With the large-scale application of modern electronic technology in automobiles, mechanical cars in the traditional sense have been replaced by modern electronic vehicles. Various electronic and electrical products have accounted for 30% of the total cost of automobiles, and even more, and this trend Constantly developing.
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The application of electronic technology plays a very important role in solving the economic, safety and comfort of automobiles. However, the development and application of many electronic products has also brought an important issue that cannot be ignored in the automotive industry. --- Research on automotive electromagnetic compatibility.
Electromagnetic Compatibility (EMC) is a new technology introduced by electromagnetic interference. It refers to the ability of an electrical installation or electrical system to operate in a specified environment without interference or environmental interference. To solve the electromagnetic compatibility problem, we must first find the source of interference in the automotive electromagnetic environment. Interference sources can be classified into in-vehicle interference sources and off-board interference sources.
Electromagnetic interference source
In-vehicle interference source
It refers to the electromagnetic interference generated by various electronic and electrical systems on the vehicle. The electromagnetic interference generated by electrical and electronic equipment is due to the fact that many wires, coils and electrical appliances with contacts in the electronic products used in automobiles have different capacitances and inductances, and any closed circuit with inductance and capacitance will oscillate. Loop. When electrical equipment works to generate sparks, high-frequency oscillations are generated and emitted into the air in the form of electromagnetic waves, which cause different degrees of interference to the normal operation of radios, televisions and other radios within a few hundred meters of the vehicle and surrounding. . The interference generated by the automobile not only affects the normal operation of the external electronic and electrical equipment, but also affects the normal operation of the electronic and electrical equipment. Therefore, the electronic environmental interference may adversely affect the performance of the electronic product, and may even cause its function to be lost.
The radio interference source of a car is mainly the ignition system of the engine, and the interference wave comes from the high frequency oscillation of the secondary voltage of the ignition system. Second, electromagnetic waves are also generated when the generator load current is abrupt and rectified. Starters, generators, flashers, contact-type electromagnetic vibration horns, wipers, instrumentation systems, etc. also produce small electromagnetic waves that conduct and interfere with radiation.
Interference electromagnetic waves generated by automotive electrical appliances have a pulse characteristic and a wide frequency band, and the frequency thereof is generally between 0.15 and 1000 MHz. Interference electromagnetic waves generated by automobile electrical appliances, divided into conductive interference and radiation interference. Conducted and interfering electromagnetic waves are directly input into the radio equipment and electronic equipment through the car wires, while the radiated interference electromagnetic waves are transmitted in space, and are input into the radio device through an antenna (such as an ignition system high voltage line equivalent to an antenna).
Vehicle interference source
External electromagnetic interference caused by natural phenomena, social environment, etc. has a serious impact on automotive electronic systems. External electromagnetic interference refers to various artificial electrical equipment, such as: high-voltage transmission lines, tram tracks, radio and television equipment, and radio communication. Electromagnetic radiation radiated from equipment and the like, and electromagnetic interference caused by natural phenomena such as lightning.
Research Status of Foreign Automotive Electromagnetic Compatibility
At present, the world's automobile developed countries have made some achievements in automotive electromagnetic compatibility research, forming a set of automotive electromagnetic compatibility system. This is mainly reflected in: relatively complete automotive electromagnetic compatibility test standards and specifications; effective mechanisms for electromagnetic compatibility testing, management and certification of automotive vehicles and components; high-precision automotive electromagnetic compatibility test system; Large-scale automotive electromagnetic compatibility prediction, analysis and design software. Third-party testing and certification institutions, automotive research institutions, etc. have also carried out research on automotive electromagnetic compatibility, and have established their own electromagnetic compatibility laboratory.
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