A method and system for diagnosing eccentricity of a reluctance rotary transformer

Abstract

The present invention belongs to the technical field of rotary transformer fault diagnosis, and specifically relates to a method and system for diagnosing eccentricity of a reluctance rotary transformer, including obtaining the output voltage of a two-phase signal winding at a fixed speed of the rotary transformer to be tested, performing a Hilbert transform on the output voltage to obtain its envelope; performing a fast Fourier transform on the envelope of the output voltage to obtain the frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested; and judging whether the rotary transformer is eccentric and the type of eccentricity according to the frequency domain characteristics and the preset parameters of the rotary transformer. The diagnostic method and system provided in the present invention can diagnose all forms of eccentricity of the rotary transformer, such as static eccentricity, dynamic eccentricity and mixed eccentricity, through the output voltage of the rotary transformer, and the output voltage is easy to obtain, and no additional testing device is required.

Description

Technical Field

[0001] The invention belongs to the technical field of rotary transformer fault diagnosis, and in particular relates to a method and system for diagnosing eccentricity of a reluctance rotary transformer. Background Art

[0002] Permanent magnet synchronous motors have been widely used in various fields, especially in vehicles, due to their high efficiency, high power density and wide speed range. The vector control of permanent magnet synchronous motors requires high-precision and high-resolution rotor position signals. Sensors that can provide position signals include Hall sensors, encoders and resolvers. Among them, resolvers are more attractive in vehicle applications and have better reliability in harsh environments full of vibration, dust, oil and wide temperature changes.

[0003] Resolvers can generally be divided into two categories, wound rotor resolvers and variable reluctance resolvers. The excitation winding of a wound rotor resolver is located on the rotor and is powered by the excitation voltage, while the signal winding is located on the stator. Although a wound rotor resolver can ideally calculate the position more accurately, it is time-consuming and expensive to manufacture because windings are required on both the stator and the rotor. In contrast, a reluctance resolver moves the excitation winding from the rotor to the stator, reducing manufacturing costs. The rotor of a reluctance resolver consists only of stacked silicon steel sheets with a special rotor shape to ensure that the air gap can provide a sinusoidal component to the induced voltage. Therefore, the reluctance resolver is often seen as a perfect choice for its simple structure, low cost, and high reliability.

[0004] The accuracy of the resolver is very important for the field-oriented control of the motor. The position error of the resolver brings torque pulsation, vibration and noise to the motor. Although the reluctance resolver has better stability than other resolvers, the position error may be caused by faults. The most likely fault is eccentricity. In the case of eccentricity, the resolver provides incorrect position signals to the drive control system, reducing the stability of the control system, and ultimately affecting the normal operation of the motor, resulting in additional torque fluctuations and noise. Eccentricity can be divided into three categories: static eccentricity, dynamic eccentricity and mixed eccentricity. When static eccentricity occurs, the unbalanced magnetic pull will cause the occurrence of dynamic eccentricity, which will then develop into mixed eccentricity.

[0005] If the eccentricity fault of the rotating transformer can be diagnosed according to the fault characteristics in the early stage of the eccentricity fault of the rotating transformer, the preventive maintenance of the rotating transformer can be carried out in advance, avoiding the further development of the rotating transformer fault, thereby improving the performance of the rotating transformer and the motor and extending the service life.

[0006] The eccentricity diagnosis objects of existing literature and patents are mostly wound rotor rotary transformers. For example, the diagnostic method proposed in the existing literature "Static eccentricity fault diagnosis of wound rotor rotary transformer" uses the signal winding output voltage and adds a search coil to determine the eccentricity type and eccentricity position of the rotary transformer. However, due to the different structures of wound rotor rotary transformers and reluctance rotary transformers, the special shape of the rotor leads to the complexity of the air gap under eccentricity, so this method cannot be applied to reluctance rotary transformers. For example, the existing literature "Comprehensive analysis of health and failure of two types of reluctance transformers with eccentricity and inter-turn faults" proposes an analysis model established by the equivalent magnetic circuit method, but this method fails to summarize the general relationship between the output voltage additional frequency and the rotary transformer parameters, so it cannot be used as a basis for diagnosing the eccentricity of the reluctance rotary transformer. Therefore, it is very necessary to study a simple method to quickly diagnose the eccentricity form. Summary of the invention

[0007] The purpose of the present invention is to provide a method and system for diagnosing eccentricity of a reluctance rotary transformer to solve the problems raised in the background technology.

[0008] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0009] In a first aspect, the present invention provides a method for diagnosing eccentricity of a reluctance rotary transformer, the method comprising the following steps:

[0010] S1. Under a fixed rotation speed of the rotary transformer to be tested, the output voltage of the two-phase signal winding is obtained, and the output voltage is Hilbert transformed to obtain its envelope;

[0011] S2. Performing a fast Fourier transform on the envelope of the output voltage to obtain frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested;

[0012] S3. Determine whether the rotary transformer is eccentric and the type of eccentricity according to the frequency domain characteristics and preset parameters of the rotary transformer.

[0013] As a further optimization solution of the present invention, step S1 includes:

[0014] S1.1. Perform Hilbert transform on the output voltage to obtain the upper and lower envelopes V of the two phases of the rotary transformer to be tested. s-up , V s-low , V c-up , V c-low ;

[0015] S1.2. Calculate the period value T of the output voltage envelope based on the rotor speed n and the pole pair number P of the resolver:

[0016]

[0017] S1.3, according to half of the cycle value T / 2, switch the upper and lower envelopes at the set position to obtain the output voltage envelope E s , with V s The amplitude zero crossing point is used as the starting point:

[0018]

[0019] As a further optimization solution of the present invention, step S3 includes:

[0020] S3.1. If additional frequencies of the fundamental frequency plus or minus the conversion frequency appear on both sides of the fundamental frequency, it is determined that mixed eccentricity has occurred;

[0021] S3.2. If there is no additional frequency of the base frequency plus or minus the rotation frequency, determine whether there is an additional frequency of the rotary transformer rotation frequency slot multiple times the base frequency. If so, it is determined that dynamic eccentricity has occurred;

[0022] S3.3, if there is no additional frequency that is multiples of the base frequency of the frequency conversion slot, then determine whether there is an additional frequency that is an integer multiple of the base frequency other than the base frequency. If so, it is determined that static eccentricity has occurred;

[0023] S3.4: If S3.1-S3.3 are not satisfied, it is determined that no eccentricity occurs.

[0024] As a further optimization solution of the present invention, in step S3, the preset parameters include design parameters, operating parameters and known frequency domain characteristics of the rotary transformer under normal working conditions.

[0025] As a further optimization solution of the present invention, in step S3.1, the step of determining the mixed eccentricity includes:

[0026] The fundamental frequency of the induced voltage is calculated through the rotor speed and pole pair number in the preset parameters of the rotary transformer, and the mixed eccentricity diagnostic frequency that meets the mixed eccentricity diagnostic conditions is selected. If the diagnostic frequency is close to the fundamental frequency and is the minimum integer multiple of the fundamental frequency plus or minus the rotation frequency, it is judged as mixed eccentricity.

[0027] In a second aspect, the present invention proposes a reluctance rotary transformer eccentricity diagnosis system, which is used to perform the above eccentricity diagnosis method, and the system comprises:

[0028] A signal acquisition module is used to obtain the output voltage of the two-phase signal winding at a fixed speed of the rotary transformer to be tested, and to perform a Hilbert transform on the output voltage to obtain its envelope;

[0029] A signal processing module, used for performing a fast Fourier transform on the envelope of the output voltage to obtain frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested;

[0030] The analysis and judgment module judges whether the rotary transformer is eccentric and the type of eccentricity according to the frequency domain characteristics and preset parameters of the rotary transformer.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention can diagnose all eccentricity forms of the rotary transformer, such as static eccentricity, dynamic eccentricity and mixed eccentricity, through the output voltage of the rotary transformer. The output voltage is easy to obtain and does not require additional testing equipment.

[0033] 2. The diagnostic method of the present invention can distinguish three different types of eccentricity faults, namely mixed eccentricity, dynamic eccentricity and static eccentricity, through frequency domain analysis, thereby improving the accuracy and reliability of diagnosis; the use of Hilbert transform and fast Fourier transform can realize rapid processing and analysis of the output voltage envelope, thereby improving the detection speed and real-time performance.

[0034] 3. The present invention provides clear conditions for the diagnosis of mixed eccentricity by calculating the fundamental frequency and selecting a specific diagnostic frequency, thereby reducing the possibility of misdiagnosis.

[0035] 4. The diagnostic method of the present invention is applicable to different types of rotary transformers, and the diagnosis of eccentricity faults can be achieved by simply adjusting the parameters of the specific rotary transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of an implementation method for diagnosing eccentricity of a reluctance rotary transformer proposed in an embodiment of the present invention.

[0037] Figure 2 The figure is a flow chart of eccentricity diagnosis of a reluctance rotary transformer in an embodiment of the present invention.

[0038] Figure 3 The two-phase signal winding voltage of the static eccentric rotary transformer provided in the embodiment of the present invention.

[0039] Figure 4 The two-phase signal winding voltage and its envelope of the static eccentric rotary transformer provided in the embodiment of the present invention.

[0040] Figure 5 The embodiment of the present invention provides a two-phase signal winding voltage envelope of a static eccentric rotary transformer, and frequency domain characteristics of the two-phase envelope after fast Fourier transformation.

[0041] Figure 6 The embodiment of the present invention provides a two-phase signal winding voltage envelope of a hybrid eccentric rotary transformer, and frequency domain characteristics of the two-phase envelope after fast Fourier transformation.

[0042] Figure 7The embodiment of the present invention provides a two-phase signal winding voltage envelope of a dynamic eccentric rotary transformer, and frequency domain characteristics of the two-phase envelope after fast Fourier transformation.

[0043] Figure 8 It is a schematic diagram of the structure of an existing reluctance rotary transformer. DETAILED DESCRIPTION

[0044] The following description provides specific application scenarios and requirements of this specification, with the purpose of enabling those skilled in the art to make and use the contents of this specification. Various local modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but to the widest scope consistent with the claims.

[0045] The terms used herein are only used for the purpose of describing specific example embodiments and are not restrictive. For example, unless the context clearly indicates otherwise, as used herein, the singular forms "a", "an" and "the" may also include plural forms. When used in this specification, the terms "include", "comprise" and / or "contain" mean that the associated integers, steps, operations, elements and / or components exist, but do not exclude the existence of one or more other features, integers, steps, operations, elements, components and / or groups or that other features, integers, steps, operations, elements, components and / or groups may be added in the system / method.

[0046] In view of the following description, these and other features of the present specification, as well as the operation and function of the related elements of the structure, and the economy of the combination and manufacture of the parts can be significantly improved. Reference is made to the accompanying drawings, all of which form a part of this specification. However, it should be clearly understood that the drawings are for illustration and description purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0047] The flowcharts used in this specification illustrate the operations implemented by the system according to some embodiments in this specification. It should be clearly understood that the operations of the flowcharts may not be implemented in sequence. On the contrary, the operations may be implemented in reverse order or simultaneously. In addition, one or more other operations may be added to the flowchart. One or more operations may be removed from the flowchart.

[0048] Example 1

[0049] like Figure 1-2 As shown, this embodiment proposes a method for diagnosing eccentricity of a reluctance rotary transformer, and the method includes the following steps:

[0050] S1. Under a fixed speed of the rotary transformer to be tested, the output voltage of the two-phase signal winding is obtained, and the output voltage is Hilbert transformed to obtain its envelope;

[0051] S2. Performing a fast Fourier transform on the envelope of the output voltage to obtain the frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested;

[0052] S3. Determine whether the resolver is eccentric and the type of eccentricity based on the frequency domain characteristics and preset parameters of the resolver.

[0053] Preferably, the step S1 comprises:

[0054] S1.1. Perform Hilbert transform on the output voltage to obtain the upper and lower envelopes V of the two phases of the rotary transformer to be tested. s-up , V s-low , V c-up , V c-low ;

[0055] S1.2. Calculate the period value T of the output voltage envelope based on the rotor speed n and the pole pair number P of the resolver:

[0056]

[0057] S1.3, according to half of the cycle value T / 2, switch the upper and lower envelopes at the set position to obtain the output voltage envelope E s , with the envelope E of the sinusoidal signal winding s For example, take V s The amplitude zero crossing point is used as the starting point:

[0058]

[0059] Preferably, step S3 is specifically as follows:

[0060] S3.1. If additional frequencies of the fundamental frequency plus or minus the conversion frequency appear on both sides of the fundamental frequency, it is determined that mixed eccentricity has occurred;

[0061] S3.2. If there is no additional frequency of the base frequency plus or minus the rotation frequency, determine whether there is an additional frequency of the rotary transformer rotation frequency slot multiple times the base frequency. If so, it is determined that dynamic eccentricity has occurred;

[0062] S3.3, if there is no additional frequency that is multiples of the base frequency of the frequency conversion slot, then determine whether there is an additional frequency that is an integer multiple of the base frequency other than the base frequency. If so, it is determined that static eccentricity has occurred;

[0063] S3.4: If S3.1-S3.3 are not satisfied, it is determined that no eccentricity occurs.

[0064] Preferably, in step S3, the preset parameters include design parameters, operating parameters and known frequency domain characteristics of the rotary transformer under normal working conditions.

[0065] Preferably, in step S3.1, the step of determining the mixed eccentricity includes:

[0066] The fundamental frequency f of the induced voltage is calculated by using the rotor speed and pole pair number in the preset parameters of the rotary transformer. P :

[0067]

[0068] A mixed eccentricity diagnosis frequency that meets the mixed eccentricity diagnosis conditions is selected. If the diagnosis frequency is close to the base frequency and is the minimum integer multiple of the base frequency plus or minus the rotation frequency, it is judged as mixed eccentricity.

[0069] As an example, in the present invention, the frequency selection principle of eccentricity diagnosis is as follows:

[0070] Taking static eccentricity as an example, the air gap length at any angle under fault is:

[0071]

[0072] To facilitate frequency domain analysis, the reciprocal of the air gap length is written in series form:

[0073]

[0074] The winding of the resolver can also be expanded into a series form:

[0075]

[0076] Using the winding function method, the mutual inductance between the rotary transformer excitation winding and the cosine signal winding can be obtained:

[0077]

[0078] Substituting (5)(6) into (7), we can obtain:

[0079]

[0080] The signal winding voltage is obtained by (8):

[0081]

[0082] According to the above embodiment, when the rotary transformer has static eccentricity, the mutual inductance between the excitation winding and the signal winding will have integer multiple harmonics of the fundamental frequency, and there will also be a DC component. The step S1 of obtaining the induced voltage envelope is equivalent to demodulating the induced voltage and filtering out the high-frequency excitation component. Therefore, the frequency domain characteristics obtained by fast Fourier transforming the envelope are the same as the frequency domain characteristics of the mutual inductance. Therefore, the eccentricity diagnosis frequency in the case of static eccentricity selects an integer multiple of the fundamental frequency, and the above method is also applicable to deriving the frequency domain characteristics of the mutual inductance in the case of dynamic eccentricity and mixed eccentricity.

[0083] In order to more clearly describe the technical solution of the present invention, the content of the present invention is described in detail, and the specific operation steps are listed as follows:

[0084] Combination Figure 2-8 For a certain type of 8-pole 10-slot reluctance rotary transformer, its structure is as follows Figure 8 As shown, experiments were conducted to implement the present invention.

[0085] For resolvers with unknown eccentricity, follow the diagnostic flowchart, such as Figure 2 As shown. It includes the following steps:

[0086] Step 1): First, the rotor of the rotary transformer to be tested is dragged at a fixed speed of 1500 rpm to collect the two-phase signal winding voltage. The collected voltage V s With V e like Figure 3 shown.

[0087] Step 2): Perform Hilbert transform on the signal winding voltage to obtain the envelope of the two-phase signal winding.

[0088] 21) Perform Hilbert transform on the measured output voltage to obtain the upper and lower envelopes V of the two phases of the rotary transformer to be tested s-up , V s-low , V c-up , V c-low ;

[0089] 22) According to the rotor speed n and the pole pair number P of the resolver, calculate the period value T of the output voltage envelope:

[0090]

[0091] 23) According to half of the cycle value (5ms), switch the upper and lower envelopes at appropriate positions to obtain the output voltage envelope. s For example, a 40ms signal with a sampling resolution of V s The amplitude zero crossing point is used as the starting point:

[0092]

[0093] Switch the upper and lower envelopes at the correct position, and the final envelope is as follows Figure 4 As shown (the upper figure is the cosine winding signal voltage, and the lower figure is the sine winding signal voltage).

[0094] Step 3): Take any phase of the two-phase envelope, perform fast Fourier transform on it, and obtain the frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested, such as Figure 5 As shown;

[0095] Step 4) Based on the obtained frequency domain characteristics and the resolver parameters, determine whether the resolver is eccentric and the type of eccentricity. P represents the fundamental frequency, f r Indicates frequency conversion.

[0096]

[0097] The rotating transformer speed is 1500rpm, the frequency is f r The rotary transformer has 8 poles, 4 pairs of poles, and a base frequency of f r is 100Hz. Figure 5 There are no frequencies of adding or subtracting the base frequency on both sides of the mid-base frequency 100Hz, i.e., 75Hz and 125Hz. Go to step 5); an example that meets the mixed eccentricity condition is as follows Figure 6 , there are additional 75Hz and 125Hz frequency components on both sides of 100Hz, and the resolver has mixed eccentricity.

[0098] Step 5) Determine whether there is an additional frequency that is multiple times the base frequency of the rotary transformer frequency conversion slot. Figure 5 does not exist. Go to step 6); Examples of satisfying the dynamic eccentricity condition are as follows Figure 7 In addition to the base frequency of 100Hz, there are additional frequencies at 150Hz, 350Hz and 400Hz, which correspond to one times the slot number of rotation frequency minus the base frequency, one times the slot number of rotation frequency plus the base frequency and two times the slot number of rotation frequency minus the base frequency, respectively. The rotating transformer has dynamic eccentricity.

[0099] Step 6) Determine whether there are additional frequencies that are integer multiples of the base frequency other than the base frequency. Figure 5 In addition to the base frequency of 100Hz, there are additional frequencies of 200Hz, 300Hz and 400Hz, corresponding to double, triple and quadruple base frequencies. The resolver has static eccentricity.

[0100] Based on the same inventive concept, this embodiment proposes a reluctance rotary transformer eccentricity diagnosis system, which is used to perform the above eccentricity diagnosis method. The system includes:

[0101] The signal acquisition module is used to obtain the output voltage of the two-phase signal winding at a fixed speed of the rotary transformer to be tested, and to perform Hilbert transformation on the output voltage to obtain its envelope;

[0102] A signal processing module, used for performing a fast Fourier transform on the envelope of the output voltage to obtain the frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested;

[0103] The analysis and judgment module determines whether the rotary transformer is eccentric and the type of eccentricity based on the frequency domain characteristics and the preset parameters of the rotary transformer.

[0104] According to the above embodiment of the present invention, the above embodiment describes a method for detecting whether a rotary transformer is eccentric and the type of eccentricity, and a system for implementing the method. By using Hilbert transform and fast Fourier transform, the eccentricity of the rotary transformer can be effectively determined by analyzing the frequency domain characteristics, thereby improving the accuracy and efficiency of detection.

[0105] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present disclosure is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present disclosure (but not limited to) by each other to form a technical solution.

[0106] In addition, although each operation is described in a specific order, this should not be understood as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present disclosure. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.

[0107] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for diagnosing eccentricity of a reluctance rotary transformer, characterized in that: The method comprises the following steps: S1. Under a fixed rotation speed of the rotary transformer to be tested, the output voltage of the two-phase signal winding is obtained, and the output voltage is Hilbert transformed to obtain its envelope; S2. Performing a fast Fourier transform on the envelope of the output voltage to obtain frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested; S3. judging whether the rotary transformer is eccentric and the type of eccentricity according to the frequency domain characteristics and preset parameters of the rotary transformer; The step S3 comprises: S3.

1. If additional frequencies of the fundamental frequency plus or minus the conversion frequency appear on both sides of the fundamental frequency, it is determined that mixed eccentricity has occurred; S3.

2. If there is no additional frequency of the base frequency plus or minus the rotation frequency, determine whether there is an additional frequency of the rotary transformer rotation frequency slot multiple times the base frequency. If so, it is determined that dynamic eccentricity has occurred; S3.3, if there is no additional frequency that is multiples of the base frequency of the frequency conversion slot, then determine whether there is an additional frequency that is an integer multiple of the base frequency other than the base frequency. If so, it is determined that static eccentricity has occurred; S3.4, if S3.1-S3.3 are not satisfied, it is determined that no eccentricity occurs; In step S3, the preset parameters include design parameters, operating parameters and known frequency domain characteristics of the rotary transformer under normal working conditions; In step S3.1, the step of determining the mixed eccentricity includes: The fundamental frequency of the induced voltage is calculated through the rotor speed and pole pair number in the preset parameters of the rotary transformer, and the mixed eccentricity diagnostic frequency that meets the mixed eccentricity diagnostic conditions is selected. If the diagnostic frequency is close to the fundamental frequency and is the minimum integer multiple of the fundamental frequency plus or minus the rotation frequency, it is judged as mixed eccentricity.

2. The method for diagnosing eccentricity of a reluctance rotary transformer according to claim 1, characterized in that: The step S1 comprises: S1.

1. Perform Hilbert transform on the output voltage to obtain the upper and lower envelopes V of the two phases of the rotary transformer to be tested. s-up ,V s-low ,V c-up ,V c-low ; S1.

2. Calculate the period value T of the output voltage envelope based on the rotor speed n and the pole pair number P of the resolver: S1.3, according to half of the cycle value T / 2, switch the upper and lower envelopes at the set position to obtain the output voltage envelope E s , with V s The amplitude zero crossing point is used as the starting point:

3. A reluctance rotary transformer eccentricity diagnosis system, characterized in that: Applied to executing the eccentricity diagnosis method according to any one of claims 1-2, the system comprises: A signal acquisition module is used to obtain the output voltage of the two-phase signal winding at a fixed speed of the rotary transformer to be tested, and to perform a Hilbert transform on the output voltage to obtain its envelope; A signal processing module, used for performing a fast Fourier transform on the envelope of the output voltage to obtain frequency domain characteristics of the output voltage envelope of the rotary transformer to be tested; The analysis and judgment module judges whether the rotary transformer is eccentric and the type of eccentricity according to the frequency domain characteristics and preset parameters of the rotary transformer.

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