A frequency domain evaluation method for IGBT device switching transient simulation model based on FFT

Abstract

The application belongs to the technical field of semiconductor, and particularly relates to a frequency domain evaluation method for an IGBT device switching transient simulation model based on FFT. The method solves the problem that the current evaluation of the switching transient simulation model lacks quantitative indexes, including: S1: taking the complete first turn-on and turn-off process duration of the device as a fundamental wave cycle, and calculating the corresponding fundamental wave frequency; S2: using the fundamental wave frequency to respectively perform Fourier transform analysis on the voltage and current waveforms in the duration, and obtaining total harmonic content THD 仿真 ; S3: comparing the obtained total harmonic content THD 仿真 with the total harmonic content THD 实测 obtained by analyzing the actual waveforms, so as to serve as a quantitative index for whether the output of the switching transient simulation model is consistent with the actual device switching characteristics.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor, and particularly relates to a frequency domain evaluation method for an IGBT device switching transient simulation model based on FFT. BACKGROUND

[0002] The semiconductor device IGBT has the advantages of high reliability, simple driving, easy protection, no need of buffer circuit, high switching frequency, voltage type driving, small driving power, low saturation voltage drop, and high voltage resistance, and has become the most widely used power electronic switching device in medium and high power variable frequency devices. Since the IGBT generally undergoes high-frequency and long-time switching transient process in the normal operation process, the device is prone to damage, and therefore a large number of documents establish IGBT switching transient simulation models and analyze the waveform results of the models. However, the conventional comparison method is only to intuitively compare the output waveforms of the measured data and the simulation model, specifically to compare the coincidence degree of the voltage and current curves in the turn-on and turn-off processes. This method is obviously insufficient to serve as a quantitative fitting accuracy evaluation or as evidence supporting the correctness of the model, and therefore a new, suitable and quantifiable index is needed to test the effectiveness of the simulation model.

[0003] Due to the packaging of power devices and apparatuses, the voltage and current stress changes of the IGBT device inside cannot be directly obtained during the normal switching process of the IGBT device. Therefore, it is necessary to establish an IGBT device switching transient simulation model to simulate the voltage and current characteristics of the IGBT device and overcome the above difficulties. Meanwhile, in the switching process simulation experiment of devices such as variable frequency devices, the IGBT device switching transient simulation model can be applied to better analyze the electrical stress changes of the device under various working conditions, thereby guiding the selection of IGBT devices and circuit design in device design. At present, there is a lack of quantifiable accuracy index of the IGBT device switching transient simulation model, and in most documents, only the peak values and shapes of the voltage and current curves in the turn-on and turn-off processes are compared intuitively to determine whether the established IGBT switching transient simulation model is good or not. Such non-quantitative index can only meet the comparison of the circuit characteristics of the stable operation condition of the variable frequency device, and cannot intuitively and comprehensively reflect the accuracy of the switching transient simulation model in the IGBT device switching characteristic research under the full working condition of the variable frequency device, especially in the transient process. SUMMARY

[0004] The application provides a frequency domain evaluation method for an IGBT device switching transient simulation model based on FFT to solve the problem of the lack of quantitative index in the current evaluation of the switching transient simulation model, and the method is based on the fact that the IGBT device meets the turn-on and turn-off safety operating area.

[0005] The application adopts the following technical scheme: an IGBT device switching transient simulation model frequency domain evaluation method based on FFT, comprising:

[0006] S1: taking the duration of the complete turn-on and turn-off process of the device as the fundamental wave period, calculating the corresponding fundamental wave frequency;

[0007] S2: using the fundamental wave frequency to respectively perform Fourier transform analysis on the voltage and current waveforms in the duration, obtaining the total harmonic content THD 仿真 ;

[0008] S3: comparing the obtained total harmonic content THD 仿真 with the total harmonic content THD 实测 obtained by analyzing the measured waveforms, as a quantitative index of whether the output of the switching transient simulation model is consistent with the actual device switching characteristics.

[0009] In some embodiments, in step S1, the fundamental wave frequency is 1 / T X , and the fundamental wave period T X =T+ΔT, wherein T is the period of normal turn-on and turn-off, and ΔT is the voltage oscillation or current tail duration.

[0010] In some embodiments, ΔT is 1 μs.

[0011] In some embodiments, in step S2, the total harmonic content THD 仿真 includes THD 仿真电压 and THD 仿真电流 .

[0012] In some embodiments, in step S3, the total harmonic content THD 实测 includes THD 实测电压 , and THD 实测电流 .

[0013] In some embodiments, step S3 specifically includes:

[0014] calculating the coincidence degree of the voltage waveform P 电压 and the coincidence degree of the current waveform P 电流 , wherein:

[0015]

[0016] ;

[0017] The accuracy of the final device transient model is: P

[0018] ​

[0019] Accuracy of the transient model P The greater, the higher the accuracy.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] Compared with the current manual comparison method of switch transient characteristic curve, the present application provides a clear quantitative index, improves the evaluation ability of the IGBT switch transient model, provides better support for full working condition design and selection of devices such as frequency converters, improves the design efficiency, and reduces the research and development period and cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a switch transient simulation waveform comparison chart of model 1 and the real waveform of the device;

[0023] Figure 2 It is a switch transient simulation waveform comparison chart of model 2 and the real waveform of the device;

[0024] Figure 3 It is an FFT analysis spectrum and THD value of the measured voltage in the switch transient process of the IGBT device provided by the present application;

[0025] Figure 4 It is an FFT analysis spectrum and THD value of the simulated voltage in the switch transient process of the IGBT device provided by the present application;

[0026] Figure 5 It is an FFT analysis spectrum and THD value of the measured current in the switch transient process of the IGBT device provided by the present application;

[0027] Figure 6 It is an FFT analysis spectrum and THD value of the simulated current in the switch transient process of the IGBT device provided by the present application;

[0028] Figure 7 It is an FFT analysis spectrum and THD value of the voltage characteristic of model 1;

[0029] Figure 8 It is an FFT analysis spectrum and THD value of the current characteristic of model 1;

[0030] Figure 9 It is a flowchart of the present application. DETAILED DESCRIPTION

[0031] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application; based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0032] As shown in Figure 9 , a frequency domain evaluation method of an IGBT device switching transient simulation model based on FFT, comprising:

[0033] S1: taking the complete turn-on and turn-off process duration of the device as a fundamental period, and calculating the corresponding fundamental frequency.

[0034] Figure 1 For the normal turn-on and turn-off V ce and I c curve of the IGBT device, the device control input signal frequency is set as f, and the period T is calculated as:

[0035] T=1 / f (1)

[0036] However, the duration T V from the turn-on voltage transient to the turn-off voltage transient, or the duration T I from the turn-on current transient to the turn-off current transient, the oscillation of V ce or the tailing of I c will occur in the turn-off process, causing the turn-off voltage or turn-off current time to be delayed, resulting in T V >T or T I >T.

[0037] The present application considers that when FFT is applied to analyze the voltage or current waveform, the fundamental period should cover the complete turn-on and turn-off process of the voltage or current, so the fundamental period should be T V or T I . However, due to the voltage oscillation or current tailing, the waveform will be weakened in the oscillation process, making it difficult to determine T V or T I . Considering that the duration of voltage oscillation or current tailing is usually less than 1us, in the present application, the fundamental period T X of FFT is taken as T+ΔT, and ΔT is taken as 1us, wherein ΔT is greater than the duration of voltage oscillation or current tailing, and is to ensure that the fundamental period of FFT covers the complete turn-on and turn-off process of the IGBT voltage and current, and then the fundamental frequency of FFT analysis is 1 / T X .

[0038] S2: using the fundamental frequency, respectively, on the segment duration of voltage, current waveform Fourier transform analysis, get the total harmonic content THD 仿真 .

[0039] Total harmonic content THD 仿真 Including THD 仿真电压 And THD 仿真电流 .

[0040] Figures 2-5 Is the FFT analysis of IGBT device switching transient process spectrum and THD content, respectively, THD 实测电压 , THD 仿真电压 , THD 实测电流 And THD 仿真电流 .

[0041] Fourier transform is a kind of transform method of time domain signal waveform into signal waveform, through the integral , get the signal in the frequency domain component, can calculate the total harmonic content THD index, the specific function is realized by Matlab mathematical calculation software.

[0042] In this patent, by Fourier analysis of the measured, simulated time domain voltage, current signal, can get the total harmonic content THD of the corresponding signal.

[0043] S3: the total harmonic content THD 仿真 And the total harmonic content THD 实测 Obtained by waveform analysis, as a quantitative index of switching transient simulation model output and the actual device switching characteristics consistent.

[0044] Total harmonic content THD 实测 Including: THD 实测电压 , and THD 实测电流 .

[0045] THD 仿真 Of the simulation curve and THD 实测 The value of the measured curve is closer, the higher the accuracy of the IGBT switching transient simulation model, more in line with the real transient characteristics of the device. At the same time, the invention needs to calculate the THD content of the voltage and current curve of IGBT device respectively, the following formula is used to calculate the coincidence degree of voltage waveform P 电压 , the coincidence degree of current waveform P 电流 :

[0046] (2)

[0047] (3)

[0048] Accuracy of final device transient model P is:

[0049]

[0050] Accuracy of transient model P The greater, the higher the accuracy.

[0051] Switching transient simulation model is established for a certain type of IGBT, model 1 is the classical Hefner model, model 2 is the model improved on the basis of Hefner model, which has been verified and is superior to model 1, taking model 1 and model 2 as examples, the switching transient simulation waveform of model 1 and the real waveform of the device are compared as shown in Figure 1 .

[0052] The switching transient simulation waveform of model 2 and the real waveform of the device are compared as shown in Figure 2 .

[0053] Considering that when applying FFT to analyze voltage or current waveform, the fundamental period should cover the complete opening process of voltage or current, so the fundamental period should be T = 20.65us. Considering that the voltage oscillation or current tail duration is usually less than 1us, take ΔT as 1us, then T X =T+ΔT=20.65+1=21.65us, the fundamental frequency of FFT analysis is also 1 / T X =47.6KHz. The specific parameters are set as above, which will be realized by using the FFT Analyzer function in MATLAB mathematical software.

[0054] The FFT analysis of voltage characteristics of IGBT device is shown in Figure 3 ;

[0055] The FFT analysis of current characteristics of IGBT device is shown in Figure 5 ;

[0056] The FFT analysis of voltage characteristics of model 1 is shown in Figure 7 .

[0057] The FFT analysis of current characteristics of model 1 is shown in Figure 8 .

[0058] The FFT analysis of voltage characteristics of model 2 is shown in Figure 4 .

[0059] The FFT analysis of current characteristics of model 2 is shown in Figure 6 .

[0060] THD of real voltage waveform of IGBT device under switching transient condition 实测电压The actual current waveform THD is 159.94%. 实测电流 The figure is 476.11%. The total harmonic distortion (THD) indices for Model 1 and Model 2 are summarized in the table below:

[0061]

[0062] Model 2 P The metric is clearly superior to Model 1. P The indicators were set to be better than those of Model 1 before the experiment. Therefore, the frequency domain evaluation method of IGBT device switching transient simulation model based on FFT proposed in this patent can verify the effectiveness of the IGBT device switching model.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency domain evaluation method for IGBT device switching transient simulation model based on FFT, characterized in that, include: S1: Take the duration of a complete turn-on and turn-off process of the device as the fundamental period and calculate its corresponding fundamental frequency. The fundamental frequency is 1 / T X The fundamental period T X =T+ΔT, where T is the normal turn-on and turn-off period, and ΔT is the duration of voltage oscillation or current tailing. S2: Using the fundamental frequency, perform Fourier transform analysis on the voltage and current waveforms during this continuous process to obtain the total harmonic distortion (THD). 仿真 ; S3: The total harmonic content (THD) obtained 仿真 Total Harmonic Distortion (THD) obtained from measured waveform analysis 实测 The comparison is used as a quantitative indicator to determine whether the output of the switching transient simulation model is consistent with the actual switching characteristics of the device. Step S3 specifically includes: Calculate the overlap of voltage waveforms P 电压 and the overlap of current waveforms P 电流 ,in: ； Accuracy of the final device transient model P for: Transient model accuracy P The larger the value, the higher the accuracy.

2. The frequency domain evaluation method for the IGBT device switching transient simulation model based on FFT according to claim 1, characterized in that, The value of ΔT is 1 μs.

3. The frequency domain evaluation method for the switching transient simulation model of IGBT devices based on FFT according to claim 1, characterized in that, In step S2, the total harmonic content (THD) 仿真 Including THD 仿真电压 and THD 仿真电流 .

4. The frequency domain evaluation method for the switching transient simulation model of IGBT devices based on FFT according to claim 3, characterized in that, In step S3, the total harmonic content (THD) 实测 Includes: THD 实测电压 and THD 实测电流 .

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