A method and system for calculating turn-on loss based on a reverse recovery model of diffused capacitance.

Abstract

This invention discloses a method and system for calculating turn-on losses based on a reverse recovery model using diffused capacitance. The method extends the junction capacitance range of SiC MOSFETs by combining diffused capacitance and a three-capacitor model. This approach more accurately describes the reverse recovery characteristics of medium-voltage SiC MOSFETs, improving the model's simulation accuracy of actual device behavior and providing a solid foundation for subsequent analysis and optimization. By solving the linearized reverse recovery model, this method obtains 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 during switching. Based on the reverse recovery voltage and current waveforms, this method can further calculate the heat loss of the medium-voltage SiC MOSFET during turn-on.

Description

Technical Field

[0001] This invention belongs to the field of electronic power technology and relates to a method, system, device and dielectric for calculating the turn-on loss of a medium-voltage silicon carbide MOSFET based on a diffused capacitance reverse recovery model. Background Technology

[0002] The electrification of medium-voltage distribution networks (10 to 35 kV) has been a long-standing trend. Medium-voltage distribution network power electronic equipment includes energy storage, static var generators (STATCOM), energy routers, etc. To connect existing low-voltage power devices to the medium-voltage grid, traditional solutions typically rely on 50 Hz power frequency transformers or silicon IGBTs in MMC / CHB cascaded topologies, resulting in large size and a large number of devices. Medium-voltage silicon carbide (SiC) MOSFETs are metal-oxide-semiconductor field-effect transistors based on silicon carbide material. As an advanced power semiconductor device, they feature high breakdown electric field, high saturation electron drift velocity, and high thermal conductivity, making them suitable for manufacturing high-temperature, high-frequency, radiation-resistant, and high-power devices. SiC MOSFETs have broad application prospects in new energy vehicles, industrial power supplies, rail transportation, and smart grids. The development of medium-voltage silicon carbide (SiC) MOSFETs can effectively solve the above problems. With a withstand voltage of up to 15 kV, power electronic equipment directly connected to the medium-voltage distribution network can be built with fewer devices, reducing the number of active and passive devices, increasing the power density of the equipment, and further improving the power electronics level of the power grid.

[0003] In the design of power electronic equipment, the calculation of conduction and switching losses of power devices is crucial, as it determines the selection of switching frequency and heat sink design. Conduction losses are generally easy to measure; however, switching losses require attention to the switching process of the power device. Currently, both academia and industry lack accurate modeling of the switching process of medium-voltage SiC MOSFETs, particularly regarding the insufficient understanding of turn-on losses caused by the reverse recovery of the body diode. This leads to inaccurate calculations of turn-on losses during device operation, resulting in over- or under-design during the design process, and preventing the full and reliable utilization of the superior performance of medium-voltage SiC MOSFETs. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method, system, device, and dielectric for calculating turn-on losses based on a reverse recovery model of a SiC MOSFET with diffused capacitance. This model and its 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 calculating turn-on losses, which is beneficial for the parameter design and thermal design of power electronic converters.

[0005] This invention is achieved through the following technical solution:

[0006] A method for calculating turn-on loss based on a reverse recovery model of diffused capacitance, comprising:

[0007] After extending the range of SiC MOSFET junction capacitance based on the diffusion capacitance and three-capacitor model, the reverse recovery model of medium-voltage silicon carbide MOSFET is obtained.

[0008] The reverse recovery model of medium-voltage silicon carbide MOSFET is linearized and approximated.

[0009] The reverse recovery model of the medium-voltage silicon carbide MOSFET after linearization approximation is used to solve the turn-on process of the reverse recovery of the SiC MOSFET, and the voltage and current waveforms of the reverse recovery are obtained.

[0010] 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.

[0011] Preferably, the specific process of establishing the three-capacitor model is as follows:

[0012] Gate-source capacitance C based on SiC MOSFET gs Gate-drain capacitance C gd and drain-source capacitance C ds A three-capacitor model was established.

[0013] Preferably, the specific process for establishing the reverse recovery model of a medium-voltage silicon carbide MOSFET is as follows:

[0014] Based on the diffusion capacitance, the three-capacitor model is improved to reduce the gate-drain capacitance of the PN junction during forward conduction. C gd and drain-source capacitance C ds Larger than the capacitance of a PN junction under reverse bias, gate-source capacitance C gs The value remains unchanged, thus yielding the reverse recovery model for medium-voltage silicon carbide MOSFETs.

[0015] Preferably, the expression for the reverse recovery model of the medium-voltage silicon carbide MOSFET is:

[0016]

[0017] in, v gs , v gd , v ds These are the voltages at each port of the device.i ch For the device channel current, the function f This represents the static characteristics of the device. i d This refers to the drain current of the device. v D and i D These represent the voltage and current of the freewheeling diode, respectively. g Represents the static output characteristics of a diode; V DC This is the DC bus voltage. V DD For driving voltage, R g For driving resistor, I L For inductor current, C gs , C gd , C ds The junction capacitance is denoted by l, and the subscripts l and h represent the capacitance values ​​of the lower transistor and the upper diode, respectively. L g , L s , L loop These are the device gate parasitic inductance, source parasitic inductance, and commutation circuit parasitic inductance, respectively.

[0018] Preferably, the reverse recovery model of the medium-voltage silicon carbide MOSFET is linearized and approximated. The specific process is as follows:

[0019] The characteristics of the SiC MOSFET channel and body diode in the reverse recovery model of medium-voltage silicon carbide MOSFETs are linearized and approximated. gs C gd And C ds The calculation is approximated by two constant capacitance segments. Based on the diffusion capacitance, the gate-source C of the MOSFET is... gs Short circuit, C gd and C ds The junction capacitance C of the body diode is obtained by connecting them in parallel. j ;

[0020] The C of the device gs C gd And C ds The specific calculation formula for approximating two constant capacitor segments is as follows:

[0021]

[0022]

[0023]

[0024] ;

[0025] in, i ch This refers to the channel current of the SiC MOSFET when it is in the saturation region. g m For the transconductance of the device, v gs and V th These are the gate-source voltage and the turn-on threshold voltage of the device, respectively. i D For body diode current, V f and R D These are the forward voltage drop and forward resistance of the body diode, respectively. V ds (- V D () represents the drain-source voltage of the MOSFET or body diode. C gs , C gd , C ds These are the gate-source capacitance, gate-drain capacitance, and drain-source capacitance of the device, respectively. V b This is the boundary voltage for capacitance changes; C gd1 , C ds1 They are respectively V ds Greater than V b Gate-drain capacitance and drain-source capacitance at the time C gd2 , C ds2 They are respectively V ds Less than V b Gate-drain capacitance and drain-source capacitance at time, including V ds The portion of the body diode that is conducting when the value is less than 0. C gd2 >> C gd1 , C ds2 >> Cds1 , C j For the junction capacitance of the body diode, we have 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 at that time. C j2 for V ds Less than V b The junction capacitance of the body diode at that time.

[0026] Preferably, the reverse recovery turn-on process of SiC MOSFET is solved based on the reverse recovery model of medium-voltage silicon carbide MOSFET after linearization approximation. The specific process is as follows:

[0027] Based on the state of the SiC MOSFET, the time-domain voltage and current waveforms are analytically solved for each stage of the turn-on process, including:

[0028] t At time 0: Before the lower SiC MOSFET of the device is turned on, the body diode of the upper MOSFET is an inductor freewheeling current. I L The forward conduction voltage of the body diode is V f + I L R D The drain-source voltage of the lower transistor is V dc + V f + I L R D The gate-source voltage of the lower transistor is v gs Maintain at the shutdown level V EE , recorded as t At time 0,

[0029] in Vf and R D These are the forward voltage drop and forward resistance of the body diode, respectively.

[0030] t 0~ t Phase 1: In t At time 0, driving voltage V DD When the voltage rises to the turn-on level, the gate-source voltage of the device is v gs The gate-source voltage of the device begins to rise, at which point the time function of the gate-source voltage begins to rise. v gs ( t Less than V th If no current flows through the lower pipe channel, then

[0031]

[0032] In the formula τ iss1 = R g ( C gs + C gd1 ), R g For driving resistor, V EE This is the gate-source turn-off voltage. C gd1 for V ds Greater than V b Gate-drain capacitance at time;

[0033] when v gs ( t ) to reach V th When this stage ends, it is denoted as t At time 1, then t 1= t 0+ τ iss1 ln(( V DD - V EE ) / ( V DD - V th )); V th The turn-on threshold voltage;

[0034] t 1~ t Phase 2: The current in the lower diode rises, the current in the body diode falls, the corresponding forward voltage drops, and the reverse recovery process begins, denoted as... t At time 2, that is, the junction capacitance of the body diode. C j If a displacement current is generated, then

[0035]

[0036] in

[0037]

[0038] In the formula: g m For the transconductance of the device, i D (t) is the time function of the body diode current;

[0039] t 2~ t Stage 3: The diode current is 0, but the channel current flowing through the junction capacitance causes a voltage change.

[0040]

[0041] in, i Cj Junction capacitance C j The current flowing through it; when v D ( t ) Descend to - V b At that time, the diode junction capacitance is changed from C j2 Descending to C j1 , recorded as t At 3 o'clock, i Cj (t) represents the junction capacitance. C j The time function of the current flowing through it; v D ( t () represents the voltage-time function of the freewheeling diode;

[0042] t 3~ t Stage 4: This is the Miller plateau stage, where the voltage of the lower transistor drops and the drive current increases. i g Continuous installation of the pipe is required C gd Charge,

[0043] ;

[0044] when v ds ( t ) decreased to V b When the junction capacitance of the lower transistor changes, then...

[0045]

[0046] when v ds ( t When the value drops to 0, this phase ends, denoted as... t 4 moments;

[0047] t 4~ t Phase 5: The opening process is complete. v gs ( t Continue to rise exponentially, recorded as t At time 5, the time constant changes to τ iss2 = R g ( C gs + C gd2 ),but

[0048]

[0049] Thus, voltage waveforms at different stages can be obtained. v ds ( t ) and current waveform i ch ( t The time-domain analytical solution of ).

[0050] Preferably, the heat loss of the medium-voltage SiC MOSFET during the turn-on process is obtained based on the reverse recovery voltage and current waveforms. The calculation formula is:

[0051] .

[0052] A system for analyzing the turn-on loss of a medium-voltage silicon carbide MOSFET based on a diffused capacitance reverse recovery model includes,

[0053] The module includes a model building module, a linearization approximation module, a voltage and current waveform solving module, and a heat loss calculation module.

[0054] The model building module is used to extend the range of SiC MOSFET junction capacitance based on the diffusion capacitance and three-capacitor model to obtain the reverse recovery model of medium-voltage silicon carbide MOSFET.

[0055] The linearization approximation module is used to perform linearization approximation on the reverse recovery model of the medium-voltage silicon carbide MOSFET.

[0056] The voltage and current waveform solving module is used to solve the turn-on process of SiC MOSFET reverse recovery based on the reverse recovery model after linearization approximation, and obtain the voltage and current waveforms of reverse recovery.

[0057] The heat loss calculation module is used to obtain the heat loss of the medium-voltage SiCMOSFET during the turn-on process based on the reverse recovery voltage and current waveforms.

[0058] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the turn-on loss calculation method based on the diffusion capacitance reverse recovery model.

[0059] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the turn-on loss calculation method based on the diffused capacitance reverse recovery model.

[0060] Compared with the prior art, the present invention has the following beneficial technical effects:

[0061] This invention discloses a reverse recovery model for medium-voltage silicon carbide MOSFETs based on diffused capacitance. Addressing the switching characteristics of medium-voltage SiC MOSFETs at higher voltages, it improves upon the traditional reverse recovery current model based on low-voltage Si / SiC power electronic devices during turn-on. By describing the device's port characteristics using a unified junction capacitance, the waveform of the reverse recovery current is derived, allowing for accurate calculation of the heat loss of the medium-voltage SiC MOSFET during turn-on. Extending the range of SiC MOSFET junction capacitance based on diffused capacitance and a three-capacitor model yields the reverse recovery model for medium-voltage SiC MOSFETs. This method improves upon the traditional reverse recovery current model based on low-voltage Si / SiC power electronic devices by combining diffused capacitance and a three-capacitor model to extend the junction capacitance range of SiC MOSFETs. This approach more accurately describes the reverse recovery characteristics of medium-voltage SiC MOSFETs, enhancing the model's simulation accuracy of actual device behavior and providing a solid foundation for subsequent analysis and optimization. By solving the linearized reverse recovery model, this method obtains 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 switching. Based on the reverse recovery voltage and current waveforms, this method can further calculate the heat loss of the medium-voltage SiC MOSFET during turn-on. Heat loss is an important parameter in device reliability assessment because it directly affects the device's operating temperature and lifespan. Accurate calculation of heat loss can provide strong support for the thermal design of the device, ensuring that the device maintains stable performance under harsh operating conditions. The reverse recovery model of this medium-voltage silicon carbide MOSFET and the solution results can effectively and accurately reflect the reverse recovery phenomenon of the MOSFET body diode during turn-on, and are used for the calculation of turn-on losses, which is beneficial for the parameter design and thermal design of power electronic converters. Attached Figure Description

[0062] Figure 1 The present invention considers a three-capacitor model with diffused capacitance;

[0063] Figure 2 This is a linearized approximation model of the SiC MOSFET of the present invention;

[0064] Figure 3 This invention provides a process experimental circuit;

[0065] Figure 4 This is the SiC MOSFET dual-pulse test platform circuit of the present invention.

[0066] Figure 5 This is the waveform of the opening process obtained by analytical calculation in this invention. Detailed Implementation

[0067] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0068] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0069] A method for calculating turn-on loss based on a reverse recovery model of diffused capacitance, comprising:

[0070] After extending the range of SiC MOSFET junction capacitance based on the diffusion capacitance and three-capacitor model, the reverse recovery model of medium-voltage silicon carbide MOSFET is obtained.

[0071] like Figure 1 As shown, the specific process of establishing the three-capacitor model is as follows:

[0072] Gate-source capacitance C based on SiC MOSFET gs Gate-drain capacitance C gd and drain-source capacitance C ds A three-capacitor model was established.

[0073] The specific process for establishing the reverse recovery model of medium-voltage silicon carbide MOSFETs is as follows:

[0074] Based on the diffusion capacitance, the three-capacitor model is improved so that the capacitance C when the PN junction in the three-capacitor model is forward-conducting is increased. gd and C ds The capacitance is larger than that of a PN junction when it is reverse biased, C gs The value remains unchanged, thus yielding the reverse recovery model for medium-voltage silicon carbide MOSFETs.

[0075] The classic three-capacitor model includes the one shown in the diagram. C gs , C gd and C ds However, generally only consider v dsTheir function when >0. This invention extends the range of SiC MOSFET junction capacitance to a certain extent: when the body diode is turned on, the PN junction withstands a forward voltage. According to semiconductor theory, the PN junction at this time has a capacitance effect caused by the accumulation of minority carriers, which is called diffusion capacitance.

[0076] The capacitance corresponding to the PN junction is mainly composed of the gate-drain capacitance of the MOSFET. C gd ) and drain-source capacitance ( C ds ) constitutes, while the gate-source capacitance ( C gs The gate-source parallel structure capacitance (PN junction capacitance) is almost unaffected by changes in drain-source voltage. Therefore, in the established reverse recovery model of a medium-voltage silicon carbide MOSFET, the PN junction capacitance during forward conduction is... C gd and C ds It is larger than the capacitance of a PN junction when it is reverse biased (which mainly depends on the barrier capacitance), and C gs Almost unchanged.

[0077] The expression for the reverse recovery model of a medium-voltage silicon carbide MOSFET is as follows:

[0078]

[0079] in, v gs , v gd , v ds These are the voltages at each port of the device. i ch For the device channel current, the function f This represents the static characteristics of the device. i d This refers to the drain current of the device. v D and i D These represent the voltage and current of the freewheeling diode, respectively. g Represents the static output characteristics of a diode; V DC This is the DC bus voltage. V DD For driving voltage, R g For driving resistor, I L For inductor current, C gs , Cgd , C ds The junction capacitance is denoted by l, and the subscripts l and h represent the capacitance values ​​of the lower transistor and the upper diode, respectively. L g , L s , L loop The parasitic inductance of the device gate, the parasitic inductance of the source, and the parasitic inductance of the commutation circuit are respectively identified.

[0080] The characteristics of the SiC MOSFET channel and body diode in the reverse recovery model of medium-voltage silicon carbide MOSFETs are linearized and approximated, such as... Figure 2 As shown, the specific process is as follows:

[0081] The characteristics of the SiC MOSFET channel and body diode are linearized and approximated, and the C of the device is... gs C gd And C ds The calculation is approximated by two constant capacitance segments. Based on the diffusion capacitance, the gate-source C of the MOSFET is... gs Short circuit, C gd and C ds The junction capacitance C of the body diode is obtained by connecting them in parallel. j ;

[0082] The C of the device gs C gd And C ds The specific calculation formula for approximating two constant capacitor segments is as follows:

[0083]

[0084]

[0085]

[0086]

[0087] in, i ch This refers to the channel current of the SiC MOSFET when it is in the saturation region. g m For the transconductance of the device, v gs and V th These are the gate-source voltage and the turn-on threshold voltage of the device, respectively. i D For body diode current, Vf and R D These are the forward voltage drop and forward resistance of the body diode, respectively. V ds (- V D () represents the drain-source voltage of the MOSFET or body diode. C gs , C gd , C ds These are the gate-source capacitance, gate-drain capacitance, and drain-source capacitance of the device, respectively. V b This is the boundary voltage for capacitance changes; C gd1 , C ds1 They are respectively V ds Greater than V b Gate-drain capacitance and drain-source capacitance at the time C gd2 , C ds2 They are respectively V ds Less than V b Gate-drain capacitance and drain-source capacitance at time, including V ds The portion of the body diode that is conducting when the value is less than 0. C gd2 >> C gd1 , C ds2 >> C ds1 , C j The junction capacitance of the body diode.

[0088] The reverse recovery turn-on process of SiC MOSFET is solved based on the linearized approximation model to obtain the reverse recovery voltage and current waveforms.

[0089] The reverse recovery process is solved based on 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 methods (such as piecewise linear methods) and numerical methods (such as Runge-Kutta methods, numerical calculation software, circuit simulation software, etc.), as well as some possible approximations.

[0090] The switching process can be divided into several stages based on the state of the SiC MOSFET, such as... Figure 5As shown, the voltage and current waveforms in the time domain are analytically solved for each stage.

[0091] (a) Stage 0 (~ t 0): In a dual-pulse half-bridge circuit, before the lower SiC MOSFET is turned on, the body diode of the same type of upper transistor acts as an inductor for freewheeling current. Let the inductor current be... I L The inductance value is large enough that it will be considered a constant current source in the subsequent analysis. At this time, the forward voltage of the diode is... V f + I L R D The drain-source voltage of the lower transistor is V dc + V f + I L R D Gate-source voltage of the lower transistor v gs Maintain at the shutdown level V EE .

[0092] (b) Phase 1 ( t 0~ t 1): t At time 0, the drive voltage rises to the turn-on level. V DD Lower pipe v gs It begins to rise. Because at this time... v gs ( t Less than V th Therefore, no current flowed through the lower pipe channel.

[0093]

[0094] In the formula τ iss1 = R g ( C gs + C gd1 ), R g For driving resistance. When v gs ( t ) to reach V th This phase ends at that time. t 1=t 0+ τ iss1 ln(( V DD - V EE ) / ( V DD - V th )).

[0095] (c) Phase 2 ( t 1~ t 2): At this point, the current in the lower diode increases, the diode current decreases, and the corresponding forward voltage decreases. It is assumed that the reverse recovery process has begun at this time, i.e., a relatively large forward voltage. C j The displacement current is caused by voltage changes. Ignoring the effect of parasitic inductance, then at this time... v gs It continues to increase exponentially. Based on Kirchhoff's laws, the nodal current equation is derived:

[0096]

[0097] Solving

[0098]

[0099] in

[0100]

[0101] v D ( t According to equation (2), it decreases slowly. Because... C gd1 and C ds1 The drain current is relatively small. Ignoring the displacement current caused by voltage changes to the lower transistor's capacitor, we assume the drain current is... i d equal to channel current i ch .when i D ( t When the voltage drops to 0 V, the next stage begins; this moment is denoted as _____. t 2.

[0102] (d) Stage 3 ( t 2~ t 3): During this stage, the diode current is 0, while the current flowing through all the channels in the junction capacitance causes a voltage change.

[0103]

[0104] when v D ( t ) Descend to - V b At that time, the diode junction capacitance is changed from C j2 Descending to C j1 , time is t 3. Entering the stage of voltage drop in the lower tube.

[0105] (e) Stage 4 ( t 3~ t 4) This stage is the Miller plateau stage. The displacement current on the lower transistor's capacitor cannot be ignored. To reduce the voltage of the lower transistor, the drive current... i g Requires continuous pipe laying C gd Charging. Yes.

[0106]

[0107] This system of equations is a typical first-order linear ordinary differential equation system, and its analytical solution can be easily obtained. When v ds ( t ) decreased to V b At that time, the junction capacitance of the lower transistor will also change, and the above equation becomes

[0108]

[0109] when v ds ( t When the value drops to 0, this phase ends, and the time is recorded as 0. t 4.

[0110] (f) Stage 4 ( t 4~ t 5): The switching process is basically complete. v gs ( t ) Continue to rise exponentially, at which point the time constant changes to τ iss2 = R g ( C gs + C gd2 ),have

[0111]

[0112] Based on the above calculations, during the MOSFET turn-on process... v ds ( t ) and i ch ( t All of these can be solved to obtain a time-domain analytical expression, and the actual heat loss during the turn-on process can be expressed as:

[0113]

[0114] (2) Analysis of reverse recovery current of SiC MOSFET. Based on the model established in step (1), the reverse recovery current of SiC MOSFET is analyzed, and the trend of reverse recovery current with the change of circuit parameters is explained.

[0115] Taking the double-pulse circuit in Figure 4 as an example, in this circuit, the lower transistor is the device, and the upper transistor is used as a diode with its gate and source shorted. An inductor is connected in parallel across the upper transistor. The reverse recovery current is defined as the sum of the current in the diode and its junction capacitance. Reverse recovery occurs when the lower transistor is turned on; before this, the upper transistor acts as a freewheeling diode, carrying the current in the inductor. When the lower transistor is turned on, the current gradually commutates from the freewheeling diode to the device. During this process, according to the diode's output characteristics, the forward voltage drop of the diode decreases as the current decreases. This voltage change occurs at the junction capacitance (…). C gd_h + C ds_h A displacement current is generated on the junction. Although the voltage change is extremely small (from below 10 volts to 0 volts), the displacement current is still significant due to the large junction capacitance at this time. This displacement current is the first part of the reverse recovery current. Figure 4 The reverse recovery current spike is shown.

[0116] When the diode is under reverse voltage C gd_h and C ds_h As the voltage decreases, the reverse voltage of the diode rises rapidly, also generating a certain displacement current, 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 plateau is shown.

[0117] The larger the forward current before commutation, the larger the forward voltage drop of the diode, and the larger the integral of the junction capacitance with respect to the voltage change, thus making the reverse recovery phenomenon more obvious.

[0118] A system for analyzing the turn-on loss of a medium-voltage silicon carbide MOSFET based on a diffused capacitance reverse recovery model includes a model building module, a linearization approximation module, a voltage and current waveform solving module, and a heat loss calculation module.

[0119] The model building module is used to extend the range of SiC MOSFET junction capacitance based on the diffusion capacitance and three-capacitor model to obtain the reverse recovery model of medium-voltage silicon carbide MOSFET.

[0120] The linearization approximation module is used to perform linearization approximation on the characteristics of the SiC MOSFET channel and body diode based on the reverse recovery model.

[0121] The voltage and current waveform solving module is used to solve the turn-on process of SiC MOSFET reverse recovery based on the reverse recovery model after linearization approximation, and obtain the voltage and current waveforms of reverse recovery.

[0122] The heat loss calculation module is used to obtain the heat loss of the medium-voltage SiCMOSFET during the turn-on process based on the reverse recovery voltage and current waveforms.

[0123] One 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, it implements the steps in the above-described dynamic scene image deblurring method; or, when the processor executes the computer program, it implements the functions of each module in the above-described dynamic scene image deblurring system.

[0124] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0125] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0126] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0127] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0128] If the modules / units integrated in the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0129] Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the above-described dynamic scene image deblurring method. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate form.

[0130] The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium may be appropriately added to or subtracted 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 may not include electrical carrier signals and telecommunication signals.

[0131] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. 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 diffusion capacitance in the above embodiments.

[0132] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0133] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0134] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0135] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do 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 diffused capacitance, characterized in that, include, After extending the range of SiC MOSFET junction capacitance based on the diffusion capacitance and three-capacitor model, the reverse recovery model of medium-voltage silicon carbide MOSFET is obtained. The reverse recovery model of medium-voltage silicon carbide MOSFET is linearized and approximated. The reverse recovery model of the medium-voltage silicon carbide MOSFET after linearization approximation is used to solve the turn-on process of the reverse recovery of the SiC MOSFET, and the voltage and current waveforms of the reverse recovery are obtained. 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 specific process for establishing the reverse recovery model of medium-voltage silicon carbide MOSFETs is as follows: Based on the diffusion capacitance, the three-capacitor model is improved to reduce the gate-drain capacitance of the PN junction during forward conduction. C gd and drain-source capacitance C ds Larger than the capacitance of a PN junction under reverse bias, gate-source capacitance C gs The value remains unchanged, thus obtaining the reverse recovery model of the medium-voltage silicon carbide MOSFET; The expression for the reverse recovery model of the medium-voltage silicon carbide MOSFET is as follows: in, v gs , v gd , v ds These are the voltages at each port of the device. i ch The function represents the channel current of the SiC MOSFET in the saturation region. f This represents the static characteristics of the device. i d This refers to the drain current of the device. v D and i D The voltage and current of the body diode are respectively the voltage and current of the diode, and the function is... g Represents the static output characteristics of a diode; V DC This is the DC bus voltage. V DD For driving voltage, R g For driving resistor, I L For inductor current, C gs , C gd , C ds The junction capacitance is denoted by l, and the subscripts l and h represent the capacitance values ​​of the lower and upper diodes, respectively. L g , L s , L loop These are the device's gate parasitic inductance, source parasitic inductance, and commutation circuit parasitic inductance, respectively.

2. The method for calculating turn-on loss based on a reverse recovery model using diffused 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 A three-capacitor model was established.

3. The method for calculating turn-on loss based on a reverse recovery model using diffused capacitance according to claim 1, characterized in that, The reverse recovery model of medium-voltage silicon carbide MOSFETs 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 medium-voltage silicon carbide MOSFETs are linearized and approximated. gs C gd And C ds The calculation is approximated by two constant capacitance segments, based on the diffusion capacitance, making the C of the MOSFET... gs Short circuit, C gd and C ds The junction capacitance C of the body diode is obtained by connecting them in parallel. j ; The C of the device gs C gd And C ds The specific calculation formula for approximating two constant capacitor segments is as follows: ； in, i ch This refers to the channel current of the SiC MOSFET when it is in the saturation region. g m For the transconductance of the device, v gs and V th These are the gate-source voltage and the turn-on threshold voltage of the device, respectively. i D For the body diode current, V f and R D These are the forward voltage drop and forward resistance of the body diode, respectively. v ds , v D These are the drain-source voltages of the MOSFET or the body diode, respectively. C gs , C gd , C ds These are the gate-source capacitance, gate-drain capacitance, and drain-source capacitance of the device, respectively. V b This is the boundary voltage for capacitance changes; C gd1 , C ds1 They are respectively v ds Greater than V b Gate-drain capacitance and drain-source capacitance at time C gd2 , C ds2 They are respectively v ds Less than V b Gate-drain capacitance and drain-source capacitance at time, including v ds The portion of the body diode that is conducting when the value is less than 0. C gd2 >> C gd1 , C ds2 >> C ds1 , C j For the junction capacitance of the body diode, we have 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 at that time. C j2 for v ds Less than V b The junction capacitance of the body diode at that time.

4. The method for calculating turn-on loss based on a reverse recovery model using diffused capacitance according to claim 3, characterized in that, The reverse recovery turn-on process of SiC MOSFET is solved based on the linearized approximation model. The specific process is as follows: Based on the state of the SiC MOSFET, the time-domain voltage and current waveforms are analytically solved for each stage of the turn-on process, including: t At time 0: Before the lower SiC MOSFET of the device is turned on, the body diode of the upper MOSFET is an inductor freewheeling current. I L The forward conduction voltage of the body diode is V f + I L R D The drain-source voltage of the lower transistor is V DC + V f + I L R D The gate-source voltage of the lower transistor is v gs Maintain at the shutdown level V EE , recorded as t At time 0, in V f and R D These are the forward voltage drop and forward resistance of the body diode, respectively. t 0~ t Phase 1: In t At time 0, driving voltage V DD When the voltage rises to the turn-on level, the gate-source voltage of the device is v gs The gate-source voltage of the device begins to rise, at which point the time function of the gate-source voltage begins to rise. v gs ( t Less than V th If no current flows through the lower pipe channel, then In the formula τ iss1 = R g ( C gs + C gd1 ), R g For driving resistor, V EE This is the gate-source turn-off voltage. C gd1 for v ds Greater than V b Gate-drain capacitance at time; when v gs ( t ) to reach V th When this stage ends, it is denoted as t At time 1, then t 1 = t 0 + τ iss1 ln(( V DD - V EE ) / ( V DD - V th )); V th The turn-on threshold voltage; t 1~ t Phase 2: The current in the lower diode rises, the current in the body diode falls, the corresponding forward voltage drops, and the reverse recovery process begins, denoted as... t At time 2, that is, the junction capacitance of the body diode. C j If a displacement current is generated, then in In the formula: g m For 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, but the channel current flowing through the junction capacitance causes a voltage change. in, i Cj Junction capacitance C j The current flowing through it; when v D ( t ) Descend to - V b At that time, the diode junction capacitance is changed from C j2 Descending to C j1 , recorded as t At 3 o'clock, i Cj (t) represents the junction capacitance. C j The time function of the current flowing through it; v D ( t () represents the voltage-time function of the freewheeling diode; t 3~ t Stage 4: This is the Miller plateau stage, where the voltage of the lower transistor drops and the drive current increases. i g Continuous installation of the pipe is required C gd Charge, ； when v ds ( t ) decreased to V b When the junction capacitance of the lower transistor changes, then... when v ds ( t When the value drops to 0, this phase ends, denoted as... t 4 moments; t 4~ t Phase 5: The opening process is complete. v gs ( t Continue to rise exponentially, recorded as t At time 5, the time constant changes to τ iss2 = R g ( C gs + C gd2 ),but Thus, voltage waveforms at different stages can be obtained. v ds ( t ) and current waveform i ch ( t The time-domain analytical solution of ).

5. The method for calculating turn-on loss based on a reverse recovery model using diffused capacitance according to claim 4, 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: 。 6. A system for analyzing the turn-on loss of a medium-voltage silicon carbide MOSFET based on a diffused capacitance reverse recovery model, wherein the turn-on loss calculation method is based on any one of claims 1-5, characterized in that, include, The module includes a model building module, a linearization approximation module, a voltage and current waveform solving module, and a heat loss calculation module. The model building module is used to extend the range of SiC MOSFET junction capacitance based on the diffusion capacitance and three-capacitor model to obtain the reverse recovery model of medium-voltage silicon carbide MOSFET. The linearization approximation module is used to perform linearization approximation 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 SiCMOSFET reverse recovery based on the reverse recovery model after linearization approximation, and obtain the voltage and current waveforms of reverse recovery. The heat loss calculation module is used to obtain the heat loss of the medium-voltage SiC MOSFET during the turn-on process based on the reverse recovery voltage and current waveforms.

7. 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, it implements the steps of the turn-on loss calculation method based on the reverse recovery model of diffusion capacitance as described in any one of claims 1-5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the turn-on loss calculation method based on the reverse recovery model of diffusion capacitance as described in any one of claims 1-5.

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