A method for evaluating the suppression effect of filter devices based on signal feature calculation

Abstract

The embodiment of the present invention discloses a method for evaluating the suppression effect of a filter device based on signal feature calculation, which relates to the field of signal testing technology. The method includes: obtaining an input signal to be evaluated and a distorted signal generated after the input signal passes through the filter device; respectively calculating the maximum value, minimum value, signal energy and trend correlation of the waveforms of the input signal and the distorted signal in the time domain; forming a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy and trend correlation of the input signal and the distorted signal; and evaluating the suppression effect of the filter device based on the calculation result obtained by the disturbance similarity calculation formula. Through the scheme of the embodiment of the present invention, the suppression effect of the filter device can be evaluated in a quantitative manner.

Description

Technical Field

[0001] The present invention relates to the technical field of signal testing, and in particular to a method for evaluating the suppression effect of a filter device based on signal feature calculation. Background Art

[0002] The current national standard GB / T 7343-2017, "Measurement Method for the Suppression Characteristics of Passive EMC Filter Components," specifies the measurement methods for the insertion loss, impedance, and S-parameters of passive filter components. These three parameters are all tested in the frequency domain, and the measurement methods are similar. They can evaluate the suppression characteristics of filter components within a certain frequency band, but cannot directly and effectively determine the filter component's suppression effect on time-domain interference signals.

[0003] The standard test method uses a calibrated 50Ω signal generator and a 50Ω receiver. The insertion loss is given by the following formula:

[0004] a e =20log(V0 / 2V2)

[0005] a e Insertion loss, in decibels (dB)

[0006] V0 is the open circuit voltage of the 50Ω signal generator, in volts (V)

[0007] V2 is the output voltage of the filter device, in volts (V)

[0008] Insertion loss test block diagram is as follows Figure 2 As shown in the figure, G is the signal source, FI is the filter element, and R is the receiver. Without bias current, the applicable frequency range is 10kHz to 10GHz; with bias current (up to 100A), the applicable frequency range is 10kHz to 100MHz.

[0009] With the development of science and technology, electronic equipment has become more and more integrated and modularized, and is facing the influence of more complex electromagnetic environment effects. Various types of signal cable ports are facing the intrusion of interference signals from complex electromagnetic environments. Filter components have become one of the necessary key components of the equipment, and the evaluation of the suppression effect of filter components has also received more and more attention from users.

[0010] The existing standard GB / T 7343-2017, "Method for measuring the rejection characteristics of passive EMC filter components," states that because the terminal impedance during the measurement process differs from the terminal impedance in the actual device or system, the characteristics obtained using the standard's unbiased insertion loss measurement method may differ from the actual characteristics. To address the challenges currently faced by passive filter components, the following technical issues need to be addressed:

[0011] 1. During the product design phase, due to the lack of quantitative indicators for the suppression effect of filter components, in many cases, equipment manufacturers can only first select several suitable filter components based on the insertion loss or cutoff frequency of the filter components, and then conduct actual tests in the laboratory to examine the suppression effect of the filter components on sensitive time domain interference signals. This will increase the design cost and time cost of equipment manufacturers;

[0012] 2. During the product finalization phase, individual differences in the suppression characteristics of filter components purchased in large quantities are difficult to detect, resulting in unqualified products during electromagnetic immunity testing;

[0013] 3. The passive filter component parameters specified in the standard include insertion loss, impedance and S parameters, which are all frequency domain parameters. When faced with time domain interference signals, the above parameters cannot directly evaluate the suppression effect of the filter component. Summary of the Invention

[0014] In view of this, an embodiment of the present invention provides a method for evaluating the suppression effect of a filter device based on signal feature calculation, which at least partially solves the problems existing in the prior art.

[0015] The embodiment of the present invention provides a method for evaluating the suppression effect of a filter device based on signal characteristic calculation.

[0016] Laws, including:

[0017] Acquire an input signal to be evaluated and a distorted signal generated after the input signal passes through a filter device;

[0018] Calculating the maximum value, minimum value, signal energy and trend correlation of the waveforms of the input signal and the distorted signal in the time domain respectively;

[0019] Based on the ratio of the maximum value, minimum value, signal energy and trend correlation of the input signal and the distorted signal, a disturbance similarity calculation formula is formed;

[0020] Based on the calculation result obtained by the disturbance similarity calculation formula, the suppression effect of the filter device is evaluated.

[0021] According to a specific implementation of the embodiment of the present disclosure, the disturbance similarity calculation formula is formed based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal, including:

[0022] The ratio of the distorted signal output by the filter to the signal energy of the input signal is recorded as S coef ;

[0023] Setting a first weight value N0 for the ratio of the signal energy of the distorted signal to the signal energy of the input signal;

[0024] N0*S coef The value of is used as the first calculation parameter of the similarity calculation formula.

[0025] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0026] The maximum value of the ratio of the distorted signal output by the filter to the input signal is recorded as MAX. coef ;

[0027] Setting a second weight value N1 for the maximum ratio of the distorted signal to the input signal;

[0028] N1*MAX coef The value of is used as the second calculation parameter of the similarity calculation formula.

[0029] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0030] The minimum value of the ratio of the distorted signal output by the filter to the input signal is recorded as MIN coef ;

[0031] Setting a third weight value N2 for the minimum ratio of the distorted signal to the input signal;

[0032] N2*MIN coef The value of is used as the third calculation parameter of the similarity calculation formula.

[0033] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0034] The trend correlation between the distorted signal output by the filter and the input signal is recorded as C coef ;

[0035] Setting a fourth weight value N3 for the trend correlation;

[0036] N3*C coef The value of is used as the fourth calculation parameter of the similarity calculation formula.

[0037] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0038] N0*S coef +N1*MAX coef +N2*MIN coef +N3*C coef The sum of sets the magnification F, (N0*S coef +N1*MAX coef +N2*MIN coef +N3*C coef The value of )*F is used as the final calculation result DS value of the similarity calculation formula.

[0039] According to a specific implementation of the embodiment of the present disclosure, the evaluating the suppression effect of the filter device based on the calculation result obtained by the disturbance similarity calculation formula includes:

[0040] Determine whether the DS value is greater than a preset threshold;

[0041] If so, it is determined that the suppression effect of the filter device meets the requirements.

[0042] According to a specific implementation of the embodiment of the present disclosure, the input signal is generated by a signal generator.

[0043] According to a specific implementation of the embodiment of the present disclosure, the input signal is a current waveform signal or a voltage waveform signal.

[0044] According to a specific implementation method of the embodiment of the present disclosure, when the input signal is a voltage waveform, the load size is arbitrarily adjusted to make it consistent with the actual installation of the filter device, and the final filtering suppression effect evaluation reflects the filtering suppression effect of the filter device in the actual installation environment.

[0045] The present invention provides a method for evaluating the suppression effect of a filtering device based on signal feature calculation, comprising obtaining an input signal to be evaluated and a distorted signal generated after the input signal passes through the filtering device; respectively calculating the maximum value, minimum value, signal energy, and trend correlation of the waveforms of the input signal and the distorted signal in the time domain; forming a disturbance similarity calculation formula based on a ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal; and evaluating the suppression effect of the filtering device based on a calculation result obtained by the disturbance similarity calculation formula. Compared with the existing technology, the solution of this application quantifies the characteristic values ​​of time-domain disturbance signals and summarizes them as evaluation parameters for the suppression effect of filter devices. The "disturbance similarity" test system proposes a time-domain measurement method for time-domain disturbance signals, which is different from the frequency-domain parameter measurement method summarized in the current standard. When the disturbance signal is a voltage waveform, the load size can be arbitrarily adjusted to make it consistent with the actual installation of the filter device. The final filter suppression effect evaluation can reflect the filter device's filtering suppression effect in the actual installation environment. The current standard measurement method can only meet the 50Ω test system, which is not consistent with the actual installation environment of the filter device and cannot evaluate the actual filtering suppression effect.

[0046] Compared with existing standard test methods, this solution has the following advantages:

[0047] 1. Quantitative evaluation of the time domain disturbance signal suppression effect of filter components

[0048] By replacing the receiver or network analyzer in the current standard with an oscilloscope and avoiding the conversion of the interference signal between the time domain and the frequency domain, the characteristics of the time domain interference signal can be obtained intuitively and efficiently, providing parameters for quantifying the suppression effect of the filter device on the time domain signal, and realizing the quantitative evaluation of the time domain interference signal suppression effect of the filter device.

[0049] 2. Simulate the actual installation environment of the filter components to evaluate the actual filtering suppression effect

[0050] In most cases, the time domain disturbance signal is a voltage waveform. In this case, the load size can be adjusted arbitrarily to make it consistent with the actual installation of the filter component. The final filter suppression evaluation can reflect the filter suppression effect of the filter component in the actual installation environment, providing a real and reliable selection basis for the subsequent selection of filter components, and eliminating the process of repeated verification tests in the experimental installation environment, thereby reducing time and testing costs for users. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 A schematic diagram of a method for evaluating the suppression effect of a filter device based on signal feature calculation provided by an embodiment of the present invention;

[0053] Figure 2 A block diagram of a test circuit for measuring insertion loss without bias provided by an embodiment of the present invention;

[0054] Figure 3 A time domain signal waveform diagram provided by an embodiment of the present invention;

[0055] Figure 4a-4b A schematic diagram of the test system layout provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0057] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0058] See also Figure 1 、 Figure 3 and Figure 4a and Figure 4b The present invention provides a set of filtering based on signal feature calculation

[0059] The device inhibition evaluation method comprises the following steps:

[0060] S101, obtaining an input signal to be evaluated and a distorted signal generated after the input signal passes through a filter device;

[0061] S102, respectively calculating the maximum value, minimum value, signal energy, and trend correlation of the waveforms of the input signal and the distorted signal in the time domain;

[0062] S103: forming a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation between the input signal and the distorted signal;

[0063] S104 : Evaluate the suppression effect of the filter device based on a calculation result obtained by the disturbance similarity calculation formula.

[0064] During steps S101 to S104, a disturbance test can be performed. In a time-domain disturbance test, the disturbance signal (input signal) will be distorted after passing through the filter. The magnitude of this waveform distortion determines the filter's ability to suppress interference. The similarity between the distorted waveform and the standard interference waveform can be used to evaluate the filter's suppression capability. This distorted waveform directly affects the device under test (EUT) connected after the filter, so the degree of "disturbance similarity" is directly related to the EUT's immunity to interference.

[0065] The requirements for suppression in the installation environment of the filter device include: the energy, amplitude and signal strength change rate of the input signal will have relevant parameter regulations. Therefore, the factors that have the greatest impact on the test device of the time domain interference signal are the energy of the interference signal, the maximum and minimum values ​​of the interference signal, and the trend correlation of the interference signal. Using the above three factors, the ratio of the output waveform parameters of the filter device to the input standard waveform parameters is used as the "disturbance similarity".

[0066] The signal energy and maximum and minimum values ​​of a time-domain signal are easily derived from the time-domain waveform. The correlation of disturbance signal trends utilizes the concept of cross-correlation. The cross-correlation coefficient represents the degree of correlation between two time series, specifically the correlation between the values ​​of signals x(t) and y(t) at any two different times t1 and t2. In fundamental signal analysis theory, the mathematical expectation of the product of two random variables is called correlation, which characterizes the degree of association between X and Y.

[0067]

[0068] The ratio of the signal energy of the filter output signal to the input standard signal is recorded as S coef The maximum value of the ratio of the output signal of the filter device to the input standard signal is recorded as MAX coef The minimum value ratio of the filter output signal to the input standard signal is recorded as MIN coef The trend correlation between the output signal of the filter device and the input standard signal is recorded as C coef , then the “harassment similarity” DS:

[0069] DS=(N0*S coef +N1*MAX coef +N2*MIN coef +N3*C coef )*F

[0070] N0, N1, N2, and N3 are the weights of different "harassment similarity" factors. Since the ratio may be too small, an amplification factor is set, denoted as F, to facilitate the comparison of DS values.

[0071] When evaluating a passive filter's ability to resist time-domain interference signals, a standard interference signal is input and the waveform of the interference signal output by the filter device is obtained. This determines the filter's DS value. A larger DS value indicates a higher similarity between the filter's output signal and the standard input signal, and a lower filtering effect. A smaller DS value indicates a higher filtering effect. This evaluation method is not only intuitive and efficient, but also allows for comparison of the filtering effects of different filter devices on the same interference signal, as well as for evaluating the filtering effects of the same filter device on different interference signals.

[0072] It is recommended that the signal generator be one that can generate the time domain interference signal of interest. It is recommended that the oscilloscope be one with a bandwidth of 500MHz or more. When the time domain interference signal is a voltage waveform, the load can use the impedance of the actual installation environment of the filter component. When the time domain interference signal is a current waveform, the load can use 50Ω.

[0073] During the test, you can follow Figure 4a and Figure 4b The test system is connected in the same way as above, but the filter device is not connected. The signal generator generates a time domain interference signal that meets the requirements, and the oscilloscope collects the standard interference signal.

[0074] Secondly, install the filter device to be tested into the test system (the filter device should be placed in a shielded metal box, and the ground of the filter device should be properly connected to the bottom of the metal box to ensure low-inductance grounding). The signal generator generates a time domain interference signal, and the oscilloscope collects the signal at the output of the filter device.

[0075] Perform a weighted analysis based on the actual installation environment requirements of the filter component, compare the characteristic parameters of the filter component output signal with those of the standard interference signal, and calculate the "interference similarity" according to the formula. Repeat the above test steps for different filter components to quantitatively compare different "interference similarities".

[0076] According to a specific implementation of the embodiment of the present disclosure, the disturbance similarity calculation formula is formed based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal, including:

[0077] The ratio of the distorted signal output by the filter to the signal energy of the input signal is recorded as S coef ;

[0078] Setting a first weight value N0 for the ratio of the signal energy of the distorted signal to the signal energy of the input signal;

[0079] N0*S coef The value of is used as the first calculation parameter of the similarity calculation formula.

[0080] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0081] The maximum value of the ratio of the distorted signal output by the filter to the input signal is recorded as MAX. coef ;

[0082] Setting a second weight value N1 for the maximum ratio of the distorted signal to the input signal;

[0083] N1*MAX coef The value of is used as the second calculation parameter of the similarity calculation formula.

[0084] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0085] The minimum value of the ratio of the distorted signal output by the filter to the input signal is recorded as MIN coef ;

[0086] Setting a third weight value N2 for the minimum ratio of the distorted signal to the input signal;

[0087] N2*MIN coef The value of is used as the third calculation parameter of the similarity calculation formula.

[0088] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0089] The trend correlation between the distorted signal output by the filter and the input signal is recorded as C coef ;

[0090] Setting a fourth weight value N3 for the trend correlation;

[0091] N3*C coef The value of is used as the fourth calculation parameter of the similarity calculation formula.

[0092] According to a specific implementation of the embodiment of the present disclosure, the formation of a disturbance similarity calculation formula based on the ratio of the maximum value, minimum value, signal energy, and trend correlation of the input signal and the distorted signal also includes:

[0093] N0*S coef +N1*MAX coef +N2*MIN coef +N3*C coef The sum of sets the magnification F, (N0*S coef +N1*MAX coef +N2*MIN coef +N3*C coef The value of )*F is used as the final calculation result DS value of the similarity calculation formula.

[0094] According to a specific implementation of the embodiment of the present disclosure, the evaluating the suppression effect of the filter device based on the calculation result obtained by the disturbance similarity calculation formula includes:

[0095] Determine whether the DS value is greater than a preset threshold;

[0096] If so, it is determined that the suppression effect of the filter device meets the requirements.

[0097] According to a specific implementation of the embodiment of the present disclosure, the input signal is generated by a signal generator.

[0098] According to a specific implementation of the embodiment of the present disclosure, the input signal is a current waveform signal or a voltage waveform signal.

[0099] According to a specific implementation method of the embodiment of the present disclosure, when the input signal is a voltage waveform, the load size is arbitrarily adjusted to make it consistent with the actual installation of the filter device, and the final filtering suppression effect evaluation reflects the filtering suppression effect of the filter device in the actual installation environment.

[0100] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device 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 device. 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 device comprising the element.

[0101] Each embodiment in this specification is described in a related manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0102] In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0103] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0104] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware or a combination thereof.

[0105] In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having logic gate circuits for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for evaluating the suppression effect of a filter device based on signal feature calculation, characterized in that: include: Acquire an input signal to be evaluated and a distorted signal generated after the input signal passes through a filter device; Respectively calculating the maximum value, minimum value, signal energy and trend correlation of the waveforms of the input signal and the distorted signal in the time domain; Based on the ratio of the maximum value, the minimum value, the signal energy and the trend correlation between the input signal and the distorted signal, a disturbance similarity DS calculation formula is formed; Based on the calculation result obtained by the disturbance similarity calculation formula, evaluating the suppression effect of the filter device; The calculation formula for forming the disturbance similarity DS based on the ratio of the input signal to the distorted signal in terms of maximum value, minimum value, signal energy and trend correlation includes: The ratio of the distorted signal output by the filter to the signal energy of the input signal is recorded as S coef ; Setting a first weight value N0 for the ratio of the signal energy of the distortion signal to the signal energy of the input signal; N0*S coef as the first calculation parameter of the similarity calculation formula; The ratio of the maximum value of the distorted signal output by the filter to the maximum value of the input signal is recorded as MAX. coef ; Setting a second weight value N1 for the maximum value ratio of the distortion signal to the input signal; N1*MAX coef as the second calculation parameter of the similarity calculation formula; The minimum value of the ratio of the distorted signal output by the filter device to the input signal is recorded as MIN coef ; Setting a third weight value N2 for the minimum value ratio of the distortion signal to the input signal; N2*MIN coef as the third calculation parameter of the similarity calculation formula; The trend correlation between the distorted signal output by the filter and the input signal is recorded as C coef ; Setting a fourth weight value N3 for the trend correlation; N3*C coef as the fourth calculation parameter of the similarity calculation formula; N0*S coef +N1*MAX coef +N2*MIN coef +N3*C coef The sum of sets the magnification F, and (N0*S coef +N1*MAX coef +N2*MIN coef +N3*C coef The value of )*F is used as the final calculation result DS value of the similarity calculation formula.

2. The method according to claim 1, characterized in that The step of evaluating the suppression effect of the filter device based on the calculation result obtained by the disturbance similarity calculation formula includes: Determine whether the DS value is greater than a preset threshold; If so, it is determined that the suppression effect of the filter device meets the requirements.

3. The method according to claim 1, characterized in that: The input signal is generated by a signal generator.

4. The method according to claim 1, characterized in that: The input signal is a current waveform signal or a voltage waveform signal.

5. The method according to claim 4, characterized in that: When the input signal is a voltage waveform, the load size is arbitrarily adjusted to make it consistent with the actual installation of the filter device. The final filter suppression effect evaluation reflects the filter suppression effect of the filter device in the actual installation environment.

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