Intelligent protection method for IGBT detection

Abstract

The application relates to the technical field of IGBT detection protection, and particularly discloses an intelligent protection method for IGBT detection, which specifically comprises the following steps: in a preset detection window, the saturation voltage drop of an IGBT is collected in real time, and the saturation voltage drop is converted into a real-time estimated temperature by using a prestored health state reference temperature curve; the historical drift amount of the saturation voltage drop of the IGBT at a standard temperature is analyzed, an accumulated aging factor is calculated, and the safety temperature threshold is dynamically adjusted downward according to the accumulated aging factor, so that the protection standard becomes stricter with the aging of the chip; the real-time estimated temperature is compared with the dynamic safety threshold, and once the real-time estimated temperature exceeds the dynamic safety threshold, the gate drive signal is immediately adjusted to limit the power consumption of the chip; the double values of the saturation voltage drop are combined, the upgrade from overheating protection to preventive protection based on the health state is realized, and the accuracy of protection and the reliability of equipment are improved.

Description

Technical Field

[0001] This invention relates to the field of IGBT detection and protection technology, and more specifically to an intelligent protection method for IGBT detection. Background Technology

[0002] As the core power switching device in modern power electronic systems, the reliability of the Insulated Gate Bipolar Transistor (IGBT) directly determines the performance and lifespan of the entire equipment, such as frequency converters, new energy vehicle drive controllers, and uninterruptible power supplies (UPS).

[0003] However, existing IGBT chips often face severe electrothermal stress challenges in actual operation, with overheating and long-term aging being the two main causes of failure. Currently, mainstream protection strategies in the industry generally rely on external monitoring methods, such as indirectly estimating chip temperature by installing thermistors (NTCs) on the heat sink, or monitoring collector current using Hall effect sensors and comparing it with fixed thresholds. These methods have fundamental limitations. First, monitoring based on heat sink temperature has significant thermal inertia and resistance, resulting in a severely delayed response and an inability to capture instantaneous temperature spikes caused by power surges within the chip. This leads to untimely protection and accidental burnout of the chip when it appears safe. Second, traditional fixed threshold protection strategies completely ignore the performance degradation of IGBT chips over time. An aged chip that has been used for several years will have significantly reduced heat resistance and short-circuit withstand capability. If the factory-set safety threshold is still used, it is essentially placed under overstress risk, accelerating its eventual failure. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent protection method for IGBT detection, and to solve the following technical problems.

[0005] The objective of this invention can be achieved through the following technical solutions: The intelligent protection method for IGBT detection includes the following steps: Step S1: Set a detection window and, when the IGBT chip is in the on state, collect the saturation voltage drop between the collector and emitter of the IGBT chip in real time; substitute the collected saturation voltage drop into the pre-stored reference temperature curve of the IGBT chip in a healthy state to obtain the real-time estimated temperature of the IGBT chip. Step S2: Obtain historical operating data, which includes the real-time saturation voltage drop change of the IGBT chip under standard temperature during the monitoring period; based on the historical operating data, obtain the cumulative aging factor of the IGBT chip, and set a safe temperature threshold based on the cumulative aging factor; Step S3: Compare the real-time estimated temperature with the safe temperature threshold. If the real-time estimated temperature exceeds the safe temperature threshold, adjust the gate drive signal of the IGBT chip to limit the power consumption of the IGBT chip.

[0006] As a further aspect of the present invention: the process of setting the detection window includes: The moment when the IGBT chip just enters the conduction state is obtained and recorded as the conduction moment. The moment when the load current of the IGBT chip reaches a stable state is obtained and recorded as the stable moment. Based on the conduction moment and the stable moment, a monitoring time period is obtained, and a detection window is set within the monitoring time period.

[0007] As a further aspect of the present invention: the process of obtaining the reference temperature curve includes: Several IGBT chip samples are selected, and a data acquisition time interval is set. The temperature and saturation voltage drop of the IGBT chip samples are acquired in real time during the monitoring period according to the acquisition time interval to obtain sample data. A rectangular coordinate system is established with temperature as the abscissa and saturation voltage drop as the ordinate. The sample data is converted into discrete coordinate points at corresponding positions in the rectangular coordinate system. The coordinate points are connected sequentially with a smooth curve to obtain a reference temperature curve.

[0008] As a further aspect of the present invention, the standard temperature is typically set to 25°C.

[0009] As a further aspect of the present invention: the process of obtaining the real-time saturation pressure drop change includes: The saturation voltage drop of the IGBT chip at the turn-on moment is obtained and denoted as the initial voltage drop V0. The saturation voltage drop of the IGBT chip is obtained in real time after the turn-on moment and denoted as the real-time saturation voltage drop. The change in real-time saturation voltage drop V is obtained. real-time =V-V0.

[0010] As a further aspect of the present invention: the process of setting the safe temperature threshold also includes: Based on the historical operating data, the cumulative aging factor is quantified using a lifespan decay algorithm based on the Arrhenius model; a maximum temperature threshold T is set. max The safe temperature threshold T is set based on the maximum temperature threshold. safe =T safe =T max -K×Caf, where K is the preset aging sensitivity coefficient and Caf is the cumulative aging factor.

[0011] As a further aspect of the present invention: the process of adjusting the gate drive signal of the IGBT chip includes: The gate drive signal reduces the gate drive voltage of the IGBT chip, thereby limiting the conduction loss of the IGBT chip by increasing its on-resistance.

[0012] As a further aspect of the present invention: if the real-time estimated temperature is less than or equal to the safe temperature threshold, the saturation voltage drop of the IGBT chip continues to be monitored in real time.

[0013] The beneficial effects of this invention are: Traditional protection methods rely on external circuit sensors to monitor heat sink temperature or fixed current thresholds, which suffer from fundamental defects such as response lag and inability to perceive the chip's true temperature and aging status. Compared to existing technologies, this invention compares the real-time saturation voltage drop with a pre-stored reference temperature curve to directly, quickly, and accurately estimate the chip's most critical state parameter, namely temperature. This method eliminates the need for expensive and slow-responding external temperature sensors, reducing system costs. More importantly, it eliminates the heat transfer delay from the heat sink to the chip core, achieving millisecond-level response to temperature changes, thus preventing chip burnout due to instantaneous overheating at its source. This invention also goes beyond instantaneous protection. By monitoring the minute changes in saturation voltage drop at standard temperatures over a long period, it can accurately quantify the cumulative aging factors caused by channel degradation, bond wire fatigue, etc., and dynamically and adaptively adjust the safe temperature threshold accordingly. This invention can sense the health degradation of the chip itself and automatically implement a more conservative protection strategy when the chip enters the later stage of its life cycle. This transforms post-fault handling into pre-fault health management, greatly delaying performance degradation, preventing sudden failures caused by aging, and extending the service life and operational reliability of IGBT modules in demanding application scenarios such as frequency converters and inverters. Attached Figure Description

[0014] The invention will now be further described with reference to the accompanying drawings.

[0015] Figure 1 This is a schematic diagram of the intelligent protection method for IGBT detection according to the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figure 1 As shown, the present invention is an intelligent protection method for IGBT detection, comprising the following steps: Step S1: Set a detection window and, when the IGBT chip is in the on state, collect the saturation voltage drop between the collector and emitter of the IGBT chip in real time; substitute the collected saturation voltage drop into the pre-stored reference temperature curve of the IGBT chip in a healthy state to obtain the real-time estimated temperature of the IGBT chip. Specifically, a detection window is preset, located in the middle of the stable saturation conduction region of the IGBT chip after it has been fully triggered to conduct by the gate drive signal and before the turn-off signal arrives. Within the detection window, the saturation voltage drop and collector current between the collector and emitter of the IGBT chip are synchronously sampled by a high-precision analog-to-digital converter (ADC). Data points of saturation voltage drop within ±5% error band of the rated collector current are selected and confirmed as valid saturation voltage drops. The selected real-time saturation voltage drop values ​​are matched with the reference temperature curve pre-stored in the FLASH memory and established during factory calibration. A linear interpolation algorithm is used to calculate and output the real-time estimated temperature of the IGBT chip. In a preferred embodiment of the present invention, the process of setting the detection window includes: The moment when the IGBT chip just enters the conduction state is recorded as the conduction moment, and the moment when the load current of the IGBT chip reaches a stable state is recorded as the stable moment. Based on the conduction moment and the stable moment, a monitoring time period is obtained, and a detection window is set within the monitoring time period. It is understood that the detection window is set within a specific time period after the IGBT chip is turned on and the load current reaches a stable state, so as to ensure that the collected data points can accurately correspond to the saturation conduction state of the IGBT chip, thereby eliminating dynamic interference during the switching process. In a preferred embodiment of the present invention, the process of obtaining the reference temperature curve includes: Select several IGBT chip samples and set a collection time interval. According to the collection time interval, acquire the temperature and saturation voltage drop of the IGBT chip samples in real time during the monitoring period to obtain sample data. Establish a rectangular coordinate system with temperature as the abscissa and saturation voltage drop as the ordinate. Transform the sample data into discrete coordinate points at corresponding positions in the rectangular coordinate system. Connect the coordinate points in sequence with a smooth curve to obtain the reference temperature curve. Specifically, a specified number of IGBT chip samples are randomly selected from the same production batch and installed on the test fixture of a temperature-controlled heat flow meter to ensure precise control and measurement of the chip temperature; and a fixed driving voltage sufficient to bring the IGBT chip into saturation is applied between the gate and emitter of the IGBT chip. A constant collector current with an extremely short pulse width is applied to the IGBT chip via an external circuit. The pulse width of the constant collector current is much smaller than the thermal time constant of the chip to ensure that the temperature does not rise due to self-heating during the measurement. The value of the constant collector current is set to be strictly consistent with the value of the current used in subsequent actual monitoring. The heat flow meter is controlled to make the temperature of the IGBT chip stabilize at several preset temperature gradient values. At each stable temperature gradient value, a pulse test current is applied, and the saturation voltage drop between the collector and emitter is measured synchronously using a high-precision data acquisition card, and the data pairs are recorded. Data from all IGBT chip samples measured at various temperature gradients were averaged to eliminate individual differences, and all data points were plotted in the Cartesian coordinate system. Based on the physical properties of semiconductors, these data points exhibit a good linear distribution, so the least squares method was used for linear regression fitting to obtain a baseline temperature curve. Step S2: Obtain historical operating data, which includes the real-time saturation voltage drop change of the IGBT chip under standard temperature during the monitoring period; based on the historical operating data, obtain the cumulative aging factor of the IGBT chip, and set a safe temperature threshold based on the cumulative aging factor; In a preferred embodiment of the present invention, the standard temperature is typically set to 25°C; The most commonly used and recommended standard temperature is 25°C. 25°C is the industry standard reference temperature and is very easy to measure after the device has stopped working and cooled naturally to the ambient temperature. In a preferred embodiment of the present invention, the process of obtaining the real-time saturation pressure drop change includes: The saturation voltage drop of the IGBT chip at the turn-on moment is obtained and denoted as the initial voltage drop V0. The saturation voltage drop of the IGBT chip is obtained in real time after the turn-on moment and denoted as the real-time saturation voltage drop. The change in real-time saturation voltage drop V is obtained. real-time =V-V0; In a preferred embodiment of the present invention, the process of setting the safe temperature threshold further includes: Based on the historical operating data, the cumulative aging factor is quantified using a lifespan decay algorithm based on the Arrhenius model; a maximum temperature threshold T is set. max The safe temperature threshold T is set based on the maximum temperature threshold. safe =T max -K×Caf, where K is the preset aging sensitivity coefficient and Caf is the cumulative aging factor; Specifically, during each power-on initialization of the IGBT chip, the chip temperature is automatically detected. When the chip is detected to be at the standard reference temperature of 25°C, a standardized test pulse is applied through the gate drive circuit. The test pulse has a fixed amplitude, width, and collector current conditions, which are strictly consistent with the test conditions when establishing the reference temperature curve. Under standardized conditions, the real-time saturation voltage drop is accurately measured and recorded as a valid data point for this aging assessment. This ensures that all data used for aging analysis are collected on the same thermodynamic and electrical reference, effectively eliminating the interference of temperature fluctuations and load changes on the measurement results. The initial voltage drop of the IGBT chip under the initial healthy state and the same standard temperature and test conditions is read from the non-volatile memory. The real-time saturation voltage drop and the change in real-time saturation voltage drop of the initial voltage drop are calculated. The change in real-time saturation voltage drop measured each time and its corresponding timestamp are stored to obtain historical operating data. Aging status assessments are performed according to a preset cycle. Based on the stored historical operating data, a weighted average algorithm is used to obtain the cumulative aging factor. , where w i V represents the weight coefficient of the i-th data point in the historical data. Data points closer to the current time have higher weights. real-time-i represents the real-time saturated pressure drop change of the i-th data point, n is the total number of data points in the historical operation data, i∈[1,n] and i is a positive integer; preset maximum temperature threshold, and dynamically adjust the actual safe temperature threshold according to the cumulative aging factor according to the following formula; Step S3: Compare the real-time estimated temperature with the safe temperature threshold. If the real-time estimated temperature exceeds the safe temperature threshold, adjust the gate drive signal of the IGBT chip to limit the power consumption of the IGBT chip. In a preferred embodiment of the present invention, the process of adjusting the gate drive signal of the IGBT chip includes: The gate drive signal reduces the gate drive voltage of the IGBT chip, thereby limiting the conduction loss of the IGBT chip by increasing the on-resistance of the IGBT chip. In a preferred embodiment of the present invention, if the real-time estimated temperature is less than or equal to the safe temperature threshold, the saturation voltage drop of the IGBT chip continues to be monitored in real time. It is understood that if the real-time estimated temperature is less than or equal to the safe temperature threshold, the protection logic unit will not output a protection signal, the IGBT chip will maintain its current operating state, and the method will periodically return to steps S1-S4 to continue collecting the saturation voltage drop in the next working cycle, thereby achieving continuous and uninterrupted real-time status monitoring and protection judgment; that is, regardless of whether the protection logic is triggered, the method will periodically return to steps S1-S4 to continue executing the saturation voltage drop collection and subsequent processing flow, so as to achieve continuous monitoring and protection of the IGBT chip's health status.

[0018] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the present invention should still fall within the scope of the invention.

Claims

1. An intelligent protection method for IGBT detection, characterized in that, Includes the following steps: Step S1: Set a preset detection window and collect the saturation voltage drop between the collector and emitter of the IGBT chip in real time when the IGBT chip is in the on state. The collected saturation voltage drop is substituted into the pre-stored reference temperature curve of the IGBT chip in a healthy state to obtain the real-time estimated temperature of the IGBT chip. Step S2: Obtain historical operating data, which includes the real-time saturation voltage drop change of the IGBT chip under standard temperature during the monitoring period; based on the historical operating data, obtain the cumulative aging factor of the IGBT chip, and set a safe temperature threshold based on the cumulative aging factor; Step S3: Compare the real-time estimated temperature with the safe temperature threshold. If the real-time estimated temperature exceeds the safe temperature threshold, adjust the gate drive signal of the IGBT chip to limit the power consumption of the IGBT chip.

2. The intelligent protection method for IGBT detection according to claim 1, characterized in that, In step S1, the process of setting the detection window includes: The moment when the IGBT chip just enters the conduction state is obtained and recorded as the conduction moment. The moment when the load current of the IGBT chip reaches a stable state is obtained and recorded as the stable moment. Based on the conduction moment and the stable moment, a monitoring time period is obtained, and a detection window is set within the monitoring time period.

3. The intelligent protection method for IGBT detection according to claim 1, characterized in that, In step S1, the process of obtaining the reference temperature curve includes: Several IGBT chip samples are selected, and a data acquisition time interval is set. The temperature and saturation voltage drop of the IGBT chip samples are acquired in real time during the monitoring period according to the acquisition time interval to obtain sample data. A rectangular coordinate system is established with temperature as the abscissa and saturation voltage drop as the ordinate. The sample data is converted into discrete coordinate points at corresponding positions in the rectangular coordinate system. The coordinate points are connected sequentially with a smooth curve to obtain a reference temperature curve.

4. The intelligent protection method for IGBT detection according to claim 1, characterized in that, In step S2, the standard temperature is typically set to 25°C.

5. The intelligent protection method for IGBT detection according to claim 2, characterized in that, In step S2, the process of obtaining the real-time saturation pressure drop change includes: The saturation voltage drop of the IGBT chip at the turn-on moment is obtained and denoted as the initial voltage drop V0. The saturation voltage drop of the IGBT chip is obtained in real time after the turn-on moment and denoted as the real-time saturation voltage drop. The change in real-time saturation voltage drop V is obtained. real-time =V-V0.

6. The intelligent protection method for IGBT detection according to claim 1, characterized in that, In step S2, the process of setting the safe temperature threshold further includes: Based on the historical operating data, the cumulative aging factor is quantified using a lifespan decay algorithm based on the Arrhenius model; a maximum temperature threshold T is set. max The safe temperature threshold T is set based on the maximum temperature threshold. safe =T max -K×Caf, where K is the preset aging sensitivity coefficient and Caf is the cumulative aging factor.

7. The intelligent protection method for IGBT detection according to claim 1, characterized in that, In step S3, the process of adjusting the gate drive signal of the IGBT chip includes: The gate drive signal reduces the gate drive voltage of the IGBT chip, thereby limiting the conduction loss of the IGBT chip by increasing its on-resistance.

8. The intelligent protection method for IGBT detection according to claim 1, characterized in that, In step S3, if the real-time estimated temperature is less than or equal to the safe temperature threshold, the saturation voltage drop of the IGBT chip continues to be monitored in real time.

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