SiC MOSFET circuit simulation model construction method and device

Abstract

The invention discloses a method and a device for constructing a circuit simulation model of a SiC MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). The method and the device are used for solving the problems of low accuracy of third quadrant characteristic modeling and poorer model convergence when the SiC MOSFET is modeled at present. The method comprises the following steps: acquiring a model circuit structure of the SiC MOSFET and a third quadrant working data point set; reverse current fitting based on voltage comparison is carried out on the third quadrant working data point set according to a preset model expression, and fitting coefficients of the model expression are obtained; and constructing a circuit simulation model of the SiC MOSFET according to the model circuit structure, the third quadrant working data point set, the model expression and each fitting coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor circuit simulation, and particularly to a method for constructing a circuit simulation model of a SiC MOSFET, a device for constructing a circuit simulation model of a SiC MOSFET, an electronic device, and a storage medium. Background Art

[0002] SiC (Silicon Carbide) is a third-generation wide-bandgap semiconductor material, which has characteristics such as a larger bandgap width, a higher breakdown field strength, a higher thermal conductivity, and a higher electron saturation rate compared with silicon. It has better performance in high-temperature, high-voltage, high-frequency, and high-power application scenarios. Currently, in medium- and high-voltage applications, SiC MOSFET (SiC Metal-Oxide-Semiconductor Field Effect Transistor) devices are gradually replacing traditional Si MOSFETs. With the continuous expansion of the application requirements of SiC MOSFETs, establishing a reliable, accurate, and practical circuit simulation model of SiC MOSFETs is crucial for the preliminary design of power electronic converters.

[0003] According to different modeling methods, traditional power device models can be mainly divided into three categories: physical models, numerical models, and behavioral models. High-precision and high-complexity physical models have a large amount of calculation and long simulation time, and are not suitable for system simulation analysis and actual industrial design. The numerical model has a complex structure and a long simulation time, and is also not suitable for the actual design of power electronic circuits. The behavioral model describes the external characteristics of the device through empirical formulas and mathematical fitting formulas, without describing the internal working mechanism of the device. The model is easy to establish and the parameters are easy to obtain, and it can accurately describe the actual working state of the device within a certain range. That is, the behavioral model has a faster simulation speed, is easier to converge, and is more in line with the actual circuit simulation requirements.

[0004] Currently, most SiC MOSFET models focus on the establishment of voltage-controlled current sources and nonlinear junction capacitances. For the establishment of the body diode model, a fixed circuit model is often directly generated using a model editor. In the product simulation models provided by some mainstream silicon carbide manufacturers to users, the reverse conduction process of the SiC MOSFET is simply approximated as a symmetric process of the forward conduction current, resulting in a large difference between the model simulation results and the actual measurements and low model accuracy. In addition, the current SiC MOSFET models also have problems with poor model convergence. Summary of the Invention

[0005] The present invention provides a method for constructing a circuit simulation model of a SiC MOSFET, a device for constructing a circuit simulation model of a SiC MOSFET, an electronic device, and a storage medium, which are used to solve or partially solve the technical problems of low accuracy in modeling the third quadrant characteristics and poor model convergence when modeling a SiC MOSFET currently.

[0006] The present invention provides a method for constructing a circuit simulation model of a SiC MOSFET, including:

[0007] Obtain the model circuit structure of the SiC MOSFET and the set of third quadrant operating data points;

[0008] Perform reverse current fitting based on voltage ratio on the set of third quadrant operating data points according to a preset model expression to obtain each fitting coefficient of the model expression;

[0009] Construct the circuit simulation model of the SiC MOSFET according to the model circuit structure, the set of third quadrant operating data points, the model expression, and each fitting coefficient.

[0010] Optionally, the model expression includes a first reverse current expression, a second reverse current expression, and a third reverse current expression; the performing reverse current fitting based on voltage ratio on the set of third quadrant operating data points according to a preset model expression to obtain each fitting coefficient of the model expression includes:

[0011] Extract the gate-source voltage and the threshold voltage of the SiC MOSFET when it operates in the third quadrant from the set of third quadrant operating data points;

[0012] Perform voltage ratio using the gate-source voltage and the threshold voltage, and based on the voltage ratio result, select a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression;

[0013] Perform fitting on the set of third quadrant operating data points according to the target reverse current expression to obtain each fitting coefficient of the target reverse current expression.

[0014] Optionally, the selecting a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression based on the voltage ratio result includes:

[0015] When the gate-source voltage is less than the threshold voltage, use the first reverse current expression as the target reverse current expression;

[0016] Among them, the first reverse current expression indicates that the reverse current in the SiC MOSFET only flows through the body diode path, and the reverse current flowing through the body diode is jointly determined by the source-drain voltage, the gate-source voltage, and the junction temperature.

[0017] Optionally, the selecting the target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression based on the voltage ratio result includes:

[0018] When the gate-source voltage is greater than or equal to the threshold voltage, extract the source-drain voltage and the knee voltage at which the body diode turns on when the SiC MOSFET operates in the third quadrant from the set of operating data points in the third quadrant;

[0019] Calculate the on-resistance according to the gate-source voltage and the threshold voltage, and calculate the body diode delayed turn-on voltage based on the on-resistance and the knee voltage; [[ID=I0]]

[0020] When the source-drain voltage is less than the body diode delayed turn-on voltage, use the second reverse current expression as the target reverse current expression;

[0021] Among them, the second reverse current expression indicates that the body diode in the SiC MOSFET is not conducting, and the reverse current only flows through the channel current path. The reverse current flowing through the channel is jointly determined by the source-drain voltage and the on-resistance.

[0022] Optionally, the method further includes:

[0023] When the source-drain voltage is greater than or equal to the body diode delayed turn-on voltage, use the third reverse current expression as the target reverse current expression;

[0024] Among them, the third reverse current expression indicates that the reverse current in the SiC MOSFET flows through both the body diode path and the channel current path at the same time. The reverse current flowing through the body diode and the channel at the same time is jointly determined by the source-drain voltage, the on-resistance, the gate-source voltage, the junction temperature, and the body diode delayed turn-on voltage.

[0025] Optionally, the method further includes:

[0026] Simulate the SiC MOSFET using the circuit simulation model, and extract the set of simulated operating data points when the SiC MOSFET operates in the third quadrant from the simulation results;

[0027] Compare the set of simulated operating data points with the set of operating data points in the third quadrant, and correct and optimize the model of the circuit simulation model based on the comparison result.

[0028] Optionally, the model circuit structure includes a body diode circuit structure; the body diode circuit structure is composed of a voltage-controlled current source, an ohmic resistor, and a non-linear junction capacitor; wherein, the parallel connection point of the voltage-controlled current source and the non-linear junction capacitor is connected in series to one end of the ohmic resistor.

[0029] The present invention also provides a device for constructing a circuit simulation model of a SiC MOSFET, including:

[0030] A data acquisition unit, configured to acquire the model circuit structure of the SiC MOSFET and a set of working data points in the third quadrant;

[0031] A data fitting unit, configured to perform reverse current fitting based on voltage comparison on the set of working data points in the third quadrant according to a preset model expression, to obtain each fitting coefficient of the model expression;

[0032] A model construction unit, configured to construct the circuit simulation model of the SiC MOSFET according to the model circuit structure, the set of working data points in the third quadrant, the model expression, and each fitting coefficient.

[0033] The present invention also provides an electronic device, the device includes a processor and a memory:

[0034] The memory is used to store program codes and transmit the program codes to the processor;

[0035] The processor is configured to execute the method for constructing the circuit simulation model of the SiC MOSFET according to any one of the above-mentioned instructions in the program codes.

[0036] The present invention also provides a computer-readable storage medium, the computer-readable storage medium is used to store program codes, and the program codes are used to execute the method for constructing the circuit simulation model of the SiC MOSFET according to any one of the above-mentioned.

[0037] From the above technical solutions, it can be seen that the present invention has the following advantages:

[0038] A method for constructing a circuit simulation model of a SiC MOSFET is provided. First, the model circuit structure of the SiC MOSFET and the set of operating data points in the third quadrant are obtained; then, based on the preset model expression, the reverse current fitting of the set of operating data points in the third quadrant is performed by voltage comparison to obtain the fitting coefficients of the model expression. Thus, based on the preset model expression, the actual measured operating data in the third quadrant can be fitted, and the accurate fitting coefficients of the model expression can be obtained by reverse fitting according to the actual data closely related to the characteristics in the third quadrant; then, according to the model circuit structure, the set of operating data points in the third quadrant, the model expression, and each fitting coefficient, a circuit simulation model of the SiC MOSFET is constructed. Therefore, by fully combining the actual measured data, the model expression, the fitting coefficients fitted based on the actual situation, and the model circuit structure of the SiC MOSFET for model establishment, a circuit simulation model with high accuracy can be obtained. Based on this model for subsequent circuit simulation, the convergence of the SiC MOSFET during simulation calculation can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0040] Figure 1 It is a schematic diagram of the equivalent circuit structure of a SiC MOSFET;

[0041] Figure 2 It is a flowchart of the steps of a method for constructing a circuit simulation model of a SiC MOSFET;

[0042] Figure 3 It is a schematic diagram of the internal structure principle of a SiC MOSFET;

[0043] Figure 4 It is a schematic diagram of the internal structure principle of another SiC MOSFET;

[0044] Figure 5 It is a schematic diagram of the improved model structure of the body diode of a SiC MOSFET;

[0045] Figure 6 It is a schematic diagram of the comparison curve of the measurement result and the simulation result of the characteristics in the third quadrant of a SiC MOSFET;

[0046] Figure 7 It is a schematic diagram of the overall flow of a method for constructing a circuit simulation model of a SiC MOSFET;

[0047] Figure 8 It is a structural block diagram of a device for constructing a circuit simulation model of a SiC MOSFET. Specific implementation manners

[0048] Embodiments of the present invention provide a method for constructing a circuit simulation model of a SiC MOSFET, a device for constructing a circuit simulation model of a SiC MOSFET, an electronic device, and a storage medium, which are used to solve or partially solve the technical problems of low accuracy in modeling the third quadrant characteristics and poor model convergence when modeling a SiC MOSFET currently.

[0049] To make the invention objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0050] To enable those skilled in the art to better understand the technical solutions provided by the embodiments of the present invention, some technical features involved in the solutions are briefly described first:

[0051] SPICE (Simulation Program with Integrated Circuit Emphasis) model: A circuit model that can be directly run and solved in SPICE simulation software is called a SPICE model.

[0052] MOS channel (Metal-Oxide-Semiconductor Channel): That is, the channel mentioned in the embodiments of the present invention. It refers to the conductive channel formed under the gate after applying a certain gate-source voltage. The channel connects the source and the drain, enabling current to pass through.

[0053] Threshold voltage : The minimum gate-source voltage required to turn on the SiC MOSFET.

[0054] Junction capacitance: The equivalent capacitance brought by the structure of the MOSFET itself, which can be divided into gate-source capacitance , gate-drain capacitance and drain-source capacitance . It can also be divided into input capacitance , output capacitance , reverse transfer capacitance 。

[0055] Static characteristics: refer to the electrical characteristics of a device under steady-state conditions. It includes output characteristics (the relationship between drain current and drain-source voltage), transfer characteristics (the relationship between drain current and gate-source voltage), the relationship between on-resistance and temperature, and the relationship between threshold voltage and temperature, etc.

[0056] Third quadrant characteristics: refer to the operating characteristics of a MOSFET under reverse voltage (the drain-source voltage is negative) and reverse current (the drain current is negative).

[0057] Body diode: A pn junction formed between the source and drain due to the structure of the MOSFET itself, having characteristics similar to those of a diode.

[0058] Body diode delayed turn-on: When a positive gate-source voltage is applied, the body diode does not turn on immediately but turns on after the applied drain-source voltage reaches a certain value.

[0059] As an example, according to different modeling methods, traditional power device models can be mainly divided into three categories: physical models, numerical models, and behavioral models. High-precision and high-complexity physical models have a large amount of calculation and long simulation time, and are not suitable for system simulation analysis and actual industrial design. Numerical models have a complex structure and long simulation time, and are also not suitable for the actual design of power electronic circuits. Behavioral models describe the external characteristics of devices through empirical formulas and mathematical fitting formulas, without describing the internal working mechanism of the devices. The models are easy to establish and the parameters are easy to obtain, and can accurately describe the actual working state of the devices within a certain range. That is, behavioral models have a faster simulation speed, are easier to converge, and are more in line with the actual circuit simulation needs.

[0060] The equivalent circuit structure of a common SiC MOSFET device is as Figure 1 shown. Combining Figure 1 , the equivalent circuit of the SiC MOSFET device mainly includes the following units: voltage-controlled current source , gate-drain capacitance , gate-source capacitance , body diode , and the resistors and inductors inside the drain, source, and gate. Among them, the drain-source capacitance is included in the body diode model.

[0061] The voltage-controlled current source is the core part of the SiC MOSFET model. Through further analysis of the present invention, the channel current expression can be customized to describe the channel current as a function of the gate-source voltage , drain-source voltage and the junction temperature to simulate the static characteristics of SiC MOSFETs. The junction capacitance of SiC MOSFETs plays a major role in the device switching waveform. The data sheets provided by manufacturers usually contain the variation curve of the junction capacitance value with the drain-source voltage . The current model often fits the characteristics of the junction capacitance by extracting the data points of the characteristic curve in the data sheet.

[0062] Regarding the modeling of the body diode , most current models directly adopt the diode circuit model in SPICE simulation software. By measurement or data extraction, the main parameters such as the maximum conduction current, reverse peak voltage, maximum dissipation power, and maximum junction temperature of the body diode are obtained. Then, by importing them into the model editor built into the SPICE simulation software, the corresponding diode circuit model can be obtained.

[0063] Currently, most SiC MOSFET models focus on the establishment of voltage-controlled current sources and nonlinear junction capacitances. For the establishment of the body diode model, a fixed circuit model is often directly generated using the model editor. The current model simplifies the third quadrant characteristics of SiC MOSFETs to the conduction process of ordinary diodes, without considering the influence of the gate-source voltage on the reverse conduction process of SiC MOSFETs. Nor does it consider the influence of the junction temperature on the model.

[0064] In the product simulation models provided by some mainstream silicon carbide manufacturers for users, the reverse conduction process of SiC MOSFETs is simply approximated as a symmetric process of the forward conduction current, resulting in a large difference between the model simulation results and the actual measurements and low model accuracy. In addition, the current SiC MOSFET models also have problems such as poor model convergence.

[0065] Therefore, one of the core inventive points of the embodiments of the present invention lies in: aiming at the deficiencies of the current technology, a method for establishing a SPICE circuit simulation model for the third quadrant characteristics of high-voltage SiC MOSFETs is proposed. On the one hand, regarding the third quadrant operating characteristics in the SiC MOSFET model, instead of using a single body diode model for description, the influence of the gate-source voltage and junction temperature on the magnitude of the third quadrant characteristic current of the SiC MOSFET is comprehensively considered. Through methods such as characteristic measurement, data fitting, and model establishment, a high-accuracy circuit simulation model of the high-voltage SiC MOSFET is obtained. On the other hand, according to the actual operating conditions of the device, the operating conditions in the third quadrant of the SiC MOSFET are divided, and three types of operating intervals, namely, only the body diode conducting, only the channel resistance conducting, and the body diode and channel resistance conducting in parallel, are proposed, and the division basis and calculation expressions of each operating interval are specified. Compared with the previous models, the third quadrant characteristic modeling method proposed by the present invention can more accurately describe the operating conditions of the SiC MOSFET in the third quadrant, and the proposed model expression has good continuity and has good convergence and generality in actual simulation use.

[0066] Referring to Figure 2 , a flowchart of the steps of a method for constructing a circuit simulation model of a SiC MOSFET provided by an embodiment of the present invention is shown, which may specifically include the following steps:

[0067] Step 201, obtain the model circuit structure of the SiC MOSFET and the set of third quadrant operating data points;

[0068] To enable those skilled in the art to better understand the technical solution of the present invention, Figure 3 a schematic diagram of the internal structure principle of a SiC MOSFET is shown.

[0069] Combined with Figure 3 , when a positive voltage exceeding the threshold voltage is applied between the gate and the source, an inversion layer, that is, an N-type channel, will be formed on the surface of the P-base region under the gate oxide layer. This channel connects the source and the drain, enabling current to pass through. When the gate voltage is lower than the threshold voltage, the channel disappears, the device is cut off, and current cannot pass through. The threshold voltage is the minimum gate-source voltage required to turn the MOSFET from the cut-off state to the on state. In the on state, the current flows from the source through the formed N-type channel to the drain. Inside the SiC MOSFET, a pn junction is formed between the P+ region under the source and the N-drift region above the drain. This result reflects the diode characteristic, that is, the body diode of the SiC MOSFET.

[0070] Due to the interface defects in SiC MOSFETs, when a positive gate-source voltage is applied, the body diode does not conduct immediately. Instead, it conducts only after the applied drain-source voltage gradually increases to a certain value, that is, the delayed conduction phenomenon of the body diode.

[0071] When the SiC MOSFET operates in the third quadrant, there are two paths for the reverse current to flow. The internal structure principle of the SiC MOSFET at this time is as Figure 4 shown.

[0072] For the paths of the reverse current to flow, one is that the current flows reversely through the MOS channel, and the other is that the current flows along the path of the body diode. When a negative turn-off voltage is applied between the gate and source terminals of the device, the MOS channel is completely pinched off, and all the reverse conduction current flows through the body diode. When a positive gate-source voltage and are applied, the MOS channel opens, and the reverse current can flow through both the MOS channel and the body diode simultaneously. At this time, it is equivalent to the parallel conduction of the channel resistance and the body diode. When the gate-source voltage gradually increases from the negative turn-off voltage to the threshold voltage , the conduction characteristics of the body diode will also change simultaneously, and the knee voltage of the body diode turning on will gradually decrease until it approaches 0. In addition, different junction temperatures will also cause changes in the operating characteristics of the SiC MOSFET in the third quadrant.

[0073] Based on the above analysis, on the one hand, the embodiment of the present invention proposes a method for establishing a SPICE circuit simulation model of the third quadrant characteristics of SiC MOSFETs considering temperature effects. The constructed circuit simulation model has the advantages of high accuracy, good convergence, and strong generality.

[0074] In a specific implementation, first, use a semiconductor power device analyzer to measure and obtain the third quadrant operating characteristic curves of the target device SiC MOSFET at different temperatures as the set of third quadrant operating data points of the SiC MOSFET.

[0075] The model circuit structure includes the body diode circuit structure. The equivalent circuit of the SiC MOSFET model considering the third quadrant characteristics is still based on Figure 1 design. On the other hand, the present invention improves the body diode part in the traditional model to obtain an improved body diode model. Exemplarily, the schematic diagram of the structure of the improved body diode model of the SiC MOSFET is as Figure 5 shown.

[0076] The improved body diode circuit structure model consists of a voltage-controlled current source (that is, the reverse current As a voltage-controlled current source), ohmic resistance and non-linear junction capacitance consist of three parts. Among them, the voltage-controlled current source and the non-linear junction capacitance The parallel connection point of is connected in series at one end of the ohmic resistance One end of.

[0077] Voltage-controlled current source (i.e., the reverse current ) The model expression will be described in detail in the subsequent introduction. The ohmic resistance Is the parasitic resistance in the circuit. Its specific resistance value can be obtained by experimental testing. The non-linear junction capacitance The capacitance value of is related to the value of the drain-source voltage . The characteristic curve can be obtained from the device data sheet. The capacitance model expression is shown as follows:

[0078]

[0079] Among them, , Are all fitting coefficients.

[0080] Therefore, by replacing the body diode part in the current model with the reverse model proposed above, compared with the current model directly using the body diode structure, the model circuit structure provided by the embodiments of the present invention fully considers the gate-source voltage , junction temperature The influence on device characteristics.

[0081] Step 202, perform reverse current fitting based on voltage comparison on the third quadrant operating data point set according to the preset model expression to obtain each fitting coefficient of the model expression;

[0082] According to the curve characteristics and data points when the SiC MOSFET operates in the third quadrant, the model expression provided by the present invention may further include a first reverse current expression, a second reverse current expression, and a third reverse current expression.

[0083] In some embodiments, the process of performing reverse current fitting based on voltage comparison on the third quadrant operating data point set according to the preset model expression to obtain each fitting coefficient of the model expression can be implemented by executing the following sub-steps S01 to S03:

[0084] Step S01: Extract the gate-source voltage and threshold voltage when the SiC MOSFET operates in the third quadrant from the third quadrant operating data point set;

[0085] Step S02: Compare the gate-source voltage with the threshold voltage, and based on the result of the voltage comparison, select a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression;

[0086] In one case, based on the result of the voltage comparison, selecting a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression can be: when the gate-source voltage is less than the threshold voltage, use the first reverse current expression as the target reverse current expression.

[0087] Among them, the first reverse current expression represents the reverse current in the SiC MOSFET only flows through the body diode path, and the knee voltage at which the body diode turns on will gradually decrease as the gate-source voltage increases. The reverse current flowing through the body diode is determined by the source-drain voltage (i.e., the opposite of the drain-source voltage ), the gate-source voltage and the junction temperature jointly.

[0088] Specifically, when , the reverse current flows through the body diode path, and its current value is related to the gate-source voltage , the source-drain voltage and the junction temperature . The first reverse current expression is:

[0089]

[0090] Among them, are all temperature-related functions, and the specific expressions are:

[0091]

[0092] Among them, are all fitting coefficients.

[0093] In another case, based on the result of the voltage comparison, selecting a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression can be achieved by performing the following sub-steps S11 to S13:

[0094] Step S11: When the gate-source voltage is greater than or equal to the threshold voltage, extract the source-drain voltage and the knee voltage at which the body diode turns on when the SiC MOSFET operates in the third quadrant from the set of operating data points in the third quadrant;

[0095] Step S12: Calculate the on-resistance based on the gate-source voltage and the threshold voltage, and calculate the body diode delayed turn-on voltage based on the on-resistance and the knee voltage;

[0096] Specifically, when occurs, the MOS channel is formed. However, due to the body diode delayed conduction phenomenon, the reverse current 's flow path depends on the source-drain voltage and the body diode delayed turn-on voltage 's magnitude relationship. When the MOS channel is opened, the reverse current can flow through both the MOS channel and the body diode simultaneously, which is equivalent to the parallel conduction of the channel resistance and the body diode. At this time, the on-resistance of the MOSFET can be considered to be composed of the MOS channel resistance and the drift region resistance together. And the on-resistance value is related to both the gate-source voltage and the junction temperature , and its expression is:

[0097]

[0098] where are all fitting coefficients. The body diode delayed turn-on voltage can be expressed as:

[0099]

[0100] where is a fitting coefficient.

[0101] Step S13-1: When the source-drain voltage is less than the body diode delayed turn-on voltage, use the second reverse current expression as the target reverse current expression;

[0102] Among them, the second reverse current expression indicates that the body diode in the SiC MOSFET is not conducting, and the reverse current only flows through the channel current path. The reverse current flowing through the channel is jointly determined by the source-drain voltage and the on-resistance.

[0103] Specifically, if and , the body diode is not conducting, and the reverse current can only pass through the channel current path. That is, at this time, the second reverse current expression is:

[0104]

[0105] Step S13-2: When the source-drain voltage is greater than or equal to the body diode delayed turn-on voltage, use the third reverse current expression as the target reverse current expression.

[0106] Among them, the third reverse current expression indicates that the reverse current in the SiC MOSFET flows through both the body diode path and the channel current path simultaneously, and the reverse current flowing through the body diode and the channel is jointly determined by the source-drain voltage, on-resistance, gate-source voltage, junction temperature, and body diode delayed turn-on voltage.

[0107] Specifically, if and , the body diode conducts, and the reverse current flows through both the body diode and the MOS channel paths simultaneously. That is, at this time, the third reverse current expression is:

[0108]

[0109] It should be noted that the reverse current model expression proposed in the foregoing embodiments of the present invention is used to fit the third quadrant operating characteristics of the SiC MOSFET and can be replaced by an expression with a similar structure. Similarly, the expressions of the voltage correlation coefficient and the temperature correlation coefficient in the model expression can also be replaced by other forms of expressions. It can be understood that the present invention does not limit this.

[0110] It can be understood that, in addition to the examples given above, other modeling methods that divide the operating conditions in the third quadrant characteristics and consider that there are three operating intervals of only the body diode conducting, only the channel resistance conducting, and the body diode and the channel resistance conducting in parallel can achieve the same function as the method proposed in the present invention.

[0111] Step S03: Fit the third quadrant operating data point set according to the target reverse current expression to obtain each fitting coefficient of the target reverse current expression.

[0112] Based on the model expression introduced above, the measured third quadrant operating data points are fitted, so that each fitting coefficient in the expression can be obtained.

[0113] Step 203, construct a circuit simulation model of the SiC MOSFET according to the model circuit structure, the third quadrant operating data point set, the model expression, and each fitting coefficient.

[0114] Based on the model circuit structure, the third quadrant operating data point set (i.e., device measurement data), the model expression, and the fitting coefficients of each expression obtained by fitting given in the previous steps, a circuit simulation model of the SiC MOSFET can be edited and generated in SPICE software.

[0115] Furthermore, after the model is established, simulation experiments can be set up and the simulation results can be compared with the measured data to verify the accuracy of the established model and further correct and optimize the model parameters.

[0116] In a specific implementation, the SiC MOSFET can be simulated using a circuit simulation model first, and a set of simulation working data points when the SiC MOSFET operates in the third quadrant can be extracted from the simulation results; then the set of simulation working data points can be compared with the set of working data points in the third quadrant, and the model of the circuit simulation model can be modified and optimized based on the comparison results. For example, the experimental measurement results of the third quadrant characteristics of the SiC MOSFET are compared with the model simulation results. Figure 6 shown.

[0117] There may be multiple sets of fitting data results (ie, fitting coefficients) generated by the data fitting software, and those skilled in the art need to select the set with the best fitting effect as the final fitting coefficient.

[0118] During fitting, the software often displays a large number of decimal places in the fitted data. This rounding can affect other fitting results. Therefore, after fitting, it's necessary to first round off a portion of the fitted data, then re-enter this portion of data and re-fit to obtain a new set of fitting results for the remaining data. This process is repeated until a complete set of fitting results is determined.

[0119] In an embodiment of the present invention, a method for establishing a SPICE circuit simulation model for the third-quadrant characteristics of a high-voltage SiC MOSFET is proposed. First, the third-quadrant operating characteristics of the SiC MOSFET model are described, rather than using a single body diode model. Instead, the effects of gate-source voltage and junction temperature on the magnitude of the SiC MOSFET's third-quadrant characteristic current are comprehensively considered. Through characteristic measurement, data fitting, and model establishment, a highly accurate high-voltage SiC MOSFET circuit simulation model is obtained. Second, based on the device's actual operating conditions, the third-quadrant operating conditions of the SiC MOSFET are divided into three operating ranges: body diode conduction only, channel resistance conduction only, and body diode and channel resistance conduction in parallel. The basis for the division and calculation expressions for each operating range are also specified. Compared with previous models, the proposed third-quadrant characteristic modeling method can more accurately describe the third-quadrant operating conditions of SiC MOSFETs. Furthermore, the proposed model expression has good continuity, demonstrating good convergence and versatility in actual simulation applications.

[0120] For better explanation, refer to Figure 7, which shows a schematic diagram of the overall process of a method for constructing a circuit simulation model of a SiC MOSFET provided by an embodiment of the present invention. It should be noted that this embodiment only briefly describes the general process of constructing the circuit simulation model of the SiC MOSFET. The specific implementation process of each step can be understood by referring to the relevant content in the foregoing embodiments and will not be elaborated here. It can be understood that the present invention is not limited thereto.

[0121] Step 701: Obtain the model circuit structure of the SiC MOSFET and the set of third quadrant working data points when operating in the third quadrant;

[0122] Step 702: Perform reverse current fitting based on voltage comparison on the set of third quadrant working data points according to a preset model expression to obtain the fitting coefficients of the model expression;

[0123] Step 703: Construct a circuit simulation model of the SiC MOSFET according to the model circuit structure, the set of third quadrant working data points, the model expression, and the fitting coefficients;

[0124] Step 704: Simulate the SiC MOSFET using the circuit simulation model, and extract the set of simulation working data points when the SiC MOSFET operates in the third quadrant from the simulation results;

[0125] Step 705: Compare the set of simulation working data points with the set of third quadrant working data points, and correct and optimize the model of the circuit simulation model based on the comparison results.

[0126] Refer to Figure 8 , which shows a structural block diagram of a device for constructing a circuit simulation model of a SiC MOSFET provided by an embodiment of the present invention, and specifically may include:

[0127] A data acquisition unit 801, configured to obtain the model circuit structure of the SiC MOSFET and the set of third quadrant working data points;

[0128] A data fitting unit 802, configured to perform reverse current fitting based on voltage comparison on the set of third quadrant working data points according to a preset model expression to obtain the fitting coefficients of the model expression;

[0129] A model construction unit 803, configured to construct a circuit simulation model of the SiC MOSFET according to the model circuit structure, the set of third quadrant working data points, the model expression, and the fitting coefficients.

[0130] In an alternative embodiment, the model expression includes a first reverse current expression, a second reverse current expression, and a third reverse current expression; the data fitting unit 802 includes:

[0131] A voltage extraction unit, configured to extract the gate-source voltage and the threshold voltage when the SiC MOSFET operates in the third quadrant from the set of operating data points in the third quadrant;

[0132] An expression selection unit, configured to perform a voltage comparison using the gate-source voltage and the threshold voltage, and based on the voltage comparison result, select a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression;

[0133] A data fitting subunit, configured to fit the set of operating data points in the third quadrant according to the target reverse current expression to obtain each fitting coefficient of the target reverse current expression.

[0134] In an alternative embodiment, the expression selection unit is specifically configured to:

[0135] When the gate-source voltage is less than the threshold voltage, use the first reverse current expression as the target reverse current expression;

[0136] Wherein, the first reverse current expression indicates that the reverse current in the SiC MOSFET only flows through the body diode path, and the reverse current flowing through the body diode is jointly determined by the source-drain voltage, the gate-source voltage, and the junction temperature.

[0137] In an alternative embodiment, the expression selection unit is specifically configured to:

[0138] When the gate-source voltage is greater than or equal to the threshold voltage, extract the source-drain voltage and the knee voltage at which the body diode turns on when the SiC MOSFET operates in the third quadrant from the set of operating data points in the third quadrant;

[0139] Calculate the on-resistance according to the gate-source voltage and the threshold voltage, and calculate the body diode delayed turn-on voltage based on the on-resistance and the knee voltage;

[0140] When the source-drain voltage is less than the body diode delayed turn-on voltage, use the second reverse current expression as the target reverse current expression;

[0141] Wherein, the second reverse current expression indicates that the body diode in the SiC MOSFET is not turned on, and the reverse current only flows through the channel current path, and the reverse current flowing through the channel is jointly determined by the source-drain voltage and the on-resistance.

[0142] In an alternative embodiment, the expression selection unit is further specifically configured to:

[0143] When the source-drain voltage is greater than or equal to the body diode delayed turn-on voltage, use the third reverse current expression as the target reverse current expression;

[0144] Wherein, the third reverse current expression represents that the reverse current in the SiC MOSFET flows through both the body diode path and the channel current path, and the reverse current flowing through the body diode and the channel is jointly determined by the source-drain voltage, on-resistance, gate-source voltage, junction temperature, and body diode delayed turn-on voltage.

[0145] In an alternative embodiment, the device further includes:

[0146] A simulation unit, configured to simulate the SiC MOSFET using the circuit simulation model, and extract a set of simulation working data points when the SiC MOSFET operates in the third quadrant from the simulation results;

[0147] A data comparison unit, configured to compare the set of simulation working data points with the set of third quadrant working data points, and correct and optimize the model of the circuit simulation model based on the comparison result.

[0148] In an alternative embodiment, the model circuit structure includes a body diode circuit structure; the body diode circuit structure is composed of a voltage-controlled current source, an ohmic resistor, and a non-linear junction capacitor; wherein, the parallel connection point of the voltage-controlled current source and the non-linear junction capacitor is connected in series to one end of the ohmic resistor.

[0149] For the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For related parts, refer to the partial description of the foregoing method embodiment.

[0150] It should be noted that, in order to enable those skilled in the art to better distinguish data of the same type but with different actual reference meanings, in the embodiments of the present invention, some technical features are distinguished and described using first, second, and third. First, second, and third are only used for data distinction and have no other special meanings. It can be understood that the present invention does not limit this.

[0151] The embodiments of the present invention further provide an electronic device, which includes a processor and a memory:

[0152] The memory is used to store program code and transmit the program code to the processor;

[0153] The processor is configured to execute the method for constructing the circuit simulation model of the SiC MOSFET according to any embodiment of the present invention according to the instructions in the program code.

[0154] An embodiment of the present invention also provides a computer-readable storage medium for storing program code, and the program code is used to execute the method for constructing a circuit simulation model of a SiC MOSFET according to any embodiment of the present invention.

[0155] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0156] In several embodiments provided by the present invention, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, indirect couplings or communication connections of devices or units, and can be in electrical, mechanical, or other forms.

[0157] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0158] In addition, in each embodiment of the present invention, the functional units can be integrated in one processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0159] When the integrated unit 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. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs.

[0160] As described above, the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of various embodiments of the present invention.

Claims

1. A method for constructing a circuit simulation model of a SiC MOSFET, characterized in that Including: Obtaining the model circuit structure of the SiC MOSFET and the set of working data points in the third quadrant; Performing reverse current fitting based on voltage comparison on the set of working data points in the third quadrant according to a preset model expression to obtain each fitting coefficient of the model expression; Constructing a circuit simulation model of the SiC MOSFET according to the model circuit structure, the set of working data points in the third quadrant, the model expression, and each fitting coefficient.

2. The method for constructing a circuit simulation model according to claim 1, wherein The model expression includes a first reverse current expression, a second reverse current expression, and a third reverse current expression; the performing reverse current fitting based on voltage comparison on the set of working data points in the third quadrant according to a preset model expression to obtain each fitting coefficient of the model expression includes: Extracting the gate-source voltage and the threshold voltage when the SiC MOSFET operates in the third quadrant from the set of working data points in the third quadrant; Performing voltage comparison using the gate-source voltage and the threshold voltage, and based on the voltage comparison result, selecting a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression; Performing fitting on the set of working data points in the third quadrant according to the target reverse current expression to obtain each fitting coefficient of the target reverse current expression.

3. The method for constructing a circuit simulation model according to claim 2, wherein, The selecting a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression based on the voltage comparison result includes: When the gate-source voltage is less than the threshold voltage, taking the first reverse current expression as the target reverse current expression; Wherein, the first reverse current expression indicates that the reverse current in the SiC MOSFET only flows through the body diode path, and the reverse current flowing through the body diode is jointly determined by the source-drain voltage, the gate-source voltage, and the junction temperature.

4. The method for constructing a circuit simulation model according to claim 2, wherein The selecting a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression based on the voltage comparison result includes: When the gate-source voltage is greater than or equal to the threshold voltage, extracting the source-drain voltage and the knee voltage at which the body diode turns on when the SiC MOSFET operates in the third quadrant from the set of working data points in the third quadrant; Calculating the on-resistance according to the gate-source voltage and the threshold voltage, and calculating the body diode delayed turn-on voltage based on the on-resistance and the knee voltage; When the source-drain voltage is less than the body diode delayed turn-on voltage, taking the second reverse current expression as the target reverse current expression; Wherein, the second reverse current expression indicates that the body diode in the SiC MOSFET is not turned on, and the reverse current only flows through the channel current path, and the reverse current flowing through the channel is jointly determined by the source-drain voltage and the on-resistance.

5. The method for constructing a circuit simulation model according to claim 4, wherein Also including: When the source-drain voltage is greater than or equal to the body diode delayed turn-on voltage, taking the third reverse current expression as the target reverse current expression; Among them, the third reverse current expression indicates that the reverse current in the SiC MOSFET flows through both the body diode path and the channel current path simultaneously. The reverse current flowing through the body diode and the channel is jointly determined by the source-drain voltage, on-resistance, gate-source voltage, junction temperature, and body diode delayed turn-on voltage.

6. The method for constructing a circuit simulation model according to any one of claims 1 to 5, characterized in that It further includes: Performing simulation on the SiC MOSFET using the circuit simulation model, and extracting a set of simulation working data points when the SiC MOSFET operates in the third quadrant from the simulation results; Comparing the set of simulation working data points with the set of third quadrant working data points, and correcting and optimizing the model of the circuit simulation model based on the comparison result.

7. The method for constructing a circuit simulation model according to claim 6, wherein The model circuit structure includes a body diode circuit structure; the body diode circuit structure is composed of a voltage-controlled current source, an ohmic resistor, and a non-linear junction capacitor; among them, the parallel connection point of the voltage-controlled current source and the non-linear junction capacitor is connected in series to one end of the ohmic resistor.

8. A device for constructing a circuit simulation model of a SiC MOSFET, characterized in that, It includes: A data acquisition unit for acquiring the model circuit structure of the SiC MOSFET and the set of third quadrant working data points; A data fitting unit for performing reverse current fitting based on voltage comparison on the set of third quadrant working data points according to a preset model expression to obtain each fitting coefficient of the model expression; A model construction unit for constructing a circuit simulation model of the SiC MOSFET according to the model circuit structure, the set of third quadrant working data points, the model expression, and each fitting coefficient.

9. The circuit simulation model construction device according to claim 8, characterized in that, The model expression includes a first reverse current expression, a second reverse current expression, and a third reverse current expression; The data fitting unit includes: A voltage extraction unit for extracting the gate-source voltage and threshold voltage when the SiC MOSFET operates in the third quadrant from the set of third quadrant working data points; An expression selection unit for performing voltage comparison using the gate-source voltage and the threshold voltage, and selecting a target reverse current expression from the first reverse current expression, the second reverse current expression, and the third reverse current expression based on the voltage comparison result; A data fitting subunit for fitting the set of third quadrant working data points according to the target reverse current expression to obtain each fitting coefficient of the target reverse current expression.

10. The circuit simulation model construction device according to claim 9, characterized in that, The expression selection unit is specifically used for: When the gate-source voltage is less than the threshold voltage, taking the first reverse current expression as the target reverse current expression; Among them, the first reverse current expression indicates that the reverse current in the SiC MOSFET only flows through the body diode path, and the reverse current flowing through the body diode is jointly determined by the source-drain voltage, gate-source voltage, and junction temperature.

11. The device for constructing a circuit simulation model according to claim 9, wherein The expression selection unit is specifically used for: When the gate-source voltage is greater than or equal to the threshold voltage, extracting the source-drain voltage and the knee voltage of body diode turn-on when the SiC MOSFET operates in the third quadrant from the set of third quadrant working data points; Calculate the on-resistance based on the gate-source voltage and the threshold voltage, and calculate the body diode delayed turn-on voltage based on the on-resistance and the knee voltage; When the source-drain voltage is less than the body diode delayed turn-on voltage, use the second reverse current expression as the target reverse current expression; Wherein, the second reverse current expression indicates that the body diode in the SiC MOSFET is not conducting, and the reverse current only flows through the channel current path, and the reverse current flowing through the channel is jointly determined by the source-drain voltage and the on-resistance.

12. The circuit simulation model construction device according to claim 11, wherein, The expression selection unit is further specifically configured to: When the source-drain voltage is greater than or equal to the body diode delayed turn-on voltage, use the third reverse current expression as the target reverse current expression; Wherein, the third reverse current expression indicates that the reverse current in the SiC MOSFET flows through both the body diode path and the channel current path at the same time, and the reverse current flowing through the body diode and the channel is jointly determined by the source-drain voltage, the on-resistance, the gate-source voltage, the junction temperature, and the body diode delayed turn-on voltage.

13. The circuit simulation model construction device according to any one of claims 8 to 12, characterized in that Further includes: A simulation unit, configured to simulate the SiC MOSFET using the circuit simulation model, and extract a set of simulation working data points when the SiC MOSFET operates in the third quadrant from the simulation results; A data comparison unit, configured to compare the set of simulation working data points with the set of third quadrant working data points, and correct and optimize the model of the circuit simulation model based on the comparison result.

14. The circuit simulation model construction device according to claim 13, wherein The model circuit structure includes a body diode circuit structure; the body diode circuit structure is composed of a voltage-controlled current source, an ohmic resistor, and a non-linear junction capacitor; wherein, the parallel connection point of the voltage-controlled current source and the non-linear junction capacitor is connected in series at one end of the ohmic resistor.

15. An electronic device, characterized in that, The device includes a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is configured to execute the method for constructing the circuit simulation model of the SiC MOSFET according to any one of claims 1-7 based on the instructions in the program codes.

16. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store program codes, and the program codes are used to execute the method for constructing the circuit simulation model of the SiC MOSFET according to any one of claims 1-7.

Images