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EMC's six-step approach to rectification

Electromagnetic compatibility (EMC) refers to the unbearable interference signal capability caused by any equipment in the wrong environment when the equipment or system operates according to regulations in the electromagnetic environment. Therefore, EMC includes two requirements: on the one hand, the interference signal of equipment to the environment during normal operation shall not exceed a certain limit; On the other hand, the equipment has certain immunity to interference signals in the environment, that is, electromagnetic sensitivity.

The interference between various operating electronic products is mainly related and interacted with each other through electromagnetic transmission, electromagnetic induction and electromagnetic radiation. Under certain conditions, it will affect, affect and injure the operating machine and personnel. In fact, there are many rectification articles about EMC.

The six steps of EMC rectification are as follows: the first step is to search and determine the radiation source, the second step is to filter, the third step is to absorb waves, the fourth step is to ground, the fifth step is to shield, and the sixth step is to disperse kinetic energy. The actual concept is shown in the figure:


Step 1: The methods for searching and determining the radiation source include elimination method, frequency point search method of spectrum analyzer and element resonance frequency analysis method. Exclusion methods include wire pulling method, zoning work exclusion method, low voltage and low current human touch method and area shielding exclusion method. Component resonance frequency analysis method refers to the fixed frequency and frequency doubling analysis classification method of crystal vibration, DDR and other components.

Step 2: Filtering is generally divided into capacitance filtering, RC filtering and LC filtering;

Step 3: The methods of absorbing electromagnetic wave include circuit series magnetic bead method, bypass magnetic ring method and paste absorbing material method. When applying the method of absorbing electromagnetic wave, it should be noted that the frequency of over-radiated electromagnetic wave must be within the range of electromagnetic wave absorbed by the absorbing material used, otherwise the absorption method will be invalid.

Step 4: The grounding method is generally divided into single-point grounding method and multi-point grounding method.

Step 5: Shielding method generally adopts shielding method, enclosure shielding method and PCB wiring layout shielding method.

Step 6: Kinetic energy dispersion method means that some monitoring software of the object to be measured can use frequency spread, frequency hopping and other technologies to carry out broadband bandwidth and frequency hopping on the frequency band with dense kinetic energy, and complete the kinetic energy of the scattered frequency band, so as to reduce the kinetic energy in the additional spotting frequency, that is, reduce the electromagnetic wave intensity radiated by the spotting frequency. Therefore, this method has obvious effect on the excessive number of peak edge wave radiation, but has no significant effect on the excessive frequency radiation of envelope wave.

This six-step EMC rectification method is more applicable to the rectification of ordinary electronic equipment. However, in fact, Tianlijun believes that although these six methods can help improve the efficiency of EMC radiation rectification, save the cycle, and quickly detect according to EMC, they are not the global solution to EMC problems. EMC problems are the most ideal or design considerations, rather than using some "catch up" solutions.

EMC (Electromagnetic Compatibility) is the electromagnetic compatibility technology we often refer to. It includes the requirements of EMI and EMS. In the common electromagnetic environment of electrical equipment or systems, it is neither affected by the electromagnetic environment nor by the environment.

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