An electromagnetic interference debugging method, device and system

Abstract

The application discloses a debugging method, device and system based on electromagnetic interference, comprising: obtaining EMI test data of a measured power conversion device under a specified test condition; identifying a target rectification frequency band and a key frequency point based on the EMI test data; mapping an exceeding degree of the target rectification frequency band and the key frequency point to a target impedance threshold value to generate a target frequency band impedance upper limit; constructing an impedance shaping network satisfying a constraint of the target impedance threshold value based on the target frequency band impedance upper limit, so that an equivalent impedance curve is not higher than a peak value of the target impedance threshold value in the target rectification frequency band; applying the impedance shaping network to the measured device and performing retesting, and if the retesting does not meet the limit value, updating the mapping or adjusting the impedance network combination until the limit value is met; and the application improves the efficiency and quality of EMC rectification.

Description

Technical Field

[0001] This invention relates to a method, apparatus, and system for debugging electromagnetic interference, belonging to the field of electromagnetic compatibility technology. Background Technology

[0002] With the increasing application of wide-bandgap power devices such as SiC and GaN in power supplies, inverters, DC / DC converters, vehicle electric drives, and grid energy storage PCS, the switching speed of these devices has significantly increased, leading to larger dv / dt and di / dt values. This results in a significant increase in conducted and radiated interference across a wider frequency range. Current EMC remediation in engineering practice typically employs the following methods: Trial-and-error remediation: After observing the out-of-limit frequency band during EMI testing, engineers rely on experience to replace / add / remove capacitors, inductors, RC dampers, or change wiring, repeating the test until the limits are met; Experience-based templates: Filters and damping networks are set based on past product experience, but this is sensitive to different hardware layouts, busbar parasitic parameters, and changes in device switching characteristics; Lack of reassurance: Even if a remediation passes, it is difficult to provide a reusable engineering explanation for "why low impedance can definitely be achieved in a certain frequency band," leading to difficulties in migrating between different batches and models.

[0003] The common problems with the above methods are: low efficiency (requiring multiple rounds of repeated testing / rework); poor predictability (the effects of component modifications are uncertain); non-reusability (difficulty in forming a standardized "rectification method library" across different products); and difficulty in establishing standard processes (unable to solidify the rectification process into a replicable method). Therefore, there is an urgent need for a systematic method that starts from test results, can formulate impedance design targets, and can ensure low impedance in the target frequency band, thereby improving the efficiency and quality of EMC rectification. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of low EMC debugging efficiency in existing technologies, and to provide a systematic method based on electromagnetic interference debugging methods, modules and systems that can form impedance design targets based on test results and ensure low impedance in the target frequency band, thereby improving the efficiency and quality of EMC rectification. To achieve the above objectives / to solve the above technical problems, the present invention is implemented using the following technical solution: First aspect: A debugging method based on electromagnetic interference, the method comprising: Obtain EMI test data of the power conversion device under test under specified test conditions; Based on the EMI test data, identify the target rectification frequency band and key frequency points; The degree of exceeding the standard of the target rectification frequency band and key frequency points is mapped to the target impedance threshold to generate the upper limit of the target frequency band impedance. Based on the upper limit of the target frequency band impedance, an impedance shaping network is constructed to satisfy the constraint of the target impedance threshold, so that the equivalent impedance curve in the target rectification frequency band is not higher than the peak value of the target impedance threshold. The impedance shaping network is applied to the device under test and retested. If the standard is not met, the mapping is updated or the impedance network combination is adjusted until the limit is met.

[0005] Optionally, the identification of the target rectification frequency band and key frequency points specifically includes: determining the frequency range [fa,fb] and key peak points exceeding the standard from the electromagnetic interference test spectrum, where [fa,fb] represents the upper and lower limits of the frequency range; To determine the type of interference, distinguish between differential mode interference and common mode interference. The determination methods include comparing different wiring, comparing before and after adding a common mode choke, analyzing the amplitude relationship between the L / N lines, or analyzing near-field scanning characteristics.

[0006] Optionally, mapping the degree of exceeding the standard to the target impedance threshold specifically includes: calculating the magnitude ΔA(f) that needs to be reduced at frequency f; The amplitude ΔA(f) is converted into the required attenuation ratio K(f) = 10ΔA / 20, and combined with the equivalent interference source model or empirical mapping rules, the target impedance threshold Ztarget(f) is determined, forming the frequency band constraint ∀f∈[fa,fb], |Z(f)|≤Ztarget(f)∀f∈[fa,fb], or the key point constraint |Z(fpi)|≤Ztarget(fpi), where Z(f) represents the actual impedance at frequency f, and Ztarget(fpi) represents the value of the upper limit function of the target impedance at the key frequency point fpi.

[0007] Optionally, the impedance shaping network includes at least: A multi-branch parallel capacitor network consists of capacitor branches with different capacitance values, different packages, or different equivalent series inductances. A damped parallel network, consisting of a capacitor and a series resistor, an RC circuit, or an RLC circuit, forms a damped branch to suppress anti-resonance spikes. The segmented network divides the target rectification frequency band into multiple sub-bands, and each sub-band is low-impedance by a corresponding impedance unit. The network is configurable, allowing users to select different branch combinations via jumpers, plugs, or switches to match different rectification goals.

[0008] Optionally, the impedance shaping network may be deployed in the following locations: The input terminal is located on the LISN side or the device side; DC bus, located near the power module terminals or on the busbar; The output terminal is located at the load terminal; Control or auxiliary power ports are used to suppress coupling paths.

[0009] Optionally, the step of mapping the degree of exceedance of the target rectification frequency band and key frequency points to a target impedance threshold to generate the upper limit of the target frequency band impedance includes: The equivalent voltage source method is adopted: at the frequency point exceeding the standard, the interference source is equivalent to an equivalent voltage source V_s and a source impedance Z_s; After adding the filter, the interference voltage is divided by the source impedance Z_s and the filter impedance Z_f. Based on the target attenuation value, the ratio between the filter impedance Z_f and the source impedance Z_s is derived, and the upper limit of the filter's target frequency band impedance is determined.

[0010] Second aspect: A low-impedance filtering device for implementing the method of the first aspect, comprising: The connection port includes at least a differential mode connection terminal and / or a common mode reference terminal; Multiple impedance units, each containing an energy channel element and a damping element; The energy channel element includes a capacitor, an inductor, or a ferrite; the damping element includes a resistor, an RC circuit, or an RLC circuit. The device is configured to achieve and ensure that the equivalent impedance is lower than the target impedance threshold mapped from the EMI test results within the target frequency band.

[0011] Optionally, the plurality of impedance units include: The first channel, including large-capacitance capacitors and moderately damped resistors, is used to cover the lower frequency band; The second channel, including a medium-capacitance capacitor and a low-ESL package structure, is used to cover the mid-frequency band. The third channel, including small-value capacitors and ultra-low loop inductance structure, is used to cover the high-frequency band; The fourth channel, which includes a damping branch consisting of a capacitor and a series resistor, is connected in parallel to the main branch and is used to suppress the anti-resonance peak.

[0012] Optionally, the device further includes configurable implementations: Plug-in capacitor cards or damping cards are used to enable rapid frequency band switching; Multiple sets of pads or jumper caps are used to select different branches; An electronic switch matrix is ​​used to automatically select branch combinations via control signals.

[0013] Third aspect: An EMC debugging system, comprising: The test unit is used to acquire EMI test data of the device under test; The data processing unit is used to identify the target rectification frequency band and key frequency points, and map the degree of exceeding the standard to the target impedance threshold; The module library stores various impedance shaping modules or combinations of impedance units as described in the second aspect. An execution unit is used to guide manual assembly or automatic selection and switching of the impedance shaping module; The closed-loop verification unit is used to retest devices that use impedance shaping networks and determine whether they meet the standards, and output a rectification report.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention maps the degree of exceeding the standard of the target rectification frequency band to the target impedance threshold to generate the upper limit of the target frequency band impedance. This changes the process from repeated trial and error to design based on the impedance constraint of the target frequency band, reducing the number of test rounds and significantly improving the rectification efficiency. This invention utilizes the correspondence between impedance thresholds and impedance shaping networks to form calculable / verifiable low impedance within the target frequency band, transforming previous qualitative analysis into quantitative rectification and greatly improving the quality of rectification. As long as the network impedance curve constructed by this invention is lower than the target impedance threshold throughout the target frequency band, the interference voltage can be guaranteed to be lower than the standard limit from the circuit principle, thus solving the problem of unpredictable effects after modifying components in traditional methods. This invention transforms abstract rectification experience into concrete, parameterized circuit modules by constructing a standardized impedance shaping module library and a target impedance threshold matching module. This forms a standardized module library and process that can be migrated to different platforms and power ranges, significantly enhancing the feasibility of EMC-compliant design. Attached Figure Description

[0015] Figure 1 The diagram shown is a schematic representation of the method flow of the present invention. Figure 2 The image shown is a schematic diagram of the EMC test results; Figure 3 The diagram shown is a schematic of a differential-mode filter circuit. Figure 4 The diagram shows the structure of a common-mode filter circuit. Detailed Implementation

[0016] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] Example 1, such as Figure 1 As shown, a debugging method based on electromagnetic interference is disclosed, the method comprising: S1: Obtain EMI test data of the power conversion device under test under specified test conditions; S2: Based on the EMI test data, identify the target rectification frequency band and key frequency points; S3: Map the degree of exceeding the standard of the target rectification frequency band and key frequency points to the target impedance threshold, and generate the target frequency band impedance upper limit function; S4: Based on the upper limit function of the target frequency band impedance, construct an impedance shaping network that satisfies the constraint of the target impedance threshold, so that the equivalent impedance curve in the target rectification frequency band is not higher than the peak value of the target impedance threshold. S5: Apply the impedance shaping network to the device under test and retest. If the standard is not met, update the mapping or adjust the impedance network combination until the limit is met.

[0020] This embodiment further elaborates on the above method in its specific implementation process: S1: Obtain electromagnetic interference test data; Acquire EMI test data of the power conversion device under test under specified test conditions. The test data may include, but is not limited to: conducted interference (LISN + receiver / spectrum analyzer) test spectrum; radiated interference test spectrum; near-field probe scan spectrum (optional); and critical operating points. The output data may be in the form of a frequency-amplitude curve.

[0021] S2: Identify target rectification frequency bands and key frequency points Identify the following from the S1 spectrum: Exceeding frequency bands: frequency range [fa, fb]; Key peak points: f_p1, f_p2, …; Optional: Determine whether differential mode or common mode is dominant (e.g., by comparing different wiring, before and after adding a common mode choke, the amplitude relationship between L / N lines, near-field scanning characteristics, etc.).

[0022] S3: Map the degree of exceeding the standard to the target impedance threshold; Establish a mapping relationship from the over-limit amplitude / margin to the target impedance threshold, and generate the target frequency band impedance upper limit function Ztarget(f).

[0023] An example mapping: Suppose that the target needs to reduce the amplitude by ΔA(f) (dB) at frequency f; then convert ΔA(f) into the required attenuation ratio K(f) = 10^(ΔA / 20); then combine the equivalent interference source model and the network relationship to obtain the setting rule of the target frequency band impedance upper limit function Z_target(f).

[0024] Output the target constraint set, frequency band constraint: ∀ f∈[f_a,f_b], |Z(f)| ≤ Ztarget(f); or key point constraint: |Z(f_pi)| ≤ Z_target(f_pi).

[0025] S4: Construct an impedance shaping network that satisfies impedance constraints; Select or design an impedance shaping network based on the upper limit function Z_target(f) of the target frequency band impedance to satisfy the above inequality constraints within the target frequency band.

[0026] In this embodiment, the impedance shaping network includes at least one of the following structures: 1) Multi-branch parallel capacitor network: a combination of capacitor branches with different capacitance values, different packages / different ESLs; 2) Damped parallel network: The capacitor and series resistor (or RC, RLC) form a damped branch to suppress anti-resonance spikes; 3) Segmented network: The target frequency band is divided into multiple sub-bands, and each sub-band is equipped with a corresponding "impedance unit" to achieve low impedance; 4) Configurable network: Different branch combinations can be selected via jumpers / plugs / switches to match different rectification goals; 5) Optional: Combine with common-mode choke, differential-mode inductor, Y capacitor, etc. to form a complete filter structure, but the core is still based on "satisfying Ztarget(f)" as the criterion.

[0027] S5: Apply the network and retest the closed loop. Connect the network obtained in S4 to the specified location of the device under test (e.g., DC-link, input terminal, output terminal, near the power module terminal, etc.) in the form of a filter board / module, and repeat the test under the same conditions as in S1. If the requirements are not met, update the mapping or adjust the impedance network combination (repeat S2~S5) until the limits and margin requirements are met.

[0028] In this embodiment, the impedance shaping network is deployed in the following locations in specific applications: The input terminal is located on the LISN side or the device side; DC bus, located near the power module terminals or on the busbar; The output terminal is located at the load terminal; Control or auxiliary power ports are used to suppress coupling paths.

[0029] The present invention is further illustrated according to the method of Example 1: like Figure 2 As shown, the directional rectification of differential-mode conducted interference is as follows: the conducted interference of the device is tested under operating condition A, and the spectrum curve is obtained. It is found that the interference exceeds the standard in the frequency band [f_a,f_b], and the peak value is the highest at f_p. Based on the excess margin ΔA, determine the target impedance threshold Z_target(f); like Figure 3 and Figure 4 As shown, select the differential-mode impedance shaping module from the module library: Main branch: C1 (larger) is used for lower frequency bands, and a small series resistor R1 is used as a backup to prevent resonance spikes; Auxiliary branch: C2 (medium) is used for the mid-frequency range, and a small series resistor R2 is used as a backup to prevent resonance spikes; High-frequency branch: C3 (small capacitance, low ESL structure) is used in the high-frequency band, and a spare series small resistor R3 is used to prevent resonance spikes; Damping branch: C4 series and R4 are connected in parallel in the main branch to suppress anti-resonance peaks; After assembly and retesting, if spikes still exist in the target frequency band, adjust the damping branch parameters or enable an additional branch. Finally, after passing the test, output the corrected configuration, store the calibration information in the module library, and reuse it in subsequent models.

[0030] like Figure 2As shown, the targeted rectification of common-mode interference is as follows: Conducted tests are performed on the device under operating condition A to obtain the spectrum curve, identifying an exceedance in the frequency band [f_a, f_b], with the highest peak at f_p. Based on the exceedance margin ΔA, the target impedance threshold Z_target(f) is determined; as... Figure 4 As shown, select the differential-mode impedance shaping module from the module library: Main branch: C1 (larger) is used for lower frequency bands, and a small series resistor R1 is used as a backup to prevent resonance spikes; Auxiliary branch: C2 (medium) is used for the mid-frequency range, and a small series resistor R2 is used as a backup to prevent resonance spikes; High-frequency branch: C3 (small capacitance, low ESL structure) is used in the high-frequency band, and a spare series small resistor R3 is used to prevent resonance spikes; Damping branch: C4 in series and R4 in parallel are connected in the main branch to suppress anti-resonance peaks. Example 2 discloses a low-impedance filtering module for implementing the method described in Example 1, comprising: Connection ports include at least a differential mode connection terminal (e.g., P / N or L / N) and / or a common mode reference terminal (PE / chassis). Multiple impedance units U1~Un, each containing an energy channel element and a damping element; damping element (resistor / RC / RLC); optional: switch selection structure (jump wire, DIP switch, relay, MOS switch, etc.); structural parameters: trace geometry, copper foil width and thickness, return path, distributed inductance control structure (e.g., multi-point parallel connection, symmetrical wiring, short loop); calibration information (optional): impedance curve or equivalent parameters for each impedance unit for quick selection; The energy channel element includes a capacitor, an inductor, or a ferrite; the damping element includes a resistor, an RC circuit, or an RLC circuit. The module is configured to achieve and ensure that the equivalent impedance is lower than the target impedance threshold mapped from the EMI test results within the target frequency band.

[0031] The plurality of impedance units include: The first channel, including a large-capacitance capacitor C1 and a moderately damped resistor, is used to cover the lower frequency band. The second channel, including a medium-value capacitor C2 and a low-ESL package structure, is used to cover the mid-frequency band. The third channel, including a small-value capacitor C3 and an ultra-low loop inductor structure, is used to cover the high-frequency band. The fourth channel, consisting of a damping branch with capacitor C4 in series and a resistor, is connected in parallel to the main branch to suppress the anti-resonance peak.

[0032] The module also includes a configurable implementation: Plug-in capacitor cards or damping cards are used to enable rapid frequency band switching; Multiple sets of pads or jumper caps are used to select different branches; An electronic switch matrix is ​​used to automatically select branch combinations via control signals.

[0033] Example 3 discloses an EMC rapid debugging system, including: a testing unit: an EMI receiver / spectrum analyzer, LISN, near-field probe, etc.; a data processing unit: used to identify the target frequency band / peak point and generate Z_target(f); a module library: various impedance shaping modules / impedance unit combinations, storing various impedance shaping modules or impedance unit combinations described in Example 2; an execution unit: guiding manual assembly or automatic selection / switching of modules; and a closed-loop verification unit: retesting and judging compliance, and outputting a rectification report.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A debugging method based on electromagnetic interference, characterized in that, The method includes: Obtain EMI test data of the power conversion device under test under specified test conditions; Based on the EMI test data, identify the target rectification frequency band and key frequency points; The degree of exceeding the standard of the target rectification frequency band and key frequency points is mapped to the target impedance threshold to generate the upper limit of the target frequency band impedance. Based on the upper limit of the target frequency band impedance, an impedance shaping network is constructed to satisfy the constraint of the target impedance threshold, so that within the target rectification frequency band, the equivalent impedance curve is not higher than the peak value of the target impedance threshold. The impedance shaping network is applied to the device under test and retested. If the standard is not met, the mapping is updated or the impedance network combination is adjusted until the limit is met.

2. The electromagnetic interference-based debugging method according to claim 1, characterized in that, The identification of the target rectification frequency band and key frequency points specifically includes: determining the frequency range [fa, fb] exceeding the standard and the key peak points from the electromagnetic interference test spectrum; To determine the type of interference, distinguish between differential-mode interference and common-mode interference. The determination methods include comparing different wiring, comparing before and after adding a common-mode choke, analyzing the amplitude relationship between the L / N lines, or analyzing near-field scanning characteristics. [fa,fb] represents the upper and lower limits of the frequency range.

3. The electromagnetic interference-based debugging method according to claim 1, characterized in that, The process of mapping the degree of exceeding the standard to the target impedance threshold specifically includes: calculating the magnitude ΔA(f) that needs to be reduced at frequency f; The amplitude ΔA(f) is converted into the required attenuation ratio K(f) = 10ΔA / 20, and combined with the equivalent interference source model or empirical mapping rules, the target impedance threshold Ztarget(f) is determined, forming the frequency band constraint ∀f∈[fa,fb], |Z(f)|≤Ztarget(f)∀f∈[fa,fb], or the key point constraint |Z(fpi)|≤Ztarget(fpi); Z(f) represents the actual impedance at frequency f, and Ztarget(fpi) represents the value of the upper limit function of the target impedance at the key frequency point fpi.

4. The electromagnetic interference-based debugging method according to claim 1, characterized in that, The impedance shaping network includes at least: A multi-branch parallel capacitor network consists of capacitor branches with different capacitance values, different packages, or different equivalent series inductances. A damped parallel network, consisting of a capacitor and a series resistor, an RC circuit, or an RLC circuit, forms a damped branch to suppress anti-resonance spikes. The segmented network divides the target rectification frequency band into multiple sub-bands, and each sub-band is low-impedance by a corresponding impedance unit. The network is configurable, allowing users to select different branch combinations via jumpers, plugs, or switches to match different rectification goals.

5. The electromagnetic interference-based debugging method according to claim 1, characterized in that, The locations where the impedance shaping network is deployed include: The input terminal is located on the LISN side or the device side; DC bus, located near the power module terminals or on the busbar; The output terminal is located at the load terminal; Control or auxiliary power ports are used to suppress coupling paths.

6. The electromagnetic interference-based debugging method according to claim 1, characterized in that, The step of mapping the degree of exceedance of the target rectification frequency band and key frequency points to a target impedance threshold to generate the upper limit of the target frequency band impedance includes: Using the equivalent voltage source method, at the frequency point exceeding the standard, the interference source is equivalent to an equivalent voltage source V_s and a source impedance Z_s; After adding the filter, the interference voltage is divided by the source impedance Z_s and the filter impedance Z_f. Based on the target attenuation value, the ratio between the filter impedance Z_f and the source impedance Z_s is derived, and the upper limit of the filter's target frequency band impedance is determined.

7. A low-impedance filtering device for implementing the method as described in any one of claims 1-6, characterized in that, include: The connection port includes at least a differential mode connection terminal and / or a common mode reference terminal; Multiple impedance units, each containing an energy channel element and a damping element; The energy channel element includes a capacitor, an inductor, or a ferrite; the damping element includes a resistor, an RC circuit, or an RLC circuit. The device is configured to achieve and ensure that the equivalent impedance is lower than the target impedance threshold mapped from the EMI test results within the target frequency band.

8. The low-impedance filtering device according to claim 7, characterized in that, The plurality of impedance units include: The first channel, including large-capacitance capacitors and moderately damped resistors, is used to cover the lower frequency band; The second channel, including a medium-capacitance capacitor and a low-ESL package structure, is used to cover the mid-frequency band. The third channel, including small-value capacitors and ultra-low loop inductance structure, is used to cover the high-frequency band; The fourth channel, which includes a damping branch consisting of a capacitor and a series resistor, is connected in parallel to the main branch and is used to suppress the anti-resonance peak.

9. The low-impedance filtering device according to claim 7, characterized in that, The device also includes configurable implementations: Plug-in capacitor cards or damping cards are used to enable rapid frequency band switching; Multiple sets of pads or jumper caps are used to select different branches; An electronic switch matrix is ​​used to automatically select branch combinations via control signals.

10. An EMC debugging system, characterized in that, include: The test unit is used to acquire EMI test data of the device under test; The data processing unit is used to identify the target rectification frequency band and key frequency points, and map the degree of exceeding the standard to the target impedance threshold; The module library stores a variety of impedance shaping modules or combinations of impedance units as described in any one of claims 7-8; An execution unit is used to guide manual assembly or automatic selection and switching of the impedance shaping module; The closed-loop verification unit is used to retest devices that use impedance shaping networks and determine whether they meet the standards, and output a rectification report.

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