Analysis of Electromagnetic Compatibility Design for Switching Power Supply Systems
Analysis of Electromagnetic Compatibility Design for Switching Power Supply Systems
With the rapid development of electronic technology, electronic devices are also moving towards functional integration and miniaturization, which brings us many conveniences. However, the electromagnetic coupling between various electronic devices has become the main problem faced by engineers. The harm of electronic environmental pollution is no less than that of traditional environmental pollution. Electromagnetic pollution, as a part of environmental pollution, has also been put on the agenda. During normal operation, electronic devices will withstand various electromagnetic interferences, including mutual interference from their internal components and interference from other electronic devices around them. At the same time, they will generate electromagnetic interference on other electronic devices around them. The requirements for electronic devices vary greatly in different application environments (household, industrial control, and power). In this regard, reference can be made to the general standard IEC/EN61000-6 series or the industry requirements of corresponding products.
This type of electromagnetic interference mainly includes two aspects in terms of transmission channels: firstly, it is transmitted along the wiring harness, which mainly includes transmission along the power port and signal port; On the other hand, it mainly transmits along space.
Electromagnetic interference:
The power supply must meet the corresponding minimum emission energy requirements in its application environment, otherwise it will cause interference to the surrounding equipment. According to the requirements of general types, the standard IEC/EN61000-6 is divided into industrial environment equipment requirements and emission requirements for residential, commercial, and light industrial environments; For general products such as power supplies, unless it is a special model, electromagnetic interference positioning will be carried out according to IEC/EN61000-6-3 or IEC/EN61000-6-4 during the initial design stage.
With the continuous miniaturization of power supply volume and increasing power density, the difficulty of designing electromagnetic interference in the power supply itself continues to increase. Currently, MORNSUN not only has built-in filters in all AC-DCs on the market, but also has invested a large amount of design costs in transformer shielding and power device noise absorption, meeting the promised indicator requirements; The R2 generation low-power DC-DC products are all designed with a six sided shielding structure, meeting the class A requirements of EN55022/CISPR 22 and EN55011/CISPR 11 in the industry, and meeting the level requirements of basic industries.
Although significant design costs have been invested in the electromagnetic interference of the power supply itself, which also meets the promised indicators, it is still inevitable that the electromagnetic interference of the power supply exceeds the standard in market applications; At this point, many design engineers believe that the root cause of the problem lies in the power supply, which is actually a misconception. Because electromagnetic interference conducted disturbance testing projects mainly focus on the power port, the power port becomes its transmission path. All electromagnetic interference will pass through the power port to the tested equipment, but the electromagnetic interference detected by the testing equipment is not only from the power supply itself, The main part also includes electromagnetic interference generated by other parts of the entire machine, as well as electromagnetic interference generated by resonance of parasitic parameters inside the equipment. This type of electromagnetic interference is coupled to the testing equipment through the power port, and the filter inside the power supply cannot filter this part of electromagnetic interference. The application environment of the power supply varies greatly, All power supply design filters are designed to address their own interference as the primary consideration. At the same time, the filter attenuation characteristics and spectral characteristics should be reserved as much as possible with maximum margin, but it is not possible to be compatible with all application scenarios; So this requires our overall machine designers to design the power front-end according to the application circuit recommended by the power supply manufacturer.
