System-level Simulation Of Electromagnetic Interference

The development of electronic products changes with each passing day, and the design of system and motherboard is becoming more and more complex, meanwhile the design cycle is constantly shrinking, which makes it more and more difficult to solve the problem of electromagnetic compatibility (EMC). With the improvement of the frequency of electronic products, the principle which is used to analyzing the problem of EMC also loses its effectiveness, and the misuses usually happen. Due to this, most of the electronic products do not one-time pass through the EMC testing, which forces the cost of later rectification high, and if delay sale on market, the loss will be immeasurable. In order to solve above problem, the research object of this paper is showed, which is system-level simulation of electromagnetic interference.This paper firstly expounds several basic theories or concepts which are closely related to the simulation of electromagnetic compatibility:the concept of Fourier transform, the concept of common mode interference and the concept of parasitic parameters. Moreover, these concepts are endowed with many new connotations. On the basis of these concepts, the concepts of Maxwell equation and simulation algorithm are elaborated as well. The expounding of these concepts is not only of great importance for understanding the actual electromagnetic compatibility problems in engineering field, but also providing help for us to carry out the simulation of electromagnetic compatibility smoothly.The simulation algorithm used in this paper is based on the full wave electromagnetic algorithm of Maxwell equation which has a super-high simulation bandwidth and less limitation conditions, therefore, it is suitable for most of the electromagnetic compatibility issues.For the electromagnetic compatibility simulation in system level, in addition to the signal of the simulation PCB, the modeling of the chassis, cables, connectors and other modules should be also taken into consideration. At present, there are the following problems existing in the common system simulation in the field:one, only a module in the system is simulated in the system, so it has a relatively poor application. Two, all the modules are taken into account, but it is lack of the utilization of the original project documents, therefore, a large number of simple models are used, resulting in inaccurate simulation results. However, if we use a lot of actual engineering documents in the simulation, it will result in a huge amount of computation, at the same time, because the model is too complex and huge, it is easy to cause errors which will further lead to situation that the simulation can not continue. According to the equivalent principle, the whole simulation process is divided into three modules in the paper, the main board (PCB) simulation module, the simulation module of the mechanism and the connector and the cable simulation module. The three layers of modules are inserted from the inside to the outside. The output of one module is exactly the input of the next adjacent module, but they are mutually independent with each other, thus it will greatly reduces the amount of computation brought by too large simulation model and improves the simulation efficiency. At the same time, it also ensures the high accuracy for simulation, at the same time, as what we carry out is the whole link simulation of an electromagnetic interference path, the application range of the simulation method for this topic is relatively wide.In this paper, the practical project prototype is used to carry on the detailed analysis of the interference principle and the comparison of the simulation data before and after the reform and correction is also carried out. By comparing the simulation data of graph, the the correctness of the reform and correction plan is verified, which will save the cost for modification and the production of prototype. At the same time, the paper also makes it prominent that the simulation method for the subject is fast, economical and effective after the comparison being made.