A predictive evaluation method for voltage drop in aircraft electrical circuit networks

Abstract

The present invention provides a method for predicting and evaluating voltage drop in an aircraft electrical circuit network. The method comprises the following steps: S1. establishing an aircraft electromagnetic model, defining the terminals of the cables and their electrical circuit network grounding structure, and characterizing the mutual coupling between the cables and the electrical circuit network using a terminal impedance matrix; S2. solving the terminal impedance matrix; S3. converting the terminal impedance matrix into a zero-pole expression; S4. converting the zero-pole expression into a state-space expression; S5. converting the state-space expression into a netlist model that can be used as input for circuit simulation analysis; and S6. importing the netlist model into a simulation environment, defining an excitation source and a terminal load, establishing a Thevenin equivalent circuit simulation model, and simulating and calculating the voltage drop at the terminal load. The present invention solves the problem of large voltage drop in composite aircraft electrical circuit network designs caused by common-mode impedance and fault currents, lightning-induced currents, and high-frequency (HIRF) coupling currents.

Description

Technical Field

[0001] The present invention relates to the field of electrical circuit network design of aircraft composite material structures, and in particular to a method for predicting and evaluating voltage drop of an aircraft electrical circuit network. Background Art

[0002] The use of composite materials in aircraft structures can significantly reduce the weight of structural components, saving fuel and flight costs. However, their electrical conductivity, far inferior to that of metal, makes it difficult for composite fuselages to perform electrical tasks such as lightning protection, system connections, and grounding. Composite aircraft should have independent ground return lines for the electrical system. For example, a carbon fiber composite fuselage must provide an electrical circuit network for current flow. Compared to traditional metal aircraft, composite aircraft electrical circuit networks face new challenges in terms of structure, termination, and current distribution. The voltage drop within the electrical circuit network is one of the most critical parameters.

[0003] When designing an electrical circuit network, it's crucial to consider both the structural strength and weight of the grounding grid while ensuring a reasonable voltage drop within the circuit under the influence of common-mode impedance to meet the voltage requirements of connected electrical and electronic equipment. Furthermore, fault currents, lightning-induced currents, and high-frequency (HIRF) coupling currents can generate significant voltage drops within the circuit, potentially causing airborne equipment to malfunction. Therefore, it's crucial to predict and assess voltage drops within electrical circuits of composite aircraft structures. Summary of the Invention

[0004] The present invention provides a method for predicting and evaluating voltage drop in an aircraft electrical circuit network, which solves the problem of large voltage drop caused by common mode impedance and fault current, lightning induced current, and HIRF coupling current in composite aircraft electrical circuit network design.

[0005] Technical Solution: A method for predicting and evaluating voltage drop in an aircraft electrical circuit network, comprising:

[0006] S1. Build an aircraft electromagnetic model, define the terminals of the cables and their electrical loop network grounding structure, and characterize the mutual coupling between the cables and the electrical loop network using a terminal impedance matrix.

[0007] S2. Solve the terminal impedance matrix;

[0008] S3. Convert the terminal impedance matrix into a zero-pole expression;

[0009] S4. Convert zero-pole expressions into state-space expressions;

[0010] S5. Converting the state-space expression into a netlist model that can be used as input for circuit simulation analysis;

[0011] S6. Import the netlist model into the simulation environment, define the excitation source and terminal load, establish the Thevenin equivalent circuit simulation model, and simulate and calculate the voltage drop of the terminal load.

[0012] In the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, S1 is specifically as follows:

[0013] Assume that cables L1~LN are connected to different parts of the electrical circuit network inside the aircraft electromagnetic model, G1~GN are the ground terminals on the electrical circuit network corresponding to the cables, and V L1 ~V LN is the voltage across the cables L1 to LN, V G1 ~V GN is the voltage at both ends of the electrical circuit network ground corresponding to cables L1 to LN, I L1 ~I LN is the current flowing through cables L1 to LN, I G1 ~I GN The current flowing through the ground of the electrical circuit network corresponding to cables L1 to LN;

[0014] Assume: Z G,G The sub-impedance matrix is ​​an impedance matrix that only contains the grounding model of the electrical loop network. The items on the diagonal are the impedance between the two ends of a certain electrical loop network grounding, and the items on the off-diagonal are the mutual impedances between different grounding ends. L,L The sub-impedance matrix is ​​an impedance matrix that only contains the cable model. The items on the diagonal are the impedance of a certain cable, and the items on the off-diagonal are the mutual impedances between different cables. G,L and Z L,G The sub-impedance matrix is ​​the mutual impedance matrix between the cable and the ground structure of the electrical loop network. Specifically, Z G,L It represents the voltage induced on the ground of the electrical circuit network when the cable passes a unit current. L,G It represents the voltage induced on the cable when a unit current flows through the electrical loop network grounding structure. The items on the diagonal are the mutual impedance between the cable and its corresponding electrical loop network grounding structure.

[0015] Then we have:

[0016] .

[0017] In S2 of the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, the terminal impedance matrix is ​​solved using the frequency domain full-wave S-PEEC algorithm.

[0018] In S3 of the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, the terminal impedance matrix is ​​converted into a zero-pole expression using a vector fitting method.

[0019] In S3 of the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, the zero-pole expression is:

[0020] ;

[0021] Where H(s) represents a rational fraction, N represents the order, s represents the frequency domain variable, and p n represents the extreme point of the fraction, α n represents the remainder of the fraction, and d represents a real number.

[0022] In S4 of the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, the state-space expression is:

[0023] .

[0024] In S5 of the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, the file format of the netlist model is .CIR.

[0025] In step S6 of the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, the netlist model is imported and the excitation source and terminal load are defined in the PSpice Designer circuit simulation software.

[0026] In S6 of the aforementioned aircraft electrical circuit network voltage drop prediction and evaluation method, the voltage drop simulation calculation of the terminal load specifically involves: simulating the voltage drop at the load end of the onboard equipment connected to the electrical circuit network inside the aircraft.

[0027] Beneficial effects: The present invention provides a method for predicting and evaluating the voltage drop of an aircraft electrical circuit network, which can combine aircraft electromagnetic field simulation with circuit simulation, effectively predict and evaluate the impact of the common-mode impedance of the electrical circuit network on the voltage drop of airborne equipment during the design stage of composite aircraft, and realize rapid iteration of the electrical circuit network design of aircraft composite structures, which has a positive effect and value on the design and verification of composite aircraft models.

[0028] The present invention can effectively predict and evaluate the impact of the common-mode impedance of the electrical circuit network on the voltage drop of airborne equipment during the design stage of composite aircraft, realize the rapid iteration of the electrical circuit network design of the aircraft composite structure, and has a positive effect and value on the design and verification of composite aircraft models.

[0029] In summary, the present invention solves the problem of large voltage drop caused by common mode impedance and fault current, lightning induced current, and HIRF coupled current in the electrical circuit network design of composite aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1This is an example diagram of aircraft cable and electrical circuit network connections;

[0031] Figure 2 It is a flowchart of the steps for estimating voltage drop in aircraft electrical circuit network;

[0032] Figure 3 This is an example diagram of the impedance matrix between aircraft cables and electrical loop networks;

[0033] Figure 4 This is an example diagram of the Thevenin equivalent circuit model for circuit simulation calculation. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] Example 1. A method for predicting and evaluating voltage drop in an aircraft electrical circuit network, comprising:

[0036] Step 1: Create a simulation model of the aircraft structure, electrical loop network, and interconnecting cables in electromagnetic field simulation software, and simplify, repair, and mesh it into an aircraft electromagnetic model. Define the terminals of the cables and the terminals of the electrical loop network grounding structure on the aircraft electromagnetic model. The mutual coupling between the cables and the electrical loop network is characterized by the defined terminal impedance matrix.

[0037] Step 2: Use the frequency domain full-wave S-PEEC algorithm to calculate and solve the terminal impedance matrix between the cable and the electrical loop network.

[0038] Step 3: Use the vector fitting method to convert the terminal impedance matrix obtained in step 2 into a zero-pole (Zeros-Pole) expression.

[0039] Step 4: Convert the zero-pole expression into a state-space expression through data expression conversion.

[0040] Step 5: Convert the state-space expression into a netlist model that can be used for circuit simulation analysis input. The format of the netlist model is .CIR format.

[0041] Step 6. Import a netlist model (.CIR format) that expresses the terminal impedance matrix between the cable and the electrical loop network into the circuit simulation software. Define the excitation source that satisfies the aircraft power supply system and the terminal load to be simulated and solved. Establish a Thevenin equivalent circuit simulation model and simulate and calculate the voltage drop of the terminal load.

[0042] Example 2. Figure 1-4As shown, a prediction and evaluation method for the voltage drop of the electrical circuit network of an aircraft is used to predict and evaluate the voltage drop of the electrical circuit network of a composite aircraft, etc., to achieve rapid iteration of the design of the electrical circuit network of a composite structure, and to solve the problem of large voltage drop caused by the common mode impedance and fault current, lightning induced current, and HIRF coupling current of the electrical circuit network of a composite aircraft.

[0043] The specific steps of the method for predicting and evaluating voltage drop in an aircraft electrical circuit network are as follows:

[0044] Step 1: Create a simulation model of a composite aircraft structure, electrical loop network, and interconnected cables in the electromagnetic field simulation software, simplify, repair, and mesh it into an aircraft electromagnetic model, define the terminals of the cables and the terminals of the electrical loop network grounding structure on the aircraft electromagnetic model, and define the mutual coupling between the cables and the electrical loop network through the defined terminal impedance matrix [Z m ] to represent.

[0045] For example, see Figure 1 , N cables (L1, L2, ...., LN) are connected to different parts of the electrical loop network inside the aircraft electromagnetic model. G1, G2, ...., GN are the ground terminals on the electrical loop network corresponding to the cables. V L1 is the voltage across cable L1, V LN is the voltage across the cable LN, V G1 is the voltage at both ends of the electrical circuit network ground corresponding to cable L1, V GN is the voltage across the ground of the electrical circuit network corresponding to cable LN, I L1 is the current flowing through cable L1, I LN is the current flowing through the cable LN, I G1 is the current flowing through the ground of the electrical circuit network corresponding to cable L1, I GN It is the current flowing through the ground of the electrical circuit network corresponding to the cable LN. G,G The sub-impedance matrix is ​​an impedance matrix that only contains the grounding model of the electrical loop network. The items on the diagonal are the impedance between the two ends of a certain electrical loop network grounding, and the items on the off-diagonal are the mutual impedances between different grounding ends (that is, the voltage induced on the other two ends of a grounding when a unit current flows through the two ends of a grounding). Z L,L The sub-impedance matrix is ​​an impedance matrix that only contains cable models. The items on the diagonal are the impedance of a certain cable, and the items on the off-diagonal are the mutual impedances between different cables (i.e., the voltage induced on another cable when a unit current flows through a certain cable). G,L and Z L,G The sub-impedance matrix is ​​the mutual impedance matrix between the cable and the ground structure of the electrical loop network, Z G,LIt represents the voltage induced on the ground of the electrical circuit network when the cable passes a unit current. L,G It represents the voltage induced on the cable when a unit current flows through the electrical loop network grounding structure. The items on the diagonal are the mutual impedance between the cable and its corresponding electrical loop network grounding structure.

[0046] .

[0047] Step 2: Use the frequency domain full-wave S-PEEC algorithm to calculate and solve the terminal impedance matrix [Z m ].

[0048] Step 3: Use the vector fitting method to transform the terminal impedance matrix [Z m ] is converted to a zero-pole expression, which is expressed as:

[0049] .

[0050] Step 4: Convert the zero-pole expression into a state-space expression through data expression conversion. The expression is:

[0051] .

[0052] Step 5: Convert the state-space expression into a netlist model that can be used for circuit simulation analysis input. The format of the netlist model is .CIR format.

[0053] Step 6. Import the netlist model (.CIR format) that can express the terminal impedance matrix between the cable and the electrical loop network into the circuit simulation software, and define the excitation source V that meets the power supply system of a composite aircraft. S and airborne equipment load R L , establish the Thevenin equivalent circuit simulation model and simulate the voltage drop of the computer-mounted equipment load.

[0054] Example 3. See Figure 1-Figure 4 The prediction and evaluation method for the voltage drop of the aircraft electrical circuit network adopted in this embodiment is specifically as follows:

[0055] Step 1: In the Galileo EMT electromagnetic field simulation software, a model of a composite aircraft structure, an electrical loop network, and a cable is imported. The model is simplified, repaired, and meshed into an aircraft electromagnetic model. The terminals of the cable and the terminals of the electrical loop network grounding structure are defined on the aircraft electromagnetic model. The mutual coupling between the cable and the electrical loop network is determined by defining the terminal impedance matrix [Zm ] to represent.

[0056] In an embodiment, [Z m ] is:

[0057] ,

[0058] See Figure 3 , Z G1,G1 is the impedance between the two ends of the electrical circuit network corresponding to the cable, Z G1,L1 Z is the voltage induced on the ground of the electrical circuit network when the cable passes a unit current. L1,G1 Z is the voltage induced on the cable when a unit current flows through the grounding structure of the electrical loop network. L1,L1 is the impedance of the cable itself, I c is the current flowing through the cable, I g The current flowing through the ground of the electrical circuit network.

[0059] Step 2: In the Galileo EMT electromagnetic field simulation software, the frequency domain full-wave S-PEEC algorithm is used to calculate and solve the terminal impedance matrix between a certain cable and the electrical circuit network inside a composite aircraft [Z m ].

[0060] Step 3: Use the vector fitting method to transform the terminal impedance matrix [Z m ] is converted to a zero-pole expression, which is expressed as:

[0061] .

[0062] Step 4: Convert the zero-pole expression into a state-space expression through data expression conversion. The expression is:

[0063] .

[0064] Step 5: Convert the state-space expression into a netlist model that can be used for circuit simulation analysis input. The format of the netlist model is .CIR format.

[0065] Step 6. In the PSpice Designer circuit simulation software, import the netlist model (.CIR format) that can express the terminal impedance matrix between the cable and the electrical loop network, and define the excitation source V that meets the power supply system of a composite aircraft. S and airborne equipment load R L , establish the Thevenin equivalent circuit simulation model, see Figure 4 , simulates the voltage drop of the computer's onboard equipment load.

Claims

1. A method for predicting and evaluating voltage drop in an aircraft electrical circuit network, characterized in that: include: S1. Build an aircraft electromagnetic model, define the terminals of the cables and their electrical loop network grounding structure, and characterize the mutual coupling between the cables and the electrical loop network using a terminal impedance matrix. S2. Use the frequency domain full-wave S-PEEC algorithm to solve the terminal impedance matrix; S3. Convert the terminal impedance matrix into a zero-pole expression; S4. Convert zero-pole expressions into state-space expressions; S5. Converting the state-space expression into a netlist model that can be used as input for circuit simulation analysis; S6. Import the netlist model into the simulation environment, define the excitation source and terminal load, establish the Thevenin equivalent circuit simulation model, and simulate and calculate the voltage drop of the terminal load; S1 is as follows: Cables L1~LN are connected to different parts of the electrical circuit network inside the aircraft electromagnetic model. G1~GN are the ground terminals on the electrical circuit network corresponding to the cables. V L1 ~V LN is the voltage across the cables L1 to LN, V G1 ~V GN is the voltage at both ends of the electrical circuit network ground corresponding to cables L1 to LN, I L1 ~I LN is the current flowing through cables L1 to LN, I G1 ~I GN The current flowing through the ground of the electrical circuit network corresponding to cables L1 to LN; Z G,G The sub-impedance matrix is ​​an impedance matrix that only contains the grounding model of the electrical loop network. The items on the diagonal are the impedance between the two ends of a certain electrical loop network grounding, and the items on the off-diagonal are the mutual impedances between different grounding ends. L,L The sub-impedance matrix is ​​an impedance matrix that only contains the cable model. The items on the diagonal are the impedance of a certain cable, and the items on the off-diagonal are the mutual impedances between different cables. G,L and Z L,G The sub-impedance matrix is ​​the mutual impedance matrix between the cable and the ground structure of the electrical loop network, Z G,L It represents the voltage induced on the ground of the electrical circuit network when the cable passes a unit current. L,G It represents the voltage induced on the cable when a unit current flows through the electrical loop network grounding structure. The items on the diagonal are the mutual impedance between the cable and its corresponding electrical loop network grounding structure. Then the terminal impedance matrix is ​​expressed as: 。 2. The method for predicting and evaluating voltage drop in an aircraft electrical circuit network according to claim 1, wherein: In S3, the terminal impedance matrix is ​​converted into a zero-pole expression using a vector fitting method.

3. The method for predicting and evaluating voltage drop in an aircraft electrical circuit network according to claim 1, wherein: In S3, the zero-pole expression is: ； Where, H ( s ) represents a rational fraction, N represents the order, s represents the frequency domain variable, p n represents the extreme point of the fraction, α n represents the remainder of a fraction, d Represents a real number.

4. The method for predicting and evaluating voltage drop in an aircraft electrical circuit network according to claim 1, wherein: In S5, the file format of the netlist model is .CIR.

5. The method for predicting and evaluating voltage drop of an aircraft electrical circuit network according to claim 1, wherein: In S6, the import of the netlist model and the definition of the excitation source and terminal load are performed in the PSpice Designer circuit simulation software.

6. The method for predicting and evaluating voltage drop in an aircraft electrical circuit network according to claim 1, wherein: In S6, the voltage drop simulation calculation of the terminal load specifically includes: simulation calculation of the voltage drop at the load end of the onboard equipment connected to the electrical circuit network inside the aircraft.

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