How Can the Radiation of Automotive Electronic Equipment Be Prevented

With the development of automotive electronic control technology, the electromagnetic compatibility (EMC) of automotive electronic equipment has attracted more and more attention. In the random inspection over the years, many enterprises have been "sacked" due to unqualified product radiation harassment. The reason is that the product EMC can not meet the requirements. "With the increasing working frequency of on-board electronic equipment, it brings higher radiation." Cheng Weitao, deputy chief engineer of Huizhou Huayang General Electronics Co., Ltd., said that modern vehicles mostly use high-speed digital circuits and have more response in the whole spectrum, so the radiation is also more serious.

2007-2008 was the golden period for the development of China's automobile GPS navigation. At that time, the industry threshold was low, and the attractive economic profits attracted a large number of enterprises to rush for gold. With the increasingly fierce competition in the industry, the fierce "price war" makes some enterprises do everything to reduce costs, and the products in the market are gradually mixed. At present, China has not formulated mandatory standards for electromagnetic radiation in vehicles. AQSIQ tests navigation products according to the requirements of current standards such as GB9254-2008 and GB / T 19392-2003. These standards are national recommended standards. Therefore, even if the product is unqualified, the enterprise does not need to bear responsibility, which makes many manufacturers take risks.

According to the interview, all front mounted navigation products must pass the test of the whole vehicle factory, and go through a road test of at least 20000 kilometers to find potential problems and risks, and then the whole vehicle factory will convene the parts suppliers for rectification to improve the electromagnetic tolerance of EMC and electronic appliances, so as to meet the requirements of vehicle safety and reliability. Different vehicle manufacturers have formed their own stricter standards based on the national standards, so there will be no problems with front mounted products. Due to the lax market supervision, enterprises have relaxed the product design cost, design concept and design skills, resulting in uneven product quality in the market. "Considering the cost problem, there are serious defects in the circuit board design of some enterprise products, lack of filter elements, and EMC can't pass the test," Cheng Weitao said. In addition, Wan Xinyu, vice president of Shenzhen SEG Navigation Technology Co., Ltd. (hereinafter referred to as "SEG navigation"), believes that in order to reduce costs, some enterprises use other materials to replace the metal shielding materials of navigation products, such as plastic.

"Radiation disturbance" harasses other electronic appliances

"Radiation disturbance" exceeding the standard refers to that the intensity of electromagnetic wave emitted by electronic products exceeds the legal limit. This may reduce the performance of surrounding equipment or systems, interfere with the normal operation of other electronic products, and may also cause certain harm to human body.

It has little impact on the human body, which is the unanimous view of many industry insiders interviewed. "At present, there is no quantitative standard for whether radiation will cause harm to human body, and there is no medical evidence to show that this electromagnetic induction is necessarily related to some diseases. The impact of radiation generated by navigation on human body is not certain." Hong Jun, technical director of SEG navigation, believes that the radiation brought to human body by consumers by motor cars, high-speed railways or aircraft far exceeds the indicators of vehicle manufacturers. "The excessive navigation radiation will cause little harm to human body, but it will cause some interference to other automotive electronic equipment," said a technical engineer of NXP semiconductor (Shanghai) Co., Ltd. Modern cars have a variety of electronic products. The working frequency and power increase gradually. The car is full of a large number of electromagnetic waves in operation. It can be imagined that the electromagnetic interference caused by excessive radiation of navigation products is serious. "The configuration of modern cars is getting higher and higher, and the degree of electronization is also getting higher and higher. The number of CPUs in a high-end configuration car exceeds 1000." the engineer said that electronic products are vulnerable to interference and are also a source of interference. In the future, automotive electronic and electrical components will continue to increase. Too high electromagnetic interference in the car may lead to mutual interference between electronic and electrical appliances. As a key component of the electronic control system, the sensor may reduce its sensitivity and precision, produce sensor signal distortion, and lead to the failure of electronics and appliances.

Cheng Weitao, technical manager of Huizhou Huayang General Electronics Co., Ltd., believes that if the vehicle navigation radiation exceeds the standard, it will affect or interfere with other vehicle electronics. Therefore, the EMC design of navigation products should meet the standard requirements to prevent other electronic equipment from electromagnetic interference, which may affect the normal operation of electronic equipment or damage the corresponding electrical components. "This electromagnetic influence will bring local misoperation in the vehicle working environment and cause system instability. This misoperation may also threaten the safety of driving," Wan Xinyu said.

Design rectification and adding shielding measures are good ways

The electromagnetic radiation disturbance caused by navigation and automotive electronics is very important, so it is very urgent to reduce the electromagnetic interference of equipment. In the interview, the reporter learned that the key to solving this problem lies in the rectification of the system circuit and the shielding of the interference source.

How to change the circuit rectification? "The effect of improving the circuit can be achieved by designing the return path of high-frequency signal as short as possible, the return area as small as possible, and improving the design of PCB." Cheng Weitao said that in addition to improving the circuit design, improving the EMC of products also needs to be carried out from many aspects, such as software design, circuit board design, shielding structure, signal line, circuit grounding mode design, etc.

Huang Li, the advanced R & D Manager of Desai Xiwei, believes that the circuit design layout, manufacturing process, shielding measures and mechanical and electronic interface processing methods can affect the circuit design.

In addition to circuit design, there are strict requirements for the selection of raw materials. PI Yubao, deputy general manager of Beijing Hainachuan Hangsheng Automotive Electronics Co., Ltd., believes that the safety and reliability of the whole vehicle must be considered in the structural design of automotive electronic and electrical equipment. The selection of electronic components must be "carefully selected". Different electronic components have different industrial standards. Select electronic components that meet automobile specifications and have been verified. Hong Jun believes that high-quality components need to be selected in the whole process from circuit design to manufacturing to ensure the shielding on the circuit. "A good horse with a good saddle", Huang Li, the advanced R & D Manager of Desai Xiwei, also agreed with this view. Huang Li said that the selection of electronic components and raw materials must meet certain requirements, otherwise the comprehensive design of the system is futile. Secondly, the EMC design capability of manufacturers must be assessed, because no matter how good devices and equipment can be stacked into qualified products.

Secondly, the radiation can be reduced by shielding the interference source. Cheng Weitao told reporters that by adding a shield, wrap the interference source and change the circuit grounding mode, so that the magnetic ground wire will not radiate outward. Suppress interference sources. Protect devices susceptible to interference. Huang Li believes that by adding filtering measures, when the interference source comes in, the interference source can be filtered out through the filter element.

In addition, Hong Jun believes that to reduce radiation, the first is to improve radiation emission through design, reduce interference or isolate interference sources; Second, it is also important to strengthen the electromagnetic tolerance of electronic appliances.

Source: viku electronic market network

How Can the Radiation of Automotive Electronic Equipment Be Prevented 1

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