METHOD AND SYSTEM FOR CHARACTERIZING IGBT MODULE AGING BASED ON MINER THEORY

Abstract

The invention discloses a method and a system for characterizing IGBT module aging based on Miner theory, including first establishing a life prediction model with a junction temperature fluctuation T.sub.jm and an average junction temperature ΔT.sub.j as inputs; then measuring a chip junction temperature data of an IGBT module; recording the junction temperature fluctuation T.sub.jm and the average junction temperature ΔT.sub.j of each power cycle; performing one life prediction in each cycle; and taking a reciprocal of a predicted life corresponding to each cycle and adding them to obtain an aging characteristic parameter D of the IGBT module. The invention may more suitably characterize the aging degree of the IGBT, and has the advantages of monotonically increasing change trend and high resolution.

Claims

1. A method for characterizing IGBT module aging based on Miner theory, comprising: S1: establishing a life prediction model with a junction temperature fluctuation and an average junction temperature as inputs; S2: measuring a data of a chip junction temperature of an IGBT module; S3: recording the junction temperature fluctuation and the average junction temperature of each power cycle; S4: performing one life prediction in each power cycle based on the life prediction model; S5: taking a reciprocal of a predicted life corresponding to each power cycle and adding them to obtain an aging characteristic parameter of the IGBT module.

2. The method of claim 1, wherein step S1 comprises: S1.1: performing a temperature cycle aging experiment on a group of IGBT modules of a same model, and controlling a temperature of an IGBT to prevent an aging of the IGBT modules from affecting their own temperature; S1.2: establishing the life prediction model $N_f=A\Delta T_j^{\alpha }{e}^{\frac{E_a}{k_B\left(T_{\mathrm{jm}}+273\right)}}$ according to the junction temperature fluctuation T.sub.jm and the average junction temperature ΔT.sub.j of the IGBT modules and a corresponding working life N.sub.f, wherein A and α are constants to be fitted, E.sub.a is an activation energy, and k.sub.B is Boltzmann constant.

3. The method of claim 2, wherein step S2 comprises: S2.1: measuring the chip junction temperature of an IGBT module to be tested when the IGBT module is disconnected in a working state and recording the chip junction temperature as T.sub.jmax; S2.2: measuring the chip junction temperature when the IGBT module is turned on and recording the chip junction temperature as T.sub.jmin.

4. The method of claim 3, wherein step S3 comprises: S3.1: a maximum junction temperature of an i-th power cycle record is T.sub.jmax-i, and a minimum junction temperature of the i-th power cycle record is T.sub.jmin-i; S3.2: calculating the junction temperature fluctuation ΔT.sub.j-i of the i-th power cycle by ΔT.sub.j-i=T.sub.jmax-i−T.sub.jmin-i; S3.3: calculating the average junction temperature T.sub.jm-i of the i-th power cycle by T.sub.jm-i=(T.sub.jmax-i+T.sub.jmin-i)/2.

5. The method of claim 4, wherein step S5 comprises: S5.1: calculating a corresponding working life N.sub.f-i by the life prediction model according to the junction temperature fluctuation T.sub.jm-i and the average junction temperature ΔT.sub.j-i recorded in the i-th power cycle; S5.2: taking a reciprocal of N.sub.f-i and adding them up to a j-th power cycle (i≤j) to obtain the aging characteristic parameter $D_j=\underset{i=1}{\overset{j}{.Math.}}\frac{1}{N_{f-i}}$ of the IGBT module; S5.3: taking D.sub.j to characterize an aging degree of the IGBT during the j-th power cycle; S5.4: when D.sub.j=1, according to the Miner theory, the IGBT is considered to be invalid at this time.

6. A system for characterizing IGBT module aging based on the Miner theory, comprising: a life prediction model building module configured to establish a life prediction model that takes a junction temperature fluctuation and an average junction temperature as inputs; a measurement module configured to measure a data of a chip junction temperature of an IGBT module; a recording module configured to record the junction temperature fluctuation and the average junction temperature of each power cycle; a life prediction module configured to perform one life prediction in each power cycle based on the life prediction model; an aging characterization module configured to take a reciprocal of a predicted life corresponding to each power cycle and add them to obtain an aging characteristic parameter of the IGBT module.

7. The system of claim 6, wherein the life prediction model building module is configured to perform a temperature cycling aging experiment on a group of IGBT modules of a same model, and control a temperature of an IGBT to prevent an aging of the IGBT modules from affecting their own temperature; according to the junction temperature fluctuation T.sub.jm and the average junction temperature ΔT.sub.j of the IGBT modules and a corresponding working life N.sub.f, the life prediction model $N_f=A\Delta T_j^{\alpha }{e}^{\frac{E_a}{k_B\left(T_{\mathrm{jm}}+273\right)}}$ is established, wherein A and α are constants to be fitted, E.sub.a is an activation energy, and k.sub.B is Boltzmann constant.

8. The system of claim 7, wherein the recording module is configured to record a maximum junction temperature of an i-th power cycle as T.sub.jmax-i, and record a minimum junction temperature of the i-th power cycle as T.sub.jmin-i; the junction temperature fluctuation ΔT.sub.j-i of the i-th power cycle is calculated by ΔT.sub.j-i=T.sub.jmax-i−T.sub.jmin-i; and the average junction temperature T.sub.jm-i of the i-th power cycle is calculated by T.sub.jm-i=(T.sub.jmax-i+T.sub.jmin-i)/2.

9. The system of claim 8, wherein the aging characterization module is configured to calculate a corresponding working life N.sub.f-i from the life prediction model according to the junction temperature fluctuation T.sub.jm-i and the average junction temperature ΔT.sub.j-i recorded in the i-th power cycle; a reciprocal of N.sub.f-i is taken and added up to a j-th power cycle (i≤j) to obtain the aging characterization parameter $D_j=\underset{i=1}{\overset{j}{.Math.}}\frac{1}{N_{f-i}}$ of the IGBT modules; D.sub.j is taken to characterize an aging degree of the IGBT during the j-th power cycle; and when D.sub.j=1, according to the Miner theory, it is considered that the IGBT is invalid at this time.

10. A computer-readable storage medium, with a computer program stored thereon, wherein the computer program implements the steps of the method of claim 1 when the computer program is executed by a processor.

11. A computer-readable storage medium, with a computer program stored thereon, wherein the computer program implements the steps of the method of claim 2 when the computer program is executed by a processor.

12. A computer-readable storage medium, with a computer program stored thereon, wherein the computer program implements the steps of the method of claim 3 when the computer program is executed by a processor.

13. A computer-readable storage medium, with a computer program stored thereon, wherein the computer program implements the steps of the method of claim 4 when the computer program is executed by a processor.

14. A computer-readable storage medium, with a computer program stored thereon, wherein the computer program implements the steps of the method of claim 5 when the computer program is executed by a processor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0042] FIG. 1 is a schematic flowchart of a method for characterizing IGBT module aging based on Miner theory provided by an embodiment of the invention.

[0043] FIG. 2 is a life prediction model provided by an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

[0044] In order to make the objects, technical solutions, and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying figures and embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention, and are not intended to limit the invention. In addition, the technical features involved in the various embodiments of the invention described below may be combined with each other as long as there is no conflict with each other.

[0045] FIG. 1 shows a schematic flowchart of a method for characterizing IGBT module aging based on Miner theory provided by an embodiment of the invention, including the following steps:

[0046] S1: establishing a life prediction model with a junction temperature fluctuation T.sub.jm and an average junction temperature ΔT.sub.j as inputs;

[0047] in an embodiment of the invention, as shown in FIG. 2, in step S1, the specific method of establishing the life prediction model with the junction temperature fluctuation T.sub.jm and the average junction temperature ΔT.sub.j as inputs is as follows:

[0048] S1.1: performing a temperature cycle aging experiment on a group of IGBT modules of a same model, and controlling a temperature of an IGBT via a thermostat to prevent an aging of the IGBT modules from affecting their own temperature;

[0049] wherein a temperature of the IGBT is controlled using a thermostat. At this time, the IGBT does not generate heat by itself, so the junction temperature fluctuation and the average junction temperature during the aging process may be strictly controlled to make the prediction result more accurate.

[0050] S1.2: establishing a life prediction model

[00005]$N_f=A\Delta T_j^{\alpha }{e}^{\frac{E_a}{k_B\left(T_{\mathrm{jm}}+273\right)}}$

according to the junction temperature fluctuation T.sub.jm and the average junction temperature ΔT.sub.j of the IGBT modules and a corresponding working life N.sub.f, wherein A and α are constants to be fitted, E.sub.a is an activation energy, E.sub.a=9.89×10.sup.−20 J, k.sub.B is Boltzmann constant, and k.sub.B=1.38×10.sup.−23 J/K.

[0051] S2: measuring a chip junction temperature data of the IGBT modules using an infrared thermometer;

[0052] in an embodiment of the invention, in step S2, the specific method of measuring the chip junction temperature data of the IGBT modules using an infrared thermometer is as follows:

[0053] S2.1: measuring a chip junction temperature of an IGBT module to be tested when the IGBT module is disconnected in a working state and recording the chip junction temperature as T.sub.jmax;

[0054] since an IGBT chip is constantly changing during operation, when the IGBT is turned on, due to the influence of the on voltage drop and the working current, the IGBT chip itself generates heat, thus causing junction temperature to rise. When the IGBT is disconnected, since the working current is basically zero, the chip basically does not generate heat, and chip temperature is dropped at this time. Therefore, when the IGBT is switched from on to off, the IGBT has maximum junction temperature, and when the IGBT is switched from off to on, the IGBT has minimum junction temperature.

[0055] S2.2: measuring a chip junction temperature when the IGBT module is turned on and recording the chip junction temperature as T.sub.jmin.

[0056] S3: recording the junction temperature fluctuation T.sub.jm and the average junction temperature ΔT.sub.j of each power cycle;

[0057] in an embodiment of the invention, in step S3, the specific method of recording the junction temperature fluctuation T.sub.jm and the average junction temperature ΔT.sub.j of each power cycle is as follows:

[0058] S3.1: recording a maximum junction temperature and a minimum junction temperature recorded in an i-th power cycle as T.sub.jmax-i and T.sub.jmin-i respectively;

[0059] S3.2: calculating a junction temperature fluctuation of the i-th power cycle by ΔT.sub.j-i=T.sub.jmax-i−T.sub.jmin-i;

[0060] S3.3: calculating an average junction temperature of the i-th power cycle by ΔT.sub.jm-i=(T.sub.jmax-i+T.sub.jmin-i)/2.

[0061] S4: performing one life prediction in each power cycle based on the life prediction model;

[0062] S5: taking a reciprocal of a predicted life corresponding to each power cycle and adding them to obtain an aging characteristic parameter D of the IGBT module.

[0063] In an embodiment of the invention, in step S5, the specific method of taking the reciprocal of the predicted life corresponding to each power cycle and adding them to obtain the aging characterization parameter D of the IGBT module is as follows:

[0064] S5.1: calculating a corresponding working life N.sub.f-i by the life prediction model according to the junction temperature fluctuation T.sub.jm-i and the average junction temperature ΔT.sub.j-i recorded in the i-th power cycle;

[0065] S5.2: taking a reciprocal of N.sub.f-i and adding them up to a j-th power cycle (i≤j) with the formula

[00006]$D_j=\underset{i=1}{\overset{j}{.Math.}}\frac{1}{N_{f-i}};$

[0066] S5.3: taking D.sub.j to characterize an aging degree of an IGBT during the j-th power cycle;

[0067] S5.4: when D.sub.j=1, according to Miner theory, the IGBT is considered to be invalid at this time.

[0068] The Miner theory is specifically: if the number of cycles of the material under an alternating stress σ.sub.1 is n.sub.1, the number of cycles under σ.sub.2 is n.sub.2 . . . and the number of cycles under σ.sub.N is n.sub.N. According to the life prediction model, it may be found that the invalid cycle life corresponding to σ.sub.1 is N.sub.f-1, the invalid cycle life corresponding to σ.sub.2 is N.sub.f-2 . . . and the invalid cycle life corresponding to σ.sub.N is N.sub.f-N. According to Miner theory, when

[00007]$\underset{i=1}{\overset{j}{.Math.}}\frac{n_i}{N_{f-i}}=1,$

it may be considered that the material is invalid. Using an analogy method to refine the theory, it is considered that the fatigue degree consumed by each cycle is 1/N.sub.i, and the current fatigue degree consumed by all cycles is recorded and accumulated to obtain the current aging degree of the IGBT module.

[0069] It should be noted that, according to implementation needs, each step/component described in the present application may be split into more steps/components, or two or a plurality of steps/components or partial operations of the steps/components may be combined into new steps/components to achieve the object of the invention.

[0070] It is easy for those skilled in the art to understand that the above are only preferred embodiments of the invention and are not intended to limit the invention. Any modification, equivalent replacement, and improvement made within the spirit and principles of the invention should be included in the protection scope of the invention.