Method and system for constructing a junction temperature monitoring model based on transient thermal behavior

Abstract

The application discloses a construction method and system of a junction temperature monitoring model based on transient thermal behavior, the junction temperature monitoring model comprising a plurality of sub-models, the calibration currents corresponding to the sub-models being different from each other, and the calibration current being a single pulse current; each sub-model is sequentially taken as a target sub-model, and the method for constructing the target sub-model comprises the following steps: applying a corresponding calibration current to a target power device kept in a conduction state, so that the target power device is heated, and the instantaneous collector-emitter voltage of the target power device is monitored in real time to obtain corresponding monitoring data; the heating power is calculated based on the calibration current and the monitoring data to obtain corresponding power data; the junction temperature data is calculated based on the power data and the thermal impedance curve corresponding to the target power device; and the target sub-model is constructed based on the junction temperature data and the monitoring data. The application does not need to create a steady-state thermal condition externally, and is low in cost and high in efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrical variable measurement, in particular to a method and system for constructing a junction temperature monitoring model based on transient thermal behavior, and to an online junction temperature monitoring method and system based on transient thermal behavior. BACKGROUND

[0002] The junction temperature (T j ) of a power semiconductor device is a key parameter determining its safety and reliability. Accurate online junction temperature monitoring is of great significance for device health management, life prediction and prevention of thermal failure. In the prior art, junction temperature monitoring is usually realized based on temperature sensitive electrical parameters (TSEP) of the device itself;

[0003] In the existing scheme, in order to obtain the temperature sensitive electrical parameters and the junction temperature, it is usually necessary to pre-calibrate under steady-state thermal conditions, i.e. to place the device on a heating table or a thermostat, to pass through a corresponding test current (low current such as 100 mA or short high current pulse such as 100 μs) at a set different temperature, and to measure the corresponding temperature sensitive electrical parameters, to establish a T j -TSEP relationship according to the set temperature and the obtained temperature sensitive electrical parameters, so as to determine the junction temperature based on the corresponding temperature sensitive electrical parameters in actual working conditions, and to realize online junction temperature monitoring. SUMMARY

[0004] The present application provides a method and system for constructing a junction temperature monitoring model based on transient thermal behavior, and an online junction temperature monitoring method and system based on the constructed junction temperature monitoring model, aiming at the mapping of temperature sensitive electrical parameters and junction temperature established under steady-state thermal conditions in the prior art, which has the problems of complicated calibration operation and low efficiency.

[0005] To solve the above technical problems, the present application solves them by the following technical solutions:

[0006] In a first aspect, the present application provides a method for constructing a junction temperature monitoring model based on transient thermal behavior;

[0007] The junction temperature monitoring model comprises a plurality of sub-models, and each sub-model is used to indicate the relationship between the instantaneous collector-emitter voltage and the junction temperature of the target power device under a corresponding calibration current. The calibration currents corresponding to the sub-models are different from each other, and the calibration current is a single pulse current.

[0008] Each sub-model is sequentially taken as a target sub-model, and the method for constructing the target sub-model comprises the following steps:

[0009] A corresponding calibration current is applied to a target power device in a conducting state to heat up the target power device, and an instantaneous collector-emitter voltage of the target power device is monitored in real time to obtain corresponding monitoring data;

[0010] A heating power is calculated based on the calibration current and the monitoring data to obtain corresponding power data;

[0011] Corresponding junction temperature data are calculated based on the power data and a thermal impedance curve corresponding to the target power device;

[0012] The target sub-model is constructed based on the junction temperature data and the monitoring data.

[0013] Based on conventional concepts, it is generally believed by those skilled in the art that the measurement result under transient thermal behavior is less accurate than that under steady-state thermal conditions (only current as a variable), and the transient process is difficult to model, so those skilled in the art often avoid studying thermal transients and only establish a mapping between temperature-sensitive electrical parameters and junction temperature under steady-state conditions;

[0014] According to the existing research results based on pre-calibration under steady-state thermal conditions, it is known that:

[0015] Not affected by sampling delay or system response speed, it is easier to achieve repeatability and consistency;

[0016] The relationship between temperature-sensitive electrical parameters (such as V GS or V CE ) and junction temperature is approximately linear, which is beneficial for high-precision fitting;

[0017] Therefore, those skilled in the art default that the steady-state thermal condition is the only way to achieve reliable calibration.

[0018] The present application discards the traditional calibration thinking of pursuing stable readings, and determines the junction temperature in the calibration process without relying on external thermal steady-state environment creation (the existing technology needs a thermostat to create multiple stable temperature points), but completes it in the thermal transient state (single pulse heating without external temperature control). Not only can it reduce costs and improve efficiency, but it can also be applied to various scenarios.

[0019] In a second aspect, the present application proposes a construction system of a junction temperature monitoring model based on transient thermal behavior;

[0020] The junction temperature monitoring model includes a plurality of sub-models, and the sub-models are used to indicate the relationship between the instantaneous collector-emitter voltage of the target power device and the junction temperature under the corresponding calibration current. The calibration currents corresponding to each sub-model are different from each other, and the calibration current is a single pulse current.

[0021] The construction system includes:

[0022] a test module configured to apply a corresponding calibration current to a target power device in a conducting state to heat up the target power device;

[0023] a monitoring module configured to monitor an instantaneous collector-emitter voltage of the target power device in real time to obtain corresponding monitoring data;

[0024] a junction temperature calculation module configured to calculate a heating power based on the corresponding calibration current and the monitoring data to obtain corresponding power data, and to calculate corresponding junction temperature data based on the corresponding power data and a thermal impedance curve corresponding to the target power device;

[0025] a data fitting module configured to construct a sub-model corresponding to the calibration current based on the corresponding junction temperature data and the monitoring data.

[0026] The test module in the prior art needs a constant temperature device to create a thermal steady state environment, but the test module in the present application can be realized only by a pulse power supply and a sampling circuit without additional temperature control equipment, which is much lower in cost compared with the prior art.

[0027] In a third aspect, the present application provides an online junction temperature monitoring method based on transient thermal behavior, comprising the following steps:

[0028] acquiring a working current and an instantaneous collector-emitter voltage corresponding to a conducting power device to be tested based on a preset monitoring rule;

[0029] determining a corresponding junction temperature according to the working current and the instantaneous collector-emitter voltage based on a preset junction temperature monitoring model, the junction temperature monitoring model being a junction temperature monitoring model constructed according to the construction method of any one of the above aspects, and specifically comprising:

[0030] taking a sub-model corresponding to the working current in the junction temperature monitoring model as a target model;

[0031] calculating a corresponding junction temperature according to the instantaneous collector-emitter voltage based on the target model.

[0032] The junction temperature monitoring model constructed based on transient thermal behavior in the present application is suitable for online junction temperature monitoring of different working currents, has a wide range of applications, and does not affect the normal operation of the power device to be tested during the monitoring process.

[0033] In a fourth aspect, an online junction temperature monitoring system based on transient thermal behavior is provided, comprising:

[0034] a collection module configured to acquire a working current and an instantaneous collector-emitter voltage corresponding to a conducting power device to be tested based on a preset monitoring rule;

[0035] The computing module is configured to determine a corresponding junction temperature based on a preset junction temperature monitoring model and the working current and the instantaneous collector-emitter voltage, wherein the junction temperature monitoring model is obtained according to the construction method in any one of the preceding embodiments.

[0036] The computing module comprises:

[0037] The matching unit is configured to take a sub-model corresponding to the working current in the junction temperature monitoring model as a target model.

[0038] The computing unit is configured to calculate a corresponding junction temperature based on the target model and the instantaneous collector-emitter voltage.

[0039] The present application has the following technical effects:

[0040] Compared with the prior art, the present application abandons the traditional calibration thinking of pursuing stable readings, and determines the junction temperature in the calibration process without relying on external thermal steady-state environment creation (the prior art requires a thermostat to create multiple stable temperature points), but completes it in the self-thermal transient state (single pulse heating without external temperature control), which not only reduces the cost and improves the efficiency, but also is applicable to various scenes. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 is a working flow diagram of a construction method of a junction temperature monitoring model based on transient thermal behavior of the present application;

[0043] Figure 2 is a schematic diagram of the thermal impedance curve of the measured IGBT module in the case;

[0044] Figure 3 is Figure 2 is a power waveform schematic diagram of the corresponding measured IGBT module under the conduction duration of 400 milliseconds at 160A;

[0045] Figure 4 is Figure 2 is a schematic diagram of the instantaneous collector-emitter voltage curve and the junction temperature curve corresponding to the measured IGBT module in the process of conduction of 400 milliseconds at 160A;

[0046] Figure 5 isFigure 2 The corresponding measured IGBT module is a transient collector-emitter voltage and junction temperature mapping curve diagram under 160A;

[0047] Figure 6 Based on Figure 5 The online junction temperature and the monitoring result based on the infrared monitoring junction temperature are compared in the transient collector-emitter voltage and junction temperature mapping curve diagram shown in the figure;

[0048] Figure 7 It is a module connection diagram of the junction temperature monitoring model construction system based on transient thermal behavior of the application;

[0049] Figure 8 It is Figure 7 The current diagram of the measurement module in the figure. DETAILED DESCRIPTION

[0050] The application will be further described in detail below in combination with embodiments, and the following embodiments are an explanation of the application and the application is not limited to the following embodiments.

[0051] Example 1, a method for constructing a junction temperature monitoring model based on transient thermal behavior;

[0052] The junction temperature monitoring model includes a plurality of sub-models, and the sub-models are used to indicate the relationship between the transient collector-emitter voltage and the junction temperature of the target power device under the corresponding calibration current. In this embodiment, the temperature-sensitive thermal parameter is the transient collector-emitter voltage V ce,inst (hereinafter referred to as V ce ), and the sub-model is a T j -V ce relationship curve;

[0053] The calibration currents corresponding to each sub-model in this embodiment are different from each other, and the calibration current is a single pulse current. Each sub-model is sequentially taken as a target sub-model, and the method for constructing the target sub-model includes the following steps:

[0054] S100, a corresponding calibration current is applied to a target power device in a conducting state, the target power device is warmed up, and the transient collector-emitter voltage of the target power device is monitored in real time to obtain corresponding monitoring data;

[0055] The monitoring data includes the transient collector-emitter voltage corresponding to a plurality of sampling points;

[0056] When the target power device is turned on, a transient self-heating is generated in the device by applying a calibration current, at which time the target power device starts to warm up, and the transient collector-emitter voltage V ce and the junction temperature T j will rise at the same time, wherein V ceThe data can be easily monitored using existing voltage monitoring devices; in this embodiment, an oscilloscope is used.

[0057] S200: Calculate the heating power based on the calibration current and the monitoring data to obtain the corresponding power data;

[0058] The power data includes the heating power corresponding to each sampling point;

[0059] Since the calibration current is a constant single-pulse current, the corresponding heating power can be accurately calculated based on the calibration current and the monitored data.

[0060] Given the current (calibration current) and voltage (instantaneous collector-emitter voltage V) ce Under the premise that the corresponding heating power can be easily calculated by those skilled in the art based on existing technology, this specification does not limit it in detail.

[0061] S300. Based on the power data and the thermal impedance curve corresponding to the target power device, calculate the corresponding junction temperature data.

[0062] The thermal impedance curve of the target power device is measured in advance based on a thermal impedance testing platform. In this embodiment, the thermal impedance curve of the target power device is measured in advance based on the existing publicly available thermal testing platform T3ster platform.

[0063] The formula for calculating the junction temperature based on power data and thermal impedance curves is as follows:

[0064] T j (t)=P(t)*Z th (t)+T f,m ;

[0065] in:

[0066] t represents a point in time;

[0067] T j (t) represents the junction temperature at point t;

[0068] P(t) represents the power at point t;

[0069] Z th (t) represents the transient thermal impedance at point t. Given the thermal impedance curve, those skilled in the art can easily obtain the transient thermal impedance at a specified time point.

[0070] * indicates a convolution operation;

[0071] T f,m This represents the ambient temperature. In this embodiment, the test was conducted in a water-cooled environment, and the coolant inlet temperature was taken as T. f,mAs tested based on air cooling, the ambient temperature can be directly taken as T f,m .

[0072] P(t)* Z th (t) represents the transient junction temperature change, and the calculation formula is:

[0073] ;

[0074] Wherein, τ is an integral variable.

[0075] S400, based on the junction temperature data and the monitoring data, the target sub-model is constructed.

[0076] That is, based on the monitoring data measured in step S100 and the junction temperature data calculated in step S300, data fitting is performed to obtain the corresponding T j -V ce relationship curve, that is, the sub-model under the corresponding calibration current.

[0077] The embodiment applies a single pulse current to the turned-on target power device, during the application, the target power device makes the device experience a predictable temperature rise process in a very short time, the instantaneous collector-emitter voltage of the target power device is collected during the temperature rise process, and the junction temperature is derived, a single current pulse is applied, a plurality of groups of instantaneous collector-emitter voltage and junction temperature corresponding to each other are obtained, and the sub-model under the corresponding calibration current is constructed.

[0078] Compared with the existing pre-calibration scheme based on steady-state thermal conditions, the embodiment has the following technical advantages:

[0079] The existing technology needs a constant temperature device to create a thermal steady state environment, and in the embodiment, only a pulse power supply and a sampling circuit are needed to realize it, which can be seamlessly embedded in the existing T3ster thermal impedance test platform, without the need for additional temperature control equipment, and the cost is much lower than that of the existing technology.

[0080] The existing technology is based on the heating and maintaining of an incubator to create multiple stable temperature points in turn to realize the calibration of the junction temperature and the corresponding temperature sensitive electrical parameters, which is time-consuming, cumbersome to operate, and low in calibration efficiency. The embodiment applies a single pulse current to complete the calibration of the instantaneous collector-emitter voltage and the junction temperature under a corresponding current once, which meets the demand of rapid calibration today.

[0081] Since the self-heating of the target power device during the pre-calibration process based on steady-state thermal conditions will cause a large deviation in the calibration results, only low-current calibration or short-time high-current calibration can be based on; for the low-current calibration scheme, although the self-heating error can be reduced, this method is difficult to realize online monitoring under actual operating conditions, the application range is limited, and the industrial applicability is poor; for short-time high-current calibration, under high-current pulse conditions, self-heating effect inevitably occurs in the device, and even if the application time of the high-current pulse is reduced, there is still a large deviation in the relationship between the temperature-sensitive electrical parameters and the junction temperature.

[0082] The prior art is based on the uniform internal temperature distribution of the power device under the calibration of the constant temperature box, but the internal distribution of the power device is non-uniform in actual operation, which causes a deviation between the actually measured temperature-sensitive electrical parameters and the temperature-sensitive electrical parameters under the steady-state thermal conditions, thereby affecting the estimation accuracy of the junction temperature.

[0083] The prior art relies on the steady-state heat dissipation capacity of the power device, and it is difficult to realize accurate calibration under high current, which leads to a narrow current range, and is not conducive to online junction temperature monitoring in a wide power range.

[0084] In summary, compared with the prior art pre-calibration scheme based on steady-state thermal conditions, the traditional calibration thinking of pursuing stable readings is abandoned, the determination of the junction temperature during the calibration process does not need to rely on external thermal steady-state environment creation (the prior art needs a constant temperature box to create multiple stable temperature points), but is completed in the self-thermal transient state (single pulse heating, no external temperature control), which not only reduces the cost and improves the efficiency, but also is applicable to various scenarios.

[0085] Further, the specific steps of step S100 to the target power device in the on-state are as follows:

[0086] Determine the corresponding test duration, which is a static value or a dynamic value;

[0087] Apply the corresponding calibration current to the target power device in the on-state according to the test duration.

[0088] As an implementable manner, the test duration is a static value, that is, the test duration corresponding to the calibration current is pre-configured, for example, the test duration corresponding to the low current is longer, and the test duration corresponding to the high current is shorter, and the person skilled in the art can configure it based on the actual situation, as long as the junction temperature of the target power device during the test process does not exceed the maximum safe working temperature of the device;

[0089] As an example, the target power device is an IGBT module, and the calibration current is 160A;

[0090] IGBT, Insulated Gate Bipolar Transistor;

[0091] Reference Figure 2 , Figure 2 The curves of different colors represent the thermal resistance curves Zth of the IGBT module under different water cooling conditions (coolant flow rates of 0.62 L / min, 1.01 L / min, 1.55 L / min, and 2.04 L / min, respectively). 0.136 K / W@141 ms means that when a single power pulse with a duration of 141 milliseconds is applied to the device, the transient thermal resistance value of the device is 0.136 K / W.

[0092] A 160A pulse with a duration of 400ms was applied to the IGBT module, and the instantaneous collector-emitter voltage V was recorded. ce The curve of heating power P calculated from the calibration current Itest is shown below. Figure 3 As shown;

[0093] Instantaneous collector-emitter voltage V during pulse ce The corresponding curve reference Figure 4 Furthermore, based on the corresponding thermal impedance curve Zth (the appropriate curve is selected according to the water cooling conditions), the heating power P curve, and the ambient temperature, the junction temperature T during the pulse is calculated. j The curve corresponding to time, i.e. Figure 4 The junction temperature curve shown in the figure;

[0094] Reference Figure 4 It can be seen that by selecting the instantaneous collector-emitter voltage V at the same time point, ce and junction temperature T j Calibration can then be completed by data fitting. In this case, the IGBT module at 160A... j -V ce The calibration results are as follows Figure 5 As shown;

[0095] In this case, based on the calibrated T j -V ce The relationship is used to perform online monitoring of the junction temperature of the IGBT module and compare it with infrared measurement data, referring to... Figure 6 The results show that its error is within 5%, indicating extremely high accuracy.

[0096] When the test duration is a static value, the staff needs to configure one by one according to the calibration current in advance, but the static threshold is difficult to adapt to all power devices, in order to avoid the situation that individual power devices exceed the maximum safe working temperature during the test in actual application, the test duration needs to be configured carefully, which will affect the data amount for subsequent data fitting; in order to further improve the accuracy of junction temperature monitoring, another implementable manner is proposed, in which the test duration is a dynamic value;

[0097] The embodiment dynamically calculates the test duration corresponding to the thermal impedance curve of each power device, that is, when the thermal impedance curve of the target power device is obtained, the test duration corresponding to each calibration current is calculated based on the thermal impedance curve and each calibration current.

[0098] The specific steps of determining the test duration corresponding to each calibration current as the target current are as follows:

[0099] S110, determining the reference voltage of the target power device under the corresponding target current;

[0100] The reference voltage can be determined by the reference data provided in the datasheet of the device by the person skilled in the art;

[0101] S120, estimating the maximum junction temperature corresponding to the reference voltage, the target current and the thermal impedance curve to obtain the maximum junction temperature reference value;

[0102] That is, the reference power corresponding to the reference voltage and the target current is calculated, and the maximum junction temperature reference value is estimated based on the reference power and the thermal impedance curve;

[0103] Referring to Figure 2 It can be known that the thermal impedance curve is used to indicate the curve of the instantaneous thermal impedance corresponding to the time within a certain time range;

[0104] In the actual measurement process, the junction temperature needs to be calculated based on the thermal impedance curve, so theoretically the maximum test duration does not exceed the duration corresponding to the thermal impedance curve;

[0105] The person skilled in the art can easily estimate the current maximum junction temperature reference value according to the above calculation formula of the junction temperature on the premise of knowing the reference voltage, the calibration current, the thermal impedance curve and the environmental temperature, so the present specification will not be described in detail.

[0106] S130, judging the over-temperature risk based on the maximum junction temperature reference value and the preset over-temperature threshold;

[0107] The person skilled in the art can self-determine the maximum safe working temperature T maxThe over-temperature threshold is set to 0.8T in this embodiment max .

[0108] S140, when it is determined that there is no over-temperature risk, determining a corresponding test duration based on the time length corresponding to the thermal impedance curve;

[0109] That is, when the calculated maximum junction temperature reference value is less than the over-temperature threshold, it is determined that there is no over-temperature risk, and the following steps are performed:

[0110] S141, determining the maximum thermal impedance Z th (max) based on the thermal impedance curve;

[0111] S142, performing weighted calculation on the maximum thermal impedance based on a preset first weight to obtain a first impedance value, and performing weighted calculation on the maximum thermal impedance based on a preset second weight to obtain a second impedance value;

[0112] In this embodiment, the first weight is greater than the second weight, and the first weight is less than or equal to 0.9;

[0113] In this embodiment, the first weight is 0.9 and the second weight is 0.7, that is, the first impedance value is 0.9Z th (max), and the second impedance value is 0.7Z th (max) ;

[0114] S143, based on the thermal impedance curve, obtaining a first duration corresponding to the first impedance value and a second duration corresponding to the second impedance value;

[0115] In this embodiment, the time point corresponding to 0.9Z th (max) is recorded as the first duration t1, and the time point corresponding to 0.7Z th (max) is recorded as the second duration t2;

[0116] S144, determining a corresponding test duration based on the first duration and the second duration, the test duration being less than the first duration and greater than the second duration;

[0117] That is, the test duration t t is in the range (t1, t2).

[0118] Those skilled in the art can set the selection rule of the test duration according to actual needs, such as taking the obtained average value as the test duration, and can also weight the first duration t1 or the second duration t2 according to the size of the calibration current, which is not limited in detail in this embodiment.

[0119] S150, when it is determined that there is an over-temperature risk, estimating an over-temperature duration for which the junction temperature reaches the over-temperature threshold based on the reference voltage, the target current and the thermal impedance curve, determining a corresponding test duration based on the over-temperature duration;

[0120] That is, when the calculated maximum junction temperature reference value is greater than or equal to the over-temperature threshold T s , it is determined that there is an over-temperature risk;

[0121] The over-temperature threshold is a known value. Based on the above formula for calculating the junction temperature, those skilled in the art can easily calculate the time required for the corresponding junction temperature to reach the over-temperature threshold, i.e. the over-temperature duration, under the premise of knowing the reference voltage, the target current, the thermal impedance curve and the ambient temperature. Therefore, this specification will not be described in detail.

[0122] The specific steps for determining the corresponding test duration based on the over-temperature duration in the embodiment are as follows:

[0123] S151, determining the thermal impedance corresponding to the over-temperature duration based on the thermal impedance curve, and obtaining an over-temperature thermal impedance Z th (t s ), t s represents the over-temperature duration;

[0124] S152, performing weighted calculation on the over-temperature thermal impedance based on a preset third weight, and obtaining a third impedance value, wherein the third weight is set to 0.8 in the embodiment, and the third impedance value is 0.8 Z th (t s ) ;

[0125] S153, obtaining a third duration corresponding to the third impedance value based on the thermal impedance curve, i.e. recording the time point corresponding to 0.8 Z th (t s ) as the third duration t3;

[0126] S154, determining a corresponding test duration based on the third duration, wherein the test duration is less than the third duration;

[0127] Those skilled in the art can set the corresponding weight for the third duration to obtain a test duration less than the third duration according to the size of the calibration current.

[0128] Embodiment 2, a system for constructing a junction temperature monitoring model based on transient thermal behavior;

[0129] The junction temperature monitoring model comprises a plurality of sub-models, and each sub-model is used to indicate the relationship between the instantaneous collector-emitter voltage and the junction temperature of the target power device under a corresponding calibration current. The calibration currents corresponding to the sub-models are different from each other, and the calibration current is a single pulse current.

[0130] Referring to Figure 7 , the construction system comprises:

[0131] a test module 100 configured to apply a corresponding calibration current to a target power device in a conducting state to heat up the target power device;

[0132] a monitoring module 200 configured to monitor an instantaneous collector-emitter voltage of the target power device in real time to obtain corresponding monitoring data;

[0133] a junction temperature calculation module 300 configured to calculate a heating power based on the corresponding calibration current and monitoring data to obtain corresponding power data, and to calculate corresponding junction temperature data based on the corresponding power data and a thermal impedance curve corresponding to the target power device;

[0134] a data fitting module 400 configured to construct a sub-model corresponding to the calibration current based on the corresponding junction temperature data and monitoring data.

[0135] a test control module 500 configured to determine a corresponding test duration, and to control the test module 100 to apply a corresponding calibration current to a target power device in a conducting state according to the test duration.

[0136] Referring to Figure 8 , the test module 100 in the embodiment comprises a current source I test , a control switch, and a voltage output end and a voltage input end. In actual application, a power device (such as an IGBT module) in a conducting state is connected to the test module 100 through the voltage input end and the voltage output end, and the current source, the switch and the power device are connected in series to form a heating loop.

[0137] In the embodiment, the control switch is an IGBT or MOS module, and the test control module 500 is configured to control the on-off of the corresponding control switch based on the test duration, so as to control the current source I test to output a pulse width of the calibration current.

[0138] The test control module 500 comprises:

[0139] a parameter determination unit configured to determine a corresponding test duration;

[0140] a switch control unit configured to control the test module 100 to apply a corresponding calibration current to a target power device in a conducting state according to the test duration.

[0141] As an implementable manner, the parameter determination unit is configured to, after obtaining the thermal impedance curve of the target power device, calculate a test duration corresponding to each calibration current based on the thermal impedance curve and each calibration current;

[0142] The parameter determination unit comprises:

[0143] a mapping subunit configured to determine a reference voltage of the target power device under a corresponding calibration current;

[0144] an estimation subunit configured to estimate a maximum junction temperature corresponding to the reference voltage, the calibration current and the thermal impedance curve, and obtain a maximum junction temperature reference value;

[0145] a judgment subunit configured to perform an over-temperature risk judgment based on the obtained maximum junction temperature reference value and a preset over-temperature threshold;

[0146] a first duration determination subunit configured to, when it is determined that there is no over-temperature risk, determine a test duration corresponding to the thermal impedance curve based on a time length corresponding to the thermal impedance curve;

[0147] a second duration determination subunit configured to, when it is determined that there is an over-temperature risk, estimate an over-temperature duration in which the junction temperature reaches the over-temperature threshold based on the reference voltage, the calibration current and the thermal impedance curve, and determine a test duration corresponding to the over-temperature duration.

[0148] Embodiment 3: An online junction temperature monitoring method based on transient thermal behavior, comprising the following steps:

[0149] S510: Based on a preset monitoring rule, collecting a working current and an instantaneous collector-emitter voltage corresponding to a turned-on power device to be measured;

[0150] The monitoring rule is a trigger rule for junction temperature monitoring, which can be designed by a person skilled in the art according to actual needs, and is not limited in detail in the specification.

[0151] S520: Based on a preset junction temperature monitoring model, determining a corresponding junction temperature according to the working current and the instantaneous collector-emitter voltage, wherein the junction temperature monitoring model is a junction temperature monitoring model obtained according to the construction method of embodiment 1;

[0152] Specifically,

[0153] S521: Taking a sub-model corresponding to the working current in the junction temperature monitoring model as a target model;

[0154] That is, matching the working current with the calibration current, and taking a sub-model corresponding to the matched calibration current as the target model;

[0155] The matching rule can be set by the person skilled in the art according to the configuration of the calibration current and actual needs, and the embodiment is not limited in detail.

[0156] S522, based on the target model, the corresponding junction temperature is calculated according to the instantaneous set voltage.

[0157] The current research direction of the person skilled in the art is the effect of different electrical parameters as temperature-sensitive electrical parameters, and the existing calibration methods for online junction temperature monitoring can be divided into two categories:

[0158] Based on transient electrical parameters;

[0159] Such methods obtain the corresponding relationship between electrical parameters and junction temperature during switching of the device, but have strict requirements for calibration conditions: the device must be operated at the switching frequency during calibration, and the parasitic parameters, gate resistance, etc. must be completely consistent with the actual working conditions, otherwise a large error will be caused. This makes the calibration equipment complex, the calibration period long and the precision difficult to guarantee; and in actual monitoring, the device needs to be controlled to turn on and off, which affects the normal operation of the system where the device is located.

[0160] Transient electrical parameters are different from the transient thermal behavior described in the present application, and the transient electrical parameters refer to the device current overshoot, device switching speed, etc. The existing technology still calibrates the transient electrical parameters and junction temperature based on the steady-state thermal condition;

[0161] For example, the patent application number CN201910829782.2 uses the device current overshoot as the temperature-sensitive electrical parameter, tests the collector turn-on current overshoot value corresponding to different diode junction temperatures under the steady-state thermal condition, and fits to obtain the relationship between the collector turn-on current overshoot and the diode junction temperature. In actual junction temperature monitoring, the diode junction temperature is determined by measuring the collector turn-on current overshoot, and the junction temperature of the IGBT is determined by the diode junction temperature.

[0162] Based on static electrical parameters:

[0163] For example, the collector-emitter voltage V CE , the gate-source voltage V GS , and the junction temperature relationship are established.

[0164] The above various methods are based on the steady-state thermal condition, and the mapping between the electrical parameters and the junction temperature can be established only after the steady state is reached at different temperature points.

[0165] But in the calibration of the on-line junction temperature monitoring, it is necessary to ensure that the established calibration relationship (the mapping relationship between the temperature-sensitive electrical parameter and the junction temperature) is still accurate under the actual working conditions of the inverter, and can monitor the junction temperature in real time under the working conditions; this means that although some electrical parameters can reflect the junction temperature, they may not be suitable for on-line junction temperature measurement; for example, the gate-source voltage V GS Generally needs to be kept constant, so it cannot be directly used for on-line monitoring under actual working conditions; for another example, the device current is generally tens of amperes, and the collector-emitter voltage V CE The mapped junction temperature error is large, and is also not suitable for actual working conditions; the junction temperature monitoring model constructed based on the transient thermal behavior in the present application is suitable for on-line junction temperature monitoring under different working currents, has a wide range of applications, and does not affect the normal operation of the power device to be measured during the monitoring process.

[0166] Embodiment 4, an on-line junction temperature monitoring system based on transient thermal behavior, comprising:

[0167] A collection module configured to collect, based on a preset monitoring rule, a working current and a transient collector-emitter voltage corresponding to a power device to be measured in conduction;

[0168] A calculation module configured to determine a corresponding junction temperature based on a preset junction temperature monitoring model and the working current and the transient collector-emitter voltage, the junction temperature monitoring model being a junction temperature monitoring model obtained by the above construction method;

[0169] The calculation module comprises:

[0170] A matching unit configured to take a sub-model corresponding to the working current in the junction temperature monitoring model as a target model;

[0171] A calculation unit configured to calculate a corresponding junction temperature based on the target model and the transient collector-emitter voltage.

[0172] For the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the related parts are referred to the part of the method embodiment.

[0173] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same and similar parts between the embodiments can be referred to each other.

[0174] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In one

[0175] The present application is described in reference to the flowchart illustrations and / or block diagrams of the methods, terminal devices (systems) and computer program products according to the present application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal devices to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal devices, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0176] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing terminal devices to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0177] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal devices to cause a series of operational steps to be performed on the computer or other programmable terminal devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable terminal devices provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0178] It is noted that:

[0179] The phrase "one embodiment" or "an embodiment" as used herein does not necessarily refer to the same embodiment, though it can. The phrase "one embodiment" or "an embodiment" can refer to a specific feature, structure, or characteristic in one or more embodiments.

[0180] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0181] Furthermore, it should be noted that the shapes and names of the parts and components described in the specific embodiments described in this specification may differ. All equivalent or simple variations made to the structure, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not depart from the structure of this invention or exceed the scope defined in these claims, they should all fall within the protection scope of this invention.

Claims

1. A method for constructing a junction temperature monitoring model based on transient thermal behavior, characterized in that: The junction temperature monitoring model includes several sub-models. The sub-models are used to indicate the relationship between the instantaneous collector-emitter voltage and junction temperature of the target power device under the corresponding calibration current. The calibration currents corresponding to each sub-model are different, and the calibration current is a single pulse current. The method of constructing the target sub-model by taking each sub-model as the target sub-model in turn includes the following steps: applying a corresponding calibration current to the target power device that is kept in the conducting state to raise the temperature of the target power device, and monitoring the instantaneous collector-emitter voltage of the target power device in real time to obtain the corresponding monitoring data; The heating power is calculated based on the calibration current and the monitoring data to obtain the corresponding power data; Based on the power data and the thermal impedance curve corresponding to the target power device, the corresponding junction temperature data is calculated. Based on the junction temperature data and the monitoring data, the target sub-model is constructed; The formula for calculating the corresponding junction temperature based on the power data and the thermal impedance curve is as follows: T j (t)= P(t)*Z th (t)+ T f,m ; in: t represents a point in time; T j (t) represents the junction temperature at point t; P(t) represents the power at point t; Z th (t) represents the transient thermal impedance at point t; * indicates a convolution operation; T f,m Indicates ambient temperature.

2. The method for constructing a junction temperature monitoring model based on transient thermal behavior according to claim 1, characterized in that: Determine the appropriate test duration; Apply a corresponding calibration current to the target power device that remains in the on state according to the test duration.

3. The method for constructing a junction temperature monitoring model based on transient thermal behavior according to claim 2, characterized in that: Pre-configure the test duration that corresponds one-to-one with the calibration current.

4. The method for constructing a junction temperature monitoring model based on transient thermal behavior according to claim 2, characterized in that, After obtaining the thermal impedance curve of the target power device, the test duration corresponding to each calibration current is calculated based on the thermal impedance curve and each calibration current. Each calibration current is taken as the target current. The specific steps for determining the test duration corresponding to the target current are: determining the reference voltage of the target power device under the corresponding target current. Based on the reference voltage, the target current, and the thermal impedance curve, the corresponding maximum junction temperature is estimated to obtain the maximum junction temperature reference value. The risk of overheating is assessed based on the maximum junction temperature reference value and the preset overheating threshold. When it is determined that there is no risk of overheating, the corresponding test duration is determined based on the time length corresponding to the thermal impedance curve. When an over-temperature risk is determined, the over-temperature duration for the junction temperature to reach the over-temperature threshold is estimated based on the reference voltage, the target current, and the thermal impedance curve, and the corresponding test duration is determined based on the over-temperature duration.

5. The method for constructing a junction temperature monitoring model based on transient thermal behavior according to claim 4, characterized in that, When it is determined that there is no risk of overheating: the maximum thermal resistance is determined based on the aforementioned thermal resistance curve; The maximum thermal resistance is weighted and calculated based on a preset first weight to obtain a first impedance value, and the maximum thermal resistance is weighted and calculated based on a preset second weight to obtain a second impedance value, wherein the first weight is greater than the second weight and the first weight is less than or equal to 0.

9. Based on the thermal impedance curve, the first duration corresponding to the first impedance value is obtained, and the second duration corresponding to the second impedance value is obtained. The corresponding test duration is determined based on the first duration and the second duration, wherein the test duration is less than the first duration and greater than the second duration.

6. The method for constructing a junction temperature monitoring model based on transient thermal behavior according to claim 4, characterized in that... The specific steps for determining the corresponding test duration based on the over-temperature duration are as follows: determine the thermal impedance corresponding to the over-temperature duration based on the thermal impedance curve, and obtain the over-temperature thermal impedance. The over-temperature thermal impedance is weighted and calculated based on a preset third weight to obtain a third impedance value; Based on the thermal impedance curve, the third duration corresponding to the third impedance value is obtained; The corresponding test duration is determined based on the third duration, and the test duration is less than the third duration.

7. A system for constructing a junction temperature monitoring model based on transient thermal behavior, characterized in that: The junction temperature monitoring model includes several sub-models. The sub-models are used to indicate the relationship between the instantaneous collector-emitter voltage and junction temperature of the target power device under the corresponding calibration current. The calibration currents corresponding to each sub-model are different, and the calibration current is a single pulse current. The construction system includes: The test module is used to apply a corresponding calibration current to the target power device that is kept in the on state, so as to raise the temperature of the target power device; The monitoring module is used to monitor the instantaneous collector-emitter voltage of the target power device in real time and obtain the corresponding monitoring data; The junction temperature calculation module is used to calculate the heating power based on the corresponding calibration current and monitoring data to obtain the corresponding power data; it is also used to calculate the corresponding junction temperature data based on the corresponding power data and the thermal impedance curve corresponding to the target power device. The data fitting module is used to construct a sub-model corresponding to the calibration current based on the corresponding junction temperature data and monitoring data. The junction temperature calculation module calculates the corresponding junction temperature based on the power data and the thermal impedance curve using the following formula: T j (t)= P(t)*Z th (t)+ T f,m ; in: t represents a point in time; T j (t) represents the junction temperature at point t; P(t) represents the power at point t; Z th (t) represents the transient thermal impedance at point t; * indicates a convolution operation; T f,m Indicates ambient temperature.

8. The system for constructing a junction temperature monitoring model based on transient thermal behavior according to claim 7, characterized in that, It also includes a test control module, which includes a parameter determination unit for determining the corresponding test duration; A switch control unit is used to control the test module to apply a corresponding calibration current to the target power device that remains in the on state, according to the test duration.

9. A method for online junction temperature monitoring based on transient thermal behavior, characterized in that, The process includes the following steps: Based on preset monitoring rules, the operating current and instantaneous collector-emitter voltage of the power device under test that is conducting are collected; Based on the preset junction temperature monitoring model, the corresponding junction temperature is determined according to the operating current and the instantaneous collector-emitter voltage. The junction temperature monitoring model is a junction temperature monitoring model constructed according to any one of claims 1 to 6, specifically: the sub-model corresponding to the operating current in the junction temperature monitoring model is taken as the target model. Based on the target model, the corresponding junction temperature is calculated according to the instantaneous collector-emitter voltage.

10. An online junction temperature monitoring system based on transient thermal behavior, characterized in that, include: The acquisition module is used to acquire the operating current and instantaneous collector-emitter voltage of the conducting power device under test based on preset monitoring rules. The calculation module is used to determine the corresponding junction temperature based on the preset junction temperature monitoring model, according to the operating current and the instantaneous collector-emitter voltage, wherein the junction temperature monitoring model is a junction temperature monitoring model constructed according to the construction method of any one of claims 1 to 6; The computing module includes: The matching unit is used to select the sub-model in the junction temperature monitoring model that corresponds to the operating current as the target model; The calculation unit is used to calculate the corresponding junction temperature based on the target model and the instantaneous collector-emitter voltage.

Images