A method for diagnosing radiated electromagnetic interference of power electronic devices

Abstract

The present invention discloses a method for diagnosing radiated electromagnetic interference of power electronic devices, belonging to the field of electromagnetic compatibility of power electronics. To address the difficulty in diagnosing radiated interference sources, an oscilloscope is used to measure the time-domain waveform of the radiated electric field, and its narrowband after bandpass filtering is analyzed. Envelope demodulation is then used to reveal the circuit PWM modulation information embedded in the radiated EMI, and then the dominant interference source is determined based on known power electronic topology modulation strategies. To address the difficulty in diagnosing radiated interference paths, the dominant path of the radiated interference source is diagnosed based on voltage and current detection, providing guidance for the deployment of precise suppression strategies for the dominant interference path and a means for revealing the mechanism of EMI filtering failure. The method for diagnosing radiated interference sources and paths provided by the present invention can provide guidance for the precise suppression of radiated electromagnetic interference of power electronic devices.

Description

Technical Field

[0001] The present invention belongs to the field of power electronic electromagnetic compatibility, and more specifically, relates to a method for diagnosing radiated electromagnetic interference of a power electronic device. Background Art

[0002] In recent years, power electronics have been widely used in modern power systems, rail transit, and consumer electronics. However, the inherent switching operation of power electronics can cause serious electromagnetic interference (EMI), potentially endangering the proper functioning of surrounding electronic equipment or affecting the reliability and lifespan of electronic systems. Power electronics must pass stringent EMC certification before deployment. Radiated EMI, in particular, has higher frequencies, a wider spatial range, and more complex propagation paths and fields, making analysis and control of radiated EMI more challenging. Furthermore, radiated interference testing requires significant equipment and time costs. Therefore, rapidly diagnosing and accurately suppressing this radiated interference has become a pressing issue for power electronics. Summary of the Invention

[0003] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a method for diagnosing radiated electromagnetic interference of power electronic devices, which can achieve rapid and accurate diagnosis of the dominant interference source and dominant propagation path of radiated EMI.

[0004] To achieve the above objectives, according to a first aspect of the present invention, a method for diagnosing radiation interference sources of a power electronic device is provided, comprising:

[0005] S1, measure the radiated EMI time domain signal of the target power electronic device, perform FFT processing on it to obtain the corresponding EMI spectrum, and obtain the peak frequency f of the EMI spectrum PK ;

[0006] S2, in K·f PK The radiated EMI time domain signal is band-pass filtered for the band-pass width; wherein the value range of K is [0.05, 0.1];

[0007] S3, performing envelope demodulation and FFT processing on the radiated EMI time domain signal after bandpass filtering in sequence to obtain the switching frequency of the radiated interference source, and taking the converter in the target power electronic device that uses the switching frequency as a modulation parameter as its radiated interference source.

[0008] According to a second aspect of the present invention, a method for diagnosing a radiation interference propagation path of a power electronic device is provided, comprising:

[0009] A1. Determine the radiation type of the cable connected to the radiation interference source of the target power electronic device; wherein the radiation type includes independent radiation and coupled radiation. If the cables are all independently connected to the load, the radiation type is independent radiation; if the cables are all connected to the load together with other cables, the radiation type is coupled radiation;

[0010] A2. Determine the radiation interference propagation path of the target power electronic device based on the radiation type of the antenna; if the radiation type of the cable is independent radiation, the cable with the largest radiation current is used as the radiation cable, and its path is used as the radiation interference propagation path; if the radiation type of the cable is coupled radiation, the cable with the largest radiation voltage is used as the radiation cable, and its path is used as the radiation interference propagation path.

[0011] According to a third aspect of the present invention, a device for diagnosing radiation interference sources of a power electronic device is provided, comprising:

[0012] The first processing module is used to measure the radiated EMI time domain signal of the target power electronic device, perform FFT processing on it to obtain the corresponding EMI spectrum, and obtain the peak frequency f of the EMI spectrum. PK ;

[0013] The second processing module is used to calculate the K·f PK The radiated EMI time domain signal is band-pass filtered for the band-pass width; wherein the value range of K is [0.05, 0.1];

[0014] The second processing module is used to perform envelope demodulation and FFT processing on the radiated EMI time domain signal after bandpass filtering in sequence to obtain the switching frequency of the radiated interference source, and use the converter in the target power electronic device that uses the switching frequency as the modulation parameter as its radiated interference source.

[0015] According to a fourth aspect of the present invention, there is provided a device for diagnosing a radiation interference propagation path of a power electronic device, comprising:

[0016] a determination module, configured to determine a radiation type of a cable connected to a radiation interference source of a target power electronic device; wherein the radiation type includes independent radiation and coupled radiation. If the cables are all independently connected to a load, the radiation type is independent radiation; if the cables are all connected to a load together with other cables, the radiation type is coupled radiation;

[0017] A processing module is configured to determine a radiation interference propagation path of the target power electronic device based on the radiation type of the antenna; wherein, if the radiation type of the cable is independent radiation, the cable with the largest radiation current is used as the radiation cable, and its path is used as the radiation interference propagation path; if the radiation type of the cable is coupled radiation, the cable with the largest radiation voltage is used as the radiation cable, and its path is used as the radiation interference propagation path.

[0018] According to a fifth aspect of the present invention, there is provided an electronic device comprising: a computer-readable storage medium and a processor;

[0019] The computer-readable storage medium is used to store executable instructions;

[0020] The processor is configured to read the executable instructions stored in the computer-readable storage medium and execute the method according to the first aspect or the second aspect.

[0021] According to a sixth aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to execute the method as described in the first aspect or the second aspect.

[0022] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0023] The method for diagnosing radiation interference sources of power electronic devices provided by the present invention addresses the difficulty in diagnosing radiation interference sources. The method uses an oscilloscope to measure the time domain waveform of the radiation electric field, compares the radiation electric field waveform to the amplitude modulation wave in communication theory, analyzes its narrow band after bandpass filtering, and reveals the circuit PWM modulation information embedded in the radiated EMI through envelope demodulation, thereby determining the dominant interference source based on the known power electronic topology modulation strategy. The method can quickly diagnose the radiation interference source and provide guidance for the deployment of precise suppression strategies for the dominant interference source.

[0024] The radiation interference propagation path diagnosis method of the power electronic device provided by the present invention addresses the difficulty in diagnosing the radiation interference path. Based on circuit theory, the node voltage and branch current are measured, and the dominant radiation cable antenna, the dominant radiation current direction and the hidden coupling are gradually determined. According to the dominant radiation current direction, it is confirmed whether the Y-type capacitor in the EMI filter connected to the dominant radiation cable antenna can effectively filter. By judging whether there is hidden coupling in the multi-stage common-mode inductor of the EMI filter connected to the dominant radiation cable, these failed Y-type capacitors and hidden couplings are the dominant paths that need to be identified and cause the degradation of filtering performance, and ultimately provide guidance for the targeted suppression of the dominant path. The method can quickly diagnose the radiation path, provide guidance for the deployment of precise suppression strategies for the dominant interference path, and provide a means for revealing the mechanism of EMI filtering failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the coupling of multiple radiation interference sources in power electronic devices.

[0026] Figure 2 Schematic diagram of the propagation path of electromagnetic interference radiated by power electronic devices.

[0027] Figure 3 This is a flow chart of a method for diagnosing radiation interference sources of a power electronic device provided by an embodiment of the present invention.

[0028] Figure 4 A schematic diagram comparing the amplitude modulation wave and radiated EMI provided by an embodiment of the present invention.

[0029] Figure 5 Schematic diagram of the principle of modulation and demodulation of amplitude modulated signals.

[0030] Figure 6 This is a simulation diagram of multi-source radiation electromagnetic interference provided by an embodiment of the present invention.

[0031] Figure 7 This is a simulation diagram of the diagnostic envelope spectrum of the dominant interference source with the same switching frequency and different modulation strategies provided by the embodiment of the present invention.

[0032] Figure 8 A simulation diagram of the radiated electromagnetic interference spectrum provided by an embodiment of the present invention.

[0033] Figure 9 (a) and (b) are respectively the time domain EMI diagram and envelope spectrum diagram of the simulated electromagnetic interference bandpass radiation EMI at 30 MHz provided by the embodiment of the present invention.

[0034] Figure 10 This is a flow chart of a method for diagnosing the propagation path of radiated interference in a power electronic device provided by an embodiment of the present invention.

[0035] Figure 11 (a) and (b) are respectively the independent radiation model and circuit diagram, and the coupled radiation model and circuit diagram of the multi-cable antenna provided by the embodiment of the present invention.

[0036] Figure 12 This is a flow chart of a method for diagnosing a dominant radiating cable antenna provided by an embodiment of the present invention.

[0037] Figure 13 (a) and (b) are respectively a Y-type capacitor path direction diagnosis principle diagram and a current measurement flow chart provided in an embodiment of the present invention.

[0038] Figure 14(a) and (b) are respectively a schematic diagram and a flow chart of an implicit coupling diagnosis based on voltage measurement provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0040] Diagnosis of radiated electromagnetic interference sources refers to determining the dominant radiating circuit topology in power electronic devices. As the demand for power conversion develops towards multi-functionality, power electronic devices begin to integrate multiple types and groups of conversion topologies. Different topology circuits generate electromagnetic interference with different characteristics. Multiple electromagnetic interferences couple with each other, forming multi-source electromagnetic interference in the power electronic device, resulting in the problem of unknown dominant interference sources. Figure 1 As shown, a power electronic device has four circuit topologies, each generating a type of radiated EMI (Electromagnetic Interference). These radiated EMI couple with each other to produce multi-source radiated EMI, which radiates outward simultaneously and is indiscriminately received by the EMC antenna. The spectrum is ultimately measured by a spectrum analyzer, but the circuit topology that primarily causes the maximum peak in the spectrum is unknown and requires diagnosis. Although extensive research has been conducted on EMI suppression technologies, deploying suppression strategies is unwise when the dominant interference source is unknown. Only by identifying the dominant radiating circuit topology causing the spectrum peak can targeted and precise suppression be implemented.

[0041] Radiated electromagnetic interference path diagnosis is to determine how the radiated EMI is transmitted outward. Figure 2 As shown, power electronics devices, which integrate various circuit topologies, are inherently complex circuit networks. In addition to directly connected circuit elements, such networks also include indirect electromagnetic field coupling effects. Radiated electromagnetic interference (EMI) propagates along this complex circuit network, ultimately reaching the ports of the power electronics device, emitting electromagnetic waves. Identifying the primary propagation paths within this network is a prerequisite for analyzing radiated EMI mechanisms and precisely mitigating these paths.

[0042] Currently, radiated EMI diagnosis still largely relies on a trial-and-error approach, comparing the spectrum before and after installing specific mitigation measures. If the mitigation effect is significant, the dominant path and source are identified. This approach relies heavily on experience and puts the cart before the horse. If the dominant radiation path and source can be quickly identified and targeted mitigation strategies can be implemented, the efficiency of radiated EMI analysis will be significantly improved, and even unnecessary mitigation measures can be reduced, helping to improve the quality and reduce the cost of power electronic devices.

[0043] Based on this, an embodiment of the present invention provides a method for diagnosing radiation interference sources of a power electronic device, such as Figure 3 Shown, including:

[0044] S1, measure the radiated electromagnetic interference time domain signal (also called radiated EMI time domain signal) of the target power electronic device, perform FFT processing on it to obtain the corresponding EMI spectrum, and obtain the peak frequency f of the EMI spectrum PK ;

[0045] S2, in K·f PK The radiated EMI time domain signal is band-pass filtered for the band-pass width; wherein the value range of K is [0.05, 0.1];

[0046] S3, performing envelope demodulation and FFT processing on the radiated EMI time domain signal after bandpass filtering in sequence to obtain the switching frequency of the radiated interference source, and using the converter in the target power electronic device that uses the switching frequency as a modulation parameter as the radiated interference source of the target power electronic device.

[0047] The radiation interference source diagnosis method provided in the embodiment of the present invention adopts the radiation interference dominant source identification technology based on envelope demodulation. Its core idea is to compare radiated EMI with amplitude modulated wave (AM) and analyze their similarities. Then, the method of processing amplitude modulated wave (AM), namely envelope demodulation, is used to process radiated EMI.

[0048] Figure 4Radiated EMI and amplitude modulation waves are compared from the perspectives of carrier wave, modulation wave, and demodulation method. AM and radiated EMI have similar waveforms, both manifesting as high-frequency oscillations. Radiated EMI and AM share similar carrier waves. For AM, the carrier wave is a fixed-frequency sine wave, while for radiated EMI, the carrier wave is a sine wave mixed with multiple frequencies. This is slightly different from the AM carrier wave, but a fixed-frequency sine wave carrier can be achieved through bandpass. The modulation wave in AM is an arbitrary waveform, while for radiated EMI, the modulation wave is a modulation strategy. In both cases, the modulation wave frequency is significantly lower than the carrier frequency. This is because the modulated wave of AM is the information to be transmitted and can be any low-frequency waveform (lower frequency than the carrier frequency); radiated EMI can be considered to have such a modulated wave: when the switching device switches, the modulated wave amplitude is large, and when the switching device does not switch, the modulated wave amplitude is 0. Therefore, the periodic characteristics of the modulated wave of radiated EMI actually reflect the switching frequency of the converter that generates the radiated EMI. The demodulation result of AM is the recovered transmission signal, while the demodulation result of radiated EMI is the pulse period of the converter's modulation strategy, that is, the switching frequency. Therefore, AM and radiated EMI are highly similar. The envelope demodulation method is borrowed to the processing of radiated EMI.

[0049] Figure 5 This demonstrates the principles of amplitude modulation and demodulation. An AM wave is generated by multiplying a low-frequency modulating wave by a high-frequency carrier wave. Envelope detection of the AM wave recovers the original modulating wave information. Therefore, a key feature of AM wave processing that allows for effective signal processing is the fixed carrier frequency.

[0050] Figure 3 A proposed method for diagnosing radiated electromagnetic interference sources is presented. First, the time-domain waveform of radiated EMI is measured according to a standard test procedure. It is worth noting that the test equipment should be a high-bandwidth oscilloscope rather than an EMI receiver. This is because identifying the dominant interference source requires time-domain information, not just spectrum information. Using an EMI receiver would not be able to obtain this time-domain information.

[0051] Then, the EMI spectrum is calculated based on FFT to determine the peak frequency f PK and the time domain EMI is at the peak frequency f PK The passband width can be selected as K times of the current frequency. The value range of K is [0.05, 0.1]. For example, when K = 0.1, the passband range is [0.95f PK ,1.05f PK ].

[0052] It should be noted that the passband width is not recommended to be the same as the resolution bandwidth (RBW) specified in the standard. This is because the RBW specified in the standard is relatively small at high frequencies, and the envelope after the passband tends to be stable, which reduces the recognition performance of time domain spikes. Specifically, it is manifested as a decrease in the highest switching frequency of the distinguishable converter. Considering that the change in the dominant interference source category is not a sudden change at each frequency point, but a gradual change. In a relatively wide spectrum range such as K·f PK , the dominant interference source of EMI is of the same category, but the time domain peak identification performance of the envelope after bandpass is better, so this bandpass width should be used. Then, the time domain waveform of the radiated EMI after bandpass has been converted into an amplitude modulated wave AM, so envelope demodulation can be used. First, the upper envelope is calculated directly based on the Hilbert transform. This process can reveal the switching pulse moment of the modulation strategy adopted. Then, based on the switching pulse moment, the FFT spectrum of the upper envelope is calculated. This process can reveal the switching frequency of the dominant interference source. Finally, based on the switching frequency of the dominant interference source and the known converter modulation strategy, it is determined which converter the dominant interference source belongs to. This converter is the dominant interference source. It can be understood that when the converter adopts different modulation strategies, the modulation parameter adopted - the switching frequency is also different. Therefore, based on the switching frequency of the dominant interference source, it is possible to know which converter the dominant interference source is.

[0053] In summary, the core idea of ​​the identification method proposed in the embodiment of the present invention is to convert the radiated EMI with a multi-frequency sine as the carrier into an amplitude modulated wave with a single-frequency sine as the carrier after bandpass preselection, and then determine the switching frequency of the dominant interference source through envelope demodulation and envelope spectrum, and finally determine which power electronic circuit the dominant interference source comes from.

[0054] It should be noted that even if the switching frequencies of the two types of converters are the same, since sinusoidally modulated PWM has sideband harmonics compared to fixed duty cycle PWM, the shapes of the two on the spectrum are still different and can be distinguished.

[0055] That is, for two types of converters with the same switching frequency but different modulation strategies, their envelope spectra are also different and can still be distinguished. For example, SPWM has sideband harmonics compared to FDPWM; variable frequency PWM has a wide switching frequency (that is, the envelope spectrum shows a very wide peak), while the envelope spectra of the other two PWMs show very narrow peaks. By simulating the envelope spectrum of multi-source coupled interference with FDPWM and DPWM modulation, as shown in Figure 7 As shown in the figure, the switching frequency of these two interference sources is 10kHz, but their envelope spectra are still distinguishable. The FDPWM has a very narrow peak, indicating that the FDPWM has the largest amplitude in the envelope spectrum. The DPWM has a spectrum with some sideband harmonics and a wide spectrum below.

[0056] The correctness of the diagnosis of radiated electromagnetic interference sources can be verified through simulation. Figure 6 The simulation shows two types of electromagnetic interference (EMI) sources: a 10kHz discontinuous PWM (DPWM) with an amplitude of 1 and a 300kHz fixed-duty PWM (FDPWM) with an amplitude of 10. These sources are mixed to generate multi-source EMI. This multi-source EMI is then high-pass-processed at 30MHz to generate simulated radiated EMI. The proposed identification method is used to identify the dominant source of the radiated EMI.

[0057] Figure 8 The simulated radiated EMI spectrum shows that the peak frequency band requiring diagnosis is 30 MHz. Furthermore, because the simulated EMI source has an ideal fixed switching frequency, it does not exhibit the high-frequency spread spectrum effect of the EMI generated by the non-ideal fixed switching frequency PWM used in the experiment, resulting in a discrete EMI spectrum. The spectrum peaks also confirm that the dominant EMI source is the 300 kHz FDPWM. This result validates the proposed diagnostic method. It is noteworthy that in the experimentally measured spectrum, radiated EMI, due to its non-ideal characteristics, does not appear as a discrete spectrum but rather a continuous spectrum. Therefore, the modulation strategy cannot be determined from discrete spectrum peaks, further highlighting the superiority of the proposed diagnostic method.

[0058] Figure 9 (a) shows the bandpass radiated EMI at 30MHz. Figure 9 (b) is the envelope spectrum of the simulated multi-source electromagnetic interference. The 10kHz peak with sideband harmonics and the 300kHz peak without sideband harmonics are Figure 9 It is clearly visible in (b) that the amplitude of the latter is much larger than that of the former, which indicates that 300kHz FDPWM is the main source of electromagnetic interference, verifying the correctness of the diagnosis method.

[0059] To quickly diagnose the dominant radiation path, an embodiment of the present invention provides a method for diagnosing the propagation path of radiation interference in a power electronic device, comprising:

[0060] A1. Determine the radiation type of the cable connected to the radiation interference source of the target power electronic device; wherein the radiation type includes independent radiation and coupled radiation. If the cables are all independently connected to the load, the radiation type is independent radiation; if the cables are all connected to the load together with other cables, the radiation type is coupled radiation;

[0061] A2. Determine the radiation interference propagation path of the target power electronic device based on the radiation type of the antenna; if the radiation type of the cable is independent radiation, the cable with the largest radiation current is used as the radiation cable, and its path is used as the radiation interference propagation path; if the radiation type of the cable is coupled radiation, the cable with the largest radiation voltage is used as the radiation cable, and its path is used as the radiation interference propagation path.

[0062] The radiation interference source of the target power electronic device adopts the radiation interference source diagnosis method of the power electronic device as described in any of the above embodiments (such as Figure 10 The method can be used to diagnose the radiation interference source of any power electronic device as shown in the figure) or any existing radiation interference source diagnosis method of the power electronic device.

[0063] Preferably, in order to identify the key leakage paths in the installed EMI filter to guide targeted solutions, and ultimately to increase the actual performance of the EMI filter without increasing the volume of the EMI filter and improve the power density of the power electronic device, the method for diagnosing the propagation path of radiated interference of the power electronic device provided in the embodiment of the present invention further includes:

[0064] A3, determining whether the converter-side current I1 of the Y-type capacitor in the EMI filter connected to the radiating cable is less than the port-side current I2, if so, the Y-type capacitor can effectively filter, otherwise it cannot effectively filter;

[0065] A4, determine whether the voltage across the multi-stage common-mode inductor in the EMI filter connected to the main radiating cable decreases step by step. If so, there is no hidden coupling in the multi-stage common-mode inductor. If not, there is hidden coupling in the common-mode inductor that does not decrease step by step.

[0066] The embodiment of the present invention provides a method for diagnosing the propagation path of radiation interference of a power electronic device, which adopts a radiation interference path diagnosis technology based on voltage and current detection.

[0067] 1. Lead the diagnostic process of radiating cable antennas.

[0068] For power electronics, cables, due to their large size, are always the primary radiation source. For high-power converters, the metal chassis acts as a shield, blocking radiation from the converter components. However, the external cables are the primary radiation source. For small, low-power power converters, even without a metal chassis, external cables remain the primary radiation source due to the small size of the converter itself.

[0069] Diagnosing the dominant radiating antenna is always necessary. This is particularly important for power electronics devices with multiple input / output cable antennas, but it is also essential for power electronics devices with a single input and output. Because the radiated electric fields from the input and output cables are not always identical, some studies have found significant differences in the radiated currents from the input and output cables.

[0070] According to the standard "GB / T 6113.203-2020 Radio disturbance and immunity measurement methods - Radiated disturbance measurement," during radiated EMI testing, cables should be terminated with a common mode absorber device (CMAD), which can be considered an open-circuit termination. Whether the cable is terminated independently or short-circuited and coupled, different radiation models are generated. Figure 11 (a) and (b) are simplified radiation models of typical cable antennas, including independent radiation and coupled radiation.

[0071] Figure 11 The independent radiation in (a) means that the antenna cables are not connected and each radiates independently. A power electronic device with multiple output cables is a typical example of an independent radiation model. This is because different output terminals need to be terminated with CMADs separately. In addition, a converter with a non-negligible chassis size is also a case of an independent radiation model. This is because the input and output cables and the chassis each form a pair of antennas. A typical feature of independent radiation is that the current on the cable may be very different. The dominant radiating antenna can be determined based on the current size, as shown in Equations (1) and (2). The radiated electric field E emitted by the device system is composed of the two cable antenna radiation electric fields E A1 ,E A2 Composition, each cable antenna electric field E A1 ,E A2 Both are related to the antenna current I A1 ,I A2 Proportional, the proportional coefficient is G IA1 ,G IA2 , and since the cable lengths are close, the proportional coefficients are similar. Then when I A1 Current ratio I A2 When it is larger, the radiation electric field E A1 Must be greater than E A2 , cable 1 is identified as the dominant antenna, as shown in Equation (2). Since the measured current of the cable is the antenna current, the measured current is the criterion for determining the dominant radiating antenna in the independent radiation model.

[0072] E=E A1 +E A2 =G IA1 I A1 +G IA2 I A2 ≈G IA (IA1 +I A2 ) (1)

[0073]

[0074] Figure 11 The coupled radiation in (b) typically occurs in power electronic devices with multiple inputs. Different power sources supply the device, such as multiple photovoltaic (PV) panels or multiple energy storage batteries. When performing radiated EMC testing, these multiple input cables are connected to the same input power source. Therefore, the cable antenna is short-circuited. In this model, the current in the coupled cable is directly connected, and the current I is measured. m Not equal to the antenna current I A The relationship between the measured current and the antenna current cannot be obtained based on the relationship between the measured current and the antenna current, as shown in Equation (3). Therefore, the measured current cannot be used as a criterion for the diagnosis of the dominant radiation cable in the coupled radiation model.

[0075]

[0076] Radiation voltage V A1 ,V A2 It can be used as the leading cable antenna diagnostic criterion for the coupled radiation model. The antenna radiation electric field is also linearly related to the antenna port voltage, G VA1 ,G VA2 is the proportional coefficient of the port voltage to the electric field of the two antennas, and the proportional coefficients are very close, as shown in Equation (4). It should be noted that the measured voltage is the antenna voltage, so the larger the measured antenna port voltage, the larger the electric field radiated by the antenna, as shown in Equation (5).

[0077] E=G VA1 V A1 +G VA2 V A2 ≈G VA (V A1 +V A2 ) (4)

[0078]

[0079] Figure 12It is the flowchart of the proposed antenna diagnosis method. For independent radiation, the radiation current can be used as the criterion for the dominant antenna. The antenna with the largest radiation current is the main radiation antenna. However, for coupled radiation, it is not appropriate to use only the magnitude of the radiation current as the criterion for the dominant antenna. Their radiation current amplitudes are always very close because they are connected to the same auxiliary power supply equipment. The radiation voltage measurement can solve the problem of diagnosing the dominant antenna in coupled radiation. The radiation voltage at the port is the fundamental cause of exciting the radiation current of the antenna. The highest radiation voltage excites the current in all antenna cables. Therefore, the radiation voltage is an accurate criterion for judging the dominant antenna.

[0080] 2. Diagnosis of the effectiveness of Y - type capacitor filtering

[0081] The Y - type capacitor in the converter, as an important part of electromagnetic interference filtering, provides a necessary path to bypass electromagnetic interference back to the chassis. However, for high - power power electronic devices, due to the existence of parasitic inductance and skin effect, the large metal chassis cannot be regarded as an equipotential body. There may be voltage jumps on the chassis reference ground, which may cause the current direction on the Y - capacitor not to flow into the ground but to flow out from the ground. The electromagnetic interference flowing out through the Y - capacitor will cause the electromagnetic interference filter to fail. It is impossible to directly measure the direction of the capacitor current because the capacitor pins are very small and an EMI current clamp cannot be installed.

[0082] Figure 13 (a) and (b) in it show the principle and process of path - direction diagnosis based on current measurement. Since the radiated EMI propagates outside the converter, the current directions of the converter - side and port - side currents I1 and I2 of the Y - capacitor are always determined to be outward, while the direction of the grounding current I of the Y - type capacitor is unknown. But at this node, according to Kirchhoff's Current Law (KCL), there is formula (1). According to the magnitudes of I2 and I1, the current direction of I can be determined. g At this node, according to Kirchhoff's Current Law (KCL), there is formula (1). According to the magnitudes of I2 and I1, the current direction of I can be determined. g is determined.

[0083] I1 - I2 = I g (6)

[0084] When I2 < I1, I g flows into the chassis ground, and the Y - capacitor plays an inhibitory role in electromagnetic interference. When I2 > I1, I g flows out from the chassis ground, and the Y - capacitor plays a deteriorating role in electromagnetic interference. In this case, continuously increasing the CM inductance impedance at I1 before the capacitor cannot suppress the emission of this capacitor branch. The flowchart of the proposed path - direction diagnosis method is as shown in Figure 13 (b) in it.

[0085] 3. Diagnosis of hidden coupling

[0086] Common-mode inductors (CM inductors), as a crucial component of EMI filtering and propagation paths, provide critical impedance for suppressing the propagation of radiated EMI. However, inductors are also susceptible to other undesirable and unknown couplings, which can cause radiated EMI to fail to be blocked as intended, potentially leading to filtering failure and even EMC certification failure. Therefore, diagnosing hidden and undesirable couplings is essential.

[0087] There are two main types of unwanted coupling: from upstream components and from other unknown sources, such as non-filter components such as fan lines. For multi-stage inductors between the converter and the filter input / output, the voltage across each inductor should decrease step by step. Otherwise, the inductor will have unwanted coupling and should be shielded. Taking the secondary common-mode inductor between the converter and the filter output / input as an example, the hidden coupling diagram is shown below. Figure 14 As shown in (a), where V a is the voltage of the front end of the first-stage common-mode inductor to ground, V b is the voltage of the first-stage common-mode inductor to ground, V c = is the voltage at the back end of the second-stage common-mode inductor to ground (i.e., the filter's input / output voltage). This undesirable hidden coupling causes the voltage distribution along the propagation path to differ from the ideal one. Therefore, hidden coupling can be diagnosed through voltage measurement.

[0088] When V a >V b >V c When V c >V b , then there is undesirable coupling and the common mode inductance should be shielded. The flowchart of the proposed hidden coupling diagnosis method is shown in the figure below. Figure 14 As shown in (b) in .

[0089] An embodiment of the present invention provides a device for diagnosing radiation interference sources of a power electronic device, comprising:

[0090] The first processing module is used to measure the radiated EMI time domain signal of the target power electronic device, perform FFT processing on it to obtain the corresponding EMI spectrum, and obtain the peak frequency f of the EMI spectrum. PK ;

[0091] The second processing module is used to calculate the K·f PK The radiated EMI time domain signal is band-pass filtered for the band-pass width; wherein the value range of K is [0.05, 0.1];

[0092] The second processing module is used to perform envelope demodulation and FFT processing on the radiated EMI time domain signal after bandpass filtering in sequence to obtain the switching frequency of the radiated interference source, and use the converter in the target power electronic device that uses the switching frequency as the modulation parameter as its radiated interference source.

[0093] An embodiment of the present invention provides a device for diagnosing a propagation path of radiated interference in a power electronic device, comprising:

[0094] a determination module, configured to determine a radiation type of a cable connected to a radiation interference source of a target power electronic device; wherein the radiation type includes independent radiation and coupled radiation. If the cables are all independently connected to a load, the radiation type is independent radiation; if the cables are all connected to a load together with other cables, the radiation type is coupled radiation;

[0095] A processing module is configured to determine a radiation interference propagation path of the target power electronic device based on the radiation type of the antenna; wherein, if the radiation type of the cable is independent radiation, the cable with the largest radiation current is used as the radiation cable, and its path is used as the radiation interference propagation path; if the radiation type of the cable is coupled radiation, the cable with the largest radiation voltage is used as the radiation cable, and its path is used as the radiation interference propagation path.

[0096] An embodiment of the present invention provides an electronic device, comprising: a computer-readable storage medium and a processor;

[0097] The computer-readable storage medium is used to store executable instructions;

[0098] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the radiation interference source diagnosis method of the power electronic device as described in any of the above embodiments or the radiation interference propagation path diagnosis method of the power electronic device as described in any of the above embodiments.

[0099] An embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions, and the computer instructions are used to enable a processor to execute the method for diagnosing the source of radiation interference of a power electronic device as described in any of the above embodiments or the method for diagnosing the propagation path of radiation interference of a power electronic device as described in any of the above embodiments.

[0100] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for diagnosing radiation interference sources of a power electronic device, characterized in that: include: S1, measure the radiated EMI time domain signal of the target power electronic device, perform FFT processing on it to obtain the corresponding EMI spectrum, and obtain the peak frequency of the EMI spectrum f PK ; S2, K· f PK The radiated EMI time domain signal is band-pass filtered for the band-pass width; wherein the value range of K is [0.05, 0.1]; S3, performing envelope demodulation and FFT processing on the radiated EMI time domain signal after bandpass filtering in sequence to obtain the switching frequency of the radiated interference source, and taking the converter in the target power electronic device that uses the switching frequency as a modulation parameter as its radiated interference source.

2. The method according to claim 1, wherein In step S1 , a high-bandwidth oscilloscope is used to measure the radiated EMI time domain signal of the target power electronic device.

3. The method according to claim 1 or 2, wherein: In step S3, the step of performing envelope demodulation and FFT processing on the bandpass filtered radiated EMI time domain signal in sequence to obtain the switching frequency of the radiated interference source includes: Performing Hilbert transform on the bandpass filtered radiated EMI time domain signal in sequence to calculate the upper envelope to obtain the switching pulse moment of the radiated EMI time domain signal; Perform FFT processing on the upper envelope to obtain an envelope spectrum, and obtain the switching frequency of the radiated EMI time domain signal according to the switching pulse moment.

4. A method for diagnosing the propagation path of radiation interference of a power electronic device, characterized in that: include: A1. Determine the radiation type of the cable connected to the radiation interference source of the target power electronic device; wherein the radiation type includes independent radiation and coupled radiation. If the cables are all independently connected to the load, the radiation type is independent radiation; if the cables are all connected to the load together with other cables, the radiation type is coupled radiation; A2. Determine the radiation interference propagation path of the target power electronic device based on the radiation type of the cable; if the radiation type of the cable is independent radiation, the cable with the largest radiation current is used as the radiation cable, and its path is used as the radiation interference propagation path; if the radiation type of the cable is coupled radiation, the cable with the largest radiation voltage is used as the radiation cable, and its path is used as the radiation interference propagation path; The radiation interference source of the target power electronic device is diagnosed by using the diagnosis method according to any one of claims 1 to 3.

5. The method according to claim 4, wherein Also includes: A3, determining the converter-side current of the Y-type capacitor in the EMI filter connected to the radiation cable I 1 Is it less than the port side current? I 2. If yes, the Y-type capacitor can effectively filter, otherwise it cannot effectively filter; A4, determine whether the voltage across the multi-stage common-mode inductor in the EMI filter connected to the main radiating cable decreases step by step. If so, there is no hidden coupling in the multi-stage common-mode inductor. If not, there is hidden coupling in the common-mode inductor that does not decrease step by step.

6. A device for diagnosing radiation interference sources of power electronic devices, characterized in that: include: The first processing module is used to measure the radiated EMI time domain signal of the target power electronic device, perform FFT processing on it to obtain the corresponding EMI spectrum, and obtain the peak frequency of the EMI spectrum f PK ; The second processing module is used to process K· f PK The radiated EMI time domain signal is band-pass filtered for the band-pass width; wherein the value range of K is [0.05, 0.1]; The second processing module is used to perform envelope demodulation and FFT processing on the radiated EMI time domain signal after bandpass filtering in sequence to obtain the switching frequency of the radiated interference source, and use the converter in the target power electronic device that uses the switching frequency as the modulation parameter as its radiated interference source.

7. A device for diagnosing the propagation path of radiation interference of a power electronic device, characterized in that: include: a determination module, configured to determine a radiation type of a cable connected to a radiation interference source of a target power electronic device; wherein the radiation type includes independent radiation and coupled radiation. If the cables are all independently connected to a load, the radiation type is independent radiation; if the cables are all connected to a load together with other cables, the radiation type is coupled radiation; a processing module, configured to determine a radiation interference propagation path of the target power electronic device based on the radiation type of the cable; wherein, if the radiation type of the cable is independent radiation, the cable with the largest radiation current is used as the radiation cable, and its path is used as the radiation interference propagation path; if the radiation type of the cable is coupled radiation, the cable with the largest radiation voltage is used as the radiation cable, and its path is used as the radiation interference propagation path; The radiation interference source of the target power electronic device is diagnosed by using the diagnostic device according to claim 6.

8. An electronic device, characterized in that: include: Computer-readable storage medium and processor; The computer-readable storage medium is used to store executable instructions; The processor is configured to read the executable instructions stored in the computer-readable storage medium and execute the method according to any one of claims 1 to 3 or the method according to any one of claims 4 to 5.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to execute the method according to any one of claims 1 to 3 or the method according to any one of claims 4 to 5.

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