Method and system for calculating turn-on loss of reverse recovery model based on diffusion capacitance

Abstract

The invention discloses a diffusion capacitance-based reverse recovery model turn-on loss calculation method and system, and the method comprises the steps: extending the junction capacitance range of a SiC MOSFET through combining the diffusion capacitance and a three-capacitor model, and can more accurately describe the reverse recovery characteristic of a medium-voltage SiC MOSFET, and achieve the simulation precision of the model on the actual device behavior. And a solid foundation is provided for subsequent analysis and optimization. By solving the linearized reverse recovery model, the method can obtain voltage and current waveforms in the reverse recovery process of the SiC MOSFET. The waveforms are key data for evaluating the turn-on loss and directly reflect energy conversion and loss conditions of a device in the turn-on and turn-off process, and the method can further calculate the heat loss of the medium-voltage SiC MOSFET in the turn-on process according to the reversely recovered voltage and current waveforms.

Description

Technical Field

[0001] The present invention belongs to the field of electronic power technology, and relates to a turn-on loss calculation method, system, device and medium of a reverse recovery model of a medium-voltage silicon carbide MOSFET based on diffusion capacitance. Background Art

[0002] The power electronics of medium-voltage distribution networks (10 to 35 kV) has always been a trend. Power electronics equipment for medium-voltage distribution networks includes energy storage, static var generators (STATCOM), energy routers, etc. In order to connect existing low-voltage power devices to the medium-voltage power grid, traditional implementation solutions are generally based on 50 Hz power frequency transformers or MMC, CHB cascade topologies built with silicon IGBTs, resulting in a large volume and a large number of devices. Medium-voltage silicon carbide (SiC) MOSFET is a metal-oxide-semiconductor field-effect transistor based on silicon carbide material. As an advanced power semiconductor device, it has the characteristics of high breakdown electric field, high saturated electron drift velocity, high thermal conductivity, etc., and is suitable for the manufacture of high-temperature, high-frequency, radiation-resistant and high-power devices. SiC MOSFET has broad application prospects in new energy vehicles, industrial power supplies, rail transportation, smart grids and other fields. The development of medium-voltage silicon carbide (SiC) MOSFET can effectively solve the above problems. Its withstand voltage can reach 15 kV, and it can use a smaller number of devices to build power electronic equipment directly connected to the medium-voltage distribution network, reduce the number of active and passive devices, increase the power density of the equipment, and further improve the power electronics level of the power grid.

[0003] In the process of designing power electronic equipment, the calculation of the conduction loss and switching loss of power devices is very important because it can determine the choice of switching frequency and the design of the heat sink. Conduction loss is generally easier to measure, but switching loss must focus on the switching process of the power device. At present, academia and industry lack accurate modeling of the switching process of medium-voltage SiC MOSFETs, especially the lack of understanding of the turn-on loss caused by the reverse recovery of the body diode. This leads to inaccurate calculation of the turn-on loss of the device when the equipment is working, over-design or under-design occurs in the design process, and the excellent performance of the medium-voltage SiC MOSFET cannot be fully and reliably exerted. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a turn-on loss calculation method, system, device and medium for a reverse recovery model of SiC MOSFET based on diffused capacitance. The model and the solution results can effectively and accurately reflect the reverse recovery phenomenon of the MOSFET body diode during the turn-on process, and are used for the calculation of turn-on loss, which is beneficial to the parameter design and thermal design of power electronic converters.

[0005] The present invention is achieved through the following technical solutions: A method for calculating turn-on loss based on a reverse recovery model of diffusion capacitance includes: After extending the range of SiC MOSFET junction capacitance based on diffusion capacitance and three-capacitor model, the reverse recovery model of medium-voltage SiC MOSFET is obtained. Linearize and approximate the reverse recovery model of medium voltage SiC MOSFET; Based on the reverse recovery model of medium-voltage SiC MOSFET after linearization and approximation, the reverse recovery turn-on process of SiC MOSFET is solved to obtain the reverse recovery voltage and current waveforms. Based on the reverse recovery voltage and current waveforms, the heat loss of the medium voltage SiC MOSFET during the turn-on process is obtained.

[0006] Preferably, the specific process of establishing the three-capacitor model is: Gate-source capacitance C based on SiC MOSFET gs , gate-drain capacitance C gd and drain-source capacitance C ds , the three-capacitor model established.

[0007] Preferably, the specific process of establishing the reverse recovery model of the medium voltage silicon carbide MOSFET is as follows: Based on the diffusion capacitance, the three-capacitor model is improved so that the gate-drain capacitance of the PN junction in the three-capacitor model during forward conduction is C gd and drain-source capacitance C ds The gate-source capacitance is larger than the capacitance of the PN junction when it is reverse biased. C gs remains unchanged, thus obtaining the reverse recovery model of the medium voltage SiC MOSFET.

[0008] Preferably, the reverse recovery model of the medium voltage silicon carbide MOSFET is expressed as:

[0009] in, v gs , v gd , v ds is the voltage of each port of the device, i ch is the device channel current, function f Represents the static characteristics of the device, i d is the device drain current; vD and i D are the voltage and current of the freewheeling diode, respectively, and the function g Represents the static output characteristics of the diode; V DC is the DC bus voltage, V DD is the driving voltage, R g is the driving resistor, I L is the inductor current, C gs , C gd , C ds is the device junction capacitance, and the subscripts l and h represent the capacitance values ​​of the lower tube device and the upper tube diode respectively; L g , L s , L loop They are the device gate parasitic inductance, source parasitic inductance and commutation circuit parasitic inductance.

[0010] Preferably, the reverse recovery model of the medium voltage silicon carbide MOSFET is linearized and approximated, and the specific process is: The characteristics of the SiC MOSFET channel and body diode in the reverse recovery model of the medium-voltage SiC MOSFET are linearized and approximated. gs , C gd and C ds Approximately two constant capacitances are calculated based on the diffusion capacitance, making the gate-source C of the MOSFET gs Short circuit, C gd and C ds The junction capacitance C of the body diode is obtained by parallel connection j ; The device's C gs , C gd and C ds The specific calculation formula for approximating two constant capacitances is:

[0011]

[0012]

[0013] ; in, ich is the channel current of SiC MOSFET in saturation region, g m is the transconductance of the device, v gs and V th are the gate-source voltage and turn-on threshold voltage of the device respectively; i D is the body diode current, V f and R D are the on-state voltage drop and on-state resistance of the body diode, respectively. V ds (- V D ) is the drain-source voltage of the MOSFET or body diode, C gs , C gd , C ds are the gate-source capacitance, gate-drain capacitance and drain-source capacitance of the device respectively, V b is the boundary voltage of capacitance change; C gd1 , C ds1 They are V ds Greater than V b The gate-drain capacitance and drain-source capacitance are C gd2 , C ds2 They are V ds Less than V b The gate-drain capacitance and drain-source capacitance at V ds <0 body diode conduction part, C gd2 >> C gd1 , C ds2 >> C ds1 , C j is the junction capacitance of the body diode, C j1 = C gd1 + C ds1 , C j2 =C gd2 + C ds2 , C j1 for V ds Greater than V b The junction capacitance of the body diode is C j2 for V ds Less than V b The junction capacitance of the body diode at the time.

[0014] Preferably, the reverse recovery turn-on process of SiCMOSFET is solved based on the reverse recovery model of the medium voltage silicon carbide MOSFET after linearization approximation processing, and the specific process is: The voltage and current waveforms in the time domain are analyzed and solved for each stage of the turn-on process according to the state of the SiC MOSFET, including: t 0 Moment: Before the lower SiC MOSFET of the device is turned on, the body diode of the upper tube is freewheeling by the inductor I L , the forward voltage of the body diode is V f + I L R D , the drain-source voltage of the lower tube is V dc + V f + I L R D , the gate-source voltage of the lower tube is v gs Maintain the shutdown level for V EE , denoted as t 0 time, in V f and R D They are the on-state voltage drop and on-state resistance of the body diode respectively; t 0 ~ t 1 Stage: In t 0 Moment, driving voltage VDD rises to the turn-on level, the gate-source voltage of the device is v gs The gate-source voltage of the device starts to rise. v gs ( t ) is less than V th , no current flows through the lower tube channel, then

[0015] In the formula τ iss1 = R g ( C gs + C gd1 ), R g is the driving resistor, V EE is the gate-source turn-off voltage, C gd1 for V ds Greater than V b The gate-drain capacitance at ; when v gs ( t ) to reach V th This stage ends when t 1 time, then t 1 = t 0 + τ iss1 ln(( V DD - V EE ) / ( V DD - V th )); V th is the turn-on threshold voltage; t 1 ~ t 2 Stage: The lower tube current rises, the body diode current decreases, the corresponding forward voltage decreases, and the reverse recovery process begins, which is recorded as t 2 moment, that is, the junction capacitance of the body diode C jThe displacement current is generated,

[0016] in

[0017] Where: g m is the transconductance of the device, i D (t) is the time function of the body diode current; t 2 ~ t 3 Stage: The diode current is 0, and the channel current flowing through the junction capacitance causes the voltage to change.

[0018] in, i Cj is the junction capacitance C j The current flowing through v D ( t ) down to - V b When the diode junction capacitance is C j2 Down to C j1 , denoted as t 3 time, i Cj (t) is the junction capacitance C j The time function of the current flowing through it; v D ( t ) is the voltage-time function of the freewheeling diode; t 3 ~ t 4 Stage: Miller platform stage, the voltage of the lower tube decreases and the driving current i g Need to keep down C gd Charge, ; when v ds ( t ) down to V b When the junction capacitance of the lower tube changes,

[0019] when v ds ( t ) decreases to 0, the stage ends and is recorded as t 4 time; t 4 ~ t 5 Stage: The opening process is completed. v gs ( t ) continues to rise exponentially, recorded as t 5 At this moment, the time constant changes to τ iss2 = R g ( C gs + C gd2 ),but

[0020] So as to obtain voltage waveforms at different stages v ds ( t ) and current waveform i ch ( t ) in the time domain.

[0021] Preferably, the heat loss of the medium voltage SiC MOSFET during the turn-on process is obtained according to the reverse recovery voltage and current waveforms. , the calculation formula is: .

[0022] A turn-on loss analysis system of a reverse recovery model of a medium voltage silicon carbide MOSFET based on diffusion capacitance, comprising: Model building module, linearization approximation processing module, voltage and current waveform solution module, heat loss calculation module, The model building module is used to obtain a reverse recovery model of a medium voltage silicon carbide MOSFET after extending the range of the SiC MOSFET junction capacitance based on the diffusion capacitance and the three-capacitor model; The linearization approximation processing module is used to perform linearization approximation processing on the reverse recovery model of the medium voltage silicon carbide MOSFET; The voltage and current waveform solving module is used to solve the turn-on process of reverse recovery of SiC MOSFET based on the reverse recovery model after linearization approximation processing to obtain the reverse recovery voltage and current waveform; The heat loss calculation module is used to obtain the heat loss of the medium voltage SiC MOSFET during the turn-on process according to the reverse recovery voltage and current waveforms.

[0023] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the turn-on loss calculation method based on the reverse recovery model of the diffusion capacitor are implemented.

[0024] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for calculating turn-on loss based on a reverse recovery model of diffusion capacitance are implemented.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses a reverse recovery model of a medium-voltage silicon carbide MOSFET based on diffused capacitance. Aiming at the switching characteristics of medium-voltage SiC MOSFET devices at higher voltages, the reverse recovery current model based on the traditional low-voltage Si / SiC power electronic devices during the opening process is improved. The device port characteristics are described by a unified junction capacitance, and the waveform of the reverse recovery current is derived, so that the heat loss of the medium-voltage SiC MOSFET during the opening process can be accurately calculated. After extending the range of SiC MOSFET junction capacitance based on diffused capacitance and three-capacitor models, the reverse recovery model of the medium-voltage silicon carbide MOSFET is obtained, which improves the reverse recovery current model based on the traditional low-voltage Si / SiC power electronic devices during the opening process. By combining diffused capacitance and three-capacitor models to extend the range of SiC MOSFET junction capacitance, this method can more accurately describe the reverse recovery characteristics of the medium-voltage SiC MOSFET and improve the simulation accuracy of the model for the actual device behavior, providing a solid foundation for subsequent analysis and optimization. By solving the linearized reverse recovery model, the method can obtain the voltage and current waveforms during the reverse recovery process of the SiC MOSFET. These waveforms are key data for evaluating turn-on losses because they directly reflect the energy conversion and loss of the device during the switching process. Based on the reverse recovery voltage and current waveforms, this method can further calculate the heat loss of the medium-voltage SiC MOSFET during the turn-on process. Heat loss is an important parameter in device reliability assessment because it is directly related to the operating temperature and life of the device. By accurately calculating the heat loss, it can provide strong support for the thermal design of the device and ensure that the device can maintain stable performance under harsh working conditions. The reverse recovery model of the medium-voltage silicon carbide MOSFET and the solution results can effectively and accurately reflect the reverse recovery phenomenon of the MOSFET body diode during the turn-on process, and are used for the calculation of turn-on losses, which is beneficial to the parameter design and thermal design of power electronic converters. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A three-capacitor model of diffusion capacitance is considered for the present invention; Figure 2 is the linearized approximate model of the SiC MOSFET of the present invention; Figure 3 A process experimental circuit for opening the present invention; Figure 4 This is the SiC MOSFET double pulse test platform circuit of the present invention.

[0027] Figure 5 This is the turn-on process waveform obtained by analytical calculation in the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] A method for calculating turn-on loss based on a reverse recovery model of diffusion capacitance includes: After extending the range of SiC MOSFET junction capacitance based on diffusion capacitance and three-capacitor model, the reverse recovery model of medium-voltage SiC MOSFET is obtained. like Figure 1 As shown, the specific process of establishing the three-capacitor model is: Gate-source capacitance C based on SiC MOSFET gs , gate-drain capacitance C gd and drain-source capacitance C ds , the three-capacitor model established.

[0031] The specific process of establishing the reverse recovery model of the medium voltage SiC MOSFET is as follows: Based on the diffusion capacitance, the three-capacitor model is improved so that the C gd and C ds The capacitance of the PN junction is larger than that when it is reverse biased, C gs remains unchanged, thus obtaining the reverse recovery model of the medium voltage SiC MOSFET.

[0032] The classic three-capacitor model includes the C gs , C gd and C ds , but generally only consider v ds >0. The present invention extends the range of SiC MOSFET junction capacitance to a certain extent: when the body diode is turned on, the PN junction is subjected to a forward voltage. According to semiconductor theory, the PN junction has a capacitance effect caused by the accumulation of minority carriers, which is called diffusion capacitance.

[0033] The capacitance corresponding to the PN junction is mainly composed of the gate-drain capacitance of the MOSFET ( Cgd ) and drain-source capacitance ( C ds ) and the gate-source capacitance ( C gs ) is a gate-source equal structure capacitance, which is almost independent of drain-source voltage changes. Therefore, in the established reverse recovery model of medium-voltage SiC MOSFET, the PN junction forward conduction C gd and C ds It is larger than the capacitance of the PN junction when it is reverse biased (mainly determined by the barrier capacitance), and C gs Almost unchanged.

[0034] The reverse recovery model of the medium voltage SiC MOSFET is expressed as:

[0035] in, v gs , v gd , v ds is the voltage of each port of the device, i ch is the device channel current, function f Represents the static characteristics of the device, i d is the device drain current; v D and i D are the voltage and current of the freewheeling diode, respectively, and the function g Represents the static output characteristics of the diode; V DC is the DC bus voltage, V DD is the driving voltage, R g is the driving resistor, I L is the inductor current, C gs , C gd , C ds is the device junction capacitance, and the subscripts l and h represent the capacitance values ​​of the lower tube device and the upper tube diode respectively; L g , L s , L loop The device gate parasitic inductance, source parasitic inductance and commutation circuit parasitic inductance are measured respectively.

[0036] The characteristics of the SiC MOSFET channel and body diode in the reverse recovery model of the medium voltage SiC MOSFET are linearized and approximated, such as Figure 2 As shown, the specific process is: The characteristics of the SiC MOSFET channel and body diode are linearized and approximated, and the C gs , C gd and C ds Approximately two constant capacitances are calculated based on the diffusion capacitance, making the gate-source C of the MOSFET gs Short circuit, C gd and C ds The junction capacitance C of the body diode is obtained by parallel connection j ; The device's C gs , C gd and C ds The specific calculation formula for approximating two constant capacitances is:

[0037]

[0038]

[0039]

[0040] in, i ch is the channel current of SiC MOSFET in saturation region, g m is the transconductance of the device, v gs and V th are the gate-source voltage and turn-on threshold voltage of the device respectively; i D is the body diode current, V f and R D are the on-state voltage drop and on-state resistance of the body diode, respectively. V ds (- V D ) is the drain-source voltage of the MOSFET or body diode, C gs , C gd , C dsare the gate-source capacitance, gate-drain capacitance and drain-source capacitance of the device respectively, V b is the boundary voltage of capacitance change; C gd1 , C ds1 They are V ds Greater than V b When the gate-drain capacitance and drain-source capacitance are C gd2 , C ds2 They are V ds Less than V b The gate-drain capacitance and drain-source capacitance at V ds <0 part of the body diode conduction, C gd2 >> C gd1 , C ds2 >> C ds1 , C j is the junction capacitance of the body diode.

[0041] The reverse recovery turn-on process of SiC MOSFET is solved based on the reverse recovery model after linearization approximation, and the reverse recovery voltage and current waveforms are obtained; The reverse recovery process is solved according to the proposed three-capacitor model. The reverse recovery process is described by differential equations, which can be solved using various differential equation solving methods, including various analytical solutions (such as piecewise linear methods) and numerical solutions (such as Runge-Kutta method, numerical calculation software, circuit simulation software, etc.), and some possible approximate processing.

[0042] The switching process is divided into several stages according to the state of SiC MOSFET, such as Figure 5 As shown, the voltage and current waveforms in the time domain are analytically solved for each stage.

[0043] (a) Phase 0 (~ t 0 ): In the double-pulse half-bridge circuit, before the lower SiC MOSFET is turned on, the body diode of the upper SiC MOSFET is the inductor freewheeling current. Assume that the inductor current is I L , the inductance is large enough, and it is considered as a constant current source in the following analysis. At this time, the forward voltage of the diode is V f +I L R D , the drain-source voltage of the lower tube is V dc + V f + I L R D . Lower tube gate-source voltage v gs Maintain at shutdown level V EE .

[0044] (b) Phase 1 t 0 ~ t 1 ): t 0 At this moment, the driving voltage rises to the turn-on level V DD , down pipe v gs began to rise. v gs ( t ) is less than V th , so no current flows through the lower tube channel.

[0045] In the formula τ iss1 = R g ( C gs + C gd1 ), R g is the driving resistance. v gs ( t ) to reach V th This phase ends when t 1 = t 0 + τ iss1 ln(( V DD - V EE ) / ( V DD - V th )).

[0046] (c) Phase 2 ( t 1 ~ t 2 ): At this time, the lower tube current increases, the diode current decreases, and the corresponding forward voltage decreases. It is believed that the reverse recovery process has begun, that is, the larger C j The displacement current generated by the voltage change. Ignoring the influence of parasitic inductance, at this time v gs It still rises exponentially. According to Kirchhoff's law, the node current equation is:

[0047] Solved

[0048] in

[0049] v D ( t ) decreases slowly according to formula (2). C gd1 and C ds1 Small, ignoring the displacement current caused by the voltage change on the lower tube capacitor, it is assumed that the drain current i d Equal to the channel current i ch .when i D ( t ) drops to 0 V, and enters the next stage, which is recorded as t 2 .

[0050] (d) Stage 3 ( t 2 ~ t 3 ): In this stage, the diode current is 0, and all the channel current flows through the junction capacitance, causing the voltage to change.

[0051] when v D ( t ) down to - V b When the diode junction capacitance is C j2 Down to C j1 , record the time ast 3 , entering the lower tube voltage drop stage.

[0052] (e) Stage 4 ( t 3 ~ t 4 ): This stage is the Miller platform stage. The displacement current on the lower tube capacitor cannot be ignored. In order to reduce the voltage of the lower tube, the driving current i g Need to keep the pipe C gd Charging. Yes

[0053] This system of equations is a typical first-order linear ordinary differential equation system, and its analytical solution is easy to find. v ds ( t ) down to V b When the junction capacitance of the lower tube changes, the above equation becomes

[0054] when v ds ( t ) decreases to 0, the stage ends and the time is recorded as t 4 .

[0055] (f) Stage 4 ( t 4 ~ t 5 ): The switching process is basically completed. v gs ( t ) continues to increase exponentially, and the time constant at this time changes to τ iss2 = R g ( C gs + C gd2 ),have

[0056] According to the above calculation, the MOSFET is turned on. v ds ( t ) and i ch ( t ) can be solved to obtain the time domain analytical expression, and the actual heat loss during the opening process can be expressed as

[0057] (2) SiC MOSFET reverse recovery current analysis. Based on the model established in step (1), the reverse recovery current of SiC MOSFET is analyzed, and the trend of reverse recovery current changing with circuit parameters is explained.

[0058] Take the double pulse circuit in Figure 4 as an example for analysis. In the double pulse circuit, the lower tube is a device, the gate source of the upper tube is short-circuited and used as a diode, the inductor is connected in parallel at both ends of the upper tube, and the reverse recovery current is defined as the sum of the current of the diode and its junction capacitance. Reverse recovery occurs when the lower tube is turned on. Before that, the upper tube acts as a freewheeling diode to flow the current on the inductor. When the lower tube is turned on, the current is gradually commutated from the freewheeling diode to the device. In this process, according to the output characteristics of the diode, the forward conduction voltage drop of the diode decreases as the current decreases. This voltage change occurs at the junction capacitance ( C gd_h + C ds_h ), although the voltage change is very small (from below 10 volts to 0 volts), the displacement current is still significant due to the large junction capacitance at this time, which is the first part of the reverse recovery current, such as Figure 4 The reverse recovery current spike is shown.

[0059] When the diode is reverse loaded, C gd_h and C ds_h becomes smaller, the reverse pressure of the diode rises rapidly, and a certain displacement current is also generated, which is the second part of the reverse recovery current. This part is consistent with the existing reverse recovery model, such as Figure 4 The reverse recovery current platform is shown.

[0060] The larger the forward current before commutation, the larger the forward voltage drop of the diode, the larger the integral of the junction capacitance to the voltage change, and therefore the more obvious the reverse recovery phenomenon.

[0061] An analysis system for the turn-on loss of a reverse recovery model of a medium-voltage silicon carbide MOSFET based on diffused capacitance, a model building module, a linearization approximation processing module, a voltage and current waveform solving module, and a heat loss calculation module. The model building module is used to obtain a reverse recovery model of a medium voltage silicon carbide MOSFET after extending the range of the SiC MOSFET junction capacitance based on the diffusion capacitance and the three-capacitor model; The linearization approximation processing module is used to perform linearization approximation processing on the characteristics of the SiC MOSFET channel and body diode based on the reverse recovery model; The voltage and current waveform solving module is used to solve the turn-on process of reverse recovery of SiC MOSFET based on the reverse recovery model after linearization approximation processing to obtain the reverse recovery voltage and current waveform; The heat loss calculation module is used to obtain the heat loss of the medium voltage SiC MOSFET during the turn-on process according to the reverse recovery voltage and current waveforms.

[0062] An embodiment of the present invention provides a terminal device, which includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned dynamic scene image deblurring method are implemented; or when the processor executes the computer program, the functions of each module in the above-mentioned dynamic scene image deblurring system are implemented.

[0063] The computer program may be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to accomplish the present invention.

[0064] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0065] The processor may 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, discrete gate or transistor logic devices, discrete hardware components, etc.

[0066] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0067] If the module / unit integrated in the terminal device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0068] Based on such understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing related hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned dynamic scene image deblurring method can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc.

[0069] The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0070] In another embodiment of the present invention, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the turn-on loss calculation method of the reverse recovery model of the medium-voltage silicon carbide MOSFET based on the diffusion capacitor in the above embodiment.

[0071] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0072] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0073] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0074] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for calculating turn-on loss based on a reverse recovery model of diffusion capacitance, characterized in that: include, After extending the range of SiC MOSFET junction capacitance based on diffusion capacitance and three-capacitor model, the reverse recovery model of medium-voltage SiC MOSFET is obtained. Linearize and approximate the reverse recovery model of medium voltage SiC MOSFET; Based on the reverse recovery model of medium-voltage SiC MOSFET after linearization and approximation, the reverse recovery turn-on process of SiC MOSFET is solved to obtain the reverse recovery voltage and current waveforms. Based on the reverse recovery voltage and current waveforms, the heat loss of the medium voltage SiC MOSFET during the turn-on process is obtained.

2. The method for calculating turn-on loss based on the reverse recovery model of diffusion capacitance according to claim 1, characterized in that: The specific process of establishing the three-capacitor model is as follows: Gate-source capacitance C based on SiC MOSFET gs , gate-drain capacitance C gd and drain-source capacitance C ds , the three-capacitor model established.

3. The method for calculating turn-on loss based on the reverse recovery model of diffusion capacitance according to claim 2, characterized in that: The specific process of establishing the reverse recovery model of the medium voltage SiC MOSFET is as follows: Based on the diffusion capacitance, the three-capacitor model is improved so that the gate-drain capacitance of the PN junction in the three-capacitor model during forward conduction is C gd and drain-source capacitance C ds The gate-source capacitance is larger than the capacitance of the PN junction when it is reverse biased. C gs remains unchanged, thus obtaining the reverse recovery model of the medium voltage SiC MOSFET.

4. The method for calculating turn-on loss based on the reverse recovery model of diffusion capacitance according to claim 1, characterized in that: The reverse recovery model of the medium voltage silicon carbide MOSFET is expressed as: in, v gs , v gd , v ds is the voltage of each port of the device, i ch is the channel current of the device, function f Represents the static characteristics of the device, i d is the device drain current; v D and i D are the voltage and current of the freewheeling diode, respectively, and the function g Represents the static output characteristics of the diode; V DC is the DC bus voltage, V DD is the driving voltage, R g is the driving resistor, I L is the inductor current, C gs , C gd , C ds is the junction capacitance of the device, and the subscripts l and h represent the capacitance values ​​of the lower diode and upper diode of the device, respectively; L g , L s , L loop They are the gate parasitic inductance, source parasitic inductance and commutation circuit parasitic inductance of the device.

5. The method for calculating turn-on loss based on the reverse recovery model of diffusion capacitance according to claim 1, characterized in that: The reverse recovery model of the medium voltage SiC MOSFET is linearized and approximated. The specific process is as follows: The characteristics of the SiC MOSFET channel and body diode in the reverse recovery model of the medium-voltage SiC MOSFET are linearized and approximated. gs , C gd and C ds Approximately, the calculation is done as two constant capacitances, based on the diffusion capacitance, so that the C of the MOSFET gs Short circuit, C gd and C ds The junction capacitance C of the body diode is obtained by parallel connection j ; The device's C gs , C gd and C ds The specific calculation formula for approximating two constant capacitances is: ； in, i ch is the channel current of the SiC MOSFET device in the saturation region, g m is the transconductance of the device, v gs and V th are the gate-source voltage and turn-on threshold voltage of the device respectively; i D is the body diode current, V f and R D are the on-state voltage drop and on-state resistance of the body diode, respectively. V ds (- V D ) is the drain-source voltage of the MOSFET or body diode, C gs , C gd , C ds are the gate-source capacitance, gate-drain capacitance and drain-source capacitance of the device respectively, V b is the boundary voltage of capacitance change; C gd1 , C ds1 They are V ds Greater than V b When the gate-drain capacitance and drain-source capacitance are C gd2 , C ds2 They are V ds Less than V b The gate-drain capacitance and drain-source capacitance at V ds <0 part of the body diode conduction, C gd2 >> C gd1 , C ds2 >> C ds1 , C j is the junction capacitance of the body diode, C j1 = C gd1 + C ds1 , C j2 = C gd2 + C ds2 , C j1 for V ds Greater than V b The junction capacitance of the body diode is C j2 for V ds Less than V b The junction capacitance of the body diode at the time.

6. The method for calculating turn-on loss based on the reverse recovery model of diffusion capacitance according to claim 5, characterized in that: Based on the reverse recovery model of the medium-voltage silicon carbide MOSFET after linearization approximation, the turn-on process of the reverse recovery of the SiC MOSFET is solved. The specific process is as follows: The voltage and current waveforms in the time domain are analyzed and solved for each stage of the turn-on process according to the state of the SiC MOSFET, including: t Time 0: Before the lower SiC MOSFET of the device is turned on, the body diode of the upper tube is freewheeling by the inductor I L , the forward voltage of the body diode is V f + I L R D , the drain-source voltage of the lower tube is V dc + V f + I L R D , the gate-source voltage of the lower tube is v gs Maintain the shutdown level for V EE , denoted as t 0 time, in V f and R D They are the on-state voltage drop and on-state resistance of the body diode respectively; t 0~ t Stage 1: In t At time 0, the driving voltage V DD rises to the turn-on level, the gate-source voltage of the device is v gs The gate-source voltage of the device starts to rise. v gs ( t ) is less than V th , no current flows through the lower tube channel, then In the formula τ iss1 = R g ( C gs + C gd1 ), R g is the driving resistor, V EE is the gate-source turn-off voltage, C gd1 for V ds Greater than V b The gate-drain capacitance at ; when v gs ( t ) to reach V th This stage ends when t 1 moment, then t 1 = t 0 + τ iss1 ln(( V DD - V EE ) / ( V DD - V th )); V th is the turn-on threshold voltage; t 1~ t Stage 2: The lower tube current rises, the body diode current decreases, the corresponding forward voltage decreases, and the reverse recovery process begins, which is recorded as t 2 moment, that is, the junction capacitance of the body diode C j The displacement current is generated, in Where: g m is the transconductance of the device, i D (t) is the time function of the body diode current; t 2~ t Stage 3: The diode current is 0, and the channel current flowing through the junction capacitance causes the voltage to change. in, i Cj is the junction capacitance C j The current flowing through v D ( t ) down to - V b When the diode junction capacitance is C j2 Down to C j1 , denoted as t 3 moments, i Cj (t) is the junction capacitance C j The time function of the current flowing through it; v D ( t ) is the voltage-time function of the freewheeling diode; t 3~ t Stage 4: Miller platform stage, the voltage of the lower tube decreases and the driving current i g Need to keep down C gd Charge, ； when v ds ( t ) down to V b When the junction capacitance of the lower tube changes, when v ds ( t ) decreases to 0, the stage ends and is recorded as t 4 Moments; t 4~ t Stage 5: The opening process is completed. v gs ( t ) continues to rise exponentially, recorded as t At 5 seconds, the time constant changes to τ iss2 = R g ( C gs + C gd2 ),but So as to obtain the voltage waveform at different stages v ds ( t ) and current waveform i ch ( t ) in the time domain.

7. The method for calculating turn-on loss based on the reverse recovery model of diffusion capacitance according to claim 6, characterized in that: Based on the reverse recovery voltage and current waveforms, the heat loss of the medium voltage SiC MOSFET during the turn-on process is obtained. , the calculation formula is: 。 8. A turn-on loss analysis system of a reverse recovery model of a medium-voltage silicon carbide MOSFET based on diffused capacitance, based on the turn-on loss calculation method according to any one of claims 1 to 7, characterized in that: include, Model building module, linearization approximation processing module, voltage and current waveform solution module, heat loss calculation module, The model building module is used to obtain a reverse recovery model of a medium voltage silicon carbide MOSFET after extending the range of the SiC MOSFET junction capacitance based on the diffusion capacitance and the three-capacitor model; The linearization approximation processing module is used to perform linearization approximation processing on the characteristics of the SiC MOSFET channel and body diode based on the reverse recovery model; The voltage and current waveform solving module is used to solve the reverse recovery turn-on process of SiCMOSFET based on the reverse recovery model after linearization approximation processing to obtain the reverse recovery voltage and current waveform; The heat loss calculation module is used to obtain the heat loss of the medium voltage SiC MOSFET during the turn-on process according to the reverse recovery voltage and current waveforms.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method for calculating turn-on loss based on the reverse recovery model of diffusion capacitance as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating turn-on loss based on a reverse recovery model of diffusion capacitance as described in any one of claims 1 to 7 are implemented.

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