Simulation And Forecast Technology Of Electromagnetic Compatibility In Automobile

The simulation and forecast of EMC (electromagnetic compatibility) on vehicle is one of the new developing technology, it bases on some kind of mathematics theories, and simulates the EMC interference on vehicle by using software. During the early development of the product, the virtual test or half virtual (hardware in loop) is performed, so that avoids the test and then to modify PCB after the product has been manufactured. It helps to control the cost and cycle of the product.The simulation and forecast of EMC on vehicle developed much early overseas, many big automobile manufacturers have developed relevant simulation software by themselves or cooperation with other software company, such as simulation software ANSOFT-HFSS of ANSOFT company of American, simulation software CTS-Microwave-Studio of CTS company of Germany, simulation software FLO/EMC of Flomerics of U.K.. They have done much work on the simulation on antenna, electromagnetic field, shielding efficiency, and have developed a series of integrated systems.Most domestic components suppliers of automobile considered only whether the function of the products meet with requires of the automobile manufacturer, considered rarely the electromagnetic compatibility during the development or localization. However, the automobile manufacturers have not strict control method; and automobile research institute inside only performed the test according to the test specification of nation, had no opinion on the development of the products, especially on the aspect of simulation and precast, they have not such kind of software, equipment and test method.This paper aim at the problem between the simulation and actually test, it applies the simulation test to all stage of the development of the product, the HiL (hardware in loop) is also included, and HiL is no more in the range of forecasting for the development of components, but for the development of the whole automobile, it is a very important parts of simulation. The main work of this paper: Oriented on the transmission line, the coupling interference between the wire-harness was simulated; at the same time, the based on other theory simulation curves are also presented, different requirements, such as require of high frequency, require of mass wire-harness, the different theory combined with transmission line theory is used, it helps to enhance the efficiency of simulation. Firstly, the coupling interference between two wires is simulated through changing the distance between the two wires; secondly, the coupling interference is simulated through changing the height between the wires and the car-body( the car-body is considered as ideal ground); then the coupling interference is simulated through changing the impedance of the terminations of the two wires. All the simulations are based on two-wire system, they also can be extended to multiple wires system.Based on the antenna theory, the matrix solve of random shape antenna was presented. The coupling current and voltage of the antennas in the glass of rear window and on the top of the car are simulated. The coupling electric field, magnetic field and scatter field are simulated, based on the mathematic mode of amplifier of antenna in the rear window, different simulation curves which based on different theory are also presented for the comparing with each other. The near electric field simulation of three different planes are presented when we analyzed the antenna on the top of the car body, they are the horizontal plane of the top of the antenna, the horizontal plane of the bottom of the antenna and the vertical plane of the car. The near electric field is simulated at different frequency range by adding electromagnetic field from the far distance more than 10 meter.The influence on the receive effect of the antenna and protection from the shielding and leakage from the slot of the car body is one of the important aspect when considering the EMC of the automobile. Here combined with the specialty of the car body, the shielding efficient of monolayer shielding body and the theory of leakage of slot is induced, the coupling current on the termination of the wire in the car body and outside the car body are simulated, it shows that the car body has almost no protesting again the emission interference form outside of the automobile, because there are too much holes and slots in the car body.When the controllers in the car are considered as interference source, wavelet theory was introduced to identify the different conductive interference source through pick up the specialty energy of the source. such as the voltage decline caused by the engine starting, it can be identified by changing three different specialty energy and four layer wavelet decomposing. HiL is used in the immunity test of developing components, so that we can analyze the immunity specialty of the components, it is also a forecasting method for the development of the whole automobile.The creative works of this paper as follow:The coupling interference is simulated according to the transmission line theory, combined with other electromagnetic field theory. It helps to instruct the layout of wire-harness and avoid the degrading of EMC caused by the coupling interference between wire-harness.The coupling interference of AM/FM antenna in the rear window and wipe-like antenna caused by far electromagnetic field are simulated, and the near electronic field of different plane are simulated.The shielding effective of car body are clarified by the simulation of the terminal inside and outside car body; and the leakage of hole and slot are analysed.Wavelet theory is used to identify the conduct interference source, and HiL is used for the immunity test of the components, and is listed in the precasting method for the development of the whole automobile, and it helps to the conductive EMC test of the automobile.