A method for testing electrical characteristics of RC-IGBT

Abstract

The present invention discloses an electrical characteristic test method of an RC-IGBT, belonging to the technical field of IGBT test. The present invention applies low, medium and high frequency signals to the RC-IGBT, collects collector current signals and collector-emitter voltage signals, and calculates the current waveform unsmooth value and the voltage waveform unsmooth value, as well as the current waveform deformation value and the voltage waveform deformation value under each frequency value signal, to obtain the electrical performance value of the RC-IGBT. The present method can improve the accuracy of electrical characteristic detection and effectively solve the problem of low detection accuracy of existing test methods.

Description

Technical Field

[0001] The invention relates to the technical field of IGBT testing, and in particular to an electrical characteristic testing method of an RC-IGBT. Background Art

[0002] In modern power electronic systems, insulated gate bipolar transistors (IGBTs) are a key power electronic device whose performance directly affects the efficiency and reliability of power conversion and control systems. Traditional IGBT performance test methods are often limited to single frequency or static testing, which makes it difficult to fully and accurately evaluate the electrical characteristics of the device under complex working conditions. Existing technologies mainly rely on single frequency point measurements or simple static parameter tests, which cannot effectively reflect the dynamic electrical characteristics of IGBTs in practical applications, especially the performance changes under different frequency working conditions. Especially for devices with complex internal structures and special working mechanisms such as insulated gate bipolar transistors with reverse conduction capabilities (RC-IGBTs), traditional test methods have been unable to accurately capture subtle changes in their electrical characteristics. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides an electrical characteristic testing method of RC-IGBT, which solves the problem of low electrical characteristic detection accuracy in the prior testing method.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: a method for testing the electrical characteristics of an RC-IGBT, comprising the following steps:

[0005] S1. Apply three signals of different frequency values ​​to the RC-IGBT to collect collector current signals and collector-emitter voltage signals, wherein the different frequency values ​​include: low frequency value, medium frequency value and high frequency value;

[0006] S2. Under each frequency value of the signal, calculate the current waveform unsmooth value and the voltage waveform unsmooth value according to the signal smoothness of the collector current signal and the collector-emitter voltage signal respectively;

[0007] S3. Under the signal of each frequency value, calculate the signal deformation value of the collector current signal and the collector-emitter voltage signal to obtain the current waveform deformation value and the voltage waveform deformation value;

[0008] S4. Calculate the electrical performance value of the RC-IGBT according to the current waveform unsmoothness value, voltage waveform unsmoothness value, current waveform deformation value and voltage waveform deformation value corresponding to each frequency value.

[0009] Furthermore, the expression of the signal in S1 is: , where V g,i(t) is the signal of the ith frequency value, V dc is the DC bias voltage, which is greater than the threshold voltage of the RC-IGBT, A is the amplitude of the sinusoidal signal, f i is the i-th frequency value, i is the number of the frequency value, t is the time, and sin is the sine signal.

[0010] Further, S2 includes the following sub-steps:

[0011] S21, under each frequency value signal, calculating the signal smoothness of each signal segment in the collector current signal to obtain the collector current smoothness;

[0012] S22, selecting a collector current smoothness greater than a smoothness threshold, and calculating an unsmoothed value of the current waveform;

[0013] S23, calculating the signal smoothness of each signal segment in the collector-emitter voltage signal to obtain the collector-emitter voltage smoothness;

[0014] S24, selecting a collector-emitter voltage smoothness greater than a smoothness threshold, and calculating an unsmoothed value of the voltage waveform.

[0015] Furthermore, the formula for calculating signal smoothness in S21 and S23 is: , where s j is the signal smoothness of the j-th segment signal, x j,n is the signal value at the nth moment in the jth segment signal, x j,n+1 is the signal value at the n+1th moment in the jth signal segment, t is the time, d is the differential sign, j is the number of each signal segment, n is the number of the moment, and N is the length of a signal segment.

[0016] Furthermore, the formula for calculating the unsmooth value of the current waveform in S22 is: , where IN Ic is the unsmoothed value of the current waveform, s Ic,m is the smoothness of the mth collector current greater than the smoothness threshold, s th is the smoothness threshold, e is a natural constant, M Ic is the number of collector current smoothnesses greater than the smoothness threshold, and m is a positive integer;

[0017] The formula for calculating the unsmoothed value of the voltage waveform in S24 is: , where IN Vce is the unsmoothed value of the voltage waveform, s Vce,m is the mth collector-emitter voltage smoothness greater than the smoothness threshold, M Vce is the number of collector-emitter voltage smoothnesses greater than the smoothness threshold.

[0018] Furthermore, S3 includes the following sub-steps:

[0019] S31. Under each frequency value signal, Fourier transform the collector current signal and the collector-emitter voltage signal respectively to obtain collector current spectrum information and collector-emitter voltage spectrum information;

[0020] S32, marking the frequency value corresponding to the maximum amplitude in the collector current spectrum information and the collector-emitter voltage spectrum information as the main frequency, and marking the frequency values ​​corresponding to other amplitudes as the secondary frequencies;

[0021] S33, in the collector current spectrum information, according to the amplitude corresponding to the main frequency and the amplitude corresponding to the sub-frequency, calculate the signal deformation value to obtain the current waveform deformation value;

[0022] S34. In the collector-emitter voltage spectrum information, a signal deformation value is calculated according to the amplitude corresponding to the main frequency and the amplitude corresponding to the sub-frequency to obtain a voltage waveform deformation value.

[0023] Furthermore, the formula for calculating the signal deformation value in S33 and S34 is: , where θ is the signal deformation value, B h is the amplitude corresponding to the hth sub-frequency, H is the number of sub-frequencies, A is the amplitude corresponding to the main frequency, and h is the number of the sub-frequency.

[0024] Further, S4 includes the following sub-steps:

[0025] S41, using the current waveform unsmooth value, voltage waveform unsmooth value, current waveform deformation value and voltage waveform deformation value corresponding to each frequency value as elements in sequence to form a row vector;

[0026] S42, each row vector is formed into a matrix to obtain an electrical performance matrix, wherein the first column of the electrical performance matrix contains 3 elements, specifically, the current waveform unsmooth values ​​corresponding to 3 different frequency values; the second column of the electrical performance matrix contains 3 elements, specifically, the voltage waveform unsmooth values ​​corresponding to 3 different frequency values; the third column of the electrical performance matrix contains 3 elements, specifically, the current waveform deformation values ​​corresponding to 3 different frequency values; the fourth column of the electrical performance matrix contains 3 elements, specifically, the voltage waveform deformation values ​​corresponding to 3 different frequency values;

[0027] S43, using a fully connected layer to calculate the electrical performance characteristic value for each column of the electrical performance matrix;

[0028] S44, calculating the instability coefficient for each column of the electrical performance matrix;

[0029] S45. Calculate the electrical performance value of the RC-IGBT according to the electrical performance characteristic value of each column and based on the compensation of the instability coefficient.

[0030] Furthermore, the formula for calculating the instability coefficient in S44 is: , where μ k is the instability coefficient of the kth column, r k,max is the maximum value in the kth column, r k,min is the minimum value in the kth column, where k is the column number.

[0031] Furthermore, the formula for calculating the electrical performance value of the RC-IGBT in S45 is: , where Y is the electrical performance value of RC-IGBT, g k is the electrical performance characteristic value of the kth column.

[0032] The beneficial effects of the present invention are:

[0033] 1. The present invention realizes the comprehensive electrical characteristic evaluation of RC-IGBT at different operating frequencies by testing three frequency points: low, medium and high, breaking through the limitation of traditional single frequency testing.

[0034] 2. The present invention introduces the current waveform unsmoothness value and the voltage waveform unsmoothness value, which can accurately quantify the signal quality of the device at different frequencies, and then by calculating the signal deformation value, it can more carefully capture the subtle changes in the electrical characteristics of the RC-IGBT. The present invention calculates the electrical performance value of the RC-IGBT by comprehensively considering the current waveform unsmoothness value, voltage waveform unsmoothness value, current waveform deformation value and voltage waveform deformation value corresponding to each frequency value, thereby improving the accuracy of detecting electrical characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a flow chart of a method for testing the electrical characteristics of an RC-IGBT. DETAILED DESCRIPTION

[0036] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0037] like Figure 1 As shown, a method for testing the electrical characteristics of an RC-IGBT comprises the following steps:

[0038] S1. Apply three signals of different frequency values ​​to the RC-IGBT to collect collector current signals and collector-emitter voltage signals, wherein the different frequency values ​​include: low frequency value, medium frequency value and high frequency value;

[0039] S2. Under each frequency value of the signal, calculate the current waveform unsmooth value and the voltage waveform unsmooth value according to the signal smoothness of the collector current signal and the collector-emitter voltage signal respectively;

[0040] S3. Under the signal of each frequency value, calculate the signal deformation value of the collector current signal and the collector-emitter voltage signal to obtain the current waveform deformation value and the voltage waveform deformation value;

[0041] S4. Calculate the electrical performance value of the RC-IGBT according to the current waveform unsmoothness value, voltage waveform unsmoothness value, current waveform deformation value and voltage waveform deformation value corresponding to each frequency value.

[0042] In this embodiment, the expression of the signal in S1 is: , where V g,i (t) is the signal of the ith frequency value, V dc is the DC bias voltage, which is greater than the threshold voltage of the RC-IGBT, A is the amplitude of the sinusoidal signal, f i is the i-th frequency value, i is the number of the frequency value, t is the time, and sin is the sine signal.

[0043] In this embodiment, the parameters of the signal of the first frequency value are: V dc =5V, A=5V, f1=10Hz; the parameters of the signal of the second frequency value are: V dc =5V, A=5V, f2=1000Hz; the parameters of the signal with the third frequency value are: V dc =5V, A=5V, f3=20000Hz.

[0044] The present invention selects three frequency value signals of low frequency, medium frequency and high frequency to test the RC-IGBT respectively, and comprehensively evaluates the electrical characteristics of the RC-IGBT under different working conditions.

[0045] In this embodiment, S2 includes the following sub-steps:

[0046] S21, under each frequency value signal, calculating the signal smoothness of each signal segment in the collector current signal to obtain the collector current smoothness;

[0047] S22, selecting a collector current smoothness greater than a smoothness threshold, and calculating an unsmoothed value of the current waveform;

[0048] S23, calculating the signal smoothness of each signal segment in the collector-emitter voltage signal to obtain the collector-emitter voltage smoothness;

[0049] S24, selecting a collector-emitter voltage smoothness greater than a smoothness threshold, and calculating an unsmoothed value of the voltage waveform.

[0050] The present invention calculates the signal smoothness of the collector current signal and the collector-emitter voltage signal in sections to evaluate the smoothness of each section of the signal, and selects the smoothness greater than the smoothness threshold to quantify the abnormality of the current and voltage waveforms.

[0051] In this embodiment, the smoothness threshold is set to 0.1. When the smoothness is less than 0.1, it is considered to be good waveform smoothness. In practical applications, the smaller the smoothness value, the smoother the waveform. For high-performance applications, the smoothness can be controlled in a smaller range, such as less than 0.05.

[0052] In this embodiment, the formula for calculating the signal smoothness in S21 and S23 is: , where s j is the signal smoothness of the j-th segment signal, x j,n is the signal value at the nth moment in the jth segment signal, x j,n+1 is the signal value at the n+1th moment in the jth signal segment, t is the time, d is the differential sign, j is the number of each signal segment, n is the number of the moment, and N is the length of a signal segment.

[0053] The present invention can quantify the smoothness of a signal by calculating the smoothness of the signal, help identify noise and irregularities in the signal, and thus improve the evaluation of signal quality.

[0054] In this embodiment, the value range of N is 5, 6, 7, etc.

[0055] Under normal circumstances, when a sinusoidal signal is applied to the RC-IGBT gate (provided that the minimum value of the signal has met the threshold voltage), the changes in the collector current signal and the collector-emitter voltage signal are continuous, without mutations or sharp fluctuations. A smooth waveform usually means that the frequency response of the signal is good and can effectively transmit information without introducing additional noise or distortion. In RC-IGBT applications, a smooth waveform helps ensure that the device can operate stably during the turn-on and turn-off process, reducing switching losses and heat generation.

[0056] In this embodiment, the formula for calculating the unsmooth value of the current waveform in S22 is: , where IN Ic is the unsmoothed value of the current waveform, s Ic,m is the smoothness of the mth collector current greater than the smoothness threshold, s this the smoothness threshold, e is a natural constant, M Ic is the number of collector current smoothnesses greater than the smoothness threshold, and m is a positive integer;

[0057] In this embodiment, the formula for calculating the voltage waveform unsmoothness value in S24 is: , where IN Vce is the unsmoothed value of the voltage waveform, s Vce,m is the mth collector-emitter voltage smoothness greater than the smoothness threshold, M Vce is the number of collector-emitter voltage smoothnesses greater than the smoothness threshold.

[0058] The present invention calculates the unsmoothness value according to the degree of deviation of the collector current smoothness and the collector-emitter voltage smoothness from the smoothness threshold, thereby reflecting the sudden change of the waveform.

[0059] In this embodiment, S3 includes the following sub-steps:

[0060] S31. Under each frequency value signal, Fourier transform the collector current signal and the collector-emitter voltage signal respectively to obtain collector current spectrum information and collector-emitter voltage spectrum information;

[0061] S32, marking the frequency value corresponding to the maximum amplitude in the collector current spectrum information and the collector-emitter voltage spectrum information as the main frequency, and marking the frequency values ​​corresponding to other amplitudes as the secondary frequencies;

[0062] S33, in the collector current spectrum information, according to the amplitude corresponding to the main frequency and the amplitude corresponding to the sub-frequency, calculate the signal deformation value to obtain the current waveform deformation value;

[0063] S34. In the collector-emitter voltage spectrum information, a signal deformation value is calculated according to the amplitude corresponding to the main frequency and the amplitude corresponding to the sub-frequency to obtain a voltage waveform deformation value.

[0064] In the present invention, only a single frequency is applied in each test, so other frequencies in the collector current signal and the collector-emitter voltage signal are caused by RC-IGBT distortion.

[0065] In this embodiment, the formula for calculating the signal deformation value in S33 and S34 is: , where θ is the signal deformation value, B h is the amplitude corresponding to the hth sub-frequency, H is the number of sub-frequencies, A is the amplitude corresponding to the main frequency, and h is the number of the sub-frequency.

[0066] The present invention uses the ratio of the corresponding amplitude of each secondary frequency to the amplitude corresponding to the main frequency to evaluate the deformation. When the signal deformation value is larger, the signal deformation is more serious.

[0067] In this embodiment, S4 includes the following sub-steps:

[0068] S41, using the current waveform unsmooth value, voltage waveform unsmooth value, current waveform deformation value and voltage waveform deformation value corresponding to each frequency value as elements in sequence to form a row vector;

[0069] S42, each row vector is formed into a matrix to obtain an electrical performance matrix, wherein the first column of the electrical performance matrix contains 3 elements, specifically, the current waveform unsmooth values ​​corresponding to 3 different frequency values; the second column of the electrical performance matrix contains 3 elements, specifically, the voltage waveform unsmooth values ​​corresponding to 3 different frequency values; the third column of the electrical performance matrix contains 3 elements, specifically, the current waveform deformation values ​​corresponding to 3 different frequency values; the fourth column of the electrical performance matrix contains 3 elements, specifically, the voltage waveform deformation values ​​corresponding to 3 different frequency values;

[0070] S43, using a fully connected layer to calculate the electrical performance characteristic value for each column of the electrical performance matrix;

[0071] S44, calculating the instability coefficient for each column of the electrical performance matrix;

[0072] S45. Calculate the electrical performance value of the RC-IGBT according to the electrical performance characteristic value of each column and based on the compensation of the instability coefficient.

[0073] The expression of the fully connected layer is: , where y is the electrical performance characteristic value, X k,i is the i-th element in the k-th column of the electrical performance matrix, W k,i For X k,i The weight of b k,i For X k,i The value of i ranges from 1 to 3.

[0074] In this embodiment, the weights and biases in the fully connected layer can be calibrated using an existing gradient descent method or a genetic method.

[0075] In this embodiment, the formula for calculating the instability coefficient in S44 is: , where μ k is the instability coefficient of the kth column, r k,max is the maximum value in the kth column, r k,min is the minimum value in the kth column, where k is the column number.

[0076] In the same column of the electrical performance matrix, there are the same type of signal characteristics at different frequency values. The instability coefficient is calculated based on the difference between the maximum value and the minimum value. When the instability coefficient is larger, the difference between the RC-IGBT at different frequency values ​​is larger, and the performance is more unstable.

[0077] In this embodiment, the formula for calculating the electrical performance value of the RC-IGBT in S45 is: , where Y is the electrical performance value of RC-IGBT, g k is the electrical performance characteristic value of the kth column.

[0078] In the present invention, the greater the electrical performance value of the RC-IGBT is, the worse the electrical performance of the RC-IGBT is.

[0079] The present invention realizes a comprehensive electrical characteristic evaluation of RC-IGBT at different operating frequencies by testing three frequency points: low, medium and high, thus breaking through the limitations of traditional single frequency testing. The present invention introduces the current waveform unsmoothness value and the voltage waveform unsmoothness value, which can accurately quantify the signal quality of the device at different frequencies, and then by calculating the signal deformation value, it can more carefully capture the subtle changes in the electrical characteristics of the RC-IGBT. The present invention calculates the electrical performance value of the RC-IGBT by comprehensively calculating the corresponding current waveform unsmoothness value, voltage waveform unsmoothness value, current waveform deformation value and voltage waveform deformation value at each frequency value, thereby improving the accuracy of detecting electrical characteristics.

[0080] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for testing the electrical characteristics of an RC-IGBT, characterized in that: The following steps are involved: S1. Apply three signals of different frequency values ​​to the RC-IGBT to collect collector current signals and collector-emitter voltage signals, wherein the different frequency values ​​include: low frequency value, medium frequency value and high frequency value; S2. Under each frequency value of the signal, calculate the current waveform unsmooth value and the voltage waveform unsmooth value according to the signal smoothness of the collector current signal and the collector-emitter voltage signal respectively; S3. Under the signal of each frequency value, calculate the signal deformation value of the collector current signal and the collector-emitter voltage signal to obtain the current waveform deformation value and the voltage waveform deformation value; S4. Calculate the electrical performance value of the RC-IGBT according to the current waveform unsmoothness value, voltage waveform unsmoothness value, current waveform deformation value and voltage waveform deformation value corresponding to each frequency value; The S2 comprises the following sub-steps: S21, under each frequency value signal, calculating the signal smoothness of each signal segment in the collector current signal to obtain the collector current smoothness; S22, selecting a collector current smoothness greater than a smoothness threshold, and calculating an unsmoothed value of the current waveform; S23, calculating the signal smoothness of each signal segment in the collector-emitter voltage signal to obtain the collector-emitter voltage smoothness; S24, selecting a collector-emitter voltage smoothness greater than a smoothness threshold, and calculating an unsmoothed value of a voltage waveform; The formula for calculating the signal smoothness in S21 and S23 is: , where s j is the signal smoothness of the j-th segment signal, x j,n is the signal value at the nth moment in the jth segment signal, x j,n+1 is the signal value at the n+1th moment in the jth segment of the signal, t is the time, d is the differential sign, j is the number of each segment of the signal, n is the number of the moment, and N is the length of a segment of the signal; The S3 comprises the following sub-steps: S31. Under each frequency value signal, Fourier transform the collector current signal and the collector-emitter voltage signal respectively to obtain collector current spectrum information and collector-emitter voltage spectrum information; S32, marking the frequency value corresponding to the maximum amplitude in the collector current spectrum information and the collector-emitter voltage spectrum information as the main frequency, and marking the frequency values ​​corresponding to other amplitudes as the secondary frequencies; S33, in the collector current spectrum information, according to the amplitude corresponding to the main frequency and the amplitude corresponding to the sub-frequency, calculate the signal deformation value to obtain the current waveform deformation value; S34, in the collector-emitter voltage spectrum information, according to the amplitude corresponding to the main frequency and the amplitude corresponding to the sub-frequency, calculating the signal deformation value to obtain the voltage waveform deformation value; The formula for calculating the signal deformation value in S33 and S34 is: , where θ is the signal deformation value, B h is the amplitude corresponding to the hth sub-frequency, H is the number of sub-frequencies, A is the amplitude corresponding to the main frequency, and h is the number of the sub-frequency.

2. The electrical characteristics testing method of RC-IGBT according to claim 1, characterized in that: The expression of the signal in S1 is: , where V g,i (t) is the signal of the ith frequency value, V dc is the DC bias voltage, which is greater than the threshold voltage of the RC-IGBT, A is the amplitude of the sinusoidal signal, f i is the i-th frequency value, i is the number of the frequency value, t is the time, and sin is the sine signal.

3. The electrical characteristics testing method of RC-IGBT according to claim 1, characterized in that: The formula for calculating the unsmooth value of the current waveform in S22 is: , where IN Ic is the unsmoothed value of the current waveform, s Ic,m is the smoothness of the mth collector current greater than the smoothness threshold, s th is the smoothness threshold, e is a natural constant, M Ic is the number of collector current smoothnesses greater than the smoothness threshold, and m is a positive integer; The formula for calculating the voltage waveform unsmoothness value in S24 is: , where IN Vce is the unsmoothed value of the voltage waveform, s Vce,m is the mth collector-emitter voltage smoothness greater than the smoothness threshold, M Vce is the number of collector-emitter voltage smoothnesses greater than the smoothness threshold.

4. The electrical characteristics testing method of RC-IGBT according to claim 1, characterized in that: The S4 comprises the following sub-steps: S41, using the current waveform unsmooth value, voltage waveform unsmooth value, current waveform deformation value and voltage waveform deformation value corresponding to each frequency value as elements in sequence to form a row vector; S42, each row vector is formed into a matrix to obtain an electrical performance matrix, wherein the first column of the electrical performance matrix contains 3 elements, specifically, the current waveform unsmooth values ​​corresponding to 3 different frequency values; the second column of the electrical performance matrix contains 3 elements, specifically, the voltage waveform unsmooth values ​​corresponding to 3 different frequency values; the third column of the electrical performance matrix contains 3 elements, specifically, the current waveform deformation values ​​corresponding to 3 different frequency values; the fourth column of the electrical performance matrix contains 3 elements, specifically, the voltage waveform deformation values ​​corresponding to 3 different frequency values; S43, using a fully connected layer to calculate the electrical performance characteristic value for each column of the electrical performance matrix; S44, calculating the instability coefficient for each column of the electrical performance matrix; S45. Calculate the electrical performance value of the RC-IGBT according to the electrical performance characteristic value of each column and based on the compensation of the instability coefficient.

5. The electrical characteristics testing method of RC-IGBT according to claim 4, characterized in that: The formula for calculating the instability coefficient in S44 is: , where μ k is the instability coefficient of the kth column, r k,max is the maximum value in the kth column, r k,min is the minimum value in the kth column, where k is the column number.

6. The electrical characteristics testing method of RC-IGBT according to claim 5, characterized in that: The formula for calculating the electrical performance value of the RC-IGBT in S45 is: , where Y is the electrical performance value of RC-IGBT, g k is the electrical performance characteristic value of the kth column.

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