Test method and related equipment for common mode insertion loss of hybrid EMI filters

Abstract

The present application provides a test method and related equipment for the common-mode insertion loss of a hybrid EMI filter. The method adopts a combination of testing and theoretical calculation to test and calculate the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter, respectively, so as to obtain the insertion loss of the hybrid EMI filter, and realize the accurate measurement and evaluation of the common-mode insertion loss of the hybrid EMI filter. The present application fully considers the influence of the sampling link on the main circuit in the active EMI filter and the influence of the passive EMI filter on the active EMI filter, so that the calculated insertion loss is more in line with reality. At the same time, the present application equivalently establishes a simulation model of the hybrid EMI filter, which is suitable for guiding the design of the hybrid EMI filter.

Description

Technical Field

[0001] The present application relates to the technical field of EMI filters, and in particular to a method for testing the common-mode insertion loss of a hybrid EMI filter and related equipment. Background Art

[0002] At present, power converters are developing in the direction of miniaturization, high frequency, and high power density. In order to pass the strict electromagnetic compatibility standards, power converters are usually equipped with electromagnetic interference EMI (Electromagnetic Interference) filters. However, the insertion loss of EMI filters in low frequency bands is generally much smaller than its insertion loss in medium and high frequency bands. In order to improve the insertion loss in low frequency bands, the values ​​of filter inductors and filter capacitors are usually increased, resulting in larger volumes of inductors and capacitors. Therefore, the volume of EMI filter components has become one of the bottlenecks restricting its high power density.

[0003] Active EMI filters are based on the principle of active compensation. They offset electromagnetic interference in the circuit by injecting a compensation signal with equal amplitude and opposite phase to the interference signal, thereby reducing EMI. Active EMI filters do not require large inductors and can provide greater insertion losses in the medium and low frequency bands. Hybrid EMI filters are composed of passive and active EMI filters. They can combine the advantages of active and passive EMI filters and provide greater insertion losses in the full frequency band. Their applications are becoming more and more extensive. The insertion loss of a hybrid EMI filter is not a simple addition of the insertion losses of passive and active EMI filters. When designing or selecting a hybrid EMI filter, it is necessary to evaluate the insertion loss of the hybrid EMI filter. However, the current evaluation method is not accurate enough, so it is difficult to design or select a suitable and effective EMI filter. Summary of the invention

[0004] In view of this, the purpose of the present application is to propose a test method and related equipment for common-mode insertion loss of a hybrid EMI filter.

[0005] Based on the above purpose, the present application provides a method for testing the common-mode insertion loss of a hybrid EMI filter, wherein the hybrid EMI filter includes an active EMI filter and a passive EMI filter, wherein the input end of the passive EMI filter is connected to an equivalent interference source, the output end of the passive EMI filter is connected to the input end of the active EMI filter, and the output end of the active EMI filter is connected to a load, comprising:

[0006] Building an equivalent circuit of the active EMI filter in an open-loop state, and obtaining the open-loop gain of the active EMI filter at each frequency point within a preset frequency range by injecting a signal into the input end of the active EMI filter;

[0007] Obtaining input impedance and output impedance of the active EMI filter in an offline state;

[0008] By short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, the passive EMI filter is converted into a two-port network, and the impedance matrix of the passive EMI filter is obtained by testing;

[0009] Building an equivalent circuit of the active EMI filter in a closed-loop state, obtaining the source impedance of the active EMI filter by calculation based on the impedance matrix and the equivalent source impedance of the hybrid EMI filter, and obtaining the closed-loop gain of the active EMI filter by calculation based on the open-loop gain, the source impedance of the active EMI filter, the load impedance, the input impedance, and the output impedance;

[0010] Based on the closed-loop gain of the active EMI filter, the source impedance of the active EMI filter, the load impedance and the input impedance, an insertion loss of the active EMI filter is obtained by calculation;

[0011] Performing equivalent impedance transformation on the active EMI filter, making the active EMI filter and the load equivalent to the load impedance of the passive EMI filter, and obtaining the load impedance of the passive EMI filter by calculation based on the input impedance, the closed-loop gain of the active EMI filter and the load impedance;

[0012] Based on the equivalent source impedance of the hybrid EMI filter, the load impedance of the passive EMI filter and the impedance matrix, the insertion loss of the passive EMI filter is obtained by calculation;

[0013] The insertion loss of the hybrid EMI filter is obtained by calculation based on the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter.

[0014] Furthermore, the equivalent circuit of the active EMI filter in the open-loop state is constructed, and the open-loop gain of the active EMI filter at each frequency point within a preset frequency range is obtained by injecting a signal into the input end of the active EMI filter, including:

[0015] A single-frequency sine wave signal is injected into the input end of the active EMI filter through a signal generator, a 50Ω resistor is connected to the output end of the active EMI filter, and an oscilloscope or a spectrum analyzer is used to detect the current at the input end and the output end of the active EMI filter, respectively, to obtain the current at the input end and the current at the output end;

[0016] Based on the amplitude ratio and phase difference between the current at the input end and the current at the output end, the gain of the active EMI filter at the single frequency is obtained by calculation;

[0017] The frequency of the sinusoidal wave signal output by the signal generator is converted within the preset frequency range, the gain of the active EMI filter at each frequency point within the preset frequency range is tested and calculated respectively, and all gains corresponding to all frequency points within the preset frequency range are used as the open-loop gain of the active EMI filter within the preset frequency range.

[0018] Furthermore, the preset frequency range is 150kHz-30MHz.

[0019] Further, obtaining the input impedance and output impedance of the active EMI filter in an offline state includes:

[0020] Connecting an impedance analyzer to the input end of the active EMI filter, and obtaining the input impedance of the active EMI filter in an offline state through testing;

[0021] An impedance analyzer is connected to the output end of the active EMI filter, and the output impedance of the active EMI filter in an offline state is obtained through testing.

[0022] Further, the passive EMI filter is converted into a two-port network by short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, and the impedance matrix of the passive EMI filter is obtained by testing, including:

[0023] The input phase line and the ground line form an input port, the output phase line and the ground line form an output port, and a vector network analyzer is used to test the Z impedance parameter Z of the passive EMI filter. 11 , Z 12 , Z 21 , Z 22 , the Z impedance parameter satisfies the following relationship:

[0024] U 1 =Z 11 I 1 +Z 12 I 2

[0025] U 2 =Z 21 I 1 +Z 22 I 2

[0026] Among them, U 1is the voltage of the input port, U 2 is the voltage of the output port, I 1 is the current of the input port, I 2 is the current of the output port.

[0027] Furthermore, the source impedance of the active EMI filter is expressed as

[0028]

[0029] Among them, Z 11 , Z 12 , Z 21 , Z 22 is the impedance matrix parameter, Z s is the equivalent source impedance of the hybrid EMI filter.

[0030] Furthermore, the load impedance of the passive EMI filter is expressed as

[0031]

[0032] Among them, Z′ L represents the load impedance of the passive EMI filter, Z L represents the load impedance, Z i represents the input impedance, G 1 represents the closed-loop gain of the active EMI filter.

[0033] Based on the same inventive concept, the present application also provides a test device for common-mode insertion loss of a hybrid EMI filter, wherein the hybrid EMI filter comprises an active EMI filter and a passive EMI filter, wherein the input end of the passive EMI filter is connected to an equivalent interference source, the output end of the passive EMI filter is connected to the input end of the active EMI filter, and the output end of the active EMI filter is connected to a load, comprising:

[0034] An open-loop gain test module is configured to build an equivalent circuit of the active EMI filter in an open-loop state, and obtain the open-loop gain of each frequency point of the active EMI filter within a preset frequency range by injecting a signal into the input end of the active EMI filter;

[0035] An offline impedance testing module, configured to obtain the input impedance and output impedance of the active EMI filter in an offline state;

[0036] An impedance matrix parameter determination module is configured to convert the passive EMI filter into a two-port network by short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, and obtain the impedance matrix of the passive EMI filter through testing;

[0037] a closed-loop gain calculation module, configured to construct an equivalent circuit of the active EMI filter in a closed-loop state, obtain the source impedance of the active EMI filter by calculation based on the impedance matrix and the equivalent source impedance of the hybrid EMI filter, and obtain the closed-loop gain of the active EMI filter by calculation based on the open-loop gain, the source impedance of the active EMI filter, the load impedance, the input impedance and the output impedance;

[0038] An active EMI filter insertion loss determination module, configured to obtain the insertion loss of the active EMI filter by calculation based on the closed-loop gain of the active EMI filter, the source impedance of the active EMI filter, the load impedance and the input impedance;

[0039] A load impedance determination module is configured to perform an equivalent impedance transformation on the active EMI filter, to make the active EMI filter and the load equivalent to the load impedance of the passive EMI filter, and to obtain the load impedance of the passive EMI filter by calculation based on the input impedance, the closed-loop gain of the active EMI filter and the load impedance;

[0040] A passive EMI filter insertion loss determination module is configured to obtain the insertion loss of the passive EMI filter by calculation based on the equivalent source impedance of the hybrid EMI filter, the load impedance of the passive EMI filter and the impedance matrix;

[0041] The hybrid EMI filter insertion loss determination module is configured to obtain the insertion loss of the hybrid EMI filter by calculation based on the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter.

[0042] Based on the same inventive concept, the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable by the processor, wherein the processor implements the method as described above when executing the computer program.

[0043] Based on the same inventive concept, the present application also provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions are used to enable a computer to execute the method as described above.

[0044] As can be seen from the above, the test method and related equipment for the common-mode insertion loss of the hybrid EMI filter provided by the present application adopt a method combining testing with theoretical calculation, and respectively test and calculate the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter, so as to obtain the insertion loss of the hybrid EMI filter, and realize the accurate measurement and evaluation of the common-mode insertion loss of the hybrid EMI filter. The present application fully considers the influence of the sampling link on the main circuit in the active EMI filter and the influence of the passive EMI filter on the active EMI filter, so that the calculated insertion loss is more in line with reality. At the same time, the present application equivalently establishes a simulation model of the hybrid EMI filter, which is suitable for guiding the design of the hybrid EMI filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 A schematic diagram of the structure of a hybrid EMI filter according to an embodiment of the present application;

[0047] Figure 2 A flow chart of a method for testing common-mode insertion loss of a hybrid EMI filter according to an embodiment of the present application;

[0048] Figure 3 An equivalent circuit diagram of an active EMI filter in an open-loop state according to an embodiment of the present application;

[0049] Figure 4 This is a circuit diagram for testing the input impedance of an active EMI filter according to an embodiment of the present application;

[0050] Figure 5 This is a circuit diagram for testing the output impedance of an active EMI filter according to an embodiment of the present application;

[0051] Figure 6 This is an equivalent circuit diagram of the active EMI filter in a closed-loop state according to an embodiment of the present application;

[0052] Figure 7 This is an equivalent impedance transformation circuit diagram of an active EMI filter according to an embodiment of the present application;

[0053] Figure 8 An equivalent circuit diagram of a passive EMI filter according to an embodiment of the present application;

[0054] Fig. 9A schematic diagram of the structure of a test device for common-mode insertion loss of a hybrid EMI filter according to an embodiment of the present application;

[0055] Fig.10 A schematic diagram of the structure of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0056] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0057] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0058] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0059] This application provides a method for testing the common-mode insertion loss of a hybrid EMI filter. Figure 1 The hybrid EMI filter includes an active EMI filter and a passive EMI filter, the input end of the passive EMI filter is connected to the equivalent interference source, the output end of the passive EMI filter is connected to the input end of the active EMI filter, and the output end of the active EMI filter is connected to the load, Figure 1 U s Represents the equivalent interference source, Z s represents the equivalent source impedance, Z LRepresents the equivalent load impedance. When the passive EMI filter and the active EMI filter are used in combination, the impedances of the passive EMI filter and the active EMI filter will be coupled with each other. On the one hand, the passive EMI filter affects the source impedance of the active EMI filter. On the other hand, the active EMI filter is equivalent to the load of the passive EMI filter. Therefore, the insertion loss of the hybrid EMI filter is not a simple addition of the insertion losses of the passive EMI filter and the active EMI filter. In this embodiment, the current sampling current detection type active EMI filter is used as an example for explanation. Figure 2 , the method includes the following steps:

[0060] Step S101: construct an equivalent circuit of the active EMI filter in an open-loop state, and obtain the open-loop gain of the active EMI filter at each frequency point within a preset frequency range by injecting a signal into the input end of the active EMI filter.

[0061] Specifically, refer to Figure 3 This is an open-loop gain test system for active EMI filters. Active EMI filters usually consist of sampling, amplification, and injection. The power positive interface V cc and the negative power supply interface V ee Connect the corresponding positive and negative DC power supplies respectively, connect the active EMI filter sampling link (input end) to the signal generator, and connect the injection link (output end) to the standard 50Ω resistor. R is the sampling resistor, C inj is the injection capacitor, and A is the operational amplifier. The signal is input into the test system through the signal generator, and then the current in the sampling link and the injection link is collected by the oscilloscope in conjunction with the current clamp, and then the open-loop gain of the active EMI filter is calculated.

[0062] Step S102: Obtain the input impedance and output impedance of the active EMI filter in an offline state.

[0063] Specifically, when the active EMI filter samples the common-mode current in the main circuit, it is equivalent to connecting a current sensor in the main circuit, which will have a certain impact on the main circuit. In addition, the injection circuit of the active EMI filter has different injection effects under different main circuit characteristics. Therefore, it is necessary to consider the actual characteristics of the active EMI filter sampling circuit (input end) and the injection circuit (output end). In this embodiment, when the active EMI filter is powered off, the input impedance and output impedance of the active EMI filter are tested.

[0064] Step S103: Short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, converting the passive EMI filter into a two-port network, and obtaining the impedance matrix of the passive EMI filter through testing.

[0065] Specifically, the input phase line and the ground line form an input port, the output phase line and the ground line form an output port, and a vector network analyzer is used to test the Z impedance parameter Z of the passive EMI filter. 11 , Z 12 , Z 21 , Z 22 , the Z impedance parameter satisfies the following relationship:

[0066] U 1 =Z 11 I 1 +Z 12 I 2 (1)

[0067] U 2 =Z 21 I 1 +Z 22 I 2 (2) Among them, U 1 is the voltage of the input port, U 2 is the voltage of the output port, I 1 is the current of the input port, I 2 is the current of the output port.

[0068] Step S104, building an equivalent circuit of the active EMI filter in a closed-loop state, obtaining the source impedance of the active EMI filter by calculation based on the impedance matrix and the equivalent source impedance of the hybrid EMI filter, and obtaining the closed-loop gain of the active EMI filter by calculation based on the open-loop gain, the source impedance of the active EMI filter, the load impedance, the input impedance and the output impedance.

[0069] Specifically, when the passive EMI filter and the active EMI filter form a hybrid EMI filter, the passive EMI filter will also affect the injection efficiency of the active EMI filter, that is, the closed-loop gain of the active EMI filter is different from the open-loop gain. The equivalent circuit of the active EMI filter in the closed-loop situation is as follows: Figure 6 As shown in the figure, Z s ′ represents the equivalent impedance of the interference source and the port equivalent impedance of the passive EMI filter, that is, the source impedance of the active EMI filter, Z i represents the input impedance, Z L Represents the load impedance. The sampling current I 0Input, after passing through the current-controlled current source, the output current becomes G 1 I 0 , G 1 Represents the closed-loop gain of the active EMI filter.

[0070] In some embodiments, the source impedance of the active EMI filter is expressed as

[0071]

[0072] Among them, Z 11 , Z 12 , Z 21 , Z 22 represents the impedance matrix parameters, Z s The closed-loop gain G of the active EMI filter is derived from formula (3): 1 for

[0073]

[0074] Among them, Z inj Represents the output impedance, Z L represents the load impedance, Z i represents the input impedance, and G represents the open-loop gain of the active EMI filter.

[0075] In other embodiments, the input impedance Z of the active EMI filter is i Very small, the source impedance Z of the current sampling current injection type active EMI filter s ' is much larger than the load impedance Z L , its closed-loop gain G 1 Approximately equal to the open-loop gain G.

[0076] Step S105: obtaining the insertion loss of the active EMI filter by calculation based on the closed-loop gain of the active EMI filter, the source impedance of the active EMI filter, the load impedance and the input impedance.

[0077] Specifically, the interference source is connected to the active EMI filter after the passive EMI filter. For the active EMI filter, the passive EMI filter can be equivalent to the source impedance of the active EMI filter. Therefore, the actual insertion loss IL of the active EMI filter can be obtained. AEF for

[0078]

[0079] Among them, Z L represents the load impedance, Z i represents the input impedance, G1 represents the closed-loop gain of the active EMI filter, Z s ' represents the source impedance of the active EMI filter. The actual insertion loss IL of the above active EMI filter is AEF The calculation takes into account the active EMI filter input impedance Z i Impact on insertion loss, source impedance Z of active EMI filters s ′ changes, closed-loop gain G 1 measurement and calculation.

[0080] Step S106: performing equivalent impedance transformation on the active EMI filter, making the active EMI filter and the load equivalent to the load impedance of the passive EMI filter, and obtaining the load impedance of the passive EMI filter by calculation based on the input impedance, the closed-loop gain of the active EMI filter and the load impedance.

[0081] Specifically, Figure 7 The figure shows the equivalent impedance circuit of the active EMI filter. The active EMI filter is connected to the output end of the passive EMI filter. For the passive EMI filter, the active EMI filter can be equivalent to the load impedance of the passive EMI filter. In addition, the influence of the active EMI filter sampling circuit on the main voltage can be equivalent to the sampling resistor connected in series. Based on the idea of ​​port equivalence, the active EMI filter is transformed into an equivalent impedance, and the equivalent impedance is obtained from the interference source side. The active EMI filter and the original load are equivalent to the load impedance of the passive EMI filter, and the equivalent load impedance of the passive EMI filter can be derived.

[0082] In some embodiments, the load impedance of the passive EMI filter is expressed as

[0083]

[0084] Among them, Z′ L represents the load impedance of the passive EMI filter, Z L represents the load impedance, Z i represents the input impedance, G 1 represents the closed-loop gain of the active EMI filter.

[0085] Step S107: obtaining the insertion loss of the passive EMI filter by calculation based on the equivalent source impedance of the hybrid EMI filter, the load impedance of the passive EMI filter and the impedance matrix.

[0086] Specifically, the equivalent circuit after the passive EMI filter is connected is as follows Figure 8 As shown in the figure, Z′ Lis the equivalent impedance of the active EMI filter and the load, that is, the load impedance of the passive EMI filter. Based on formula (1), formula (2), Kirchhoff's voltage law, and Kirchhoff's current law, the insertion loss IL of the passive EMI filter can be derived: PEF The expression is

[0087]

[0088] Among them, Z 11 , Z 12 , Z 21 , Z 22 is the impedance matrix parameter, Z s is the equivalent source impedance of the hybrid EMI filter.

[0089] Step S108: obtaining the insertion loss of the hybrid EMI filter by calculation based on the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter.

[0090] Specifically, by combining formula (5) and formula (7), the insertion loss IL of the hybrid EMI filter can be obtained:

[0091] IL=IL AEF +IL PEF (8) Among them, IL AEF Indicates the actual insertion loss of the active EMI filter, IL PEF Represents the passive EMI filter insertion loss.

[0092] In some embodiments, the equivalent circuit of the active EMI filter in an open-loop state is constructed, and an open-loop gain of the active EMI filter at each frequency point within a preset frequency range is obtained by injecting a signal into an input terminal of the active EMI filter, including:

[0093] A single-frequency sine wave signal is injected into the input end of the active EMI filter through a signal generator, a 50Ω resistor is connected to the output end of the active EMI filter, and an oscilloscope or a spectrum analyzer is used to detect the current at the input end and the output end of the active EMI filter, respectively, to obtain the current at the input end and the current at the output end;

[0094] Based on the amplitude ratio and phase difference between the current at the input end and the current at the output end, the gain of the active EMI filter at the single frequency is obtained by calculation;

[0095] The frequency of the sinusoidal wave signal output by the signal generator is converted within the preset frequency range, the gain of the active EMI filter at each frequency point within the preset frequency range is tested and calculated respectively, and all gains corresponding to all frequency points within the preset frequency range are used as the open-loop gain of the active EMI filter within the preset frequency range, and the open-loop gain is G.

[0096] In some embodiments, the preset frequency range is 150kHz-30MHz.

[0097] In other embodiments, the preset frequency range can be adjusted according to actual conditions, and the data range is not specifically limited.

[0098] In some embodiments, obtaining the input impedance and output impedance of the active EMI filter in an offline state includes: connecting an impedance analyzer to the input end of the active EMI filter, and obtaining the input impedance of the active EMI filter in an offline state through testing; connecting an impedance analyzer to the output end of the active EMI filter, and obtaining the output impedance of the active EMI filter in an offline state through testing.

[0099] Specifically, Figure 4 As shown in Figure 1, when testing the input impedance, connect the impedance analyzer to the input end of the active EMI filter, and the test result is recorded as Zi. Figure 5 As shown in the figure, when testing the output impedance, connect the impedance analyzer to the output end of the active EMI filter and record the test result as Z inj .

[0100] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or server. The method of this embodiment can also be applied to a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the described method.

[0101] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0102] Based on the same inventive concept, corresponding to any of the above-mentioned embodiment methods, the present application also provides a testing device for the common-mode insertion loss of a hybrid EMI filter.

[0103] refer to Fig. 9 , a test device for common-mode insertion loss of the hybrid EMI filter, wherein the hybrid EMI filter comprises an active EMI filter and a passive EMI filter, wherein the input end of the passive EMI filter is connected to an equivalent interference source, the output end of the passive EMI filter is connected to the input end of the active EMI filter, and the output end of the active EMI filter is connected to a load, comprising:

[0104] The open-loop gain test module 901 is configured to build an equivalent circuit of the active EMI filter in an open-loop state, and obtain the open-loop gain of each frequency point of the active EMI filter within a preset frequency range by injecting a signal into the input end of the active EMI filter;

[0105] An offline impedance testing module 902 is configured to obtain the input impedance and output impedance of the active EMI filter in an offline state;

[0106] The impedance matrix parameter determination module 903 is configured to convert the passive EMI filter into a two-port network by short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, and obtain the impedance matrix of the passive EMI filter through testing;

[0107] A closed-loop gain calculation module 904 is configured to build an equivalent circuit of the active EMI filter in a closed-loop state, obtain the source impedance of the active EMI filter by calculation based on the impedance matrix and the equivalent source impedance of the hybrid EMI filter, and obtain the closed-loop gain of the active EMI filter by calculation based on the open-loop gain, the source impedance of the active EMI filter, the load impedance, the input impedance, and the output impedance;

[0108] An active EMI filter insertion loss determination module 905 is configured to obtain the insertion loss of the active EMI filter by calculation based on the closed-loop gain of the active EMI filter, the source impedance of the active EMI filter, the load impedance and the input impedance;

[0109] A load impedance determination module 906 is configured to perform an equivalent impedance transformation on the active EMI filter, to make the active EMI filter and the load equivalent to the load impedance of the passive EMI filter, and to obtain the load impedance of the passive EMI filter by calculation based on the input impedance, the closed-loop gain of the active EMI filter and the load impedance;

[0110] A passive EMI filter insertion loss determination module 907 is configured to obtain the insertion loss of the passive EMI filter by calculation based on the equivalent source impedance of the hybrid EMI filter, the load impedance of the passive EMI filter and the impedance matrix;

[0111] The hybrid EMI filter insertion loss determination module 908 is configured to obtain the insertion loss of the hybrid EMI filter by calculation based on the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter.

[0112] For the convenience of description, the above device is described in terms of functions divided into various modules. Of course, when implementing the present application, the functions of each module can be implemented in the same or multiple software and / or hardware.

[0113] The device of the above embodiment is used to implement the test method of common-mode insertion loss of the hybrid EMI filter corresponding to any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be repeated here.

[0114] Based on the same inventive concept, corresponding to any of the above-mentioned embodiments and methods, the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for testing the common-mode insertion loss of the hybrid EMI filter described in any of the above embodiments is implemented.

[0115] Fig.10 A more specific schematic diagram of the hardware structure of an electronic device provided in this embodiment is shown, and the device may include: a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040, and a bus 1050. The processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040 are connected to each other through the bus 1050 in the device.

[0116] The processor 1010 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0117] The memory 1020 may be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 1020 may store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant program codes are stored in the memory 1020 and are called and executed by the processor 1010.

[0118] The input / output interface 1030 is used to connect the input / output module to realize information input and output. The input / output module can be configured in the device as a component (not shown in the figure), or it can be externally connected to the device to provide corresponding functions. The input device may include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device may include a display, a speaker, a vibrator, an indicator light, etc.

[0119] The communication interface 1040 is used to connect a communication module (not shown) to realize communication interaction between the device and other devices. The communication module can realize communication through a wired mode (such as USB, network cable, etc.) or a wireless mode (such as mobile network, WIFI, Bluetooth, etc.).

[0120] The bus 1050 includes a path that transmits information between the various components of the device (eg, the processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040).

[0121] It should be noted that, although the above device only shows the processor 1010, the memory 1020, the input / output interface 1030, the communication interface 1040 and the bus 1050, in the specific implementation process, the device may also include other components necessary for normal operation. In addition, it can be understood by those skilled in the art that the above device may also only include the components necessary for implementing the embodiments of the present specification, and does not necessarily include all the components shown in the figure.

[0122] The electronic device of the above embodiment is used to implement the test method of common-mode insertion loss of the corresponding hybrid EMI filter in any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be repeated here.

[0123] Based on the same inventive concept, corresponding to any of the above-mentioned embodiment methods, the present application also provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the test method for the common-mode insertion loss of the hybrid EMI filter as described in any of the above embodiments.

[0124] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device.

[0125] The computer instructions stored in the storage medium of the above embodiment are used to enable the computer to execute the test method for common-mode insertion loss of the hybrid EMI filter as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0126] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0127] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present application difficult to understand, the known power supply / ground connection with the integrated circuit (IC) chip and other components may or may not be shown in the provided drawings. In addition, the device can be shown in the form of a block diagram to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform to be implemented in the embodiments of the present application (that is, these details should be fully within the scope of understanding of those skilled in the art). In the case of elaborating specific details (e.g., circuits) to describe exemplary embodiments of the present application, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details or when these specific details are changed. Therefore, these descriptions should be considered to be illustrative rather than restrictive.

[0128] Although the present application has been described in conjunction with specific embodiments of the present application, many replacements, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed.

[0129] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.

Claims

1. A method for testing common-mode insertion loss of a hybrid EMI filter, wherein the hybrid EMI filter comprises an active EMI filter and a passive EMI filter, wherein the input end of the passive EMI filter is connected to an equivalent interference source, the output end of the passive EMI filter is connected to the input end of the active EMI filter, and the output end of the active EMI filter is connected to a load. It is characterized in that include: Building an equivalent circuit of the active EMI filter in an open-loop state, and obtaining the open-loop gain of the active EMI filter at each frequency point within a preset frequency range by injecting a signal into the input end of the active EMI filter; Obtaining input impedance and output impedance of the active EMI filter in an offline state; By short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, the passive EMI filter is converted into a two-port network, and the impedance matrix of the passive EMI filter is obtained by testing; Building an equivalent circuit of the active EMI filter in a closed-loop state, obtaining the source impedance of the active EMI filter by calculation based on the impedance matrix and the equivalent source impedance of the hybrid EMI filter, and obtaining the closed-loop gain of the active EMI filter by calculation based on the open-loop gain, the source impedance of the active EMI filter, the load impedance, the input impedance, and the output impedance; Based on the closed-loop gain of the active EMI filter, the source impedance of the active EMI filter, the load impedance and the input impedance, the insertion loss IL of the active EMI filter is obtained by calculation. AEF , Among them, Z L represents the load impedance, Z i represents the input impedance, G 1 represents the closed-loop gain of the active EMI filter, Z s ' represents the source impedance of the active EMI filter; Performing equivalent impedance transformation on the active EMI filter, making the active EMI filter and the load equivalent to the load impedance of the passive EMI filter, and obtaining the load impedance of the passive EMI filter by calculation based on the input impedance, the closed-loop gain of the active EMI filter and the load impedance; Based on the equivalent source impedance of the hybrid EMI filter, the load impedance of the passive EMI filter and the impedance matrix, the insertion loss IL of the passive EMI filter is obtained by calculation. PEF , Among them, Z L represents the load impedance, Z i represents the input impedance, G 1 represents the closed-loop gain of the active EMI filter, Z s ' represents the source impedance of the active EMI filter; The insertion loss of the hybrid EMI filter is obtained by calculation based on the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter.

2. The test method according to claim 1, It is characterized in that The equivalent circuit of the active EMI filter in an open-loop state is constructed, and an open-loop gain of the active EMI filter at each frequency point within a preset frequency range is obtained by injecting a signal into an input end of the active EMI filter, including: A single-frequency sine wave signal is injected into the input end of the active EMI filter through a signal generator, a 50Ω resistor is connected to the output end of the active EMI filter, and an oscilloscope or a spectrum analyzer is used to detect the current at the input end and the output end of the active EMI filter, respectively, to obtain the current at the input end and the current at the output end; Based on the amplitude ratio and phase difference between the current at the input end and the current at the output end, the gain of the active EMI filter at the single frequency is obtained by calculation; The frequency of the sinusoidal wave signal output by the signal generator is converted within the preset frequency range, the gain of the active EMI filter at each frequency point within the preset frequency range is tested and calculated respectively, and all gains corresponding to all frequency points within the preset frequency range are used as the open-loop gain of the active EMI filter within the preset frequency range.

3. The test method according to claim 1 or 2, It is characterized in that The preset frequency range is 150kHz-30MHz.

4. The test method according to claim 1 or 2, It is characterized in that Obtaining the input impedance and output impedance of the active EMI filter in an offline state, including: Connecting an impedance analyzer to the input end of the active EMI filter, and obtaining the input impedance of the active EMI filter in an offline state through testing; An impedance analyzer is connected to the output end of the active EMI filter, and the output impedance of the active EMI filter in an offline state is obtained through testing.

5. The test method according to claim 1 or 2, It is characterized in that The method converts the passive EMI filter into a two-port network by short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, and obtains the impedance matrix of the passive EMI filter by testing, including: The input phase line and the ground line form an input port, the output phase line and the ground line form an output port, and a vector network analyzer is used to test the Z impedance parameter Z of the passive EMI filter. 11 , Z 12 , Z 21 , Z 22 , the Z impedance parameter satisfies the following relationship: U 1 =Z 11 ·I 1 +Z 12 ·I 2 U 2 =Z 21 ·I 1 +Z 22 ·I 2 Among them, U 1 is the voltage of the input port, U 2 is the voltage of the output port, I 1 is the current of the input port, I 2 is the current of the output port.

6. The test method according to claim 1 or 2, It is characterized in that The source impedance of the active EMI filter is expressed as Among them, Z 11 , Z 12 , Z 21 , Z 22 is the impedance matrix parameter, Z s is the equivalent source impedance of the hybrid EMI filter.

7. The test method according to claim 1 or 2, It is characterized in that The load impedance of the passive EMI filter is expressed as Among them, Z′ L represents the load impedance of the passive EMI filter, Z L represents the load impedance, Z i represents the input impedance, G 1 represents the closed-loop gain of the active EMI filter.

8. A test device for common-mode insertion loss of a hybrid EMI filter, the hybrid EMI filter comprising an active EMI filter and a passive EMI filter, the input end of the passive EMI filter being connected to an equivalent interference source, the output end of the passive EMI filter being connected to the input end of the active EMI filter, and the output end of the active EMI filter being connected to a load, It is characterized in that include: An open-loop gain test module is configured to build an equivalent circuit of the active EMI filter in an open-loop state, and obtain the open-loop gain of each frequency point of the active EMI filter within a preset frequency range by injecting a signal into the input end of the active EMI filter; An offline impedance testing module, configured to obtain the input impedance and output impedance of the active EMI filter in an offline state; An impedance matrix parameter determination module is configured to convert the passive EMI filter into a two-port network by short-circuiting the input phase line and the output phase line of the passive EMI filter respectively, and obtain the impedance matrix of the passive EMI filter through testing; a closed-loop gain calculation module, configured to construct an equivalent circuit of the active EMI filter in a closed-loop state, obtain the source impedance of the active EMI filter by calculation based on the impedance matrix and the equivalent source impedance of the hybrid EMI filter, and obtain the closed-loop gain of the active EMI filter by calculation based on the open-loop gain, the source impedance of the active EMI filter, the load impedance, the input impedance and the output impedance; The active EMI filter insertion loss determination module is configured to obtain the insertion loss IL of the active EMI filter by calculation based on the closed-loop gain of the active EMI filter, the source impedance of the active EMI filter, the load impedance and the input impedance. AEF , Among them, Z L represents the load impedance, Z i represents the input impedance, G 1 represents the closed-loop gain of the active EMI filter, Z s ' represents the source impedance of the active EMI filter; A load impedance determination module is configured to perform an equivalent impedance transformation on the active EMI filter, to make the active EMI filter and the load equivalent to the load impedance of the passive EMI filter, and to obtain the load impedance of the passive EMI filter by calculation based on the input impedance, the closed-loop gain of the active EMI filter and the load impedance; The passive EMI filter insertion loss determination module is configured to obtain the insertion loss IL of the passive EMI filter by calculation based on the equivalent source impedance of the hybrid EMI filter, the load impedance of the passive EMI filter and the impedance matrix. PEF , Among them, Z L represents the load impedance, Z i represents the input impedance, G 1 represents the closed-loop gain of the active EMI filter, Z s ' represents the source impedance of the active EMI filter; The hybrid EMI filter insertion loss determination module is configured to obtain the insertion loss of the hybrid EMI filter by calculation based on the insertion loss of the active EMI filter and the insertion loss of the passive EMI filter.

9. An electronic device, It is characterized in that The method comprises a memory, a processor, and a computer program stored in the memory and executable by the processor, wherein the processor implements the method according to any one of claims 1 to 7 when executing the computer program.

10. A non-transitory computer-readable storage medium, It is characterized in that The non-transitory computer-readable storage medium stores computer instructions for causing a computer to execute the method according to any one of claims 1 to 7.

Images