A bearingless motor radial displacement detection error compensation method

Abstract

The application discloses a bearingless motor radial displacement detection error compensation method, and aims at the bearingless motor rotor suspension position eccentricity problem caused by non-ideal factors such as process assembly error, inconsistent device characteristics and device temperature drift, and performs self-adaptive compensation on the rotor eccentricity in the motor suspension state, and realizes the suspension of the optimal position (stator geometric center) of the rotor. The method considers that the position of the rotor in the minimum state of the anti-eccentric suspension current is the stator geometric center, takes the anti-eccentric suspension current of the bearingless motor as an observation object, realizes the self-adaptive compensation of the bearingless motor rotor suspension position eccentricity. The observation quantity is convenient to obtain, can be realized through a simple low-pass filter link, and can better reflect the rotor suspension position eccentricity, and the algorithm is simple to realize, and the system structure is simple.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bearingless motor driving, and particularly relates to a bearingless motor radial displacement detection error compensation method. BACKGROUND

[0002] Compared with a traditional mechanical bearing motor, a bearingless motor has no mechanical wear, and has the advantages of small size, easy maintenance, long service life, high precision and the like, and is widely applied to high-performance occasions such as centrifuges, sealed pumps, semiconductor industries, life sciences and aerospace. As an important part of a bearingless motor control system, the accuracy and real-time performance of a rotor radial displacement sensing detection link are important guarantees for realizing high-performance operation of the bearingless motor. However, due to the existence of non-ideal factors such as process assembly errors, inconsistent device characteristics and device temperature drift, the center detected by the radial displacement sensor does not coincide with the geometric center of the stator of the bearingless motor, that is, the rotor suspension position is eccentric, which further leads to additional loss of the system and reduction of suspension performance. Therefore, for the foregoing rotor suspension position eccentricity problem, targeted compensation measures need to be implemented to ensure high-performance operation of the bearingless motor. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a bearingless motor radial displacement detection error compensation method, which is aimed at the rotor suspension position eccentricity problem of a bearingless motor caused by non-ideal factors such as process assembly errors, inconsistent device characteristics and device temperature drift, and which is aimed at self-adaptive compensation of rotor eccentricity in a motor suspension state to realize suspension of the rotor at an optimal position (the geometric center of the stator). The method considers that the position of the rotor in the state of minimum anti-eccentric suspension current is the geometric center of the stator, takes the anti-eccentric suspension current of the bearingless motor as an observation object, realizes self-adaptive compensation of the rotor suspension position eccentricity of the bearingless motor, and has the advantages of being easy to obtain, being realized through a simple low-pass filtering link, and being able to better reflect the rotor suspension position eccentricity, and has the advantages of simple algorithm implementation and simple system structure.

[0004] The present application adopts the following technical solutions to solve the above technical problems:

[0005] A bearingless motor radial displacement detection error compensation method takes the anti-eccentric suspension current of the bearingless motor as an observation object, compensates for the rotor suspension position eccentricity in a bearingless motor suspension state, and realizes suspension of the rotor at an optimal position (the geometric center of the stator). The implementation steps of the scheme are as follows:

[0006] Step S1: First, an eccentricity compensation initial vector is actively applied

[0007] Step S2: Calculate the eccentricity compensation vector at the current time

[0008] Step S3: Obtain the bearingless motor suspension current vector at the current time and complete the suspension closed-loop control.

[0009] Step S4: Perform mathematical processing on the obtained bearingless motor suspension current vector to obtain the bearingless motor anti-disturbance suspension current amplitude at the current time and the anti-eccentricity suspension current amplitude

[0010] Step S5: Obtain the bearingless motor tracking transformation matrix P at the current time t (k) and the tracking step matrix dP xy (k);

[0011] Step S6: Repeat steps S2 to S5 to obtain the rotor eccentricity compensation vector in real time and apply it to the bearingless motor system to compensate for the rotor suspension position eccentricity until the rotor is stably operated at the optimal point (the geometric center of the stator).

[0012] Further, as a bearingless motor radial displacement detection error compensation method of the present application, the setting of the eccentricity compensation initial vector in step S1 is not unique and can be set in any direction according to actual needs.

[0013] Further, as a bearingless motor radial displacement detection error compensation method of the present application, the calculation method of the current time eccentricity compensation vector in step S2 is the accumulation of the product of the tracking step matrix dP xy (k-1) obtained at the previous time and the unit vector , and the corresponding formula can be written as

[0014] Further, as a bearingless motor radial displacement detection error compensation method of the present application, the bearingless motor suspension current vector in step S3 can be obtained by sampling the current sensor, but is not limited to this.

[0015] Further, as a bearingless motor radial displacement detection error compensation method of the present application, the bearingless motor suspension closed-loop control system in step S3 can adopt a typical control structure of displacement outer loop-current inner loop, but is not limited to this. The basic principle is to subtract the actual sampling value of the bearingless motor radial displacement vector set value from it, and consider the effect of the eccentricity compensation vector , and send it to the displacement regulator to obtain the bearingless motor radial suspension force set value Further, the suspension current vector setting value is obtained through the bearingless motor decoupling model and the suspension current vector actual sampling value The difference is sent into the current regulator to obtain the suspension command voltage vector Finally, the inverter switching signal S is obtained through the modulation link L to realize the suspension closed-loop control of the bearingless motor.

[0016] Further, as a bearingless motor radial displacement detection error compensation method of the application, the bearingless motor suspension current vector in step S4 can be divided into anti-disturbance suspension current vector and anti-eccentricity suspension current vector The former is used to generate the radial suspension force part resisting the external disturbance force, and the latter is used to generate the radial suspension force part resisting the eccentric magnetic pull; for the latter anti-eccentricity suspension current vector, the more serious the eccentricity of the rotor suspension position is, the greater the amplitude of the suspension current vector required to resist the eccentric magnetic pull is, that is, the amplitude of the anti-eccentricity suspension current vector is greater, and when the rotor suspension position is not eccentric, that is, the rotor is suspended at the geometric center of the stator, the amplitude of the anti-eccentricity suspension current is the smallest.

[0017] Further, as a bearingless motor radial displacement detection error compensation method of the application, the anti-disturbance suspension current vector in step S4 and the anti-eccentricity suspension current vector For the former, since the rotor of the bearingless motor is affected by a series of unknown disturbance forces, even in a stable state, the amplitude of the anti-disturbance suspension current is constantly changing; the difference is that for the latter, the amplitude of the anti-eccentricity suspension current is theoretically a constant value in a stable state, that is, the addition of a low-pass filter link can realize the extraction of the anti-eccentricity suspension current component at the current time, and the corresponding formula can be written as

[0018]

[0019] Further, as a bearingless motor radial displacement detection error compensation method of the application, the current time bearingless motor tracking step matrix dP in step S5 xy (k) is determined by the quadrant of the anti-eccentricity suspension vector in the rotating coordinate system, where the tracking step matrix dP xy and the tracking transformation matrix P t are both 2×2 matrices.

[0020] Further, as a bearingless motor radial displacement detection error compensation method of the application, in order to prevent the bearingless motor suspension position optimal point fluctuation phenomenon in step S5, that is, when the minimum anti-eccentric suspension current vector amplitude is tracked, the eccentric compensation vector In the optimal point fluctuation, the rotor will fluctuate even in the stable state, and the count threshold c is set Th ; Each fluctuation of the eccentric compensation vector will be recorded in the fluctuation count value c, and when the fluctuation count value c is greater than the count threshold c Th , the rotor suspension position eccentric compensation method will stop, that is, the bearingless motor tracking step matrix dP xy (k) is 0.

[0021] Further, as a bearingless motor radial displacement detection error compensation method of the application, in order to ensure that the rotor suspension position eccentric problem appears again, the proposed suspension position eccentric compensation method can be restarted normally, and the compensation current threshold i Th is set When the anti-eccentric suspension current amplitude at the current moment is greater than the minimum value of the anti-eccentric suspension current amplitude in the algorithm running process , the proposed suspension position eccentric compensation method will be restarted.

[0022] Compared with the prior art, the application has the following technical effects:

[0023] 1. The bearingless motor radial displacement detection error compensation method provided by the application can adaptively compensate the rotor eccentricity in the motor suspension state, and realize the suspension of the optimal position (stator geometric center) of the rotor, for the bearingless motor rotor suspension position eccentric problem caused by process assembly error, inconsistent device characteristics, and device temperature drift and other non-ideal factors.

[0024] 2. The bearingless motor radial displacement detection error compensation method provided by the application selects the anti-eccentric suspension current of the bearingless motor as the observation quantity, which is easy to obtain and can better reflect the rotor eccentricity.

[0025] 3. The bearingless motor radial displacement detection error compensation method provided by the application has simple algorithm implementation, does not need to rely on any parameters, and has simple system structure. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The application is a bearingless motor radial displacement detection error compensation method flowchart.

[0027] Figure 2 The application is the selection rule of the tracking transformation matrix. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described in detail below with reference to the drawings:

[0029] The present application can be implemented in many different forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0030] The present application discloses a kind of bearingless motor radial displacement detection error compensation method.For the bearingless motor rotor suspension position eccentric problem caused by process assembly error, device characteristic inconsistency and device temperature drift etc.Non-ideal factors, the rotor eccentricity of motor suspension state is self-adaptive compensation, the optimal position (stator geometric center) of rotor is realized.Suspension.This method considers that the position of rotor in the minimum state of anti-eccentric suspension current is stator geometric center, realizes the adaptive compensation of bearingless motor rotor suspension position eccentricity with bearingless motor anti-eccentric suspension current as observation object.The observation quantity is easy to obtain, and can be realized by designing simple low-pass filter link, and can better reflect rotor suspension position eccentricity, algorithm realization is simple, and system structure is simple.The implementation steps of the scheme are as follows:

[0031] Step S1: first actively exert eccentricity compensation initial vector

[0032] Step S2: calculate the eccentricity compensation vector of current time

[0033] Step S3: obtain the bearingless motor suspension current vector of current time And complete suspension closed-loop control;

[0034] Step S4: the bearingless motor suspension current vector obtained Mathematical treatment is carried out, and the anti-disturbance suspension current amplitude of bearingless motor at current time And anti-eccentric suspension current amplitude

[0035] Step S5: obtain the bearingless motor tracking transformation matrix P t (k) and tracking step matrix dP xy (k) of current time;

[0036] Step S6: repeat step S2 to step S5, real-time acquisition rotor eccentricity compensation vector And exert on bearingless motor system, compensate for rotor suspension position eccentricity, until realizing the stable operation of rotor at optimal point (stator geometric center).

[0037] Step S1: the eccentricity compensation initial vector The setting is not unique, and any direction can be set according to actual needs.

[0038] Step S2: the current time eccentricity compensation vector The calculation method is the accumulation of the product of the tracking step matrix dP xy (k-1) obtained at the last time and the unit vector The corresponding formula can be written as

[0039] Step S3: the bearingless motor suspension current vector It can be obtained by sampling the current sensor, but is not limited to this.

[0040] The bearingless motor suspension closed-loop control system in step S3 can adopt, but is not limited to, the typical control structure of displacement outer loop-current inner loop, and the basic principle is to subtract the actual sampling value of the bearingless motor radial displacement vector set value from the bearingless motor radial displacement vector set value , and consider the effect of the eccentricity compensation vector , and send it to the displacement regulator to obtain the bearingless motor radial suspension force set value , and then obtain the suspension current vector set value through the bearingless motor decoupling model, and subtract the actual sampling value of the suspension current vector from the suspension current vector set value to send it to the current regulator to obtain the suspension command voltage vector Finally, the inverter switching signal S is obtained through the modulation link L to realize the suspension closed-loop control of the bearingless motor.

[0041] The bearingless motor suspension current vector in step S4 can be divided into the disturbance-resistant suspension current vector and the anti-eccentricity suspension current vector The former is used to generate a part of the radial suspension force to resist external disturbance forces, and the latter is used to generate a part of the radial suspension force to resist the eccentric magnetic pull; for the latter anti-eccentricity suspension current vector, the more serious the eccentricity of the rotor suspension position, the greater the amplitude of the additional suspension current vector required to resist the eccentric magnetic pull, that is, the greater the amplitude of the anti-eccentricity suspension current vector , and when the rotor suspension position is not eccentric, that is, the rotor is suspended at the geometric center of the stator, the amplitude of the anti-eccentricity suspension current is the smallest.

[0042] The disturbance-resistant suspension current vector and the anti-eccentricity suspension current vector For the former, since the rotor of the bearingless motor is affected by a series of unknown disturbance forces, even in a stable state, the amplitude of the anti-interference suspension current Also in constant change; the difference is that for the latter, the anti-eccentric suspension current amplitude In the steady state, it is theoretically a constant value, that is, the current anti-eccentric suspension current component at the current moment can be extracted by adding a low-pass filter (LPF), and the corresponding formula can be written as

[0043] The tracking step matrix dP of the bearingless motor at the current moment in step S5 xy (k) is determined by the quadrant of the rotating coordinate system in which the anti-eccentric suspension vector difference between the current moment and the previous moment is located, wherein the tracking step matrix dP xy and the tracking transformation matrix P t are both 2×2 matrices.

[0044] In step S5, in order to prevent the fluctuation of the optimal point of the bearingless motor suspension position, that is, the compensation method proposed in the tracking of the minimum anti-eccentric suspension current vector amplitude , the eccentric compensation vector fluctuates around the optimal point, causing the rotor to fluctuate even in a steady state, a count threshold c Th is set; each fluctuation of the eccentric compensation vector is recorded in the fluctuation count value c, and when the fluctuation count value c is greater than the count threshold c Th , the rotor suspension position eccentric compensation method proposed will stop, that is, the tracking step matrix dP of the bearingless motor at the current moment xy (k) is 0.

[0045] In step S5, in order to ensure that the rotor suspension position eccentric problem appears again, the proposed suspension position eccentric compensation method can be restarted normally, a compensation current threshold i Th is set, and when the anti-eccentric suspension current amplitude at the current moment is greater than the minimum value of the anti-eccentric suspension current amplitude during the running of the algorithm , the proposed suspension position eccentric compensation method will be restarted.

[0046] Figure 1 is a flow chart of a bearingless motor radial displacement detection error compensation method, the tracking step matrix dP xy and the tracking transformation matrix P t are respectively a 2×2 tracking step matrix and a tracking transformation matrix:

[0047]

[0048] wherein dP 11 , dP 12 , dP 21 , dP 22 , P t11, P t12 , P t21 , P t22 is the value of each cell in the matrix.

[0049] Figure 2 is the selection of the tracking transformation matrix, where and are the rotation coordinate system of the stationary coordinate system and the suspension control subsystem, respectively.

[0050] In combination Figure 1 with Figure 2 , the specific process of the radial displacement detection error compensation method of the bearingless motor is described in detail below. First, the initial vector of eccentricity compensation is set at the beginning of the algorithm Then, the calculation of the current time eccentricity compensation vector is performed. The calculation method of the current time eccentricity compensation vector is the accumulation of the product of the tracking step matrix dP xy (k-1) obtained at the last time and the unit vector , and the corresponding formula can be written as Next, the current time bearingless motor suspension current vector is obtained and the suspension closed-loop control is completed. Then, the obtained bearingless motor suspension current vector is mathematically processed to obtain the current time bearingless motor anti-disturbance suspension current amplitude and the anti-eccentricity suspension current amplitude The aforementioned bearingless motor suspension current vector can be divided into an anti-disturbance suspension current vector and an anti-eccentricity suspension current vector The former is used to generate a radial suspension force part that resists external disturbance forces, and the latter is used to generate a radial suspension force part that resists eccentric magnetic pull; for the latter anti-eccentricity suspension current vector, the more serious the eccentricity of the rotor suspension position, the greater the amplitude of the additional suspension current vector required to resist the eccentric magnetic pull, i.e., the greater the anti-eccentricity suspension current vector amplitude When the rotor is suspended at the geometric center of the stator, the amplitude of the anti-eccentricity suspension current is also the smallest. Based on this, for the anti-disturbance suspension current vector , since the rotor of the bearingless motor is affected by a series of unknown disturbance forces, even in a stable state, the anti-disturbance suspension current amplitude is constantly changing; the difference is that for the anti-eccentricity suspension current vector , the anti-eccentricity suspension current amplitude is theoretically a constant value in a stable state, i.e., the addition of a low-pass filter element can realize the extraction of the current time anti-eccentricity suspension current component, and the corresponding formula can be written as Finally, the tracking transformation matrix P of the bearingless motor at the current time is obtained t (k) and the tracking step matrix dP xy (k) are obtained as the basis for the calculation of the eccentricity compensation vector at the next time.

[0051] In order to further simplify the compensation method, dP 12 = dP 21 = P t12 = P t21 = 0, dP 11 = dP 12 = dP, where dP is the compensation step. P t11 and the value of P t21 and the anti-eccentric suspension current vector difference are related to the quadrant of the rotating coordinate system, and the specific relationship is shown in Figure 2 Taking the case in Figure 2 , the anti-eccentric suspension current vector difference is located in the second quadrant of the rotating coordinate system, at this time P t11 = 1, P t21 = -1, that is, the tracking transformation matrix can be written as:

[0052]

[0053] The bearingless motor radial displacement detection error compensation method of the application further sets a count threshold and a compensation current threshold, wherein the setting of the count threshold c Th is to prevent the optimal point fluctuation phenomenon of the application, that is, when the minimum anti-eccentric suspension current vector amplitude is tracked, the eccentricity compensation vector fluctuates around the optimal point, resulting in fluctuations of the rotor even in a stable state. Although this is only a fluctuation in the compensation size, the optimal point fluctuation phenomenon has a non-negligible impact on the suspension performance of the bearingless motor under high-speed running conditions. In addition, the setting of the current compensation threshold i Th is to restart the compensation method when the rotor suspension position eccentricity appears again.

[0054] It is worth mentioning that the bearingless motor radial displacement detection error compensation method of the application can simplify the design of the displacement regulator, and the integral element in the traditional PID-based displacement regulator is no longer needed, which can avoid problems such as integral parameter selection and integral saturation. The bearingless motor radial displacement detection error compensation method of the application can achieve full compensation of the rotor suspension position eccentricity of the bearingless motor without relying on any parameters, so that the rotor can be stably suspended at the optimal point (the geometric center of the stator). The scheme is simple in structure and easy to implement, and the compensation method is universal and suitable for actual engineering production.

[0055] As used herein, and unless otherwise indicated, all terms have their ordinary meanings. It should be understood that any definitions are to be used as elucidated herein and should not be taken in any restrictive sense unless expressly defined.

[0056] The above description is only specific embodiments of the present application. It should be understood that the above description is only a specific embodiment of the present application. It should be understood that any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for compensating for radial displacement detection errors in a bearingless motor, characterized by, Aiming at the problem of the bearingless motor rotor suspension position eccentricity caused by the process assembly error, the inconsistent device characteristics and the device temperature drift and other non-ideal factors, the rotor eccentricity in the motor suspension state is adaptively compensated to realize the optimal position suspension of the rotor. This method considers that the position of the rotor in the minimum anti-eccentric suspension current state is the geometric center of the stator. The anti-eccentric suspension current of the bearingless motor is taken as the observation object to realize the adaptive compensation of the bearingless motor rotor suspension position eccentricity. The observation quantity is obtained through the design of a low-pass filter link, and can reflect the rotor suspension position eccentricity. The implementation steps of the method are as follows: Step S1 : First, an eccentricity compensation initial vector is actively applied ; Step S2: Calculate the eccentricity compensation vector at the current time ; Step S3: obtaining the bearingless motor suspension current vector at the current moment and completing the suspension closed-loop control; Step S4: obtaining the bearingless motor suspension current vector of the current moment Step S3: performing mathematical processing to obtain the bearingless motor anti-disturbance suspension current amplitude of the current moment Step S2: obtaining the bearingless motor anti-eccentricity suspension current amplitude ; Step S5: obtaining a bearingless motor tracking transformation matrix at a current time and a tracking step matrix ; Step S6: repeat steps S2 to S5 to obtain the rotor eccentricity compensation vector in real time And applied to bearingless motor system, the rotor suspension position eccentricity is compensated until the stable operation of the rotor at the optimal point is realized. The bearingless motor suspension closed-loop control system in the step S3 adopts a typical control structure of displacement outer loop-current inner loop, and the basic principle is to set a radial displacement vector value of the bearingless motor , to subtract the actual sampling value , and consider the effect of an eccentric compensation vector , and send it to a displacement regulator to obtain a radial suspension force set value of the bearingless motor , and then obtain a suspension current vector set value through a bearingless motor decoupling model , subtract the actual sampling value of the suspension current vector , and send it to a current regulator to obtain a suspension instruction voltage vector , and finally obtain an inverter switching signal through a modulation link to realize the suspension closed-loop control of the bearingless motor.

2. The method of claim 1, wherein, The step S1 eccentricity compensation initial vector Any direction can be set according to actual needs.

3. The method of claim 1, wherein, The current time eccentricity compensation vector in step S2 The calculation method is the tracking step matrix obtained at the last time The product of the unit vector The accumulation, and the corresponding formula is written as .

4. The method of claim 1, wherein, The bearingless motor suspension current vector in the step S3 is obtained by sampling with a current sensor.

5. The method of claim 1, wherein, The bearingless motor suspension current vector in the step S4 is divided into a disturbance-resistant suspension current vector and an anti-eccentricity suspension current vector , the disturbance-resistant suspension current vector is used to generate a radial suspension force component resisting external disturbance force, the anti-eccentricity suspension current vector is used to generate a radial suspension force component resisting eccentric magnetic pull force; the more serious the eccentricity of the rotor suspension position, the greater the amplitude of the additional suspension current vector required to resist the eccentric magnetic pull force, i.e. the amplitude of the anti-eccentricity suspension current vector is greater; when the rotor suspension position is not eccentric, i.e. the rotor is suspended at the geometric center of the stator, the amplitude of the anti-eccentricity suspension current reaches a minimum.

6. The method of claim 1, wherein, The anti-disturbance levitation current vector in step S4 The anti-eccentricity levitation current vector For the anti-disturbance levitation current vector Since the rotor of the bearingless motor is affected by the disturbance force, the anti-disturbance levitation current amplitude is constantly changing even in the steady state; for the anti-eccentricity levitation current vector , the anti-eccentricity levitation current amplitude is a constant value in the steady state, and a low-pass filter (LPF) is added to extract the anti-eccentricity levitation current component at the current time, and the corresponding formula is written as .

7. The method of claim 1, wherein, the tracking step matrix of the bearingless motor at the current time instant is determined by the quadrant of the rotating coordinate system in which the difference between the anti-eccentric suspension vector at the current time instant and at the previous time instant lies, wherein the tracking step matrix and the tracking transformation matrix are both 2x2 matrices.

8. The method of claim 1, wherein, The step S5 method is provided with a count threshold value ; each fluctuation of the eccentricity compensation vector will be recorded into a fluctuation count value , when the fluctuation count value is greater than the count threshold value , the rotor suspension position eccentricity compensation method stops, and the bearingless motor tracking step matrix at the current time is 0.

9. The method of claim 1, wherein, The method in the step S5 is provided with a compensation current threshold value , the current time anti-eccentric suspension current amplitude is greater than the minimum value of the anti-eccentric suspension current amplitude in the algorithm running process , the suspension position eccentricity compensation method will be restarted.

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