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This article shows you what the concept of EMC electromagnetic compatibility design is, the content is concise and easy to understand, it can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

The concept of EMC

EMC (Electro Magnetic Compatibility)-electromagnetic compatibility (EMC) refers to the ability of electronic, electrical equipment or systems to work normally according to design requirements in the expected electromagnetic environment. As far as the world is concerned, the problem of electromagnetic compatibility has formed a new discipline, and it is also a marginal science based on the theory of electromagnetic field, including information, electrical engineering, electronics, communications, materials, structure and so on. at the same time, it is also a practical discipline, which requires product engineers to have rich practical knowledge.

The central topic of electromagnetic compatibility is to study how to control and eliminate electromagnetic interference, so that when electronic equipment or system works with other devices, it will not lead to the deterioration or degradation of the working performance of any part of the equipment or system.

An ideally designed electronic device or system should not emit any unwanted energy, nor should it be affected by any unwanted energy. Of course, before the electronic equipment or system leaves the factory, the main basis to measure its EMC performance is the EMC test results. These tests measure some harassment and interference of a product simulation product in the actual working environment.

General electronic product design does not consider the EMC problem, it will lead to EMC test failure, so that can not pass the certification of relevant laws and regulations, and can not be sold at the factory. Even if this product is applied to the actual working environment, there will be some practical problems. Therefore, in practical application, it is necessary to constantly develop practical methods to eliminate electromagnetic interference and disturbance. For example, according to the demand, engineers have designed a filter circuit with good effect, which is placed in front of the product Imax O interface, so that most of the interference noise entering the system due to conduction can be eliminated at the population of the circuit system. An isolation circuit (such as transformer isolation and photoelectric isolation, etc.) is designed to solve the conducted interference through the power line, signal wire and ground wire, and to prevent the interference caused by common impedance and long-line transmission; an energy absorption circuit is designed to reduce the noise energy absorbed by circuits and devices, or through the selection of components and reasonable arrangement of circuit systems to reduce the impact of interference.

At present, the performance of the EMC of a product is mainly measured from the following two aspects.

(1) EMI (Electro Magnetic Interference)-electromagnetic interference performance. That is, when the equipment or system in a certain environment is running normally, it should not produce electromagnetic energy interference that exceeds the requirements of the corresponding standards. Such electromagnetic interference is as follows:

Electromagnetic disturbance transmitted from the power cord

Harassment transmitted from signal lines and control lines

Disturbance radiated from the product shell (including all cables in the product)

Harmonic current from the power port (Harmonic)

Voltage fluctuation and flicker (Fluctuation and Flicker) generated by the power port.

(2) EMS Electro Magnetic Susceptibility)-electromagnetic disturbance rejection performance. That is, when the equipment or system in a certain environment is running normally, the equipment or system can withstand various types of electromagnetic energy interference. This kind of electromagnetic energy interference mainly includes:

Electrostatic discharge (ESD)

Electrical fast transient pulse group of power port

Electrical fast transient pulse group of signal line and control line port

Surge and Lightning strike of Power Port

Surge and lightning strike at the port of signal line and control line

Electromagnetic radiation transmitted from space to product shell

Conducted interference coming from the power port

Voltage drop and interruption of the power port.

EMC design is in the process of product design, the use of certain design skills and additional technical means to improve the EMC performance of the product (including the anti-interference ability and anti-disturbance level of the product), and can run normally according to the design expectation of the product in a certain environment. In order to measure the EMC performance of the product before reaching the actual application environment, EMC testing is needed. Corresponding to the EMC indicators of the above products, EMC testing usually has the following two aspects.

(1) EMI electromagnetic interference test

Power cord conducted disturbance (CE) test

Signal and control line conducted disturbance (CE) test

Radiation disturbance (RE) test

Harmonic current (Harmonic) test

Voltage fluctuation and flicker (Fluctuation and Flicker) test.

(2) electromagnetic immunity test of EMS

Immunity test of electrostatic discharge (ESD)

Immunity Test of Electrical Fast transient burst (EFT/B) in Power Port

Immunity Test of Electrical Fast transient burst (EFT/B) for signal Line and Control Line

Surge (SURGE) and Lightning Test of Power Port

Surge (SURGE) and lightning strike test of signal line and control line

Shell radiation immunity (RS) test

Conducted immunity (CS) Test of Power Port

Conducted immunity (CS) Test of signal Line and Control Line

Voltage drop and interruption test (DIP) on the power port.

EMC design concept

In the design of electronic products, in order to obtain good EMC performance and cost ratio, it is important to design EMC products.

The EMC performance of electronic products is given by design. Testing is only to characterize the inherent EMC performance of electronic products by some quantitative method. For enterprises to standardize EMC design, it can be implemented in the following three steps.

Step 1: EMC design should be considered in the early stage of research and development.

If the EMC problem is not considered in the early stage of the product design, it is hoped to be solved in the testing stage (manifested as solving the EMC problem of the designed product through rectification, so a large amount of manpower and material resources are invested in the later test / verification, rectification stage). Then, even if the product rectification is successful, in most cases, the rectification will involve changes in circuit principle, PCB design, structure and mold, resulting in a great increase in R & D costs and a great extension of the cycle.

Only by considering and predicting the EMC problem in the early product design process, turning EMC into a controllable design technology, parallel and synchronized with the product function design process, can the product be designed well at one time.

Step 2: improving the EMC performance of electronic products through design is definitely not given by EMC experts in the enterprise, because EMC can never exist without product hardware, structure and other physical objects.

Therefore, in order to make the designed electronic products achieve good EMC performance at one time, it is necessary to improve the EMC experience and awareness of product design engineers. For example, hardware engineers should not only master the knowledge of circuit design, but also master the basic knowledge of EMI and EMS anti-interference design; PCB design engineers need to master the corresponding device layout, cascading design, high-speed wiring EMC design knowledge; structural engineers also need to understand the shielding of product structure and other aspects of design knowledge.

Because these engineers who participate in product design together, if they want to realize the opinions put forward by EMC experts in the product design process, they should understand and understand the mysteries of the suggestions put forward by EMC experts, and combine them with the design characteristics of their respective fields, so as to eliminate the sprout of all EMC problems in the product design stage. Only when all the developers involved in product design work together to improve the quality of EMC, can we design electronic products with high performance EMC.

Step 3: the enterprise should establish a set of standard EMC design system and design analysis method.

The enterprise should establish a set of standard EMC design system and design analysis method, that is, integrate the process of EMC design analysis and risk assessment into the R & D process, evaluate and control EMC in all stages of product design, consider the possible EMC problems in the early stage of research and development, and predict the risk of EMC test failure.

Fully consider the possible EMC problems and find a solution to ensure that the product can pass the testing and certification at one time after the end of the design. Of course, for enterprises, it will also reduce unnecessary manpower and R & D costs, and shorten the product listing cycle.

The above content is what is the concept of EMC electromagnetic compatibility design. Have you learned the knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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