CN106055845A - Electromagnetic compatibility modeling method - Google Patents

Abstract

The invention belongs to the field of electromagnetic compatibility and mainly solves the complexity problem of electromagnetic compatibility analysis and modeling. A unified packaging EMC modeling method that communicates with the outside world through ports is designed. It uses multi-port networks to describe the interference sources, propagation paths and sensors in a unified manner. The interference source, transmission path, and sensor are all regarded as black boxes, which communicate with the outside world through ports, and any window that allows the system to have an electromagnetic energy relationship with the outside world is defined as a port. Compared with the traditional EMC modeling method, this method has the characteristics of consistency and easy combination. The invention has strong practical value, can be applied to different levels of electromagnetic compatibility analysis, and has good application prospects in the fields of electromagnetic interference suppression, electromagnetic compatibility performance analysis and evaluation, electromagnetic protection and the like.

Description

An Electromagnetic Compatibility Modeling Method

technical field

The invention relates to an electromagnetic interference and electromagnetic compatibility analysis method, in particular to an electromagnetic compatibility modeling method, which can be applied to the analysis of electromagnetic compatibility performance at different levels such as system level, equipment level and circuit board level.

Background technique

The electromagnetic compatibility model is a mathematical description of the electromagnetic interference mechanism and experimental analysis, and is the basis for the prediction and analysis of electromagnetic compatibility. According to the principle of three elements of electromagnetic interference, the interference model is divided into interference source model, transmission path model and sensor model.

In terms of levels, electromagnetic compatibility analysis can generally be divided into three levels: system level, equipment level, and circuit board level. Because the objects at each level are highly targeted, the analysis methods and modeling methods will also be clearly distinguished. The first level is the board-level electromagnetic compatibility prediction, which needs to establish the electromagnetic behavior model of the PCB board; the second level is the electromagnetic compatibility prediction of the equipment, such as the electromagnetic compatibility prediction of the electronic and electrical components such as multi-core wires and drivers, and the equipment The EMC prediction between equipment and equipment requires the establishment of models of multi-conductor transmission lines, linear and nonlinear loads; the third level is system-level EMC prediction, which is aimed at various equipment such as aircraft, ships, missiles, and spacecraft. For EMC prediction of complex electronic and electrical equipment systems, it is necessary to establish an EMC model of a large system and a spatial propagation model of radio waves.

The traditional electromagnetic compatibility model is easy to understand, but it cannot fully reflect the process of interference generation, propagation and formation; in addition, for different levels of electromagnetic compatibility analysis, the modeling methods are diverse, and it is difficult to achieve high versatility, which is not conducive to Further development of electromagnetic compatibility technology.

Contents of the invention

In order to overcome the shortcomings of the existing EMC modeling methods, the present invention provides a new EMC modeling method, which is called a consistent modeling method for EMC.

The technical solution adopted in the present invention is an electromagnetic compatibility modeling method, which is characterized in that it includes the following steps:

The first step is to encapsulate the three elements of interference source, transmission path and sensitive equipment.

The traditional electromagnetic compatibility modeling method is to model the three elements of electromagnetic interference separately, but this method uses a multi-port network to describe the model of the interference source, propagation path and sensor in a unified manner. The sources of interference, transmission paths, and sensors are all considered as black boxes, which communicate with the outside world through ports.

The second step is to determine the port of the packaged model.

The encapsulated model communicates with the outside world through ports. Any window that allows the system to have an electromagnetic energy relationship with the outside world is defined as a port. All ports of the model are bidirectional, i.e. contain both input and output. When the actual system can only generate energy input or energy output at a certain port, it can degenerate into a one-way port.

Ports include not only the input and output ports of signals in the traditional sense, such as antennas, signal interfaces, power interfaces, etc.;

The third step is to build a model.

To determine the port type of the model is to find the function expressions and function parameters that the output of each port of the model is the same as the input. According to the type of model entity, the port types can be divided into three types: circuit port, electromagnetic port and hybrid port.

The establishment of the circuit model is mainly implemented according to the category of the circuit, and the theory and method of circuit modeling are relatively mature.

The establishment of the electromagnetic model is mainly based on the physical properties of the electromagnetic field, through a set of differential equations or integral equations, and determined according to the boundary conditions. There are three methods for solving the boundary value problem of electromagnetic field: the first is the analytical method, the second is the approximate method, and the third is the numerical method.

The establishment of the hybrid model needs to combine the analysis method of the circuit model and the analysis method of the electromagnetic model. The hybrid model can be re-divided into two types of subunit models, circuit model and electromagnetic model.

Compared with the traditional electromagnetic compatibility modeling method, the invention has the characteristics of consistency and easy combination. The research results of electromagnetic compatibility prediction can be easily introduced to meet the requirements of different levels of electromagnetic compatibility analysis, and achieve the purpose of using one modeling method to meet the requirements of different levels of electromagnetic compatibility analysis. The invention has strong practical value, can be applied to different levels of electromagnetic compatibility analysis, and has good application prospects in the fields of electromagnetic interference suppression, electromagnetic compatibility performance analysis and evaluation, electromagnetic protection and the like.

Description of drawings

Figure 1 is a schematic diagram of the EMC consistency modeling method;

Fig. 2 is a schematic diagram of the shelter;

Figure 3 is the EMC consistency modeling of the shelter;

Figure 4 is the topological relationship of the model;

Figure 5 is the basic structure of the front end of the radar system;

Figure 6 is the EMC consistency modeling of the front end of the radar system.

detailed description

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

The first step is to encapsulate the model.

Fig. 1 is a schematic diagram of an electromagnetic compatibility consistent modeling method, where p ₁ to p _N are ports. The use of bidirectional ports to describe the energy exchange window between the device and the outside world can accurately reflect the interaction between the system and the outside world. In the actual system, the ideal input port and output port do not exist. The so-called ideal input (output) port means that the energy will only be transferred from the outside (inside) to the inside (outside). Defined as unidirectional, is an approximation taken for simplicity. However, this approximation may cause important EMI causes to be neglected.

The second step is to determine the port of the packaged model.

The output of any port is a function of the input of all ports, this relationship is described by the following equations:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ...</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ...</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ {\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ...</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, p _ti represents the output of the i-th port;

p _ri represents the input of the i-th port.

The relationship between ports is not limited to a one-to-one relationship. The input of a port can be the weighted sum of the output of multiple other model ports; the output of a port can also have an impact on the port input of other multiple models.

The relationship between ports can be written in matrix form

[P]=[Γ][P] (2)

In the formula, [P] is a vector composed of all ports;

[Γ] is the transmission relationship between ports, and for unrelated ports, the corresponding element in [Γ] is 0.

An example of a vehicle-mounted shelter is used to illustrate the EMC consistency modeling method.

Figure 2 is a schematic diagram of the shelter. It is divided into two compartments. In compartment 1, there is a computer operation compartment and two computers for data processing; in compartment 2, there is a receiver protected by a receiver cabinet, and an antenna is connected outside the compartment. The receiver data is connected to the computer through the data cable.

EMC consistency modeling is shown in Figure 3. The dotted line in the figure is the interaction relationship between ports. The numbering rules of ports p _{i, j, k} are: i: model level; j: model number of the same level; k: port number of the same model.

According to the level of the model, the topological relationship is established as shown in Figure 4. If the electromagnetic compatibility analysis between systems is concerned with the energy exchange between the shelter and the external space, then only the shelter model needs to be extracted; if the electromagnetic compatibility analysis at the equipment level is performed, It is necessary to extract the four-level model where the PC is located; for circuit-level EMC analysis, it is necessary to conduct more in-depth, detailed, and lower-level EMC consistency modeling.

In the actual EMC analysis, the EMC consistency modeling should be carried out from the bottom of the required analysis problem in accordance with the principle of "from small to large".

The unified modeling method for electromagnetic compatibility analysis has the following characteristics:

(1) Consistency

The interference element or a part of the interference element is regarded as an independent unit, and the connection between the unit and the outside world is realized through the port. The unit is a model entity, and the behavior of the model is described by the transfer function between the unit ports. Therefore, no matter it is the interference source, the interference transmission path or the sensitive equipment or a part of them, it can be defined as a model entity, so that the models corresponding to the various units have the same structure, which will provide analysis, calculation and computer simulation programs. Bring great convenience.

(2) combination

Models are easy to combine and grade. After using the EMC consistency modeling method to describe the system, the structure of each model is the same, but the levels can be different, and the model units at the bottom can be easily combined into higher-level units.

The connected ports between the model entities are directly connected, and the remaining ports are used as the parameters of the high-level unit ports; the high-level unit ports are their weighted combination.

(3) Independence

Vertical independence: Model entities are only connected to model entities of higher order and lower order, and there is no direct connection between model entities with a difference of more than two orders. are vertically independent.

Horizontal independence: There is no direct connection between the same-level model entities that are not subordinate to the same high-level unit, and they are horizontally independent.

A typical radar system front-end is taken as an example to illustrate the characteristics of EMC consistency modeling. The basic structure of the radar system front end is represented by Fig. 5, which models the radar system front end. The three-level model (bottom model) is IF amplifier, IF filter, down-conversion mixer, low-noise amplifier, RF filter, local oscillator 1, local oscillator 2, up-conversion mixer, filter, power amplifier, transceiver Switches and antennas; the second-level model is antenna, transceiver switch, transmitting circuit and receiving circuit; the first-level model (top model) is the radar front end.

Figure 6 shows the EMC conformance modeling of the radar system front end.

The embodiment of model consistency: because only the electromagnetic properties of the modeling target are concerned, the structures of the three-level models are actually the same, and their electromagnetic properties are described by ports.

The embodiment of model combination: the three-level model IF amplifier, IF filter, down-conversion mixer, low-noise amplifier, radio frequency filter, and local oscillator 1 form the second-level model receiving circuit; the third-level model local oscillator 2, up-conversion The mixer, filter, and power amplifier form a second-level model transmitting circuit; while the second-level model antenna, transceiver switch, transmitting circuit and receiving circuit are combined to form a complete front-end of the radar system. Among them, the input port P1 _of the up-conversion mixer becomes the input port of the intermediate frequency signal of the radar front end through the transmitting circuit; the input port _P3 of the intermediate frequency amplifier becomes the output port of the intermediate frequency signal of the radar front end through the receiving circuit; the transceiver port of the antenna is connected to The front end of the radar becomes the wireless electromagnetic signal port of the whole radar system.

The embodiment of the longitudinal independence of the model: the electromagnetic characteristics of the radar front-end are reflected by four second-level models, and the third-level models, such as the up-conversion mixer, cannot directly affect the electromagnetic characteristics of the radar front-end. Although in a physical sense, the IF signal input of the radar front-end is realized by an up-conversion filter, but from the perspective of the orderliness of modeling and the convenience of subsequent analysis, such a setting is reasonable.

The embodiment of the lateral independence of the model: take the low noise amplifier subordinate to the receiving circuit and the power amplifier subordinate to the transmitting circuit as examples. Since the two have different affiliations, there is no direct connection between them. Starting from the actual circuit, the signal generated by the power amplifier needs to pass through the receiving switch to generate energy leakage, and then pass through the RF filter before reaching the low noise amplifier. Therefore, the setting of the model's horizontal independence is in line with the physical meaning of the modeling goal.

Claims (9)

1. an electromagnetic compatibility modeling method, it is characterised in that comprise the steps:

These three elements of interference source, delivering path and sensitive equipment are packaged, carry out Unify legislation with multiport network by the first step The model of interference source, route of transmission and sensor, is accordingly to be regarded as flight data recorder by interference source, delivering path and sensor, this flight data recorder By port with extraneous contact；

Second step, determines the port of model after encapsulation, and the model after encapsulation is contacted with the external world by port；

3rd step, determines the port type of model, finds the output of each port of model to join with function expression and the function of input Number, sets up model.

2. electromagnetic compatibility modeling method as claimed in claim 1, is characterised by, described port is sent out with extraneous for allowing system The window of raw electromagnetic energy relation, all of the port of model is all two-way, i.e. comprises input and output, when real system is at certain When Single port is only possible to produce energy input or energy output, one way ports can be deteriorated to.

3. electromagnetic compatibility modeling method as claimed in claim 2, it is characterised in that described port include antenna, signaling interface, Power interface, also comprises slit, undesirable material wave transparent energetic interaction approach.

4. electromagnetic compatibility modeling method as claimed in claim 1, it is characterised in that described port type is divided into circuit port, Solenoid ports and Hybrid port three class.

5. electromagnetic compatibility modeling method as claimed in claim 1, it is characterised in that described model is divided into circuit model, electromagnetism Model and mixing model three class.

6. electromagnetic compatibility modeling method as claimed in claim 5, it is characterised in that the foundation of described circuit model is according to circuit Classification implement.

7. electromagnetic compatibility modeling method as claimed in claim 5, it is characterised in that the foundation of described electromagnetic model is according to electricity The physical property in magnetic field, by one group of differential equation or integral equation, and determines according to boundary condition.

8. electromagnetic compatibility modeling method as claimed in claim 7, it is characterised in that the boundary value side of solving of described boundary condition Method is analytic method, or method of approximation, or numerical method.

9. electromagnetic compatibility modeling method as claimed in claim 5, it is characterised in that the foundation of described mixed model needs to combine The analysis method of circuit model and the analysis method of electromagnetic model, be divided into circuit model and the two kinds of son of electromagnetic model is single Meta-model.