A method and system for detecting failure of electrolytic capacitors inside a frequency converter

Abstract

The application provides a method and system for detecting failure of electrolytic capacitor inside a frequency converter, characterized in that: in step S1, a voltage collecting device is used to continuously measure voltage value after the frequency converter is powered off; in step S2, a processing module is used to process the voltage value to obtain actual discharge time after the frequency converter is powered off; in step S3, the actual discharge time is compared with standard discharge time recorded inside the frequency converter; if the actual discharge time is less than the standard discharge time, alarm information indicating failure of the electrolytic capacitor is outputted, and then the process is exited; if the actual discharge time is not less than the standard discharge time, the process is directly exited. Advantageous effects: by using the method and system, whether failure of the electrolytic capacitor occurs can be found immediately after the frequency converter is powered off, so that the user can be timely informed to replace the equipment, production plan can be changed, and equipment damage and other losses can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit safety, in particular to a method and system for detecting failure of electrolytic capacitor inside a frequency converter. BACKGROUND

[0002] The electrolytic capacitor is one of the core components in the main circuit of the current frequency converter, mainly playing the role of rectifier filtering and smoothing DC voltage. Its service life is relatively low among all core components. At the same time, due to the influence of uncertain factors such as environmental temperature and working conditions, its service life will also fluctuate greatly. If it fails unexpectedly, the frequency converter will not work, and it may also cause damage to the equipment, thereby causing loss to the user. The main reason for the failure of the electrolytic capacitor is long-term use, internal heating of the electrolytic capacitor, which causes the electrolyte to dry out and thus fail. During use, the service life of the electrolytic capacitor is greatly affected by parameters such as actual capacitance size, working voltage, current and environmental temperature, which is a complex parameter affected by multiple variables. SUMMARY

[0003] Currently, the detection of the service life of the electrolytic capacitor of the frequency converter mainly focuses on how to more accurately calculate the service life. However, during the operation of the frequency converter, real-time detection of parameters such as voltage, current and environmental temperature requires more sensors, and the current flowing through the electrolytic capacitor is a pulsating current with many harmonics, which is not conducive to service life calculation, and the hardware cost is high. It is not conducive to the realization of online service life detection of the frequency converter.

[0004] The purpose of the present application is to provide a method for detecting failure of electrolytic capacitor inside a frequency converter, a processing module is preset, a voltage acquisition device is arranged in the processing module, and the voltage acquisition device is connected to the electrolytic capacitor through the DC bus of the frequency converter;

[0005] In the method,

[0006] Firstly, a standard discharge test is performed on the frequency converter, and a corresponding standard discharge time is recorded in the frequency converter;

[0007] Subsequently, during the normal operation of the frequency converter, the following steps are performed for each time the main circuit of the frequency converter is powered off:

[0008] Step S1, continuously measuring the voltage value after the frequency converter is powered off by using the voltage acquisition device;

[0009] Step S2, processing the actual discharge time after the frequency converter is powered off according to the voltage value by using the processing module;

[0010] Step S3, comparing the actual discharge time with the standard discharge time recorded in the frequency converter.

[0011] If the actual discharge time is less than the standard discharge time, outputting alarm information for indicating that the electrolytic capacitor is invalid, and then exiting;

[0012] If the actual discharge time is not less than the standard discharge time, directly exiting.

[0013] Preferably, the frequency converter performs the standard discharge test after the factory manufacturing is completed, and records the standard discharge time in the frequency converter.

[0014] Preferably, the voltage acquisition device is provided with a first end connected to the positive pole of the DC bus and a second end connected to the negative pole of the DC bus.

[0015] A plurality of resistors with the same volume are connected in series between the first end and the second end.

[0016] In the step S1, the voltage value of the frequency converter after power-off is obtained by continuously measuring the voltage value of one of the resistors.

[0017] Preferably, the processing module is further provided with a processing unit connected to the voltage acquisition device.

[0018] The step S2 specifically includes:

[0019] Step S21, using the processing unit to obtain the voltage value continuously acquired by the voltage acquisition device;

[0020] Step S22, using the processing unit to process the actual discharge time according to the change of the voltage value with time.

[0021] Preferably, the processing module is further provided with a human-computer interaction interface connected to the processing unit.

[0022] In the step S3, the processing module displays the alarm information in the human-computer interaction interface.

[0023] The technical solution also provides a system for detecting the invalidation of an electrolytic capacitor in a frequency converter, comprising:

[0024] A voltage acquisition device connected to the DC bus of the frequency converter for acquiring the voltage value of the frequency converter;

[0025] A data processing unit connected to the voltage acquisition device for processing the discharge time of the frequency converter according to the voltage value continuously acquired by the voltage acquisition device after the frequency converter is powered off.

[0026] a recording unit connected to the data processing unit, configured to record the discharge time processed by the data processing unit as a standard discharge time when a standard discharge test is performed on the frequency converter;

[0027] a comparison unit connected to the data processing unit and the recording unit respectively, configured to obtain the discharge time processed by the data processing unit as an actual discharge time when the frequency converter is powered off each time, compare the actual discharge time with the standard discharge time and output a comparison result;

[0028] an alarm unit connected to the comparison unit, configured to output an alarm information indicating that the electrolytic capacitor is invalid when the comparison result indicates that the actual discharge time is less than the standard discharge time.

[0029] Preferably, the standard discharge test is performed on the frequency converter after the factory manufacturing is completed to record the standard discharge time in the recording unit.

[0030] Preferably, the voltage collecting device is provided with:

[0031] a first end configured to be connected to a positive pole of the DC bus;

[0032] a second end configured to be connected to a negative pole of the DC bus;

[0033] a plurality of resistors with the same volume connected in series between the first end and the second end;

[0034] a measurement unit connected to two ends of one of the resistors and configured to obtain the voltage value of the frequency converter after being powered off by continuously measuring the voltage value of one of the resistors.

[0035] Preferably, the data processing unit specifically comprises:

[0036] a receiving component configured to obtain the voltage value continuously collected by the voltage collecting device after the frequency converter is powered off;

[0037] a processing component connected to the receiving component and configured to process the actual discharge time according to the change of the voltage value with time and output the actual discharge time.

[0038] Preferably, the application further comprises:

[0039] a human-computer interaction unit connected to the alarm unit, configured to provide a human-computer interaction interface in the human-computer interaction unit to display the alarm information output by the alarm unit.

[0040] Beneficial effects: using the method and system of the application, after the power failure of the frequency converter, it can be found whether there is a failure of the electrolytic capacitor, so as to timely inform the user to replace the equipment, change the production plan, and reduce the damage of the equipment and other losses. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 For the preferred embodiment of the application, the overall flowchart is shown;

[0042] Figure 2 For the preferred embodiment of the application, the processing module workflow diagram is shown;

[0043] Figure 3 In the preferred embodiment of the application, the system structure diagram is shown. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0045] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0046] The application will be further described below with reference to the drawings and specific embodiments, but not as a limitation of the application.

[0047] The application provides a method for detecting the failure of electrolytic capacitor in a frequency converter, characterized in that a processing module is preset, a voltage acquisition device is arranged in the processing module, and the voltage acquisition device is connected with the electrolytic capacitor through the DC bus of the frequency converter.

[0048] In the method,

[0049] Firstly, a standard discharge test is performed on the frequency converter, and a corresponding standard discharge time is recorded in the frequency converter;

[0050] Subsequently, in the process of normal operation of the frequency converter, the following steps are performed for each power failure of the main circuit of the frequency converter:

[0051] Step S1, the voltage acquisition device is used to continuously measure the voltage value after the power failure of the frequency converter;

[0052] Step S2, the processing module is used to process the actual discharge time of the frequency converter after the power failure according to the voltage value;

[0053] Step S3, compare the actual discharge time with the standard discharge time recorded in the frequency converter;

[0054] If the actual discharge time is less than the standard discharge time, output an alarm information indicating that the electrolytic capacitor is invalid, and then exit;

[0055] If the actual discharge time is not less than the standard discharge time, directly exit.

[0056] Specifically, in the embodiment, the voltage parameter in the frequency converter is the voltage parameter of the capacitor to be tested, and the voltage of the capacitor to be tested after power-off is the bus voltage of the main circuit of the frequency converter. The standard discharge time is the time taken for the voltage to drop from a stable voltage to 0 when the frequency converter is in a complete and normal state. When the capacitor is in use and discharging, the time taken for the voltage to drop from a stable voltage to 0 becomes the actual discharge time.

[0057] In a preferred embodiment of the present application, the frequency converter performs a standard discharge test after factory manufacturing to record the standard discharge time in the frequency converter.

[0058] Specifically, in the embodiment, the frequency converter performs a discharge test to confirm a standard discharge time when it is shipped. Since the frequency converter is subjected to quality inspection when it is shipped, the standard discharge time is the discharge time of the frequency converter when the quality is normal, which facilitates subsequent detection of the quality of the corresponding capacitor of the frequency converter.

[0059] In a preferred embodiment of the present application, the voltage collecting device is provided with a first end connected to the positive pole of the DC bus and a second end connected to the negative pole of the DC bus.

[0060] A plurality of resistors with the same volume are connected in series between the first end and the second end.

[0061] In step S1, the voltage value of the frequency converter after power-off is obtained by continuously measuring the voltage value of one of the resistors.

[0062] Specifically, in the embodiment, the plurality of resistors with the same resistance value evenly distribute the voltage, and the voltage of a single voltage dividing resistor can be collected through an AD collection port, which can protect the AD collection port from being damaged by high voltage. Since the voltage across each voltage dividing resistor is uniform, the current capacitor voltage can be obtained by collecting a single voltage dividing resistor and converting it through a corresponding formula. In addition, the operator can flexibly set the number of voltage dividing resistors according to the voltage environment of the frequency converter, which has good adaptability.

[0063] In a preferred embodiment of the present application, the processing module is further provided with a processing unit connected to the voltage collecting device.

[0064] The step S2 specifically comprises:

[0065] In step S21, the voltage value continuously collected by the voltage collection device is acquired by the processing unit;

[0066] In step S22, the actual discharge time is obtained by the processing unit according to the change of the voltage value with time.

[0067] Specifically, in the embodiment, the voltage value collected by the voltage collection device is acquired by the processing unit, and the actual discharge time is obtained by the processing unit according to the change of the voltage value with time. Since the voltage collection data can only collect the value of the voltage, which is converted by the AD for processing by the processor, the discharge time cannot be directly measured. However, the clock in the processor can determine the discharge time according to the time when the voltage is zero, and the comparison between the standard discharge time and the currently collected discharge time also needs to be performed in the processing unit.

[0068] In the preferred embodiment of the application, a human-computer interaction interface connected to the processing unit is further arranged in the processing module.

[0069] In step S3, the processing module displays the alarm information in the human-computer interaction interface.

[0070] Specifically, in the embodiment, the human-computer interaction module includes but is not limited to light, sound, mobile phone, computer, television and other media and devices that can be used by the user to understand the current state of the electrolytic capacitor in the frequency converter.

[0071] The application further provides a system for detecting the failure of the electrolytic capacitor in the frequency converter, comprising:

[0072] The voltage collection device 1 is connected to the electrolytic capacitor through the DC bus of the frequency converter, and is used to collect the voltage value of the frequency converter;

[0073] The data processing unit 2 is connected to the voltage collection device 1, and is used to obtain the discharge time of the frequency converter according to the voltage value continuously collected by the voltage collection device 1 after the frequency converter is powered off;

[0074] The recording unit 3 is connected to the data processing unit 2, and is used to record the discharge time obtained by the data processing unit 2 as a standard discharge time when a standard discharge test is performed on the frequency converter;

[0075] The comparison unit 4 is connected to the data processing unit 2 and the recording unit 3, respectively, and is used to obtain the discharge time obtained by the data processing unit 2 as an actual discharge time when the frequency converter is powered off each time, compare the actual discharge time with the standard discharge time, and output a comparison result;

[0076] The alarm unit 5 is connected to the comparison unit 4, and is used for outputting an alarm information for indicating the failure of the electrolytic capacitor when the comparison result indicates that the actual discharge time is less than the standard discharge time.

[0077] Specifically, in the embodiment, the voltage collecting device 1 collects the voltage of the electrolytic capacitor to be tested, and converts the collected data into analog signals through an AD conversion port, so as to input the data into the data processing unit 2, so that the data processing unit 2 can directly process the collected data, and the data processing unit 2 directly measures the discharge time of the frequency converter after the frequency converter is powered off, and records the discharge time through a recording unit 3.

[0078] In the preferred embodiment of the present application, the frequency converter is subjected to a standard discharge test after being manufactured in the factory, so as to record the standard discharge time in the recording unit 3.

[0079] Specifically, in the embodiment, the recording unit 3 is subjected to a standard discharge test when being manufactured, and records the obtained standard discharge time in the recording unit 3, so as to compare the standard discharge time with the discharge time of the frequency converter after the frequency converter is powered off. The measured standard discharge time needs to be measured multiple times and averaged, so as to ensure that the frequency converter is in a normal state, and to ensure that the measurement of the discharge time has better accuracy.

[0080] In the preferred embodiment of the present application, the voltage collecting device 1 is provided with:

[0081] A first end L1, used for connecting a positive pole of a DC bus;

[0082] A second end L2, used for connecting a negative pole of the DC bus;

[0083] A plurality of resistors with the same volume, which are connected in series between the first end L1 and the second end L2;

[0084] A measurement unit 11, which is connected to two ends of one of the resistors, and obtains the voltage value of the frequency converter after being powered off by continuously measuring the voltage value of the one resistor.

[0085] Specifically, in the embodiment, the signal collected by the measurement unit is an analog signal, which can be directly displayed to an operator through an analog instrument. When the voltage collecting device 1 or the data processing unit 2 fails, the working personnel can obtain the working state of the electrolytic capacitor through manual calculation.

[0086] In the preferred embodiment of the present application, the data processing unit 2 specifically includes:

[0087] A receiving component 21, used for obtaining the voltage value continuously collected by the voltage collecting device 1 after the frequency converter is powered off;

[0088] The processing component 22 is connected to the receiving component 21 and is configured to process the actual discharge time according to the change of the voltage value over time and output the actual discharge time.

[0089] In particular, in the embodiment, the preferred embodiment of the application further comprises:

[0090] The man-machine interaction unit 6 is connected to the alarm unit 5, and a man-machine interaction interface is provided in the man-machine interaction unit 6 to display the alarm information output by the alarm unit 5.

[0091] In the embodiment, if the frequency converter is in a normal state, the man-machine interaction unit 6 displays that the current electrolytic capacitor is normal, if the frequency converter is damaged, the man-machine interaction unit 6 is in an alarm state to alarm the user, and the man-machine interaction unit 6 can also trigger the control relay to be disconnected by an alarm instruction to prevent the frequency converter from continuing to work, thereby achieving the protection of the frequency converter system.

[0092] The above only describes the preferred embodiments of the application, and does not limit the implementation and protection scope of the application. It should be realized by those skilled in the art that any equivalent replacement and obvious change made according to the content of the specification and drawings should be included in the protection scope of the application.

Claims

1. A method of detecting failure of an electrolytic capacitor inside a frequency converter, characterized by, A preset processing module is provided with a voltage acquisition device connected to the electrolytic capacitor through the DC bus of the frequency converter; In the method: First, a standard discharge test is performed on the frequency converter, and a corresponding standard discharge time is recorded in the frequency converter; Subsequently, during normal operation of the frequency converter, the following steps are performed for each time the main circuit of the frequency converter is powered off: Step S1, the voltage acquisition device is used to continuously measure the voltage value after the frequency converter is powered off; Step S2, the processing module is used to process the voltage value to obtain the actual discharge time after the frequency converter is powered off; Step S3, compare the actual discharge time with the standard discharge time recorded in the frequency converter: If the actual discharge time is less than the standard discharge time, output an alarm information indicating that the electrolytic capacitor is invalid, and then exit; If the actual discharge time is not less than the standard discharge time, directly exit; In the voltage acquisition device, a first end connected to the positive pole of the DC bus and a second end connected to the negative pole of the DC bus are provided; A plurality of resistors with the same volume are connected in series between the first end and the second end; In step S1, the voltage value of one of the resistors is continuously measured and converted to obtain the voltage value after the frequency converter is powered off; The number of resistors in series is set according to the voltage environment of the frequency converter.

2. The method of claim 1, wherein, After the frequency converter is manufactured in the factory, the standard discharge test is performed to record the standard discharge time in the frequency converter.

3. The method of claim 1, wherein, A processing unit connected to the voltage acquisition device is further provided in the processing module; Step S2 specifically includes: Step S21, the processing unit is used to obtain the voltage value continuously acquired by the voltage acquisition device; Step S22, the processing unit is used to process the actual discharge time according to the change of the voltage value with time.

4. The method of claim 3, wherein, A human-computer interaction interface connected to the processing unit is further provided in the processing module; In step S3, the processing module displays the alarm information in the human-computer interaction interface.

5. A system for detecting failure of an electrolytic capacitor inside a frequency converter for implementing the method of any one of claims 1-4, characterized by Including: A voltage acquisition device connected to the electrolytic capacitor through the DC bus of the frequency converter is used to continuously measure the voltage value after the frequency converter is powered off; A data processing unit connected to the voltage acquisition device is used to process the discharge time of the frequency converter according to the voltage value continuously acquired by the voltage acquisition device after the frequency converter is powered off; A recording unit connected to the data processing unit is used to record the discharge time processed by the data processing unit as a standard discharge time when a standard discharge test is performed on the frequency converter. A comparison unit is connected to the data processing unit and the recording unit respectively, and is configured to obtain the actual discharge time from the data processing unit when the frequency converter is powered off each time, compare the actual discharge time with the standard discharge time, and output a comparison result; An alarm unit is connected to the comparison unit, and is configured to output an alarm information indicating that the electrolytic capacitor is invalid when the comparison result indicates that the actual discharge time is less than the standard discharge time.

6. The system of claim 5, wherein, The standard discharge test is performed on the frequency converter after the factory manufacturing, and the standard discharge time is recorded in the recording unit.

7. The system of claim 5, wherein the voltage collection device comprises: a first end configured to be connected to a positive pole of the DC bus; a second end configured to be connected to a negative pole of the DC bus; a plurality of resistors with the same volume connected in series between the first end and the second end; a measurement unit connected to two ends of one of the resistors and configured to obtain the voltage value of the frequency converter after being powered off by continuously measuring the voltage value of one of the resistors. The data processing unit specifically comprises:

8. The system of claim 5, wherein, a receiving component configured to obtain the voltage value obtained by the voltage collection device after the frequency converter is powered off; a processing component connected to the receiving component and configured to obtain the actual discharge time according to the change of the voltage value over time and output the actual discharge time. Further comprising:

9. The system of claim 5, wherein, a human-computer interaction unit connected to the alarm unit, and configured to provide a human-computer interaction interface in the human-computer interaction unit, and display the alarm information output by the alarm unit. ​

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