Method and system for measuring junction temperature and thermal resistance of MOSFET (Metal Oxide Semiconductor Field Effect Transistor) power module

Abstract

The invention discloses a method and a system for measuring junction temperature and thermal resistance of an MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) power module, and relates to the technical field of semiconductor device junction temperature measurement, and the method comprises the steps: heating the MOSFET power module which is not connected in parallel with a freewheeling diode until the internal junction temperature reaches a specified temperature, obtaining the voltage drop of a body diode at different junction temperatures, and obtaining the relationship between the voltage drop of the body diode and the internal junction temperature; controlling an MOSFET power module which is not connected in parallel with a freewheeling diode to heat, and obtaining a surface shell temperature and a body diode voltage drop to obtain a relationship between an internal junction temperature and the surface shell temperature; drain-source voltage, drain-source current and surface shell temperature of the MOSFET power module connected in parallel with the freewheeling diode in a normal working state are obtained, the internal junction temperature of the power module is determined according to the relation between the internal junction temperature and the surface shell temperature, and the junction-to-case thermal resistance value of the power module is obtained according to a junction-to-case thermal resistance theoretical formula. The problems that the junction temperature of the MOSFET power module cannot be monitored in real time and the thermal resistance cannot be measured are solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device junction temperature measurement technology, and in particular to a method and system for measuring the junction temperature and thermal resistance of a MOSFET power module. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] For MOSFET power modules without a parallel freewheeling diode, a body diode V can be used. SD The junction temperature is measured by the temperature-sensitive electrical parameter method (T), which involves heating the forward channel and measuring the junction voltage of the parasitic diode in the reverse direction to obtain its temperature-sensitive parameters and junction temperature.

[0004] Due to the current capacity requirements in practical applications, MOSFETs are often packaged with anti-parallel freewheeling diodes to form MOSFET power modules. The principle of MOSFET power modules ensures that in reverse current flow only through the anti-parallel freewheeling diode and not through the MOSFET body diode, ultimately leading to inaccurate junction temperature test results. Furthermore, the use of a body diode V... SD When measuring junction temperature using the temperature-sensitive electrical parameter method (T), a small test current is required to estimate the junction temperature, making it unsuitable for online monitoring. For MOSFET power modules with parallel freewheeling diodes, their junction-to-case thermal resistance cannot be tested, thus their heat dissipation capacity cannot be determined.

[0005] In addition, existing technologies use the drain-source voltage (V) in the MOSFET saturation region as a basis. DS ) and drain-source current (I DS ) is used as a temperature parameter, by establishing V DS -I DS -T j Three-dimensional curve cluster, reverse lookup of junction temperature T j However, this method requires complex equipment such as pulse voltage sources and oscilloscopes, and the pulse width needs to be strictly controlled to prevent self-heating. The set pulse width and duty cycle are not specified to prevent self-heating, and the establishment of V... DS -I DS -T j Three-dimensional curve clusters need to undergo different V... DS The I below DS and T j Measurements of different V DS Different self-heating effects can cause measurement errors. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a method and system for measuring the junction temperature and thermal resistance of a MOSFET power module, effectively resolving the problems of the inability to monitor the junction temperature and measure the thermal resistance of a parallel freewheeling diode MOSFET power module in real time.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for measuring the junction temperature and thermal resistance of a MOSFET power module, comprising: Heat the MOSFET power module without parallel freewheeling diodes until the internal junction temperature reaches a specified temperature and stabilizes. Obtain the body diode voltage drop at different junction temperatures, and thus obtain the relationship between body diode voltage drop and internal junction temperature. The heat generation of the MOSFET power module without parallel freewheeling diode is controlled and the surface case temperature and corresponding body diode voltage drop after the temperature stabilizes are obtained. Based on the relationship between body diode voltage drop and internal junction temperature, the relationship between internal junction temperature and surface case temperature is obtained. The surface case temperature of the MOSFET power module with parallel freewheeling diodes is obtained under normal operating conditions. Based on the relationship between the internal junction temperature and the surface case temperature, the internal junction temperature of the power module is determined. Obtain the drain-source voltage and drain-source current of the MOSFET power module with parallel freewheeling diodes under normal operating conditions, and then use this information to obtain the junction-to-case thermal resistance value of the power module based on the junction-to-case thermal resistance theory formula.

[0008] As an alternative implementation, the relationship between internal junction temperature and surface case temperature is determined by constructing a body diode voltage drop-internal junction temperature measurement model for a MOSFET power module without a parallel freewheeling diode. Specifically: The body diode voltage drop-internal junction temperature measurement model of a MOSFET power module without a parallel freewheeling diode includes a gate voltage module, a test current module, a high-temperature chamber, and a temperature control platform. The MOSFET power module without a parallel freewheeling diode is placed inside the high-temperature chamber. The temperature of the high-temperature chamber is controlled to heat the MOSFET power module without a parallel freewheeling diode. The internal junction temperature is monitored through the temperature control platform until the internal junction temperature reaches the specified temperature and stabilizes. At the same time, the body diode voltage drop is measured at multiple temperature points, thereby obtaining the relationship between the body diode voltage drop and the internal junction temperature. A MOSFET power module without a parallel freewheeling diode is heated by applying current at room temperature. After the internal and external temperatures of the module stabilize, the temperature of the outer casing directly below the module chip and the corresponding body diode voltage drop are measured. The internal junction temperature is derived based on the relationship between the body diode voltage drop and the internal junction temperature, thereby determining the relationship between the internal junction temperature and the surface case temperature at room temperature.

[0009] As an alternative implementation, the gate voltage power supply of the gate voltage module provides a negative gate voltage to the MOSFET power module without a parallel freewheeling diode, enabling it to operate in body diode mode; the constant current source of the test current module provides a small current to the MOSFET power module without a parallel freewheeling diode and monitors the body diode voltage drop.

[0010] As an alternative implementation, the surface case temperature is measured by a temperature sensor mounted on the substrate below the MOSFET power module.

[0011] As an alternative implementation, based on the surface case temperature T of the power module c The internal junction temperature T of the power module j And the drain-source voltage V and drain-source current I, according to the junction-shell thermal resistance theory formula R=(T j -T c The junction-shell thermal resistance of the power module is obtained by calculating (V×I) / (V×I).

[0012] In a second aspect, the present invention provides a measurement system for junction temperature and thermal resistance of a MOSFET power module, comprising: a MOSFET power module and a load circuit, a drive circuit and a temperature calculation and control system connected to the MOSFET power module; The temperature calculation and control system is used to control the drive circuit and load circuit to make the MOSFET power module work normally, obtain the drain-source voltage, drain-source current and surface case temperature under normal working conditions, obtain the internal junction temperature of the power module according to the relationship between the surface case temperature and the internal junction temperature and the surface case temperature, and obtain the junction-case thermal resistance value of the power module according to the drain-source voltage and drain-source current using the junction-case thermal resistance theory formula.

[0013] As an alternative implementation, the process of determining the relationship between internal junction temperature and surface case temperature includes: heating the MOSFET power module without a parallel freewheeling diode until the internal junction temperature reaches a specified temperature and stabilizes, obtaining the body diode voltage drop at different junction temperatures, thereby obtaining the relationship between body diode voltage drop and internal junction temperature; controlling the MOSFET power module without a parallel freewheeling diode to heat up and obtaining the surface case temperature and corresponding body diode voltage drop after temperature stabilization, thereby obtaining the relationship between internal junction temperature and surface case temperature based on the relationship between body diode voltage drop and internal junction temperature.

[0014] As an alternative implementation, the relationship between internal junction temperature and surface case temperature is determined by constructing a body diode voltage drop-internal junction temperature measurement model for a MOSFET power module without a parallel freewheeling diode. Specifically: The body diode voltage drop-internal junction temperature measurement model of a MOSFET power module without a parallel freewheeling diode includes a gate voltage module, a test current module, a high-temperature chamber, and a temperature control platform. The MOSFET power module without a parallel freewheeling diode is placed inside the high-temperature chamber. The temperature of the high-temperature chamber is controlled to heat the MOSFET power module without a parallel freewheeling diode. The internal junction temperature is monitored through the temperature control platform until the internal junction temperature reaches the specified temperature and stabilizes. At the same time, the body diode voltage drop is measured at multiple temperature points, thereby obtaining the relationship between the body diode voltage drop and the internal junction temperature. A MOSFET power module without a parallel freewheeling diode is heated by applying current at room temperature. After the internal and external temperatures of the module stabilize, the temperature of the outer casing directly below the module chip and the corresponding body diode voltage drop are measured. The internal junction temperature is derived based on the relationship between the body diode voltage drop and the internal junction temperature, thereby determining the relationship between the internal junction temperature and the surface case temperature at room temperature.

[0015] As an alternative implementation, the gate voltage power supply of the gate voltage module provides a negative gate voltage to the MOSFET power module without a parallel freewheeling diode, enabling it to operate in body diode mode; the constant current source of the test current module provides a small current to the MOSFET power module without a parallel freewheeling diode and monitors the body diode voltage drop.

[0016] As an alternative implementation, based on the surface case temperature T of the power module c The internal junction temperature T of the power module j And the drain-source voltage V and drain-source current I, according to the junction-shell thermal resistance theory formula R=(T j -T c The junction-shell thermal resistance of the power module is obtained by calculating (V×I) / (V×I).

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes a method and system for measuring the junction temperature and thermal resistance of a MOSFET power module. By heating and controlling the heat generation process of a MOSFET power module without a parallel freewheeling diode, the relationship between the body diode voltage drop and the internal junction temperature, and the relationship between the internal junction temperature and the surface case temperature, are determined. Based on the drain-source voltage, drain-source current, and surface case temperature of a MOSFET power module with a parallel freewheeling diode under normal operating conditions, the internal junction temperature and the junction-to-case thermal resistance of the power module are determined. This effectively solves the problem of not being able to measure the MOSFET junction temperature online for MOSFET power modules with anti-parallel freewheeling diodes, and allows for the testing of the junction-to-case thermal resistance of MOSFET power modules with parallel freewheeling diodes. The implementation method is simple, easy to implement, and suitable for engineering applications; the testing principle is simple, with no complex circuit or software requirements, and has low dependence on measurement equipment and programs.

[0018] Compared with existing V based on MOSFET saturation region DS and I DS As a temperature parameter, by establishing V DS -I DS -T j The methods for reverse-engineering junction temperature using three-dimensional curve clusters differ. This invention establishes the body diode voltage drop V... F -Internal junction temperature T j The relationship curve, combined with the internal junction temperature T j - Surface shell temperature T c The junction temperature is derived from the case temperature using the relationship curve. This avoids the equipment complexity and self-heating effects associated with pulse measurements, requiring only a constant current source, gate voltage control, and a temperature sensor. The equipment is simple and more suitable for engineering applications. This application verifies the consistency of temperature distribution between non-parallel and parallel diode modules through simulation (temperature difference of only 0.4℃), demonstrating the model's versatility. Existing technologies lack verification of this type of structure.

[0019] This invention provides a pulse-free, simple, and online-implementable method for measuring junction temperature and thermal resistance. By combining modeling and simulation, the reliability and engineering applicability of the measurement are improved. For the first time, a basic temperature rise model is proposed using a non-parallel diode module, and this model is extended to the actual junction temperature and thermal resistance measurement of diode modules, thus possessing stronger versatility and engineering applicability.

[0020] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a schematic diagram illustrating the basic principle of measuring the internal body diode voltage drop and internal junction temperature of a MOSFET power module without a parallel freewheeling diode, as provided in Embodiment 1 of the present invention. Figure 2 This is the relationship curve between the internal junction temperature and the surface shell temperature under normal temperature conditions provided in Embodiment 1 of the present invention; Figure 3 The MOSFET power module model with parallel freewheeling diode provided in Embodiment 1 of the present invention and its substrate temperature when the upper bridge is working; wherein, (a) is the MOSFET power module model with parallel freewheeling diode, and (b) is the substrate temperature; Figure 4 The temperature of the parallel chip in the bridge when the MOSFET power module with the parallel freewheeling diode provided in Embodiment 1 of the present invention is in operation. Figure 5 The model of the MOSFET power module without a parallel freewheeling diode on the upper bridge and the substrate temperature when the upper bridge is working are provided in Embodiment 1 of the present invention; wherein, (a) is the MOSFET power module model without a parallel freewheeling diode on the upper bridge and (b) is the substrate temperature; Figure 6 The temperature of the parallel chip on the upper bridge when the MOSFET power module without a freewheeling diode on the upper bridge is in operation, as provided in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram illustrating the basic principle of junction temperature and thermal resistance measurement of a MOSFET power module with a parallel freewheeling diode provided in Embodiment 1 of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0027] Example 1 This embodiment provides a method for measuring the junction temperature and thermal resistance of a MOSFET power module, including: Heat the MOSFET power module without parallel freewheeling diodes until the internal junction temperature reaches a specified temperature and stabilizes. Obtain the body diode voltage drop at different junction temperatures, and thus obtain the relationship between body diode voltage drop and internal junction temperature. The heat generation of the MOSFET power module without parallel freewheeling diode is controlled and the surface case temperature and corresponding body diode voltage drop after the temperature stabilizes are obtained. Based on the relationship between body diode voltage drop and internal junction temperature, the relationship between internal junction temperature and surface case temperature is obtained. The surface case temperature of the MOSFET power module with parallel freewheeling diodes is obtained under normal operating conditions. Based on the relationship between the internal junction temperature and the surface case temperature, the internal junction temperature of the power module is determined. Obtain the drain-source voltage and drain-source current of the MOSFET power module with parallel freewheeling diodes under normal operating conditions, and then use this information to obtain the junction-to-case thermal resistance value of the power module based on the junction-to-case thermal resistance theory formula.

[0028] like Figure 1 The diagram illustrates the basic principle of measuring the body diode voltage drop and internal junction temperature within a MOSFET power module without a parallel freewheeling diode. It includes a gate voltage module, a test current module, a high-temperature chamber, and a temperature control platform. The MOSFET power module without a parallel freewheeling diode is placed inside the high-temperature chamber. The MOSFET power module without a parallel freewheeling diode refers to the bonding wire bypassing the freewheeling diode and bonding from the DBC substrate to the MOSFET.

[0029] Among them, the gate voltage module provides a negative gate voltage to the DUT, enabling it to operate in the body diode state; The constant current source of the test current module provides a small current I to the DUT in the high-temperature chamber. F And monitor the body diode voltage drop V F ; The high-temperature chamber temperature is controlled to heat the MOSFET power module without a parallel freewheeling diode, and the temperature control platform monitors the DUT temperature to ensure that the DUT junction temperature reaches the specified temperature and stabilizes; simultaneously, the body diode voltage drop V is measured at multiple temperature points. F Thus, the body diode voltage drop V is obtained. F -Internal junction temperature T j The relationship curve.

[0030] A MOSFET power module without a parallel freewheeling diode is heated by applying current at room temperature. After the internal and external temperatures of the module stabilize, the temperature of the outer casing directly below the module chip is measured, as well as the corresponding MOSFET body diode voltage drop. The result is then calculated based on the body diode voltage drop V. F -Internal junction temperature T j The relationship curve was used to derive the internal junction temperature, and from this, the internal junction temperature T under normal temperature conditions was plotted. j - Surface shell temperature T c Relationship curves, such as Figure 2 As shown.

[0031] like Figures 3-6As shown, MOSFET power module models with and without parallel freewheeling diodes are established. Only the number and length of the upper bridge bonding wires are changed in both models. In the MOSFET power module model without parallel freewheeling diodes, the upper bridge bonding wires bypass the freewheeling diodes and bond to the MOSFETs via the DBC, ensuring that the modules have the same external conditions during actual operation.

[0032] The temperature distribution of the module during bridge operation was analyzed. In both simulations, the chip power consumption was the same, and the locations of the maximum junction temperature and maximum case temperature were the same, with a temperature difference of only 0.4℃. Therefore, the internal junction temperature-surface case temperature relationship model obtained for the MOSFET power module without a parallel freewheeling diode can be applied to actual MOSFET power modules with a parallel freewheeling diode.

[0033] like Figure 7 The diagram shows the basic principle of a MOSFET power module junction temperature and thermal resistance measurement system with parallel freewheeling diodes. It mainly includes a temperature calculation and control system, a drive circuit, a load circuit, and a temperature sensor.

[0034] Specifically, the MOSFET power module is made to operate normally by controlling the drive circuit and the load circuit, the drain-source voltage V and drain-source current I under normal operating conditions are collected, and the surface case temperature T of the power module is measured by a temperature sensor located on the substrate below the power module. c ; Therefore, the internal junction temperature T of the power module is obtained from the relationship curve between the internal junction temperature and the surface case temperature. j To prevent excessively high junction temperatures from affecting the normal operation of the module, the junction-shell thermal resistance is calculated using the theoretical formula R=(T j -T c The junction-to-shell thermal resistance of the power module is obtained by calculating (V×I) / (V×I).

[0035] Example 2 This embodiment provides a system for measuring the junction temperature and thermal resistance of a MOSFET power module, including: a MOSFET power module and a load circuit, a drive circuit, and a temperature calculation and control system connected to the MOSFET power module; The temperature calculation and control system is used to control the drive circuit and load circuit to make the MOSFET power module work normally, obtain the drain-source voltage, drain-source current and surface case temperature under normal working conditions, obtain the internal junction temperature of the power module according to the relationship between the surface case temperature and the internal junction temperature and the surface case temperature, and obtain the junction-case thermal resistance value of the power module according to the drain-source voltage and drain-source current using the junction-case thermal resistance theoretical formula. In this embodiment, the process of determining the relationship between the internal junction temperature and the surface case temperature includes: heating the MOSFET power module without a parallel freewheeling diode until the internal junction temperature reaches a specified temperature and stabilizes, obtaining the body diode voltage drop at different junction temperatures, thereby obtaining the relationship between the body diode voltage drop and the internal junction temperature; controlling the MOSFET power module without a parallel freewheeling diode to heat up and obtaining the surface case temperature and the corresponding body diode voltage drop after the temperature stabilizes, thereby obtaining the relationship between the internal junction temperature and the surface case temperature based on the relationship between the body diode voltage drop and the internal junction temperature.

[0036] In this embodiment, the relationship between the internal junction temperature and the surface case temperature is determined by constructing a body diode voltage drop-internal junction temperature measurement model for a MOSFET power module without a parallel freewheeling diode. Specifically: The body diode voltage drop-internal junction temperature measurement model of a MOSFET power module without a parallel freewheeling diode includes a gate voltage module, a test current module, a high-temperature chamber, and a temperature control platform. The MOSFET power module without a parallel freewheeling diode is placed inside the high-temperature chamber. The temperature of the high-temperature chamber is controlled to heat the MOSFET power module without a parallel freewheeling diode. The internal junction temperature is monitored through the temperature control platform until the internal junction temperature reaches the specified temperature and stabilizes. At the same time, the body diode voltage drop is measured at multiple temperature points, thereby obtaining the relationship between the body diode voltage drop and the internal junction temperature. A MOSFET power module without a parallel freewheeling diode is heated by applying current at room temperature. After the internal and external temperatures of the module stabilize, the temperature of the outer casing directly below the module chip and the corresponding body diode voltage drop are measured. The internal junction temperature is derived based on the relationship between the body diode voltage drop and the internal junction temperature, thereby determining the relationship between the internal junction temperature and the surface case temperature at room temperature.

[0037] In this embodiment, the gate voltage power supply of the gate voltage module provides a negative gate voltage to the MOSFET power module without a parallel freewheeling diode, making it operate in the body diode state; the constant current source of the test current module provides a small current to the MOSFET power module without a parallel freewheeling diode and monitors the body diode voltage drop.

[0038] In this embodiment, based on the surface temperature T of the power module c The internal junction temperature T of the power module j And the drain-source voltage V and drain-source current I, according to the junction-shell thermal resistance theory formula R=(T j -T c The junction-shell thermal resistance of the power module is obtained by calculating (V×I) / (V×I).

[0039] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for measuring the junction temperature and thermal resistance of a MOSFET power module, characterized in that, include: Heat the MOSFET power module without parallel freewheeling diodes until the internal junction temperature reaches a specified temperature and stabilizes. Obtain the body diode voltage drop at different junction temperatures, and thus obtain the relationship between body diode voltage drop and internal junction temperature. The heat generation of the MOSFET power module without parallel freewheeling diode is controlled and the surface case temperature and corresponding body diode voltage drop after the temperature stabilizes are obtained. Based on the relationship between body diode voltage drop and internal junction temperature, the relationship between internal junction temperature and surface case temperature is obtained. The surface case temperature of the MOSFET power module with parallel freewheeling diodes is obtained under normal operating conditions. Based on the relationship between the internal junction temperature and the surface case temperature, the internal junction temperature of the power module is determined. Obtain the drain-source voltage and drain-source current of the MOSFET power module with parallel freewheeling diodes under normal operating conditions, and then use this information to obtain the junction-to-case thermal resistance value of the power module based on the junction-to-case thermal resistance theory formula.

2. The method for measuring the junction temperature and thermal resistance of a MOSFET power module as described in claim 1, characterized in that, The relationship between internal junction temperature and surface case temperature was determined by constructing a body diode voltage drop-internal junction temperature measurement model for a MOSFET power module without parallel freewheeling diodes. Specifically: The body diode voltage drop-internal junction temperature measurement model of a MOSFET power module without a parallel freewheeling diode includes a gate voltage module, a test current module, a high-temperature chamber, and a temperature control platform. The MOSFET power module without a parallel freewheeling diode is placed inside the high-temperature chamber. The temperature of the high-temperature chamber is controlled to heat the MOSFET power module without a parallel freewheeling diode. The internal junction temperature is monitored through the temperature control platform until the internal junction temperature reaches the specified temperature and stabilizes. At the same time, the body diode voltage drop is measured at multiple temperature points, thereby obtaining the relationship between the body diode voltage drop and the internal junction temperature. A MOSFET power module without a parallel freewheeling diode is heated by applying current at room temperature. After the internal and external temperatures of the module stabilize, the temperature of the outer casing directly below the module chip and the corresponding body diode voltage drop are measured. The internal junction temperature is derived based on the relationship between the body diode voltage drop and the internal junction temperature, thereby determining the relationship between the internal junction temperature and the surface case temperature at room temperature.

3. The method for measuring the junction temperature and thermal resistance of a MOSFET power module as described in claim 2, characterized in that, The gate voltage module provides a negative gate voltage to the MOSFET power module without a parallel freewheeling diode, enabling it to operate in body diode mode; the constant current source of the test current module provides a small current to the MOSFET power module without a parallel freewheeling diode and monitors the body diode voltage drop.

4. The method for measuring the junction temperature and thermal resistance of a MOSFET power module as described in claim 1, characterized in that, The surface case temperature is measured by a temperature sensor mounted on the substrate below the MOSFET power module.

5. The method for measuring the junction temperature and thermal resistance of a MOSFET power module as described in claim 1, characterized in that, Based on the surface temperature T of the power module c The internal junction temperature T of the power module j And the drain-source voltage V and drain-source current I, according to the junction-shell thermal resistance theory formula R=(T j -T c The junction-shell thermal resistance of the power module is obtained by calculating (V×I) / (V×I).

6. A system for measuring the junction temperature and thermal resistance of a MOSFET power module, characterized in that, include: MOSFET power module and load circuit, drive circuit and temperature calculation and control system connected to MOSFET power module; The temperature calculation and control system is used to control the drive circuit and load circuit to make the MOSFET power module work normally, obtain the drain-source voltage, drain-source current and surface case temperature under normal working conditions, obtain the internal junction temperature of the power module according to the relationship between the surface case temperature and the internal junction temperature and the surface case temperature, and obtain the junction-case thermal resistance value of the power module according to the drain-source voltage and drain-source current using the junction-case thermal resistance theory formula.

7. The measurement system for junction temperature and thermal resistance of a MOSFET power module as described in claim 6, characterized in that, The process of determining the relationship between internal junction temperature and surface case temperature includes: heating the MOSFET power module without a parallel freewheeling diode until the internal junction temperature reaches a specified temperature and stabilizes, obtaining the body diode voltage drop at different junction temperatures, and thus obtaining the relationship between body diode voltage drop and internal junction temperature; controlling the MOSFET power module without a parallel freewheeling diode to heat up and obtaining the surface case temperature and corresponding body diode voltage drop after the temperature stabilizes, and thus obtaining the relationship between internal junction temperature and surface case temperature based on the relationship between body diode voltage drop and internal junction temperature.

8. The measurement system for junction temperature and thermal resistance of a MOSFET power module as described in claim 7, characterized in that, The relationship between internal junction temperature and surface case temperature was determined by constructing a body diode voltage drop-internal junction temperature measurement model for a MOSFET power module without parallel freewheeling diodes. Specifically: The body diode voltage drop-internal junction temperature measurement model of a MOSFET power module without a parallel freewheeling diode includes a gate voltage module, a test current module, a high-temperature chamber, and a temperature control platform. The MOSFET power module without a parallel freewheeling diode is placed inside the high-temperature chamber. The temperature of the high-temperature chamber is controlled to heat the MOSFET power module without a parallel freewheeling diode. The internal junction temperature is monitored through the temperature control platform until the internal junction temperature reaches the specified temperature and stabilizes. At the same time, the body diode voltage drop is measured at multiple temperature points, thereby obtaining the relationship between the body diode voltage drop and the internal junction temperature. A MOSFET power module without a parallel freewheeling diode is heated by applying current at room temperature. After the internal and external temperatures of the module stabilize, the temperature of the outer casing directly below the module chip and the corresponding body diode voltage drop are measured. The internal junction temperature is derived based on the relationship between the body diode voltage drop and the internal junction temperature, thereby determining the relationship between the internal junction temperature and the surface case temperature at room temperature.

9. The measurement system for junction temperature and thermal resistance of a MOSFET power module as described in claim 8, characterized in that, The gate voltage module provides a negative gate voltage to the MOSFET power module without a parallel freewheeling diode, enabling it to operate in body diode mode; the constant current source of the test current module provides a small current to the MOSFET power module without a parallel freewheeling diode and monitors the body diode voltage drop.

10. The measurement system for junction temperature and thermal resistance of a MOSFET power module as described in claim 6, characterized in that, Based on the surface temperature T of the power module c The internal junction temperature T of the power module j And the drain-source voltage V and drain-source current I, according to the junction-shell thermal resistance theory formula R=(T j -T c The junction-shell thermal resistance of the power module is obtained by calculating (V×I) / (V×I).

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