve, a check valve, a first mass flow controller, a first pressure sensor, a second mass flow controller, and a second pressure sensor. The filter is connected to the oil tank and the servo hydraulic pump. The relief valve is connected to the oil tank and the servo hydraulic pump. The check valve is connected to the relief valve, the first mass flow controller, and the second mass flow controller. The first mass flow controller is connected to the first pressure sensor and the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing. The second mass flow controller is connected to the second pressure sensor and the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing; The electromagnetic closed-loop control subsystem includes a first PID controller, a second PID controller, a first power amplifier, a second power amplifier, a first current sensor, a second current sensor, a first D / A converter, a first A / D converter, a second D / A converter, a second A / D converter, a first electromagnetic coil and a second electromagnetic coil. The first D / A converter is connected to a first mass flow controller and a second mass flow controller, and is connected to the first PID controller. The first A / D converter is connected to the first PID controller and the second PID controller, and is connected to a first pressure sensor, a first mass flow controller, a second pressure sensor and a second mass flow controller. The second D / A converter is connected to the second PID controller, the first power amplifier and the second power amplifier. The second A / D converter is connected to the second PID controller, the first current sensor and the second current sensor. The first power amplifier is respectively connected to the first current sensor and the first electromagnetic coil. The second power amplifier is respectively connected to the second current sensor and the second electromagnetic coil.

7. The displacement control system of the magnetic fluid double-suspension bearing with constant flow oil supply according to claim 6, wherein: The single-degree-of-freedom magneto-hydrodynamic double-suspension bearing is provided with a single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor. A first support cavity unit is arranged at the first end of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor. A second support cavity unit is arranged at the second end of the single-degree-of-freedom magneto-hydrodynamic double-suspension bearing rotor.

8. The displacement control system of the magnetic fluid double-suspension bearing with constant flow rate oil supply according to claim 7, characterized in that: Radial magnetic poles are uniformly arranged in the first support cavity unit and the second support cavity unit. Every two adjacent radial magnetic poles form a support unit. Each pair of radial magnetic poles is arranged on the same installation plane and the interval angle is 90°.

9. The displacement control system of the magnetic fluid double-suspension bearing with constant flow rate oil supply according to claim 8, characterized in that: A first electromagnetic coil is installed on the radial magnetic poles of the first support cavity unit. A second electromagnetic coil is installed on the radial magnetic poles of the second support cavity unit.

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