Alternating current motor dynamic open-phase diagnosis method and system
By directly using the magnitude and phase relationship of the three-phase current for dynamic phase loss diagnosis, the existing methods are solved by the impact of current frequency and false alarms, achieving higher diagnostic accuracy and lower implementation cost.
Patent Information
- Application Number
- CN202411681777.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-02-25
AI Technical Summary
The existing dynamic phase loss detection method is based on the three-phase imbalance strategy, which is easily affected by the current frequency, has poor calculation accuracy, and is prone to false alarms when judging the phase loss.
By directly utilizing the magnitude and phase relationship of the three-phase current during phase loss, dynamic phase loss diagnosis is not required to calculate the three-phase imbalance, which simplifies the diagnostic process and reduces the computational complexity.
It improves the accuracy of phase-deficiency diagnosis, reduces calculation errors caused by current frequency changes, can quickly identify phase-deficiency failures, and avoids false alarms at low speeds and low torques, reducing implementation costs.
Smart Images
Figure CN119510918A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of motor control, and in particular to a method and system for diagnosing dynamic phase loss of an AC motor. Background Art
[0002] During the operation of AC motors, three-phase AC is a common power supply method, including three-phase four-wire star (Y-shaped) and three-phase three-wire triangle connection methods. When three-phase AC is applied to the three-phase stator winding (each phase differs by 120 degrees electrical angle), a three-phase motor will generate a rotating magnetic field, which cuts the rotor winding to generate electricity. However, during long-term use, the three-phase power line may become loose or broken due to vibration, corrosion and other reasons, resulting in failure of the connection between the motor drive controller and the drive motor. This phenomenon is called phase loss. Phase loss will cause abnormal phenomena such as excessive torque output pulsation, AC current waveform distortion, and increased motor noise. In severe cases, overcurrent may occur, and even damage the controller or motor. Therefore, it is very important to perform dynamic phase loss diagnosis on the motor.
[0003] At present, the existing dynamic phase loss detection methods are mainly based on multivariable conditions or three-phase imbalance strategies. These methods require calculating the average value of the three-phase current for several cycles in the software, and then calculating the three-phase imbalance to perform phase loss diagnosis. However, these methods have obvious disadvantages: first, the calculation of the three-phase imbalance is easily affected by the current frequency. When the current frequency changes greatly, the accuracy of the imbalance calculation is poor; second, the judgment of phase loss diagnosis is only based on the three-phase imbalance, which is prone to false alarms. Summary of the invention
[0004] To solve the above problems, the present invention provides a method and system for dynamic phase loss diagnosis of an AC motor, which performs dynamic phase loss diagnosis by directly utilizing the magnitude and phase relationship of the three-phase current when a phase is lost, without calculating the three-phase imbalance, thereby simplifying the diagnosis process and reducing the complexity of the calculation.
[0005] The above objectives can be achieved through the following solutions:
[0006] A method for dynamic phase loss diagnosis of an AC motor comprises: determining to start dynamic phase loss diagnosis of the AC motor; periodically collecting three-phase current data, analyzing the absolute values and phase relationships of the three-phase currents; and obtaining a phase loss diagnosis result according to the absolute values and phase relationships of the three-phase currents.
[0007] Optionally, determining to start the dynamic phase loss diagnosis of the AC motor includes: judging whether to start the dynamic phase loss diagnosis of the AC motor based on the speed value and torque value of the AC motor; wherein, comparing the speed value with a first threshold, and comparing the torque value with a second threshold; determining to start the dynamic phase loss diagnosis of the AC motor based on the comparison result of the speed value with the first threshold and the comparison result of the torque value with the second threshold.
[0008] Optionally, the determination of starting the dynamic phase loss diagnosis of the AC motor also includes: judging whether there is a subsequent stage shutdown, shutdown, derating or three-phase current and fault; if there is a subsequent stage shutdown, shutdown, derating or three-phase current and fault, no dynamic phase loss diagnosis is performed; if there is no subsequent stage shutdown, shutdown, derating or three-phase current and fault, dynamic phase loss diagnosis is performed.
[0009] Optionally, the method further includes: if dynamic phase loss diagnosis is not performed, determining again after a predetermined time whether there is a subsequent stage shutdown, shutdown, derating or three-phase current and fault.
[0010] Optionally, obtaining a phase loss diagnosis result based on the absolute values of the three-phase currents and the phase relationship includes: setting a third threshold value for the phase current; determining whether the absolute value of the first phase current value is less than or equal to the third threshold value; if the absolute value of the first phase current value is less than or equal to the third threshold value, determining whether the absolute value of the sum of the second phase current value and the third phase current value is less than or equal to the third threshold value; if the absolute value of the sum of the second phase current value and the third phase current value is less than or equal to the third threshold value, diagnosing that the first phase is missing and obtaining a phase loss signal.
[0011] Optionally, the method further includes: if the first phase current value is 0, and the phase difference between the second phase and the third phase is 180 degrees, then the first phase should be diagnosed as being missing and the phase missing signal should be obtained.
[0012] Optionally, the method also includes: setting a fourth threshold for the number of times the phase loss signal is obtained; determining whether the number is greater than or equal to the fourth threshold; if the number is less than the fourth threshold, continuing to periodically collect the three-phase current data and re-diagnosing; if the number is greater than or equal to the fourth threshold, outputting the diagnostic result as the first phase being lost.
[0013] Based on the same inventive concept, the present invention also provides an AC motor dynamic phase loss diagnosis system, the system comprising: a dynamic defect detection enabling module and a current relationship judgment module, the dynamic defect detection enabling module comprising a data acquisition submodule and a condition judgment submodule, the current relationship judgment module comprising a current relationship analysis submodule and a result output submodule; wherein the data acquisition submodule is used to collect the speed and torque of the AC motor; the data acquisition submodule is also used to periodically collect three-phase current data; the condition judgment submodule is used to determine whether to start the dynamic phase loss diagnosis of the AC motor; the current relationship analysis submodule is used to analyze the absolute value and phase relationship of the three-phase current according to the collected three-phase current data when performing dynamic phase loss diagnosis; the phase loss diagnosis submodule is used to obtain the phase loss diagnosis result according to the absolute value and the phase relationship of the three-phase current.
[0014] Based on the same inventive concept, the present invention also provides a computer storage medium storing one or more programs, which can implement any of the aforementioned methods when the one or more programs are executed.
[0015] Based on the same inventive concept, the present invention also provides a device, including a processor, a communication interface, a memory and a communication bus; the processor, the communication interface and the memory communicate with each other through the communication bus; the processor is used to execute the program stored in the aforementioned computer-readable storage medium.
[0016] Compared with the prior art, the present invention has the following advantages:
[0017] 1. The present invention performs dynamic phase loss diagnosis by directly using the magnitude and phase relationship of the three-phase current when the phase is lost, without calculating the three-phase imbalance, thereby simplifying the diagnosis process and reducing the complexity of the calculation;
[0018] 2. The present invention avoids calculating the three-phase imbalance, reduces the calculation error caused by the change of current frequency, and improves the accuracy of phase loss diagnosis; at the same time, by accurately judging the phase and magnitude relationship of the three-phase current, the phase loss fault can be more reliably identified;
[0019] 3. The method of the present invention can complete the diagnosis within one current cycle and has the characteristics of rapid response. Compared with other methods that require the calculation of three-phase imbalance, the present invention has more advantages in time and can detect and handle phase failure in a shorter time, thereby effectively protecting the motor and drive system.
[0020] 4. The present invention sets reasonable speed and torque thresholds, and does not perform dynamic phase loss detection at low speed and low torque, thereby avoiding false alarm faults caused by small current amplitude and frequency; at the same time, for the subsequent stage shutdown, tube shutdown, derating, and three-phase current and fault conditions, dynamic phase loss detection is not performed, further reducing the possibility of false alarms;
[0021] 5. The present invention reduces the complicated calculation process and has a relatively low implementation cost. At the same time, since the method is simple and easy to implement, it can be conveniently applied to various motor drive systems, thereby improving its scope of application and practicality.
[0022] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0024] Figure 1 It is a flow chart of a method for diagnosing dynamic phase loss of an AC motor according to an embodiment of the present invention.
[0025] Figure 2 Schematic diagram of the relationship between the three-phase currents when phase A is missing in an embodiment of the present invention.
[0026] Figure 3 It is an execution flow chart of a method for diagnosing dynamic phase loss of an AC motor according to an embodiment of the present invention.
[0027] Figure 4 It is a structural schematic diagram of a dynamic phase loss diagnosis system for an AC motor according to an embodiment of the invention.
[0028] Figure 5 It is a schematic diagram of the structure of an electronic device according to an embodiment of the invention. DETAILED DESCRIPTION
[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0030] Reference Figure 1 An embodiment of the present invention proposes a method for dynamic phase loss diagnosis of an AC motor, which performs dynamic phase loss diagnosis by directly utilizing the magnitude and phase relationship of the three-phase current when the phase is lost, without calculating the three-phase imbalance, thereby simplifying the diagnosis process and reducing the complexity of the calculation.
[0031] The method of this embodiment specifically includes:
[0032] Determine the dynamic phase loss diagnosis of the starting AC motor;
[0033] Periodically collect three-phase current data and analyze the absolute value and phase relationship of the three-phase current;
[0034] A phase loss diagnosis result is obtained according to the absolute values of the three-phase currents and the phase relationship.
[0035] For example, Figure 2 As shown in the figure, after the dynamic phase loss diagnosis is turned on, the three-phase current data is periodically collected, for example, the three-phase current data is collected every 10ms; in a certain collection cycle, the three-phase current data is obtained as follows: Ia=0A, Ib=4.5A, Ic=-4.5A (the negative sign indicates that the current direction is opposite to the reference direction); the absolute value of the three-phase current is analyzed: it is found that the absolute value of Ia is 0A, while the absolute values of Ib and Ic are equal and not 0; the phase relationship of the three-phase current is analyzed: it is found that the phase difference between Ib and Ic is 180° (because their current values have opposite signs and equal magnitudes); according to the above analysis, it can be judged that the current of phase A is 0A, and the phase difference between phase B and phase C is 180°, which is consistent with the three-phase current change relationship when phase A is missing (such as Figure 2 As shown), therefore, the phase loss diagnosis result can be obtained as: phase A is missing; the present invention has the advantages of simplifying the diagnosis process, improving accuracy, rapid response, reducing false alarms and reducing implementation costs, and provides a new and effective method for dynamic phase loss diagnosis of motors.
[0036] Optionally, the determining to start the dynamic phase loss diagnosis of the AC motor includes:
[0037] Whether to start the dynamic phase loss diagnosis of the AC motor is determined according to the speed and torque values of the AC motor;
[0038] comparing the rotation speed value with a first threshold value, and comparing the torque value with a second threshold value;
[0039] According to the comparison result between the rotation speed value and the first threshold value and the comparison result between the torque value and the second threshold value, it is determined to start the dynamic phase loss diagnosis of the AC motor.
[0040] Specifically, when the dynamic phase loss diagnosis is not performed, the speed and torque value of the motor will continue to be monitored, and the dynamic phase loss diagnosis will be re-determined when the conditions are met.
[0041] For example, assume that there is an AC motor whose normal operating speed is 300rpm and the torque is 20NM, and the three-phase current (Ia, Ib, Ic) has a phase difference of 120° under normal circumstances, and the current value is equal (assuming it is 5A); use sensors to collect the motor speed and torque in real time. For example, at a certain moment, the motor speed is collected to be 250rpm and the torque is 18NM; set the first threshold to 200rpm and the second threshold to 15NM; compare the collected speed value (250rpm) with the first threshold (200rpm), and find that the speed is greater than the threshold; compare the collected torque value (18NM) with the second threshold (15NM), and find that the torque is also greater than the threshold; since both the speed and torque are greater than their respective thresholds, the conditions for starting dynamic phase loss diagnosis are met.
[0042] For example, assume that there is an AC motor whose operating status is monitored by a control system; in order to perform dynamic phase loss diagnosis, it is necessary to obtain the motor's speed and torque values and compare them with preset thresholds; the motor's speed and torque values are obtained in real time through sensors. For example, assume that the currently measured speed value is 180rpm and the torque value is 10NM; the measured speed value is compared with a preset first threshold (such as 200rpm), and the measured torque value is compared with a preset second threshold (such as 15NM); since the speed value of 180rpm is less than the first threshold of 200rpm, and the torque value of 10NM is less than the second threshold of 15NM, the judgment condition is not met. According to the judgment result, since both the speed and torque values do not reach the preset thresholds, dynamic phase loss diagnosis is not performed. This is because at low speeds and low torques, the motor's current amplitude and frequency are small, and performing phase loss diagnosis may result in false alarms, affecting the stability and reliability of the system.
[0043] Optionally, the determining to start the dynamic phase loss diagnosis of the AC motor further includes:
[0044] Determine whether there is a subsequent shutdown, shutdown, derating, or three-phase current and fault;
[0045] If the subsequent stage is shut down, shut down, derated, or the three-phase current and fault occur, dynamic phase loss diagnosis will not be performed;
[0046] If there is no subsequent stage shutdown, shutdown, derating or three-phase current and fault, dynamic phase loss diagnosis is performed.
[0047] Specifically, when the AC motor is shut down, shut down, derated, or has a three-phase current and fault, the actual torque of the motor has dropped to 0NM or is in an abnormal state; at this time, if dynamic phase loss diagnosis is performed, it may cause misdiagnosis due to abnormal changes in current amplitude and frequency; therefore, in order to avoid false alarms and ensure the accuracy of diagnosis, dynamic phase loss diagnosis is not started under these fault conditions.
[0048] For example, suppose there is an AC motor, which has a speed of 300rpm and a torque of 20NM during normal operation; at this time, the three-phase current (Ia, Ib, Ic) of the motor is in a normal state, with a phase difference of 120°, and the current value is stable; however, when the motor has a rear-stage shutdown fault, the actual torque of the motor quickly drops to 0NM; at this time, if dynamic phase loss diagnosis is performed, due to abnormal changes in current amplitude and frequency, the diagnostic system may misjudge that the motor has a phase loss fault; in order to avoid such false alarms, according to the description in the technical solution, when the rear-stage shutdown, shutdown, derating or three-phase current and fault are detected, the dynamic phase loss diagnosis is not started; similarly, if the motor has a shutdown, derating or three-phase current and fault, it will also cause a misdiagnosis due to similar abnormal current changes. Therefore, in these fault states, dynamic phase loss diagnosis is also not performed.
[0049] Optionally, the method further comprises:
[0050] If dynamic phase loss diagnosis is not performed, it is determined again after a predetermined time whether there is a subsequent stage shutdown, shutdown, derating, or three-phase current and fault.
[0051] Exemplarily, the motor is operating normally with the speed and torque both within the normal range, and suddenly a rear-stage shutdown fault is detected (for example, a key circuit is accidentally cut off). At this time, the dynamic phase loss diagnosis should not be started because the actual torque may have dropped to 0, which may easily lead to misdiagnosis. The time when the fault occurred is recorded, and after a predetermined time (for example, 1 second or as set), check again whether there is a rear-stage shutdown, shutdown, derating or three-phase current and fault. Assuming that after the predetermined time, the system detects that the rear-stage shutdown fault has been repaired (for example, the circuit has been reconnected), after confirming that the fault has been repaired, check the speed and torque of the motor again. If the speed and torque are both greater than the set first and second thresholds (for example, the speed is greater than 200rpm and the torque is greater than 15NM), re-perform dynamic phase loss diagnosis.
[0052] Optionally, obtaining a phase loss diagnosis result according to the absolute values of the three-phase currents and the phase relationship includes:
[0053] Setting a third threshold value of the phase current;
[0054] Determine whether the absolute value of the first phase current value is less than or equal to the third threshold;
[0055] If the absolute value of the first phase current value is less than or equal to the third threshold, determining whether the absolute value of the sum of the second phase current value and the third phase current value is less than or equal to the third threshold;
[0056] If the absolute value of the sum of the second phase current value and the third phase current value is less than or equal to the third threshold, a first phase failure is diagnosed and a phase failure signal is obtained.
[0057] Specifically, when a phase is missing, the current of this phase will become zero or close to zero, depending on the specific design and fault conditions; wherein, the third threshold is a preset threshold used to determine whether the current value is close to 0 and whether the sum of the two-phase currents is also close to 0; when the absolute value of the B-phase current Ib is less than or equal to the third threshold, and the absolute value of the sum of the A-phase and C-phase currents is also less than or equal to the third threshold, it can be determined whether a phase is missing.
[0058] For example, Figure 3 As shown, the first phase, the second phase, and the third phase can be phase A, phase B, and phase C, or phase C, phase A, and phase B, or phase B, phase C, and phase A; assuming that there is a three-phase AC motor, whose three phases are phase A, phase B, and phase C, a third threshold value of the phase current can be set, for example, set to 10A (this value can be adjusted according to actual conditions); measure the absolute value of the current value of phase A (denoted as Ia), and determine whether it is less than or equal to the third threshold value (10A). If |Ia|≤10A, then determine whether the absolute value of the sum of the current value of phase B (denoted as Ib) and the current value of phase C (denoted as Ic) is also less than or equal to the third threshold value, that is, determine whether |Ib+Ic|≤10A is established; if both of the above two conditions are met, then the phase A loss can be diagnosed and a phase loss output signal; similarly, measure the absolute value of the B-phase current and determine whether it is less than or equal to the third threshold. If the condition is met, we then determine whether the absolute value of the sum of the A-phase current and the C-phase current is also less than or equal to the third threshold, that is, determine whether |Ia+Ic|≤10A is established. If both conditions are met, the B-phase is diagnosed as being phase-lost, and a phase-lost signal is output; similarly, measure the absolute value of the C-phase current and make a similar judgment. If |Ic|≤10A and |Ia+Ib|≤10A, the C-phase is diagnosed as being phase-lost, and a phase-lost signal is output; by simply judging the absolute value and phase relationship of the three-phase current, the motor's phase-lost fault can be quickly and accurately diagnosed without complex calculations; this method not only reduces the amount of code, but also improves the accuracy and response speed of diagnosis.
[0059] Optionally, the method further comprises:
[0060] If the first phase current value is 0, and the phase difference between the second phase and the third phase is 180 degrees, the first phase should be diagnosed as being phase-lost and the phase-lost signal should be obtained.
[0061] Exemplarily, the currents of phases A, B and C are sampled by current sensors. Assume that at a certain sampling moment, we obtain a current value of phase A of 0, that is, Ia=0; then we need to determine the phase relationship between phases B and C. Since the phase difference of the three-phase current is 120 degrees when the motor is operating normally, if phase A is missing, the phase difference between phases B and C will become 180 degrees. Through a phase detection device or algorithm, it can be obtained that the phase difference between phases B and C is 180 degrees; based on the above judgment, when the current value of phase A is 0 and the phase difference between phases B and C is 180 degrees, it can be determined that a phase loss fault has occurred in phase A. At this time, the system should output a phase loss signal to indicate that phase A is missing; after receiving the phase loss signal, the system can take corresponding fault response measures, such as shutdown protection, alarm prompts, etc., to ensure the safe operation of the motor.
[0062] Optionally, the method further comprises:
[0063] Setting a fourth threshold value for the number of times the phase loss signal is obtained;
[0064] Determining whether the number of times is greater than or equal to a fourth threshold;
[0065] If the number of times is less than a fourth threshold, continue to periodically collect the three-phase current data and re-diagnose;
[0066] If the number of times is greater than or equal to a fourth threshold, the diagnosis result is output as the first phase being missing.
[0067] For example, Figure 3As shown, the fourth threshold N is set, which means that in the continuous diagnosis cycle, if the number of detected phase loss signals reaches or exceeds N times, the phase is confirmed to be lost; for example, N=3 can be set, which means that the phase loss is confirmed only when the phase loss signal is detected in three consecutive diagnosis cycles; in the first diagnosis cycle, the collected A-phase current value is 0, and the phase difference between phases B and C is 180 degrees, which meets the diagnosis condition of the first phase loss. At this time, we get a phase loss signal and record the number of times as 1; in the next second diagnosis cycle, the same data is collected again, that is, the A-phase current value is 0, the phase difference between phases B and C is 180 degrees, and a phase loss signal is obtained again, and the number of times is recorded as 2; in the third diagnosis cycle, it is still Then the same data is collected, the diagnostic condition of the first phase being lost is met, the third phase loss signal is obtained, and the number is recorded as 3; at this time, check whether the number of phase loss signals is greater than or equal to the fourth threshold value N. Since the phase loss signal has been detected for three consecutive cycles (number of times = 3), and 3 is greater than or equal to the set fourth threshold value N (N = 3), it can be confirmed that phase A is lost, and the diagnostic result is output as phase A loss, and corresponding measures are taken, such as alarm, shutdown, etc., to prevent further damage to the motor; by setting the fourth threshold value N and detecting the number of phase loss signals in consecutive diagnostic cycles, it is possible to more accurately determine whether the motor is phase-lost. This method can improve the accuracy and reliability of diagnosis and reduce false alarms and omissions.
[0068] Based on the same inventive concept, Figure 4 As shown, the present invention also provides an AC motor dynamic phase loss diagnosis system, the system includes: a dynamic defect detection enabling module and a current relationship judgment module, the dynamic defect detection enabling module includes a data acquisition submodule and a condition judgment submodule, the current relationship judgment module includes a current relationship analysis submodule and a result output submodule; wherein,
[0069] The data acquisition submodule is used to collect the speed and torque of the AC motor; the data acquisition submodule is also used to periodically collect three-phase current data;
[0070] The condition judgment submodule is used to make a judgment based on the size of the rotational speed and the first threshold value, and the size of the torque and the second threshold value; the condition judgment submodule is also used to perform dynamic phase loss diagnosis if the rotational speed value is greater than the first threshold value and the torque value is greater than the second threshold value; the condition judgment submodule is also used to not perform dynamic phase loss diagnosis if the rotational speed value is less than or equal to the first threshold value or the torque value is less than or equal to the second threshold value;
[0071] The current relationship analysis submodule is used to analyze the absolute values and phase relationships of the three-phase currents according to the collected three-phase current data when dynamic phase loss diagnosis is performed;
[0072] The phase loss diagnosis submodule is used to obtain a phase loss diagnosis result according to the absolute values of the three-phase currents and the phase relationship.
[0073] Based on the above disclosed content, the present invention also provides an electronic device. Figure 5 As shown, the electronic device of an embodiment of the present invention includes at least one electrically connected processor and at least one storage medium, wherein the storage medium is electrically connected to the processor, wherein the storage medium stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method as described above.
[0074] Based on the same inventive concept, the present invention also provides a storage medium, which stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the method as described above.
[0075] It should be noted that the electrical connection between the above-mentioned units does not necessarily mean the connection between lines. An indirect connection method can be applied to the embodiments of the present invention as long as the purpose of the present invention is achieved.
[0076] The above is only an exemplary embodiment of the present invention and cannot be used to limit the scope of the present invention. That is, any equivalent changes and modifications made according to the teachings of the present invention are still within the scope of the present invention. After considering the disclosure of the specification and the truth of practice, it will be easy for those skilled in the art to think of other embodiments of the present invention. This application is intended to cover any variation, use or adaptive change of the present invention, which follows the general principles of the present invention and includes common knowledge or customary technical means in the technical field not recorded in the present invention.
Claims
1. A method for dynamic phase loss diagnosis of an AC motor, characterized in that: The method comprises: Determine the dynamic phase loss diagnosis of the starting AC motor; Periodically collect three-phase current data and analyze the absolute value and phase relationship of the three-phase current; A phase loss diagnosis result is obtained according to the absolute values of the three-phase currents and the phase relationship.
2. The method for dynamic phase loss diagnosis of an AC motor according to claim 1, characterized in that: The determination of starting the dynamic phase loss diagnosis of the AC motor comprises: Whether to start the dynamic phase loss diagnosis of the AC motor is determined according to the speed and torque values of the AC motor; comparing the rotation speed value with a first threshold value, and comparing the torque value with a second threshold value; According to the comparison result between the rotation speed value and the first threshold value and the comparison result between the torque value and the second threshold value, it is determined to start the dynamic phase loss diagnosis of the AC motor.
3. The method for dynamic phase loss diagnosis of an AC motor according to claim 2, characterized in that: The determining and starting the dynamic phase loss diagnosis of the AC motor also includes: Determine whether there is a subsequent shutdown, shutdown, derating, or three-phase current and fault; If the subsequent stage is shut down, shut down, derated, or the three-phase current and fault occur, dynamic phase loss diagnosis will not be performed; If there is no subsequent stage shutdown, shutdown, derating or three-phase current and fault, dynamic phase loss diagnosis is performed.
4. The method for dynamic phase loss diagnosis of an AC motor according to claim 3, characterized in that: The method further comprises: If dynamic phase loss diagnosis is not performed, it is determined again after a predetermined time whether there is a subsequent stage shutdown, shutdown, derating, or three-phase current and fault.
5. The method for dynamic phase loss diagnosis of an AC motor according to claim 1, characterized in that: The step of obtaining the phase loss diagnosis result according to the absolute values of the three-phase currents and the phase relationship includes: Setting a third threshold value of the phase current; Determine whether the absolute value of the first phase current value is less than or equal to the third threshold; If the absolute value of the first phase current value is less than or equal to the third threshold, determining whether the absolute value of the sum of the second phase current value and the third phase current value is less than or equal to the third threshold; If the absolute value of the sum of the second phase current value and the third phase current value is less than or equal to the third threshold, a first phase failure is diagnosed and a phase failure signal is obtained.
6. The method for dynamic phase loss diagnosis of an AC motor according to claim 5, characterized in that: The method further comprises: If the first phase current value is 0, and the phase difference between the second phase and the third phase is 180 degrees, the first phase should be diagnosed as being phase-lost and the phase-lost signal should be obtained.
7. The method for dynamic phase loss diagnosis of an AC motor according to claim 6, characterized in that: The method further comprises: Setting a fourth threshold value for the number of times the phase loss signal is obtained; Determining whether the number is greater than or equal to a fourth threshold; If the number of times is less than a fourth threshold, continue to periodically collect the three-phase current data and re-diagnose; If the number of times is greater than or equal to a fourth threshold, the diagnosis result is output as the first phase being missing.
8. An AC motor dynamic phase loss diagnosis system, characterized in that: The system includes: a dynamic defect detection enabling module and a current relationship judgment module, wherein the dynamic defect detection enabling module includes a data acquisition submodule and a condition judgment submodule, and the current relationship judgment module includes a current relationship analysis submodule and a result output submodule; wherein, The data acquisition submodule is used to collect the speed and torque of the AC motor; the data acquisition submodule is also used to periodically collect three-phase current data; The condition judgment submodule is used to determine whether to start the dynamic phase loss diagnosis of the AC motor; The current relationship analysis submodule is used to analyze the absolute values and phase relationships of the three-phase currents according to the collected three-phase current data when dynamic phase loss diagnosis is performed; The phase loss diagnosis submodule is used to obtain a phase loss diagnosis result according to the absolute values of the three-phase currents and the phase relationship.
9. A computer storage medium, characterized in that: One or more programs are stored, and when the one or more programs are executed, a method for diagnosing dynamic phase loss of an AC motor as described in any one of claims 1 to 7 can be implemented.
10. A device, characterized in that: The system comprises a processor, a communication interface, a memory and a communication bus; the memory stores at least one program in a computer storage medium as claimed in claim 9 which can be loaded and executed by the processor.