Intelligent automatic test system for IGBT device

Abstract

The application relates to the technical field of IGBT device performance testing, in particular to an intelligent automatic testing system for IGBT devices, which comprises a data acquisition module, a data analysis module and a data testing module.The data acquisition module is used for acquiring various types of data of each IGBT device at each moment under the same temperature; the data analysis module is used for analyzing the difference between all peak values and corresponding adjacent trough values in all short-circuit currents of each IGBT device, determining the oscillation difference value of each IGBT device, and combining the distribution of all peak values and all short-circuit currents in the adjacent area and the mutation offset coefficient to determine the oscillation abnormality coefficient of each IGBT device; and the data testing module is used for detecting the IGBT device.The application improves the accuracy of IGBT device performance testing by analyzing the change trend characteristics of the short-circuit current of the IGBT device under different temperatures and the consistency of the oscillation characteristics of the short-circuit current and temperature changes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of IGBT device performance testing, and particularly relates to an intelligent automatic testing system for IGBT devices. BACKGROUND

[0002] IGBT devices have the advantages of high blocking voltage, low on-state voltage, large current-carrying density, etc., and are widely used in the fields of rail transit, new energy power generation, electric vehicles, etc. In order to improve the efficiency of the converter system and reduce the production and maintenance costs, such IGBT devices generally adopt a multi-chip integrated packaging power module structure. The module has become the main power electronic switching device in the converter system, and fully exerting the performance of the IGBT and ensuring the reliable operation of the IGBT are prerequisites for the normal operation of the converter system.

[0003] In the production process, the performance of the IGBT device needs to be automatically tested. The existing method mainly acquires the electrical performance parameters such as the saturation voltage and short-circuit current of the IGBT device, and compares whether the detected electrical performance parameters meet the design specifications to judge the quality of the IGBT device. However, the performance of the IGBT device is disturbed by the change of the junction temperature, and the short-circuit current will change to different degrees under different junction temperature conditions. Therefore, the existing method has the defect of insufficient accuracy of the performance test result. SUMMARY

[0004] In order to solve the above technical problems, the purpose of the present application is to provide an intelligent automatic testing system for IGBT devices, and the technical solution adopted is as follows:

[0005] The present application provides an intelligent automatic testing system for IGBT devices, which comprises:

[0006] A performance data acquisition module is configured to acquire various types of data of each IGBT device at each time under different temperatures, wherein the short-circuit current is one type of data among all types of data, and all types of data of each IGBT device at each time under each temperature form a triple;

[0007] A performance data analysis module is configured to cluster all triples of each IGBT device under each temperature, obtain two cluster clusters, and determine the mutation difference coefficient of each IGBT device under each temperature based on the difference of all triples between the two cluster clusters in each IGBT device;

[0008] Based on the difference between each type of data of each IGBT device at each time and the corresponding same type of data of each IGBT device at each time, and in combination with the mutation difference coefficient, the mutation offset coefficient of each IGBT device under each temperature is determined;

[0009] determining an oscillation difference value of each IGBT device at each temperature based on the difference between each peak value and its respective adjacent valley value in the fitted curve of all short-circuit currents of each IGBT device, and determining an oscillation anomaly coefficient of each IGBT device at each temperature in combination with the distribution of all short-circuit currents in the neighborhood of each peak value and the mutation offset coefficient;

[0010] a performance data testing module for recording the average short-circuit current of each IGBT device at each temperature as the average short-circuit current of each IGBT device at each temperature;

[0011] determining a trend significance of each IGBT device based on the variation trend and distribution of the average short-circuit current of each IGBT device at all temperatures, and determining a quality evaluation coefficient of each IGBT device in combination with the correlation between the oscillation anomaly coefficient of each IGBT device at all temperatures and the oscillation anomaly coefficients of all other IGBT devices at all temperatures, to detect the IGBT device.

[0012] Preferably, the mutation difference coefficient of each IGBT device at each temperature is the average of the differences between all triplets in one cluster of each IGBT device and all triplets in another cluster.

[0013] Preferably, the determination method of the mutation offset coefficient of each IGBT device at each temperature is:

[0014] determining a comprehensive difference coefficient of each IGBT device at each temperature based on the difference between each type of data of each IGBT device at all times and the corresponding same type of data of all other IGBT devices at all times;

[0015] The expression of the mutation offset coefficient of each IGBT device at each temperature is: ; in the formula, represents the mutation offset coefficient of the i-th IGBT device at temperature k; represents the mutation difference coefficient of the i-th IGBT device at temperature k; represents the comprehensive difference coefficient of the i-th IGBT device at temperature k.

[0016] Preferably, the determination method of the comprehensive difference coefficient of each IGBT device at each temperature is:

[0017] calculating the average of the differences between each type of data between different IGBT devices, and taking the average of all said averages of each type of data as the comprehensive difference coefficient.

[0018] Preferably, the determination method of the oscillation difference value of each IGBT device at each temperature is:

[0019] The current fitting curve of each IGBT device at each temperature is obtained by fitting all short-circuit currents of each IGBT device at each temperature, and the average of the difference between each peak value on the current fitting curve of each IGBT device at each temperature and the adjacent valley value thereof is analyzed, which is recorded as the first average of each peak value on the current fitting curve of each IGBT device at each temperature.

[0020] The oscillation difference value of each IGBT device at each temperature is the average of the first average of all peak values on the current fitting curve of each IGBT device at each temperature.

[0021] Preferably, the method for determining the oscillation anomaly coefficient of each IGBT device at each temperature is as follows:

[0022] The kurtosis of each peak value and all fitting values in the neighborhood of each peak value on the current fitting curve of each IGBT device at each temperature is determined.

[0023] The cumulative sum of the kurtosis of all peak values of each IGBT device at each temperature is determined, which is recorded as the peak steepness index of each IGBT device.

[0024] The expression of the oscillation anomaly coefficient of each IGBT device at each temperature is as follows: ; in the formula, represents the oscillation anomaly coefficient of the i-th IGBT device at temperature k; represents the mutation offset coefficient of the i-th IGBT device at temperature k; represents the peak steepness index of the i-th IGBT device at temperature k; represents the oscillation difference value of the i-th IGBT device at temperature k.

[0025] Preferably, the method for determining the trend significance of each IGBT device is as follows:

[0026] The average short-circuit current of each IGBT device at all temperatures is taken as the input of the trend test algorithm, and the absolute value of the output trend test result is taken as the trend significant feature of each IGBT device.

[0027] The trend significance of each IGBT device is the product of the average of the average short-circuit current of each IGBT device at all temperatures and the trend significant feature.

[0028] Preferably, the method for determining the quality evaluation coefficient of each IGBT device is as follows:

[0029] The oscillation consistency of each IGBT device is determined based on the correlation between the oscillation anomaly coefficient of each IGBT device at all temperatures and the oscillation anomaly coefficients of other IGBT devices at all temperatures.

[0030] The expression of the quality evaluation coefficient of each IGBT device is: ; in the formula, represents the quality evaluation index of the i-th IGBT device; represents the trend significance of the i-th IGBT device; represents the oscillation consistency of the i-th IGBT device.

[0031] Preferably, the determination method of the oscillation consistency of each IGBT device is:

[0032] The oscillation anomaly sequence of each IGBT device is composed of the oscillation anomaly coefficients of each IGBT device at all temperatures;

[0033] The oscillation consistency of each IGBT device is the average of the correlation of the oscillation anomaly sequence of each IGBT device and the oscillation anomaly sequences of all other IGBT devices.

[0034] Preferably, the detection of the IGBT device comprises:

[0035] If the normalized value of the quality evaluation index of the IGBT device is less than a preset value, the corresponding IGBT device has a production fault, otherwise, the IGBT device is produced normally.

[0036] The present application has the following beneficial effects:

[0037] The present application determines the mutation offset coefficient of each IGBT device at each temperature by analyzing the differences between the various data of each IGBT device at all times and the corresponding same type data of all other IGBT devices at all times, and combining the mutation difference coefficient. Based on the differences between all peak values and their respective adjacent valley values in the fitted curve of all short-circuit currents of each IGBT device, the oscillation difference value of each IGBT device at each temperature is determined, and the oscillation anomaly coefficient of each IGBT device at each temperature is determined in combination with the distribution of all short-circuit currents in the neighborhood of each peak value and the mutation offset coefficient. The beneficial effect is that it can reflect the stability of the performance of the IGBT device.

[0038] The present application determines the trend significance of each IGBT device based on the change trend and distribution of the average short-circuit current of each IGBT device at all temperatures, and determines the quality evaluation coefficient of each IGBT device in combination with the correlation between the oscillation anomaly coefficient of each IGBT device at all temperatures and the oscillation anomaly coefficients of all other IGBT devices at all temperatures. The beneficial effect is that it can comprehensively evaluate the quality and reliability of the IGBT device.

[0039] The application determines the quality evaluation index of the IGBT device by analyzing the change trend characteristics of the short-circuit current of the IGBT at different temperatures and the consistency of the oscillation characteristics of the short-circuit current and the temperature change, comprehensively evaluates the quality of the IGBT device, and improves the accuracy of the performance test of the IGBT device. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0041] Figure 1 A block diagram of an intelligent automatic test system of an IGBT device provided by an embodiment of the present application is provided.

[0042] Figure 2 A schematic diagram of a quality evaluation coefficient extraction process provided by an embodiment of the present application is provided.

[0043] Figure 3 A schematic diagram of an IGBT device automatic test process provided by an embodiment of the present application is provided. DETAILED DESCRIPTION

[0044] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the specific implementation, structure, features and effects of an intelligent automatic test system of an IGBT device according to the present application are described in detail as follows by combining the drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0046] The specific scheme of the intelligent automatic test system of the IGBT device provided by the present application is described in detail below in combination with the drawings.

[0047] Please refer to Figure 1 which shows a block diagram of an intelligent automatic test system of an IGBT device provided by an embodiment of the present application, the system comprising: a performance data acquisition module 101, a performance data analysis module 102, and a performance data test module 103.

[0048] The performance data collection module is configured to collect various types of data of each IGBT device at each time under different temperatures, wherein the short-circuit current is one of the various types of data, and all types of data of each IGBT device at each time under different temperatures form a triple.

[0049] The plurality of IGBT devices to be detected are connected in parallel in the test circuit for detection as the same batch, and an oscilloscope is used to collect various types of data of each IGBT device at each time within a preset time period under different temperatures, wherein the various types of data include three performance parameters of the short-circuit current, the saturation voltage and the gate current, the length of the preset time period is t, and the sampling time interval is T.

[0050] It should be noted that the values of the collection time t and the time interval T are artificially set, and in the embodiment, the value of the collection time t is 50 , the value of the time interval T is 1 , and the implementer can also set them according to the specific situation, which is not specially limited in the embodiment.

[0051] Further, in order to obtain the performance of the IGBT under different temperature conditions, the measurement is performed under different temperature environments, the temperature interval during the test is set, and the detection is performed every preset interval within the temperature interval.

[0052] It should be noted that the values of the temperature interval and the detection interval are artificially set, and in the embodiment, the range of the temperature interval is 25-145℃, and the value of the preset interval is 10℃, and the implementer can also set them according to the specific situation, which is not specially limited in the embodiment.

[0053] The performance data analysis module is configured to cluster all triples of each IGBT device under different temperatures to obtain two cluster clusters, determine a mutation difference coefficient of each IGBT device under different temperatures based on the differences of all triples between the two cluster clusters in each IGBT device, determine a mutation offset coefficient of each IGBT device under different temperatures based on the differences of various types of data of each IGBT device at each time and corresponding types of data of other IGBT devices at each time, and in combination with the mutation difference coefficient, determine an oscillation abnormality coefficient of each IGBT device under different temperatures based on the differences of all peak values and their respective adjacent valley values in a fitted curve of all short-circuit currents of each IGBT device, and in combination with the distribution of all short-circuit currents in the neighborhood of each peak value and the mutation offset coefficient.

[0054] S1: determining a mutation deviation coefficient of each IGBT device at each temperature based on the difference between each type of data of each IGBT device at all times and the corresponding same type of data of each IGBT device at all times, in combination with the mutation deviation coefficient.

[0055] The measurement of short-circuit current can help evaluate the performance of the IGBT device under abnormal conditions, the saturation voltage is a key parameter for measuring the voltage drop of the IGBT in the on state, and the size of the gate current directly affects the switching speed and driving power of the IGBT. In the production process of the IGBT device, the process control may not be strict, resulting in abnormal amplitude or overall deviation of some performance parameters in the IGBT device.

[0056] When the IGBT device is of good quality, all short-circuit currents, all saturation voltages and all gate currents in the corresponding period are relatively stable as a whole, and when the IGBT device is abnormal, some of all short-circuit currents, all saturation voltages and all gate currents in the corresponding period have dramatic changes.

[0057] Therefore, based on the abnormal amplitude or overall deviation characteristics of all short-circuit currents, all saturation voltages and all gate currents in each period, the following analysis is performed, specifically:

[0058] (1) First, the short-circuit current, saturation voltage and gate current of each IGBT device at each time at each temperature are combined into a three-tuple.

[0059] Further, all three-tuples of each IGBT device at each temperature are taken as the input of the clustering algorithm, and two clustering clusters are output.

[0060] It should be noted that there are many commonly used clustering algorithms, and in the present embodiment, fuzzy C-means clustering algorithm is used to cluster all three-tuples of each IGBT device at each temperature to obtain two clustering clusters; in actual application, the implementer can also use k-means clustering algorithm to cluster the three-tuples, and the selection of the clustering method is not specially limited in the present embodiment.

[0061] Among them, the fuzzy C-means clustering is a known technology, and the specific process of clustering data will not be repeated.

[0062] (2) If the IGBT device has quality problems, one or more parameter values in the three-tuple have abnormal mutations, which further cause the difference between the clustering clusters to become larger, while the difference between the clustering clusters under the good quality state is relatively smaller.

[0063] Therefore, the average of the difference between all three-tuples in one clustering cluster and all three-tuples in the other clustering cluster of each IGBT device at each temperature is further analyzed, which is recorded as the mutation deviation coefficient of each IGBT device at each temperature.

[0064] The greater the value of the mutation difference coefficient is, the more likely the abnormal amplitude of the short-circuit current, the saturation voltage or the gate current of the corresponding IGBT device exists.

[0065] It should be noted that there are many methods for measuring the difference between triplets. In the embodiment, the Mahalanobis distance between all triplets in each cluster and all triplets in another cluster is calculated to measure the difference between corresponding triplets in different cluster clusters. The implementer can also use the Euclidean distance or other methods for measuring the difference between three-dimensional data. The embodiment does not make special restrictions.

[0066] The calculation process of the Mahalanobis distance is a known technology, and the specific calculation process will not be described again.

[0067] (3) Further, to analyze the difference in performance between different IGBT devices in the same batch, the average of the difference between the various data in different IGBT devices is calculated, and the average of the average of all class data is taken as the comprehensive difference coefficient. The specific implementation steps are as follows:

[0068] First, the short-circuit current of each IGBT device at all times under each temperature is grouped to form a short-circuit current sequence of each IGBT device under each temperature.

[0069] Further, the average of the difference between the short-circuit current sequence of each IGBT device under each temperature and the short-circuit current sequence of all other IGBT devices is analyzed, which is recorded as the short-circuit current difference of each IGBT device under each temperature. The greater the short-circuit current difference is, the more likely the corresponding IGBT short-circuit current is to exist.

[0070] It should be noted that there are many methods for measuring the difference between two sequences. In the embodiment, the DTW distance between the short-circuit current sequence of each IGBT device under each temperature and the short-circuit current sequence of all other IGBT devices is calculated to measure the difference between the short-circuit current sequences of different devices. In actual application, as an alternative implementation, the implementer can also use the Euclidean distance or other methods for measuring the difference between sequences. In the embodiment, the method for analyzing the difference between sequences described below also uses the DTW distance. The method for calculating the difference between sequences is not limited in the embodiment.

[0071] The calculation process of the DTW distance is a known technology, and the specific calculation process will not be described again.

[0072] Further, the saturation voltage of each IGBT device at all times under each temperature is grouped to form a saturation voltage sequence of each IGBT device under each temperature.

[0073] Further, the average of the difference between the saturation voltage sequence of each IGBT device at each temperature and the saturation voltage sequences of all other IGBT devices is analyzed, denoted as the saturation voltage difference of each IGBT device at each temperature.

[0074] The gate current of each IGBT device at all times at each temperature is combined to form the gate current sequence of each IGBT device at each temperature.

[0075] Further, the average of the difference between the gate current sequence of each IGBT device at each temperature and the gate current sequences of all other IGBT devices is analyzed, denoted as the gate current difference of each IGBT device at each temperature.

[0076] The greater the saturation voltage difference and the gate current difference of the IGBT device, the more likely it is that the saturation voltage and the gate current of the corresponding IGBT device have a deviation.

[0077] (4) Further, based on the short-circuit current difference, the saturation voltage difference and the gate current difference of each IGBT device at each temperature, the comprehensive difference coefficient of each IGBT device at each temperature is determined, specifically:

[0078] The comprehensive difference coefficient of each IGBT device at each temperature is the average of the short-circuit current difference, the saturation voltage difference and the gate current difference of each IGBT device at each temperature.

[0079] (5) Based on the comprehensive difference coefficient and the mutation difference coefficient of each IGBT device at each temperature, the mutation deviation coefficient of each IGBT device at each temperature is determined to evaluate the quality of the IGBT device, specifically:

[0080] The expression of the oscillation abnormality coefficient of each IGBT device at each temperature is: ; in the formula, represents the oscillation abnormality coefficient of the i-th IGBT device at temperature k; represents the mutation deviation coefficient of the i-th IGBT device at temperature k; represents the peak steepness index of the i-th IGBT device at temperature k; represents the oscillation difference value of the i-th IGBT device at temperature k.

[0081] Further, according to the mutation deviation coefficient of each IGBT device at each temperature, it can be understood that, the more unstable the performance of the IGBT device is, the greater the mutation deviation coefficient of the IGBT device is, the greater the mutation difference coefficient of the corresponding IGBT device is, and the greater the comprehensive difference coefficient of the corresponding IGBT device is; on the contrary, the more stable the performance of the IGBT device is, the smaller the mutation deviation coefficient of the IGBT device is, the smaller the mutation difference coefficient of the corresponding IGBT device is, and the smaller the comprehensive difference coefficient of the corresponding IGBT device is.

[0082] S2: Based on the difference between all peak values and their respective adjacent valley values in the fitted curve of all short-circuit currents of each IGBT device, the oscillation difference value of each IGBT device at each temperature is determined, and the oscillation abnormal coefficient of each IGBT device at each temperature is determined in combination with the distribution of all short-circuit currents in the neighborhood of each peak value and the mutation deviation coefficient.

[0083] When the IGBT is faulty, the change of the short-circuit current is very obvious. For example, the IGBT has a poor bonding wire welding, which is easy to cause the short-circuit current to oscillate, and the greater the amplitude of oscillation is, the worse the quality of the IGBT may be. Therefore, the performance of the IGBT device is further evaluated in combination with the change characteristics of the short-circuit current sequence.

[0084] The current starts in a low-value stable state, and when the short-circuit occurs, the current suddenly increases to a very high value. At this time, the current will experience a transient process, and after reaching the highest value, it will appear a small amplitude decrease and then slightly increase, and keep oscillating to reach a new larger value stable state. After maintaining for a period of time, it quickly decays to a low-value stable state. In the above transient process, the short-circuit current sequence has multiple peaks and valleys, and the oscillation characteristics of the short-circuit current are analyzed based on the peaks and valleys.

[0085] (1) First, all short-circuit currents in the short-circuit current sequence of each IGBT device at each temperature are fitted to obtain the current fitting curve of each IGBT device at each temperature.

[0086] It should be noted that there are many commonly used fitting algorithms, and in the present embodiment, the polynomial fitting technology is used to fit the discrete short-circuit current data in the short-circuit current sequence, and the implementer can also use other fitting methods such as least squares method, and the present embodiment does not make special limitations.

[0087] (2) Further, the point on the current fitting curve of each IGBT device at each temperature where the first derivative is 0 and the second derivative is less than 0 is taken as the peak position; similarly, the point on the current fitting curve of each IGBT device at each temperature where the first derivative is 0 and the second derivative is greater than 0 is taken as the valley position.

[0088] (3) Further, the average of the difference between each peak value on the current fitting curve of each IGBT device at each temperature and its adjacent valley value is analyzed, denoted as the first average of each peak value on the current fitting curve of each IGBT device at each temperature;

[0089] The average of the first difference of all peak values on the current fitting curve of each IGBT device at each temperature is analyzed, denoted as the oscillation difference value of each IGBT device at each temperature; the greater the oscillation difference value, the greater the oscillation amplitude of the short-circuit current of the corresponding IGBT device.

[0090] It should be noted that there are many methods for measuring the difference between numerical values. In the embodiment, the absolute value of the difference between each peak value and its adjacent valley value is taken as a way to measure the difference between adjacent peak and valley values. In actual application, the implementer can also use other methods such as ratio to measure the difference, which is not specially limited in the embodiment.

[0091] (4) The sharpness of the peak can reflect the response ability of the short-circuit protection circuit inside the IGBT device. The greater the sharpness, the faster the short-circuit current rises, and the performance of the IGBT may be relatively poor.

[0092] Thus, the neighborhood is set with each peak position of each IGBT device as the center point. There are many methods for dividing the neighborhood, and in the embodiment, the distance between the nearest valley position is taken as the neighborhood radius of the corresponding peak. The implementer can also choose the neighborhood division method according to the specific situation, which is not specially limited in the embodiment.

[0093] The kurtosis of each peak value and all fitting values in the neighborhood on the current fitting curve of each IGBT device at each temperature is determined.

[0094] The cumulative sum of the kurtosis of all peaks at each temperature of each IGBT device is determined, denoted as the peak steepness index of each IGBT device. The greater the peak steepness index, the poorer the response ability of the short-circuit protection circuit inside the corresponding IGBT device may be.

[0095] The calculation process of the kurtosis is a known technology, and the specific calculation process is not described again.

[0096] (5) Further, the oscillation anomaly coefficient of each IGBT device at each temperature is determined based on the peak steepness index, the oscillation difference value and the mutation offset coefficient of each IGBT device at each temperature, so as to evaluate whether there is a failure inside the IGBT device, specifically:

[0097] The expression of the oscillation anomaly coefficient of each IGBT device at each temperature is: ; in the formula, oscillation anomaly coefficient of the i-th IGBT device at temperature k. represents the mutation offset coefficient of the i-th IGBT device at temperature k; represents the peak steepness index of the i-th IGBT device at temperature k; represents the oscillation difference value of the i-th IGBT device at temperature k.

[0098] According to the oscillation anomaly coefficient of each IGBT device at each temperature, it can be understood that the more significant the short-circuit current oscillation of the IGBT device is, the greater the oscillation anomaly coefficient of the IGBT device is, the greater the oscillation anomaly coefficient of the corresponding device is, the greater the mutation offset coefficient is, and the greater the oscillation difference value is; on the contrary, the more stable the short-circuit current of the IGBT device is, the smaller the oscillation anomaly coefficient of the IGBT device is, the smaller the oscillation anomaly coefficient of the corresponding device is, the smaller the mutation offset coefficient is, and the smaller the oscillation difference value is.

[0099] The performance data test module 103 is configured to record the average short-circuit current of each IGBT device at each temperature as the average short-circuit current of each IGBT device at each temperature, determine the trend significance of each IGBT device based on the change trend and distribution of the average short-circuit current of each IGBT device at all temperatures, and determine the quality evaluation coefficient of each IGBT device by combining the correlation between the oscillation anomaly coefficient of each IGBT device at all temperatures and the oscillation anomaly coefficients of other IGBT devices at all temperatures, to detect the IGBT device.

[0100] S3: The performance data test module 103 is configured to record the average short-circuit current of each IGBT device at each temperature as the average short-circuit current of each IGBT device at each temperature, determine the trend significance of each IGBT device based on the change trend and distribution of the average short-circuit current of each IGBT device at all temperatures, and determine the quality evaluation coefficient of each IGBT device by combining the correlation between the oscillation anomaly coefficient of each IGBT device at all temperatures and the oscillation anomaly coefficients of other IGBT devices at all temperatures.

[0101] IGBT devices are often applied in parallel to work in high-power scenarios and will frequently suffer from the impact of electro-thermal stress, resulting in the increase of junction temperature inside the device and further failure. For a good quality IGBT device, the greater the short-circuit current is, and the more significant the increasing trend of the short-circuit current is as the temperature rises. For a defective IGBT device, the short-circuit current is smaller, and the increasing trend of the short-circuit current is slower as the temperature rises.

[0102] Therefore, the size and change trend characteristics of the short-circuit current of each IGBT device at different temperatures are analyzed, specifically:

[0103] (1) The average short-circuit current of each IGBT device at each temperature is recorded as the average short-circuit current of each IGBT device at each temperature.

[0104] The average short-circuit current of each IGBT device at all temperatures is taken as an input of a trend test algorithm, and the absolute value of the output trend test result is taken as a trend significance feature of each IGBT device.

[0105] It should be noted that there are many commonly used trend test algorithms, and in the embodiment, the Mann-Kendall trend test algorithm is used to obtain the trend significance feature of each IGBT device, and the Cox-Stuart trend test algorithm can also be used to analyze the change trend of the average short-circuit current at all temperatures, and the embodiment does not make special limitations.

[0106] The process of the Mann-Kendall trend test algorithm for detecting the change trend of a group of data is a known technology, and the specific process will not be repeated.

[0107] The trend significance of each IGBT device is the product of the mean value of the average short-circuit current of each IGBT device at all temperatures and the trend significance feature.

[0108] The greater the trend significance, the more obvious the change of the short-circuit current of the IGBT device with temperature, and the better the quality of the IGBT device, and the greater the mean value of the average short-circuit current of the IGBT device at all temperatures, and the greater the trend significance feature; on the contrary, the smaller the trend significance, the less obvious the change of the short-circuit current of the IGBT device with temperature, and the worse the quality of the IGBT device, and the smaller the mean value of the average short-circuit current of the IGBT device at all temperatures, and the smaller the trend significance feature.

[0109] (2) In parallel applications, due to the differences between devices, the loss distribution of IGBT devices will be uneven, causing different junction temperatures of IGBT devices, and further affecting the degree of change of short-circuit current.

[0110] Therefore, the oscillation abnormality coefficients of each IGBT device at all temperatures are arranged in ascending order of temperature to form an oscillation abnormality sequence of each IGBT device;

[0111] The mean value of the correlation of the oscillation abnormality sequence of each IGBT device and the oscillation abnormality sequences of all other IGBT devices is analyzed, and is recorded as the oscillation consistency of each IGBT device. The greater the oscillation consistency, the less the corresponding IGBT device is affected by uneven loss in the circuit.

[0112] It should be noted that there are many methods for measuring the correlation between sequences, and in the embodiment, the Pearson correlation coefficient between the oscillation abnormal sequences of different IGBT devices is calculated to measure the correlation between the oscillation abnormal sequences of different IGBT devices, and the implementer can also use the Kendall rank correlation coefficient to measure the correlation between different sequences. The selection of the method for measuring the correlation between sequences is not specially limited in the embodiment, and the implementer can select it according to the specific circumstances.

[0113] (3) Further, based on the trend significance and oscillation consistency of each IGBT device, a quality evaluation coefficient of each IGBT device is determined to comprehensively evaluate the quality and reliability of the IGBT device, specifically:

[0114] The expression of the quality evaluation coefficient of each IGBT device is: ; in the formula, indicates the quality evaluation index of the i-th IGBT device; indicates the trend significance of the i-th IGBT device; indicates the oscillation consistency of the i-th IGBT device.

[0115] Further, according to the quality evaluation coefficient of each IGBT device, if the quality of the IGBT device is better, the quality evaluation index of the IGBT device is larger, the trend significance of the corresponding IGBT device is larger, and the oscillation consistency of the corresponding IGBT device is larger; on the contrary, if the quality of the IGBT device is worse, the quality evaluation index of the IGBT device is smaller, the trend significance of the corresponding IGBT device is smaller, and the oscillation consistency of the corresponding IGBT device is smaller.

[0116] Preferably, the embodiment provides a quality evaluation coefficient extraction process diagram as shown in Figure 2 .

[0117] S4: Based on the quality evaluation coefficient of each IGBT device, each IGBT device is detected.

[0118] The embodiment obtains the quality evaluation coefficient of the IGBT device by analyzing the trend change characteristics of the short-circuit current of the IGBT device at different temperatures and the degree of oscillation of the short-circuit current.

[0119] Further, based on the quality evaluation coefficient of each IGBT device, each IGBT device is detected, specifically:

[0120] If the normalized value of the quality evaluation index of the IGBT device is less than a preset value, the corresponding IGBT device has a production fault; on the contrary, if the normalized value of the quality evaluation index of the IGBT device is greater than or equal to the preset value, the corresponding IGBT device is produced normally.

[0121] It should be noted that the preset value is artificially set, and the preset value in the embodiment is 0.75, and the implementer can also set it by himself according to the specific situation, and the embodiment does not have special limitation.

[0122] At this point, by analyzing the change trend characteristics of the IGBT short-circuit current at different temperatures, and the consistency of the oscillation characteristics of the short-circuit current and the temperature change, the quality evaluation index of the IGBT device is determined, the quality of the IGBT device is comprehensively evaluated, and the performance test of the IGBT device is completed.

[0123] Preferably, the schematic diagram of the automatic test process of the IGBT device provided by the embodiment is as shown in Figure 3 .

[0124] It should be noted that the above-mentioned embodiment of the application is only for description, and does not represent the advantages and disadvantages of the embodiment. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0125] Each embodiment in the specification is described in a progressive manner, and the same and similar parts between each embodiment can be referred to each other, and each embodiment mainly describes the difference from other embodiments.

[0126] The above only describes the preferred embodiment of the application, and does not limit the application, and any modification, equivalent replacement, improvement, etc. within the principle of the application should be included in the protection scope of the application.

Claims

1. An intelligent automatic test system for IGBT devices, characterized in that: The system comprises: The performance data acquisition module is used to obtain various data of each IGBT device at different temperatures at different times. The short-circuit current is one of all the data types. All the data types of each IGBT device at different temperatures at different times form a triplet. A performance data analysis module is used to cluster all triplets of each IGBT device at each temperature to obtain two clusters, and determine the mutation difference coefficient of each IGBT device at each temperature based on the mean of the difference between all triplets of the two clusters in each IGBT device; Based on the difference between various data of each IGBT device at all times and the corresponding similar data of other IGBT devices at all times, combined with the mutation difference coefficient, determine the mutation offset coefficient of each IGBT device at each temperature; Based on the differences between all peak values ​​and their respective adjacent trough values ​​in the fitted curve of all short-circuit currents of each IGBT device, the oscillation difference value of each IGBT device at each temperature is determined, and combined with the distribution of all short-circuit currents in each peak value and its neighborhood, as well as the sudden shift coefficient, the oscillation anomaly coefficient of each IGBT device at each temperature is determined; the neighborhood of the peak is obtained by taking the distance between the peak and the trough position closest to the peak as the neighborhood radius of the corresponding peak; A performance data testing module is used to record the average of all short-circuit currents of each IGBT device at each temperature as the average short-circuit current of each IGBT device at each temperature; Based on the changing trend and distribution of the average short-circuit current of each IGBT device at all temperatures, the trend significance of each IGBT device is determined. In combination with the correlation between the oscillation abnormality coefficient of each IGBT device at all temperatures and the oscillation abnormality coefficient of other IGBT devices at all temperatures, the quality assessment coefficient of each IGBT device is determined and the IGBT device is tested. The method for determining the sudden shift coefficient of each IGBT device at each temperature is as follows: Calculate the mean of the differences between different IGBT devices for each type of data, and take the average of the mean values ​​of all types of data as the comprehensive difference coefficient; The expression of the sudden offset coefficient of each IGBT device at each temperature is: Where, represents the sudden shift coefficient of the ith IGBT device at temperature k; represents the mutation difference coefficient of the i-th IGBT device at temperature k; represents the comprehensive difference coefficient of the ith IGBT device at temperature k; The method for determining the oscillation difference value of each IGBT device at each temperature is as follows: Fitting all short-circuit currents of each IGBT device at each temperature to obtain a current fitting curve, analyzing the average of the differences between each peak value and its adjacent valley value on the current fitting curve of each IGBT device at each temperature, and recording it as the first average value of each peak value on the current fitting curve of each IGBT device at each temperature; The oscillation difference value of each IGBT device at each temperature is the average of the first average values ​​of all wave peak values ​​on the current fitting curve of each IGBT device at each temperature; The method for determining the oscillation abnormality coefficient of each IGBT device at each temperature is as follows: Determine the kurtosis of each peak value and all fitting values ​​in its neighborhood on the current fitting curve of each IGBT device at each temperature; Determine the cumulative sum of the peaks of all the peaks of each IGBT device at each temperature, and record it as the peak steepness index of each IGBT device; The expression of the oscillation abnormal coefficient of each IGBT device at each temperature is: Where, represents the oscillation anomaly coefficient of the i-th IGBT device at temperature k; represents the sudden shift coefficient of the ith IGBT device at temperature k; represents the peak steepness index of the i-th IGBT device at temperature k; represents the oscillation difference value of the i-th IGBT device at temperature k; The method for determining the trend significance of each IGBT device is: The average short-circuit current of each IGBT device at all temperatures is used as the input of the trend detection algorithm, and the absolute value of the trend detection result is output as the trend significance feature of each IGBT device; The trend significance of each IGBT device is the product of the average short-circuit current of each IGBT device at all temperatures and the trend significance feature; The method for determining the quality assessment coefficient of each IGBT device is as follows: The oscillation anomaly coefficients of each IGBT device at all temperatures are combined into an oscillation anomaly sequence of each IGBT device; the oscillation consistency of each IGBT device is the mean value of the correlation between the oscillation anomaly sequence of each IGBT device and the oscillation anomaly sequences of all other IGBT devices; The expression for the quality assessment coefficient of each IGBT device is: Where, represents the quality assessment index of the i-th IGBT device; Indicates the trend significance of the i-th IGBT device; Represents the oscillation consistency of the i-th IGBT device.

2. The intelligent automatic testing system for IGBT devices according to claim 1, characterized in that: The detecting of the IGBT device includes: If the normalized value of the quality assessment index of the IGBT device is less than a preset value, then the corresponding IGBT device has a production fault; otherwise, the IGBT device is produced normally.

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