Multi-chip parallel IGBT module temperature prediction method based on frequency domain thermal coupling model

Abstract

The invention provides a multi-chip parallel IGBT module temperature prediction method based on a frequency domain thermal coupling model, and the method comprises the steps: determining the grouping of chips according to the average loss, and building a thermal coupling model of a multi-chip parallel IGBT module; extracting parameters of the thermal coupling model; and inputting the power loss PT1-PTn of each IGBT chip and the power loss PD1-PDn of each diode into the thermal coupling model, and outputting the junction temperatures TjT1-TjTn and TjD1-TjDn of each chip of the device, the module shell temperature TC and the output heat flow PoutC at the position by combining the parameters of the thermal coupling model. The method can be suitable for the characteristic that parallel chips in the multi-chip parallel IGBT module can only be heated at the same time, the parameter identification complexity of an existing thermal coupling model is simplified, the heat flow characteristic of the power module and the loss characteristic generated under the working condition are considered, and the junction temperature, the shell temperature and the output heat flow of the multi-chip module can be monitored.

Description

Technical Field

[0001] The present invention relates to the technical field of reliability analysis of power electronic power semiconductor devices, and in particular, to a temperature prediction method and system for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model. Background Art

[0002] With the rapid development of power electronics technology, the requirements for the power density and efficiency of power conversion equipment are also getting higher and higher. In order to control larger power, the current-carrying capacity of a single chip can be expanded by paralleling multiple chips inside the power module, so as to obtain a large current output capacity. In high-power applications, multi-chip parallel modules are easily affected by severe thermal stress, resulting in shortened device life and degraded system performance. The reliability of power modules highly depends on accurate temperature information. Therefore, analyzing the thermal behavior of multi-chip parallel IGBT modules is crucial.

[0003] Currently, the widely used method for calculating the device temperature of multi-chip IGBT modules is to use a coupled thermal impedance matrix to calculate the influence of thermal coupling between multiple chips on the device temperature. However, the problems it has include: the parallel chips can only be turned on simultaneously to generate losses, and the coupled thermal impedance of a single chip cannot be obtained; the input power loss of the chip is regarded as equal to the output power on the housing, ignoring the thermal flow characteristics of the device; the loss characteristics generated by the module under working conditions are not considered; there are many parameters to be identified, and the parameter extraction process is complex. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a temperature prediction method and system for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model.

[0005] According to one aspect of the present invention, there is provided a temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model, including:

[0006] Determining the grouping of chips according to the average loss, and establishing a thermal coupling model of the multi-chip parallel IGBT module;

[0007] Extracting the parameters of the thermal coupling model, including: multi-input junction-to-case thermal impedance Z jc,TkC@Tall , Z jc,TkC@Dall , k = 1,..., n, multi-input heat transfer function G LPF,C@Tall (s), G LPF,C@Dall (s), multi-input case-to-environment thermal impedance Z Ca@Tall , Z Ca@Dall ;

[0008] Applying the power losses P T1 ~P Tn of each IGBT chip and the power losses P of each diodeD1 ~P Dn is input into the thermal coupling model, and combined with the thermal coupling model parameters, the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn of each chip of the device, the module case temperature T C and the output heat flux P outC at this location are output.

[0009] Preferably, the grouping of chips according to the average loss includes:

[0010] According to the power loss characteristics generated under the chip operating conditions, the chips with equal average losses are divided into the same group, that is, the IGBT chips T1~Tn with equal average losses are divided into one group, and the diode chips D1~Dn with equal average losses are divided into one group.

[0011] Preferably, the thermal coupling model includes:

[0012] represents the external thermal network of the IGBT module, inputs the total IGBT loss P IGBT,all =P T1 +…+P Tn and the total diode loss P Diode,all =P D1 +…+P Dn After flowing through the heat flux network from the chip to the case and then into the case-environment thermal impedance network from the case to the environment, the output heat flux P outC and the case temperature Tc are obtained;

[0013] represents the internal thermal network of the IGBT module, which is divided into two parts: the IGBT chip and the diode chip. Each part inputs the power losses P T1 ~P Tn and P D1 ~P Dn and then is connected to the case temperature Tc through the junction-case thermal impedance network, and finally the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn are obtained.

[0014] Preferably, the extraction of the thermal coupling model parameters includes:

[0015] Make the current flow through all the IGBT chips in the multi-chip parallel IGBT module simultaneously. Under the constant loss input, obtain the thermal coupling model parameters of the thermal coupling model when all IGBTs are heated;

[0016] Make the current flow through all the diode chips in the multi-chip parallel IGBT module simultaneously, and obtain the thermal coupling model parameters of the thermal coupling model when all the diodes are heated under a constant loss input.

[0017] Preferably, the multi-input junction-case thermal impedance parameters include:

[0018] Heating all the IGBT chips T 1 ~T n Make the k-th IGBT chip T k , k = 1, 2…n generate the multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature T jc,TkC@Tall , which is defined as where @Tall represents heating all the IGBT chips, and T jc,TkC@Tall is the temperature of heating all the IGBT chips T 1 ~T n Make the k-th IGBT chip T k generate the junction-case temperature difference with the case temperature T C , and P Tk is the power loss of the k-th IGBT chip T k ;

[0019] Heating all the IGBT chips T 1 ~T n Make the k-th diode chip D k， k = 1, 2…n generate the multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature T jc,TkC@Dall , which is defined as where T jc,DkC@Tall is the temperature of heating all the IGBT chips T 1 ~T n Make the k-th diode chip D k generate the junction-case temperature difference with the case temperature T C , and P IGBT,all is the sum of the power losses of all the IGBT chips, that is, P IGBT,all = P T1 +…+ P Tn ;

[0020] Heating all the diode chips D1~Dn makes the k-th IGBT chip T k， k = 1, 2…n generate the multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature T jc,TkC@Dall , which is defined as where @Dall represents heating all the diode chips, and T jc,TkC@Dall is the temperature of heating all the diode chips D1~Dn that makes the k-th IGBT chip T k generate the junction-case temperature difference with the case temperature TC The junction-to-case temperature difference, P Diode,all is the sum of the power losses of all diode chips, i.e., P Diode,all = P D1 + … + P Dn ;

[0021] Heat all the diode chips D1~Dn so that the k-th diode chip D k， k = 1, 2…n generates a multi-input junction-to-case thermal impedance Z C with the junction-to-case temperature difference from the case temperature T jc,DkC@Dall , which is defined as where T jc,DkC@Dall is the junction-to-case temperature difference generated by heating all the diode chips D1~Dn to make the k-th diode chip D k with the case temperature T C , and P Dk is the power loss of the k-th diode chip D k .

[0022] Preferably, the multi-input heat flow transfer function includes:

[0023] The heat flow transfer function G LPF,C@Tall (s) for heating all the IGBT chips T1~Tn to obtain the output heat flow at the case temperature point, which is defined as where P outC@Tall represents the output heat flow obtained by heating all the IGBT chips T1~Tn at the case temperature point C

[0024] The heat flow transfer function G LPF,C@Dall (s) for heating all the diode chips D1~Dn to obtain the output heat flow at the case temperature point, which is defined as where P outC@Dall represents the output heat flow obtained by heating all the diode chips D1~Dn at the case temperature point C

[0025] Preferably, the multi-input case ambient thermal impedance parameter includes

[0026] The multi-input case ambient thermal impedance Z Ca@Tall for heating all the IGBT chips T1~Tn to cause a case ambient temperature difference in the case temperature, which is defined as where T Ca@Tall represents the case-to-ambient temperature difference generated by heating all the IGBT chips T1~Tn to make the case temperature Tc

[0027] The multi-input case ambient thermal impedance Z Ca@Dall for heating all the diode chips D1~Dn to cause a case ambient temperature difference in the case temperature, defined as where T Ca@Dall represents the case-to-ambient temperature difference generated by heating all the diode chips D1~Dn to make the case temperature Tc

[0028] Preferably, the junction temperature is obtained by multiplying the two multi-input junction-to-case thermal impedances at the chip T k or D k by the total power losses of the two sets of inputs respectively, and then adding them in the form of the junction-to-case temperature difference to obtain the chip T k or D k junction temperature;

[0029] The output heat flux is obtained by multiplying the two heat flux transfer function parameters by the total power losses of the two sets of inputs respectively to obtain two output heat fluxes P outC@Tall and P outC@Dall at the case temperature, and then superimposing them to obtain the total output heat flux at the case temperature;

[0030] The case temperature T C of the module is obtained by multiplying the two thermal impedances at the case temperature by the two output heat fluxes at the case temperature point respectively, and then adding them in the form of the case-to-environment temperature difference to obtain the case temperature.

[0031] Preferably, the determination process of the case temperature point is as follows: according to the ratio of the average power losses generated by each chip under the standard working condition in the same substrate, the central coordinate values of each chip are weighted and added to obtain the power center point coordinate, which is the heat flux superposition center, that is, the highest temperature point on the outer shell of the substrate, and is the case temperature point.

[0032] According to the second aspect of the present invention, a multi-chip parallel IGBT module temperature prediction system based on a frequency-domain thermal coupling model is provided, including:

[0033] Model establishment module: determining the grouping of chips according to the average losses, and establishing a thermal coupling model of the multi-chip parallel IGBT module;

[0034] Parameter extraction module: extracting the thermal coupling model parameters, including: multi-input junction-to-case thermal impedances Z jc,TkC@Tall , Z jc,TkC@Dall , k = 1,..., n, multi-input heat flux transfer functions G LPF,C@Tall (s), G LPF,C@Dall (s), multi-input case-to-environment thermal impedances Z Ca@Tall , Z Ca@Dall ;

[0035] Prediction module: inputting the power losses P T1 ~P Tn of each IGBT chip and the power losses P D1 ~P Dn of each diode into the thermal coupling model, and combining the thermal coupling model parameters, outputting the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn, the module case temperature T C and the output heat flux P at this location outC .

[0036] Compared with the prior art, the embodiments of the present invention have at least one of the following beneficial effects:

[0037] The temperature prediction method and system for multi-chip parallel IGBT modules based on the frequency-domain thermal coupling model in the embodiments of the present invention can be applicable to the characteristic that the parallel chips inside the multi-chip parallel IGBT module can only be heated simultaneously. At the same time, it simplifies the parameter identification complexity of the existing thermal coupling model, and takes into account the heat flux characteristics of the power module and the loss characteristics generated under working conditions, and can monitor the junction temperature, case temperature and output heat flux of the multi-chip module.

[0038] In the temperature prediction method and system for multi-chip parallel IGBT modules based on the frequency-domain thermal coupling model in the embodiments of the present invention, when calculating the influence of thermal coupling on temperature prediction, the instantaneous power can be converted into average power for calculation. Therefore, even when the chips do not generate losses simultaneously under working conditions, the chips can be modeled in groups according to the equality of the average values, that is, the loss characteristics generated under working conditions are considered in the monitoring and prediction.

[0039] The temperature prediction method for multi-chip parallel IGBT modules based on the frequency-domain thermal coupling model in the embodiments of the present invention is applicable to parallel devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] By reading the following detailed description of the non-limiting embodiments with reference to the accompanying drawings, other features, objects and advantages of the present invention will become more apparent:

[0041] Figure 1 is a flowchart of the temperature prediction method for multi-chip parallel IGBT modules based on the frequency-domain thermal coupling model in an embodiment of the present invention;

[0042] Figure 2 is a structural diagram of the thermal coupling model in a preferred embodiment of the present invention;

[0043] Figure 3 is a multi-chip parallel IGBT module in a preferred embodiment of the present invention;

[0044] Figure 4 is a finite element model of the multi-chip parallel IGBT module in a preferred embodiment of the present invention;

[0045] Figure 5 is a comparison of the junction temperatures obtained by finite element simulation and thermal coupling model calculation in a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made. These all belong to the protection scope of the present invention.

[0047] The present invention provides an embodiment, a temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model, and its specific process is as Figure 1 shown, including:

[0048] Step 1, determine the grouping of chips according to the average loss, and establish a thermal coupling model of the multi-chip parallel IGBT module;

[0049] Step 2, extract the thermal coupling model parameters, specifically including: multi-input junction-case thermal impedance Z jc,TkC@Tall , Z jc,TkC@Dall , k = 1,..., n, multi-input heat flow transfer function G LPF,C@Tall (s), G LPF,C@Dall (s), multi-input case-environment thermal impedance Z Ca@Tall , Z Ca@Dall ;

[0050] Step 3, input the power losses P T1 ~P Tn of each IGBT chip and the power losses P D1 ~P Dn of each diode into the thermal coupling model, and combine the thermal coupling model parameters to output the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn of each chip of the device, the case temperature T C of the module, and the output heat flow P outC .

[0051] In this embodiment, by grouping the chips and taking the total power loss of each group of chips as the input, it is applicable to the characteristic that parallel chips can only generate losses simultaneously, and simplifies the parameter extraction process; at the same time, this method considers the heat flow characteristics of power semiconductor devices and the loss characteristics generated under working conditions. This embodiment can realize the prediction of the junction temperature, case temperature and output heat flow of the multi-chip parallel IGBT module, and overcomes the problems existing in the prior art that are not applicable to parallel devices and have complex parameter identification.

[0052] In a preferred embodiment of the present invention, a preferred method for grouping chips in step 1 is provided. According to the power loss characteristics generated under the chip operating conditions, chips with equal average losses are grouped into the same group. When calculating the influence of thermal coupling on temperature prediction, the instantaneous power can be converted into average power for calculation. Therefore, even if the chips do not generate losses simultaneously, the chips can be grouped and modeled according to the equal average values. Specifically, all IGBTs (T1, … Tn) are grouped into one group, and all diodes (D1, … Dn) are grouped into one group. In the model, @Tall represents the parameters obtained by heating all IGBTs simultaneously, and @Dall represents the parameters obtained by heating all diodes simultaneously. The power loss of each group is used as an input item of the thermal coupling model, and the multi-input junction-to-case thermal impedance parameters, multi-input heat flux transfer function parameters, and multi-input case-to-environment thermal impedance parameters are obtained for each group of chips.

[0053] In a preferred embodiment of the present invention, a preferred structure of the thermal coupling model is provided. Specifically, as Figure 2 shown, it includes two parts. One part is the external thermal network representing the IGBT module, and the other part is the internal thermal network representing the IGBT module.

[0054] In the external thermal network, the multi-input heat flux transfer function and the multi-input case-to-environment thermal impedance. The total IGBT loss P IGBT,all = P T1 + … + P Tn and the total diode loss P Diode,all = P D1 + … + P Dn After flowing through the heat flux network from the chip to the case, it flows into the case-to-environment thermal impedance network of the case to the environment, thereby obtaining the output heat flux P outC and the case temperature Tc.

[0055] In the internal thermal network, Figure 2 the module located above is the IGBT chip, and the module located in the middle is the diode. In the upper module, it includes the multi-input junction-to-case thermal impedance of each IGBT chip. After inputting the power losses P T1 ~P Tn of each chip and the total diode loss P Diode，all it is connected to the case temperature Tc through the junction-to-case thermal impedance network. After superimposing the temperatures obtained by the two groups of inputs of each chip passing through the junction-to-case thermal impedance, the junction temperatures T jT1 ~T jTn of each chip are obtained. In the middle module, it includes the multi-input junction-to-case thermal impedance of each diode. After inputting the power losses P D1 ~P Dn of each chip and the total IGBT loss P IGBT，all it is connected to the case temperature Tc through the junction-to-case thermal impedance network. After superimposing the temperatures obtained by the two groups of inputs of each chip passing through the junction-to-case thermal impedance, the junction temperatures TjD1 to T jDn 。

[0056] In a preferred embodiment of the present invention, in step S2, the parameters of the thermal coupling model are extracted. The model parameters are obtained by applying the same power input, such as a constant current source input, to the same group of chips, and calculating according to the output temperature difference and heat flow divided by the total input power; only two power inputs need to be applied to the entire model to obtain all the parameters.

[0057] Specifically, make the current flow through all the IGBT chips in the multi-chip parallel IGBT module simultaneously. Under a constant loss input, obtain the thermal coupling model parameters of the thermal coupling model when heating all the IGBTs;

[0058] Make the current flow through all the diode chips in the multi-chip parallel IGBT module simultaneously. Under a constant loss input, obtain the thermal coupling model parameters of the thermal coupling model when heating all the diodes.

[0059] Furthermore, the thermal coupling model is divided into two paths. One path is the junction-case thermal impedance path, and the other path is the heat flow transfer function path. The junction-case thermal impedance network and the heat flow channel are connected to the external radiator thermal impedance network. The characteristic of the heat flow channel is a low-pass filter LPF, defined as the ratio of the output power to the input power. Both the junction-case thermal impedance network and the case-environment thermal impedance network adopt the Foster-type thermal network. The thermal impedances used in the thermal coupling model of the embodiment of the present invention are Zjc and Zca, defined as the ratio of the temperature difference to the input power.

[0060] In a preferred embodiment, a preferred calculation method for the multi-input junction-case thermal impedance parameters is proposed. Specifically,

[0061] Heat all the IGBT chips T 1 to T n Make the kth IGBT chip T k , k = 1, 2... n generate a multi-input junction-case thermal impedance Z C with the junction-case temperature difference from the case temperature T jc,TkC@Tall , which is defined as where @Tall represents heating all the IGBT chips, and T jc,TkC@Tall is the temperature when heating all the IGBT chips T 1 to T n Make the kth IGBT chip T k generate a junction-case temperature difference from the case temperature T C , and P Tk is the power loss of the kth IGBT chip T k ;

[0062] Heat all the IGBT chips T 1 to Tn Cause the k-th diode chip D k , where k = 1, 2... n, to generate a multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature T jc,TkC@Dall， which is defined as where T jc,DkC@Tall is the temperature for heating all IGBT chips T 1 ~T n Cause the k-th diode chip D k to generate a junction-case temperature difference between the junction temperature and the case temperature T C , P IGBT,all is the sum of the power losses of all IGBT chips, that is, P IGBT,all = P T1 +... + P Tn ;

[0063] Heat all diode chips D1~Dn to cause the k-th IGBT chip T k , where k = 1, 2... n, to generate a multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature T jc,TkC@Dall , which is defined as where @Dall represents heating all diode chips, and T jc,TkC@Dall is the junction-case temperature difference between the junction temperature and the case temperature T k generated by heating all diode chips D1~Dn to the k-th IGBT chip T C , P Diode,all is the sum of the power losses of all diode chips, that is, P Diode,all = P D1 +... + P Dn ;

[0064] Heat all the diode chips D1~Dn to cause the k-th diode chip D k , where k = 1, 2... n, to generate a multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature T jc,DkC@Dall , which is defined as where T jc,DkC@Dall is the junction-case temperature difference between the junction temperature and the case temperature T k generated by heating all diode chips D1~Dn to the k-th diode chip D C , and P Dk is the power loss of the k-th diode chip D k .

[0065] In a preferred embodiment, a preferred calculation method for multi-input heat flow transfer function parameters is proposed. Specifically,

[0066] Heat all IGBT chips T1~Tn to obtain the heat flow transfer function G LPF,C@Tall (s) of the output heat flow at the case temperature point, which is defined as where P outC@Tall represents the output heat flux obtained by heating all IGBT chips T1 to Tn at the case temperature point C.

[0067] The heat transfer function G LPF,C@Dall (s) of the output heat flux obtained by heating all diode chips D1 to Dn at the case temperature point is defined as where P outC@Dall represents the output heat flux obtained by heating all diode chips D1 to Dn at the case temperature point C.

[0068] In a preferred embodiment, a preferred calculation method for multi-input case environment thermal impedance parameters is proposed.

[0069] The multi-input case environment thermal impedance Z Ca@Tall generated by heating all IGBT chips T1 to Tn to produce a case environment temperature difference is defined as where T Ca@Tall represents the case-to-environment temperature difference generated by heating all IGBT chips T1 to Tn to make the case temperature Tc.

[0070] The multi-input case environment thermal impedance Z Ca@Dall generated by heating all diode chips D1 to Dn to produce a case environment temperature difference is defined as where T Ca@Dall represents the case-to-environment temperature difference generated by heating all diode chips D1 to Dn to make the case temperature Tc.

[0071] In the above embodiment, the parameter identification complexity of the existing thermal coupling model is simplified. In the process of extracting parameters, it is only necessary to heat the internal thermal network twice, record the input losses of each chip, the output heat flux of the power center point, the case temperature, and the junction temperature of each chip, and then all parameters can be obtained.

[0072] It should be noted that in the model construction process, the input losses, junction temperatures, case temperatures, and output heat fluxes can be measured by any one or more of the following methods: the calculation method based on the device data sheet, the simulation-based method, or the experimental measurement method.

[0073] In a preferred embodiment of the present invention, in step 3, the power losses P T1 ~P Tn of each IGBT chip and the power losses P D1 ~P Dn of each diode are input into the thermal coupling model. Combining the parameters of the thermal coupling model, the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn of each chip of the device, the case temperature T C of the module and the output heat flux P at this place are output.outC , specifically:

[0074] Multiply the two sets of junction-to-case thermal impedance network parameters Z jc,TkC@Tall and Z jc,TkC@Dall by the two sets of input powers at the chip Tk respectively, and then add them in the form of the junction-to-case temperature difference to obtain the junction temperature of the chip Tk, that is, T jTk = n·p Tk ·Z jc,TkC@Tall + p Diode,all ·Z jc,TkC@Dall + T C , multiply the two sets of junction-to-case thermal impedance network parameters Z jc,TkC@Tall and Z jc,TkC@Dall by the two sets of input powers at the chip Dk respectively, and then add them in the form of the junction-to-case temperature difference to obtain the junction temperature of the chip Dk, that is, T jDk = p IGBT,all ·Z jc,TkC@Tall + n·p Dk ·Z jc,TkC@Dall + T C .

[0075] Multiply the two heat flux transfer function parameters G LPF,C@Tall(s) and G LPF,C@Dall(s) by the total losses of the two sets of input powers respectively to obtain two output heat fluxes P outC@Tall and P outC@Dall at the case temperature. After superposition, the total output power p out,C = G LPF,C@Tall (s)·p IGBT,all + G LPF,C@Dall (s)·p Diode,all = p out,C@Tall + p out,C@Dall .

[0076] Multiply the two external heat sink thermal impedance network parameters Z Ca@Tall and Z Ca@Dall by the two output heat fluxes at the case temperature and the case temperature point respectively, and then add them in the form of the case-to-environment temperature difference to obtain the case temperature, that is, T C = p out,C@Tall ·Z Ca@Tall + p outC@Dall ·Z Ca@Dall + T a , and this temperature is used as the reference temperature of the junction-to-case thermal impedance network.

[0077] Among them, the power loss of each chip can be obtained by experimentally measuring electrical parameters such as current and voltage and then inputting them into the loss calculation model, or directly measured by other devices. The measurement or calculation method is not limited.

[0078] The above embodiments achieve the monitoring of the junction temperature, case temperature, and the output heat flux at this location during the normal operation of the working conditions.

[0079] Based on the same inventive concept, in other embodiments of the present invention, a temperature prediction system for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model is provided, including a model establishment module, a parameter extraction module, and a prediction module. The model establishment module determines the grouping of chips according to the average loss and establishes a thermal coupling model of the multi-chip parallel IGBT module; the parameter extraction module extracts the parameters of the thermal coupling model, including: multi-input junction-case thermal impedance Z jc,TkC@Tall , Z jc,TkC@Dall , k = 1,…,n, multi-input heat flux transfer function G LPF,C@Tall (s), G LPF,C@Dall (s), multi-input case environment thermal impedance Z Ca@Tall , Z Ca@Dall ; the prediction module inputs the power losses P T1 ~P Tn of each IGBT chip and the power losses P D1 ~P Dn of each diode into the thermal coupling model, combines the parameters of the thermal coupling model, and outputs the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn of each chip of the device, the case temperature T C of the module, and the output heat flux P outC at this location.

[0080] In the above examples of the present invention, the specific implementation techniques of each module / unit can specifically refer to the corresponding steps of the device temperature prediction method for the multi-chip parallel IGBT module based on the frequency-domain thermal coupling model in the above embodiments, which will not be elaborated here.

[0081] Based on the same inventive concept, the present invention provides a specific application embodiment for predicting the junction temperature, case temperature, and output heat flux of a multi-chip parallel IGBT module, and the process is as follows:

[0082] S1, analyze the power loss situation of each chip when the multi-chip parallel IGBT module operates under working conditions;

[0083] According to the power loss characteristics generated by the chips under working conditions, the chips with equal average losses are divided into the same group. When calculating the influence of thermal coupling on temperature prediction, the instantaneous power can be converted into average power for calculation. Therefore, even if the chips do not generate losses simultaneously, the chips can be grouped and modeled according to the equal average values. Specifically, when the multi-chip parallel IGBT module operates as a bridge arm of a full-bridge topology, all IGBTs (T1,…T6) can be divided into one group, and all diodes (D1,…D6) can be divided into one group.

[0084] S2: Determine the power center position on the housing of each substrate in the module, i.e., the case temperature measurement point. The specific method is to weight the coordinates of the center of each chip according to the average loss of each chip to obtain the coordinates of the power center. This point is the center of the superposition of heat fluxes, and the temperature at this point is the highest temperature on the housing of the substrate. By default, each chip has a junction temperature measurement point, which is generally the center of the chip.

[0085] S3: Identify the parameters of the thermal coupling model. After obtaining the parameters, the thermal coupling model of the multi-chip parallel IGBT module can be constructed to accurately predict the junction temperature, case temperature, and output heat flux of the module.

[0086] In a preferred embodiment, S3 is implemented. The specific process is as follows:

[0087] S3.1: Let the current flow through all IGBT chips in the multi-chip parallel IGBT module simultaneously. Under a constant loss input, obtain the parameters of the thermal coupling model when all IGBTs are heated.

[0088] S3.2: Let the current flow through all diode chips in the multi-chip parallel IGBT module simultaneously. Under a constant loss input, obtain the parameters of the thermal coupling model when all diodes are heated.

[0089] After simplification, the parameter extraction process (i.e., step 3) only requires heating the module twice, recording the input losses of each chip, the output heat flux at the power center point, the case temperature, and the junction temperature of each chip, and then all parameters can be obtained. It should be noted that the input loss, output heat flux, case temperature, and junction temperature here are all measured under the condition of constant power heating, which is different from the predicted junction temperature, case temperature, and output heat flux under other heating conditions monitored during the subsequent application of the thermal coupling model.

[0090] Take Figure 3 the multi-chip parallel IGBT module shown as an example. In the Figure 4 finite element simulation shown, two heating conditions are applied to this module, and the case temperature and heat flux at the power center point and the chip junction temperature are recorded respectively:

[0091] 1. Heat all IGBT chips T1 to T6 with a constant input power.

[0092] 2. Heat all diode chips D1 to D6 with a constant input power.

[0093] Then, study and verify the output heat flux and case temperature at the power center C and the junction temperature of chip T3. Through curve fitting in the time domain, the thermal impedance network parameters such as Zjc and Zca can be identified. The heat flux transfer function is a low-pass filter (LPF), and its parameters can be identified by fitting the heat flux information output from the power center.

[0094] The power loss of the sine half-wave is used in the simulation to simplify the representation of the loss under the working conditions. The predicted temperatures at chip T3 and power center C1 point are as Figure 5 shown, and the maximum error is 0.3 degrees Celsius, which is caused by insufficient curve fitting accuracy. After 2 seconds, the error decreases, and the finite element simulation results are basically consistent with the junction temperature results calculated by the thermal coupling model.

[0095] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. A temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model, characterized in that, it includes: Determine the grouping of chips according to the average loss, and establish a thermal coupling model of the multi-chip parallel IGBT module; Extract the thermal coupling model parameters, including: multi-input junction shell thermal impedance Z jc,TkC@Tall , Z jc,TkC@Dall , k = 1, …, n, multi-input heat flow transfer function G LPF,C@Tall (s), G LPF,C@Dall (s), multi-input shell environment thermal impedance Z Ca@Tall , Z Ca@Dall ; Input the power losses P T1 ~P Tn of each IGBT chip and the power losses P D1 ~P Dn of each diode into the thermal coupling model, and combine with the thermal coupling model parameters to output the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn of each chip of the device, the module case temperature T C and the output heat flux P outC .

2. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 1, characterized in that, The determining the grouping of chips according to the average loss includes: According to the power loss characteristics generated under the chip operating conditions, group the chips with equal average losses into the same group, that is; group the IGBT chips T1 to Tn with equal average losses into one group, and group the diode chips D1 to Dn with equal average losses into one group.

3. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 1, characterized in that, The thermal coupling model includes: Represents the external thermal network of the IGBT module, and inputs the total IGBT loss P IGBT,all = P T1 + … + P Tn and the total diode loss P Diode,all = P D1 + … + P Dn After flowing through the chip-to-case thermal flow network, it flows into the case-to-environment case-environment thermal impedance network, and the output heat flow P outC and the case temperature Tc are obtained; It represents the internal thermal network of the IGBT module, which is divided into two parts: the IGBT chip and the diode chip. The power losses P T1 ~P Tn and P D1 ~P Dn of each part are input, and then connected to the case temperature Tc through the junction-case thermal impedance network. Finally, the junction temperatures T jT1 ~T jTn and T jD1 ~T jDn .

4. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 1, characterized in that, The extracting the thermal coupling model parameters includes: Make the current flow through all the IGBT chips in the multi-chip parallel IGBT module at the same time, and under a constant loss input, obtain the thermal coupling model parameters when heating all the IGBTs in the thermal coupling model; Make the current flow through all the diode chips in the multi-chip parallel IGBT module at the same time, and under a constant loss input, obtain the thermal coupling model parameters when heating all the diodes in the thermal coupling model.

5. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 4, characterized in that, The multi-input junction-case thermal impedance parameters include: Heat all IGBT chips T 1 ~T n Cause the k-th IGBT chip T k , k = 1, 2…n to generate a multi-input junction-to-case thermal impedance Z C with the case temperature T jc,TkC@Tall , which is defined as where @Tall represents heating all IGBT chips, T jc,TkC@Tall is the temperature of heating all IGBT chips T 1 ~T n Cause the k-th IGBT chip T k to generate a junction-to-case temperature difference with the case temperature T C , P Tk is the power loss of the k-th IGBT chip T k ; Heat all the IGBT chips T 1 ~T n Cause the k-th diode chip D k , where k = 1, 2…n, to generate a multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature T jc,TkC@Dall , which is defined as where T jc,DkC@Tall is the junction-case temperature difference generated by heating all the IGBT chips T 1 ~T n to cause the k-th diode chip D k to generate, P C is the sum of the power losses of all the IGBT chips, that is, P IGBT,all = P IGBT,all +…+ P T1 Tn ;​ Heat all diode chips D1 to Dn to cause the kth IGBT chip T k , where k = 1, 2... n, to generate a multi-input junction-to-case thermal impedance Z C between the junction temperature and the case temperature T jc,TkC@Dall , which is defined as where @Dall represents heating all diode chips, and T jc,TkC@Dall is the junction-to-case temperature difference between the junction temperature of the kth IGBT chip T k caused by heating all diode chips D1 to Dn and the case temperature T C , P Diode,all is the sum of the power losses of all diode chips, that is, P Diode,all = P D1 +... + P Dn ; Heat all the diode chips D1 to Dn so that the k-th diode chip D k , where k = 1, 2... n, generates a multi-input junction-case thermal impedance Z C between the junction temperature and the case temperature, which is defined as jc,DkC@Dall where T jc,DkC@Dall is the junction-case temperature difference generated by heating all the diode chips D1 to Dn so that the k-th diode chip D k generates, and P C is the power loss of the k-th diode chip D Dk . k ​ 6. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 4, characterized in that, The multi-input heat flow transfer function includes: Heat all IGBT chips T1 to Tn at the case temperature point to obtain the heat transfer function G LPF,C@Tall (s) of the output heat flux, which is defined as where P outC@Tall represents the output heat flux obtained by heating all IGBT chips T1 to Tn at the case temperature point C. Heat all the diode chips D1 to Dn at the case temperature point to obtain the heat transfer function G LPF,C@Dall (s) of the output heat flux, which is defined as where P outC@Dall represents the output heat flux obtained by heating all the diode chips D1 to Dn at the case temperature point C.

7. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 4, characterized in that, The multi-input case-environment thermal impedance parameters include Multi-input case-to-ambient thermal impedance Z that generates a case-to-ambient temperature difference by heating all IGBT chips T1 to Tn Ca@Tall , which is defined as where T Ca@Tall represents the case-to-ambient temperature difference Tc generated by heating all IGBT chips T1 to Tn Multi-input case-to-ambient thermal impedance Z that heats all diode chips D1 to Dn to create a case-to-ambient temperature difference Ca@Dall , defined as where T Ca@Dall represents the case-to-ambient temperature difference Tc generated by heating all diode chips D1 to Dn 8. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 1, characterized in that, The method for obtaining the junction temperature is as follows: Two multi-input junction-to-case thermal impedances are multiplied by the total power losses of the two sets of inputs at the chip T k or D k respectively, and then added in the form of the junction-to-case temperature difference to obtain the junction temperature of the chip T k or D k ; The way to obtain the output heat flux is as follows: The two heat flux transfer function parameters are respectively multiplied by the total losses of the two groups of input powers to obtain two output heat fluxes P outC@Tall and P outC@Dall at the shell temperature, and the total output heat flux at the shell temperature is obtained after superposition; The shell temperature T of the module C is obtained by multiplying the two thermal resistances by the two output heat fluxes at the shell temperature and the shell temperature point respectively, and adding them in the form of the shell environmental temperature difference to obtain the shell temperature.

9. The temperature prediction method for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model according to claim 1, characterized in that, The process of determining the case temperature point is as follows: According to the ratio of the average power losses generated under the standard operating conditions of each chip in the same substrate, weighted sum the central coordinate values of each chip to obtain the power center point coordinate, which is the heat flow superposition center, that is, the highest temperature point on the outer shell of this substrate, which is the case temperature point.

10. A temperature prediction system for a multi-chip parallel IGBT module based on a frequency-domain thermal coupling model, characterized in that, it includes: Model establishment module: Determine the grouping of chips according to the average loss, and establish a thermal coupling model of the multi-chip parallel IGBT module; Extraction parameter module: extract the thermal coupling model parameters, including: multi-input junction shell thermal impedance Z jc,TkC@Tall , Z jc,TkC@Dall , k = 1, …, n, multi-input heat flow transfer function G LPF,C@Tall (s), G LPF,C@Dall (s), multi-input shell environment thermal impedance Z Ca@Tall , Z Ca@Dall ; Prediction module: Input the power losses P of each IGBT chip T1 ~P Tn and the power losses P of each diode D1 ~P Dn into the thermal coupling model, and combine with the thermal coupling model parameters to output the junction temperatures T of each chip of the device jT1 ~T jTn and T jD1 ~T jDn , the module case temperature T C and the output heat flux P at this location outC .

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