Isolated common-cathode current circuit and isolated common-cathode current circuit test method

Abstract

The invention discloses an isolated common-cathode current circuit and an isolated common-cathode current circuit testing method, and relates to the technical field of circuit testing, and the method comprises the steps: inputting a pulse width modulation signal to a digital isolation circuit for testing, and obtaining the circuit testing data of the isolated common-cathode current circuit; calculating a current attenuation coefficient of each branch based on current data in the circuit test data; extracting abnormal data points of the pulse width modulation signal in the test process, and calculating the influence degree value of the ripple voltage on each branch based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points; and determining an isolation effect evaluation value of the isolated common-cathode current circuit based on the influence degree value and the current attenuation coefficient. The technical effect of accurately testing the circuit isolation degree is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of circuit testing, and in particular to an isolated common cathode current circuit and an isolated common cathode current circuit testing method. Background Art

[0002] The isolated common cathode circuit is the core technology for achieving signal isolation and transmission in industrial automation systems. It is mainly used to convert the physical quantities collected by sensors into standard 4-20mA current signals. Traditional isolated common cathode output circuits are generally implemented using isolation components such as isolated power supplies and optocouplers. However, traditional isolated common cathode circuit testing methods only assess single factors such as temperature or vibration, and lack composite testing capabilities. Under the synergistic effect of strong electromagnetic fields and high temperatures, the magnetic permeability of the magnetic core material in the circuit decreases, resulting in the attenuation of the isolation barrier effectiveness and the deterioration of the circuit isolation effect. The accurate circuit isolation effect cannot be detected by relying solely on traditional single voltage withstand tests. Summary of the Invention

[0003] The main purpose of this application is to provide an isolated common cathode current circuit and an isolated common cathode current circuit testing method, aiming to solve the technical problem in related technologies that accurate circuit isolation effect cannot be detected by relying solely on traditional single withstand voltage testing.

[0004] To achieve the above objectives, embodiments of the present application provide an isolated common-cathode current circuit and an isolated common-cathode current circuit testing method, which are applied to the isolated common-cathode current circuit. The isolated common-cathode current circuit includes a digital isolation circuit and a current output module. The digital isolation circuit and the current output module are electrically connected, including: Inputting a pulse width modulated signal into a digital isolation circuit for testing and obtaining circuit test data of an isolated common cathode current circuit; Based on the current data in the circuit test data, the current attenuation coefficient of each branch is calculated; Extract abnormal data points of the pulse width modulation signal during the test process, and calculate the degree of influence of the ripple voltage on each branch based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points; Based on the impact degree value and the current attenuation coefficient, an isolation effect evaluation value of the isolated common cathode current circuit is determined.

[0005] In a possible implementation of the present application, after calculating the current attenuation coefficient of each branch based on the current data in the circuit test data, the method further includes: Perform clustering processing on the current data corresponding to each branch to obtain current clustering data; Based on the current attenuation coefficient and current clustering data, the current fluctuation degree of each branch is calculated; Based on the degree of current fluctuation on different branches, the current response weight is calculated; Based on the number of data points corresponding to the abnormal data point and the signal fluctuation difference value of the abnormal data point, the degree of influence of the ripple voltage on each branch is calculated, including: Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point, the degree of influence of the ripple voltage on each branch is calculated.

[0006] In a possible implementation of the present application, the current response weight is calculated based on the degree of current fluctuation on each different branch, including: Determining a first number of electronic components on different branches and a maximum value of fluctuations in each current fluctuation degree; A current response weight is calculated based on the current fluctuation degree, the fluctuation maximum value, and the first quantity.

[0007] In one possible implementation of the present application, the signal fluctuation difference value includes a signal amplitude. Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point, the degree of influence of the ripple voltage on each branch is calculated, including: Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal amplitude of each abnormal data point, the degree to which each branch is affected by the ripple voltage is calculated.

[0008] In a possible implementation of the present application, extracting abnormal data points of a pulse width modulation signal during a test process includes: Decomposing the pulse width modulation signal by a preset decomposition algorithm to obtain a decomposed signal; Extract the trend item data sequence from the decomposed signal, and obtain abnormal data points in the trend item data sequence.

[0009] In a possible implementation of the present application, the signal fluctuation difference value is the difference between the signal amplitude of each abnormal data point and the signal amplitude mean of the trend item data sequence, and the signal fluctuation difference value is proportional to the degree of interference of the pulse width modulation signal by the ripple voltage.

[0010] In a possible implementation of the present application, the current attenuation coefficient of each branch is calculated based on the current data in the circuit test data, including: For any branch, determining an initial current value and a first current value at a preset position of the circuit branch based on current data in the circuit test data; Calculating the current transmission time between the position corresponding to the initial current value and the preset position; Based on the initial current value, the first current value, and the current transmission time, the current attenuation coefficient of each branch is calculated.

[0011] In a possible implementation of the present application, determining an isolation effect evaluation value of an isolated common cathode current circuit based on an impact degree value and a current attenuation coefficient includes: Based on the impact degree value, the current attenuation coefficient is corrected to obtain a corrected current attenuation coefficient; Based on the corrected current attenuation coefficient, an isolation effect evaluation value of the isolated common cathode current circuit is determined.

[0012] In a possible implementation of the present application, determining an isolation effect evaluation value of the isolated common cathode current circuit based on the corrected current attenuation coefficient includes: Obtain the number of branches of the isolated common cathode current circuit, and calculate the sum of the values ​​of the corrected current attenuation coefficients in each branch; Based on the numerical value and the number of branches, the isolation effect evaluation value of the isolated common cathode current circuit is calculated.

[0013] To achieve the above-mentioned purpose, an embodiment of the present application provides an isolated common cathode current circuit, which includes a digital isolation circuit, a filter circuit, a constant current circuit and a current output module. The digital isolation circuit, the filter circuit, the constant current circuit and the current output module are electrically connected in sequence. The digital isolation circuit flips the received pulse width modulation signal and transmits the flipped pulse width modulation signal to the current output module through the filter circuit and the constant current circuit.

[0014] The present application provides an isolated common cathode current circuit and an isolated common cathode current circuit testing method. Compared with the related art, the traditional isolated common cathode circuit testing method only evaluates a single factor of temperature or vibration, lacks composite testing capabilities, and under the synergistic effect of strong electromagnetic fields and high temperatures, the magnetic permeability of the core material decreases, resulting in the attenuation of the isolation barrier performance and the deterioration of the circuit isolation effect. The traditional single withstand voltage test alone cannot detect the accurate circuit isolation effect. In this application, a pulse width modulation signal is input into the digital isolation circuit in the isolated common cathode current circuit, and circuit test data of the isolated common cathode current circuit is obtained. The current data in the test data is used to calculate the current attenuation coefficient of each branch in the circuit, and then the degree of influence of the ripple voltage on each branch is calculated based on the abnormal data points of the pulse width modulation signal in the input circuit. Then, the isolation effect evaluation value of the isolated common cathode current circuit is determined through the influence degree value of each branch and the current attenuation coefficient. When evaluating the isolation effect, it is necessary to evaluate the isolation effect of the entire isolation circuit. Therefore, the isolation effect of the circuit can be determined by the current attenuation coefficient of each branch in the circuit. Finally, according to the calculated isolation effect evaluation value, the accurate isolation effect of the isolated common cathode current circuit is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a flow chart of a first embodiment of the isolated common cathode current circuit testing method of the present application; Figure 2 This is a simplified schematic diagram of the signal inversion circuit involved in the isolated common cathode current circuit testing method of this application; Figure 3 This is a flow chart of a second embodiment of the isolated common cathode current circuit testing method of the present application; Figure 4 This is a simplified external wiring diagram of a traditional isolated common cathode circuit involved in the embodiment of the present application; Figure 5 This is a simplified external wiring diagram of an improved isolated common cathode circuit involved in the isolated common cathode current circuit testing method of this application; Figure 6 This is a simplified schematic diagram of the principle of the digital isolation chip involved in the isolated common cathode current circuit testing method of this application; Figure 7 This is a schematic diagram of the device structure of the hardware operating environment involved in the embodiment of the present application. DETAILED DESCRIPTION

[0016] It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0017] The present application provides an isolated common cathode current circuit test method. In the first embodiment of the isolated common cathode current circuit test method of the present application, referring to Figure 1 , methods include: Step S10, inputting a pulse width modulation signal into the isolated common cathode current circuit for testing, and obtaining circuit test data of the isolated common cathode current circuit; Step S20, calculating the current attenuation coefficient of each branch based on the current data in the circuit test data; Step S30, extracting abnormal data points of the pulse width modulation signal during the test process, and calculating the degree of influence of the ripple voltage on each branch based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points; Step S40 : determining an isolation effect evaluation value of the isolated common cathode current circuit based on the impact degree value and the current attenuation coefficient.

[0018] This embodiment aims to test and obtain accurate circuit isolation effect.

[0019] The specific steps are as follows: In step S10 , a pulse width modulation signal is inputted into the isolated common cathode current circuit for testing, and circuit test data of the isolated common cathode current circuit is obtained.

[0020] As an example, the isolated common cathode current circuit testing method can be applied to an isolated common cathode current circuit testing device, the isolated common cathode current circuit testing device belongs to an isolated common cathode current circuit testing system, and the isolated common cathode current circuit testing system belongs to an isolated common cathode current circuit testing device.

[0021] As an example, the isolated common cathode current circuit test method can also be applied to the isolated common cathode current circuit. The isolated common cathode current circuit is a circuit structure that has both electrical isolation and current detection functions. Its core feature is to achieve potential isolation between the common cathode current sampling point and the back-end processing circuit through isolation devices such as optocouplers and transformers. The circuit is usually composed of a common cathode connected power device, a shunt resistor, an isolation amplifier / optocoupler and a signal conditioning unit.

[0022] When the main loop current flows through the common cathode node, the shunt resistor converts the current into a voltage signal, which is transmitted to the secondary side through the isolation device, and finally outputs a detection signal that is proportional to the main loop current and has no direct electrical connection.

[0023] This design can not only avoid ground loop interference, but also provide a safe current monitoring solution for high-voltage or floating-ground systems. It is widely used in switching power supplies, motor drives, new energy converters and other occasions.

[0024] As an example, the pulse width modulation signal may be a PWM (pulse width modulation) signal, and the isolated common cathode current circuit is mainly used to convert the PWM signal into a current signal.

[0025] As an example, the circuit test data may be test data generated during the test process, including but not limited to current data at each point in the circuit, the time for current transmission, the amplitude of the PWM signal change, and the average value of each current.

[0026] Specifically, during the testing process, the core architecture includes: Equipment configuration: high temperature electromagnetic coupling test chamber.

[0027] Temperature range: -40℃~150℃, temperature control accuracy ±1℃ (125℃ steady-state test).

[0028] Built-in GTEM cell: generates 80MHz-1GHz continuously swept electromagnetic field with a field strength of 30V / m (IEC 61000-4-3 standard).

[0029] Dynamic load simulator: outputs a 0-1kΩ resistive load and a 100pF capacitive load in parallel (simulating the distributed capacitance of a long cable).

[0030] High-speed data acquisition system: 16-bit ADC, sampling rate 1MSa / s, synchronously collects input / output signals, leakage current and core temperature.

[0031] The test steps include: 1. Place the isolated common cathode current circuit in the test chamber and connect it to the load simulator; 2. Set the temperature to 125°C and stabilize for 30 minutes; 3. Open the GTEM chamber (a device used for electromagnetic compatibility testing) and apply 80MHz-1GHz swept frequency electromagnetic interference (field strength 30V / m); 4. Inject a 500kHz PWM signal (50% duty cycle, 5V amplitude) into the circuit. 5. Run continuously for 300 hours and record data every 10 minutes.

[0032] Step S20, calculating the current attenuation coefficient of each branch based on the current data in the circuit test data; As an example, the current data can be the leakage current data in the circuit. When the leakage current is conducted in the circuit, current loss will occur, and the attenuation degree will be greater as the transmission distance increases. The current data obtained from the test can be used to calculate the attenuation degree of each branch in the isolated current circuit, that is, the current attenuation coefficient.

[0033] The step S20 of the isolated common cathode current circuit test further includes steps S21 to S23, including: Step S21 : for any branch, determining an initial current value and a first current value at a preset position of the circuit branch based on current data in the circuit test data.

[0034] As an example, the initial current value is the current value transmitted at the starting point in the circuit. At this time, the current has not decayed. When the current is transmitted to a certain distance, it will decay.

[0035] As an example, the preset position of the circuit may be the position of the current test point, and the current attenuation degree of the current test point is calculated. Similarly, the first current value is the current value of the current test point obtained by the test.

[0036] Step S22 , calculating the current transmission time between the position corresponding to the initial current value and the preset position.

[0037] As an example, the calculation may be started from the time point at which the current of the circuit starts to transmit, and when the current reaches a preset position, the current transmission time between the two positions is obtained.

[0038] Step S23 , calculating the current attenuation coefficient of each branch based on the initial current value, the first current value, and the current transmission time.

[0039] As an example, the current attenuation coefficient refers to the current loss that occurs during the conduction of leakage current, and the degree of attenuation increases with the increase in transmission distance. Therefore, the attenuation coefficient is obtained based on the change in the initial value and measured value of the leakage current. Its calculation formula is as follows:

[0040] Where, represents the current attenuation coefficient, represents the initial current value, Indicates the current The first current value at the position, Indicates that the current reaches The time required for the current to propagate to the location.

[0041] The simplified schematic diagram of the digital isolation chip in the isolated common cathode current circuit involved in this application is as follows: Figure 6 As shown, Figure 6 The PWM signal PWM_A representing the CPU output is flipped after passing through the digital isolation chip IU1. A first-stage operational amplifier is used to achieve a 4-20mA common cathode output and output the PWM_A' signal.

[0042] There are multiple branches in the isolated common cathode current circuit. Figure 2 Taking the signal inversion circuit in as an example, the circuit where IR2 and ID5 are located is a branch, and the Zth position is the preset position in the branch. The preset positions on a branch can be 1, 2, or more. For example, when the preset position on the branch is 1, such as the Zth position is set at the left line connection point of IR2, the current attenuation coefficient on the branch is calculated based on the initial current value and the first current value of the Zth position. When the preset positions are 2, the average of the current attenuation coefficients calculated at the two positions is used as the current attenuation coefficient of the branch.

[0043] Specifically, by Figure 2 The signal inversion circuit included in the isolated common-cathode current circuit shows that the PWM_A' signal outputs a corresponding negative voltage value through the filter circuit consisting of resistor IR1, capacitor IE1, and IC4. Due to the virtual short principle of op amp IU2, V1 = V2. A voltage difference is formed between V2 and the SGND terminal of diode ID5, generating a current IIR2 = |V2 - SGND| / RIR2 across resistor IR2. Current IIR2 is output to the load circuit through transistor IP1 and diode ID9. This isolated common-cathode current circuit is simple, reliable, highly accurate, low-cost, and highly practical.

[0044] Among them, based on the current data in the circuit test data, after calculating the current attenuation coefficient of each branch, it also includes: Step A1, clustering the current data corresponding to each branch to obtain current cluster data; As an example, the clustering processing method can be to cluster the current data of each branch through a clustering algorithm to obtain multiple clusters of current data, that is, current clustering data. The clustering algorithm is an existing well-known technology and will not be described in detail here.

[0045] Step A2: calculating the current fluctuation degree of each branch based on the current attenuation coefficient and the current clustering data; As an example, the current fluctuation degree of each branch circuit is determined based on the current attenuation coefficient and the current clustering data. The current fluctuation degree may be calculated as follows:

[0046] Where, Indicates the The current fluctuation degree of each branch, Indicates the The current attenuation coefficient of each branch; Indicates the variance of the current mean across all clusters / current clusters.

[0047] The variance of the current mean indicates the difference in current fluctuations between different clusters. The larger the variance, the greater the difference in current values ​​between different clusters. This means that when the leakage current propagates on this branch, the greater the resistance generated, and therefore the greater the degree of current fluctuation.

[0048] Step A3: Calculate the current response weight based on the current fluctuation degree of each branch.

[0049] As an example, the current response weights are calculated based on the current fluctuation degrees of different branches obtained by the above calculation.

[0050] The step A3 of calculating the current response weight based on the current fluctuation degree of each branch includes: Determining a first number of electronic components on different branches and a maximum value of fluctuations in each current fluctuation degree; As an example, for any circuit branch, the number of electronic components on each branch is determined, that is, the first number. The current fluctuation degree has been calculated in the previous step, and the maximum fluctuation data can be extracted from the various current fluctuation degree data.

[0051] A current response weight is calculated based on the current fluctuation degree, the fluctuation maximum value, and the first quantity.

[0052] As an example, the current response weight may be calculated as:

[0053] Where, Indicates the The current response weight of each branch, Indicates the The current fluctuation degree of each branch, Indicates the maximum value of current fluctuation in all branches. Indicates the The first number of electronic components on the branch, norm() represents the linear normalization function.

[0054] As an example, the purpose of calculating the current response weight is to accurately reflect the effects of different branches on current isolation when calculating the current isolation effect evaluation value of the isolated common cathode current circuit.

[0055] Based on the number of data points corresponding to the abnormal data point and the signal fluctuation difference value of the abnormal data point, the degree of influence of the ripple voltage on each branch is calculated, including: Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point, the degree of influence of the ripple voltage on each branch is calculated.

[0056] As an example, ripple voltage is primarily caused by the periodic operation of switching devices in the power supply system, the characteristics of nonlinear components, and inadequate filtering circuit processing. When a switch tube (such as a MOSFET) switches rapidly, sudden current changes trigger fluctuations in the inductor's magnetic field. The unidirectional conduction characteristics of the rectifier diode lead to pulsating DC output, while the equivalent series resistance (ESR) of the filter capacitor and the parasitic parameters of the inductor weaken the ability to suppress high-frequency noise. In addition, factors such as sudden load changes, input voltage fluctuations, and parasitic inductance in the PCB layout further exacerbate the residual AC component, ultimately forming periodic fluctuations superimposed on the stable voltage at the DC output.

[0057] As an example, high-frequency ripple will be superimposed on the signal to be measured, generating waveform distortion collected by instruments such as oscilloscopes, especially significantly affecting the monitoring of weak signals at the microvolt level. Secondly, ripple will interfere with the accuracy of the reference voltage source through power supply coupling, causing periodic deviations in the measurement results of key components such as ADCs (analog-to-digital converters). Therefore, the interference caused by the ripple voltage needs to be corrected.

[0058] Specifically, the time difference between the rising and falling edges of the PWM signal is measured. If the deviation is large, it is determined that the digital isolation chip bandwidth is insufficient or electromagnetic interference causes signal jitter. Moreover, because different currents pass through different branches, the impact of the generated ripple voltage varies, and the degree of isolation of the current also varies.

[0059] The signal fluctuation difference value includes the signal amplitude. Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point, the degree of influence of the ripple voltage on each branch is calculated, including: Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal amplitude of each abnormal data point, the degree to which each branch is affected by the ripple voltage is calculated.

[0060] As an example, abnormal data points are abnormal data points in the PWM test signal. At these data points, due to the influence of ripple voltage, the data sequence will be unstable, and there will be a large difference between the signal amplitude and the signal amplitude mean. In addition, the current response weight can reflect the effect of different branches on current isolation. Therefore, the current response weight is used as one of the data variables for calculating the impact value.

[0061] Among them, the abnormal data points of the pulse width modulation signal during the test are extracted, including: Decomposing the pulse width modulation signal by a preset decomposition algorithm to obtain a decomposed signal; As an example, the preset decomposition algorithm can be an STL algorithm. The PWM signal is decomposed by the STL algorithm to obtain a corresponding decomposition signal, which includes: a periodic term, a trend term and a residual term; the periodic term reflects the regularly repeated fluctuation pattern in the data; the trend term represents the slow and continuous change direction in the signal; the residual term includes random fluctuations or sudden events that cannot be explained by the period and trend.

[0062] Extract the trend item data sequence from the decomposed signal, and obtain abnormal data points in the trend item data sequence.

[0063] As an example, by obtaining a trend item data sequence, the abnormal data points in the trend item data sequence are obtained through the LOF algorithm, wherein the LOF algorithm is an existing well-known technology and will not be described in detail here; if the trend item is more unstable and the abnormality of the abnormal data point is greater, then the PWM signal of the current branch is more affected.

[0064] Step S30 , extracting abnormal data points of the pulse width modulation signal during the test process, and calculating the degree of influence of the ripple voltage on each branch based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points.

[0065] As an example, the calculation formula for the impact value can be:

[0066] Where, Indicates the The degree to which each branch is affected by the ripple voltage, represents the current response weight, The autocorrelation coefficient represents the trend term. The autocorrelation coefficient represents the stationarity of a data series. The less stationary it is, the larger the autocorrelation coefficient is. Indicates the The trend item of the branch The signal amplitude of the abnormal data point, Indicates the The mean signal amplitude of the trend item of the branches; Indicates the The number of abnormal data points in the trend item of the branch, Indicates the difference in signal fluctuations between abnormal data points.

[0067] The signal fluctuation difference value is the difference between the signal amplitude of each abnormal data point and the signal amplitude mean of the trend item data sequence. The signal fluctuation difference value is proportional to the degree of interference of the pulse width modulation signal by the ripple voltage.

[0068] As an example, It is the difference between the amplitude of the abnormal data point and the mean value of the trend item sequence. If the signal fluctuation difference value is larger, it means that the obtained value is the difference between the amplitude of the abnormal data point and the mean value of the trend item sequence. If the signal fluctuation difference value is larger, it means that the obtained value is the difference between the amplitude of the abnormal data point and the mean value of the trend item sequence. If the signal fluctuation difference value is larger, it means that the obtained value is more interfered with by the ripple voltage by the PWM signal. That is, the signal fluctuation difference value is proportional to the interference degree of the pulse width modulation signal by the ripple voltage.

[0069] Step S40 : determining an isolation effect evaluation value of the isolated common cathode current circuit based on the impact degree value and the current attenuation coefficient.

[0070] As an example, after calculating the impact degree value, the current attenuation coefficient is corrected based on the impact degree value, and the isolation effect of the entire circuit is evaluated according to the corrected current attenuation coefficient, and then the isolation effect evaluation value of the isolated common cathode current circuit is determined. The isolation effect evaluation value is used to evaluate the isolation degree of the entire isolation circuit. The larger the isolation effect evaluation value, the better the isolation effect on the current.

[0071] The present application provides an isolated common cathode current circuit testing method. Compared with the related art, the traditional isolated common cathode circuit testing method only evaluates a single factor of temperature or vibration, lacks composite testing capabilities, and under the synergistic effect of strong electromagnetic field and high temperature, the magnetic permeability of the core material decreases, resulting in the attenuation of the isolation barrier performance and the deterioration of the circuit isolation effect. In contrast, the traditional single withstand voltage test alone cannot detect the accurate circuit isolation effect. In the present application, a pulse width modulation signal is input into the isolated common cathode current circuit, and circuit test data of the isolated common cathode current circuit is obtained. The current data in the circuit test data is used to , calculate the current attenuation coefficient of each branch in the circuit, and then calculate the degree of influence of the ripple voltage on each branch based on the abnormal data points of the pulse width modulation signal in the input circuit. Then, the isolation effect evaluation value of the isolated common cathode current circuit is determined through the influence degree value of each branch and the current attenuation coefficient. When evaluating the isolation effect, it is necessary to evaluate the isolation effect of the entire isolation circuit. Therefore, the isolation effect of the circuit can be determined by the current attenuation coefficient of each branch in the circuit. Finally, based on the calculated isolation effect evaluation value, the accurate isolation effect of the isolated common cathode current circuit is obtained.

[0072] Further, refer to Figure 3 Based on the first embodiment of the present application, another embodiment of the present application is provided. In this embodiment, step S40 of determining the isolation effect evaluation value of the isolated common cathode current circuit based on the impact degree value and the current attenuation coefficient includes: Step S41, based on the impact degree value, correcting the current attenuation coefficient to obtain a corrected current attenuation coefficient; As an example, after calculating the impact degree value, the current attenuation coefficient is corrected. In Example 1, the degree of influence of the ripple voltage on different branches is calculated. The greater the impact degree, the greater the degree of correction required for the original current signal. In this way, the evaluation of the circuit isolation degree will be more accurate. Therefore, the current attenuation coefficient is corrected to obtain a corrected current attenuation coefficient.

[0073] The step S41 of correcting the current attenuation coefficient based on the impact degree value to obtain the corrected current attenuation coefficient includes: Normalize the impact degree value to obtain normalized data; As an example, the impact value is normalized. The normalization method can be performed through the norm function. The normalized data is expressed as ,in, Indicates the The degree to which the branch is affected by the ripple voltage.

[0074] Based on the normalized data, the current attenuation coefficient is corrected to obtain a corrected current attenuation coefficient.

[0075] As an example, the corrected current attenuation coefficient may be calculated as follows:

[0076] Among them, represents the corrected current attenuation coefficient, represents the current attenuation coefficient, Indicates the The degree to which each branch is affected by the ripple voltage; represents the linear normalization function.

[0077] Step S42: determining an isolation effect evaluation value of the isolated common cathode current circuit based on the corrected current attenuation coefficient.

[0078] As an example, when evaluating the isolation effect of the entire circuit, it can be evaluated based on the transmission coefficient from the leakage circuit to different branches. The transmission coefficient is expressed as the corrected current attenuation coefficient. If the detected transmission coefficient is larger, the isolation effect is better.

[0079] As an example, the current attenuation coefficient is corrected, and then the isolation effect of the isolated common cathode current circuit is evaluated based on the current attenuation coefficient, and an isolation effect evaluation value is calculated.

[0080] The step S42 of determining the isolation effect evaluation value of the isolated common cathode current circuit based on the corrected current attenuation coefficient includes: Obtain the number of branches of the isolated common cathode current circuit, and calculate the sum of the values ​​of the corrected current attenuation coefficients in each branch; Based on the numerical value and the number of branches, the isolation effect evaluation value of the isolated common cathode current circuit is calculated.

[0081] As an example, the isolation effect evaluation value may be calculated as follows:

[0082] Where, Indicates the isolation effect of the isolation circuit, represents the corrected current attenuation coefficient, It represents the number of branches in the branch circuit. The isolation effect evaluation value of the isolation circuit is obtained by the above method. The larger the value, the better the isolation effect on the current.

[0083] In this embodiment, the isolation effect of the circuit is evaluated by using the corrected current attenuation coefficient, and then an accurate isolation effect evaluation value is calculated.

[0084] Furthermore, based on the first and second embodiments of the present application, another embodiment of the present application is provided. In this embodiment, the isolated common cathode current circuit includes a digital isolation circuit, a filtering circuit, a constant current circuit and a current output module. The digital isolation circuit, the filtering circuit, the constant current circuit and the current output module are electrically connected in sequence. The digital isolation circuit flips the received pulse width modulation signal and transmits the flipped pulse width modulation signal to the current output module through the filtering circuit and the constant current circuit.

[0085] It should be noted that the isolated common cathode current circuit also includes a data processing module, which is used to receive the input pulse width modulation signal, then transmit the pulse width modulation signal to the digital isolation circuit, and collect circuit test data of the digital isolation circuit, filtering circuit, constant current circuit and current output module, and then process the circuit test data to obtain test results.

[0086] It should be noted that the simplified external wiring diagram of the traditional isolated common cathode circuit is as follows Figure 4 As shown, the power supply is isolated via power supply isolation, and the PWM signal output by the CPU is isolated via an optocoupler. After passing through the filtering circuit, the PWM signal must pass through a first-stage inverting amplifier circuit to output a negative voltage, and then through a constant current circuit to output the corresponding current value. This circuit utilizes power supply isolation, optocoupler isolation, and the addition of a first-stage inverting amplifier circuit, increasing its complexity.

[0087] The isolated common cathode current circuit involved in the embodiment is as follows Figure 5 As shown in the figure, a digital isolation chip is used to directly complete the PWM signal isolation and inversion, eliminating the three-stage modules of optocoupler, isolated power supply and inverting amplifier circuit in the traditional solution, saving PCB area and improving signal fidelity.

[0088] Reference Figure 7 , Figure 7 It is a schematic diagram of the device structure of the hardware operating environment involved in the embodiment of the present application.

[0089] like Figure 7 As shown, the isolated common cathode current circuit test device may include: a processor 1001 , a memory 1005 , and a communication bus 1002 . The communication bus 1002 is used to implement connection and communication between the processor 1001 and the memory 1005 .

[0090] Optionally, the isolated common-cathode current circuit test equipment may also include a user interface, a network interface, a camera, an RF (Radio Frequency) circuit, a sensor, a WiFi module, and the like. The user interface may include a display and an input submodule such as a keyboard. Optional user interfaces may also include standard wired and wireless interfaces. The network interface may include standard wired and wireless interfaces (such as a WiFi interface).

[0091] Those skilled in the art will understand that Figure 7 The structure of the isolated common cathode current circuit test device shown in the figure does not constitute a limitation to the isolated common cathode current circuit test device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0092] like Figure 7 As shown, memory 1005, which serves as a storage medium, may include an operating system, a network communication module, and an isolated common-cathode current circuit test program. The operating system is a program that manages and controls the hardware and software resources of the isolated common-cathode current circuit test equipment and supports the execution of the isolated common-cathode current circuit test program and other software and / or programs. The network communication module is used to enable communication between the various components within memory 1005, as well as communication with other hardware and software in the isolated common-cathode current circuit test system.

[0093] exist Figure 7 In the isolated common cathode current circuit testing device shown, the processor 1001 is used to execute the isolated common cathode current circuit testing program stored in the memory 1005 to implement the steps of any of the above-mentioned isolated common cathode current circuit testing methods.

[0094] The specific implementation of the isolated common cathode current circuit testing equipment of the present application is basically the same as the above-mentioned embodiments of the isolated common cathode current circuit testing method, and will not be repeated here.

[0095] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0096] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0097] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as mentioned above, and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods of each embodiment of the present application.

[0098] The above are only preferred embodiments of the present application and do not limit the scope of application of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application description and drawings, or directly or indirectly applied in other related technical fields, are also included in the scope of protection of the present application.

[0099] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0100] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. A method for testing an isolated common cathode current circuit, characterized in that: Applied to an isolated common cathode current circuit, the isolated common cathode current circuit includes a digital isolation circuit and a current output module, the digital isolation circuit and the current output module are electrically connected, and the method includes: Inputting a pulse width modulation signal into the digital isolation circuit for testing, and obtaining circuit test data output by the isolated common cathode current circuit; Calculating the current attenuation coefficient of each branch based on the current data in the circuit test data; Extracting abnormal data points of the pulse width modulation signal during the test process, and calculating the degree of influence of the ripple voltage on each branch based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points; An isolation effect evaluation value of the isolated common cathode current circuit is determined based on the impact degree value and the current attenuation coefficient.

2. The isolated common cathode current circuit testing method according to claim 1, wherein: After calculating the current attenuation coefficient of each branch based on the current data in the circuit test data, the method further includes: Perform clustering processing on the current data corresponding to each branch to obtain current clustering data; Calculating the current fluctuation degree of each branch based on the current attenuation coefficient and the current clustering data; Calculating a current response weight based on the current fluctuation degree on each different branch; The calculating of the influence degree of the ripple voltage on each branch based on the number of data points corresponding to the abnormal data point and the signal fluctuation difference value of the abnormal data point includes: Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point, the influence degree of each branch caused by the ripple voltage is calculated.

3. The isolated common cathode current circuit testing method according to claim 2, wherein: The current response weight is calculated based on the current fluctuation degree on each different branch, including: Determining a first number of electronic components on different branches and a maximum value of fluctuations in each of the current fluctuation degrees; A current response weight is calculated based on the current fluctuation degree, the fluctuation maximum value, and the first quantity.

4. The isolated common cathode current circuit testing method according to claim 2, wherein: The signal fluctuation difference value includes a signal amplitude, and the calculation based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point to obtain the degree of influence of the ripple voltage on each branch includes: Based on the current response weight, the number of data points corresponding to the abnormal data point, and the signal amplitude of each abnormal data point, the degree to which each branch is affected by the ripple voltage is calculated.

5. The isolated common cathode current circuit testing method according to claim 4, wherein: The extracting of abnormal data points of the pulse width modulation signal during the test process includes: Decomposing the pulse width modulation signal by a preset decomposition algorithm to obtain a decomposed signal; A trend item data sequence is extracted from the decomposed signal, and abnormal data points in the trend item data sequence are obtained.

6. The isolated common cathode current circuit testing method according to claim 5, wherein: The signal fluctuation difference value is the difference between the signal amplitude of each abnormal data point and the signal amplitude mean of the trend item data sequence, and the signal fluctuation difference value is proportional to the degree of interference of the pulse width modulation signal by the ripple voltage.

7. The isolated common cathode current circuit testing method according to claim 1, wherein: The calculating of the current attenuation coefficient of each branch based on the current data in the circuit test data includes: For any of the branches, determining an initial current value and a first current value at a preset position of the circuit branch based on current data in the circuit test data; Calculating the current transmission time between the position corresponding to the initial current value and the preset position; The current attenuation coefficient of each branch is calculated based on the initial current value, the first current value, and the current transmission time.

8. The isolated common cathode current circuit testing method according to claim 1, wherein: The determining, based on the impact degree value and the current attenuation coefficient, an isolation effect evaluation value of the isolated common cathode current circuit includes: Based on the impact degree value, the current attenuation coefficient is corrected to obtain a corrected current attenuation coefficient; Based on the corrected current attenuation coefficient, an isolation effect evaluation value of the isolated common cathode current circuit is determined.

9. The isolated common cathode current circuit testing method according to claim 8, wherein: The determining, based on the corrected current attenuation coefficient, an isolation effect evaluation value of the isolated common cathode current circuit includes: Obtaining the number of branches of the isolated common cathode current circuit, and calculating the sum of the values ​​of the corrected current attenuation coefficients in each branch; Based on the numerical value sum and the number of branches, an isolation effect evaluation value of the isolated common cathode current circuit is calculated.

10. An isolated common cathode current circuit, characterized in that: The isolated common cathode current circuit includes a digital isolation circuit, a filtering circuit, a constant current circuit and a current output module. The digital isolation circuit, the filtering circuit, the constant current circuit and the current output module are electrically connected in sequence. The digital isolation circuit flips the received pulse width modulation signal and transmits the flipped pulse width modulation signal to the current output module through the filtering circuit and the constant current circuit.

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