SiC MOSFET power cycle characteristic parameter online extraction method and system

Abstract

The invention belongs to the field of reliability of components, and particularly discloses an online extraction method and system for power cycle characteristic parameters of a SiC MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). According to the invention, the characteristic parameter information of the device, including the conduction voltage drop, the drain current, the Miller plateau voltage and the device temperature, is acquired in real time, the threshold voltage is calculated through the extracted Miller plateau voltage and the drain current, and the SiC MOSFET power cycle degradation parameter fitting model is established, so that reliability analysis and life estimation can be more accurately carried out on the SiC MOSFET power cycle degradation parameter fitting model. The method can be used for reliability research of SiC MOSFETs of different models and service life estimation based on data driving.

Description

Technical Field

[0001] The present application belongs to the field of component reliability, and more specifically, to an online extraction method and system for SiC MOSFET power cycle characteristic parameters. Background Art

[0002] The current main power device aging test database is provided by NASA's AMES Research Center in the United States, but it is mainly silicon-based devices. With the large-scale application of third-generation semiconductor power devices, the device reliability research and life prediction of SiC MOSFET are becoming increasingly important. At present, the device reliability research and life prediction of SiC MOSFET at home and abroad are still in the initial stage.

[0003] Power cycle testing is a common experimental method in the field of reliability research. In this test method, the power device is actively heated due to its own loss. When it is turned on, the conduction loss is caused by the on-resistance. This conduction loss will increase the temperature inside the device. When the device temperature rises to the set value, the power current will be disconnected, allowing the device to cool down naturally or actively using the cooling system. When the device temperature drops to the set value, the cooling system is turned off, the power current is reloaded, and the next cycle is performed until the device under test reaches the failure standard. During each cycle, a temperature gradient will be generated inside the power device to accelerate the aging and failure of the device. We can collect the characteristic characterization parameters of the device in this process for reliability analysis and life estimation.

[0004] Power cycling tests are used to accelerate the aging and failure of SiC MOSFET devices, and can also simulate the actual working conditions of SiC MOSFET devices. At present, when most power cycling systems extract parameters, the MOSFET is not working during the period, which will affect the effect of power cycling and increase the error of life estimation. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a method and system for online extraction of SiC MOSFET power cycle characteristic parameters, aiming to solve the problem that when the existing method extracts parameters, the MOSFET is in a non-working state during the period, which affects the effect of the power cycle.

[0006] To achieve the above objectives, in a first aspect, the present application provides a method for online extraction of SiC MOSFET power cycle characteristic parameters, comprising:

[0007] Real-time extraction of SiC MOSFET device temperature after the power cycle test is started;

[0008] If the extracted device temperature reaches the set maximum point, the gate drive signal of the SiC MOSFET is turned off and the cooling of the SiC MOSFET is started. If the extracted device temperature drops to the set minimum point, the gate drive signal of the SiC MOSFET is turned on to perform the next power cycle.

[0009] Extracting characteristic parameter values ​​of each cycle in the cycle control process, wherein the characteristic parameters include the on-state voltage drop, the drain current when turned on, and the Miller platform voltage of the SiC MOSFET;

[0010] Calculate the threshold voltage of SiC MOSFET by extracting the Miller platform voltage and drain current during turn-on.

[0011] The relationship between the threshold voltage and the number of power cycles, and the relationship between the on-state voltage drop and the number of power cycles are fitted respectively, and the SiC MOSFET power cycle degradation parameter fitting model is obtained.

[0012] Preferably, the device temperature of the SiC MOSFET is a case temperature of the SiC MOSFET.

[0013] Preferably, the on-state voltage drop of the SiC MOSFET is the gate-source voltage sampled when the driving signal is turned on, and the Miller platform voltage is the gate driving voltage sampled when the SiC MOSFET enters the Miller platform.

[0014] Preferably, the threshold voltage of the SiC MOSFET is calculated by extracting the Miller platform voltage and the drain current when turned on, as follows:

[0015]

[0016] Among them, V th is the threshold voltage, V miller is the Miller platform voltage, S is the structural parameter of SiC MOSFET, I d is the drain current collected by the device during power cycling, I d0 and g m are the rated forward continuous drain current and transconductance of SiC MOSFET respectively.

[0017] Preferably, before fitting, a sliding average value is used to filter the array of threshold voltage and power cycle number and the array of on-state voltage drop and power cycle number.

[0018] Preferably, the SiC MOSFET power cycle degradation parameter fitting model includes:

[0019] V th(n)=a·exp(b·n)+c·exp(d·n)

[0020] V DS(ON) (n)=a·exp(b·n)+c·exp(d·n)

[0021] Among them, V th is the threshold voltage, V DS is the on-state voltage drop, n is the number of power cycles, a, b, c, d are fitting parameters, which are calculated and determined by actual sampling data.

[0022] Preferably, the method further includes: substituting the on-state voltage drop threshold for setting device failure into the power cycle degradation parameter fitting model to calculate the number of power cycles; and calculating the difference between the number of power cycles and the current number of power cycles as the remaining life of the SiC MOSFET.

[0023] Preferably, the method further comprises: obtaining the device temperature as T m The on-state voltage drop of the SiC MOSFET sampled at time T m is the midpoint between the set maximum and minimum temperature of the device; if the device temperature is T m When the on-state voltage drop of the SiC MOSFET sampled is greater than or equal to the set on-state voltage drop threshold of the device failure, a device failure warning is issued.

[0024] To achieve the above-mentioned purpose, in a second aspect, the present application provides an online extraction system for SiC MOSFET power cycle characteristic parameters, including: a device temperature extraction module, an on-state voltage drop extraction module, a drain current extraction module, a gate drive module, a Miller platform voltage extraction module, and a control module;

[0025] The device temperature extraction module is used to extract the device temperature of the SiC MOSFET in real time;

[0026] The on-state voltage drop extraction module is used to extract the drain-source voltage when the SiC MOSFET is turned on;

[0027] The drain current extraction module is used to extract the drain current when the SiC MOSFET is turned on;

[0028] The gate drive module is used to drive SiC MOSFETs of different models;

[0029] The Miller platform extraction module is used to sample the gate drive voltage when the SiC MOSFET enters the Miller platform to obtain the Miller platform voltage;

[0030] The control module is used to control each module by adopting the method described in the first aspect to realize online extraction of characteristic parameters.

[0031] Preferably, the drain current extraction module comprises: a high-precision resistor and an isolated sampling amplifier;

[0032] The high-precision resistor has an accuracy error of less than 0.1%, and is connected in series between the gate and the ground point of the SiC MOSFET;

[0033] The isolation sampling amplifier is used to isolate the power supply at the power end from the power supply signal at the control end, measure the voltage across the high-precision resistor when the SiC MOSFET is turned on, and send it to the controller to calculate the drain current when the SiC MOSFET is turned on.

[0034] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0035] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0036] The present application provides a method and system for online extraction of SiC MOSFET power cycle characteristic parameters, which can obtain the characteristic parameter information of the device in real time, including on-state voltage drop, drain current, Miller platform voltage, and device temperature. At the same time, the threshold voltage is calculated by extracting the Miller platform voltage and drain current, and a SiC MOSFET power cycle degradation parameter fitting model is established to more accurately analyze its reliability and estimate its life. The present application can be used for reliability research of different models of SiC MOSFET and life estimation based on data drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of a method for online extraction of SiC MOSFET power cycle characteristic parameters provided in an embodiment of the present application.

[0038] Figure 2 It is a schematic diagram of the structure of an online extraction system for SiC MOSFET power cycle characteristic parameters provided in an embodiment of the present application.

[0039] Figure 3 It is a schematic diagram of the on-state voltage drop extraction module provided in an embodiment of the present application.

[0040] Figure 4 It is a schematic diagram of the drain current extraction module provided in an embodiment of the present application.

[0041] Figure 5 It is a schematic diagram of a gate drive module provided in an embodiment of the present application.

[0042] Figure 6 It is a schematic diagram of the Miller platform voltage extraction module provided in an embodiment of the present application.

[0043] Figure 7 This is a schematic diagram of turning on a SiC MOSFET provided in an embodiment of the present application.

[0044] Figure 8 It is a schematic diagram of the temperature extraction module provided in an embodiment of the present application.

[0045] Fig. 9 It is a power cycle control flow chart provided in an embodiment of the present application.

[0046] Fig.10 It is a schematic diagram of temperature change of power cycle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0048] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0049] The terms "first" and "second" in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of the objects. For example, a first response message and a second response message are used to distinguish different response messages rather than to describe a specific order of the response messages.

[0050] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0051] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. For example, multiple processing units refer to two or more processing units, etc.; multiple elements refer to two or more elements, etc.

[0052] Next, the technical solutions provided in the embodiments of the present application are introduced.

[0053] like Figure 1 As shown, the present application provides a method for online extraction of SiC MOSFET power cycle characteristic parameters, comprising:

[0054] Real-time extraction of SiC MOSFET device temperature after the power cycle test is started;

[0055] If the extracted device temperature reaches the set maximum point, the gate drive signal of the SiC MOSFET is turned off and the cooling of the SiC MOSFET is started. If the extracted device temperature drops to the set minimum point, the gate drive signal of the SiC MOSFET is turned on to perform the next power cycle.

[0056] Extracting characteristic parameter values ​​of each cycle in the cycle control process, wherein the characteristic parameters include the on-state voltage drop, the drain current when turned on, and the Miller platform voltage of the SiC MOSFET;

[0057] Calculate the threshold voltage of SiC MOSFET by extracting the Miller platform voltage and drain current during turn-on.

[0058] The relationship between the threshold voltage and the number of power cycles, and the relationship between the on-state voltage drop and the number of power cycles are fitted respectively, and the SiC MOSFET power cycle degradation parameter fitting model is obtained.

[0059] Preferably, the device temperature of the SiC MOSFET is a case temperature of the SiC MOSFET.

[0060] Preferably, the on-state voltage drop of the SiC MOSFET is the gate-source voltage sampled when the driving signal is turned on, and the Miller platform voltage is the gate driving voltage sampled when the SiC MOSFET enters the Miller platform.

[0061] Preferably, the threshold voltage of the SiC MOSFET is calculated by extracting the Miller platform voltage and the drain current when turned on, as follows:

[0062]

[0063] Among them, V th is the threshold voltage, V miller is the Miller platform voltage, S is the structural parameter of SiC MOSFET, I d is the drain current collected by the device during power cycling, I d0 and g m are the rated forward continuous drain current and transconductance of SiC MOSFET respectively.

[0064] Preferably, before fitting, a sliding average value is used to filter the array of threshold voltage and power cycle number and the array of on-state voltage drop and power cycle number.

[0065] Preferably, the SiC MOSFET power cycle degradation parameter fitting model includes:

[0066] V th (n)=a·exp(b·n)+c·exp(d·n)

[0067] V DS(ON) (n)=a·exp(b·n)+c·exp(d·n)

[0068] Among them, V th is the threshold voltage, V DS is the on-state voltage drop, n is the number of power cycles, a, b, c, d are fitting parameters, which are calculated and determined by actual sampling data.

[0069] Preferably, the method further includes: substituting the on-state voltage drop threshold for setting device failure into the power cycle degradation parameter fitting model to calculate the number of power cycles; and calculating the difference between the number of power cycles and the current number of power cycles as the remaining life of the SiC MOSFET.

[0070] Preferably, the method further comprises: obtaining the device temperature as T m The on-state voltage drop of the SiC MOSFET sampled at time T m is the midpoint between the set maximum and minimum temperature of the device; if the device temperature is T m When the on-state voltage drop of the SiC MOSFET sampled is greater than or equal to the set on-state voltage drop threshold of the device failure, a device failure warning is issued.

[0071] like Figure 2 As shown, the present application provides an online extraction system for SiC MOSFET power cycle characteristic parameters, including: a device temperature extraction module, a conduction voltage drop extraction module, a drain current extraction module, a gate drive module, a Miller platform voltage extraction module and a control module;

[0072] The device temperature extraction module is used to extract the device temperature of the SiC MOSFET in real time;

[0073] The on-state voltage drop extraction module is used to extract the drain-source voltage when the SiC MOSFET is turned on;

[0074] The drain current extraction module is used to extract the drain current when the SiC MOSFET is turned on;

[0075] The gate drive module is used to drive SiC MOSFETs of different models;

[0076] The Miller platform extraction module is used to sample the gate drive voltage when the SiC MOSFET enters the Miller platform to obtain the Miller platform voltage;

[0077] The control module is used to control each module using the method described above to achieve online extraction of characteristic parameters.

[0078] On-state voltage drop extraction module

[0079] When the device is turned on, the drain-source voltage is generally very small, but when the device is turned off, the drain-source voltage is very large, equal to the power supply voltage. Therefore, the on-state voltage drop extraction module needs to be consistent with the turn-on of the SiC MOSFET, working when the SiC MOSFET is turned on, and stopping working and isolating the high-voltage source when the SiC MOSFET is turned off.

[0080] In one embodiment of the present application, the module uses Figure 3 The current sensing amplifier shown is used to extract the on-state voltage V of the SiC MOSFET. DS(on) The voltage output of the current sense amplifier is proportional to the voltage drop across a very low value resistor, typically across a high current power rail, so the MOSFET drive signal can be detected. When the drive signal is on, the gate-source voltage V DS The sampling voltage at this time is also the on-state voltage V of the MOSFET. DS(on) The current sensing amplifier is consistent with the opening of the SiC MOSFET. It works when the SiC MOSFET is turned on, and stops working and isolates the high voltage source when the SiC MOSFET is turned off. The on-state voltage V DS(on) .

[0081] Drain Current Extraction Module

[0082] The drain current extraction module can use a Hall sensor connected in series in a power circulation circuit, or can be connected in series with a high-precision resistor to measure the voltage value across the resistor and then convert it into a current value.

[0083] In one embodiment of the present application, the drain current extraction module uses an indirect measurement method. Specifically, a high-precision resistor R is connected in series in the power loop. shunt , the resistance value has an accuracy error of less than 0.1%, and then use Figure 4 The isolated precision amplifier shown in the figure is used to extract the voltage value across the high-precision resistor and then convert it into the on-state current I of the SiC MOSFET. DThe output and input circuits of the isolated precision amplifier are separated by an isolation barrier with strong anti-electromagnetic interference performance, which improves the stability of the circuit and reduces crosstalk and the breakdown of the high-voltage side into the low-voltage side. The extracted voltage value divided by the value of the high-precision resistor is the value of the drain current.

[0084] Gate drive module

[0085] To ensure that the gate drive module can drive various types of SiC MOSFET, a large current drive solution is required, while also having negative voltage drive capabilities to adapt to the characteristics of SiC materials.

[0086] In one embodiment of the present application, the gate drive module adopts Figure 5 The gate driver shown is implemented as shown in FIG. The gate driver has an isolated driving capability of 4A current and a high dv / dt characteristic, which can meet the requirements of most different types of SiC MOSFETs.

[0087] In order to increase the reliability of the circuit system in the module, an isolated drive method can be used for electrical isolation. In the present application, the drive module can convert the zero voltage drive into a negative voltage drive through the combination of voltage stabilizing diodes (DZ1-DZ2) and capacitors (C1, R1).

[0088] In this embodiment, VCC2 can be set to 15V voltage, which is the driving voltage. R2 and R3 are driving resistors, which can be set to 10Ω and 2Ω respectively, and can be replaced according to the actual model. DZ1 is a 11.7V voltage-stabilizing diode, and DZ2 is a 3V voltage-stabilizing diode. When the drive is turned on, the voltage-stabilizing value of DZ1 and the forward conduction value of DZ2 are about 12V, then the voltage across the energy storage network connected in parallel by C1 and R1 is 3V, and the driving voltage V GS is 12V. C1 and R1 can be set to 47nF and 10kΩ. When the driver is turned off, since the voltage across the capacitor cannot change suddenly, the voltage difference between the left and right sides of C1 is 3V. At this time, V GS The voltage is -3V, realizing negative voltage drive. When R1 and C1 are replaced with 0Ω resistors, it is 0 voltage drive. In this case, when the drive is turned on, V GS The voltage is the voltage of VCC2, which is 15V. When the driver is turned off, V GS The voltage is 0V.

[0089] Miller Platform Extraction Module

[0090] In one embodiment of the present application, the Miller platform extraction module is as follows Figure 6 The differential circuit and comparison circuit shown are used to determine the moment when the SiC MOSFET enters the Miller platform. At this moment, the gate drive voltage is sampled, and the voltage value obtained by the sampling is the Miller platform voltage.

[0091] Figure 7 This is a schematic diagram of the MOSFET turning on, where V millier is the Miller platform voltage, the gate-source voltage V GS At the moment of opening, it rises first, then enters the Miller platform, rises again, and finally stabilizes. Figure 6 The differential circuit composed of R1, R2, R3, C1, and U1 is used to distinguish V GS The rising stage and the Miller platform stage are then compared with the set reference threshold voltage through the comparison circuit composed of U3 and R4, and the corresponding pulse signal is output to achieve isolation and power amplification through the digital isolation chip. The obtained signal VOUT1 is used to control the PMOS tube Q1 of the voltage sampling circuit to perform Miller platform voltage sampling. The digital isolation chip U2 can achieve signal isolation and increase the driving ability of the signal, so that the signal has the ability to drive the PMOS tube Q1 to control the conduction of the sampling circuit.

[0092] The specific working process is: when V GS When it rises, VOUT1 is high, PMOS tube Q1 is turned off, and the sampling circuit output voltage VOUT2 is 0; when V GS When entering the Miller platform, VOUT1 is low, the PMOS tube Q1 is turned on, and the sampling circuit output voltage VOUT2 is the gate-source voltage V GS , at this time VGS is the Miller platform voltage V millier ; When V GS When it rises again, VOUT1 is at a high level and the PMOS tube Q1 is turned off.

[0093] Device temperature extraction module

[0094] The present application is implemented by using a thermocouple that is in close contact with the tube shell of the SiC MOSFET device, and the extracted temperature signal is transmitted to the control module using serial communication.

[0095] In one embodiment of the present application, the device temperature extraction module uses a thermocouple PT1000 platinum resistance sensor, and then uses Figure 8 The RTD digital converter shown converts the temperature signal into a digital signal. The temperature signal can be converted into an electrical signal for data monitoring and processing.

[0096] Control Module

[0097] The control module is used to control the input signal of the gate drive module. Specifically, the temperature information transmitted by the temperature extraction module is used to control the opening and closing of the drive signal. After the temperature cycle test is started, when the tube shell temperature of the SiC MOSFET device reaches the set highest point, the drive signal is turned off and the cooling fan is turned on. When the tube shell temperature drops to the set lowest point, the drive signal is turned on and the process is cyclically controlled. At the same time, the control module records the number of cycles and the characteristic standard parameters collected in each cycle, and forms a fitting curve to predict the life and analyze the reliability of the SiC MOSFET undergoing the power cycle test.

[0098] In one embodiment of the present application, the control module can be controlled by a control unit such as STM32, FPGA, etc. The collected conduction voltage drop, drain current, Miller platform voltage, and device temperature are stored and processed, and the temperature information transmitted by the temperature extraction module is used to control the opening and closing of the drive signal. When the tube shell temperature of the SiC MOSFET device reaches the set highest point, the drive signal is turned off and the cooling fan is turned on. When the tube shell temperature drops to the set lowest point, the drive signal is turned on and the process is cyclically controlled. At the same time, the control module forms a record of the number of cycles and the characteristic standard parameters collected in each cycle. At the same time, the data is transmitted to the host computer for the operator to check and inspect.

[0099] like Fig. 9 Shown is a flow chart of power cycle control performed by the system of the present application. Fig.10 Schematic diagram of temperature change during power cycle. max and T min are the shell temperatures T set during the experiment. c The maximum and minimum values ​​reached; T m To measure V DS(on) The corresponding temperature value is equal to T max and T min The average value of the sum; V DS(on) is the on-state voltage drop between the drain and source of the SiC MOSFET device; V DS(on)th is the set device failure threshold, which is generally equal to the value corresponding to a 20% change in the initial value.

[0100] After the system initialization configuration is completed, turn on the power supply, and control the drive module to output a high voltage through the control module to turn on the device. Under the action of the drain load current, the device gradually heats up. At this time, it is necessary to continuously detect the device's shell temperature. When the temperature reaches the highest temperature set by the program, control the drive module to output a low voltage to turn off the device. At the same time, turn on the cooling fan to quickly cool the device. When the temperature drops to the set minimum temperature, turn on the drive voltage again for the next power cycle. This cycle repeats until the device fails and the experiment ends. Fig.10 Medium V GS is the gate drive voltage, which is equal to the output voltage of the driver board and is used to control the switching state of the SiC MOSFET device. During each power cycle, the device's on-state voltage drop needs to be measured at a fixed temperature value when the device is in the on-state.

[0101] In the embodiment of the present application, after power cycling, the threshold voltage V th and the on-state voltage drop V DS(on) An array with the number of power cycles n.

[0102] In the embodiment of the present application, the two sets of array data are first filtered using a sliding average. Sliding average filtering is a data processing method that can smooth data. In this embodiment, the number of cycles is incremented and three consecutive threshold voltages V are taken. th and the on-state voltage drop V DS(on) Each data point forms a queue, and the queue length is always fixed at 3. When a new data point is sampled, the entire queue moves forward one step while keeping the queue length unchanged. After each move, the average value of the queue is calculated as the output. That is, the average value of the queues with a cycle number of 2, 3, and 4 is taken as the value when n is 3; the average value of the queues with a cycle number of 3, 4, and 5 is taken as the value when n is 4, and so on.

[0103] In the embodiment of the present application, a new threshold voltage V is formed after filtering. th and the on-state voltage drop V DS(on) The nonlinear model is fitted to the new two groups of arrays with the number of cycles n, and then the formula of the fitting curve is obtained, that is, the SiC MOSFET power cycle degradation parameter fitting model is established, which can be used to predict its device life.

[0104] In the examples of the present application, the selected model is a double exponential model.

[0105] It can be understood that the detailed functional implementation of each of the above-mentioned units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0106] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method, which will not be repeated here.

[0107] Based on the method in the above embodiment, an embodiment of the present application provides an electronic device, which may include: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. The processor may call the logic instructions in the memory to execute the method in the above embodiment.

[0108] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application.

[0109] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0110] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0111] It is understandable that the processor in the embodiment of the present application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0112] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0113] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions may be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state disk (SSD)), etc.

[0114] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0115] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for online extraction of SiC MOSFET power cycle characteristic parameters, characterized in that: include: Real-time extraction of SiC MOSFET device temperature after the power cycle test is started; If the extracted device temperature reaches the set maximum point, the gate drive signal of the SiC MOSFET is turned off and the cooling of the SiC MOSFET is started. If the extracted device temperature drops to the set minimum point, the gate drive signal of the SiC MOSFET is turned on to perform the next power cycle. Extracting characteristic parameter values ​​of each cycle in the cycle control process, wherein the characteristic parameters include the on-state voltage drop, the drain current when turned on, and the Miller platform voltage of the SiC MOSFET; Calculate the threshold voltage of SiC MOSFET by extracting the Miller platform voltage and drain current during turn-on. The relationship between the threshold voltage and the number of power cycles, and the relationship between the on-state voltage drop and the number of power cycles are fitted respectively, and the SiC MOSFET power cycle degradation parameter fitting model is obtained.

2. The extraction method according to claim 1, characterized in that The device temperature of the SiC MOSFET is the case temperature of the SiC MOSFET.

3. The extraction method according to claim 1, characterized in that The on-state voltage drop of the SiC MOSFET is the gate-source voltage sampled when the drive signal is turned on, and the Miller platform voltage is the gate drive voltage sampled when the SiC MOSFET enters the Miller platform.

4. The extraction method according to claim 1, characterized in that The threshold voltage of SiC MOSFET is calculated by extracting the Miller platform voltage and the drain current when it is turned on, as follows: Among them, V th is the threshold voltage, V miller is the Miller platform voltage, S is the structural parameter of SiC MOSFET, I d is the drain current collected by the device during power cycling, I d0 and g m are the rated forward continuous drain current and transconductance of SiC MOSFET respectively.

5. The extraction method according to claim 1, characterized in that Before fitting, the arrays of threshold voltage and power cycle number and the arrays of on-state voltage drop and power cycle number are filtered using a sliding average.

6. The extraction method according to claim 1, characterized in that The SiC MOSFET power cycle degradation parameter fitting model includes: V th (n)=a·exp(b·n)+c·exp(d·n) V DS(ON) (n)=a·exp(b·n)+c·exp(d·n) Among them, V th is the threshold voltage, V DS is the on-state voltage drop, n is the number of power cycles, and a, b, c, j are fitting parameters, which are calculated and determined by actual sampling data.

7. The extraction method according to any one of claims 1 to 6, characterized in that The method further includes: Substitute the on-state voltage drop threshold of the set device failure into the power cycle degradation parameter fitting model to calculate the number of power cycles; The difference between the number of power cycles and the current number of power cycles is calculated as the remaining life of the SiC MOSFET.

8. The extraction method according to any one of claims 1 to 6, characterized in that The method further includes: Get the device temperature as T m The on-state voltage drop of the SiC MOSFET sampled at time T m The midpoint between the set maximum point and the set minimum point of the device temperature; If the device temperature is T m When the on-state voltage drop of the SiC MOSFET sampled is greater than or equal to the set on-state voltage drop threshold of the device failure, a device failure warning is issued.

9. A SiC MOSFET power cycle characteristic parameter online extraction system, characterized in that: include: Device temperature extraction module, on-state voltage drop extraction module, drain current extraction module, gate drive module, Miller platform voltage extraction module and control module; The device temperature extraction module is used to extract the device temperature of the SiC MOSFET in real time; The on-state voltage drop extraction module is used to extract the drain-source voltage when the SiC MOSFET is turned on; The drain current extraction module is used to extract the drain current when the SiC MOSFET is turned on; The gate drive module is used to drive SiC MOSFETs of different models; The Miller platform extraction module is used to sample the gate drive voltage when the SiC MOSFET enters the Miller platform to obtain the Miller platform voltage; The control module is used to control each module by adopting the method according to any one of claims 1 to 8 to realize online extraction of characteristic parameters.

10. The extraction system according to claim 9, characterized in that The drain current extraction module includes: a high-precision resistor and an isolated sampling amplifier; The high-precision resistor has an accuracy error of less than 0.1%, and is connected in series between the gate and the ground point of the SiC MOSFET; The isolation sampling amplifier is used to isolate the power supply at the power end from the power supply signal at the control end, measure the voltage across the high-precision resistor when the SiC MOSFET is turned on, and send it to the controller to calculate the drain current when the SiC MOSFET is turned on.

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