A parameter monitoring determination method, a thermal fatigue aging monitoring method and related devices

Abstract

The application discloses a kind of monitoring parameter determination method, thermal fatigue aging monitoring method and related device, the present application will be equivalent to heat source when radiating emitter side and collector side between mutual influence, construct the thermal network model of press-in type IGBT module under cooling process, heat source model is solved based on thermal network model, and further obtain shell temperature model, determine the monitoring parameter of press-in type IGBT module in shell temperature model, which characterizes the thermal fatigue aging state, fill the blank of press-in type IGBT module thermal fatigue aging monitoring parameter, and based on the determined monitoring parameter can effectively realize the thermal fatigue aging monitoring of press-in type IGBT module, fill the blank of press-in type IGBT module thermal fatigue aging monitoring.

Description

Technical Field

[0001] This invention relates to a method for determining monitoring parameters, a method for monitoring thermal fatigue aging, and related devices, belonging to the field of power electronics technology. Background Technology

[0002] Mainstream IGBT (insulated gate bipolar transistor) modules include soldered IGBT modules and press-fit IGBT modules. Regardless of whether it's a soldered or press-fit IGBT module, thermal fatigue aging is one of the main causes of IGBT module failure. Most existing research focuses on monitoring the thermal fatigue aging of soldered IGBT modules, primarily by collecting the thermal time constant to determine the degree of thermal fatigue aging. However, the physical structures of press-fit IGBT modules differ from those of soldered IGBT modules. This structural difference leads to vastly different heat dissipation methods and internal thermal networks. Therefore, it is currently unclear whether thermal fatigue aging monitoring based on the thermal time constant is applicable to press-fit IGBT modules. In other words, thermal fatigue aging monitoring of press-fit IGBT modules lacks clearly defined monitoring parameters, and consequently, there is no specific method for monitoring the thermal fatigue aging of press-fit IGBT modules. Summary of the Invention

[0003] This invention provides a method for determining monitoring parameters, a method for monitoring thermal fatigue aging, and a related device, which solves the problems disclosed in the background art.

[0004] According to one aspect of this application, a method for determining monitoring parameters is provided, comprising:

[0005] Based on the heat flow direction generated by the chip in the IGBT module, and using heat sources to characterize the influence of collector-side heat dissipation on emitter-side and emitter-side heat dissipation on collector-side respectively, a thermal network model of the IGBT module under the cooling process is constructed.

[0006] Based on the thermal network model, the heat source model on side A is solved using the electrothermal analogy theory; where A is the collector or emitter.

[0007] By substituting the heat source model into the thermal network model on side A, the shell temperature model on side A is obtained.

[0008] Solve the shell temperature model on side A to determine the monitoring parameters characterizing the thermal fatigue aging state of the IGBT module in the shell temperature model on side A.

[0009] Furthermore, based on the heat flow direction generated by the chip in the IGBT module, and using heat sources to characterize the effects of collector-side heat dissipation on the emitter side and the effects of emitter-side heat dissipation on the collector side, a thermal network model of the IGBT module under the cooling process is constructed, including:

[0010] Based on the direction of heat flow generated by the chip in the IGBT module, the boundary line of the heat flow path is determined, and the boundary line is used as the starting point of the model to construct the initial thermal network model of the IGBT module under the cooling process.

[0011] The components in the initial thermal network model are simplified, and heat sources are used to characterize the effects of heat dissipation on the collector side and heat dissipation on the emitter side, respectively, to obtain a new thermal network model. This new thermal network model is then used as the thermal network model of the IGBT module during the cooling process.

[0012] Furthermore, based on the heat network model, the electrothermal analogy theory is used to solve the heat source model on side A, including:

[0013] Using the electrothermal analogy theory, the heat dissipation process in the thermal network model is equivalent to a series connection of a DC power source and a resistor. Side A is equivalent to a resistor, and the heat source in the thermal network model is equivalent to a voltage source. Based on the equivalent thermal network model, the three-element method is used to obtain the heat source model on side A.

[0014] Furthermore, the heat source model on side A is as follows:

[0015] ;

[0016] In the formula, for t Heat source on side A at time [time] They are respectively t At time 0s, the thermal capacity of the device on side B is... and the heat capacity of the B-side heat sink initial value, For the thermal resistance of the heatsink on side B, All are thermal time constants; where, if A is the collector, then B is the emitter; if A is the emitter, then B is the collector; the device on the B side is the component from the chip to the B side in the IGBT module.

[0017] Furthermore, the shell temperature model for side A is as follows:

[0018] ;

[0019] In the formula, for t The temperature of the shell on side A at that moment. All are coefficients. All are thermal time constants.

[0020] Furthermore, the shell temperature model is solved to determine the monitoring parameters characterizing the thermal fatigue aging state of the IGBT module, including:

[0021] Solve the general solution term of the case temperature model. Based on the general solution term, obtain parameters that are only related to the thermal resistance and thermal capacity of the device on side A, and parameters that are only related to the thermal resistance and thermal capacity of the heat sink on side A. Use the obtained parameters as monitoring parameters to characterize the thermal fatigue aging state of the IGBT module. Here, the device on side A is the component from the chip to side A in the IGBT module.

[0022] According to another aspect of this application, a monitoring parameter determination device is provided, comprising:

[0023] The thermal network model module constructs a thermal network model of the IGBT module under the cooling process, based on the flow direction of heat generated by the chip in the IGBT module and by using heat sources to characterize the influence of collector-side heat dissipation on emitter-side and emitter-side heat dissipation on collector-side respectively.

[0024] The heat source model module solves the heat source model on side A using the electrothermal analogy theory based on the heat network model; where A is the collector or emitter.

[0025] The shell temperature model module inputs the heat source model into the thermal network model on side A to obtain the shell temperature model on side A.

[0026] The monitoring parameter determination module solves the A-side shell temperature model to determine the monitoring parameters characterizing the thermal fatigue aging state of the IGBT module in the A-side shell temperature model.

[0027] According to another aspect of this application, a method for monitoring thermal fatigue aging is provided, characterized in that it includes:

[0028] Obtain the case temperature at various moments during the cooling process of the IGBT module;

[0029] Based on the shell temperature at each moment during the cooling process, construct the shell temperature curve for the cooling process;

[0030] Based on the cooling process shell temperature curve and shell temperature model, the values ​​of monitoring parameters characterizing the thermal fatigue aging state of the IGBT module are fitted; wherein, the monitoring parameters are the monitoring parameters determined by the above-mentioned monitoring parameter determination method; the shell temperature model is the shell temperature model obtained by the above-mentioned monitoring parameter determination method;

[0031] The thermal fatigue aging state of the IGBT module is determined based on the monitored parameter values.

[0032] According to another aspect of this application, a thermal fatigue aging monitoring device is provided, characterized in that it comprises:

[0033] The module acquires the case temperature at various moments during the cooling process of the IGBT module.

[0034] The curve construction module constructs a shell temperature curve for the cooling process based on the shell temperature at various moments during the cooling process.

[0035] The fitting module fits the values ​​of monitoring parameters characterizing the thermal fatigue aging state of the IGBT module based on the shell temperature curve and shell temperature model during the cooling process; wherein, the monitoring parameters are the monitoring parameters determined by the above-mentioned monitoring parameter determination method; the shell temperature model is the shell temperature model obtained by the above-mentioned monitoring parameter determination method.

[0036] The condition determination module determines the thermal fatigue aging state of the IGBT module based on monitored parameter values.

[0037] According to another aspect of this application, a computer-readable storage medium is provided that stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a monitoring parameter determination method or a thermal fatigue aging monitoring method.

[0038] According to another aspect of this application, a computer device is provided, including one or more processors and one or more memories, wherein one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing a monitoring parameter determination method or a thermal fatigue aging monitoring method.

[0039] The beneficial effects achieved by this invention are as follows: This invention equates the mutual influence between the emitter side and the collector side during heat dissipation as a heat source, constructs a thermal network model of the press-fit IGBT module during the cooling process, solves the heat source model based on the thermal network model, and further obtains the case temperature model. In the case temperature model, monitoring parameters characterizing the thermal fatigue aging state of the press-fit IGBT module are determined, filling the gap in thermal fatigue aging monitoring parameters for press-fit IGBT modules. Furthermore, based on the determined monitoring parameters, thermal fatigue aging monitoring of press-fit IGBT modules can be effectively realized, filling the gap in thermal fatigue aging monitoring of press-fit IGBT modules. Attached Figure Description

[0040] Figure 1 A flowchart illustrating the method for determining monitoring parameters;

[0041] Figure 2 This is a cross-sectional view of a press-fit IGBT module;

[0042] Figure 3 This is a schematic diagram of the initial thermal network model;

[0043] Figure 4 This is a schematic diagram of the thermal network model of an IGBT module during the cooling process.

[0044] Figure 5 This is a diagram illustrating the equivalent process of collector-side and capacitor discharge.

[0045] Figure 6 This is a schematic diagram of the equivalent heat network model;

[0046] Figure 7 This is a schematic diagram of the collector-side thermal network model;

[0047] Figure 8 This is a diagram showing the location of thermocouples.

[0048] Figure 9 The thermal time constant under different degrees of fretting wear when the thermocouple is at the bottom. picture;

[0049] Figure 10 The thermal time constant under different degrees of fretting wear when the thermocouple is at the bottom. picture;

[0050] Figure 11 The thermal time constant under different degrees of fretting wear when the thermocouple is at the top. picture;

[0051] Figure 12 The thermal time constant under different degrees of fretting wear when the thermocouple is at the top. picture;

[0052] Figure 13 The thermal time constant under different degrees of fretting wear when the thermocouple is located on the front side. picture;

[0053] Figure 14 The thermal time constant under different degrees of fretting wear when the thermocouple is located on the front side. picture;

[0054] Figure 15 The thermal time constant under different degrees of fretting wear when the thermocouple is on the right side. picture;

[0055] Figure 16 The thermal time constant under different degrees of fretting wear when the thermocouple is on the right side. picture;

[0056] Figure 17 The thermal time constant under different degrees of fretting wear when the thermocouple is located on the left side. picture;

[0057] Figure 18 The thermal time constant under different degrees of fretting wear when the thermocouple is located on the left side. picture;

[0058] Figure 19 Block diagram of the device for determining monitoring parameters;

[0059] Figure 20A flowchart of a method for monitoring thermal fatigue aging;

[0060] Figure 21 This is a block diagram of a thermal fatigue aging monitoring device. Detailed Implementation

[0061] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0062] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0063] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0064] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0065] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0066] It should be noted that similar symbols and letters in the following figures represent similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0067] Thermal network models are a method for simulating and analyzing heat transfer behavior in complex systems. They describe the system's thermal conduction, convection, and radiation characteristics by simplifying the physical structure into nodes and connecting elements. A thermal network model consists of nodes (representing elements or regions) and connecting elements (representing heat transfer paths). The thermal properties of each material layer are typically represented by a combination of thermal capacity and thermal resistance, as seen in models such as chips, substrates, and heat sinks. Common thermal network models include continuous network models and local network models.

[0068] This application provides a method for determining monitoring parameters based on thermal network modeling technology. The aim is to determine monitoring parameters characterizing the thermal fatigue aging state of a single-chip press-fit IGBT module by constructing a thermal network model of the module. This method can be executed by a monitoring parameter determination device, which can be a terminal device or a server. The terminal device can include, but is not limited to, mobile phones, computers, smart wearable devices, smart vehicle devices, etc. The server can be an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, big data, and artificial intelligence platforms, etc. Optionally, this method can also be executed collaboratively by multiple electronic devices with computing power. For ease of explanation, subsequent embodiments will be described as being executed by a monitoring parameter determination device.

[0069] See Figure 1 , Figure 1 This is a flowchart of a monitoring parameter determination method provided in an embodiment of this application. The monitoring parameter determination method can be executed by a monitoring parameter determination device, and the monitoring parameter determination method may include at least the following steps:

[0070] Step 1: Based on the heat flow direction generated by the chip in the IGBT module, and using heat sources to characterize the influence of collector-side heat dissipation on emitter-side and emitter-side heat dissipation on collector-side respectively, construct a thermal network model of the IGBT module under the cooling process.

[0071] It should be noted that, see Figure 2 The overall internal structure is a multi-chip IGBT module, which, from top to bottom, includes the collector, chip (i.e., IGBT chip), diode (the chip and diode are arranged in an array on the same plane), disc spring, and emitter. Figure 2 The right side of the middle section shows a single chip, which includes a support and, from top to bottom, a collector molybdenum sheet, a chip, an emitter molybdenum sheet, a silver pad, and a gate pin arranged in the support. As can be seen from the figure, the press-fit chip is composed of multiple layers of materials pressed together to form a conductive structure. Figure 2 The four small diagrams at the bottom illustrate the internal temperature distribution of the chip under four different placement schemes. In each diagram, yellow represents the material area that heats up when energized, and purple represents the surrounding non-energized parts.

[0072] Welded IGBT modules can be modeled using either a continuous network model or a local network model. However, due to the significant structural differences between press-fitted and welded IGBT modules, directly constructing a continuous or local network model cannot accurately reflect the internal heat transfer. To improve the efficiency of parameter determination, model derivation can be performed using a single-chip IGBT as an example. Therefore, in some embodiments, constructing a thermal network model of the IGBT module during the cooling process may include the following steps:

[0073] 11) Based on the direction of heat flow generated by the chip in the IGBT module, determine the boundary line of the heat flow path, and use the boundary line as the starting point of the model to construct the initial thermal network model of the IGBT module under the cooling process.

[0074] Unlike welded IGBT modules, in press-fit IGBT modules, the heat generated by the chip can be transferred to both electrodes (i.e., the emitter side and the collector side). Therefore, the bulk thermal resistance of the chip can be divided into two parts according to the heat flow path. These two parts are separated by the PN junction of the chip. Therefore, the PN junction can be used as the starting point to construct an initial thermal network model.

[0075] It should be noted that the initial thermal network model here can be a continuous network model. Continuous network models have clear physical meaning, realistically represent the heat conduction process, and can directly map the heat conduction process. For specific structures, please refer to [reference needed]. Figure 3 The model mainly includes chip (i.e., silicon chip) - collector, chip - emitter, collector-side heat sink, and emitter-side heat sink. Figure 3 middle, a and b These are the distances from the PN junction to the collector and emitter surfaces, respectively. P loss The power loss generated by the chip during normal operation is equivalent to a heat source in the continuous network model. T j For chip junction temperature, T c-c The collector-side case temperature, T c-eHere, Rchip represents the emitter-side case temperature, and Cchip represents the chip's thermal resistance and thermal capacity, respectively. Rc_chip_mo_c represents the thermal resistance at the interface between the chip and the collector molybdenum plate, Cc_chip_mo_c represents the thermal capacity at the interface between the chip and the collector molybdenum plate, Rmo_c represents the collector molybdenum plate thermal resistance, Cmo_c represents the collector molybdenum plate thermal capacity, Rc_mo_c represents the collector-side heatsink thermal resistance, Ccollector represents the collector-side heatsink thermal capacity, Rradiator_c represents the collector-side heatsink thermal resistance, Ccollector_c represents the collector-side heatsink thermal resistance, Rc_chip_mo_e represents the chip-emitter molybdenum plate thermal resistance, Cc_chip_mo_e represents the chip-emitter molybdenum plate thermal capacity, Rmo_e represents the emitter molybdenum plate thermal resistance, Cmo_e represents the emitter molybdenum plate thermal capacity, and Rc_... mo_e represents the thermal resistance at the interface between the emitter molybdenum sheet and the collector, Cc_mo_e represents the thermal capacitance at the interface between the emitter molybdenum sheet and the collector, Remitter represents the emitter thermal resistance, Cemitter represents the emitter thermal capacitance, Rradiator_e represents the thermal resistance of the emitter-side heatsink, and Ccollector_e represents the thermal capacitance of the emitter-side heatsink. In a press-fit IGBT, the internal contact surface is formed by the direct contact between the chip and the electrode material (such as a molybdenum sheet or copper plate). Thermal resistance is generated due to air gaps caused by microscopic unevenness of the contact surface, and its thermal capacitance is determined by the physical properties of the contact materials (metal and solder layer).

[0076] 12) Simplify the components in the initial thermal network model, and use heat sources to characterize the effects of heat dissipation on the collector side and heat dissipation on the emitter side, respectively, to obtain a new thermal network model. Use the new thermal network model as the thermal network model of the IGBT module under the cooling process.

[0077] It should be noted that, considering that the IGBT module does not generate power loss during the cooling process and that the chip in the IGBT module has the lowest conductivity and bears almost all of the voltage drop, the components in the model will be simplified in some embodiments for the convenience of subsequent calculations. Specifically, the same type of thermal resistance in the initial thermal network model can be simplified to one thermal resistance, and the same type of thermal capacity can be simplified to one thermal capacity.

[0078] During the cooling process, heat flows from the high-temperature side to the low-temperature side. However, as can be seen from the internal structure of the press-fit IGBT module, the physical structure from the chip to the collector and from the chip to the emitter is not completely symmetrical. Therefore, it is necessary to consider the effect of heat dissipation on one side on the other side during the cooling process. For this purpose, heat sources are used to characterize the effect of heat dissipation on the collector side on the emitter side and the effect of heat dissipation on the emitter side on the collector side.

[0079] Based on the above simplification and considering the impact of heat dissipation on both sides, Figure 3 The model in can be transformed into Figure 4 In the model, as a physically meaningful continuous network model, the chip-to-collector section is simplified to thermal resistance and thermal capacitance, while the emitter-side devices (the components from the chip to the emitter are collectively referred to as emitter-side devices) are also uniformly simplified to thermal resistance and thermal capacitance. Figure 4 middle T jc and T je These are the junction temperatures on the collector side and emitter side, respectively. T hc and T he These are the collector-side case temperature and the emitter-side case temperature, respectively. T a For ambient temperature, R c1 and R c2 These are the thermal resistances of the collector-side devices (i.e., the components from the chip to the collector are collectively referred to as collector-side devices) and the collector-side heat sink, respectively. R e1 and R e2 These are the thermal resistances of the emitter-side devices and the emitter heat sink, respectively. C c1 and C c2 These are the heat capacities of the collector-side devices and the collector heat sink, respectively. C e1 and C e2 These are the heat capacities of the emitter-side device and the emitter-side heat sink, respectively. I 1. The effect of emitter-side device heat dissipation on collector-side heat flow. I 2. The impact of collector-side device heat dissipation on emitter-side heat flow, and according to the principle of energy conservation, I 1=- I 2.

[0080] Will Figure 3 The model is simplified to Figure 4 The resulting thermal network model has fewer nodes and connections, thus reducing the number of equations to be solved and significantly lowering computational complexity. Furthermore, by using direct heat conduction between the chip and the heat sink as the primary path and ignoring the minute lateral heat flow between packaging materials, the introduced error remains within acceptable engineering limits.

[0081] Step 2: Based on the thermal network model, use the electrothermal analogy theory to solve the heat source model on side A; where A is the collector or emitter.

[0082] It should be noted that, since thermal networks and electrical networks have similar characteristics, heat source models can be constructed using electrical theory. Because the solution process for heat source models on both sides is similar, this example uses the collector side. The process of solving the heat source model can include:

[0083] 21) Using the electrothermal analogy theory, the heat dissipation process in the thermal network model is equivalent to the series connection of a DC power supply and a resistor in a circuit network, and the collector side is equivalent to a resistor.

[0084] Since the discharge process of a capacitor can be represented by a discrete numerical equation in trapezoidal form:

[0085] ;

[0086] In the formula, u c ( t ) is a capacitor t Voltage at time, R m This is the energy efficiency resistance value of the capacitor. , C 0 represents the capacitance value of the capacitor. To discretize the time step, i c ( t () represents the capacitor current. For capacitor Voltage at a given moment.

[0087] As can be seen from the above formula, in Internally, the discharge of a capacitor can be equivalent to a series connection of a DC power source and a resistor. Therefore, the heat dissipation process of the heat capacity in the thermal network model is equivalent to a series connection of a DC power source and a resistor.

[0088] The Thevenin equivalent circuit on the collector side can be represented as:

[0089] ;

[0090] In the formula, R eq This represents the Thevenin equivalent resistance value corresponding to the collector side. This represents the current voltage value of the equivalent partial capacitor. The equivalent current flowing through the capacitor is... This is the equivalent historical voltage. R m1 This represents the energy-efficiency resistance value of the equivalent partial device-side capacitance. R m2 This represents the energy-efficiency resistance value of the equivalent portion of the heat sink-side capacitor, with / / indicating that it is connected in parallel in the circuit.

[0091] The equivalent process on the collector side is obtained according to Thevenin's theorem; see [link / reference]. Figure 5 , Figure 5 middle These are the historical voltages on the equivalent device side and the heat sink side, respectively.

[0092] 22) The heat source in the thermal network model is equivalent to a voltage source. Based on the equivalent thermal network model, the three-element method is used to obtain the collector-side heat source model.

[0093] It should be noted that by performing the equivalent operation in step 21) on the thermal network model and treating the voltage sources (corresponding to the heat sources in the thermal network) as short circuits, the following can be obtained: Figure 6 The heat network model shown, Figure 6 middle, t At time 0s, the IGBT module stops heating, and the internal junction temperature begins to drop. At this point, the switch in the thermal network model is closed, and the emitter-side device is equivalent to a second-order continuous network model. Due to the smaller thermal resistance on the collector side, some of the heat released from the emitter-side thermal capacitance during heat dissipation will flow to the collector. i ( t )express, i R1 ( t This indicates the heat flow conducted from the chip to the emitter casing during the heat dissipation process. i R2 ( t This indicates the heat flow conducted from the emitter casing to the heat sink. i c1 ( t The heat flow conducted from the chip to the device side thermal capacity i c2 ( t This indicates the heat flow conducted from the emitter-side casing to the heat capacity of the radiator.

[0094] Assumption C e1 and C e2 The voltages are respectively u 1( t )and u 2( t Based on Kirchhoff's current law and voltage law, we have:

[0095] ;

[0096] We can obtain:

[0097] .

[0098] Based on the three elements of circuit principle, we obtain u 1( t )and u 2(t ) is represented as:

[0099] ;

[0100] In the formula, u 1 and u 2 are respectively t At time 0s, the thermal capacity of the emitter-side device C e1 and emitter-side heat sink heat capacity C e2 initial value, , This is a thermal time constant that is only relevant to the derivation of the heat source.

[0101] available:

[0102] ;

[0103] In the formula, i ( t That is t The heat source on the collector side at a given time is represented by the above equation, which is the heat source model, specifically a second-order model.

[0104] The above formula is derived based on the collector side. If the case is the emitter side, the formula needs to be adjusted accordingly based on the symmetry characteristics of the collector and emitter.

[0105] A general formula can be given on both sides, as follows:

[0106] ;

[0107] In the formula, for t Heat source on side A at time [time] They are respectively t At time 0s, the thermal capacity of the device on side B is... and the heat capacity of the B-side heat sink initial value, For the thermal resistance of the heatsink on side B, All are thermal time constants; where, if A is the collector, then B is the emitter; if A is the emitter, then B is the collector; the device on the B side is the component from the chip to the B side in the IGBT module.

[0108] Step 3: Input the heat source model into the thermal network model on side A to obtain the shell temperature model on side A.

[0109] It should be noted that, taking the collector side as an example again, see [link to relevant documentation]. Figure 7 Substituting the aforementioned heat source model into the collector-side heat network model, that is... i ( tAs an external heating source for the collector side, the collector side can be analyzed separately to obtain the collector side shell temperature model.

[0110] Based on Kirchhoff's current law and Kirchhoff's voltage law, we have:

[0111] ;

[0112] In the formula, T hc ( t )for t The collector-side case temperature is constantly changing. for t The temperature difference between the chip junction temperature and the ambient temperature at all times.

[0113] After rearranging the above formula, we get:

[0114] .

[0115] The above equation is a second-order nonhomogeneous differential equation, and the solution to the equation can be expressed as:

[0116] ;

[0117] In the formula, T hc ( t )for t The collector-side case temperature at any given time, All are coefficients. All are thermal time constants.

[0118] The above formula is derived based on the collector side. If the case is the emitter side, the formula needs to be adjusted accordingly based on the symmetry characteristics of the collector and emitter of the device.

[0119] A general formula can be given on both sides, as follows:

[0120] ;

[0121] In the formula, for t The temperature of the shell on side A at that moment. All are coefficients. All are thermal time constants.

[0122] Step 4: Solve the shell temperature model to determine the monitoring parameters in the shell temperature model that characterize the thermal fatigue aging state of the IGBT module.

[0123] In some embodiments, the process of determining the monitoring parameters may include: solving the general solution of the case temperature model, obtaining parameters that are only related to the thermal resistance and thermal capacity of the device on side A, and parameters that are only related to the thermal resistance and thermal capacity of the heat sink on side A, based on the general solution, and using the obtained parameters as monitoring parameters characterizing the thermal fatigue aging state of the IGBT module.

[0124] Taking the collector side as an example again, the solution to the above differential equation consists of a general solution and a particular solution. The non-homogeneous term on the right-hand side of the equation is generated by the action of the second-order heat source. Therefore, the form of the particular solution is related to the non-homogeneous term. , Its value is related to the thermal resistance and thermal capacity of the emitter side, as well as the equivalent resistance of the collector.

[0125] The general solution term of the above differential equation is related to the second-order model of the collector itself. Solving for the general solution term of the differential equation, its general solution is obtained from the homogeneous terms of the equation:

[0126] ;

[0127] In the formula, the coefficients It can be represented as:

[0128] ;

[0129] Because there is a significant difference in heat capacity between the heat sink and the device, the above coefficient formula can be simplified to:

[0130] ;

[0131] Let be the characteristic roots of the general solution term of the differential equation. According to Vieta's formulas, we have:

[0132] ;

[0133] Therefore, we can solve for:

[0134] ;

[0135] From the above equation, it can be seen that the thermal time constant... Mainly with Related, thermal time constant Mainly with The correlation allows us to determine the thermal time constant. and The thermal time constant can be used as a monitoring parameter to characterize the thermal fatigue aging state of IGBT modules. and It can be used not only for detecting the aging status of single-chip press-fit IGBT modules, but also to reasonably reflect the thermal fatigue status of multi-chip IGBT modules with thermal-fluid coupling.

[0136] The above method treats the interaction between the emitter side and the collector side during heat dissipation as an equivalent heat source, constructs a thermal network model of the press-fit IGBT module during the cooling process, solves the heat source model based on the thermal network model, and further obtains the case temperature model. In the case temperature model, the monitoring parameters characterizing the thermal fatigue aging state of the press-fit IGBT module are determined, filling the gap in the monitoring parameters for thermal fatigue aging of the press-fit IGBT module.

[0137] To verify the effectiveness of the above method, finite element simulation models under different degrees of fretting wear were established, and thermal fatigue aging monitoring parameters were extracted, as follows:

[0138] A finite element model of a press-fit IGBT module was built based on a simulation platform. The finite element model includes geometric modeling, material parameter selection, and electrothermal coupling. Considering the complexity of the press-fit IGBT module and its chip structure, and the significant differences in the dimensions of the heat sink and devices, the simulation calculation is challenging. To simplify the analysis, the following assumptions are made to the finite element model:

[0139] When performing geometric modeling, structures such as gate pins and housings are ignored, as are fine structures such as chamfers and fillets, to avoid excessively fine meshing that would increase solution time. It is assumed that the physical parameters of each material are constant and do not change with temperature. Modeling of heat sinks and fixtures is omitted, and the function of heat sinks is replaced by setting equivalent convection heat dissipation coefficients on the upper and lower surfaces of the press-fit IGBT module.

[0140] The physical properties of the packaging materials for the press-fit IGBT module are shown in Table 1.

[0141] Table 1 Physical property parameters of compression-fit IGBT module packaging materials

[0142]

[0143] The active region of a press-fit IGBT module experiences the highest current flow and generates the highest temperature. Since the lower molybdenum layer is in direct contact with the active region of the chip, it experiences the greatest stress and is prone to fretting wear failure. Therefore, an air layer is added between the chip's emitter side and the lower molybdenum layer, and the thickness of this air layer is varied to simulate different degrees of fretting wear failure.

[0144] See Figure 8By applying thermocouples at different locations on the surface of the finite element model of the press-fit IGBT module (specifically including the top, bottom, front, left and right sides), multiple sets of cooling process shell temperature curves under different heat dissipation conditions were extracted. The extracted cooling process shell temperature curves were fitted using a fourth-order model (i.e. the shell temperature model mentioned above) to extract the thermal time constant and verify the effectiveness of the method.

[0145] See the fitting results Figures 9-18 ,from Figures 9-12 It can be seen that the emitter side with the added fretting wear layer has a device-related thermal time constant. As the degree of fretting wear worsened, a significant increase occurred; when the fretting wear reached 1 mm, The increase is approximately 61.9% compared to healthy conditions, while the thermal time constant related to the radiator... Although there were changes, the magnitude was small. Furthermore, the thermal time constant related to the device on the collector side without the added fretting wear layer... No significant changes were observed. Figures 13-14 middle, , Compared to the same situation Figures 15-18 The reason why the thermal time constant of the upper surface is large is that, due to the physical structure of the grooves on the front surface of the press-fit IGBT module, its convective heat transfer coefficient is smaller than that of the left and right sides. According to the thermal time constant in heat transfer, the thermal time constant of the upper surface is larger than that of the left and right sides. Figures 15-18 middle , They are almost identical because the physical structures on the left and right sides are completely symmetrical, with the same symmetrical convective heat transfer environment, and their cooling curves almost overlap.

[0146] The above experiments verify that the monitoring parameters determined by the above method, namely , It can be used to monitor the thermal fatigue aging status of press-fit IGBT modules.

[0147] See Figure 19 , Figure 19 This is a block diagram of a monitoring parameter determination device provided in an embodiment of this application. The device is a virtual device that can be loaded and executed by a computer device. The computer device may include the aforementioned monitoring parameter determination device. The device may include a thermal network model module, a heat source model module, a shell temperature model module, and a monitoring parameter determination module. When executing the aforementioned monitoring parameter determination method, it can:

[0148] The thermal network model module constructs a thermal network model of the IGBT module under the cooling process, based on the flow direction of heat generated by the chip in the IGBT module and by using heat sources to characterize the effects of collector-side heat dissipation on emitter-side and emitter-side heat dissipation on collector-side respectively; wherein the IGBT module is a single-chip press-fit type IGBT module.

[0149] The heat source model module solves the heat source model on side A by using the electrothermal analogy theory based on the heat network model; where A is the collector or emitter.

[0150] The shell temperature model module inputs the heat source model into the thermal network model on side A to obtain the shell temperature model on side A.

[0151] The monitoring parameter determination module solves the A-side shell temperature model to determine the monitoring parameters characterizing the thermal fatigue aging state of the IGBT module in the A-side shell temperature model.

[0152] The aforementioned device equates the interaction between the emitter side and the collector side during heat dissipation to a heat source, constructs a thermal network model of the press-fit IGBT module during the cooling process, solves the heat source model based on the thermal network model, and further obtains the case temperature model. In the case temperature model, monitoring parameters characterizing the thermal fatigue aging state of the press-fit IGBT module are determined, filling the gap in thermal fatigue aging monitoring parameters for press-fit IGBT modules.

[0153] See Figure 20 , Figure 20 This is a flowchart of a thermal fatigue aging monitoring method provided in an embodiment of this application. The thermal fatigue aging monitoring method can be executed by a thermal fatigue aging monitoring device, which is similar to a monitoring parameter determination device and can be a terminal device or a server. The thermal fatigue aging monitoring method can include at least the following steps:

[0154] S1) Obtain the case temperature at each moment during the cooling process of the IGBT module.

[0155] It should be noted that the shell temperature can be obtained through thermocouples, similar to the experiments described above.

[0156] S2) Construct the shell temperature curve for the cooling process based on the shell temperature at each moment during the cooling process.

[0157] S3) Based on the shell temperature curve and shell temperature model during the cooling process, fit the values ​​of the monitoring parameters characterizing the thermal fatigue aging state of the IGBT module; wherein, the monitoring parameters are the monitoring parameters determined by the above-mentioned monitoring parameter determination method; the shell temperature model is the shell temperature model obtained by the above-mentioned monitoring parameter determination method.

[0158] Based on the shell temperature curve and shell temperature model during the cooling process, the values ​​of monitoring parameters characterizing the thermal fatigue aging state of the IGBT module are fitted. Specifically, the shell temperature model is used to fit the shell temperature curve during the cooling process and extract the thermal time constant.

[0159] S4) Determine the thermal fatigue aging state of the IGBT module based on the monitored parameter values.

[0160] Taking the bottom case temperature on the collector side as an example, the thermal time constant is obtained by fitting the case temperature cooling curve. , As shown in Table 2.

[0161] Table 2. Correspondence between thermal time constant and degree of aging

[0162]

[0163] As shown in the table above, the thermal time constant A significant increase occurred as the degree of aging progressed, reaching 1mm. The increase is approximately 61.9% compared to healthy conditions, while the thermal time constant... Although there are changes, the magnitude is small. It should be noted that the thermal time constant varies due to differences in mass. The order of magnitude is significantly smaller than that of the thermal time constant. However, this does not affect the comparison of their magnitude of change.

[0164] The above method, based on determined monitoring parameters, can effectively realize the thermal fatigue aging monitoring of press-fit IGBT modules, filling the gap in thermal fatigue aging monitoring of press-fit IGBT modules. It is applicable to the thermal fatigue aging monitoring of press-fit IGBT modules in high-power grid-connected and grid-connected converters.

[0165] See Figure 21 , Figure 21 This is a block diagram of a thermal fatigue aging monitoring device provided in an embodiment of this application. The device is a virtual device that can be loaded and executed by a computer device. The computer device may include the aforementioned thermal fatigue aging monitoring device. The device may include an acquisition module, a curve construction module, a fitting module, and a state determination module. When executing the aforementioned thermal fatigue aging monitoring method, it can:

[0166] The module acquires the case temperature at various moments during the cooling process of the IGBT module.

[0167] The curve construction module generates a shell temperature curve for the cooling process based on the shell temperature at various times during the cooling process.

[0168] The fitting module fits the values ​​of monitoring parameters characterizing the thermal fatigue aging state of the IGBT module based on the cooling process shell temperature curve and shell temperature model; wherein, the monitoring parameters are the monitoring parameters determined by the above-mentioned monitoring parameter determination method; the shell temperature model is the shell temperature model obtained by the above-mentioned monitoring parameter determination method.

[0169] The status determination module determines the thermal fatigue aging status of the IGBT module based on the monitored parameter values.

[0170] The above-mentioned device can effectively monitor the thermal fatigue aging of press-fit IGBT modules based on the determined monitoring parameters, filling the gap in thermal fatigue aging monitoring of press-fit IGBT modules. It is suitable for monitoring the thermal fatigue aging of press-fit IGBT modules in high-power grid-connected and grid-connected converters.

[0171] This application also relates to a computer-readable storage medium that stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a method for determining monitoring parameters or a method for monitoring thermal fatigue aging.

[0172] This application also relates to a computer device including one or more processors and one or more memories, wherein one or more programs are stored in one or more memories and configured to be executed by one or more processors, and the one or more programs include instructions for performing a monitoring parameter determination method or a thermal fatigue aging monitoring method.

[0173] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0174] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0175] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0176] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0177] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A method for determining monitoring parameters, characterized in that, include: Based on the heat flow direction generated by the chip in the IGBT module, the boundary line of the heat flow path is determined. The boundary line is used as the starting point of the model to construct an initial thermal network model of the IGBT module under the cooling process. The components in the initial thermal network model are simplified, and heat sources are used to characterize the influence of collector-side heat dissipation on emitter-side and emitter-side heat dissipation on collector-side, respectively, to obtain a new thermal network model. The new thermal network model is used as the thermal network model of the IGBT module under the cooling process. Using electrothermal analogy theory, the heat dissipation process in the thermal network model of the IGBT module during the cooling process is equivalent to a series connection of a DC power supply and a resistor. Side A is equivalent to a resistor, and the heat source in the thermal network model of the IGBT module during the cooling process is equivalent to a voltage source. Based on the equivalent thermal network model, the three-element method is used to obtain the heat source model of side A; where the heat source model of side A is... , Let A be the heat source on side A at time t. The thermal capacities of device B at time t=0s are respectively and the heat capacity of the B-side heat sink initial value, For the thermal resistance of the heatsink on side B, All are thermal time constants; if A is the collector, then B is the emitter; if A is the emitter, then B is the collector; the device on side B is the component from the chip to side B in the IGBT module; By incorporating the heat source model on side A into the thermal network model on side A, the shell temperature model on side A is obtained. Find the general solution term of the A-side unpacking temperature model. Based on the general solution term, obtain parameters that are only related to the thermal resistance and thermal capacity of the A-side device, as well as parameters that are only related to the thermal resistance and thermal capacity of the A-side heat sink. Use the obtained parameters as monitoring parameters to characterize the thermal fatigue aging state of the IGBT module. Here, the A-side device is the component in the IGBT module that connects the chip to the A-side.

2. The method according to claim 1, characterized in that, The shell temperature model for side A is: ； In the formula, Let be the shell temperature on side A at time t. All are coefficients. All are thermal time constants.

3. A device for determining monitoring parameters, characterized in that, include: The thermal network model module constructs a thermal network model of the IGBT module under the cooling process, based on the flow direction of heat generated by the chip in the IGBT module and by using heat sources to characterize the influence of collector-side heat dissipation on emitter-side and emitter-side heat dissipation on collector-side respectively. The heat source model module solves the heat source model on side A using the electrothermal analogy theory, based on the heat network model; where A is the collector or emitter. The shell temperature model module inputs the heat source model on side A into the thermal network model on side A to obtain the shell temperature model on side A. The monitoring parameter determination module solves the A-side shell temperature model to determine the monitoring parameters characterizing the thermal fatigue aging state of the IGBT module in the A-side shell temperature model. The monitoring parameters are those determined by the method described in any one of claims 1 to 2; the A-side shell temperature model is the A-side shell temperature model obtained by the method described in any one of claims 1 to 2.

4. A method for monitoring thermal fatigue aging, characterized in that, include: Obtain the case temperature at various moments during the cooling process of the IGBT module; Based on the shell temperature at each moment during the cooling process, construct the shell temperature curve for the cooling process; Based on the shell temperature curve and shell temperature model during the cooling process, values ​​of monitoring parameters characterizing the thermal fatigue aging state of the IGBT module are fitted; wherein, the monitoring parameters are the monitoring parameters determined by the method described in any one of claims 1 to 2; and the shell temperature model is the shell temperature model obtained by the method described in any one of claims 1 to 2. The thermal fatigue aging state of the IGBT module is determined based on the monitored parameter values.

5. A thermal fatigue aging monitoring device, characterized in that, include: The module acquires the case temperature at various moments during the cooling process of the IGBT module. The curve construction module constructs a shell temperature curve for the cooling process based on the shell temperature at various moments during the cooling process. The fitting module fits the values ​​of monitoring parameters characterizing the thermal fatigue aging state of the IGBT module based on the shell temperature curve and shell temperature model during the cooling process; wherein the monitoring parameters are the monitoring parameters determined by the method described in any one of claims 1 to 2; and the shell temperature model is the shell temperature model obtained by the method described in any one of claims 1 to 2. The status determination module determines the thermal fatigue aging status of the IGBT module based on the monitored parameter values.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform the method of any one of claims 1 to 2, 4.

7. A computer device, characterized in that, include: One or more processors and one or more memories, one or more programs stored in one or more memories and configured to be executed by one or more processors, the one or more programs including instructions for performing the method of any one of claims 1 to 2, 4.

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