A real-time monitoring method and system for operating state of a DC motor with speed feedback

Abstract

This invention belongs to the field of motor monitoring technology, specifically relating to a method and system for real-time monitoring of the operating status of a DC motor with speed feedback. The method includes: synchronously acquiring the armature current of the DC motor and the speed feedback voltage characterizing its rotational speed; performing multi-frequency band decomposition on the feedback voltage; extracting the proportion of high-frequency noise energy and introducing a voltage RMS compensation factor; determining contact degradation indicators; extracting the current commutation ripple frequency; calculating the deviation between its actual value and the theoretical voltage mapping value; combining load current correction; determining a consistency deviation index; and finally, obtaining a health score for the DC motor through a nonlinear attenuation model. This invention achieves a fundamental distinction between speed fluctuations and tachogenerator aging, effectively avoiding control misjudgments caused by tachogenerator aging.

Description

Technical Field

[0001] This invention relates to the field of motor monitoring technology. More specifically, this invention relates to a method and system for real-time monitoring of the operating status of a DC motor with speed feedback. Background Technology

[0002] DC motors are widely used in industrial automated production lines, precision machine tool feed drives, and rail transit gantry crane units due to their excellent speed regulation performance. Systems used to control the speed of DC motors are typically equipped with a tachogenerator as a speed feedback element. The tachogenerator provides a feedback signal based on the ratio between its output voltage and speed, achieving closed-loop control of the DC motor speed. Furthermore, because tachogenerators are simple in structure, resistant to high temperatures, and have a certain degree of resistance to electromagnetic interference, they remain the mainstream choice in many high-reliability applications.

[0003] Currently, during long-term continuous operation, tachogenerators experience mechanical wear, reduced spring pressure, or surface oxidation of their internal carbon brushes and commutators. This can lead to poor contact between the carbon brushes and commutator, generating momentary, weak electric arcs—high-frequency noise. Simultaneously, this physical aging can cause abnormal feedback signals, primarily manifested as superimposed high-frequency arc noise and a false attenuation of the output voltage amplitude. When the tachogenerator's feedback voltage decreases due to poor contact, the control system may mistakenly interpret this as a decrease in the actual DC motor speed, incorrectly increasing the drive current. This misjudgment caused by the aging of the tachogenerator itself can easily trigger a motor runaway accident, damaging mechanical equipment and potentially endangering the safety of personnel on site.

[0004] However, most existing monitoring schemes rely on simple threshold judgments or open circuit detection, making it difficult to effectively distinguish whether a drop in the tachometer feedback voltage during DC motor operation is caused by changes in the actual load of the DC motor or by contact degradation of the tachometer generator itself. Furthermore, existing algorithms often suffer from large time delays and low sensitivity when dealing with high-frequency contact noise, failing to provide effective early warning information in the early stages of a fault. Therefore, how to achieve deep decoupling and accurate assessment of the health status of the tachometer generator using only existing electrical signals has become a key technical challenge for ensuring the safe and stable operation of DC motor systems. Summary of the Invention

[0005] To address the technical problems of existing solutions, such as difficulty in distinguishing whether a drop in feedback voltage is caused by load changes or tachogenerator degradation, and low early warning sensitivity, this invention proposes a real-time monitoring method and system for the operating status of a DC motor with speed feedback. This method can fundamentally distinguish between speed fluctuations and tachogenerator aging, enabling refined assessment of contact status and effective identification of false voltage attenuation, preventing DC motor runaway accidents, and ensuring the safe operation of the system.

[0006] In a first aspect, the present invention provides a method for real-time monitoring of the operating status of a DC motor with speed feedback, comprising: synchronously acquiring the armature current of the DC motor and a speed feedback voltage characterizing its rotational speed, and processing the speed feedback voltage to obtain an AC ripple signal; performing multi-band decomposition on the AC ripple signal, determining a contact degradation index based on the ratio of high-frequency noise band energy to total energy, and introducing the effective value of the speed feedback voltage as a compensation factor; extracting the current commutation ripple frequency in the armature current spectrum, constructing a theoretical correspondence between the current commutation ripple frequency and the speed feedback voltage based on the structural parameters of the DC motor, calculating the deviation of the actual measured value from the theoretical correspondence, and correcting the deviation in conjunction with the load current to determine a consistency deviation index; and obtaining an operating health score of the DC motor by evaluating it through a nonlinear attenuation model based on the contact degradation index and the consistency deviation index, thereby realizing real-time monitoring of the operating status of the DC motor.

[0007] This invention achieves dual verification of the contact status and signal consistency of the tachogenerator by synchronously monitoring the armature current and the speed feedback voltage. This method can fundamentally distinguish between speed fluctuations caused by load changes and false voltage attenuation caused by aging of the tachogenerator, thereby effectively preventing DC motor runaway accidents and significantly improving the system's safe operation assurance capability.

[0008] Preferably, the contact degradation index satisfies the following relationship:

[0009]

[0010] in, For contact degradation indicators; This is a set of nodes in a predefined high-frequency noise band. It is the set of all frequency band nodes; For the first The first frequency band node Each decomposition coefficient, the sum of its squares, represents the energy of that frequency band; It is a non-zero minimum constant; This is the effective value of the speed measurement feedback voltage; These are the preset weighting coefficients.

[0011] This invention establishes a dynamic judgment mechanism by introducing the effective value of the speed feedback voltage as a compensation factor. When the DC motor is running at high speed, this indicator can automatically correct the weak interference signal generated by normal high-speed mechanical friction, which is not a fault interference. This avoids misjudgment of the system under high-speed conditions and ensures the sensitivity and accuracy of capturing the weak arc characteristics in the early stage of carbon brush wear.

[0012] Preferably, the consistency deviation index is calculated as follows:

[0013]

[0014] in, This is a consistency deviation indicator; The commutation ripple frequency is extracted from the armature current spectrum. This represents the average value of the speed measurement feedback voltage; This is the theoretical conversion constant; It is a non-zero reference constant; This represents the magnitude of the load current. This is the load sensitivity suppression coefficient.

[0015] This invention utilizes the current commutation ripple frequency, which is unaffected by contact resistance, as the actual speed reference and introduces a load correction term. This not only accurately identifies false attenuation of the speed measurement feedback voltage, but also appropriately relaxes the judgment criteria under conditions of high current load on DC motors and armature reaction interference magnetic field, thereby effectively reducing the false alarm rate of the system.

[0016] Preferably, the health score satisfies the following relationship:

[0017]

[0018] in, Rate your health; The weighting coefficients for the contact degradation index, The weighting coefficient for the consistency deviation index; For contact degradation indicators; This is a consistency deviation indicator.

[0019] This invention transforms complex microscopic electrical signal characteristics into an intuitive percentage-based health score through a nonlinear attenuation model. Furthermore, by allocating weights, this model enhances the system's awareness of voltage distortion faults that could lead to serious consequences. It supports graded control measures that automatically trigger healthy operation, wear warnings, and fault shutdowns, thereby achieving refined and intelligent monitoring of the DC motor's operating status.

[0020] Preferably, the process of acquiring the AC ripple signal includes: acquiring the speed feedback voltage of the tachogenerator through a high-precision industrial acquisition device; calculating the sliding average value of the speed feedback voltage within a preset time window; and subtracting the corresponding sliding average value from the speed feedback voltage to obtain the AC ripple signal after filtering out the DC fundamental wave.

[0021] Preferably, when performing multi-band decomposition on the AC ripple signal, the AC ripple signal is divided into multiple independent frequency bands by wavelet packet decomposition technology, and the high-frequency noise frequency band range belonging to the contact between the carbon brush and the commutator of the tachogenerator is determined according to the rated speed of the tachogenerator and the number of commutator segments.

[0022] This invention utilizes wavelet packet decomposition technology to divide AC ripple signals into multiple independent frequency bands, enabling multi-scale refined analysis. By combining the rated speed of the tachogenerator with the number of commutator segments, the high-frequency noise band range of the carbon brush-commutator contact is targeted and determined. This ensures accurate identification of the weak arc frequency band caused by carbon brush wear or surface oxidation, effectively eliminating low-frequency fundamental waves and environmental interference. This improves the system's sensitivity and accuracy in capturing subtle anomalies in their early stages, providing reliable data support for calculating contact degradation indices.

[0023] Preferably, the extraction process of the current commutation ripple frequency includes: performing power spectral density analysis on the armature current, identifying the main peak frequency with the largest energy amplitude in the spectrum, performing logical verification on the main peak frequency according to the pole pair number and slot number parameters of the DC motor to eliminate interference frequencies, and locking the current commutation ripple frequency that characterizes the actual speed of the DC motor.

[0024] Preferably, the health score is divided into a healthy operation zone, a wear warning zone, and a fault shutdown zone.

[0025] Preferably, the speed feedback voltage is derived from a tachogenerator coaxially connected to the DC motor, and the armature current is obtained through a shunt or Hall sensor connected in series with the DC motor bus.

[0026] Secondly, the present invention provides a real-time monitoring system for the operating status of a DC motor with speed feedback, comprising a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the aforementioned method for real-time monitoring of the operating status of a DC motor with speed feedback is implemented.

[0027] By adopting the above technical solution, a computer program is generated from the above-mentioned method for real-time monitoring of the operating status of a DC motor with speed feedback, and stored in a memory so that it can be loaded and executed by a processor. A terminal device can then be made based on the memory and the processor for convenient use.

[0028] The beneficial effects of this invention are as follows:

[0029] This invention achieves dual dynamic verification of the contact state and signal consistency of a tachogenerator by synchronously acquiring the armature current of a DC motor and the speed feedback voltage characterizing its rotational speed. The method extracts the AC ripple from the speed feedback voltage and performs multi-band decomposition, combining it with a voltage RMS compensation factor to determine contact degradation indicators. Simultaneously, it uses the current commutation ripple frequency as a speed reference, combining it with a load correction term to determine consistency deviation indicators. Finally, a nonlinear attenuation model is used to fuse the two indicators into a percentage-based health score, fundamentally distinguishing between load fluctuations and tachogenerator aging, effectively preventing DC motor runaway accidents, and ensuring the safe and stable operation of industrial production.

[0030] Furthermore, this invention introduces a dynamic correction mechanism in the index construction, automatically correcting mechanical interference under high speed using the effective voltage value, and introducing a load sensitivity suppression coefficient to reduce the false alarm rate under high current conditions. The system also uses wavelet packet decomposition to capture the weak arc characteristics in the early stage of carbon brush wear, and combines the DC motor structural parameters to perform logical verification of the current frequency to ensure the sensitivity and accuracy of monitoring. At the same time, this scheme divides the health score into three intervals: healthy operation, wear warning, and fault shutdown, realizing refined and intelligent hierarchical control of the DC motor operating status. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating a method for real-time monitoring of the operating status of a DC motor with speed feedback according to the present invention.

[0032] Figure 2 This is a schematic diagram showing the comparison of wavelet packet energy spectrum feature distributions;

[0033] Figure 3 This is a schematic diagram showing the results of the dynamic consistency verification between the current commutation ripple frequency and the speed measurement feedback voltage.

[0034] Figure 4 This is a schematic diagram illustrating how health scores change over time. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0036] This invention discloses a method for real-time monitoring of the operating status of a DC motor with speed feedback, referring to... Figure 1 This includes steps S1-S4:

[0037] S1. Synchronously acquire the armature current of the DC motor and the speed feedback voltage that characterizes its speed, and process the speed feedback voltage to obtain the AC ripple signal.

[0038] In an optional embodiment, during DC motor operation, to ensure the capture of sufficiently subtle signal characteristics, a high-precision industrial data acquisition device with a frequency set at least 20 times the rated commutation frequency of the DC motor is used to acquire two key electrical signals characterizing the DC motor's operating status in real time: armature current and speed feedback voltage. The armature current is acquired by a shunt or Hall sensor connected in series with the DC motor bus. The waveform of this armature current includes periodic ripples generated by the commutation of the DC motor rotor; the frequency of these ripples directly reflects the actual speed of the DC motor. The speed feedback voltage is acquired from a tachogenerator coaxially connected to the DC motor and reflects the measured speed of the DC motor. The acquired speed feedback voltage is then de-DC processed to extract the pure AC component.

[0039] Specifically, when performing DC-to-DC processing on the speed feedback voltage, the sliding average value of the speed feedback voltage within a preset time window is first calculated, and this average value is used as the steady-state reference for the current DC motor speed. Then, subtracting this sliding average value from the speed feedback voltage filters out the DC fundamental wave, thus obtaining an AC ripple signal containing only fluctuation characteristics. For example, if the current output voltage reference of the tachogenerator is approximately 12V, the above sliding average processing can extract AC components with amplitudes in the millivolt range. These AC components contain the high-frequency arc noise characteristics of the AC ripple in the speed feedback voltage, and these characteristics are the core basis for judging whether the carbon brush contact condition is good.

[0040] Thus, by synchronously acquiring and preprocessing multi-source signals, the system can ensure that it provides an accurate data foundation for subsequent noise analysis and frequency extraction.

[0041] S2. Perform multi-band decomposition on the AC ripple signal, and determine the contact degradation index based on the ratio of high-frequency noise band energy to total energy and by introducing the effective value of the speed measurement feedback voltage as a compensation factor.

[0042] In an optional embodiment, the contact degradation index is used to reflect the quality of contact between the carbon brushes and commutator of the tachogenerator. Under ideal operating conditions with good contact between the carbon brushes and commutator, the AC ripple signal mainly consists of low-frequency rotational cycles. However, once mechanical wear or surface oxidation occurs between the carbon brushes and commutator, the contact gaps between them will generate a momentary weak electric arc, which manifests as broadband high-frequency noise in the frequency spectrum. To achieve a quantitative assessment of the high-frequency noise intensity, wavelet packet decomposition technology is used to finely divide the AC ripple signal into multiple independent frequency bands. Based on the rated speed of the tachogenerator and the number of commutator segments, the high-frequency noise frequency band belonging to the contact between the carbon brushes and commutator of the tachogenerator is determined, thereby constructing the contact degradation index, which satisfies the following relationship:

[0043]

[0044] in, For contact degradation indicators; This is a set of preset high-frequency noise frequency band nodes. For example, the total number of nodes in wavelet packet decomposition is set to 16 based on the high-frequency noise characteristics of the tachogenerator. The frequency band nodes are numbered sequentially from low to high signal frequency as 1 to 16. Nodes 8 to 15 correspond to the frequency bands where weak electric arcs are concentrated. It is the set of all frequency band nodes; For the first The first frequency band node In wavelet packet decomposition, the original signal is decomposed into a series of discrete coefficient sequences at each frequency band node. The decomposition coefficient is the first in the sequence of node coefficients. Each discrete sampled data value, the sum of its squares represents the energy of that frequency band; It is a non-zero minimum constant; This is the effective value of the speed measurement feedback voltage; These are preset weighting coefficients, which have the dimensions of offset voltage.

[0045] It should be noted that the contact degradation index The construction of this equation lies in coupling the signal feature extraction principle with the motor operation law. The first part of the equation characterizes the intensity of the arc burst by the ratio of the high-frequency noise band energy to the total energy of the AC ripple signal; the second part maps the physical fact that normal mechanical friction at high speeds in mechanical dynamics increases background noise, by introducing a quantity with the dimension of canceling voltage, i.e. Weighting coefficients This eliminates the effective value of the speed measurement feedback voltage. The dimensions of the measurement were used to construct a background noise subtraction barrier, which reduced feature misjudgment at high speeds.

[0046] In the above formula, the first term is the ratio of high-frequency noise energy to the total AC ripple signal energy. The higher this ratio, the worse the contact condition between the carbon brush and the commutator. The second term is the speed compensation term; the higher the DC motor speed, the better the contact condition between the carbon brush and the commutator. The larger the value, the higher the mechanical friction between the carbon brush and the commutator, which causes normal minor vibrations or electromagnetic fluctuations. These vibrations are then converted into weak interference signals superimposed on the speed feedback voltage signal, i.e., non-fault interference. Therefore, by subtracting the speed compensation term as background noise, the system automatically filters out the interference energy caused by normal mechanical friction under high-speed conditions when the DC motor is running at high speed. This avoids artificially inflated contact degradation indicators, thus ensuring the sensitivity and accuracy of capturing the weak arc characteristics in the early stages of carbon brush wear. It should be noted that when the motor is healthy and under high speed or heavy load conditions, the correction term may be greater than the previous term, resulting in a negative value for the calculated contact degradation indicator. Therefore, when the calculated contact degradation indicator is negative, the system automatically corrects the contact degradation indicator value to 0.

[0047] For example, assuming good contact between the carbon brush and the commutator, and assuming wavelet packet decomposition of the AC ripple signal, the total energy of all frequency band nodes is 2000, of which 400 belongs to the high-frequency noise band. Let's set... If the effective value of the current speed measurement feedback voltage V, weighting coefficient ,but If the carbon brush is severely worn, assuming the energy in the high-frequency noise band is 1600, the index will change to... Even after removing background noise, the contact degradation index still clearly reflects the severe and weak arcing phenomenon caused by carbon brush wear.

[0048] In this way, by combining the proportion of high-frequency noise energy with real-time speed information, the system can sensitively capture the weak arc characteristics generated in the early stage of carbon brush wear, thereby achieving accurate assessment of the contact state between the carbon brush and commutator of the tachogenerator.

[0049] S3. Extract the current commutation ripple frequency from the armature current spectrum, construct the theoretical correspondence between the current commutation ripple frequency and the speed feedback voltage based on the structural parameters of the DC motor, calculate the deviation of the actual measured value from the theoretical correspondence, and correct the deviation in combination with the load current to determine the consistency deviation index.

[0050] In an optional embodiment, power spectral density analysis is performed on the armature current to identify the main peak frequency with the largest energy amplitude in the spectrum. Logical verification is then performed on the main peak frequency based on the pole pair and slot number parameters of the DC motor to eliminate interfering frequencies and lock in the current commutation ripple frequency characterizing the actual speed of the DC motor. This frequency is proportional to the speed of the tachogenerator and is not affected by changes in the contact resistance at the interface between the tachogenerator carbon brushes and the commutator. Therefore, the accuracy and reliability of the tachogenerator can be determined by comparing the speed calculated from the current commutation ripple frequency with the measured speed characterized by the speed feedback voltage. Based on this, a consistency deviation index is constructed, and its calculation method is as follows:

[0051]

[0052] in, This is a consistency deviation indicator; The commutation ripple frequency is extracted from the armature current spectrum. The average value of the speed feedback voltage is the sliding average value of the speed feedback voltage calculated within a preset time window, which is used as a steady-state reference to characterize the current DC motor speed. This is the theoretical conversion constant, with units of Hz / V; This is a non-zero reference constant, with units of Hertz (Hz). This represents the magnitude of the load current. This is the load sensitivity suppression coefficient, measured in amperes. .

[0053] It should be noted that the consistency deviation indicator The construction of this equation is based on the combination of electromagnetic laws of motors and residual verification mechanisms. The first term of the absolute value in the equation reflects the degree of distortion deviation between the actual rotational speed and frequency and the theoretical mapped frequency; while the introduction of the second term conforms to the objective law in motors that armature reaction interference with the main magnetic field under high current conditions leads to ripple waveform distortion. This term is expressed in units of per ampere. Load sensitivity suppression coefficient It offset the magnitude of the load current. The dimensions of the measurement realize the adaptive relaxation of soft constraints on the judgment criteria under heavy load conditions.

[0054] Furthermore, the current commutation ripple frequency extracted from the armature current reflects the actual frequency of the DC motor's rotational speed. Using a preset theoretical conversion constant, the average value of the tachogenerator's speed feedback voltage is mapped to obtain the theoretical frequency. In the formula, the first term calculates the normalized absolute deviation between the actual and theoretical frequencies. If the tachogenerator is functioning normally, the actual and theoretical frequencies are highly consistent, and the ratio of the first term approaches 0. If the tachogenerator's contact degradation leads to a decrease in the speed feedback voltage (i.e., a decrease in the average speed feedback voltage), the ratio of the first term will significantly deviate from 0. The second term is the load correction term. Under high-current loads on the DC motor, the armature reaction interferes with the magnetic field, causing distortion in the originally regular current commutation ripple waveform and resulting in a normal deviation. Therefore, by deducting this normal deviation as an interference term and appropriately relaxing the judgment criteria under high loads, the false alarm rate of the system is effectively reduced. It should be noted that when the motor is healthy and operating at high speed or heavy load, the correction term may be greater than the previous term, resulting in a negative result for the consistency deviation index. Therefore, when the consistency deviation index is calculated as negative, the system automatically corrects the consistency deviation index value to 0.

[0055] For example, the current commutation ripple frequency extracted from the armature current spectrum. Hz; theoretical conversion constant Hz / V; non-zero reference constant Load sensitivity suppression coefficient When the tachogenerator malfunctions, the speed feedback voltage output by the tachogenerator experiences a false attenuation due to poor contact. V, its normal value should be 25V, load current A, then the consistency deviation index Therefore, even after deducting the normal waveform distortion caused by the large load, the result still deviates significantly from zero. Based on this, the system can determine that the speed feedback voltage output by the tachometer generator is distorted, posing a serious risk of failure.

[0056] In this way, by using the current commutation ripple frequency in the armature current spectrum as the actual frequency reference reflecting the DC motor speed, the distortion of the speed measurement feedback voltage caused by contact degradation of the tachogenerator can be effectively identified, thus providing a reliable self-diagnostic basis for the system.

[0057] S4. Based on the contact degradation index and the consistency deviation index, the operating health score of the DC motor is obtained through nonlinear attenuation model evaluation, thereby realizing real-time monitoring of the operating status of the DC motor.

[0058] In an optional embodiment, the contact degradation index and the consistency deviation index are integrated into a percentage-based health score. This score employs a function model with non-linear decay characteristics, and its sensitivity can be dynamically adjusted according to the fault type and severity. In particular, higher weight is given to speed measurement feedback voltage distortion faults that may lead to serious consequences. The health score then satisfies the following relationship:

[0059]

[0060] in, Rate your health; The weighting coefficients for the contact degradation index, The weighting coefficient for the consistency deviation index; For contact degradation indicators; This is a consistency deviation indicator.

[0061] It should be noted that the health score The construction of this model relies on the use of an inverse proportional nonlinear decay model. This model... and The two dimensionless features are weighted and fused, utilizing the graded configuration of the weight parameters, such as... A more significant negative penalty is applied to voltage distortion phenomena that can easily lead to runaway accidents. This formula smoothly maps complex physical and electromagnetic variables to a health tolerance surface based on a percentage, thereby compensating for the shortcomings of traditional static monitoring methods with fixed thresholds.

[0062] Furthermore, this model is essentially an inverse proportional nonlinear decay function, which, in practical applications, For example, such as , This weighting setting means that the negative impact of speed measurement feedback voltage signal distortion on the health score is far greater than the minor carbon brush wear caused by contact degradation; assuming the current , Then the health score The score is far below the safety threshold. This safety threshold, along with the boundary values ​​of the relevant range, are preset values ​​based on the actual operating conditions of the DC motor and historical maintenance data. For example, the preset safety threshold here is 50 points. Based on this, the system determines that the DC motor is in a fault shutdown state and immediately performs protective operations such as cutting off the power supply, thereby effectively preventing accidents from occurring.

[0063] Furthermore, this invention employs a percentage-based scoring mechanism and presets health score thresholds for three status intervals based on actual usage conditions. For example, when the preset thresholds are 80 and 50 points, if... If it is determined to be a healthy operating zone; This is identified as a wear warning zone; if It was determined to be a fault shutdown area.

[0064] In this way, through the fusion evaluation of multi-dimensional indicators, micro-noise and macro-deviation are transformed into an intuitive percentage-based health score. The system can automatically trigger graded control measures such as healthy operation, wear warning, and fault shutdown based on the different preset intervals in which the score is located, namely the healthy operation zone, wear warning zone, and fault shutdown zone, so as to realize the refined and intelligent monitoring and maintenance of the DC motor's operating status.

[0065] Reference Figure 2 This is a comparison diagram of the wavelet packet energy spectrum feature distribution in the embodiments of the present invention. By comparing and showing the process of the energy center shifting from the low-frequency region representing the good contact condition of the tachogenerator to the high-frequency noise region representing the carbon brush wear condition, the physical essence of the contact degradation index is revealed intuitively.

[0066] Reference Figure 3 This is a graph showing the dynamic consistency verification results of the current commutation ripple frequency and the speed measurement feedback voltage in an embodiment of the present invention. The theoretical baseline in the graph corresponds to the theoretical frequency mapping term, i.e., the denominator, in the consistency deviation index formula. This represents the highly consistent mapping relationship between the average speed feedback voltage and the theoretical frequency under normal tachogenerator conditions. It can be seen that normal data points closely surround the theoretical baseline, while abnormal data points deviate to the left of the theoretical baseline. This deviation reveals spurious attenuation of the speed feedback voltage, thus directly verifying the effectiveness of the consistency deviation index in addressing tachogenerator distortion.

[0067] Reference Figure 4 This is a schematic diagram of the change of the health score of the DC motor over time in an embodiment of the present invention. As can be seen, as the DC motor runs for a long time, its health score starts from the healthy operation zone, passes through the wear warning zone over time, and finally falls into the fault shutdown zone, completely recording the entire process of the tachogenerator from early wear to functional failure.

[0068] This invention also discloses a real-time monitoring system for the operating status of a DC motor with speed feedback, comprising a processor and a memory. The memory stores computer program instructions, which, when executed by the processor, implement a real-time monitoring method for the operating status of a DC motor with speed feedback according to the present invention.

[0069] The system also includes other components well known to those skilled in the art, such as communication buses and communication interfaces, the settings and functions of which are known in the art and will not be described in detail here.

[0070] In the description of this specification, "multiple" or "several" means at least two, such as two, three or more, unless otherwise expressly and specifically defined.

Claims

1. A method for real-time monitoring of the operating status of a DC motor with speed feedback, characterized in that, include: The armature current of the DC motor and the speed feedback voltage characterizing its rotational speed are acquired synchronously, and the speed feedback voltage is processed to obtain an AC ripple signal. The AC ripple signal is decomposed into multiple frequency bands. Based on the ratio of high-frequency noise band energy to total energy, and with the effective value of the speed measurement feedback voltage introduced as a compensation factor, the contact degradation index is determined. Extract the current commutation ripple frequency from the armature current spectrum, construct the theoretical correspondence between the current commutation ripple frequency and the speed feedback voltage based on the structural parameters of the DC motor, calculate the deviation of the actual measured value from the theoretical correspondence, and correct the deviation in combination with the load current to determine the consistency deviation index. Based on the contact degradation index and the consistency deviation index, the operating health score of the DC motor is obtained through evaluation using a nonlinear decay model, thereby realizing real-time monitoring of the operating status of the DC motor.

2. The real-time monitoring method for the operating state of a DC motor with speed feedback according to claim 1, characterized in that, The contact degradation index satisfies the following relationship: in, For contact degradation indicators; This is a set of nodes in a predefined high-frequency noise band. It is the set of all frequency band nodes; For the first The first frequency band node Each decomposition coefficient, the sum of its squares, represents the energy of that frequency band; It is a non-zero minimum constant; This is the effective value of the speed measurement feedback voltage; The weighting coefficients are preset; when the degradation index is exposed... When the calculated value is negative, the system automatically corrects the contact degradation index value to 0.

3. The real-time monitoring method for operating state of a DC motor with speed feedback according to claim 1, characterized in that, The consistency deviation index is calculated as follows: in, This is a consistency deviation indicator; The commutation ripple frequency is extracted from the armature current spectrum. This represents the average value of the speed measurement feedback voltage; This is the theoretical conversion constant; It is a non-zero reference constant; The magnitude of the load current; This is the load sensitivity suppression coefficient; when consistency deviates from the index... When the calculation is negative, the system automatically corrects the consistency deviation index value to 0.

4. The real-time monitoring method for operating state of a DC motor with speed feedback according to claim 1, characterized in that, The health score satisfies the following relationship: in, Rate your health; The weighting coefficients for the contact degradation index, The weighting coefficient for the consistency deviation index; For contact degradation indicators; This is a consistency deviation indicator.

5. The real-time monitoring method of the operating state of a DC motor with speed feedback according to claim 1, characterized in that, The process of acquiring the AC ripple signal includes: acquiring the speed feedback voltage of the tachogenerator through a high-precision industrial acquisition device; calculating the sliding average value of the speed feedback voltage within a preset time window; and subtracting the corresponding sliding average value from the speed feedback voltage to obtain the AC ripple signal after filtering out the DC fundamental wave.

6. The real-time monitoring method of the operating state of a DC motor with speed feedback according to claim 1, characterized in that, When performing multi-band decomposition on the AC ripple signal, the AC ripple signal is divided into multiple independent frequency bands by wavelet packet decomposition technology, and the high-frequency noise frequency band range belonging to the contact between the carbon brush and commutator of the tachogenerator is determined according to the rated speed of the tachogenerator and the number of commutator segments.

7. The real-time monitoring method of the operating state of a DC motor with speed feedback according to claim 1, characterized in that, The extraction process of the current commutation ripple frequency includes: performing power spectral density analysis on the armature current, identifying the main peak frequency with the largest energy amplitude in the spectrum, performing logical verification on the main peak frequency according to the pole pair number and slot number parameters of the DC motor to eliminate interference frequencies, and locking the current commutation ripple frequency that characterizes the actual speed of the DC motor.

8. The real-time monitoring method of the operating state of a DC motor with speed feedback according to claim 1, characterized in that, The health score is divided into a healthy operation zone, a wear warning zone, and a fault shutdown zone.

9. The real-time monitoring method of the operating state of a DC motor with speed feedback according to claim 1, characterized in that, The speed feedback voltage is derived from a tachogenerator coaxially connected to the DC motor, and the armature current is obtained through a shunt or Hall sensor connected in series with the DC motor bus.

10. A real-time monitoring system for the operating state of a DC motor with speed feedback, characterized in that include: A processor and a memory, wherein the memory stores computer program instructions that, when executed by the processor, implement a real-time monitoring method for the operating status of a DC motor with speed feedback according to any one of claims 1-9.

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