Schematic diagram of switching power supply transformer shielding layer to suppress common mode EMI

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

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Overview:
Electromagnetic Compatibility (EMC) refers to the ability of an electronic device or system to function properly in an electromagnetic environment without posing unacceptable electromagnetic disturbances to anything in the environment. It includes both electromagnetic interference (EMI) and electromagnetic sensitivity (EMS). Due to the high di/dt and du/dt in the switching power supply, all topological switching power supplies have electromagnetic interference problems. At present, the technical means for overcoming electromagnetic interference mainly include: setting passive or active filters at the input and output ends of the power supply, setting a shielded casing and grounding, adopting soft switching technology and frequency conversion control technology.
In switching power supplies, the root cause of EMI is the sharp change in the high frequency of current and voltage. It conducts EMI through the conduction of wires and the coupling of inductors and capacitors. At the same time, changes in current and voltage must be accompanied by changes in the magnetic field and electric field, thus causing radiated EMI. This paper focuses on the mechanism of common mode EMI generation in switching power supply transformers. Based on this, the suppression effect of different shielding layer setting methods on common mode EMI in switching power supply transformers is expounded.
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