Method and apparatus for constructing parallel current source model for IGBT turn-off current analysis

Abstract

This application discloses a method and apparatus for constructing a parallel current source model for IGBT turn-off current analysis. The main scheme is as follows: Based on the physical nature of the IGBT turn-off current decrease process, it is revealed that it includes two synchronously occurring sub-processes (the carrier injection process and the carrier recombination reduction process corresponding to MOSFET turn-off); the IGBT turn-off current is defined as the parallel superposition of the currents (injection current and recombination current) generated by these two sub-processes; this abstract "dual current" physical theory is transformed into an equivalent circuit composed of a controlled source and a current source connected in parallel; the two sub-processes are analyzed in this way: for the first sub-process, a first relationship characterizing the dynamic evolution law of the injection current is derived; for the second sub-process, a second relationship characterizing the dynamic evolution law of the recombination current is derived; finally, by combining these two relationships, a parallel current source model for quantitatively characterizing the IGBT turn-off current decrease process is constructed.

Description

Technical Field

[0001] This application relates to the field of IGBT characteristic analysis technology, and in particular to a method and apparatus for constructing a parallel current source model for IGBT turn-off current analysis. Background Technology

[0002] An insulated-gate bipolar transistor (IGBT) is a composite power semiconductor device that combines the advantages of a MOSFET (MOSFET) ("gate voltage control and low drive power") with the advantages of a bipolar transistor (BPT) ("low on-state voltage and high current carrying capacity"). The core structure of an IGBT is a MOSFET gate control unit + a bipolar transistor conduction unit. It is widely used in medium- and high-voltage, high-current power electronic systems such as motor drives and photovoltaic inverters.

[0003] The IGBT turn-off process refers to the complete dynamic process by which the IGBT, under the action of the gate control signal, gradually transitions from a conducting state carrying large current and low on-state voltage drop to a turn-off state with near-zero current and high voltage. The turn-off current decrease process is a critical stage in the turn-off process because it directly determines the safety of the IGBT device (the rate of current decrease and the parasitic inductance of the circuit can easily generate surge voltages, and runaway may damage the device), affects system efficiency (the overlap characteristics of current and voltage determine the magnitude of turn-off losses), and also determines the stability of the entire power electronic system (a smooth transfer of inductive load current from the IGBT to the freewheeling diode is required to avoid system oscillations or waveform distortion).

[0004] Currently, in the analysis and research of the IGBT turn-off current reduction process, the traditional method decomposes the process into two independent stages: the first stage is the MOSFET turn-off process, in which the collector current follows the classical control relationship between the gate and emitter voltages; the second stage is the carrier recombination reduction process, that is, after the MOSFET is completely turned off, the collector current is dominated only by the carrier recombination law.

[0005] However, while this kind of separation simplifies the analysis of the IGBT turn-off current decrease process to some extent, the assumption is too idealistic and does not conform to the physical nature of actual operating conditions (such as the two stages mentioned above, which are not completely independent but occur simultaneously and influence each other). Ultimately, the analysis results of traditional methods cannot accurately reflect the real physical mechanism of the process. Summary of the Invention

[0006] This application provides a method and apparatus for constructing a parallel current source model for IGBT turn-off current analysis. The main purpose is to break the segmented assumption based on "two stages" and establish an analysis model (parallel current source model) that can reflect the synchronicity of the MOSFET turn-off process and the carrier recombination reduction process, thereby making the analysis of IGBT turn-off current more accurate and more in line with physical reality.

[0007] To achieve the above objectives, this application mainly provides the following technical solutions: The first aspect of this application provides a method for constructing a parallel current source model for IGBT turn-off current analysis, the method comprising: Based on the fact that the IGBT turn-off current decrease process includes a first sub-process and a second sub-process that occur simultaneously, the IGBT turn-off current is determined to include the injection current generated by the first sub-process and the recombination current generated by the second sub-process; the first sub-process is the carrier injection process corresponding to MOSFET turn-off; the second sub-process is the carrier recombination reduction process. An equivalent circuit for the IGBT turn-off process is established by equating the IGBT to a parallel structure of the controlled source corresponding to the injected current and the current source corresponding to the composite current. For the first sub-process, based on the control relationship between the gate and emitter voltages on the injected current, a first relationship characterizing the dynamic evolution law of the injected current is obtained; For the second sub-process, the equivalent circuit is used to correct the dynamic evolution process of the charge carriers, and a dynamic correlation between the injected current and the total number of charge carriers is established to obtain a second relationship that characterizes the dynamic evolution law of the composite current. Based on the first relationship corresponding to the injected current and the second relationship corresponding to the composite current, a parallel current source model is constructed. The parallel current source model is used to quantitatively characterize the IGBT turn-off current decrease process.

[0008] A second aspect of this application provides a device for constructing a parallel current source model for IGBT turn-off current analysis, the device comprising: The determining unit is used to determine the IGBT turn-off current, including the injection current generated by the first sub-process and the recombination current generated by the second sub-process, based on the IGBT turn-off current decrease process including a first sub-process and a second sub-process that occur simultaneously; the first sub-process is a carrier injection process corresponding to MOSFET turn-off; the second sub-process is a carrier recombination reduction process. The first building unit is used to establish an equivalent circuit for the IGBT turn-off process by equating the IGBT to a parallel structure of the controlled source corresponding to the injected current and the current source corresponding to the composite current. The first acquisition unit is used to obtain, for the first sub-process, a first relationship characterizing the dynamic evolution law of the injection current based on the control relationship between the gate and emitter voltages on the injection current; The second acquisition unit is used to modify the dynamic evolution process of the charge carriers using the equivalent circuit for the second sub-process, establish the dynamic correlation between the injected current and the total number of charge carriers, and obtain the second relationship characterizing the dynamic evolution law of the composite current. The second construction unit is used to construct a parallel current source model based on the first relationship corresponding to the injected current and the second relationship corresponding to the composite current. The parallel current source model is used to quantitatively characterize the IGBT turn-off current decrease process.

[0009] A third aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the parallel current source model construction method for IGBT turn-off current analysis as described above.

[0010] A fourth aspect of this application provides an electronic device, the device including at least one processor, and at least one memory and bus connected to the processor; The processor and the memory communicate with each other via the bus. The processor is used to call program instructions in the memory to execute the parallel current source model construction method for IGBT turn-off current analysis as described above.

[0011] By employing the above-described technical solution, the technical solution provided in this application has at least the following advantages: This application provides a method and apparatus for constructing a parallel current source model for IGBT turn-off current analysis. Based on the physical nature of the IGBT turn-off current decrease process, it reveals that it includes two synchronously occurring sub-processes: one is the carrier injection process corresponding to MOSFET turn-off, and the other is the carrier recombination reduction process. Accordingly, this application defines the IGBT turn-off current as the parallel superposition of the currents (injection current and recombination current) generated by these two sub-processes, and transforms this abstract "dual-current" physical theory into an equivalent circuit composed of a controlled source and a current source connected in parallel, thereby transforming the complex physical process into an engineering problem that can be analyzed and calculated using circuit theory. On this basis, this application further analyzes the two sub-processes: for the first sub-process, a first relationship characterizing the dynamic evolution law of the injection current is derived; for the second sub-process, a second relationship characterizing the dynamic evolution law of the recombination current is derived. Finally, by combining these two relationships, a parallel current source model for quantitatively characterizing the IGBT turn-off current decrease process is constructed.

[0012] Compared to existing technologies, traditional analysis methods model the IGBT turn-off current decrease process as two separate stages, which fails to accurately reflect the true physical mechanism of the process. This application breaks away from this segmented assumption based on two stages and establishes an analysis model (parallel current source model) that reflects the synchronicity between the MOSFET turn-off process and the carrier recombination reduction process, thereby making the analysis of IGBT turn-off current more accurate and closer to physical reality.

[0013] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0014] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a method for constructing a parallel current source model for IGBT turn-off current analysis provided in this application embodiment; Figure 2 The inductive load half-bridge circuit structure provided in the embodiments of this application; Figure 3 The half-bridge equivalent circuit for the IGBT turn-off process provided in the embodiments of this application; Figure 4 A block diagram of a parallel current source model construction device for IGBT turn-off current analysis provided in this application embodiment; Figure 5 A block diagram of another parallel current source model construction device for IGBT turn-off current analysis provided in this application embodiment. Detailed Implementation

[0015] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0016] In the analysis and study of the IGBT turn-off current decrease process, traditional methods decompose this process into two independent stages: the first stage is the turn-off process of the insulated-gate field-effect transistor (MOSFET), in which the collector current follows the classical control relationship between the gate and emitter voltages; the second stage is the carrier recombination reduction process, that is, after the MOSFET is completely turned off, the collector current is dominated only by the carrier recombination law. Specifically, the explanation includes the following: In the first stage, the "MOSFET turn-off process," the decrease in the IGBT's turn-off current is simplified to a current change controlled solely by the MOSFET gate. The IGBT's gate-emitter voltage is the control signal: as the gate-emitter voltage gradually decreases from the turn-on voltage, the electric field between the gate and emitter weakens, the conductivity of the MOS channel gradually decreases (the channel narrows), leading to a reduction in the number of charge carriers injected into the IGBT's drift region, ultimately manifested as a decrease in the collector current.

[0017] Specifically, the classical control relationship between the gate-emitter voltage and the collector current in the "MOSFET turn-off process" is shown in formula (1): (1); where, i C For collector current, u GE This is the gate-emitter voltage; μ n For carrier mobility, v cha For channel carrier saturation velocity, l cha Channel length and width c ox Channel capacitance; u GE Gate-emitter voltage, U T This is the gate turn-on voltage; α pnp The transfer factor of the internal transistors of the IGBT is a factor related to the effective width of the drift region. w m The relevant quantities. The current control relationship in this first stage is described as follows: based on the classic MOSFET gate voltage-channel current law, combined with the amplification characteristics of the IGBT internal bipolar transistor, it describes... u GE During descent, i C The process of how the effective gate voltage changes with the square of the effective gate voltage.

[0018] In the second stage, the "carrier recombination reduction process," assuming the MOSFET is completely turned off (carrier injection stops), the remaining carriers in the IGBT drift region will be spontaneously consumed through "recombination" (electrons and holes combine, reducing the number of carriers), leading to a continuous decrease in collector current until it reaches zero. The core logic of the second stage is: after the MOSFET is turned off, no new carriers are injected into the drift region externally, and the existing carriers in the drift region (accumulated during the turn-on phase) will gradually disappear according to the "natural law of carrier recombination," with the current determined solely by the carrier recombination process.

[0019] Specifically, the process of "spontaneous recombination of charge carriers leading to exponential decay of current after the MOSFET is completely turned off" is described by the following formulas (2)-(4). The differential equation for charge carrier recombination is shown in formula (2). (2); where, Q N dQ represents the carrier charge in the IGBT drift region, τ represents the carrier recombination lifetime, and dQ N / dt represents the rate of change of carrier charge over time. This differential equation describes the change in carrier charge in the drift region after the MOSFET is completely turned off: the rate of change (consumption rate) of carrier charge is proportional to the current charge, with a proportionality constant of 1 / τ (reflecting the rate of recombination).

[0020] At t=0, Q N =Q0. Solving the differential equation (2) above, we obtain the following expression (3), which is used to characterize the variation of the charge carrier quantity. (3); among which, Q N The carrier charge in the IGBT drift region, Q 0 represents the initial carrier charge in the drift region at time t=0 (the moment the MOSFET is completely turned off), and t represents the time taken from the moment the MOSFET is completely turned off; τ represents the carrier recombination lifetime; this is the result of solving formula (2), which describes the "law of change of carrier charge with time": as time goes by, the carrier charge decreases in an "exponential decay" manner (the larger t is, the lower the carrier charge becomes). Q N The closer to 0).

[0021] The collector current corresponding to carrier recombination is obtained and expressed by the following expression (4): (4); among which, i C For total shutdown current, Q N The carrier charge in the IGBT drift region, Q0 represents the initial carrier charge in the drift region at time t=0 (the moment when the MOSFET is completely turned off), t represents the time taken from the moment the MOSFET is completely turned off; τ represents the carrier recombination lifetime; this expression (4) quantitatively describes the "variation law of collector current with time in the second stage": the current also decays exponentially, and the initial current is Q 0 / τ eventually drops to zero as carriers are depleted.

[0022] However, traditional methods assume that the first stage occurs first, followed by the second stage. That is, the MOSFET is turned off first (carrier injection completely stops), and then the carrier recombination process begins; the two stages proceed sequentially. But in actual physical processes, these two stages occur simultaneously. Therefore, the ideal assumptions of traditional methods cannot reflect the actual physical nature of "synchronous occurrence + mutual influence," leading to significant deviations between calculated current variation patterns and carrier concentrations and actual operating conditions.

[0023] Based on the above considerations, this application provides a method for constructing a parallel current source model for IGBT turn-off current analysis. The goal is to establish an analytical model that reflects the synchronicity between the MOSFET turn-off process and the carrier recombination reduction process, thereby achieving a more accurate and realistic analysis of the IGBT turn-off current decrease process. Figure 1 As shown, the following specific steps are provided in this embodiment of the invention: (It should be noted that the step numbers in this embodiment are only used to distinguish the operation links and do not constitute a limitation on the execution order of each step).

[0024] Step 101: Based on the IGBT turn-off current decrease process, which includes a first sub-process and a second sub-process that occur simultaneously, determine that the IGBT turn-off current includes the injection current generated by the first sub-process and the composite current generated by the second sub-process; the first sub-process is the carrier injection process corresponding to the MOSFET turn-off; the second sub-process is the carrier recombination reduction process.

[0025] It should be noted that, in order to facilitate the distinction of the different sub-processes included in the “IGBT turn-off current decrease process”, the embodiments of this application use the terms “first” and “second” for identification, and “first” and “second” only serve an identification purpose and do not indicate any order, time sequence or difference in importance.

[0026] In the embodiments of this application, the "carrier injection process corresponding to MOSFET turn-off" and "carrier recombination reduction process" included in the IGBT turn-off current decrease process are defined as occurring synchronously, based on their actual physical mechanisms. That is, physically, the carrier injection and recombination behaviors are carried out synchronously within the same time period, rather than being two independent stages that occur sequentially.

[0027] Furthermore, based on the fact that the first and second sub-processes occur synchronously, the IGBT turn-off current is determined to be the parallel superposition of the injected current and the composite current. Specific explanations include the following: The embodiments of this application employ an inductive load half-bridge circuit structure (such as...). Figure 2 This provides a circuit basis for analyzing the IGBT turn-off current decrease process. Figure 2 The parameters are defined as follows: u chip,CE and u chip,F These are the terminal voltages of the IGBT chip and the freewheeling diode (FWD) chip, respectively. u CE and u F These are the external terminal voltages for the IGBT and FWD devices, respectively. L s,1 , L s,2 , L s,CE , L s,F These are the parasitic inductance parameters of each loop in the circuit, where... L s,CE The parasitic inductance inside the IGBT device. L s,F This refers to the parasitic inductance inside the FWD device. Figure 2 This is a typical inductive load half-bridge circuit with an "upper arm FWD + lower arm IGBT" configuration, and the connection relationship is as follows: DC power supply and capacitor: The positive terminal of the DC power supply UDC is connected to the positive terminal of the capacitor C, and the negative terminal of the capacitor C is connected to the negative terminal of the power supply, forming a DC bus (the capacitor acts as a filter).

[0028] Upper arm (FWD branch): The anode of the FWD chip is connected to the parasitic inductor. L s,2 At one end, the cathode of the FWD chip is connected to a parasitic inductor. L s,1 One end; L s,1 The other end is connected to the positive terminal of the DC bus; L s,2The other end is connected to an inductive load ( I load One end of ).

[0029] Lower arm (IGBT branch): The collector (C) of the IGBT chip is connected to the parasitic inductor. L s,CE One end, L s,CE The other end is connected to the other end of the inductive load; the emitter (E) of the IGBT chip is connected to the negative terminal of the DC bus; the gate (G) of the IGBT chip is the control terminal, receiving the gate voltage. u GE (G is connected to the positive terminal of uGE, E is connected to...) u GE (negative electrode).

[0030] Current path: When the IGBT is turned on, the current... i C From the positive terminal of the DC bus → L s,1 →Inductive load→ L s,CE →IGBT (C→E)→DC bus negative terminal; When the IGBT is turned off, the inductive load current IL cannot change abruptly and will be transferred to the FWD branch: current i F From inductive load → L s,2 →FWD (Anode → Cathode)→ L s,1 →Inductive loads form a freewheeling loop.

[0031] like Figure 2 During the IGBT's turn-on current rise phase, charge carriers begin to be injected into the device. However, at this time, the collector-emitter voltage is still much higher than the on-state voltage drop, and the conductivity modulation effect in the drift region is weak. As the turn-off current decreases, a large number of charge carriers remain in the drift region. As the gate voltage decreases, the gate channel gradually narrows, and the number of electrons injected into the drift region from the gate decreases accordingly. At this point, the number of charge carriers injected into the drift region is insufficient to counteract the recombination of charge carriers within the drift region, causing the dynamic balance of charge carriers in the drift region to be disrupted, and the total number of remaining charge carriers continues to decrease.

[0032] Therefore, the IGBT's turn-off current decrease process can be decomposed into two synchronously occurring current components: carrier injection current and carrier recombination current; among which, the carrier injection current ( i C1 The dynamic characteristics of the current corresponding to the MOSFET turn-off process can be described by formula (1); where, Carrier recombination current ( i C2): This corresponds to the current generated by the reduction of carrier recombination in the drift region. Therefore, the total turn-off current iC is the superposition of the two currents mentioned above, satisfying the following formula (5): i C =i C1 + i C2 (5); among which, i C For collector current, i C1 The injection current generated in the first sub-process i C2 The composite current generated by the second sub-process. Formula (5) defines the core framework of the "parallel current source model" constructed in the embodiments of this application: the turn-off current of the IGBT is essentially the parallel superposition of the injected current and the composite current, which makes this model break the assumption of splitting the turn-off process based on "two stages".

[0033] Step 102: By equating the IGBT to a parallel structure of the controlled source corresponding to the injected current and the current source corresponding to the composite current, an equivalent circuit for the IGBT turn-off process is established.

[0034] Step 101, based on the innovative concept of "dual synchronous subprocess" proposed in Step 101, transforms the abstract "dual current" physical theory into an equivalent circuit model consisting of a controlled source and a current source connected in parallel. This transforms the complex physical process into an engineering problem that can be analyzed and calculated using circuit theory.

[0035] Specifically, in a pre-constructed inductive load half-bridge circuit structure (such as...) Figure 2 In this paper, based on the IGBT device itself, the dynamic turn-off behavior of the IGBT is abstracted as a parallel combination of the controlled source corresponding to the injected current and the current source corresponding to the composite current. Based on the half-bridge circuit structure and parallel combination, by integrating at least the freewheeling diode and the loop parasitic inductance, the half-bridge equivalent circuit of the IGBT turn-off process is obtained (e.g., Figure 3 ).

[0036] In the analysis of the IGBT turn-off current decrease process, Figure 1, which reflects the actual circuit working principle, can be further abstracted into a model embodying the core idea of ​​the "parallel current source model" in the embodiments of this application. Figure 2 (Equivalent circuit of half-bridge circuit during turn-off process), thus more clearly showing the parallel superposition relationship between injected current and composite current.

[0037] Figure 3As a circuit visualization representation of formula (5), the abstract "parallel current source" model is transformed into an intuitive equivalent circuit, clearly demonstrating the core logic that the IGBT turn-off current is composed of the injection current and the composite current in parallel. At the same time, the parasitic inductance, FWD and other key components of the original circuit are retained, and a circuit-level analysis framework is built for the mathematical modeling of subsequent steps 103-105.

[0038] Figure 3 shows the equivalent circuit of the turn-off process, with the connection relationships based on... Figure 2 This is a simplified version, designed to represent the parallel connection of injected current and composite current. Specific explanations include the following: IGBT branch (lower arm): IGBT is equivalent to " i C1 (Controlled source) + i C2 The two current sources are connected in parallel, with their common terminal connected to the collector (C) and emitter (E) of the IGBT; the collector (C) of the IGBT is connected to the parasitic inductor. L s,CE One end, L s,CE The other end is connected to a DC power supply. U DC The negative terminal of the IGBT; the emitter (E) of the IGBT is connected to the DC power supply. U DC The positive terminal; IGBT chip voltage u chip,CE It is connected in parallel at both ends of the equivalent structure of IGBT.

[0039] FWD branch (upper bridge arm): FWD is equivalent to its chip voltage. u chip,F The corresponding controlled source is connected in parallel with the parasitic inductor. L s,F Both ends; L s,F One end is connected to a parasitic inductor L s,2 The other end is connected to a DC power supply. U DC The positive pole.

[0040] Circuits and Currents: Parasitic Inductance L s,1 Connect the positive terminal of the DC power supply to the FWD branch; parasitic inductance L s,2 Connect the FWD branch to the inductive load current I L The node; when turned off, the current i C ( i C1 +i C2 ) flows out from the IGBT branch, i F The current flowing out from the FWD branch corresponds to the load current I. L .

[0041] Step 103: For the first sub-process, based on the control relationship between the gate and emitter voltages on the injection current, the first relationship characterizing the dynamic evolution law of the injection current is obtained.

[0042] The injected current is essentially determined by the MOSFET portion of the IGBT. The physical mechanism of this portion, whether in the conventional method or the parallel current source model constructed in this embodiment, is based on the control of the channel current by the gate voltage. Therefore, the formula (1) for the "first stage MOSFET turn-off process" in the conventional method can be directly used to characterize the first relationship corresponding to the dynamic evolution law of the injected current generated by the first sub-process in this embodiment.

[0043] Specifically, this step can be further broken down into: establishing a control relationship between the gate and emitter voltages and the injection current based on the gate control characteristics of the MOSFET; the control relationship is used to characterize how changes in the gate voltage drive the initial changes in the injection current; based on the control relationship, deriving a dynamic evolution expression of the injection current over time according to the charging and discharging effect of the gate capacitance during the turn-off process; and determining the first relationship corresponding to the dynamic evolution law of the injection current based on the dynamic evolution expression of the injection current over time.

[0044] It should be noted that, in order to distinguish the different "current dynamic evolution laws" obtained in steps 103 and 104, the embodiments of this application use the terms "first" and "second" for identification, that is, to obtain "the first relationship corresponding to the dynamic evolution law of the injected current" and "the second relationship corresponding to the dynamic evolution law of the composite current". Here, the terms "first" and "second" only serve as identification and do not indicate any order, time sequence or difference in importance.

[0045] Step 104: For the second sub-process, the dynamic evolution process of the charge carriers is corrected using the equivalent circuit, and a dynamic correlation between the injected current and the total amount of charge carriers is established to obtain the second relationship characterizing the dynamic evolution law of the composite current.

[0046] This step addresses the physical process of carrier recombination, modifying the dynamic evolution of carriers in the second stage of the traditional method, the "carrier recombination reduction process," establishing a dynamic correlation between the injection current and the recombination current, and then deriving the dynamic evolution law of the recombination current over time. This provides a dynamic mathematical expression describing the "second sub-process" for the parallel current source model to be constructed in the embodiments of this application.

[0047] Specifically, this step is further refined into steps (1)-(4); (1) Under the assumption that the first and second sub-processes are independent of each other, a traditional carrier decay model corresponding to the dynamic evolution law of recombination current is established. For example, the second stage of the traditional method, "carrier recombination reduction process", uses formulas (2)-(4) to describe the process of "after the MOSFET is completely turned off, the spontaneous recombination of carriers leads to the exponential decay of current", which is the traditional carrier decay model corresponding to the dynamic evolution law of recombination current in the traditional method.

[0048] (2) The traditional carrier decay model is modified by using the equivalent circuit to obtain a carrier evolution model applicable to the scenario where the first subprocess and the second subprocess occur simultaneously.

[0049] Considering that MOSFET turn-off is a gradual process (the injected current gradually decreases over time), this step modifies the differential equation of carrier change in the traditional carrier decay model, incorporating the dynamic influence of the injected current on the total number of carriers into the model. Specifically, formula (6) is used to replace formula (2) in the traditional model, thereby reflecting the supplementary role of carrier injection behavior on the change in the total number of carriers, and thus more accurately reflecting the physical nature of the synchronous occurrence of the two sub-processes.

[0050] When considering the MOSFET turn-off process, the carrier change law in the drift region is as shown in formula (6): (6); i C1 For injecting current, Q N The carrier charge in the IGBT drift region, Q 0 represents the initial carrier charge in the drift region at time t=0 (when the MOSFET is completely turned off), and t represents the time taken from when the MOSFET is completely turned off; τ represents the carrier recombination lifetime; this expression (6) reflects the supplementary role of carrier injection behavior on the change in the total amount of carriers, and is the mathematical basis for realizing the synchronization process of the first subprocess and the second subprocess in the embodiments of this application.

[0051] (3) Based on the modified carrier evolution model and the physical relationship between carrier recombination rate and current, the dynamic evolution expression of recombination current over time is derived.

[0052] (4) Based on the dynamic evolution expression of the composite current over time, determine the second relationship corresponding to the dynamic evolution law of the composite current.

[0053] As in (3)-(4), the goal is to solve the modified differential equation obtained in (2) (as in formula (6)). First, the carrier charge Q is obtained.N Based on the pattern of change over time, the composite current is derived. i C2 The expression for the dynamic evolution over time is derived in the following formulas (7) and (8): Assuming the MOSFET turn-off process is instantaneous, i C1 =0, formula (6) returns to the form of formula (2). Solving formula (6) yields: (7); This is the analytical solution to formula (6), which quantitatively describes the injection current. i C1 The dynamic influence of the carrier charge quantity over time.

[0054] Current in the carrier recombination region i C2 for: (8); This formula is derived from Q N Differentiating with respect to time clarifies the composite current. i C2 With injected current i C1 The dynamic relationship between them is different from the traditional view. i C2 and i C1 The assumptions that they are mutually independent are completely different.

[0055] From formula (8), we can see that, i C2 Not independent, but related to i C1 This is because the injection of external charge affects the net change in carriers in the drift region.

[0056] Step 105: Based on the first relationship corresponding to the injected current and the second relationship corresponding to the composite current, construct a parallel current source model. The parallel current source model is used to quantitatively characterize the IGBT turn-off current decrease process.

[0057] This step involves integrating the final expression for the turn-off current and completing model quantization. It includes: integrating the first relationship characterizing the dynamic evolution of the injected current with the second relationship characterizing the dynamic evolution of the composite current to establish a parallel superposition relationship between the total turn-off current and the currents of the two sub-processes; based on the parallel superposition relationship and combined with the structural characteristics of the equivalent circuit, constructing a parallel current source model that quantitatively characterizes the IGBT turn-off current decrease process.

[0058] Specifically, this step involves: combining the total current parallel superposition relationship established in step 101 (as shown in formula (5)), and calculating the composite current derived in step 104. i C2 Substituting the expression and rearranging it, we obtain the turn-off current. i C The complete mathematical expression of is finally obtained as formula (9).

[0059] (9); This step completes the final quantization of the "parallel current source model" and obtains the mathematical form of the turn-off current that can accurately describe the synchronous occurrence of the twin processes.

[0060] In the embodiments of this application, in order to make the formulas (1) to (9) involved in steps 101 to 105 clearer, the variables involved in each formula are explained again, and the specific role of each formula in the method of this embodiment is summarized again: The variables appearing in formulas (1)-(9) include: i C This is the total collector current when the IGBT is turned off; i C1 This is the injection current (the first subprocess current, determined by the MOSFET section). i C1 This is the recombination current (the second subprocess current, determined by carrier recombination); Q N τ represents the carrier charge in the IGBT base region; Q0 represents the initial carrier charge at the initial turn-off time (t=0); t represents the time variable; and τ represents the carrier recombination lifetime (time constant). μ n Electron mobility; v cha This is the saturation velocity of the channel carriers; l cha This refers to the length of the channel; c ox The capacitance per unit area of ​​the oxide layer; u GE This is the gate-emitter voltage; U T This is the threshold voltage of the MOSFET; α pnp This represents the current gain of the PNP transistor inside the IGBT.

[0061] In this embodiment of the application, formula (1) represents the dynamic evolution law of the injected current, which serves to describe the injected current. i C1The dynamic process of changing with gate voltage; Formulas (2)-(4) describe the process of "spontaneous recombination of charge carriers leading to exponential decay of current after the MOSFET is completely turned off"; Formula (5) is a characterization of the parallel superposition relationship of total current; Formula (6) is a modified differential equation of charge carrier change, which characterizes the modified model that incorporates the dynamic influence of injected current and establishes the mathematical basis for the synchronization process; Formula (7) is the analytical solution of Formula (6), which describes the change of charge carrier charge under the influence of injected current; Formula (8) is the dynamic expression of recombination current, which characterizes the dynamic relationship between recombination current and injected current; Formula (9) is the final expression of turn-off current, which serves to integrate and obtain the complete turn-off current expression, thus completing the quantity of the "parallel current source model".

[0062] In some modified embodiments, for the parallel current source model obtained in steps 101-105, this application embodiment can also conduct simulation analysis and physical experimental tests to obtain measured data of IGBT turn-off characteristics under various operating conditions such as different voltages, currents, and temperatures. Based on this multi-dimensional operating condition data, a comprehensive validity verification of the parallel current source model constructed in this application is carried out. By comparing and analyzing the turn-off current calculation results output by the model with the measured data, it is verified whether the constructed model can accurately and objectively reflect the real dynamic change characteristics of IGBT turn-off current under various different actual application operating conditions, ensuring the accuracy, applicability, and engineering practicality of the model.

[0063] Furthermore, as a response to the above Figure 1 To implement the method shown, this application provides a device for constructing a parallel current source model for IGBT turn-off current analysis. This device embodiment corresponds to the aforementioned method embodiment. For ease of reading, this device embodiment will not repeat the details of the aforementioned method embodiment, but it should be clear that the device in this embodiment can implement all the contents of the aforementioned method embodiment. This device is applied to an analysis model (parallel current source model) that reflects the synchronicity of the MOSFET turn-off process and the carrier recombination reduction process, specifically as follows... Figure 4 As shown, the device includes: The determining unit 21 is used to determine the IGBT turn-off current, including the injection current generated by the first sub-process and the recombination current generated by the second sub-process, based on the IGBT turn-off current decrease process including the synchronously occurring first sub-process and second sub-process; the first sub-process is the carrier injection process corresponding to MOSFET turn-off; the second sub-process is the carrier recombination reduction process. The first building unit 22 is used to establish an equivalent circuit for the IGBT turn-off process by equating the IGBT to a parallel structure of the controlled source corresponding to the injected current and the current source corresponding to the composite current. The first acquisition unit 23 is used to obtain, for the first sub-process, a first relationship characterizing the dynamic evolution law of the injection current based on the control relationship between the gate and emitter voltages on the injection current; The second acquisition unit 24 is used to modify the dynamic evolution process of the charge carriers using the equivalent circuit for the second sub-process, establish the dynamic correlation between the injected current and the total number of charge carriers, and obtain the second relationship characterizing the dynamic evolution law of the composite current. The second construction unit 25 is used to construct a parallel current source model based on the first relationship corresponding to the injected current and the second relationship corresponding to the composite current. The parallel current source model is used to quantitatively characterize the IGBT turn-off current decrease process.

[0064] Furthermore, the determining unit 21 is also configured to: after determining that the IGBT turn-off current includes the injection current generated by the first sub-process and the composite current generated by the second sub-process, based on the fact that the first sub-process and the second sub-process occur synchronously, determine that the IGBT turn-off current is the parallel superposition of the injection current and the composite current.

[0065] Furthermore, the first building unit 22 is specifically used to: in the pre-built inductive load half-bridge circuit structure, based on the IGBT device itself, abstract the dynamic turn-off behavior of the IGBT as a parallel combination of the controlled source corresponding to the injected current and the current source corresponding to the composite current; based on the half-bridge circuit structure and the parallel combination, by integrating at least a freewheeling diode and a loop parasitic inductance, obtain the equivalent circuit of the IGBT turn-off process.

[0066] Furthermore, the first acquisition unit 23 is specifically used to: establish a control relationship between the gate and emitter voltages and the injection current based on the gate control characteristics of the MOSFET, wherein the control relationship is used to characterize how the gate voltage change drives the initial change of the injection current; based on the control relationship, derive a dynamic evolution expression of the injection current changing with time according to the charging and discharging effect of the gate capacitance during the turn-off process; and determine the first relationship corresponding to the dynamic evolution law of the injection current according to the dynamic evolution expression of the injection current changing with time.

[0067] Furthermore, the second acquisition unit 24 is specifically used for: establishing a traditional carrier decay model corresponding to the dynamic evolution law of the recombination current under the assumption that the first sub-process and the second sub-process are independent of each other; modifying the traditional carrier decay model using the equivalent circuit to obtain a carrier evolution model applicable to the scenario where the first sub-process and the second sub-process occur simultaneously; deriving a dynamic evolution expression of the recombination current changing with time based on the modified carrier evolution model and the physical relationship between the carrier recombination rate and the current; and determining the second relationship corresponding to the dynamic evolution law of the recombination current according to the dynamic evolution expression of the recombination current changing with time.

[0068] Furthermore, the second construction unit 25 is specifically used to: integrate the first relationship characterizing the dynamic evolution law of the injected current with the second relationship characterizing the dynamic evolution law of the composite current to establish a parallel superposition relationship between the total turn-off current and the two sub-process currents; based on the parallel superposition relationship and combined with the structural characteristics of the equivalent circuit, construct a parallel current source model that quantitatively characterizes the IGBT turn-off current decrease process.

[0069] Furthermore, such as Figure 5 As shown, the device includes a verification unit 26, used to verify whether the parallel current source model reflects the dynamic characteristics of the IGBT turn-off current under different operating conditions using simulation or experimental data.

[0070] The parallel current source model construction device for IGBT turn-off current analysis provided in this application includes a processor and a memory. The aforementioned determination unit, first construction unit, first acquisition unit, second acquisition unit, and second construction unit are all stored in the memory as program units, and the processor executes the aforementioned program units stored in the memory to realize the corresponding functions.

[0071] The processor contains a core, which retrieves the corresponding program unit from memory. One or more cores can be configured. By adjusting the core parameters, this breaks the segmented assumption based on "two consecutive stages," establishing an analytical model (parallel current source model) that reflects the synchronicity of the MOSFET turn-off process and the carrier recombination reduction process. This makes the analysis of IGBT turn-off current more accurate and closer to physical reality.

[0072] This application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the parallel current source model construction method for IGBT turn-off current analysis as described above.

[0073] This application provides an electronic device, which includes at least one processor, at least one memory and a bus connected to the processor; wherein the processor and the memory communicate with each other through the bus; the processor is used to call program instructions in the memory to execute the parallel current source model construction method for IGBT turn-off current analysis as described above.

[0074] This application also provides a computer program product that, when executed on a data processing device, is suitable for executing the steps of a method for constructing a parallel current source model with IGBT turn-off current analysis.

[0075] 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.

[0076] In a typical configuration, the device includes one or more processors (CPUs), memory, and a bus. The device may also include input / output interfaces, network interfaces, etc.

[0077] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM, and memory includes at least one memory chip. Memory is an example of computer-readable media.

[0078] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0079] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0080] 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.

[0081] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for constructing a parallel current source model for IGBT turn-off current analysis, characterized in that, The method includes: Based on the fact that the IGBT turn-off current decrease process includes a first sub-process and a second sub-process that occur simultaneously, the IGBT turn-off current is determined to include the injection current generated by the first sub-process and the recombination current generated by the second sub-process; the first sub-process is the carrier injection process corresponding to MOSFET turn-off; the second sub-process is the carrier recombination reduction process. An equivalent circuit for the IGBT turn-off process is established by equating the IGBT to a parallel structure of the controlled source corresponding to the injected current and the current source corresponding to the composite current. For the first sub-process, based on the control relationship between the gate and emitter voltages on the injected current, a first relationship characterizing the dynamic evolution law of the injected current is obtained; For the second sub-process, the equivalent circuit is used to correct the dynamic evolution process of the charge carriers, and a dynamic correlation between the injected current and the total number of charge carriers is established to obtain a second relationship that characterizes the dynamic evolution law of the composite current. Based on the first relationship corresponding to the injected current and the second relationship corresponding to the composite current, a parallel current source model is constructed. The parallel current source model is used to quantitatively characterize the IGBT turn-off current decrease process.

2. The method according to claim 1, characterized in that, After determining that the IGBT turn-off current includes the injection current generated by the first sub-process and the composite current generated by the second sub-process, the method further includes: Based on the fact that the first sub-process and the second sub-process occur synchronously, the IGBT turn-off current is determined to be the parallel superposition of the injected current and the composite current.

3. The method according to claim 2, characterized in that, The equivalent circuit for the IGBT turn-off process is established by equating the IGBT to a parallel structure of the controlled source corresponding to the injected current and the current source corresponding to the composite current, including: In the pre-constructed inductive load half-bridge circuit structure, based on the IGBT device itself, the dynamic turn-off behavior of the IGBT is abstracted as a parallel combination of the controlled source corresponding to the injected current and the current source corresponding to the composite current. Based on the half-bridge circuit structure and the parallel combination, by integrating at least a freewheeling diode and a loop parasitic inductance, an equivalent circuit for the IGBT turn-off process is obtained.

4. The method according to any one of claims 1 to 3, characterized in that, For the first sub-process, based on the control relationship between the gate and emitter voltages on the injected current, a first relationship characterizing the dynamic evolution law of the injected current is obtained, including: Based on the gate control characteristics of MOSFET, a control relationship between the gate and emitter voltages and the injection current is established. This control relationship is used to characterize how changes in the gate voltage drive initial changes in the injection current. Based on the control relationship, and according to the charging and discharging effect of the gate capacitance during the turn-off process, a dynamic evolution expression of the injection current changing with time is derived. Based on the dynamic evolution expression of the injected current over time, the first relationship corresponding to the dynamic evolution law of the injected current is determined.

5. The method according to any one of claims 1 to 3, characterized in that, For the second sub-process, the equivalent circuit is used to correct the dynamic evolution process of the charge carriers, and a dynamic correlation between the injected current and the total number of charge carriers is established to obtain a second relationship characterizing the dynamic evolution law of the recombination current, including: Assuming that the first sub-process and the second sub-process are independent of each other, a traditional carrier decay model corresponding to the dynamic evolution law of the composite current is established. The traditional carrier decay model is modified using the equivalent circuit to obtain a carrier evolution model suitable for the scenario where the first sub-process and the second sub-process occur simultaneously. Based on the modified carrier evolution model, and combined with the physical relationship between carrier recombination rate and current, a dynamic evolution expression of recombination current over time is derived. Based on the dynamic evolution expression of the composite current over time, the second relationship corresponding to the dynamic evolution law of the composite current is determined.

6. The method according to any one of claims 1 to 3, characterized in that, The step of constructing a parallel current source model based on the first relationship corresponding to the injected current and the second relationship corresponding to the composite current includes: The first relationship characterizing the dynamic evolution of the injected current is integrated with the second relationship characterizing the dynamic evolution of the composite current to establish a parallel superposition relationship between the total turn-off current and the currents of the two sub-processes. Based on the aforementioned parallel superposition relationship and combined with the structural characteristics of the equivalent circuit, a parallel current source model is constructed to quantitatively characterize the IGBT turn-off current decrease process.

7. The method according to claim 6, characterized in that, The method further includes: Using simulation or experimental data, verify whether the parallel current source model reflects the dynamic characteristics of IGBT turn-off current under different operating conditions.

8. A device for constructing a parallel current source model for IGBT turn-off current analysis, characterized in that, The device includes: The determining unit is used to determine the IGBT turn-off current, including the injection current generated by the first sub-process and the recombination current generated by the second sub-process, based on the IGBT turn-off current decrease process including a first sub-process and a second sub-process that occur simultaneously; the first sub-process is a carrier injection process corresponding to MOSFET turn-off; the second sub-process is a carrier recombination reduction process. The first building unit is used to establish an equivalent circuit for the IGBT turn-off process by equating the IGBT to a parallel structure of the controlled source corresponding to the injected current and the current source corresponding to the composite current. The first acquisition unit is used to obtain, for the first sub-process, a first relationship characterizing the dynamic evolution law of the injection current based on the control relationship between the gate and emitter voltages on the injection current; The second acquisition unit is used to modify the dynamic evolution process of the charge carriers using the equivalent circuit for the second sub-process, establish the dynamic correlation between the injected current and the total number of charge carriers, and obtain the second relationship characterizing the dynamic evolution law of the composite current. The second construction unit is used to construct a parallel current source model based on the first relationship corresponding to the injected current and the second relationship corresponding to the composite current. The parallel current source model is used to quantitatively characterize the IGBT turn-off current decrease process.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the parallel current source model construction method for IGBT turn-off current analysis as described in any one of claims 1-7.

10. An electronic device, characterized in that, The device includes at least one processor, and at least one memory and bus connected to the processor; The processor and the memory communicate with each other via the bus. The processor is used to call program instructions in the memory to execute the parallel current source model construction method for IGBT turn-off current analysis as described in any one of claims 1-7.

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