Dual three-phase permanent magnet synchronous motor turn-to-turn short circuit fault adaptive diagnosis method

Abstract

The invention relates to a dual three-phase permanent magnet synchronous motor turn-to-turn short circuit fault adaptive diagnosis method, and belongs to the technical field of motor fault diagnosis. A mathematical model and an adjustable model of a dual three-phase motor turn-to-turn short circuit fault are established, space vector decoupling transformation of a multi-phase motor is combined, a short circuit fault component is introduced into a harmonic sub-plane of a stator voltage equation, and a fault characteristic value is designed by using an x-y current residual error of a real motor and the adjustable model. A fundamental wave amplitude is extracted through orthogonal Fourier transform to serve as a fault degree feature, a model reference adaptive law of an observer and a segmented PI regulator based on a mapping relation between a short-circuit current residual error and a fault turn ratio is constructed, PI parameters are dynamically adjusted according to the rotating speed and the load working condition, and adaptive feedback estimation of the short-circuit turn ratio is achieved. The fault feature extraction precision and real-time performance are improved, the fault-tolerant algorithm is simplified, the parameter design of the disturbance observer is optimized, the problem of diagnosis distortion caused by working condition changes is solved, and a motor monitoring optimization solution is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor fault diagnosis, and relates to an adaptive diagnosis method for inter-turn short circuit faults of a dual three-phase permanent magnet synchronous motor. Background Art

[0002] Due to its advantages such as high efficiency, high power density, and strong fault tolerance, dual three-phase permanent magnet synchronous motors have been widely used in high-reliability applications. However, various fault problems will inevitably occur during the operation of the motor, and the inter-turn short circuit fault is one of the most common fault types. The inter-turn short circuit fault will introduce a short circuit loop, resulting in changes in the motor parameter matrix. The mathematical model during normal operation of the motor will introduce additional short circuit components. At the same time, the short circuit current will also cause electromagnetic torque pulsation, resulting in a decrease in the output efficiency of the motor. Therefore, for dual three-phase motors, it is very necessary to diagnose the degree of inter-turn short circuit faults in real time and online.

[0003] When traditional inter-turn short circuit fault diagnosis methods estimate the fault degree, affected by factors such as fault significance and feature extraction frequency, the detection accuracy is prone to fluctuate with changes in motor operating conditions, and it is difficult to maintain stable diagnostic accuracy. To solve this problem, new diagnostic strategies with diagnostic accuracy independent of operating conditions need to be applied.

[0004] Regarding the problem of the diagnostic accuracy of the degree of inter-turn short circuit faults of dual three-phase permanent magnet synchronous motors fluctuating with changes in motor operating conditions, there are already some invention patents. For example: Patent No. CN118858934A discloses a method for diagnosing inter-turn short circuit faults of a dual three-phase permanent magnet synchronous motor. By establishing a mathematical model of inter-turn short circuit faults of a dual three-phase permanent magnet synchronous motor in the rotating coordinate system and comparing it with the normal motor model, the fault characteristics can be analyzed. However, when extracting fault characteristics and performing coordinate transformation and filter processing, this method still has the problem of introducing more advanced signal processing algorithms to improve the sensitivity and timeliness of fault diagnosis. Patent No. CN118826586A discloses a method for diagnosing inter-turn short circuit faults and fault-tolerant control of a five-phase permanent magnet synchronous motor. This method extracts fault characteristic information through a preset disturbance observer model and implements precise fault-tolerant control based on the fault characteristic information. However, in terms of the fault characteristic information extraction method, this method still has the problem of further studying and improving the parameter design and stability analysis method of the disturbance observer model to improve the extraction accuracy and real-time performance of fault characteristic information.

[0005] The existing technologies have the following disadvantages:

[0006] 1. When traditional inter-turn short circuit fault diagnosis methods estimate the fault degree, affected by factors such as fault significance and feature extraction frequency, the detection accuracy is prone to fluctuate with changes in motor operating conditions, and it is difficult to maintain stable diagnostic accuracy.

[0007] 2. The existing fault feature extraction methods have the problem of introducing more advanced signal processing algorithms to improve the sensitivity and timeliness of fault diagnosis.

[0008] 3. The existing disturbance observer models have problems in further research and improvement in terms of parameter design and stability analysis, which affect the extraction accuracy and real-time performance of fault feature information.

[0009] 4. The existing technologies lack an adaptive observer for the short-circuit turn ratio of motors, unable to extract the fundamental wave characteristic parameters of short-circuit current online, and it is difficult to achieve closed-loop tracking estimation of the fault degree.

[0010] 5. The existing technologies lack a model reference adaptive law based on a segmented PI regulator, unable to achieve adaptive feedback regulation of the parameters to be estimated, and unable to ensure that the diagnostic accuracy is not affected by changes in motor operating conditions. Summary of the Invention

[0011] In the existing technologies, there is a problem that the diagnostic accuracy is prone to fluctuate with changes in motor operating conditions and it is difficult to maintain stable diagnostic accuracy. Therefore, to solve the above problems, the present invention provides an adaptive diagnosis method for inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor.

[0012] To achieve the above object, the present invention provides the following technical solutions:

[0013] An adaptive diagnosis method for inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor, characterized by comprising the following steps:

[0014] Step 1: Establish a mathematical model and an adjustable model under the condition of inter-turn short-circuit faults of a dual three-phase motor, and establish a dual three-phase motor fault model according to the space vector decoupling transformation of a multi-phase motor;

[0015] Step 2: Introduce short-circuit fault components in the d-q and x-y harmonic sub-planes of the stator voltage equation; use the x-y current difference component between the actual motor and the adjustable model to design a characteristic value reflecting the degree of turn short fault;

[0016] Step 3: Establish an observer from the short-circuit current residual component to the fault turn ratio to design a feedback control law;

[0017] Step 4: Establish a model reference adaptive law based on a segmented proportional-integral (PI) regulator to adaptively feedback-regulate the parameters to be estimated.

[0018] Further, the A-phase fault of the dual three-phase motor fault model in Step 1 is expressed by the following formula:

[0019]

[0020] Among them, u d is the direct-axis voltage; u q is the quadrature-axis voltage; u x , u y are harmonic voltages; R s is the stator resistance; i d is the direct-axis current; i q is the quadrature-axis current; i x , i y are harmonic currents; i F is the short-circuit current; θ is the synchronous electrical angle; ω is the synchronous angular velocity L d is the direct-axis inductance; L q is the quadrature-axis inductance; L z is the stator leakage inductance; ψ f is the permanent magnet flux linkage; σ is the short-circuit fault turn ratio.

[0021] Furthermore, the u x and u y harmonic voltages in the A-phase fault of the dual three-phase motor fault model are expressed as the following formula:

[0022]

[0023] Among them, the symbol "" represents the motor parameters of the adjustable model, is the current estimated by the adjustable model;

[0024] The differential signal is expressed as the following formula:

[0025]

[0026] Among them, Δi x is the x-axis current residual; Δi y is the y-axis current residual; d is the differential symbol;

[0027] From formulas (1) to (3), the mapping relationship between the differential signal and the short-circuit turn ratio σ is obtained, which is expressed as the following formula:

[0028]

[0029] Furthermore, the specific steps of step 2 include:

[0030] Calculate the x-y current difference component between the real motor and the adjustable model;

[0031] Simplify the feature extraction function of the fault current, and use the primary component of the fault current as the object to design the eigenvalue of the fault degree;

[0032] According to the relevant conclusions of the orthogonal Fourier transform, extract the amplitude information of the fundamental wave component in the x-y current difference component as the characteristic value representing the fault degree.

[0033] Further, step 2 further includes:

[0034] Extract i according to the following relationship x The amplitude information of the fundamental wave component in the current residual:

[0035]

[0036] In the formula, A1 and A2 are the characteristic parameters of the orthogonal Fourier transform, and FI is the fault characteristic value;

[0037] Among them,

[0038]

[0039] In the formula, x1 is the subscript of the fundamental wave component, k = 1, 2, 3,...;

[0040] The FI reaction model refers to the input deviation of the fault harmonic current between the adaptive system adjustment model and the real motor.

[0041] Further, step 3 specifically includes:

[0042] Apply a certain load torque TL to the tow motor. After the motor runs to a stable speed, introduce a short-circuit fault with a given turn ratio in phase A;

[0043] Collect the x-y axis current signals of the real motor and the current signal residuals of the adjustable model to generate the fault characteristic value FI as the input of the adaptive law of the observer.

[0044] Further, step 4 specifically includes:

[0045] Collect the speed and load information of the motor, and judge in real time which segmented interval the current working condition is in;

[0046] Select the corresponding PI control parameters to adjust the short-circuit turn ratio estimation.

[0047] Further, the segmented PI regulator in step 4 mainly includes:

[0048] Input end, the current residual signal in the xy subspace between the adjustable model and the real motor;

[0049] Output end, the estimated value of the short-circuit turn ratio;

[0050] Control law part, composed of a segmented PI regulator;

[0051] The control law part collects the speed and load signals of the motor, determines the segmented interval of the current working condition in real time, and selects the corresponding PI control parameters to adjust the short-turn ratio estimation.

[0052] Furthermore, the segmented PI regulator conducts grid division on the working condition range within the boundary, and formulates the regulator parameters of the working points in other grids by linear interpolation method to maintain fault tracking under different working conditions.

[0053] Compared with the prior art, the present invention provides a method for adaptive diagnosis of inter-turn short circuit faults of a dual three-phase permanent magnet synchronous motor, which has the following beneficial effects:

[0054] 1. The diagnostic accuracy is improved and the diagnostic error is reduced. The present invention designs a characteristic value that can reflect the degree of turn short fault by using the current difference component between the real motor and the adjustable model, and realizes the adaptive feedback adjustment of the parameter to be estimated based on the model reference adaptive law of the segmented PI regulator. Within the working condition range of ±40% speed / load of the rated working point of the controlled object, the diagnostic error of the fault degree is reduced by about 20 percentage points, solving the problem that the diagnostic accuracy is distorted with the change of the motor working condition in the prior art;

[0055] 2. The extraction accuracy and real-time performance of fault characteristic information are improved. The present invention simplifies the characteristic extraction function of the fault current, selects the primary component mainly contained in the fault current as the object to design the characteristic value representing the fault degree, and improves the extraction accuracy and real-time performance of the fault characteristic information;

[0056] 3. The fault characteristic parameters of the mathematical model of the inter-turn short circuit fault of the motor are enriched. The present invention establishes a mathematical model and an adjustable model under the condition of inter-turn short circuit fault of a dual three-phase motor, and deduces the fault model of the dual three-phase motor according to the space vector decoupling transformation of the multi-phase motor, enriching the fault characteristic parameters and improving the accuracy of fault diagnosis;

[0057] 4. The complexity of the fault tolerance algorithm is reduced. The present invention realizes the adaptive feedback adjustment of the parameter to be estimated based on the model reference adaptive law of the segmented proportional-integral (PI) regulator, without diagnosing the specific value of the fault parameter, reducing the complexity of the fault tolerance algorithm;

[0058] 5. The parameter design and stability analysis of the disturbance observer model are improved. The present invention establishes a model of inter-turn short circuit fault of a dual three-phase motor based on real motor data through a finite element model, providing a theoretical basis for the parameter design and stability analysis of the disturbance observer model.

[0059] Other advantages, objects, and features of the present invention will be set forth in part in the following description, and in part will be obvious to those skilled in the art upon examination of the following, or may be learned by practice of the present invention. The objects and other advantages of the present invention may be realized and obtained by the following description of the specification. Brief Description of the Drawings

[0060] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail with reference to the accompanying drawings, where:

[0061] Figure 1 Schematic diagram showing the variation of the fault characteristic value FI with the fault degree in a specific embodiment of the present invention;

[0062] Figure 2 Schematic diagram for fault degree diagnosis in a specific embodiment of the present invention;

[0063] Figure 3 Schematic diagram of the model structure based on a segmented PI regulator in a specific embodiment of the present invention;

[0064] Figure 4 Schematic diagram of the fault phase current waveform under single-phase short-circuit fault conditions in a specific embodiment of the present invention;

[0065] Figure 5 Schematic diagram of the short-circuit current waveform under single-phase short-circuit fault conditions in a specific embodiment of the present invention;

[0066] Figure 6 Schematic diagram of the fault harmonic plane current waveform under single-phase short-circuit fault conditions in a specific embodiment of the present invention;

[0067] Figure 7 Schematic diagram of the fault electromagnetic torque under single-phase short-circuit fault conditions in a specific embodiment of the present invention;

[0068] Figure 8 Schematic diagram of the diagnostic accuracy of the traditional diagnostic method with the change of the light fault condition of the motor;

[0069] Figure 9 Schematic diagram of the diagnostic accuracy of the traditional diagnostic method with the change of the heavy fault condition of the motor;

[0070] Figure 10 Schematic diagram of the diagnostic accuracy with the change of the light fault condition of the motor in a specific embodiment of the present invention;

[0071] Figure 11 Schematic diagram of the diagnostic accuracy with the change of the heavy fault condition of the motor in a specific embodiment of the present invention. Detailed Description of the Embodiment

[0072] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only schematically illustrate the basic concept of the present invention. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0073] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams rather than physical diagrams, and should not be construed as a limitation on the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0074] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation on the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0075] The present invention proposes an adaptive diagnosis method for the inter-turn short-circuit fault of a dual-three-phase permanent magnet synchronous motor. By establishing an adaptive observer for the short-circuit turn ratio of the motor, the fundamental wave characteristic parameters of the short-circuit current can be extracted online, and the closed-loop tracking estimation of the fault degree can be realized, thereby ensuring that the diagnostic accuracy is not affected by the change of the motor working conditions. This method mainly includes the following steps:

[0076] Step 1: To estimate the degree of the inter-turn short-circuit fault of the motor, first, a mathematical model and an adjustable model under the condition of the inter-turn short-circuit fault of the dual-three-phase motor need to be established. According to the space vector decoupling (Vector Space Decomposition, VSD) transformation of the multi-phase motor, the fault model of the dual-three-phase motor is deduced. The fault of phase A is expressed by the following formula:

[0077]

[0078] Among them, u d is the direct-axis voltage; u q is the quadrature-axis voltage; u x, u y is the harmonic voltage; R s is the stator resistance; i d is the direct-axis current; i q is the quadrature-axis current; i x , i y is the harmonic current; i F is the short-circuit current; θ is the synchronous electrical angle; ω is the synchronous angular velocity L d is the direct-axis inductance; L q is the quadrature-axis inductance; L z is the stator leakage inductance; ψ f is the permanent magnet flux linkage; σ is the short-circuit fault turn ratio.

[0079] Step 2: It can be obtained from formula (1) that the turn-to-turn short-circuit fault introduces short-circuit fault components in both the d-q and x-y harmonic sub-planes of the stator voltage equation. Therefore, by using the x-y current difference component between the real motor and the adjustable model, a characteristic value that can reflect the degree of turn short-circuit fault can be designed.

[0080] The above superscript symbol "" represents the motor parameters of the adjustable model, is the current estimated by the adjustable model; Rewrite the last two terms in the above formula (1) to obtain the following formula:

[0081]

[0082] Then the differential signal can be expressed as the following formula:

[0083]

[0084] where, Δi x is the x-axis current residual; Δi y is the y-axis current residual; d is the differential symbol;

[0085] Substitute formulas (2)-(3) into formula (1), and the mapping relationship between the differential signal and the short-circuit turn ratio σ can be obtained and expressed as the following formula:

[0086]

[0087] When the fault resistance remains unchanged, the effective value of the short-circuit current has a monotonically increasing property with the change of the fault turn ratio under any operating conditions of the motor. Therefore, the fault turn ratio of the adjustable model will remain synchronized with the short-circuit current convergence, that is: is the short-circuit turn ratio estimated by the motor adjustable model.

[0088] Step 3: By designing an appropriate feedback control law, an observer from the short-circuit current residual component to the fault turn ratio can be established, that is: when Δi x →0, Δi y →0,

[0089] Considering that the analytical formula of the short-circuit current is relatively complex, the characteristic extraction function of the fault current can actually be simplified to a certain extent. The short-circuit current mainly includes odd harmonic components such as the first, third, fifth, and seventh harmonics of the motor. Among them, the third harmonic component is mainly caused by the saturation factor of the stator core, and the fifth and seventh harmonic components are mainly affected by the non-linearity of the inverter. The fundamental component is the main component of the short-circuit current, and its change with the severity of the turn-to-turn short-circuit fault is also the most obvious. Therefore, the first component mainly included in the fault current can be selected as the object to design the characteristic value representing the fault degree.

[0090] According to the relevant conclusions of the orthogonal Fourier transform, the amplitude information of the fundamental component in the current residual can be extracted according to the following relationship: x The amplitude information of the fundamental component in the current residual:

[0091]

[0092] In the formula, A1 and A2 are the characteristic parameters of the orthogonal Fourier transform; FI is the fault characteristic value.

[0093] Among them,

[0094]

[0095] In the formula, x1 is the subscript of the fundamental component; k = 1, 2, 3, …

[0096] Taking FI as the fault characteristic value can reflect the input deviation of the fault harmonic current between the adjusted model and the real motor in the model reference adaptive system.

[0097] Please refer to Figure 1 for the schematic diagram of the change of the fault characteristic value FI with the fault degree in a specific embodiment of the present invention; Figure 1 shows the change of the fault characteristic value FI with the fault degree under different given short-circuit turn ratios. In this figure, a short-circuit fault with σ = 0.3 is introduced into the A-phase winding of the motor at t = 0.2 s, a short-circuit fault with σ = 0.5 is introduced at t = 0.4 s, and the fault is reset at t = 0.6 s. The results show that FI can reflect the current short-circuit turn ratio in proportion and has good followability for the change of the fault degree.

[0098] Please refer to Figure 2 for the schematic diagram of the fault degree diagnosis in a specific embodiment of the present invention; Figure 2 shows the control block diagram based on the model reference adaptive diagnosis method, and the current closed-loop control is used to control the pre-fault d-axis current and x-y axis current near the zero-value setting.

[0099] By applying a certain load torque \(T_L\) to the motor, after the motor runs to a stable speed, a short - circuit fault with a given turn ratio is introduced in phase A. Then, the fault feature value \(FI\) is generated by collecting the residual of the x - y axis current signals of the real motor and the x - y axis current signals of the adjustable model, and is used as the input of the adaptive law of the observer.

[0100] Step 4: To achieve the closed - loop tracking estimation of the short - circuit fault degree, based on the fault feature extraction, a model reference adaptive law based on a piece - wise PI regulator is designed to realize the adaptive feedback adjustment of the parameter to be estimated. Please refer to Figure 3 , which is the schematic diagram of the model structure based on the piece - wise PI regulator in a specific embodiment of the present invention; Figure 3 shows the regulator structure, which mainly consists of three parts. The input end is the current residual signal in the xy subspace between the adjustable model and the real motor, the output end is the estimated value of the short - circuit turn ratio, and the control law part is composed of a piece - wise PI regulator. During the adjustment process, the control law part collects the speed and load signals of the motor, and judges in real - time which piece - wise interval the current working condition is in, and selects the corresponding PI control parameters (\(K_{P_1}\), \(K_{I_1}\),...) to adjust the short - turn ratio estimation value. This regulator selects the boundary working points under the maximum working condition measurement range of the motor (rated working point: speed 1200 rpm, load torque 10 Nm, and the actual measurement range is defined by ±40% maximum deviation of speed and torque. The boundary working conditions correspond to four working points: p1: 800 rpm, 6 Nm / p2: 800 rpm, 14 Nm / p3: 1600 rpm, 6 Nm / p4: 1600 rpm, 14 Nm) as a reference, formulates the PI parameter values under the boundary working conditions with the standard of maintaining a specific tracking performance, and at the same time conducts a grid - like dissection of the working condition range within the boundary, and formulates the regulator parameters of the working points in other grids by the linear interpolation method to maintain the relative stability of the fault tracking effect under different working conditions.

[0101] The present invention establishes an inter - turn short - circuit fault model of a dual - three - phase motor based on real motor data through a finite - element model, and conducts fault simulations under single - phase short - circuit fault conditions. Please refer to Figure 4 , which is the schematic diagram of the fault - phase current waveform under single - phase short - circuit fault conditions in a specific embodiment of the present invention; Please refer to Figure 5 , which is the schematic diagram of the short - circuit current waveform under single - phase short - circuit fault conditions in a specific embodiment of the present invention; Please refer to Figure 6 , which is the schematic diagram of the fault harmonic - plane current waveform under single - phase short - circuit fault conditions in a specific embodiment of the present invention; Please refer to Figure 7 , which is the schematic diagram of the fault electromagnetic torque under single - phase short - circuit fault conditions in a specific embodiment of the present invention; Figures 4 to 7The presented simulation results show that when an inter-turn short circuit fault occurs in the a-phase winding, the corresponding phase current of this phase increases rapidly. Under the fault degree with a shorted turn ratio σ = 0.2, the peak current of the a-phase increases by approximately 22% compared to the normal operating state, which conforms to the variation law that the short-circuit current increases with the severity of the fault. At the same time, harmonic components are generated in the d-axis, q-axis, and x-axis currents after the a-phase fault occurs, which is consistent with the conclusion that the short-circuit current will introduce additional components in the dq and xy subspaces of the dual three-phase motor. The model adopted in the present invention can well reproduce the operating state of the motor under the inter-turn short circuit fault condition.

[0102] The adaptive diagnosis method for the inter-turn short circuit fault of the dual three-phase permanent magnet synchronous motor is compared with the traditional estimation method (that is, a method that does not use the feedback regulation of the control law part and only performs open-loop diagnostic estimation using the current residual signal between the healthy motor model and the real motor), and the variation of the diagnostic accuracy of the fault degree with the speed / load condition is obtained under two sets of conditions of light and heavy inter-turn short circuit faults of the motor. Please refer to Figure 8 for the schematic diagram of the diagnostic accuracy of the traditional diagnostic method with the change of the light fault condition of the motor; please refer to Figure 9 for the schematic diagram of the diagnostic accuracy of the traditional diagnostic method with the change of the heavy fault condition of the motor; please refer to Figure 10 for the schematic diagram of the diagnostic accuracy of a specific embodiment of the present invention with the change of the light fault condition of the motor; please refer to Figure 11 for the schematic diagram of the diagnostic accuracy of a specific embodiment of the present invention with the change of the heavy fault condition of the motor; Figures 8 to 11 From the presented comparison, the variation of the estimation accuracy of the two diagnostic methods with the working condition can be seen within the range of ±40% of the speed and load torque near the rated working condition of the motor. The results show that the traditional diagnostic method only has a high diagnostic accuracy near the rated working point of the motor, has accuracy distortion with the change of the motor speed under the light fault condition, and has accuracy distortion with the deviation of the motor speed and load from the rated working point under the heavy fault condition. For example, in Figure 8 , there is a distortion of 0.2 in the diagnostic accuracy of the traditional method under the positive offset of the maximum speed, Figure 9 , and the distortion of the traditional method reaches 0.36 under the positive offset of the maximum speed and torque. The diagnostic distortion of the closed-loop diagnostic system remains within the range of 0.1 with the offset of the working condition under both light and heavy fault conditions, has a steady-state tracking accuracy that does not change with the motor working condition, and reduces the diagnostic error by approximately 20% compared with the traditional diagnostic method.

[0103] The fault characteristics based on the x-y sub-plane current residual signal have good followability in reflecting the degree of inter-turn short circuit fault, and the adaptive feedback regulator can achieve accurate tracking of the degree of inter-turn short circuit fault. The experimental results show that within the working condition range of ±40% speed / load at the rated working point of the controlled object, compared with the traditional open-loop diagnosis method, the diagnostic error of the fault degree of the proposed diagnosis method is reduced by about 20 percentage points.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the 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 present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An adaptive diagnosis method for inter-turn short circuit faults of a dual-three-phase permanent magnet synchronous motor, characterized in that, The following steps are involved: Step 1: Establish a mathematical model and an adjustable model under the condition of a dual three-phase motor interturn short circuit fault, and establish a dual three-phase motor fault model according to the space vector decoupling transformation of the multi-phase motor; Step 2: Introduce short-circuit fault components in the dq and xy harmonic sub-planes of the stator voltage equation; use the xy current difference components between the real motor and the adjustable model to design a characteristic value reflecting the degree of the short-circuit fault; Step 3: Establish an observer from the short-circuit current residual component to the fault turns ratio to design the feedback control law; Step 4: Establish a model reference adaptive law based on a piecewise proportional-integral (PI) regulator to adjust the estimated parameters through adaptive feedback.

2. The method for adaptively diagnosing inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The A-phase fault of the dual three-phase motor fault model in step 1 is expressed as follows: where, u d is the direct-axis voltage; u q is the quadrature-axis voltage; u x , u y are the harmonic voltages; R s is the stator resistance; i d is the direct-axis current; i q is the quadrature-axis current; i x , i y are the harmonic currents; i F is the short-circuit current; θ is the synchronous electrical angle; ω is the synchronous angular velocity L d is the direct-axis inductance; L q is the quadrature-axis inductance; L z is the stator leakage inductance; ψ f is the permanent magnet flux linkage; σ is the short-circuit fault turn ratio.

3. The method for adaptively diagnosing inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that: The u in the A-phase fault of the dual-three-phase motor fault model x and u y The harmonic voltage is expressed by the following formula: Among them, the symbol "” represents the motor parameters of the adjustable model, is the current estimated for the adjustable model; The differential signal is expressed as follows: where, Δi x is the x-axis current residual; Δi y is the y-axis current residual; d is the differential symbol; The mapping relationship between the differential signal and the short-circuit turns ratio σ is obtained from formulas (1) to (3), which is expressed as follows:

4. The method for adaptively diagnosing inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The step 2 specifically includes: Calculate the xy current difference between the real motor and the adjustable model; Simplifying the characteristic extraction function of the fault current and utilizing the primary component of the fault current as an object to design the characteristic value of the fault degree; According to the relevant conclusions of orthogonal Fourier transform, the amplitude information of the fundamental component in the xy current difference component is extracted as the characteristic value to characterize the fault degree.

5. The method for adaptively diagnosing inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor according to claim 4, characterized in that: The step 2 further comprises: Extract i according to the following relationship x Amplitude information of the fundamental wave component in the current residual: Where A1 and A2 are characteristic parameters of orthogonal Fourier transform, and FI is the fault characteristic value; in, Where x1 is the subscript of the fundamental component, k = 1, 2, 3, ...; The FI reaction model refers to the input deviation of the fault harmonic current between the adaptive system adjustment model and the real motor.

6. The method for adaptively diagnosing inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The step 3 specifically includes: By applying a certain load torque TL to the traction motor, after the motor runs to a stable speed, a short circuit fault with a given turns ratio is introduced in phase A; The xy-axis current signal of the real motor and the residual of the xy-axis current signal of the adjustable model are collected to generate the fault characteristic value FI as the adaptive law input of the observer.

7. The method for adaptively diagnosing inter-turn short-circuit faults of a dual three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The step 4 specifically includes: Collect the motor's speed and load information to determine in real time which segment the current working condition is in; The corresponding PI control parameters are selected to adjust the short-circuit turns ratio estimation.

8. An adaptive diagnosis method for inter-turn short circuit fault of a dual-three-phase permanent magnet synchronous motor according to claim 7, characterized in that: The segmented PI regulator described in step 4 mainly includes: An input end, the current residual signal in the xy subspace between the adjustable model and the real motor; An output end, the estimated value of the shorted turn ratio; A control law part, which is composed of a segmented PI regulator; The control law part collects the speed and load signals of the motor, and judges the segmented interval where the current working condition is located in real time, and selects the corresponding PI control parameters to adjust the short turn ratio estimation value.

9. An adaptive diagnosis method for inter-turn short circuit fault of a dual-three-phase permanent magnet synchronous motor according to claim 8, characterized in that: The segmented PI regulator conducts grid division on the working condition range within the boundary, and formulates the regulator parameters of the working points in other grids by linear interpolation method to maintain fault tracking under different working conditions.

Images