The large-scale application of modern electronic technology in automobiles plays a very important role in the economy, safety and comfort of automobiles. However, with the increase of the number of many automotive electronic products, the increase of the working frequency and the increase of the power, the working environment of the automobile is filled with electromagnetic waves, which causes the electromagnetic interference problem to become increasingly prominent, which affects the normal operation of the automobile electronic equipment and causes driving. Inconvenience, but the damage to the corresponding electrical components, endangering the safety of the riders. Therefore, electromagnetic compatibility EMC of automotive electronic equipment is receiving more and more attention.
The electromagnetic environment formed by the work of automotive electronic equipment has the characteristics of complexity and variability, which means that the in-vehicle system is subject to a wide range of interference sources. According to the source classification of electromagnetic interference, it can be divided into vehicle exterior interference, vehicle interior interference and vehicle body static interference.
Outside interference
External interference refers to the influence of external electromagnetic interference caused by natural phenomena, social environment, etc. on the automotive electronic system. Such as: high-voltage transmission lines, near tram tracks, radio and television equipment and radio communication equipment, such as electromagnetic radiation that interferes with the car, as well as electromagnetic interference caused by natural phenomena such as lightning and sunspot radiation.
2. In-vehicle interference
In-vehicle interference refers to internal mutual interference during the operation of automotive electronic equipment. For example, the ignition system of the engine, the flasher, the contact type electromagnetic vibration electric horn, the wiper, and the instrument system all generate certain conducted interference and radiated electromagnetic waves. Conducted interference is directly input into the radio equipment and electronic equipment through the car wire, and the radiated interference is transmitted in space. The antenna (such as the ignition system high voltage line is equivalent to the antenna) is input into the radio device, thereby affecting the normal operation of the electronic and electrical equipment.
3. Vehicle body static interference
The static interference of the car body is related to the car itself and the external environment. Because the car body and the air are rubbed at high speed when the car is running, unevenly distributed static electricity is formed on the car body, and the electrostatic discharge will form an interference current on the car body, and at the same time generate a high frequency. Radiation, which forms electromagnetic interference to automotive electronic equipment.
In summary, the electromagnetic compatibility of automotive electronic equipment includes two aspects, one is electromagnetic emission, which measures electromagnetic interference generated by the system; the other is electromagnetic sensitivity, which measures the ability of the system to resist electromagnetic interference during normal operation. To comprehensively improve the electromagnetic compatibility of automotive electronic equipment, it can be considered from three aspects, one is to reduce the intensity of electromagnetic interference emitted by equipment; the second is to suppress the transmission of electromagnetic interference; the third is to reduce the intensity of receiving interference of electromagnetic sensitive components of equipment. Each aspect highlights the importance of EMC testing.
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