CN113719539B - Magnetic suspension bearing displacement sensor fault-tolerant control system and control method - Google Patents

Abstract

The invention provides a fault-tolerant control system and a fault-tolerant control method for a displacement sensor of a magnetic bearing. The system comprises a magnetic suspension bearing rotor device, a controller, a power amplifier, a thrust disc, a sensor assembly, a fault diagnosis module and a fault-tolerant control module, wherein the thrust disc is connected with a rotor in the magnetic suspension bearing rotor device and moves synchronously. The sensor assembly includes a radial displacement sensor and a composite displacement sensor. According to the invention, the composite displacement sensor is reused and used as a redundant displacement sensor, so that the hardware cost is saved, and the fault-tolerant control algorithm is easy to realize; by additionally arranging the composite displacement sensor and the function multiplexing among the sensor components, multiple redundancy is realized, and the system reliability is improved. The displacement measurement values of the two non-differential sensors are subjected to coordinate transformation to obtain displacement values of two radial degrees of freedom, so that the fault-tolerant control of the sensors is realized, and the reliability of the system is improved.

Description

Magnetic suspension bearing displacement sensor fault-tolerant control system and control method

technical field

The invention relates to the technical field of sensor fault-tolerant control, in particular to a fault-tolerant control system and control method for a magnetic suspension bearing displacement sensor.

Background technique

Magnetic suspension bearings have the advantages of low loss, no lubrication and no contact, and have been more and more widely used in recent years.

The magnetic suspension bearing rotor system consists of a rotor, a displacement sensor, a controller, a power amplifier and a magnetic bearing body. The displacement sensor transmits the rotor displacement value to the controller. After the controller calculates the control current signal, it drives the power amplifier to generate the control current. The electromagnetic force generated by the control current passing through the electromagnet coil acts on the rotor to keep the rotor suspended at the preset position.

In order to realize the closed-loop feedback control of the system in a general active magnetic bearing system, at least one displacement sensor must be installed on each degree of freedom of the magnetic bearing to detect the rotor displacement signal in real time. In order to avoid the failure of the electromagnetic bearing caused by the failure of the displacement sensor and improve the reliability of the system, the existing fault-tolerant control methods mainly include configuring redundant sensors on each degree of freedom, or using the self-sensing method to obtain the electromagnetic bearing coil voltage The rotor displacement estimation signal is extracted from the current and current signals.

In the existing sensor fault-tolerant control method, the redundant sensors are in the standby state under normal circumstances, and the function reuse cannot be realized, the cost performance is low, the displacement calculation accuracy of the self-sensing method is low, and the stability of the magnetic bearing is poor, so it is urgent to propose a solution plan.

The invention patent with application number CN202010376226.7 discloses a fault-tolerant control system and control method for displacement sensors used in active radial magnetic bearings. The control system is compatible with the active radial magnetic suspension bearing, and the system includes a displacement feedback part, a fault diagnosis circuit, a fault-tolerant control module and a feedback execution part; the displacement feedback part is fixedly arranged on the periphery of the active radial magnetic suspension bearing rotor in an asymmetric form The output of the displacement feedback part is electrically connected to the input of the fault diagnosis circuit and the fault-tolerant control module, the output of the fault diagnosis circuit is electrically connected to the input of the fault-tolerant control module, and the output of the fault-tolerant control module is electrically connected to the input of the feedback execution part. Connection, the output of the feedback execution part is electrically connected with the electromagnetic coil in the active radial magnetic suspension bearing.

However, the above-mentioned sensor fault-tolerant control system has the disadvantage of being unable to eliminate the common-mode noise in the displacement of each degree of freedom due to the asymmetric sensor arrangement, and the added two redundant displacement sensors do not play an additional role when no fault occurs. effect, low cost performance.

In view of this, it is necessary to design an improved magnetic suspension bearing displacement sensor fault-tolerant control system and control method to solve the above problems.

Contents of the invention

The purpose of the present invention is to provide a fault-tolerant control system and control method for a magnetic suspension bearing displacement sensor.

In order to achieve the purpose of the above invention, the present invention provides a fault-tolerant control system for a magnetic suspension bearing displacement sensor, which includes a magnetic suspension bearing rotor device, a controller and a power amplifier, and also includes a motor that is connected to the rotor in the magnetic suspension bearing rotor device and moves synchronously. Thrust disc, sensor assembly, fault diagnosis module and fault-tolerant control module;

The sensor assembly includes several radial displacement sensors for measuring rotor displacement data and a composite displacement sensor for measuring thrust disk displacement data; the composite displacement sensors and the radial displacement sensors are not coplanar with each other.

As a further improvement of the present invention, several radial displacement sensors are coplanarly arranged, and a plane Cartesian coordinate system is established on a plane perpendicular to the central axis of the rotor with the center of the rotor in the magnetic suspension bearing rotor device as the origin. The displacement sensor includes a first radial displacement sensor arranged in the positive and negative directions of the X axis and arranged symmetrically with each other, a second radial displacement sensor arranged in the positive and negative directions of the Y axis and arranged symmetrically with each other, and a third radial displacement sensor sensor.

As a further improvement of the present invention, the first connecting line formed by the third radial displacement sensor and the center of the rotor does not coincide with the X axis or the Y axis.

As a further improvement of the present invention, several grooves are arranged at equal intervals on the outer circumference of the thrust disk, and the composite displacement sensor is arranged on the outer side of the thrust disk in the radial direction for measuring the distance between it and the thrust disk. The surface distance can simultaneously obtain the rotor radial displacement information and the rotor rotational position angle information.

As a further improvement of the present invention, the second connecting line formed between the composite displacement sensor and the center of the thrust disc and the first connecting line formed between the third radial displacement sensor and the center of the rotor are arranged on different planes, Neither parallel nor intersecting; the second connection line is neither parallel nor intersecting with the X-axis and the Y-axis.

As a further improvement of the present invention, the fault-tolerant control module includes a filtering module and a displacement calculation module; the filtering module performs filtering processing on the measured value of the composite displacement sensor to obtain the effective displacement of the non-groove portion of the edge of the thrust plate; the displacement The calculation module obtains the calculated value of the displacement of each degree of freedom according to the fault form of the sensor.

As a further improvement of the present invention, the fault diagnosis module performs comprehensive sampling and analysis on the measured values of the composite displacement sensor and the radial displacement sensor to determine whether the sensor is faulty.

As a further improvement of the present invention, the magnetic suspension bearing rotor device is one of a permanent magnet bias hybrid magnetic bearing rotor device and a pure electric excitation magnetic bearing rotor device.

In order to achieve the purpose of the above invention, the present invention also provides a fault-tolerant control method for a magnetic suspension bearing displacement sensor, using the above-mentioned fault-tolerant control system for a magnetic suspension bearing displacement sensor to perform fault-tolerant control, including the following steps:

S1, start the magnetic suspension bearing rotor device, the rotor and the thrust plate rotate synchronously, the sensor components measure the displacement data in real time, and obtain the radial displacement measurement value measured by the radial displacement sensor and the thrust measured by the composite displacement sensor under normal conditions The relationship between the effective displacement measurements of the non-groove portion of the disk edge;

S2, the fault-tolerant control module intercepts and filters the displacement measurement value of the composite displacement sensor, and judges the real-time sampling measurement value of the composite displacement sensor according to the above relationship, taking the fluctuation range of the effective measurement value of the non-groove part as the effective range, If it is within the aforementioned effective range, output this value, otherwise, output the last sampled measurement value as the current measurement value, and finally perform low-pass filtering on the above-mentioned intercepted displacement value to obtain the radial displacement of the rotor;

When all the sensors are working normally, the measured values of the first radial sensor are marked as s ₁ and s ₃ , the measured values of the second radial sensor are marked as s ₂ and s ₄ , the measured values of the third radial sensor are marked as s ₅ , The measured value of the processed composite displacement sensor is denoted as s ₆ , and the relationship between the above measured value and the displacement values x and y in the X-axis and Y-axis directions is as follows:

s ₁ =x; s ₂ =-y; s ₃ =-x; s ₄ =y;

S3, classify the above-mentioned sensor fault forms, and calculate the degree of freedom displacement corresponding to the above-mentioned classified fault forms;

S4, the controller obtains a control current signal according to the displacement calculation value obtained by the fault-tolerant control module, drives the power amplification module to obtain the control current, and passes it into the electromagnetic coil in the magnetic suspension bearing rotor device to control the rotor.

As a further improvement of the present invention, the specific process of sensor fault form classification and displacement calculation in step S3 is:

Fault state one,

One of the first radial sensor and the second radial sensor fails, or the two non-differential sensors fail, the third radial sensor and the compound displacement sensor are in any state, and the first radial sensor S ₁ and the second Take the fault of radial sensor _S2 as an example, the displacement is as follows:

x=-s ₃ ; y=s ₄ ;

Fault state two,

Two differential sensors of the first radial sensor and the second radial sensor are faulty, or three sensors are faulty, at least one of the third radial sensor and the composite displacement sensor is normal, and the first radial sensor S ₁ , the second radial sensor Take the failure of the second radial sensor S ₂ , the first radial sensor S ₃ , and the third radial sensor S ₅ as an example, and the displacements are as follows:

y＝s₄；

y=s ₄ ;

Fault state three,

Both the first radial sensor and the second radial sensor are faulty, the third radial sensor and the composite displacement sensor are normal, and the displacement is as follows:

The beneficial effects of the present invention are:

1. The fault-tolerant control system of the magnetic suspension bearing displacement sensor provided by the present invention, by multiplexing the composite displacement sensor, uses it as a redundant displacement sensor, which saves hardware costs, and the fault-tolerant control algorithm is easy to implement; by adding a composite displacement sensor and sensor components Multiplexing between functions, realizing multiple redundancy, and improving system reliability. The function multiplexing mechanism between the sensor components is that the coordinate transformation of the displacement measurement values of the two non-differential sensors can obtain the displacement values of the two degrees of freedom in the radial direction, thereby realizing sensor fault-tolerant control and improving system reliability. .

2. The fault-tolerant control system of the magnetic suspension bearing displacement sensor provided by the present invention adopts a sensor assembly composed of a radial displacement sensor and a composite displacement sensor, and sets the first/second/third radial displacement sensors to be symmetrical or non-symmetrical. The symmetrical sensor arrangement enables the radial displacement sensor to obtain multi-degree-of-freedom displacement measurement values, which are integrated with the effective measurement values of the composite displacement sensor, enabling fault-tolerant control and displacement calculation under different sensor failure forms, ensuring High measurement accuracy before and after sensor failure.

3. In the fault-tolerant control method of the magnetic suspension bearing displacement sensor provided by the present invention, the fault-tolerant control module calculates the normal sensor measurement sampling value according to the sensor fault form, obtains the displacement calculation value of each degree of freedom and thus calculates the control current signal, and improves the system after the fault. reliability.

4. In the fault-tolerant control system of the magnetic suspension bearing displacement sensor provided by the present invention, the groove structure on the thrust plate will make the displacement sampling value of the composite displacement sensor unable to directly reflect the actual displacement of the rotor. The present invention performs data processing on the displacement sampling value of the composite sensor. The effective displacement information is obtained, and the displacement value of each degree of freedom is accurately calculated. The mechanism of data processing is: the depth or width of a groove in the thrust disk is different from other grooves, as a groove indicating the position angle of the rotor. Square wave waveform, according to the groove depth of the rotor angle, the sensor can compensate the measurement data at the groove to get a more accurate thrust plate displacement; the effective displacement value measured by the composite displacement sensor can accurately reflect the rotor displacement. The mechanism is that the rotor displacement changes at a slow rate. Through the sudden change of the displacement measurement value of the composite sensor, it can be judged that the corresponding position is the outer surface of the thrust disc or a groove, combined with the data correction of the precise depth of the groove at different rotor position angles obtained in the previous test. It can reflect the precise displacement of the thrust disc, and the distance between the thrust disc and the plane where the radial sensor is located is very close, and its displacement accurately reflects the rotor displacement at the radial sensor.

Description of drawings

Fig. 1 is a frame diagram of a fault-tolerant control system for a magnetic suspension bearing displacement sensor provided by the present invention.

Fig. 2 is a structural diagram of the fault-tolerant control system of the magnetic suspension bearing displacement sensor provided by the present invention.

Fig. 3 is an arrangement diagram of the sensor assembly provided by the present invention (a in Fig. 3 is a front view, and b in Fig. 3 is a side view).

reference sign

1-first radial sensor S ₁ ; 2-first radial sensor S ₃ ; 3-second radial sensor S ₂ ; 4-second radial sensor S ₄ ; 5-third radial sensor S ₅ ; 6 - Composite sensor S ₆ .

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and/or processing steps closely related to the solution of the present invention are shown in the drawings, and the steps related to the present invention are omitted. Invent other details that don't really matter.

Additionally, it should be noted that the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also Other elements not expressly listed, or inherent to the process, method, article, or apparatus are also included.

Please refer to Figs. 1-2, the present invention provides a fault-tolerant control system for a magnetic suspension bearing displacement sensor, which includes a magnetic suspension bearing rotor device, a controller and a power amplifier, and is connected with the rotor in the magnetic suspension bearing rotor device and moves synchronously Thrust discs, sensor assemblies, fault diagnosis modules, and fault-tolerant control modules.

In this embodiment, the magnetic suspension bearing rotor device includes one axial magnetic bearing, two radial magnetic bearings and a rotor. Wherein, the magnetic suspension bearing rotor device may be one of a permanent magnet bias hybrid magnetic bearing rotor device and a pure electric excitation magnetic bearing rotor device.

Please refer to Figure 2-3, the sensor assembly includes several radial displacement sensors for measuring rotor displacement data and composite displacement sensors for measuring thrust disc displacement data; the composite displacement sensor and the radial The displacement sensors are arranged not in the same plane as each other.

In this embodiment, several radial displacement sensors are coplanarly arranged, and a plane Cartesian coordinate system is established on a plane perpendicular to the central axis of the rotor with the center of the rotor in the magnetic suspension bearing rotor device as the origin. The displacement sensor includes a first radial displacement sensor arranged in the positive and negative directions of the X axis and arranged symmetrically to each other, a second radial displacement sensor arranged in the positive and negative directions of the Y axis and arranged symmetrically to each other, and a third radial displacement sensor . The first connecting line formed by the third radial displacement sensor and the center of the rotor circle is set at an included angle with the X-axis and the Y-axis respectively, and the angles of the included angles are all greater than 0° and less than 90°, that is, the first A connecting line does not coincide with either the X-axis or the Y-axis.

In this embodiment, several grooves are arranged at equal intervals on the outer circumference of the thrust plate, and the composite displacement sensor is set on the outer side of the thrust plate in the radial direction for measuring the surface between it and the thrust plate. The radial displacement information of the thrust disc and the rotor rotational position angle information can be obtained at the same time. The angle between the second connecting line formed between the composite displacement sensor and the center of the thrust disc and the first connecting line formed between the third radial displacement sensor and the center of the rotor is greater than 0° and less than 90° °; the first connecting line and the second connecting line are arranged on different planes, do not intersect and are not parallel; the angles between the second connecting line and the X axis and the Y axis are both greater than 0° and less than 90°, that is , the second connecting line is not intersected with the X-axis and the Y-axis respectively and is not arranged in parallel.

In this embodiment, the fault-tolerant control module includes a filtering module and a displacement calculation module; the filtering module performs filtering processing on the measured value of the composite displacement sensor to obtain the effective displacement of the non-groove portion of the edge of the thrust plate; the displacement calculation The module obtains the displacement calculation value of each degree of freedom according to the sensor fault form.

Specifically, the thrust plate is provided with several groove structures, one of which is different in depth or width from the other grooves, and serves as a groove indicating the position angle of the rotor. The resulting measurement waveform is the displacement of the thrust plate and The square-wave-like waveform with the depth of the groove is superimposed, and the measurement data at the position where the sensor is facing the groove is compensated according to the depth of the groove opposed by the rotor rotation angle, so that a more accurate displacement of the thrust disc can be obtained.

The fault diagnosis module performs comprehensive sampling and analysis on the measured values of the composite displacement sensor and the radial displacement sensor to determine whether the sensor is faulty.

The controller calculates the control current signal according to the output displacement value of the fault-tolerant control module.

Driven by the control current signal, the power amplifying module generates a control current to control the movement of the rotor.

Example 1

Embodiment 1 of the present invention provides a method for fault-tolerant control using the above-mentioned magnetic suspension bearing displacement sensor fault-tolerant control system, firstly, according to the measured values of the rotor at different positions measured by the radial displacement sensor under normal circumstances, and its corresponding composite displacement The sensor effectively measures the sampling value, and establishes the corresponding relationship between the rotor displacement and the effective sampling value of the composite displacement sensor; then, after the fault occurs, the composite displacement sensor is filtered according to the above corresponding relationship and the normal sensor displacement measurement value to obtain the effective sampling value, Finally, the displacement of each degree of freedom is calculated according to different fault forms, and the control current signal is generated by the controller. The control current signal drives the power amplifier module to generate a control current, and the control current generates electromagnetic force through the magnetic bearing electromagnetic coil to control the rotor.

Specifically include the following steps:

S1, start the magnetic suspension bearing rotor device, the rotor and the thrust plate rotate synchronously, the sensor components measure the displacement data in real time, and obtain the radial displacement measurement value measured by the radial displacement sensor and the thrust measured by the composite displacement sensor under normal conditions The relationship between effective displacement measurements for the non-groove portion of the disk rim.

S2, the fault-tolerant control module intercepts and filters the displacement measurement value of the composite displacement sensor, according to the above relationship, judges the real-time sampling measurement value of the composite displacement sensor, and uses the fluctuation range of the effective measurement value of the non-groove part as the effective range ( According to the range of rotor displacement measured by the normal sensor, the effective range of the output voltage sampling value measured by the corresponding composite displacement sensor is obtained. Within the aforementioned effective range, output this value, otherwise, output the last sampled measurement value as the current measurement value, and finally perform low-pass filtering on the above-mentioned intercepted displacement value to obtain the radial displacement of the rotor;

When all the sensors are working normally, the measured values of the first radial sensor are marked as s ₁ and s ₃ , the measured values of the second radial sensor are marked as s ₂ and s ₄ , the measured values of the third radial sensor are marked as s ₅ , The measured value of the processed composite displacement sensor is denoted as s ₆ , and the relationship between the above measured value and the displacement values x and y in the X-axis and Y-axis directions is as follows:

s ₁ =x; s ₂ =-y; s ₃ =-x; s ₄ =y;

S3, classify the above-mentioned sensor fault forms, and calculate the degree of freedom displacement corresponding to the above-mentioned classified fault forms:

Note: In this embodiment, the first radial sensor is marked as the first radial sensor S ₁ and the first radial sensor S ₃ ; the second radial sensor is marked as the second radial sensor S ₂ and S ₄ ; The third radial sensor is denoted as third radial sensor S ₅ ; the composite sensor is denoted composite sensor S ₆ .

Fault state one,

One of the first radial sensor and the second radial sensor fails, or the two non-differential sensors fail, the third radial sensor and the compound displacement sensor are in any state, and the first radial sensor S ₁ and the second Take the fault of radial sensor _S2 as an example, the displacement is as follows:

x=-s ₃ ; y=s ₄ ;

Fault state two,

Two differential sensors of the first radial sensor and the second radial sensor are faulty, or three sensors are faulty, at least one of the third radial sensor and the composite displacement sensor is normal, and the first radial sensor S ₁ , the second radial sensor Take the failure of the second radial sensor S ₂ , the first radial sensor S ₃ , and the third radial sensor S ₅ as an example, and the displacements are as follows:

y＝s₄；

y=s ₄ ;

Fault state three,

Both the first radial sensor and the second radial sensor are faulty, the third radial sensor and the composite displacement sensor are normal, and the displacement is as follows:

S4. The controller module obtains a control current signal according to the displacement calculation value obtained by the above-mentioned fault-tolerant control module, drives the power amplification module to obtain a control current, and passes it into the electromagnetic coil in the magnetic suspension bearing rotor device to control the rotor.

To sum up, the present invention provides a fault-tolerant control system and control method for a magnetic suspension bearing displacement sensor. The system includes a magnetic suspension bearing rotor device, a controller and a power amplifier, a thrust plate connected with the rotor in the magnetic suspension bearing rotor device and moves synchronously, a sensor assembly, a fault diagnosis module and a fault-tolerant control module. The sensor assembly includes several radial displacement sensors for measuring rotor displacement data and a composite displacement sensor for measuring thrust disk displacement data; the composite displacement sensors and the radial displacement sensors are not coplanar with each other. In the present invention, the compound displacement sensor is used as a redundant displacement sensor by multiplexing, which saves the hardware cost, and the fault-tolerant control algorithm is easy to realize; by adding the compound displacement sensor and the function multiplexing between the sensor components, multiple redundancy is realized, Improve system reliability. By performing coordinate transformation on the displacement measurement values of two non-differential sensors, the displacement values of two radial degrees of freedom can be obtained, thereby realizing sensor fault-tolerant control and improving system reliability.

The above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced. Without departing from the spirit and scope of the technical solution of the present invention.

Claims (6)

1. A fault-tolerant control system of a magnetic suspension bearing displacement sensor, comprising a magnetic suspension bearing rotor device, a controller and a power amplifier, characterized in that: it also includes a thrust plate and a sensor assembly which are connected with the rotor in the magnetic suspension bearing rotor device and move synchronously , fault diagnosis module and fault-tolerant control module; The sensor assembly includes several radial displacement sensors for measuring rotor displacement data and composite displacement sensors for measuring thrust disk displacement data; the composite displacement sensors and the radial displacement sensors are not coplanar with each other; A plurality of said radial displacement sensors are coplanarly arranged, with the center of the rotor in the magnetic suspension bearing rotor device as the origin, and a plane Cartesian coordinate system is established on a plane perpendicular to the central axis of the rotor, and said radial displacement sensors include an X A first radial displacement sensor arranged symmetrically in the positive and negative directions of the axis, a second radial displacement sensor arranged in the positive and negative directions of the Y axis and symmetrical to each other, and a third radial displacement sensor; The first connecting line formed by the third radial displacement sensor and the center of the rotor does not coincide with the X axis or the Y axis; A number of grooves are arranged at equal intervals on the outer edge of the thrust plate, and the composite displacement sensor is set on the outside of the thrust plate in the radial direction for measuring the surface distance between it and the thrust plate, through the fault-tolerant control module The data processing of the rotor can obtain the rotor radial displacement information and the rotor rotation position angle information at the same time; The second connection line formed by the composite displacement sensor and the center of the thrust disc and the first connection line formed by the third radial displacement sensor and the center of the rotor are arranged on different planes, neither parallel nor intersecting; the second connection The lines are neither parallel nor intersecting the X and Y axes. 2. the magnetic suspension bearing displacement sensor fault-tolerant control system according to claim 1, is characterized in that: described fault-tolerant control module comprises filter module and displacement calculation module; Described filter module carries out filtering process to the measured value of composite displacement sensor, obtains The effective displacement of the non-groove part of the edge of the thrust plate; the displacement calculation module obtains the displacement calculation value of each degree of freedom according to the fault form of the sensor. 3. The magnetic suspension bearing displacement sensor fault-tolerant control system according to claim 1, characterized in that: said fault diagnosis module carries out comprehensive sampling analysis to the measured values of said composite displacement sensor and said radial displacement sensor, and judges whether the sensor is malfunction. 4. The fault-tolerant control system of the magnetic suspension bearing displacement sensor according to claim 1, wherein the magnetic suspension bearing rotor device is one of a permanent magnet bias hybrid magnetic bearing rotor device and a pure electric excitation magnetic bearing rotor device. 5. A fault-tolerant control method for a magnetic suspension bearing displacement sensor, characterized in that: using the magnetic suspension bearing displacement sensor fault-tolerant control system according to any one of claims 1 to 4 to perform fault-tolerant control, comprising the following steps: S1, start the magnetic suspension bearing rotor device, the rotor and the thrust plate rotate synchronously, the sensor components measure the displacement data in real time, and obtain the radial displacement measurement value measured by the radial displacement sensor and the thrust measured by the composite displacement sensor under normal conditions Corresponding relationship of the effective displacement measurement value of the non-groove part of the edge of the disk; S2, the fault-tolerant control module intercepts and filters the displacement measurement value of the composite displacement sensor, and judges the real-time sampling measurement value of the composite displacement sensor according to the above relationship, taking the fluctuation range of the effective measurement value of the non-groove part as the effective range, If it is within the aforementioned effective range, output this value, otherwise, output the last sampled measurement value as the current measurement value, and finally perform low-pass filtering on the above-mentioned intercepted displacement value to obtain the radial displacement of the rotor; When all the sensors are working normally, the measured values of the first radial sensor are marked as s ₁ and s ₃ , the measured values of the second radial sensor are marked as s ₂ and s ₄ , the measured values of the third radial sensor are marked as s ₅ , The measured value of the processed composite displacement sensor is denoted as s ₆ , and the relationship between the above measured value and the displacement values in the X-axis and Y-axis directions is as follows:

; S3, classify the sensor fault form, and calculate the degree of freedom displacement corresponding to the above-mentioned classified fault form; S4, the controller obtains a control current signal according to the displacement calculation value obtained by the fault-tolerant control module, drives the power amplification module to obtain the control current, and passes it into the electromagnetic coil in the magnetic suspension bearing rotor device to control the rotor. 6. The fault-tolerant control method of the magnetic suspension bearing displacement sensor according to claim 5, characterized in that: the first radial sensor is marked as the first radial sensor S ₁ and the first radial sensor S ₃ ; the second radial sensor The sensors are marked as the second radial sensor S ₂ and the second radial sensor S ₄ ; the third radial sensor is marked as the third radial sensor S ₅ ; the compound sensor is marked as compound sensor S ₆ ; The specific process of sensor fault form classification and displacement calculation in step S3 is: Fault state one, One of the first radial sensor and the second radial sensor fails, or the two non-differential sensors fail, the third radial sensor and the compound displacement sensor are in any state, and the first radial sensor S ₁ and the second Take the fault of radial sensor _S2 as an example, the displacement is as follows:

Fault state two, Two differential sensors of the first radial sensor and the second radial sensor are faulty, or three sensors are faulty, at least one of the third radial sensor and the composite displacement sensor is normal, and the first radial sensor S ₁ , the second radial sensor Take the failure of the second radial sensor S ₂ , the first radial sensor S ₃ , and the third radial sensor S ₅ as an example, and the displacements are as follows:

Fault state three, Both the first radial sensor and the second radial sensor are faulty, the third radial sensor and the composite displacement sensor are normal, and the displacement is as follows:

.

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