A method for modeling a three-phase uncontrolled rectifier logic

Abstract

The present application relates to a three-phase uncontrolled rectifier main circuit mathematical model modeling method, in particular to a three-phase uncontrolled rectifier logic modeling method. The method adopts a logic modeling method to realize the establishment of the three-phase uncontrolled rectifier main circuit mathematical model. The logic modeling includes a voltage calculation part model, a diode conduction logic judgment model and a three-phase current operation logic model. The combination of the above voltage calculation part model, diode conduction logic judgment model and three-phase current operation logic model is the entire three-phase uncontrolled rectifier main circuit mathematical model. The present application designs a three-phase uncontrolled rectifier logic modeling method applied to semi-physical simulation commissioning. The method adopts a logic modeling method to realize the establishment of the three-phase uncontrolled rectifier main circuit mathematical model, provides a main circuit model for semi-physical simulation test, and verifies the effectiveness of the three-phase uncontrolled rectifier semi-physical simulation model.

Description

Technical Field

[0001] This invention relates to a mathematical modeling method for the main circuit of a three-phase uncontrolled rectifier, specifically a logic modeling method for a three-phase uncontrolled rectifier. Background Technology

[0002] Three-phase uncontrolled rectifier circuits are widely used in various fields due to their advantages such as no need for control, circuit reliability, and rapid switching action of transistors. In the early stages of new product development, simulation platforms are needed to verify and implement the main circuit of the three-phase uncontrolled rectifier. Hardware-in-the-loop (HIL) simulation technology can meet the high reliability simulation requirements of both software and hardware, effectively shortening the development cycle. However, it also brings new challenges, namely, the mathematical modeling of the main circuit. To maximize the verification of the functionality and performance of the new product's control unit, a high-precision mathematical model of the main circuit needs to be built.

[0003] Currently, the mathematical model of the main circuit of a three-phase uncontrolled rectifier is typically built using the built-in components and switch modules from the SimPowerSystems module library in MATLAB simulation software. Since the IGBT / Diode models in the SimPowerSystems module library are electrical models that consider parasitic parameters, they are relatively complex and are usually used for offline simulation. However, three-phase uncontrolled rectifiers often require online real-time simulation in conjunction with new products. But because the main circuit is built using the component modules from the SimPowerSystems module library in real-time online simulation, the model is complex, computationally intensive, and has a low simulation step size. To improve simulation accuracy, the model needs to be compiled and downloaded to the FPGA board of a hardware-in-the-loop simulation platform, but the SimPowerSystems module library cannot perform compilation and downloading. Summary of the Invention

[0004] This invention addresses the problem of complex and undownloadable main circuit mathematical models built using the SimPowerSystems module library by providing a logic modeling method for three-phase uncontrolled rectifiers. This method is used in conjunction with a hardware-in-the-loop (HIL) simulation platform for online real-time simulation of new products. The model is simple, computationally inefficient, and can be compiled and downloaded to an FPGA board for real-time simulation. It can also be verified and implemented through a HIL test platform.

[0005] The present invention is achieved by the following technical solution: a logic modeling method for a three-phase uncontrolled rectifier, which adopts a logic modeling approach to realize the construction of a mathematical model of the main circuit of a three-phase uncontrolled rectifier.

[0006] The above-mentioned logic modeling method for a three-phase uncontrolled rectifier includes a voltage calculation model, a diode conduction logic judgment model, and a three-phase current calculation logic model.

[0007] The voltage calculation model is established as follows: First, the absolute values ​​of the three AC side line voltages are taken. Then, the maximum value among the three line voltage absolute values ​​is selected as Um. After subtracting the forward voltage drop Vd of the two diodes and the voltage drop generated by the current on the diode internal resistance Rd_rect from Um, it is compared with 0. If it is greater than 0, the voltage output is Ud. If it is less than 0, the rectification is considered invalid and the output is 0. Um = max{|Uab|, |Ubc|, |Uca|}, Ud = Um-2·i_dc·Rd_rect-2·Vd;

[0008] DC side voltage is

[0009] The process of establishing the diode conduction logic judgment model is as follows: In a three-phase uncontrolled rectifier circuit, there are 2 diodes conducting at each moment. In order to complete the phase current calculation, it is necessary to determine the conduction state of the diodes on each bridge arm. In the model, the maximum value of the absolute value of the current input line voltage is used to determine the conducting bridge arm.

[0010] The logic for this part is as follows:

[0011] When status = 0, phases a and b are conducting; when status = 1, phases b and c are conducting; when status = 2, phases c and a are conducting; when status = 3, phases c and a are conducting.

[0012] The process of establishing the three-phase current calculation logic model is as follows: using status as the judgment criterion, the current sign is determined according to the signs of the AC side line voltages Uab, Ubc, and Uca, thus obtaining the three-phase current calculation formula.

[0013] Combining the voltage calculation model, diode conduction logic judgment model, and three-phase current calculation logic model above yields the mathematical model of the entire three-phase uncontrolled rectifier main circuit.

[0014] The above-mentioned logic modeling method for a three-phase uncontrolled rectifier uses the XilinxBlockset module library in MATLAB simulation software to build a mathematical model of the main circuit of the three-phase uncontrolled rectifier, which results in faster operation.

[0015] The above-mentioned logic modeling method for a three-phase uncontrolled rectifier allows the mathematical model of the main circuit to be encapsulated into a module that can be connected to different input and output modules, thus possessing versatility.

[0016] The above-mentioned logic modeling method for a three-phase uncontrolled rectifier allows the mathematical model of the main circuit to be downloaded to an FPGA for real-time online hardware-in-the-loop simulation.

[0017] This invention designs a logic modeling method for three-phase uncontrolled rectifiers applied to semi-physical simulation and commissioning. By adopting a logic modeling approach, the mathematical model of the main circuit of the three-phase uncontrolled rectifier is built, providing the main circuit model for semi-physical simulation testing and verifying the effectiveness of the semi-physical simulation model of the three-phase uncontrolled rectifier. Attached Figure Description

[0018] Figure 1 This is the topology diagram of the main circuit of a three-phase uncontrolled rectifier.

[0019] Figure 2 This is the logic diagram for voltage operation.

[0020] Figure 3 This is a logic diagram for determining diode conduction.

[0021] Figure 4 This is a three-phase current operation logic diagram.

[0022] Figure 5 This is a mathematical model diagram of a three-phase uncontrolled rectifier main circuit.

[0023] Figure 6 The waveform diagram is a semi-physical simulation diagram of a three-phase uncontrolled rectifier model. Detailed Implementation

[0024] The main circuit topology of the three-phase uncontrolled rectifier is as follows: Figure 1 The diagram shows a rectifier circuit consisting of six uncontrolled rectifier diodes. When the input AC voltage is constant, a DC voltage is obtained across the load.

[0025] The model's inputs and outputs are shown in Table 1.

[0026] Table 1 Input and Output Variables

[0027] i_dc DC side current udc DC side voltage Uab / Ubc / Uca AC side line voltage i_a / i_b / i_c AC three-phase current

[0028] (1) Voltage Calculation Section

[0029] First, the absolute values ​​of the three AC line voltages are taken. Then, the maximum value among the three line voltage absolute values ​​is selected as Um. After subtracting the forward voltage drop of the two diodes Vd and the voltage drop generated by the current on the diode internal resistance Rd_rect from Um, it is compared with 0. If it is greater than 0, the voltage output is Ud. If it is less than 0, the rectification is considered invalid and the output is 0.

[0030] Um=max{|Uab|, |Ubc|, |Uca|}

[0031] Ud=Um-2·i_dc·Rd_rect-2·Vd

[0032] DC side voltage is

[0033]

[0034] The logic model for voltage calculation is as follows: Figure 2 As shown.

[0035] (2) Current Calculation Section

[0036] In a three-phase uncontrolled rectifier circuit, two diodes are conducting at any given time. To calculate the phase current, the conduction state of the diodes on each bridge arm needs to be determined. In the model, the maximum absolute value of the current input line voltage is used to determine which bridge arm is conducting.

[0037] The logic for this part is as follows, including the diode conduction logic: Figure 3 As shown.

[0038]

[0039] When status = 0, phases a and b are conducting.

[0040] When status = 1, phases b and c are conducting.

[0041] When status = 2, phases c and a are conducting.

[0042] When status = 3, phases c and a are conducting.

[0043] Since the uncontrolled rectifier circuit will not experience voltage and current signs differing during operation, the current sign is determined based on the conduction relationship and the status, according to the AC side line voltages Uab, Ubc, and Uca. This allows us to derive the three-phase current calculation formula. The logic model for the current calculation is as follows: Figure 4 As shown.

[0044]

[0045]

[0046]

[0047] Based on the aforementioned voltage and current logic relationships, a three-phase uncontrolled rectifier main circuit is modeled. Combining the voltage calculation model, diode conduction logic judgment model, and three-phase current calculation logic model yields a semi-physical simulation test model of the entire three-phase uncontrolled rectifier main circuit. The constructed model is as follows: Figure 5 As shown.

[0048] Example

[0049] After constructing the mathematical model of the three-phase uncontrolled rectifier main circuit, the parameters were set as follows: diode forward voltage drop vd = 0.8V, diode internal resistance Rd_rect = 0.001Ω, and simulation step size Ts = 1e-5. The hardware-in-the-loop simulation model of the three-phase uncontrolled rectifier main circuit was then verified through simulation. The hardware-in-the-loop simulation waveforms of the three-phase uncontrolled rectifier model are shown below. Figure 6 As shown.

[0050] Hardware-in-the-loop (HIL) simulation modeling of the main circuit of a three-phase uncontrolled rectifier has the following advantages:

[0051] 1) The model has clear logic, simple structure, low resource consumption, and is easy to verify;

[0052] 2) This model can be encapsulated as a module, connecting to different input and output modules, thus possessing versatility;

[0053] 3) The model can be compiled and downloaded to the FPGA board, and can be used in conjunction with generators, auxiliary circuits and subway power supply systems for real-time simulation verification.

Claims

1. A logic modeling method for a three-phase uncontrolled rectifier, characterized in that: A logical modeling approach was adopted to construct the mathematical model of the main circuit of a three-phase uncontrolled rectifier. The logical modeling includes a voltage calculation model, a diode conduction logic judgment model, and a three-phase current calculation logic model. The process of establishing the voltage calculation model is as follows: First, take the absolute value of the three AC side line voltages. Then, select the maximum value of the three line voltage absolute values ​​as Um. Subtract the forward voltage drop of the two diodes Vd and the voltage drop generated by the current on the diode internal resistance Rd_rect from Um. Compare it with 0. If it is greater than 0, the voltage output is Ud. If it is less than 0, the rectification is considered invalid and the output is 0. , ; DC side voltage is ; The process of establishing the diode conduction logic judgment model is as follows: In a three-phase uncontrolled rectifier circuit, there are 2 diodes conducting at each moment. In order to complete the phase current calculation, it is necessary to determine the conduction state of the diodes on each bridge arm. In the model, the maximum value of the absolute value of the current input line voltage is used to determine the conducting bridge arm. The logic for this part is as follows: , When status = 0, phases a and b are conducting; when status = 1, phases b and c are conducting; when status = 2, phases c and a are conducting; when status = 3, phases c and a are conducting. The process of establishing the three-phase current calculation logic model is as follows: using status as the judgment criterion, the current sign is determined according to the signs of the AC side line voltages Uab, Ubc, and Uca, thus obtaining the three-phase current calculation formula. , , ; Combining the voltage calculation model, diode conduction logic judgment model, and three-phase current calculation logic model above yields the mathematical model of the entire three-phase uncontrolled rectifier main circuit.

2. The logic modeling method for a three-phase uncontrolled rectifier according to claim 1, characterized in that: A mathematical model of the main circuit of a three-phase uncontrolled rectifier was built using the Xilinx Blockset module library in MATLAB simulation software.

3. The logic modeling method for a three-phase uncontrolled rectifier according to claim 2, characterized in that: The mathematical model of this main circuit is encapsulated as a module, which connects to different input and output modules, making it versatile.

4. The logic modeling method for a three-phase uncontrolled rectifier according to claim 3, characterized in that: The mathematical model of this main circuit is downloaded to the FPGA for real-time online hardware-in-the-loop simulation.

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