A Real-Time Simulation Modeling Method for a Two-Level Bidirectional DC / DC Conversion System

Abstract

This invention belongs to the field of electronic circuit simulation modeling technology, specifically a real-time simulation modeling method for a two-level bidirectional DC / DC converter system. It includes breaking down the circuit into modules based on the circuit topology and electrical working mechanism, establishing real-time simulation models for each module (i.e., FPGA real-time simulation models for the input side, the two-level bidirectional DC / DC converter, and the output side), combining these three to obtain the overall FPGA real-time simulation model, and building a power battery model in the CPU. The current and voltage input / output parameters of the power battery interact in real-time with the final FPGA real-time simulation model obtained via interface configuration (S14). This invention builds a real-time simulation model through mechanism analysis, balancing model accuracy and real-time performance. The model can achieve smooth and rapid switching between Buck / Boost modes simply by adjusting the software control algorithm, efficiently verifying the dynamic performance and stability of the bidirectional energy flow control strategy.

Description

Technical Field

[0001] This invention relates to the field of simulation modeling technology for electronic circuits, and in particular to a real-time simulation modeling method for a two-level bidirectional DC / DC conversion system. Background Technology

[0002] With the rapid development of power electronic systems towards greater complexity and higher reliability, traditional offline simulation testing methods and physical prototype testing methods can no longer meet the needs of efficient, safe, and full-condition development and testing. Existing real-time simulation modeling methods mainly include the following categories: 1) Modeling schemes based on the state-space averaging method, which averages the circuit state variables over a switching cycle to obtain a continuous, nonlinear average model, primarily used for system-level dynamic analysis rather than high-precision real-time simulation. 2) Modeling schemes based on traditional offline simulation, typically using modules from the Simscape module library in the Matlab / Simulink toolbox to build simulation models, which cannot simultaneously achieve high accuracy and real-time rapid simulation. 3) Modeling schemes based on simplified models constructed from ideal switching devices, which suffer from numerical stability issues; simulating fault conditions and nonlinear components significantly increases model complexity and computational load.

[0003] The main shortcomings of existing real-time simulation modeling methods are: 1) Modeling schemes based on the state-space averaging method cannot simulate transient processes and discontinuous modes of switching, as the averaging method assumes that the circuit always operates in continuous conduction mode; it cannot simulate nonlinear effects, nor can it characterize the effects of dead time and device saturation; it cannot be used to verify control or protection logic related to switching, resulting in narrow applicability. 2) Traditional offline simulation testing methods are slow, especially for complex systems, where simulating a physical process that lasts a few seconds may take several hours; they cannot connect to real controllers, failing to meet the real-time interaction requirements of controller hardware; and they cannot verify actual factors such as controller hardware, software sampling circuits, and delays. 3) Simplified modeling schemes, forced to simplify models to ensure real-time performance, lead to distorted simulation waveforms, failing to accurately reflect nonlinear effects such as dead time and parasitic parameters, and making it difficult to safely, comprehensively, and faithfully verify the controller's fault conditions and robustness. Summary of the Invention

[0004] To overcome the limitations of existing real-time simulation modeling methods, such as the contradiction between model accuracy and real-time performance, numerical stability issues like algebraic loops, and the difficulty in performing high-fidelity fault modeling, this invention provides a real-time simulation modeling method for two-level bidirectional DC / DC converter systems. This method fundamentally breaks through the limitations of existing solutions, offering a novel modeling method that can achieve high-fidelity simulation of high-frequency switching details, meet real-time simulation calculation requirements, and is easy to develop. It realizes a closed-loop process from theoretical analysis to real-time verification. Furthermore, the proposed modeling method can perform real-time, flexible, and accurate fault and extreme condition tests, providing a high-precision, full-condition simulation test method for the development of two-level bidirectional DC / DC systems.

[0005] This invention provides a real-time simulation modeling method for a two-level bidirectional DC / DC converter system. Based on the topology and electrical working mechanism of the two-level bidirectional DC / DC converter circuit, the circuit modules are divided into a power battery section, an input side section, a two-level bidirectional DC / DC section, and an output side section. When the power battery is charging, the two-level bidirectional DC / DC converter circuit operates in Buck mode; when the power battery is discharging, the two-level bidirectional DC / DC converter circuit operates in Boost mode. The direction of the current discharging from the power battery is set to positive. The method includes the following steps:

[0006] S1. Establish a real-time simulation model of the circuit in modules. The sub-steps are as follows:

[0007] S11, the input side consists of a pre-charge circuit and a filter inductor, wherein the filter inductor current... The voltage across the filter inductor can be obtained by integrating the voltage across the filter inductor. Subtract the terminal voltage from the power battery voltage The voltage of the pre-charge circuit is obtained, and its FPGA real-time simulation model is built based on the voltage and current relationship on the input side.

[0008] S12, Filter inductor current in the two-level bidirectional DC / DC section The current flows into the first switch VT1 and the second switch VT2 connected in parallel, respectively, which include the charging Buck condition, the discharging Boost condition, and the charging / discharging Buck-Boost condition. Based on the voltage and current relationship of the charging Buck condition, an FPGA real-time simulation model of the charging Buck condition is built; based on the voltage and current relationship of the discharging Boost condition, an FPGA real-time simulation model of the discharging Boost condition is built; based on the voltage and current relationship of the charging / discharging Buck-Boost condition, an FPGA real-time simulation model of the charging / discharging Buck-Boost condition is built.

[0009] S13, The output side consists of the intermediate bus capacitor C and the slow-release resistor R.slop and load resistance R load The system is configured such that when the system is in charging mode, the output side is a DC power supply. For the intermediate bus capacitor C, its FPGA real-time simulation model is built based on the current-voltage relationship of the output side.

[0010] S14. After combining the FPGA real-time simulation models of the input side, the two-level bidirectional DC / DC part and the output side, we obtain the FPGA real-time simulation model of the entire two-level bidirectional DC / DC converter circuit topology without the power battery part.

[0011] S2. Build a power battery model in the CPU. The current and voltage input and output parameters of the power battery can interact in real time with the FPGA real-time simulation model finally obtained in S14 through interface configuration.

[0012] Preferably, if the FPGA real-time simulation model has a feedback channel, a unit delay unit of one step size is introduced into the feedback channel. This unit delay unit uses feedback data from the previous simulation step size to participate in the current step size calculation, thereby eliminating algebraic loops. Introducing a one-step computational delay into the feedback channel based on an accurate mathematical model effectively solves the algebraic loop problem, ensuring the numerical stability of the model under high-speed real-time simulation and avoiding simulation calculation divergence and crashes.

[0013] Preferably, open / open circuit faults of switching transistors are simulated by providing normally open or normally closed drive signals to the switching transistors; bridge arm shoot-through faults are simulated by overlapping drive signals of upper and lower switching transistors in the same bridge arm or by setting the dead time too small; transient faults during mode switching are simulated by forcing incorrect direction commands or by sudden load changes during mode switching; current or voltage sensor faults are simulated by changing the turns ratio of voltage or current sensors online; and online hot switching of the model is simulated by adjusting the capacitor or inductor parameter values ​​in real time to simulate component aging or failure faults.

[0014] Compared with existing technologies, the technical solution provided by this invention has the following technical effects: Based on a detailed analysis of the working principle of the bidirectional DC / DC converter circuit, the method of this invention builds a real-time simulation FPGA model and a power battery CPU model for a two-level bidirectional DC / DC converter system. The system architecture is innovated through the collaborative simulation of the FPGA and CPU models. Fault simulation and online parameter hot-switching functions are added to the above models, achieving functional and application innovations through real-time online simulation experiments. Ultimately, high-precision real-time simulation experiments of the two-level bidirectional DC / DC converter system under all operating conditions are achieved. The method of this invention, while ensuring high model accuracy, builds a real-time simulation model through mechanism analysis, balancing model accuracy and real-time performance. The model can achieve smooth and rapid switching between Buck / Boost modes simply by adjusting the software control algorithm, efficiently verifying the dynamic performance and stability of the bidirectional energy flow control strategy, and providing a powerful platform for the development of complex energy management algorithms. Adding fault simulation and online parameter hot-switching functions to the above models enables safe and realistic simulation of various extreme and fault conditions without affecting the stability of the main model, achieving comprehensive testing of the system's fault response strategy and robustness. The online hot-switching function of model parameters allows researchers to dynamically adjust circuit parameters such as inductance and capacitance values ​​during simulation without interrupting the experiment, greatly improving the efficiency of control parameter tuning and system optimization. The real-time simulation model built by the aforementioned modeling method realizes a closed-loop process from theoretical analysis to real-time verification, providing an efficient, reliable, and full-condition real-time simulation verification method for the development of bidirectional DC / DC systems, which has significant implications for improving the development efficiency and reliability of power electronic conversion systems. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram illustrating the overall innovative concept of a real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to a certain embodiment of the present invention.

[0018] Figure 2 This is a topology diagram of the main circuit of the two-level bidirectional DC / DC converter system according to a certain embodiment of the present invention;

[0019] Figure 3 This is a circuit schematic diagram of the input side portion according to a certain embodiment of the present invention;

[0020] Figure 4 This is a diagram of the FPGA real-time simulation model corresponding to the input side portion in a certain embodiment of the present invention;

[0021] Figure 5 This is a circuit schematic diagram of the two-level bidirectional DC / DC section in a certain embodiment of the present invention;

[0022] Figure 6 This is a real-time FPGA simulation model diagram of the two-level bidirectional DC / DC section under the charging Buck condition in a certain embodiment of the present invention.

[0023] Figure 7 This is a real-time FPGA simulation model diagram of the two-level bidirectional DC / DC section under the discharge Boost condition in a certain embodiment of the present invention.

[0024] Figure 8 This is a real-time FPGA simulation model diagram of the two-level bidirectional DC / DC section under the charge-discharge Buck-Boost condition in a certain embodiment of the present invention.

[0025] Figure 9 This is a circuit schematic diagram of the output side portion according to a certain embodiment of the present invention;

[0026] Figure 10 This is a real-time simulation model diagram of the FPGA for the output side portion in a certain embodiment of the present invention;

[0027] Figure 11 This is an FPGA real-time simulation model of the entire two-level bidirectional DC / DC converter circuit topology without the power battery section in a certain embodiment of the present invention.

[0028] Figure 12 This is a CPU model diagram of the power battery described in a certain embodiment of the present invention;

[0029] Figure 13 This is a waveform diagram of the upper and lower transistor pulses and charging current under Buck charging conditions in a certain embodiment of the present invention (the upper transistor is used as a switching transistor, and the lower transistor is used as a freewheeling diode).

[0030] Figure 14 This is a waveform diagram of the upper and lower transistor pulses and charging current under the Buck charging condition in a certain embodiment of the present invention (the upper and lower transistors are complementary in conduction).

[0031] Figure 15 This is a waveform diagram of bus voltage and discharge current under Boost discharge conditions in a certain embodiment of the present invention (the upper transistor is used as a freewheeling diode, and the lower transistor is used as a switching transistor).

[0032] Figure 16 This is a waveform diagram of bus voltage and discharge current under Boost discharge conditions in a certain embodiment of the present invention (with complementary conduction of upper and lower transistors).

[0033] Figure 17 This is a waveform diagram of the upper and lower transistor pulses and the charging / discharging current during the charging and discharging operation of a Buck-Boost circuit in a certain embodiment of the present invention.

[0034] Figure 18 The waveforms of the upper and lower transistor pulses and the charging / discharging current during the Boost-Buck discharge-to-charge switching condition are shown in a certain embodiment of the present invention. Detailed Implementation

[0035] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0036] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0037] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0038] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] In one embodiment, a real-time simulation modeling method for a two-level bidirectional DC / DC converter system is disclosed, and its innovative approach is as follows: Figure 1 As shown, the topology of the two-level bidirectional DC / DC converter circuit is as follows: Figure 2As shown, based on the topology and electrical working mechanism of the two-level bidirectional DC / DC converter circuit, the circuit modules are divided into a power battery section, an input side section, a two-level bidirectional DC / DC section, and an output side section. When the two-level bidirectional DC / DC converter circuit is in Buck mode, VT1 is used as a switching transistor, and VT2 is used as a freewheeling diode. The bus charges the power battery through the DC / DC converter. When the two-level bidirectional DC / DC converter circuit is in Boost mode, VT2 is used as a switching transistor, and VT1 is used as a freewheeling diode. The power battery supplies power to the load through the DC / DC converter. The direction of the power battery discharge current is set to positive. For pre-charge contactors, For pre-charge resistor, The main contactor is L, which is the inductor. VT1 and VT2 are the switching transistors, C is the intermediate bus capacitor, and R is the R value. slope For slow-release resistors, R load For the load resistance, in this specific embodiment, C = 28.8 mF; R slope =30kΩ; L=1.1mH; Line resistance R line =0.01Ω; CHR=10Ω; Simulation step size Ts=1e-7s;

[0040] The method includes the following steps:

[0041] S1. Establish a real-time simulation model of the circuit in modules. The sub-steps are as follows:

[0042] S11, the input side consists of a pre-charge circuit and a filter inductor, and its circuit schematic is as follows: Figure 3 As shown, the filter inductor current... The voltage across the filter inductor can be obtained by integrating the voltage across the filter inductor. Subtract the terminal voltage from the power battery voltage The voltage is obtained from the pre-charge circuit voltage, based on the voltage-current relationship on the input side, such as... Figure 4 As shown, its FPGA real-time simulation model is built; filter inductor current. The calculation formula is:

[0043] ,

[0044] In the formula, The voltage across the filter inductor is... This is the inductance value of the filter inductor;

[0045] S12, Filter inductor current in the two-level bidirectional DC / DC section The circuit diagram shows the inputs to the first and second switching transistors VT1 and VT2 connected in parallel, respectively. Figure 5As shown, it includes charging Buck mode, discharging Boost mode and charging / discharging Buck-Boost mode;

[0046] Based on the voltage-current relationship under the charging Buck condition, an FPGA real-time simulation model of the charging Buck condition is built, such as... Figure 6 As shown, the voltage-current relationship under the charging Buck condition is as follows: When the switching states of transistors VT1 and VT2 are (0,0), if the inductor current... Then the DC side current Output voltage If the inductor current Then the DC side current Output voltage When the switching states of transistors VT1 and VT2 are (1,0), the DC side current is... Output voltage See Table 1 for details.

[0047] Table 1 Voltage-current relationship under charging Buck operating conditions

[0048]

[0049] Under Buck charging conditions, the upper transistor acts as a switching transistor, and the lower transistor acts as a freewheeling diode. After starting under light load and being loaded to full load, the pulse and charging current waveforms of the upper and lower transistors during charging are as follows: Figure 13 As shown. The upper and lower transistors conduct complementaryly. After a light load start-up, the load increases to half load. The waveforms of the upper and lower transistor pulses and the charging current under charging conditions are as follows. Figure 14 As shown.

[0050] Based on the voltage-current relationship under the discharge boost condition, an FPGA real-time simulation model of the discharge boost condition is built as shown in the figure. Figure 7 As shown, the voltage-current relationship under the discharge Boost condition is as follows: When the switching states of switching transistors VT1 and VT2 are (0,0), if the inductor current... Then the DC side current Output voltage If the inductor current Then the DC side current Output voltage When the switching states of transistors VT1 and VT2 are (0,1), the DC side current is... Output voltage See Table 2 for details.

[0051] Table 2 Voltage-current relationship under discharge boost condition

[0052]

[0053] Under Boost discharge conditions, the upper transistor acts as a freewheeling diode, and the lower transistor acts as a switching transistor. After starting under light load and being loaded to full load, the pulse and discharge current waveforms of the upper and lower transistors under discharge conditions are as follows: Figure 15 As shown. The upper and lower transistors conduct complementaryly. After a light load start-up, the load increases to half load. The waveforms of the upper and lower transistor pulses and the charging current under discharge conditions are as follows. Figure 16 As shown.

[0054] Based on the voltage-current relationship under the charging / discharging Buck-Boost operating conditions, an FPGA real-time simulation model of the charging / discharging Buck-Boost operating conditions is built, such as... Figure 8 As shown; the voltage-current relationship under the charging / discharging Buck-Boost condition is as follows: when the switching states of switching transistors VT1 and VT2 are (0,0), if the inductor current... Then the DC side current Output voltage If the inductor current Then the DC side current Output voltage When the switching states of transistors VT1 and VT2 are (1,0), the DC side current is... Output voltage When the switching states of transistors VT1 and VT2 are (0,1), the DC side current is... Output voltage See Table 3 for details.

[0055] Table 3. Voltage-current relationship during charging and discharging of Buck-Boost modules.

[0056]

[0057] Under Buck-Boost charging and discharging conditions, it starts under light load, and after startup, the charging condition is increased to half load. Buck-Boost charging and discharging switching is achieved solely through PWM pulses, with waveforms of the upper and lower transistor pulses and the charging / discharging current as shown below. Figure 17 As shown.

[0058] Under Boost-Buck discharge-to-charge conditions, the system starts under light load, and then the discharge condition is increased to half load. Boost-Buck discharge-to-charge switching is achieved solely through PWM pulses. The waveforms of the upper and lower MOSFET pulses and the charge / discharge current are as follows: Figure 18 As shown.

[0059] S13, The output side consists of the intermediate bus capacitor C and the slow-release resistor R. slop and load resistance R load Its structure and circuit schematic are as follows: Figure 9As shown, when the system is in charging mode, the output side is a DC power supply. For the intermediate bus capacitor C, based on the current-voltage relationship on the output side, its FPGA real-time simulation model is built, as follows. Figure 10 As shown; calculate the current of the intermediate bus capacitor C using the product equation. :

[0060] ,

[0061] in, This is the voltage across capacitor C on the intermediate busbar; .

[0062] S14. After combining the FPGA real-time simulation models of the input side, the two-level bidirectional DC / DC converter, and the output side, the FPGA real-time simulation model of the entire two-level bidirectional DC / DC converter circuit topology is obtained, excluding the power battery section. Figure 11 As shown;

[0063] S2. Build a power battery model in the CPU, specifically as follows: Figure 12 As shown, the current and voltage input and output parameters of the power battery are configured through the interface and interact in real time with the FPGA real-time simulation model finally obtained by S14. The power battery model built in the CPU is deployed in the HR CPCI 5125 computing board. The power battery current i_battery is obtained as input by reading the interface Board:[2] and Address:[9] through the register. After calculation by the power battery model, the power battery voltage U_battery and battery polarization voltage V_e are output. The power battery model also contains a SOC calculation module, which updates the SOC value in real time according to the current integral. U_battery is also output to the data acquisition or monitoring system through the data9 port. The FPGA is responsible for calculating the high-frequency and fast DC / DC main circuit part, and the CPU is responsible for calculating the slow power battery model part. The system architecture innovation is achieved by co-simulating the two-level bidirectional DC / DC main circuit real-time simulation FPGA model and the power battery CPU model.

[0064] Based on the above embodiments, in a preferred embodiment, if the FPGA real-time simulation model has a feedback channel, a unit delay unit of one step size is introduced into the feedback channel. This unit delay unit uses feedback data from the previous simulation step size to participate in the current step size calculation, thereby eliminating algebraic loops. Specifically, feedback channels exist in both the input-side and output-side FPGA real-time simulation models. Due to their closed-loop structure, the system output simultaneously depends on both the current input / output signal and the current feedback signal, forming an algebraic loop during simulation calculation, causing the simulation system to be unsolvable or to diverge. To solve this numerical stability problem, this invention introduces a step-size calculation delay into the feedback channel to eliminate the algebraic loop and ensure the numerical stability of the model under all operating conditions. For real-time simulation systems with sufficiently small simulation step sizes, this delay has a negligible impact on the system's dynamic characteristics.

[0065] Based on the above embodiments, in a preferred embodiment, open / closed circuit faults of switching devices are simulated by providing normally open or normally closed drive signals to the switching devices; bridge arm shoot-through faults are simulated by overlapping drive signals of upper and lower switching devices in the same bridge arm or by setting the dead time too small (e.g., <100ns); transient faults during mode switching are simulated by forcing incorrect direction commands or by sudden load changes during mode switching; current or voltage sensor faults are simulated by changing the turns ratio of voltage or current sensors online; and online hot switching of the model is simulated by adjusting the capacitor or inductor parameter values ​​in real time, simulating aging or failure faults of components such as capacitors and inductors. The proposed modeling method can simulate fault states and post-fault system responses in real time and realistically without affecting model stability, achieving innovation in functionality and application. The simulated fault conditions include, but are not limited to: open and closed circuit faults of switching devices, bridge arm shoot-through faults, voltage / current sensor faults, inductor saturation faults, capacitor aging and failure faults, and output load impact faults. The above fault injection and simulation modules are configured through a graphical human-computer interaction interface, allowing users to customize fault types, fault injection times, and fault durations.

[0066] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A real-time simulation modeling method for a two-level bidirectional DC / DC converter system, characterized in that, Based on the topology and electrical working mechanism of the two-level bidirectional DC / DC converter circuit, the circuit modules are divided into a power battery section, an input side section, a two-level bidirectional DC / DC section, and an output side section. When the power battery is charging, the two-level bidirectional DC / DC converter circuit is in Buck mode; when the power battery is discharging, the two-level bidirectional DC / DC converter circuit is in Boost mode. The direction of the power battery discharge current is set to positive. The method includes the following steps: S1. Establish a real-time simulation model of the circuit in modules. The sub-steps are as follows: S11, The input side consists of a pre-charge circuit and a filter inductor, wherein the filter inductor current... The voltage across the filter inductor can be obtained by integrating the voltage across the filter inductor. Subtract the terminal voltage from the power battery voltage The voltage of the pre-charge circuit is obtained, and its FPGA real-time simulation model is built based on the voltage and current relationship on the input side. S12, Filter inductor current in the two-level bidirectional DC / DC section The current flows into the first switch VT1 and the second switch VT2 connected in parallel, respectively, which include the charging Buck condition, the discharging Boost condition, and the charging / discharging Buck-Boost condition. Based on the voltage and current relationship of the charging Buck condition, an FPGA real-time simulation model of the charging Buck condition is built; based on the voltage and current relationship of the discharging Boost condition, an FPGA real-time simulation model of the discharging Boost condition is built; based on the voltage and current relationship of the charging / discharging Buck-Boost condition, an FPGA real-time simulation model of the charging / discharging Buck-Boost condition is built. S13, The output side consists of the intermediate bus capacitor C and the slow-release resistor R. slop and load resistance R load The system is configured such that when the system is in charging mode, the output side is a DC power supply. For the intermediate bus capacitor C, its FPGA real-time simulation model is built based on the current-voltage relationship of the output side. S14. After combining the FPGA real-time simulation models of the input side, the two-level bidirectional DC / DC part and the output side, we obtain the FPGA real-time simulation model of the entire two-level bidirectional DC / DC converter circuit topology without the power battery part. S2. Build a power battery model in the CPU. The current and voltage input and output parameters of the power battery can interact in real time with the FPGA real-time simulation model finally obtained in S14 through interface configuration.

2. The real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to claim 1, characterized in that, If the FPGA real-time simulation model has a feedback channel, a unit delay unit with a unit step size is introduced into the feedback channel. The unit delay unit uses the feedback data of the previous simulation step size to participate in the current step size calculation in order to eliminate the algebraic loop.

3. The real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to claim 2, characterized in that, Simulate open / open circuit faults of switching transistors by providing normally open or normally closed drive signals; simulate bridge arm shoot-through faults by overlapping drive signals of upper and lower switching transistors in the same bridge arm or by setting the dead time too small; simulate transient faults during mode switching by forcing incorrect direction commands or by sudden load changes during mode switching; simulate current or voltage sensor faults by changing the turns ratio of voltage or current sensors online; and simulate online hot switching of the model and component aging or failure faults by adjusting capacitor or inductor parameter values ​​in real time.

4. A real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to any one of claims 1 to 3, characterized in that, Current of the filter inductor in S11 The calculation formula is: ， In the formula, The voltage across the filter inductor is... This is the inductance value of the filter inductor.

5. The real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to claim 4, characterized in that, The voltage-current relationship in the charging Buck condition of S12 is as follows: When the switching states of switching transistors VT1 and VT2 are (0,0), if the inductor current... Then the DC side current Output voltage If the inductor current Then the DC side current Output voltage When the switching states of transistors VT1 and VT2 are (1,0), the DC side current is... Output voltage .

6. The real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to claim 5, characterized in that, The voltage-current relationship in the discharge Boost mode of S12 is as follows: When the switching states of switching transistors VT1 and VT2 are (0,0), if the inductor current... Then the DC side current Output voltage If the inductor current Then the DC side current Output voltage When the switching states of transistors VT1 and VT2 are (0,1), the DC side current is... Output voltage .

7. The real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to claim 6, characterized in that, The voltage-current relationship in the charging / discharging Buck-Boost mode of S12 is as follows: When the switching states of switching transistors VT1 and VT2 are (0,0), if the inductor current... Then the DC side current Output voltage If the inductor current Then the DC side current Output voltage When the switching states of transistors VT1 and VT2 are (1,0), the DC side current is... Output voltage When the switching states of transistors VT1 and VT2 are (0,1), the DC side current is... Output voltage .

8. The real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to claim 7, characterized in that, In the output side of S13, the current of the intermediate bus capacitor C is calculated using the product equation. : ， in, This is the voltage across capacitor C on the intermediate busbar; .

9. The real-time simulation modeling method for a two-level bidirectional DC / DC converter system according to claim 8, characterized in that, The power battery model built in the CPU by S2 is deployed on the HR CPCI 5125 computing board. The power battery current i_battery is obtained as input through the register reading interface Board:[2] and Address:[9]. After calculation by the power battery model, the power battery voltage U_battery and the battery polarization voltage V_e are output. The power battery model also contains a SOC calculation module, which updates the SOC value in real time according to the current integral. U_battery is also output to the data acquisition or monitoring system through the data9 port.

Images