An isolated common cathode current circuit and an isolated common cathode current circuit testing method

Abstract

The application 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.The method comprises the following steps: inputting a pulse width modulation signal to a digital isolation circuit for testing, and obtaining circuit testing data of the isolated common cathode current circuit; based on current data in the circuit testing data, the current attenuation coefficients of branches are calculated; abnormal data points of the pulse width modulation signal in the testing process are extracted, and based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points, the influence degree values of the branches affected by ripple voltage are calculated; based on the influence degree values and the current attenuation coefficients, the isolation effect evaluation value of the isolated common cathode current circuit is determined.The application achieves the technical effect of accurately testing the circuit isolation degree.

Description

TECHNICAL FIELD

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

[0002] The isolated common cathode circuit is a core technology for realizing signal isolation and transmission in an industrial automation system, and is mainly used for converting a physical quantity collected by a sensor into a standard 4-20mA current signal. A traditional isolated common cathode output circuit generally uses an isolated power supply and an optical coupler and other isolation elements to realize isolation. However, the traditional isolated common cathode circuit testing method only examines a single factor of temperature or vibration, and lacks composite testing capability. Under the synergistic effect of a strong electromagnetic field and high temperature, the magnetic permeability of the magnetic core material in the circuit decreases, resulting in a decrease in the isolation barrier effectiveness and a decrease in the isolation effect of the circuit. The traditional single voltage withstand test cannot detect the accurate circuit isolation effect. SUMMARY

[0003] The main purpose of the present application is to provide an isolated common cathode current circuit and an isolated common cathode current circuit testing method, which aims to solve the technical problem in the related art that the traditional single voltage withstand test cannot detect the accurate circuit isolation effect.

[0004] To achieve the above-mentioned purpose, the 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 an isolated common cathode current circuit, the isolated common cathode current circuit comprising a digital isolation circuit and a current output module, the digital isolation circuit and the current output module being electrically connected, and comprising:

[0005] inputting a pulse width modulation signal to the digital isolation circuit for testing, and obtaining circuit test data of the isolated common cathode current circuit;

[0006] based on current data in the circuit test data, calculating current attenuation coefficients of each branch;

[0007] extracting abnormal data points of the pulse width modulation signal in the testing process, and based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points, calculating an influence degree value of each branch affected by ripple voltage;

[0008] based on the influence degree value and the current attenuation coefficient, determining an isolation effect evaluation value of the isolated common cathode current circuit.

[0009] In a possible implementation of the present application, after the current attenuation coefficients of each branch are calculated based on the current data in the circuit test data, the method further comprises:

[0010] performing clustering processing on the current data corresponding to each branch to obtain current clustering data.

[0011] The current fluctuation degree of each branch is calculated based on the current attenuation coefficient and the current clustering data;

[0012] The current response weight is calculated based on the current fluctuation degree of each different branch;

[0013] The influence degree value of each branch affected by the ripple voltage is calculated based on the data point quantity corresponding to the abnormal data point and the signal fluctuation difference value of the abnormal data point, including:

[0014] The influence degree value of each branch affected by the ripple voltage is calculated based on the current response weight, the data point quantity corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point.

[0015] In a possible implementation of the present application, the current response weight is calculated based on the current fluctuation degree of each different branch, including:

[0016] The first quantity of electronic elements on different branches and the maximum fluctuation value in the current fluctuation degree are determined;

[0017] The current response weight is calculated based on the current fluctuation degree, the maximum fluctuation value, and the first quantity.

[0018] In a possible implementation of the present application, the signal fluctuation difference value includes the signal amplitude, and the influence degree value of each branch affected by the ripple voltage is calculated based on the current response weight, the data point quantity corresponding to the abnormal data point, and the signal fluctuation difference value of the abnormal data point, including:

[0019] The influence degree value of each branch affected by the ripple voltage is calculated based on the current response weight, the data point quantity corresponding to the abnormal data point, and the signal amplitude of each abnormal data point.

[0020] In a possible implementation of the present application, the abnormal data point of the pulse width modulation signal in the test process is extracted, including:

[0021] The pulse width modulation signal is decomposed by a preset decomposition algorithm to obtain a decomposition signal;

[0022] The trend item data sequence in the decomposition signal is extracted, and the abnormal data point in the trend item data sequence is obtained.

[0023] In a possible implementation of the present application, the signal fluctuation difference value is the difference value between the signal amplitude of each abnormal data point and the average signal amplitude of the trend item data sequence, and the signal fluctuation difference value is proportional to the interference degree of the pulse width modulation signal affected by the ripple voltage.

[0024] 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:

[0025] For any branch, the initial current value and the first current value at the preset position of the circuit branch are determined based on the current data in the circuit test data.

[0026] The current transmission time between the position corresponding to the initial current value and the preset position is calculated.

[0027] The current attenuation coefficient of each branch is calculated based on the initial current value, the first current value and the current transmission time.

[0028] In a possible implementation of the present application, the isolation effect evaluation value of the isolated common cathode current circuit is determined based on the influence degree value and the current attenuation coefficient, including:

[0029] The current attenuation coefficient is corrected based on the influence degree value to obtain a corrected current attenuation coefficient.

[0030] The isolation effect evaluation value of the isolated common cathode current circuit is determined based on the corrected current attenuation coefficient.

[0031] In a possible implementation of the present application, the isolation effect evaluation value of the isolated common cathode current circuit is determined based on the corrected current attenuation coefficient, including:

[0032] The number of branches of the isolated common cathode current circuit is obtained, and the sum of the values of the corrected current attenuation coefficients in each branch is calculated.

[0033] The isolation effect evaluation value of the isolated common cathode current circuit is calculated based on the sum of the values and the number of branches.

[0034] To achieve the above-mentioned purpose, the embodiments of the present application provide 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 performs flip processing on the received pulse width modulation signal, and transmits the flip-processed pulse width modulation signal to the current output module through the filter circuit and the constant current circuit.

[0035] The application provides an isolated common cathode current circuit and an isolated common cathode current circuit testing method. In the related art, the traditional isolated common cathode circuit testing method only examines a single factor of temperature or vibration, lacks composite testing capability, and under the synergistic effect of a strong electromagnetic field and high temperature, the magnetic permeability of a magnetic core material decreases, resulting in the attenuation of the isolation barrier effectiveness and the deterioration of the isolation effect of the circuit. However, the traditional single voltage resistance test cannot detect the accurate circuit isolation effect. In the application, a pulse width modulation signal is input into a 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 circuit test data is used to calculate the current attenuation coefficients of each branch in the circuit. Then, the influence degree values of each branch affected by ripple voltage are calculated according to the abnormal data points of the pulse width modulation signal in the input circuit. Further, the isolation effect evaluation value of the isolated common cathode current circuit is determined through the influence degree values of each branch and the current attenuation coefficients. When evaluating the isolation effect, the isolation effect of the entire isolation circuit needs to be evaluated. Therefore, the isolation effect of the circuit can be determined through the current attenuation coefficients of each branch in the circuit. Finally, the accurate isolation effect of the isolated common cathode current circuit is obtained according to the calculated isolation effect evaluation value. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A flowchart of a first embodiment of the isolated common cathode current circuit testing method of the application;

[0037] Figure 2 A simplified principle diagram of a signal inversion circuit related to the isolated common cathode current circuit testing method of the application;

[0038] Figure 3 A flowchart of a second embodiment related to the isolated common cathode current circuit testing method of the application;

[0039] Figure 4 A simplified external wiring diagram of a traditional isolated common cathode circuit related to the embodiment scheme of the application;

[0040] Figure 5 A simplified external wiring diagram of an improved isolated common cathode circuit related to the isolated common cathode current circuit testing method of the application;

[0041] Figure 6 A simplified principle diagram of a digital isolation chip related to the isolated common cathode current circuit testing method of the application;

[0042] Figure 7 A device structure diagram of a hardware running environment related to the embodiment scheme of the application. DETAILED DESCRIPTION

[0043] It should be understood that the specific embodiments described herein are merely exemplary and do not limit the application.

[0044] The embodiment of the application provides a kind of isolated common cathode current circuit test method, in the first embodiment of the isolated common cathode current circuit test method of the application, refer to Figure 1 , method includes:

[0045] Step S10, pulse width modulation signal is input to isolated common cathode current circuit for testing, and the circuit test data of isolated common cathode current circuit is acquired;

[0046] Step S20, based on the current data in circuit test data, the current attenuation coefficient of each branch is calculated;

[0047] Step S30, the abnormal data point of pulse width modulation signal in test process is extracted, and based on the data point quantity corresponding to abnormal data point and the signal fluctuation difference value of abnormal data point, the influence degree value of each branch by ripple voltage is calculated;

[0048] Step S40, based on influence degree value and current attenuation coefficient, the isolation effect evaluation value of isolated common cathode current circuit is determined.

[0049] The embodiment aims at: test the accurate circuit isolation effect.

[0050] Specific steps are as follows:

[0051] Step S10, pulse width modulation signal is input to isolated common cathode current circuit for testing, and the circuit test data of isolated common cathode current circuit is acquired.

[0052] As an example, the isolated common cathode current circuit test method can be applied to isolated common cathode current circuit test device, and the isolated common cathode current circuit test device belongs to isolated common cathode current circuit test system, and the isolated common cathode current circuit test system belongs to isolated common cathode current circuit test equipment.

[0053] As an example, the isolated common cathode current circuit test method can also be applied to isolated common cathode current circuit, and the isolated common cathode current circuit is a circuit structure with electrical isolation and current detection function, and its core feature is that the common cathode current sampling point is electrically isolated from the rear-end processing circuit by isolating devices such as optocoupler and transformer, and the circuit is usually composed of common cathode connection power device, shunt resistance, isolation amplifier / optocoupler and signal conditioning unit.

[0054] When the main loop current flows through the common cathode node, the shunt resistance converts the current into a voltage signal, which is transmitted to the secondary side through the isolating device, and finally outputs a detection signal proportional to the main loop current without direct electrical connection.

[0055] This design can avoid ground loop interference and provide a safe current monitoring solution for high-voltage or floating ground systems, and is widely used in switching power supplies, motor drives, and new energy converters.

[0056] As an example, the pulse width modulation signal can 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.

[0057] As an example, the circuit test data can be test data generated during the test, including but not limited to current data at each point in the circuit, time of current transmission, change amplitude of the PWM signal, and average value of each current, etc.

[0058] Specifically, during the test, the core architecture includes:

[0059] Device configuration: high-temperature electromagnetic coupling test box.

[0060] Temperature range: -40℃~150℃, temperature control accuracy ±1℃ (125℃ steady-state test).

[0061] Built-in GTEM chamber: generate 80MHz-1GHz continuous sweep electromagnetic field, field strength 30V / m (IEC 61000-4-3 standard).

[0062] Dynamic load simulator: output 0-1kΩ resistive load, parallel 100pF capacitive load (simulate long cable distributed capacitance).

[0063] High-speed data acquisition system: 16-bit ADC, sampling rate 1MSa / s, synchronous acquisition of input / output signals, leakage current and magnetic core temperature.

[0064] The test steps include:

[0065] 1. Place the isolated common cathode current circuit in the test box and connect the load simulator.

[0066] 2. Set the temperature to 125℃ and stabilize for 30 minutes.

[0067] 3. Turn on the GTEM chamber (a device for electromagnetic compatibility testing), apply 80MHz-1GHz sweep electromagnetic interference (field strength 30V / m).

[0068] 4. Inject a 500kHz PWM signal (duty cycle 50%, amplitude 5V) into the circuit.

[0069] 5. Run continuously for 300 hours, record data every 10 minutes.

[0070] Step S20, based on the current data in the circuit test data, the current attenuation coefficient of each branch is calculated;

[0071] As an example, the current data can be the leakage current data in the circuit, the leakage current will appear current loss in the process of conduction in the circuit, and the attenuation degree will be larger with the increase of transmission distance. The attenuation degree of each branch in the isolated current circuit can be calculated by the test current data, that is, the current attenuation coefficient.

[0072] The step S20 of the isolated common cathode current circuit test further includes steps S21-S23, including:

[0073] Step S21, for any branch, based on the current data in the circuit test data, the initial current value and the first current value at the preset position of the circuit branch are determined.

[0074] As an example, the initial current value is the current value transmitted at the starting position of the circuit, at this time, the current has not attenuated, and the current will attenuate when it is transmitted to a certain distance.

[0075] As an example, the preset position of the circuit can 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 testing.

[0076] Step S22, the current transmission time between the initial current value corresponding position and the preset position is calculated.

[0077] As an example, the current transmission time between the two positions can be calculated from the time point of the current starting transmission position of the circuit, and the current transmission time between the two positions is obtained when the preset position is reached.

[0078] Step S23, based on the initial current value, the first current value and the current transmission time, the current attenuation coefficient of each branch is calculated.

[0079] As an example, the current attenuation coefficient refers to the current loss in the process of conduction of the leakage current, and the attenuation degree is larger with the increase of transmission distance. Therefore, the attenuation coefficient is obtained according to the change of the initial value and the measured value of the leakage current. The calculation formula is as follows:

[0080]

[0081] In the formula, represents the current attenuation coefficient, represents the initial current value, represents the first current value at the current position, represents the current reaching the first the current transmission time required at the position.

[0082] The simplified schematic diagram of the digital isolation chip in the isolated common cathode current circuit is shown in Figure 6 Figure 6 The PWM signal PWM_A output by the CPU is reversed after passing through the digital isolation chip IU1, and a single operational amplifier can realize the output of 4-20mA common cathode. The output PWM_A' signal.

[0083] There are multiple branches in the isolated common cathode current circuit. Taking the signal reversing circuit contained in the isolated common cathode current circuit in Figure 2 The circuit in which IR2 and ID5 are located is a branch, and the Zth position is the preset position in the branch. The preset position on a branch can be one, two or more. For example, when the preset position on the branch is one, the Zth position is set at the left side of the IR2 connection point. According to the initial current value and the first current value at the Zth position, the current decay coefficient on the branch is calculated. When the preset position is two, the average value of the current decay coefficients calculated at the two positions is taken as the current decay coefficient of the branch.

[0084] Specifically, from the signal reversing circuit contained in the isolated common cathode current circuit in Figure 2 , it can be obtained that the PWM_A' signal passes through the filter circuit composed of the resistor IR1, the capacitor IE1 and the IC4 to output a corresponding negative voltage value. According to the principle of virtual short of the operational amplifier IU2, V1=V2 at this time; V2 and the SGND at the end of the diode ID5 form a voltage difference, and a current IIR2=|V2-SGND| / RIR2 is formed on the resistor IR2; the current IIR2 is output to the load circuit through the transistor IP1 and the diode ID9. The isolated common cathode current circuit is simple and reliable, has high accuracy, low cost and strong practicability.

[0085] After calculating the current decay coefficients of each branch based on the current data in the circuit test data, the method further includes:

[0086] Step A1, clustering the current data corresponding to each branch to obtain current clustering data;

[0087] As an example, the clustering method can be clustering the current data of each branch by a clustering algorithm to obtain multiple clustering clusters of the current data, that is, the current clustering data. The clustering algorithm is a known technology and will not be described here.

[0088] Step A2, calculating the current fluctuation degree of each branch based on the current decay coefficient and the current clustering data; ​

[0089] As an example, the degree of current fluctuation in each branch circuit can be determined based on the current attenuation coefficient and current clustering data. The calculation method for the degree of current fluctuation can be as follows:

[0090]

[0091] In the formula, Indicates the first The degree of current fluctuation in each branch. Indicates the first The current attenuation coefficient of each branch; This represents the variance of the mean current across all clusters / current clustering data.

[0092] The variance of the mean current represents 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 the leakage current generates greater resistance when it propagates in that branch, and therefore the greater the degree of current fluctuation.

[0093] Step A3: Calculate the current response weights based on the current fluctuation levels on each branch.

[0094] As an example, based on the current fluctuation levels of different branches obtained from the above calculations, the current response weights are then calculated.

[0095] Step A3, which calculates the current response weights based on the current fluctuation levels on different branches, includes:

[0096] Determine the initial number of electronic components on different branches and the maximum fluctuation value among various current fluctuation levels;

[0097] As an example, for any circuit branch, determine the number of electronic components on each branch, which is the first quantity. The current fluctuation level has been calculated in the previous step, and the data of the maximum fluctuation value can be extracted from the data of each current fluctuation level.

[0098] The current response weight is calculated based on the degree of current fluctuation, the maximum value of the fluctuation, and the first quantity.

[0099] As an example, the formula for calculating the current response weight can be:

[0100]

[0101] In the formula, Indicates the first The current response weight of each branch, Indicates the first The degree of current fluctuation in each branch. represents the maximum value of the current fluctuation degree in all branches, represents the first number of electronic components on the branch, norm() represents a linear normalization function.

[0102] As an example, the purpose of calculating the current response weight is to accurately reflect the effect of different branches on the current isolation when calculating the current isolation effect evaluation value of the isolated common cathode current circuit.

[0103] Based on the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points, the influence degree value of each branch affected by the ripple voltage is calculated, including:

[0104] Based on the current response weight, the number of data points corresponding to the abnormal data points, and the signal fluctuation difference value of the abnormal data points, the influence degree value of each branch affected by the ripple voltage is calculated.

[0105] As an example, the generation of the ripple voltage is mainly caused by the periodic action of the switching device in the power supply system, the characteristics of the nonlinear element, and the insufficient processing of the filter circuit. When the switching tube (such as MOSFET) rapidly switches, the current mutation causes the inductance magnetic field to fluctuate, the unidirectional conduction characteristic of the rectifier diode causes the pulsed direct current output, and the parasitic parameters of the equivalent series resistance (ESR) of the filter capacitor and the inductance can weaken the suppression ability of high-frequency noise. In addition, factors such as load mutation, input voltage fluctuation, and parasitic inductance in PCB layout can further exacerbate the residual AC component, eventually forming a periodic fluctuation superimposed on the stable voltage at the DC output end.

[0106] As an example, high-frequency ripple will be superimposed on the signal to be measured, generating waveform distortion collected by oscilloscopes and other instruments, especially for monitoring weak signals at the microvolt level. Secondly, the ripple voltage coupled through the power supply will interfere with the accuracy of the reference voltage source, causing periodic deviations in the measurement results of key devices such as ADC (analog-to-digital converter), so it is necessary to correct the interference caused by the ripple voltage.

[0107] 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 has insufficient bandwidth or electromagnetic interference causes signal jitter. Moreover, because different currents pass through different branches, the influence degree of the ripple voltage generated is different, and the isolation degree of the current is also different.

[0108] Among them, 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 points, and the signal fluctuation difference value of the abnormal data points, the influence degree value of each branch affected by the ripple voltage is calculated, including:

[0109] Based on the current response weight, the number of data points corresponding to abnormal data points, and the signal amplitude of each abnormal data point, the degree of influence of ripple voltage on each branch is calculated.

[0110] As an example, abnormal data points are the abnormal data points in the PWM test signal. These data points are affected by ripple voltage, which will cause the data sequence to be unstable. There will be a large difference between the signal amplitude and the average signal amplitude. Furthermore, 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 to calculate the degree of influence.

[0111] Among them, abnormal data points of the pulse width modulation signal extracted during the test include:

[0112] The pulse width modulation signal is decomposed using a preset decomposition algorithm to obtain the decomposed signal;

[0113] As an example, the preset decomposition algorithm can be the STL algorithm. The PWM signal is decomposed by the STL algorithm to obtain the corresponding decomposed signal. The decomposed signal includes: periodic term, trend term and residual term. The periodic term reflects the regular and recurring fluctuation pattern in the data. The trend term represents the slow and continuous direction of change in the signal. The residual term contains random fluctuations or sudden events that cannot be explained by the periodicity and trend.

[0114] Extract the trend term data sequence from the decomposed signal and obtain the outlier data points in the trend term data sequence.

[0115] As an example, by obtaining the trend term data sequence, the abnormal data points in the trend term data sequence are obtained through the LOF algorithm, where the LOF algorithm is a well-known existing technology and will not be described in detail here; if the trend term is more unstable and the abnormality of the abnormal data points is greater, it means that the PWM signal of the current branch is more affected.

[0116] Step S30: Extract abnormal data points of the pulse width modulation signal during the test, and calculate the degree of influence of 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.

[0117] As an example, the formula for calculating the degree of influence could be:

[0118]

[0119] In the formula, Indicates the first The degree to which each branch is affected by ripple voltage Indicates the current response weight. The autocorrelation coefficient represents the trend term. The autocorrelation coefficient indicates the stationarity of a data series; the less stationary the series, the larger its autocorrelation coefficient. Indicates the first The trend item of the branch road The signal amplitude of the abnormal data points Indicates the first The average signal amplitude of the trend term of each branch; Indicates the first The number of outlier data points in the trend item of each branch. This indicates the difference in signal fluctuations between abnormal data points.

[0120] Among them, the signal fluctuation difference value is the difference between the signal amplitude of each abnormal data point and the mean signal amplitude of the trend term data sequence. The signal fluctuation difference value is proportional to the degree of interference of the pulse width modulation signal by the ripple voltage.

[0121] As an example, The difference between the amplitude of the abnormal data point and the mean of the trend term sequence is the signal fluctuation difference. The larger the signal fluctuation difference, the greater the interference of the PWM signal with ripple voltage. In other words, the signal fluctuation difference is proportional to the interference of the pulse width modulation signal with ripple voltage.

[0122] Step S40: Based on the degree of influence and the current attenuation coefficient, determine the isolation effect evaluation value of the isolated common cathode current circuit.

[0123] As an example, after calculating the degree of influence, the current attenuation coefficient is corrected based on the degree of influence. The isolation effect of the entire circuit is then evaluated based on the corrected current attenuation coefficient. In this way, the isolation effect evaluation value of the isolated common cathode current circuit is determined. The isolation effect evaluation value evaluates the degree of isolation of the entire isolation circuit. The larger the isolation effect evaluation value, the better the current isolation effect.

[0124] The application provides an isolated common cathode current circuit test method. In the related art, the traditional isolated common cathode circuit test method only examines a single factor of temperature or vibration, lacks composite test capability, under the synergistic effect of a strong electromagnetic field and high temperature, the magnetic permeability of a magnetic core material decreases, causing the isolation barrier effectiveness to attenuate, and the isolation effect of the circuit to deteriorate. The traditional single voltage withstand test cannot detect the accurate circuit isolation effect. In the application, a pulse width modulation signal is input to the isolated common cathode current circuit, and circuit test data of the isolated common cathode current circuit is acquired. The current data in the circuit test data is used to calculate the current attenuation coefficients of each branch in the circuit. Then, the abnormal data points of the pulse width modulation signal in the input circuit are used to calculate the influence degree values of each branch affected by the ripple voltage. Further, the influence degree values of each branch and the current attenuation coefficients are used to determine the isolation effect evaluation value of the isolated common cathode current circuit. When evaluating the isolation effect, the isolation effect of the entire isolation circuit needs to be evaluated. Therefore, the isolation effect of the circuit can be determined by the current attenuation coefficients of each branch in the circuit. Finally, the accurate isolation effect of the isolated common cathode current circuit is obtained according to the calculated isolation effect evaluation value.

[0125] Further, with reference to Figure 3 , based on the first embodiment in the application, another embodiment of the application is provided. In the embodiment, the step S40 of determining the isolation effect evaluation value of the isolated common cathode current circuit based on the influence degree value and the current attenuation coefficient includes:

[0126] The step S41 includes correcting the current attenuation coefficient based on the influence degree value to obtain a corrected current attenuation coefficient.

[0127] As an example, after the influence degree value is calculated, the current attenuation coefficient is corrected. In the first embodiment, the influence degree of each branch affected by the ripple voltage is calculated. The greater the influence degree, the greater the correction degree of the original current signal. Therefore, the current attenuation coefficient is corrected to obtain a corrected current attenuation coefficient, so that the evaluation of the circuit isolation degree is more accurate.

[0128] The step S41 of correcting the current attenuation coefficient based on the influence degree value to obtain a corrected current attenuation coefficient includes:

[0129] The influence degree value is normalized to obtain normalized data.

[0130] As an example, the influence degree value is normalized. The normalization method can be performed by a norm function. The normalized data is represented as , wherein represents the i-th normalized data. The value of the degree of influence of the ripple voltage on the branch.

[0131] The current attenuation coefficient is corrected based on the normalized data to obtain a corrected current attenuation coefficient.

[0132] As an example, the corrected current attenuation coefficient can be calculated in the following manner:

[0133]

[0134] wherein, represents the corrected current attenuation coefficient, represents the current attenuation coefficient, represents the first the value of the degree of influence of the ripple voltage on the branch; represents a linear normalization function.

[0135] At step S42, the isolation effect evaluation value of the isolated common cathode current circuit is determined based on the corrected current attenuation coefficient.

[0136] As an example, when evaluating the isolation effect of the entire circuit, the transmission coefficient of the leakage circuit to different branches can be evaluated, wherein the transmission coefficient is represented by the corrected current attenuation coefficient. The greater the detected transmission coefficient, the better the isolation effect.

[0137] As an example, by correcting the current attenuation coefficient, the isolation effect of the isolated common cathode current circuit is evaluated by the current attenuation coefficient, and the isolation effect evaluation value is calculated.

[0138] The step S42 of determining the isolation effect evaluation value of the isolated common cathode current circuit based on the corrected current attenuation coefficient comprises:

[0139] The number of branches of the isolated common cathode current circuit is obtained, and the numerical sum of the corrected current attenuation coefficients in each branch is calculated.

[0140] Based on the numerical sum and the number of branches, the isolation effect evaluation value of the isolated common cathode current circuit is calculated.

[0141] As an example, the isolation effect evaluation value can be calculated in the following manner:

[0142]

[0143] wherein, represents the isolation effect of the isolation circuit, represents the corrected current attenuation coefficient, The branch number of the branch circuit is represented, and the isolation effect evaluation value of the isolation circuit is obtained by the above method, and the larger the value is, the better the isolation effect on the current is.

[0144] In the embodiment, the isolation effect of the circuit is evaluated by the corrected current attenuation coefficient, and then an accurate isolation effect evaluation value is calculated.

[0145] Further, based on the first and second embodiments of the present application, another embodiment of the present application is provided, in which the isolated common cathode current circuit 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 performs flip processing on the received pulse width modulation signal, and transmits the flip-processed pulse width modulation signal to the current output module through the filter circuit and the constant current circuit.

[0146] It should be noted that the isolated common cathode current circuit further includes a data processing module, which is configured to receive an input pulse width modulation signal, transmit the pulse width modulation signal to the digital isolation circuit, collect circuit test data of each part of the digital isolation circuit, the filter circuit, the constant current circuit, and the current output module, and then process the circuit test data to obtain a test result.

[0147] It should be noted that a traditional isolated common cathode circuit external simplified wiring diagram is shown in Figure 4 The power supply is isolated by a power supply, and the PWM signal output by the CPU is isolated by an optical coupler. The PWM signal needs to pass through a level shifter circuit after passing through the filter circuit to output a negative voltage, and then pass through the constant current circuit to output a corresponding current value. In this circuit, power supply isolation and optical coupler isolation are used, and a level shifter circuit is added, which increases the complexity of the circuit.

[0148] In the embodiment, the isolated common cathode current circuit is shown in Figure 5 The digital isolation chip is used to directly complete the PWM signal isolation and inversion, eliminating the three modules of optical coupler, isolation power supply, and inverting amplifier circuit in the traditional scheme, saving the PCB area, and improving the signal fidelity.

[0149] Referring to Figure 7 , Figure 7 is a device structure diagram of a hardware running environment involved in the embodiment scheme of the present application.

[0150] As shown in Figure 7 , the isolated common cathode current circuit test device can include a processor 1001, a memory 1005, and a communication bus 1002. The communication bus 1002 is used to realize the connection communication between the processor 1001 and the memory 1005.

[0151] Optionally, the isolated common-cathode current circuit testing equipment may also include a user interface, a network interface, a camera, RF (Radio Frequency) circuitry, sensors, a WiFi module, etc. The user interface may include a display screen and an input submodule such as a keyboard; optional user interfaces may also include standard wired or wireless interfaces. The network interface may include standard wired or wireless interfaces (such as a Wi-Fi interface).

[0152] Those skilled in the art will understand that Figure 7 The structure of the isolated common cathode current circuit test equipment shown does not constitute a limitation on the isolated common cathode current circuit test equipment. It may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0153] like Figure 7 As shown, the memory 1005, serving 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, supporting the operation 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 the memory 1005, as well as communication with other hardware and software in the isolated common-cathode current circuit test system.

[0154] exist Figure 7 In the isolated common cathode current circuit test device shown, the processor 1001 is used to execute the isolated common cathode current circuit test program stored in the memory 1005 to implement the steps of the isolated common cathode current circuit test method described above.

[0155] The specific implementation of the isolated common cathode current circuit test equipment of this application is basically the same as the embodiments of the above-described isolated common cathode current circuit test method, and will not be repeated here.

[0156] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0157] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0158] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned example method can be realized by means of software and the necessary general hardware platform, of course, it can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product in essence or in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium (such as a ROM / RAM, a magnetic disc, an optical disc) as described above, and includes a plurality of instructions for causing a terminal device (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the method of each embodiment of the present application.

[0159] The above is only the preferred embodiment of the present application, and does not limit the scope of the application. Any equivalent structure or equivalent process transformation based on the content of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the scope of protection of the present application.

[0160] It should be noted that: the above-mentioned sequence of the embodiments of the present application is only for description, not to limit the scope of the application. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are also possible or can be advantageous.

[0161] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other. Each embodiment focuses on the difference from other embodiments.

Claims

1. An isolated common cathode current circuit test method, characterized by, The application is applied to an isolated common cathode current circuit, the isolated common cathode current circuit comprises a digital isolation circuit and a current output module, the digital isolation circuit and the current output module are electrically connected, and the method comprises the following steps: A pulse width modulation signal is input to the digital isolation circuit for testing, and circuit test data output by the isolated common cathode current circuit is acquired; Based on current data in the circuit test data, the current attenuation coefficient of each branch is calculated; Abnormal data points of the pulse width modulation signal in the test process are extracted, and the influence degree value of each branch affected by ripple voltage is calculated 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 influence degree value and the current attenuation coefficient, the isolation effect evaluation value of the isolated common cathode current circuit is determined.

2. The method of claim 1, wherein the method further comprises: After the current attenuation coefficient of each branch is calculated based on the current data in the circuit test data, the following steps are further included: The current data corresponding to each branch is clustered to obtain current clustering data; Based on the current attenuation coefficient and the current clustering data, the current fluctuation degree of each branch is calculated; Based on the current fluctuation degree on each different branch, the current response weight is calculated; The influence degree value of each branch affected by ripple voltage is calculated based on the current response weight, the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points. The influence degree value of each branch affected by ripple voltage is calculated based on the current response weight, the number of data points corresponding to the abnormal data points and the signal fluctuation difference value of the abnormal data points.

3. The method of claim 2, wherein the step of applying a test signal to the isolated common cathode current circuit comprises applying a test signal to the isolated common cathode current circuit through the first and second test signal lines. The current response weight is calculated based on the current fluctuation degree on each different branch, which comprises the following steps: The first number of electronic elements on different branches and the maximum value of fluctuation in the current fluctuation degree are determined; Based on the current fluctuation degree, the maximum value of fluctuation and the first number, the current response weight is calculated.

4. The method of claim 2, wherein the step of applying a test signal to the isolated common cathode current circuit comprises applying a test signal to the isolated common cathode current circuit to determine whether the isolated common cathode current circuit is operating properly. The signal fluctuation difference value comprises a signal amplitude, and the influence degree value of each branch affected by ripple voltage is calculated based on the current response weight, the number of data points corresponding to the abnormal data points and the signal amplitude of each abnormal data point. The influence degree value of each branch affected by ripple voltage is calculated based on the current response weight, the number of data points corresponding to the abnormal data points and the signal amplitude of each abnormal data point.

5. The method of claim 4, wherein the step of applying a test signal to the isolated common cathode current circuit comprises applying a test signal to the isolated common cathode current circuit to determine whether the isolated common cathode current circuit is operating properly. The abnormal data points of the pulse width modulation signal in the test process are extracted, which comprises the following steps: The pulse width modulation signal is decomposed by a preset decomposition algorithm to obtain a decomposed signal; Trend item data sequences in the decomposed signal are extracted, and abnormal data points in the trend item data sequences are acquired.

6. The method of claim 5, wherein the step of applying a test signal to the isolated common cathode current circuit comprises applying a test signal to the isolated common cathode current circuit to determine whether the isolated common cathode current circuit is operating properly. The signal fluctuation difference value is the difference value between the signal amplitude of each abnormal data point and the average value of the signal amplitude of the trend item data sequences, and the signal fluctuation difference value is proportional to the interference degree of the pulse width modulation signal affected by ripple voltage.

7. The method of claim 1, wherein the method further comprises: applying a voltage to the test circuit to determine whether the test circuit is operating properly. The current attenuation coefficient of each branch is calculated based on the current data in the circuit test data, which comprises the following steps: For any branch, based on the current data in the circuit test data, an initial current value and a first current value at a preset position of the circuit branch are determined; A current transmission time between the initial current value corresponding position and the preset position is calculated; Based on the initial current value, the first current value and the current transmission time, a current attenuation coefficient of each branch is calculated.

8. The method of claim 1, wherein the method further comprises: applying a voltage to the test circuit to determine whether the test circuit is operating properly. The isolation effect evaluation value of the isolated common cathode current circuit is determined based on the influence degree value and the current attenuation coefficient, including: Based on the influence degree value, the current attenuation coefficient is corrected to obtain a corrected current attenuation coefficient; Based on the corrected current attenuation coefficient, the isolation effect evaluation value of the isolated common cathode current circuit is determined.

9. The method of claim 8, wherein the step of applying a test signal to the isolated common cathode current circuit comprises applying a test signal to the isolated common cathode current circuit to determine whether the isolated common cathode current circuit is operating properly. The isolation effect evaluation value of the isolated common cathode current circuit is determined based on the corrected current attenuation coefficient, including: The number of branches of the isolated common cathode current circuit is obtained, and the sum of the values of the corrected current attenuation coefficients in each branch is calculated; Based on the sum of the values and the number of branches, the isolation effect evaluation value of the isolated common cathode current circuit is calculated.

10. An isolated common cathode current circuit, comprising: The circuit test data is processed by the isolated common cathode current circuit test method according to any one of claims 1-9, the isolated common cathode current circuit 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 the flipped pulse width modulation signal is transmitted to the current output module through the filter circuit and the constant current circuit, the isolated common cathode current circuit further includes a data processing module, the data processing module is used for receiving input pulse width modulation signal, then transmitting the pulse width modulation signal to the digital isolation circuit, and collecting circuit test data of each part of the digital isolation circuit, the filter circuit, the constant current circuit and the current output module.

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