Method, system and equipment for calculating stray inductance of power module

Abstract

The invention provides a stray inductance calculation method, system and equipment for a power module, and the method comprises the steps: measuring the power module connected to a stray inductance test circuit, and obtaining the current change data and first voltage change data of the power module in a specified time range, the stray inductance test circuit comprises an auxiliary switch tube which is connected to the input end of the power module and is configured to be capable of switching the on state or the off state, and the specified time range is a time period before the auxiliary switch tube is switched from the off state to the second-time on state and the current in the power module is reduced to a zero point; and performing filtering processing on the first voltage change data to obtain second voltage change data, and forming a first curve graph based on the current change data and the second voltage change data to solve the problem that the amplitude fluctuation ratio of the measured voltage change data of the power module is relatively large in the existing stray inductance calculation method of the power module. The error of point-taking calculation is large; and the calculation precision of the stray inductance is relatively low.

Description

Technical Field

[0001] The present invention belongs to the technical field of stray inductance calculation, and more specifically, relates to a method, system and device for calculating the stray inductance of a power module. Background Art

[0002] Stray inductance refers to the unwanted inductance generated in the circuit due to electromagnetic induction, which can cause interference and energy loss during signal transmission. Especially in power module design, too high stray inductance will lead to insufficient design margin, affect circuit characteristics, and even cause device damage. Therefore, accurate calculation of the stray inductance of the power module has become a key link in designing a power module with low stray inductance.

[0003] The existing method for calculating the stray inductance of a power module is to use an oscilloscope to measure the power module in a standard stray inductance test circuit to obtain the voltage change data and current change data of the power module, and then perform point calculation on the voltage change data and current change data to obtain the stray inductance L of the power module. p The values ​​are:

[0004] L p =V step / |di DUT / dt|.

[0005] However, since the waveform displayed by the oscilloscope contains noise and the continuity of adjacent points is poor, the amplitude fluctuation rate of the voltage change data of the measured power module is large, resulting in a large numerical error after taking the point calculation and substituting it into the above formula, resulting in low calculation accuracy of stray inductance. Therefore, how to design a stray inductance method of power module that can eliminate noise, reduce data interference and has high precision has become a question worth considering for technicians in this field. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the existing method for calculating the stray inductance of a power module has a large error in point calculation and a low calculation accuracy of the stray inductance due to the large amplitude fluctuation rate of the voltage change data of the measured power module.

[0007] In order to achieve the above object, the present invention provides a method, system and device for calculating stray inductance of a power module.

[0008] According to a first aspect of the present invention, a method for calculating stray inductance of a power module is provided, comprising:

[0009] The power module connected to the stray inductance test circuit is measured to obtain current change data and first voltage change data of the power module within a specified time range, wherein the stray inductance test circuit includes an auxiliary switch tube connected to the input end of the power module and configured to be able to switch between an on and off state, and the specified time range is a time period from when the auxiliary switch tube switches from the off state to the second on state and before the current in the power module decreases to zero;

[0010] Performing filtering processing on the first voltage change data to obtain second voltage change data, and forming a first curve graph based on the current change data and the second voltage change data;

[0011] According to the first curve, the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the second voltage change data tends to be stable are selected to obtain the stray inductance L p The values ​​are:

[0012] L p =V step / |di DUT / dt|

[0013] Where:

[0014] V step is the average value of the maximum voltage value and the minimum voltage value;

[0015] |di DUT / dt| is the absolute value of the change rate of the current change data within the time range.

[0016] Optionally, measuring the power module connected to the stray inductance test circuit to obtain current change data and first voltage change data of the power module within a specified time range includes:

[0017] Using an oscilloscope, measure the voltage and current in the power module within 15 to 40 ns before the auxiliary switch tube switches from the off state to the second on state and the current in the power module decreases to zero;

[0018] The measured data is exported to Excel to obtain the current change data and the first voltage change data in the power module.

[0019] Optionally, the oscilloscope includes a current probe and a voltage probe, each having a positive interface and a negative interface, the positive interface and the negative interface of the current probe are both connected to the input end of the power module, and the positive interface and the negative interface of the voltage probe are respectively connected to the input end and the output end of the power module.

[0020] Optionally, filtering the first voltage change data to obtain second voltage change data, and forming a first curve graph based on the current change data and the second voltage change data, includes:

[0021] Inputting the first voltage change data into VBA embedded in Excel;

[0022] The first voltage change data is filtered using a low-pass filter function to obtain the second voltage change data and form the first curve graph.

[0023] Optionally, the stray inductance test circuit further includes a capacitor module and an inductor, the output end of the capacitor module is connected to the input end of the auxiliary switch tube, and the inductor is connected in parallel with the power module.

[0024] Optionally, the stray inductance test circuit further includes a signal generator for enabling the auxiliary switch tube to switch between an on and an off state.

[0025] Optionally, the power module is an IGBT module or a MOSFET module.

[0026] According to a second aspect of the present invention, a stray inductance calculation system for a power module includes:

[0027] A data acquisition module measures the power module connected to a stray inductance test circuit to acquire current change data and first voltage change data of the power module within a specified time range, wherein the stray inductance test circuit includes an auxiliary switch tube connected to an input end of the power module and configured to be able to switch between an on and off state, and the specified time range is a time period from when the auxiliary switch tube switches from an off state to a second on state and before the current in the power module decreases to zero;

[0028] a data processing module, filtering the first voltage change data to obtain second voltage change data, and forming a first curve graph based on the current change data and the second voltage change data;

[0029] The stray inductance calculation module selects the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the second voltage change data tends to be stable according to the first curve graph, and obtains the stray inductance L p The values ​​are:

[0030] L p =V step / |di DUT / dt|

[0031] Where:

[0032] V step is the average value of the maximum voltage value and the minimum voltage value;

[0033] |di DUT / dt| is the absolute value of the change rate of the current change data within the time range.

[0034] According to a third aspect of the present invention, there is provided a stray inductance calculation device for a power module, comprising a processor and a memory, wherein the processor implements any of the above-mentioned stray inductance calculation methods for a power module when executing a computer program stored in the memory.

[0035] The beneficial effects of the present invention are:

[0036] The stray inductance calculation method of the power module proposed in the present invention obtains the current change data and the first voltage change data of the power module within a specified time range, and then filters the first voltage change data to obtain the second voltage change data and forms a first curve graph; then, according to the first curve graph, the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the second voltage change data tends to be stable are selected to calculate the stray inductance L p Compared with the existing stray inductance calculation method of the power module, the stray inductance calculation method of the present invention can eliminate noise, reduce data interference, and realize high-precision calculation of the stray inductance of the power module by filtering the first voltage change data.

[0037] The stray inductance calculation system and the stray inductance calculation device of the power module of the present invention belong to a general inventive concept with the stray inductance calculation method of the power module mentioned above, and have at least the same beneficial effects as the stray inductance calculation method of the power module mentioned above, and the beneficial effects are not repeated here.

[0038] Based on the above content, it can be seen that the technical solution of the present invention can effectively solve the problem that the existing method for calculating the stray inductance of the power module has a large amplitude fluctuation rate of the measured voltage change data of the power module, resulting in large errors in point calculation and low calculation accuracy of the stray inductance.

[0039] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which the same or similar reference numerals are used throughout the drawings to represent the same or similar components.

[0041] Figure 1A schematic diagram of a process flow of a method for calculating stray inductance of a power module according to an embodiment of the present invention is shown;

[0042] Figure 2 A stray inductance test circuit diagram according to an embodiment of the present invention is shown;

[0043] Figure 3 A first graph showing embodiment 1 of the present invention;

[0044] Figure 4 A first scatter plot of Example 1 of the present invention is shown;

[0045] Figure 5 A second graph showing Comparative Example 1 of the present invention;

[0046] Figure 6 A second scatter plot of Comparative Example 1 of the present invention is shown;

[0047] Figure 7 A principle block diagram of a stray inductance calculation system for a power module according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to more fully understand the technical solution of the present invention, the exemplary embodiments of the present invention will be described in more comprehensive and detailed in conjunction with the accompanying drawings below. Obviously, the one or more embodiments of the present invention described below are only one or more of the specific ways in which the technical solution of the present invention can be implemented, and are not exhaustive. It should be understood that other ways belonging to a general inventive concept can be used to implement the technical solution of the present invention, and should not be limited by the exemplary embodiments described. Based on one or more embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work should fall within the scope of protection of the present invention.

[0049] Example: Figure 1 A schematic diagram of a process flow of a method for calculating stray inductance of a power module according to an embodiment of the present invention is shown; Figure 2 A stray inductance test circuit diagram according to an embodiment of the present invention is shown.

[0050] Reference Figure 1-2 , an embodiment of the present invention provides a method for calculating stray inductance of a power module, comprising:

[0051] Step S110: measuring the power module connected to the stray inductance test circuit to obtain current change data and first voltage change data of the power module within a specified time range, wherein the stray inductance test circuit includes an auxiliary switch tube connected to the input end of the power module and configured to be able to switch between an on and off state, and the specified time range is a time period from when the auxiliary switch tube switches from the off state to the second on state and before the current in the power module decreases to zero;

[0052] Step S120: filtering the first voltage change data to obtain second voltage change data, and forming a first curve graph based on the current change data and the second voltage change data;

[0053] Step S130: According to the first curve, select the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the second voltage change data tends to be stable, and obtain the stray inductance L p The values ​​are:

[0054] L p =V step / |di DUT / dt|

[0055] Where:

[0056] V step is the average value of the maximum voltage and the minimum voltage;

[0057] |di DUT / dt| is the absolute value of the rate of change of the current change data within the time range.

[0058] In a specific embodiment, the stray inductance test circuit further includes a capacitor module and an inductor, the output end of the capacitor module is connected to the input end of the auxiliary switch tube, and the inductor is connected in parallel with the power module.

[0059] In a specific embodiment, the stray inductance test circuit further includes a signal generator for enabling the auxiliary switch tube to switch between an on and off state.

[0060] Specifically, Figure 2 As shown, G represents a DC power supply, C represents a capacitor module, T1 and T2 represent power modules, T3 represents an auxiliary switch tube, and L L represents the inductor, C1 and E2 represent the connection positions of the positive and negative terminals of the voltage probe, and i DUT Indicates the connection position of the positive and negative terminals of the current probe. Figure 2 It can be seen that when the signal generator outputs a double-pulse control signal to the auxiliary switch tube, the switch state of the auxiliary switch tube is first switched from the first on state to the off state, and then switched from the off state to the second on state.

[0061] When the auxiliary switch tube is in the first on state, the capacitor module, the auxiliary switch tube and the inductor form a loop, and the power module is short-circuited.

[0062] When the auxiliary switch tube is switched to the off state, current is output from the output end of the inductor to the input end of the power module, and the inductor and the power module form a loop.

[0063] When the auxiliary switch tube switches to the second conduction state, the current in the power module gradually decreases to zero and then increases in the opposite direction. While the current is gradually decreasing to zero, the voltage in the power module is in a stable state and the inductor is equivalent to an open circuit state. The current change data and voltage change data of the power module during switching can be used to calculate the stray inductance.

[0064] In a specific embodiment, the power module is an IGBT module or a MOSFET module.

[0065] In one embodiment, in step S110, a power module connected to a stray inductance test circuit is measured to obtain current change data and first voltage change data of the power module within a specified time range, including:

[0066] Step S111: using an oscilloscope to measure the voltage and current in the power module within 15 to 40 ns before the auxiliary switch tube switches from the off state to the second on state and the current in the power module decreases to zero;

[0067] Step S112: exporting the measured data to Excel to obtain current change data and first voltage change data in the power module.

[0068] In a specific embodiment, the oscilloscope includes a current probe and a voltage probe, each having a positive interface and a negative interface. The positive interface and the negative interface of the current probe are both connected to the input end of the power module, and the positive interface and the negative interface of the voltage probe are respectively connected to the input end and the output end of the power module.

[0069] In one embodiment, in step S120, filtering is performed on the first voltage change data to obtain second voltage change data, and a first curve graph is formed based on the current change data and the second voltage change data, including:

[0070] Step S121: inputting the first voltage change data into the VBA embedded in Excel;

[0071] Step S122: using a low-pass filter function to filter the first voltage change data to obtain second voltage change data and form a first curve graph.

[0072] In one embodiment, in step S122, filtering the first voltage change data using a low-pass filter function to obtain second voltage change data includes:

[0073] Convert the first voltage variation data into an array Variant_arr_raw_ids();

[0074] Convert each element in the array Variant_arr_raw_ids() to Double data type and output it to the InputData() array;

[0075] Call the LowPassFilter2() filter function to filter the InputData() array and output it to the OutputData() data;

[0076] Call the WaveSmooth() smoothing function to smooth the OutputData() data and output it to the WaveSmooth_OutputData() array;

[0077] Output the WaveSmooth_OutputData() array to Excel to obtain the second voltage data.

[0078] In one embodiment, in step S122, after filtering the first voltage change data using a low-pass filter function to obtain the second voltage change data and forming a first curve graph, the following steps are included:

[0079] The first curve graph is converted into a first scatter graph in Excel.

[0080] Please refer to Figure 3-6 The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0081] Embodiment 1:

[0082] Embodiment 1 of the present invention provides a method for calculating stray inductance of a power module, comprising: a first curve graph and a first scatter plot obtained by using the method for calculating stray inductance of a power module in any of the above embodiments.

[0083] Figure 3 A first graph showing Example 1 of the present invention is shown.

[0084] Figure 4 A first scatter plot of Example 1 of the present invention is shown.

[0085] like Figure 3 and 4As shown in the figure, the ordinate is the current value or voltage value, and the abscissa is the measurement time. Figure 4 It can be obtained by taking the middle point that the maximum voltage value of the second voltage change data is 13.73V, and the minimum voltage value is 12.07V. Then, the amplitude fluctuation rate of the voltage change data of the power module obtained by the stray inductance calculation method of the power module of the present invention is:

[0086] σ=[(maximum voltage value-minimum voltage value) / average value]*100%=12.87%,

[0087] and in Figure 4 Get the |di in the same time range DUT |=46.72A,|dt|=32ns,then the stray inductance L p The value is: 8.86nH.

[0088] Comparative Example 1:

[0089] Comparative Example 1 of the present invention provides a method for calculating stray inductance of a power module, comprising:

[0090] Step S210: measuring a power module connected to a stray inductance test circuit to obtain current change data and first voltage change data of the power module within a specified time range, wherein the stray inductance test circuit includes an auxiliary switch tube connected to an input end of the power module and configured to be able to switch between an on and off state, and the specified time range is a time period from when the auxiliary switch tube switches from an off state to a second on state and before the current in the power module decreases to zero;

[0091] Step S220: obtaining a second curve graph based on the current change data and the first voltage change data;

[0092] Step S230: According to the second curve, select the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the first voltage change data tends to be stable, and obtain the stray inductance L p The values ​​are:

[0093] L p =V step / |di DUT / dt|

[0094] Where:

[0095] V step is the average value of the maximum voltage and the minimum voltage;

[0096] |di DUT / dt| is the absolute value of the rate of change of the current change data within the time range.

[0097] In one embodiment, in step S210, a power module connected to a stray inductance test circuit is measured to obtain current change data and first voltage change data of the power module within a specified time range, including:

[0098] Step S211: using an oscilloscope to measure the voltage and current in the power module within 15 to 40 ns before the auxiliary switch tube switches from the off state to the second on state and the current in the power module decreases to zero;

[0099] Step S212: exporting the measured data to Excel to obtain current change data and first voltage change data in the power module.

[0100] In one embodiment, in step S220, after obtaining the second curve graph based on the current change data and the first voltage change data, the following steps are included:

[0101] Convert the second curve graph into a second scatter graph in Excel.

[0102] Figure 5 A second graph showing Comparative Example 1 of the present invention is shown.

[0103] Figure 6 A second scatter plot of Comparative Example 1 of the present invention is shown.

[0104] like Figure 5 and 6 As shown in the figure, the ordinate is the current value or voltage value, and the abscissa is the measurement time. Figure 6 It can be obtained by taking the middle point that the maximum voltage value of the first voltage change data is 16.58V, and the minimum voltage value is 8.53V. Then, the amplitude fluctuation rate of the voltage change data of the power module obtained by the stray inductance calculation method of the power module of Comparative Example 1 of the present invention is:

[0105] σ=[(maximum voltage value-minimum voltage value) / average value]*100%=62.26%,

[0106] and in Figure 6 Get the |di in the same time range DUT |=45.87A,|dt|=32.06ns,then the stray inductance L p The value is: 9.925nH.

[0107] To sum up, the method for calculating the stray inductance of the power module proposed in the present invention, compared with comparative example 1, reduces the amplitude fluctuation rate of the voltage change data of the power module measured by the second voltage change data obtained by filtering the first voltage change data, thereby eliminating noise, reducing data interference, and achieving high-precision calculation of the stray inductance of the power module.

[0108] Figure 7 A principle block diagram of a stray inductance calculation system for a power module according to an embodiment of the present invention is shown.

[0109] Reference Figure 7 , a stray inductance calculation system for a power module according to an embodiment of the present invention comprises:

[0110] A data acquisition module measures a power module connected to a stray inductance test circuit to obtain current change data and first voltage change data of the power module within a specified time range, wherein the stray inductance test circuit includes an auxiliary switch tube connected to an input end of the power module and configured to be able to switch between an on and off state, and the specified time range is a time period from when the auxiliary switch tube switches from an off state to a second on state and before the current in the power module decreases to zero;

[0111] A data processing module performs filtering processing on the first voltage change data to obtain second voltage change data, and forms a first curve graph based on the current change data and the second voltage change data;

[0112] The stray inductance calculation module selects the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the second voltage change data tends to be stable according to the first curve graph, and obtains the stray inductance L p The values ​​are:

[0113] L p =V step / |di DUT / dt|

[0114] Where:

[0115] V step is the average value of the maximum voltage and the minimum voltage;

[0116] |di DUT / dt| is the absolute value of the rate of change of the current change data within the time range.

[0117] Accordingly, based on the method for calculating the stray inductance of a power module proposed in an embodiment of the present invention, an embodiment of the present invention further proposes a stray inductance calculation device for a power module, including a processor and a memory, and when the processor executes a computer program stored in the memory, the method for calculating the stray inductance of the power module proposed in an embodiment of the present invention is implemented.

[0118] Although one or more embodiments of the present invention are described above, it should be known to those skilled in the art that the present invention can be implemented in any other form without departing from its subject matter and scope. Therefore, the embodiments described above are illustrative rather than restrictive, and many modifications and substitutions are obvious to those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A method for calculating stray inductance of a power module, characterized in that: include: The power module connected to the stray inductance test circuit is measured to obtain current change data and first voltage change data of the power module within a specified time range, wherein the stray inductance test circuit includes an auxiliary switch tube connected to the input end of the power module and configured to be able to switch between an on and off state, and the specified time range is a time period from when the auxiliary switch tube switches from the off state to the second on state and before the current in the power module decreases to zero; Performing filtering processing on the first voltage change data to obtain second voltage change data, and forming a first curve graph based on the current change data and the second voltage change data; According to the first curve, the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the second voltage change data tends to be stable are selected to obtain the stray inductance L p The values ​​are: L p =V step / |the DUT / dt| Where: V step is the average value of the maximum voltage value and the minimum voltage value; |di DUT / dt| is the absolute value of the change rate of the current change data within the time range.

2. The method for calculating stray inductance of a power module according to claim 1, characterized in that: The step of measuring the power module connected to the stray inductance test circuit to obtain current change data and first voltage change data of the power module within a specified time range includes: Using an oscilloscope, measure the voltage and current in the power module within 15 to 40 ns before the auxiliary switch tube switches from the off state to the second on state and the current in the power module decreases to zero; The measured data is exported to Excel to obtain the current change data and the first voltage change data in the power module.

3. The method for calculating stray inductance of a power module according to claim 2, characterized in that: The oscilloscope includes a current probe and a voltage probe, each having a positive interface and a negative interface. The positive interface and the negative interface of the current probe are both connected to the input end of the power module, and the positive interface and the negative interface of the voltage probe are respectively connected to the input end and the output end of the power module.

4. The method for calculating stray inductance of a power module according to claim 3, characterized in that: The filtering process is performed on the first voltage change data to obtain second voltage change data, and a first curve graph is formed based on the current change data and the second voltage change data, including: Inputting the first voltage change data into VBA embedded in Excel; The first voltage change data is filtered using a low-pass filter function to obtain the second voltage change data and form the first curve graph.

5. The method for calculating stray inductance of a power module according to claim 4, characterized in that: The stray inductance test circuit also includes a capacitor module and an inductor. The output end of the capacitor module is connected to the input end of the auxiliary switch tube, and the inductor is connected in parallel with the power module.

6. The method for calculating stray inductance of a power module according to claim 5, characterized in that: The stray inductance test circuit also includes a signal generator for enabling the auxiliary switch tube to switch between an on and off state.

7. The method for calculating stray inductance of a power module according to claim 6, characterized in that: The power module is an IGBT module or a MOSFET module.

8. A stray inductance calculation system for a power module, characterized in that: include: A data acquisition module measures the power module connected to a stray inductance test circuit to acquire current change data and first voltage change data of the power module within a specified time range, wherein the stray inductance test circuit includes an auxiliary switch tube connected to an input end of the power module and configured to be able to switch between an on and off state, and the specified time range is a time period from when the auxiliary switch tube switches from an off state to a second on state and before the current in the power module decreases to zero; a data processing module, filtering the first voltage change data to obtain second voltage change data, and forming a first curve graph based on the current change data and the second voltage change data; The stray inductance calculation module selects the maximum voltage value and the minimum voltage value within the time range when the fluctuation of the second voltage change data tends to be stable according to the first curve graph, and obtains the stray inductance L p The values ​​are: L p =V step / |the pUT / dt| Where: V step is the average value of the maximum voltage value and the minimum voltage value; |di DUT / dt| is the absolute value of the change rate of the current change data within the time range.

9. A stray inductance calculation device for a power module, characterized in that: The invention comprises a processor and a memory, wherein when the processor executes a computer program stored in the memory, the method for calculating the stray inductance of the power module according to any one of claims 1 to 7 is implemented.

Images