CN112986781B - Junction temperature online monitoring data verification system and method - Google Patents
Junction temperature online monitoring data verification system and method Download PDFInfo
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- CN112986781B CN112986781B CN202110185012.6A CN202110185012A CN112986781B CN 112986781 B CN112986781 B CN 112986781B CN 202110185012 A CN202110185012 A CN 202110185012A CN 112986781 B CN112986781 B CN 112986781B
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Abstract
A system and a method for verifying junction temperature online monitoring data are provided, the system comprises: a junction temperature calibration module; a data fitting module; the emergency stop control module is suitable for applying forced turn-off signals to all main power switch tubes in the converter in an online working state from the first moment until all currents in all load inductors are zero at the third moment; the sampling module is also suitable for testing the current flowing through all load inductors electrically connected with the main power switch tube in the process from the first moment to the third moment, and the sampling module is also suitable for injecting constant current into the main power switch tube to be tested in the forward direction from the third moment or the fourth moment and acquiring second conduction saturation voltage drops of the main power switch tube to be tested at different moments in an off-line state and a conduction state; and the compensation module acquires the verified junction temperature at the first moment according to the junction temperature sampling value. The junction temperature on-line monitoring data verification system obtains higher precision of verification junction temperature.
Description
Technical Field
The invention relates to the field of power semiconductor device testing, in particular to a junction temperature online monitoring data verification system and method.
Background
Junction temperature is an important parameter characterizing the operating and health status of power semiconductor devices. And the chip in the power semiconductor device is packaged in the module and works in a high-voltage large-current environment, so that the junction temperature of the chip cannot be directly measured. Therefore, the online monitoring of the junction temperature of the power semiconductor device in the working state is very difficult, and is also a hot spot of current research.
The traditional method for detecting the junction temperature of the power semiconductor chip is mainly based on the research of SiIGBT, and comprises four major methods, namely a physical contact method, an optical measurement method, a model prediction method and a thermal inductance parameter method (TSEPs) extraction method. The TSEPs method uses the chip as a temperature sensor, reflects the change of the average junction temperature of the chip by measuring the change of temperature sensitive electrical parameters, can realize non-invasive measurement of a power module to be measured, and is theoretically the most suitable method for online monitoring of the junction temperature. However, the online measurement of the junction temperature itself belongs to an exploration phase, and it is difficult to find a more reliable method for determining and verifying the accuracy of the test result.
Disclosure of Invention
The invention aims to solve the technical problems that junction temperature online monitoring data cannot be verified and the verification method is poor in precision in the prior art.
In order to solve the above technical problem, the present invention provides a junction temperature online monitoring data verification system, which is adapted to obtain a verified junction temperature of a main power switch tube to be tested in a current transformer, where the current transformer includes a plurality of power switch tube units, and each power switch tube unit includes: the power supply comprises a main power switch tube and a diode connected with the main power switch tube in an inverse parallel mode; the converter also comprises a load inductor electrically connected with the main power switch tube; the method comprises the following steps: the junction temperature calibration module is suitable for injecting constant current into a main power switching tube to be tested in the forward direction and acquiring a first mapping relation between a first conduction saturation voltage drop and junction temperature of the main power switching tube to be tested in an off-line state and a conduction state; the data fitting module is suitable for fitting data in the first mapping relation to obtain a first functional relation, and the first functional relation takes the first conduction saturation voltage drop as an independent variable and takes the junction temperature of the main power switching tube to be measured as a dependent variable; the emergency stop control module is suitable for applying forced turn-off signals to all main power switch tubes in the converter in an online working state from the first moment until all currents in all load inductors are tested to be zero at the third moment; the sampling module is suitable for testing currents flowing through all load inductors electrically connected with the main power switch tube in the process from the first moment to the third moment, the sampling module is further suitable for injecting constant currents into the main power switch tube to be tested from the third moment or the fourth moment in the forward direction, second conduction saturation voltage drops of the main power switch tube to be tested at different moments in an off-line state and a conduction state are obtained, the fourth moment is greater than the third moment, and the difference value between the fourth moment and the third moment is smaller than or equal to a first threshold value; and the compensation module is suitable for acquiring corresponding junction temperature sampling values in the first functional relation according to the second conduction saturation voltage drop at different moments, and acquiring the verification junction temperature at the first moment according to the junction temperature sampling values at different moments.
Optionally, the junction temperature calibration module is adapted to control a constant current injected into the main power switching tube to be tested in the forward direction to be 5mA to 200mA; the sampling module is suitable for injecting a constant current of 5mA-200mA in the forward direction into the main power switch tube to be tested.
Optionally, the sampling module includes a voltage sampling module and a current sampling module, the voltage sampling module is adapted to inject a constant current to the main power switching tube to be tested from a third time or a fourth time in a forward direction, and obtain a second conduction saturation voltage drop of the main power switching tube to be tested at different times in an off-line state and a conduction state, and the current sampling module is adapted to test currents flowing through all load inductors electrically connected to the main power switching tube in a process from the first time to the third time.
Optionally, the emergency stop control module is adapted to apply a forced turn-off signal so that a current in a load inductor electrically connected to the main power switching tube to be tested becomes zero at a second time; the second time is greater than the first time and less than or equal to the third time.
Optionally, the method further includes: the online junction temperature testing module is suitable for testing the online junction temperature of the main power switching tube to be tested at and before the first moment; and the comparison module is suitable for acquiring the difference value between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment, and acquiring the test precision of the on-line junction temperature test module according to the difference value between the on-line junction temperature at the first moment and the verification junction temperature at the first moment.
Optionally, the method further includes: and the correction module is suitable for correcting the on-line junction temperature test module when the difference value between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment is larger than a second threshold value until the difference value between the on-line junction temperature and the verification junction temperature is smaller than or equal to the second threshold value.
Optionally, the compensation module includes a junction temperature sampling value obtaining unit and a junction temperature compensation obtaining unit, the junction temperature sampling value obtaining unit is adapted to obtain a corresponding junction temperature sampling value in the first functional relationship according to second conduction saturation voltage drops at different times, and the junction temperature compensation obtaining unit is adapted to obtain a verified junction temperature at a first time according to the junction temperature sampling values at different times.
Optionally, the junction temperature compensation obtaining unit includes: | T 1 －T m ∣＝q×(t m －t 1 ) 1/2 (ii) a Wherein, t m Is the m-th time, t 1 The first time, the mth time is more than or equal to the third time, T m Is the junction temperature sampling value at the m-th moment, T 1 And q is the verified junction temperature at the first moment, and q is a coefficient in the junction temperature compensation acquisition unit.
Optionally, the first threshold is greater than zero and less than or equal to 10 milliseconds.
The invention also provides a junction temperature on-line monitoring data verification method, which is suitable for obtaining the verification junction temperature of a main power switch tube to be tested in a current transformer, wherein the current transformer comprises a plurality of power switch tube units, and each power switch tube unit comprises: the power supply comprises a main power switch tube and a diode connected with the main power switch tube in an inverse parallel mode; the converter further includes a load inductor electrically connected to the main power switching tube, including: injecting a constant current into a main power switching tube to be tested in a forward direction, and acquiring a first mapping relation between a first conduction saturation voltage drop and junction temperature of the main power switching tube to be tested in an off-line state and a conduction state; fitting the data in the first mapping relation to obtain a first functional relation, wherein the first functional relation takes the first conduction saturation voltage drop as an independent variable and takes the junction temperature of the main power switching tube to be measured as a dependent variable; applying a forced turn-off signal to all main power switch tubes in the converter in an online working state from the first moment until all currents in all load inductors are tested to be zero at the third moment; injecting a constant current into the main power switching tube to be tested from a third moment or a fourth moment in a forward direction, and acquiring a second conduction saturation voltage drop of the main power switching tube to be tested at different moments in an off-line state and a conduction state, wherein the fourth moment is greater than the third moment and the difference between the fourth moment and the third moment is less than or equal to a first threshold; acquiring corresponding junction temperature sampling values in the first functional relation according to second conduction saturation voltage drops at different moments; and obtaining the verified junction temperature at the first moment according to the junction temperature sampling values at different moments.
Optionally, the method further includes: testing the online junction temperature of the main power switch tube to be tested online; acquiring a difference value between the online junction temperature of a main power switching tube to be tested at a first moment and the verification junction temperature at the first moment; and obtaining the test precision of the online junction temperature test module according to the difference between the online junction temperature at the first moment and the verification junction temperature at the first moment.
Optionally, the method further includes: and when the difference between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment is larger than a second threshold, correcting the process of on-line testing the main power switching tube to be tested until the difference between the on-line junction temperature and the verification junction temperature is smaller than or equal to the second threshold.
Optionally, the process of applying a forced turn-off signal to all main power switch tubes in the converter in the online working state from the first time includes: applying a forced turn-off signal to a main power switching tube to be tested from a first moment to enable current in a load inductor electrically connected with the main power switching tube to be tested to become zero at a second moment; the second time is greater than the first time and less than or equal to the third time.
Optionally, in a process of injecting a constant current into the main power switching tube to be tested in the forward direction, the main power switching tube to be tested is suitable for being placed on the heating platform, and the junction temperature of the main power switching tube to be tested in the first mapping relation is calibrated by the temperature of the heating platform.
Optionally, the constant current injected into the main power switch tube to be tested in the forward direction is 5mA-200mA; the constant current injected into the main power switch tube to be tested in the forward direction is 5mA-200mA.
Optionally, the sampling value of the junction temperature at different time instants and the formula | T 1 －T m ∣＝q×(t m －t 1 ) 1/2 Obtaining a verification junction temperature at a first moment; wherein, t m Is the m-th time, t 1 The first time, the mth time is more than or equal to the third time, T m Is the junction temperature sampling value at the m-th moment, T 1 Q is the formula | T for the verified junction temperature at the first instant in time 1 －T m ∣＝q×(t m －t 1 ) 1/2 Coefficient (2) of (1).
Optionally, the first threshold is greater than zero and less than or equal to 10 milliseconds.
Optionally, the method further includes: and when the verified junction temperature at the first moment is less than or equal to the junction temperature threshold of the device, the heat dissipation capability of the converter meets the requirement.
The technical scheme of the invention has the following advantages:
according to the junction temperature online monitoring data verification method provided by the technical scheme of the invention, forced turn-off signals are applied to all main power switch tubes in a converter in an online working state from the first moment until all currents in all load inductors are tested to be zero at the third moment; since a forced turn-off signal is applied to all main power switch tubes in the converter from the first moment, the power switch tube unit enters a fast follow current mode. Specifically, when a main power switch tube unit to be tested performs fast follow current on an inductor electrically connected with a main power switch tube to be tested, the main power switch tube to be tested is in a turn-off state, current does not flow through the main power switch tube to be tested, a diode connected with the main power switch tube to be tested in reverse parallel conducts through overcurrent, reverse voltage is applied to two ends of a load inductor electrically connected with the main power switch tube to be tested, so that the current in the load inductor electrically connected with the main power switch tube to be tested is fast returned to zero, and at the moment, a branch circuit where the load inductor electrically connected with the main power switch tube to be tested is located is disconnected and damping oscillation cannot continue to return to zero; when a certain main power switch tube which is not to be tested carries out rapid follow current on an inductor which is electrically connected with the main power switch tube which is not to be tested, the main power switch tube which is not to be tested is in a turn-off state, current does not flow through the main power switch tube which is not to be tested, a diode which is reversely connected in parallel with the main power switch tube which is not to be tested is conducted to flow through the current, reverse voltage is applied to two ends of a load inductor which is electrically connected with the main power switch tube which is not to be tested, so that the current in the load inductor which is electrically connected with the main power switch tube which is not to be tested is rapidly returned to zero, and at the moment, a branch circuit where the load inductor which is electrically connected with the main power switch tube which is not to be tested is located is disconnected, and damping oscillation is not continuously returned to zero. In sum, the interval between the first time and the third time is smaller. Because the interval time from the first moment to the third moment is shorter, and the first moment corresponds to the end moment of the online working state of the converter, the temperature of the main power switching tube to be tested in the turn-off process is compensated, the calculated junction temperature at the first moment can accurately represent the junction temperature of the power switching tube to be tested at the first moment, so that the accuracy of the junction temperature at the first moment obtained after compensation is higher, and the junction temperature at the first moment obtained after compensation can be used as the verification junction temperature. Specifically, constant current is injected into the main power switching tube to be tested in the forward direction from the third moment, second conduction saturation voltage drops of the main power switching tube to be tested at different moments in the off-line state and the conduction state are obtained, junction temperature sampling values are obtained in the first function relation by utilizing the second conduction saturation voltage drops at different moments, and verified junction temperature at the first moment can be obtained by adopting the corresponding relation between the values and time according to the junction temperature. In conclusion, the verification junction temperature with higher precision can be obtained by adopting the method and the device for verifying the precision of the on-line junction temperature test.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a junction temperature online monitoring data verification system according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a sampling module according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a compensation module according to an embodiment of the invention;
fig. 4 is a topology structure of the converter in online operation according to an embodiment of the present invention;
fig. 5 is a topology of a junction temperature calibration module according to an embodiment of the present invention;
FIG. 6 is a timing diagram illustrating the application of a forced shutdown signal by the scram control module according to an embodiment of the present invention;
fig. 7 is a schematic current flow diagram corresponding to the converter of fig. 4 during an emergency stop shutdown phase according to an embodiment of the present invention;
fig. 8 is a circuit topology diagram of a second conduction saturation voltage drop of the main power switch to be tested at different moments when the main power switch is in an off-line state and in a conduction state, which is obtained by the sampling module according to the embodiment of the present invention;
fig. 9 is a graph of junction temperature versus time after a first time, in accordance with an embodiment of the present invention.
Fig. 10 is a flowchart of a junction temperature online monitoring data verification method according to another embodiment of the present invention.
Detailed Description
As described in the background art, it is difficult to find a more reliable method for verifying the accuracy of the test result.
Most of the existing methods for evaluating the accuracy of junction temperature online monitoring data are to establish a thermoelectric coupling model for the whole system, wherein the thermoelectric coupling model comprises a device model, a loss model and a thermal impedance model, but the method has great limitations. Firstly, the device model is generally according to a device manual, and in an actual working condition, due to the influence of stray parameters of a busbar and a capacitor, the actual parameters are often different from the manual parameters, especially, the switching loss is greatly influenced by the stray parameters, so that the dynamic and static parameters of the module under different temperatures and working conditions need to be measured again under the design and application conditions. In addition, the loss model usually performs superposition calculation on the loss according to a control rule under an ideal condition, and relates to a plurality of parameters such as a modulation ratio, a power factor, a switching frequency, a modulation method, a junction temperature and the like, and an approximate calculation result has an error with an actual condition. Furthermore, the device manual only gives junction-to-case transient thermal impedances that require design testing due to varying heat dissipation systems for users. Therefore, the method for evaluating the junction temperature by using the thermocouple model method needs a lot of test data and calculates load, and the final result is a simulation calculated value and does not represent the true junction temperature value. Generally, the method can be only used for verifying the reasonability of junction temperature online monitoring data, namely the approximate range of the test data is consistent with that of the calculated data, and the method is not used for quantitatively analyzing the accuracy and the error range of the junction temperature online monitoring data.
And measuring the junction temperature of the power module by using an optical method so as to compare and verify the online monitoring data. The defects of the optical method for measuring the junction temperature of the power module are as follows: firstly, the voltage endurance capacity of the module is reduced by uncovering the module and carrying out sol treatment, and when the infrared thermal imager is used for measurement, a black coating needs to be coated on the upper surface of the module to enhance the radiation coefficient. In addition, the response time of the temperature-sensitive optical fiber and the infrared thermal imager is in millisecond level, and compared with the switching cycle response of a power module, the response is too slow, and the accuracy is not high.
The junction temperature of the power module is measured by using a physical contact method, usually a thermistor or a thermocouple is placed on a substrate of the power module to measure the temperature, but the temperature difference between the substrate temperature of the power module and the junction temperature inside the power chip is large (can reach more than 60K), and the error is unacceptable.
The low-current saturation conduction voltage drop method (hereinafter referred to as a low-current method) is a junction temperature measurement method based on thermosensitive inductive parameters, and is recommended by industry association to be used for thermal resistance test and reliability test of IGBT modules. The low-current conduction saturation voltage drop method mainly utilizes the negative linear relation between the conduction saturation voltage drop of the IGBT under constant low current and the junction temperature to realize off-line measurement of the junction temperature (relative to on-line measurement). The existing low-current saturated conduction voltage drop method adopts direct current for heating the IGBT module, needs to be provided with an additional auxiliary switch, is only suitable for measuring a cooling curve after a heat source is cut off, and cannot be completely compared and verified with online measurement.
On this basis, an embodiment of the present invention provides a junction temperature online monitoring data verification system, which is adapted to obtain a verified junction temperature of a main power switch tube to be tested in a current transformer, where the current transformer includes a plurality of power switch tube units, and each power switch tube unit includes: the power supply comprises a main power switch tube and a diode connected with the main power switch tube in an inverse parallel mode; the converter also comprises a load inductor electrically connected with the main power switch tube; referring to fig. 1, the junction temperature online monitoring data verification system 1 includes:
the junction temperature calibration module 10 is used for injecting a constant current into the main power switching tube to be tested in the forward direction, and acquiring a first mapping relation between a first conduction saturation voltage drop and the junction temperature of the main power switching tube to be tested in an off-line state and a conduction state;
the data fitting module 20 is adapted to fit data in the first mapping relation to obtain a first functional relation, where the first functional relation takes the first conduction saturation voltage drop as an independent variable and takes the junction temperature of the main power switching tube to be measured as a dependent variable;
the emergency stop control module 30 is adapted to apply a forced turn-off signal to all main power switching tubes in the converter in an online working state from a first moment until all currents in all load inductors are zero at a third moment;
the sampling module 40 is adapted to test currents flowing through all load inductors electrically connected to the main power switching tube in a process from a first time to a third time, the sampling module 40 is further adapted to inject a constant current to the main power switching tube to be tested in a forward direction from the third time or a fourth time, and obtain a second conduction saturation voltage drop of the main power switching tube to be tested in an offline state and in a conduction state at different times, the fourth time is greater than the third time, and a difference between the fourth time and the third time is less than or equal to a first threshold;
and the compensation module 50 is adapted to obtain corresponding junction temperature sampling values in the first functional relationship according to the second conduction saturation voltage drops at different times, and obtain the verified junction temperature at the first time according to the junction temperature sampling values at different times.
The converter includes: DC network, AC network and bridge power switch Guan Dianlu, said bridge power switchHave a plurality of power switch tube units in the pipe circuit, each power switch tube unit includes: the power supply comprises a main power switch tube and a diode connected with the main power switch tube in an inverse parallel mode; the alternating current network comprises a load inductor electrically connected with the main power switch tube, and the direct current network comprises a load resistor and a direct current bus power supply U which are connected in series DC 。
In an embodiment, the converter is exemplified as a three-phase full-bridge converter, and referring to fig. 4, a bridge type 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 comprises a first main power switch tube T1 and a first diode D1 reversely connected with the first main power switch tube T1 in parallel; the second power switch tube unit comprises a second main power switch tube T2 and a second diode D2 which is reversely connected with the second main power switch tube T2 in parallel; the third power switch tube unit comprises a third main power switch tube T3 and a third diode D3 which is reversely connected with the third main power switch tube T3 in parallel; the fourth power switch tube unit comprises a fourth main power switch tube T4 and a fourth diode D4 which is reversely connected with the fourth main power switch tube T4 in parallel; the fifth power switch tube unit comprises a fifth main power switch tube T5 and a fifth diode D5 which is reversely connected with the fifth main power switch tube T5 in parallel; the sixth power switch tube unit comprises a sixth main power switch tube T6 and a sixth diode D6 which is connected with the sixth main power switch tube T6 in an inverse parallel mode. The collector of the first main power switch tube T1, the collector of the third main power switch tube T3 and the collector of the fifth main power switch tube T5 are connected together and connected with a direct current bus power supply U DC The emitter of the second main power switch tube T2, the emitter of the fourth main power switch tube T4 and the emitter of the sixth main power switch tube T6 are connected together and are connected with a direct current bus power supply U DC Is connected. 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).
Referring to fig. 4, the current transformer further includes: first load inductance L A First load inductance L A One end of the first primary power switch tube is electrically connected with an emitting electrode of the first primary power switch tube T1 and a collector electrode of the second primary power switch tube T2; and a first load inductor L A A first load resistor R connected in series A First load inductance L A And the other end of the first load resistor R A Is connected with one end of the connecting rod; second load inductance L B Second load inductance L B One end of the first primary power switch tube is electrically connected with an emitting electrode of the third primary power switch tube T3 and a collector electrode of the fourth primary power switch tube T4; and a second load inductance L B Second load resistor R connected in series B Second load inductance L B And the other end of the first resistor and a second load resistor R B Is connected with one end of the connecting rod; third load inductance L C Third load inductance L C One end of the first switch is electrically connected with the emitter of the fifth main power switch tube T5 and the collector of the sixth main power switch tube T6; and a third load inductor L C A third load resistor R connected in series C Third load inductance L C And the other end of the third load resistor R C Is connected with one end of the connecting rod; a first load resistor R A The other end of (2), a second load resistor R B And the other end of the third load resistor R C The other ends of the two are connected together; first load inductance L A And a first load resistor R A Total voltage of upper output is U AN Second load inductance L B And a second load resistor R B Total voltage of upper output is U BN Third load inductance L C And a third load resistor R C Total voltage of upper output is U CN (ii) a Flows through the first load inductor L A And a first load resistor R A Is a first current I A Through the second load inductance L B And a second load resistor R B Is a second current I B Through the third load inductor L C And a third load resistor R C Is a third current I C . The sixth main power switch tube T6 to be tested has a conduction saturation voltage drop V CE . The sixth main power switch tube is selected in the embodimentAnd T6 is used as a main power switch tube to be tested. Of course, in other embodiments, other main power switch tubes may be arbitrarily selected as the main power switch tube to be tested.
Fig. 5 shows a topology structure of a junction temperature calibration module, where the junction temperature calibration module 10 is adapted to inject a constant current into a main power switching tube to be measured in a forward direction, and obtain a first mapping relationship between a first conduction saturation voltage drop and a junction temperature of the main power switching tube to be measured in an off-line state and a conduction state. Specifically, the junction temperature calibration module 10 injects the constant current into the main power switch tube to be tested from the collector of the main power switch tube to be tested, and specifically, when the sixth main power switch tube T6 is selected as the main power switch tube to be tested, the junction temperature calibration module 10 injects the constant current into the sixth main power switch tube T6 in the forward direction. The constant current is 5mA-200mA, such as 5mA, 10mA, 50mA, 100mA, 150mA or 200mA, so that the constant current is small, and the phenomenon that the conduction current in the main power switch tube to be tested is too large to generate heat can be avoided.
The junction temperature calibration module 10 includes a first constant current source 101, the first constant current source 101 is adapted to generate a constant current and inject the constant current into a main power switch tube to be tested in a forward direction, in a process that the junction temperature calibration module 10 injects the constant current into the main power switch tube to be tested in the forward direction, a negative end of the first constant current source 101 is connected with a collector of the main power switch tube to be tested, the main power switch tube to be tested is adapted to be placed on a heating platform 102, specifically, a chip corresponding to the main power switch tube to be tested is placed on the heating platform 102, the heating platform 102 heats the main power switch tube to be tested to a predetermined temperature, and a gate of the main power switch tube to be tested is conducted. In the process of calibrating the main power switching tube to be tested by the junction temperature calibration module 10, the injected constant current is kept constant all the time, and the main power switching tube to be tested at different junction temperatures T can be obtained by adjusting the temperature of the heating platform 102 j Lower first conduction saturation voltage drop V CE1 The first mapping relation between the first conduction saturation voltage drop and the junction temperature of the main power switch tube in an off-line state and a conduction state is obtained. Main power switch tube to be tested in first mapping relationThe junction temperature of (a) is calibrated by the temperature of the heated platen 102.
The first functional relationship to which the data fitting module 20 fits may be a polynomial or trigonometric function.
In this embodiment, under a constant small current, the conduction saturation voltage drop of the IGBT itself and the junction temperature are in an approximately linear relationship, that is, the first functional relationship can be fitted by a first-order polynomial. In a specific embodiment, the first functional relationship is fitted using a unary first order polynomial: t is j ＝A 1 ＊V CE1 +A 2 . Wherein A is 1 And A 2 Are coefficients in the first functional relationship.
It should be noted that, in this embodiment, the specific data fitting module 20 is not limited, as long as the data fitting module 20 realizes fitting into the first functional relationship according to the first mapping relationship.
Referring to fig. 6, fig. 6 is a timing chart of the emergency stop control module 30 applying the forced turn-off signal, the timing chart corresponds to the converter of fig. 4, in fig. 6, t0 to t1 are normal operation phases of the converter, during which an online junction temperature test can be performed; t 1-t 3 are the emergency stop turn-off stage; and t3-t 5 are small current testing stages for obtaining a second conduction saturation voltage drop for the main power switch tube to be tested. The initial time is t0, the first time is t1, the second time is t2, the third time is t3, and the fifth time is t5. It should be noted that, in other embodiments, t4 to t5 may also be selected as a low current test stage for obtaining a second conduction saturation voltage drop for the main power switch to be tested, the fourth time is t4, the fourth time t4 is greater than the third time t3, and a difference between the fourth time t4 and the third time t3 is less than or equal to a first threshold, where the first threshold is greater than zero and less than or equal to 10 milliseconds, for example, the first threshold is 1 millisecond, 2 milliseconds, 3 milliseconds, 4 milliseconds, 5 milliseconds, 6 milliseconds, 7 milliseconds, 8 milliseconds, 9 milliseconds, or 10 milliseconds.
t 0-t 1 are normal operation stages of the converter, and between t 0-t 1, the grid electrode of the main power switch tube is driven by a Pulse Width Modulation (PWM) signal of the converter, and different main power switch tubes have time sequences corresponding to the PWM signal required by self-operation. Specifically, in the converter of fig. 4, the timing of the PWM signal at the gate of the first main power switch tube T1 is PWM1 at the stage of T0 to T1 (see fig. 6), the timing of the PWM signal at the gate of the second main power switch tube T2 is PWM2 at the stage of T0 to T1 (see fig. 6), the timing of the PWM signal at the gate of the third main power switch tube T3 is PWM3 at the stage of T0 to T1 (see fig. 6), the timing of the PWM signal at the gate of the fourth main power switch tube T4 is PWM4 at the stage of T0 to T1 (see fig. 6), the timing of the PWM signal at the gate of the fifth main power switch tube T5 is PWM5 at the stage of T0 to T1 (see fig. 6), and the timing of the PWM signal at the gate of the sixth main power switch tube T6 is PWM6 at the stage of T0 to T1 (see fig. 6).
The emergency stop control module 30 applies a forced turn-off signal from the first time t1, and can turn off all the main power switch tubes in the converter in a short time (ms level), and the emergency stop control module 30 applies a time turn-off signal to all the main power switch tubes at the first time t1, for example, in this embodiment, the emergency stop control module 30 applies a low level to all the main power switch tubes until all the currents in all the load inductors at the third time t3 are all zero at the third time t3. The emergency stop control module 30 continuously applies a forced turn-off signal to the gates of all the main power switching tubes at the first time t1 to the third time t3, so as to ensure that all the main power switching tubes are turned off at the first time t1 to the third time t3, and the current at the first time t1 to the third time t3 does not flow through each main power switching tube. Specifically, for the converter in fig. 4, the sudden stop control module 30 applies a forced turn-off signal to 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 from the first time T1 until the third time T3, the first load inductor L A A second load inductor L B And a third load inductance L C All are zero at a third instant t3.
It should be noted that the third time t3 is electrically connected to the main power switch tubeThe moment when the currents in all the connected load voltages are exactly zero, in particular, for the converter in fig. 4, the third time t3 is the first load inductance L A A second load inductor L B And a third load inductance L C At the moment when the currents are all exactly zero. In the period from the first time t1 to the third time t3, the current in the partial load inductor may become zero first, and the current in the partial load inductor may become zero later until the current in all the load voltages at the third time t3 becomes zero. For the converter in fig. 4, when the sixth main power switch transistor T6 is the main power switch transistor to be tested, the third load inductor L C After the current in (1) first becomes zero at a second time t2, the first load inductance L A Current in and second load inductance L B The current in (b) becomes zero synchronously at a third instant t3.
It should be noted that the emergency stop control module 30 is adapted to apply a forced turn-off signal so that the current in the load inductor electrically connected to the main power switch tube to be tested becomes zero at the second time; the second time is greater than the first time and less than or equal to the third time. The timing sequence in fig. 6 is illustrated with the second time being greater than the first time and less than the third time as an example. In other embodiments, for converters with other structures or when other main power switching tubes are selected as the main power switching tubes to be tested, the second time may also be equal to the third time.
Since the forced turn-off signal is applied to all the main power switch tubes in the converter from the first time t1, the power switch tube unit enters a fast follow current mode. Specifically, when a main power switch tube unit to be tested performs fast follow current on an inductor electrically connected with a main power switch tube to be tested, the main power switch tube to be tested is in a turn-off state, current does not flow through the main power switch tube to be tested, a diode connected with the main power switch tube to be tested in reverse parallel conducts through overcurrent, reverse voltage is applied to two ends of a load inductor electrically connected with the main power switch tube to be tested, so that the current in the load inductor electrically connected with the main power switch tube to be tested is fast returned to zero, and at the moment, a branch circuit where the load inductor electrically connected with the main power switch tube to be tested is located is disconnected and damping oscillation cannot continue to return to zero; when a certain main power switch tube which is not to be tested carries out rapid follow current on an inductor which is electrically connected with the main power switch tube which is not to be tested, the main power switch tube which is not to be tested is in a turn-off state, current does not flow through the main power switch tube which is not to be tested, a diode which is reversely connected in parallel with the main power switch tube which is not to be tested is conducted to flow through the current, reverse voltage is applied to two ends of a load inductor which is electrically connected with the main power switch tube which is not to be tested, so that the current in the load inductor which is electrically connected with the main power switch tube which is not to be tested is rapidly returned to zero, and at the moment, a branch circuit where the load inductor which is electrically connected with the main power switch tube which is not to be tested is located is disconnected, and damping oscillation is not continuously returned to zero. In summary, the interval between the first time t1 and the third time t3 is made smaller.
In this embodiment, for the current transformer in fig. 4, when the sixth main power switch tube T6 is the main power switch tube to be tested, referring to fig. 6 and 7 in combination, the sixth power switch unit provides the third load inductor L from the first time T1 to the second time T2 C And performing fast follow current, wherein 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 in an off state from the first time T1 to the second time T2, the sixth diode D6 is conducted to flow current, the first diode T1 is conducted to flow current, the third diode T3 is conducted to flow current, and the second diode T2, the fourth diode T4 and the fifth diode T5 are not conducted. The first current I flows from the first time t1 to the second time t2 A And the second current I B Is equal to the third current I C The reverse voltage is applied to the third load inductor Lc, so that the current in the third load inductor Lc rapidly returns to zero at the time t2, and the branch where the third load inductor Lc is located is disconnected at the time t2 without continuing damping oscillation to return to zero. The current flowing through the third inductor Lc is at a rate dI of change from the first time t1 to the second time t2 C /dt＝(U CN －I C ＊R C ) /Lc; at a first time t1 to a second time t2, U CN ＝(2/3)＊U DC . In the stage from the second time T2 to the third time T3, the first main power switch tube to the sixth main power switch tube are all turned off, the sixth diode D6, the second diode T2, the fourth diode T4 and the fifth diode T5 are not conducted, the first diode T1 and the third diode T3 are conducted to flow current, but the first current I is caused to flow through the first diode T1 and the third diode T3 A And a second current I B In the same direction, in this case, the energy stored in the inductor is transferred to the dc bus power supply U in a reactive manner DC Forming a first current I on the capacitor side A And a second current I B And at the same time becomes zero at a third instant t3. In one embodiment, (t 3-t 1) is 1ms to 5ms.
It should be noted that the selection of the first time t1 is not limited by a special condition, and the emergency shutdown step may be performed at any time after an end time of the operation of the converter, and then the time when the emergency shutdown step is performed is taken as the first time t1. Both the second time t2 and the third time t3 are tested.
The sampling module 40 tests the current flowing through all load inductors electrically connected to the main power switch tube from the first time t1 to the third time t3, and specifically, for the converter of fig. 4, the sampling module 40 tests the first load inductor L from the first time t1 to the third time t3 A A second load inductor L B And the current in the third load inductance Lc, the second time t2 and the third time t3 are known from the test.
The sampling module 40 is further adapted to inject a constant current into the main power switching tube to be tested in the forward direction from the third time t3 or the fourth time t4, and obtain a second conduction saturation voltage drop of the main power switching tube to be tested at different times in an off-line state and a conduction state. Specifically, for the converter in fig. 4, when the sixth main power switch tube T6 is selected by the main power switch tube to be tested, the sampling module 40 is adapted to inject a constant current into the sixth main power switch tube T6 from the third time T3 or the fourth time T4 in the forward direction, and obtain the second conduction saturation voltage drop V of the sixth main power switch tube T6 in the off-line state and in the conduction state at different times CE2 . In this embodiment, the sampling module 40 is adapted to self-sampleA third time T3 is started to inject a constant current in a forward direction into the sixth main power switch T6 as an example.
The sampling module 40 (refer to fig. 2) includes a voltage sampling module 41 and a current sampling module 42, where the voltage sampling module 41 is adapted to inject a constant current into the main power switch tube to be tested from the third time t3 or the fourth time t4 in the forward direction, and obtain a second conduction saturation voltage drop V of the main power switch tube to be tested at different times in the off-line state and the conduction state CE2 The current sampling module 42 is adapted to test the current flowing through all load inductors electrically connected to the main power switch tube during the period from the first time t1 to the third time t3. The sampling module 40 further includes a second constant current source 43, the second constant current source 43 is adapted to generate a constant current and inject the constant current into the main power switching tube to be tested in the forward direction, in the process that the sampling module 40 injects the constant current into the main power switching tube to be tested in the forward direction, a negative end of the second constant current source is connected to a collector of the main power switching tube to be tested, the second constant current source always injects the constant current into the main power switching tube to be tested in the forward direction, referring to fig. 6, between a third time T3 and a fifth time T5, a high level is applied to a gate of the main power switching tube to be tested to conduct, specifically, a high level is applied to a gate of the sixth main power switching tube T6 to conduct, and a low level is applied to gates of the first main power switching tube T1 to the fifth power switching tube T5 to continue to keep an off state.
It should be noted that, when the second conduction saturation voltage drop V is sampled from the fourth time t4 CE2 Meanwhile, a high level is applied to the grid electrode of the main power switch tube to be tested between the fourth time T4 and the fifth time T5 to conduct, and a low level is applied to the grid electrode of the first main power switch tube T1 to the fifth power switch tube T5 between the third time T3 and the fifth time T5 to continuously keep the off state.
In this embodiment, the constant current injected by the sampling module 40 to the main power switch tube to be tested in the forward direction is 5mA to 200mA, such as 5mA, 10mA, 50mA, 100mA, 150mA or 200mA.
In a specific embodiment, the constant current injected by the sampling module 40 into the main power switch to be tested in the forward direction is equal to the constant current injected by the junction temperature calibration module 10 into the main power switch to be tested in the forward direction, so as to improve the accuracy of the finally obtained verification junction temperature.
In this embodiment, the compensation module 50 (refer to fig. 3) includes a junction temperature sampling value obtaining unit 51 and a junction temperature compensation obtaining unit 52, where the junction temperature sampling value obtaining unit 51 is adapted to obtain the second conduction saturation voltage drop V according to different time instants CE2 And acquiring a corresponding junction temperature sampling value in the first functional relationship, wherein the junction temperature compensation acquiring unit 52 is adapted to acquire the verified junction temperature at the first time t1 according to the junction temperature sampling values at different times.
In one embodiment, the junction temperature compensation acquiring unit 52 includes: | T 1 －T m ∣＝q×(t m －t 1 ) 1/2 (ii) a Wherein, t m Is the m-th time, t 1 The first time, the mth time is more than or equal to the third time, T m Is the junction temperature sampling value at the m-th moment, T 1 For the verified junction temperature at the first time instant, q is the coefficient in the junction temperature compensation acquisition unit 52.
The junction temperature online monitoring data verification system further comprises: the online junction temperature testing module is suitable for testing the online junction temperature of the main power switching tube to be tested at and before the first moment; the comparison module is suitable for acquiring the difference value between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment, and acquiring the test precision of the on-line junction temperature test module according to the difference value between the on-line junction temperature at the first moment and the verification junction temperature at the first moment; and the correction module is suitable for correcting the on-line junction temperature test module when the difference value between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment is larger than a second threshold value until the difference value between the on-line junction temperature and the verification junction temperature is smaller than the second threshold value. The second threshold can be set according to the accuracy requirements.
In this embodiment, no specific limitation is imposed on the online junction temperature test module, and any module capable of online testing junction temperature in the prior art is available.
Correspondingly, another embodiment of the present invention further provides a junction temperature online monitoring data verification method, which is suitable for obtaining a verified junction temperature of a main power switch tube to be tested in a current transformer, where the current transformer includes a plurality of power switch tube units, and each power switch tube unit includes: the power supply comprises a main power switch tube and a diode connected with the main power switch tube in an inverse parallel mode; the converter further includes a load inductor electrically connected to the main power switch tube, and referring to fig. 10, the converter includes the following steps:
s01: injecting a constant current into a main power switch tube to be tested in a forward direction, and acquiring a first mapping relation between a first conduction saturation voltage drop and junction temperature of the main power switch tube to be tested in an off-line state and a conduction state;
s02: fitting the data in the first mapping relation to obtain a first functional relation, wherein the first functional relation takes the first conduction saturation voltage drop as an independent variable and takes the junction temperature of the main power switching tube to be measured as a dependent variable;
s03: applying a forced turn-off signal to all main power switch tubes in the converter in an online working state from the first moment until all currents in all load inductors are tested to be zero at the third moment;
s04: injecting a constant current into the main power switching tube to be tested from a third moment or a fourth moment in a forward direction, and acquiring a second conduction saturation voltage drop of the main power switching tube to be tested at different moments in an off-line state and a conduction state, wherein the fourth moment is greater than the third moment and the difference between the fourth moment and the third moment is less than or equal to a first threshold;
s05: acquiring corresponding junction temperature sampling values in the first functional relation according to second conduction saturation voltage drops at different moments;
s06: and obtaining the verified junction temperature at the first moment according to the junction temperature sampling values at different moments.
In the process of injecting constant current to the main power switching tube to be tested in the forward direction, the main power switching tube to be tested is suitable for being placed on the heating platform, and the junction temperature of the main power switching tube to be tested in the first mapping relation is calibrated by the temperature of the heating platform.
The process of applying the forced turn-off signal to all main power switch tubes in the converter in the online working state from the first moment comprises the following steps: applying a forced turn-off signal to a main power switching tube to be tested from a first moment to enable current in a load inductor electrically connected with the main power switching tube to be tested to become zero at a second moment; the second time is greater than the first time and less than or equal to the third time.
The constant current injected into the main power switch tube to be tested in the forward direction is 5mA-200mA; the constant current injected into the main power switch tube to be tested in the forward direction is 5mA-200mA.
According to the junction temperature sampling value and the formula | T at different time instants 1 －T m ∣＝q×(t m －t 1 ) 1/2 Obtaining a verification junction temperature at a first moment; wherein, t m Is the m-th time, t 1 The first time, the mth time is more than or equal to the third time, T m Is the junction temperature sampling value at the m-th moment, T 1 Q is the formula | T for the verified junction temperature at the first instant in time 1 －T m ∣＝q×(t m －t 1 ) 1/2 Coefficient (b) in (c).
In one embodiment, t m1 The second conduction saturation voltage drop of the main power switch tube to be measured at any moment is V CE2 (t m1 ) Will V CE2 (t m1 ) Substituting the first function relation to calculate the junction temperature sampling value T of the main power switch tube to be tested m1 。t m2 The second conduction saturation voltage drop of the main power switch tube to be measured at any moment is V CE2 (t m2 ) Will V CE2 (t m2 ) The junction temperature sampling value T of the main power switch tube to be measured is calculated in the first functional relation m2 。t m3 The second conduction saturation voltage drop of the main power switch tube to be measured at any moment is V CE2 (t m3 ) Will V CE2 (t m3 ) The junction temperature sampling value T of the main power switch tube to be measured is calculated in the first functional relation m3 。t m4 The second conduction saturation voltage drop of the main power switch tube to be measured at any moment is V CE2 (t m4 ) Will V CE2 (t m4 ) The junction temperature sampling value T of the main power switch tube to be measured is calculated in the first functional relation m4 。
Mixing the above t m1 、t m2 、t m3 、t m4 、T m1 、T m2 、T m3 And T m4 The value of (a) is taken into | T 1 －T m ∣＝q×(t m －t 1 ) 1/2 The specific value of q is obtained, i.e. the fitted curve in fig. 9 is obtained, and the junction temperature at t1 is inversely deduced in the fitted curve in fig. 9 as the verified junction temperature at t1. Referring to fig. 9, the horizontal axis of the graph is time in seconds, and the vertical axis is the junction temperature variation of the main power switch tube to be measured.
The junction temperature online monitoring data verification method further comprises the following steps: testing the online junction temperature of the main power switch tube to be tested online; acquiring a difference value between the online junction temperature of a main power switch tube to be tested at a first moment and the verification junction temperature at the first moment; and obtaining the test precision of the online junction temperature test module according to the difference between the online junction temperature at the first moment and the verification junction temperature at the first moment.
And when the difference between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment is larger than a second threshold, correcting the process of on-line testing the main power switching tube to be tested until the difference between the on-line junction temperature and the verification junction temperature is smaller than or equal to the second threshold.
It should be noted that the concept of the present invention can also obtain the verified junction temperature of other main power switch tubes in the converter in fig. 4. The concept of the invention can also obtain the verification junction temperature of the main power switch to be tested of the current transformer with other structures. Other configurations of converters such as those in H-bridge circuits and those in single-phase half-bridge circuits.
In this embodiment, the method further includes: and evaluating the heat dissipation capacity of the converter by adopting the verified junction temperature, wherein when the verified junction temperature at the first moment is less than or equal to the junction temperature threshold of the device, the heat dissipation capacity of the converter meets the requirement.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (18)
1. A junction temperature on-line monitoring data verification system is suitable for obtaining verification junction temperature of a main power switch tube to be tested in a current transformer, wherein the current transformer comprises a plurality of power switch tube units, and each power switch tube unit comprises: the power supply comprises a main power switch tube and a diode connected with the main power switch tube in an inverse parallel mode; the converter also comprises a load inductor electrically connected with the main power switch tube; it is characterized by comprising:
the junction temperature calibration module is suitable for injecting constant current into the main power switching tube to be tested in the forward direction, and acquiring a first mapping relation between a first conduction saturation voltage drop and junction temperature of the main power switching tube to be tested in an off-line state and a conduction state;
the data fitting module is suitable for fitting data in the first mapping relation to obtain a first functional relation, and the first functional relation takes the first conduction saturation voltage drop as an independent variable and takes the junction temperature of the main power switching tube to be measured as a dependent variable;
the emergency stop control module is suitable for applying forced turn-off signals to all main power switch tubes in the converter in an online working state from the first moment until all currents in all load inductors are zero at the third moment;
the sampling module is suitable for testing currents flowing through all load inductors electrically connected with the main power switch tube in the process from the first moment to the third moment, the sampling module is further suitable for injecting constant currents into the main power switch tube to be tested from the third moment or the fourth moment in the forward direction, second conduction saturation voltage drops of the main power switch tube to be tested at different moments in an off-line state and a conduction state are obtained, the fourth moment is greater than the third moment, and the difference value between the fourth moment and the third moment is smaller than or equal to a first threshold value;
and the compensation module is suitable for acquiring corresponding junction temperature sampling values in the first functional relation according to the second conduction saturation voltage drops at different moments, and acquiring the verified junction temperature at the first moment according to the junction temperature sampling values at different moments.
2. The system for verifying the junction temperature online monitoring data as claimed in claim 1, wherein the junction temperature calibration module is adapted to inject a constant current of 5mA-200mA in the forward direction of the main power switching tube to be tested; the sampling module is suitable for injecting a constant current of 5mA-200mA in the forward direction into the main power switch tube to be tested.
3. The system for verifying junction temperature online monitoring data as claimed in claim 1, wherein the sampling module includes a voltage sampling module and a current sampling module, the voltage sampling module is adapted to inject a constant current to the main power switching tube to be tested in a forward direction from a third time or a fourth time, and obtain a second conduction saturation voltage drop of the main power switching tube to be tested in an off-line state and in a conduction state at different times, and the current sampling module is adapted to test a current flowing through all load inductors electrically connected to the main power switching tube in a process from the first time to the third time.
4. The junction temperature online monitoring data verification system according to claim 1, wherein the scram control module is adapted to apply a forced turn-off signal so that a current in a load inductor electrically connected to the main power switch tube to be tested becomes zero at a second moment; the second time is greater than the first time and less than or equal to the third time.
5. The system for verifying junction temperature online monitoring data as claimed in claim 1, further comprising: the online junction temperature testing module is suitable for testing the online junction temperature of the main power switching tube to be tested at and before the first moment;
and the comparison module is suitable for acquiring the difference value between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment, and acquiring the test precision of the on-line junction temperature test module according to the difference value between the on-line junction temperature at the first moment and the verification junction temperature at the first moment.
6. The system for verifying on-line junction temperature monitoring data as claimed in claim 5, further comprising: and the correction module is suitable for correcting the on-line junction temperature test module when the difference value between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment is larger than a second threshold value until the difference value between the on-line junction temperature and the verification junction temperature is smaller than or equal to the second threshold value.
7. The system for verifying the junction temperature on-line monitoring data as claimed in claim 1, wherein the compensation module comprises a junction temperature sampling value obtaining unit and a junction temperature compensation obtaining unit, the junction temperature sampling value obtaining unit is adapted to obtain corresponding junction temperature sampling values in the first functional relationship according to second conduction saturation voltage drops at different times, and the junction temperature compensation obtaining unit is adapted to obtain the verified junction temperature at the first time according to the junction temperature sampling values at the different times.
8. The system for verifying the junction temperature online monitoring data as claimed in claim 7, wherein the junction temperature compensation obtaining unit comprises: | T 1 －T m ∣＝q×(t m －t 1 ) 1/2 (ii) a Wherein, t m Is the m-th time, t 1 The first time, the mth time is more than or equal to the third time, T m Is the junction temperature sampling value at the m-th moment, T 1 And q is the verified junction temperature at the first moment, and q is a coefficient in the junction temperature compensation acquisition unit.
9. The system for verifying on-line junction temperature monitoring data as claimed in claim 1, wherein the first threshold is greater than zero and less than or equal to 10 milliseconds.
10. A junction temperature on-line monitoring data verification method is suitable for obtaining verification junction temperature of a main power switch tube to be tested in a current transformer, the current transformer comprises a plurality of power switch tube units, and each power switch tube unit comprises: the power supply comprises a main power switch tube and a diode connected with the main power switch tube in an inverse parallel mode; the converter still includes with main power switch tube electricity is connected's load inductance, its characterized in that includes:
injecting a constant current into a main power switch tube to be tested in a forward direction, and acquiring a first mapping relation between a first conduction saturation voltage drop and junction temperature of the main power switch tube to be tested in an off-line state and a conduction state;
fitting the data in the first mapping relation to obtain a first functional relation, wherein the first functional relation takes the first conduction saturation voltage drop as an independent variable and takes the junction temperature of the main power switching tube to be measured as a dependent variable;
applying a forced turn-off signal to all main power switch tubes in the converter in an online working state from the first moment until all currents in all load inductors are tested to be zero at the third moment;
injecting a constant current into the main power switching tube to be tested from a third moment or a fourth moment in a forward direction, and acquiring a second conduction saturation voltage drop of the main power switching tube to be tested at different moments in an off-line state and a conduction state, wherein the fourth moment is greater than the third moment and the difference between the fourth moment and the third moment is less than or equal to a first threshold;
acquiring corresponding junction temperature sampling values in the first functional relation according to second conduction saturation voltage drops at different moments;
and obtaining the verified junction temperature at the first moment according to the junction temperature sampling values at different moments.
11. The method for verifying junction temperature online monitoring data as claimed in claim 10, further comprising: testing the online junction temperature of the main power switch tube to be tested online; acquiring a difference value between the online junction temperature of a main power switch tube to be tested at a first moment and the verification junction temperature at the first moment; and obtaining the test precision of the online junction temperature test module according to the difference between the online junction temperature at the first moment and the verification junction temperature at the first moment.
12. The method for verifying junction temperature online monitoring data as claimed in claim 11, further comprising: and when the difference between the on-line junction temperature of the main power switching tube to be tested at the first moment and the verification junction temperature at the first moment is larger than a second threshold, correcting the process of on-line testing the main power switching tube to be tested until the difference between the on-line junction temperature and the verification junction temperature is smaller than or equal to the second threshold.
13. The method for verifying the junction temperature online monitoring data as claimed in claim 10, wherein the step of applying a forced turn-off signal to all main power switching tubes in the converter in the online working state from the first moment comprises: applying a forced turn-off signal to a main power switching tube to be tested from a first moment to enable current in a load inductor electrically connected with the main power switching tube to be tested to become zero at a second moment; the second time is greater than the first time and less than or equal to the third time.
14. A junction temperature online monitoring data verification method as claimed in claim 10, wherein in a process of injecting a constant current in a forward direction into the main power switching tube to be tested, the main power switching tube to be tested is adapted to be placed on the heating platform, and the junction temperature of the main power switching tube to be tested in the first mapping relation is calibrated by the temperature of the heating platform.
15. The junction temperature online monitoring data verification method as claimed in claim 10, wherein the constant current injected in the forward direction to the main power switch tube to be tested is 5mA-200mA; the constant current injected into the main power switch tube to be tested in the forward direction is 5mA-200mA.
16. The method of claim 10The method for verifying the junction temperature on-line monitoring data is characterized in that the method is based on the junction temperature sampling value and the formula | T at different moments 1 －T m ∣＝q×(t m －t 1 ) 1/2 Obtaining a verification junction temperature at a first moment;
wherein, t m Is the m-th time, t 1 The first time, the mth time is more than or equal to the third time, T m Is the junction temperature sampling value at the m-th moment, T 1 Q is the formula | T for the verified junction temperature at the first instant in time 1 －T m ∣＝q×(t m －t 1 ) 1/2 Coefficient (2) of (1).
17. The online junction temperature monitoring data verification method according to claim 10, wherein the first threshold is greater than zero and less than or equal to 10 milliseconds.
18. The method for verifying junction temperature online monitoring data as claimed in claim 10, further comprising: and evaluating the heat dissipation capacity of the converter by adopting the verified junction temperature, wherein when the verified junction temperature at the first moment is less than or equal to the junction temperature threshold of the device, the heat dissipation capacity of the converter meets the requirement.
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