A parasitic parameter-based wide-bandgap device switching current measurement method and system

Abstract

The application discloses a kind of based on parasitic parameter wide band gap device switch current measurement method and system, select a section of line of power loop as detection line, and detection line is the only flow path of switch current;The voltage waveform at both ends of detection line is measured, and the measurement waveform is obtained;And carry out smooth denoising processing and fourier decomposition, the fourier series obtained is as the amplitude and phase under different frequency components of measurement waveform;The amplitude and phase under different frequencies are compensated based on the transmission characteristics of passive voltage probe, and the amplitude and phase of voltage waveform at both ends of detection line under different frequencies are obtained;According to the relationship between the voltage waveform at both ends of detection line and the amplitude and phase of switch current under different frequencies, the amplitude and phase of switch current under different frequencies are obtained, the fourier series of switch current is synthesized, and the waveform of switch current is obtained, to complete switch current measurement.The application has no influence on power loop layout, is easy to integrate, and can promote the wide application of wide band gap device.

Description

Technical Field

[0001] This invention belongs to the technical field, specifically relating to a method and system for measuring the switching current of wide bandgap devices based on parasitic parameters. Background Technology

[0002] Power electronics technology is a crucial supporting technology for the national economy and national security, and an important means to achieve energy conservation, environmental protection, and improve people's quality of life. High-efficiency and high-quality power conversion is the ultimate goal of power electronics technology development, and the demand for higher efficiency and power density is the driving force behind its progress. Due to the approaching theoretical limits of materials, traditional silicon (Si) devices have reached their theoretical limits, and the potential for further optimizing Si devices to improve power converter performance is very limited, failing to meet the future application demands for higher efficiency and power density. New-generation wide-bandgap (WBG) semiconductor devices, such as silicon carbide (SiC) and gallium nitride (GaN) devices, although still in the early stages of development, have already shown enormous potential. Due to the superior material properties, such as higher electron mobility, higher saturation electron velocity, and higher breakdown field compared to Si, WBG devices exhibit higher switching speeds and lower on-state resistance. By using WBG devices, the switching frequency can be significantly increased without increasing power loss, thereby achieving higher efficiency and power density. Therefore, WBG devices have extremely broad application prospects.

[0003] However, as the switching frequency increases, switching losses begin to dominate the total power loss. Accurate assessment of switching losses is crucial for fast WBG devices, with the key being accurate measurement of the switching waveforms, including switching voltage and switching current. To accurately capture the fast switching transients (only a few nanoseconds) of WBG devices, the measurement system needs sufficiently high bandwidth to capture the switching waveforms accurately. For example, for fast GaN devices, whose typical rise / fall times are only 2 ns, the measurement system should have a bandwidth of at least (3–5) × 175 MHz. Therefore, for measuring the switching voltage, the passive voltage probes TPP1000 or TPP0850 are sufficient.

[0004] The measurement of switching current requires not only sufficiently high bandwidth but also low insertion impedance. Among existing commercial current probes, Hall effect current probes and Rogowski coils have relatively low bandwidths, failing to meet the measurement requirements. For example, the TCP0030A probe, with the highest bandwidth among commercial Hall effect current probes, has a bandwidth of only 120MHz, while the TRCP0300 probe, with the highest bandwidth among Rogowski coils, has a bandwidth of only 30MHz. Currently, the widely used switching current measurement method for WBG devices is the coaxial current shunt. Due to its coaxial structure, its bandwidth can reach 2GHz, and its structure is as follows... Figure 1As shown in (a). However, as Figure 1 As shown in (b) and (c), the large size of the coaxial current shunt inevitably introduces a significant additional inductance into the power circuit, such as Figure 2 As shown. On the one hand, the increased insertion impedance alters the switching waveform, thus adversely affecting measurement accuracy. On the other hand, the high switching speed of WBG devices makes them highly susceptible to parasitic inductance, which can lead to severe voltage overshoot and ringing, potentially causing device damage. Therefore, the large insertion inductance introduced by the coaxial current shunt is unacceptable for fast WBG devices.

[0005] To date, researchers have made significant efforts to reduce the insertion inductance introduced by current sensors. Among these efforts, some researchers have proposed a surface-mount coaxial shunt resistor by combining the coaxial structure of a coaxial current shunt with a small-sized surface-mount resistor. Figure 3 As shown, the insertion inductance is still around 0.56nH. Another method to reduce the insertion inductance is to use a large number of small resistors in parallel to measure the switching current, but the measurement accuracy is not ideal due to current sharing problems caused by the skin effect and proximity effect in the measurement circuit, as well as coupling inductance. Some researchers have also proposed using a multilayer printed circuit board (PCB) design to embed a single-turn coil, such as... Figure 4 As shown, the switching current is derived by utilizing the coupling relationship between the detection coil and the power circuit. However, the detection coil in this method requires careful design, and its post-processing and correction are also very complex. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and system for measuring the switching current of wide bandgap devices based on parasitic parameters, which addresses the shortcomings of the prior art. This method enables accurate measurement of the high-speed switching current of WBG devices, has almost no impact on the layout of the power circuit, does not introduce additional insertion impedance, and has the advantage of easy integration.

[0007] The present invention adopts the following technical solution:

[0008] A method for measuring the switching current of a wide bandgap device based on parasitic parameters includes the following steps:

[0009] S1. Select a section of the power circuit as the detection line, and the detection line is the only path for the switching current to flow.

[0010] S2. Measure the voltage waveform at both ends of the detection line determined in step S1 to obtain the measured waveform;

[0011] S3. Perform smoothing and noise reduction processing on the measurement waveform obtained in step S2;

[0012] S4. Perform Fourier decomposition on the measurement waveform after smoothing and denoising in step S3, and use the obtained Fourier series as the amplitude and phase of the measurement waveform at different frequency components.

[0013] S5. Based on the transmission characteristics of the passive voltage probe, the amplitude and phase at different frequencies obtained in step S4 are compensated to obtain the amplitude and phase of the voltage waveform at both ends of the detection line at different frequencies.

[0014] S6. Use finite element simulation to determine the frequency-related parasitic parameters of the detection line. Based on the relationship between the frequency-related parasitic parameters and the amplitude and phase of the voltage and switching current at different frequencies at the two ends of the detection line, use the amplitude and phase of the voltage waveform at the two ends of the detection line obtained in step S5 to obtain the amplitude and phase of the switching current at different frequencies respectively.

[0015] S7. Using the amplitude and phase of the switching current at different frequencies obtained in step S6, the Fourier series of the switching current is synthesized to obtain the waveform of the switching current, thus completing the switching current measurement.

[0016] Specifically, in step S1, a section of the line between the source of the lower switching transistor in the half-bridge circuit and the system ground is used as a detection line.

[0017] Specifically, in step S2, a high-bandwidth passive voltage probe is used to measure the voltage waveform v at both ends of the detection line. sense Measurements were performed using a grounding spring as the grounding method, and the voltage waveform v across the test line was measured. sense Specifically:

[0018]

[0019] Where R0 is the DC parasitic resistance of the detection line, I0 is the DC component of the switching current, and Z k To detect the parasitic impedance of the line at the kth harmonic frequency, I k Let ω be the amplitude of the switching current at the k-th harmonic frequency, where k is the harmonic order, ω is the fundamental angular frequency, and t is time. Let be the phase angle of the switching current at the kth harmonic frequency. The parasitic impedance angle of the detection line at the kth harmonic frequency is given.

[0020] Specifically, in step S3, the wavelet signal denoiser toolbox is used to measure the waveform v. sense Perform smoothing and noise reduction processing.

[0021] Specifically, in step S5, a passive voltage probe is modeled, and the transmission characteristics of the passive voltage probe are obtained based on the established probe model. The probe transmission characteristics are used as the measured value of the detection line voltage v. sense 'and actual value v sense The relationship between amplitude and phase at different frequencies is relevant to the measurement waveform v. sense The amplitude and phase at different frequencies are compensated to obtain the actual voltage waveform v. sense .

[0022] Furthermore, measure the waveform v sense Specifically:

[0023]

[0024] Where V0' is the DC component of the measured voltage value, V k 'This refers to the amplitude of the measured voltage at the k-th harmonic frequency, where k is the harmonic order, ω is the fundamental frequency, and t is time.' The phase angle of the voltage measurement at the kth harmonic frequency is used to detect the voltage measurement value.

[0025] Specifically, in step S6, the voltage waveform v across the detection line is measured. sense With switching current i D2 The relationship between amplitude and phase at different frequencies is as follows:

[0026]

[0027]

[0028]

[0029] Where V0 is the DC component of the detection voltage, I0 is the DC component of the switching current, R0 is the DC parasitic resistance of the detection line, and V k To detect the amplitude of the voltage at the kth harmonic frequency, I k Z is the amplitude of the switching current at the kth harmonic frequency. k To detect the parasitic impedance of the test line at the kth harmonic frequency, To detect the phase angle of the voltage at the kth harmonic frequency, Let be the phase angle of the switching current at the kth harmonic frequency. The parasitic impedance angle of the detection line at the kth harmonic frequency is given.

[0030] Furthermore, the relationship between amplitude attenuation and phase shift from the probe measurement end to the oscilloscope input end and the signal frequency is as follows:

[0031]

[0032]

[0033]

[0034] Where V0 is the DC component of the detected voltage, V0' is the DC component of the measured detected voltage, G(j0) is the DC amplitude of the complex transfer function of the probe-oscilloscope system, and V k To detect the amplitude of the voltage at the kth harmonic frequency, V k 'G(jkω)| represents the amplitude of the measured voltage at the k-th harmonic frequency, and |G(jkω)| represents the amplitude of the complex transfer function of the probe-oscilloscope system at the k-th harmonic frequency. To detect the phase angle of the voltage at the kth harmonic frequency, To detect the phase angle of the voltage measurement at the kth harmonic frequency, Let be the phase angle of the complex transfer function of the probe-oscilloscope system at the kth harmonic frequency.

[0035] Specifically, in step S7, the switching current i D2 Specifically:

[0036]

[0037] Where I0 is the DC component of the switching current, I k Let ω be the amplitude of the switching current at the k-th harmonic frequency, where k is the harmonic order, ω is the fundamental frequency, and t is time. Let be the phase angle of the switching current at the kth harmonic frequency.

[0038] Secondly, embodiments of the present invention provide a wide-bandgap device switching current measurement system based on parasitic parameters, comprising:

[0039] Select a module, choose a section of the power circuit as the detection line, and ensure that the detection line is the only path for the switching current to flow.

[0040] The waveform module measures the voltage waveform at both ends of the detection line determined by the selected module to obtain the measured waveform;

[0041] The processing module performs smoothing and noise reduction processing on the measurement waveform obtained by the waveform module.

[0042] The decomposition module performs Fourier decomposition on the measurement waveform after smoothing and denoising by the processing module, and uses the obtained Fourier series as the amplitude and phase of the measurement waveform at different frequency components.

[0043] The compensation module, based on the transmission characteristics of the passive voltage probe, compensates for the amplitude and phase at different frequencies obtained by the decomposition module, thereby obtaining the amplitude and phase of the voltage waveform at both ends of the detection line at different frequencies.

[0044] The calculation module uses finite element simulation to determine the frequency-related parasitic parameters of the detection line. Based on the relationship between the frequency-related parasitic parameters and the amplitude and phase of the voltage and switching current at different frequencies at the two ends of the detection line, the amplitude and phase of the switching current at different frequencies are obtained by using the amplitude and phase of the voltage waveform at the two ends of the detection line at different frequencies obtained by the compensation module.

[0045] The measurement module uses the amplitude and phase of the switching current at different frequencies obtained from the calculation module to synthesize the Fourier series of the switching current, thereby obtaining the waveform of the switching current and completing the switching current measurement.

[0046] Compared with the prior art, the present invention has at least the following beneficial effects:

[0047] This invention discloses a method for measuring the switching current of wide-bandgap devices based on parasitic parameters. A segment of the power circuit is selected as the detection line, and the voltage waveform at both ends of the detection line is measured to obtain the measured waveform. Smoothing and noise reduction processing, along with Fourier decomposition, are then performed. The resulting Fourier series is used as the amplitude and phase of the measured waveform at different frequency components. Based on the transmission characteristics of a passive voltage probe, compensation is applied to the amplitude and phase at different frequencies to obtain the amplitude and phase of the voltage waveform at both ends of the detection line at different frequencies. The amplitude and phase of the switching current at different frequencies are then calculated based on the relationship between the voltage waveform at both ends of the detection line and the amplitude and phase of the switching current at different frequencies. The Fourier series of the switching current are synthesized to obtain the waveform of the switching current, thus completing the switching current measurement. This invention enables high-bandwidth switching current measurement with almost no impact on the power circuit layout, and has the advantages of low insertion impedance and easy integration.

[0048] Furthermore, the section of the circuit between the source of the lower switching transistor and system ground in the half-bridge circuit should be used as a detection line, ensuring that the designed detection line is the only path for the switching current. This ensures that the detection line shares a common ground with the power circuit, facilitating measurement.

[0049] Furthermore, a high-bandwidth passive voltage probe is used to measure the voltage waveform v across the detection line. sense Measurements are performed to ensure the most accurate measurement of high-frequency signals. A grounding spring is used as the grounding method to detect the voltage waveform v across the two ends of the detection line. sense This reduces the impact of probe grounding inductance on the measurement.

[0050] Furthermore, the wavelet signal denoiser toolbox in MATLAB software was used to measure the waveform v.sense 'Smoothing and denoising processing is performed. Based on wavelet analysis theory, noise interference in the measured signal is removed while retaining useful information, thereby ensuring measurement accuracy.'

[0051] Furthermore, a passive voltage probe is modeled, and its transmission characteristics are obtained based on the established probe model. These transmission characteristics are used as the measured value of the detection line voltage, v. sense 'and actual value v sense The relationship between amplitude and phase at different frequencies is relevant to the measurement waveform v. sense The amplitude and phase at different frequencies are compensated to obtain the actual detected voltage waveform v. sense This can further improve measurement accuracy and reduce the impact of oscilloscope probe bandwidth on the measurement, thereby enabling accurate measurement of the actual detected voltage v. sense Accurate measurement.

[0052] Furthermore, the waveform v will be measured. sense Expanding this into a Fourier series yields the amplitude and phase of its different frequency components, which can then be compensated to obtain the actual detected voltage v. sense .

[0053] Furthermore, based on the relationship between amplitude attenuation and phase shift from the probe measurement end to the oscilloscope input end and the signal frequency, the measurement result v... sense The Fourier series of ' gives the detected voltage v sense The Fourier series is used to realize the actual detection voltage v. sense Accurate measurement.

[0054] Furthermore, based on the voltage waveform v across the detection line... sense With switching current i D2 The relationship between amplitude and phase at different frequencies yields the switching current i. D2 The Fourier series of .

[0055] Furthermore, due to the switching current i D2 The Fourier series of the switching current i are synthesized to obtain the switching current i. D2 The waveform is the accurate measurement result of the switching current.

[0056] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0057] In summary, this invention does not affect the power circuit layout, is easy to integrate, and can remove obstacles to the accurate assessment of switching losses of fast WBG devices, thus promoting the widespread application of WBG devices.

[0058] The following description, using the switching current test of GaN devices as an example, along with the accompanying drawings and embodiments, provides a further detailed explanation of the technical solution of the present invention. Attached Figure Description

[0059] Figure 1 The figures are cross-sectional views of a coaxial current shunt, (a) showing the coaxial structure, (b) showing a physical diagram of the coaxial current shunt, and (c) showing a physical diagram of a GaN device.

[0060] Figure 2 The diagram shows a comparison of the power loop area of ​​a GaN half-bridge with and without a coaxial current shunt, where (a) is a GaN half-bridge with a coaxial current shunt and (b) is a GaN half-bridge without a coaxial current shunt.

[0061] Figure 3 Schematic diagrams of PCB designs for two types of surface-mount coaxial shunt resistors;

[0062] Figure 4 Equivalent circuit diagram for a switching current measurement method with embedded single-turn coil;

[0063] Figure 5 This is a schematic diagram of a dual-pulse test (DPT) circuit based on GaN devices;

[0064] Figure 6 This document provides an example of a half-bridge circuit PCB design and a schematic diagram illustrating the design and selection of detection lines.

[0065] Figure 7 Parasitic parameter curves of sensor traces extracted by Ansys Q3D Extractor;

[0066] Figure 8 A schematic diagram of the equivalent circuit model of the probe-oscilloscope system connecting the circuit;

[0067] Figure 9 The image shows the impedance characteristic curves of the TPP1000 probe, where the solid line is the curve fitted from the data table and the dashed line is the curve obtained through modeling.

[0068] Figure 10 A comparison diagram of the impedance of the probe-oscilloscope system and the impedance of the detection line;

[0069] Figure 11 This is a schematic diagram of the probe's transmission characteristics;

[0070] Figure 12 This is a flowchart of the present invention;

[0071] Figure 13 This is a comparison chart of the switching current waveforms when the load current is 2A in a specific application example;

[0072] Figure 14 Here is a comparison chart of the switching current waveforms when the load current is 5A in a specific application example;

[0073] Figure 15 A comparison of the switching current waveforms when the load current is 10A in a specific application example;

[0074] Figure 16 This is a comparison diagram of the switching current waveforms when the load current is 20A in a specific application example. Detailed Implementation

[0075] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0076] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0077] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0078] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" relationship.

[0079] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0080] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0081] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0082] This invention provides a method for measuring the switching current of wide bandgap devices (WBGs) based on parasitic parameters. This method enables accurate measurement of the high-speed switching current of WBGs, has almost no impact on the layout of the power circuit, does not introduce additional insertion impedance, and has the advantage of easy integration. By accurately measuring the high-frequency switching current of WBGs, accurate assessment of their switching losses can be achieved, guiding the high-frequency application design of WBGs and ultimately fully leveraging their high-frequency performance.

[0083] Please see Figure 12 The present invention discloses a method for measuring the switching current of a wide bandgap device based on parasitic parameters, comprising the following steps:

[0084] S1. Select a section of the line from the source of the switching transistor Q2 to the system ground as the detection line, while ensuring that the detection line carries the switching current i. D2 The only circulation path;

[0085] Using a section of the power circuit (from the source of the lower switching transistor to system ground) as the test line, the current in this section is the switching current i of the device under test (DUT). D2 The present invention aims to measure the voltage v across the detection line. sense and using v sense and i D2 The relationship between them is shown in Equation (1), and the switching current i of the DUT can then be derived. D2 .

[0086]

[0087] Among them, L sense R senseM and M are respectively the parasitic self-inductance, parasitic resistance, and the relationship between the detection line and the above-mentioned detection line. Figure 5 The mutual inductance between other parts of the power circuit shown.

[0088] Figure 5 A dual-pulse test (DPT) circuit based on GaN devices is shown, which is widely used to evaluate the dynamic performance of power devices. In the DPT circuit, the upper switching transistor is connected to the load inductor L. O Parallel connection, for its current i O Provides a freewheeling path. The drain of the lower switching transistor Q2 is connected to the source of Q1, and the decoupling capacitor C... in It is connected in parallel with the series circuit of Q1 and Q2 to form a power loop. in With DC voltage V dc Parallel connection. L sense and R sense These are the parasitic self-inductance and parasitic resistance of a line segment (detection line) from the source of Q2 to ground, respectively. rest It is the parasitic inductance of other parts of the power circuit, M is L rest and L sense Mutual intuition between them, L in It is V dc With C in The parasitic inductance of the lines between them.

[0089] Since i cannot be directly obtained from equation (1) D2 Regarding v sense The expression, and v sense The function of time t is also unknown and very complex, making it difficult to directly solve this first-order non-homogeneous differential equation. To conveniently, quickly, and accurately solve this equation from the voltage waveform v... sense The measured waveform yields the switching current i D2 The waveform is shown in the figure. This invention provides a detailed derivation based on Fourier series theory. According to Fourier series theory, a periodic function can be considered as a superposition of infinitely many sine and cosine functions of different frequencies, i.e., a Fourier series.

[0090] Therefore, the periodic voltage waveform v sense and switching current i D2 They are written as:

[0091]

[0092]

[0093] Where V0 and I0 are DC components, and f is the fundamental frequency.

[0094] Due to the skin effect and proximity effect, L sense R senseSince M is frequency-dependent, it should be taken into account. Substituting (3) into (1), we get:

[0095]

[0096] Where R0 is the DC parasitic resistance of the detection line, R k =R sense (kf), L k =L sense (kf)-M(kf),

[0097] By comparing (2) and (4), we can obtain:

[0098]

[0099]

[0100]

[0101] (5)~(7) are v sense and i D2 The relationship between the amplitude and phase of the Fourier series components at different frequencies.

[0102] It is worth noting that the selection and design of the sense line are crucial for accurate measurement of the switching current. On one hand, the sense line should have sufficiently high parasitic parameters to ensure adequate measurement sensitivity. On the other hand, since fast WBG devices are highly susceptible to parasitic inductance, the insertion impedance introduced by the sense line into the power loop should be as small as possible and should not affect the power loop layout. To ensure measurement accuracy, the selected sense line should be i D2 The only path should be shared with the circuit ground for easy measurement. Therefore, as mentioned above, this invention uses a section of the line from the source of the lower switching transistor in the half-bridge circuit to the system ground as the detection line, such as... Figure 5 As shown, Figure 6 The image shows a PCB design example of a detection line based on a half-bridge circuit, along with the detection line itself. The parasitic parameters used in this method are selected based on this PCB design.

[0103] S2. Use a high-bandwidth passive voltage probe TPP1000 to measure the voltage waveform v across the detection line determined in step S1. sense The measurement was performed, and the measured waveform v was obtained. sense ';

[0104] Guarantee i D2 The key to accurate measurement is v senseAccurate measurement is crucial. Even using the 1GHz high-bandwidth passive voltage probe TPP1000 is insufficient to guarantee measurement accuracy. The influence of the voltage probe on the measurement results needs to be considered and compensated for and corrected. Therefore, accurate modeling of the passive voltage probe TPP1000 is necessary. The passive voltage probe consists of four parts: the probe tip, coaxial cable, compensation network, and ground wire. It can be represented by an equivalent circuit of series and parallel resistors, capacitors, and inductors, as shown in the diagram. Figure 8 As shown, the probe tip can be connected in series with a resistor R. P Probe input capacitor C P and series resistor R P1 The parallel circuit is used for modeling; the coaxial cable, as a lossy transmission line, can be modeled by a series of line elements (R, L, G, C) connected in series and parallel; the probe compensation network consists of R trim R comp and C comp Modeling. R S and C S These are the input resistors and capacitors of the oscilloscope, R. S1 It is C S The series resistance. Grounding inductance L P The value of is related to the grounding technology.

[0105] Among them, the series resistance R of the probe P and input capacitor C P The input resistance R of the oscilloscope S and input capacitor C S The parasitic inductance of the 1 / 2” grounding spring is 10nH, obtained from the datasheets of the probe and oscilloscope, respectively. Other parameters R... P1 R, L, G, C, R trim R comp C comp and R S1 Parametric scanning AC analysis was performed using simulation software to ensure a good match between the impedance characteristics of the model and the impedance characteristics of the probe. Figure 9 As shown.

[0106] When a high-bandwidth passive voltage probe is connected to the circuit to measure the voltage across the detection leads, it will act as a load, drawing current from the circuit. This will affect the circuit's operation and further influence the measurement results. To minimize the load effect, the impedance |Z of the probe-oscilloscope system should be adjusted. P (s)|s should be much higher than the impedance of the detection line|Z sense (s)|, by comparing |Z P (s)| and |Z sense (s)| It can be seen that, as Figure 10 As shown, within the frequency range of 1kHz to 1GHz, |Z P(s)|ratio|Z sense (s)| More than 100 times higher. This is due to the extremely small parasitic capacitance of the TPP1000 probe, so the load effect of the passive voltage probe on the measurement can be ignored.

[0107] S3. Use the wavelet signal denoising toolbox in MATLAB software to denoise the measured waveform v obtained in step S2. sense Perform smoothing and noise reduction processing;

[0108] Before performing compensation and correction, it is usually necessary to smooth and denoise the measured signal because oscilloscope measurement signals often contain Gaussian white noise, which can affect measurement accuracy. The waveform can be effectively smoothed and denoised using the wavelet signaldenoiser toolbox in MATLAB.

[0109] S4. Use MATLAB software to smooth and denoise the v after step S3. sense The signal is decomposed into Fourier series, which are the amplitude and phase of different frequency components.

[0110] S5. Model the passive voltage probe TPP1000. Based on the established probe model, obtain the probe's transmission characteristics. Based on the probe's transmission characteristics, use MATLAB software to smooth and denoise the voltage probe obtained in step S4. sense The amplitude and phase at different frequencies are compensated to obtain v. sense Amplitude and phase at different frequencies;

[0111] Besides requiring sufficiently small load effects, the probe circuit from the probe tip to the oscilloscope input should also have the smallest possible attenuation and phase to ensure sufficiently high signal fidelity. Based on the established model, the probe's transmission characteristics can be obtained, such as... Figure 11 As shown, the gain from the probe tip to the oscilloscope input remains stable until around 20MHz, then gradually decreases to 3dB at 1GHz. Furthermore, when the signal frequency is above 10MHz, a phase difference begins to appear between the signal at the probe tip and the signal at the oscilloscope input. For high-frequency WBG devices, the oscillation frequency during switching transients is typically above 100MHz, thus distorting the measured waveform.

[0112] Additionally, grounding inductance affects the probe's bandwidth. The 1GHz bandwidth of the passive voltage probe was measured using a 1 / 2” grounding spring. If a 6” ground wire with a parasitic inductance of approximately 150nH is used, the bandwidth will be further reduced. Figure 11 As shown. To achieve this, we need to... sense For accurate measurement, a grounding spring should be used as the grounding method.

[0113] Simultaneously, compensation and correction of the measured detection voltage are also essential. As mentioned earlier, due to bandwidth limitations, the measured value of the detection voltage v... sense 'and actual value v sense There are certain differences in amplitude and phase, both of which can be regarded as the superposition of infinitely many sine and cosine functions of different frequencies, as shown in equations (2) and (8).

[0114]

[0115] The relationship between amplitude attenuation and phase shift from the probe measurement end to the oscilloscope input end and signal frequency is shown in equations (2) and (8)-(12). The transmission characteristics of the probe are also the measured value of the detection line voltage v. sense 'and actual value v sense The relationship between amplitude and phase at different frequencies.

[0116] Assuming the probe-oscilloscope system is linear time-invariant (LTI), then:

[0117]

[0118] Where G(jω) is the complex transfer function of the probe-oscilloscope system, obtained from the established probe model, as follows: Figure 11 As shown.

[0119] From equations (2), (8), and (9), we get:

[0120]

[0121]

[0122]

[0123] By measuring the detection voltage v sense By performing compensation and correction, the actual voltage waveform v can be obtained. sense Therefore, the switching current i can be accurately derived. D2 .

[0124] S6. Using the finite element simulation software Ansys Q3D Extractor, the frequency-related parasitic parameters L of the detection line are obtained. sense R sense The M value is determined based on the voltage v across the detection line. sense With switching current i D2 The relationship between amplitude and phase at different frequencies (5) to (7), obtained from step S5. sense The amplitude and phase at different frequencies are obtained respectively. D2 Amplitude and phase at different frequencies;

[0125] The frequency-dependent parasitic parameters of the detection line were accurately simulated using the finite element analysis (FEA) software Ansys Q3D Extractor, namely: L sense R sense And M, such as Figure 7 As shown, equations (2), (3) and (5)-(7) can then be used to determine the measured detection voltage v. sense Accurately derive i D2 .

[0126] S7, i based on step S6 D2 The amplitude and phase at different frequencies were determined using MATLAB software according to equation (3) for i. D2 The Fourier series are synthesized to obtain the switching current i. D2 The waveform.

[0127] Based on the above technical solutions, the present invention ultimately achieves a high-bandwidth, high-precision, low-insertion-impedance, and easily integrated switching current measurement.

[0128] In another embodiment of the present invention, a wide bandgap device switching current measurement system based on parasitic parameters is provided. This system can be used to implement the above-mentioned wide bandgap device switching current measurement method based on parasitic parameters. Specifically, the wide bandgap device switching current measurement system based on parasitic parameters includes a selection module, a waveform module, a processing module, a decomposition module, a compensation module, a calculation module, and a measurement module.

[0129] Among them, the selection module selects a section of the power circuit as the detection line, and the detection line is the only path for the switching current to flow.

[0130] The waveform module measures the voltage waveform at both ends of the detection line determined by the selected module to obtain the measured waveform;

[0131] The processing module performs smoothing and noise reduction processing on the measurement waveform obtained by the waveform module.

[0132] The decomposition module performs Fourier decomposition on the measurement waveform after smoothing and denoising by the processing module, and uses the obtained Fourier series as the amplitude and phase of the measurement waveform at different frequency components.

[0133] The compensation module, based on the transmission characteristics of the passive voltage probe, compensates for the amplitude and phase at different frequencies obtained by the decomposition module, thereby obtaining the amplitude and phase of the voltage waveform at both ends of the detection line at different frequencies.

[0134] The calculation module uses finite element simulation to determine the frequency-related parasitic parameters of the detection line. Based on the relationship between the frequency-related parasitic parameters and the amplitude and phase of the voltage and switching current at different frequencies at the two ends of the detection line, the amplitude and phase of the switching current at different frequencies are obtained by using the amplitude and phase of the voltage waveform at the two ends of the detection line at different frequencies obtained by the compensation module.

[0135] The measurement module uses the amplitude and phase of the switching current at different frequencies obtained from the calculation module to synthesize the Fourier series of the switching current, thereby obtaining the waveform of the switching current and completing the switching current measurement.

[0136] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0137] The dual-pulse half-bridge topology exemplified in this invention is essentially the same as bridge circuit topologies such as Buck or Boost. Therefore, the method of this invention is also applicable to Buck, Boost, and other bridge converter topologies.

[0138] Based on the method proposed in this invention, a DPT experimental platform was established, and DPT experiments were conducted. The detection voltage v was measured at output currents of 2A, 5A, 10A, and 20A. sense The drain current i measured by the coaxial current shunt D2 and output current i L The waveform is obtained and exported from the oscilloscope.

[0139] Using the wavelet signal denoising toolbox in MATLAB to denoise v sense After denoising the waveform, compensation and correction are performed by considering the probe model. After compensation, the amplitude of the waveform is amplified and the phase is shifted forward. MATLAB is used to analyze v... sense Perform a Fourier transform and derive the switching current i using the aforementioned method. D2 .

[0140] exist Figure 13 , Figure 14 , Figure 15 and Figure 16 In the diagram, the switching current i is derived under output currents of 2A, 5A, 10A, and 20A (before and after compensation). D2 i measured by a coaxial current shunt D2 Comparison. Due to the influence of the probe on the measurement, directly from the measured v... sense The derived switching current waveform has a large error, with its amplitude being smaller and its phase lagging behind that of the coaxial current shunt. Compensation is achieved by considering a probe model, amplifying the amplitude and shifting the phase forward.

[0141] from Figure 13 , Figure 14 , Figure 15 and Figure 16 It can be seen that the switching current measured by the proposed method, after compensation, can match well with the switching current waveform measured by the coaxial current shunt. Therefore, the accuracy of the proposed switching current measurement method, including probe model-based compensation, can be verified.

[0142] In summary, the present invention provides a method and system for measuring the switching current of wide bandgap devices based on parasitic parameters. This method obtains the switching current by measuring the voltage across the detection line. It utilizes a common high-bandwidth passive voltage probe for measurement, and by compensating the voltage probe, achieves high-bandwidth measurement, improving measurement accuracy. It eliminates the need for additional measurement components, resulting in low cost and easy integration. Therefore, it shows great promise for performance evaluation in GaN high-power-density converters and integrated modules.

[0143] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for measuring the switching current of a wide bandgap device based on parasitic parameters, characterized in that, Includes the following steps: S1. Select a section of the power circuit as the detection line, and the detection line is the only path for the switching current to flow. S2. Measure the voltage waveform at both ends of the detection line determined in step S1 to obtain the measured waveform. Use a high-bandwidth passive voltage probe to measure the voltage waveform at both ends of the detection line. v sense Measurements were performed using a grounding spring as the grounding method, and the voltage waveform across the test line was measured. v sense Specifically: in, The DC parasitic resistance of the detection line, This represents the DC component of the switching current. For the detection line at the first Parasitic impedance at subharmonic frequencies For the switching current in the first... Amplitude at the second harmonic frequency For harmonic order, The fundamental angular frequency, For time, For the switching current in Phase angle at subharmonic frequencies For the detection line at the first Parasitic impedance angle at subharmonic frequencies; S3. Use the wavelet signal denoiser toolbox to analyze the measurement waveform obtained in step S2. v sense Perform smoothing and noise reduction processing; S4. Perform Fourier decomposition on the measurement waveform after smoothing and denoising in step S3, and use the obtained Fourier series as the amplitude and phase of the measurement waveform at different frequency components. S5. Based on the transmission characteristics of the passive voltage probe, compensate for the amplitude and phase at different frequencies obtained in step S4 to obtain the amplitude and phase of the voltage waveform at both ends of the detection line at different frequencies. Model the passive voltage probe and obtain its transmission characteristics based on the established probe model. The probe transmission characteristics are used as the measured value of the detection line voltage. v sense 'and actual value v sense The relationship between amplitude and phase at different frequencies is important for measuring waveforms. v sense The amplitude and phase at different frequencies are compensated to obtain the actual voltage waveform. v sense ; S6. Use finite element simulation to determine the frequency-related parasitic parameters of the detection line. Based on the relationship between the frequency-related parasitic parameters and the amplitude and phase of the voltage and switching current at different frequencies at the two ends of the detection line, use the amplitude and phase of the voltage waveform at the two ends of the detection line obtained in step S5 to obtain the amplitude and phase of the switching current at different frequencies respectively. S7. Using the amplitude and phase of the switching current at different frequencies obtained in step S6, the Fourier series of the switching current is synthesized to obtain the waveform of the switching current, thus completing the switching current measurement.

2. The method for measuring the switching current of a wide bandgap device based on parasitic parameters according to claim 1, characterized in that, In step S1, the line between the source of the lower switching transistor and the system ground in the half-bridge circuit is used as a detection line.

3. The method for measuring the switching current of a wide bandgap device based on parasitic parameters according to claim 1, characterized in that, In step S5, the waveform is measured. v sense Specifically: in, To detect the DC component of the voltage measurement, To detect the voltage measurement value at the first Amplitude at the second harmonic frequency For harmonic order, For the fundamental frequency, For time, To detect the voltage measurement value at the first Phase angle at the subharmonic frequency.

4. The method for measuring the switching current of a wide bandgap device based on parasitic parameters according to claim 1, characterized in that, In step S6, the voltage waveform across the detection line is measured. v sense With switching current i D2 The relationship between amplitude and phase at different frequencies is as follows: in, V 0 represents the DC component of the detected voltage. I 0 represents the DC component of the switching current. The DC parasitic resistance of the detection line, To detect the voltage at the first Amplitude at the second harmonic frequency For the switching current in the first... Amplitude at the second harmonic frequency For the detection line at the first Parasitic impedance at subharmonic frequencies To detect the voltage at the first Phase angle at subharmonic frequencies For the switching current in the first... Phase angle at subharmonic frequencies For the detection line at the first Parasitic impedance angle at subharmonic frequencies.

5. The method for measuring the switching current of a wide bandgap device based on parasitic parameters according to claim 4, characterized in that, The specific relationship between amplitude attenuation and phase shift from the probe measurement end to the oscilloscope input end and the signal frequency is as follows: in, To detect the DC component of the voltage, To detect the DC component of the voltage measurement, The DC amplitude of the complex transfer function of the probe-oscilloscope system. To detect the voltage at the first Amplitude at the second harmonic frequency To detect the voltage measurement value at the first Amplitude at the second harmonic frequency For the complex transfer function of the probe-oscilloscope system in the th... Amplitude at the second harmonic frequency To detect the voltage at the first Phase angle at subharmonic frequencies To detect the voltage measurement value at the first Phase angle at subharmonic frequencies For the complex transfer function of the probe-oscilloscope system in the th... Phase angle at the subharmonic frequency.

6. The method for measuring the switching current of a wide bandgap device based on parasitic parameters according to claim 1, characterized in that, In step S7, the switching current... Specifically: in, This represents the DC component of the switching current. For the switching current in the first... Amplitude at the second harmonic frequency For harmonic order, For the fundamental frequency, For time, For the switching current in the first... Phase angle at the subharmonic frequency.

7. A wide-bandgap device switching current measurement system based on parasitic parameters, characterized in that, include: Select a module, choose a section of the power circuit as the detection line, and ensure that the detection line is the only path for the switching current to flow. The waveform module measures the voltage waveform across the detection line determined by the selected module, obtaining the measured waveform. A high-bandwidth passive voltage probe is then used to measure the voltage waveform across the detection line. v sense Measurements were performed using a grounding spring as the grounding method, and the voltage waveform across the test line was measured. v sense Specifically: in, The DC parasitic resistance of the detection line, This represents the DC component of the switching current. For the detection line at the first Parasitic impedance at subharmonic frequencies For the switching current in the first... Amplitude at the second harmonic frequency For harmonic order, The fundamental angular frequency, For time, For the switching current in Phase angle at subharmonic frequencies For the detection line at the first Parasitic impedance angle at subharmonic frequencies; The processing module uses the wavelet signal denoiser toolbox to smooth and denoise the measurement waveforms obtained by the waveform module. The decomposition module performs Fourier decomposition on the measurement waveform after smoothing and denoising by the processing module, and uses the obtained Fourier series as the amplitude and phase of the measurement waveform at different frequency components. The compensation module, based on the transmission characteristics of the passive voltage probe, compensates for the amplitude and phase at different frequencies obtained by the decomposition module, thus obtaining the amplitude and phase of the voltage waveform at both ends of the detection line at different frequencies. It then models the passive voltage probe and, based on the established probe model, obtains its transmission characteristics, which are used as the measured voltage value of the detection line. v sense 'and actual value v sense The relationship between amplitude and phase at different frequencies is important for measuring waveforms. v sense The amplitude and phase at different frequencies are compensated to obtain the actual voltage waveform. v sense ; The calculation module uses finite element simulation to determine the frequency-related parasitic parameters of the detection line. Based on the relationship between the frequency-related parasitic parameters and the amplitude and phase of the voltage and switching current at different frequencies at the two ends of the detection line, the amplitude and phase of the switching current at different frequencies are obtained by using the amplitude and phase of the voltage waveform at the two ends of the detection line at different frequencies obtained by the compensation module. The measurement module uses the amplitude and phase of the switching current at different frequencies obtained from the calculation module to synthesize the Fourier series of the switching current, thereby obtaining the waveform of the switching current and completing the switching current measurement.

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