IGBT loss and junction temperature calculation method

Abstract

The invention relates to the technical field of power electronic converter power module loss and junction temperature calculation, in particular to an IGBT loss and junction temperature calculation method, which adopts a junction temperature iteration method, sets an initial junction temperature, and then updates the junction temperature after each loss calculation and junction temperature calculation until the junction temperature is stable. And after the junction temperature is stable, calculating the instantaneous junction temperature of the IGBT by using the transient thermal resistance characteristic and the instantaneous loss average value of the IGBT to obtain an instantaneous junction temperature sequence and the instantaneous highest junction temperature of the IGBT. Through the calculation method, the problem of insufficient accuracy can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power module loss and junction temperature calculation of power electronic converters, and particularly to a method for calculating IGBT loss and junction temperature. Background Art

[0002] As a core component of power components of power electronic converters, the reliability of IGBT (Insulated Gate Bipolar Transistor) is crucial for the reliability of power electronic converters. The reliability of IGBT is closely related to its junction temperature. The higher the junction temperature, the shorter the life of IGBT. And when the operating temperature of IGBT exceeds the maximum junction temperature, the device may be damaged and fail. In order to improve the market competitiveness of power electronic converters, during product R & D and design, on the basis of meeting the reliability target, designers expect a more appropriate design margin to reduce the cost of converter power components. However, when the design margin is insufficient, the reliability of the converter will have problems. Therefore, the accurate calculation of the junction temperature of converter IGBT under various working conditions has become a difficult problem in the design of power components of power electronic converters. The accurate calculation of IGBT loss and junction temperature is crucial for the design of power components of power electronic converters.

[0003] In recent years, researchers have proposed some methods for calculating the junction temperature of IGBT. Zhang Yi, Wang Huai, etc. proposed a simplified thermal modeling method applicable to periodic power losses of modular multilevel inverters, that is, using a semi-sine loss curve to transform and discretely equivalent the irregular loss task surface of IGBT, and realizing a relatively accurate calculation of the junction temperature fluctuation of IGBT. J.J. Nelson, G. Venkataramanan, etc. transformed both the power loss function and the thermal network model into the frequency domain, and then calculated the IGBT junction temperature based on frequency domain analysis. M. Ouhab, 2. Khatir, etc. considered factors such as modulation strategy and power factor in the calculation of IGBT power loss in motor traction, improving the accuracy of junction temperature calculation. Wang Xiping, Li Zhigang, etc. used rectangular pulse loss to equivalent the original loss, and then combined with the thermal network for junction temperature iterative calculation, realizing a relatively fast calculation of the junction temperature.

[0004] In the currently proposed methods for calculating IGBT loss and junction temperature, the calculation of power loss mostly uses a semi-sine curve for equivalence, resulting in inaccurate loss calculation and further introducing errors into the junction temperature calculation; in addition, the current life models for reliability analysis mainly focus on junction temperature fluctuations, and only the maximum and minimum junction temperature values need to be calculated. Therefore, the estimation of the junction temperature at other time points leads to a large amount of computational redundancy in iterative calculations, seriously increasing the calculation time and computational amount of the junction temperature.

[0005] Generally, power devices are temperature-sensitive devices, that is, they have a certain temperature coefficient. For example, IGBT is a typical positive temperature coefficient device. At high temperature Tj When = 150 °C, the saturation voltage drop of the IGBT is T j It is more than 1.2 times that at = 25 °C, and the switching speed also has the same characteristics. When calculating the temperature, assume a temperature to estimate the temperature rise, and based on this assumed temperature condition, estimate a junction temperature according to the power consumption and thermal resistance. Generally, this is not the assumed temperature. Due to the temperature characteristics of the IGBT, the power consumption at this assumed temperature needs to be adjusted and iterative calculations are required to approach the final output junction temperature and the corresponding power consumption at that junction temperature to make the result more accurate. Traditional iteration using manual calculation is time-consuming, and generally, a large amount of work is required to achieve an iteration within 1 °C.

[0006] In addition, in the prior art, a Chinese invention patent document with the publication number CN116992819A and the publication date of November 3, 2023 is also proposed. The technical solution disclosed in this patent document is as follows: An IGBT junction temperature estimation method and system, the method includes: measuring and collecting the bus voltage waveform of the IGBT module, and inputting the bus voltage waveform into a signal processing circuit for preprocessing to obtain temperature-sensitive electrical parameters; collecting the instantaneous current waveform of the IGBT module, and calculating the loss of the IGBT module according to the working state of the IGBT module and the instantaneous current waveform; based on the loss and thermal resistance and heat capacity parameters, constructing a thermal resistance network model to obtain the temperature distribution of each layer in the IGBT module, and estimating the initial IGBT junction temperature through the temperature distribution of each layer; based on the temperature-sensitive electrical parameters, optimizing the thermal resistance network model to obtain the final IGBT junction temperature.

[0007] The above technical solution is aimed at the online monitoring and estimation of the IGBT junction temperature in actual products. The calculation of the IGBT loss is relatively rough, the update of the junction temperature does not participate in the calculation of the loss, and no junction temperature iteration is formed, resulting in insufficient calculation accuracy. Summary of the Invention

[0008] To solve the above technical problems, the present invention proposes an IGBT loss and junction temperature calculation method, which can effectively solve the problem of insufficient accuracy.

[0009] The present invention is realized by adopting the following technical solutions:

[0010] An IGBT loss and junction temperature calculation method includes the following steps:

[0011] Step S 1 . Set the initial junction temperature, and through simulation, calculate the average loss at the initial junction temperature. The average loss includes average conduction loss, average turn-on loss, and average turn-off loss;

[0012] Step S 2. Set the radiator temperature according to the IGBT thermal resistance parameter, use the average loss to calculate the IGBT junction temperature;

[0013] Step S 3 . Determine whether the difference in junction temperature between two consecutive times is less than the threshold value. If not, recalculate the junction temperature iteratively; if so, obtain the accurate junction temperature of the IGBT;

[0014] Step S 4 . Calculate the IGBT instantaneous loss sequence at the accurate junction temperature, where the instantaneous loss sequence = instantaneous turn-on loss data sequence + instantaneous turn-off loss data sequence + conduction loss data sequence;

[0015] Step S 5 . Based on the IGBT instantaneous loss sequence in Step S 4 obtain the average value of the IGBT instantaneous loss at the accurate junction temperature;

[0016] Step S 6 . Based on the IGBT instantaneous thermal resistance model, use the average value of the IGBT instantaneous loss to solve the instantaneous junction temperature, and obtain the IGBT instantaneous junction temperature sequence and the instantaneous maximum junction temperature.

[0017] The said Step S 1 specifically includes the following steps:

[0018] Step S 11 . Through simulation, obtain the voltage data of the IGBT and the current Ic data sequence, and set the initial junction temperature;

[0019] Step S 12 . At the initial junction temperature, calculate the corresponding voltage Vce data sequence according to the obtained current Ic data sequence;

[0020] Step S 13 . Calculate the conduction loss data sequence according to the current Ic data sequence and the voltage Vce data sequence;

[0021] Step S 14 . Based on the conduction loss data sequence, calculate the average conduction loss over a long period;

[0022] Step S 15 . Determine the turn-on moment and turn-off moment of the IGBT;

[0023] Step S 16 . Calculate the instantaneous turn-on loss energy and the instantaneous turn-off loss energy, and calculate the total loss energy at the turn-on moment and the total loss energy at the turn-off moment;

[0024] Step S 17 . Solve the average turn-on loss and the average turn-off loss over a long period.

[0025] Step S 11 Specifically: Model the power electronic converter through simulation software, run the simulation under a certain working condition to obtain the voltage data and the current Ic data sequence of the IGBT under this working condition, and set the initial junction temperature.

[0026] The method for calculating the voltage Vce data sequence is as follows: Based on the original data curve of Ic-Vce, establish a fourth-order fitting curve of Ic-Vce; use the Newton-Raphson iteration algorithm to solve the voltage Vce data sequence corresponding to the current Ic data sequence, and calculate to obtain the voltage Vce data sequence.

[0027] The method for calculating the conduction loss data sequence is: Multiply the current Ic data sequence and the voltage Vce data sequence point by point to calculate the conduction loss data sequence.

[0028] Step S 15 Specifically: Use the mutation in the acquired voltage data and the positive and negative of the current Ic data sequence to determine the turn-on moment and turn-off moment of the IGBT.

[0029] The calculation methods for the instantaneous turn-on loss energy and the instantaneous turn-off loss energy are as follows: Based on the original data curves of Eon-Ic, Eon-Rg, Eoff-Ic, and Eoff-Rg, establish fourth-order fitting curves respectively; use the trend extrapolation method and linear interpolation to solve the instantaneous turn-on loss energy and the instantaneous turn-off loss energy.

[0030] Step S 5 Specifically, it includes the following steps: Determine the window width of the sliding window, and based on the IGBT instantaneous loss sequence, perform sliding calculation on the instantaneous loss sequence within the window to obtain the average loss of the IGBT instantaneous loss.

[0031] The method for determining the window width of the sliding window is as follows:

[0032] When it is an AC conversion system, the window width T w is:

[0033] T w = T AC / 4;

[0034] When it is a DC conversion system, the window width T w is:

[0035] T w = T s *15;

[0036] In the formula, TAC is the period of the AC system, and T s is the switching period.

[0037] The method for calculating the instantaneous junction temperature is:

[0038] T jins = P ins × Z thjc + T javg

[0039]

[0040] Wherein, T jins is the instantaneous junction temperature, P ins is the average value of the IGBT instantaneous loss at the accurate junction temperature, Z thjc is the instantaneous thermal resistance value; r i and τ i are the instantaneous thermal resistance parameters respectively, t per is the fluctuation period of the junction temperature, T javg is the accurate junction temperature value.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. The present invention adopts a junction temperature iteration method, sets an initial junction temperature, and then updates the junction temperature after each loss calculation and junction temperature calculation until the junction temperature is stable. After the junction temperature is stable, the instantaneous junction temperature of the IGBT is calculated by using the transient thermal resistance characteristic and the average value of the instantaneous loss of the IGBT, and the instantaneous highest junction temperature of the IGBT can be obtained, which makes the thermal stress analysis of the IGBT module more accurate.

[0043] 2. Since the characteristics of the switching device are not included in the simulation model, the Vce voltage when the IGBT is turned on is inaccurate. Therefore, the present invention calculates the corresponding Vce data sequence by obtaining the current Ic data sequence, which is convenient for improving the calculation accuracy.

[0044] 3. The present invention aims at the calculation of the IGBT loss and junction temperature in the R & D and design stage of the power electronic converter product, and the data is obtained through accurate simulation modeling, and sufficient simulation analysis can be carried out for various different working conditions.

[0045] 4. When calculating the conduction loss, the present invention takes into account the Ic-Vce characteristic and the influence of the junction temperature. By extracting the characteristic data, fitting the characteristic curve with a quartic polynomial, and calculating Vce by the Newton-Raphson iteration, the accuracy of the loss calculation is ensured. When calculating the turn-on and turn-off losses, the influences of Vce, Ic and Rg are taken into account, and the calculation accuracy is improved by using the trend extrapolation method and linear interpolation.

[0046] 5. By reasonably selecting the window width of the sliding window, the present invention can optimize the dynamic response and steady-state accuracy while ensuring the system performance for both the AC conversion system and the DC conversion system. Description of the Drawings

[0047] The present invention will be further described in detail below in conjunction with the specification drawings and specific embodiments, where:

[0048] Figure 1 is a schematic flow chart of the present invention;

[0049] Figure 2 is a schematic diagram of the voltage data and current Ic data sequence of the IGBT obtained in the present invention;

[0050] Figure 3 is the original data curve of Ic-Vce in the present invention;

[0051] Figure 4 is the fourth-order fitting curve of Ic-Vce in the present invention;

[0052] Figure 5 is the original data curve of Eon-Ic in the present invention;

[0053] Figure 6 is the original data curve of Eon-Rg in the present invention;

[0054] Figure 7 is a schematic diagram of the voltage waveform (long period) when the IGBT is switched in the present invention;

[0055] Figure 8 is a schematic diagram of the voltage waveform (amplified, short time) when the IGBT is switched in the present invention;

[0056] Figure 9 is a schematic diagram of the transient thermal resistance characteristic in the present invention. Specific Embodiments

[0057] Example 1

[0058] As a basic embodiment of the present invention, the present invention includes a method for calculating IGBT loss and junction temperature, comprising the following steps:

[0059] Step S 1 . Set the initial junction temperature, and calculate the average loss at the initial junction temperature through simulation. The average loss includes average conduction loss, average turn-on loss, and average turn-off loss.

[0060] Step S 2 . According to the IGBT thermal resistance parameters, use the average loss to set the radiator temperature and calculate the IGBT junction temperature.

[0061] Step S 3 . Judge whether the difference value of the junction temperature for two consecutive times is less than the threshold value. If not, re-iterate to calculate the junction temperature; if so, obtain the accurate junction temperature of the IGBT.

[0062] Step S4 . Calculate the IGBT instantaneous loss sequence at the accurate junction temperature, where the instantaneous loss sequence = instantaneous turn-on loss data sequence + instantaneous turn-off loss data sequence + conduction loss data sequence.

[0063] Step S 5 . Based on the IGBT instantaneous loss sequence in Step S 4 , obtain the average value of the IGBT instantaneous loss at the accurate junction temperature.

[0064] Step S 6 . Based on the instantaneous thermal resistance model of the IGBT, use the average value of the IGBT instantaneous loss to solve for the instantaneous junction temperature, and obtain the IGBT instantaneous junction temperature sequence and the instantaneous maximum junction temperature.

[0065] Embodiment 2

[0066] As a preferred embodiment of the present invention, the present invention includes an IGBT loss and junction temperature calculation method, comprising the following steps:

[0067] Step S 1 . Set the initial junction temperature, and through simulation, calculate the average loss at the initial junction temperature, where the average loss includes average conduction loss, average turn-on loss, and average turn-off loss.

[0068] Step S 2 . According to the IGBT thermal resistance parameters, use the average loss to set the radiator temperature and calculate the IGBT junction temperature.

[0069] Step S 3 . Determine whether the difference in junction temperature between two consecutive times is less than the threshold value. If not, re-iterate to calculate the junction temperature; if so, obtain the accurate junction temperature of the IGBT.

[0070] Step S 4 . Calculate the IGBT instantaneous loss sequence at the accurate junction temperature, where the instantaneous loss sequence = instantaneous turn-on loss data sequence + instantaneous turn-off loss data sequence + conduction loss data sequence.

[0071] Step S 5 . Based on the IGBT instantaneous loss sequence in Step S 4 , obtain the average value of the IGBT instantaneous loss at the accurate junction temperature. Specifically, the window width of the sliding window can be determined, and based on the IGBT instantaneous loss sequence, the average loss within the window is calculated by sliding the instantaneous loss sequence within the window to obtain the average value of the IGBT instantaneous loss.

[0072] Among them, the method for determining the window width of the sliding window is:

[0073] When it is an AC conversion system, the window width T w is:

[0074] T w = T AC / 4;

[0075] When it is a DC conversion system, the window width T w is:

[0076] T w = T s * 15;

[0077] In the formula, TAC is the period of the AC system, and T s is the switching period.

[0078] Step S 6 . Based on the IGBT instantaneous thermal resistance model, use the average value of the IGBT instantaneous loss to solve the instantaneous junction temperature, and obtain the IGBT instantaneous junction temperature sequence and the instantaneous maximum junction temperature. Among them, the calculation method of the instantaneous junction temperature is:

[0079] T jins = P ins × Z thjc + T javg

[0080]

[0081] In the formula, T jins is the instantaneous junction temperature, P ins is the average value of the IGBT instantaneous loss at the accurate junction temperature, Z thjc is the instantaneous thermal resistance value; r i and τ i are the instantaneous thermal resistance parameters respectively, t per is the fluctuation period of the junction temperature, and T javg is the accurate junction temperature value.

[0082] Embodiment 3

[0083] As another preferred embodiment of the present invention, the present invention includes an IGBT loss and junction temperature calculation method, which includes the following steps:

[0084] Step S 1 . Set the initial junction temperature, and through simulation, calculate the average loss at the initial junction temperature. The average loss includes the average conduction loss, the average turn-on loss, and the average turn-off loss. Specifically, it includes the following steps:

[0085] Step S 11 . Through simulation, obtain the voltage data and the current Ic data sequence of the IGBT, and set the initial junction temperature.

[0086] Step S 12.At the initial junction temperature, the corresponding voltage Vce data sequence is calculated according to the obtained current Ic data sequence. Specifically, the corresponding voltage Vce data sequence can be obtained by looking up the obtained current Ic data sequence in the original data curve of Ic-Vce. Among them, the original data curve of Ic-Vce is the characteristic curve of the IGBT itself and can be taken from the manufacturer's data sheet of the IGBT. Ic is the current and Vce is the voltage.

[0087] Step S 13 .According to the current Ic data sequence and the voltage Vce data sequence, the current Ic data sequence and the voltage Vce data sequence are multiplied point by point to calculate the conduction loss data sequence.

[0088] Step S 14 .Based on the conduction loss data sequence, the average conduction loss over a long period is calculated.

[0089] Step S 15 .Determine the turn-on time and turn-off time of the IGBT.

[0090] Step S 16 .Calculate the instantaneous turn-on loss energy and the instantaneous turn-off loss energy, and calculate the total turn-on loss energy and the total turn-off loss energy at the turn-on time. Specifically, based on the original data curves of Eon-Ic, Eon-Rg, Eoff-Ic, and Eoff-Rg, which are the characteristic curves of the IGBT itself and can be taken from the manufacturer's data sheet of the IGBT. Among them, Eon is the instantaneous turn-on loss energy, Eoff is the instantaneous turn-off loss energy, Rg is the resistance, and Ic is the current.

[0091] Step S 17 .Solve for the average turn-on loss and the average turn-off loss over a long period.

[0092] Step S 2 .According to the IGBT thermal resistance parameter, using the average loss, set the radiator temperature and calculate the IGBT junction temperature.

[0093] Step S 3 .Determine whether the difference in junction temperature between two consecutive times is less than the threshold value. If not, recalculate the junction temperature iteratively; if so, obtain the accurate junction temperature of the IGBT.

[0094] Step S 4 .Calculate the IGBT instantaneous loss sequence at the accurate junction temperature, where the instantaneous loss sequence = instantaneous turn-on loss data sequence + instantaneous turn-off loss data sequence + conduction loss data sequence.

[0095] Step S 5 .Based on Step S 4The IGBT instantaneous loss sequence is used to obtain the average value of the IGBT instantaneous loss at the accurate junction temperature.

[0096] Step S 6 . Based on the IGBT instantaneous thermal resistance model, the instantaneous junction temperature is solved by using the average value of the IGBT instantaneous loss, and the IGBT instantaneous junction temperature sequence and the instantaneous maximum junction temperature are obtained.

[0097] Embodiment 4

[0098] As the best implementation mode of the present invention, referring to the attached Figure 1 of the specification, the present invention includes a method for calculating the IGBT loss and junction temperature, including the following steps:

[0099] Step S 1 . Set the initial junction temperature, and through simulation, calculate the average loss at the initial junction temperature. The average loss includes the average conduction loss, the average turn-on loss, and the average turn-off loss. Specifically, it includes the following steps:

[0100] Step S 11 . Model the power electronic converter through simulation software. Referring to the attached Figure 2 of the specification, run the simulation under a certain working condition to obtain the fine voltage and current data of the IGBT under this working condition; set the initial junction temperature.

[0101] Step S 12 . At the initial junction temperature, according to the obtained current Ic data sequence, that is, the current data in Step S 11 , calculate the corresponding voltage Vce data sequence.

[0102] Referring to the attached Figure 3 of the specification, the existing method for obtaining the voltage Vce data sequence is: take points on the original data curve of Ic-Vce, store the data points, and then look up the value of Vce according to Ic. The values between two data points need to be interpolated. If fewer points are taken, such as taking 10 points on the curve, the calculation accuracy is insufficient; if more points are taken, such as taking 100 points, the workload of data extraction is increased and more storage resources are required. Among them, the original data curve of Ic-Vce is the characteristic curve of the IGBT itself and can be taken from the manufacturer's data manual of the IGBT.

[0103] Based on this, the method adopted by the present invention is: based on the original data curve of Ic-Vce, take an appropriate number of points on the original data curve, and then adopt a fourth-degree polynomial to fit the curve:

[0104] I C = a1*V CE 4 + b1*V CE 3 + c1*VCE 2 + d1 * V CE + e1. In this way, only five values of a1, b1, c1, d1, and e1 need to be stored to obtain the fourth-order fitting curve of Ic-Vce of the original data curve, such as the green curve in the attached Figure 4 to the specification. After obtaining the fourth-order fitting curve of Ic-Vce, the Newton-Raphson iteration algorithm is used to solve the voltage Vce data sequence corresponding to the current Ic data sequence, and the voltage Vce data sequence is calculated.

[0105] Step S 13 . Multiply the current Ic data sequence and the voltage Vce data sequence point by point to calculate the conduction loss data sequence.

[0106] Step S 14 . Based on the conduction loss data sequence, calculate the average conduction loss over a long period.

[0107] Step S 15 . Use the mutation in the acquired voltage data and the positive and negative of the current Ic data sequence to determine the turn-on moment and turn-off moment of the IGBT.

[0108] Step S 16 . Based on the original data curves of Eon-Ic, Eon-Rg, Eoff-Ic, and Eoff-Rg, establish fourth-order fitting curves respectively. Refer to the attached Figure 5 to the specification and the attached Figure 6 to the specification. The original data curves of Eon-Ic, Eon-Rg, Eoff-Ic, and Eoff-Rg are the characteristic curves of the IGBT itself and can be obtained from the manufacturer's data sheet of the IGBT. Similar to Step S 12 , extract data points, fit the curves. After obtaining the fourth-order fitting curves, use the trend extrapolation method and linear interpolation to solve the instantaneous turn-on loss energy and instantaneous turn-off loss energy, calculate the total turn-on loss energy at the turn-on moment and the total turn-off loss energy at the turn-off moment, that is, the total energy of the turn-on loss or turn-off loss within a period (a relatively long time compared to the switching time), and obtain the instantaneous turn-on loss data sequence and the instantaneous turn-off loss data sequence.

[0109] Step S 17 . Refer to the attached Figure 7 to the specification and the attached Figure 8 to the specification. Based on the total turn-on loss energy at the turn-on moment and the total turn-off loss energy at the turn-off moment, divide by the total duration of the calculated waveform to solve the average turn-on loss and average turn-off loss over a long period.

[0110] Step S 2.Based on the IGBT thermal resistance parameters, set the radiator temperature using the average loss, and calculate the IGBT junction temperature. Among them, the IGBT thermal resistance parameters can be obtained from the data sheet provided by the manufacturer. Among them, the method for calculating the junction temperature is:

[0111] t j = T h + P × (R thjc + R thch )

[0112] In the above formula, T j is the IGBT junction temperature, T h is the radiator temperature, P is the average loss of the IGBT, R thjc is the thermal resistance from the IGBT junction to the case, and R thch is the thermal resistance from the IGBT case to the radiator.

[0113] Step S 3 .Determine whether the difference between two consecutive junction temperatures is small enough, that is, whether it is less than the threshold. If not, recalculate the junction temperature iteratively; if so, obtain the accurate junction temperature of the IGBT. Specifically, the threshold can be 0.001, and the judgment method is:

[0114] |T 1 - T 2 | < 0.001,

[0115] In the formula, T 1 and T 2 are two consecutive junction temperatures.

[0116] Step S 4 .Calculate the IGBT instantaneous loss sequence at the accurate junction temperature. The instantaneous loss sequence = instantaneous turn-on loss data sequence + instantaneous turn-off loss data sequence + conduction loss data sequence.

[0117] Step S 5 .Determine the window width of the sliding window. Based on the IGBT instantaneous loss sequence in Step S 4 , perform a sliding calculation of the average loss on the instantaneous loss sequence within the window to obtain the average IGBT instantaneous loss. Among them, the method for determining the window width of the sliding window is:

[0118] When it is an AC conversion system, the window width T w is:

[0119] T w = T AC / 4;

[0120] When it is a DC conversion system, the window width T w is:

[0121] Tw = T s * 15;

[0122] Wherein, TAC is the period of the AC system, and T s is the switching period.

[0123] Step S 6 . Refer to the attached Figure 9 to the specification. Based on the transient thermal resistance model of the IGBT, the transient junction temperature is solved by using the average value of the IGBT transient loss, and the transient junction temperature sequence and the transient maximum junction temperature of the IGBT are obtained. Among them, the calculation method of the transient junction temperature is as follows:

[0124] T jins = P ins × Z thjc + T javg

[0125]

[0126] Wherein, T jins is the transient junction temperature, P ins is the average value of the IGBT transient loss at the accurate junction temperature, Z thjc is the transient thermal resistance value; r i and τ i are respectively the transient thermal resistance parameters in the attached Figure 9 to the specification, t per is the fluctuation period of the junction temperature in the attached Figure 9 to the specification, and T javg is the accurate junction temperature value.

[0127] In summary, after reading the documents of the present invention, all other corresponding transformation schemes made by those of ordinary skill in the art without creative mental labor according to the technical solutions and technical concepts of the present invention shall fall within the scope protected by the present invention.

Claims

1. A method for calculating IGBT loss and junction temperature, characterized in that: The following steps are involved: Step S1. Setting an initial junction temperature, and calculating the average loss at the initial junction temperature through simulation, wherein the average loss includes an average conduction loss, an average turn-on loss, and an average turn-off loss; Step S2. According to the IGBT thermal resistance parameter, using the average loss, setting the heat sink temperature, and calculating the IGBT junction temperature; Step S3. Determine whether the junction temperature difference between two consecutive times is less than a threshold value. If not, recalculate the junction temperature iteratively; if so, obtain the accurate junction temperature of the IGBT; Step S4. Calculate the IGBT instantaneous loss sequence at the accurate junction temperature, wherein the instantaneous loss sequence = instantaneous turn-on loss data sequence + instantaneous turn-off loss data sequence + conduction loss data sequence; Step S5. Based on the IGBT instantaneous loss sequence in step S4, an average value of the IGBT instantaneous loss at an accurate junction temperature is obtained; Step S6. Based on the instantaneous thermal resistance model of the IGBT, the instantaneous junction temperature is solved by using the average instantaneous loss of the IGBT to obtain the instantaneous junction temperature sequence and the instantaneous maximum junction temperature of the IGBT.

2. The method for calculating IGBT loss and junction temperature according to claim 1, characterized in that: The step S1 specifically includes the following steps: Step S 11 .Acquire the voltage data and current Ic data sequence of the IGBT through simulation and set the initial junction temperature; Step S 12 . At the initial junction temperature, the corresponding voltage Vce data sequence is calculated based on the acquired current Ic data sequence; Step S 13 . According to the current Ic data sequence and the voltage Vce data sequence, the conduction loss data sequence is calculated; Step S 14 . Based on the conduction loss data series, calculate the average conduction loss over a long period; Step S 15 .Determine the turn-on and turn-off time of IGBT; Step S 16 . Calculate the instantaneous turn-on loss energy and the instantaneous turn-off loss energy, and calculate the total energy loss at the turn-on time and the total energy loss at the turn-off time; Step S 17 .Solve the average turn-on loss and average turn-off loss over a long period.

3. A method for calculating IGBT loss and junction temperature according to claim 2, characterized in that: Step S 11 Specifically, it means: modeling the power electronic converter through simulation software, running the simulation under a certain working condition to obtain the voltage data and current Ic data sequence of the IGBT under the working condition, and setting the initial junction temperature.

4. The method for calculating IGBT loss and junction temperature according to claim 2, characterized in that: The method for calculating the voltage Vce data sequence is as follows: based on the original data curve of Ic-Vce, establish the Ic-Vce quartic fitting curve; use the Newton-Raphaelite iterative algorithm to solve the current Ic data sequence corresponding to the voltage Vce data sequence, and calculate the voltage Vce data sequence.

5. The method for calculating IGBT loss and junction temperature according to claim 2, characterized in that: The calculation method of the conduction loss data sequence is: multiply the current Ic data sequence and the voltage Vce data sequence point by point to calculate the conduction loss data sequence.

6. The method for calculating IGBT loss and junction temperature according to claim 2, characterized in that: Step S 15 Specifically, it refers to: using the mutation in the acquired voltage data and the positive and negative of the current Ic data sequence to determine the turn-on and turn-off time of the IGBT.

7. The method for calculating IGBT loss and junction temperature according to claim 2, characterized in that: The calculation method of instantaneous turn-on loss energy and instantaneous turn-off loss energy is as follows: based on the original data curves of Eon-Ic, Eon-Rg, Eoff-Ic and Eoff-Rg, four-order fitting curves are established respectively; trend extrapolation method and linear interpolation are used to solve the instantaneous turn-on loss energy and instantaneous turn-off loss energy.

8. A method for calculating IGBT loss and junction temperature according to any one of claims 1 to 7, characterized in that: Step S5 specifically includes the following steps: determining the window width of the sliding window, and based on the IGBT instantaneous loss sequence, slidingly calculating the average loss of the instantaneous loss sequence in the window to obtain the average value of the IGBT instantaneous loss.

9. The method for calculating IGBT loss and junction temperature according to claim 8, characterized in that: The method for determining the window width of the sliding window is: When it is an AC conversion system, the window width T w for: T w =T AC / 4; When it is a DC conversion system, the window width T w for: T w =T s *15; Where TAC is the period of the AC system, T s is the switching cycle.

10. The method for calculating IGBT loss and junction temperature according to claim 1, characterized in that: The calculation method of the instantaneous junction temperature is: T jins =P ins ×Z thjc +T javg Where, T jins is the instantaneous junction temperature, P ins is the average instantaneous loss of the IGBT at the exact junction temperature, Z thjc is the instantaneous thermal resistance; r i and τ i They are the instantaneous thermal resistance parameters, t per is the fluctuation period of junction temperature, T javg is the accurate junction temperature value.

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