Fault detection method and detection device

Abstract

The present invention relates to electrical equipment maintenance technology, and discloses a fault detection method and a detection device. Used to detect the fault of a load with a coaxial motor, the detection method includes: inputting a modulated current into the motor to drive the load to run at no load; collecting the drive current parameters during the operation of the motor; and when the drive current parameters are inconsistent with the preset drive current parameters, determining that the motor is demagnetized. By monitoring the stator current of the motor, the demagnetization fault can be detected. This fault detection method can quickly identify the fault of the motor, so that the location of the fault can be determined by the elimination method, which can reduce unnecessary disassembly; the method provided in the embodiment of the present application provides a fast and convenient fault detection technology with strong practicality.

Description

Technical Field

[0001] The invention relates to electrical equipment maintenance technology, and in particular to a fault detection method and a detection device that can be used for a load with a coaxial motor. Background Art

[0002] The prior art has a load with a coaxial motor, such as a water pump or the like, in which the motor part is coaxially installed with the load device and is generally installed in the same housing.

[0003] Especially for equipment like sewage pumps that operate in harsh environments for a long time, various faults may occur. When the water pump fails to start or suddenly stops during operation, it is generally impossible to determine whether it is the motor or the pump body that is faulty without disassembling the sewage pump. In addition, sewage pumps are placed in sewage and smelly water for a long time for water treatment. When the water pump is removed from the sewage due to a fault, the engineers are less willing to repair it due to severe pollution.

[0004] There is no rapid fault detection method for loads with coaxial motors (such as water pumps and other similar equipment) in the prior art, and rapid fault detection cannot be performed without disassembling the machine, which makes the fault detection operation of such equipment time-consuming and labor-intensive, and fails to improve the repair rate.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0006] In order to solve the above technical problem or at least partially solve the above technical problem, the present application provides a fault detection method and a detection device.

[0007] In a first aspect, the present application provides a fault detection method for detecting a fault of a load having a coaxial motor, comprising:

[0008] Inputting a modulated current into the motor to drive the load to run at no load;

[0009] collecting driving current parameters of the motor during operation; and

[0010] When the driving current parameter is inconsistent with the preset driving current parameter, it is determined that the motor is demagnetized.

[0011] According to an embodiment of the present invention, before driving the load to run at no load, the method further includes:

[0012] Locating an initial position of a rotor of the motor;

[0013] The phase of the modulation current is determined according to the initial position.

[0014] According to an embodiment of the present invention, the step of locating the initial position of the rotor of the motor includes:

[0015] Alternatingly energizing each phase of the motor;

[0016] Collecting the inductance parameters of the motor coil winding during the alternating power-on process;

[0017] The initial position of the rotor of the motor is determined by utilizing the enhancement or weakening of the inductance parameters at each corresponding position.

[0018] According to an embodiment of the present invention, the step of locating the initial position of the rotor of the motor includes:

[0019] energizing any two phases of the motor;

[0020] The rotor of the motor is magnetically attracted and rotated to a predetermined position corresponding to any two phases in the energized state; and

[0021] The positioning of the rotor of the motor is completed.

[0022] According to an embodiment of the present invention, before inputting the modulation current to the motor, the method includes:

[0023] According to the phase of the modulation current, a PWM current signal with a phase difference of 120° is generated as the modulation current.

[0024] According to an embodiment of the present invention, after collecting the driving current parameters of the motor during operation, the method further includes:

[0025] comparing the collected driving current parameters with the preset driving current parameters;

[0026] It is calculated whether the driving current parameter increases by a current percentage greater than the preset driving current parameter by more than 5%, and if so, it is determined that the motor is demagnetized.

[0027] According to an embodiment of the present invention, it is calculated whether the increase ratio of the driving current parameter is between 5% and 10% compared with the preset driving current parameter, and if so, it is determined that the motor is weakly demagnetized; or

[0028] It is calculated whether the increase ratio of the driving current parameter exceeds 10% compared with the preset driving current parameter. If yes, it is determined that the motor is strongly demagnetized.

[0029] According to an embodiment of the present invention, if it is determined according to the above method that the motor is normal, it is determined that the load has a fault.

[0030] In a second aspect, the present application provides a fault detection device for detecting a fault of a load having a coaxial motor, the fault detection device comprising a controller and a modulation current source; the current output end of the modulation current source is connected to the motor, and the modulation current source is used to supply a modulation current to the motor; the controller comprises an instruction module, a current acquisition module, a demagnetization judgment module and a load fault judgment module; the instruction module signal is connected to the signal input end of the modulation current source; the receiving end of the current acquisition module is connected to the motor, and is used to collect the driving current parameters of the motor; the receiving end of the demagnetization judgment module is connected to the output end of the current acquisition module, and is used to compare whether the obtained driving current parameters are consistent with the preset driving current parameters of the motor, and when the comparison result indicates that the driving current parameters are inconsistent with the preset driving current parameters, determine that the motor is demagnetized; the receiving end of the load fault judgment module is connected to the output end of the demagnetization judgment module, and is used to determine the fault of the load according to the demagnetization judgment of the motor by the demagnetization judgment module.

[0031] According to one embodiment of the present invention, the controller also has a motor starting module, the output end of the motor starting module is connected to the input end of the modulation current source, and the input end of the motor starting module is connected to the instruction module; the motor starting module controls the modulation current source to provide a current vector to the stator of the motor according to the starting instruction of the instruction module, thereby locating the initial position of the rotor of the motor.

[0032] According to an embodiment of the present invention, there is also a display for displaying the fault detection result, and the display signal is connected to the controller.

[0033] According to an embodiment of the present invention, the modulated current source is a three-phase PWM current source capable of modulating current and frequency.

[0034] According to an embodiment of the present invention, the controller further comprises a storage module for storing preset drive current parameters of the motor, and the storage module signal is connected to a receiving end of the demagnetization determination module.

[0035] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0036] The method provided in the embodiment of the present application is aimed at fault detection of a load with a coaxial motor. Since the modulation current is directly input for detection, the problem that the traditional PWM pulse width modulation signal may not be able to start normally due to excessive starting current can be avoided; at the same time, the drive current signal is directly collected. This is because after the motor rotor has a demagnetization fault, the magnetic properties of the permanent magnet are affected, and then the air gap flux is distorted, and finally the fault can be directly reflected in the stator current. Therefore, by monitoring the stator current of the motor, the demagnetization fault can be detected. The motor can be quickly identified for faults, so that the fault can be determined by the elimination method, which can reduce unnecessary disassembly; the method provided in the embodiment of the present application provides a quick and convenient solution with strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0038] 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0039] Figure 1 A schematic diagram of a fault detection method flow chart provided in an embodiment of the present application.

[0040] Figure 2 A schematic diagram of the principle of a rotor positioning method in a fault detection method provided in an embodiment of the present application.

[0041] Figure 3 A circuit diagram of a modulated current source in a fault detection device provided in an embodiment of the present application.

[0042] Figure 4 A schematic diagram of the structural composition of a fault detection device provided in an embodiment of the present application.

[0043] Figure 5 A schematic diagram of waveform comparison in a fault detection method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0045] Figure 1 A fault detection method provided in an embodiment of the present application is used to detect a fault of a load having a coaxial motor, and mainly comprises the steps of:

[0046] Step S1, start detection;

[0047] Step S2, inputting a modulated current to the motor to drive the load to run without load; passing a current set by a program to realize the open-loop operation of the motor; wherein during the driving process, the input current value can be gradually controlled according to whether the motor is running with or without load, so as to perform multiple tests in multiple current value intervals;

[0048] Step S3, collecting the driving current parameters of the motor during operation; comparing the given input current value with the previous no-load operation current of the water pump;

[0049] Step S4: when the driving current parameter is inconsistent with the preset driving current parameter, determining that the motor is demagnetized.

[0050] For the fault detection of the load with a coaxial motor, since the modulation current is directly input for detection, the problem that the traditional PWM pulse width modulation signal may not be able to start normally due to excessive starting current can be avoided; at the same time, the drive current signal is directly collected. This is because after the motor rotor has a demagnetization fault, the magnetic properties of the permanent magnet are affected, and then the air gap flux is distorted, and finally the fault can be directly reflected in the stator current. Therefore, by monitoring the stator current of the motor, the demagnetization fault can be detected. The cause of the fault can be quickly identified for the motor, and then the cause of the fault can be determined by elimination, which can reduce unnecessary disassembly; the method provided in the embodiment of the present application provides a quick and convenient solution with strong practicality.

[0051] According to an embodiment of the present invention, before driving the load to run at no-load, the method further includes the following steps:

[0052] Position the initial position of the motor's rotor; only by first determining the rotor's position when stationary can we decide which two switches should be triggered for the first time when starting. In this specification, the process of determining the rotor's initial position is called positioning. Thus, the phase of the modulation current can be determined according to the initial position.

[0053] According to an embodiment of the present invention, in the step of locating the initial position of the rotor of the motor, the simplest and most commonly used method is to energize any two phases and control the motor current not to be too large. After a period of energization, the rotor will rotate to the predicted position corresponding to the energized state, thus completing the positioning of the rotor. Figure 2 For example, if the two phases AB are energized, the stator magnetic potential F a The position is shown in the figure. At this time, if the rotor magnetic potential F f In the icon position, the rotor will rotate clockwise by 120° electrical angle and align with the direction of the stator magnetic field, thus completing the positioning of the rotor of the motor.

[0054] According to an embodiment of the present invention, in another implementation of locating the initial position of the rotor of the motor, the overall operation may be:

[0055] Alternatingly energizing each phase of the motor;

[0056] Collecting the inductance parameters of the motor coil winding during the alternating power-on process;

[0057] The initial position of the rotor of the motor is determined by utilizing the enhancement or weakening of the inductance parameters at each corresponding position.

[0058] The specific operation can be to first energize one phase of the motor winding and ground the other two phases. Then change the grounded two-phase winding to energize, and the original energized winding to ground, generating a magnetic field in the opposite direction. The power-on time in both cases is very short, the rotor does not rotate, and a current pulse is generated in the winding. By comparing the size of the current pulse in these two cases, the size of the two winding inductances can be compared, so that the rotor can be positioned within a range of 180°. Then change the motor winding of another phase and repeat the previous process to position the rotor within another 180° range. Each of the three-phase windings is tested once, and the overlap of the three ranges can determine the 60° range where the rotor is located.

[0059] According to an embodiment of the present invention, before inputting the modulation current to the motor, the method includes:

[0060] According to the phase of the modulation current, a PWM current signal with a phase difference of 120° is generated as the modulation current. Figure 3 The example shown is a schematic diagram of a current source circuit for PWM modulated current provided in an embodiment of the present invention.

[0061] Figure 5 A schematic diagram of waveform comparison in a fault detection method provided in an embodiment of the present application. As shown in the figure, according to an embodiment of the present invention, after collecting the drive current parameters of the motor during operation, it also includes:

[0062] Compare the collected drive current parameters with the preset drive current parameters, and specifically use the collected values ​​to perform direct difference calculation. Figure 5 By comparing the waveform area ratio of the induced potential, the percentage of reduction in the peak waveform can be approximated as the demagnetization rate.

[0063] It is calculated whether the driving current parameter increases by a current percentage greater than the preset driving current parameter by more than 5%, and if so, it is determined that the motor is demagnetized.

[0064] According to an embodiment of the present invention, it is calculated whether the increase ratio of the driving current parameter is between 5% and 10% compared with the preset driving current parameter, and if so, it is determined that the motor is weakly demagnetized; or

[0065] It is calculated whether the increase ratio of the driving current parameter exceeds 10% compared with the preset driving current parameter. If yes, it is determined that the motor is strongly demagnetized.

[0066] According to an embodiment of the present invention, if it is determined according to the above method that the motor is normal, it is determined that the load has a fault.

[0067] like Figure 4 As shown, the embodiment of the present invention can also be considered to provide a fault detection device for detecting a fault of a load having a coaxial motor. The fault detection device mainly includes a controller 1 and a modulation current source 2.

[0068] The current output end of the modulation current source 2 is connected to the motor 3, and the modulation current source 2 is used to supply modulation current to the motor 3;

[0069] The controller 1 mainly includes an instruction module 11, a current acquisition module 12, a demagnetization judgment module 13 and a load fault judgment module 14; the instruction module 11 is signal-connected to the signal input end of the modulation current source 2; the receiving end of the current acquisition module 12 is connected to the motor 3, and is used to collect the driving current parameters of the motor 3; the receiving end of the demagnetization judgment module 13 is connected to the output end of the current acquisition module 12, and is used to compare whether the obtained driving current parameters are consistent with the preset driving current parameters of the motor 3, and when the comparison result indicates that the driving current parameters are inconsistent with the preset driving current parameters, it is determined that the motor 3 is demagnetized; the receiving end of the load fault judgment module 14 is connected to the output end of the demagnetization judgment module 13, and is used to determine the fault of the load according to the demagnetization judgment of the motor 3 by the demagnetization judgment module 13.

[0070] The current acquisition module 12 can be a sampling circuit, which can be connected to the drive circuit (which can be the modulation current source 2 side or directly connected to the access side of the motor 3) through a sampling resistor. The instruction module 11 can be a physical button or a touch instruction input device. The demagnetization judgment module 13 and the load fault judgment module 14 can be a comparator or a PLC intelligent controller.

[0071] The controller 1 also has a motor starting module 15, the output end of the motor starting module 15 is connected to the input end of the modulation current source 2, and the input end of the motor starting module 15 is connected to the instruction module; the motor starting module 15 controls the modulation current source 2 to provide a current vector to the stator of the motor according to the starting instruction of the instruction module, thereby locating the initial position of the rotor of the motor 3. The motor starting module 15 can be selected as a dedicated starting circuit.

[0072] A display 4 for displaying the fault detection result is also provided, and the display 4 is connected to the controller 1 via a signal.

[0073] The modulation current source 2 is a three-phase PWM current source capable of modulating current and frequency. The specific circuit diagram is as follows: Figure 3 shown.

[0074] The controller 1 further comprises a storage module 5 for storing preset drive current parameters of the motor, and the storage module 5 is signal-connected to a receiving end of the demagnetization determination module.

[0075] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0076] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A fault detection method for detecting a fault of a load having a coaxial motor, characterized in that: include: Inputting a modulated current into the motor to drive the load to run at no load; Collecting driving current parameters of the motor during operation; as well as When the driving current parameter is inconsistent with a preset driving current parameter, determining that the motor is demagnetized, the preset driving current parameter being the current of the load running at no load in a historical time period; Before driving the load to run without load, the method further includes: locating the initial position of the rotor of the motor; determining the phase of the modulation current according to the initial position; The step of locating the initial position of the rotor of the motor includes: energizing any two phases of the motor; the rotor of the motor is magnetically attracted and rotated to a predicted position corresponding to any two phases in the energized state; and completing the positioning of the rotor of the motor.

2. The fault detection method according to claim 1, characterized in that: The step of locating the initial position of the rotor of the motor comprises: Alternatingly energizing each phase of the motor; Collecting the inductance parameters of the motor coil winding during the alternating power-on process; The initial position of the rotor of the motor is determined by utilizing the enhancement or weakening of the inductance parameters at each corresponding position.

3. The fault detection method according to claim 1, characterized in that: Before inputting the modulation current to the motor, the method includes: According to the phase of the modulation current, a PWM current signal with a phase difference of 120° is generated as the modulation current.

4. The fault detection method according to any one of claims 1 to 3, characterized in that: After collecting the driving current parameters of the motor during operation, the method further includes: comparing the collected driving current parameters with the preset driving current parameters; It is calculated whether the driving current parameter increases by a current percentage greater than the preset driving current parameter by more than 5%, and if so, it is determined that the motor is demagnetized.

5. The fault detection method according to claim 4, characterized in that: Calculate whether the increase ratio of the driving current parameter is between 5% and 10% compared with the preset driving current parameter, and if so, determine that the motor is weakly demagnetized; or It is calculated whether the increase ratio of the driving current parameter exceeds 10% compared with the preset driving current parameter. If yes, it is determined that the motor is strongly demagnetized.

6. The fault detection method according to claim 4, characterized in that: If the motor is judged to be normal according to the above method, it is judged that the load has a fault.

7. A fault detection device for detecting a fault of a load having a coaxial motor, characterized in that: The fault detection device comprises a controller (1) and a modulation current source (2); The current output end of the modulation current source (2) is connected to the motor (3), and the modulation current source (2) is used to supply modulation current to the motor (3); The controller (1) is used to locate the initial position of the rotor of the motor (3); The phase of the modulation current is determined according to the initial position; the step of locating the initial position of the rotor of the motor (3) comprises: controlling the modulation current source (2) to energize any two phases of the motor (3); the rotor of the motor (3) is magnetically attracted and rotated to a predetermined position corresponding to any two phases in the energized state; and completing the positioning of the rotor of the motor; The controller (1) comprises an instruction module (11), a current acquisition module (12), a demagnetization judgment module (13) and a load fault judgment module (14); the instruction module (11) is signal-connected to the signal input end of the modulation current source (2); the receiving end of the current acquisition module (12) is connected to the motor (3) for collecting the drive current parameter of the motor (3); the receiving end of the demagnetization judgment module (13) is connected to the output end of the current acquisition module (12) for comparing whether the obtained drive current parameter is consistent with the preset drive current parameter of the motor (3), and determining that the motor (3) is demagnetized when the comparison result indicates that the drive current parameter is inconsistent with the preset drive current parameter; the receiving end of the load fault judgment module (14) is connected to the output end of the demagnetization judgment module (13) for determining the fault of the load according to the demagnetization judgment of the motor (3) by the demagnetization judgment module (13), and the preset drive current parameter is the current of the load running at no load in a historical time period.

8. The fault detection device according to claim 7, characterized in that: The controller (1) further comprises a motor starting module (15), the output end of the motor starting module (15) being connected to the input end of the modulation current source (2), and the input end of the motor starting module (15) being connected to the instruction module; the motor starting module (15) controls the modulation current source (2) to provide a current vector to the stator of the motor according to the starting instruction of the instruction module, thereby locating the initial position of the rotor of the motor (3).

9. The fault detection device according to claim 7 or 8, characterized in that: It also has a display (4) for displaying the fault detection result, and the display (4) is connected to the controller (1) via a signal.

10. The fault detection device according to claim 7 or 8, characterized in that: The modulation current source (2) is a three-phase PWM current source capable of modulating current and frequency.

11. The fault detection device according to claim 7 or 8, characterized in that: The controller (1) also has a storage module (5) for storing preset drive current parameters of the motor, and the storage module (5) is signal-connected to the receiving end of the demagnetization judgment module.

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