0 Preface:
With the rapid development of electronic technology, electronic devices are also moving toward functional integration and miniaturization, which brings us a lot of convenience, but the electromagnetic coupling between various electronic devices has become an engineer's face. The main problem. The harm of electronic environmental pollution is no less than that of traditional environmental pollution. Electromagnetic pollution has also been put on the agenda as part of environmental pollution. During normal operation, electronic equipment will withstand various electromagnetic interferences, including mutual interference of its own internal devices, as well as interference from other electronic devices around it, and electromagnetic interference to other surrounding electronic devices. The requirements for electronic equipment in different application environments (home, industrial control, power) are very different. In this respect, reference can be made to the general standard IEC/EN61000-6 series or the corresponding industry requirements.
This kind of electromagnetic interference mainly includes two aspects in the transmission path: one is transmission along the wire harness, which mainly includes transmission along the power port and transmission of the signal port; on the other hand, the transmission is mainly along the space.
1 electromagnetic interference:
The power supply must meet the corresponding minimum emission energy requirements in its application environment, otherwise it will interfere with the surrounding environment equipment. The standard IEC/EN61000-6 is divided into industrial environment equipment requirements and residential areas and commercials according to the general type requirements. The emission requirements for district and light industrial environments; for general-purpose products such as power supplies, the electromagnetic interference location at the beginning of the design will be designed in accordance with IEC/EN61000-6-3 or IEC/EN61000-6-4 unless it is a special model.
With the continuous miniaturization of the power supply, the power density continues to increase, and the design of electromagnetic interference for the power supply itself is constantly increasing. MORNSUN currently has not only built-in filters for all AC-DCs, but also for transformer shielding. Power device noise absorption has invested a large amount of design cost to meet the commitment requirements; R2 generation low-power DC-DC products are all designed with six-sided shielding structure to meet the industry CLASS A of EN55022/CISPR 22, EN55011/CISPR 11 Requirements, in line with the level requirements of the basic industry.
Although the power supply itself has invested a lot of design costs and meets the requirements of various indicators, but the power supply in the market is still inevitably subject to electromagnetic interference exceeding the standard; at this time, many design engineers will consider the root cause of the problem In the power supply, this aspect of the understanding is actually a misunderstanding, because the electromagnetic interference conducted disturbance test project, mainly for the power port, then the power port becomes his transmission path, all electromagnetic interference will be reached through the power port Measuring equipment, but the electromagnetic interference detected by the testing equipment, in addition to the power supply itself, the main part also includes the electromagnetic interference generated by other parts of the whole machine, and the electromagnetic interference generated by the resonance of the internal parasitic parameters of the equipment. It will be coupled to the test equipment through the power port. The internal filter of the power supply cannot be used to filter this part of the electromagnetic interference. The power supply application environment is very different. All the power supply design filters are mainly considered to solve their own interference. Filter attenuation Sex and spectrum characteristics should reserve the largest margin as much as possible, but it is not compatible with all applications; then this requires our designers to design the power supply front end, must be designed according to the application circuit recommended by the power supply manufacturer, for example : The problem of EMI exceeding the standard during the application of LH15 product (see the figure below).
The above picture shows the results of the conducted disturbance test of the MORNSUN power supply LH15-10B05. This result complies with the CLASS B requirements of EN55022/CISPR22, and the margin is very sufficient.
The above picture shows that the power supply of MORNSUN power supply LH15-10B05 is applied to a certain brand of products, the whole machine tests the conducted disturbance results, this result can not meet the CLASS B requirements of EN55022/CISPR22, even CLASS A can not meet the requirements, let alone design margin.
Therefore, even if the internal electromagnetic interference design level is higher, the application part must be left in the application process. The specific parameters can refer to the specification of the specific product. MORNSUN's power products will have an application circuit column in the specification, which will describe the indicators on the basis of the application circuit in great detail.
2 electromagnetic immunity:
In addition to complying with the electromagnetic interference requirements mentioned above, the power supply must also meet the immunity requirements of the corresponding application environment. If the minimum requirements of the environment cannot be met, it will be affected by electromagnetic interference generated by other surrounding equipment, causing damage. The output is unstable and abnormal, which ultimately affects the normal operation of the whole machine.
For the general-purpose products of power supply, there is no specific standard that requires the anti-interference performance to reach a certain level. When applying to a specific industry, it refers to the industry standard; but in the initial stage of design, there is no specific industry, only reference. The specific requirements of the general standard IEC/EN61000-6, the standard IEC/EN61000-6-1/2 are divided into industrial environment equipment immunity requirements and immunity requirements in residential areas, commercial areas and light industrial environments. The MORNSUN power AC-DC part is designed according to the most stringent grade of industrial type products, and the design margin is very sufficient. At present, this type of power supply promises four-level index 2KV (differential touch) / 4KV (common mode) Protective products, the internal design of the port protection varistor is using 14D specifications (see the figure below)
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