Status Quo and Development Trend of Automotive Electromagnetic Compatibility at Home and Abroad

With the large number of applications of modern electronic technologies in automobiles, mechanical vehicles in the traditional sense have been replaced by modern electronic vehicles. Various electronic and electrical products have accounted for 30% or even more of the total cost of automobiles. In constant development.

The application of electronic technology plays an important role in solving the economical, safety, and comfort aspects of automobiles. However, the development and application of numerous electronic products have also brought an important issue to the automotive industry that cannot be ignored - --- Research on automotive electromagnetic compatibility.

Electromagnetic Compatibility Technology (EMC) is a new technology derived from electromagnetic interference. It refers to the ability of electrical installations or electrical systems to operate without interference or environmental disturbances. To solve the electromagnetic compatibility problem, we must first find the source of interference in the automotive electromagnetic environment. Interference sources can be divided into in-vehicle interference sources and off-board interference sources.

Electromagnetic Interference Sources The intra-vehicle interference sources refer to the electromagnetic interference generated by various electrical and electronic systems in the vehicle. The electromagnetic interference generated by electronic and electrical equipment is due to the fact that many electric wires, coils, and electrical appliances with contacts in the electronic products used in automobiles have different capacitances and inductances, and any closed loop with inductance and capacitance will oscillate. Loop. When electrical equipment produces sparks, high-frequency oscillations are generated and emitted into the air in the form of electromagnetic waves, which cause different levels of interference to the normal operation of radios, televisions, and other radio devices within and around several hundred meters of the car. . The interference generated by automobiles will not only affect the normal operation of external electronic equipment, but also affect the normal operation of their own electronic and electrical equipment. Therefore, electronic environmental interference will adversely affect the performance of electronic products, and even lead to the loss of their functions.

The main source of radio interference in a car is the ignition system of the engine. 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 fluctuates and rectifies. Starters, generators, flashers, contact-type electromagnetic vibration electric horns, wiper blades, instrumentation systems, etc., will also produce smaller electromagnetic waves that conduct and interfere with radiation.

Interfering electromagnetic waves generated by automotive appliances have pulse characteristics and wide frequency bands, and their frequencies are generally between 0.15 and 1 000 MHz. The interference electromagnetic waves generated by automotive electrical appliances are divided into two types: conducted interference and radiated interference. Electromagnetic waves that conduct electromagnetic interference are directly input into the radio equipment and electronic equipment through the vehicle wires. The radiation interference electromagnetic waves propagate in the space and are input into the radio equipment through an antenna (such as an ignition system high-voltage line is equivalent to an antenna).

External electromagnetic interference caused by natural phenomena, social environment, etc. affects the automotive electronic system more seriously. External electromagnetic interference refers to man-made electrical equipment, such as: high-voltage transmission lines, tram tracks near, radio and television Electromagnetic radiation emitted by equipment and radio communication equipment that interferes with the vehicle, and electromagnetic interference caused by lightning and other natural phenomena.

Research status of foreign automotive electromagnetic compatibility At present, the developed countries in the world have made some achievements in the study of automotive electromagnetic compatibility and formed a set of automotive electromagnetic compatibility systems. This is mainly manifested in: a relatively complete automotive electromagnetic compatibility testing standards and specifications; an effective organization for electromagnetic compatibility testing, management, and certification of complete vehicles and parts; and a highly accurate automotive electromagnetic compatibility testing system; The large-scale automotive electromagnetic compatibility prediction, analysis and design software. Third-party testing and certification agencies and automotive research institutes also carried out research on automotive electromagnetic compatibility and established their own electromagnetic compatibility labs.

1. More complete automotive EMC standard specification. International Organization for Standardization (ISO), International Electrotechnical Commission (IEC), Special Committee on International Radio Interference (CISPR), American Automobile Industry Association (SAE), German Standard (DIN), German Electrical Engineers Association (VDE) and other organizations The type and severity of interferences for anti-jamming detection are specified, and almost all manufacturers of automobiles and automotive electronics manufacturers accept these standards or add them to their own corporate standards.

2. Many large EMC laboratories. Since 1965, Volkswagen has started to set up an open-air anti-radio interference test-bed for automobiles, which has been continuously improved and improved in the 1970s. In 1978, it introduced more advanced test equipment. In 1985, it vigorously promoted the establishment of the automobile electromagnetic compatibility center system. In 1987, the new automotive electromagnetic compatibility center was completed. The French PSA Electromagnetic Compatibility Laboratory has three darkrooms: one for the vehicle, one for the adjustment of components and vehicle receivers, and one for component testing. The darkroom size of the test vehicle is 15.5 mX 10 mX 6 113, the turntable diameter is 8.4113, and the wheelbase adjustment range is 2 000 to 3 700 mm. There are hundreds of EMC laboratories in Europe, and other organizations that have large-scale automotive EMC laboratories include German BMW Motors, Audi Motors, French u-TAC, British Automobile Industry Research Association (MIRA), and Italian Fiat.

3. Car EMC prediction research. Research on electromagnetic compatibility of automobiles was basically limited to experiments. However, with the advent of electric vehicles and hybrid-driven vehicles, as well as the rapid increase of automotive electrical systems and the continuous increase in the frequency of signals, the problem of electromagnetic compatibility of automobiles is becoming more and more important for auto manufacturers. One burden. In order to improve the efficiency of solving problems and reduce costs, the application of digital modeling and digital simulation technology to automotive electromagnetic compatibility research is becoming a hot topic in automotive electromagnetic compatibility research.

Research on the domestic automobile electromagnetic compatibility research The research work on the automobile electromagnetic compatibility technology in China began with the research of the electromagnetic interference characteristic measurement of the car. At the beginning of the 1980s in the 20th century, it began to measure the electromagnetic interference characteristics of automobiles. In 1994, the China Automotive Technology and Research Center took the lead in carrying out measurements on the characteristics of automotive radio interference and conducted a general survey of various types of automobiles (new cars) throughout the country. According to statistics on census results, the passing rate is only 24%, and a considerable portion of unqualified vehicles are seriously excessive. From the 1990s of the 20th century, China began to control radio interference in automobiles. Domestic auto testing agencies and manufacturing companies have purchased electromagnetic interference receiver systems to study and test the radio interference level of automobiles and control them. The national automobile inspection agencies, including the Tianjin Automobile Inspection Center and the Chongqing National Bus Quality Supervision and Inspection Center, all have electromagnetic interference detection capabilities. Since then, domestic research on electromagnetic compatibility technologies for automobiles and their components has begun, and large-scale electromagnetic compatibility experimental facilities have begun to be researched and constructed. In March 2001, the EMC Laboratory of China Automotive Technology and Research Center passed the accreditation of the China Laboratory Accreditation Committee, marking a new development in China's automotive electromagnetic compatibility test technology. The EMC testing facilities of the China Automotive Technology and Research Center include field open field, anechoic chamber, conductive shielding room, amplifier room and measurement control system. The anechoic chamber is the main body of the electromagnetic compatibility laboratory. It can realize the uniformity and attenuation of the electromagnetic field in the room. It can simulate the electromagnetic distribution of the open field outdoors and complete various experiments related to the electromagnetic field. The laboratory passed the test of the United States SIS testing agency, and the performance indicators have met the technical requirements of international relevant standards.

Judging from the domestic situation, due to the backwardness of the overall level of China's automobile industry and the lack of understanding of the importance of automotive electromagnetic compatibility, there are few studies on electromagnetic compatibility. Vehicle electromagnetic compatibility regulations are not sound and implementation is not strict enough. In 1992, China promulgated a mandatory national standard GB14O23-92 "Test Methods and Permissible Values ​​of Radio Interference Characteristics of Vehicles, Motor Boats, and Spark-Ignition Engine Drive Devices", which limits the electromagnetic interference of cars to the environment. In 1998, GB 17619-98 "Limits and Measurement Methods for Electromagnetic Radiation Characteristics of Electrical and Electronic Components of Motor Vehicles" was promulgated. In 2001, GB/T 18387-2001 "Limits and Measurement Methods for Electromagnetic Field Radiative Intensity of Electric Vehicles, Broadband 9 kHz to 30 MHz" was issued.

Future development trends With the increase in the degree of automotive electronics, automotive electromagnetic compatibility technology is being established as an important branch of automotive technology. People are paying more attention to and attaching importance to the electromagnetic compatibility of automobiles. The standardization process of China's automotive electromagnetic compatibility technology will be accelerated, new national standards will be continuously formulated, and old standards will be constantly revised. The national standards to be developed in the next two years are: GB “Limits and Measurement Methods for Electrical Disturbance Caused by Conduction and Coupling of Road Vehicles”; GB “Limits and Measurement Methods for Electromagnetic Disturbance Caused by Electrostatic Discharge on Road Vehicles”; For a period of time, it will focus on the research and testing of electromagnetic compatibility of auto parts in order to promote the accelerating development of domestic automotive electronics and electrical parts technology, increase the production level of domestic automotive electronics and electrical components, and accelerate the domestic production of auto production in China. Based on the phased results of the electromagnetic compatibility technology of electronic components, we will strengthen the research and testing of the electromagnetic immunity of automotive vehicles, catch up with the development level of international automotive technology, and improve the overall level of domestic automobiles.