Electrical safety pre-detection device suitable for high-capacity capacitor
By applying AC voltage and DC voltage to the electrical safety pre-detection device of large-capacitor capacitors, the problem of inaccurate leakage current testing in high-humidity environments is solved, more efficient testing and more accurate results are achieved, and the product yield rate is improved.
Patent Information
- Application Number
- CN202510307331.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-06-06
AI Technical Summary
The leakage current test results of large-capacitor capacitors in high humidity environments are inaccurate and the test efficiency is low, making it difficult to distinguish the open circuit or short circuit of the circuit and the leakage current.
An electrical safety pre-detection device is designed, including a voltage output module and an electrical safety pre-detection module. By applying AC voltage and DC voltage, the capacitance value range is detected by the AC voltage, and the leakage current size and short circuit situation are detected by the DC voltage.
It improves the accuracy and efficiency of large-capacity capacitor leakage current test, can accurately determine whether the device is open or short-circuited, and initially screens out devices with significantly large leakage current, improving the reliability of the test results and product yield.
Smart Images
Figure CN120103213A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of capacitor packaging and testing, and in particular to an electrical safety pre-detection device suitable for large-capacity capacitors. Background Art
[0002] At present, large-capacity capacitors are packaged and tested before they are put into production. During the package test, the size of the measured current is generally used to determine whether the device is open during the test or whether a tantalum core is packaged inside the device.
[0003] However, when the ambient humidity is high, the current of the large-capacity capacitor actually tested is comparable to the current of the open-circuit test, making it impossible to determine whether the leakage current tested is caused by an open circuit or the leakage current of the large-capacity capacitor itself, thereby affecting the accuracy of the test results.
[0004] In addition, when conducting a leakage current test, since the charging current is relatively large, it is necessary to charge for a period of time first, and then measure the leakage current after the charging current gradually decreases. This makes it take a long time to screen out devices with large leakage current, which leads to low test efficiency. Summary of the invention
[0005] The purpose of the present application is to solve at least one of the above-mentioned technical defects, especially the technical defects of low accuracy of leakage current test results of large-capacity capacitors and low test efficiency in the prior art.
[0006] The present application provides an electrical safety pre-detection device applicable to large-capacity capacitors, the device comprising a voltage output module connected to one end of a device under test, and an electrical safety pre-detection module connected to the other end of the device under test;
[0007] Wherein, the voltage output module is used to apply AC voltage and DC voltage to the device under test;
[0008] The electrical safety pre-detection module is used to detect whether the device under test is open or short-circuited, and the magnitude of the leakage current.
[0009] Optionally, the voltage output module includes a DC voltage output circuit, an AC voltage output circuit and an adder;
[0010] The DC voltage output circuit and the AC voltage output circuit are respectively connected to the input end of the adder, and the output end of the adder is connected to the device under test.
[0011] Optionally, the AC voltage output circuit is a sine wave generating circuit.
[0012] Optionally, a first protection resistor is connected in series between the adder and the device under test.
[0013] Optionally, the electrical safety pre-detection module includes a voltage divider circuit, a DC voltage detection circuit and an AC voltage detection circuit;
[0014] The device under test is connected in series with the DC voltage detection circuit and the AC voltage detection circuit respectively through the voltage divider circuit.
[0015] Optionally, the DC voltage detection circuit includes a first low-pass filter and a first comparator connected in series.
[0016] Optionally, the AC voltage detection circuit includes a bandpass filter, a high-speed absolute value circuit, a second low-pass filter and a second comparator which are connected in series in sequence.
[0017] Optionally, when both the first comparator and the second comparator output a high level, the device under test is open circuited;
[0018] When the first comparator outputs a high level and the second comparator outputs a low level, the device under test is normal;
[0019] When the first comparator outputs a low level and the second comparator outputs a high level, the device under test is short-circuited;
[0020] When both the first comparator and the second comparator output a low level, the leakage current of the device under test is greater than a preset current value.
[0021] Optionally, a second protection resistor is connected in series between the device under test and the voltage divider circuit.
[0022] Optionally, the threshold voltages of the first comparator and the second comparator are set according to the capacity range of the device under test.
[0023] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:
[0024] The present application provides an electrical safety pre-detection device suitable for large-capacity capacitors, the device includes a voltage output module connected to one end of the device under test, and an electrical safety pre-detection module connected to the other end of the device under test; wherein, the voltage output module of the present application can apply AC voltage and DC voltage to the device under test, so that the device under test is in a state similar to the actual work during the test, ensuring that the test results reflect the real situation, and after the present application applies AC voltage and DC voltage to the device under test, the electrical safety pre-detection module can use AC voltage to judge the capacitance value range of the device under test, and then detect whether the device under test is open circuit, and can also use DC voltage to judge the leakage current size of the device under test and whether a short circuit occurs. In this way, it is possible to accurately judge whether the device under test is open circuit or short circuit, and to preliminarily screen out devices with obviously large leakage current before testing, thereby effectively improving the test accuracy and test efficiency, and also improving the yield rate of the product under test. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0026] Figure 1 A schematic diagram of the structure of an electrical safety pre-detection device suitable for large-capacity capacitors provided in an embodiment of the present application;
[0027] Figure 2 A schematic diagram of the circuit structure of an electrical safety pre-detection device provided in an embodiment of the present application. DETAILED DESCRIPTION
[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only 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 creative work are within the scope of protection of this application.
[0029] In one embodiment, Figure 1 As shown, Figure 1 A structural schematic diagram of an electrical safety pre-detection device suitable for large-capacity capacitors provided in an embodiment of the present application; the present application provides an electrical safety pre-detection device suitable for large-capacity capacitors, the device comprising a voltage output module connected to one end of the device under test, and an electrical safety pre-detection module connected to the other end of the device under test.
[0030] Wherein, the voltage output module is used to apply AC voltage and DC voltage to the device under test.
[0031] The electrical safety pre-detection module is used to detect whether the device under test is open or short-circuited, and the magnitude of the leakage current.
[0032] In the present embodiment, since the large-capacity capacitor generally only needs to perform low-frequency testing when performing packaging testing, low-frequency testing is used when testing tantalum capacitors, electrolytic capacitors, solid capacitors, etc. High-frequency testing is generally applicable to multilayer ceramic capacitors or film capacitors. When the present application performs a low-frequency test on a large-capacity capacitor, the large-capacity capacitor can be equivalent to a circuit model in which a pure resistor and a pure capacitor are connected in parallel. At this time, it is only necessary to connect the circuit model to the electrical safety pre-detection device of the present application, and then perform an electrical safety pre-inspection before testing it, and preliminarily screen out devices with significantly larger leakage currents through pre-inspection, and determine whether the device under test is open or short-circuited, thereby effectively improving the accuracy and test efficiency during leakage current testing.
[0033] Specifically, when the electrical safety pre-detection device of the present application performs pre-detection on a device under test with a large-capacity capacitor, its voltage output module can be connected to one end of the device under test to apply AC voltage and DC voltage to the device under test, and its electrical safety pre-detection module can be connected to the other end of the device under test. In this way, it can detect whether the device under test is open or short-circuited, as well as the size of the leakage current, thereby realizing circuit inspection of the device under test and preliminary leakage current screening.
[0034] It is understandable that the present application applies voltage to the device under test through the voltage output module, and the leakage current of the device under test can be accurately measured to ensure the safety and reliability of the device under test in actual use. Further, since a simple DC voltage cannot determine the size of the capacitance of the device under test, a simple AC voltage cannot detect the short circuit of the device under test. Therefore, in order to detect whether the device under test is open or short-circuited, and whether the leakage current is too large, the voltage applied by the voltage output module to the device under test includes both a DC voltage and an AC voltage, so that the electrical safety pre-detection module can use the AC voltage to determine the capacitance value range of the device under test, and then detect whether the device under test is open, and can also use the DC voltage to determine the leakage current size of the device under test and whether a short circuit occurs.
[0035] For example, the device under test of the present application may be a tantalum capacitor. Since the withstand voltage range of the tantalum capacitor itself is generally between 3V and 75V, and the capacity is generally between 100nF and 470uF. Therefore, the use of the electrical safety pre-detection device of the present application can achieve rapid open and short circuit detection of the tantalum capacitor. For example, the present application can use AC voltage division to determine the capacitance value range of the tantalum capacitor. When the capacitance value is detected to be lower than 100nF, the tantalum capacitor can be considered to be open. This process no longer needs to detect leakage current, and the capacitance value can be used to detect whether the circuit is open, thereby effectively improving the measurement accuracy.
[0036] In addition, when the capacity of the tantalum capacitor is large, such as above 470uF, the charging time will be longer. At this time, if the leakage current is large or the tantalum capacitor is short-circuited internally, the electrical safety pre-detection module can also be used to determine the leakage current of the tantalum capacitor or whether a short circuit occurs.
[0037] In the above embodiment, the device includes a voltage output module connected to one end of the device under test, and an electrical safety pre-detection module connected to the other end of the device under test; wherein, the voltage output module of the present application can apply AC voltage and DC voltage to the device under test, so that the device under test is in a state similar to the actual work during the test, ensuring that the test results reflect the real situation, and after the present application applies AC voltage and DC voltage to the device under test, the electrical safety pre-detection module can use AC voltage to determine the capacitance value range of the device under test, and then detect whether the device under test is open circuit, and can also use DC voltage to determine the leakage current size of the device under test and whether a short circuit occurs. In this way, it is possible to accurately determine whether the device under test is open circuit or short circuit, and to preliminarily screen out devices with significantly larger leakage current before testing, thereby effectively improving the test accuracy and test efficiency, and also improving the yield rate of the product under test.
[0038] In one embodiment, Figure 2 As shown, Figure 2 A schematic diagram of the circuit structure of an electrical safety pre-detection device provided in an embodiment of the present application; the voltage output module may include a DC voltage output circuit, an AC voltage output circuit and an adder.
[0039] The DC voltage output circuit and the AC voltage output circuit are respectively connected to the input end of the adder, and the output end of the adder is connected to the device under test.
[0040] In this embodiment, since the voltage applied by the voltage output module of the present application to the device under test includes both a DC voltage and an AC voltage, the voltage output module of the present application includes both a DC voltage output circuit and an AC voltage output circuit, and also includes an adder, which is arranged between the device under test and the DC voltage output circuit and the AC voltage output circuit.
[0041] Specifically, in the present application, the input end of the adder is respectively connected to the DC voltage output circuit and the AC voltage output circuit, and the output end is connected to the device under test, so that the DC voltage output by the DC voltage output circuit and the AC voltage output by the AC voltage output circuit can be superimposed and acted on the device under test, so that the device under test is in a state similar to the actual working state during the test, thereby ensuring that the test results reflect the actual situation.
[0042] In one embodiment, the AC voltage output circuit is a sine wave generating circuit.
[0043] In this embodiment, Figure 2 As shown, the AC voltage output circuit in the voltage output module can be a sine wave generating circuit, which uses a sinusoidal signal as an excitation source and combines the DC voltage output by the DC voltage output circuit to enable the device under test to output DC signals and AC signals at the same time, so as to improve the test dimension and test efficiency.
[0044] In addition, the frequency of the sinusoidal signal in the present application can be adjusted according to the capacitance range of the large-capacity capacitor to be tested. For example, when the device under test is a tantalum capacitor with an operating voltage range of 3.3V to 150V, considering that the frequency is too low and the test time needs to be extended, and the circuit component cost is too high if the frequency is too high, the present application can set the frequency of the sinusoidal signal to 5kHz~15kHz, which is based on the convenience of circuit design and is not limited here.
[0045] In a specific implementation, the present application can set the sinusoidal signal to 10kHz, so that the filter response time is shorter. Then set the reset operation, discharge the low-pass filter capacitor, disconnect the VIN input, and then perform the test operation, connect the VIN input, and delay 10ms to get the test result. The entire circuit is powered by a ±5V power supply. The overall test solution is simple, the circuit size is small, and it is easy to integrate multiple channels for synchronous testing.
[0046] In one embodiment, Figure 2 As shown, a first protection resistor Rprotect1 is connected in series between the adder and the device under test. The first protection resistor can prevent the device under test from being short-circuited, and the resistance of the first protection resistor is small and can be ignored during calculation.
[0047] In one embodiment, the electrical safety pre-detection module may include a voltage divider circuit, a DC voltage detection circuit, and an AC voltage detection circuit.
[0048] The device under test is connected in series with the DC voltage detection circuit and the AC voltage detection circuit respectively through the voltage divider circuit.
[0049] In this embodiment, Figure 2As shown, the electrical safety pre-detection module of the present application may include a voltage divider circuit, a DC voltage detection circuit and an AC voltage detection circuit. In this way, the voltage output by the device under test can be divided into a DC voltage divider and an AC voltage divider by the voltage divider circuit, and the size of the DC voltage divider can be detected by the DC voltage detection circuit, and the size of the AC voltage divider can be detected by the AC voltage detection circuit. In this way, it is possible to accurately determine whether the device under test is open or short-circuited, and preliminarily screen out devices with obviously large leakage current before testing, thereby effectively improving the test accuracy and test efficiency, and can also improve the yield rate of the product under test.
[0050] Among them, the voltage divider circuit of the present application can be composed of a DC voltage divider resistor Rx and an AC voltage divider capacitor Cs. The sizes of the DC voltage divider resistor Rx and the AC voltage divider capacitor Cs can be adjusted according to the capacitance range of the device under test, and are not limited here.
[0051] In one embodiment, the DC voltage detection circuit includes a first low-pass filter and a first comparator connected in series.
[0052] In this embodiment, Figure 2 As shown, the DC voltage detection circuit of the present application may include a first low-pass filter and a first comparator connected in series, wherein the input end of the first low-pass filter is connected to the voltage divider circuit, and the output end is connected to the first comparator, so that after the DC voltage is taken out through the first low-pass filter, the threshold of the leakage current can be monitored through the first comparator.
[0053] It is understandable that when the DC leakage current of the device under test of the present application is large, that is, when the equivalent parallel resistance Rx is small, the voltage on Rs in the voltage divider circuit formed by Rx and Rs will increase, and if it exceeds the DC_THRESHOLD threshold voltage of the first comparator, DC_STATUS will output a low level. Therefore, the present application can monitor the threshold of the leakage current by adjusting the voltage of DC_THRESHOLD.
[0054] In one embodiment, the AC voltage detection circuit includes a bandpass filter, a high-speed absolute value circuit, a second low-pass filter and a second comparator which are sequentially connected in series.
[0055] In this embodiment, Figure 2 As shown, the DC voltage detection circuit of the present application may include a bandpass filter, a high-speed absolute value circuit, a second low-pass filter and a second comparator connected in series in sequence, wherein the input end of the bandpass filter is connected to the voltage divider circuit, and the high-speed absolute value circuit, the second low-pass filter and the second comparator are connected to the bandpass filter in sequence, so that after obtaining the AC signal through the bandpass filter, the high-speed absolute value circuit and the second low-pass filter circuit are used to convert the AC signal into a measurable DC signal, and then input it into the second comparator for measurement.
[0056] It is understandable that when the device under test is normal, the parallel equivalent resistance Rx is very large, and only Cx works. At this time, Cx and Cs form a voltage divider circuit, and the effect of Rs can be almost ignored. At this time, if Cx increases, the voltage divider on Cs will also increase. When Cx increases to a certain extent, that is, the filtered voltage is higher than AC_THRESHOLD in the second comparator, AC_STATUS will output a low level. Therefore, the present application can monitor the threshold of the measured capacitance value by adjusting the voltage of AC_THRESHOLD.
[0057] In one embodiment, when both the first comparator and the second comparator output a high level, the device under test is open circuit.
[0058] When the first comparator outputs a high level and the second comparator outputs a low level, the device under test is normal.
[0059] When the first comparator outputs a low level and the second comparator outputs a high level, the device under test is short-circuited.
[0060] When both the first comparator and the second comparator output a low level, the leakage current of the device under test is greater than a preset current value.
[0061] In this embodiment, when the DC voltage detection circuit of the application includes a first low-pass filter and a first comparator connected in series, and the DC voltage detection circuit of the application includes a band-pass filter, a high-speed absolute value circuit, a second low-pass filter and a second comparator connected in series in sequence, the application can detect the size of the DC voltage division through the DC voltage detection circuit, and can also detect the size of the AC voltage division through the AC voltage detection circuit.
[0062] Schematically, as shown in the following table:
[0063]
[0064] Table 1 Output levels and results of the first comparator and the second comparator
[0065] It can be seen from the above table that when the DC voltage in the circuit is lower than the threshold voltage DC_THRESHOLD of the first comparator, and the AC voltage in the circuit is lower than the threshold voltage AC_THRESHOLD of the second comparator, both the first comparator and the second comparator output a high level, and the device under test is open; when the DC voltage in the circuit is lower than the threshold voltage DC_THRESHOLD of the first comparator, and the AC voltage in the circuit is higher than the threshold voltage AC_THRESHOLD of the second comparator, the first comparator outputs a high level, and the second comparator outputs a low level, and the device under test is normal; when the circuit When the DC voltage division in the circuit is higher than the threshold voltage DC_THRESHOLD of the first comparator, and the AC voltage division in the circuit is lower than the threshold voltage AC_THRESHOLD of the second comparator, the first comparator outputs a low level and the second comparator outputs a high level. At this time, the device under test is short-circuited; when the DC voltage division in the circuit is higher than the threshold voltage DC_THRESHOLD of the first comparator, and the AC voltage division in the circuit is higher than the threshold voltage AC_THRESHOLD of the second comparator, the first comparator outputs a low level and the second comparator outputs a low level. At this time, the leakage current of the device under test is greater than the preset current value.
[0066] In addition, since the circuit of the present application only needs to output two level signals to determine whether the device under test is open, short-circuited, or whether the leakage current is too large, the present application can use a single-chip microcomputer to implement 8 or 16 high and low level detections. In this way, a single-chip microcomputer detection circuit can simultaneously support 4 or 8 large-capacity capacitors for simultaneous testing, thereby further improving the test efficiency.
[0067] In one embodiment, Figure 2 As shown, a second protection resistor Rprotect2 is connected in series between the device under test and the voltage divider circuit. The second protection resistor can prevent the device under test from being short-circuited, and the resistance of the second protection resistor is small and can be ignored in calculation.
[0068] In one embodiment, the threshold voltages of the first comparator and the second comparator are set according to the capacity range of the device under test.
[0069] In this embodiment, Figure 2 As shown, the first comparator of the present application is provided with a threshold voltage DC_THRESHOLD, and the second comparator is provided with a threshold voltage AC_THRESHOLD. The present application compares the capacitance value of the device under test with DC_THRESHOLD and AC_THRESHOLD respectively, and detects whether the circuit is open, short-circuited, or whether the leakage current is too large according to the comparison result. Therefore, the present application can set the threshold voltages of the first comparator and the second comparator according to the capacity range of the device under test.
[0070] For example, when the present application selects a tantalum capacitor with a capacity range of 100nF~470uF for testing, the DC_THRESHOLD in the first comparator of the present application can be set to about 0.5~1V, and the AC_THRESHOLD in the second comparator can be set to about 1.2~2.5V. The specific adjustment can be made depending on the actual capacity of the device under test and is not limited here.
[0071] Finally, it should be noted that, in this article, relational terms such as first and second, etc. 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 presence of other identical elements in the process, method, article or device including the elements.
[0072] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can refer to each other.
[0073] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. 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 application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An electrical safety pre-detection device suitable for large-capacity capacitors, characterized in that: The device comprises a voltage output module connected to one end of the device under test, and an electrical safety pre-detection module connected to the other end of the device under test; Wherein, the voltage output module is used to apply AC voltage and DC voltage to the device under test; The electrical safety pre-detection module is used to detect whether the device under test is open or short-circuited, and the magnitude of the leakage current.
2. The electrical safety pre-detection device for large-capacity capacitors according to claim 1, characterized in that: The voltage output module includes a DC voltage output circuit, an AC voltage output circuit and an adder; The DC voltage output circuit and the AC voltage output circuit are respectively connected to the input end of the adder, and the output end of the adder is connected to the device under test.
3. The electrical safety pre-detection device for large-capacity capacitors according to claim 2, characterized in that: The AC voltage output circuit is a sine wave generating circuit.
4. The electrical safety pre-detection device for large-capacity capacitors according to claim 2, characterized in that: A first protection resistor is connected in series between the adder and the device under test.
5. The electrical safety pre-detection device for large-capacity capacitors according to any one of claims 1 to 4, characterized in that: The electrical safety pre-detection module includes a voltage divider circuit, a DC voltage detection circuit and an AC voltage detection circuit; The device under test is connected in series with the DC voltage detection circuit and the AC voltage detection circuit respectively through the voltage divider circuit.
6. The electrical safety pre-detection device for large-capacity capacitors according to claim 5, characterized in that: The DC voltage detection circuit includes a first low-pass filter and a first comparator connected in series.
7. The electrical safety pre-detection device for large-capacity capacitors according to claim 6, characterized in that: The AC voltage detection circuit includes a bandpass filter, a high-speed absolute value circuit, a second low-pass filter and a second comparator which are sequentially connected in series.
8. The electrical safety pre-detection device for large-capacity capacitors according to claim 7, characterized in that: When both the first comparator and the second comparator output a high level, the device under test is open circuited; When the first comparator outputs a high level and the second comparator outputs a low level, the device under test is normal; When the first comparator outputs a low level and the second comparator outputs a high level, the device under test is short-circuited; When both the first comparator and the second comparator output a low level, the leakage current of the device under test is greater than a preset current value.
9. The electrical safety pre-detection device for large-capacity capacitors according to claim 5, characterized in that: A second protection resistor is connected in series between the device under test and the voltage divider circuit.
10. The electrical safety pre-detection device for large-capacity capacitors according to claim 7 or 8, characterized in that: The threshold voltages of the first comparator and the second comparator are set according to the capacity range of the device under test.