Technical column



Development trend of EMC test system for automotive OEM electronic parts


       As consumers pay more and more attention to the safety of automotive electronic systems, the electromagnetic compatibility technology of automotive electronic components plays an increasingly important role in the field of automotive safety testing. It is not only reflected in the automotive electromagnetic Compatible standards, major international automobile companies are also constantly establishing and updating existing EMC testing standards to deal with harsher electromagnetic environments, and most of the standard requirements are much harsher than current international standards.

This article will introduce        the main, especially the OEM EMC standards that are at the forefront of development.

EMC Standards for         OEM Automotive Electronic Components

The EMC standards        of major car manufacturers are almost all based on the current international standards (such as CISPR, ISO, IEC ), and on this basis, they are sorted out and repaired according to their own characteristics, and finally form a unique EMC standard system. American standard: Taking Ford standard ( Ford-EMC-2009.01 ) as an example, its test method in the conduction immunity test is unique, adding a variety of pulse waveforms on the basis of ISO 7637 , effectively simulating the real vehicle environment various adverse situations. For example, a variety of random pulse signal tests ( CI220 ) can be carried out by using the pulse waveform generator specified by the Ford standard; according to the different products to be tested, select the pulse interference signal ( CI230 ) that the real vehicle may receive when it is cold or hot. In addition, There are also a variety of micro-interruption tests ( CI260 ), pulse signal coupling tests ( RI130 , RI150 ) that are closer to the application environment , etc. It is precisely because of its excellent performance that many well-known car manufacturers in the world have partially adopted its standards, such as Mazda ( MES 67602A:2011 ), a certain model division of Volvo , and the EMC standard of Jaguar ( JLR-EMC-CS_v1.0_V3 ), etc. . GM's standards are more streamlined and more cautious in adopting international standards. If conducted emissions are only measured in the AM band (0.52~1.71 MHz ); the antenna required for low-frequency magnetic field radiation emission is relatively special; the radar wave frequency band of radiation immunity has always adhered to high-level ( 600 V/m ) tests, etc.

        German standards (Volkswagen, Mercedes-Benz, etc.) are favored by many car manufacturers because of their standard limits, moderate grades and diverse choices. For example, FAW ( JA3700 ), Geely Emgrand, etc. have adopted some of the content. In terms of test items, the coupling emission test ( CV test ) uses the coupling clip of ISO 7637 to measure the coupling interference on the sample wire harness. The ESD power-on mode test is done using the fixture in the ISO 10605 annex. Legal standards (such as Peugeot, Renault , and also Nissan 28401NDS02 ) are also self-contained. The test standard includes a large number of electrical performance tests ( Electrical test ), and the EMC test items are relatively comprehensive. Taking Peugeot ( PSA B21 7110-C ) as an example, its test items have reached as many as 30 , and the requirements and limits of the standard are slightly higher than other standards. For example, the test requirement for large current injection ( BCI ) is 300 mA ( Closed-loop method), radiation immunity ( RI ) test requirements level up to 200 V/m and so on. In addition, there are EMC of Chrysler, Toyota, BMW and other OEMsThe standard system is also very mature. Domestic automakers, such as Shanghai Automobile, Changan Automobile, Southeast Automobile, etc., have also established relatively complete EMC standard systems and development plans.

Development Trend of EMC Standards          for Automotive Electronic Components

         Since the 21st century, due to the strong support of governments of various countries, new energy vehicle technology has developed rapidly, and plug-in / hybrid / pure electric vehicles have been launched one after another. The related new energy vehicle EMC technical standards have become the key research objects today. The relevant test methods have been added to the new version of CISPR 25 . A number of well-known OEMs have also introduced more mature testing methods, such as BMW and Peugeot. Among the domestic automakers, BYD and GAC have also done fruitful research in this field, and are preparing to write corporate standards for EMC testing of new energy vehicles. Among the third-party laboratories, such as Intertek Automobile Laboratory, conducted a lot of research and development on the test standards released by BMW, Peugeot, Volkswagen and SAIC, and completed a number of EMC performance test projects on battery packs on this basis. Different from the low-voltage system of traditional cars, the battery pack contains a large number of high-voltage drive modules (for example: high-voltage three-phase motor, motor controller battery management module BMU, etc.), due to the high voltage and large energy of these modules, so It is very easy to be coupled to the low-voltage system part of the battery, resulting in a serious test exceeding the standard. Therefore, in addition to the necessary high-voltage module test, a very important high-low voltage coupling experiment has been added.

Cars        with 2G/3G/4G/Wi-Fi and Bluetooth functional modules are also one of the hot spots for the development of EMC testing standards in the future. Volkswagen has made it clear that it will add tests in relevant frequency bands to future test standards. Volvo Cars' new version of the standard ( REQ-043878_V2 ) has also added requirements for radiated emissions and radiated immunity in relevant frequency bands. For the test laboratory, how to realize the effective connection between the handheld device and the tested sample in the darkroom is an urgent problem to be solved.

       In addition, the existing EMC standards for automotive electronic components are not monolithic and impeccable. With the continuous development of the automotive EMC industry, problems in the current standards will also be exposed. Since the near-field frequency band ( 0.1~48 MHz ) is more sensitive and has many factors affecting the test results, the regulations on radiated emissions in this frequency band will be more detailed; in order to increase the test repeatability, the radiated immunity test There will be certain requirements for the field uniformity of the anechoic chamber or a more detailed explanation for the calibration of the field strength; the unified large current injection test verification method can significantly improve the comparability of various laboratories; the reverberation chamber and The GTEM cell method has been highly recommended by many OEMs , especially Japanese and American OEMs , because of its more uniform field strength ; due to the wide application of 2G/3G/4G/Wi-Fi in automobiles, various OEM standards The chapter on handheld antennas will also become more and more detailed.

         OEM's control and prospect of EMC quality system for automotive electronic components

         The quality system is the key and guarantee for the survival and development of an enterprise. For the automotive industry that involves personal safety, quality system control is particularly important for automotive OEMs . Because of the early start, the EMC quality system of major car manufacturers in Europe and the United States is relatively complete, and there is an independent department responsible for EMC testing of complete vehicles or parts. The main domestic joint venture OEMs , such as Pan Asia, Nanjing Ford R&D Center, Shanghai Volkswagen, etc., have also established mature EMC quality management systems by learning from foreign advanced experience. During the continuous communication and learning with major OEMs , Intertek summarized the common system flow in the EMC test control of auto parts, as shown in Figure 1 . Establishing an effective management and control system can make the EMC test of the entire model project traceable; make the EMC experiment process more rigorous and smooth. Only by establishing a mature EMC control system, can OEMs , component suppliers, and third-party laboratories perform their duties and responsibilities, and avoid delaying the project time of OEMs and component suppliers due to process reasons.



Figure 1 Flow chart of EMC test management for automotive electronic components


        The responsibility of the third-party laboratory in the EMC quality control system is not only to provide testing services, but also to become a bridge and cornerstone for communication between OEMs and suppliers. The OEM is the final customer of the third-party laboratory, while the component supplier and the third-party laboratory have a direct contractual relationship. The third-party laboratory has the responsibility and obligation to let the OEM understand any situation that occurs in the formal test, so as to provide the OEM with first-hand real and effective test data.

        Due to the late start of the domestic auto industry, there is still a long way to go for the research of automotive EMC technology and the control of the quality system. In recent years, domestic OEMs have gradually established a department to control the EMC quality system through continuous introduction, digestion, and absorption, and on this basis, a complete component and vehicle testing standard system and a standardized testing process have been established. Including the approval process of the test plan, the testing and control process of components, the submission process of the report, etc. After unremitting efforts and trials, a group of domestic OEMs such as Shanghai Automobile, Chongqing Changan, BYD, Southeast Automobile, Geely Automobile, and Beiqi Foton have established their own unique EMC quality management systems. Other domestic OEMs are also starting to establish their own EMC quality management systems one after another, and have achieved certain results.

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