Method for detecting failure of electrolytic capacitor, failure detection circuit and embedded system

Abstract

The application discloses a kind of electrolytic capacitor fault detection method, fault detection circuit and embedded system, digital electric signal is carried out high-pass filtering, and spectrum analysis is carried out to high-pass filtering signal, can determine the amplitude of high-pass filtering signal at different frequency points, then determine target maximum amplitude in preset frequency range, and target maximum amplitude is compared with the preset threshold value corresponding to preset frequency range, if target maximum amplitude is greater than preset threshold value, it indicates that there is at least one amplitude exceeding preset threshold value high frequency point, i.e. high-pass filtering signal contains high-frequency noise, corresponding electrolytic capacitor appears aging and other capacitance value substantial attenuation fault, by the above-mentioned fault detection method, the fault of electrolytic capacitor can be analyzed without increasing circuit hardware cost, so that electrolytic capacitor can be replaced in advance to avoid system failure at uncertain time before electrolytic capacitor life is completely exhausted.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a fault detection method, fault detection circuit and embedded system for electrolytic capacitors. Background Technology

[0002] The system power supply of an embedded system typically involves converting AC power into DC power through rectification and filtering. This DC power then powers the internal MCU chip or other IC modules via a DC-DC power converter module. The internal DC power supply is further filtered by capacitors before supplying power to the MCU chip or other IC modules. To achieve better filtering / decoupling and for cost considerations, electrolytic capacitors are generally used in the power supply voltage conversion circuit.

[0003] The capacitance of an electrolytic capacitor is affected by the ambient temperature. In related technologies, embedded systems typically use thermistors / thermocouples to monitor the temperature of the embedded system. However, this temperature value can only reflect the temperature around the thermistor / thermocouple and cannot accurately determine the capacitance of the electrolytic capacitor. This can lead to over-protection or under-protection, which in turn affects the normal operation of the embedded system. Summary of the Invention

[0004] This application provides a fault detection method, fault detection circuit, and embedded system for electrolytic capacitors, which can accurately determine the capacitance value of electrolytic capacitors and thus provide early warning of electrolytic capacitor faults.

[0005] In a first aspect, embodiments of this application provide a fault detection method for an electrolytic capacitor, applied to a fault detection circuit. The fault detection circuit includes a DC power supply circuit and a controller. The DC power supply circuit includes a voltage conversion module for converting an input voltage into the operating voltage of the controller. The electrolytic capacitor is coupled between the positive DC voltage terminal and the negative DC voltage terminal of the voltage conversion module. The controller includes an ADC module for acquiring analog electrical signals from a temperature sensing element in the fault detection circuit. The fault detection method includes:

[0006] The digital electrical signal obtained by the ADC module converting the analog electrical signal is acquired, and the digital electrical signal is subjected to high-pass filtering to obtain a high-pass filtered signal.

[0007] Spectral analysis is performed on the high-pass filtered signal to determine the target maximum amplitude value of the high-pass filtered signal within a preset frequency range, and the target maximum amplitude value is compared with a preset threshold value corresponding to the preset frequency range; the preset frequency range characterizes the frequency range of high-frequency noise generated on the operating voltage due to the failure of the electrolytic capacitor.

[0008] If the maximum target value is greater than the preset threshold, the electrolytic capacitor is determined to be faulty.

[0009] In some embodiments, the preset frequency range and the preset threshold are obtained in the following manner:

[0010] Replace the electrolytic capacitor with the faulty capacitor;

[0011] The digital electrical signal under fault conditions obtained by the ADC module converting the analog electrical signal is acquired, and the digital electrical signal under fault conditions is subjected to high-pass filtering to obtain a high-pass filtered signal under fault conditions.

[0012] Perform spectral analysis on the high-pass filtered signal under the fault condition to determine the first frequency point corresponding to the largest amplitude value in the high-pass filtered signal under the fault condition.

[0013] The preset frequency range is obtained by expanding the first frequency point, and the preset threshold is determined based on the maximum amplitude value of the high-pass filtered signal under the fault state, wherein the preset threshold is less than the maximum amplitude value of the high-pass filtered signal under the fault state.

[0014] In some embodiments, the step of expanding the preset frequency range based on the frequency point includes:

[0015] Determine the second frequency point corresponding to the second amplitude value in the high-pass filtered signal under the fault condition;

[0016] The preset frequency range is obtained by expanding the frequency range between the first frequency point and the second frequency point.

[0017] In some embodiments, the electrolytic capacitor includes a first capacitor and a second capacitor, wherein the first capacitor is coupled between the DC positive voltage terminal and the DC negative voltage terminal on the input side of the voltage conversion module, and the second capacitor is coupled between the DC positive voltage terminal and the DC negative voltage terminal on the output side of the voltage conversion module.

[0018] The preset frequency range and the preset threshold are obtained in the following way:

[0019] The first electrolytic capacitor is replaced with the first fault capacitor to determine the first preset frequency range and the first preset threshold that characterize the first electrolytic capacitor as being in a fault state.

[0020] The second electrolytic capacitor is replaced with the second fault capacitor to determine a second preset frequency range and a second preset threshold that characterize the second electrolytic capacitor as being in a faulty state.

[0021] The first electrolytic capacitor is replaced with a first fault capacitor and the second electrolytic capacitor is replaced with a second fault capacitor to determine a third preset frequency range and a third preset threshold that characterize the first electrolytic capacitor and the second electrolytic capacitor being in a fault state at the same time.

[0022] In some embodiments, comparing the target maximum amplitude value with a preset threshold corresponding to the preset frequency range includes at least one of the following:

[0023] Determine the first target maximum amplitude value of the high-pass filtered signal within the first preset frequency range, and compare the first target maximum amplitude value with the first preset threshold value; if the first maximum amplitude value is greater than the first preset threshold value, determine that the first electrolytic capacitor has failed;

[0024] Determine the second target maximum amplitude value of the high-pass filtered signal within the second preset frequency range, and compare the second target maximum amplitude value with the second preset threshold value; if the second maximum amplitude value is greater than the second preset threshold value, determine that the second electrolytic capacitor has failed;

[0025] Determine the third target maximum amplitude value of the high-pass filtered signal within the third preset frequency range, and compare the third target maximum amplitude value with the third preset threshold value; if the third maximum amplitude value is greater than the third preset threshold value, determine that the first electrolytic capacitor and the second electrolytic capacitor have both failed.

[0026] In some embodiments, the controller includes a Vdd pin, a Vss pin, a Vdda pin, a Vssa pin, and an ADC pin; the Vdd pin is connected to the positive DC voltage terminal of the output side of the voltage conversion module, and the Vss pin is connected to the negative DC voltage terminal of the output side of the voltage conversion module; the Vdda pin is coupled to the Vdd pin, and the Vssa pin is coupled to the Vss pin; the ADC module is powered by the voltage between the Vdda pin and the Vssa pin, and is coupled to the temperature sensing element in the fault detection circuit through the ADC pin.

[0027] In some embodiments, after obtaining the digital electrical signal, the method further includes:

[0028] The digital electrical signal is subjected to low-pass filtering to obtain a low-pass filtered signal;

[0029] The temperature value at the temperature sensing element is determined based on the low-pass filtered signal and the preset temperature-signal correspondence.

[0030] In some embodiments, the cutoff frequency of the low-pass filter is less than 100Hz, and the cutoff frequency of the high-pass filter is greater than 100Hz.

[0031] Secondly, embodiments of this application provide a fault detection circuit, including at least one controller and a memory for communicatively connecting to the at least one controller; the memory stores instructions executable by the at least one controller, which, when executed by the at least one controller, enable the at least one controller to perform the method as described in the first aspect.

[0032] Thirdly, embodiments of this application provide an embedded system including the fault detection circuit described in the second aspect.

[0033] The fault detection method, fault detection circuit, and embedded system for electrolytic capacitors in this application have at least the following beneficial effects: When the electrolytic capacitor in the DC power supply circuit is connected to the controller and provides the operating voltage, if the electrolytic capacitor experiences a significant decrease in capacitance due to aging, high-frequency noise will be generated on the provided operating voltage. This high-frequency noise will be conducted to the reference voltage of the controller's ADC module, thus superimposing a certain frequency of high-frequency noise onto the digital signal converted by the ADC module. The fault detection method in this application performs high-pass filtering on the digital signal and performs spectral analysis on the high-pass filtered signal, which can determine whether the high-pass filtered signal is in a state of flux. The amplitude at the same frequency point is calculated, and then the target maximum amplitude value is determined within a preset frequency range. The target maximum amplitude value is compared with a preset threshold corresponding to the preset frequency range. If the target maximum amplitude value is greater than the preset threshold, it indicates that there is at least one high-frequency point with an amplitude exceeding the preset threshold, that is, the high-pass filter signal contains high-frequency noise. The corresponding electrolytic capacitor has a fault such as aging and a significant decrease in capacitance value. Through the above fault detection method, the fault of the electrolytic capacitor can be analyzed without increasing the circuit hardware cost. Thus, the user can be reminded before the electrolytic capacitor's lifespan is completely exhausted so that the electrolytic capacitor can be replaced in advance, avoiding system failure at an uncertain time.

[0034] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description and the accompanying drawings. Attached Figure Description

[0035] Figure 1 A circuit block diagram of a fault detection circuit provided in one embodiment of this application;

[0036] Figure 2 A circuit diagram of an AC input fault detection circuit provided in one embodiment of this application;

[0037] Figure 3A circuit diagram of a DC input fault detection circuit provided in one embodiment of this application;

[0038] Figure 4 This is an overall flowchart of a fault detection method provided in one embodiment of this application;

[0039] Figure 5 A flowchart for determining the temperature value after low-pass filtering is provided as an embodiment of this application;

[0040] Figure 6 A flowchart for determining a preset frequency range and a preset threshold is provided as an embodiment of this application;

[0041] Figure 7 A flowchart illustrating how a preset frequency range is obtained based on frequency point expansion is provided as an embodiment of this application;

[0042] Figure 8 The spectrum diagram provided as an example in this application after replacing the first electrolytic capacitor C1 with the faulty capacitor;

[0043] Figure 9 The spectrum diagram provided as an example in this application after replacing the second electrolytic capacitor C2 with the faulty capacitor;

[0044] Figure 10 The spectrum diagram provided as an example of this application after simultaneously replacing the first electrolytic capacitor C1 and the second electrolytic capacitor C2 with faulty capacitors;

[0045] Figure 11 This is a schematic diagram of the connection structure of a fault detection circuit provided in one embodiment of this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various implementations. Simultaneously, the steps or actions described in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0047] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0048] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0049] With the deepening of industrial automation, the communication networks of embedded systems are becoming increasingly larger, and the demand for networking functions is also increasing (such as bus-type servo drives / frequency converters). Scenarios where hundreds of units are simultaneously connected to the network are becoming commonplace. Embedded systems rely on stable DC power supplies. Typically, AC power is converted to DC power through rectification and filtering, and then the DC-DC voltage is converted to a lower voltage by a DC-DC voltage converter module. After filtering by electrolytic capacitors, a DC voltage suitable for embedded system operation is obtained. DC-DC voltage converter modules generally use electrolytic capacitors for filtering. The capacitance value (or lifespan) of electrolytic capacitors is affected by factors such as ambient temperature. As temperature rises, the capacitance value decreases significantly; for example, for every 10-degree Celsius increase in temperature, the lifespan of an electrolytic capacitor is reduced by half. Therefore, in high-temperature environments, the lifespan issue of electrolytic capacitors is particularly prominent. Thus, ensuring the stable operation of electrolytic capacitors is one of the keys to ensuring the normal power supply of embedded systems, thereby guaranteeing the normal operation of the embedded system network and avoiding significant economic and time losses caused by sudden network outages.

[0050] While embedded systems currently incorporate temperature-sensing elements such as thermistors / thermocouples to monitor system temperature, the monitored temperature only reflects the ambient temperature around the thermistor / thermocouple and cannot accurately determine the impact of temperature on the lifespan of electrolytic capacitors, frequently leading to over-protection or under-protection situations. Dedicated temperature-sensing elements for electrolytic capacitors would increase the hardware cost of the circuit and might require a redesign of the circuit board.

[0051] Based on this, this application provides a fault detection method, fault detection circuit, and embedded system for electrolytic capacitors. The method involves high-pass filtering the digital signal converted by the ADC module and performing spectral analysis on the high-pass filtered signal to determine its amplitude at different frequency points. Then, a target maximum amplitude is determined within a preset frequency range, and this target maximum amplitude is compared with a preset threshold corresponding to the preset frequency range. If the target maximum amplitude is greater than the preset threshold, it indicates that there is at least one high-frequency point where the amplitude exceeds the preset threshold, meaning the high-pass filtered signal contains high-frequency noise. This indicates that the corresponding electrolytic capacitor is experiencing aging or significant capacitance degradation. Through this fault detection method, electrolytic capacitor faults can be analyzed without increasing circuit hardware costs. This allows for timely reminders to users before the electrolytic capacitor's lifespan is completely exhausted, enabling early replacement and preventing system failures at uncertain times.

[0052] The following description, in conjunction with the accompanying drawings, explains the fault detection method, fault detection circuit, and embedded system for electrolytic capacitors.

[0053] Reference Figure 1 The fault detection circuit for the electrolytic capacitor shown includes a DC power supply circuit and a controller. The DC power supply circuit includes a voltage conversion module, which converts the input voltage into the operating voltage of the controller. The electrolytic capacitor is coupled between the positive DC voltage terminal and the negative DC voltage terminal of the voltage conversion module. The controller includes an ADC module, which is used to acquire the analog electrical signal of the temperature sensing element in the fault detection circuit.

[0054] Reference Figure 2 and Figure 3 The circuit diagram of the specific fault detection circuit shown is a DC-DC voltage conversion module. A first electrolytic capacitor C1 is installed on the input side of the DC-DC voltage conversion module, with its two ends coupled to the positive and negative DC voltage terminals of the input side, respectively. A second electrolytic capacitor C2 is installed on the output side of the DC-DC voltage conversion module, with its two ends coupled to the positive and negative DC voltage terminals of the output side, respectively. The input voltage on the input side of the DC-DC voltage conversion module can be the voltage obtained after rectification by the AC power supply (e.g., ...). Figure 2 (as shown), or it can be the voltage of a DC power supply (such as...). Figure 3 (As shown).

[0055] The controller has Vdd, Vss, Vdda, Vssa, and ADC pins. The Vdd pin connects to the positive DC voltage terminal of the voltage conversion module's output, and the Vss pin connects to the negative DC voltage terminal of the same module. The Vdda pin is coupled to the Vdd pin, and the Vssa pin is coupled to the Vss pin. The ADC module is powered by the voltage between the Vdda and Vssa pins and is coupled to the temperature sensing element in the fault detection circuit via the ADC pin. It is worth noting that if the controller does not internally couple the Vdda pin to the Vdd pin, an external connection line is added to couple the Vdda pin to the Vdd pin. This coupling can be direct or indirect (e.g., a diode is also placed on the connection line between the two pins). Similarly, if the controller does not internally couple the Vssa pin to the Vss pin, an external connection line is added to couple the Vssa pin to the Vss pin. This coupling can be direct or indirect (e.g., an inductor is also placed on the connection line between the two pins).

[0056] Reference Figure 4 The diagram shows a flowchart of a fault detection method for an electrolytic capacitor provided in an embodiment of this application. The fault detection method includes, but is not limited to, the following steps:

[0057] Step S110: Obtain the digital electrical signal obtained by the ADC module converting the analog electrical signal, and perform high-pass filtering on the digital electrical signal to obtain the high-pass filtered signal;

[0058] Step S120: Perform spectrum analysis on the high-pass filtered signal to determine the target maximum amplitude of the high-pass filtered signal within a preset frequency range, and compare the target maximum amplitude with a preset threshold corresponding to the preset frequency range; the preset frequency range characterizes the frequency range of high-frequency noise generated on the working voltage due to the failure of the electrolytic capacitor.

[0059] Step S130: If the target maximum amplitude value is greater than the preset threshold, it is determined that the electrolytic capacitor has failed.

[0060] When the capacitance of the electrolytic capacitor in the DC power supply circuit decreases significantly (e.g., due to excessively high operating temperature, aging, or other lifespan issues), the internal resistance of the electrolytic capacitor will also increase significantly, causing high-frequency noise to be generated on Vdd of the DC-DC voltage converter module. In the circuit, the positive voltage of the DC-DC voltage converter module's output operating voltage is input to the Vdd pin of the controller, and the negative voltage is input to the Vss pin. Since the Vdda pin of the controller is coupled to the Vdd pin, and the Vssa pin is coupled to the Vss pin, the high-frequency noise in the output operating voltage of the DC-DC voltage converter module will be conducted to Vdda (Vss and Vssa are both grounded). The ADC module performs analog-to-digital conversion on the acquired analog electrical signal, outputting a digital electrical signal that can be used for spectrum analysis. Since the ADC module operates based on the reference voltage Vdda, the high-frequency noise in Vdd will be superimposed on the digital electrical signal output by the ADC module. Under normal operating conditions, the temperature change rate of an electrolytic capacitor is relatively slow. The digital signal converted by the temperature sampling ADC module should not contain high-frequency noise of a fixed frequency. The fault detection method of this application utilizes this characteristic to determine whether the electrolytic capacitor in the DC power supply circuit has a lifespan problem. Therefore, by performing spectral analysis on the digital signal, the high-frequency noise of Vdd can be determined in the frequency domain. Based on this high-frequency noise, analysis can be performed to determine whether the electrolytic capacitor has a lifespan problem, and it can also be determined in advance whether the electrolytic capacitor is nearing the end of its lifespan.

[0061] The digital signal converted by the ADC module contains temperature information from the temperature sensing element in the low-frequency band. Directly performing spectrum analysis on this digital signal would result in the amplitude at each frequency point including temperature information. Different temperature values ​​have different effects on the amplitude, leading to inconsistent standards for amplitude judgment based on preset thresholds. This necessitates considering the current temperature value of the temperature sensing element and applying the corresponding preset threshold, resulting in excessive data volume and a complex judgment process. To avoid the influence of low-frequency signals in spectrum analysis, the digital signal converted by the ADC module is high-pass filtered to remove the influence of temperature values ​​and DC bias, resulting in a high-pass filtered signal. Spectrum analysis is then performed on this high-pass filtered signal. Spectrum analysis methods can include frequency domain expansion algorithms such as Fast Fourier Transform (FFT), and are not limited here.

[0062] If the electrolytic capacitor's lifespan is compromised, the amplitude of the high-pass filter signal at a specific frequency point will exceed a preset threshold. The high-frequency noise of Vdd has a certain frequency point / range (the frequency of the high-frequency noise is related to the equivalent series resistance (ESR) and equivalent series inductance (ESL) of the electrolytic capacitor, as well as the parameters of other components in the circuit). For practical applications, the preset frequency range and preset threshold need to be calculated using appropriate methods. After determining the preset frequency range and preset threshold for the fault detection circuit, a spectrum analysis is performed on the high-pass filter signal. The maximum amplitude value within the preset frequency range is found as the target maximum amplitude value. Then, the target maximum amplitude value is compared with the preset threshold value corresponding to the preset frequency range. If the target maximum amplitude value is greater than the preset threshold value, it indicates that the high-frequency noise at that frequency point is sufficiently large, meaning the electrolytic capacitor has failed.

[0063] The aforementioned fault detection method, without increasing circuit hardware costs, uses an ADC module to collect and convert the digital electrical signal from the temperature sensing element. Based on the spectral analysis of the digital signal, it identifies the point with the largest amplitude within a preset frequency range and compares this amplitude with a preset threshold. Since the preset threshold is determined based on the amplitude of high-frequency noise superimposed in the frequency domain under fault conditions such as electrolytic capacitor depletion, a value greater than the preset threshold indicates a fault in the electrolytic capacitor, requiring the user to perform maintenance, such as replacing the electrolytic capacitor. This method can provide early warning of electrolytic capacitor lifespan issues in the power supply system of embedded systems, thereby preventing unpredictable power supply failures caused by electrolytic capacitor failure at uncertain times.

[0064] Understandably, the digital signal converted by the ADC module can still achieve the original temperature detection function. By performing low-pass filtering on the digital signal, a low-pass filtered signal representing the temperature value can be obtained, thereby determining the temperature value of the sensing element. The controller performs two-way processing on the digital signal: the first path performs low-pass filtering on the digital signal to calculate the temperature value, and the second path performs high-pass filtering on the digital signal, executing the processing steps S120 to S130 above. The first path performs low-pass filtering on the digital signal to calculate the temperature value, referring to... Figure 5 As shown, it specifically includes:

[0065] Step S210: Perform low-pass filtering on the digital electrical signal to obtain a low-pass filtered signal;

[0066] Step S220: Determine the temperature value at the temperature sensing element based on the low-pass filter signal and the preset temperature-signal correspondence.

[0067] When the temperature sensing element is a thermistor, the ADC module acquires the voltage across the thermistor as the input analog electrical signal. The converted digital electrical signal is also a voltage signal. This digital signal is then low-pass filtered to obtain a low-pass filtered signal containing temperature information. Based on the controller's internally preset temperature-signal (in this case, voltage signal) correspondence, the corresponding temperature is determined using the low-pass filtered signal. When the temperature sensing element is a thermocouple, the ADC module acquires the voltage corresponding to the thermocouple's thermoelectric potential as the input analog electrical signal. Similarly, the converted digital electrical signal is also a voltage signal. This digital signal is then low-pass filtered to obtain a low-pass filtered signal containing temperature information. Based on the controller's internally preset temperature-signal (in this case, voltage signal) correspondence, the corresponding temperature is determined using the low-pass filtered signal.

[0068] Depending on the circuit parameters of the actual fault detection circuit, the cutoff frequencies of the low-pass filter and the high-pass filter will also be different. In some embodiments, the cutoff frequency of the low-pass filter is less than 100Hz, and the cutoff frequency of the high-pass filter is greater than 100Hz.

[0069] Reference Figure 6 As shown, in some embodiments, the preset frequency range and preset threshold are obtained in the following ways:

[0070] Step S310: Replace the electrolytic capacitor with the faulty capacitor;

[0071] Step S320: Obtain the digital electrical signal under fault conditions obtained by the ADC module converting the analog electrical signal; perform high-pass filtering on the digital electrical signal under fault conditions to obtain the high-pass filtered signal under fault conditions.

[0072] Step S330: Perform spectrum analysis on the high-pass filter signal under fault conditions to determine the first frequency point corresponding to the largest amplitude value in the high-pass filter signal under fault conditions.

[0073] Step S340: Obtain a preset frequency range by expanding the first frequency point, and determine a preset threshold based on the maximum amplitude value of the high-pass filter signal under fault conditions. The preset threshold is less than the maximum amplitude value of the high-pass filter signal under fault conditions.

[0074] As mentioned above, the preset frequency range and preset threshold are determined based on the current circuit parameters. Steps S310 to S340 provide a method for determining the preset frequency range and preset threshold. Specifically, based on the current fault detection circuit, the electrolytic capacitor is replaced with a faulty capacitor. This faulty capacitor can be a capacitor whose lifespan has expired (the capacitance value of this capacitor has decreased significantly relative to its rated capacitance value and its internal resistance has increased, to simulate the effect of higher temperatures on the electrolytic capacitor). After replacing it with a faulty capacitor, high-frequency noise will be generated on the Vdd voltage during the operation of the fault detection circuit. The high-frequency noise is transmitted to the ADC module. The digital electrical signal acquired and converted by the ADC module contains high-frequency noise in the frequency domain. Therefore, the digital electrical signal is high-pass filtered and expanded in the frequency domain. There is at least one frequency point in the frequency domain with a very high amplitude. The maximum amplitude and the first frequency point corresponding to the maximum amplitude are determined. The first frequency point is the frequency of the high-frequency noise, and the amplitude of the first frequency point is the magnitude of the high-frequency noise. Since the frequency of the high-frequency noise may appear within a certain frequency range, the preset frequency range is obtained based on the first frequency point, and the preset threshold is set according to the amplitude corresponding to the first frequency point. Subsequently, during the actual operation of the fault detection circuit, the frequency point with an amplitude higher than the preset threshold is searched according to the preset frequency range obtained above. If there is one, it indicates that high-frequency noise caused by the failure of the electrolytic capacitor is superimposed in the frequency domain.

[0075] Understandably, if the preset threshold is less than the amplitude of the first frequency point, for example, if 50%-90% of the amplitude of the first frequency point is taken as the preset threshold, it can serve as an early warning. That is, when the amplitude of high-frequency noise in the frequency domain in actual application has not yet reached the amplitude of the first frequency point, the fault detection circuit can remind the user, and the user can replace the electrolytic capacitor that is about to fail in advance.

[0076] Reference Figure 7 As shown, in some embodiments, the step S340 above, which involves expanding the preset frequency range based on the frequency point, includes:

[0077] Step S410: Determine the second frequency point corresponding to the second amplitude value in the high-pass filtered signal under fault conditions;

[0078] Step S420: Expand the frequency range based on the frequency interval between the first frequency point and the second frequency point to obtain the preset frequency range.

[0079] The frequency point expansion method is generally determined according to the distribution of high-frequency noise in the frequency domain. This is because there may be multiple frequency points with significantly large amplitudes in the frequency domain, and these frequency points can all be considered as high-frequency noise frequencies. In this embodiment, the preset frequency range is determined by using the frequency interval formed by the first frequency point with the largest amplitude and the second frequency point with the second largest amplitude. The second frequency point may be higher or lower than the first frequency point. The interval is expanded with the first and second frequency points as endpoints to form the preset frequency range that includes the first and second frequency points. For example, if the first frequency point is 2000Hz and the second frequency point is 4000Hz, the preset frequency range can be 1500Hz-4500Hz.

[0080] according to Figure 2 and Figure 3 In the circuit shown, electrolytic capacitors are installed on both the input and output sides of the DC-DC voltage conversion module. A failure of any electrolytic capacitor will generate high-frequency noise on Vdd. However, the frequency of the high-frequency noise generated on Vdd may differ depending on the electrolytic capacitor's failure. Therefore, multiple preset frequency ranges and preset thresholds are needed to address this. Specifically, referring to steps S320 to S340 above, in the case of multiple electrolytic capacitors, the preset frequency ranges and preset thresholds are obtained as follows:

[0081] Replace the first electrolytic capacitor C1 with the first faulty capacitor to determine the first preset frequency range and the first preset threshold that characterize the first electrolytic capacitor C1 as being in a faulty state.

[0082] The second electrolytic capacitor C2 is replaced with the second faulty capacitor to determine the second preset frequency range and the second preset threshold that characterize the second electrolytic capacitor C2 as being in a faulty state.

[0083] The first electrolytic capacitor C1 is replaced with the first fault capacitor, and the second electrolytic capacitor C2 is replaced with the second fault capacitor, so as to determine the third preset frequency range and the third preset threshold that characterize the first electrolytic capacitor C1 and the second electrolytic capacitor C2 being in a fault state at the same time.

[0084] That is, a total of three sets of preset frequency ranges and preset thresholds are set for the two electrolytic capacitors. The first set of preset frequency ranges and preset thresholds is: the first electrolytic capacitor C1 is replaced with the first faulty capacitor and the second electrolytic capacitor C2 is a normal capacitor. Under this condition, the first preset frequency range and the first preset threshold are determined according to steps S320 to S340. The second set of preset frequency ranges and preset thresholds is: the second electrolytic capacitor C2 is replaced with the second faulty capacitor and the first electrolytic capacitor C1 is a normal capacitor. Under this condition, the second preset frequency range and the second preset threshold are determined according to steps S320 to S340. The third set of preset frequency ranges and preset thresholds is: the first electrolytic capacitor C1 is replaced with the first faulty capacitor and the second electrolytic capacitor C2 is replaced with the second faulty capacitor. Under this condition, the third preset frequency range and the third preset threshold are determined according to steps S320 to S340.

[0085] It is understandable that the above three preset frequency ranges and preset thresholds correspond to the case of two electrolytic capacitors; if there are more electrolytic capacitors, the preset frequency ranges and preset thresholds are obtained by replacing each electrolytic capacitor with a faulty capacitor one by one.

[0086] Therefore, it can be seen that when the fault detection circuit is actually working, after expanding the high-pass filter signal in the frequency domain, it can judge according to each preset frequency range and preset threshold, thereby determining which electrolytic capacitor in the circuit is faulty. Taking the above two electrolytic capacitors as an example, the controller matches the expanded high-pass filter signal in the frequency domain with three preset frequency ranges and preset thresholds. Specifically, this includes at least one of the following:

[0087] Determine the first target maximum amplitude value of the high-pass filtered signal within the first preset frequency range, and compare the first target maximum amplitude value with a first preset threshold value; if the first maximum amplitude value is greater than the first preset threshold value, determine that the first electrolytic capacitor C1 has failed.

[0088] Determine the second target maximum amplitude value of the high-pass filtered signal within the second preset frequency range, and compare the second target maximum amplitude value with the second preset threshold value; if the second maximum amplitude value is greater than the second preset threshold value, determine that the second electrolytic capacitor C2 is faulty;

[0089] Determine the third target maximum amplitude value of the high-pass filtered signal within the third preset frequency range, and compare the third target maximum amplitude value with the third preset threshold value; if the third maximum amplitude value is greater than the third preset threshold value, determine that the first electrolytic capacitor C1 and the second electrolytic capacitor C2 have both failed.

[0090] Understandably, once a fault is confirmed in an electrolytic capacitor, corresponding alerts can be issued based on the specific fault condition. For example, if the first electrolytic capacitor C1 is found to be faulty while the second electrolytic capacitor C2 is functioning normally, a first alert is issued; if the second electrolytic capacitor C2 is found to be faulty while the first electrolytic capacitor C1 is functioning normally, a second alert is issued; and if both the first and second electrolytic capacitors C1 and C2 are found to be faulty, a third alert is issued. This facilitates maintenance personnel in locating the fault and improves processing efficiency.

[0091] In summary, the DC power supply circuit connects to the controller to provide the operating voltage. If the electrolytic capacitor in the DC power supply circuit experiences a significant decrease in capacitance due to aging, it will generate high-frequency noise on the provided operating voltage. This high-frequency noise will be conducted to the reference voltage of the controller's ADC module, thus superimposing a certain frequency of high-frequency noise onto the digital signal converted by the ADC module. The fault detection method of this application performs high-pass filtering on the digital signal and performs spectrum analysis on the high-pass filtered signal to determine the amplitude of the high-pass filtered signal at different frequency points. Then, it determines the target maximum amplitude within a preset frequency range and compares the target maximum amplitude with a preset threshold corresponding to the preset frequency range. If the target maximum amplitude is greater than the preset threshold, it indicates that there is at least one high-frequency point with an amplitude exceeding the preset threshold, that is, the high-pass filtered signal contains high-frequency noise, and the corresponding electrolytic capacitor has experienced a significant decrease in capacitance due to aging. Through the above fault detection method, the fault of the electrolytic capacitor can be analyzed without increasing the circuit hardware cost, thereby reminding the user before the electrolytic capacitor's lifespan is completely exhausted so that the electrolytic capacitor can be replaced in advance, avoiding system failure at an uncertain time.

[0092] The fault detection method of this application will be explained in detail below with a specific example.

[0093] Reference Figure 2 In the circuit shown, the Vdd and Vss pins of the embedded system's controller are connected to the output side of the DC-DC voltage conversion module, and the input side of the DC-DC voltage conversion module is connected to an AC power supply through a rectifier module. A first electrolytic capacitor C1 is provided on the input side of the DC-DC voltage conversion module, and a second electrolytic capacitor C2 is provided on the output side of the DC-DC voltage conversion module.

[0094] The controller's Vdd pin is connected to the controller's Vdda pin, and the controller's Vss pin is connected to the controller's Vssa pin through an inductor. The controller's ADC pin is the acquisition pin, used to acquire the analog electrical signal of the temperature sensing element and convert the analog electrical signal into a digital electrical signal.

[0095] Depending on the type of electrolytic capacitor failure, the conversion result of the ADC module may contain multiple noise frequencies. (Refer to...) Figure 8, Figure 9 and Figure 10 As shown, the method for determining the frequency and threshold caused by the depletion of the electrolytic capacitor's lifespan is as follows:

[0096] Group 1: Replace the first electrolytic capacitor C1 in the circuit with a capacitor that has exhausted its lifespan. After powering on, the controller reads the conversion result of the ADC module, performs high-pass filtering on the conversion result, and performs FFT spectrum analysis. Select the frequency point corresponding to the largest amplitude in the frequency domain as Fnoise1, and determine the frequency range 1 based on Fnoise1. Use 50%-90% of the largest amplitude as the threshold Plim1.

[0097] The second group: Replace the second electrolytic capacitor C2 in the circuit with a capacitor that has exhausted its lifespan. After powering on, the controller reads the conversion result of the ADC module, performs high-pass filtering on the conversion result, and performs FFT spectrum analysis. Select the frequency point corresponding to the largest amplitude in the frequency domain as Fnoise2, and determine the frequency range 2 based on Fnoise2. Take 50%-90% of the largest amplitude as the threshold Plim2.

[0098] Group 3: Replace the first electrolytic capacitor C1 and the second electrolytic capacitor C2 in the circuit with capacitors that have exhausted their lifespan. After power-on, the controller reads the conversion result of the ADC module, performs high-pass filtering on the conversion result, and performs FFT spectrum analysis. Select the frequency point corresponding to the largest amplitude in the frequency domain as Fnoise3, and determine the frequency range 3 based on Fnoise3. Use 50%-90% of the largest amplitude as the threshold Plim3.

[0099] Under normal operating conditions, the temperature of an electrolytic capacitor changes relatively slowly. The digital electrical signal converted by the temperature sampling ADC module should not contain high-frequency noise of a fixed frequency. The fault detection method of this application utilizes this characteristic to determine whether the electrolytic capacitor in the circuit has a lifespan problem.

[0100] Specifically, the controller reads the conversion result (digital electrical signal) of the ADC. The first branch performs low-pass filtering on the conversion result and calculates the temperature value of the temperature sensing element. The second branch performs high-pass filtering on the conversion result to filter out the influence of temperature value and DC bias. Then, FFT spectrum analysis is performed on the high-pass filtered result to obtain the amplitude of the signal at different frequencies.

[0101] In the frequency domain, extract the maximum amplitude Pnoise1 from the frequency range 1, compare the maximum amplitude Pnoise1 with the threshold Plim1, and if Pnoise1>Plim1, then determine that the first electrolytic capacitor C1 is close to the end of its life.

[0102] In the frequency domain, extract the maximum amplitude Pnoise2 from the frequency range 2, compare the maximum amplitude Pnoise2 with the threshold Plim2, and if Pnoise2>Plim2, then determine that the second electrolytic capacitor C2 is close to the end of its life.

[0103] In the frequency domain, extract the maximum amplitude Pnoise3 from the frequency range 3, compare the maximum amplitude Pnoise3 with the threshold Plim3, and if Pnoise3>Plim3, then determine that the first electrolytic capacitor C1 and the second electrolytic capacitor C2 are close to the end of their lifespan.

[0104] Based on the above judgment results, a warning message will be issued to the user. The user can replace the capacitor or controller in advance to avoid the embedded system's network from going offline at an unpredictable time.

[0105] like Figure 11 As shown, Figure 11 This is a schematic diagram of a fault detection circuit 1000 provided in one embodiment of this application.

[0106] The fault detection circuit 1000 in this embodiment includes one or more processors 1001 and a memory 1002. Figure 11 The example uses a processor 1001 and a memory 1002.

[0107] Processor 1001 and memory 1002 can be connected via a bus or other means. Figure 11 Taking the example of a connection between China and Israel via a bus.

[0108] Memory 1002, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory 1002 may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory 1002 may optionally include memory 1002 remotely located relative to processor 1001, and these remote memories can be connected to the fault detection circuit 1000 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0109] Those skilled in the art will understand that Figure 11 The device structure shown does not constitute a limitation on the fault detection circuit 1000, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0110] This application also provides an embedded system including the aforementioned fault detection circuit 1000.

[0111] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network nodes. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0112] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0113] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0114] In the several embodiments provided in this application, it should be understood that the disclosed systems, instruments, and methods can be implemented in other ways. For example, the instrument embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between instruments or units may be electrical, mechanical, or other forms. Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, i.e., they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0115] It should also be understood that the various implementation methods provided in this application can be combined arbitrarily to achieve different technical effects.

[0116] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A fault detection method for electrolytic capacitors, characterized in that, The fault detection circuit includes a DC power supply circuit and a controller; the DC power supply circuit includes a voltage conversion module for converting the input voltage into the operating voltage of the controller, and the electrolytic capacitor is coupled between the positive DC voltage terminal and the negative DC voltage terminal of the voltage conversion module. The controller includes an ADC module, which is used to acquire the analog electrical signal of the temperature sensing element in the fault detection circuit; The fault detection method includes: The digital electrical signal obtained by the ADC module converting the analog electrical signal is acquired, and the digital electrical signal is subjected to high-pass filtering to obtain a high-pass filtered signal. Spectral analysis is performed on the high-pass filtered signal to determine the target maximum amplitude value of the high-pass filtered signal within a preset frequency range, and the target maximum amplitude value is compared with a preset threshold value corresponding to the preset frequency range; the preset frequency range characterizes the frequency range of high-frequency noise generated on the operating voltage due to the failure of the electrolytic capacitor. If the maximum target value is greater than the preset threshold, the electrolytic capacitor is determined to be faulty.

2. The method according to claim 1, characterized in that, The preset frequency range and the preset threshold are obtained in the following way: Replace the electrolytic capacitor with the faulty capacitor; The digital electrical signal under fault conditions obtained by the ADC module converting the analog electrical signal is acquired, and the digital electrical signal under fault conditions is subjected to high-pass filtering to obtain a high-pass filtered signal under fault conditions. Perform spectral analysis on the high-pass filtered signal under the fault condition to determine the first frequency point corresponding to the largest amplitude value in the high-pass filtered signal under the fault condition. The preset frequency range is obtained by expanding the first frequency point, and the preset threshold is determined based on the maximum amplitude value of the high-pass filtered signal under the fault state, wherein the preset threshold is less than the maximum amplitude value of the high-pass filtered signal under the fault state.

3. The method according to claim 2, characterized in that, The step of expanding the preset frequency range based on the frequency point includes: Determine the second frequency point corresponding to the second amplitude value in the high-pass filtered signal under the fault condition; The preset frequency range is obtained by expanding the frequency range between the first frequency point and the second frequency point.

4. The method according to claim 1 or 2, characterized in that, The electrolytic capacitor includes a first capacitor and a second capacitor. The first capacitor is coupled between the DC positive voltage terminal and the DC negative voltage terminal on the input side of the voltage conversion module, and the second capacitor is coupled between the DC positive voltage terminal and the DC negative voltage terminal on the output side of the voltage conversion module. The preset frequency range and the preset threshold are obtained in the following way: The first electrolytic capacitor is replaced with the first fault capacitor to determine the first preset frequency range and the first preset threshold that characterize the first electrolytic capacitor as being in a fault state. The second electrolytic capacitor is replaced with the second fault capacitor to determine a second preset frequency range and a second preset threshold that characterize the second electrolytic capacitor as being in a faulty state. The first electrolytic capacitor is replaced with a first fault capacitor and the second electrolytic capacitor is replaced with a second fault capacitor to determine a third preset frequency range and a third preset threshold that characterize the first electrolytic capacitor and the second electrolytic capacitor being in a fault state at the same time.

5. The method according to claim 4, characterized in that, The comparison of the target maximum amplitude with a preset threshold corresponding to the preset frequency range includes at least one of the following: Determine the first target maximum amplitude value of the high-pass filtered signal within the first preset frequency range, and compare the first target maximum amplitude value with the first preset threshold value; if the first maximum amplitude value is greater than the first preset threshold value, determine that the first electrolytic capacitor has failed; Determine the second target maximum amplitude value of the high-pass filtered signal within the second preset frequency range, and compare the second target maximum amplitude value with the second preset threshold. If the second maximum value is greater than the second preset threshold, it is determined that the second electrolytic capacitor has failed. Determine the third target maximum amplitude value of the high-pass filtered signal within the third preset frequency range, and compare the third target maximum amplitude value with the third preset threshold. If the third maximum amplitude value is greater than the third preset threshold, it is determined that both the first electrolytic capacitor and the second electrolytic capacitor have failed simultaneously.

6. The method according to claim 1, characterized in that, The controller includes a Vdd pin, a Vss pin, a Vdda pin, a Vssa pin, and an ADC pin; the Vdd pin is connected to the positive DC voltage terminal of the output side of the voltage conversion module, and the Vss pin is connected to the negative DC voltage terminal of the output side of the voltage conversion module; the Vdda pin is coupled to the Vdd pin, and the Vssa pin is coupled to the Vss pin; the ADC module is powered by the voltage between the Vdda pin and the Vssa pin, and is coupled to the temperature sensing element in the fault detection circuit through the ADC pin.

7. The method according to claim 1, characterized in that, After obtaining the digital electrical signal, the method further includes: The digital electrical signal is subjected to low-pass filtering to obtain a low-pass filtered signal; The temperature value at the temperature sensing element is determined based on the low-pass filtered signal and the preset temperature-signal correspondence.

8. The method according to claim 7, characterized in that, The cutoff frequency of the low-pass filter is less than 100Hz, and the cutoff frequency of the high-pass filter is greater than 100Hz.

9. A fault detection circuit, characterized in that, It includes at least one controller and a memory for communicating with the at least one controller; The memory stores instructions that can be executed by the at least one controller to enable the at least one controller to perform the method as described in any one of claims 1 to 8.

10. An embedded system comprising the fault detection circuit of claim 9.

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