CN116136565A - Method, device and circuit for detecting two parallel silicon carbide field effect transistors - Google Patents

Abstract

The application relates to a method, a device and a circuit for detecting two parallel silicon carbide field effect transistors. The method comprises the following steps: respectively inputting a first driving voltage and a second driving voltage into the two parallel silicon carbide field effect transistors to obtain a first saturated current corresponding to the first driving voltage and a second saturated current corresponding to the second driving voltage, wherein the first driving voltage and the second driving voltage are voltages of the two parallel silicon carbide field effect transistors in a saturated state, and the first driving voltage is not equal to the second driving voltage; and determining a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturation current, the second saturation current and the field effect transistor parameters. According to the method, the silicon carbide field effect transistor with larger aging degree can be determined through the larger of the threshold voltages of the two silicon carbide field effect transistors connected in parallel, and then the actual health state of the two silicon carbide field effect transistors connected in parallel is determined.

Description

Method, device and circuit for detecting two parallel silicon carbide field effect transistors

Technical Field

The application relates to the technical field of power semiconductor device testing, in particular to a method, a device and a circuit for detecting two parallel silicon carbide field effect transistors.

Background

With the development of power semiconductor technology, siC MOSFETs (silicon carbide field effect transistors) have been widely focused and applied due to their characteristics of high breakdown field strength, high thermal conductivity, high saturated electron drift rate, and the like. However, due to the immaturity of silicon carbide field effect transistor gate oxide processes, silicon carbide devices can exhibit unique chip-related failure modes compared to silicon power devices. Electrons in the channel tunnel into the gate oxide under long term gate bias stress and are trapped by near-interface oxide traps. The accumulation of electrons in the gate oxide weakens the effective electric field across the oxide, resulting in an increase in threshold voltage that in turn leads to an increase in device loss. Thus, the threshold voltage shift of a silicon carbide field effect transistor can be used as a parameter for representing the health state of the silicon carbide field effect transistor.

In order to improve the power class and the current capacity of the power module, the power module adopts a multi-silicon carbide field effect transistor parallel structure. In the parallel structure of the multi-silicon carbide field effect tube, due to the inconformity of heat dissipation conditions and operation conditions of the silicon carbide field effect tubes, the phenomenon of inconformity of degradation occurs among the parallel silicon carbide field effect tubes, and the phenomenon of inconformity of current distribution and heat non-uniformity among the parallel silicon carbide field effect tubes can be further caused, so that the safe operation of the power module is affected. Therefore, the method has practical significance in detecting the threshold voltage of the multi-chip parallel silicon carbide power module and further detecting the health state of the multi-chip parallel silicon carbide power module.

However, in the related art, since all the electrical interfaces (gate, drain and source) between the parallel silicon carbide field effect transistors are connected together, when the threshold voltage is detected in the parallel state, the detection result obtained is the result of the common influence of the silicon carbide field effect transistors with different aging degrees, and the actual aging degrees of the silicon carbide field effect transistors with different aging degrees after being connected in parallel depend on the silicon carbide field effect transistor with larger aging degrees. Therefore, the state information of each silicon carbide field effect transistor is difficult to determine in the related art, and the actual health state of the two parallel silicon carbide field effect transistors is difficult to determine.

Disclosure of Invention

Accordingly, it is desirable to provide a method, an apparatus and a circuit for detecting two parallel silicon carbide field effect transistors, which can determine the actual health status of the two parallel silicon carbide field effect transistors.

In a first aspect, the present application provides a method for detecting two parallel silicon carbide field effect transistors. The method comprises the following steps:

respectively inputting a first driving voltage and a second driving voltage into the two parallel silicon carbide field effect transistors to obtain a first saturated current corresponding to the first driving voltage and a second saturated current corresponding to the second driving voltage, wherein the first driving voltage and the second driving voltage are voltages of the two parallel silicon carbide field effect transistors in a saturated state, and the first driving voltage is not equal to the second driving voltage;

and determining a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturation current, the second saturation current and the field effect transistor parameters.

In one embodiment, the determining the first and second threshold voltages of the two parallel silicon carbide fets based on the first and second drive voltages, the first and second saturation currents, and the fet parameters includes:

determining a first relationship and a second relationship of the first threshold voltage and the second threshold voltage based on the first drive voltage, the first saturation current, the second drive voltage, the second saturation current, and the fet parameter;

and determining a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first relationship and the second relationship.

In one embodiment, the first relationship comprises a sum of the first threshold voltage and a second threshold voltage.

In one embodiment, the second relationship comprises a sum of squares of the first and second threshold voltages.

In one embodiment, the FET parameters are determined based on the channel width, electron mobility, oxide specific capacitance, and length of the channel of the silicon carbide FET.

In one embodiment, the first driving voltage is greater than a parallel threshold voltage of the two parallel silicon carbide field effect transistors and less than a difference between a drain-to-kelvin source voltage drop and the parallel threshold voltage when the two parallel silicon carbide field effect transistors are turned on.

In one embodiment, the second driving voltage is greater than a parallel threshold voltage of the two parallel silicon carbide field effect transistors and less than a difference between a drain-to-kelvin source voltage drop when the two parallel silicon carbide field effect transistors are turned on and the parallel threshold voltage.

In one embodiment, the obtaining the first saturation current corresponding to the first driving voltage and the second saturation current corresponding to the second driving voltage includes:

and the drain electrodes of the two parallel silicon carbide field effect transistors are respectively provided with a Rogowski coil, and the first saturation current and the second saturation current are obtained based on detection of the Rogowski coils.

In a second aspect, the present application further provides a two parallel silicon carbide field effect transistor detection device. The apparatus for implementing the steps of the method of any one of the first aspect above, the apparatus comprising a power supply selection module, a saturation current determination module and a threshold voltage determination module connected to each other in pairs, wherein,

the power supply selection module is used for providing the first driving voltage and the second driving voltage and inputting the first driving voltage and the second driving voltage into the field effect tube working module;

the saturated current determining module is used for obtaining a first saturated current and a second saturated current corresponding to the two parallel silicon carbide field effect transistors based on the input first driving voltage and second driving voltage;

the threshold voltage determining module is used for collecting the first driving voltage, the second driving voltage, the first saturated current and the second saturated current, and determining the first threshold voltage and the second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturated current, the second saturated current and the field effect transistor parameters.

In a third aspect, the present application further provides a two parallel silicon carbide field effect transistor detection circuit, including a driving voltage module and a field effect transistor module connected to each other, wherein,

the driving voltage module comprises a first driving voltage source positive electrode, a second driving voltage source positive electrode and a selection switch, one end of the selection switch is used for selecting and connecting the first driving voltage source or the second driving voltage source, the other end of the selection switch is connected with a collector electrode of a first triode, an emitter electrode of the first triode is connected with one end of a first resistor, a base electrode of the first triode is respectively connected with a driving signal source and a base electrode of a second triode, an emitter electrode of the second triode is connected with a voltage source negative electrode, a collector electrode of the second triode is connected with one end of a second resistor, and the other end of the first resistor is connected with the other end of the second resistor and is connected with the field effect transistor module;

the field effect tube module comprises a first field effect tube, a second field effect tube, a third resistor and a fourth resistor, wherein the grid electrode of the first field effect tube is connected with the grid electrode of the second field effect tube and is connected with the driving voltage module, the drain electrode of the first field effect tube is connected with the drain electrode of the second field effect tube, the source electrode of the first field effect tube is connected with one end of the third resistor, the source electrode of the second field effect tube is connected with one end of the fourth resistor, the other end of the third resistor is connected with the other end of the fourth resistor, and the source electrode of the first field effect tube is connected with the source electrode of the second field effect tube and is grounded.

According to the method and the device for detecting the two parallel silicon carbide field effect transistors, the first driving voltage and the second driving voltage are respectively input into the two parallel silicon carbide field effect transistors to obtain the first saturated current corresponding to the first driving voltage and the second saturated current corresponding to the second driving voltage, the first driving voltage and the second driving voltage are voltages of the two parallel silicon carbide field effect transistors working in a saturated state, the first driving voltage is not equal to the second driving voltage, and the first threshold voltage and the second threshold voltage of the two parallel silicon carbide field effect transistors are determined based on the first driving voltage, the second driving voltage, the first saturated current, the second saturated current and the field effect transistor parameters. According to the detection method for the two parallel silicon carbide field effect transistors, the corresponding saturated current can be obtained by inputting different driving voltages, the threshold voltage of the two parallel silicon carbide field effect transistors is further determined, the silicon carbide field effect transistor with larger aging degree can be determined through the larger one of the two threshold voltages, and then the actual health state of the two parallel silicon carbide field effect transistors is determined.

The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below to provide a more thorough understanding of the other features, objects, and advantages of the application.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:

FIG. 1 is a flow chart of a method for detecting two parallel silicon carbide field effect transistors in one embodiment;

FIG. 2 is a block diagram of a two parallel silicon carbide FET detection device in one embodiment;

FIG. 3 is a schematic diagram of two parallel SiC FETs in one embodiment;

FIG. 4 is a schematic diagram of a circuit of two parallel silicon carbide FETs saturating current according to one embodiment;

FIG. 5 is a flow chart of a method for detecting two parallel silicon carbide field effect transistors in an embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

Unless defined otherwise, technical or scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms "a," "an," "the," "these," and the like in this application are not intended to be limiting in number, but rather are singular or plural. The terms "comprising," "including," "having," and any variations thereof, as used in the present application, are intended to cover a non-exclusive inclusion; for example, a process, method, and system, article, or apparatus that comprises a list of steps or modules (units) is not limited to the list of steps or modules (units), but may include other steps or modules (units) not listed or inherent to such process, method, article, or apparatus. The terms "connected," "coupled," and the like in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Reference to "a plurality" in this application means two or more. "and/or" describes an association relationship of an association object, meaning that there may be three relationships, e.g., "a and/or B" may mean: a exists alone, A and B exist together, and B exists alone. Typically, the character "/" indicates that the associated object is an "or" relationship. The terms "first," "second," "third," and the like, as referred to in this application, merely distinguish similar objects and do not represent a particular ordering of objects.

The terms "module," "unit," and the like are used below as a combination of software and/or hardware that can perform a predetermined function. While the means described in the following embodiments are preferably implemented in hardware, implementations of software, or a combination of software and hardware, are also possible and contemplated.

With the development of power semiconductor technology, siC MOSFETs (silicon carbide field effect transistors) have been widely focused and applied due to their characteristics of high breakdown field strength, high thermal conductivity, high saturated electron drift rate, and the like. However, due to the immaturity of silicon carbide field effect transistor gate oxide processes, silicon carbide devices can exhibit unique chip-related failure modes compared to silicon power devices. Electrons in the channel tunnel into the gate oxide under long term gate bias stress and are trapped by near-interface oxide traps. The accumulation of electrons in the gate oxide weakens the effective electric field across the oxide, resulting in an increase in threshold voltage that in turn leads to an increase in device loss. Thus, the threshold voltage of a silicon carbide field effect transistor can be taken as a parameter characterizing its health. In order to improve the power class and the current capacity of the power module, the power module adopts a multi-silicon carbide field effect transistor parallel structure. In the parallel structure of the multi-silicon carbide field effect tube, due to the inconformity of heat dissipation conditions and operation conditions of the silicon carbide field effect tubes, the phenomenon of inconformity of degradation occurs among the parallel silicon carbide field effect tubes, and the phenomenon of inconformity of current distribution and heat non-uniformity among the parallel silicon carbide field effect tubes can be further caused, so that the safe operation of the power module is affected. Therefore, the method has practical significance in detecting the threshold voltage of the multi-chip parallel silicon carbide power module and further determining the health state of the multi-chip parallel silicon carbide power module. However, in the related art, since all the electrical interfaces (gate, drain and source) between the parallel silicon carbide field effect transistors are connected together, when the threshold voltage is detected in the parallel state, the detection result obtained is the result of the common influence of the silicon carbide field effect transistors with different aging degrees, and the actual aging degrees of the silicon carbide field effect transistors with different aging degrees after being connected in parallel depend on the silicon carbide field effect transistor with larger aging degrees. Therefore, the state information of each silicon carbide field effect transistor is difficult to determine in the related art, and the actual health state of the two parallel silicon carbide field effect transistors is difficult to determine.

In view of the unbalanced aging phenomenon of two parallel silicon carbide field effect transistors and the limitations of the related technology, as shown in fig. 1, an embodiment of the present application provides a method for detecting two parallel silicon carbide field effect transistors, where the method includes:

s201: and respectively inputting a first driving voltage and a second driving voltage into the two parallel silicon carbide field effect transistors to obtain a first saturated current corresponding to the first driving voltage and a second saturated current corresponding to the second driving voltage, wherein the first driving voltage and the second driving voltage are voltages of the two parallel silicon carbide field effect transistors working in a saturated state, and the first driving voltage is not equal to the second driving voltage.

In an embodiment of the present application, the silicon carbide field effect transistor includes a compound semiconductor field effect transistor composed of silicon and carbide. The silicon carbide field effect transistor threshold voltage is the voltage applied to the gate when the source and drain of the silicon carbide field effect transistor begin to conduct. Although silicon carbide field effect transistors have lower on-resistance and switching loss compared with silicon field effect transistors of the same power class, and are suitable for higher operating frequencies and have higher high-temperature stability, the silicon carbide devices can have unique chip-related failure modes which cause the increase of threshold voltages to cause the increase of device loss, so that the threshold voltages can be used as parameters for representing the health state of the silicon carbide field effect transistors.

In this embodiment of the present application, the two parallel silicon carbide field effect transistors include two silicon carbide field effect transistors with source electrodes, gate electrodes, and drain electrodes respectively connected in parallel. And inputting a first driving voltage to the grid electrodes of the two parallel silicon carbide field effect transistors, and detecting the total current of the drain electrodes of the two parallel silicon carbide field effect transistors to obtain a first saturated current corresponding to the first driving voltage. Similarly, a second driving voltage is input to the gates of the two parallel silicon carbide field effect transistors, and a second saturation current corresponding to the second driving voltage can be obtained. The first driving voltage and the second driving voltage are voltages of the two parallel silicon carbide field effect transistors working in a saturated state. The first driving voltage and the second driving voltage can comprise the voltage difference between the grid electrode and the source electrode of the two parallel silicon carbide field effect transistors, and the first driving voltage and the second driving voltage are voltages of the two parallel silicon carbide field effect transistors working in a saturated state. In this embodiment, the saturation state is a working state in which the total current of the drains of the two parallel silicon carbide field effect transistors hardly changes with the increase of the gate-source voltage. The first driving voltage is not equal to the second driving voltage, and the first saturated current and the second saturated current corresponding to the first driving voltage and the second saturated current can be obtained respectively by applying different first driving voltages and second driving voltages respectively, so that two groups of different driving voltage-saturated current data groups can be obtained.

S203: and determining a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturation current, the second saturation current and the field effect transistor parameters.

In this embodiment, the fet parameters include parameters related to the fet structure. In general, two parallel silicon carbide field effect transistors work as a power module in the form of a packaged chip, and the parameters of the field effect transistors may be structural parameters common to the two parallel silicon carbide field effect transistors. In other embodiments, if two fets of the respective fet parameters are known to be connected in parallel, the common fet parameter after the parallel connection may be determined based on the respective fet parameters.

In this embodiment of the present application, after determining the first driving voltage, the second driving voltage, the first saturation current, the second saturation current, and the fet parameter, the relationship between the first saturation current and the threshold voltage and the relationship between the second saturation current and the threshold voltage may be determined based on the fet parameter under the first driving voltage and the second driving voltage, respectively. Further, because the saturation current is the sum of the saturation currents of the two silicon carbide field effect transistors, the relationship between the first saturation current and the first threshold voltage and the relationship between the second saturation current and the first threshold voltage and the second threshold voltage can be further determined under the first driving voltage and the second driving voltage, and the relationship between the second saturation current and the first threshold voltage and the second threshold voltage can be finally determined.

According to the detection method for the two parallel silicon carbide field effect transistors, the corresponding saturated current can be obtained through inputting different driving voltages, the threshold voltages of the two parallel silicon carbide field effect transistors are further determined, after the respective threshold voltages of the two parallel silicon carbide field effect transistors are determined, the silicon carbide field effect transistor with larger aging degree can be determined through the larger one of the two threshold voltages, and then the actual health state of the two parallel silicon carbide field effect transistors is determined. In the embodiment of the application, when two parallel silicon carbide field effect transistors are initially selected, manufactured or packaged into a power module, two silicon carbide field effect transistors with the threshold voltages close to or the same as each other are generally selected, and the initial threshold voltages of the two parallel silicon carbide field effect transistors are marked. However, the threshold voltage shift phenomenon existing in the working process can cause the aging of the two parallel silicon carbide field effect transistors, and the aging degrees of the two silicon carbide field effect transistors can be different. The larger one of the first threshold voltage and the second threshold voltage detected in the embodiment of the application has larger difference value with the initial threshold voltage, and the drift degree of the threshold voltage is larger, so that the aging degree of the silicon carbide field effect transistor corresponding to the larger threshold voltage is also larger, and the actual aging degree of the two parallel silicon carbide field effect transistors can be represented. Based on the above, the difference between the initial voltage and the larger of the first threshold voltage and the second threshold voltage can be used as the detection result of the health state of the two parallel silicon carbide field effect transistors. In other embodiments, since the initial threshold voltage is unchanged, the greater of the first threshold voltage and the second threshold voltage may also be directly used as the detection result of the health states of the two parallel silicon carbide field effect transistors.

In the embodiment of the application, the actual health states of the two parallel silicon carbide field effect transistors are determined, so that the service lives of the chips and the devices can be managed more accurately, the phenomenon that normal work cannot be continued or other devices cannot be damaged due to abnormality and aging failure in the working process of the chips and the devices is avoided, and the working stability of the two parallel silicon carbide field effect transistors and integrated circuits, chips or devices of the two parallel silicon carbide field effect transistors is effectively improved.

In this embodiment, determining the first threshold voltage and the second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturation current, the second saturation current, and the field effect transistor parameter in step S203 includes:

s301: the first and second relationships of the first and second threshold voltages are determined based on the first drive voltage, the first saturation current, the second drive voltage, the second saturation current, and the fet parameter.

S303: and determining a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first relationship and the second relationship.

In this embodiment of the present application, the input voltage of the two parallel silicon carbide field effect transistors is the first driving voltage V _gs1 At the time, a first saturation current I _d(sat)1 Can be represented by formula (1):

I _d(sat)1 ＝k(V _gs1 -V _th1 ) ² +k(V _gs1 -V _th2 ) ² (1)

wherein I is _d(sat)1 For the first saturation current, k is the FET parameter, V _gs1 For the first driving voltage, V _th1 At a first threshold voltage of V _th2 Is the second threshold voltage. The physical meaning of the formula (1) is that the input voltage is the first driving voltage V _gs1 When the first saturation current is the sum of the saturation currents of the two parallel silicon carbide field effect transistors, k (V _gs1 -V _th1 ) ² And k (V) _gs1 -V _th2 ) ² Respectively represent the respective saturation currents of the two parallel silicon carbide field effect transistors. Similarly, the input voltage of the two parallel silicon carbide field effect transistors is the second driving voltage V _gs2 At the time, the second saturation current I _d(sat)2 Can be represented by formula (2):

I _d(sat)2 ＝k(V _gs2 -V _th1 ) ² +k(V _gs2 -V _th2 ) ² (2)

wherein I is _d(sat)2 Is the second saturation current, k is the parameter of the field effect transistor, V _gs2 For the second driving voltage, V _th1 At a first threshold voltage of V _th2 Is the second threshold voltage.

Expanding the formula (1) can obtain the formula (3):

I _d(sat)1 ＝2kV _gs1 ² +k(V _th1 ² +V _th2 ² )-2kV _gs1 (V _th1 +V _th2 ) (3)

wherein I is _d(sat)1 For the first saturation current, k is the FET parameter, V _gs1 For the first driving voltage, V _th1 At a first threshold voltage of V _th2 Is the second threshold voltage. Similarly, expanding formula (2) can result in formula (4):

I _d(sat)2 ＝2kV _gs2 ² +k(V _th1 ² +V _th2 ² )-2kV _gs2 (V _th1 +V _th2 ) (4)

wherein I is _d(sat)2 Is the second saturation current, k is the parameter of the field effect transistor, V _gs2 For the second driving voltage, V _th1 At a first threshold voltage of V _th2 Is the second threshold voltage. Further, formula (5) can be obtained by subtracting formula (3) from formula (4):

I _d(sat)2 -I _d(sat)1 ＝2k(V _gs2 ² -V _gs1 ² )-2k(V _th1 +V _th2 )(V _gs2 -V _gs1 ) (5)

wherein I is _d(sat)1 For the first saturation current, I _d(sat)2 Is the second saturation current, k is the parameter of the field effect transistor, V _gs1 For the first driving voltage, V _gs2 For the second driving voltage, V _th1 At a first threshold voltage of V _th2 Is the second threshold voltage. In the embodiment of the application, the first driving voltage V may be based on _gs1 First saturation current I _d(sat)1 Second driving voltage V _gs2 Second saturation current I _d(sat)2 And a FET parameter k to determine the first threshold voltage V _th1 And a second threshold voltage V _th2 Is the first relation C of (2) ₁ And a second relation C ₂ 。

In the embodiment of the present application, the first relation C ₁ May include the first threshold voltage V _th1 And a second threshold valueVoltage V _th2 And (3) summing. From equation (5), equation (6) can be obtained, the first relationship C ₁ Expressed by formula (6):

wherein C is ₁ V is the first relation between the first threshold voltage and the second threshold voltage of two parallel silicon carbide field effect transistors _th1 At a first threshold voltage of V _th2 At a second threshold voltage of V _gs1 For the first driving voltage, V _gs2 For the second driving voltage, I _d(sat)1 For the first saturation current, I _d(sat)2 And k is a field effect transistor parameter.

In the embodiment of the present application, the second relation C ₂ May include the first threshold voltage V _th1 And a second threshold voltage V _th2 Square sum of (d). Substituting formula (6) into formula (3) to obtain formula (7), the second relationship C ₂ Expressed by formula (7):

wherein C is ₂ V is the second relation between the first threshold voltage and the second threshold voltage of two parallel silicon carbide field effect transistors _th1 At a first threshold voltage of V _th2 At a second threshold voltage of V _gs1 For the first driving voltage, V _gs2 For the second driving voltage, I _d(sat)1 For the first saturation current, I _d(sat)2 And k is a field effect transistor parameter.

In the embodiment of the application, the first relation C expressed by the formula (6) is related ₁ And a second relation C represented by formula (7) ₂ Formula (8) can be obtained:

then based on the first relationC ₁ And a second relation C ₂ Determining a first threshold voltage V of the two parallel silicon carbide field effect transistors _th1 And a second threshold voltage V _th2 Can be represented by formula (9):

in the embodiment of the application, the first threshold voltage V _th1 And a second threshold voltage V _th2 Can be respectively expressed as

It is possible to do this according to the larger of them +.>

The actual threshold voltages of the two parallel silicon carbide field effect transistors are represented, and the actual health states of the two parallel silicon carbide field effect transistors are further determined.

The decoupling detection of the health states of the silicon carbide field effect transistors in the two parallel silicon carbide field effect transistors or the two parallel silicon carbide power modules formed by the two parallel silicon carbide field effect transistors is realized, the problem that the independent state detection of the silicon carbide field effect transistors is difficult to carry out under the parallel condition in the related technology is solved, the health management level of power electronic equipment is improved, and the degradation rule and failure mechanism of the multi-chip parallel silicon carbide module are also facilitated to be explored.

In this embodiment of the present application, the fet parameters are determined based on the channel width, electron mobility, oxide specific capacitance, and length of the channel of the silicon carbide fet. In some embodiments, the fet parameter k may be determined according to equation (10):

wherein W is the channel width, mu _n For electron mobility, C _ox The specific capacitance of the oxide layer, L is the length of the channel, and the parameters areStructural parameters of silicon carbide field effect transistors.

In this embodiment of the present application, the first driving voltage is greater than a parallel threshold voltage of the two parallel silicon carbide field effect transistors, and is less than a difference between a voltage drop from a drain to a kelvin source when the two parallel silicon carbide field effect transistors are turned on and the parallel threshold voltage. The second driving voltage is larger than the parallel threshold voltage of the two parallel silicon carbide field effect transistors and smaller than the difference between the voltage drop from the drain to the Kelvin source when the two parallel silicon carbide field effect transistors are conducted and the parallel threshold voltage.

In this embodiment, to obtain the first saturation current and the second saturation current of the two parallel silicon carbide field effect transistors, the first driving voltage and the second driving voltage should be set to make the field effect transistors work in a saturated state. Based on this, the first driving voltage V _gs1 Formula (11) should be satisfied:

V _th <V _gs1 <V _Ds -V _th (11)

wherein V is _Ds For the voltage drop between the drain terminal of the chip and the Kelvin source terminal, i.e. the conduction voltage drop of the chip, V _th Is the threshold voltage of the chip. Similarly, the second driving voltage V _gs2 Formula (12) should be satisfied:

V _th <V _gs2 <V _Ds -V _th (11)

wherein V is _Ds For the voltage drop between the drain terminal of the chip and the Kelvin source terminal, i.e. the conduction voltage drop of the chip, V _th Is the threshold voltage of the chip.

In this embodiment of the present application, the obtaining the first saturation current corresponding to the first driving voltage and the second saturation current corresponding to the second driving voltage includes: and setting a Rogowski coil on the drain electrodes of the two parallel silicon carbide field effect transistors, and detecting the first saturation current and the second saturation current based on the Rogowski coil. In the embodiment of the application, the Rogowski coil is used for detecting the saturation current, no special requirements are imposed on the conductor and the size, the rapid transient response capability is achieved, and the detection efficiency of the saturation current can be improved.

It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.

Based on the same inventive concept, the embodiment of the present application further provides a two-parallel silicon carbide field effect transistor detection device 400 for implementing the two-parallel silicon carbide field effect transistor detection method. The implementation of the solution provided by the apparatus 400 is similar to the implementation described in the above method, so the specific limitation of the embodiment of the two-parallel silicon carbide field effect transistor detection apparatus 400 provided below may be referred to the limitation of the two-parallel silicon carbide field effect transistor detection method hereinabove, and will not be repeated here.

In one embodiment, as shown in fig. 2, a two-by-two parallel silicon carbide field effect transistor detection device 400 is provided, which includes a power supply selection module 401, a saturation current determination module 402, and a threshold voltage determination module 403 that are connected to each other, wherein:

the power supply selection module 401 is configured to provide the first driving voltage and the second driving voltage and input the first driving voltage and the second driving voltage to the fet operation module;

the saturation current determining module 402 is configured to obtain a first saturation current and a second saturation current corresponding to the two parallel silicon carbide field effect transistors based on the input first driving voltage and second driving voltage;

the threshold voltage determining module 403 is configured to collect the first driving voltage, the second driving voltage, the first saturation current, and the second saturation current, and determine a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturation current, the second saturation current, and the field effect transistor parameter.

The modules in the two parallel silicon carbide field effect transistor detection devices 400 may be all or partially implemented by software, hardware, or a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.

In the embodiment of the application, a two-parallel silicon carbide field effect transistor detection circuit is further provided, and based on the two-parallel silicon carbide field effect transistor detection method in the embodiment of the application, the threshold voltage of the field effect transistor in the two-parallel silicon carbide field effect transistor detection circuit can be detected. As shown in fig. 3, the two parallel silicon carbide field effect transistor detection circuits include a driving voltage module and a field effect transistor module connected to each other, wherein,

the driving voltage module comprises a first driving voltage source anode V _gs1 Positive pole V of second driving voltage source _gs2 And a selection switch S, one end of which is used for selectively connecting the first driving voltage source V _gs1 Or a second driving voltage source V _gs2 The other end of the selection switch is connected with the collector of a first triode Q1, and the emitter of the first triode Q1 is connected with a first resistor R _{g_on} The base of the first triode Q1 is respectively connected with a driving signal source and the base of a second triode Q2, the emitter of the second triode Q2 is connected with a voltage source cathode which is shown as-5V in figure 3, and the collector of the second triode Q2 is connected with a second resistor R _{g_off} Is connected with one end of the first resistor R _{g_on} And a second resistor R _{g_off} Is connected with the other end of the field effect tube moduleConnecting;

the field effect tube module comprises a first field effect tube Q3, a second field effect tube Q4 and a third resistor R _bw1 And a fourth resistor R _bw2 The grid electrode of the first field effect tube Q3 and the grid electrode of the second field effect tube Q4 are connected and connected with the driving voltage module, the drain electrode of the first field effect tube Q3 is connected with the drain electrode of the second field effect tube Q4, and the source electrode of the first field effect tube Q3 and the third resistor R _bw1 One end of the second FET Q4 is connected with the fourth resistor R _bw2 Is connected with one end of the third resistor R _bw1 And the other end of the fourth resistor R _bw2 The source electrode of the first field effect transistor Q3 is connected with the source electrode of the second field effect transistor Q4 and grounded.

In this embodiment, the driving signal source is used for controlling the switch of the first triode Q1 and the second triode Q2. When the driving signal source sends a high-level signal, the first triode Q1 is conducted, and the selection switch selects and turns on the working voltage +15V and the first driving voltage source V _gs1 And a second driving voltage source V _gs2 The turned-on voltage source is applied to the gates of the first field effect transistor Q3 and the second field effect transistor Q4. In contrast, if the driving signal source sends a low level signal, the second triode Q2 is turned on, and the negative electrode of the voltage source-5V is applied to the gates of the first fet Q3 and the second fet Q4. The first resistor R _{g_on} And a second resistor R _{g_off} The resistor is used for driving the resistor and controlling the switching speed of the two parallel silicon carbide field effect transistors so as to control the loss of the silicon carbide field effect transistors. Wherein the first resistor R _{g_on} To turn on the resistor, a second resistor R _{g_off} To turn off the resistor. In this embodiment, the first transistor Q1 and the second transistor Q2 are equivalent resistances of the two parallel silicon carbide field effect transistors.

In this embodiment, as shown in fig. 4, a schematic circuit diagram of two parallel silicon carbide field effect transistors is shown, where the saturation currents include a first saturation current and a second saturation current. As can be seen from fig. 4, in the case of silicon carbide field effect transistor operating in saturation state, the total saturation current I of the parallel-connected drain electrodesSaturation current I for each of two silicon carbide field effect transistors ₁ 、I ₂ And (3) summing.

The method for detecting two parallel silicon carbide field effect transistors provided by the present application will be described by a specific embodiment of the present application, and the circuit of fig. 3 or fig. 4 is used as an example, as shown in fig. 5, to adjust the selection switch S to turn on the first driving voltage V _gs1 Detecting a first saturation current I _d(sat)1 Further, the above formula (1) can be obtained. The re-selection switch S is adjusted to switch on the second driving voltage V _gs2 Detecting a second saturation current I _d(sat)2 Further, the above formula (2) can be obtained. The first relation C between the first threshold voltage and the second threshold voltage of the two parallel silicon carbide field effect transistors can be obtained according to the formula (1) and the formula (2) ₁ And a second relation C ₂ Finally, the first threshold voltage V of the two parallel silicon carbide field effect transistors can be obtained _th1 And a second threshold voltage V _th2 。

Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, database, or other medium used in the various embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high density embedded nonvolatile Memory, resistive random access Memory (ReRAM), magnetic random access Memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric Memory (Ferroelectric Random Access Memory, FRAM), phase change Memory (Phase Change Memory, PCM), graphene Memory, and the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, and the like. By way of illustration, and not limitation, RAM can be in the form of a variety of forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), and the like. The databases referred to in the various embodiments provided herein may include at least one of relational databases and non-relational databases. The non-relational database may include, but is not limited to, a blockchain-based distributed database, and the like. The processors referred to in the embodiments provided herein may be general purpose processors, central processing units, graphics processors, digital signal processors, programmable logic units, quantum computing-based data processing logic units, etc., without being limited thereto.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.

Claims (10)

1. The method for detecting the silicon carbide field effect transistors in two parallel connection is characterized by comprising the following steps:

respectively inputting a first driving voltage and a second driving voltage into the two parallel silicon carbide field effect transistors to obtain a first saturated current corresponding to the first driving voltage and a second saturated current corresponding to the second driving voltage, wherein the first driving voltage and the second driving voltage are voltages of the two parallel silicon carbide field effect transistors in a saturated state, and the first driving voltage is not equal to the second driving voltage;

and determining a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturation current, the second saturation current and the field effect transistor parameters.

2. The method of claim 1, wherein determining the first and second threshold voltages of two parallel silicon carbide fets based on the first and second drive voltages, the first and second saturation currents, and the fet parameters comprises:

determining a first relationship and a second relationship of the first threshold voltage and the second threshold voltage based on the first drive voltage, the first saturation current, the second drive voltage, the second saturation current, and the fet parameter;

and determining a first threshold voltage and a second threshold voltage of the two parallel silicon carbide field effect transistors based on the first relationship and the second relationship.

3. The method of claim 2, wherein the first relationship comprises a sum of the first threshold voltage and a second threshold voltage.

4. A method according to claim 3, wherein the second relationship comprises a sum of squares of the first and second threshold voltages.

5. The method of claim 1, wherein the fet parameters are determined based on a channel width, electron mobility, oxide specific capacitance, and a length of a channel of the silicon carbide fet.

6. The method of claim 1, wherein the first drive voltage is greater than a parallel threshold voltage of the two parallel silicon carbide fets and less than a difference between a drain-to-kelvin source voltage drop when the two parallel silicon carbide fets are on and the parallel threshold voltage.

7. The method of claim 1, wherein the second drive voltage is greater than a parallel threshold voltage of the two parallel silicon carbide fets and less than a difference between a drain-to-kelvin source voltage drop when the two parallel silicon carbide fets are on and the parallel threshold voltage.

8. The method of claim 1, wherein the obtaining a first saturation current corresponding to the first drive voltage and a second saturation current corresponding to the second drive voltage comprises:

and the drain electrodes of the two parallel silicon carbide field effect transistors are respectively provided with a Rogowski coil, and the first saturation current and the second saturation current are obtained based on detection of the Rogowski coils.

9. A two-parallel silicon carbide field effect transistor detection device, characterized in that the two-parallel silicon carbide field effect transistor detection device is used for realizing the steps of the method according to any one of claims 1 to 7, the device comprises a power supply selection module, a saturation current determination module and a threshold voltage determination module which are mutually connected in pairs,

the power supply selection module is used for providing the first driving voltage and the second driving voltage and inputting the first driving voltage and the second driving voltage into the field effect tube working module;

the saturated current determining module is used for obtaining a first saturated current and a second saturated current corresponding to the two parallel silicon carbide field effect transistors based on the input first driving voltage and second driving voltage;

the threshold voltage determining module is used for collecting the first driving voltage, the second driving voltage, the first saturated current and the second saturated current, and determining the first threshold voltage and the second threshold voltage of the two parallel silicon carbide field effect transistors based on the first driving voltage, the second driving voltage, the first saturated current, the second saturated current and the field effect transistor parameters.

10. A detection circuit of two parallel silicon carbide field effect transistors is characterized by comprising a driving voltage module and a field effect transistor module which are connected with each other, wherein,

the driving voltage module comprises a first driving voltage source positive electrode, a second driving voltage source positive electrode and a selection switch, one end of the selection switch is used for selecting and connecting the first driving voltage source or the second driving voltage source, the other end of the selection switch is connected with a collector electrode of a first triode, an emitter electrode of the first triode is connected with one end of a first resistor, a base electrode of the first triode is respectively connected with a driving signal source and a base electrode of a second triode, an emitter electrode of the second triode is connected with a voltage source negative electrode, a collector electrode of the second triode is connected with one end of a second resistor, and the other end of the first resistor is connected with the other end of the second resistor and is connected with the field effect transistor module;

the field effect tube module comprises a first field effect tube, a second field effect tube, a third resistor and a fourth resistor, wherein the grid electrode of the first field effect tube is connected with the grid electrode of the second field effect tube and is connected with the driving voltage module, the drain electrode of the first field effect tube is connected with the drain electrode of the second field effect tube, the source electrode of the first field effect tube is connected with one end of the third resistor, the source electrode of the second field effect tube is connected with one end of the fourth resistor, the other end of the third resistor is connected with the other end of the fourth resistor, and the source electrode of the first field effect tube is connected with the source electrode of the second field effect tube and is grounded.

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