A method for evaluating the health state of an optocoupler based on a switching time characteristic parameter

Abstract

The application discloses a kind of optical coupler health state evaluation methods based on switching time characteristic parameters, pre-calibration switching time characteristic parameters t r The mapping relationship between CTR;In the state that optical coupler is in online operation, the switching time characteristic parameters of optical coupler are detected and calculated t r Online real-time detection value;Based on the mapping relationship between pre-calibration switching time characteristic parameters t r The mapping relationship between CTR;The online real-time value of CTR corresponding to optical coupler is calculated;Based on the change of the online real-time value of CTR corresponding to optical coupler with the online operation time of optical coupler, the health state of optical coupler is evaluated;The application avoids the complex measurement process of directly measuring CTR and avoids the interference to original circuit in measurement process;Meanwhile, the application is based on the performance degradation condition of optical coupler under real switching mode, and the life evaluation model is established under actual working environment, so that the health state of optical coupler under specific condition can be more accurately reflected.

Description

Technical Field

[0001] This invention belongs to the field of electronic component reliability testing, specifically relating to a method for evaluating the health status of optocouplers based on switching time characteristic parameters, which is particularly suitable for application as a life evaluation method for optocouplers in relay protection boards. Background Technology

[0002] Relay protection boards are widely used in critical scenarios such as high-voltage switchgear and substations. They typically integrate a large number of optocouplers. As a core component of relay protection boards in power systems, optocouplers are responsible for the "electrical-optical-electrical" isolation and transmission of switching signals (such as protection action signals, switch positions, power indications, etc.), achieving safe isolation between high-voltage and low-voltage systems and accurate signal transmission. Their reliability directly determines the reliability and safety of relay protection equipment. However, relay protection boards are exposed to harsh environments such as high temperatures and electromagnetic interference for extended periods, accelerating the aging process of the optocouplers.

[0003] CTR (Current Transfer Ratio, i.e., Output Current) I C With input current I F The current transfer ratio (CTR) is a core indicator of optocoupler health status, therefore existing optocoupler health status assessments (which are also equivalent to life assessment methods) generally rely on CTR measurement. However, traditional CTR testing techniques have significant limitations in practical applications of relay protection boards, and are highly complex to operate: they require applying and detecting the input-side drive current under offline conditions. I F At the same time, it is necessary to measure the output side collector current. I C Furthermore, a constant drive current must be continuously applied during the measurement, which generates additional temperature stress, causing temperature rise deviations in the device and affecting the accuracy of optocoupler health status monitoring. In addition, optocouplers in relay protection boards often operate in dynamic switching mode, while CTR testing relies on static current loading, which cannot reflect the degradation mechanism under real dynamic switching conditions. Therefore, current optocoupler lifetime assessment models based on CTR often fail to accurately reflect the health status of optocouplers in actual operating environments (real dynamic switching).

[0004] Patent application CN116298848A (application number CN202310196668.7) discloses a method, device and medium for assessing the expected life of an optocoupler. This invention uses the input current as a sensitive parameter to indicate the health status of the optocoupler and uses the Weibull distribution to obtain the optocoupler life model. However, the input current required by this method needs to be measured offline, which is complicated to operate and still cannot accurately reflect the health status of the optocoupler in the actual working environment (real dynamic switch).

[0005] Chenhao Wu et al. published a paper entitled "An Online Proactive CTR Monitoring Method for Optocoupler in Automotive Auxiliary Converter" IEEE Transactions on Instrumentation and Measurement The article (vol. 70, pp. 1-13, 2021) proposes an online optocoupler CTR test circuit that measures CTR by measuring the voltage at key nodes. However, the accuracy of CTR measurement in this method mainly depends on the accuracy of voltage measurement and the accuracy of the two resistors. In practical applications, if the resistor values ​​shift due to aging or temperature changes, it will lead to CTR calculation errors.

[0006] In summary, in the current technology, the offline measurement method used for measuring the CTR parameter of optocouplers requires interrupting the operation of the equipment and disconnecting the optocoupler. Furthermore, the measurement requires simultaneous monitoring of both the input and output currents of the optocoupler, which increases the cost of power system downtime maintenance and cannot accurately reflect the dynamic characteristics of the device under real operating conditions. On the other hand, online measurement usually requires the introduction of current or voltage sampling circuits into the original circuit, which will interfere with the original circuit and change the signal transmission characteristics, resulting in limited measurement accuracy.

[0007] Therefore, the applicant seeks technical solutions to address the above-mentioned technical problems. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a method for evaluating the health status of an optocoupler based on switching time characteristic parameters, which avoids the complex measurement process of directly measuring CTR and avoids interference with the original circuit during the measurement process; at the same time, the switching time characteristic parameters introduced in this invention t r The data acquisition and characterization are based on the performance degradation conditions of the optocoupler under real switching operating modes, and the lifetime assessment model is established in the actual working environment, thus it can more accurately reflect the health status of the optocoupler under specific conditions.

[0009] The technical solution adopted in this invention is as follows:

[0010] A method for assessing the health status of optocouplers based on switching time characteristic parameters is proposed. The optocouplers are installed in a relay protection board, and the switching time characteristic parameters of the optocouplers are... t r The health status of the optocoupler is assessed using aging-sensitive parameters; wherein the optocoupler health status assessment method includes:

[0011] Pre-calibrate switching time characteristic parameters tr The mapping relationship between CTR;

[0012] An edge detection module is installed in the relay protection board. When the optocoupler is in online operation, the switching time characteristic parameters of the optocoupler are detected and calculated. t r The online real-time detection value; based on pre-calibrated switching time characteristic parameters. t r The mapping relationship between the optical coupler and the CTR is used to calculate the online real-time value of the CTR corresponding to the optical coupler;

[0013] The health status of the optocoupler is assessed by analyzing the change in the real-time online CTR value of the optocoupler over its online operating time.

[0014] Among them, the switching time characteristic parameter t r This refers to the voltage difference between the output collector and the output emitter of an optocoupler during the conduction process. V CE The edge fall time; the CTR refers to the collector current of the optocoupler on its output side. I C Its input current on the input side I F The ratio of .

[0015] Preferably, the switching time characteristic parameter t r This refers to the voltage difference V between the output collector and the output emitter of an optocoupler during the conduction process. CE The edge ranges from 100-85%V CE Decreased to 15-0% V CE The preferred time is from 95-90% V CE Decrease to 10-5% V CE The time.

[0016] Preferably, the calibration switching time characteristic parameter t r The mapping relationship between CTR and other data includes the following steps:

[0017] S11. Select the optocoupler as the calibration sample. With the optocoupler offline, measure and record its switching time characteristic parameters in the initial healthy state. t r Initial values ​​and CTR initial values;

[0018] S12. Apply temperature stress to the calibration sample at fixed time intervals according to step S11 above.

[0019] The process involves measuring and recording the switching time characteristic parameters at time t. t r The CTR value and CTR value are monitored until an optocoupler failure is detected, whereby an optocoupler failure is defined as a measured CTR value lower than the set minimum CTR value.

[0020] S13. Calculate the switching time characteristic parameters corresponding to each time t obtained in step S20 above. t r The values ​​and CTR values ​​are normalized and converted into switching time characteristic parameters relative to those in step S11 above. t r The formula for normalizing the initial values ​​and the rate of change of the initial CTR values ​​is as follows:

[0021] ;

[0022] ;

[0023] Where ΔCTR(t) is the rate of change of CTR at time t, CTR(t) is the CTR value of the record corresponding to time t, and CTR(0) is the initial value of CTR; Δ t r ( t (This is a time interval) t r rate of change t r ( t ) represents the switching time characteristic parameter recorded at time t. t r Value, t r (0) is a switching time characteristic parameter t r Initial value;

[0024] S14. Based on each ΔCTR(t) data and Δ t r ( t Data, in CTR change rate and t r Establish a suitable mapping formula model between the rates of change.

[0025] Preferably, in step S11, the switching time characteristic parameter t r The process of measuring and recording initial values ​​includes:

[0026] During the initial healthy conduction process of the optocoupler, the voltage difference between its output collector and its output emitter is measured and recorded. V CE The edge fall time;

[0027] The process of measuring and recording the initial value of CTR includes: providing an input current I to the input side of the optocoupler. F Measure the collector current on the output side of the optocoupler. I C According to the formula: CTR=( I C / I F )×100%, obtain the initial CTR value of the optocoupler and record it.

[0028] Preferably, in step S12, a temperature stress is applied to the calibration sample using a temperature chamber or a self-heating method, wherein 70-90% of the maximum allowable operating temperature corresponding to the calibration sample is taken as the temperature stress.

[0029] Preferably, in step S14, the mapping formula model adopts the following linear formula model:

[0030] ;in, k Here, ε is the correlation coefficient, and ε is the compensation amount.

[0031] Based on the measured data, the least squares method was used for fitting. k and ε Cross-validation was used to ensure that the relative error of the fitted model was less than 5%, and the goodness of fit R0 was [value missing]. 2 >0.9.

[0032] Preferably, the edge detection module includes a voltage signal conditioning circuit, a multi-channel ADC sampling chip, an MCU, and an isolated power supply module for power supply; wherein, the voltage signal conditioning circuit converts the voltage difference of the optocoupler... V CE The signal is adjusted to the rated input range of the multi-channel ADC sampling chip, and the voltage difference of the optocoupler is acquired by the ADC sampling chip. V CE The signal waveform is then used by the MCU to calculate the switching time characteristic parameters of the optocoupler. t r The online real-time detection value.

[0033] Preferably, the edge detection module is installed separately or integrated into the relay protection board; the edge detection module also includes a human-machine interface module that communicates with the MCU, through which the switching time characteristic parameters are transmitted. t r The online real-time detection values ​​are displayed.

[0034] Preferably, the process of assessing the health status of the optocoupler based on the change of the online real-time CTR value corresponding to the optocoupler with the online running time of the optocoupler includes:

[0035] The switching time characteristic parameters of the optocoupler are acquired and calculated by the edge detection module at fixed time intervals. t r The online real-time detection values ​​are recorded based on pre-calibrated switching time characteristic parameters. t r The mapping relationship between the optical coupler and the CTR is used to calculate the online real-time value of the CTR corresponding to the optical coupler;

[0036] The number of failed optocouplers at each acquisition time is counted, and a statistical table of the number of failed optocouplers at each acquisition time is generated. The failed optocoupler refers to the optocoupler whose calculated CTR value in real time is lower than its set minimum CTR value.

[0037] Preferably, the process of assessing the health status of the optocoupler based on the change of its online real-time CTR value with the online operating time of the optocoupler further includes: fitting a two-parameter Weibull distribution model of the optocoupler lifetime according to the following formula:

[0038] ;

[0039] ;

[0040] ;

[0041] Where F(t) is the cumulative failure percentage of the optical coupler at acquisition time t, R(t) is the reliability function of the optical coupler at acquisition time t; β is the shape parameter, which determines the shape characteristics of the distribution; and η is the scale parameter, which represents the characteristic lifetime corresponding to this specific working condition.

[0042] The F(t) is obtained using the median rank method. Where i is the number of newly failed optocouplers within the cumulative failure time, and n is the total number of test optocoupler samples; the shape parameters are obtained by linearly fitting the two-parameter Weibull distribution model curve. β Scale parameters η and optical coupler reliability function R ( t );

[0043] The lifetime of the optocouplers under different online operating times is evaluated based on the online real-time CTR value of the optocoupler and its corresponding optocoupler reliability function R(t).

[0044] This invention creatively introduces a switching time characteristic parameter. t r(During the conduction process of the optocoupler, the voltage difference between its output collector and its output emitter) V CE The edge fall time was used as an aging-sensitive parameter for assessing the health status of optocouplers. An edge detection module was proposed to be installed in the relay protection board to collect the switching time characteristic parameters of the optocouplers. t r The online real-time detection value, and based on pre-calibrated switching time characteristic parameters. t r The online real-time value of the CTR corresponding to the optocoupler is calculated by mapping the relationship between the optocoupler and the CTR, thereby realizing the lifetime (health status) assessment of the optocoupler. This avoids the complex measurement process of directly measuring the CTR and avoids interference with the original circuit during the measurement process. At the same time, the switching time characteristic parameter introduced in this invention... t r The data acquisition and characterization are based on the performance degradation conditions of the optocoupler under the actual switching operation mode, and the lifetime assessment model is established in the actual working environment, thus it can more accurately reflect the health status of the optocoupler device under specific conditions.

[0045] Furthermore, this invention only requires calibration of the switching time characteristic parameters once. t r By mapping the relationship with CTR, the online real-time value of CTR and the establishment of life model for the optocoupler under various operating conditions can be realized, avoiding the complicated subsequent shutdown, disassembly and measurement work. Attached Figure Description

[0046] Figure 1 These are the switching time characteristic parameters of the optocoupler in the specific embodiments of this application. t r A schematic diagram;

[0047] Figure 2 This is a schematic diagram of the edge detection module according to a specific embodiment of this application;

[0048] Figure 3 This is a schematic diagram of the experimental platform under a specific implementation of this application;

[0049] Figure 4 The initial voltage difference is measured by the experimental platform under the specific implementation method of this application. V CE Time-domain waveform diagram; Detailed Implementation

[0050] This embodiment provides a method for assessing the health status of an optocoupler based on its switching time characteristic parameters. The optocoupler is installed in a relay protection board, and its switching time characteristic parameters are... t rThe optocoupler health status is assessed using aging-sensitive parameters; the optocoupler health status assessment method includes: pre-calibrating switching time characteristic parameters. t r The mapping relationship between the optocoupler and the CTR; an edge detection module is installed in the relay protection board. When the optocoupler is in online operation, the switching time characteristic parameters of the optocoupler are detected and calculated. t r The online real-time detection value; based on pre-calibrated switching time characteristic parameters. t r The mapping relationship between the optocoupler and the CTR is used to calculate the online real-time value of the optocoupler; the health status of the optocoupler is assessed based on the change of the online real-time value of the optocoupler with the online operating time of the optocoupler; among which, the switching time characteristic parameter t r This refers to the voltage difference between the output collector and the output emitter of an optocoupler during the conduction process. V CE The edge fall time; CTR refers to the collector current of the optocoupler on its output side. I C Its input current on the input side I F The ratio of .

[0051] Preferably, in this embodiment, the switching time characteristic parameter t r This refers to the voltage difference V between the output collector and the output emitter of an optocoupler during the conduction process. CE The edge ranges from 100-85%V CE Decreased to 15-0% V CE The preferred time is from 95-90% V CE Decrease to 10-5% V CE The time; please refer to the details. Figure 1 As shown, the switching time characteristic parameters t r This refers to the voltage difference V between the output collector and the output emitter of an optocoupler during the conduction process. CE The edge from 90%V CE Decreased to 10% V CE Time;

[0052] Preferably, in this embodiment, the calibrated switching time characteristic parameters are... t r The mapping relationship between CTR and other data includes the following steps:

[0053] S11. Select the optocoupler as the calibration sample. With the optocoupler offline, measure and record its switching time characteristic parameters in the initial healthy state. t r Initial values ​​and CTR initial values; preferably, in this step S11, the switching time characteristic parameters t r The process of measuring and recording initial values ​​includes:

[0054] During the initial healthy conduction process of the optocoupler, the voltage difference between its output collector and its output emitter is measured and recorded. V CE The edge fall time;

[0055] The process of measuring and recording the initial value of CTR includes: providing an input current I to the input side of the optocoupler. F Measure the collector current on the output side of the optocoupler. I C According to the formula: CTR=( I C / I F )×100% to obtain and record the initial CTR value of the optocoupler;

[0056] S12. Apply temperature stress to the calibration sample and measure and record its switching time characteristic parameters at time t at fixed time intervals, following the process described in step S11 above. t r The value and CTR value are measured until the optocoupler failure is found. Optocoupler failure means that the measured CTR value is lower than the set minimum CTR value. Preferably, in this step S12, temperature stress is applied to the calibration sample by using a temperature chamber or self-heating method. Specifically, preferably, 70-90% of the maximum allowable operating temperature of the calibration sample is used as the temperature stress.

[0057] S13. Calculate the switching time characteristic parameters corresponding to each time t obtained in step S20 above. t r The values ​​and CTR values ​​are normalized and converted into switching time characteristic parameters relative to those in step S11 above. t r The formula for normalizing the initial values ​​and the rate of change of the initial CTR values ​​is as follows:

[0058] ;

[0059] ;

[0060] Where ΔCTR(t) is the rate of change of CTR at time t, CTR(t) is the CTR value of the record corresponding to time t, and CTR(0) is the initial value of CTR; Δ t r ( t (This is a time interval) t r rate of change t r ( t ) represents the switching time characteristic parameter recorded at time t. t r Value, t r (0) is a switching time characteristic parameter t r Initial value;

[0061] S14. Based on each ΔCTR(t) data and Δ t r ( t Data, in CTR change rate and t r Establish a suitable mapping formula model between the rates of change.

[0062] Preferably, in step S14, the mapping formula model adopts the following linear formula model:

[0063] ;in, k Here, ε is the correlation coefficient, and ε is the compensation amount.

[0064] Based on the measured data, the least squares method was used for fitting. k and ε Cross-validation was used to ensure that the relative error of the fitted model was less than 5%, and the goodness of fit R0 was [value missing]. 2 >0.9.

[0065] Preferably, please refer to Figure 2 As shown, in this embodiment, the edge detection module includes a voltage signal conditioning circuit (…). Figure 2 Labeled as "voltage conditioning circuit," capable of simultaneously inputting switching signals from multiple sets of input optocouplers; multi-channel ADC sampling chip ( Figure 2 The chip is labeled "ADC sampling chip"), the MCU, and the isolated power supply module for power supply. Figure 2 (labeled as "power module"); where the voltage difference of the optocoupler is conditioned by a voltage signal conditioning circuit. V CE The signal is adjusted to the rated input range of the multi-channel ADC sampling chip, and the voltage difference of the optocoupler is acquired through the ADC sampling chip. V CE The signal waveform is then used by the MCU to calculate the switching time characteristic parameters of the optocoupler.t r The online real-time detection value; more preferably, in this embodiment, the edge detection module is separately or integrated into the relay protection board; the edge detection module also includes a human-machine interaction module that communicates with the MCU, through which the switching time characteristic parameters are transmitted. t r The online real-time detection values ​​are displayed.

[0066] Preferably, in this embodiment, the process of assessing the health status of the optocoupler based on the change of the online real-time CTR value corresponding to the optocoupler with the online running time of the optocoupler includes:

[0067] The switching time characteristic parameters of the optocoupler are obtained by collecting and calculating data through the edge detection module at fixed time intervals. t r The online real-time detection values ​​are recorded based on pre-calibrated switching time characteristic parameters. t r The mapping relationship between the optical coupler and the CTR is used to calculate the online real-time value of the CTR corresponding to the optical coupler;

[0068] The number of failed optocouplers at each acquisition time is counted, and a statistical table of the number of failed optocouplers at each acquisition time is generated. A failed optocoupler is one whose calculated CTR value in real time is lower than its set minimum CTR value.

[0069] The two-parameter Weibull distribution model of the optocoupler lifetime is fitted according to the following formula:

[0070] ;

[0071] ;

[0072] ;

[0073] Where F(t) is the cumulative failure percentage of the optical coupler at acquisition time t, R(t) is the reliability function of the optical coupler at acquisition time t; β is the shape parameter, which determines the shape characteristics of the distribution; and η is the scale parameter, which represents the characteristic lifetime corresponding to this specific working condition.

[0074] F(t) is obtained using the median-rank method. Where i is the number of newly failed optocouplers within the cumulative failure time, and n is the total number of test optocoupler samples; the shape parameters are obtained by linearly fitting the two-parameter Weibull distribution model curve. β Scale parameters η and optical coupler reliability function R ( t );

[0075] The lifetime of the optocouplers under different online operating times is evaluated based on the online real-time CTR value of the optocoupler and its corresponding optocoupler reliability function R(t).

[0076] To enable those skilled in the art to better understand the technical solutions of this invention, based on the above embodiments, the following specific embodiments will be proposed in conjunction with the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort should fall within the scope of protection of this invention.

[0077] Please see Figure 3 The experimental platform shown uses ON Semiconductor MOC8050M as the optocoupler sample; AD7606 as the multi-channel ADC sampling chip for the voltage edge detection device (i.e., the "edge detection module"); STM32 minimum system board as the MCU; RCS-941A as the relay protection board; and a constant temperature chamber to apply temperature stress to the calibration sample.

[0078] Pre-calibrated switching time characteristic parameters t r When mapping the relationship with the CTR, the voltage difference between its output collector and its output emitter is measured and recorded using an oscilloscope. V CE The edge fall time completes the switching time characteristic parameters. t r Initial value measurement and recording; the CTR initial value is measured and recorded in the optocoupler offline state, specifically by providing input current to the optocoupler input side. I F The corresponding input voltage is V F Output side voltage difference V CE Measure the collector current on the output side of the optocoupler. I C According to the formula: CTR=( I C / I F )×100% to obtain and record the initial CTR value of the optocoupler;

[0079] At room temperature, a switching signal is applied to the optocoupler sample (i.e., the calibration sample in this embodiment), and the initial voltage difference is measured. V CE Time-domain waveforms such as Figure 4As shown (each horizontal division (div) represents 0.5 milliseconds, meaning each grid on the horizontal axis spans 0.5 ms; each vertical division (div) represents 4 volts, meaning each grid on the vertical axis spans 4 V), recording the switching time characteristic parameters. t r Initial values; simultaneously measure and record the initial CTR values ​​offline;

[0080] Then, an accelerated aging test was conducted on the optocoupler samples under temperature stress. The optocoupler samples were placed in a constant temperature chamber at 85°C and continuously powered on. Measurements were recorded every 100 hours. V CE Waveform and record t r ( t Then, offline measurements are taken and CTR(t) is recorded until the CTR(t) is lower than the minimum CTR value specified in the instruction manual (i.e., the "set minimum CTR value" as described throughout this application), which indicates that the optocoupler has failed; for each t r ( t The data and CTR(t) data are normalized according to the scheme described in the above embodiment to finally generate Δ. t r The corresponding table for ΔCTR changes is shown in Table 1:

[0081]

[0082] Fitting the linear formula model using the least squares method: , obtain parameters k =-0.402, ε= 0.015, which determines the rate of change of CTR and t r The mapping formula model between the rates of change is as follows: .

[0083] Install the voltage edge detection device on the relay protection board, ensure the equipment is in normal working condition, and record the voltage difference every 50 hours. V CE Corresponding switching time characteristic parameters t r The online real-time detection value, and based on the CTR change rate and t r The mapping formula model between the rates of change was used to statistically analyze the number of failed optocouplers at each acquisition time t, generating a statistical table of the number of failed optocouplers at each acquisition time t. The total number of experimental optocoupler samples was 80, as shown in Table 2 below:

[0084]

[0085] Obtained using the median rank method F ( t The shape parameters in the two-parameter Weibull distribution model are obtained by linearly fitting the curve of the optocoupler lifetime to the two-parameter Weibull distribution model. β= 0.7108, scale parameter η= 6373.43, yielding the reliability function R(t):

[0086] ;

[0087] The lifetime of the optocoupler is evaluated based on its online real-time CTR value and its corresponding optocoupler reliability function R(t) at different online operating times. A specific example of the lifetime evaluation process in this embodiment is shown below:

[0088] An optocoupler has an initial CTR value of 150%, while its manual specifies a minimum CTR value (i.e., the "set minimum CTR value") of 100%. Therefore, when the edge detection module measures the switching time characteristic parameters of this optocoupler... t r It has changed by 15% from its initial value, i.e., Δ t r =15, then through the mapping formula model, it can be seen that the CTR of the optocoupler has decreased by 6.015%, that is, the CTR of the optocoupler at this time is about 141%, so the optocoupler still has a high CTR and its health status is good. In addition, the cumulative working time t of the optocoupler and its reliability function R(t) are combined to further judge the current operational reliability of the optocoupler. For example, if the optocoupler has been working for 128 hours, then R(128)=0.94, which means that the reliability of the optocoupler is currently at a high level and can continue to be used. When the R(t) of the optocoupler is less than 0.9, it can be said that the reliability of the optocoupler is low and the optocoupler can be replaced. In implementation, the specific reliability threshold R(t) can be adjusted in accordance with the actual reliability requirements of the system. These are conventional technical choices that can be made by those skilled in the art based on the content of this application, and no creative effort is required.

[0089] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0090] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for assessing the health status of an optocoupler based on switching time characteristic parameters, wherein the optocoupler is installed in a relay protection board, characterized in that... The switching time characteristic parameter t of the optocoupler r The health status of the optocoupler is assessed using aging-sensitive parameters; wherein the optocoupler health status assessment method includes: Pre-calibrate the switching time characteristic parameter t r The mapping relationship between the rate of change and the CTR rate of change; An edge detection module is installed in the relay protection board. When the optocoupler is in online operation, the switching time characteristic parameter t of the optocoupler is detected and calculated. r The online real-time detection value; based on the pre-calibrated switching time characteristic parameter t r The mapping relationship between the rate of change and the CTR rate of change was used to calculate the online real-time value of the CTR corresponding to the optocoupler. The health status of the optocoupler is assessed by analyzing the change in the real-time online CTR value of the optocoupler over its online operating time. Wherein, the switching time characteristic parameter t r This refers to the voltage difference V between the output collector and the output emitter of an optocoupler during the conduction process. CE The CTR refers to the edge fall time; the CTR refers to the collector current I of the optocoupler on its output side. C Its input current I on the input side F The ratio of .

2. The method for assessing the health status of an optical coupler based on switching time characteristic parameters according to claim 1, characterized in that, The switching time characteristic parameter t r This refers to the voltage difference V between the output collector and the output emitter of an optocoupler during the conduction process. CE The edge ranges from 100-85%V CE Decreased to 15-0% V CE The time.

3. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 1, characterized in that, The switching time characteristic parameter t r This refers to the voltage difference V between the output collector and the output emitter of an optocoupler during the conduction process. CE The edge is from 95-90% V CE Decrease to 10-5% V CE The time.

4. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 1, characterized in that, The calibration switching time characteristic parameter t r The mapping relationship between the rate of change and the CTR rate of change includes the following steps: S11. Select the optocoupler as the calibration sample. With the optocoupler offline, measure and record its switching time characteristic parameter t in the initial healthy state. r Initial values ​​and CTR initial values; S12. Apply temperature stress to the calibration sample at fixed time intervals according to step S11 above. The process described above measures and records the switching time characteristic parameter t at time t. r The CTR value and CTR value are monitored until an optocoupler failure is detected, whereby an optocoupler failure is defined as a measured CTR value lower than the set minimum CTR value. S13. The switching time characteristic parameter t corresponding to each time t obtained in step S12 above. r The values ​​and CTR values ​​are normalized and converted into the switching time characteristic parameter t relative to the above step S11. r The formula for normalizing the initial values ​​and the rate of change of the initial CTR values ​​is as follows: ； ； Where ΔCTR(t) is the rate of change of CTR at time t, CTR(t) is the CTR value of the record corresponding to time t, and CTR(0) is the initial value of CTR; Δt r (t) represents time t at a certain time. r rate of change, t r (t) represents the switching time characteristic parameter t recorded at time t. r Value, t r (0) represents the switching time characteristic parameter t. r Initial value; S14. Based on each ΔCTR(t) data and Δt r (t) data, in the relationship between the rate of change of CTR and t r Establish a suitable mapping formula model between the rates of change.

5. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 4, characterized in that, In step S11, the switching time characteristic parameter t r The process of measuring and recording initial values ​​includes: During the initial healthy conduction process of the optocoupler, the voltage difference V between its output collector and its output emitter is measured and recorded. CE The edge fall time; The process of measuring and recording the initial value of CTR includes: providing an input current I to the input side of the optocoupler. F Measure the collector current I on the output side of the optocoupler. C According to the formula: CTR=(I C / I F )×100%, obtain the initial CTR value of the optocoupler and record it.

6. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 4, characterized in that, In step S12, temperature stress is applied to the calibration sample using a temperature chamber or self-heating method, wherein 70-90% of the maximum allowable operating temperature of the calibration sample is taken as the temperature stress.

7. The method for assessing the health status of an optical coupler based on switching time characteristic parameters according to claim 4, characterized in that, In step S14, the mapping formula model adopts the following linear formula model: Where k is the correlation coefficient and ε is the compensation amount; Based on the measured data, k and ε were fitted using the least squares method. Cross-validation was used to ensure that the relative error of the fitted model was less than 5%, and the goodness of fit R0 was [value missing]. 2 > 0.

9.

8. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 1, characterized in that, The edge detection module includes a voltage signal conditioning circuit, a multi-channel ADC sampling chip, an MCU, and an isolated power supply module for power supply; wherein, the voltage signal conditioning circuit converts the voltage difference V of the optocoupler... CE The signal is adjusted to the rated input range of the multi-channel ADC sampling chip, and the voltage difference V of the optocoupler is acquired by the ADC sampling chip. CE The signal waveform is then used by the MCU to calculate the switching time characteristic parameter t of the optocoupler. r The online real-time detection value.

9. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 8, characterized in that, The edge detection module is either separately or integrated into the relay protection board; The edge detection module also includes a human-machine interface module that communicates with the MCU, through which the switching time characteristic parameter t is transmitted. r The online real-time detection values ​​are displayed.

10. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 1, characterized in that, The process of assessing the health status of an optocoupler based on the change in its online real-time CTR value over its online operating time includes: The switching time characteristic parameter t corresponding to the optocoupler is obtained by the edge detection module at fixed time intervals. r The online real-time detection value is recorded based on the pre-calibrated switching time characteristic parameter t. r The mapping relationship between the rate of change and the CTR rate of change was used to calculate the online real-time value of the CTR corresponding to the optocoupler. The number of failed optocouplers at each acquisition time is counted, and a statistical table of the number of failed optocouplers at each acquisition time is generated. The failed optocoupler refers to the optocoupler whose calculated CTR value in real time is lower than its set minimum CTR value.

11. The method for assessing the health status of an optocoupler based on switching time characteristic parameters according to claim 10, characterized in that, The process of assessing the health status of an optocoupler based on the change in its online real-time CTR value over its online operating time also includes fitting a two-parameter Weibull distribution model of the optocoupler's lifetime using the following formula: ； ； ； Where F(t) is the cumulative failure percentage of the optical coupler at acquisition time t, R(t) is the reliability function of the optical coupler at acquisition time t; β is the shape parameter, which determines the shape characteristics of the distribution; and η is the scale parameter, which represents the characteristic lifetime corresponding to a specific working condition. The F(t) is obtained using the median rank method. Where i is the number of newly failed optocouplers within the cumulative failure time, and n is the total number of test optocoupler samples; the shape parameter β, the scale parameter η, and the optocoupler reliability function R(t) are obtained by linear fitting the curve of the two-parameter Weibull distribution model. The lifetime of the optocouplers under different online operating times is evaluated based on the online real-time CTR value of the optocoupler and its corresponding optocoupler reliability function R(t).

Images