IGBT module junction temperature estimation method and system

Abstract

The invention relates to an IGBT module junction temperature estimation method and system, and the method comprises the following steps: obtaining a performance curve set of an IGBT module under different working conditions, and carrying out the fitting optimization, and obtaining an optimal performance curve set; constructing a transient thermal resistance curve model according to a transient thermal resistance principle, and constructing a second-order Foster thermal network model based on the transient thermal resistance curve model; performing Laplace transformation and discretization processing based on a backward difference method on the second-order Foster thermal network model to obtain a junction temperature estimation model; collecting a phase current instantaneous value, and calculating the total power loss of the IGBT module in real time in combination with the optimal performance curve set; and finally, the junction temperature of the IGBT module is obtained in real time by using the total power loss of the IGBT module obtained through real-time calculation and the junction temperature estimation model, and junction temperature estimation is completed. According to the method, the effect of improving the power loss precision of the IGBT module is achieved by optimizing the performance curve, and then the junction temperature estimation precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, in particular to an IGBT module junction temperature estimation method and system. BACKGROUND

[0002] In refrigeration technology, IGBT power modules are continuously turned on and turned off, resulting in corresponding conduction loss and switching loss, which causes the IGBT module to continuously generate heat, eventually leading to the rise and even fluctuation of the IGBT junction temperature. Due to the difference in the thermal expansion coefficients of the materials in each layer of the IGBT module, the junction temperature fluctuation will cause thermal stress, which in turn will cause the device to fail. In addition, the junction temperature of the IGBT during operation must not exceed its limit temperature (usually 150℃), otherwise the chip will be easily burned out.

[0003] The current prediction method for the junction temperature of the power device wafer is the thermal network model method. The thermal network model method calculates the junction temperature of the IGBT wafer in the IGBT power module based on the loss model of the IGBT power module and the thermal resistance model constructed. The accuracy of the junction temperature estimation depends mainly on the accuracy of the power loss calculation and the accuracy of the thermal resistance model. In actual application, through a large amount of offline data modeling and calibration and a reasonable loss and thermal resistance model modeling method, relatively accurate junction temperature estimation can be achieved. This method does not require any additional hardware cost, has the advantages of fast response speed and good working condition adaptability. For example, the prior art "CN114398809A" discloses an IGBT module junction temperature calculation method considering a heat sink. From the perspective of engineering application, for a large power converter IGBT module with a large change in operating conditions, the coupling of the FWD / IGBT chip in the heat-conducting silicone layer under different operating conditions is obtained through the results of finite element simulation, and then the mathematical expression is obtained. Considering the operation resource overhead and accuracy of the junction temperature estimation, a thermal network mathematical model considering the loss coupling of the IGBT chip and the FWD chip under different operating conditions is given. The mathematical model has a simple structure and small calculation amount, and can realize more accurate real-time response of the dynamic change of the IGBT junction temperature in engineering application. However, this kind of method requires high accuracy of the model, and errors will be generated when obtaining data for modeling through offline experiments, making accurate modeling difficult and prone to errors. In addition, the parameters in the thermal resistance model will be affected when the IGBT power module ages, thereby increasing the error of the junction temperature estimation. SUMMARY

[0004] To overcome the technical problem of insufficient accuracy of the IGBT module junction temperature estimation in the prior art, the present application provides an IGBT module junction temperature estimation method and system.

[0005] To solve the above technical problems, the technical solutions of the present application are as follows: An IGBT module junction temperature estimation method, comprising the following steps: S1: Obtain the set of performance curves of the IGBT module under different operating conditions and perform fitting optimization to obtain the optimal set of performance curves; the set of performance curves includes at least: IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve and IGBT module parasitic diode forward voltage drop curve. S2: Construct a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and construct a second-order Foster thermal network model based on the transient thermal resistance curve model; perform Laplace transform and discretization processing based on the backward difference method on the second-order Foster thermal network model to finally obtain the junction temperature estimation model of the IGBT module. S3: Real-time acquisition of instantaneous phase current values, and real-time calculation of the total power loss of the IGBT module in conjunction with the optimal performance curve set; S4: Using the total power loss of the IGBT module calculated in real time and the junction temperature of the IGBT module obtained in real time by the junction temperature estimation model, the junction temperature is estimated.

[0006] Preferably, in step S2, the transient thermal resistance curve model expression is:

[0007] in, The junction-to-shell thermal resistance varies over time. For time variables, , These are the first and second thermal resistance parameters of the thermal mesh model, respectively. , These are the first and second heat capacity parameters of the thermal mesh model, respectively.

[0008] Preferably, a second-order Foster thermal network model is constructed based on the transient thermal resistance curve model. The second-order Foster thermal network model is then subjected to Laplace transform and discretization based on the backward difference method to obtain the junction temperature estimation model, expressed as:

[0009] in, This is the junction temperature under the current conditions. This refers to the junction temperature in the previous state. These are the junction temperatures in the first two states. This represents the total power loss in the current state. This represents the total power loss in the previous state. Where T is the sensor temperature and T is the preset sampling rate.

[0010] Preferably, in step S1, the IGBT module loses energy when turned on. Curve, IGBT module turn-off energy loss Curve, reverse recovery energy of parasitic diode in IGBT module Curve, IGBT module on-state voltage drop Curves and parasitic diode forward voltage drop of IGBT module The expressions for the curves are as follows:

[0011]

[0012]

[0013]

[0014]

[0015] in, This is the collector-emitter current. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve.

[0016] Preferably, the least squares method is used to... , , , and The curves were fitted and optimized to obtain the following results: , , , and The curves are collectively stored as the optimal performance curve set, with the following expressions:

[0017]

[0018]

[0019]

[0020]

[0021] in, , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve.

[0022] Preferably, the objective function used for the least squares fitting optimization is:

[0023] The optimal fitting coefficients are obtained by minimizing the sum of squares of the fitting errors of the objective function.

[0024] Preferably, in step S3, the total power loss is the sum of various losses, including: IGBT module turn-on loss, IGBT module turn-off loss, IGBT module parasitic diode reverse recovery loss, IGBT module conduction loss, and IGBT module parasitic diode conduction loss.

[0025] Preferably, in step S3, the expression for calculating the total power loss of the IGBT module is as follows:

[0026]

[0027]

[0028]

[0029]

[0030]

[0031] in, For IGBT module turn-on losses, For IGBT module turn-off losses, For the conduction loss of the IGBT module, For the parasitic diode reverse recovery loss of the IGBT module, For the conduction loss of the parasitic diode in the IGBT module, This is the voltage bus level conversion factor. This is the instantaneous value of the phase current. This refers to the duty cycle of the IGBT device. For switching frequency, This represents the total power loss of a single IGBT.

[0032] Preferably, the method is used to monitor the junction temperature of the IGBT power module in the air conditioner compressor driver in real time.

[0033] An IGBT module junction temperature estimation system, comprising: Fitting and optimization unit: used to obtain the set of performance curves of IGBT module under different operating conditions and perform fitting and optimization to obtain the optimal set of performance curves; the set of performance curves includes at least: IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve and IGBT module parasitic diode forward voltage drop curve. Model building unit: used to build a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and to build a second-order Foster thermal network model based on the transient thermal resistance curve model; the second-order Foster thermal network model is subjected to Laplace transform and discretization based on the backward difference method to finally obtain the junction temperature estimation model of the IGBT module. Power loss calculation unit: used to collect instantaneous phase current values ​​in real time and calculate the total power loss of the IGBT module in real time by combining the optimal performance curve set; Junction temperature estimation unit: used to estimate the junction temperature by using the total power loss of the IGBT module calculated in real time and the junction temperature estimation model to obtain the junction temperature of the IGBT module in real time.

[0034] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention provides a method for estimating the junction temperature of an IGBT module, comprising the following steps: First, acquiring a set of performance curves of the IGBT module under different operating conditions and performing fitting optimization to obtain the optimal set of performance curves; the set of performance curves includes at least: the IGBT module turn-on loss energy curve, the IGBT module turn-off loss energy curve, the IGBT parasitic diode reverse recovery energy curve, the IGBT module forward voltage drop curve, and the IGBT module parasitic diode forward voltage drop curve; then, constructing a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance curve model, and constructing a second-order Foster thermal network model based on the transient thermal resistance curve model; performing Laplace transform and discretization based on the backward difference method on the second-order Foster thermal network model to finally obtain the junction temperature estimation model of the IGBT module; then, acquiring the instantaneous value of the phase current in real time, and calculating the total power loss of the IGBT module in real time in combination with the optimal set of performance curves; finally, using the total power loss of the IGBT module calculated in real time and the junction temperature estimation model to obtain the junction temperature of the IGBT module in real time, thus completing the junction temperature estimation.

[0035] This invention utilizes offline dual-pulse experiments and a loss energy manual provided by the manufacturer to construct a loss energy model database using the least squares method. The total loss of a single IGBT is then calculated. This method improves the accuracy of IGBT model loss, thereby enhancing the accuracy of junction temperature estimation models. Offline transient thermal resistance experiments are also conducted in conjunction with... The transient thermal resistance curve is obtained by relating the temperature of the IGBT chip to the ambient temperature. A second-order Foster thermal network model is constructed, and the thermal network model is discretized using Laplace transform and backward difference method to finally obtain the junction temperature estimation model. Utilizing the electrothermal coupling model effectively reduces hardware costs and provides real-time estimation of the current maximum temperature of the IGBT module chip; it improves the accuracy of junction temperature estimation and the stability of the entire system; and it is beneficial for engineering applications. Attached Figure Description

[0036] Figure 1 This is a flowchart of an IGBT module junction temperature estimation method in Example 1; Figure 2This is a flowchart of an IGBT module junction temperature estimation method in Example 2; Figure 3 This is a schematic diagram of a double-pulse experiment for estimating the junction temperature of an IGBT module in Example 2; Figure 4 This is a flowchart of the IGBT module total power loss calculation method for an IGBT module junction temperature estimation method in Example 2; Figure 5 The equivalent circuit diagram of the discretized second-order Foster thermal network model of an IGBT module junction temperature estimation method in Example 2 is shown below. Figure 6 This is a schematic diagram of the junction temperature estimation algorithm framework for an IGBT module junction temperature estimation method in Example 2; Figure 7 This is a system framework diagram of an IGBT module junction temperature estimation method in Example 3. Detailed Implementation

[0037] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this application. To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] Example 1 like Figure 1 As shown, a method for estimating the junction temperature of an IGBT module includes the following steps: S1: Obtain the set of performance curves of the IGBT module under different operating conditions and perform fitting optimization to obtain the optimal set of performance curves; the set of performance curves includes at least: IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve and IGBT module parasitic diode forward voltage drop curve. S2: Construct a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and construct a second-order Foster thermal network model based on the transient thermal resistance curve model; perform Laplace transform and discretization processing based on the backward difference method on the second-order Foster thermal network model to finally obtain the junction temperature estimation model of the IGBT module. S3: Real-time acquisition of instantaneous phase current values, and real-time calculation of the total power loss of the IGBT module in conjunction with the optimal performance curve set; S4: Using the total power loss of the IGBT module calculated in real time and the junction temperature of the IGBT module obtained in real time by the junction temperature estimation model, the junction temperature is estimated.

[0040] In the specific implementation process, firstly, experiments were conducted on the compressor IGBT module under actual operating conditions of the air conditioning unit based on the double-pulse experimental principle, including current rise and fall, voltage rise and fall, and temperature rise and fall, to obtain the IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve, and IGBT module parasitic diode forward voltage drop curve. Next, the obtained performance curves were combined with the IGBT module energy data sheet provided by the manufacturer, and the optimal performance curve was fitted using the least squares method. Then, based on the transient thermal resistance principle, the effects of air-cooled air velocity and refrigerant condensate were considered in the experiment, combined with... Based on the relationship with temperature, a transient thermal resistance curve model from the IGBT module chip to the internal NTC of the IGBT module is obtained. A second-order Foster thermal network model is then constructed based on this transient thermal resistance curve model. This second-order Foster thermal network model is discretized using Laplace transform and backward difference method to obtain a junction temperature estimation model. Finally, the instantaneous phase current value under actual operating conditions is read from the input module of the hardware design. The instantaneous current value is used to determine the system current flow direction. Combined with the above optimal performance curve expression, the total power loss of the IGBT module is calculated. The real-time temperature of the IGBT module is obtained based on the junction temperature estimation model.

[0041] Example 2 This embodiment provides a flowchart of an IGBT module junction temperature estimation method, as shown below. Figure 2 As shown, the method operates on an air-cooled air conditioning compressor, and the method includes the following steps: S1: Obtain the set of performance curves of the IGBT module under different operating conditions and perform fitting optimization to obtain the optimal set of performance curves; the set of performance curves includes at least: IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve and IGBT module parasitic diode forward voltage drop curve. S2: Construct a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and construct a second-order Foster thermal network model based on the transient thermal resistance curve model; perform Laplace transform and discretization processing based on the backward difference method on the second-order Foster thermal network model to finally obtain the junction temperature estimation model of the IGBT module. S3: Real-time acquisition of instantaneous phase current values, and real-time calculation of the total power loss of the IGBT module in conjunction with the optimal performance curve set; S4: Using the total power loss of the IGBT module calculated in real time and the junction temperature of the IGBT module obtained in real time by the junction temperature estimation model, the junction temperature is estimated.

[0042] In step S2, the transient thermal resistance curve model expression is:

[0043] in, The junction-to-shell thermal resistance varies over time. For time variables, , These are the first and second thermal resistance parameters of the thermal mesh model, respectively. , These are the first and second heat capacity parameters of the thermal mesh model, respectively.

[0044] A second-order Foster thermal network model is constructed based on the transient thermal resistance curve model. This model is then subjected to Laplace transform and discretization using the backward difference method to obtain the junction temperature estimation model, expressed as:

[0045] in, This is the junction temperature under the current conditions. This refers to the junction temperature in the previous state. These are the junction temperatures in the first two states. This represents the total power loss in the current state. This represents the total power loss in the previous state. Where T is the sensor temperature and T is the preset sampling rate.

[0046] In step S1, the IGBT module loses energy when turned on. Curve, IGBT module turn-off energy loss Curve, reverse recovery energy of parasitic diode in IGBT module Curve, IGBT module on-state voltage drop Curves and parasitic diode forward voltage drop of IGBT module The expressions for the curves are as follows:

[0047]

[0048]

[0049]

[0050]

[0051] in, This is the collector-emitter current. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve.

[0052] In step S1, the least squares method is used to... , , , and The curves were fitted and optimized to obtain the following results: , , , and The curves are collectively stored as the optimal performance curve set, with the following expressions:

[0053]

[0054]

[0055]

[0056]

[0057] in, , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve.

[0058] The objective function used in the least squares fitting optimization is as follows:

[0059] The optimal fitting coefficients are obtained by minimizing the sum of squares of the fitting errors of the objective function.

[0060] In step S3, the total power loss is the sum of various losses, including: IGBT module turn-on loss, IGBT module turn-off loss, IGBT module parasitic diode reverse recovery loss, IGBT module conduction loss, and IGBT module parasitic diode conduction loss.

[0061] In step S3, the expression for calculating the total power loss of the IGBT module is as follows:

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] in, For IGBT module turn-on losses, For the turn-off loss of IGBT devices, For IGBT device conduction loss, This refers to the reverse recovery loss of the diode, a parasitic component of the IGBT. For the conduction loss of the diode, a parasitic component of the IGBT, This is the voltage bus level conversion factor. This is the instantaneous value of the phase current. This refers to the duty cycle of the IGBT device. For switching frequency, This represents the total power loss of a single IGBT.

[0068] The method is used to monitor the junction temperature of the IGBT power module in the air conditioner compressor driver in real time.

[0069] In the specific implementation process, such as Figure 3 As shown, the actual operating condition test of the air conditioner compressor IGBT module was conducted based on the double-pulse experimental principle, combined with the factory energy loss data of the air-cooled air conditioner compressor. The factory energy loss data includes: factory IGBT module switching loss energy, factory IGBT on-state voltage drop, factory diode reverse recovery loss energy, and factory diode on-state voltage drop curve. The optimal IGBT switching loss energy, IGBT on-state voltage drop, diode reverse recovery loss energy, and diode on-state voltage drop curve were fitted using the least squares method. The specific steps of the least squares method include: setting the objective function as... The error is The optimal function is the one where the error is minimized. Solving for a, b, c, and d, let... The optimal fitting coefficients can be obtained by solving the problem. The optimized performance curve can be obtained by replacing the fitting coefficients in the performance curve with the optimal fitting coefficients. The total loss of the IGBT module can be calculated using the optimized performance curve, thereby improving the accuracy of the IGBT module loss and thus improving the accuracy of the junction temperature estimation model.

[0070] The calculation process for the total power loss of an IGBT module is as follows: Figure 4 As shown, the actual operating parameters of the compressor drive module IGBT are obtained when the air conditioning unit is running. Based on the actual operating conditions, the instantaneous values ​​of the three-phase current and the duty cycle are obtained. Combined with the optimized performance curve, the IGBT switching loss, IGBT conduction loss, diode reverse recovery loss and diode conduction loss are calculated.

[0071] like Figure 5As shown, based on the principle of transient thermal resistance experiments and its relationship with temperature, a transient thermal resistance model of the IGBT module of the air conditioner compressor was obtained by conducting actual operating condition tests. This model considers the air-cooled air velocity. Based on the transient thermal resistance model parameters and the IGBT module Tc as the reference temperature, a second-order Foster thermal network model was constructed. The second-order thermal network model was then subjected to Laplace transform and backward differential discretization to obtain the junction temperature estimation model. T,(n)=K,T,(n-1)-K,Tj(n-2)+KPiss(n)-K,Poss(n-1)+ Tntc. Finally, based on parameters such as the instantaneous current value obtained from the hardware design sampling under actual operating conditions, the total loss and transient heat value of a single IGBT module are calculated, and the maximum junction temperature of the air conditioner compressor IGBT module is estimated in real time.

[0072] The method algorithm framework diagram provided in this embodiment is as follows: Figure 6 As shown, after obtaining the performance curve based on the double-pulse experimental principle, the least squares method is used for optimization in conjunction with the energy data sheet provided by the manufacturer. Based on the optimized performance curve, the total IGBT module loss is calculated. The total IGBT module loss includes: IGBT module turn-on loss, IGBT module turn-off loss, IGBT module parasitic diode reverse recovery loss, IGBT module conduction loss, and IGBT module parasitic diode conduction loss. The calculated total IGBT module loss is then evaluated. If the IGBT module loss is normal (i.e., greater than 0), it is input into the junction temperature estimation model for junction temperature estimation, and the temperature difference is output. If the IGBT module loss is abnormal (i.e., less than or equal to 0), the total IGBT module loss is set to zero, and the junction temperature estimation model outputs zero (i.e., the junction temperature output is abnormal).

[0073] Example 3 This embodiment provides an IGBT module junction temperature estimation system, such as... Figure 7 As shown, the system operates under an air-cooled air conditioning compressor, and the system includes: Fitting and optimization unit 301: used to obtain the set of performance curves of IGBT module under different operating conditions and perform fitting and optimization to obtain the optimal set of performance curves; the set of performance curves includes at least: IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve and IGBT module parasitic diode forward voltage drop curve. Model building unit 302: is used to build a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and to build a second-order Foster thermal network model based on the transient thermal resistance curve model; the second-order Foster thermal network model is subjected to Laplace transform and discretization based on the backward difference method to finally obtain the junction temperature estimation model of the IGBT module. Power loss calculation unit 303: used to collect the instantaneous value of phase current in real time, and calculate the total power loss of the IGBT module in real time in combination with the optimal performance curve set; Junction temperature estimation unit 304: used to estimate the junction temperature by using the total power loss of the IGBT module calculated in real time and the junction temperature estimation model to obtain the junction temperature of the IGBT module in real time.

[0074] In the specific implementation process, the fitting and optimization unit 301 obtains the performance curve based on the double-pulse experimental principle, and then uses the least squares method combined with the factory loss energy to fit and optimize the optimal performance curve. The model building unit 302 constructs a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and constructs a second-order Foster thermal network model based on the parameters of the transient thermal resistance curve model. The second-order Foster thermal network model is then subjected to Laplace transform and discretization processing based on the backward difference method to obtain the junction temperature estimation model of the IGBT module. Afterwards, the power loss calculation unit 303 reads the instantaneous value of the phase current from the input module of the air-cooled air conditioning compressor, determines the current direction, and calculates the total power loss of the IGBT module in combination with the optimal performance curve. Finally, the junction temperature estimation unit 304 takes the total power loss of the IGBT module as input and outputs the junction temperature estimate.

[0075] The same or similar labels correspond to the same or similar parts; The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this application. Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for estimating the junction temperature of an IGBT module, characterized in that, Includes the following steps: S1: Obtain the set of performance curves of the IGBT module under different operating conditions and perform fitting optimization to obtain the optimal set of performance curves; the set of performance curves includes at least: IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve and IGBT module parasitic diode forward voltage drop curve. S2: Construct a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and construct a second-order Foster thermal network model based on the transient thermal resistance curve model; perform Laplace transform and discretization processing based on the backward difference method on the second-order Foster thermal network model to finally obtain the junction temperature estimation model of the IGBT module. S3: Real-time acquisition of instantaneous phase current values, and real-time calculation of the total power loss of the IGBT module in conjunction with the optimal performance curve set; S4: Using the total power loss of the IGBT module calculated in real time and the junction temperature of the IGBT module obtained in real time by the junction temperature estimation model, the junction temperature is estimated.

2. The IGBT module junction temperature estimation method according to claim 1, characterized in that, In step S2, the transient thermal resistance curve model expression is: in, The thermal resistance from junction to casing varies over time. For time variables, , These are the first and second thermal resistance parameters of the thermal mesh model, respectively. , These are the first and second heat capacity parameters of the thermal mesh model, respectively.

3. The IGBT module junction temperature estimation method according to claim 2, characterized in that, A second-order Foster thermal network model is constructed based on the transient thermal resistance curve model. This model is then subjected to Laplace transform and discretization using the backward difference method to obtain the junction temperature estimation model, expressed as: in, This is the junction temperature under the current conditions. This refers to the junction temperature in the previous state. These are the junction temperatures in the first two states. This represents the total power loss in the current state. This represents the total power loss in the previous state. Where T is the sensor temperature and T is the preset sampling rate.

4. The IGBT module junction temperature estimation method according to claim 1, characterized in that, In step S1, the IGBT module loses energy when turned on. Curve, IGBT module turn-off energy loss Curve, reverse recovery energy of parasitic diode in IGBT module Curve, IGBT module on-state voltage drop Curves and parasitic diode forward voltage drop of IGBT module The expressions for the curves are as follows: in, This is the collector-emitter current. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve. , , , They are respectively The first, second, third, and fourth fitting coefficients of the curve.

5. The IGBT module junction temperature estimation method according to claim 4, characterized in that, In step S1, the least squares method is used to... , , , and The curves were fitted and optimized to obtain the following results: , , , and The curves are collectively stored as the optimal performance curve set, with the following expressions: in, , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve. , , , They are respectively The first, second, third, and fourth best-fit coefficients of the curve.

6. The IGBT module junction temperature estimation method according to claim 5, characterized in that, The objective function used in the least squares fitting optimization is as follows: The optimal fitting coefficients are obtained by minimizing the sum of squares of the fitting errors of the objective function.

7. The IGBT module junction temperature estimation method according to claim 1, characterized in that, In step S3, the total power loss is the sum of various losses, including: IGBT module turn-on loss, IGBT module turn-off loss, IGBT module parasitic diode reverse recovery loss, IGBT module conduction loss, and IGBT module parasitic diode conduction loss.

8. The IGBT module junction temperature estimation method according to claim 7, characterized in that, In step S3, the expression for calculating the total power loss of the IGBT module is as follows: in, For IGBT module turn-on losses, For the turn-off loss of IGBT devices, For the conduction loss of the IGBT module, For the reverse recovery loss of the parasitic diode of the IGBT module, For the conduction loss of the parasitic diode in the IGBT module, This is the voltage bus level conversion factor. This is the instantaneous value of the phase current. This refers to the duty cycle of the IGBT device. For switching frequency, This represents the total power loss of a single IGBT.

9. A method for estimating the junction temperature of an IGBT module according to any one of claims 1-8, characterized in that, The method is used to monitor the junction temperature of the IGBT power module in the air conditioner compressor driver in real time.

10. An IGBT module junction temperature estimation system, characterized in that, include: Fitting and optimization unit: Used to obtain the set of performance curves of IGBT modules under different operating conditions and perform fitting and optimization to obtain the optimal set of performance curves; The set of performance curves includes at least: IGBT module turn-on loss energy curve, IGBT module turn-off loss energy curve, IGBT module parasitic diode reverse recovery energy curve, IGBT module forward voltage drop curve, and IGBT module parasitic diode forward voltage drop curve. Model building unit: used to build a transient thermal resistance curve model for the IGBT module based on the transient thermal resistance principle, and to build a second-order Foster thermal network model based on the transient thermal resistance curve model; the second-order Foster thermal network model is subjected to Laplace transform and discretization based on the backward difference method to finally obtain the junction temperature estimation model of the IGBT module. Power loss calculation unit: used to collect instantaneous phase current values ​​in real time and calculate the total power loss of the IGBT module in real time by combining the optimal performance curve set; Junction temperature estimation unit: used to estimate the junction temperature by using the total power loss of the IGBT module calculated in real time and the junction temperature estimation model to obtain the junction temperature of the IGBT module in real time.

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