How to solve electromagnetic interference in power systems
The power supply must meet the corresponding minimum emission energy requirements in its application environment, otherwise it will cause interference to the surrounding equipment. The standard IEC/EN61000-6 is divided into industrial environment equipment requirements and emission requirements for residential, commercial, and light industrial environments according to the general type requirements; For general products such as power supplies, unless it is a special model, electromagnetic interference positioning will be designed according to IEC/EN61000-6-3 or IEC/EN61000-6-4 in the initial stage of design.
With the continuous miniaturization of power supplies and the increasing power density, the difficulty of designing electromagnetic interference for the power supply itself continues to increase. MORNSUN currently has all AC-DCs on the market that not only have built-in filters, but also invest a lot of design costs in transformer shielding and power device noise absorption to meet the promised performance requirements; All R2 generation low-power DC-DC products are designed with a six sided shielding structure, meeting the Class A requirements of industry EN55022/CISPR 22 and EN55011/CISPR 11, and complying with the level requirements of basic industries.
Although the power supply has invested a significant amount of design cost in electromagnetic interference and meets the promised requirements, it is still inevitable that there will be issues of electromagnetic interference exceeding the standard in market applications; At this point, many design engineers believe that the root of the problem lies in the power supply. However, this understanding is actually flawed because the electromagnetic interference conducted interference testing project is mainly aimed at the power port, which becomes its transmission path. All electromagnetic interference will reach the tested equipment through the power port. However, the electromagnetic interference tested by the testing equipment not only comes from the power supply itself, but also mainly includes electromagnetic interference generated by other parts of the machine, as well as electromagnetic interference generated by resonance of parasitic parameters inside the equipment. This type of electromagnetic interference will be coupled to the testing equipment through the power port, and the internal filter of the power supply cannot filter this part of the electromagnetic interference. The application environment of the power supply varies greatly, All power supply design filters prioritize addressing their own interference, while reserving maximum margin for filter attenuation and spectral characteristics. However, it is not possible to be compatible with all application scenarios; So this requires our whole machine designers to design the power front-end according to the application circuit recommended by the power supply manufacturer.
