A real-time monitoring method and system for motor operating status

Abstract

The present invention provides a method and system for real-time monitoring of the operating status of an electric motor. The monitoring system comprises a motor sampling module, a calculation and analysis module, and a display module, all connected in sequence. The monitoring method includes collecting real-time voltage and current data of the electric motor via the motor sampling module and transmitting the data to the calculation and analysis module via a communication cable. The calculation and analysis module then performs coordinate transformation and rotation transformation based on the electric motor's vector control algorithm to obtain the motor's real-time speed, torque, and magnetic flux data. The calculation and analysis module then further analyzes the data to obtain torsional vibration and torque pulsation data via bandpass and lowpass filtering. The data is then transmitted to the display module via a communication cable for real-time display and storage. The present invention effectively monitors parameters such as torsional vibration and torque pulsation of the electric motor without requiring the installation of additional mechanical sensors. The method has the advantages of high precision, strong anti-interference capability, and high real-time performance.

Description

Technical Field

[0001] The present invention relates to the field of motor monitoring technology, and in particular discloses a real-time monitoring method and a monitoring system for the motor operating status. The method realizes real-time and high-precision monitoring of the motor operating status based on voltage and current sampling and a vector control algorithm of the motor in combination with communication transmission technology. Background Art

[0002] As a power electronic device that drives electric motors, frequency converters (VFDs) can achieve energy conservation and emission reduction through their speed regulation, while also meeting the speed regulation requirements of process sites. Since electric motors can operate at varying speeds, and the VFD output voltage contains high-order harmonics caused by the switching frequency of power electronic components, these harmonics can affect the motor's normal operation. With the increasing use of VFDs, load systems are more susceptible to mechanical damage due to shaft torsional vibration after VFD speed regulation. To effectively prevent this, VFDs are developing active suppression features for system torsional vibrations. Furthermore, various sensors are used to monitor torsional vibrations in real time, initiating shutdown protection measures when limits are exceeded.

[0003] Existing motor monitoring technologies often rely on built-in sensors combined with corresponding algorithms to monitor the motor's operating status in real time. This can generally detect motor anomalies or faults, such as overload, short circuit, and phase loss. Furthermore, real-time monitoring and control of motor operating parameters, such as voltage, current, power, and speed, ensures optimal motor operation. This is particularly true for inverter-driven motors operating at varying speeds. Maintaining the rated motor flux, output voltage, output current, and load torque within these parameters is essential for optimal motor operation. These monitoring data all involve collecting electrical signals. To monitor non-electrical information, such as the motor's torsional vibration amplitude and torque ripple, magnetoelectric sensors or geared discs are typically installed on the motor to obtain key parameters such as speed and torque. However, these traditional monitoring methods have numerous drawbacks. Installing sensors or geared discs increases the motor's mechanical complexity, potentially leading to wear or failure. Furthermore, these sensors require high installation location and precision, and are susceptible to electromagnetic interference, compromising measurement accuracy and reliability. In addition, traditional monitoring methods make it difficult to obtain real-time information such as the motor's torsional vibration data and torque pulsation, and cannot meet the modern industry's demand for high-precision and high-reliability monitoring of the motor's operating status. Summary of the Invention

[0004] The purpose of the present invention is to solve the defects of the prior art and provide a real-time monitoring method and monitoring system for the operating status of an electric motor. By installing a motor sampling module close to the motor side, the voltage and current of the motor are collected in real time, and the data is transmitted to the calculation and analysis module using a communication cable. Based on the vector control algorithm of the motor, coordinate transformation and rotation transformation methods are used to parse the real-time speed, real-time torque and real-time flux data of the motor, and further analyze and obtain data information such as the torsional vibration data and torque pulsation of the motor, thereby realizing efficient and high-precision real-time monitoring of the operating status of the motor.

[0005] The present invention is implemented as follows: a real-time monitoring method and a monitoring system for the running state of a motor, wherein the monitoring method comprises the following steps:

[0006] S1. Data input: Set the nameplate parameters of the motor to be collected through the display module with input function module, including the motor rated voltage, rated current, rated frequency and rated speed, etc.

[0007] S2. Data collection: The motor sampling module located on the motor power input circuit collects the motor's real-time voltage and current data.

[0008] S3, data transmission: the real-time voltage and real-time current data collected in step S2 are transmitted to the calculation and analysis module via a communication cable, wherein the communication cable is an optical fiber.

[0009] S4. Data analysis: The calculation and analysis module performs coordinate transformation and rotation transformation on the real-time voltage and real-time current data collected in step S2 based on the vector control algorithm of the motor, and parses the real-time speed, real-time torque and real-time flux data of the motor, and further analyzes and obtains the torsional vibration data and torque pulsation data of the motor through bandpass filtering and low-pass filtering. The process of coordinate transformation and rotation transformation is: first, through 3-2 transformation, the static three-phase current is converted into a static two-phase current in the αβ coordinate system, and then through dq transformation, the static two-phase current in the αβ coordinate system is converted into a rotating two-phase current in the dq coordinate system, and the torque current component and the excitation current component are obtained respectively. The calculation and analysis module uses a flux observer to obtain the orientation angle of the motor flux in the dq transformation.

[0010] The calculation and analysis module calculates the angular velocity ω according to the orientation angle of the motor magnetic flux. r And the real-time torque T is processed by low-pass filtering and band-pass filtering to obtain the torsional vibration data and torque pulsation data of the motor, where the center frequency of the band-pass filter is the mechanical rotation frequency of the motor, and the real-time speed ω is obtained by the angular velocity ω rCombined with the number of motor pole pairs and real-time torque calculation, the speed ω after bandpass filtering is subtracted from the real-time speed ω h And the speed ω after low-pass filtering g , obtain the torsional vibration data ω of the motor t Similarly, after low-pass filtering and band-pass filtering of the real-time torque T of the motor, the torque pulsation data T of the motor is obtained. t .

[0011] S5. Data display: The display module receives the processed data obtained in step S4 through the communication cable and displays the real-time speed, real-time torque, real-time magnetic flux, torsional vibration data and torque ripple data of the motor as well as historical data curves and operating trends in real time.

[0012] S6. Data storage: The display module has a memory and a data storage function to store various data of the motor.

[0013] The monitoring system used for the monitoring method includes a motor sampling module, a calculation and analysis module and a display module connected in sequence, wherein the motor sampling module is installed near the input end of the motor, and includes a current sensor and a voltage sensor arranged on the motor power input line, which are used to collect real-time voltage and real-time current data of the motor. The calculation and analysis module is connected to the motor sampling module through a communication cable, receives the real-time voltage and real-time current data collected by the motor sampling module, and performs analysis and processing. The display module is connected to the calculation and analysis module using a communication cable, and is used to display the results obtained by the calculation and analysis module in real time and store data. The display module also has an input function module for setting the nameplate parameters of the monitored motor.

[0014] The communication cable between the display module and the calculation and analysis module adopts optical fiber.

[0015] The motor is driven by power input from a motor driver or directly driven by a power grid. The motor driver is a frequency converter or a frequency converter, or an AC motor driver.

[0016] The display module is provided with a memory including one or more readable storage media.

[0017] In the monitoring system, a set of calculation and analysis modules can be connected to multiple sets of motor sampling modules using communication cables. The multiple sets of motor sampling modules are respectively used to collect voltage and current samples of multiple motors.

[0018] The beneficial effects of the present invention are:

[0019] 1. No need to install magnetoelectric sensors or gear discs and other mechanical devices on the motor, thus avoiding mechanical wear and installation complexity;

[0020] 2. It can collect and analyze the motor's operating data in real time, and display it in real time through the display device. Combined with the historical data curve, it is convenient for users to find abnormal status of the motor's operation in time;

[0021] 3. It can not only obtain the basic operating parameters of the motor, but also further analyze advanced information such as torsional vibration data and torque ripple, meeting the high requirements of modern industry for motor monitoring;

[0022] 4. The communication cable for transmitting data between the motor sampling module and the calculation and analysis module uses optical fiber, which can effectively avoid electromagnetic interference and further ensure the stability and reliability of data transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of the real-time monitoring system for the motor operating status of the present invention.

[0024] Figure 2 This is a schematic diagram of the calculation and data transmission process for the calculation and analysis module in the present invention to obtain the real-time speed, real-time driving torque and real-time magnetic flux of the motor.

[0025] Figure 3 is based on Figure 2 The real-time angular velocity of the motor obtained in the calculation is low-pass filtered and band-pass filtered to obtain the motor torsional vibration data.

[0026] Figure 4 is based on Figure 2 The real-time driving torque of the motor obtained in the process is low-pass filtered and band-pass filtered to obtain the motor torque ripple data.

[0027] Figure 5 It is a schematic diagram of the connection structure of the second embodiment of the present invention.

[0028] In the figure: 1. First motor sampling module; 11. Current sensor; 12. Voltage sensor; 13. Second motor sampling module;

[0029] 2. Calculation and analysis module; 3. Display module; 4. First motor; 41. Second motor;

[0030] 5. First communication cable; 51. Second communication cable; 52. Third communication cable; 53. Fourth communication cable;

[0031] 6. First motor driver; 61. Second motor driver;

[0032] 7. First encoder speed measurement sampling module; 71. Second encoder speed measurement sampling module;

[0033] 8. First speed encoder; 81. Second speed encoder. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1:

[0036] like Figure 1 As shown, the present invention provides a method and system for real-time monitoring of the operating status of a motor. The monitoring system includes a first motor sampling module 1, a calculation and analysis module 2, and a display module 3, which are connected in sequence. The first motor sampling module 1 is installed near the input end of a first motor 4 and includes a current sensor 11 and a voltage sensor 12 provided on the power input line of the first motor 4 for collecting real-time voltage and real-time current data of the first motor 4. The calculation and analysis module 2 is connected to the first motor sampling module 1 via a first communication cable 5, receives the real-time voltage and real-time current data collected by the first motor sampling module 1, and performs analysis and processing. The display module 3 is connected to the calculation and analysis module 2 via a communication cable, and displays the analysis results obtained by the calculation and analysis module 2 in real time and stores the data. The display module 3 includes an input function module for inputting nameplate parameters of the monitored motor. The first motor 4 is driven by a first motor driver 6 inputting power or directly driven by the power grid. The first motor driver 6 can be a frequency converter, a frequency converter, an AC motor driver, or other type of motor driver. The communication cable in the monitoring system is optical fiber.

[0037] According to the attached Figure 1 ~Attachment Figure 3 The method for real-time monitoring of the motor operating status of the present invention comprises the following steps:

[0038] S1. Data input: Set the nameplate parameters of the motor that need to be collected through the display module with input function module, such as motor rated voltage, rated current, rated frequency and rated speed, etc.

[0039] S2. Data collection: The first motor sampling module 1 collects the real-time voltage and current data of the first motor 4.

[0040] S3, data transmission: the collected real-time voltage and real-time current data are transmitted to the calculation and analysis module 2 through the first communication cable 5,

[0041] S4. Data analysis: The calculation and analysis module 2 performs coordinate transformation and rotation transformation on the collected real-time voltage and real-time current data based on the vector control algorithm of the motor, and parses the real-time speed, real-time torque and real-time flux data of the first motor 4. It then further analyzes and obtains the torsional vibration data and torque ripple data of the motor through bandpass filtering and low-pass filtering.

[0042] S5, data display: The real-time speed, real-time torque, real-time magnetic flux, torsional vibration data and torque pulsation data of the motor obtained in step S4, as well as the historical data curve and operation trend are displayed in real time through the display module 3.

[0043] S6. Data storage: Various data of the motor are stored through the data storage function of the display module 3.

[0044] The three-phase currents collected by the current sensor 11 in the first motor sampling module 1 in step S2 are respectively expressed as I a , I b and I c Indicates that the voltage sensor 12 collects the three-phase voltages using U a 、U b and U c Indicates that the current sensor 11 can also only collect two-phase currents, and the third-phase current can be calculated by formula (1):

[0045] (1).

[0046] In step S4, the calculation and analysis module 2 uses a flux observer to obtain the orientation angle of the motor flux. The flux observer uses formula (2) to calculate the orientation angle θ:

[0047] (2).

[0048] In step S4, the real-time voltage and current data collected are subjected to coordinate transformation and rotation transformation to obtain the torque current component I ds and the excitation current component I qs The transformation process is as follows: first, through 3-2 transformation, the static three-phase current I a , I b and I c Converted into the stationary two-phase current I in the αβ coordinate system α , I β , and then through dq transformation, the static two-phase current in the αβ coordinate system is converted into the rotating two-phase current in the dq coordinate system, that is, the torque current component I is obtained respectively ds and the excitation current component I qs .

[0049] The 3-2 transformation is shown in formula (3):

[0050] (3) .

[0051] The dq transformation is shown in formula (4):

[0052] (4) .

[0053] The flux observer of the calculation and analysis module 2 uses formula (5) to calculate the angular velocity ω r :

[0054] (5).

[0055] The real-time magnetic flux value in step S4 Calculated by formula (6):

[0056] (6).

[0057] The real-time torque T of the first motor 4 is calculated by formula (7):

[0058] (7).

[0059] The real-time speed ω is calculated by formula (8):

[0060] (8),

[0061] Among them S k is the slip compensation coefficient. When the motor is an excitation synchronous motor or a permanent magnet synchronous motor, S k =0, p is the number of motor pole pairs.

[0062] In step S4, the calculation and analysis module of the monitoring system calculates the angular velocity ω according to the orientation angle of the motor flux. r And the real-time torque T is processed by low-pass filtering and band-pass filtering to obtain the torsional vibration data and torque pulsation data of the motor, where the center frequency of the band-pass filter is the mechanical rotation frequency of the motor, and the real-time speed ω is obtained by the angular velocity ω r Combined with the number of motor pole pairs and real-time torque calculation, the speed ω after bandpass filtering is subtracted from the real-time speed ω h And the speed ω after low-pass filtering g , obtain the torsional vibration data ω of the motor t Similarly, after low-pass filtering and band-pass filtering of the real-time torque T of the motor, the torque pulsation data T of the motor is obtained. t .

[0063] The transfer function H(s) of the bandpass filter is expressed as formula (9):

[0064] (9),

[0065] The three coefficients a, b, and c of the filter can be determined according to the three variables: the frequency point ω0 at which the filter acts, the notch bandwidth parameter k1, and the notch depth parameter k2.

[0066] The transfer function G(s) of the low-pass filter is expressed as formula (10):

[0067] (10),

[0068] Where, T d is the time constant of the low-pass filter.

[0069] Example 2:

[0070] According to the attached Figure 5 The real-time monitoring system for the operation status of an electric motor described in the present invention adopts a set of calculation and analysis modules 2 to be applied to multiple sets of motor sampling modules to respectively perform voltage and current sampling on different motors, and a schematic diagram of the connection relationship is provided. The calculation and analysis module 2 is connected to the multiple sets of motor sampling modules through communication cables and transmits the sampling data. The calculation and analysis module 2 calculates and processes the sampling data of each motor separately according to the parameters of different motors set by the input function module of the display module 3, and then obtains the torsional vibration data and torque pulsation of each motor.

[0071] To further improve the calculation accuracy, a speed encoder is provided on the motor side, and is connected to the encoder speed sampling module via a communication cable and then to the calculation and analysis module 2. The calculation and analysis module 2 can directly obtain the rotation speed of the motor rotor. In this embodiment, a first speed encoder 8 is provided on one side of the first motor 4, which is then connected to the first encoder speed sampling module 7 via a communication cable and then to the calculation and analysis module 2 via a fourth communication cable 53. A second speed encoder 81 is provided on one side of the second motor 41, which is then connected to the second encoder speed sampling module 71 via a communication cable and then to the calculation and analysis module 2 via a third communication cable 52. A second motor sampling module 13 is installed on the power input line of the second motor 41 and is connected to the calculation and analysis module 2 via a second communication cable 51. The first motor 4 is driven by the input power of the first motor driver 6, and the second motor 41 is driven by the input power of the second motor driver 61. The rest is the same as in Example 1. The connection method of providing two or more sets of motor sampling modules for respectively sampling voltage and current of different motors is similar.

[0072] Optionally, the communication cable between the motor sampling module and the calculation and analysis module uses optical fiber, which can effectively avoid electromagnetic interference and ensure the stability and reliability of data transmission.

[0073] Optionally, the motor operating frequency obtained by the calculation and analysis module is the fundamental frequency, and an FFT calculation with a variable fundamental frequency can be performed on the voltage and current of the motor.

[0074] The calculation and analysis module may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor may be implemented in at least one of the following hardware forms: a DSP (Digital Signal Processing), an FPGA (Field-Programmable Gate Array), or a PLA (Programmable Logic Array).

[0075] The display module may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content displayed on the display screen. The display module also includes memory, which may include one or more readable storage media, such as high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory storage devices.

[0076] The above-described specific embodiments are merely preferred embodiments of the present invention and are intended to explain the present invention in detail, but are not intended to limit the present invention. It is apparent that persons skilled in the art may make various equivalent modifications, variations, and substitutions to the specific embodiments based on the disclosure of the present invention, and such equivalent modifications, variations, and substitutions shall fall within the scope of protection of the present invention. The scope of protection of the present invention shall be determined by the description of the claims of this application.

Claims

1. A method for real-time monitoring of the operating status of a motor, characterized in that: The monitoring method comprises the following steps: S1. Data input: Set the nameplate parameters of the motor to be collected through the display module with input function module, including the motor rated voltage, rated current, rated frequency and rated speed. S2. Data collection: The motor sampling module located on the motor power input circuit collects the motor's real-time voltage and current data. S3, data transmission: the real-time voltage and real-time current data collected in step S2 are transmitted to the calculation and analysis module through the communication cable, S4, data analysis: The calculation and analysis module performs coordinate transformation and rotation transformation on the real-time voltage and real-time current data collected in step S2 based on the vector control algorithm of the motor, and parses the real-time speed, real-time torque and real-time flux data of the motor. It further analyzes and obtains the torsional vibration data and torque ripple data of the motor through bandpass filtering and low-pass filtering. S5. Data display: The display module receives the processed data obtained in step S4 through the communication cable and displays the real-time speed, real-time torque, real-time magnetic flux, torsional vibration data and torque ripple data of the motor as well as historical data curves and operating trends in real time. S6. Data storage: The display module has a memory and a data storage function to store various data of the motor. In step S4, the calculation and analysis module uses a flux observer to obtain the orientation angle of the motor flux. The flux observer uses formula (2) to calculate the orientation angle θ. The three-phase voltages collected in step S2 are respectively expressed as U a 、U b and U c express: （2）， The flux observer of the calculation and analysis module uses formula (5) to calculate the angular velocity ω r : （5）， The real-time magnetic flux value in step S4 Calculated by formula (6): （6）， The real-time torque T of the first motor is calculated by formula (7): （7）， Among them I ds The torque current component is obtained by performing coordinate transformation and rotation transformation on the real-time voltage and real-time current data collected in step S4. The real-time speed ω is calculated by formula (8): （8）， Among them S k is the slip compensation coefficient. When the motor is an excitation synchronous motor or a permanent magnet synchronous motor, S k =0, p is the number of motor pole pairs, In step S4, the calculation and analysis module of the monitoring system calculates the angular velocity ω according to the orientation angle of the motor flux. r And the real-time torque T is processed by low-pass filtering and band-pass filtering to obtain the torsional vibration data and torque pulsation data of the motor, where the center frequency of the band-pass filter is the mechanical rotation frequency of the motor, and the real-time speed ω is obtained by the angular velocity ω r Combined with the number of motor pole pairs and real-time torque calculation, the speed ω after bandpass filtering is subtracted from the real-time speed ω h And the speed ω after low-pass filtering g , obtain the torsional vibration data ω of the motor t Similarly, after low-pass filtering and band-pass filtering of the real-time torque T of the motor, the torque pulsation data T of the motor is obtained. t .

2. A method for real-time monitoring of motor operating status according to claim 1, characterized in that: The communication cable described in step S3 is an optical fiber.

3. The method for real-time monitoring of motor operating status according to claim 1, characterized in that: The process of performing coordinate transformation and rotation transformation on the collected real-time voltage and real-time current data in step S4 is as follows: first, through 3-2 transformation, the static three-phase current is converted into a static two-phase current in the αβ coordinate system, and then through dq transformation, the static two-phase current in the αβ coordinate system is converted into a rotating two-phase current in the dq coordinate system to obtain the torque current component and the excitation current component respectively. The calculation and analysis module uses a flux observer to obtain the orientation angle of the motor flux in the dq transformation.

4. A method for real-time monitoring of motor operating status according to claim 1 or 2, characterized in that: In step S4, the calculation and analysis module calculates the angular velocity ω according to the orientation angle of the motor flux. r And the real-time torque T is processed by low-pass filtering and band-pass filtering to obtain the torsional vibration data and torque pulsation data of the motor, where the center frequency of the band-pass filter is the mechanical rotation frequency of the motor, and the real-time speed ω is obtained by the angular velocity ω r Combined with the number of motor pole pairs and real-time torque calculation, the speed ω after bandpass filtering is subtracted from the real-time speed ω h And the speed ω after low-pass filtering g , obtain the torsional vibration data ω of the motor t Similarly, after low-pass filtering and band-pass filtering of the real-time torque T of the motor, the torque pulsation data T of the motor is obtained. t .

5. A real-time monitoring system for the operation status of a motor, used in the real-time monitoring method for the operation status of a motor as claimed in any one of claims 1 to 4, characterized in that: It includes a motor sampling module, a calculation and analysis module and a display module connected in sequence, wherein the motor sampling module is installed near the input end of the motor, includes a current sensor and a voltage sensor arranged on the motor power input line, and is used to collect real-time voltage and real-time current data of the motor. The calculation and analysis module is connected to the motor sampling module through a communication cable, receives the real-time voltage and real-time current data collected by the motor sampling module, and performs analysis and processing. The display module is connected to the calculation and analysis module through a communication cable, and is used to display the results obtained by the calculation and analysis module in real time and store data. The display module also has an input function module, which is used to set the nameplate parameters of the monitored motor.

6. A real-time monitoring system for motor operating status according to claim 5, characterized in that: The communication cable between the display module and the calculation and analysis module adopts optical fiber.

7. The real-time monitoring system for motor operation status according to claim 5, characterized in that: The electric motor is driven by an input power supply from a motor driver or directly driven by a power supply grid.

8. A real-time monitoring system for motor operating status according to claim 5 or 6, characterized in that: One set of the calculation and analysis modules is connected to multiple sets of motor sampling modules for correspondingly collecting voltage and current samples of multiple motors using communication cables.

9. The real-time monitoring system for motor operating status according to claim 5, characterized in that: The display module is provided with a memory including one or more readable storage media.

10. A real-time monitoring system for motor operating status according to claim 5 or 7, characterized in that: The motor driver is a frequency converter or a frequency converter, or an AC motor driver.

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