Quasi-online Identification Method and Junction Temperature Calibration Method and System for Aging Parameters of Power Modules

Abstract

A quasi-online identification method and junction temperature calibration method and system for aging parameters of a power module. The system includes: a first junction temperature calibration module, a second junction temperature calibration module, a first data fitting module, a second data fitting module, a first sampling module, a first measured junction temperature acquisition unit, an emergency stop control module, a second sampling module, a second measured junction temperature acquisition unit, an aging parameter acquisition module, and a correction unit. The method and system have relatively high accuracy in the acquired aging parameters and reduce the test difficulty.

Description

Technical Field

[0001] The present invention relates to the field of power semiconductor device testing, and particularly to a method and system for quasi-online identification of aging parameters and junction temperature calibration of a power module. Background Art

[0002] Junction temperature is an important parameter characterizing the working state and health state of a power semiconductor device. However, the chip in the power semiconductor device is encapsulated inside the module and operates in a high-voltage and high-current environment, so the junction temperature of the chip cannot be directly measured. Therefore, it is quite difficult to online monitor the junction temperature of the power semiconductor device under the working state, which is also a current research hotspot.

[0003] Traditional methods for detecting the junction temperature of a power semiconductor chip mainly focus on the research of SiIGBT, including four categories: physical contact method, optical measurement method, model prediction method, and extraction method of thermal sensitive electrical parameters (TSEPs). Currently, the method of thermal sensitive electrical parameters (TSEPs) is more widely used. Its core idea is to use the device to be measured itself as a temperature sensing component and establish a mapping model between temperature and external electrical variables. Among them, the large-current conduction voltage drop method has fast response, high resolution, and low invasiveness to the original inverter's hardware and software, and is currently the most promising real-time online monitoring technology for junction temperature.

[0004] The implementation process of the large-current conduction voltage drop method is as follows: Through laboratory calibration, the three-dimensional mapping relationship between the junction temperature T c and the conduction voltage drop V J under different working currents I CE is obtained. The junction temperature expression T J = f(I C , V CE ) is fitted from the three-dimensional data network. In the online working condition, by measuring the conduction current and conduction voltage drop of the power semiconductor chip in real time, and substituting the conduction current and conduction voltage drop obtained from the online test into T J = f(I C : V CE ), the online calculation of the junction temperature is realized.

[0005] However, most of the thermal sensitive electrical parameters are affected by the aging characteristics of the power module, which is a common challenge faced in the online monitoring of junction temperature using the thermal sensitive electrical parameter method. The influence of aging on the conduction voltage drop is mainly manifested in the conduction voltage drop V CEIncrease. To ensure the accuracy of the online monitoring results of the junction temperature during the entire life cycle of the power module, it is necessary to monitor and decouple the aging parameters during the long-term operation of the power module. However, the current research in this area is still in its infancy in the laboratory, and the main aging parameter identification methods are all measurement methods in the laboratory, lacking effective identification methods for the module in the installed state. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the problems of low accuracy and great test difficulty of the obtained aging parameters in the prior art, so as to provide a quasi-online identification method for aging parameters of a power module, a junction temperature calibration method and a system.

[0007] To solve the above technical problems, the present invention provides a quasi-online identification system for aging parameters of a power module, which is suitable for monitoring the junction temperature of the main power switch tube to be measured in the power module. The power module includes a bonding wire connected to the main power switch tube, and the system includes: a first junction temperature calibration module, which is suitable for injecting a first calibrated conduction current into the main power switch tube to be measured in the forward direction, and obtaining a first mapping relationship between the first calibrated conduction saturation voltage drop, the first calibrated conduction current of the main power switch tube to be measured, and the first calibrated junction temperature of the main power switch tube to be measured in the off-line state; a second junction temperature calibration module, which is suitable for injecting a second constant calibrated current into the main power switch tube to be measured, and obtaining a second mapping relationship between the second calibrated conduction saturation voltage drop and the second calibrated junction temperature of the main power switch tube to be measured in the off-line state, and the second constant calibrated current is much smaller than the first calibrated conduction current; a first data fitting module, which is suitable for fitting the data in the first mapping relationship to obtain a first functional relationship, where the first functional relationship takes the first calibrated conduction saturation voltage drop and the first calibrated conduction current as independent variables and the first calibrated junction temperature as the dependent variable; a second data fitting module, which is suitable for fitting the data in the second mapping relationship to obtain a second functional relationship, where the second functional relationship takes the second calibrated conduction saturation voltage drop as the independent variable and the second calibrated junction temperature as the dependent variable; a first sampling module, which is suitable for injecting a first test current into the main power switch tube to be measured in the forward direction in the converter in the quasi-online working state and obtaining the first test conduction voltage drop of the main power switch tube to be measured; a first test junction temperature acquisition unit, which is suitable for acquiring the first test junction temperature, and the first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first functional relationship; an emergency stop control module, which is suitable for applying a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state until the current in all the load inductors in the converter is all zero; the quasi-online working state satisfies that the power module is in the converter and the converter is in the self-check or standby state; a second sampling module, which is suitable for injecting a second test current into the main power switch tube to be measured in the converter in the quasi-online working state after the emergency stop control module applies a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state and obtaining the second test conduction voltage drop of the main power switch tube to be measured, and the second test current is equal to the second constant calibrated current; a second test junction temperature acquisition unit, which is suitable for acquiring the second test junction temperature, and the second test junction temperature is the value of the second calibrated junction temperature corresponding to the data of the second test conduction voltage drop in the second functional relationship.An aging parameter acquisition module, wherein the aging parameter acquisition module is adapted to acquire an equivalent resistance change parameter of the bonding wire at a characteristic temperature according to the second test junction temperature, the first test current, and the first test on-state voltage drop when the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than a threshold value. ;

[0008] Optionally, the aging parameter acquisition module includes: a first submodule, the first submodule is adapted to obtain the aging parameter according to the equivalent resistance change parameter ΔR (T t ), the resistance temperature coefficient k of the bonding wire, the second test junction temperature T C2 , characteristic temperature T t Get the junction temperature T of the bonding wire at the second test C2 The equivalent resistance change parameter ΔR(T C2 ), ΔR(T C2 )=ΔR(T t )*(1+k*(T C2 -T t ); a second submodule, the second submodule is adapted to conduct the voltage drop V according to the first test C1 , the first test current I C1 , the bonding wire is at the second test junction temperature T C2 The equivalent resistance change parameter ΔR(T C2 ) Get the first test calibration on-state voltage drop V Z1 , V Z1 =V C1 -ΔR(T C2 )*I C1 ; A third submodule, the third submodule is suitable for calibrating the conduction voltage drop V according to the first test Z1 , the first test current I C1 and the second test junction temperature T C2 And the first functional relationship obtains the equivalent resistance change parameter ΔR (T t ).

[0009] Optionally, a comparison module is provided, wherein the comparison module is adapted to compare whether an absolute value of a difference between the first test junction temperature and the second test junction temperature is greater than a threshold value.

[0010] Optionally, the threshold value is 1mA to 100mA.

[0011] Optionally, the main power switch tube includes an IGBT.

[0012] The present invention also provides a junction temperature calibration system, comprising: the quasi-online identification system for power module aging parameters of the present invention; and a correction unit, wherein the correction unit is suitable for calibrating the first functional relationship into a first corrected functional relationship according to the equivalent resistance change parameter.

[0013] Optionally, it further includes: an online sampling module, which is adapted to inject a third test current into the main power switch to be measured in the converter in the online working state in the forward direction and obtain the third test conduction voltage drop of the main power switch to be measured; an online junction temperature acquisition unit, which is adapted to obtain the online junction temperature of the main power switch to be measured according to the third test current, the third test conduction voltage drop and the first correction function relationship.

[0014] Optionally, the first function relationship is T B1 = f1(I B1 , V B1 ); the first correction function relationship is T B1 = f1(I B1 , V B1 - [ΔR(T t ) * (1 + k * (T B1 - T t )] * I B1 ); T B1 is the first calibrated junction temperature, I B1 is the first calibrated conduction current, T t is the characteristic temperature, k is the resistance temperature coefficient of the bonding wire, ΔR(T t ) is the equivalent resistance change parameter of the bonding wire at the characteristic temperature, V B1 is the first calibrated conduction saturation voltage drop.

[0015] Optionally, it further includes: a first condition judgment unit, which is adapted to judge whether the online operation time of the converter is greater than the time threshold; a second condition judgment unit, which is adapted to judge whether the converter meets the quasi-online working state; the first sampling module is adapted to inject a first test current into the main power switch to be measured in the converter in the quasi-online working state in the forward direction and obtain the first test conduction voltage drop of the main power switch to be measured when the online operation time of the converter is greater than the time threshold and the converter meets the quasi-online working state.

[0016] The present invention also provides a method for quasi-online identification of aging parameters of a power module, which is suitable for monitoring the junction temperature of the main power switch tube to be measured in the power module. The power module includes a bonding wire connected to the main power switch tube, and the method includes: Step S1: Inject a first calibrated conduction current into the main power switch tube to be measured in the forward direction, and obtain a first mapping relationship between the first calibrated conduction saturation voltage drop of the main power switch tube to be measured in the off-line state, the first calibrated conduction current, and the first calibrated junction temperature of the main power switch tube to be measured; Step S2: Fit the data in the first mapping relationship to obtain a first functional relationship, where the first functional relationship takes the first calibrated conduction saturation voltage drop and the first calibrated conduction current as independent variables and the first calibrated junction temperature as the dependent variable; Step S3: Inject a second constant calibrated current into the main power switch tube to be measured, and obtain a second mapping relationship between the second calibrated conduction saturation voltage drop of the main power switch tube to be measured in the off-line state and the second calibrated junction temperature of the main power switch tube to be measured, and the second constant calibrated current is much smaller than the first calibrated conduction current; Step S4: Fit the data in the second mapping relationship to obtain a second functional relationship, where the second functional relationship takes the second calibrated conduction saturation voltage drop as the independent variable and the second calibrated junction temperature as the dependent variable; Step S5: Inject a first test current into the main power switch tube to be measured in the converter in the quasi-online working state in the forward direction and obtain the first test conduction voltage drop of the main power switch tube to be measured; Step S6: Obtain the first test junction temperature, where the first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first functional relationship; Step S7: After obtaining the first test junction temperature, apply a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state until the current in all the load inductors in the converter is all zero; The quasi-online working state satisfies: the power module is in the converter, and the converter is in the self-check or standby state; Step S8: After applying the forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state, inject a second test current into the main power switch tube to be measured in the converter in the quasi-online working state and obtain the second test conduction voltage drop of the main power switch tube to be measured, and the second test current is equal to the second constant calibrated current; Step S9: Obtain the second test junction temperature, where the second test junction temperature is the value of the second calibrated junction temperature corresponding to the data of the second test conduction voltage drop in the second functional relationship; Step S10: When the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than the threshold, obtain the equivalent resistance change parameter of the bonding wire at the characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop.

[0017] Optionally, the step of obtaining the equivalent resistance change parameter of the bonding wire at the characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop includes: according to the equivalent resistance change parameter ΔR(T t) Resistance temperature coefficient k of the bonding wire, second test junction temperature T C2 Characteristic temperature T t Obtain the equivalent resistance change parameter ΔR(T C2 ) of the bonding wire at the second test junction temperature T C2 ),ΔR(T C2 ) = ΔR(T t ) * (1 + k * (T C2 - T t )); Suitable for obtaining the first test calibrated conduction voltage drop V C1 according to the first test conduction voltage drop V C1 , first test current I C2 and the equivalent resistance change parameter ΔR(T C2 ) of the bonding wire at the second test junction temperature T Z1 , V Z1 = V C1 - ΔR(T C2 ) * I C1 ; According to the first test calibrated conduction voltage drop V Z1 , first test current I C1 and the second test junction temperature T C2 and the first function relationship to obtain the equivalent resistance change parameter ΔR(T t ) at the characteristic temperature.

[0018] Optionally, the main power switch includes an IGBT.

[0019] The present invention also provides a junction temperature calibration method, including: the power module aging parameter quasi-online identification method of the present invention; calibrating the first function relationship to the first corrected function relationship according to the equivalent resistance change parameter.

[0020] Optionally, it further includes: injecting a third test current into the main power switch to be tested in the converter in the on-line working state and obtaining the third test conduction voltage drop of the main power switch to be tested; obtaining the on-line junction temperature of the main power switch to be tested according to the third test current, the third test conduction voltage drop and the first corrected function relationship.

[0021] Optionally, the first function relationship is T B1 = f1(I B1 , V B1 ); The first corrected function relationship is T B1 = f1(I B1 , V B1 - [ΔR(T t ) * (1 + k * (T B1 - T t )] * I B1 ); T B1 is the first calibrated junction temperature, IB1 is the first calibrated conduction current, T t is the characteristic temperature, k is the resistance temperature coefficient of the bonding wire, ΔR(T t ) is the equivalent resistance change parameter of the bonding wire at the characteristic temperature, V B1 is the first calibrated conduction saturation voltage drop.

[0022] Optionally, it further includes: before performing step S5, determining whether the online operation time of the converter is greater than the time threshold and whether the converter meets the quasi-online working state; after the online operation time of the converter is greater than the time threshold and the converter meets the quasi-online working state, performing step S5; if the online operation time of the converter is less than or equal to the time threshold, and / or if the converter does not meet the quasi-online working state, then a third test current is injected forward into the main power switch tube to be tested in the converter in the online working state and the third test conduction voltage drop of the main power switch tube to be tested is obtained, and the online junction temperature of the main power switch tube to be tested is obtained according to the third test current, the third test conduction voltage drop and the first function relationship.

[0023] The technical solution of the present invention has the following advantages:

[0024] The power module aging parameter quasi-online identification method provided by the technical solution of the present invention injects a first test current into the forward direction of the main power switch tube to be measured in the converter in the quasi-online working state and obtains the first test conduction voltage drop of the main power switch tube to be measured. The quasi-online working state satisfies that the power module is in the converter and the converter is in the self-check or standby state; the first test junction temperature is obtained. The first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first function relationship. After that, a forced turn-off signal is applied to all the main power switch tubes in the converter in the quasi-online working state until the current in all the load inductors in the converter is all zero. Since a forced turn-off signal is applied to all the main power switch tubes in the converter, the power switch tube unit enters the fast freewheeling mode, so that the current in the load inductor electrically connected to the main power switch tube to be measured quickly returns to zero. At this time, the branch where the load inductor electrically connected to the main power switch tube to be measured is disconnected and will not continue to damp and oscillate to zero, so that the time for applying the forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state is less. After that, a second test current is injected into the main power switch tube to be measured in the converter in the quasi-online working state and the second test conduction voltage drop of the main power switch tube to be measured is obtained. The second test current is equal to the second constant calibration current. The second test junction temperature is obtained. The second test junction temperature is the value of the second calibrated junction temperature corresponding to the data of the second test conduction voltage drop in the second function relationship. The data of the second test junction temperature obtained by the small current injection method after the emergency stop control is relatively accurate, that is, the small current method is used to calibrate the quasi-online junction temperature monitoring data to obtain the true value of the junction temperature of the main power switch tube to be measured in the aging state. When the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than the threshold, the equivalent resistance change parameter of the bonding wire at the characteristic temperature is obtained according to the second test junction temperature, the first test current, and the first test conduction voltage drop, so that the accuracy of the equivalent resistance change parameter of the bonding wire at the characteristic temperature is relatively high. Since the second test junction temperature is obtained by testing in the quasi-online state, it is not necessary to take out the main power switch tube to be measured during the use of the converter, and it is relatively easy to obtain the data of the second test junction temperature by the small current injection method after the emergency stop control, and the test difficulty is low.

[0025] The junction temperature calibration method provided by the technical solution of the present invention calibrates the first function relationship into a first corrected function relationship according to the equivalent resistance change parameter. Since the equivalent resistance change parameter of the bonding wire at the characteristic temperature is considered in the first corrected function relationship, the first corrected function relationship can accurately measure the junction temperature of the main power switch tube to be measured in the on-line state. Description of the Drawings

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a curve graph obtained by a junction temperature monitoring method in the prior art;

[0028] Figure 2 It is a power module aging parameter quasi-online identification system provided by an embodiment of the present invention;

[0029] Figure 3 It is a topological structure of an on-line operation of an inverter provided by an embodiment of the present invention;

[0030] Figure 4 It is a timing diagram provided by an embodiment of the present invention;

[0031] Figure 5 It is a junction temperature calibration system provided by an embodiment of the present invention;

[0032] Figure 6 It is a topological structure of on-line sampling provided by an embodiment of the present invention. Specific Embodiments

[0033] For the identification of aging parameters during the application of power modules, the current main research is mainly carried out under laboratory conditions using the constant pulse current method. The implementation method of the constant pulse current method is as follows: keep the power module conducting at a fixed ambient temperature, inject a short pulse constant current I, and measure the conduction voltage drop V CE1 , and calculate it with the conduction voltage drop V CE0 in the initial state of the healthy module to obtain the aging equivalent impedance Since the fixed ambient temperature and the fixed current source can only be realized under laboratory conditions, the test is difficult under on-line conditions, and this method has no application value under the service conditions of the equipment.

[0034] Another method is the inflection point method. The inflection point method utilizes the characteristic that there is an inflection point in the V' CE - I c curve (refer to Figure 1 ), and the aging characteristic parameters are measured based on the characteristic that V' CE is not sensitive to the change of the junction temperature (T J ) at the inflection point. Since the temperature limitation is reduced, it has certain on-line test conditions. However, the current at the inflection point is generally relatively small, and the voltage change caused by the degenerative impedance change is also relatively small, making the measurement relatively difficult. In addition, it is also difficult to ensure a constant current under on-line conditions.

[0035] On this basis, an embodiment of the present invention provides a quasi-online identification system for aging parameters of a power module, which is suitable for monitoring the junction temperature of the main power switch tube to be measured in the power module. The power module includes a bonding wire connected to the main power switch tube. Refer to Figure 2 , including:

[0036] A first junction temperature calibration module 100, which is suitable for injecting a first calibrated conduction current into the main power switch tube to be measured in the forward direction, and obtaining a first mapping relationship between the first calibrated conduction saturation voltage drop, the first calibrated conduction current of the main power switch tube to be measured, and the first calibrated junction temperature of the main power switch tube to be measured in the offline state;

[0037] A second junction temperature calibration module 200, which is suitable for injecting a second constant calibrated current into the main power switch tube to be measured, and obtaining a second mapping relationship between the second calibrated conduction saturation voltage drop and the second calibrated junction temperature of the main power switch tube to be measured in the offline state. The second constant calibrated current is much smaller than the first calibrated conduction current;

[0038] A first data fitting module 110, which is suitable for fitting the data in the first mapping relationship to obtain a first functional relationship. The first functional relationship takes the first calibrated conduction saturation voltage drop and the first calibrated conduction current as independent variables and the first calibrated junction temperature as the dependent variable;

[0039] A second data fitting module 210, which is suitable for fitting the data in the second mapping relationship to obtain a second functional relationship. The second functional relationship takes the second calibrated conduction saturation voltage drop as the independent variable and the second calibrated junction temperature as the dependent variable;

[0040] A first sampling module 300, which is suitable for injecting a first test current into the main power switch tube to be measured in the converter in the quasi-online working state in the forward direction and obtaining the first test conduction voltage drop of the main power switch tube to be measured;

[0041] A first test junction temperature acquisition unit 310, which is suitable for acquiring a first test junction temperature. The first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first functional relationship;

[0042] An emergency stop control module 400, which is suitable for applying a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state until the current in all the load inductors in the converter is all zero; The quasi-online working state satisfies: the power module is in the converter, and the converter is in the self-check or standby state;

[0043] A second sampling module 500, which is adapted to inject a second test current into a main power switch tube to be tested in a converter in a quasi-online working state and obtain a second test conduction voltage drop of the main power switch tube to be tested after the emergency stop control module applies a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state, wherein the second test current is equal to a second constant calibration current;

[0044] A second test junction temperature acquisition unit 510, which is adapted to acquire a second test junction temperature, and the second test junction temperature is a numerical value of a second calibrated junction temperature corresponding to data of the second test conduction voltage drop in a second functional relationship;

[0045] An aging parameter acquisition module 600, which is adapted to obtain an equivalent resistance change parameter of a bonding wire at a characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop when the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than a threshold.

[0046] Reference Figure 3 , the converter includes: a DC network, an AC network, and a bridge-type power switch tube circuit. The bridge-type power switch tube circuit has a plurality of power switch tube units, and each power switch tube unit includes: a main power switch tube and a diode reversely connected in parallel with the main power switch tube; the AC network includes a load inductor electrically connected to the main power switch tube, and the DC network includes a load resistor connected in series and a DC bus power supply U DC .

[0047] In one embodiment, taking a three-phase full-bridge converter as an example for illustration, reference Figure 3, the bridge power switch tube circuit in the converter includes a first power switch tube unit, a second power switch tube unit, a third power switch tube unit, a fourth power switch tube unit, a fifth power switch tube unit, and a sixth power switch tube unit. The first power switch tube unit includes a first main power switch tube T1 and a first diode D1 reversely connected in parallel with the first main power switch tube T1; the second power switch tube unit includes a second main power switch tube T2 and a second diode D2 reversely connected in parallel with the second main power switch tube T2; the third power switch tube unit includes a third main power switch tube T3 and a third diode D3 reversely connected in parallel with the third main power switch tube T3; the fourth power switch tube unit includes a fourth main power switch tube T4 and a fourth diode D4 reversely connected in parallel with the fourth main power switch tube T4; the fifth power switch tube unit includes a fifth main power switch tube T5 and a fifth diode D5 reversely connected in parallel with the fifth main power switch tube T5; the sixth power switch tube unit includes a sixth main power switch tube T6 and a sixth diode D6 reversely connected in parallel with the sixth main power switch tube T6. The collectors of the first main power switch tube T1, the third main power switch tube T3, and the fifth main power switch tube T5 are connected together and connected to the positive pole of the DC bus power supply U DC The emitters of the second main power switch tube T2, the fourth main power switch tube T4, and the sixth main power switch tube T6 are connected together and connected to the negative pole of the DC bus power supply U DC . The first main power switch tube T1, the second main power switch tube T2, the third main power switch tube T3, the fourth main power switch tube T4, the fifth main power switch tube T5, and the sixth main power switch tube T6 are all IGBTs (Insulated Gate Bipolar Transistors).

[0048] Figure 3 In , the power module in the present invention includes several pairs of power switch tube units formed at the upper bridge position and the lower bridge position. A pair of power switch tube units formed at the upper bridge position and the lower bridge position is, for example, the first power switch tube unit and the second power switch tube unit, or, for example, the third power switch tube unit and the fourth power switch tube unit, or, for example, the fifth power switch tube unit and the sixth power switch tube unit.

[0049] The bonding wires in the power module include: the bonding wires connecting different power switch tube units in the power module, and the bonding wires between the power switch tube unit and the lead-out terminals of the power module.

[0050] Reference Figure 3 , the converter further includes: a first load inductor L A , one end of the first load inductor L A is electrically connected to the emitter of the first main power switch tube T1 and the collector of the second main power switch tube T2; and the first load inductor L AThe first load resistor R connected in series A , the first load inductance L A The other end is connected to the first load resistor R A One end of the second load inductor L B , the second load inductor L B One end is electrically connected to the emitter of the third main power switch tube T3 and the collector of the fourth main power switch tube T4; and the second load inductor L B The second load resistor R connected in series B , the second load inductor L B The other end is connected to the second load resistor R B The third load inductor L C , the third load inductor L C One end is electrically connected to the emitter of the fifth main power switch tube T5 and the collector of the sixth main power switch tube T6; and the third load inductor L C The third load resistor R connected in series C , the third load inductor L C The other end is connected to the third load resistor R C One end of the first load resistor R A The other end of the second load resistor R B The other end and the third load resistor R C The other ends of the first load inductor L A and the first load resistor R A The total output voltage is U AN , the second load inductor L B and the second load resistor R B The total output voltage is U BN , the third load inductor L C and the third load resistor R C The total output voltage is U CN ; flows through the first load inductor L A and the first load resistor R A The current is the first current I A , flows through the second load inductor L B and the second load resistor R B The current is the second current I B , flows through the third load inductor L C and the third load resistor R C The current is the third current I C The sixth main power switch tube T6 to be tested has a conduction saturation voltage drop V CEIn this embodiment, the sixth main power switch tube T6 is selected as the main power switch tube to be measured. Of course, in other embodiments, any other main power switch tube can be arbitrarily selected as the main power switch tube to be measured.

[0051] In this embodiment, the first junction temperature calibration module 100 injects the first calibrated conduction current from the collector of the main power switch tube to be measured into the main power switch tube to be measured. Specifically, it is selected to inject the second constant calibrated current into the sixth main power switch tube T6. The value range of the first calibrated conduction current injected into the main power switch tube to be measured is the working current during the normal operation of the converter.

[0052] During the process that the first junction temperature calibration module 100 injects the first calibrated conduction current into the main power switch tube to be measured, the main power switch tube to be measured is suitable to be placed on the heating platform, and the junction temperature of the main power switch tube to be measured in the first mapping relationship is calibrated by the temperature of the heating platform.

[0053] The first junction temperature calibration module 100 includes a first constant current source. The first constant current source injects a large current into the main power switch tube to be measured, and then a set of mapping data of the first calibrated conduction current and the first calibrated conduction saturation voltage drop can be obtained. By adjusting the temperature of the heating table, the mapping data of the first calibrated conduction current and the first calibrated conduction saturation voltage drop of the main power switch tube to be measured at different first calibrated junction temperatures can be obtained, so as to obtain the first mapping relationship between the first calibrated conduction saturation voltage drop and the first calibrated conduction current and the first calibrated junction temperature of the main power switch tube to be measured in the off-line state.

[0054] The first function relationship fitted by the first data fitting module 110 can be a polynomial or a trigonometric function.

[0055] The first function relationship is T B1 = f1(I B1 , V B1 ). Wherein, T B1 is the first calibrated junction temperature, I B1 is the first calibrated conduction current, and V B1 is the first calibrated conduction saturation voltage drop.

[0056] During the process that the second junction temperature calibration module 200 injects the second constant calibrated current into the main power switch tube to be measured, the main power switch tube to be measured is suitable to be placed on the heating platform, and the junction temperature of the main power switch tube to be measured in the second mapping relationship is calibrated by the temperature of the heating platform. The second constant calibrated current is much smaller than the first calibrated conduction current.

[0057] In this embodiment, the main power switch tube to be measured is an IGBT, and the second junction temperature calibration module 200 injects a second constant calibration current into the main power switch tube to be measured in the forward direction. When the main power switch tube to be measured has other structures, it is also possible to inject the second constant calibration current in the reverse direction. For example, for a MOSFET, the second constant calibration current is injected in the reverse direction. When the main power switch tube is a MOSFET, each power switch tube unit includes the main power switch tube but does not include a diode.

[0058] In one embodiment, the second junction temperature calibration module 200 injects the second constant calibration current into the main power switch tube to be measured in the forward direction from the collector of the main power switch tube to be measured. Specifically, it is selected to inject the second constant calibration current into the sixth main power switch tube T6. The second constant calibration current is 5 mA - 200 mA, such as 5 mA, 10 mA, 50 mA, 100 mA, 150 mA or 200 mA. In this way, the second constant calibration current is relatively small, which can avoid excessive conduction current inside the main power switch tube to be measured and heat generation.

[0059] The second junction temperature calibration module 200 includes a second constant current source. The second constant current source is adapted to generate a constant current and inject the constant current into the main power switch tube to be measured in the forward direction. During the process of the second junction temperature calibration module 200 injecting the constant current into the main power switch tube to be measured, the negative terminal of the second constant current source is connected to the collector of the main power switch tube to be measured. The main power switch tube to be measured is preferably placed on a heating platform. Specifically, the chip corresponding to the main power switch tube to be measured is placed on the heating platform, and the main power switch tube to be measured is heated to a predetermined temperature by the heating platform, and the gate of the main power switch tube to be measured is turned on. During the calibration process of the second junction temperature calibration module 200 for the main power switch tube to be measured, the injected constant current remains unchanged all the time. By adjusting the temperature of the heating platform, the mapping data of the second calibrated on-state saturation voltage drop of the main power switch tube to be measured at different second calibrated junction temperatures can be obtained, so as to obtain the second mapping relationship between the second calibrated on-state saturation voltage drop of the main power switch tube in the off-line state and the second calibrated junction temperature of the main power switch tube to be measured. The second constant calibration current is much smaller than the first calibrated conduction current. The junction temperature of the main power switch tube to be measured in the second mapping relationship is calibrated by the temperature of the heating platform.

[0060] The on-state saturation voltage drop at a fixed small current (mA level) is linearly negatively correlated with the junction temperature. The method of measuring the junction temperature by using this relationship by the second junction temperature calibration module 200 is called the small current on-state voltage drop method. As a standard method for off-line junction temperature measurement in a laboratory, it is not affected by aging, but it is a laboratory measurement method and is generally not used for on-line applications.

[0061] In this embodiment, the off-line state mentioned refers to that the main power switch tube to be measured is taken out from the converter and tested in the laboratory.

[0062] The second function relationship fitted by the second data fitting module 210 can be a polynomial or a trigonometric function. In this embodiment, under a constant small current, the on-state saturation voltage drop of the IGBT itself and the junction temperature have an approximately linear relationship, that is, the second function relationship can be fitted by a first-order unary polynomial.

[0063] The second function relationship is T B2 = f2(V B2 ). Wherein, T B2 is the second calibrated junction temperature, and V B2 is the second calibrated on-state saturation voltage drop.

[0064] It should be noted that in this embodiment, there are no restrictions on the specific first data fitting module 110 and the second data fitting module 210. As long as the first data fitting module 110 can fit into the first function relationship according to the first mapping relationship, and as long as the second data fitting module 210 can fit into the second function relationship according to the second mapping relationship.

[0065] The first sampling module 300 is adapted to inject a first test current I C1 in the forward direction into the main power switch tube to be tested in the converter in the quasi-online working state, and obtain the first test on-state voltage drop V C1 of the main power switch tube to be tested. The quasi-online working state satisfies that the power module is in the converter, and the converter is in the self-check or standby state.

[0066] The first test junction temperature acquisition unit 310 is adapted to acquire the first test junction temperature T C1 , and the first test junction temperature T C1 is the value of the first calibrated junction temperature T C1 corresponding to the data of the first test on-state voltage drop V C1 and the first test current I B1 in the first function relationship. That is, the data of the first test on-state voltage drop V C1 obtained by the test is assigned to V B1 , the data of the first test current I C1 is assigned to I B1 , and the value of T B1 calculated through the first function relationship is used as the first test junction temperature T C1 .

[0067] The emergency stop control module 400 is adapted to apply a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state until the current in all the load inductors in the converter is all zero.

[0068] Reference Figure 4 , Figure 4A timing diagram for the first sampling module 300, the emergency stop control module 400, and the second sampling module 500, which corresponds to Figure 3 the converter, Figure 4 In Figure 4 , the states of the converter include the online state, the quasi-online state, and the offline state. The online state means that the converter is in the operating state, outputting a certain power, and the main power switching tubes are alternately turned on. The gates of the main power switching tubes are driven by the pulse width modulation signal (Pulse width modulation, abbreviated as PWM) of the converter. Different main power switching tubes have corresponding timings of the pulse width modulation signals required for their own operation. The offline state means that the main power switching tube to be tested is removed from the converter and sent to the laboratory for testing. The quasi-online state means that the main power switching tube to be tested is in the converter, and the converter is in the self-check or standby state. Figure 4 In Figure 4 , the quasi-online state is taken as an example of the self-check state. In the quasi-online state, the converter does not output power.

[0069] The emergency stop control module 400 applies a forced turn-off signal to all the main power switching tubes in the converter in the quasi-online working state from the first moment t1 to the third moment t3 until the current in all the load inductors in the converter becomes zero. This process lasts for milliseconds, that is, all the main power switching tubes in the converter are turned off in a very short time. During the stage when the emergency stop control module 400 continuously applies a forced turn-off signal to the gates of all the main power switching tubes, the current does not flow through each main power switching tube. Specifically, for Figure 3 the converter in Figure 3 , the emergency stop control module 400 applies a forced turn-off signal to the first main power switching tube T1, the second main power switching tube T2, the third main power switching tube T3, the fourth main power switching tube T4, the fifth main power switching tube T5, and the sixth main power switching tube T6 from the first moment t1 until the current in the first load inductor L A , the second load inductor L B and the third load inductor L C becomes zero at the third moment t3. The third moment t3 is the moment when the current in all the load voltages electrically connected to the main power switching tubes just becomes zero. Specifically, for Figure 4 the converter in Figure 4 , the third moment t3 is the moment when the current in the first load inductor L A , the second load inductor L B and the third load inductor L C just becomes zero. During the stage from the first moment t1 to the third moment t3, the current in some load inductors can become zero first, and the current in some load inductors can become zero later until the current in all the load voltages becomes zero at the third moment t3. For Figure 3 the converter in Figure 3 , when the sixth main power switching tube T6 is the main power switching tube to be tested, the third load inductor LC The current in C becomes zero at the second moment t2 first. After that, the current in the first load inductor L A and the current in the second load inductor L B become zero synchronously at the third moment t3.

[0070] Since a forced turn-off signal has been applied to all the main power switch tubes in the converter since the first moment t1, the power switch tube unit enters the fast freewheeling mode. Specifically, when the main power switch tube unit to be measured performs fast freewheeling for the inductor electrically connected to the main power switch tube to be measured, the main power switch tube to be measured is in the off state, the current does not flow through the main power switch tube to be measured, the diode reversely connected in parallel with the main power switch tube to be measured conducts to allow the current to flow through, and a reverse voltage is applied across the two ends of the load inductor electrically connected to the main power switch tube to be measured, so that the current in the load inductor electrically connected to the main power switch tube to be measured quickly returns to zero. At this time, the branch where the load inductor electrically connected to the main power switch tube to be measured is located is disconnected and will not continue to decay and oscillate to zero; when a non-main power switch tube to be measured performs fast freewheeling for the inductor electrically connected to the non-main power switch tube to be measured, the non-main power switch tube to be measured is in the off state, the current does not flow through the non-main power switch tube to be measured, the diode reversely connected in parallel with the non-main power switch tube to be measured conducts to allow the current to flow through, and a reverse voltage is applied across the two ends of the load inductor electrically connected to the non-main power switch tube to be measured, so that the current in the load inductor electrically connected to the non-main power switch tube to be measured quickly returns to zero. At this time, the branch where the load inductor electrically connected to the non-main power switch tube to be measured is located is disconnected and will not continue to decay and oscillate to zero. In summary, the interval time between the first moment t1 and the third moment t3 is relatively small.

[0071] In one embodiment, (t3 - t1) is from 1 ms to 5 ms.

[0072] The second sampling module 500 is adapted to inject a second test current into the main power switch tube to be tested in the converter in the quasi-online working state and obtain the second test conduction voltage drop of the main power switch tube to be tested after the emergency stop control module applies a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state. The second sampling module 500 is adapted to inject a second test current into the main power switch tube to be tested in the converter in the quasi-online working state and obtain the second test conduction voltage drop of the main power switch tube to be tested after the third moment t3 and before the fourth moment t4. The second sampling module 500 applies a high level to the gate of the main power switch tube to be tested after the third moment t3 and before the fourth moment t4 to turn it on. Specifically, a high level is applied to the gate of the sixth main power switch tube T6 to turn it on, and a low level is applied to the gates of the first main power switch tube T1 to the fifth power switch tube T5 to keep them in the off state. The second test current is 5 mA - 200 mA, such as 5 mA, 10 mA, 50 mA, 100 mA, 150 mA or 200 mA.

[0073] The difference between the fourth moment t4 and the third moment t3 is in the millisecond level.

[0074] The second test current is equal to the second constant calibration current, which improves the accuracy of the finally obtained verified junction temperature.

[0075] The second test junction temperature acquisition unit 510 is adapted to acquire the second test junction temperature T C2 , and the second test junction temperature T C2 is the value of the second calibrated junction temperature T C2 corresponding to the data of the second test conduction voltage drop V B2 in the second functional relationship. That is, the data of the second test conduction voltage drop V C2 obtained by testing is assigned to V B2 , and the value of T B2 calculated through the second functional relationship is used as the second test junction temperature T C2 .

[0076] The aging parameter acquisition module 600 includes: a first sub-module, and the first sub-module is adapted to obtain the equivalent resistance change parameter ΔR(T t ) of the bonding wire at the second test junction temperature T C2 according to the equivalent resistance change parameter ΔR(T t ) of the bonding wire at the characteristic temperature, the resistance temperature coefficient k of the bonding wire, the second test junction temperature T C2 , and the characteristic temperature T C2 ), ΔR(T C2 ) = ΔR(T t ) * (1 + k * (T C2 - T t); a second sub-module, the second sub-module is adapted to obtain a first test calibrated conduction voltage drop V C1 according to the first test conduction voltage drop V C1 , the first test current I C2 , and the equivalent resistance change parameter ΔR(T C2 ) of the bonding wire at the second test junction temperature T Z1 , where V Z1 = V C1 - ΔR(T C2 ) * I C1 ; a third sub-module, the third sub-module is adapted to obtain the equivalent resistance change parameter ΔR(T Z1 ) at the characteristic temperature according to the first test calibrated conduction voltage drop V C1 , the first test current I C2 , the second test junction temperature T t , and the first function relationship. Specifically, assign the first test current I C1 to I B1 , assign the second test junction temperature T C2 to T B1 , assign V C1 - ΔR(T C2 ) * I C1 to V B1 , and calculate the equivalent resistance change parameter ΔR(T t ) at the characteristic temperature according to the first function relationship.

[0077] In one embodiment, the characteristic temperature is 10 degrees Celsius to 40 degrees Celsius. In this embodiment, the characteristic temperature is exemplified by 25 degrees Celsius.

[0078] In this embodiment, the power module aging parameter quasi-online identification system further includes: a comparison module, the comparison module is adapted to compare whether the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than a threshold. In one embodiment, the threshold is 1 mA to 100 mA.

[0079] Another embodiment of the present invention further provides a junction temperature calibration system. Referring to Figure 5 , it includes: the power module aging parameter quasi-online identification system provided in the above embodiment; a correction unit 700, the correction unit 700 is adapted to calibrate the first function relationship into a first corrected function relationship according to the equivalent resistance change parameter.

[0080] The first function relationship is T B1 = f1(I B1 , V B1 ). The first corrected function relationship is T B1 = f1(I B1 , V B1 - [ΔR(Tt )*(1 + k*(T B1 - T t )]*I B1 );T B1 is the first calibrated junction temperature, I B1 is the first calibrated conduction current, T t is the characteristic temperature, k is the resistance temperature coefficient of the bonding wire, V B1 is the first calibrated conduction saturation voltage drop.

[0081] In this embodiment, the junction temperature calibration system further includes: a first condition judgment unit, the first condition judgment unit is adapted to judge whether the online operation time of the converter is greater than a time threshold; a second condition judgment unit, the second condition judgment unit is adapted to judge whether the converter meets the quasi-online working state; the first sampling module is adapted to inject a first test current in the forward direction into the main power switch tube to be measured in the converter in the quasi-online working state and obtain the first test conduction voltage drop of the main power switch tube to be measured when the online operation time of the converter is greater than the time threshold and the converter meets the quasi-online working state.

[0082] In this embodiment, the junction temperature calibration system further includes: an online sampling module, the online sampling module is adapted to inject a third test current in the forward direction into the main power switch tube to be measured in the converter in the online working state and obtain the third test conduction voltage drop of the main power switch tube to be measured; an online junction temperature acquisition unit, the online junction temperature acquisition unit is adapted to obtain the online junction temperature of the main power switch tube to be measured according to the third test current, the third test conduction voltage drop and the first correction function relationship.

[0083] Figure 6 This is the topological structure diagram of the online sampling provided in this embodiment. The online sampling module includes an online current sampling module and an online conduction voltage sampling module. The main power switch tube to be measured is a working element of the power device module. The power device module includes: a converter and a main control module. The online current sampling module can be an internal current sampling module in the power device module. The output end of the current sampling internal module is adapted to be connected to the input end of the main control module, and the output end of the main control module is adapted to provide a working timing for each main power switch tube in the converter. The power device module further includes: a CPU (Central Processing Unit).

[0084] Another embodiment of the present invention further provides a method for quasi-online identification of power module aging parameters, which is adapted to monitor the junction temperature of the main power switch tube to be measured in the power module. The power module includes a bonding wire connected to the main power switch tube, and includes:

[0085] Step S1: Inject a first calibrated conduction current into the main power switch to be measured in the forward direction, and obtain a first mapping relationship between the first calibrated conduction saturation voltage drop of the main power switch to be measured in the off-line state, the first calibrated conduction current, and the first calibrated junction temperature of the main power switch to be measured;

[0086] Step S2: Fit the data in the first mapping relationship to obtain a first functional relationship, where the first functional relationship takes the first calibrated conduction saturation voltage drop and the first calibrated conduction current as independent variables and the first calibrated junction temperature as the dependent variable;

[0087] Step S3: Inject a second constant calibrated current into the main power switch to be measured, and obtain a second mapping relationship between the second calibrated conduction saturation voltage drop of the main power switch to be measured in the off-line state and the second calibrated junction temperature of the main power switch to be measured. The second constant calibrated current is much smaller than the first calibrated conduction current;

[0088] Step S4: Fit the data in the second mapping relationship to obtain a second functional relationship, where the second functional relationship takes the second calibrated conduction saturation voltage drop as the independent variable and the second calibrated junction temperature as the dependent variable;

[0089] Step S5: Inject a first test current into the main power switch to be measured in the forward direction in the converter under the quasi-online working state and obtain the first test conduction voltage drop of the main power switch to be measured;

[0090] Step S6: Obtain the first test junction temperature, where the first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first functional relationship;

[0091] After obtaining the first test junction temperature, apply a forced turn-off signal to all the main power switches in the converter under the quasi-online working state until the current in all the load inductors in the converter is zero; The quasi-online working state satisfies: the power module is in the converter, and the converter is in the self-check or standby state;

[0092] Step S8: After applying a forced turn-off signal to all the main power switches in the converter under the quasi-online working state, inject a second test current into the main power switch to be measured in the converter under the quasi-online working state and obtain the second test conduction voltage drop of the main power switch to be measured. The second test current is equal to the second constant calibrated current;

[0093] Step S9: Obtain the second test junction temperature, where the second test junction temperature is the value of the second calibrated junction temperature corresponding to the data of the second test conduction voltage drop in the second functional relationship;

[0094] Step S10: When the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than the threshold value, obtain the equivalent resistance change parameter of the bonding wire at the characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop.

[0095] The steps of obtaining the equivalent resistance change parameter of the bonding wire at the characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop include: According to the equivalent resistance change parameter ΔR(T t ) of the bonding wire at the characteristic temperature, the resistance temperature coefficient k of the bonding wire, the second test junction temperature T C2 , and the characteristic temperature T t , obtain the equivalent resistance change parameter ΔR(T C2 ) of the bonding wire at the second test junction temperature T C2 ), ΔR(T C2 ) = ΔR(T t ) * (1 + k * (T C2 - T t )); It is suitable to obtain the first test calibrated conduction voltage drop V C1 according to the first test conduction voltage drop V C1 , the first test current I C2 , and the equivalent resistance change parameter ΔR(T C2 ) of the bonding wire at the second test junction temperature T C2 Z1 , V Z1 = V C1 - ΔR(T C2 ) * I C1 ; According to the first test calibrated conduction voltage drop V Z1 , the first test current I C1 , the second test junction temperature T C2 , and the first function relationship, obtain the equivalent resistance change parameter ΔR(T t ) at the characteristic temperature.

[0096] The main power switch tube includes an IGBT.

[0097] Another embodiment of the present invention further provides a junction temperature calibration method, including: the power module aging parameter quasi-online identification method provided in the above embodiment; calibrating the first function relationship to the first corrected function relationship according to the equivalent resistance change parameter.

[0098] The first function relationship is T B1 = f1(I B1 , V B1 ); The first corrected function relationship is T B1 = f1(I B1 , V B1 - [ΔR(T t ) * (1 + k * (T B1-T t )]*I B1 );T B1 is the first calibrated junction temperature, I B1 is the first calibrated conduction current, T t is the characteristic temperature, k is the resistance temperature coefficient of the bonding wire, ΔR(T t ) is the equivalent resistance change parameter of the bonding wire at the characteristic temperature, V B1 is the first calibrated conduction saturation voltage drop.

[0099] In this embodiment, it further includes: before performing step S5, it further includes: performing a first condition judgment, that is, judging whether the online operation time of the converter is greater than the time threshold; if the online operation time of the converter is less than or equal to the time threshold, a third test current is positively injected into the main power switch tube to be tested in the converter in the online working state, and the third test conduction voltage drop of the main power switch tube to be tested is obtained, and the online junction temperature of the main power switch tube to be tested is obtained according to the third test current, the third test conduction voltage drop and the first function relationship.

[0100] In this embodiment, after performing the first condition judgment, a second condition judgment is performed, that is, judging whether the converter meets the quasi-online working state; if the converter does not meet the quasi-online working state, a third test current is positively injected into the main power switch tube to be tested in the converter in the online working state, and the third test conduction voltage drop of the main power switch tube to be tested is obtained, and the online junction temperature of the main power switch tube to be tested is obtained according to the third test current, the third test conduction voltage drop and the first function relationship.

[0101] In this embodiment, if the online operation time of the converter is greater than the time threshold and the converter meets the quasi-online working state, step S5 is performed.

[0102] In this embodiment, after calibrating the first function relationship to the first corrected function relationship according to the equivalent resistance change parameter, a third test current is positively injected into the main power switch tube to be tested in the converter in the online working state, and the third test conduction voltage drop of the main power switch tube to be tested is obtained, and the online junction temperature of the main power switch tube to be tested is obtained according to the third test current, the third test conduction voltage drop and the first corrected function relationship.

[0103] It should be noted that the concept of the present invention can also obtain Figure 3 the verified junction temperatures of other main power switch tubes in the converter in . The concept of the present invention can also obtain the verified junction temperatures of the main power switches to be tested of converters with other structures. Converters with other structures such as converters of H-bridge circuits and single-phase half-bridge circuits.

[0104] This method greatly improves the accuracy of online monitoring of the junction temperature after the power module undergoes degenerative changes in practical applications. At the same time, by applying this method, the health status of the power module during use can also be monitored, providing a basis for predicting the life of the power module.

[0105] In this embodiment, a first test current is injected forward into the main power switch tube to be tested in the converter under the quasi-online working state, and the first test conduction voltage drop of the main power switch tube to be tested is obtained. The quasi-online working state satisfies that the main power switch tube to be tested is in the converter, and the converter is in the self-check or standby state. The first test junction temperature is obtained, and the first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first functional relationship. After that, a forced turn-off signal is applied to all the main power switch tubes in the converter under the quasi-online working state until the current in all the load inductors in the converter becomes zero. Since a forced turn-off signal is applied to all the main power switch tubes in the converter, the power switch tube unit enters the fast freewheeling mode, causing the current in the load inductor electrically connected to the main power switch tube to be tested to quickly return to zero. At this time, the branch where the load inductor electrically connected to the main power switch tube to be tested is located is disconnected and will not continue to damp and oscillate to zero, resulting in a shorter time for applying the forced turn-off signal to all the main power switch tubes in the converter under the quasi-online working state. After that, a second test current is injected into the main power switch tube to be tested in the converter under the quasi-online working state, and the second test conduction voltage drop of the main power switch tube to be tested is obtained. The second test current is equal to the second constant calibration current. The second test junction temperature is obtained, and the second test junction temperature is the value of the second calibrated junction temperature corresponding to the data of the second test conduction voltage drop in the second functional relationship. The data of the second test junction temperature obtained by the small current injection method after the emergency stop control is relatively accurate, that is, the small current method is used to calibrate the online junction temperature monitoring data to obtain the true value of the junction temperature in the aging state of the main power switch tube to be tested. When the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than the threshold, the equivalent resistance change parameter of the bonding wire at the characteristic temperature is obtained according to the second test junction temperature, the first test current, and the first test conduction voltage drop. The first functional relationship is calibrated to the first corrected functional relationship according to the equivalent resistance change parameter. Since the equivalent resistance change parameter of the bonding wire at the characteristic temperature is considered in the first corrected mapping relationship, the first corrected functional relationship can accurately measure the junction temperature of the main power switch tube to be tested in the online state. Since the second test junction temperature is measured in the quasi-online state, the main power switch tube to be tested does not need to be taken out during the use of the converter, and the data of the second test junction temperature obtained by the small current injection method after the emergency stop control is relatively easy to obtain, and the test difficulty is low.

[0106] In a comparative experiment, the high-precision sampling module and sampling calibration method of the invention were applied for on-line testing, and the verification method in this article was used for comparison. First, the on-line monitoring results of the junction temperature of the new module were compared and verified, and the error was less than 5°C. The module was subjected to 300,000 power cycles of accelerated aging in the laboratory, and then the on-line measurement results of the junction temperature before and after aging calibration were compared and verified respectively. The error of the on-line monitoring data without calibration after aging reached 22°C. By applying the aging calibration method of the present invention, the equivalent resistance change parameter ΔR(T t ) was 35 mΩ, and the error of the on-line monitoring data after calibration was controlled within 7°C.

[0107] Obviously, the above embodiments are merely examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A quasi-online identification system for aging parameters of a power module, suitable for monitoring the junction temperature of the main power switch tube to be measured in the power module. The power module includes a bonding wire connected to the main power switch tube, and is characterized in that, Including: A first junction temperature calibration module, which is adapted to forward inject a first calibrated conduction current into the main power switch to be measured, and obtain a first mapping relationship between the first calibrated conduction saturation voltage drop, the first calibrated conduction current of the main power switch to be measured, and the first calibrated junction temperature of the main power switch to be measured in an off-line state; A second junction temperature calibration module, which is adapted to inject a second constant calibrated current into the main power switch to be measured, and obtain a second mapping relationship between the second calibrated conduction saturation voltage drop and the second calibrated junction temperature of the main power switch to be measured in an off-line state, and the second constant calibrated current is much smaller than the first calibrated conduction current; A first data fitting module, which is adapted to fit the data in the first mapping relationship to obtain a first functional relationship, where the first functional relationship takes the first calibrated conduction saturation voltage drop and the first calibrated conduction current as independent variables and the first calibrated junction temperature as the dependent variable; A second data fitting module, which is adapted to fit the data in the second mapping relationship to obtain a second functional relationship, where the second functional relationship takes the second calibrated conduction saturation voltage drop as the independent variable and the second calibrated junction temperature as the dependent variable; A first sampling module, which is adapted to forward inject a first test current into the main power switch to be measured in the converter in a quasi-online working state and obtain the first test conduction voltage drop of the main power switch to be measured; A first test junction temperature acquisition unit, which is adapted to acquire a first test junction temperature, and the first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first functional relationship; An emergency stop control module, which is adapted to apply a forced turn-off signal to all the main power switches in the converter in a quasi-online working state until the current in all the load inductors in the converter is all zero; the quasi-online working state satisfies that the power module is in the converter and the converter is in a self-check or standby state; A second sampling module, which is adapted to, after the emergency stop control module applies a forced turn-off signal to all the main power switches in the converter in a quasi-online working state, inject a second test current into the main power switch to be measured in the converter in a quasi-online working state and obtain the second test conduction voltage drop of the main power switch to be measured, and the second test current is equal to the second constant calibrated current; A second test junction temperature acquisition unit, which is adapted to acquire a second test junction temperature, and the second test junction temperature is the value of the second calibrated junction temperature corresponding to the data of the second test conduction voltage drop in the second functional relationship; An aging parameter acquisition module, which is adapted to obtain the equivalent resistance change parameter of the bonding wire at the characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop when the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than a threshold; The aging parameter acquisition module includes: a first submodule, the first submodule is adapted to obtain the equivalent resistance change parameter ΔR (T t ), the resistance temperature coefficient k of the bonding wire, the second test junction temperature T C2 , characteristic temperature T t Get the junction temperature T of the bonding wire at the second test C2 The equivalent resistance change parameter ΔR(T C2 ), ΔR(T C2 )=ΔR(T t )*(1+k*(T C2 -T t ); a second submodule, the second submodule is adapted to conduct the voltage drop V according to the first test C1 , the first test current I C1 , the bonding wire is at the second test junction temperature T C2 The equivalent resistance change parameter ΔR(T C2 ) Get the first test calibration on-state voltage drop V Z1 , V Z1 =V C1 -ΔR(T C2 )*I C1 ; A third submodule, the third submodule is suitable for calibrating the conduction voltage drop V according to the first test Z1 , the first test current I C1 and the second test junction temperature T C2 And the first functional relationship obtains the equivalent resistance change parameter ΔR (T t ), the first functional relationship is T B1 =f1(I B1 , V B1 ), T B1 is the first calibrated junction temperature, I B1 is the first rated on-state current, V B1 It is the first calibration on-state saturation voltage drop.

2. The quasi-online identification system for aging parameters of a power module according to claim 1, characterized in that, It also includes: A comparison module, which is adapted to compare whether the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than a threshold value.

3. The quasi-online identification system for aging parameters of a power module according to claim 1, characterized in that, The threshold value is 1 mA to 100 mA.

4. The quasi-online identification system for aging parameters of a power module according to claim 1, characterized in that, The main power switch tube includes an IGBT.

5. A junction temperature calibration system, characterized in that, Comprising: The power module aging parameter quasi-online identification system according to any one of claims 1 to 4; A correction unit, which is adapted to calibrate the first functional relationship into a first corrected functional relationship according to the equivalent resistance change parameter.

6. The junction temperature calibration system according to claim 5, characterized in that, Further comprising: An online sampling module, which is adapted to inject a third test current in the forward direction into the main power switch tube to be measured in the converter in the online working state and obtain the third test conduction voltage drop of the main power switch tube to be measured. An online junction temperature acquisition unit, which is adapted to obtain the online junction temperature of the main power switch tube to be measured according to the third test current, the third test conduction voltage drop and the first corrected functional relationship.

7. The junction temperature calibration system according to claim 5, characterized in that, The first correction function relationship is T B1 = f1(I B1 , V B1 − [ΔR(T t ) * (1 + k * (T B1 − T t ))] * I B1 ); T B1 is the first calibrated junction temperature, I B1 is the first calibrated conduction current, T t is the characteristic temperature, k is the resistance temperature coefficient of the bonding wire, ΔR(T t ) is the equivalent resistance change parameter of the bonding wire at the characteristic temperature, V B1 is the first calibrated conduction saturation voltage drop.

8. The junction temperature calibration system according to claim 5, characterized in that, Further comprising: A first condition judgment unit, which is adapted to judge whether the online operation time of the converter is greater than a time threshold value; A second condition judgment unit, which is adapted to judge whether the converter meets the quasi-online working state; The first sampling module is adapted to inject a first test current in the forward direction into the main power switch tube to be measured in the converter in the quasi-online working state and obtain the first test conduction voltage drop of the main power switch tube to be measured when the online operation time of the converter is greater than the time threshold value and the converter meets the quasi-online working state.

9. A quasi-online identification method for aging parameters of a power module, suitable for monitoring the junction temperature of a main power switch tube to be measured in the power module. The power module includes a bonding wire connected to the main power switch tube, and is characterized in that, Comprising: Step S1: Inject a first calibrated conduction current in the forward direction into the main power switch tube to be measured, and obtain a first mapping relationship between the first calibrated conduction saturation voltage drop of the main power switch tube to be measured in the offline state, the first calibrated conduction current, and the first calibrated junction temperature of the main power switch tube to be measured; Step S2: Fit the data in the first mapping relationship to obtain a first functional relationship, where the first functional relationship takes the first calibrated conduction saturation voltage drop and the first calibrated conduction current as independent variables and the first calibrated junction temperature as the dependent variable; Step S3: Inject a second constant calibrated current into the main power switch tube to be measured, and obtain a second mapping relationship between the second calibrated conduction saturation voltage drop of the main power switch tube to be measured in the offline state and the second calibrated junction temperature of the main power switch tube to be measured, where the second constant calibrated current is much smaller than the first calibrated conduction current; Step S4: Fit the data in the second mapping relationship to obtain a second functional relationship, where the second functional relationship takes the second calibrated conduction saturation voltage drop as the independent variable and the second calibrated junction temperature as the dependent variable; Step S5: Inject a first test current in the forward direction into the main power switch tube to be measured in the converter in the quasi-online working state and obtain the first test conduction voltage drop of the main power switch tube to be measured; Step S6: Obtain a first test junction temperature, where the first test junction temperature is the value of the first calibrated junction temperature corresponding to the data of the first test conduction voltage drop and the first test current in the first functional relationship; Step S7: After obtaining the first test junction temperature, apply a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state until the current in all the load inductors in the converter becomes zero; the quasi-online working state satisfies that the power module is in the converter and the converter is in the self-check or standby state; Step S8: After applying a forced turn-off signal to all the main power switch tubes in the converter in the quasi-online working state, inject a second test current into the main power switch tube to be tested in the converter in the quasi-online working state and obtain the second test conduction voltage drop of the main power switch tube to be tested, where the second test current is equal to the second constant calibration current; Step S9: Obtain the second test junction temperature, which is the value of the second calibrated junction temperature corresponding to the data of the second test conduction voltage drop in the second functional relationship; Step S10: When the absolute value of the difference between the first test junction temperature and the second test junction temperature is greater than the threshold, obtain the equivalent resistance change parameter of the bonding wire at the characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop; The steps of obtaining the equivalent resistance change parameter of the bonding wire at the characteristic temperature according to the second test junction temperature, the first test current, and the first test conduction voltage drop include: according to the equivalent resistance change parameter ΔR(T t ) of the bonding wire, the resistance temperature coefficient k of the bonding wire, the second test junction temperature T C2 , and the characteristic temperature T t , obtaining the equivalent resistance change parameter ΔR(T C2 ) of the bonding wire at the second test junction temperature T C2 ), ΔR(T C2 ) = ΔR(T t ) * (1 + k * (T C2 - T t )); being suitable for obtaining the first test calibrated conduction voltage drop V C1 according to the first test conduction voltage drop V C1 , the first test current I C2 , and the equivalent resistance change parameter ΔR(T C2 ) of the bonding wire at the second test junction temperature T Z1 , V Z1 = V C1 - ΔR(T C2 ) * I C1 ; according to the first test calibrated conduction voltage drop V Z1 , the first test current I C1 , the second test junction temperature T C2 , and the first function relationship to obtain the equivalent resistance change parameter ΔR(T t ) at the characteristic temperature, the first function relationship is T B1 = f1(I B1 , V B1 ), T B1 is the first calibrated junction temperature, I B1 is the first calibrated conduction current, and V B1 is the first calibrated conduction saturation voltage drop.

10. The quasi-online identification method for aging parameters of a power module according to claim 9, characterized in that, The main power switch tube includes an IGBT.

11. A junction temperature calibration method, characterized in that, Including: The quasi-online identification method for the aging parameters of the power module according to any one of claims 9 to 10; Calibrate the first functional relationship to the first corrected functional relationship according to the equivalent resistance change parameter.

12. The junction temperature calibration method according to claim 11, characterized in that, Further including: Inject a third test current forward into the main power switch tube to be tested in the converter in the online working state and obtain the third test conduction voltage drop of the main power switch tube to be tested; Obtain the online junction temperature of the main power switch tube to be tested according to the third test current, the third test conduction voltage drop, and the first corrected functional relationship.

13. The junction temperature calibration method according to claim 11, characterized in that, The first correction function relationship is T B1 = f1(I B1 , V B1 − [ΔR(T t ) * (1 + k * (T B1 − T t ))] * I B1 ); T B1 is the first calibrated junction temperature, I B1 is the first calibrated conduction current, T t is the characteristic temperature, k is the resistance temperature coefficient of the bonding wire, ΔR(T t ) is the equivalent resistance change parameter of the bonding wire at the characteristic temperature, V B1 is the first calibrated conduction saturation voltage drop.

14. The junction temperature calibration method according to claim 11, characterized in that, Further including: Before performing step S5, determine whether the online operation time of the converter is greater than the time threshold and whether the converter satisfies the quasi-online working state; If the online operation time of the converter is greater than the time threshold and the converter satisfies the quasi-online working state, then perform step S5; If the online operation time of the converter is less than or equal to the time threshold, and / or if the converter does not satisfy the quasi-online working state, then inject a third test current forward into the main power switch tube to be tested in the converter in the online working state and obtain the third test conduction voltage drop of the main power switch tube to be tested, and obtain the online junction temperature of the main power switch tube to be tested according to the third test current, the third test conduction voltage drop, and the first functional relationship.

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