A bearingless permanent-magnet sheet motor displacement measurement method under three-hall fault state under relative hall fault

Abstract

This invention discloses a method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state with relative Hall faults. The method includes: obtaining the output signal expression of the Hall fault when it is not faulty; when there is a three-Hall fault including relative Hall fault, determining the numbers of the three fault Halls; mechanically fixing the rotor at the center position, rotating the rotor, obtaining the output signals of the three non-faulty Halls, and calculating the non-eccentric permanent magnet flux linkage coefficient; subtracting the basic permanent magnet flux linkage from the three non-faulty Hall output signals respectively to obtain signals that are only related to displacement changes, and calculating the effective component of each non-faulty Hall output signal; calculating and obtaining the reconstructed one-phase displacement signal and the displacement signals of the remaining two phases based on the method of reconstructing the missing one-phase displacement signal; multiplying the three-phase displacement signals by a cosine negative-sequence component and a sine negative-sequence component that are one harmonic of the rotor frequency, and summing them to obtain the rotor radial displacements x and y respectively.

Description

Technical Field

[0001] This invention relates to the field of bearingless motor control technology, and in particular to a method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state with relative Hall fault. Background Technology

[0002] Bearingless thin-plate motors, lacking a shaft and with a short axial length, separate stator and rotor, easily achieve five-degree-of-freedom levitation, making them uniquely applicable in ultra-clean medical fields such as cardiac pumps. Traditional bearingless control requires displacement sensors to sample displacement signals in real time to achieve closed-loop control. Commonly used displacement sensors, such as eddy current sensors, are large, expensive, and highly susceptible to environmental influences, failing to meet the requirements of small size and stable levitation performance in cardiac pumps. Therefore, some researchers have proposed using small-volume, low-cost Hall effect sensors to replace commonly used displacement sensors, significantly reducing system size and improving levitation capability and accuracy. However, due to the influence of temperature, vibration, and noise, Hall effect sensors are prone to failure, leading to the loss of Hall output signals. This prevents displacement information calculation and closed-loop control, causing the bearingless motor system to lose its ability to levitate and transport blood, potentially resulting in a major safety accident. Therefore, research on Hall effect sensor fault-tolerant technology is needed to ensure stable levitation of the bearingless motor system even in the event of Hall effect failure.

[0003] Chinese patent CN118589928A discloses a "rotor displacement identification method under three-Hall fault conditions in a bearingless permanent magnet thin-film motor". This patent proposes a method for solving the non-eccentric permanent magnet flux linkage coefficient, which can calculate the rotor radial displacement under asymmetric dual-Hall fault conditions, ensuring the bearingless motor system remains levitated. However, this method is only applicable to asymmetric dual-Hall fault conditions. When a three-Hall fault occurs under relative Hall fault conditions, because the Hall sensor opposite to the faulty Hall also malfunctions, the non-eccentric permanent magnet flux linkage cannot be calculated based on the relative Hall output signal. This leads to the re-coupling of rotor radial displacement and angle, making it impossible to calculate the rotor radial displacement. Summary of the Invention

[0004] Technical Objective: To address the shortcomings of existing bearingless permanent magnet thin-film motor displacement measurement methods in the case of three-Hall faults under relative Hall faults, this invention discloses a method for measuring the displacement of bearingless permanent magnet thin-film motors under three-Hall fault conditions.

[0005] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution.

[0006] A method for displacement measurement of a bearingless permanent magnet thin-film motor under a three-Hall fault state with relative Hall faults is disclosed. The bearingless permanent magnet thin-film motor adopts a six-tooth one-pole motor structure, including six L-shaped stators. Each L-shaped stator includes an axial stator yoke and radial stator teeth, which are evenly distributed around the thin-film rotor. The radial stator teeth are flush with the rotor. Each axial stator yoke is wound with a suspension winding and a torque winding, respectively. The torque winding has one pair of poles, and the suspension winding has two pairs of poles, realizing both suspension control and rotation control. The bottom of the L-shaped stator is connected by an iron core magnetic ring. A pair of parallel magnetized permanent magnets with poles are attached to the outside of the thin-film rotor. The magnetic field of the permanent magnets is sinusoidally distributed in space. Six Hall sensors Hall1-Hall6 are evenly installed counterclockwise at equal intervals in the radial stator slots, with Hall1 located at the center of the stator slot facing the N-pole rotor. The other five Hall sensors are numbered sequentially in a counterclockwise order. The method includes the following steps: Step S1: Obtain Hall effect non-fault status Hall 1- Hall The output signal expression of 6, when a three-Hall fault involving relative Hall faults is present, determines the number of the three fault Halls; the three fault Halls include the two fault-relative Halls and the fault-single Hall, and the three non-fault Halls include the two non-fault-relative Halls and the non-fault-remaining single Hall; Step S2: Fix the rotor mechanically at the center position, rotate the rotor, obtain the three non-fault Hall output signals, and calculate the non-eccentric permanent magnet flux linkage coefficient based on the amplitude of the three non-fault Hall output signals. Step S3: Subtract the basic permanent magnet flux portion from the three non-faulty Hall output signals respectively to obtain signals that are only related to displacement changes, which are used as the effective components of each non-faulty Hall output signal. Step S4: Based on the method of reconstructing the missing phase displacement signal, calculate and obtain the reconstructed phase displacement signal and the displacement signals of the other two phases according to the effective components of the non-fault Hall output signal obtained in step S3. Step S5: Multiply the three-phase displacement signal obtained in step S4 by a cosine negative sequence component that is a harmonic of the rotor frequency, and sum them to obtain the rotor radial displacement x; multiply the three displacement signals by a sine negative sequence component that is a harmonic of the rotor frequency, and perform subtraction to obtain the rotor radial displacement y.

[0007] Beneficial Effects: This invention employs an offline mechanical measurement method to obtain the amplitude of the non-eccentric permanent magnet flux linkage, eliminating its influence on displacement calculation. Secondly, based on the displacement signal reconstruction concept and the displacement offset of three symmetrically distributed Hall sensors, the missing phase displacement signal is calculated using two of the remaining Hall sensors through trigonometric functions. An equation is then established to decouple the rotor's radial displacement and angle. The algorithm proposed in this invention can recalculate displacement information under a three-Hall fault condition with a dual-Hall fault in the motor, improving the reliability and fault tolerance of the bearingless sheet metal system. The algorithm eliminates the need for online calculation of the non-eccentric permanent magnet flux linkage and solves for displacement by reconstructing the missing phase displacement signal through trigonometric functions. This results in short processing and calculation time, improving computational efficiency. Attached Figure Description

[0008] Figure 1 This is a flowchart of the displacement measurement method for a bearingless permanent magnet thin-film motor under a three-Hall fault state in the context of a relative Hall fault, provided by the present invention. Figure 2 This is a schematic diagram of the mechanical position of the bearingless permanent magnet thin-film motor Hall sensor used in this invention; Figure 3 This is an axial cross-sectional view of the six-tooth, one-pole, bearingless permanent magnet thin-film motor provided by the present invention; Figure 4 This is a schematic diagram of the rotor eccentricity of the bearingless permanent magnet thin-film motor provided by the present invention; Figure 5 It is a simulation diagram of given displacement and estimated displacement under Hall sensor failure, as shown in patent CN118589928A; Figure 6 These are simulation diagrams of the given displacement and estimated displacement of the motor rotor displacement measurement method provided by this invention; Figure 7 This is an overall block diagram of a bearingless permanent magnet thin-film motor system using a displacement-free algorithm. Detailed Implementation

[0009] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0010] Example: This example describes a method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state with relative Hall faults, as shown in the attached figure. Figure 2 and attached Figure 3As shown, the bearingless permanent magnet thin-film motor adopts a six-tooth, one-pole motor structure, including six L-shaped stators. Each L-shaped stator 2 includes an axial stator yoke and radial stator teeth, evenly distributed around the thin-film rotor 1. The radial stator teeth are flush with the rotor. Each axial stator yoke is wound with a suspension winding 4 and a torque winding 5. The torque winding has one pair of poles, and the suspension winding has two pairs of poles, simultaneously realizing suspension control and rotation control. The bottom of the L-shaped stator is connected by an iron core magnetic ring 3. A pair of parallel magnetized permanent magnets are attached to the outside of the thin-film rotor. The magnetic field of the permanent magnet is sinusoidally distributed in space. Six Hall sensors Hall1-Hall6 are evenly installed counterclockwise at equal intervals in the radial stator slots. Hall1 is located at the center of the stator slot facing the N-pole rotor. The other five Hall sensors are numbered sequentially in a counterclockwise order. The application scenario of this invention is as follows: when a three-Hall fault, which includes a relative Hall fault, is detected, the three Hall output signals are lost, the numbers of the three faulty Hall sensors are identified, the displacement expression is reconstructed based on the output signals of the three non-faulty Hall sensors, and a set of equations is established to solve the rotor displacement in the start-up state. As attached Figure 4 As shown, during the actual operation of a bearingless permanent magnet thin-film motor, the motor rotor exhibits eccentricity, which can be decomposed into eccentricities in two perpendicular directions according to the coordinate system. Assuming all six Hall effect sensors are functioning correctly, control can be achieved through a displacement-free reverse-sequence decoupling algorithm. Figure 7 This is a block diagram of the overall control of the bearingless permanent magnet thin-film motor system employing the displacement-free reverse decoupling algorithm of this invention. The torque control section uses traditional vector control, with an outer speed loop using the speed calculated from the Hall sensor as feedback, and an inner current loop. The displacement control section has an outer displacement loop using the displacement obtained from the Hall sensor signal through the displacement calculation method of this invention as feedback, and the inner loop is also a current loop. However, in practical operation, when the Hall sensor malfunctions, it can no longer be used for feedback. Figure 7 The solution shown is calculated.

[0011] As attached Figure 1 As shown, this invention provides a method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state with relative Hall faults. Six Hall sensors are evenly installed counterclockwise at the same angle in the radial stator slots. The method is used to deduce the Hall fault-free state. Hall 1- HallThe output signal of 6, when containing a three-Hall fault with relative Hall faults, determines the numbers of the three fault Halls; the rotor is mechanically fixed at the center position, the rotor is rotated, and the average amplitude of the remaining three non-faulty Hall output signals is taken as the non-eccentric permanent magnet flux linkage coefficient; the basic permanent magnet flux linkage is subtracted from the remaining non-faulty Hall signals to obtain signals only related to displacement changes, and then simplified to obtain the effective components of the signal; the difference between the two Hall output signals symmetrically distributed with one of the faulty Halls is used to obtain a sine expression for displacement, and then a cosine expression for displacement is calculated. The two Hall output signals symmetrically distributed in a faulty Hall sensor are summed with a cosine expression of 0.75 times the displacement to reconstruct a single-phase displacement signal. The non-faulty Hall output signals are summed and doubled to obtain the remaining two-phase displacement signals. The three-phase displacement signals are multiplied by a cosine negative-sequence component with a frequency greater than the rotor frequency, and summed to obtain the rotor radial displacement x. The three-phase displacement signals are multiplied by a sine negative-sequence component with a frequency greater than the rotor frequency, and the difference is processed to obtain the rotor radial displacement y. This invention can accurately estimate rotor displacement information when the symmetrical dual-Hall sensor of the motor fails. In this embodiment, Hall 1. Hall 4 and Hall Taking the example of three Hall sensors failing to output signals, including two relative Hall sensors... Hall 1 and Hall 4. It should be noted that in practical applications, regardless of which three Hall faults are involved under relative Hall fault conditions, the method of this embodiment can be used for rotor displacement estimation. The method includes the following steps: Step S1: First, derive the Hall non-fault condition. Hall 1- Hall The output signal expression for 6, when involving a three-Hall fault including relative Hall faults, determines the numbers of the three faulty Halls. The three faulty Halls include the two faulty relative Halls and the faulty single Hall. The three non-faulty Halls include the two non-faulty relative Halls and the remaining non-faulty single Hall. It should be noted that this invention defines the Hall located at the center of the stator slot directly opposite the N-pole rotor as Hall1, and sequentially defines the numbers of the other five Halls in a counter-clockwise order. When a Hall fault occurs, i.e., abnormal Hall data or no output signal, the faulty Hall number can be quickly identified. Establish a non-faulty state Hall 1- Hall The expression for the output signal of 6. Hall Taking 1 as an example, the output signal and the rotor are along Hall 1. Direction and perpendicular to HallThe displacement in direction 1 is related to the rotor angle and the permanent magnet flux linkage. Since the thin-plate rotor does not have silicon steel sheets and the armature leakage magnetic reluctance is relatively large, the leakage magnetic flux is ignored. The expression is as follows: , in, θ l Represents the angle of rotor eccentricity. l Represents the length of rotor eccentricity. ωt Represents the rotor angle. θ 0 represents Hall The mechanical angle at point 1 is taken as follows: θ 0 = 0; k 1 is along Hall Displacement coefficient in direction 1 k 2 is perpendicular to Hall The displacement coefficient in direction 1, and k 1. k 2. Given, k 3 is the flux linkage coefficient of the non-eccentric permanent magnet.

[0012] because Hall 1 and Hall 4. Relatively distributed in the mechanical direction, using θ 0+ pi replace θ 0, Hall 4. The output signal is represented as follows: , Similarly, the output signals of the other Hall sensors can be derived.

[0013] The following is Hall 1. Hall 4 and Hall Taking the failure of three Hall sensors as an example, including two relative Hall sensors... Hall 1 and Hall 4.

[0014] Step S2: Fix the rotor mechanically in the center position, rotate the rotor, and obtain the three non-faulty Hall output signals. At this time, since the rotor is mechanically fixed in the center position, the length of the rotor eccentricity is... l When the value is 0, the output signal is independent of displacement change; that is, the output signal only retains the cosine term of the third term concerning the unbiased permanent magnet flux linkage coefficient. The unbiased permanent magnet flux linkage coefficient is calculated based on the amplitudes of the three Hall output signals when there is no fault. k 3. Due to Hall 2. Hall 5 are relatively distributed in the mechanical direction, that is Hall 2. HallThe cosine terms of the non-eccentric permanent magnet flux linkage coefficient in equation 5 have different signs. After the three Hall output signals are superimposed, only one remains, i.e. Hall The cosine term of 6 concerning the flux linkage coefficient of the unbiased permanent magnet is based on... Hall The non-eccentric permanent magnet flux linkage coefficient can be calculated from the output signal amplitude of 6. k 3.

[0015] Step S3: Subtract the basic permanent magnet flux portion from the three non-faulty Hall output signals to simplify the process and obtain signals that are only related to displacement changes, which are used as the effective components of each non-faulty Hall output signal.

[0016] by Hall The location of 1 is the starting point, take θ 0=0, the measured value k Substitute this term into the expression and subtract it, then process it using the product-to-sum formula. Hall Components in 2 that are only related to displacement Hall 2_eff The expression is as follows: , in, Hall 5's displacement-only component Hall 5_eff and Hall Components in 2 that are only related to displacement Hall 2_eff same; but Hall 6 Components that are only related to displacement Hall 6_eff The expression is as follows: , Step S4: Based on the method of reconstructing the missing phase displacement signal, calculate and obtain the reconstructed phase displacement signal and the displacement signals of the other two phases according to the effective components of the non-fault Hall output signal obtained in step S3. The method for reconstructing the missing phase displacement signal includes: subtracting the output signals of two non-fault Halls that are symmetrically distributed with one of the fault Halls to obtain a sine expression for the displacement; then calculating a cosine expression for the displacement; summing the output signals of the two non-fault Halls that are symmetrically distributed with one of the fault Halls with 0.75 times the cosine expression for the displacement to obtain the reconstructed phase displacement signal; and adding the two non-fault Halls to each other and doubling the sum of the two non-fault Halls to obtain the remaining two phase displacement signals.

[0017] Hall 2 and Hall 6 and Faults Hall 4. Mechanically symmetrically distributed. Hall2_eff and Hall 6_eff The difference yields a sine expression for the displacement, and the calculation formula is: , in, Hall 2_eff and Hall 6_eff These are the effective components of the output signals of two non-faulty Hall sensors that are symmetrically distributed with respect to one of the faulty Hall sensors.

[0018] according to Hall 2_eff and Hall 6_eff The difference can be calculated using the cosine expression for displacement based on a 90° angular difference. The formula is as follows: , Where A is the cosine expression for displacement.

[0019] According to the above formula and Hall 2_eff and Hall 6_eff The output expression can reconstruct the missing phase displacement signal, and the calculation formula is as follows: , Where B is the reconstructed one-phase displacement signal; Then the non-faulty Hall 6_eff twice and Hall 2_eff , Hall 5_eff The displacement signals of the other two phases are obtained by summing the signals relative to the Hall effect, and the calculation formula is as follows: , , in, Hall5 _eff The effective component of the output signal of the remaining Hall among three non-faulty Halls, excluding the two non-faulty Halls that are symmetrically distributed with one of the faulty Halls. Step S5: Multiply the three-phase displacement signal obtained in step S4 by a cosine negative sequence component that is a harmonic of the rotor frequency, and sum them to obtain the rotor radial displacement x; multiply the three displacement signals by a sine negative sequence component that is a harmonic of the rotor frequency, and perform subtraction to obtain the rotor radial displacement y. , , in, k It is the displacement coefficient, and , is a known value.

[0020] The invention also included simulation analysis; Figure 5 The simulation diagrams of given displacement and estimated displacement under Hall sensor failure in patent CN118589928A show that the two are very similar and cannot be used to calculate displacement. Figure 6 The simulation diagrams of the given displacement and estimated displacement of the motor rotor displacement measurement method provided by this invention show that the two have a high degree of overlap, and the displacement information can be correctly calculated, verifying the feasibility of the solution.

[0021] The present invention also discloses an electronic device, the device comprising: a memory for storing a computer program; and a processor for executing the computer program to cause the device to perform the aforementioned method.

[0022] The present invention also provides a computer storage medium on which a computer program is stored, wherein when the computer program is run, a device running the computer program implements the aforementioned method.

[0023] In the embodiments of this application, the terms "first" and "second" (if they exist) are used only as name identifiers and do not represent the order of first and second.

[0024] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that all or part of the steps in the methods of the above embodiments can be implemented by means of software plus a general-purpose hardware platform. Based on this understanding, the technical solution of this application can be embodied in the form of a software product. This computer software product can be stored in a storage medium. The memory can be various types of memory, such as random access memory, read-only memory, flash memory, etc., such as read-only memory (ROM) / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which can be a personal computer, server, or network communication device such as a router) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0025] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state with relative Hall faults, characterized in that: The bearingless permanent magnet thin-film motor adopts a six-tooth, one-pole motor structure, including six L-shaped stators. Each L-shaped stator includes an axial stator yoke and radial stator teeth, evenly distributed around the thin-film rotor. The radial stator teeth are flush with the rotor. Each axial stator yoke is wound with a suspension winding and a torque winding, respectively. The torque winding has one pair of poles, and the suspension winding has two pairs of poles, simultaneously realizing suspension control and rotation control. The bottom of the L-shaped stator is connected by an iron core magnetic ring. A pair of parallel magnetized permanent magnets with poles are attached to the outside of the thin-film rotor. The magnetic field of the permanent magnets is sinusoidally distributed in space. Six Hall sensors Hall1-Hall6 are evenly installed counterclockwise at equal intervals in the radial stator slots, with Hall1 located at the center of the stator slot facing the N-pole rotor. The other five Hall sensors are numbered sequentially in a counterclockwise order. The method includes the following steps: Step S1: Obtain Hall effect non-fault status Hall 1- Hall The output signal expression of 6, when a three-Hall fault involving relative Hall faults is present, determines the number of the three fault Halls; the three fault Halls include the two fault-relative Halls and the fault-single Hall, and the three non-fault Halls include the two non-fault-relative Halls and the non-fault-remaining single Hall; Step S2: Fix the rotor mechanically at the center position, rotate the rotor, obtain the three non-fault Hall output signals, and calculate the non-eccentric permanent magnet flux linkage coefficient based on the amplitude of the three non-fault Hall output signals. Step S3: Subtract the basic permanent magnet flux portion from the three non-faulty Hall output signals respectively to obtain a signal that is only related to displacement change, which is used as the effective component of each non-faulty Hall output signal. Step S4: Based on the method of reconstructing the missing phase displacement signal, calculate and obtain the reconstructed phase displacement signal and the displacement signals of the other two phases according to the effective components of the non-fault Hall output signal obtained in step S3. Step S5: Multiply the three-phase displacement signal obtained in step S4 by a cosine negative sequence component that is a harmonic of the rotor frequency, and sum them to obtain the rotor radial displacement x; multiply the three displacement signals by a sine negative sequence component that is a harmonic of the rotor frequency, and perform subtraction to obtain the rotor radial displacement y.

2. The method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state in the case of a relative Hall fault, as described in claim 1, is characterized in that: In step S4, the method for reconstructing the missing phase displacement signal includes: subtracting the output signals of two non-fault Halls that are symmetrically distributed with one of the fault Halls to obtain a sine expression for the displacement, then calculating a cosine expression for the displacement, summing the output signals of the two non-fault Halls that are symmetrically distributed with one of the fault Halls with 0.75 times the cosine expression for the displacement to obtain the reconstructed phase displacement signal, and adding the two non-fault Halls relative to each other and doubling the sum of the two non-fault Halls relative to each other to obtain the remaining two phase displacement signals respectively.

3. The method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state in relation to a Hall fault, as described in claim 2, is characterized in that: The sine expression for displacement, and the calculation formulas include: ， in, Hall 2_eff and Hall 6_eff These are the effective components of the output signals of two non-faulty Hall sensors that are symmetrically distributed with one of the faulty Hall sensors. k 1 is along Hall Displacement coefficient in direction 1 k 2 is perpendicular to Hall Displacement coefficient in direction 1 θ l Represents the angle of rotor eccentricity. l Represents the length of rotor eccentricity. ωt Represents the rotor angle. θ 0 represents Hall The mechanical angle at which 1 is located.

4. The method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state in relation to a Hall fault, as described in claim 2, is characterized in that: The formulas for calculating the cosine expression of displacement include: ， Where A is the cosine expression for displacement; k 1 is along Hall Displacement coefficient in direction 1 k 2 is perpendicular to Hall Displacement coefficient in direction 1 θ l Represents the angle of rotor eccentricity. l Represents the length of rotor eccentricity. ωt Represents the rotor angle. θ 0 represents Hall The mechanical angle at which 1 is located.

5. The method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state in relation to a Hall fault, as described in claim 2, is characterized in that: Formula for reconstructing a single-phase displacement signal include: ， Where B is the reconstructed one-phase displacement signal; Hall 2_eff and Hall 6_eff These are the effective components of the output signals of two non-faulty Hall sensors that are symmetrically distributed with one of the faulty Hall sensors. k 1 is along Hall Displacement coefficient in direction 1 k 2 is perpendicular to Hall Displacement coefficient in direction 1 θ l Represents the angle of rotor eccentricity. l Represents the length of rotor eccentricity. ωt Represents the rotor angle. θ 0 represents Hall 1 represents the mechanical angle, and A is the cosine expression for the displacement.

6. The method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state in the case of a relative Hall fault, as described in claim 2, is characterized in that: Formula for calculating the remaining two-phase displacement signals include: ， ， in, Hall 2_eff and Hall 6_eff These are the effective components of the output signals of two non-faulty Hall sensors that are symmetrically distributed with one of the faulty Hall sensors. Hall5 _eff The effective component of the output signal of the remaining Hall among three non-faulty Halls, excluding the two non-faulty Halls that are symmetrically distributed with one of the faulty Halls. k 1 is along Hall Displacement coefficient in direction 1 k 2 is perpendicular to Hall Displacement coefficient in direction 1 θ l Represents the angle of rotor eccentricity. l Represents the length of rotor eccentricity. ωt Represents the rotor angle. θ 0 represents Hall The mechanical angle at which 1 is located.

7. The method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state in the case of a relative Hall fault, as described in claim 1, is characterized in that: In step S5, the formulas for calculating the rotor radial displacements x and y include: ， ， in, Hall 2_eff and Hall 6_eff These are the effective components of the output signals of two non-faulty Hall sensors that are symmetrically distributed with one of the faulty Hall sensors. Hall5 _eff The effective component of the output signal of the remaining Hall among three non-faulty Halls, excluding the two non-faulty Halls that are symmetrically distributed with one of the faulty Halls. k 1 is along Hall Displacement coefficient in direction 1 k 2 is perpendicular to Hall Displacement coefficient in direction 1 θ l Represents the angle of rotor eccentricity. l Represents the length of rotor eccentricity. ωt Represents the rotor angle. θ 0 represents Hall 1 represents the mechanical angle; B represents the reconstructed one-phase displacement signal; A represents the cosine expression for the displacement. k It is the displacement coefficient, and .

8. The method for measuring the displacement of a bearingless permanent magnet thin-film motor under a three-Hall fault state in the case of a relative Hall fault, as described in claim 1, is characterized in that: In step S3, when calculating the effective components of the non-faulty Hall output signal, the process is performed using the product-to-sum formula.

Images