Suspended orthogonal coordinate system-based bearingless motor composite sensing detection method

Abstract

The invention discloses a bearingless motor composite sensing detection method based on a suspension orthogonal coordinate system, and belongs to the technical field of bearingless motor driving. According to the technology, an electric suspension orthogonal coordinate system of the bearingless motor is established, position assembly of four sensors based on the suspension orthogonal coordinate system is completed, voltage values of the four sensors at the current moment and stator current of the bearingless motor are sampled, and motor flux density values of the four sensors at the current moment are obtained through calculation; mathematical operation is carried out on the flux density sum and the flux density difference of two sensors spaced by 180 degrees on the two sets of machines, stator current effect decoupling is considered, the rotor rotation angle and the rotor radial displacement of the bearingless motor at the current moment are obtained, and therefore bearingless motor suspension and torque closed-loop control are completed; according to the invention, a suspension orthogonal coordinate system sensor position configuration mode is adopted and four sensors are utilized to realize composite detection of the rotation angle and the radial displacement of the bearingless motor rotor, so that the system cost is reduced while stable operation of the system is ensured.

Description

Technical Field

[0001] This invention relates to the field of bearingless motor drive technology, and in particular to a composite sensing and detection method for bearingless motors based on a suspended orthogonal coordinate system. Background Technology

[0002] Bearingless motors, due to their advantages of high sealing, no contact, and no wear, play an irreplaceable role in fields such as wafer cleaning in semiconductor manufacturing, solution stirring in chemical processes, and blood pumps for artificial hearts in medical devices. The core of a bearingless system is to adjust the excitation in the motor through displacement feedback to ensure stable levitation at the motor's center. This requires the use of displacement sensors to accurately capture precise information about the radial displacement of the motor rotor. However, the linearity, sensitivity, and resolution of displacement sensors are easily affected by temperature and electromagnetic noise, impacting the motor's levitation performance and limiting the widespread adoption of bearingless motors. Furthermore, the high cost of displacement sensors hinders the practical application of this type of motor.

[0003] The introduction of a suspension control system, while providing the aforementioned advantages to bearingless motors, also places extremely high demands on their sensing systems. Both the rotor's angular and radial displacements need to be detected, which undoubtedly increases the cost of bearingless motor systems significantly, especially radial displacement sensors, whose high cost is one of the main reasons limiting the industrial application of bearingless motors. Therefore, research into low-cost, reliable angular / radial displacement detection schemes for bearingless motors is of great significance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a composite sensing and detection method for bearingless motors based on a suspended orthogonal coordinate system. To address the problem of high cost of traditional sensing schemes for bearingless motors, the present invention adopts a sensor position configuration method based on a suspended orthogonal coordinate system, and uses only four sensors to achieve composite detection of rotor angle and radial displacement of the bearingless motor. This reduces system cost while ensuring stable system operation.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A composite sensing and detection method for bearingless motors based on a suspended orthogonal coordinate system is proposed. This method employs a sensor positioning configuration within a suspended orthogonal coordinate system and utilizes four sensors to achieve composite detection of the rotor angle and radial displacement of the bearingless motor. The implementation steps of this method are as follows:

[0007] Step S1: Establish an electric levitation orthogonal coordinate system for the bearingless motor and complete the assembly of the four sensor positions based on the levitation orthogonal coordinate system;

[0008] Step S2: Calculate the voltage values ​​of the four sensors and the stator current i of the bearingless motor at the current moment.M Samples are taken and the magnetic flux density values ​​of the motor at the four current sensors, B1, B2, B3, and B4, are calculated.

[0009] Step S3: Perform mathematical calculations on the magnetic flux density difference between two sensors located 180° apart on the two sets of mechanical parts to obtain the current rotor angle θ of the bearingless motor. e ;

[0010] Step S4: Perform mathematical calculations on the magnetic flux density sums at the two sensors that are 180° apart on the two sets of mechanical parts, and decouple them considering the stator current effect to obtain the decoupled magnetic flux density sum (B1+B3) at the two sensors. f (B2+B4) f Thus, the radial displacements x and y of the bearingless motor rotor at the current moment can be obtained;

[0011] Step S5, using the calculated rotor angle θ of the bearingless motor e And radial displacements x and y, to complete the suspension and torque closed-loop control of the bearingless motor;

[0012] Step S6: Repeat steps S2 to S5 to calculate the rotor angle θ of the bearingless motor in real time. e It controls radial displacements x and y, and performs bearingless motor suspension and torque closed-loop control.

[0013] Furthermore, the angle θ between the two coordinate axes of the suspended orthogonal coordinate system in step S1 and the mechanical orthogonal coordinate system... LO The number of pole pairs p of the levitation winding is determined by θ. LO =90 / p.

[0014] Furthermore, the sensor used to detect the magnetic flux density of the motor in step S1 can be any sensor capable of measuring magnetic flux density and meeting the assembly requirements.

[0015] Furthermore, in step S2, the stator current is sampled using a current sensor based on the Hall effect.

[0016] Furthermore, in step S3, the magnetic flux density difference at the two sensors, which are mechanically 180° apart, is only related to the rotor rotation angle and is not related to the rotor radial displacement.

[0017] Furthermore, in step S3, the rotor angle calculation adopts the arctangent of trigonometric functions or the phase-locked loop method, and the calculation formula is as follows:

[0018]

[0019] Among them, B1, B2, B3, and B4 are the magnetic flux density values ​​of the motor at the four sensors.

[0020] Furthermore, in step S4, the magnetic flux density at the two sensors, which are mechanically separated by 180°, is related to both the rotor angle and radial displacement. Based on the calculation of the rotor angle, the calculation of the rotor radial displacement is performed, and the calculation formula is as follows:

[0021]

[0022] Where, θ e Let θ be the rotor angle of the bearingless motor, x and y be the radial displacement of the bearingless motor, μ0 represent the free permeability, δ0 represent the eccentric equivalent air gap length of the bearingless motor rotor, and E represent the fundamental amplitude of the magnetomotive force. Represents the initial phase angle, the subscript f represents the magnetic flux density component contributed by the rotor excitation, and k r The displacement calculation coefficients are represented by B1, B2, B3, and B4, which are the motor magnetic flux density values ​​at the four sensors.

[0023] Furthermore, in step S4, the decoupling of the stator current effect is mainly the decoupling of the levitation current effect. The torque winding and the rotor have the same number of pole pairs, and the torque current is much smaller than the excitation current. Therefore, the effect of the torque current on the magnetic flux density detection is negligible.

[0024] Furthermore, in step S5, the bearingless motor suspension and torque closed-loop control scheme adopts a dual closed-loop control of the torque system (outer speed loop - inner current loop) and a dual closed-loop control of the suspension system (outer displacement loop - inner current loop).

[0025] Furthermore, the formulas for calculating the sum and difference of magnetic flux density at the two sets of sensors mechanically separated by 180° in steps S3 and S4 are as follows:

[0026]

[0027]

[0028] Where B1, B2, B3, and B4 are the magnetic flux density values ​​of the motor at the four sensors, and θ e Let θ be the rotor angle of the bearingless motor, x and y be the radial displacement of the bearingless motor, μ0 represent the free permeability, δ0 represent the eccentric equivalent air gap length of the bearingless motor rotor, and E represent the fundamental amplitude of the magnetomotive force. The initial phase angle is represented by the subscript f, which represents the magnetic flux density component contributed by the rotor excitation part, the subscript T, which represents the magnetic flux density component contributed by the stator current effective driving torque part, and the subscript L, which represents the magnetic flux density component contributed by the stator current levitation control part.

[0029] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0030] (1) The bearingless motor composite sensing and detection method based on the suspended orthogonal coordinate system provided by the present invention uses only four sensors to realize the composite detection of rotor angle and radial displacement, which simplifies the hardware structure and reduces the cost. The coordinate axis angle of the coordinate system is related to the number of pole pairs of the suspended winding, so that the sensor layout fits the electromagnetic characteristics of the motor and improves the accuracy of detection.

[0031] (2) The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system provided by the present invention can simultaneously complete the detection of rotor angle and radial displacement, avoiding the error and synchronization problem of independent detection by multiple sensors; the rotation angle is calculated by using magnetic flux density difference to eliminate radial displacement interference, and the accuracy is ensured by using trigonometric function arctangent or phase-locked loop method; the magnetic flux density affected by both rotation angle and displacement is decoupled by stator current effect to achieve accurate calculation of radial displacement.

[0032] (3) The bearingless motor composite sensing and detection method based on the suspended orthogonal coordinate system provided by the present invention uses the torque system dual closed-loop control of the speed outer loop and the current inner loop, and the suspension system dual closed-loop control of the displacement outer loop and the current inner loop, combined with real-time calculation data, to achieve high-precision closed-loop control; the Hall effect current sensor provides reliable data for magnetic flux density calculation and decoupling, and the influence of torque current is negligible, which reduces the control difficulty.

[0033] (4) The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system provided by the present invention performs sampling, calculation and control steps in a loop to realize real-time monitoring of rotor status and dynamic response of the system; it is compatible with a variety of magnetic flux density measurement sensors, which can be flexibly selected according to actual needs, thus improving the adaptability of the technology to application scenarios. Attached Figure Description

[0034] Figure 1 This is a structural block diagram of the present invention;

[0035] Figure 2 This is a schematic diagram of the sensor magnetic flux density and B1+B3 after decoupling the stator current effect based on the suspended orthogonal coordinate system configuration of the present invention.

[0036] Figure 3 This is a schematic diagram of the sensor magnetic flux density and B2+B4 after decoupling the stator current effect based on the suspended orthogonal coordinate system configuration of the present invention.

[0037] Figure 4 This is a schematic diagram of the magnetic flux density difference B1-B3 of the sensor after decoupling the stator current effect based on the suspended orthogonal coordinate system configuration of the present invention;

[0038] Figure 5 This is a schematic diagram of the magnetic flux density difference B2-B4 of the sensor after decoupling the stator current effect based on the suspended orthogonal coordinate system configuration of the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention discloses a composite sensing and detection method for bearingless motors based on a suspended orthogonal coordinate system. Addressing the high cost of traditional sensing schemes for bearingless motors, this method employs a suspended orthogonal coordinate system sensor configuration, utilizing only four sensors to achieve composite detection of rotor angular and radial displacement of the bearingless motor. This reduces system costs while ensuring stable system operation.

[0041] A composite sensing and detection method for bearingless motors based on a suspended orthogonal coordinate system is proposed. This method employs a sensor positioning configuration within a suspended orthogonal coordinate system and utilizes four sensors to achieve composite detection of the rotor angle and radial displacement of the bearingless motor. The implementation steps of this method are as follows:

[0042] Step S1: Establish an electric levitation orthogonal coordinate system for the bearingless motor and complete the assembly of the four sensor positions based on the levitation orthogonal coordinate system;

[0043] Step S2: Calculate the voltage values ​​of the four sensors and the stator current i of the bearingless motor at the current moment. M Samples are taken and the magnetic flux density values ​​of the motor at the four current sensors, B1, B2, B3, and B4, are calculated.

[0044] Step S3: Perform mathematical calculations on the magnetic flux density difference between two sensors located 180° apart on the two sets of mechanical parts to obtain the current rotor angle θ of the bearingless motor. e ;

[0045] Step S4: Perform mathematical calculations on the magnetic flux density sums at the two sensors that are 180° apart on the two sets of mechanical parts, and decouple them considering the stator current effect to obtain the decoupled magnetic flux density sum (B1+B3) at the two sensors. f (B2+B4) f Thus, the radial displacements x and y of the bearingless motor rotor at the current moment can be obtained;

[0046] Step S5, using the calculated rotor angle θ of the bearingless motor e And radial displacements x and y, to complete the suspension and torque closed-loop control of the bearingless motor;

[0047] Step S6: Repeat steps S2 to S5 to calculate the rotor angle θ of the bearingless motor in real time.e It controls radial displacements x and y, and performs bearingless motor suspension and torque closed-loop control.

[0048] Furthermore, the angle θ between the two coordinate axes of the suspended orthogonal coordinate system in step S1 and the mechanical orthogonal coordinate system... LO The number of pole pairs p of the levitation winding is determined by θ. LO =90 / p.

[0049] Furthermore, the sensor used to detect the magnetic flux density of the motor in step S1 can be any sensor capable of measuring magnetic flux density and meeting the assembly requirements.

[0050] Furthermore, in step S2, the stator current is sampled using a current sensor based on the Hall effect.

[0051] Furthermore, in step S3, the magnetic flux density difference at the two sensors, which are mechanically 180° apart, is only related to the rotor rotation angle and is not related to the rotor radial displacement.

[0052] Furthermore, in step S3, the rotor angle calculation adopts the arctangent of trigonometric functions or the phase-locked loop method, and the calculation formula is as follows:

[0053]

[0054] Among them, B1, B2, B3, and B4 are the magnetic flux density values ​​of the motor at the four sensors.

[0055] Furthermore, in step S4, the magnetic flux density at the two sensors, which are mechanically separated by 180°, is related to both the rotor angle and radial displacement. Based on the calculation of the rotor angle, the calculation of the rotor radial displacement is performed, and the calculation formula is as follows:

[0056]

[0057] Where, θ e Let θ be the rotor angle of the bearingless motor, x and y be the radial displacement of the bearingless motor, μ0 represent the free permeability, δ0 represent the eccentric equivalent air gap length of the bearingless motor rotor, and E represent the fundamental amplitude of the magnetomotive force. Represents the initial phase angle, the subscript f represents the magnetic flux density component contributed by the rotor excitation, and k r The displacement calculation coefficients are represented by B1, B2, B3, and B4, which are the motor magnetic flux density values ​​at the four sensors.

[0058] Furthermore, in step S4, the decoupling of the stator current effect is mainly the decoupling of the levitation current effect. The torque winding and the rotor have the same number of pole pairs, and the torque current is much smaller than the excitation current. Therefore, the effect of the torque current on the magnetic flux density detection is negligible.

[0059] Furthermore, in step S5, the bearingless motor suspension and torque closed-loop control scheme adopts a dual closed-loop control of the torque system (outer speed loop - inner current loop) and a dual closed-loop control of the suspension system (outer displacement loop - inner current loop).

[0060] Furthermore, the formulas for calculating the sum and difference of magnetic flux density at the two sets of sensors mechanically separated by 180° in steps S3 and S4 are as follows:

[0061]

[0062]

[0063] Where B1, B2, B3, and B4 are the magnetic flux density values ​​of the motor at the four sensors, and θ e Let θ be the rotor angle of the bearingless motor, x and y be the radial displacement of the bearingless motor, μ0 represent the free permeability, δ0 represent the eccentric equivalent air gap length of the bearingless motor rotor, and E represent the fundamental amplitude of the magnetomotive force. The initial phase angle is represented by the subscript f, which represents the magnetic flux density component contributed by the rotor excitation part, the subscript T, which represents the magnetic flux density component contributed by the stator current effective driving torque part, and the subscript L, which represents the magnetic flux density component contributed by the stator current levitation control part.

[0064] After decoupling the stator current effect based on the suspended orthogonal coordinate system, the sum and difference of the sensor magnetic flux density are as follows: Figure 2-5 As shown.

[0065] Combination Figure 1-5 This invention details the specific process of a composite sensing and detection method for a bearingless motor based on a suspended orthogonal coordinate system. First, an electrical suspended orthogonal coordinate system for the bearingless motor is established, with the angle θ between the two coordinate axes of this suspended orthogonal coordinate system and the mechanical orthogonal coordinate system. LO The angle is 45°, and the assembly of four sensors based on a suspended orthogonal coordinate system is completed. The theoretical values ​​for the sum and difference of magnetic flux density at two sensors mechanically separated by 180° can be obtained:

[0066]

[0067] Where B1, B2, B3, and B4 are the magnetic flux density values ​​of the motor at the four sensors, and θ e Let θ be the rotor angle of the bearingless motor, x and y be the radial displacement of the bearingless motor, μ0 represent the free permeability, δ0 represent the eccentric equivalent air gap length of the bearingless motor rotor, and E represent the fundamental amplitude of the magnetomotive force. The initial phase angle is represented by the subscript f, which represents the magnetic flux density component contributed by the rotor excitation part, the subscript T, which represents the magnetic flux density component contributed by the stator current effective driving torque part, and the subscript L, which represents the magnetic flux density component contributed by the stator current levitation control part. Stator current effect decoupling can be achieved by detecting and calculating the sum / difference of magnetic flux density using sensors, and then subtracting the corresponding magnetic flux density component calculated based on the model and sampled stator current. The decoupled magnetic flux density component, i.e., the magnetic flux density component of the rotor excitation part, can be used for subsequent composite detection of rotor angle / radial displacement in bearingless motors. Since the torque winding has the same number of pole pairs as the rotor, the magnetic flux density component contributed by the stator current effective driving torque part is negligible compared to the magnetic flux density component contributed by the rotor excitation part; only the decoupling of the magnetic flux density component contributed by the stator current levitation control part needs to be considered.

[0068] From formulas (1) and (2) and combined Figure 2-5 The schematic diagram of the sensor magnetic flux density and magnetic flux density difference after decoupling from the stator current effect can be obtained as follows:

[0069] The magnetic flux density difference after decoupling the stator current effect at two sensors 180° apart is only related to the rotor angle and is independent of the rotor radial displacement. It can be used to detect the rotor angle. Using differential subtraction can not only eliminate the influence of device temperature drift, but also eliminate the influence of rotor suspension eccentricity on the angle calculation.

[0070] The sum of magnetic flux density after decoupling the stator current effect at two sensors 180° apart is related to both the rotor angle and the rotor radial displacement. With the rotor angle already calculated, the sum of magnetic flux density can be used to calculate the rotor radial displacement.

[0071] Based on the sensor configuration scheme of a bearingless motor using a suspended orthogonal coordinate system, the rotor angle of the bearingless motor can be calculated as follows, where the magnetic flux density component contributed by the effective driving torque of the stator current is considered negligible:

[0072]

[0073] The radial displacement of a bearingless motor can be calculated as follows:

[0074]

[0075] Based on this, after completing the assembly of four sensors based on a suspended orthogonal coordinate system, the voltage values ​​of the four sensors and the stator current i of the bearingless motor at the current moment are analyzed. M Sampling is performed, and the current magnetic flux density values ​​B1, B2, B3, and B4 of the motor at the four sensors can be calculated using the sensor characteristics. Then, the magnetic flux density difference between the two sets of sensors, which are mechanically 180° apart, is mathematically calculated as shown in formula (3) to obtain the current rotor angle θ of the bearingless motor. eSimultaneously, the magnetic flux density at two sensors mechanically separated by 180° is mathematically calculated, and the stator current effect is considered for decoupling to obtain the decoupled magnetic flux density at the two sensors (B1+B3). f (B2+B4) f After performing the mathematical operations shown in formula (4), the radial displacements x and y of the bearingless motor rotor at the current moment can be obtained. Finally, the rotor angle and radial displacement of the bearingless motor obtained from the calculation can be used to complete the suspension / torque closed-loop control of the bearingless motor.

[0076] This invention relates to a composite sensing and detection method for bearingless motors based on a suspended orthogonal coordinate system. Addressing the issue of high costs associated with traditional sensing solutions for bearingless motors, this invention employs a sensor position configuration using a suspended orthogonal coordinate system. By utilizing only four sensors, it achieves composite detection of rotor angle / radial displacement of the bearingless motor, thereby reducing system costs while ensuring stable system operation.

[0077] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite sensing and detection method for bearingless motors based on a suspended orthogonal coordinate system, characterized in that, The technology employs a suspended orthogonal coordinate system sensor positioning configuration and utilizes four sensors to achieve composite detection of rotor angle and radial displacement of a bearingless motor. The implementation steps of the technology are as follows: Step S1: Establish an electric levitation orthogonal coordinate system for the bearingless motor and complete the assembly of the four sensor positions based on the levitation orthogonal coordinate system; Step S2: Calculate the voltage values ​​of the four sensors and the stator current i of the bearingless motor at the current moment. M Samples are taken and the current magnetic flux density values ​​of the motor at the four sensors are calculated as B1, B2, B3, and B4. Step S3: Perform mathematical calculations on the magnetic flux density difference between two sensors located 180° apart on the two sets of mechanical parts to obtain the current rotor angle θ of the bearingless motor. e ; Step S4: Perform mathematical calculations on the magnetic flux density sums at the two sensors that are 180° apart on the two sets of mechanical parts, and decouple them considering the stator current effect to obtain the decoupled magnetic flux density sums at the two sensors (B1+B3). f (B2+B4) f Thus, the radial displacements x and y of the bearingless motor rotor at the current moment can be obtained; Step S5, using the calculated rotor angle θ of the bearingless motor e And radial displacements x and y, to complete the suspension and torque closed-loop control of the bearingless motor; Step S6: Repeat steps S2 to S5 to calculate the rotor angle θ of the bearingless motor in real time. e It controls radial displacements x and y, and performs bearingless motor suspension and torque closed-loop control.

2. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S1, the angle θ between the two coordinate axes of the suspended orthogonal coordinate system and the mechanical orthogonal coordinate system. LO The number of pole pairs p of the levitation winding is determined by θ. LO =90 / p.

3. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S1, the sensor used to detect the magnetic flux density of the motor at the location of the sensor can be any type of sensor capable of measuring magnetic flux density and meeting the assembly requirements.

4. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S2, the stator current is sampled using a current sensor based on the Hall effect.

5. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S3, the magnetic flux density difference between the two sensors, which are 180° apart on the two sets of mechanical parts, is only related to the rotor rotation angle and is not related to the rotor radial displacement.

6. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S3, the rotor angle is calculated using either the arctangent function of a trigonometric function or a phase-locked loop method, and the calculation formula is as follows: Among them, B1, B2, B3, and B4 are the magnetic flux density values ​​of the motor at the four sensors.

7. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S4, the magnetic flux density at the two sensors, which are mechanically separated by 180°, is related to both the rotor angle and radial displacement. Based on the calculation of the rotor angle, the rotor radial displacement is calculated using the following formula: Where, θ e Let θ be the rotor angle of the bearingless motor, x and y be the radial displacement of the bearingless motor, μ0 represent the free permeability, δ0 represent the eccentric equivalent air gap length of the bearingless motor rotor, and E represent the fundamental amplitude of the magnetomotive force. Represents the initial phase angle, the subscript f represents the magnetic flux density component contributed by the rotor excitation, and k r The displacement calculation coefficients are represented by B1, B2, B3, and B4, which are the motor magnetic flux density values ​​at the four sensors.

8. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S4, the decoupling of the stator current effect is mainly the decoupling of the levitation current effect. The torque winding and the rotor have the same number of pole pairs, and the torque current is much smaller than the excitation current. The effect of the torque current on the magnetic flux density detection is negligible.

9. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, In step S5, the bearingless motor suspension and torque closed-loop control scheme adopts a dual closed-loop control of the torque system (outer speed loop - inner current loop) and a dual closed-loop control of the suspension system (outer displacement loop - inner current loop).

10. The bearingless motor composite sensing and detection method based on a suspended orthogonal coordinate system according to claim 1, characterized in that, The formulas for calculating the sum and difference of magnetic flux density at the two sensors that are mechanically separated by 180° in steps S3 and S4 are as follows: Where B1, B2, B3, and B4 are the motor magnetic flux density values ​​at the four sensors, and θ e Let θ be the rotor angle of the bearingless motor, x and y be the radial displacement of the bearingless motor, μ0 represent the free permeability, δ0 represent the eccentric equivalent air gap length of the bearingless motor rotor, and E represent the fundamental amplitude of the magnetomotive force. The initial phase angle is represented by the subscript f, which represents the magnetic flux density component contributed by the rotor excitation part, the subscript T, which represents the magnetic flux density component contributed by the stator current effective driving torque part, and the subscript L, which represents the magnetic flux density component contributed by the stator current levitation control part.

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