IGBT junction temperature estimation method and device

Abstract

The invention discloses an IGBT junction temperature estimation method and device, and relates to the technical field of IGBTs. The equivalent environment temperature is determined according to the historical actual environment temperature of the IGBT, and the theoretical equivalent junction temperature of the IGBT at the current moment is determined according to the equivalent environment temperature, the historical equivalent temperature of RC network nodes of all orders in an IGBT equivalent four-order RC network, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT. The actual equivalent junction temperature of the IGBT at the current moment is determined according to the theoretical equivalent junction temperature at the current moment, the junction temperature estimation of the IGBT is realized, the actual environment temperature of the IGBT is considered when the junction temperature of the IGBT is estimated, and the junction temperature estimation precision of the IGBT is improved.

Description

Technical Field

[0001] The present invention relates to the field of IGBT technology, and in particular to an IGBT junction temperature estimation method and device. Background Art

[0002] Insulate-Gate Bipolar Transistor (IGBT) is the core power device in power electronic systems. The junction temperature of IGBT is closely related to its working performance, life and reliability. Accurate estimation of IGBT junction temperature is of great significance to improving the reliability of IGBT and extending its service life.

[0003] The current IGBT junction temperature estimation scheme does not consider the actual working environment of the IGBT when estimating the IGBT junction temperature, resulting in large errors and low accuracy in the estimation results. Summary of the invention

[0004] The present invention solves the technical problem of how to improve the estimation accuracy of the IGBT junction temperature by providing an IGBT junction temperature estimation method and device.

[0005] On the one hand, the present invention provides the following technical solutions: A method for estimating an IGBT junction temperature, comprising: Obtaining the actual ambient temperature of the IGBT in history, the equivalent temperature of each order RC network node in the equivalent fourth-order RC network of the IGBT, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT; Determine the equivalent ambient temperature based on the actual ambient temperature in history; Determine the theoretical equivalent junction temperature at the current moment according to the equivalent ambient temperature, the historical equivalent temperature, the theoretical equivalent junction temperature and the output power; The actual equivalent junction temperature of the IGBT at the current moment is determined according to the theoretical equivalent junction temperature at the current moment.

[0006] In some embodiments, the actual ambient temperature in history includes the actual ambient temperature at the N-4th moment, where N is the current moment; The determining of the equivalent ambient temperature according to the historical actual ambient temperature comprises: The actual ambient temperature at the N-4th moment is used as the equivalent ambient temperature.

[0007] In some embodiments, the actual ambient temperature in history includes the actual ambient temperature at the N-5th moment, where N is the current moment; The determining of the equivalent ambient temperature according to the historical actual ambient temperature comprises: Obtaining the actual equivalent junction temperature at the N-5th and N-4th moments; The equivalent ambient temperature is determined according to the actual ambient temperature at the N-5th moment and the actual equivalent junction temperatures at the N-5th and N-4th moments.

[0008] In some embodiments, determining the equivalent ambient temperature according to the actual ambient temperature at the N-5th moment and the actual equivalent junctions at the N-5th and N-4th moments includes: According to the formula Determine the equivalent ambient temperature; wherein, is the equivalent ambient temperature, is the actual ambient temperature at the N-5th moment, is the actual equivalent junction temperature at the N-4th moment, is the actual equivalent junction temperature at the N-5th moment, is the heat loss coefficient due to ambient temperature change.

[0009] In some implementations, determining the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment includes: The theoretical equivalent junction temperature at the current moment is used as the actual equivalent junction temperature at the current moment.

[0010] In some implementations, determining the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment includes: Obtaining the output power at the current moment and the flow rate of cooling water in the liquid cooling system of the IGBT; The actual equivalent junction temperature at the current moment is determined according to the theoretical equivalent junction temperature at the current moment, the output power, and the flow rate of the cooling water.

[0011] In some implementations, determining the actual equivalent junction temperature at the current moment according to the theoretical equivalent junction temperature at the current moment and the output power and the flow rate of the cooling water includes: Determining the actual equivalent junction temperature at the current moment according to a preset relationship between the actual equivalent junction temperature and the theoretical equivalent junction temperature, the output power, and the flow rate of the cooling water; In the preset relationship, the actual equivalent junction temperature is positively correlated with the theoretical equivalent junction temperature, negatively correlated with the output power, and positively correlated with the flow rate of the cooling water.

[0012] On the other hand, the present invention also provides the following technical solutions: An IGBT junction temperature estimation device, comprising: An acquisition module is used to acquire the actual ambient temperature of the IGBT in history, the equivalent temperature of each RC network node in the equivalent fourth-order RC network of the IGBT, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT; A determination module, used for determining an equivalent ambient temperature according to the historical actual ambient temperature; and for determining the theoretical equivalent junction temperature at a current moment according to the equivalent ambient temperature, the historical equivalent temperature, the theoretical equivalent junction temperature and the output power; And used to determine the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment.

[0013] On the other hand, the present invention also provides the following technical solutions: A computer device comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of any one of the above IGBT junction temperature estimation methods.

[0014] On the other hand, the present invention also provides the following technical solutions: A computer-readable storage medium stores a computer program, wherein the computer program, when executed by a processor, implements the steps of any one of the above-mentioned methods for estimating the junction temperature of an IGBT.

[0015] One or more technical solutions provided by the present invention have at least the following technical effects or advantages: The present invention determines an equivalent ambient temperature according to actual ambient temperatures of the IGBT in history, determines the theoretical equivalent junction temperature of the IGBT at the current moment according to the equivalent ambient temperature, equivalent temperatures of nodes of each order in an equivalent fourth-order RC network of the IGBT in history, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT, determines the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment, realizes the estimation of the junction temperature of the IGBT, and takes the actual ambient temperature of the IGBT into consideration when estimating the junction temperature of the IGBT, thereby improving the accuracy of the estimation of the junction temperature of the IGBT. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0017] Figure 1 Schematic diagram of an IGBT equivalent fourth-order RC network in an embodiment of the present invention; Figure 2 Flow chart of the IGBT junction temperature estimation method according to an embodiment of the present invention; Figure 3 Schematic diagram of a liquid cooling system for an IGBT in an embodiment of the present invention; Figure 4 Schematic diagram of an IGBT junction temperature estimation device in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The embodiment of the present invention solves the technical problem of how to improve the estimation accuracy of the IGBT junction temperature by providing an IGBT junction temperature estimation method and device.

[0019] In order to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0020] The physical structure of IGBT is generally composed of packaging structures such as copper plate, solder layer, liner and substrate. Its basic physical characteristics can be equivalent to the electrical model of resistor and capacitor in parallel. In the embodiment of the present invention, a fourth-order RC parallel network is used to perform electrical modeling on the physical structure of IGBT, and the following is obtained: Figure 1 The equivalent fourth-order RC network of the IGBT shown in the figure replaces the physical structures such as the copper plate, solder layer, liner and substrate. , , , is the resistance, , , , The output power P of the IGBT in the electrical system is added to both ends of the equivalent fourth-order RC network. Figure 1 middle is the theoretical equivalent junction temperature of IGBT, , , , The nodes are first-order RC network nodes, second-order RC network nodes, third-order RC network nodes, and fourth-order RC network nodes. , , , They are the equivalent temperatures of the first-order RC network node, the second-order RC network node, the third-order RC network node, and the fourth-order RC network node. Since the physical structure corresponding to the fourth-order RC network node is in contact with the environment, the equivalent temperature of the fourth-order RC network node is the equivalent ambient temperature of the IGBT. , The initial value is generally 25°C.

[0021] According to Kirchhoff's first law, we can get Figure 1 Mathematical differential model of equivalent fourth-order RC network: ; Where t is time; By time discretizing the mathematical differential model at the current time N, we can obtain the discrete equation: ; In the formula, They are respectively the theoretical equivalent junction temperature at the current moment N and the theoretical equivalent junction temperature at the N-1th moment; , are the equivalent temperature of the first-order RC network node at the Nth moment and the equivalent temperature of the first-order RC network node at the N-1th moment respectively; , are the equivalent temperature of the second-order RC network node at the Nth moment and the equivalent temperature of the second-order RC network node at the N-1th moment respectively; , are the equivalent temperature of the third-order RC network node at the Nth moment and the equivalent temperature of the third-order RC network node at the N-1th moment respectively; is the IGBT output power at the N-1th moment, which is calculated from the voltage and current flowing through the collector and emitter of the IGBT at the N-1th moment; is the sampling time interval.

[0022] Theoretical equivalent junction temperature , equivalent temperature, equivalent ambient temperature The unit is ℃, IGBT output power The unit is W, the sampling time interval The unit is s. , , , , , , , Both can be obtained from the IGBT data sheet.

[0023] The discretized equation can be deduced into a difference equation: ; In the formula, is the theoretical equivalent junction temperature at the N-2th moment; , are the equivalent temperature of the first-order RC network node at the N-2th moment and the equivalent temperature of the first-order RC network node at the N-3th moment respectively; , , They are the equivalent temperature of the second-order RC network node at the N-2th moment, the equivalent temperature of the second-order RC network node at the N-3th moment, and the equivalent temperature of the second-order RC network node at the N-4th moment; , They are the equivalent temperature of the third-order RC network node at the N-3th moment and the equivalent temperature of the third-order RC network node at the N-4th moment, respectively.

[0024] Based on the above difference equation, we can get Figure 2 The IGBT junction temperature estimation method shown includes: Step S1, obtaining the actual ambient temperature of the IGBT in history, the equivalent temperature of each RC network node in the equivalent fourth-order RC network of the IGBT, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT; Step S2, determining an equivalent ambient temperature based on the actual ambient temperature in history; Step S3, determining the theoretical equivalent junction temperature at the current moment according to the equivalent ambient temperature, the historical equivalent temperature, the theoretical equivalent junction temperature and the output power; Step S4, determining the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment.

[0025] In step S1, the historical equivalent temperature includes the equivalent temperature of the first-order RC network node at the N-3th moment and the equivalent temperature at the N-2th moment , the equivalent temperature of the second-order RC network node at the N-4th moment and the equivalent temperature at the N-3th moment , the equivalent temperature of the third-order RC network node at the N-4th moment ; The historical theoretical equivalent junction temperature includes the theoretical equivalent junction temperature at the N-2th moment and the theoretical equivalent junction temperature at the N-1th moment ; The historical output power includes the output power at the N-1th moment .

[0026] It should be noted that the actual ambient temperature, equivalent temperature, theoretical equivalent junction temperature, and output power in history can all be considered known and can be assigned initial values.

[0027] Assume that the actual ambient temperature of the IGBT is T. In some embodiments, the actual ambient temperature in history may include the actual ambient temperature at the N-4th moment. , N is the current moment; step S2 may include: the actual ambient temperature at the N-4th moment As the equivalent ambient temperature . Then the above difference equation becomes: ; Step S3 can calculate the theoretical equivalent junction temperature at the current moment according to the above differential equation The specific process is: the actual ambient temperature at the N-4th moment , the equivalent temperature of the second-order RC network node at the N-4th moment and the equivalent temperature of the third-order RC network node at the N-4th moment Substituting the formula into the difference equation Calculate the equivalent temperature of the third-order RC network node at the N-3th moment ; The equivalent temperature of the first-order RC network node at the N-3th moment , the equivalent temperature of the second-order RC network node at the N-3th moment and the equivalent temperature of the third-order RC network node at the N-3th moment Substituting the formula into the difference equation Calculate the equivalent temperature of the second-order RC network node at the N-2th moment ; The theoretical equivalent junction temperature at the N-2th moment is , the equivalent temperature of the first-order RC network node at the N-2th moment and the equivalent temperature of the second-order RC network node at the N-2th moment Substituting the formula into the difference equation Calculate the equivalent temperature of the first-order RC network node at the N-1th moment ; The output power at the N-1th moment , Theoretical equivalent junction temperature at the N-1th moment and the equivalent temperature of the first-order RC network node at the N-1th moment Substituting the formula into the difference equation Calculate the theoretical equivalent junction temperature at the current moment .

[0028] In some embodiments, step S4 may include: converting the theoretical equivalent junction temperature at the current moment into As the actual equivalent junction temperature at the current moment In this way, the junction temperature estimation of the IGBT is realized, and the actual ambient temperature of the IGBT is taken into consideration when estimating the junction temperature of the IGBT, which can improve the accuracy of the IGBT junction temperature estimation.

[0029] As mentioned above, step S2 can convert the actual ambient temperature at the N-4th moment into As the equivalent ambient temperature However, in the actual working environment of IGBT, the actual ambient temperature sometimes cannot represent the equivalent ambient temperature. In this case, the actual ambient temperature at the N-4th moment is As the equivalent ambient temperature To further improve the accuracy of IGBT junction temperature estimation, in some implementations, the historical actual ambient temperature may also include the actual ambient temperature at the N-5th moment, and step S2 may also include: Obtain the actual equivalent junction temperature at the N-5th and N-4th moments; The equivalent ambient temperature is determined according to the actual ambient temperature at the N-5th moment and the actual equivalent junction temperatures at the N-5th and N-4th moments.

[0030] It should be noted that the actual equivalent junction temperatures at the N-5th and N-4th moments can be considered known and can be assigned initial values.

[0031] In some embodiments, based on the actual ambient temperature at the N-5th moment The equivalent ambient temperature is determined by the actual equivalent junction temperature at the N-5th and N-4th moments. , which can include: According to the formula Determine the equivalent ambient temperature; where, is the actual ambient temperature at the N-5th moment, is the actual equivalent junction temperature at the N-4th moment, is the actual equivalent junction temperature at the N-5th moment, is the heat loss coefficient due to ambient temperature change and is a nonlinear function.

[0032] in, The actual is the change in the actual equivalent junction temperature in history, which is equivalent to correcting the actual ambient temperature at the N-5th moment according to the change in the actual equivalent junction temperature in history. .

[0033] As mentioned above, step S4 can calculate the theoretical equivalent junction temperature at the current moment. As the actual equivalent junction temperature at the current moment However, in the actual working environment of IGBT, there is a liquid cooling system that exchanges heat with IGBT to control the temperature of IGBT, such as Figure 3 As shown in the figure. The increase of cooling water temperature in the liquid cooling system will cause the temperature of IGBT to decrease, that is, the actual equivalent junction temperature of IGBT should be lower than the theoretical equivalent junction temperature. The decrease of cooling water temperature will cause the temperature of IGBT to increase, that is, the actual equivalent junction temperature of IGBT should be higher than the theoretical equivalent junction temperature. Considered as the actual equivalent junction temperature of the IGBT , which will reduce the accuracy of IGBT junction temperature estimation. To further improve the accuracy of IGBT junction temperature estimation, in some implementations, step S4 may also include: Obtain the current IGBT output power and the flow rate of cooling water in the IGBT liquid cooling system; The actual equivalent junction temperature at the current moment is determined according to the theoretical equivalent junction temperature and output power at the current moment and the flow rate of cooling water.

[0034] In some implementations, determining the actual equivalent junction temperature at the current moment according to the theoretical equivalent junction temperature and output power at the current moment, and the flow rate of cooling water may include: Determine the actual equivalent junction temperature at the current moment according to the preset relationship between the actual equivalent junction temperature and the theoretical equivalent junction temperature, the output power, and the flow rate of the cooling water; In the preset relationship, the actual equivalent junction temperature is positively correlated with the theoretical equivalent junction temperature, negatively correlated with the output power, and positively correlated with the flow rate of the cooling water.

[0035] In some implementations, the preset relationship may be: ;in, is the actual equivalent junction temperature at the current moment, is the IGBT output power at the current moment, is the cooling water flow rate, is the density of cooling water, is the specific heat capacity of cooling water, is the temperature change heat loss coefficient of cooling water. In some embodiments, The value range of can be 0.6~0.9. In the formula, It is equivalent to the temperature change of cooling water. When the temperature of cooling water increases, the temperature change is positive, and when the temperature of cooling water decreases, the temperature change is negative. Therefore, the temperature change of cooling water in the liquid cooling system is taken into account when estimating the junction temperature of IGBT, which improves the estimation accuracy of the junction temperature of IGBT.

[0036] like Figure 4 As shown, the embodiment of the present invention also provides an IGBT junction temperature estimation device, including: An acquisition module is used to obtain the actual ambient temperature of the IGBT in history, the equivalent temperature of each RC network node in the equivalent fourth-order RC network of the IGBT, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT; A determination module, used for determining an equivalent ambient temperature according to historical actual ambient temperatures; and for determining the theoretical equivalent junction temperature at the current moment according to the equivalent ambient temperature, the historical equivalent temperature, the theoretical equivalent junction temperature and the output power; And it is used to determine the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment.

[0037] In some embodiments, the historical actual ambient temperature may include the actual ambient temperature at the N-4th moment, where N is the current moment; Determine the module, which can be used specifically for: The actual ambient temperature at the N-4th moment is taken as the equivalent ambient temperature.

[0038] In some embodiments, the historical actual ambient temperature may include the actual ambient temperature at the N-5th moment, where N is the current moment; Determine the module, which can be used specifically for: Obtain the actual equivalent junction temperature at the N-5th and N-4th moments; The equivalent ambient temperature is determined according to the actual ambient temperature at the N-5th moment and the actual equivalent junction temperatures at the N-5th and N-4th moments.

[0039] In some implementations, the determination module may also be used to: According to the formula Determine the equivalent ambient temperature; where, is the equivalent ambient temperature, is the actual ambient temperature at the N-5th moment, is the actual equivalent junction temperature at the N-4th moment, is the actual equivalent junction temperature at the N-5th moment, is the heat loss coefficient due to ambient temperature change.

[0040] In some implementations, the determination module may be specifically configured to: The theoretical equivalent junction temperature at the current moment is taken as the actual equivalent junction temperature at the current moment.

[0041] In some implementations, the determination module may be specifically configured to: Obtain the current output power and the flow rate of cooling water in the IGBT liquid cooling system; The actual equivalent junction temperature at the current moment is determined according to the theoretical equivalent junction temperature and output power at the current moment and the flow rate of cooling water.

[0042] In some implementations, the determination module may also be used to: Determine the actual equivalent junction temperature at the current moment according to the preset relationship between the actual equivalent junction temperature and the theoretical equivalent junction temperature, the output power, and the flow rate of the cooling water; In the preset relationship, the actual equivalent junction temperature is positively correlated with the theoretical equivalent junction temperature, negatively correlated with the output power, and positively correlated with the flow rate of the cooling water.

[0043] Based on the same inventive concept as the above-mentioned IGBT junction temperature estimation method, an embodiment of the present invention also provides a computer device, including a memory, a processor and a computer program stored in the memory, and the processor executes the computer program to implement the steps of any one of the above-mentioned IGBT junction temperature estimation methods.

[0044] Since the computer device introduced in the embodiment of the present invention is a computer device used to implement the IGBT junction temperature estimation method in the embodiment of the present invention, based on the IGBT junction temperature estimation method introduced in the embodiment of the present invention, a person skilled in the art can understand the specific implementation of the computer device in the embodiment of the present invention and its various variations, so how the computer device implements the method in the embodiment of the present invention is not described in detail here. As long as a person skilled in the art implements the computer device used in the IGBT junction temperature estimation method in the embodiment of the present invention, it belongs to the scope of protection of the present invention.

[0045] Based on the same inventive concept as the above-mentioned IGBT junction temperature estimation method, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of any of the above-mentioned IGBT junction temperature estimation methods when executed by a processor.

[0046] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented 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.

[0047] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0048] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0049] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0050] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0051] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for estimating IGBT junction temperature, characterized in that: include: Obtaining the actual ambient temperature of the IGBT in history, the equivalent temperature of each RC network node in the equivalent fourth-order RC network of the IGBT, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT; Determine the equivalent ambient temperature based on the historical actual ambient temperature; Determine the theoretical equivalent junction temperature at the current moment according to the equivalent ambient temperature, the historical equivalent temperature, the theoretical equivalent junction temperature, and the output power; The actual equivalent junction temperature of the IGBT at the current moment is determined according to the theoretical equivalent junction temperature at the current moment.

2. The IGBT junction temperature estimation method according to claim 1, characterized in that: The actual ambient temperature in history includes the actual ambient temperature at the N-4th moment, where N is the current moment; The determining of the equivalent ambient temperature according to the historical actual ambient temperature comprises: The actual ambient temperature at the N-4th moment is used as the equivalent ambient temperature.

3. The IGBT junction temperature estimation method according to claim 1, characterized in that: The actual ambient temperature in history includes the actual ambient temperature at the N-5th moment, where N is the current moment; The determining of the equivalent ambient temperature according to the historical actual ambient temperature comprises: Obtaining the actual equivalent junction temperature at the N-5th and N-4th moments; The equivalent ambient temperature is determined according to the actual ambient temperature at the N-5th moment and the actual equivalent junction temperatures at the N-5th and N-4th moments.

4. The IGBT junction temperature estimation method according to claim 3, characterized in that: The determining the equivalent ambient temperature according to the actual ambient temperature at the N-5th moment and the actual equivalent junctions at the N-5th and N-4th moments includes: According to the formula Determine the equivalent ambient temperature; wherein, is the equivalent ambient temperature, is the actual ambient temperature at the N-5th moment, is the actual equivalent junction temperature at the N-4th moment, is the actual equivalent junction temperature at the N-5th moment, is the heat loss coefficient due to ambient temperature change.

5. The IGBT junction temperature estimation method according to claim 1, characterized in that: The determining the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment includes: The theoretical equivalent junction temperature at the current moment is used as the actual equivalent junction temperature at the current moment.

6. The IGBT junction temperature estimation method according to claim 1, characterized in that: The determining the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment includes: Obtaining the output power at the current moment and the flow rate of cooling water in the liquid cooling system of the IGBT; The actual equivalent junction temperature at the current moment is determined according to the theoretical equivalent junction temperature at the current moment, the output power, and the flow rate of the cooling water.

7. The IGBT junction temperature estimation method according to claim 6, characterized in that: The determining the actual equivalent junction temperature at the current moment according to the theoretical equivalent junction temperature at the current moment and the output power and the flow rate of the cooling water includes: Determining the actual equivalent junction temperature at the current moment according to a preset relationship between the actual equivalent junction temperature and the theoretical equivalent junction temperature, the output power, and the flow rate of the cooling water; In the preset relationship, the actual equivalent junction temperature is positively correlated with the theoretical equivalent junction temperature, negatively correlated with the output power, and positively correlated with the flow rate of the cooling water.

8. An IGBT junction temperature estimation device, characterized in that: include: An acquisition module is used to acquire the actual ambient temperature of the IGBT in history, the equivalent temperature of each RC network node in the equivalent fourth-order RC network of the IGBT, the theoretical equivalent junction temperature of the IGBT and the output power of the IGBT; A determination module, used for determining an equivalent ambient temperature according to the historical actual ambient temperature; and for determining the theoretical equivalent junction temperature at a current moment according to the equivalent ambient temperature, the historical equivalent temperature, the theoretical equivalent junction temperature and the output power; And used to determine the actual equivalent junction temperature of the IGBT at the current moment according to the theoretical equivalent junction temperature at the current moment.

9. A computer device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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