CN116298764A

CN116298764A - Apparatus, method and peak detection circuit for characterizing junction temperature of IGBT device

Info

Publication number: CN116298764A
Application number: CN202310409630.3A
Authority: CN
Inventors: 王博; 房新斌; 孙鹏菊; 赵品志; 孟金磊; 沈瑞华
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2023-04-17
Filing date: 2023-04-17
Publication date: 2023-06-23

Abstract

The invention relates to an apparatus, a method and a peak detection circuit for characterizing junction temperature of an IGBT device. Specifically, an embodiment of the present disclosure provides an apparatus for characterizing a junction temperature of an IGBT device, wherein the IGBT device includes a first IGBT and a second IGBT connected in series, the apparatus comprising: a voltage measurement circuit configured to measure different peaks of induced voltage on a second stray inductance between a main emitter node and an auxiliary emitter node of the second IGBT during switching operation of the second IGBT at different half-cycles of the phase current; and a junction temperature characterizer configured to generate a first characterization signal and a second characterization signal, respectively, based on the different peaks, the first characterization signal characterizing a first junction temperature of the first IGBT and the second characterization signal characterizing a second junction temperature of the second IGBT.

Description

Apparatus, method and peak detection circuit for characterizing junction temperature of IGBT device

Technical Field

Embodiments of the present disclosure relate to the field of temperature measurement of IGBTs, and more particularly, to an apparatus, method, and peak detection circuit for characterizing junction temperatures of IGBT devices.

Background

Insulated Gate Bipolar Transistors (IGBTs) are a type of power device that is widely used in the fields of power electronics systems, motion control, motor driving, power supply circuits, and the like. When the IGBT is operated, the junction temperature of the IGBT is a severely limited upper limit, and the IGBT junction temperature fluctuation is one of the most important causes of the IGBT aging failure. Therefore, accurate estimation of junction temperature is very important for ensuring safe operation of the IGBT device and accurate estimation of the remaining lifetime of the IGBT device.

The IGBT junction temperature depends on the operating conditions of the IGBT and is highly dependent on the current flowing when the IGBT is on and the voltage that the IGBT is subjected to when the IGBT is off. In the prior art, the loss of the IGBT is estimated by using information such as voltage, current and the like during the operation of the IGBT, and then the junction temperature of the IGBT is estimated by using a thermal network model of the IGBT device. However, certain errors exist in the method due to errors of the loss model and changes of parameters of the thermal network model along with ageing of the IGBT device.

Other techniques for measuring the junction temperature of an IGBT may include mounting a thermocouple on the IGBT chip or measuring a thermistor inside the IGBT device, regarding the problem of the thermistor as the IGBT junction temperature. These techniques require specially designed IGBT devices or slow dynamic response and large errors.

Therefore, the prior art is not suitable for on-line measurement of the junction temperature of the IGBT, or can not respond to the situation that the junction temperature of the IGBT is excessively high in a moment in time.

It is therefore desirable to provide a new method, device, circuit for characterizing the junction temperature of an IGBT that solves the above-mentioned technical problems of the prior art.

Disclosure of Invention

In order to solve the technical problems in the prior art, embodiments of the present disclosure provide a method, an apparatus, and a peak detection circuit for characterizing a junction temperature of an IGBT.

In a first aspect, there is provided an apparatus for characterizing a junction temperature of an insulated gate bipolar transistor, IGBT, device, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the apparatus comprising: a peak detection circuit configured to measure different peaks of the induced voltage on the second stray inductance between the main emitter node and the auxiliary emitter node of the second IGBT during switching operation of the second IGBT at different half-cycles of the phase current; and a junction temperature characterizer configured to generate a first characterization signal and a second characterization signal, respectively, based on the different peaks, the first characterization signal characterizing a first junction temperature of the first IGBT and the second characterization signal characterizing a second junction temperature of the second IGBT.

In some embodiments, the junction temperature characterizer is configured to: the method includes the steps of characterizing a junction temperature of a first IGBT based on a peak value of an induced voltage during a first half period of a phase current, and characterizing a junction temperature of a second IGBT based on a peak value of the induced voltage during a second half period of the phase current, wherein the first half period is a positive half period or a negative half period, and the second half period is a negative half period or a positive half period.

By the device of the embodiment of the disclosure, the junction temperature of two IGBTs can be obtained by measuring the induced voltage on the stray inductance between the main emitter node and the auxiliary emitter node of one of the two IGBTs on different time sequences, namely on different phase current half cycles (positive half cycle and negative half cycle), so that the hardware cost can be reduced, and the junction temperature of the two IGBTs can be accurately measured in a simple mode.

In a second aspect, a method for characterizing a junction temperature of an insulated gate bipolar transistor, IGBT, device is provided, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the method comprising the steps of: receiving a first characterization signal characterizing a first half-cycle and a second characterization signal characterizing a second half-cycle; characterizing a first junction temperature of the first IGBT based on the first characterization signal; and characterizing a second junction temperature of the second IGBT based on the second characterization signal.

In some embodiments, the first half cycle is a positive half cycle or a negative half cycle, and the second half cycle is a negative half cycle or a positive half cycle.

By the method, the junction temperature of the two IGBTs can be obtained by measuring the induced voltage on the stray inductance between the main emitter node and the auxiliary emitter node of one of the two IGBTs on different time sequences, namely different phase current half periods (positive half period and negative half period), so that the hardware cost can be reduced, and the junction temperature of the two IGBTs can be accurately measured in a simple mode.

In a third aspect, there is provided a peak detection circuit for characterizing a junction temperature of an insulated gate bipolar transistor, IGBT, device, comprising: a peak detector configured to obtain a peak voltage; a storage capacitor connected with the peak detector, wherein the output voltage of the peak detector charges the storage capacitor to obtain a storage capacitor voltage until the maximum storage capacitor voltage is obtained; and a resistor connected in parallel with the storage capacitor, the resistor and the storage capacitor forming a loop, such that the resistor discharges the storage capacitor for obtaining the next maximum storage capacitor voltage, wherein the maximum storage capacitor voltage is used for representing the junction temperature of the insulated gate bipolar transistor IGBT device.

In some embodiments, the peak detector comprises a first operational amplifier, a second operational amplifier, and a diode, the positive input terminal of the first operational amplifier receiving the input voltage, the output terminal of the first operational amplifier being connected to the positive electrode of the diode, the positive electrode of the diode being connected to the positive input terminal of the second operational amplifier and the positive electrode of the capacitor, the output terminal of the second operational amplifier being connected to the negative input terminal of the first operational amplifier and the negative input terminal of the second operational amplifier.

In some embodiments, the first operational amplifier has a voltage follower function and the second operational amplifier has a buffer isolation function.

In some embodiments, when the potential of the positive input terminal of the first operational amplifier is greater than the potential of the negative input terminal of the first operational amplifier, the output of the first operational amplifier outputs a positive voltage such that the diode is turned on and the output of the first operational amplifier charges the storage capacitor.

In some embodiments, when the potential of the positive input terminal of the first operational amplifier is less than the potential of the negative input terminal of the first operational amplifier, the output of the first operational amplifier outputs a negative voltage such that the diode turns off and the output of the first operational amplifier does not charge the storage capacitor.

In some embodiments, the peak detection circuit further comprises a voltage divider configured to convert the voltage from the IGBT device to a desired voltage level.

In some embodiments, the resistance value of the resistor is configured such that the maximum peak voltage that can be achieved by the storage capacitor is less than the minimum peak voltage that can be achieved after discharge.

By the peak detection circuit, the complicated circuit in the prior art can be replaced by using a simple resistor, so that the hardware cost is reduced, and the measurement accuracy can be ensured.

In a fourth aspect, there is provided a method for characterizing a junction temperature of an insulated gate bipolar transistor, IGBT, device using a peak detection circuit, the method comprising the steps of: obtaining the relation between the voltage of the storage capacitor after discharge and the peak voltage; obtaining the relation between the peak voltage and the junction temperature; obtaining the relation between the discharge time of the storage capacitor and the junction temperature; obtaining the relationship between the voltage of the storage capacitor after discharge and the junction temperature through the relationship between the voltage of the storage capacitor after discharge and the peak voltage, the relationship between the peak voltage and the junction temperature and the relationship between the discharge time and the junction temperature; and characterizing the junction temperature based on the voltage after the storage capacitor is discharged.

In some embodiments, the relationship between the voltage after the storage capacitor is discharged and the peak voltage is a function of the peak voltage and the discharge time, the relationship between the peak voltage and the junction temperature is a function of the junction temperature, the relationship between the discharge time and the junction temperature is a function of the junction temperature, and the relationship between the voltage after the storage capacitor is discharged and the junction temperature is a function of the junction temperature.

In some embodiments, the voltage after discharge of the storage capacitor is fitted to a relationship function of the junction temperature.

By the method of the embodiment of the disclosure, the junction temperature can be accurately measured, and the problem of inaccurate measurement caused by curve deviation due to discharge of the storage capacitor in the peak detection circuit can be solved.

In a fifth aspect, there is provided an apparatus for characterizing a junction temperature of an insulated gate bipolar transistor, IGBT, device, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the apparatus comprising: a peak measurement circuit configured to measure different peak voltages of the induced voltage on the second stray inductance between the main emitter node and the auxiliary emitter node of the second IGBT during switching operation of the second IGBT at different half cycles of the phase current; and a junction temperature characterizer configured to generate a first characterization signal and a second characterization signal, respectively, based on the different maximum storage capacitor voltages, the first characterization signal characterizing a first junction temperature of the first IGBT and the second characterization signal characterizing a second junction temperature of the second IGBT, wherein the peak measurement circuit comprises: a peak detector configured to obtain a peak voltage; a storage capacitor connected with the peak detector, wherein the output voltage of the peak detector charges the storage capacitor to obtain a storage capacitor voltage until the maximum storage capacitor voltage is obtained; a resistor in parallel with the storage capacitor, the resistor and the storage capacitor forming a loop such that the resistor discharges the storage capacitor for obtaining a next maximum storage capacitor voltage.

By the device of the embodiment of the disclosure, the junction temperature of two IGBTs can be obtained by measuring the induced voltage on the stray inductance between the main emitter node and the auxiliary emitter node of one of the two IGBTs on different time sequences, namely on different phase current half cycles (positive half cycle and negative half cycle), so that the hardware cost can be reduced, and the junction temperature of the two IGBTs can be accurately measured in a simple mode. And the complicated circuit in the prior art can be replaced by using a simple resistor, so that the hardware cost is reduced, and the measurement accuracy can be ensured.

In a sixth aspect, there is provided a method for characterizing a junction temperature of an insulated gate bipolar transistor, IGBT, device, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the method comprising the steps of: receiving a first characterization signal characterizing a first half-cycle and a second characterization signal characterizing a second half-cycle; characterizing a first junction temperature of the first IGBT based on the first characterization signal; and characterizing a second junction temperature of the second IGBT based on the second characterization signal, wherein the method further comprises characterizing the junction temperature of the insulated gate bipolar transistor IGBT device using a peak detection circuit, comprising the steps of: obtaining the relation between the voltage of the storage capacitor after discharge and the peak voltage; obtaining the relation between the peak voltage and the junction temperature; obtaining the relation between the discharge time of the storage capacitor and the junction temperature; obtaining the relationship between the voltage of the storage capacitor after discharge and the junction temperature through the relationship between the voltage of the storage capacitor after discharge and the peak voltage, the relationship between the peak voltage and the junction temperature and the relationship between the discharge time and the junction temperature; and characterizing the junction temperature based on the voltage after the storage capacitor is discharged.

By the method, the junction temperature of the two IGBTs can be obtained by measuring the induced voltage on the stray inductance between the main emitter node and the auxiliary emitter node of one of the two IGBTs on different time sequences, namely different phase current half periods (positive half period and negative half period), so that the hardware cost can be reduced, and the junction temperature of the two IGBTs can be accurately measured in a simple mode. And the junction temperature can be accurately measured and the problem of inaccurate measurement caused by curve deviation due to discharge of the storage capacitor in the peak detection circuit can be supplemented.

It should be understood that this summary is not intended to identify key or essential features of the disclosed embodiments, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the description that follows.

Drawings

The foregoing and other objects, features and advantages of the disclosure will be apparent from the following more particular descriptions of exemplary embodiments of the disclosure as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the disclosure.

Fig. 1 shows a schematic diagram of an IGBT device according to an embodiment of the disclosure;

fig. 2 shows a schematic diagram of a current path when an IGBT according to an embodiment of the disclosure turns on in a first half-cycle;

fig. 3 shows a schematic diagram of a current path when an IGBT according to an embodiment of the disclosure turns off during a first half-cycle;

fig. 4 shows a schematic diagram of a current path of an IGBT according to an embodiment of the disclosure when the IGBT is on during a second half-cycle;

fig. 5 shows a current path schematic of an IGBT according to an embodiment of the disclosure when the IGBT turns off during a second half-cycle;

FIG. 6 illustrates a schematic diagram of induced voltages at different timings according to an embodiment of the present disclosure;

fig. 7 shows a circuit diagram for measuring the junction temperature of an IGBT according to an embodiment of the disclosure;

FIG. 8 illustrates a schematic diagram of induced voltages at different temperatures according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram illustrating a storage capacitor discharging process and process simplification according to an embodiment of the present disclosure;

FIG. 10 is a schematic diagram illustrating induced voltage peak versus junction temperature according to an embodiment of the present disclosure;

FIG. 11 is a schematic diagram showing induced voltage delay time versus junction temperature according to an embodiment of the present disclosure; and

fig. 12 shows a schematic diagram of storing a residual voltage versus IGBT junction temperature according to an embodiment of the disclosure.

Throughout the drawings, the same or similar reference numerals are used to designate the same or similar elements.

Detailed Description

The present disclosure will now be discussed in connection with several example embodiments. It should be understood that these embodiments are discussed only in order to enable those skilled in the art to better understand and practice the present disclosure, and are not meant to imply any limitation on the scope of the subject matter.

As used herein, the term "comprising" and variations thereof is to be understood as an open term meaning "including but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first," "second," and the like, may refer to different or the same object. Other explicit and implicit definitions may be included below. Unless the context clearly indicates otherwise, the definition of terms is consistent throughout the specification.

Fig. 1 shows a schematic diagram of an IGBT device 1 for use in a power application. The IGBT device 1 includes a first IGBT 10 and a second IGBT 20 connected in series. The first IGBT 10 is formed as an IGBT semiconductor chip and includes an IGBT semiconductor component. The second IGBT 20 is formed as an IGBT semiconductor chip and includes an IGBT semiconductor component. Two emitters are used in an IGBT semiconductor chip, one being a main emitter for flowing load current and the other being an auxiliary emitter for a gate driver.

As shown in fig. 1, the first IGBT 10 is located at the upper portion of the IGBT device 1, and thus may also be referred to as an upper arm IGBT. The second IGBT 20 is located in the lower part of the IGBT device 1 and may therefore also be referred to as a lower leg IGBT.

In some embodiments, the first IGBT 10 includes the following terminals: first collector C ₁ First insulated gate G ₁ First auxiliary emitter e ₁ First main emitter E ₁ C ₂ 。

In some embodiments, the second IGBT 20 includes the following terminals: second collector E ₁ C ₂ Second insulated gate G ₂ Second auxiliary emitter e ₂ Second main emitter E ₂ 。

As shown in fig. 1, a first main emitter E as a first IGBT 10 ₁ C ₂ And a first auxiliary emitter e as a first IGBT 10 ₁ Is short-circuited between the terminals of the pair. Although the first main emitter E ₁ C ₂ With a first auxiliary emitter e ₁ Is short-circuited between them, and there is a first stray inductance L between them _σ1 . When the first isFirst collector C of IGBT 10 ₁ Will be at the first stray inductance L when the current of (a) varies _σ1 Generates a first induced voltage V _e1E1 . First induced voltage V _e1E1 Peak value of V _{e1E1_peak} And the peak value V _{e1E1_peak} And a first collector C ₁ Is related to the maximum slope of the current change. At the same time, a first collector C ₁ The maximum slope of the current variation of (a) is subjected to the junction temperature T of the first IGBT 10 _j Is a function of (a) and (b). Therefore, the junction temperature T of the first IGBT 10 _j Can be obtained from a first induced voltage V _e1E1 Peak value V of (2) _{e1E1_peak} To characterize.

Taking the turn-off of the first IGBT 10 as an example, V _{e1E1_peak} Can be represented by formula (1):

wherein V is _{e1E1_peak} Is a first induced voltage V _e1E1 Is a peak of (c). L (L) _σ1 For the first main emitter E ₁ C ₂ With a first auxiliary emitter e ₁ A first stray inductance therebetween.

A first off current i for the first IGBT 10 _c1off For the maximum value of the derivative of time t, which is the first collector C of the first IGBT 10 ₁ Second main emitter E of second IGBT 20 ₂ Voltage V between _dc Load current I _load Junction temperature T of the first IGBT 10 _j Is a function f (V) _dc ，I _load ，T _j ). Due to L _σ1 、V _dc 、I _load Is of a known quantity, therefore, in the above formula, V _{e1E1_peak} And T is _j Has a unique correspondence such that V of the first IGBT 10 _{e1E1_peak} Can be used to characterize the junction temperature T of the first IGBT _j . Note that the above is an example in which the switching-off of the first IGBT 10 is used to measure the junction temperature, and the switching-on of the first IGBT 10 may also be used to measure the junction temperature T of the first IGBT 10 _j The principle is the same.

Similarly, a second main emitter E as a second IGBT 20 ₂ And a second auxiliary emitter e as a second IGBT 20 ₂ Is short-circuited between the terminals of the pair. Although a second main emitter E ₂ And a second auxiliary emitter e ₂ Is short-circuited between them, and there is a second stray inductance L between them _σ2 . When the second collector E of the second IGBT 20 ₁ C ₂ Will be in the second stray inductance L when the current of (a) is changed _σ2 Generating a second induced voltage V _e2E2 . Second induced voltage V _e2E2 Peak value of V _{e2E2_peak} And the peak value V _{e2E2_peak} And a second collector E ₁ C ₂ Is related to the maximum slope of the current change. At the same time, the maximum slope of the second collector current variation is subject to the junction temperature T of the second IGBT 20 _j Is a function of (a) and (b). Therefore, the junction temperature T of the second IGBT 20 _j Can be induced by a second induced voltage V _e2E2 Peak value V of (2) _{e2E2_peak} To characterize.

Taking the turn-off of the second IGBT 20 as an example, V _{e2E2_peak} Can be represented by formula (2):

wherein V is _{e2E2_peak} Is the second induced voltage V _e2E2 Is a peak of (c). L (L) _σ2 For the second main emitter E ₂ And a second auxiliary emitter e ₂ A second stray inductance therebetween.

A second off current i for the second IGBT 20 _c2off For the maximum value of the derivative of time t, which is the first collector C of the first IGBT 10 ₁ Second main emitter E of second IGBT 20 ₂ Voltage V between _dc Load current I _load Junction temperature T of the second IGBT 20 _j Is a function f (V) _dc ，I _load ，T _j ). Due to L _σ1 、V _dc 、I _load Is of a known quantity and therefore of the formulaIn V _{e2E2_peak} And T is _j Has a unique correspondence such that V of the second IGBT 20 _{e2E2_max} Can be used to characterize the junction temperature T of the second IGBT 20 _j . Note that the above is an example in which the second IGBT 20 is turned off to measure the junction temperature, and the turn-on of the second IGBT 20 may also be used to measure the junction temperature T of the second IGBT 20 _j The principle is the same.

V _{e1E1_peak} And V _{e2E2_peak} Is a low voltage signal and is therefore easier to measure than other temperature sensitive electrical parameters such as the voltage between the collector and the emitter, the off-delay time, etc. V (V) _{e1E1_peak} And V _{e2E2_peak} Relative to junction temperature T _j Has good linearity. Therefore, this method is preferable.

V for the second IGBT 20 _{e2E2_peak} Since the ground of the measuring circuit is connected to the ground of the dc bus, it can be measured relatively easily. However, V for the first IGBT 10 _{e1E1_peak} If the measuring circuit is directly connected to the first auxiliary emitter e ₁ And a first main emitter E ₁ C ₂ Between due to E ₁ C ₂ The potential of (2) varies at time, if accurate measurement of V is required _{e1E1_peak} Isolation circuitry is required but this adds to the hardware cost.

Thus, embodiments of the present disclosure propose a method that only measures the second auxiliary emitter e at different times ₂ And a second main emitter E ₂ The voltage therebetween can be used to measure the junction temperature of the first IGBT 10 and the second IGBT 20 of the IGBT device 1, the principle of which will be discussed in detail below.

First, taking a phase current negative half period in a power frequency period as an example, a load current i _load Flows toward the IGBT device as indicated by the arrows in fig. 2. Note that this load current direction is merely exemplary, which may also flow outward from the IGBT device. Load current i _load Representing the variation value, the maximum value (fixed value) of which is represented by I _load And (3) representing.

As shown in fig. 2, the load current flows through the anti-parallel diode of the second IGBT 20 and the first IGBT 10. When the second IGBT 20 is at the gate v _ge2 When the current I of the anti-parallel diode of the first IGBT 10 is turned on under the excitation of the received signal _d1 The current i of the second IGBT 20 drops _c2 Rising, at stray inductance L _σ2 Generating induced voltage V _e2E2 Due to the reverse recovery action of the antiparallel diode of the first IGBT 10 at this time, it produces waveforms respectively above and below the horizontal axis as shown in fig. 2.

As shown in fig. 3, the load current flows through the anti-parallel diodes of the second IGBT 20 and the first IGBT 10. When the second IGBT 20 is at the gate v _ge2 When the current i of the anti-parallel diode of the first IGBT 10 is turned off under the excitation of the received signal _d1 Rising the current i of the second IGBT 20 _c2 Falling, at stray inductance L _σ2 Generating induced voltage V _e2E2 Since the antiparallel diode of the first IGBT 10 has no reverse recovery effect at this time, it produces a waveform just below the horizontal axis as shown in fig. 3.

As can be seen from the embodiments of fig. 2 and 3, during the negative half-cycle of the phase current in one power frequency cycle, the second stray inductance L flows _σ2 Is determined by the second IGBT 20. That is, in the second stray inductance L _σ2 The induced voltage generated thereon is associated with the second IGBT 20. Thus, at stray inductance L _σ2 Induced voltage V generated on _e2E2 Is associated with the second IGBT 20. Therefore V _e2E2 May be used to characterize the junction temperature of the second IGBT 20.

Next, taking a positive phase current half period in a power frequency period as an example, the load current i _load Flows outward from the IGBT device as indicated by the arrows in fig. 4. Note that this load current direction is only exemplary, which may also flow towards the IGBT device. Load current i _load Representing the variation value, the maximum value (fixed value) of which is represented by I _load And (3) representing.

As shown in fig. 4, the load current flows through the anti-parallel diodes of the first IGBT 10 and the second IGBT 20. When the first IGBT 10 is at the gate v _ge1 When the first IGBT 10 is turned on under the excitation of the received signal, the current i _c1 Rising, second ICurrent i of anti-parallel diode of GBT 20 _d2 Falling, at stray inductance L _σ2 Generating induced voltage V _e2E2 Due to the reverse recovery action of the antiparallel diode of the second IGBT 20 at this time, it produces waveforms respectively above and below the horizontal axis as shown in fig. 4.

As shown in fig. 5, the load current flows through the anti-parallel diodes of the first IGBT 10 and the second IGBT 20. When the first IGBT 10 is at the gate v _ge1 When the current i of the first IGBT 10 is turned off under the excitation of the received signal _c1 The current i of the anti-parallel diode of the second IGBT 20 falls _d2 Rising, at stray inductance L _σ2 Generating induced voltage V _e2E2 Since the antiparallel diode of the second IGBT 20 has no reverse recovery effect at this time, it produces a waveform just below the horizontal axis as shown in fig. 5.

As can be seen from the embodiments of fig. 4 and 5, during the positive phase current half-cycle in one power frequency cycle, the second stray inductance L flows _σ2 Is determined by the first IGBT 10. That is, in the second stray inductance L _σ2 The induced voltage generated above is associated with the first IGBT 10. Thus, at stray inductance L _σ2 Induced voltage V generated on _e2E2 Is associated with the first IGBT 10. Therefore V _e2E2 May be used to characterize the junction temperature of the first IGBT 10.

Specifically, during the negative half-cycle of the phase current in one power frequency period, the load current flows through the second IGBT 20. When the second IGBT 20 starts to turn off, the current i of the second IGBT 20 _c2 Will be from I _load And down to 0.V (V) _{e2E2_peak} Reflecting the maximum current slope of the second IGBT 20. Thus, in the negative half-cycle of the phase current, V _{e2E2_peak} May be used to characterize the junction temperature of the second IGBT 20. In this case, i _c2 Downward flow and decrease, V _e2E2 The polarity of (2) is positive and negative.

In the positive phase current half period of one power frequency period, the load current flows through the first IGBT 10. When the first IGBT 10 starts to turn off, the load current will commutate from the first IGBT 10 to the anti-parallel diode of the second IGBT 20, the current of the first IGBT 10i _c1 Will be from I _load And down to 0. The anti-parallel diode of the second IGBT 20 will increase from 0 to I at the same time _load 。i _d2 The slope of (a) is determined by the turn-off speed of the first IGBT 10, i.e _c1 Is a slope of (2). i.e _c1 Slope sum i of (2) _d2 Is opposite in sign to the slope of V _e2E2 The polarity of (2) is positive and negative. That is, during the positive half-cycle of the phase current, V _{e2E2_peak} Reflecting the maximum current slope of the first IGBT 10. Thus V _{e2E2_peak} May be used to characterize the junction temperature of the first IGBT 10.

Note that the excitation signal, the current direction, the current magnitude, the current rise and fall, the waveform, and the like at the time of turning on and off described above are all exemplary, and the embodiments of the present disclosure are not limited thereto.

FIG. 6 is V in a power frequency cycle _e2E2 For example, in phase A current i _a In the positive half period of (c), at t ₁ 、t ₃ 、t ₅ At odd time points, the gate v of the first IGBT 10 _ge1 A shutdown signal is received. As described above, during the positive half-cycle of the phase current, V _{e2E2_peak} May be used to characterize the junction temperature of the first IGBT 10. For example, in phase A current i _a In the negative half cycle of (c), at t ₈ 、t ₁₀ 、t ₁₂ At even time points, the gate v of the second IGBT 20 _ge1 A shutdown signal is received. As described above, during the negative half-cycle of phase current, V _{e2E2_peak} May be used to characterize the junction temperature of the second IGBT 20.

The above-described positive and negative half periods and corresponding points in time are merely exemplary, and embodiments of the present disclosure are not limited thereto.

Fig. 7 schematically illustrates a peak detection circuit for characterizing the junction temperature of an IGBT device. The IGBT device in fig. 7 is only illustrative, and other connection forms of IGBT devices, such as an IGBT device composed of two parallel IGBT chips, are also possible. In some embodiments, e ₂ And E is ₂ Voltage V between _e2E2 Is input as an input voltage to the peak detector. In some embodiments, to prevent the voltage from being too high above the rated voltage of the chip, the voltage V _e2E2 Can first pass through a voltage dividerThereby being converted to the desired voltage level. Voltage V _e2E2 After passing through the voltage divider, the voltage is input as an input voltage to a peak detector, which serves to detect a peak value and obtain a peak voltage.

The peak detector is connected to the positive pole of the storage capacitor C, the negative pole of which is grounded. The output voltage of the peak detector may charge the storage capacitor until a peak voltage is obtained. That is, the output voltage of the peak detector charges the storage capacitor to a certain voltage, and when the subsequent output voltage is greater than the previous output voltage, the peak detector outputs the voltage and charges the storage capacitor. When the subsequent output voltage is less than the previous output voltage, the peak detector will not output a voltage and will not charge the storage capacitor. In this way, the storage capacitor is charged to the peak voltage.

The storage capacitor C of the embodiments of the present disclosure is connected in parallel with the resistor R, which forms a loop with the storage capacitor, so that the resistor can serve as a reset unit to discharge the storage capacitor. Thus, after a peak voltage is obtained, the storage capacitor is reset to an initial state by means of the resistive discharge. The peak voltage is output to an analog-to-digital converter ADC in a Micro Control Unit (MCU) to convert the analog signal to a digital signal.

The peak detection circuit of the embodiment of the present disclosure can realize the discharge of the storage capacitor C by the parallel resistor R as a reset unit. The value of the resistor R needs to ensure that the maximum peak voltage V appears in the sampling period _{peak_max} In the case of (2) releasing the potential of the storage capacitor to the minimum peak voltage V before the start of the next sampling period _{peak_min} The following is given.

Therefore, the resistor R and the storage capacitor 210 should satisfy the following relationship:

wherein V is _{peak_max} V is the maximum peak voltage that may occur _{peak_min} Is the smallest peak voltage that may occur.

Is a capacitance discharge formula, wherein T _SW R is the resistance value of the resistor R, C is the capacitance value of the storage capacitor, and e is a natural constant.

The meaning of equation (3) is that the resistor R and the storage capacitor 210 should satisfy the relationship that the resistor R discharges the storage capacitor 210 such that the maximum peak voltage that may occur is at least lower than the minimum peak voltage that may occur after discharge.

Voltage peak V for different junction temperatures _{eE_peak} Time of occurrence t _x Turn-off signal t from IGBT ₀ With different delay times t _x -t ₀ . For example, as shown in FIG. 8, for a junction temperature of 25 ℃, the voltage peak V _{eE_peak} Possibly at t ₁ Appears at the moment; for a junction temperature of 50 ℃, voltage peak V _{eE_peak} Possibly at t ₂ Appears at the moment; for a junction temperature of 75 ℃, voltage peak V _{eE_peak} Possibly at t ₃ Appears at the moment; for a junction temperature of 100 ℃, voltage peak V _{eE_peak} Possibly at t ₄ Occurs at a moment.

Firstly, in order to meet the accuracy and comprehensiveness of measurement, the time t of sampling the storage capacitor voltage _s Should be greater than V _{eE_peak} The maximum delay value possible, t, for the embodiment of fig. 8 _s Should be greater than t ₄ . For different junction temperatures, at t _s And collecting capacitor voltage at the moment to characterize the junction temperature. However, at the time of measurement, the capacitance may have undergone a different discharge time (Δt in the figure ₁ ，Δt ₂ ，Δt ₃ ，Δt ₄ ). At t ₁ Time sum t ₂ Time of day, e.g. corresponding to t ₂ Peak voltage V at time _{eE_peak} For peak detection circuits where there is no resistor R discharging the storage capacitor 210, it is possible to detect a peak value corresponding to t by measuring ₂ Peak voltage V at time _{eE_peak} The corresponding junction temperature (e.g., 75 ℃ C.) is obtained. However, in the peak detection circuit having the resistor R for discharging the storage capacitor 210, the voltage peak V _{eE_peak} It is possible to be t ₁ Peak voltage V at time _{eE_peak} Voltage peak after discharge. The junction temperature is unknown, the discharge time is also unknown, and V cannot be obtained by using a discharge compensation method _{eE_peak} Is a precise value of (a).

Let the discharge time of the storage capacitor be Deltat for any junction temperature, and the voltage after the discharge of the storage capacitor be V for any discharge time Deltat _out . At t _s At the moment, the voltage after the storage capacitor is discharged is as follows:

wherein V is _{eE_peak} Is the voltage peak.

The capacitor discharge formula is adopted, wherein R is the resistance value of a resistor R, C is the capacitance value of a storage capacitor, and e is a natural constant.

The discharge curve of the storage capacitor is shown in fig. 9. Since the discharge time Deltat of the capacitor is only from 0 to t _s Is much smaller than the RC time constant, i.e., t _s Far less than t _RC . Therefore, this small segment can be processed as a linear process, i.e., one can apply

Simplified as-a "Δt+b. Therefore, the voltage after the storage capacitor is discharged can be reduced to:

V _out ＝V _{eE_peak} ·(-a·Δt+b) (5)

by experimentally collecting data and fitting the data points, V can be obtained _{eE_peak} And Deltat and junction temperature T _j Is a relationship of (3). V (V) _{eE_peak} The relationship with junction temperature and the relationship between Δt and junction temperature may be linear or other relationships, and are exemplified by the linear relationship below, wherein V _{eE_peak} And junction temperature T _j As shown in FIG. 10, deltat is plotted against junction temperature T _j The linear relationship of (2) is shown in fig. 11:

V _{eE_peak} ＝-c·T _j +d (6)

Δt＝e·T _j +f (7)

substituting the formula (6) and the formula (7) into the formula (5) to obtain:

equation (8) shows V _out Is T _j Is a quadratic equation of (c). Accordingly, V _out Can be used for replacing V _{eE_peak} To calculate the junction temperature T _j . The coefficients a, b, c, d, e, f in equation (8) can be obtained by experimentation and fitting.

Furthermore, a possible junction temperature T _j Is far from the vertex of the curve of the quadratic equation, as shown in fig. 12. V (V) _out And T _j The relationship between can be further simplified to a linear relationship:

V _out ＝α·T _j +β (9)

where α and β are coefficients that can be obtained by experimentation and fitting.

According to the embodiment of the disclosure, the junction temperature of two IGBTs can be obtained by measuring the induced voltage between the main emitter and the auxiliary emitter of one of the two IGBTs on different time sequences, namely on different phase current half cycles (a positive half cycle and a negative half cycle), so that the hardware cost can be reduced, and the junction temperature of the two IGBTs can be accurately measured in a simple mode.

According to the embodiment of the disclosure, the reduction of hardware cost is realized by using a simple resistor instead of a complex circuit, and meanwhile, the accuracy of measurement can be ensured, and the resistor can discharge the storage capacitor, so that the storage capacitor is reset to prepare for the next measurement in a simple and efficient manner. Accordingly, according to the embodiments of the present disclosure, the junction temperature can be accurately measured and the problem of inaccurate measurement due to curve shift caused by storage capacitor discharge can be compensated. In addition, according to the embodiments of the present disclosure, the relationship between the respective parameters may be intuitively expressed in the form of a function, and may be calculated through the function to obtain an accurate junction temperature. The relation function of the storage capacitor voltage and the junction temperature can be obtained through simplification, for example, a linear function or a second power function can be obtained through simplification, wherein the linear relation function has the advantages of being simple in calculation and capable of meeting the requirements on accuracy.

It is to be understood that the above detailed embodiments of the present disclosure are merely illustrative or explanatory of the principles of the disclosure and are not intended to limit the disclosure. Accordingly, any modifications, equivalent substitutions, improvements, etc. should be included within the scope of the present disclosure without departing from the spirit and scope of the present disclosure. Meanwhile, the appended claims of the present disclosure are intended to cover all such variations and modifications as fall within the scope and boundary of the claims or the equivalents of the scope and boundary.

Claims

1. An apparatus for characterizing junction temperature of an insulated gate bipolar transistor, IGBT, device, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the apparatus comprising:

a peak detection circuit configured to measure different peaks of an induced voltage on a second stray inductance between a main emitter node and an auxiliary emitter node of the second IGBT during switching operation of the second IGBT at different half-cycles of a phase current; and

a junction temperature characterizer configured to generate a first characterization signal and a second characterization signal, respectively, based on the different peaks, the first characterization signal characterizing a first junction temperature of the first IGBT and the second characterization signal characterizing a second junction temperature of the second IGBT.

2. The apparatus of claim 1, wherein the junction temperature characterizer is configured to:

during a first half period of the phase current, a junction temperature of the first IGBT is characterized based on a peak value of the induced voltage during the first half period, and during a second half period of the phase current, a junction temperature of the second IGBT is characterized based on a peak value of the induced voltage during the second half period, wherein the first half period is a positive half period or a negative half period, and the second half period is a negative half period or a positive half period.

3. A method for characterizing junction temperature of an insulated gate bipolar transistor, IGBT, device, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the method comprising the steps of:

receiving a first characterization signal characterizing a first half-cycle and a second characterization signal characterizing a second half-cycle;

characterizing a first junction temperature of the first IGBT based on the first characterization signal; and

and characterizing a second junction temperature of a second IGBT based on the second characterization signal.

4. A method according to claim 3, wherein the first half cycle is a positive half cycle or a negative half cycle and the second half cycle is a negative half cycle or a positive half cycle.

5. A peak detection circuit for characterizing junction temperature of an insulated gate bipolar transistor, IGBT, device, comprising:

a peak detector configured to obtain a peak voltage;

the storage capacitor is connected with the peak detector, and the output voltage of the peak detector enables the storage capacitor to be charged to obtain storage capacitor voltage until the maximum storage capacitor voltage is obtained;

a resistor in parallel with the storage capacitor, the resistor and the storage capacitor forming a loop, such that the resistor discharges the storage capacitor for obtaining a next maximum storage capacitor voltage,

wherein the maximum storage capacitor voltage is used to characterize the junction temperature of the insulated gate bipolar transistor IGBT device.

6. The peak detection circuit of claim 5, wherein the peak detector comprises a first operational amplifier, a second operational amplifier, and a diode, the positive input terminal of the first operational amplifier receiving an input voltage, the output terminal of the first operational amplifier being connected to the positive electrode of the diode, the positive electrode of the diode being connected to the positive input terminal of the second operational amplifier and the positive electrode of the capacitor, the output terminal of the second operational amplifier being connected to the negative input terminal of the first operational amplifier and the negative input terminal of the second operational amplifier.

7. The peak detection circuit according to claim 6, wherein the first operational amplifier has a voltage following function and the second operational amplifier has a buffer isolation function.

8. The peak detection circuit according to claim 6, wherein when a potential of the positive input terminal of the first operational amplifier is greater than a potential of the negative input terminal of the first operational amplifier, the output terminal of the first operational amplifier outputs a positive voltage such that the diode is turned on and the output terminal of the first operational amplifier charges the storage capacitor.

9. The peak detection circuit according to claim 6, wherein when a potential of the positive input terminal of the first operational amplifier is smaller than a potential of the negative input terminal of the first operational amplifier, the output terminal of the first operational amplifier outputs a negative voltage such that the diode is turned off and the output terminal of the first operational amplifier does not charge the storage capacitor.

10. The peak detection circuit of claim 5, further comprising a voltage divider configured to convert a voltage from the IGBT device to a desired voltage level.

11. The peak detection circuit according to any one of claims 5 to 10, wherein a resistance value of the resistor is configured such that a maximum peak voltage that can be obtained by the storage capacitor is smaller than a minimum peak voltage that can be obtained after discharge.

12. A method for characterizing junction temperature of an insulated gate bipolar transistor, IGBT, device using a peak detection circuit according to any of claims 5 to 11, the method comprising the steps of:

obtaining the relation between the voltage of the storage capacitor after discharge and the peak voltage;

obtaining the relation between the peak voltage and the junction temperature;

obtaining the relation between the discharge time of the storage capacitor and the junction temperature;

obtaining the relationship between the voltage of the storage capacitor after discharge and the junction temperature through the relationship between the voltage of the storage capacitor after discharge and the peak voltage, the relationship between the peak voltage and the junction temperature and the relationship between the discharge time and the junction temperature; and

and characterizing the junction temperature based on the voltage of the storage capacitor after discharging.

13. The method of claim 12, wherein the storage capacitor discharged voltage is a function of the peak voltage and the discharge time, the peak voltage and the junction temperature are a function of the peak voltage and the junction temperature, the discharge time and the junction temperature are a function of the discharge time and the junction temperature, and the storage capacitor discharged voltage and the junction temperature are a function of the junction temperature.

14. The method of claim 13, wherein the voltage after discharge of the storage capacitor is fitted to a function of the junction temperature.

15. An apparatus for characterizing junction temperature of an insulated gate bipolar transistor, IGBT, device, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the apparatus comprising:

a peak measurement circuit configured to measure different peak voltages of the induced voltage on the second stray inductance between the main emitter node and the auxiliary emitter node of the second IGBT during switching operation of the second IGBT over different half-cycles of the phase current; and

a junction temperature characterizer configured to generate a first characterization signal and a second characterization signal, respectively, based on the different maximum storage capacitor voltages, the first characterization signal characterizing a first junction temperature of the first IGBT, the second characterization signal characterizing a second junction temperature of the second IGBT,

wherein the peak measurement circuit comprises:

a peak detector configured to obtain a peak voltage;

and a resistor connected in parallel with the storage capacitor, wherein the resistor and the storage capacitor form a loop, so that the resistor discharges the storage capacitor for obtaining the next maximum storage capacitor voltage.

16. A method for characterizing junction temperature of an insulated gate bipolar transistor, IGBT, device, wherein the IGBT device comprises a first IGBT and a second IGBT connected in series, the method comprising the steps of:

characterizing a second junction temperature of a second IGBT based on the second characterization signal,

wherein the method further comprises characterizing a junction temperature of the insulated gate bipolar transistor, IGBT, device using the peak detection circuit according to any of claims 5 to 10, comprising the steps of:

obtaining the relation between the peak voltage and the junction temperature;