What is the EMC filter rectification six-step method?
Electromagnetic Compatility (EMC) refers to the ability of a device or system to operate in its electromagnetic environment and not tolerate electromagnetic interference in any device in its environment.
Therefore, EMC includes two requirements: on the one hand, the electromagnetic interference generated by the equipment in the normal operation process cannot exceed a certain limit; on the other hand, it means that the appliance has certain electromagnetic interference in the environment.
The degree of immunity, ie electromagnetic sensitivity.
Interference between various operating electronic devices is mainly related to each other and affects each other in three ways: electromagnetic conduction, electromagnetic induction and electromagnetic radiation.
Under certain conditions, it will cause interference, influence and harm to the running equipment and personnel. There are actually a lot of rectification articles about specific EMC fields.
The EMC rectification six-step method is as follows: the first step to find the confirmation radiation source, the second step filter, the third step absorbing wave, the fourth step grounding, the fifth step shielding, and the sixth step energy dispersion method.
The specific ideas are as follows:
The first step: find the method to confirm the radiation source, including the exclusion method, the spectrum analyzer frequency search method, and the component natural frequency analysis method.
The exclusion method includes a wire drawing method, a partitioning work elimination method, a human body touch method with low voltage and small current, and a region shielding method.
The component natural frequency analysis method refers to the fixed frequency of some components and its multiplication frequency analysis classification method. The operating frequencies of components such as crystal oscillator and DDR are fixed.
The second step: filtering is generally divided into capacitive filtering, RC filtering and LC filtering;
The third step: the method of absorbing electromagnetic waves is a circuit series magnetic bead method, a winding magnetic ring method and a absorbing material method. Special attention should be paid when using the method of absorbing electromagnetic waves: the frequency of the electromagnetic wave exceeding the standard must be within the frequency range of the electromagnetic wave absorbed by the absorbing material used, otherwise the absorbing method will be invalid.
The fourth step: the grounding method is generally divided into a single point grounding method and a multi-point grounding method.
The fifth step: The shielding method generally has a shield shielding method, a housing shielding method, and a PCB trace layout shielding method.
The sixth step: the energy dispersion method means that some control software of the measured object can use the techniques of spread spectrum and frequency hopping to spread the frequency bandwidth and the hopping frequency to realize the dispersed frequency band energy, thereby adding to the single point frequency.
The energy on the lower side, that is, the effect of reducing the intensity of the electromagnetic wave radiated at a single point frequency.
Therefore, this method will have a significant effect on the frequency radiation of the peak burr-shaped waveform, and it will not have a significant effect on the envelope waveform frequency radiation exceeding the standard.
This EMC rectification six-step method is more suitable for the rectification of common electronic equipment.
However, the above six methods, in fact, they help to improve the efficiency of EMC radiation rectification, save cycle, and quickly pass EMC testing, but it is not a solution to the fundamental problem of EMC. EMC's problem is ideally at the design end consider.
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