Learn electromagnetic compatibility from experts - standards, design, and fault analysis

Central topics:

• Interpretation of the differences between the new and old basic immunity standards
• Engineering design of EMC for electronic and electrical products
• Fault location analysis of electromagnetic disturbance problems
• Electromagnetic compatibility and EMI suppression device technology

Whether the electromagnetic compatibility index of electronic products is qualified is directly related to whether the products can be put on the market. With the continuous improvement of chip speed and integration, the widespread adoption of high-density electronic assembly technology, and the development of electronic products that are "light, thin, short, small" and highly functional, engineers are facing huge challenges in electromagnetic compatibility design.

This special issue invites senior experts in the EMC/EMI field. From the differentiated interpretation of the old and new national electromagnetic compatibility standards that need to be understood in the early stage, the engineering design of electronic product EMC, the improvement of electromagnetic compatibility performance of key electronic components, to the fault point location analysis of electromagnetic interference problems faced by later product certification, the system helps engineers quickly complete the process from electromagnetic compatibility standard understanding, design, fault analysis and rectification to the final test to obtain EMC test certification certificate.

The electromagnetic compatibility experts who participated in the EMC/EMI teaching of the Electronic Components Technology Network include:

• Qian Zhenyu, a famous domestic EMC expert and professor
• Ma Yongjian, Senior Member of China Institute of Electronics and Chief EMC Expert
• Zhu Wenli, Director of CESI Electromagnetic Compatibility Laboratory, Institute of Electronics, Ministry of Industry and Information Technology
• He Junping, Associate Professor, Harbin Institute of Technology Shenzhen Graduate School

Qian Zhenyu, Zhu Wenli, and He Junping

Qian Zhenyu: Interpretation of the differences between the new and old basic anti-interference standards

At present, the old and new versions of the national electromagnetic compatibility anti-interference standards coexist. Many companies are not clear about the differences between the old and new versions and how to understand these differences. Once the new product standards are promulgated, they will be caught off guard and even cause immeasurable losses. Enterprises need to understand the contents of these new and old standards. Professor Qian Zhenyu, a member of the National Electromagnetic Compatibility Standardization Technical Committee, interprets the differences between the new and old basic anti-interference standards from the following aspects, and provides solutions to problems that may be encountered in the implementation of the standards:

• Electrostatic discharge immunity test: including test methods for ungrounded equipment, direct discharge to the test product and discharge test to the horizontal coupling plate.
• Radio frequency radiated electromagnetic field immunity test: including the severity level of the test and the calibration of the test site.
• Pulse group immunity test: including characteristic parameters of pulse group generator, coupling/decoupling network, configuration of laboratory type test, and test methods.
• Surge immunity test: including the requirements for voltage and current waveforms at the EUT port of the power line coupling/decoupling network, the coupling/decoupling network used in the interconnection line test, the coupling/decoupling network for high-speed communication lines, and the requirements for the metal ground reference plate added in the new version of the standard. It also proposes solutions to the problems of tripping in the laboratory after installing the surge test equipment, the floating problem of surge output and surge generator casing, the common mode test problem of shell insulation equipment, the surge test problem of DC/DC converter, and the surge voltage application problem of the tested equipment.
• Voltage dips, short interruptions and voltage variations immunity test
  

Ma Yongjian: Conduct EMC engineering design in the initial stage of product design

In order to obtain EMC test certification certificates for electronic products, many companies continue to use the test-rectify-test method to conduct EMC test experiments on products. However, this method increases the weight and cost of the product, fails to solve the problem of signal frequency and interference frequency being consistent, and may also affect the safety of the product and make the rectification ineffective. Ma Yongjian, chief EMC expert and senior member of the China Electronics Society and general manager of Shenzhen Rambo Filter Technology Co., Ltd., strongly reminds everyone: "The EMC of the product is designed, not tested! EMC issues of electronic and electrical products should not be solved in the testing stage, but should be designed as early as the initial stage of product design and development."

Ma Yongjian recommends that enterprises establish a standardized EMC design system in the product development stage, adopt a set of systematic electromagnetic compatibility design processes, evaluate, predict, analyze and design the EMC problems of products, conduct EMC comprehensive design at all stages of product design, and consider possible EMC problems in the early stage of R&D to ensure that the product samples can pass the EMC test and certification at one time, shortening the product's market cycle. In order to help enterprises compile corresponding EMC design rules and EMC design specifications in each technical link of each stage of product EMC design and guide the engineering design of product EMC, Ma Yongjian gave an example of a relatively mature EMC design system (mainly using the design rule check method). For a detailed introduction to EMC engineering design, please see: Engineering design of EMC for electronic and electrical products

Zhu Wenli: Quickly locate and analyze the fault point of electromagnetic disturbance problems

It is often difficult to avoid electromagnetic compatibility problems in products. Solving this problem requires analysis from several aspects, such as common electromagnetic interference problems, product composition and internal structure, and unqualified curves of product testing. After mastering some basic ideas, it will be easier to locate electromagnetic compatibility problems, and rectification can be completed more smoothly, thereby accelerating the progress of product design finalization or certification and listing.

Zhu Wenli, director of the Electromagnetic Compatibility Room of the CESI Quality and Safety Testing Center of the Fifth Institute of Electronics of the Ministry of Industry and Information Technology, combined with more than 20 years of practical experience in EMC, taught everyone how to calmly deal with electromagnetic disturbance problems from six aspects: analysis of the main electromagnetic disturbance sources in the product, disturbance source location, product continuous conduction emission problem fault location, product intermittent conduction emission problem fault location, product radiation disturbance problem fault location, and disturbance power problem fault location. For specific electromagnetic disturbance problem fault point location analysis methods, please refer to this well-received article: Fault Point Location Analysis of Electromagnetic Disturbance Problems [Pictures

and Text] He Junping: Focus on Electromagnetic Compatibility and EMI Suppression Device Technology

In addition to design improvements, the technology and performance improvement of key electronic components are also the key to solving electromagnetic compatibility problems. Associate Professor He Junping of the Shenzhen Graduate School of Harbin Institute of Technology said that in response to the increasingly stringent electromagnetic compatibility regulations and the pressure of shrinking electrical and electronic products, new high-performance and small-volume EMI suppression devices will gradually become a development trend: the improvement of EMC standards requires further improvement in the high-frequency performance of suppression devices; the miniaturization of EMI is mainly affected by the original noise size of the power supply, the volume of inductance and capacitance, and its volume can be effectively reduced by adopting new magnetic materials, planar integrated design, hybrid filter design, etc.

He Junping introduced the new progress of electromagnetic compatibility, put forward the common problems of EMI filters, development trends and methods to improve the performance of EMI filters; analyzed the design scheme for improving the high-frequency performance of passive EMI filters from five aspects: factors affecting the performance of filter L/C devices, the influence of L magnetic saturation/frequency, the influence of LC temperature, the influence of stray coupling of filter L/C devices, and the suppression of parasitic parameters/coupling; and introduced two EMI filter miniaturization design technologies: planar integrated design (electromagnetic integration, capacitor, inductor integration) and hybrid integrated design. For more details, please see: Electromagnetic compatibility and EMI suppression device technology